diff --git a/contrib/llvm-project/clang/include/clang/Sema/Sema.h b/contrib/llvm-project/clang/include/clang/Sema/Sema.h
index 3752a23faa85..28a5f17d0dd5 100644
--- a/contrib/llvm-project/clang/include/clang/Sema/Sema.h
+++ b/contrib/llvm-project/clang/include/clang/Sema/Sema.h
@@ -1,14109 +1,14119 @@
 //===--- Sema.h - Semantic Analysis & AST Building --------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // This file defines the Sema class, which performs semantic analysis and
 // builds ASTs.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CLANG_SEMA_SEMA_H
 #define LLVM_CLANG_SEMA_SEMA_H
 
 #include "clang/AST/ASTConcept.h"
 #include "clang/AST/ASTFwd.h"
 #include "clang/AST/Attr.h"
 #include "clang/AST/Availability.h"
 #include "clang/AST/ComparisonCategories.h"
 #include "clang/AST/DeclTemplate.h"
 #include "clang/AST/DeclarationName.h"
 #include "clang/AST/Expr.h"
 #include "clang/AST/ExprCXX.h"
 #include "clang/AST/ExprConcepts.h"
 #include "clang/AST/ExprObjC.h"
 #include "clang/AST/ExprOpenMP.h"
 #include "clang/AST/ExternalASTSource.h"
 #include "clang/AST/LocInfoType.h"
 #include "clang/AST/MangleNumberingContext.h"
 #include "clang/AST/NSAPI.h"
 #include "clang/AST/PrettyPrinter.h"
 #include "clang/AST/StmtCXX.h"
 #include "clang/AST/StmtOpenMP.h"
 #include "clang/AST/TypeLoc.h"
 #include "clang/AST/TypeOrdering.h"
 #include "clang/Basic/BitmaskEnum.h"
 #include "clang/Basic/Builtins.h"
 #include "clang/Basic/DarwinSDKInfo.h"
 #include "clang/Basic/ExpressionTraits.h"
 #include "clang/Basic/Module.h"
 #include "clang/Basic/OpenCLOptions.h"
 #include "clang/Basic/OpenMPKinds.h"
 #include "clang/Basic/PragmaKinds.h"
 #include "clang/Basic/Specifiers.h"
 #include "clang/Basic/TemplateKinds.h"
 #include "clang/Basic/TypeTraits.h"
 #include "clang/Sema/AnalysisBasedWarnings.h"
 #include "clang/Sema/CleanupInfo.h"
 #include "clang/Sema/DeclSpec.h"
 #include "clang/Sema/ExternalSemaSource.h"
 #include "clang/Sema/IdentifierResolver.h"
 #include "clang/Sema/ObjCMethodList.h"
 #include "clang/Sema/Ownership.h"
 #include "clang/Sema/Scope.h"
 #include "clang/Sema/SemaConcept.h"
 #include "clang/Sema/TypoCorrection.h"
 #include "clang/Sema/Weak.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/SmallBitVector.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/TinyPtrVector.h"
 #include "llvm/Frontend/OpenMP/OMPConstants.h"
 #include <deque>
 #include <memory>
 #include <optional>
 #include <string>
 #include <tuple>
 #include <vector>
 
 namespace llvm {
   class APSInt;
   template <typename ValueT, typename ValueInfoT> class DenseSet;
   class SmallBitVector;
   struct InlineAsmIdentifierInfo;
 }
 
 namespace clang {
   class ADLResult;
   class ASTConsumer;
   class ASTContext;
   class ASTMutationListener;
   class ASTReader;
   class ASTWriter;
   class ArrayType;
   class ParsedAttr;
   class BindingDecl;
   class BlockDecl;
   class CapturedDecl;
   class CXXBasePath;
   class CXXBasePaths;
   class CXXBindTemporaryExpr;
   typedef SmallVector<CXXBaseSpecifier*, 4> CXXCastPath;
   class CXXConstructorDecl;
   class CXXConversionDecl;
   class CXXDeleteExpr;
   class CXXDestructorDecl;
   class CXXFieldCollector;
   class CXXMemberCallExpr;
   class CXXMethodDecl;
   class CXXScopeSpec;
   class CXXTemporary;
   class CXXTryStmt;
   class CallExpr;
   class ClassTemplateDecl;
   class ClassTemplatePartialSpecializationDecl;
   class ClassTemplateSpecializationDecl;
   class VarTemplatePartialSpecializationDecl;
   class CodeCompleteConsumer;
   class CodeCompletionAllocator;
   class CodeCompletionTUInfo;
   class CodeCompletionResult;
   class CoroutineBodyStmt;
   class Decl;
   class DeclAccessPair;
   class DeclContext;
   class DeclRefExpr;
   class DeclaratorDecl;
   class DeducedTemplateArgument;
   class DependentDiagnostic;
   class DesignatedInitExpr;
   class Designation;
   class EnableIfAttr;
   class EnumConstantDecl;
   class Expr;
   class ExtVectorType;
   class FormatAttr;
   class FriendDecl;
   class FunctionDecl;
   class FunctionProtoType;
   class FunctionTemplateDecl;
   class ImplicitConversionSequence;
   typedef MutableArrayRef<ImplicitConversionSequence> ConversionSequenceList;
   class InitListExpr;
   class InitializationKind;
   class InitializationSequence;
   class InitializedEntity;
   class IntegerLiteral;
   class LabelStmt;
   class LambdaExpr;
   class LangOptions;
   class LocalInstantiationScope;
   class LookupResult;
   class MacroInfo;
   typedef ArrayRef<std::pair<IdentifierInfo *, SourceLocation>> ModuleIdPath;
   class ModuleLoader;
   class MultiLevelTemplateArgumentList;
   class NamedDecl;
   class ObjCCategoryDecl;
   class ObjCCategoryImplDecl;
   class ObjCCompatibleAliasDecl;
   class ObjCContainerDecl;
   class ObjCImplDecl;
   class ObjCImplementationDecl;
   class ObjCInterfaceDecl;
   class ObjCIvarDecl;
   template <class T> class ObjCList;
   class ObjCMessageExpr;
   class ObjCMethodDecl;
   class ObjCPropertyDecl;
   class ObjCProtocolDecl;
   class OMPThreadPrivateDecl;
   class OMPRequiresDecl;
   class OMPDeclareReductionDecl;
   class OMPDeclareSimdDecl;
   class OMPClause;
   struct OMPVarListLocTy;
   struct OverloadCandidate;
   enum class OverloadCandidateParamOrder : char;
   enum OverloadCandidateRewriteKind : unsigned;
   class OverloadCandidateSet;
   class OverloadExpr;
   class ParenListExpr;
   class ParmVarDecl;
   class Preprocessor;
   class PseudoDestructorTypeStorage;
   class PseudoObjectExpr;
   class QualType;
   class StandardConversionSequence;
   class Stmt;
   class StringLiteral;
   class SwitchStmt;
   class TemplateArgument;
   class TemplateArgumentList;
   class TemplateArgumentLoc;
   class TemplateDecl;
   class TemplateInstantiationCallback;
   class TemplateParameterList;
   class TemplatePartialOrderingContext;
   class TemplateTemplateParmDecl;
   class Token;
   class TypeAliasDecl;
   class TypedefDecl;
   class TypedefNameDecl;
   class TypeLoc;
   class TypoCorrectionConsumer;
   class UnqualifiedId;
   class UnresolvedLookupExpr;
   class UnresolvedMemberExpr;
   class UnresolvedSetImpl;
   class UnresolvedSetIterator;
   class UsingDecl;
   class UsingShadowDecl;
   class ValueDecl;
   class VarDecl;
   class VarTemplateSpecializationDecl;
   class VisibilityAttr;
   class VisibleDeclConsumer;
   class IndirectFieldDecl;
   struct DeductionFailureInfo;
   class TemplateSpecCandidateSet;
 
 namespace sema {
   class AccessedEntity;
   class BlockScopeInfo;
   class Capture;
   class CapturedRegionScopeInfo;
   class CapturingScopeInfo;
   class CompoundScopeInfo;
   class DelayedDiagnostic;
   class DelayedDiagnosticPool;
   class FunctionScopeInfo;
   class LambdaScopeInfo;
   class PossiblyUnreachableDiag;
   class RISCVIntrinsicManager;
   class SemaPPCallbacks;
   class TemplateDeductionInfo;
 }
 
 namespace threadSafety {
   class BeforeSet;
   void threadSafetyCleanup(BeforeSet* Cache);
 }
 
 // FIXME: No way to easily map from TemplateTypeParmTypes to
 // TemplateTypeParmDecls, so we have this horrible PointerUnion.
 typedef std::pair<llvm::PointerUnion<const TemplateTypeParmType *, NamedDecl *>,
                   SourceLocation>
     UnexpandedParameterPack;
 
 /// Describes whether we've seen any nullability information for the given
 /// file.
 struct FileNullability {
   /// The first pointer declarator (of any pointer kind) in the file that does
   /// not have a corresponding nullability annotation.
   SourceLocation PointerLoc;
 
   /// The end location for the first pointer declarator in the file. Used for
   /// placing fix-its.
   SourceLocation PointerEndLoc;
 
   /// Which kind of pointer declarator we saw.
   uint8_t PointerKind;
 
   /// Whether we saw any type nullability annotations in the given file.
   bool SawTypeNullability = false;
 };
 
 /// A mapping from file IDs to a record of whether we've seen nullability
 /// information in that file.
 class FileNullabilityMap {
   /// A mapping from file IDs to the nullability information for each file ID.
   llvm::DenseMap<FileID, FileNullability> Map;
 
   /// A single-element cache based on the file ID.
   struct {
     FileID File;
     FileNullability Nullability;
   } Cache;
 
 public:
   FileNullability &operator[](FileID file) {
     // Check the single-element cache.
     if (file == Cache.File)
       return Cache.Nullability;
 
     // It's not in the single-element cache; flush the cache if we have one.
     if (!Cache.File.isInvalid()) {
       Map[Cache.File] = Cache.Nullability;
     }
 
     // Pull this entry into the cache.
     Cache.File = file;
     Cache.Nullability = Map[file];
     return Cache.Nullability;
   }
 };
 
 /// Tracks expected type during expression parsing, for use in code completion.
 /// The type is tied to a particular token, all functions that update or consume
 /// the type take a start location of the token they are looking at as a
 /// parameter. This avoids updating the type on hot paths in the parser.
 class PreferredTypeBuilder {
 public:
   PreferredTypeBuilder(bool Enabled) : Enabled(Enabled) {}
 
   void enterCondition(Sema &S, SourceLocation Tok);
   void enterReturn(Sema &S, SourceLocation Tok);
   void enterVariableInit(SourceLocation Tok, Decl *D);
   /// Handles e.g. BaseType{ .D = Tok...
   void enterDesignatedInitializer(SourceLocation Tok, QualType BaseType,
                                   const Designation &D);
   /// Computing a type for the function argument may require running
   /// overloading, so we postpone its computation until it is actually needed.
   ///
   /// Clients should be very careful when using this function, as it stores a
   /// function_ref, clients should make sure all calls to get() with the same
   /// location happen while function_ref is alive.
   ///
   /// The callback should also emit signature help as a side-effect, but only
   /// if the completion point has been reached.
   void enterFunctionArgument(SourceLocation Tok,
                              llvm::function_ref<QualType()> ComputeType);
 
   void enterParenExpr(SourceLocation Tok, SourceLocation LParLoc);
   void enterUnary(Sema &S, SourceLocation Tok, tok::TokenKind OpKind,
                   SourceLocation OpLoc);
   void enterBinary(Sema &S, SourceLocation Tok, Expr *LHS, tok::TokenKind Op);
   void enterMemAccess(Sema &S, SourceLocation Tok, Expr *Base);
   void enterSubscript(Sema &S, SourceLocation Tok, Expr *LHS);
   /// Handles all type casts, including C-style cast, C++ casts, etc.
   void enterTypeCast(SourceLocation Tok, QualType CastType);
 
   /// Get the expected type associated with this location, if any.
   ///
   /// If the location is a function argument, determining the expected type
   /// involves considering all function overloads and the arguments so far.
   /// In this case, signature help for these function overloads will be reported
   /// as a side-effect (only if the completion point has been reached).
   QualType get(SourceLocation Tok) const {
     if (!Enabled || Tok != ExpectedLoc)
       return QualType();
     if (!Type.isNull())
       return Type;
     if (ComputeType)
       return ComputeType();
     return QualType();
   }
 
 private:
   bool Enabled;
   /// Start position of a token for which we store expected type.
   SourceLocation ExpectedLoc;
   /// Expected type for a token starting at ExpectedLoc.
   QualType Type;
   /// A function to compute expected type at ExpectedLoc. It is only considered
   /// if Type is null.
   llvm::function_ref<QualType()> ComputeType;
 };
 
 /// Sema - This implements semantic analysis and AST building for C.
 class Sema final {
   Sema(const Sema &) = delete;
   void operator=(const Sema &) = delete;
 
   ///Source of additional semantic information.
   IntrusiveRefCntPtr<ExternalSemaSource> ExternalSource;
 
   static bool mightHaveNonExternalLinkage(const DeclaratorDecl *FD);
 
   /// Determine whether two declarations should be linked together, given that
   /// the old declaration might not be visible and the new declaration might
   /// not have external linkage.
   bool shouldLinkPossiblyHiddenDecl(const NamedDecl *Old,
                                     const NamedDecl *New) {
     if (isVisible(Old))
      return true;
     // See comment in below overload for why it's safe to compute the linkage
     // of the new declaration here.
     if (New->isExternallyDeclarable()) {
       assert(Old->isExternallyDeclarable() &&
              "should not have found a non-externally-declarable previous decl");
       return true;
     }
     return false;
   }
   bool shouldLinkPossiblyHiddenDecl(LookupResult &Old, const NamedDecl *New);
 
   void setupImplicitSpecialMemberType(CXXMethodDecl *SpecialMem,
                                       QualType ResultTy,
                                       ArrayRef<QualType> Args);
 
 public:
   /// The maximum alignment, same as in llvm::Value. We duplicate them here
   /// because that allows us not to duplicate the constants in clang code,
   /// which we must to since we can't directly use the llvm constants.
   /// The value is verified against llvm here: lib/CodeGen/CGDecl.cpp
   ///
   /// This is the greatest alignment value supported by load, store, and alloca
   /// instructions, and global values.
   static const unsigned MaxAlignmentExponent = 32;
   static const uint64_t MaximumAlignment = 1ull << MaxAlignmentExponent;
 
   typedef OpaquePtr<DeclGroupRef> DeclGroupPtrTy;
   typedef OpaquePtr<TemplateName> TemplateTy;
   typedef OpaquePtr<QualType> TypeTy;
 
   OpenCLOptions OpenCLFeatures;
   FPOptions CurFPFeatures;
 
   const LangOptions &LangOpts;
   Preprocessor &PP;
   ASTContext &Context;
   ASTConsumer &Consumer;
   DiagnosticsEngine &Diags;
   SourceManager &SourceMgr;
 
   /// Flag indicating whether or not to collect detailed statistics.
   bool CollectStats;
 
   /// Code-completion consumer.
   CodeCompleteConsumer *CodeCompleter;
 
   /// CurContext - This is the current declaration context of parsing.
   DeclContext *CurContext;
 
   /// Generally null except when we temporarily switch decl contexts,
   /// like in \see ActOnObjCTemporaryExitContainerContext.
   DeclContext *OriginalLexicalContext;
 
   /// VAListTagName - The declaration name corresponding to __va_list_tag.
   /// This is used as part of a hack to omit that class from ADL results.
   DeclarationName VAListTagName;
 
   bool MSStructPragmaOn; // True when \#pragma ms_struct on
 
   /// Controls member pointer representation format under the MS ABI.
   LangOptions::PragmaMSPointersToMembersKind
       MSPointerToMemberRepresentationMethod;
 
   /// Stack of active SEH __finally scopes.  Can be empty.
   SmallVector<Scope*, 2> CurrentSEHFinally;
 
   /// Source location for newly created implicit MSInheritanceAttrs
   SourceLocation ImplicitMSInheritanceAttrLoc;
 
   /// Holds TypoExprs that are created from `createDelayedTypo`. This is used by
   /// `TransformTypos` in order to keep track of any TypoExprs that are created
   /// recursively during typo correction and wipe them away if the correction
   /// fails.
   llvm::SmallVector<TypoExpr *, 2> TypoExprs;
 
   /// pragma clang section kind
   enum PragmaClangSectionKind {
     PCSK_Invalid      = 0,
     PCSK_BSS          = 1,
     PCSK_Data         = 2,
     PCSK_Rodata       = 3,
     PCSK_Text         = 4,
     PCSK_Relro        = 5
    };
 
   enum PragmaClangSectionAction {
     PCSA_Set     = 0,
     PCSA_Clear   = 1
   };
 
   struct PragmaClangSection {
     std::string SectionName;
     bool Valid = false;
     SourceLocation PragmaLocation;
   };
 
    PragmaClangSection PragmaClangBSSSection;
    PragmaClangSection PragmaClangDataSection;
    PragmaClangSection PragmaClangRodataSection;
    PragmaClangSection PragmaClangRelroSection;
    PragmaClangSection PragmaClangTextSection;
 
   enum PragmaMsStackAction {
     PSK_Reset     = 0x0,                // #pragma ()
     PSK_Set       = 0x1,                // #pragma (value)
     PSK_Push      = 0x2,                // #pragma (push[, id])
     PSK_Pop       = 0x4,                // #pragma (pop[, id])
     PSK_Show      = 0x8,                // #pragma (show) -- only for "pack"!
     PSK_Push_Set  = PSK_Push | PSK_Set, // #pragma (push[, id], value)
     PSK_Pop_Set   = PSK_Pop | PSK_Set,  // #pragma (pop[, id], value)
   };
 
   struct PragmaPackInfo {
     PragmaMsStackAction Action;
     StringRef SlotLabel;
     Token Alignment;
   };
 
   // #pragma pack and align.
   class AlignPackInfo {
   public:
     // `Native` represents default align mode, which may vary based on the
     // platform.
     enum Mode : unsigned char { Native, Natural, Packed, Mac68k };
 
     // #pragma pack info constructor
     AlignPackInfo(AlignPackInfo::Mode M, unsigned Num, bool IsXL)
         : PackAttr(true), AlignMode(M), PackNumber(Num), XLStack(IsXL) {
       assert(Num == PackNumber && "The pack number has been truncated.");
     }
 
     // #pragma align info constructor
     AlignPackInfo(AlignPackInfo::Mode M, bool IsXL)
         : PackAttr(false), AlignMode(M),
           PackNumber(M == Packed ? 1 : UninitPackVal), XLStack(IsXL) {}
 
     explicit AlignPackInfo(bool IsXL) : AlignPackInfo(Native, IsXL) {}
 
     AlignPackInfo() : AlignPackInfo(Native, false) {}
 
     // When a AlignPackInfo itself cannot be used, this returns an 32-bit
     // integer encoding for it. This should only be passed to
     // AlignPackInfo::getFromRawEncoding, it should not be inspected directly.
     static uint32_t getRawEncoding(const AlignPackInfo &Info) {
       std::uint32_t Encoding{};
       if (Info.IsXLStack())
         Encoding |= IsXLMask;
 
       Encoding |= static_cast<uint32_t>(Info.getAlignMode()) << 1;
 
       if (Info.IsPackAttr())
         Encoding |= PackAttrMask;
 
       Encoding |= static_cast<uint32_t>(Info.getPackNumber()) << 4;
 
       return Encoding;
     }
 
     static AlignPackInfo getFromRawEncoding(unsigned Encoding) {
       bool IsXL = static_cast<bool>(Encoding & IsXLMask);
       AlignPackInfo::Mode M =
           static_cast<AlignPackInfo::Mode>((Encoding & AlignModeMask) >> 1);
       int PackNumber = (Encoding & PackNumMask) >> 4;
 
       if (Encoding & PackAttrMask)
         return AlignPackInfo(M, PackNumber, IsXL);
 
       return AlignPackInfo(M, IsXL);
     }
 
     bool IsPackAttr() const { return PackAttr; }
 
     bool IsAlignAttr() const { return !PackAttr; }
 
     Mode getAlignMode() const { return AlignMode; }
 
     unsigned getPackNumber() const { return PackNumber; }
 
     bool IsPackSet() const {
       // #pragma align, #pragma pack(), and #pragma pack(0) do not set the pack
       // attriute on a decl.
       return PackNumber != UninitPackVal && PackNumber != 0;
     }
 
     bool IsXLStack() const { return XLStack; }
 
     bool operator==(const AlignPackInfo &Info) const {
       return std::tie(AlignMode, PackNumber, PackAttr, XLStack) ==
              std::tie(Info.AlignMode, Info.PackNumber, Info.PackAttr,
                       Info.XLStack);
     }
 
     bool operator!=(const AlignPackInfo &Info) const {
       return !(*this == Info);
     }
 
   private:
     /// \brief True if this is a pragma pack attribute,
     ///         not a pragma align attribute.
     bool PackAttr;
 
     /// \brief The alignment mode that is in effect.
     Mode AlignMode;
 
     /// \brief The pack number of the stack.
     unsigned char PackNumber;
 
     /// \brief True if it is a XL #pragma align/pack stack.
     bool XLStack;
 
     /// \brief Uninitialized pack value.
     static constexpr unsigned char UninitPackVal = -1;
 
     // Masks to encode and decode an AlignPackInfo.
     static constexpr uint32_t IsXLMask{0x0000'0001};
     static constexpr uint32_t AlignModeMask{0x0000'0006};
     static constexpr uint32_t PackAttrMask{0x00000'0008};
     static constexpr uint32_t PackNumMask{0x0000'01F0};
   };
 
   template<typename ValueType>
   struct PragmaStack {
     struct Slot {
       llvm::StringRef StackSlotLabel;
       ValueType Value;
       SourceLocation PragmaLocation;
       SourceLocation PragmaPushLocation;
       Slot(llvm::StringRef StackSlotLabel, ValueType Value,
            SourceLocation PragmaLocation, SourceLocation PragmaPushLocation)
           : StackSlotLabel(StackSlotLabel), Value(Value),
             PragmaLocation(PragmaLocation),
             PragmaPushLocation(PragmaPushLocation) {}
     };
 
     void Act(SourceLocation PragmaLocation, PragmaMsStackAction Action,
              llvm::StringRef StackSlotLabel, ValueType Value) {
       if (Action == PSK_Reset) {
         CurrentValue = DefaultValue;
         CurrentPragmaLocation = PragmaLocation;
         return;
       }
       if (Action & PSK_Push)
         Stack.emplace_back(StackSlotLabel, CurrentValue, CurrentPragmaLocation,
                            PragmaLocation);
       else if (Action & PSK_Pop) {
         if (!StackSlotLabel.empty()) {
           // If we've got a label, try to find it and jump there.
           auto I = llvm::find_if(llvm::reverse(Stack), [&](const Slot &x) {
             return x.StackSlotLabel == StackSlotLabel;
           });
           // If we found the label so pop from there.
           if (I != Stack.rend()) {
             CurrentValue = I->Value;
             CurrentPragmaLocation = I->PragmaLocation;
             Stack.erase(std::prev(I.base()), Stack.end());
           }
         } else if (!Stack.empty()) {
           // We do not have a label, just pop the last entry.
           CurrentValue = Stack.back().Value;
           CurrentPragmaLocation = Stack.back().PragmaLocation;
           Stack.pop_back();
         }
       }
       if (Action & PSK_Set) {
         CurrentValue = Value;
         CurrentPragmaLocation = PragmaLocation;
       }
     }
 
     // MSVC seems to add artificial slots to #pragma stacks on entering a C++
     // method body to restore the stacks on exit, so it works like this:
     //
     //   struct S {
     //     #pragma <name>(push, InternalPragmaSlot, <current_pragma_value>)
     //     void Method {}
     //     #pragma <name>(pop, InternalPragmaSlot)
     //   };
     //
     // It works even with #pragma vtordisp, although MSVC doesn't support
     //   #pragma vtordisp(push [, id], n)
     // syntax.
     //
     // Push / pop a named sentinel slot.
     void SentinelAction(PragmaMsStackAction Action, StringRef Label) {
       assert((Action == PSK_Push || Action == PSK_Pop) &&
              "Can only push / pop #pragma stack sentinels!");
       Act(CurrentPragmaLocation, Action, Label, CurrentValue);
     }
 
     // Constructors.
     explicit PragmaStack(const ValueType &Default)
         : DefaultValue(Default), CurrentValue(Default) {}
 
     bool hasValue() const { return CurrentValue != DefaultValue; }
 
     SmallVector<Slot, 2> Stack;
     ValueType DefaultValue; // Value used for PSK_Reset action.
     ValueType CurrentValue;
     SourceLocation CurrentPragmaLocation;
   };
   // FIXME: We should serialize / deserialize these if they occur in a PCH (but
   // we shouldn't do so if they're in a module).
 
   /// Whether to insert vtordisps prior to virtual bases in the Microsoft
   /// C++ ABI.  Possible values are 0, 1, and 2, which mean:
   ///
   /// 0: Suppress all vtordisps
   /// 1: Insert vtordisps in the presence of vbase overrides and non-trivial
   ///    structors
   /// 2: Always insert vtordisps to support RTTI on partially constructed
   ///    objects
   PragmaStack<MSVtorDispMode> VtorDispStack;
   PragmaStack<AlignPackInfo> AlignPackStack;
   // The current #pragma align/pack values and locations at each #include.
   struct AlignPackIncludeState {
     AlignPackInfo CurrentValue;
     SourceLocation CurrentPragmaLocation;
     bool HasNonDefaultValue, ShouldWarnOnInclude;
   };
   SmallVector<AlignPackIncludeState, 8> AlignPackIncludeStack;
   // Segment #pragmas.
   PragmaStack<StringLiteral *> DataSegStack;
   PragmaStack<StringLiteral *> BSSSegStack;
   PragmaStack<StringLiteral *> ConstSegStack;
   PragmaStack<StringLiteral *> CodeSegStack;
 
   // #pragma strict_gs_check.
   PragmaStack<bool> StrictGuardStackCheckStack;
 
   // This stack tracks the current state of Sema.CurFPFeatures.
   PragmaStack<FPOptionsOverride> FpPragmaStack;
   FPOptionsOverride CurFPFeatureOverrides() {
     FPOptionsOverride result;
     if (!FpPragmaStack.hasValue()) {
       result = FPOptionsOverride();
     } else {
       result = FpPragmaStack.CurrentValue;
     }
     return result;
   }
 
   // Saves the current floating-point pragma stack and clear it in this Sema.
   class FpPragmaStackSaveRAII {
   public:
     FpPragmaStackSaveRAII(Sema &S)
         : S(S), SavedStack(std::move(S.FpPragmaStack)) {
       S.FpPragmaStack.Stack.clear();
     }
     ~FpPragmaStackSaveRAII() { S.FpPragmaStack = std::move(SavedStack); }
 
   private:
     Sema &S;
     PragmaStack<FPOptionsOverride> SavedStack;
   };
 
   void resetFPOptions(FPOptions FPO) {
     CurFPFeatures = FPO;
     FpPragmaStack.CurrentValue = FPO.getChangesFrom(FPOptions(LangOpts));
   }
 
   // RAII object to push / pop sentinel slots for all MS #pragma stacks.
   // Actions should be performed only if we enter / exit a C++ method body.
   class PragmaStackSentinelRAII {
   public:
     PragmaStackSentinelRAII(Sema &S, StringRef SlotLabel, bool ShouldAct);
     ~PragmaStackSentinelRAII();
 
   private:
     Sema &S;
     StringRef SlotLabel;
     bool ShouldAct;
   };
 
   /// A mapping that describes the nullability we've seen in each header file.
   FileNullabilityMap NullabilityMap;
 
   /// Last section used with #pragma init_seg.
   StringLiteral *CurInitSeg;
   SourceLocation CurInitSegLoc;
 
   /// Sections used with #pragma alloc_text.
   llvm::StringMap<std::tuple<StringRef, SourceLocation>> FunctionToSectionMap;
 
   /// VisContext - Manages the stack for \#pragma GCC visibility.
   void *VisContext; // Really a "PragmaVisStack*"
 
   /// This an attribute introduced by \#pragma clang attribute.
   struct PragmaAttributeEntry {
     SourceLocation Loc;
     ParsedAttr *Attribute;
     SmallVector<attr::SubjectMatchRule, 4> MatchRules;
     bool IsUsed;
   };
 
   /// A push'd group of PragmaAttributeEntries.
   struct PragmaAttributeGroup {
     /// The location of the push attribute.
     SourceLocation Loc;
     /// The namespace of this push group.
     const IdentifierInfo *Namespace;
     SmallVector<PragmaAttributeEntry, 2> Entries;
   };
 
   SmallVector<PragmaAttributeGroup, 2> PragmaAttributeStack;
 
   /// The declaration that is currently receiving an attribute from the
   /// #pragma attribute stack.
   const Decl *PragmaAttributeCurrentTargetDecl;
 
   /// This represents the last location of a "#pragma clang optimize off"
   /// directive if such a directive has not been closed by an "on" yet. If
   /// optimizations are currently "on", this is set to an invalid location.
   SourceLocation OptimizeOffPragmaLocation;
 
   /// The "on" or "off" argument passed by \#pragma optimize, that denotes
   /// whether the optimizations in the list passed to the pragma should be
   /// turned off or on. This boolean is true by default because command line
   /// options are honored when `#pragma optimize("", on)`.
   /// (i.e. `ModifyFnAttributeMSPragmaOptimze()` does nothing)
   bool MSPragmaOptimizeIsOn = true;
 
   /// Set of no-builtin functions listed by \#pragma function.
   llvm::SmallSetVector<StringRef, 4> MSFunctionNoBuiltins;
 
   /// Flag indicating if Sema is building a recovery call expression.
   ///
   /// This flag is used to avoid building recovery call expressions
   /// if Sema is already doing so, which would cause infinite recursions.
   bool IsBuildingRecoveryCallExpr;
 
   /// Used to control the generation of ExprWithCleanups.
   CleanupInfo Cleanup;
 
   /// ExprCleanupObjects - This is the stack of objects requiring
   /// cleanup that are created by the current full expression.
   SmallVector<ExprWithCleanups::CleanupObject, 8> ExprCleanupObjects;
 
   /// Store a set of either DeclRefExprs or MemberExprs that contain a reference
   /// to a variable (constant) that may or may not be odr-used in this Expr, and
   /// we won't know until all lvalue-to-rvalue and discarded value conversions
   /// have been applied to all subexpressions of the enclosing full expression.
   /// This is cleared at the end of each full expression.
   using MaybeODRUseExprSet = llvm::SmallSetVector<Expr *, 4>;
   MaybeODRUseExprSet MaybeODRUseExprs;
 
   std::unique_ptr<sema::FunctionScopeInfo> CachedFunctionScope;
 
   /// Stack containing information about each of the nested
   /// function, block, and method scopes that are currently active.
   SmallVector<sema::FunctionScopeInfo *, 4> FunctionScopes;
 
   /// The index of the first FunctionScope that corresponds to the current
   /// context.
   unsigned FunctionScopesStart = 0;
 
   /// Track the number of currently active capturing scopes.
   unsigned CapturingFunctionScopes = 0;
 
   ArrayRef<sema::FunctionScopeInfo*> getFunctionScopes() const {
     return llvm::ArrayRef(FunctionScopes.begin() + FunctionScopesStart,
                           FunctionScopes.end());
   }
 
   /// Stack containing information needed when in C++2a an 'auto' is encountered
   /// in a function declaration parameter type specifier in order to invent a
   /// corresponding template parameter in the enclosing abbreviated function
   /// template. This information is also present in LambdaScopeInfo, stored in
   /// the FunctionScopes stack.
   SmallVector<InventedTemplateParameterInfo, 4> InventedParameterInfos;
 
   /// The index of the first InventedParameterInfo that refers to the current
   /// context.
   unsigned InventedParameterInfosStart = 0;
 
   ArrayRef<InventedTemplateParameterInfo> getInventedParameterInfos() const {
     return llvm::ArrayRef(InventedParameterInfos.begin() +
                               InventedParameterInfosStart,
                           InventedParameterInfos.end());
   }
 
   typedef LazyVector<TypedefNameDecl *, ExternalSemaSource,
                      &ExternalSemaSource::ReadExtVectorDecls, 2, 2>
     ExtVectorDeclsType;
 
   /// ExtVectorDecls - This is a list all the extended vector types. This allows
   /// us to associate a raw vector type with one of the ext_vector type names.
   /// This is only necessary for issuing pretty diagnostics.
   ExtVectorDeclsType ExtVectorDecls;
 
   /// FieldCollector - Collects CXXFieldDecls during parsing of C++ classes.
   std::unique_ptr<CXXFieldCollector> FieldCollector;
 
   typedef llvm::SmallSetVector<const NamedDecl *, 16> NamedDeclSetType;
 
   /// Set containing all declared private fields that are not used.
   NamedDeclSetType UnusedPrivateFields;
 
   /// Set containing all typedefs that are likely unused.
   llvm::SmallSetVector<const TypedefNameDecl *, 4>
       UnusedLocalTypedefNameCandidates;
 
   /// Delete-expressions to be analyzed at the end of translation unit
   ///
   /// This list contains class members, and locations of delete-expressions
   /// that could not be proven as to whether they mismatch with new-expression
   /// used in initializer of the field.
   typedef std::pair<SourceLocation, bool> DeleteExprLoc;
   typedef llvm::SmallVector<DeleteExprLoc, 4> DeleteLocs;
   llvm::MapVector<FieldDecl *, DeleteLocs> DeleteExprs;
 
   typedef llvm::SmallPtrSet<const CXXRecordDecl*, 8> RecordDeclSetTy;
 
   /// PureVirtualClassDiagSet - a set of class declarations which we have
   /// emitted a list of pure virtual functions. Used to prevent emitting the
   /// same list more than once.
   std::unique_ptr<RecordDeclSetTy> PureVirtualClassDiagSet;
 
   /// ParsingInitForAutoVars - a set of declarations with auto types for which
   /// we are currently parsing the initializer.
   llvm::SmallPtrSet<const Decl*, 4> ParsingInitForAutoVars;
 
   /// Look for a locally scoped extern "C" declaration by the given name.
   NamedDecl *findLocallyScopedExternCDecl(DeclarationName Name);
 
   typedef LazyVector<VarDecl *, ExternalSemaSource,
                      &ExternalSemaSource::ReadTentativeDefinitions, 2, 2>
     TentativeDefinitionsType;
 
   /// All the tentative definitions encountered in the TU.
   TentativeDefinitionsType TentativeDefinitions;
 
   /// All the external declarations encoutered and used in the TU.
   SmallVector<VarDecl *, 4> ExternalDeclarations;
 
   typedef LazyVector<const DeclaratorDecl *, ExternalSemaSource,
                      &ExternalSemaSource::ReadUnusedFileScopedDecls, 2, 2>
     UnusedFileScopedDeclsType;
 
   /// The set of file scoped decls seen so far that have not been used
   /// and must warn if not used. Only contains the first declaration.
   UnusedFileScopedDeclsType UnusedFileScopedDecls;
 
   typedef LazyVector<CXXConstructorDecl *, ExternalSemaSource,
                      &ExternalSemaSource::ReadDelegatingConstructors, 2, 2>
     DelegatingCtorDeclsType;
 
   /// All the delegating constructors seen so far in the file, used for
   /// cycle detection at the end of the TU.
   DelegatingCtorDeclsType DelegatingCtorDecls;
 
   /// All the overriding functions seen during a class definition
   /// that had their exception spec checks delayed, plus the overridden
   /// function.
   SmallVector<std::pair<const CXXMethodDecl*, const CXXMethodDecl*>, 2>
     DelayedOverridingExceptionSpecChecks;
 
   /// All the function redeclarations seen during a class definition that had
   /// their exception spec checks delayed, plus the prior declaration they
   /// should be checked against. Except during error recovery, the new decl
   /// should always be a friend declaration, as that's the only valid way to
   /// redeclare a special member before its class is complete.
   SmallVector<std::pair<FunctionDecl*, FunctionDecl*>, 2>
     DelayedEquivalentExceptionSpecChecks;
 
   typedef llvm::MapVector<const FunctionDecl *,
                           std::unique_ptr<LateParsedTemplate>>
       LateParsedTemplateMapT;
   LateParsedTemplateMapT LateParsedTemplateMap;
 
   /// Callback to the parser to parse templated functions when needed.
   typedef void LateTemplateParserCB(void *P, LateParsedTemplate &LPT);
   typedef void LateTemplateParserCleanupCB(void *P);
   LateTemplateParserCB *LateTemplateParser;
   LateTemplateParserCleanupCB *LateTemplateParserCleanup;
   void *OpaqueParser;
 
   void SetLateTemplateParser(LateTemplateParserCB *LTP,
                              LateTemplateParserCleanupCB *LTPCleanup,
                              void *P) {
     LateTemplateParser = LTP;
     LateTemplateParserCleanup = LTPCleanup;
     OpaqueParser = P;
   }
 
   class DelayedDiagnostics;
 
   class DelayedDiagnosticsState {
     sema::DelayedDiagnosticPool *SavedPool = nullptr;
     friend class Sema::DelayedDiagnostics;
   };
   typedef DelayedDiagnosticsState ParsingDeclState;
   typedef DelayedDiagnosticsState ProcessingContextState;
 
   /// A class which encapsulates the logic for delaying diagnostics
   /// during parsing and other processing.
   class DelayedDiagnostics {
     /// The current pool of diagnostics into which delayed
     /// diagnostics should go.
     sema::DelayedDiagnosticPool *CurPool = nullptr;
 
   public:
     DelayedDiagnostics() = default;
 
     /// Adds a delayed diagnostic.
     void add(const sema::DelayedDiagnostic &diag); // in DelayedDiagnostic.h
 
     /// Determines whether diagnostics should be delayed.
     bool shouldDelayDiagnostics() { return CurPool != nullptr; }
 
     /// Returns the current delayed-diagnostics pool.
     sema::DelayedDiagnosticPool *getCurrentPool() const {
       return CurPool;
     }
 
     /// Enter a new scope.  Access and deprecation diagnostics will be
     /// collected in this pool.
     DelayedDiagnosticsState push(sema::DelayedDiagnosticPool &pool) {
       DelayedDiagnosticsState state;
       state.SavedPool = CurPool;
       CurPool = &pool;
       return state;
     }
 
     /// Leave a delayed-diagnostic state that was previously pushed.
     /// Do not emit any of the diagnostics.  This is performed as part
     /// of the bookkeeping of popping a pool "properly".
     void popWithoutEmitting(DelayedDiagnosticsState state) {
       CurPool = state.SavedPool;
     }
 
     /// Enter a new scope where access and deprecation diagnostics are
     /// not delayed.
     DelayedDiagnosticsState pushUndelayed() {
       DelayedDiagnosticsState state;
       state.SavedPool = CurPool;
       CurPool = nullptr;
       return state;
     }
 
     /// Undo a previous pushUndelayed().
     void popUndelayed(DelayedDiagnosticsState state) {
       assert(CurPool == nullptr);
       CurPool = state.SavedPool;
     }
   } DelayedDiagnostics;
 
   /// A RAII object to temporarily push a declaration context.
   class ContextRAII {
   private:
     Sema &S;
     DeclContext *SavedContext;
     ProcessingContextState SavedContextState;
     QualType SavedCXXThisTypeOverride;
     unsigned SavedFunctionScopesStart;
     unsigned SavedInventedParameterInfosStart;
 
   public:
     ContextRAII(Sema &S, DeclContext *ContextToPush, bool NewThisContext = true)
       : S(S), SavedContext(S.CurContext),
         SavedContextState(S.DelayedDiagnostics.pushUndelayed()),
         SavedCXXThisTypeOverride(S.CXXThisTypeOverride),
         SavedFunctionScopesStart(S.FunctionScopesStart),
         SavedInventedParameterInfosStart(S.InventedParameterInfosStart)
     {
       assert(ContextToPush && "pushing null context");
       S.CurContext = ContextToPush;
       if (NewThisContext)
         S.CXXThisTypeOverride = QualType();
       // Any saved FunctionScopes do not refer to this context.
       S.FunctionScopesStart = S.FunctionScopes.size();
       S.InventedParameterInfosStart = S.InventedParameterInfos.size();
     }
 
     void pop() {
       if (!SavedContext) return;
       S.CurContext = SavedContext;
       S.DelayedDiagnostics.popUndelayed(SavedContextState);
       S.CXXThisTypeOverride = SavedCXXThisTypeOverride;
       S.FunctionScopesStart = SavedFunctionScopesStart;
       S.InventedParameterInfosStart = SavedInventedParameterInfosStart;
       SavedContext = nullptr;
     }
 
     ~ContextRAII() {
       pop();
     }
   };
 
   /// Whether the AST is currently being rebuilt to correct immediate
   /// invocations. Immediate invocation candidates and references to consteval
   /// functions aren't tracked when this is set.
   bool RebuildingImmediateInvocation = false;
 
   /// Used to change context to isConstantEvaluated without pushing a heavy
   /// ExpressionEvaluationContextRecord object.
   bool isConstantEvaluatedOverride;
 
   bool isConstantEvaluated() const {
     return ExprEvalContexts.back().isConstantEvaluated() ||
            isConstantEvaluatedOverride;
   }
 
   /// RAII object to handle the state changes required to synthesize
   /// a function body.
   class SynthesizedFunctionScope {
     Sema &S;
     Sema::ContextRAII SavedContext;
     bool PushedCodeSynthesisContext = false;
 
   public:
     SynthesizedFunctionScope(Sema &S, DeclContext *DC)
         : S(S), SavedContext(S, DC) {
       auto *FD = dyn_cast<FunctionDecl>(DC);
       S.PushFunctionScope();
       S.PushExpressionEvaluationContext(
           (FD && FD->isConsteval())
               ? ExpressionEvaluationContext::ImmediateFunctionContext
               : ExpressionEvaluationContext::PotentiallyEvaluated);
       if (FD) {
         FD->setWillHaveBody(true);
         S.ExprEvalContexts.back().InImmediateFunctionContext =
             FD->isImmediateFunction();
         S.ExprEvalContexts.back().InImmediateEscalatingFunctionContext =
             S.getLangOpts().CPlusPlus20 && FD->isImmediateEscalating();
       } else
         assert(isa<ObjCMethodDecl>(DC));
     }
 
     void addContextNote(SourceLocation UseLoc) {
       assert(!PushedCodeSynthesisContext);
 
       Sema::CodeSynthesisContext Ctx;
       Ctx.Kind = Sema::CodeSynthesisContext::DefiningSynthesizedFunction;
       Ctx.PointOfInstantiation = UseLoc;
       Ctx.Entity = cast<Decl>(S.CurContext);
       S.pushCodeSynthesisContext(Ctx);
 
       PushedCodeSynthesisContext = true;
     }
 
     ~SynthesizedFunctionScope() {
       if (PushedCodeSynthesisContext)
         S.popCodeSynthesisContext();
       if (auto *FD = dyn_cast<FunctionDecl>(S.CurContext)) {
         FD->setWillHaveBody(false);
         S.CheckImmediateEscalatingFunctionDefinition(FD, S.getCurFunction());
       }
       S.PopExpressionEvaluationContext();
       S.PopFunctionScopeInfo();
     }
   };
 
   /// WeakUndeclaredIdentifiers - Identifiers contained in \#pragma weak before
   /// declared. Rare. May alias another identifier, declared or undeclared.
   ///
   /// For aliases, the target identifier is used as a key for eventual
   /// processing when the target is declared. For the single-identifier form,
   /// the sole identifier is used as the key. Each entry is a `SetVector`
   /// (ordered by parse order) of aliases (identified by the alias name) in case
   /// of multiple aliases to the same undeclared identifier.
   llvm::MapVector<
       IdentifierInfo *,
       llvm::SetVector<
           WeakInfo, llvm::SmallVector<WeakInfo, 1u>,
           llvm::SmallDenseSet<WeakInfo, 2u, WeakInfo::DenseMapInfoByAliasOnly>>>
       WeakUndeclaredIdentifiers;
 
   /// ExtnameUndeclaredIdentifiers - Identifiers contained in
   /// \#pragma redefine_extname before declared.  Used in Solaris system headers
   /// to define functions that occur in multiple standards to call the version
   /// in the currently selected standard.
   llvm::DenseMap<IdentifierInfo*,AsmLabelAttr*> ExtnameUndeclaredIdentifiers;
 
 
   /// Load weak undeclared identifiers from the external source.
   void LoadExternalWeakUndeclaredIdentifiers();
 
   /// WeakTopLevelDecl - Translation-unit scoped declarations generated by
   /// \#pragma weak during processing of other Decls.
   /// I couldn't figure out a clean way to generate these in-line, so
   /// we store them here and handle separately -- which is a hack.
   /// It would be best to refactor this.
   SmallVector<Decl*,2> WeakTopLevelDecl;
 
   IdentifierResolver IdResolver;
 
   /// Translation Unit Scope - useful to Objective-C actions that need
   /// to lookup file scope declarations in the "ordinary" C decl namespace.
   /// For example, user-defined classes, built-in "id" type, etc.
   Scope *TUScope;
 
   /// The C++ "std" namespace, where the standard library resides.
   LazyDeclPtr StdNamespace;
 
   /// The C++ "std::bad_alloc" class, which is defined by the C++
   /// standard library.
   LazyDeclPtr StdBadAlloc;
 
   /// The C++ "std::align_val_t" enum class, which is defined by the C++
   /// standard library.
   LazyDeclPtr StdAlignValT;
 
   /// The C++ "std::initializer_list" template, which is defined in
   /// \<initializer_list>.
   ClassTemplateDecl *StdInitializerList;
 
   /// The C++ "std::coroutine_traits" template, which is defined in
   /// \<coroutine_traits>
   ClassTemplateDecl *StdCoroutineTraitsCache;
 
   /// The C++ "type_info" declaration, which is defined in \<typeinfo>.
   RecordDecl *CXXTypeInfoDecl;
 
   /// The C++ "std::source_location::__impl" struct, defined in
   /// \<source_location>.
   RecordDecl *StdSourceLocationImplDecl;
 
   /// Caches identifiers/selectors for NSFoundation APIs.
   std::unique_ptr<NSAPI> NSAPIObj;
 
   /// The declaration of the Objective-C NSNumber class.
   ObjCInterfaceDecl *NSNumberDecl;
 
   /// The declaration of the Objective-C NSValue class.
   ObjCInterfaceDecl *NSValueDecl;
 
   /// Pointer to NSNumber type (NSNumber *).
   QualType NSNumberPointer;
 
   /// Pointer to NSValue type (NSValue *).
   QualType NSValuePointer;
 
   /// The Objective-C NSNumber methods used to create NSNumber literals.
   ObjCMethodDecl *NSNumberLiteralMethods[NSAPI::NumNSNumberLiteralMethods];
 
   /// The declaration of the Objective-C NSString class.
   ObjCInterfaceDecl *NSStringDecl;
 
   /// Pointer to NSString type (NSString *).
   QualType NSStringPointer;
 
   /// The declaration of the stringWithUTF8String: method.
   ObjCMethodDecl *StringWithUTF8StringMethod;
 
   /// The declaration of the valueWithBytes:objCType: method.
   ObjCMethodDecl *ValueWithBytesObjCTypeMethod;
 
   /// The declaration of the Objective-C NSArray class.
   ObjCInterfaceDecl *NSArrayDecl;
 
   /// The declaration of the arrayWithObjects:count: method.
   ObjCMethodDecl *ArrayWithObjectsMethod;
 
   /// The declaration of the Objective-C NSDictionary class.
   ObjCInterfaceDecl *NSDictionaryDecl;
 
   /// The declaration of the dictionaryWithObjects:forKeys:count: method.
   ObjCMethodDecl *DictionaryWithObjectsMethod;
 
   /// id<NSCopying> type.
   QualType QIDNSCopying;
 
   /// will hold 'respondsToSelector:'
   Selector RespondsToSelectorSel;
 
   /// A flag to remember whether the implicit forms of operator new and delete
   /// have been declared.
   bool GlobalNewDeleteDeclared;
 
   /// Describes how the expressions currently being parsed are
   /// evaluated at run-time, if at all.
   enum class ExpressionEvaluationContext {
     /// The current expression and its subexpressions occur within an
     /// unevaluated operand (C++11 [expr]p7), such as the subexpression of
     /// \c sizeof, where the type of the expression may be significant but
     /// no code will be generated to evaluate the value of the expression at
     /// run time.
     Unevaluated,
 
     /// The current expression occurs within a braced-init-list within
     /// an unevaluated operand. This is mostly like a regular unevaluated
     /// context, except that we still instantiate constexpr functions that are
     /// referenced here so that we can perform narrowing checks correctly.
     UnevaluatedList,
 
     /// The current expression occurs within a discarded statement.
     /// This behaves largely similarly to an unevaluated operand in preventing
     /// definitions from being required, but not in other ways.
     DiscardedStatement,
 
     /// The current expression occurs within an unevaluated
     /// operand that unconditionally permits abstract references to
     /// fields, such as a SIZE operator in MS-style inline assembly.
     UnevaluatedAbstract,
 
     /// The current context is "potentially evaluated" in C++11 terms,
     /// but the expression is evaluated at compile-time (like the values of
     /// cases in a switch statement).
     ConstantEvaluated,
 
     /// In addition of being constant evaluated, the current expression
     /// occurs in an immediate function context - either a consteval function
     /// or a consteval if statement.
     ImmediateFunctionContext,
 
     /// The current expression is potentially evaluated at run time,
     /// which means that code may be generated to evaluate the value of the
     /// expression at run time.
     PotentiallyEvaluated,
 
     /// The current expression is potentially evaluated, but any
     /// declarations referenced inside that expression are only used if
     /// in fact the current expression is used.
     ///
     /// This value is used when parsing default function arguments, for which
     /// we would like to provide diagnostics (e.g., passing non-POD arguments
     /// through varargs) but do not want to mark declarations as "referenced"
     /// until the default argument is used.
     PotentiallyEvaluatedIfUsed
   };
 
   using ImmediateInvocationCandidate = llvm::PointerIntPair<ConstantExpr *, 1>;
 
   /// Data structure used to record current or nested
   /// expression evaluation contexts.
   struct ExpressionEvaluationContextRecord {
     /// The expression evaluation context.
     ExpressionEvaluationContext Context;
 
     /// Whether the enclosing context needed a cleanup.
     CleanupInfo ParentCleanup;
 
     /// The number of active cleanup objects when we entered
     /// this expression evaluation context.
     unsigned NumCleanupObjects;
 
     /// The number of typos encountered during this expression evaluation
     /// context (i.e. the number of TypoExprs created).
     unsigned NumTypos;
 
     MaybeODRUseExprSet SavedMaybeODRUseExprs;
 
     /// The lambdas that are present within this context, if it
     /// is indeed an unevaluated context.
     SmallVector<LambdaExpr *, 2> Lambdas;
 
     /// The declaration that provides context for lambda expressions
     /// and block literals if the normal declaration context does not
     /// suffice, e.g., in a default function argument.
     Decl *ManglingContextDecl;
 
     /// If we are processing a decltype type, a set of call expressions
     /// for which we have deferred checking the completeness of the return type.
     SmallVector<CallExpr *, 8> DelayedDecltypeCalls;
 
     /// If we are processing a decltype type, a set of temporary binding
     /// expressions for which we have deferred checking the destructor.
     SmallVector<CXXBindTemporaryExpr *, 8> DelayedDecltypeBinds;
 
     llvm::SmallPtrSet<const Expr *, 8> PossibleDerefs;
 
     /// Expressions appearing as the LHS of a volatile assignment in this
     /// context. We produce a warning for these when popping the context if
     /// they are not discarded-value expressions nor unevaluated operands.
     SmallVector<Expr*, 2> VolatileAssignmentLHSs;
 
     /// Set of candidates for starting an immediate invocation.
     llvm::SmallVector<ImmediateInvocationCandidate, 4> ImmediateInvocationCandidates;
 
     /// Set of DeclRefExprs referencing a consteval function when used in a
     /// context not already known to be immediately invoked.
     llvm::SmallPtrSet<DeclRefExpr *, 4> ReferenceToConsteval;
 
     /// \brief Describes whether we are in an expression constext which we have
     /// to handle differently.
     enum ExpressionKind {
       EK_Decltype, EK_TemplateArgument, EK_Other
     } ExprContext;
 
     // A context can be nested in both a discarded statement context and
     // an immediate function context, so they need to be tracked independently.
     bool InDiscardedStatement;
     bool InImmediateFunctionContext;
     bool InImmediateEscalatingFunctionContext;
 
     bool IsCurrentlyCheckingDefaultArgumentOrInitializer = false;
 
     // When evaluating immediate functions in the initializer of a default
     // argument or default member initializer, this is the declaration whose
     // default initializer is being evaluated and the location of the call
     // or constructor definition.
     struct InitializationContext {
       InitializationContext(SourceLocation Loc, ValueDecl *Decl,
                             DeclContext *Context)
           : Loc(Loc), Decl(Decl), Context(Context) {
         assert(Decl && Context && "invalid initialization context");
       }
 
       SourceLocation Loc;
       ValueDecl *Decl = nullptr;
       DeclContext *Context = nullptr;
     };
     std::optional<InitializationContext> DelayedDefaultInitializationContext;
 
     ExpressionEvaluationContextRecord(ExpressionEvaluationContext Context,
                                       unsigned NumCleanupObjects,
                                       CleanupInfo ParentCleanup,
                                       Decl *ManglingContextDecl,
                                       ExpressionKind ExprContext)
         : Context(Context), ParentCleanup(ParentCleanup),
           NumCleanupObjects(NumCleanupObjects), NumTypos(0),
           ManglingContextDecl(ManglingContextDecl), ExprContext(ExprContext),
           InDiscardedStatement(false), InImmediateFunctionContext(false),
           InImmediateEscalatingFunctionContext(false) {}
 
     bool isUnevaluated() const {
       return Context == ExpressionEvaluationContext::Unevaluated ||
              Context == ExpressionEvaluationContext::UnevaluatedAbstract ||
              Context == ExpressionEvaluationContext::UnevaluatedList;
     }
 
     bool isConstantEvaluated() const {
       return Context == ExpressionEvaluationContext::ConstantEvaluated ||
              Context == ExpressionEvaluationContext::ImmediateFunctionContext;
     }
 
     bool isImmediateFunctionContext() const {
       return Context == ExpressionEvaluationContext::ImmediateFunctionContext ||
              (Context == ExpressionEvaluationContext::DiscardedStatement &&
               InImmediateFunctionContext) ||
              // C++23 [expr.const]p14:
              // An expression or conversion is in an immediate function
              // context if it is potentially evaluated and either:
              //   * its innermost enclosing non-block scope is a function
              //     parameter scope of an immediate function, or
              //   * its enclosing statement is enclosed by the compound-
              //     statement of a consteval if statement.
              (Context == ExpressionEvaluationContext::PotentiallyEvaluated &&
               InImmediateFunctionContext);
     }
 
     bool isDiscardedStatementContext() const {
       return Context == ExpressionEvaluationContext::DiscardedStatement ||
              (Context ==
                   ExpressionEvaluationContext::ImmediateFunctionContext &&
               InDiscardedStatement);
     }
   };
 
   /// A stack of expression evaluation contexts.
   SmallVector<ExpressionEvaluationContextRecord, 8> ExprEvalContexts;
 
   // Set of failed immediate invocations to avoid double diagnosing.
   llvm::SmallPtrSet<ConstantExpr *, 4> FailedImmediateInvocations;
 
   /// Emit a warning for all pending noderef expressions that we recorded.
   void WarnOnPendingNoDerefs(ExpressionEvaluationContextRecord &Rec);
 
   /// Compute the mangling number context for a lambda expression or
   /// block literal. Also return the extra mangling decl if any.
   ///
   /// \param DC - The DeclContext containing the lambda expression or
   /// block literal.
   std::tuple<MangleNumberingContext *, Decl *>
   getCurrentMangleNumberContext(const DeclContext *DC);
 
 
   /// SpecialMemberOverloadResult - The overloading result for a special member
   /// function.
   ///
   /// This is basically a wrapper around PointerIntPair. The lowest bits of the
   /// integer are used to determine whether overload resolution succeeded.
   class SpecialMemberOverloadResult {
   public:
     enum Kind {
       NoMemberOrDeleted,
       Ambiguous,
       Success
     };
 
   private:
     llvm::PointerIntPair<CXXMethodDecl *, 2> Pair;
 
   public:
     SpecialMemberOverloadResult() {}
     SpecialMemberOverloadResult(CXXMethodDecl *MD)
         : Pair(MD, MD->isDeleted() ? NoMemberOrDeleted : Success) {}
 
     CXXMethodDecl *getMethod() const { return Pair.getPointer(); }
     void setMethod(CXXMethodDecl *MD) { Pair.setPointer(MD); }
 
     Kind getKind() const { return static_cast<Kind>(Pair.getInt()); }
     void setKind(Kind K) { Pair.setInt(K); }
   };
 
   class SpecialMemberOverloadResultEntry
       : public llvm::FastFoldingSetNode,
         public SpecialMemberOverloadResult {
   public:
     SpecialMemberOverloadResultEntry(const llvm::FoldingSetNodeID &ID)
       : FastFoldingSetNode(ID)
     {}
   };
 
   /// A cache of special member function overload resolution results
   /// for C++ records.
   llvm::FoldingSet<SpecialMemberOverloadResultEntry> SpecialMemberCache;
 
   /// A cache of the flags available in enumerations with the flag_bits
   /// attribute.
   mutable llvm::DenseMap<const EnumDecl*, llvm::APInt> FlagBitsCache;
 
   /// The kind of translation unit we are processing.
   ///
   /// When we're processing a complete translation unit, Sema will perform
   /// end-of-translation-unit semantic tasks (such as creating
   /// initializers for tentative definitions in C) once parsing has
   /// completed. Modules and precompiled headers perform different kinds of
   /// checks.
   const TranslationUnitKind TUKind;
 
   llvm::BumpPtrAllocator BumpAlloc;
 
   /// The number of SFINAE diagnostics that have been trapped.
   unsigned NumSFINAEErrors;
 
   typedef llvm::DenseMap<ParmVarDecl *, llvm::TinyPtrVector<ParmVarDecl *>>
     UnparsedDefaultArgInstantiationsMap;
 
   /// A mapping from parameters with unparsed default arguments to the
   /// set of instantiations of each parameter.
   ///
   /// This mapping is a temporary data structure used when parsing
   /// nested class templates or nested classes of class templates,
   /// where we might end up instantiating an inner class before the
   /// default arguments of its methods have been parsed.
   UnparsedDefaultArgInstantiationsMap UnparsedDefaultArgInstantiations;
 
   // Contains the locations of the beginning of unparsed default
   // argument locations.
   llvm::DenseMap<ParmVarDecl *, SourceLocation> UnparsedDefaultArgLocs;
 
   /// UndefinedInternals - all the used, undefined objects which require a
   /// definition in this translation unit.
   llvm::MapVector<NamedDecl *, SourceLocation> UndefinedButUsed;
 
   /// Determine if VD, which must be a variable or function, is an external
   /// symbol that nonetheless can't be referenced from outside this translation
   /// unit because its type has no linkage and it's not extern "C".
   bool isExternalWithNoLinkageType(const ValueDecl *VD) const;
 
   /// Obtain a sorted list of functions that are undefined but ODR-used.
   void getUndefinedButUsed(
       SmallVectorImpl<std::pair<NamedDecl *, SourceLocation> > &Undefined);
 
   /// Retrieves list of suspicious delete-expressions that will be checked at
   /// the end of translation unit.
   const llvm::MapVector<FieldDecl *, DeleteLocs> &
   getMismatchingDeleteExpressions() const;
 
   class GlobalMethodPool {
   public:
     using Lists = std::pair<ObjCMethodList, ObjCMethodList>;
     using iterator = llvm::DenseMap<Selector, Lists>::iterator;
     iterator begin() { return Methods.begin(); }
     iterator end() { return Methods.end(); }
     iterator find(Selector Sel) { return Methods.find(Sel); }
     std::pair<iterator, bool> insert(std::pair<Selector, Lists> &&Val) {
       return Methods.insert(Val);
     }
     int count(Selector Sel) const { return Methods.count(Sel); }
     bool empty() const { return Methods.empty(); }
 
   private:
     llvm::DenseMap<Selector, Lists> Methods;
   };
 
   /// Method Pool - allows efficient lookup when typechecking messages to "id".
   /// We need to maintain a list, since selectors can have differing signatures
   /// across classes. In Cocoa, this happens to be extremely uncommon (only 1%
   /// of selectors are "overloaded").
   /// At the head of the list it is recorded whether there were 0, 1, or >= 2
   /// methods inside categories with a particular selector.
   GlobalMethodPool MethodPool;
 
   /// Method selectors used in a \@selector expression. Used for implementation
   /// of -Wselector.
   llvm::MapVector<Selector, SourceLocation> ReferencedSelectors;
 
   /// List of SourceLocations where 'self' is implicitly retained inside a
   /// block.
   llvm::SmallVector<std::pair<SourceLocation, const BlockDecl *>, 1>
       ImplicitlyRetainedSelfLocs;
 
   /// Kinds of C++ special members.
   enum CXXSpecialMember {
     CXXDefaultConstructor,
     CXXCopyConstructor,
     CXXMoveConstructor,
     CXXCopyAssignment,
     CXXMoveAssignment,
     CXXDestructor,
     CXXInvalid
   };
 
   typedef llvm::PointerIntPair<CXXRecordDecl *, 3, CXXSpecialMember>
       SpecialMemberDecl;
 
   /// The C++ special members which we are currently in the process of
   /// declaring. If this process recursively triggers the declaration of the
   /// same special member, we should act as if it is not yet declared.
   llvm::SmallPtrSet<SpecialMemberDecl, 4> SpecialMembersBeingDeclared;
 
   /// Kinds of defaulted comparison operator functions.
   enum class DefaultedComparisonKind : unsigned char {
     /// This is not a defaultable comparison operator.
     None,
     /// This is an operator== that should be implemented as a series of
     /// subobject comparisons.
     Equal,
     /// This is an operator<=> that should be implemented as a series of
     /// subobject comparisons.
     ThreeWay,
     /// This is an operator!= that should be implemented as a rewrite in terms
     /// of a == comparison.
     NotEqual,
     /// This is an <, <=, >, or >= that should be implemented as a rewrite in
     /// terms of a <=> comparison.
     Relational,
   };
 
   /// The function definitions which were renamed as part of typo-correction
   /// to match their respective declarations. We want to keep track of them
   /// to ensure that we don't emit a "redefinition" error if we encounter a
   /// correctly named definition after the renamed definition.
   llvm::SmallPtrSet<const NamedDecl *, 4> TypoCorrectedFunctionDefinitions;
 
   /// Stack of types that correspond to the parameter entities that are
   /// currently being copy-initialized. Can be empty.
   llvm::SmallVector<QualType, 4> CurrentParameterCopyTypes;
 
   void ReadMethodPool(Selector Sel);
   void updateOutOfDateSelector(Selector Sel);
 
   /// Private Helper predicate to check for 'self'.
   bool isSelfExpr(Expr *RExpr);
   bool isSelfExpr(Expr *RExpr, const ObjCMethodDecl *Method);
 
   /// Cause the active diagnostic on the DiagosticsEngine to be
   /// emitted. This is closely coupled to the SemaDiagnosticBuilder class and
   /// should not be used elsewhere.
   void EmitCurrentDiagnostic(unsigned DiagID);
 
   /// Records and restores the CurFPFeatures state on entry/exit of compound
   /// statements.
   class FPFeaturesStateRAII {
   public:
     FPFeaturesStateRAII(Sema &S);
     ~FPFeaturesStateRAII();
     FPOptionsOverride getOverrides() { return OldOverrides; }
 
   private:
     Sema& S;
     FPOptions OldFPFeaturesState;
     FPOptionsOverride OldOverrides;
     LangOptions::FPEvalMethodKind OldEvalMethod;
     SourceLocation OldFPPragmaLocation;
   };
 
   void addImplicitTypedef(StringRef Name, QualType T);
 
   bool WarnedStackExhausted = false;
 
   /// Increment when we find a reference; decrement when we find an ignored
   /// assignment.  Ultimately the value is 0 if every reference is an ignored
   /// assignment.
   llvm::DenseMap<const VarDecl *, int> RefsMinusAssignments;
 
   /// Indicate RISC-V vector builtin functions enabled or not.
   bool DeclareRISCVVBuiltins = false;
 
   /// Indicate RISC-V SiFive vector builtin functions enabled or not.
   bool DeclareRISCVSiFiveVectorBuiltins = false;
 
 private:
   std::unique_ptr<sema::RISCVIntrinsicManager> RVIntrinsicManager;
 
   std::optional<std::unique_ptr<DarwinSDKInfo>> CachedDarwinSDKInfo;
 
   bool WarnedDarwinSDKInfoMissing = false;
 
 public:
   Sema(Preprocessor &pp, ASTContext &ctxt, ASTConsumer &consumer,
        TranslationUnitKind TUKind = TU_Complete,
        CodeCompleteConsumer *CompletionConsumer = nullptr);
   ~Sema();
 
   /// Perform initialization that occurs after the parser has been
   /// initialized but before it parses anything.
   void Initialize();
 
   /// This virtual key function only exists to limit the emission of debug info
   /// describing the Sema class. GCC and Clang only emit debug info for a class
   /// with a vtable when the vtable is emitted. Sema is final and not
   /// polymorphic, but the debug info size savings are so significant that it is
   /// worth adding a vtable just to take advantage of this optimization.
   virtual void anchor();
 
   const LangOptions &getLangOpts() const { return LangOpts; }
   OpenCLOptions &getOpenCLOptions() { return OpenCLFeatures; }
   FPOptions     &getCurFPFeatures() { return CurFPFeatures; }
 
   DiagnosticsEngine &getDiagnostics() const { return Diags; }
   SourceManager &getSourceManager() const { return SourceMgr; }
   Preprocessor &getPreprocessor() const { return PP; }
   ASTContext &getASTContext() const { return Context; }
   ASTConsumer &getASTConsumer() const { return Consumer; }
   ASTMutationListener *getASTMutationListener() const;
   ExternalSemaSource *getExternalSource() const { return ExternalSource.get(); }
 
   DarwinSDKInfo *getDarwinSDKInfoForAvailabilityChecking(SourceLocation Loc,
                                                          StringRef Platform);
   DarwinSDKInfo *getDarwinSDKInfoForAvailabilityChecking();
 
   ///Registers an external source. If an external source already exists,
   /// creates a multiplex external source and appends to it.
   ///
   ///\param[in] E - A non-null external sema source.
   ///
   void addExternalSource(ExternalSemaSource *E);
 
   void PrintStats() const;
 
   /// Warn that the stack is nearly exhausted.
   void warnStackExhausted(SourceLocation Loc);
 
   /// Run some code with "sufficient" stack space. (Currently, at least 256K is
   /// guaranteed). Produces a warning if we're low on stack space and allocates
   /// more in that case. Use this in code that may recurse deeply (for example,
   /// in template instantiation) to avoid stack overflow.
   void runWithSufficientStackSpace(SourceLocation Loc,
                                    llvm::function_ref<void()> Fn);
 
   /// Helper class that creates diagnostics with optional
   /// template instantiation stacks.
   ///
   /// This class provides a wrapper around the basic DiagnosticBuilder
   /// class that emits diagnostics. ImmediateDiagBuilder is
   /// responsible for emitting the diagnostic (as DiagnosticBuilder
   /// does) and, if the diagnostic comes from inside a template
   /// instantiation, printing the template instantiation stack as
   /// well.
   class ImmediateDiagBuilder : public DiagnosticBuilder {
     Sema &SemaRef;
     unsigned DiagID;
 
   public:
     ImmediateDiagBuilder(DiagnosticBuilder &DB, Sema &SemaRef, unsigned DiagID)
         : DiagnosticBuilder(DB), SemaRef(SemaRef), DiagID(DiagID) {}
     ImmediateDiagBuilder(DiagnosticBuilder &&DB, Sema &SemaRef, unsigned DiagID)
         : DiagnosticBuilder(DB), SemaRef(SemaRef), DiagID(DiagID) {}
 
     // This is a cunning lie. DiagnosticBuilder actually performs move
     // construction in its copy constructor (but due to varied uses, it's not
     // possible to conveniently express this as actual move construction). So
     // the default copy ctor here is fine, because the base class disables the
     // source anyway, so the user-defined ~ImmediateDiagBuilder is a safe no-op
     // in that case anwyay.
     ImmediateDiagBuilder(const ImmediateDiagBuilder &) = default;
 
     ~ImmediateDiagBuilder() {
       // If we aren't active, there is nothing to do.
       if (!isActive()) return;
 
       // Otherwise, we need to emit the diagnostic. First clear the diagnostic
       // builder itself so it won't emit the diagnostic in its own destructor.
       //
       // This seems wasteful, in that as written the DiagnosticBuilder dtor will
       // do its own needless checks to see if the diagnostic needs to be
       // emitted. However, because we take care to ensure that the builder
       // objects never escape, a sufficiently smart compiler will be able to
       // eliminate that code.
       Clear();
 
       // Dispatch to Sema to emit the diagnostic.
       SemaRef.EmitCurrentDiagnostic(DiagID);
     }
 
     /// Teach operator<< to produce an object of the correct type.
     template <typename T>
     friend const ImmediateDiagBuilder &
     operator<<(const ImmediateDiagBuilder &Diag, const T &Value) {
       const DiagnosticBuilder &BaseDiag = Diag;
       BaseDiag << Value;
       return Diag;
     }
 
     // It is necessary to limit this to rvalue reference to avoid calling this
     // function with a bitfield lvalue argument since non-const reference to
     // bitfield is not allowed.
     template <typename T,
               typename = std::enable_if_t<!std::is_lvalue_reference<T>::value>>
     const ImmediateDiagBuilder &operator<<(T &&V) const {
       const DiagnosticBuilder &BaseDiag = *this;
       BaseDiag << std::move(V);
       return *this;
     }
   };
 
   /// A generic diagnostic builder for errors which may or may not be deferred.
   ///
   /// In CUDA, there exist constructs (e.g. variable-length arrays, try/catch)
   /// which are not allowed to appear inside __device__ functions and are
   /// allowed to appear in __host__ __device__ functions only if the host+device
   /// function is never codegen'ed.
   ///
   /// To handle this, we use the notion of "deferred diagnostics", where we
   /// attach a diagnostic to a FunctionDecl that's emitted iff it's codegen'ed.
   ///
   /// This class lets you emit either a regular diagnostic, a deferred
   /// diagnostic, or no diagnostic at all, according to an argument you pass to
   /// its constructor, thus simplifying the process of creating these "maybe
   /// deferred" diagnostics.
   class SemaDiagnosticBuilder {
   public:
     enum Kind {
       /// Emit no diagnostics.
       K_Nop,
       /// Emit the diagnostic immediately (i.e., behave like Sema::Diag()).
       K_Immediate,
       /// Emit the diagnostic immediately, and, if it's a warning or error, also
       /// emit a call stack showing how this function can be reached by an a
       /// priori known-emitted function.
       K_ImmediateWithCallStack,
       /// Create a deferred diagnostic, which is emitted only if the function
       /// it's attached to is codegen'ed.  Also emit a call stack as with
       /// K_ImmediateWithCallStack.
       K_Deferred
     };
 
     SemaDiagnosticBuilder(Kind K, SourceLocation Loc, unsigned DiagID,
                           const FunctionDecl *Fn, Sema &S);
     SemaDiagnosticBuilder(SemaDiagnosticBuilder &&D);
     SemaDiagnosticBuilder(const SemaDiagnosticBuilder &) = default;
 
     // The copy and move assignment operator is defined as deleted pending
     // further motivation.
     SemaDiagnosticBuilder &operator=(const SemaDiagnosticBuilder &) = delete;
     SemaDiagnosticBuilder &operator=(SemaDiagnosticBuilder &&) = delete;
 
     ~SemaDiagnosticBuilder();
 
     bool isImmediate() const { return ImmediateDiag.has_value(); }
 
     /// Convertible to bool: True if we immediately emitted an error, false if
     /// we didn't emit an error or we created a deferred error.
     ///
     /// Example usage:
     ///
     ///   if (SemaDiagnosticBuilder(...) << foo << bar)
     ///     return ExprError();
     ///
     /// But see CUDADiagIfDeviceCode() and CUDADiagIfHostCode() -- you probably
     /// want to use these instead of creating a SemaDiagnosticBuilder yourself.
     operator bool() const { return isImmediate(); }
 
     template <typename T>
     friend const SemaDiagnosticBuilder &
     operator<<(const SemaDiagnosticBuilder &Diag, const T &Value) {
       if (Diag.ImmediateDiag)
         *Diag.ImmediateDiag << Value;
       else if (Diag.PartialDiagId)
         Diag.S.DeviceDeferredDiags[Diag.Fn][*Diag.PartialDiagId].second
             << Value;
       return Diag;
     }
 
     // It is necessary to limit this to rvalue reference to avoid calling this
     // function with a bitfield lvalue argument since non-const reference to
     // bitfield is not allowed.
     template <typename T,
               typename = std::enable_if_t<!std::is_lvalue_reference<T>::value>>
     const SemaDiagnosticBuilder &operator<<(T &&V) const {
       if (ImmediateDiag)
         *ImmediateDiag << std::move(V);
       else if (PartialDiagId)
         S.DeviceDeferredDiags[Fn][*PartialDiagId].second << std::move(V);
       return *this;
     }
 
     friend const SemaDiagnosticBuilder &
     operator<<(const SemaDiagnosticBuilder &Diag, const PartialDiagnostic &PD) {
       if (Diag.ImmediateDiag)
         PD.Emit(*Diag.ImmediateDiag);
       else if (Diag.PartialDiagId)
         Diag.S.DeviceDeferredDiags[Diag.Fn][*Diag.PartialDiagId].second = PD;
       return Diag;
     }
 
     void AddFixItHint(const FixItHint &Hint) const {
       if (ImmediateDiag)
         ImmediateDiag->AddFixItHint(Hint);
       else if (PartialDiagId)
         S.DeviceDeferredDiags[Fn][*PartialDiagId].second.AddFixItHint(Hint);
     }
 
     friend ExprResult ExprError(const SemaDiagnosticBuilder &) {
       return ExprError();
     }
     friend StmtResult StmtError(const SemaDiagnosticBuilder &) {
       return StmtError();
     }
     operator ExprResult() const { return ExprError(); }
     operator StmtResult() const { return StmtError(); }
     operator TypeResult() const { return TypeError(); }
     operator DeclResult() const { return DeclResult(true); }
     operator MemInitResult() const { return MemInitResult(true); }
 
   private:
     Sema &S;
     SourceLocation Loc;
     unsigned DiagID;
     const FunctionDecl *Fn;
     bool ShowCallStack;
 
     // Invariant: At most one of these Optionals has a value.
     // FIXME: Switch these to a Variant once that exists.
     std::optional<ImmediateDiagBuilder> ImmediateDiag;
     std::optional<unsigned> PartialDiagId;
   };
 
   /// Is the last error level diagnostic immediate. This is used to determined
   /// whether the next info diagnostic should be immediate.
   bool IsLastErrorImmediate = true;
 
   /// Emit a diagnostic.
   SemaDiagnosticBuilder Diag(SourceLocation Loc, unsigned DiagID,
                              bool DeferHint = false);
 
   /// Emit a partial diagnostic.
   SemaDiagnosticBuilder Diag(SourceLocation Loc, const PartialDiagnostic &PD,
                              bool DeferHint = false);
 
   /// Build a partial diagnostic.
   PartialDiagnostic PDiag(unsigned DiagID = 0); // in SemaInternal.h
 
   /// Whether deferrable diagnostics should be deferred.
   bool DeferDiags = false;
 
   /// RAII class to control scope of DeferDiags.
   class DeferDiagsRAII {
     Sema &S;
     bool SavedDeferDiags = false;
 
   public:
     DeferDiagsRAII(Sema &S, bool DeferDiags)
         : S(S), SavedDeferDiags(S.DeferDiags) {
       S.DeferDiags = DeferDiags;
     }
     ~DeferDiagsRAII() { S.DeferDiags = SavedDeferDiags; }
   };
 
   /// Whether uncompilable error has occurred. This includes error happens
   /// in deferred diagnostics.
   bool hasUncompilableErrorOccurred() const;
 
   bool findMacroSpelling(SourceLocation &loc, StringRef name);
 
   /// Get a string to suggest for zero-initialization of a type.
   std::string
   getFixItZeroInitializerForType(QualType T, SourceLocation Loc) const;
   std::string getFixItZeroLiteralForType(QualType T, SourceLocation Loc) const;
 
   /// Calls \c Lexer::getLocForEndOfToken()
   SourceLocation getLocForEndOfToken(SourceLocation Loc, unsigned Offset = 0);
 
   /// Retrieve the module loader associated with the preprocessor.
   ModuleLoader &getModuleLoader() const;
 
   /// Invent a new identifier for parameters of abbreviated templates.
   IdentifierInfo *
   InventAbbreviatedTemplateParameterTypeName(IdentifierInfo *ParamName,
                                              unsigned Index);
 
   void emitAndClearUnusedLocalTypedefWarnings();
 
   private:
     /// Function or variable declarations to be checked for whether the deferred
     /// diagnostics should be emitted.
     llvm::SmallSetVector<Decl *, 4> DeclsToCheckForDeferredDiags;
 
   public:
   // Emit all deferred diagnostics.
   void emitDeferredDiags();
 
   enum TUFragmentKind {
     /// The global module fragment, between 'module;' and a module-declaration.
     Global,
     /// A normal translation unit fragment. For a non-module unit, this is the
     /// entire translation unit. Otherwise, it runs from the module-declaration
     /// to the private-module-fragment (if any) or the end of the TU (if not).
     Normal,
     /// The private module fragment, between 'module :private;' and the end of
     /// the translation unit.
     Private
   };
 
   void ActOnStartOfTranslationUnit();
   void ActOnEndOfTranslationUnit();
   void ActOnEndOfTranslationUnitFragment(TUFragmentKind Kind);
 
   void CheckDelegatingCtorCycles();
 
   Scope *getScopeForContext(DeclContext *Ctx);
 
   void PushFunctionScope();
   void PushBlockScope(Scope *BlockScope, BlockDecl *Block);
   sema::LambdaScopeInfo *PushLambdaScope();
 
   /// This is used to inform Sema what the current TemplateParameterDepth
   /// is during Parsing.  Currently it is used to pass on the depth
   /// when parsing generic lambda 'auto' parameters.
   void RecordParsingTemplateParameterDepth(unsigned Depth);
 
   void PushCapturedRegionScope(Scope *RegionScope, CapturedDecl *CD,
                                RecordDecl *RD, CapturedRegionKind K,
                                unsigned OpenMPCaptureLevel = 0);
 
   /// Custom deleter to allow FunctionScopeInfos to be kept alive for a short
   /// time after they've been popped.
   class PoppedFunctionScopeDeleter {
     Sema *Self;
 
   public:
     explicit PoppedFunctionScopeDeleter(Sema *Self) : Self(Self) {}
     void operator()(sema::FunctionScopeInfo *Scope) const;
   };
 
   using PoppedFunctionScopePtr =
       std::unique_ptr<sema::FunctionScopeInfo, PoppedFunctionScopeDeleter>;
 
   PoppedFunctionScopePtr
   PopFunctionScopeInfo(const sema::AnalysisBasedWarnings::Policy *WP = nullptr,
                        const Decl *D = nullptr,
                        QualType BlockType = QualType());
 
   sema::FunctionScopeInfo *getCurFunction() const {
     return FunctionScopes.empty() ? nullptr : FunctionScopes.back();
   }
 
   sema::FunctionScopeInfo *getEnclosingFunction() const;
 
   void setFunctionHasBranchIntoScope();
   void setFunctionHasBranchProtectedScope();
   void setFunctionHasIndirectGoto();
   void setFunctionHasMustTail();
 
   void PushCompoundScope(bool IsStmtExpr);
   void PopCompoundScope();
 
   sema::CompoundScopeInfo &getCurCompoundScope() const;
 
   bool hasAnyUnrecoverableErrorsInThisFunction() const;
 
   /// Retrieve the current block, if any.
   sema::BlockScopeInfo *getCurBlock();
 
   /// Get the innermost lambda enclosing the current location, if any. This
   /// looks through intervening non-lambda scopes such as local functions and
   /// blocks.
   sema::LambdaScopeInfo *getEnclosingLambda() const;
 
   /// Retrieve the current lambda scope info, if any.
   /// \param IgnoreNonLambdaCapturingScope true if should find the top-most
   /// lambda scope info ignoring all inner capturing scopes that are not
   /// lambda scopes.
   sema::LambdaScopeInfo *
   getCurLambda(bool IgnoreNonLambdaCapturingScope = false);
 
   /// Retrieve the current generic lambda info, if any.
   sema::LambdaScopeInfo *getCurGenericLambda();
 
   /// Retrieve the current captured region, if any.
   sema::CapturedRegionScopeInfo *getCurCapturedRegion();
 
   /// Retrieve the current function, if any, that should be analyzed for
   /// potential availability violations.
   sema::FunctionScopeInfo *getCurFunctionAvailabilityContext();
 
   /// WeakTopLevelDeclDecls - access to \#pragma weak-generated Decls
   SmallVectorImpl<Decl *> &WeakTopLevelDecls() { return WeakTopLevelDecl; }
 
   /// Called before parsing a function declarator belonging to a function
   /// declaration.
   void ActOnStartFunctionDeclarationDeclarator(Declarator &D,
                                                unsigned TemplateParameterDepth);
 
   /// Called after parsing a function declarator belonging to a function
   /// declaration.
   void ActOnFinishFunctionDeclarationDeclarator(Declarator &D);
 
   void ActOnComment(SourceRange Comment);
 
   //===--------------------------------------------------------------------===//
   // Type Analysis / Processing: SemaType.cpp.
   //
 
   QualType BuildQualifiedType(QualType T, SourceLocation Loc, Qualifiers Qs,
                               const DeclSpec *DS = nullptr);
   QualType BuildQualifiedType(QualType T, SourceLocation Loc, unsigned CVRA,
                               const DeclSpec *DS = nullptr);
   QualType BuildPointerType(QualType T,
                             SourceLocation Loc, DeclarationName Entity);
   QualType BuildReferenceType(QualType T, bool LValueRef,
                               SourceLocation Loc, DeclarationName Entity);
   QualType BuildArrayType(QualType T, ArrayType::ArraySizeModifier ASM,
                           Expr *ArraySize, unsigned Quals,
                           SourceRange Brackets, DeclarationName Entity);
   QualType BuildVectorType(QualType T, Expr *VecSize, SourceLocation AttrLoc);
   QualType BuildExtVectorType(QualType T, Expr *ArraySize,
                               SourceLocation AttrLoc);
   QualType BuildMatrixType(QualType T, Expr *NumRows, Expr *NumColumns,
                            SourceLocation AttrLoc);
 
   QualType BuildAddressSpaceAttr(QualType &T, LangAS ASIdx, Expr *AddrSpace,
                                  SourceLocation AttrLoc);
 
   /// Same as above, but constructs the AddressSpace index if not provided.
   QualType BuildAddressSpaceAttr(QualType &T, Expr *AddrSpace,
                                  SourceLocation AttrLoc);
 
   bool CheckQualifiedFunctionForTypeId(QualType T, SourceLocation Loc);
 
   bool CheckFunctionReturnType(QualType T, SourceLocation Loc);
 
   /// Build a function type.
   ///
   /// This routine checks the function type according to C++ rules and
   /// under the assumption that the result type and parameter types have
   /// just been instantiated from a template. It therefore duplicates
   /// some of the behavior of GetTypeForDeclarator, but in a much
   /// simpler form that is only suitable for this narrow use case.
   ///
   /// \param T The return type of the function.
   ///
   /// \param ParamTypes The parameter types of the function. This array
   /// will be modified to account for adjustments to the types of the
   /// function parameters.
   ///
   /// \param Loc The location of the entity whose type involves this
   /// function type or, if there is no such entity, the location of the
   /// type that will have function type.
   ///
   /// \param Entity The name of the entity that involves the function
   /// type, if known.
   ///
   /// \param EPI Extra information about the function type. Usually this will
   /// be taken from an existing function with the same prototype.
   ///
   /// \returns A suitable function type, if there are no errors. The
   /// unqualified type will always be a FunctionProtoType.
   /// Otherwise, returns a NULL type.
   QualType BuildFunctionType(QualType T,
                              MutableArrayRef<QualType> ParamTypes,
                              SourceLocation Loc, DeclarationName Entity,
                              const FunctionProtoType::ExtProtoInfo &EPI);
 
   QualType BuildMemberPointerType(QualType T, QualType Class,
                                   SourceLocation Loc,
                                   DeclarationName Entity);
   QualType BuildBlockPointerType(QualType T,
                                  SourceLocation Loc, DeclarationName Entity);
   QualType BuildParenType(QualType T);
   QualType BuildAtomicType(QualType T, SourceLocation Loc);
   QualType BuildReadPipeType(QualType T,
                          SourceLocation Loc);
   QualType BuildWritePipeType(QualType T,
                          SourceLocation Loc);
   QualType BuildBitIntType(bool IsUnsigned, Expr *BitWidth, SourceLocation Loc);
 
   TypeSourceInfo *GetTypeForDeclarator(Declarator &D, Scope *S);
   TypeSourceInfo *GetTypeForDeclaratorCast(Declarator &D, QualType FromTy);
 
   /// Package the given type and TSI into a ParsedType.
   ParsedType CreateParsedType(QualType T, TypeSourceInfo *TInfo);
   DeclarationNameInfo GetNameForDeclarator(Declarator &D);
   DeclarationNameInfo GetNameFromUnqualifiedId(const UnqualifiedId &Name);
   static QualType GetTypeFromParser(ParsedType Ty,
                                     TypeSourceInfo **TInfo = nullptr);
   CanThrowResult canThrow(const Stmt *E);
   /// Determine whether the callee of a particular function call can throw.
   /// E, D and Loc are all optional.
   static CanThrowResult canCalleeThrow(Sema &S, const Expr *E, const Decl *D,
                                        SourceLocation Loc = SourceLocation());
   const FunctionProtoType *ResolveExceptionSpec(SourceLocation Loc,
                                                 const FunctionProtoType *FPT);
   void UpdateExceptionSpec(FunctionDecl *FD,
                            const FunctionProtoType::ExceptionSpecInfo &ESI);
   bool CheckSpecifiedExceptionType(QualType &T, SourceRange Range);
   bool CheckDistantExceptionSpec(QualType T);
   bool CheckEquivalentExceptionSpec(FunctionDecl *Old, FunctionDecl *New);
   bool CheckEquivalentExceptionSpec(
       const FunctionProtoType *Old, SourceLocation OldLoc,
       const FunctionProtoType *New, SourceLocation NewLoc);
   bool CheckEquivalentExceptionSpec(
       const PartialDiagnostic &DiagID, const PartialDiagnostic & NoteID,
       const FunctionProtoType *Old, SourceLocation OldLoc,
       const FunctionProtoType *New, SourceLocation NewLoc);
   bool handlerCanCatch(QualType HandlerType, QualType ExceptionType);
   bool CheckExceptionSpecSubset(const PartialDiagnostic &DiagID,
                                 const PartialDiagnostic &NestedDiagID,
                                 const PartialDiagnostic &NoteID,
                                 const PartialDiagnostic &NoThrowDiagID,
                                 const FunctionProtoType *Superset,
                                 SourceLocation SuperLoc,
                                 const FunctionProtoType *Subset,
                                 SourceLocation SubLoc);
   bool CheckParamExceptionSpec(const PartialDiagnostic &NestedDiagID,
                                const PartialDiagnostic &NoteID,
                                const FunctionProtoType *Target,
                                SourceLocation TargetLoc,
                                const FunctionProtoType *Source,
                                SourceLocation SourceLoc);
 
   TypeResult ActOnTypeName(Scope *S, Declarator &D);
 
   /// The parser has parsed the context-sensitive type 'instancetype'
   /// in an Objective-C message declaration. Return the appropriate type.
   ParsedType ActOnObjCInstanceType(SourceLocation Loc);
 
   /// Abstract class used to diagnose incomplete types.
   struct TypeDiagnoser {
     TypeDiagnoser() {}
 
     virtual void diagnose(Sema &S, SourceLocation Loc, QualType T) = 0;
     virtual ~TypeDiagnoser() {}
   };
 
   static int getPrintable(int I) { return I; }
   static unsigned getPrintable(unsigned I) { return I; }
   static bool getPrintable(bool B) { return B; }
   static const char * getPrintable(const char *S) { return S; }
   static StringRef getPrintable(StringRef S) { return S; }
   static const std::string &getPrintable(const std::string &S) { return S; }
   static const IdentifierInfo *getPrintable(const IdentifierInfo *II) {
     return II;
   }
   static DeclarationName getPrintable(DeclarationName N) { return N; }
   static QualType getPrintable(QualType T) { return T; }
   static SourceRange getPrintable(SourceRange R) { return R; }
   static SourceRange getPrintable(SourceLocation L) { return L; }
   static SourceRange getPrintable(const Expr *E) { return E->getSourceRange(); }
   static SourceRange getPrintable(TypeLoc TL) { return TL.getSourceRange();}
 
   template <typename... Ts> class BoundTypeDiagnoser : public TypeDiagnoser {
   protected:
     unsigned DiagID;
     std::tuple<const Ts &...> Args;
 
     template <std::size_t... Is>
     void emit(const SemaDiagnosticBuilder &DB,
               std::index_sequence<Is...>) const {
       // Apply all tuple elements to the builder in order.
       bool Dummy[] = {false, (DB << getPrintable(std::get<Is>(Args)))...};
       (void)Dummy;
     }
 
   public:
     BoundTypeDiagnoser(unsigned DiagID, const Ts &...Args)
         : TypeDiagnoser(), DiagID(DiagID), Args(Args...) {
       assert(DiagID != 0 && "no diagnostic for type diagnoser");
     }
 
     void diagnose(Sema &S, SourceLocation Loc, QualType T) override {
       const SemaDiagnosticBuilder &DB = S.Diag(Loc, DiagID);
       emit(DB, std::index_sequence_for<Ts...>());
       DB << T;
     }
   };
 
   /// Do a check to make sure \p Name looks like a legal argument for the
   /// swift_name attribute applied to decl \p D.  Raise a diagnostic if the name
   /// is invalid for the given declaration.
   ///
   /// \p AL is used to provide caret diagnostics in case of a malformed name.
   ///
   /// \returns true if the name is a valid swift name for \p D, false otherwise.
   bool DiagnoseSwiftName(Decl *D, StringRef Name, SourceLocation Loc,
                          const ParsedAttr &AL, bool IsAsync);
 
   /// A derivative of BoundTypeDiagnoser for which the diagnostic's type
   /// parameter is preceded by a 0/1 enum that is 1 if the type is sizeless.
   /// For example, a diagnostic with no other parameters would generally have
   /// the form "...%select{incomplete|sizeless}0 type %1...".
   template <typename... Ts>
   class SizelessTypeDiagnoser : public BoundTypeDiagnoser<Ts...> {
   public:
     SizelessTypeDiagnoser(unsigned DiagID, const Ts &... Args)
         : BoundTypeDiagnoser<Ts...>(DiagID, Args...) {}
 
     void diagnose(Sema &S, SourceLocation Loc, QualType T) override {
       const SemaDiagnosticBuilder &DB = S.Diag(Loc, this->DiagID);
       this->emit(DB, std::index_sequence_for<Ts...>());
       DB << T->isSizelessType() << T;
     }
   };
 
   enum class CompleteTypeKind {
     /// Apply the normal rules for complete types.  In particular,
     /// treat all sizeless types as incomplete.
     Normal,
 
     /// Relax the normal rules for complete types so that they include
     /// sizeless built-in types.
     AcceptSizeless,
 
     // FIXME: Eventually we should flip the default to Normal and opt in
     // to AcceptSizeless rather than opt out of it.
     Default = AcceptSizeless
   };
 
   enum class AcceptableKind { Visible, Reachable };
 
 private:
   /// Methods for marking which expressions involve dereferencing a pointer
   /// marked with the 'noderef' attribute. Expressions are checked bottom up as
   /// they are parsed, meaning that a noderef pointer may not be accessed. For
   /// example, in `&*p` where `p` is a noderef pointer, we will first parse the
   /// `*p`, but need to check that `address of` is called on it. This requires
   /// keeping a container of all pending expressions and checking if the address
   /// of them are eventually taken.
   void CheckSubscriptAccessOfNoDeref(const ArraySubscriptExpr *E);
   void CheckAddressOfNoDeref(const Expr *E);
   void CheckMemberAccessOfNoDeref(const MemberExpr *E);
 
   bool RequireCompleteTypeImpl(SourceLocation Loc, QualType T,
                                CompleteTypeKind Kind, TypeDiagnoser *Diagnoser);
 
   struct ModuleScope {
     SourceLocation BeginLoc;
     clang::Module *Module = nullptr;
     bool ModuleInterface = false;
     VisibleModuleSet OuterVisibleModules;
   };
   /// The modules we're currently parsing.
   llvm::SmallVector<ModuleScope, 16> ModuleScopes;
 
   /// For an interface unit, this is the implicitly imported interface unit.
   clang::Module *ThePrimaryInterface = nullptr;
 
   /// The explicit global module fragment of the current translation unit.
   /// The explicit Global Module Fragment, as specified in C++
   /// [module.global.frag].
   clang::Module *TheGlobalModuleFragment = nullptr;
 
   /// The implicit global module fragments of the current translation unit.
   /// We would only create at most two implicit global module fragments to
   /// avoid performance penalties when there are many language linkage
   /// exports.
   ///
   /// The contents in the implicit global module fragment can't be discarded
   /// no matter if it is exported or not.
   clang::Module *TheImplicitGlobalModuleFragment = nullptr;
   clang::Module *TheExportedImplicitGlobalModuleFragment = nullptr;
 
   /// Namespace definitions that we will export when they finish.
   llvm::SmallPtrSet<const NamespaceDecl*, 8> DeferredExportedNamespaces;
 
   /// In a C++ standard module, inline declarations require a definition to be
   /// present at the end of a definition domain.  This set holds the decls to
   /// be checked at the end of the TU.
   llvm::SmallPtrSet<const FunctionDecl *, 8> PendingInlineFuncDecls;
 
   /// Helper function to judge if we are in module purview.
   /// Return false if we are not in a module.
   bool isCurrentModulePurview() const {
     return getCurrentModule() ? getCurrentModule()->isModulePurview() : false;
   }
 
   /// Enter the scope of the explicit global module fragment.
   Module *PushGlobalModuleFragment(SourceLocation BeginLoc);
   /// Leave the scope of the explicit global module fragment.
   void PopGlobalModuleFragment();
 
   /// Enter the scope of an implicit global module fragment.
   Module *PushImplicitGlobalModuleFragment(SourceLocation BeginLoc,
                                            bool IsExported);
   /// Leave the scope of an implicit global module fragment.
   void PopImplicitGlobalModuleFragment();
 
   VisibleModuleSet VisibleModules;
 
   /// Cache for module units which is usable for current module.
   llvm::DenseSet<const Module *> UsableModuleUnitsCache;
 
   bool isUsableModule(const Module *M);
 
   bool isAcceptableSlow(const NamedDecl *D, AcceptableKind Kind);
 
 public:
   /// Get the module unit whose scope we are currently within.
   Module *getCurrentModule() const {
     return ModuleScopes.empty() ? nullptr : ModuleScopes.back().Module;
   }
 
   /// Is the module scope we are an interface?
   bool currentModuleIsInterface() const {
     return ModuleScopes.empty() ? false : ModuleScopes.back().ModuleInterface;
   }
 
   /// Is the module scope we are in a C++ Header Unit?
   bool currentModuleIsHeaderUnit() const {
     return ModuleScopes.empty() ? false
                                 : ModuleScopes.back().Module->isHeaderUnit();
   }
 
   /// Get the module owning an entity.
   Module *getOwningModule(const Decl *Entity) {
     return Entity->getOwningModule();
   }
 
   /// Make a merged definition of an existing hidden definition \p ND
   /// visible at the specified location.
   void makeMergedDefinitionVisible(NamedDecl *ND);
 
   bool isModuleVisible(const Module *M, bool ModulePrivate = false);
 
   // When loading a non-modular PCH files, this is used to restore module
   // visibility.
   void makeModuleVisible(Module *Mod, SourceLocation ImportLoc) {
     VisibleModules.setVisible(Mod, ImportLoc);
   }
 
   /// Determine whether a declaration is visible to name lookup.
   bool isVisible(const NamedDecl *D) {
     return D->isUnconditionallyVisible() ||
            isAcceptableSlow(D, AcceptableKind::Visible);
   }
 
   /// Determine whether a declaration is reachable.
   bool isReachable(const NamedDecl *D) {
     // All visible declarations are reachable.
     return D->isUnconditionallyVisible() ||
            isAcceptableSlow(D, AcceptableKind::Reachable);
   }
 
   /// Determine whether a declaration is acceptable (visible/reachable).
   bool isAcceptable(const NamedDecl *D, AcceptableKind Kind) {
     return Kind == AcceptableKind::Visible ? isVisible(D) : isReachable(D);
   }
 
   /// Determine whether any declaration of an entity is visible.
   bool
   hasVisibleDeclaration(const NamedDecl *D,
                         llvm::SmallVectorImpl<Module *> *Modules = nullptr) {
     return isVisible(D) || hasVisibleDeclarationSlow(D, Modules);
   }
 
   bool hasVisibleDeclarationSlow(const NamedDecl *D,
                                  llvm::SmallVectorImpl<Module *> *Modules);
   /// Determine whether any declaration of an entity is reachable.
   bool
   hasReachableDeclaration(const NamedDecl *D,
                           llvm::SmallVectorImpl<Module *> *Modules = nullptr) {
     return isReachable(D) || hasReachableDeclarationSlow(D, Modules);
   }
   bool hasReachableDeclarationSlow(
       const NamedDecl *D, llvm::SmallVectorImpl<Module *> *Modules = nullptr);
 
   bool hasVisibleMergedDefinition(const NamedDecl *Def);
   bool hasMergedDefinitionInCurrentModule(const NamedDecl *Def);
 
   /// Determine if \p D and \p Suggested have a structurally compatible
   /// layout as described in C11 6.2.7/1.
   bool hasStructuralCompatLayout(Decl *D, Decl *Suggested);
 
   /// Determine if \p D has a visible definition. If not, suggest a declaration
   /// that should be made visible to expose the definition.
   bool hasVisibleDefinition(NamedDecl *D, NamedDecl **Suggested,
                             bool OnlyNeedComplete = false);
   bool hasVisibleDefinition(const NamedDecl *D) {
     NamedDecl *Hidden;
     return hasVisibleDefinition(const_cast<NamedDecl*>(D), &Hidden);
   }
 
   /// Determine if \p D has a reachable definition. If not, suggest a
   /// declaration that should be made reachable to expose the definition.
   bool hasReachableDefinition(NamedDecl *D, NamedDecl **Suggested,
                               bool OnlyNeedComplete = false);
   bool hasReachableDefinition(NamedDecl *D) {
     NamedDecl *Hidden;
     return hasReachableDefinition(D, &Hidden);
   }
 
   bool hasAcceptableDefinition(NamedDecl *D, NamedDecl **Suggested,
                                AcceptableKind Kind,
                                bool OnlyNeedComplete = false);
   bool hasAcceptableDefinition(NamedDecl *D, AcceptableKind Kind) {
     NamedDecl *Hidden;
     return hasAcceptableDefinition(D, &Hidden, Kind);
   }
 
   /// Determine if the template parameter \p D has a visible default argument.
   bool
   hasVisibleDefaultArgument(const NamedDecl *D,
                             llvm::SmallVectorImpl<Module *> *Modules = nullptr);
   /// Determine if the template parameter \p D has a reachable default argument.
   bool hasReachableDefaultArgument(
       const NamedDecl *D, llvm::SmallVectorImpl<Module *> *Modules = nullptr);
   /// Determine if the template parameter \p D has a reachable default argument.
   bool hasAcceptableDefaultArgument(const NamedDecl *D,
                                     llvm::SmallVectorImpl<Module *> *Modules,
                                     Sema::AcceptableKind Kind);
 
   /// Determine if there is a visible declaration of \p D that is an explicit
   /// specialization declaration for a specialization of a template. (For a
   /// member specialization, use hasVisibleMemberSpecialization.)
   bool hasVisibleExplicitSpecialization(
       const NamedDecl *D, llvm::SmallVectorImpl<Module *> *Modules = nullptr);
   /// Determine if there is a reachable declaration of \p D that is an explicit
   /// specialization declaration for a specialization of a template. (For a
   /// member specialization, use hasReachableMemberSpecialization.)
   bool hasReachableExplicitSpecialization(
       const NamedDecl *D, llvm::SmallVectorImpl<Module *> *Modules = nullptr);
 
   /// Determine if there is a visible declaration of \p D that is a member
   /// specialization declaration (as opposed to an instantiated declaration).
   bool hasVisibleMemberSpecialization(
       const NamedDecl *D, llvm::SmallVectorImpl<Module *> *Modules = nullptr);
   /// Determine if there is a reachable declaration of \p D that is a member
   /// specialization declaration (as opposed to an instantiated declaration).
   bool hasReachableMemberSpecialization(
       const NamedDecl *D, llvm::SmallVectorImpl<Module *> *Modules = nullptr);
 
   /// Determine if \p A and \p B are equivalent internal linkage declarations
   /// from different modules, and thus an ambiguity error can be downgraded to
   /// an extension warning.
   bool isEquivalentInternalLinkageDeclaration(const NamedDecl *A,
                                               const NamedDecl *B);
   void diagnoseEquivalentInternalLinkageDeclarations(
       SourceLocation Loc, const NamedDecl *D,
       ArrayRef<const NamedDecl *> Equiv);
 
   bool isUsualDeallocationFunction(const CXXMethodDecl *FD);
 
   // Check whether the size of array element of type \p EltTy is a multiple of
   // its alignment and return false if it isn't.
   bool checkArrayElementAlignment(QualType EltTy, SourceLocation Loc);
 
   bool isCompleteType(SourceLocation Loc, QualType T,
                       CompleteTypeKind Kind = CompleteTypeKind::Default) {
     return !RequireCompleteTypeImpl(Loc, T, Kind, nullptr);
   }
   bool RequireCompleteType(SourceLocation Loc, QualType T,
                            CompleteTypeKind Kind, TypeDiagnoser &Diagnoser);
   bool RequireCompleteType(SourceLocation Loc, QualType T,
                            CompleteTypeKind Kind, unsigned DiagID);
 
   bool RequireCompleteType(SourceLocation Loc, QualType T,
                            TypeDiagnoser &Diagnoser) {
     return RequireCompleteType(Loc, T, CompleteTypeKind::Default, Diagnoser);
   }
   bool RequireCompleteType(SourceLocation Loc, QualType T, unsigned DiagID) {
     return RequireCompleteType(Loc, T, CompleteTypeKind::Default, DiagID);
   }
 
   template <typename... Ts>
   bool RequireCompleteType(SourceLocation Loc, QualType T, unsigned DiagID,
                            const Ts &...Args) {
     BoundTypeDiagnoser<Ts...> Diagnoser(DiagID, Args...);
     return RequireCompleteType(Loc, T, Diagnoser);
   }
 
   template <typename... Ts>
   bool RequireCompleteSizedType(SourceLocation Loc, QualType T, unsigned DiagID,
                                 const Ts &... Args) {
     SizelessTypeDiagnoser<Ts...> Diagnoser(DiagID, Args...);
     return RequireCompleteType(Loc, T, CompleteTypeKind::Normal, Diagnoser);
   }
 
   /// Get the type of expression E, triggering instantiation to complete the
   /// type if necessary -- that is, if the expression refers to a templated
   /// static data member of incomplete array type.
   ///
   /// May still return an incomplete type if instantiation was not possible or
   /// if the type is incomplete for a different reason. Use
   /// RequireCompleteExprType instead if a diagnostic is expected for an
   /// incomplete expression type.
   QualType getCompletedType(Expr *E);
 
   void completeExprArrayBound(Expr *E);
   bool RequireCompleteExprType(Expr *E, CompleteTypeKind Kind,
                                TypeDiagnoser &Diagnoser);
   bool RequireCompleteExprType(Expr *E, unsigned DiagID);
 
   template <typename... Ts>
   bool RequireCompleteExprType(Expr *E, unsigned DiagID, const Ts &...Args) {
     BoundTypeDiagnoser<Ts...> Diagnoser(DiagID, Args...);
     return RequireCompleteExprType(E, CompleteTypeKind::Default, Diagnoser);
   }
 
   template <typename... Ts>
   bool RequireCompleteSizedExprType(Expr *E, unsigned DiagID,
                                     const Ts &... Args) {
     SizelessTypeDiagnoser<Ts...> Diagnoser(DiagID, Args...);
     return RequireCompleteExprType(E, CompleteTypeKind::Normal, Diagnoser);
   }
 
   bool RequireLiteralType(SourceLocation Loc, QualType T,
                           TypeDiagnoser &Diagnoser);
   bool RequireLiteralType(SourceLocation Loc, QualType T, unsigned DiagID);
 
   template <typename... Ts>
   bool RequireLiteralType(SourceLocation Loc, QualType T, unsigned DiagID,
                           const Ts &...Args) {
     BoundTypeDiagnoser<Ts...> Diagnoser(DiagID, Args...);
     return RequireLiteralType(Loc, T, Diagnoser);
   }
 
   QualType getElaboratedType(ElaboratedTypeKeyword Keyword,
                              const CXXScopeSpec &SS, QualType T,
                              TagDecl *OwnedTagDecl = nullptr);
 
   // Returns the underlying type of a decltype with the given expression.
   QualType getDecltypeForExpr(Expr *E);
 
   QualType BuildTypeofExprType(Expr *E, TypeOfKind Kind);
   /// If AsUnevaluated is false, E is treated as though it were an evaluated
   /// context, such as when building a type for decltype(auto).
   QualType BuildDecltypeType(Expr *E, bool AsUnevaluated = true);
 
   using UTTKind = UnaryTransformType::UTTKind;
   QualType BuildUnaryTransformType(QualType BaseType, UTTKind UKind,
                                    SourceLocation Loc);
   QualType BuiltinEnumUnderlyingType(QualType BaseType, SourceLocation Loc);
   QualType BuiltinAddPointer(QualType BaseType, SourceLocation Loc);
   QualType BuiltinRemovePointer(QualType BaseType, SourceLocation Loc);
   QualType BuiltinDecay(QualType BaseType, SourceLocation Loc);
   QualType BuiltinAddReference(QualType BaseType, UTTKind UKind,
                                SourceLocation Loc);
   QualType BuiltinRemoveExtent(QualType BaseType, UTTKind UKind,
                                SourceLocation Loc);
   QualType BuiltinRemoveReference(QualType BaseType, UTTKind UKind,
                                   SourceLocation Loc);
   QualType BuiltinChangeCVRQualifiers(QualType BaseType, UTTKind UKind,
                                       SourceLocation Loc);
   QualType BuiltinChangeSignedness(QualType BaseType, UTTKind UKind,
                                    SourceLocation Loc);
 
   //===--------------------------------------------------------------------===//
   // Symbol table / Decl tracking callbacks: SemaDecl.cpp.
   //
 
   struct SkipBodyInfo {
     SkipBodyInfo() = default;
     bool ShouldSkip = false;
     bool CheckSameAsPrevious = false;
     NamedDecl *Previous = nullptr;
     NamedDecl *New = nullptr;
   };
 
   DeclGroupPtrTy ConvertDeclToDeclGroup(Decl *Ptr, Decl *OwnedType = nullptr);
 
   void DiagnoseUseOfUnimplementedSelectors();
 
   bool isSimpleTypeSpecifier(tok::TokenKind Kind) const;
 
   ParsedType getTypeName(const IdentifierInfo &II, SourceLocation NameLoc,
                          Scope *S, CXXScopeSpec *SS = nullptr,
                          bool isClassName = false, bool HasTrailingDot = false,
                          ParsedType ObjectType = nullptr,
                          bool IsCtorOrDtorName = false,
                          bool WantNontrivialTypeSourceInfo = false,
                          bool IsClassTemplateDeductionContext = true,
                          ImplicitTypenameContext AllowImplicitTypename =
                              ImplicitTypenameContext::No,
                          IdentifierInfo **CorrectedII = nullptr);
   TypeSpecifierType isTagName(IdentifierInfo &II, Scope *S);
   bool isMicrosoftMissingTypename(const CXXScopeSpec *SS, Scope *S);
   void DiagnoseUnknownTypeName(IdentifierInfo *&II,
                                SourceLocation IILoc,
                                Scope *S,
                                CXXScopeSpec *SS,
                                ParsedType &SuggestedType,
                                bool IsTemplateName = false);
 
   /// Attempt to behave like MSVC in situations where lookup of an unqualified
   /// type name has failed in a dependent context. In these situations, we
   /// automatically form a DependentTypeName that will retry lookup in a related
   /// scope during instantiation.
   ParsedType ActOnMSVCUnknownTypeName(const IdentifierInfo &II,
                                       SourceLocation NameLoc,
                                       bool IsTemplateTypeArg);
 
   /// Describes the result of the name lookup and resolution performed
   /// by \c ClassifyName().
   enum NameClassificationKind {
     /// This name is not a type or template in this context, but might be
     /// something else.
     NC_Unknown,
     /// Classification failed; an error has been produced.
     NC_Error,
     /// The name has been typo-corrected to a keyword.
     NC_Keyword,
     /// The name was classified as a type.
     NC_Type,
     /// The name was classified as a specific non-type, non-template
     /// declaration. ActOnNameClassifiedAsNonType should be called to
     /// convert the declaration to an expression.
     NC_NonType,
     /// The name was classified as an ADL-only function name.
     /// ActOnNameClassifiedAsUndeclaredNonType should be called to convert the
     /// result to an expression.
     NC_UndeclaredNonType,
     /// The name denotes a member of a dependent type that could not be
     /// resolved. ActOnNameClassifiedAsDependentNonType should be called to
     /// convert the result to an expression.
     NC_DependentNonType,
     /// The name was classified as an overload set, and an expression
     /// representing that overload set has been formed.
     /// ActOnNameClassifiedAsOverloadSet should be called to form a suitable
     /// expression referencing the overload set.
     NC_OverloadSet,
     /// The name was classified as a template whose specializations are types.
     NC_TypeTemplate,
     /// The name was classified as a variable template name.
     NC_VarTemplate,
     /// The name was classified as a function template name.
     NC_FunctionTemplate,
     /// The name was classified as an ADL-only function template name.
     NC_UndeclaredTemplate,
     /// The name was classified as a concept name.
     NC_Concept,
   };
 
   class NameClassification {
     NameClassificationKind Kind;
     union {
       ExprResult Expr;
       NamedDecl *NonTypeDecl;
       TemplateName Template;
       ParsedType Type;
     };
 
     explicit NameClassification(NameClassificationKind Kind) : Kind(Kind) {}
 
   public:
     NameClassification(ParsedType Type) : Kind(NC_Type), Type(Type) {}
 
     NameClassification(const IdentifierInfo *Keyword) : Kind(NC_Keyword) {}
 
     static NameClassification Error() {
       return NameClassification(NC_Error);
     }
 
     static NameClassification Unknown() {
       return NameClassification(NC_Unknown);
     }
 
     static NameClassification OverloadSet(ExprResult E) {
       NameClassification Result(NC_OverloadSet);
       Result.Expr = E;
       return Result;
     }
 
     static NameClassification NonType(NamedDecl *D) {
       NameClassification Result(NC_NonType);
       Result.NonTypeDecl = D;
       return Result;
     }
 
     static NameClassification UndeclaredNonType() {
       return NameClassification(NC_UndeclaredNonType);
     }
 
     static NameClassification DependentNonType() {
       return NameClassification(NC_DependentNonType);
     }
 
     static NameClassification TypeTemplate(TemplateName Name) {
       NameClassification Result(NC_TypeTemplate);
       Result.Template = Name;
       return Result;
     }
 
     static NameClassification VarTemplate(TemplateName Name) {
       NameClassification Result(NC_VarTemplate);
       Result.Template = Name;
       return Result;
     }
 
     static NameClassification FunctionTemplate(TemplateName Name) {
       NameClassification Result(NC_FunctionTemplate);
       Result.Template = Name;
       return Result;
     }
 
     static NameClassification Concept(TemplateName Name) {
       NameClassification Result(NC_Concept);
       Result.Template = Name;
       return Result;
     }
 
     static NameClassification UndeclaredTemplate(TemplateName Name) {
       NameClassification Result(NC_UndeclaredTemplate);
       Result.Template = Name;
       return Result;
     }
 
     NameClassificationKind getKind() const { return Kind; }
 
     ExprResult getExpression() const {
       assert(Kind == NC_OverloadSet);
       return Expr;
     }
 
     ParsedType getType() const {
       assert(Kind == NC_Type);
       return Type;
     }
 
     NamedDecl *getNonTypeDecl() const {
       assert(Kind == NC_NonType);
       return NonTypeDecl;
     }
 
     TemplateName getTemplateName() const {
       assert(Kind == NC_TypeTemplate || Kind == NC_FunctionTemplate ||
              Kind == NC_VarTemplate || Kind == NC_Concept ||
              Kind == NC_UndeclaredTemplate);
       return Template;
     }
 
     TemplateNameKind getTemplateNameKind() const {
       switch (Kind) {
       case NC_TypeTemplate:
         return TNK_Type_template;
       case NC_FunctionTemplate:
         return TNK_Function_template;
       case NC_VarTemplate:
         return TNK_Var_template;
       case NC_Concept:
         return TNK_Concept_template;
       case NC_UndeclaredTemplate:
         return TNK_Undeclared_template;
       default:
         llvm_unreachable("unsupported name classification.");
       }
     }
   };
 
   /// Perform name lookup on the given name, classifying it based on
   /// the results of name lookup and the following token.
   ///
   /// This routine is used by the parser to resolve identifiers and help direct
   /// parsing. When the identifier cannot be found, this routine will attempt
   /// to correct the typo and classify based on the resulting name.
   ///
   /// \param S The scope in which we're performing name lookup.
   ///
   /// \param SS The nested-name-specifier that precedes the name.
   ///
   /// \param Name The identifier. If typo correction finds an alternative name,
   /// this pointer parameter will be updated accordingly.
   ///
   /// \param NameLoc The location of the identifier.
   ///
   /// \param NextToken The token following the identifier. Used to help
   /// disambiguate the name.
   ///
   /// \param CCC The correction callback, if typo correction is desired.
   NameClassification ClassifyName(Scope *S, CXXScopeSpec &SS,
                                   IdentifierInfo *&Name, SourceLocation NameLoc,
                                   const Token &NextToken,
                                   CorrectionCandidateCallback *CCC = nullptr);
 
   /// Act on the result of classifying a name as an undeclared (ADL-only)
   /// non-type declaration.
   ExprResult ActOnNameClassifiedAsUndeclaredNonType(IdentifierInfo *Name,
                                                     SourceLocation NameLoc);
   /// Act on the result of classifying a name as an undeclared member of a
   /// dependent base class.
   ExprResult ActOnNameClassifiedAsDependentNonType(const CXXScopeSpec &SS,
                                                    IdentifierInfo *Name,
                                                    SourceLocation NameLoc,
                                                    bool IsAddressOfOperand);
   /// Act on the result of classifying a name as a specific non-type
   /// declaration.
   ExprResult ActOnNameClassifiedAsNonType(Scope *S, const CXXScopeSpec &SS,
                                           NamedDecl *Found,
                                           SourceLocation NameLoc,
                                           const Token &NextToken);
   /// Act on the result of classifying a name as an overload set.
   ExprResult ActOnNameClassifiedAsOverloadSet(Scope *S, Expr *OverloadSet);
 
   /// Describes the detailed kind of a template name. Used in diagnostics.
   enum class TemplateNameKindForDiagnostics {
     ClassTemplate,
     FunctionTemplate,
     VarTemplate,
     AliasTemplate,
     TemplateTemplateParam,
     Concept,
     DependentTemplate
   };
   TemplateNameKindForDiagnostics
   getTemplateNameKindForDiagnostics(TemplateName Name);
 
   /// Determine whether it's plausible that E was intended to be a
   /// template-name.
   bool mightBeIntendedToBeTemplateName(ExprResult E, bool &Dependent) {
     if (!getLangOpts().CPlusPlus || E.isInvalid())
       return false;
     Dependent = false;
     if (auto *DRE = dyn_cast<DeclRefExpr>(E.get()))
       return !DRE->hasExplicitTemplateArgs();
     if (auto *ME = dyn_cast<MemberExpr>(E.get()))
       return !ME->hasExplicitTemplateArgs();
     Dependent = true;
     if (auto *DSDRE = dyn_cast<DependentScopeDeclRefExpr>(E.get()))
       return !DSDRE->hasExplicitTemplateArgs();
     if (auto *DSME = dyn_cast<CXXDependentScopeMemberExpr>(E.get()))
       return !DSME->hasExplicitTemplateArgs();
     // Any additional cases recognized here should also be handled by
     // diagnoseExprIntendedAsTemplateName.
     return false;
   }
   void diagnoseExprIntendedAsTemplateName(Scope *S, ExprResult TemplateName,
                                           SourceLocation Less,
                                           SourceLocation Greater);
 
   void warnOnReservedIdentifier(const NamedDecl *D);
 
   Decl *ActOnDeclarator(Scope *S, Declarator &D);
 
   NamedDecl *HandleDeclarator(Scope *S, Declarator &D,
                               MultiTemplateParamsArg TemplateParameterLists);
   bool tryToFixVariablyModifiedVarType(TypeSourceInfo *&TInfo,
                                        QualType &T, SourceLocation Loc,
                                        unsigned FailedFoldDiagID);
   void RegisterLocallyScopedExternCDecl(NamedDecl *ND, Scope *S);
   bool DiagnoseClassNameShadow(DeclContext *DC, DeclarationNameInfo Info);
   bool diagnoseQualifiedDeclaration(CXXScopeSpec &SS, DeclContext *DC,
                                     DeclarationName Name, SourceLocation Loc,
                                     bool IsTemplateId);
   void
   diagnoseIgnoredQualifiers(unsigned DiagID, unsigned Quals,
                             SourceLocation FallbackLoc,
                             SourceLocation ConstQualLoc = SourceLocation(),
                             SourceLocation VolatileQualLoc = SourceLocation(),
                             SourceLocation RestrictQualLoc = SourceLocation(),
                             SourceLocation AtomicQualLoc = SourceLocation(),
                             SourceLocation UnalignedQualLoc = SourceLocation());
 
   static bool adjustContextForLocalExternDecl(DeclContext *&DC);
   void DiagnoseFunctionSpecifiers(const DeclSpec &DS);
   NamedDecl *getShadowedDeclaration(const TypedefNameDecl *D,
                                     const LookupResult &R);
   NamedDecl *getShadowedDeclaration(const VarDecl *D, const LookupResult &R);
   NamedDecl *getShadowedDeclaration(const BindingDecl *D,
                                     const LookupResult &R);
   void CheckShadow(NamedDecl *D, NamedDecl *ShadowedDecl,
                    const LookupResult &R);
   void CheckShadow(Scope *S, VarDecl *D);
 
   /// Warn if 'E', which is an expression that is about to be modified, refers
   /// to a shadowing declaration.
   void CheckShadowingDeclModification(Expr *E, SourceLocation Loc);
 
   void DiagnoseShadowingLambdaDecls(const sema::LambdaScopeInfo *LSI);
 
 private:
   /// Map of current shadowing declarations to shadowed declarations. Warn if
   /// it looks like the user is trying to modify the shadowing declaration.
   llvm::DenseMap<const NamedDecl *, const NamedDecl *> ShadowingDecls;
 
 public:
   void CheckCastAlign(Expr *Op, QualType T, SourceRange TRange);
   void handleTagNumbering(const TagDecl *Tag, Scope *TagScope);
   void setTagNameForLinkagePurposes(TagDecl *TagFromDeclSpec,
                                     TypedefNameDecl *NewTD);
   void CheckTypedefForVariablyModifiedType(Scope *S, TypedefNameDecl *D);
   NamedDecl* ActOnTypedefDeclarator(Scope* S, Declarator& D, DeclContext* DC,
                                     TypeSourceInfo *TInfo,
                                     LookupResult &Previous);
   NamedDecl* ActOnTypedefNameDecl(Scope* S, DeclContext* DC, TypedefNameDecl *D,
                                   LookupResult &Previous, bool &Redeclaration);
   NamedDecl *ActOnVariableDeclarator(
       Scope *S, Declarator &D, DeclContext *DC, TypeSourceInfo *TInfo,
       LookupResult &Previous, MultiTemplateParamsArg TemplateParamLists,
       bool &AddToScope, ArrayRef<BindingDecl *> Bindings = std::nullopt);
   NamedDecl *
   ActOnDecompositionDeclarator(Scope *S, Declarator &D,
                                MultiTemplateParamsArg TemplateParamLists);
   // Returns true if the variable declaration is a redeclaration
   bool CheckVariableDeclaration(VarDecl *NewVD, LookupResult &Previous);
   void CheckVariableDeclarationType(VarDecl *NewVD);
   bool DeduceVariableDeclarationType(VarDecl *VDecl, bool DirectInit,
                                      Expr *Init);
   void CheckCompleteVariableDeclaration(VarDecl *VD);
   void CheckCompleteDecompositionDeclaration(DecompositionDecl *DD);
   void MaybeSuggestAddingStaticToDecl(const FunctionDecl *D);
 
   NamedDecl* ActOnFunctionDeclarator(Scope* S, Declarator& D, DeclContext* DC,
                                      TypeSourceInfo *TInfo,
                                      LookupResult &Previous,
                                      MultiTemplateParamsArg TemplateParamLists,
                                      bool &AddToScope);
   bool AddOverriddenMethods(CXXRecordDecl *DC, CXXMethodDecl *MD);
 
   enum class CheckConstexprKind {
     /// Diagnose issues that are non-constant or that are extensions.
     Diagnose,
     /// Identify whether this function satisfies the formal rules for constexpr
     /// functions in the current lanugage mode (with no extensions).
     CheckValid
   };
 
   bool CheckConstexprFunctionDefinition(const FunctionDecl *FD,
                                         CheckConstexprKind Kind);
 
   void DiagnoseHiddenVirtualMethods(CXXMethodDecl *MD);
   void FindHiddenVirtualMethods(CXXMethodDecl *MD,
                           SmallVectorImpl<CXXMethodDecl*> &OverloadedMethods);
   void NoteHiddenVirtualMethods(CXXMethodDecl *MD,
                           SmallVectorImpl<CXXMethodDecl*> &OverloadedMethods);
   // Returns true if the function declaration is a redeclaration
   bool CheckFunctionDeclaration(Scope *S,
                                 FunctionDecl *NewFD, LookupResult &Previous,
                                 bool IsMemberSpecialization, bool DeclIsDefn);
   bool shouldLinkDependentDeclWithPrevious(Decl *D, Decl *OldDecl);
   bool canFullyTypeCheckRedeclaration(ValueDecl *NewD, ValueDecl *OldD,
                                       QualType NewT, QualType OldT);
   void CheckMain(FunctionDecl *FD, const DeclSpec &D);
   void CheckMSVCRTEntryPoint(FunctionDecl *FD);
   void CheckHLSLEntryPoint(FunctionDecl *FD);
   Attr *getImplicitCodeSegOrSectionAttrForFunction(const FunctionDecl *FD,
                                                    bool IsDefinition);
   void CheckFunctionOrTemplateParamDeclarator(Scope *S, Declarator &D);
   Decl *ActOnParamDeclarator(Scope *S, Declarator &D);
   ParmVarDecl *BuildParmVarDeclForTypedef(DeclContext *DC,
                                           SourceLocation Loc,
                                           QualType T);
   ParmVarDecl *CheckParameter(DeclContext *DC, SourceLocation StartLoc,
                               SourceLocation NameLoc, IdentifierInfo *Name,
                               QualType T, TypeSourceInfo *TSInfo,
                               StorageClass SC);
   void ActOnParamDefaultArgument(Decl *param,
                                  SourceLocation EqualLoc,
                                  Expr *defarg);
   void ActOnParamUnparsedDefaultArgument(Decl *param, SourceLocation EqualLoc,
                                          SourceLocation ArgLoc);
   void ActOnParamDefaultArgumentError(Decl *param, SourceLocation EqualLoc);
   ExprResult ConvertParamDefaultArgument(ParmVarDecl *Param, Expr *DefaultArg,
                                          SourceLocation EqualLoc);
   void SetParamDefaultArgument(ParmVarDecl *Param, Expr *DefaultArg,
                                SourceLocation EqualLoc);
 
   // Contexts where using non-trivial C union types can be disallowed. This is
   // passed to err_non_trivial_c_union_in_invalid_context.
   enum NonTrivialCUnionContext {
     // Function parameter.
     NTCUC_FunctionParam,
     // Function return.
     NTCUC_FunctionReturn,
     // Default-initialized object.
     NTCUC_DefaultInitializedObject,
     // Variable with automatic storage duration.
     NTCUC_AutoVar,
     // Initializer expression that might copy from another object.
     NTCUC_CopyInit,
     // Assignment.
     NTCUC_Assignment,
     // Compound literal.
     NTCUC_CompoundLiteral,
     // Block capture.
     NTCUC_BlockCapture,
     // lvalue-to-rvalue conversion of volatile type.
     NTCUC_LValueToRValueVolatile,
   };
 
   /// Emit diagnostics if the initializer or any of its explicit or
   /// implicitly-generated subexpressions require copying or
   /// default-initializing a type that is or contains a C union type that is
   /// non-trivial to copy or default-initialize.
   void checkNonTrivialCUnionInInitializer(const Expr *Init, SourceLocation Loc);
 
   // These flags are passed to checkNonTrivialCUnion.
   enum NonTrivialCUnionKind {
     NTCUK_Init = 0x1,
     NTCUK_Destruct = 0x2,
     NTCUK_Copy = 0x4,
   };
 
   /// Emit diagnostics if a non-trivial C union type or a struct that contains
   /// a non-trivial C union is used in an invalid context.
   void checkNonTrivialCUnion(QualType QT, SourceLocation Loc,
                              NonTrivialCUnionContext UseContext,
                              unsigned NonTrivialKind);
 
   void AddInitializerToDecl(Decl *dcl, Expr *init, bool DirectInit);
   void ActOnUninitializedDecl(Decl *dcl);
   void ActOnInitializerError(Decl *Dcl);
 
   void ActOnPureSpecifier(Decl *D, SourceLocation PureSpecLoc);
   void ActOnCXXForRangeDecl(Decl *D);
   StmtResult ActOnCXXForRangeIdentifier(Scope *S, SourceLocation IdentLoc,
                                         IdentifierInfo *Ident,
                                         ParsedAttributes &Attrs);
   void SetDeclDeleted(Decl *dcl, SourceLocation DelLoc);
   void SetDeclDefaulted(Decl *dcl, SourceLocation DefaultLoc);
   void CheckStaticLocalForDllExport(VarDecl *VD);
   void CheckThreadLocalForLargeAlignment(VarDecl *VD);
   void FinalizeDeclaration(Decl *D);
   DeclGroupPtrTy FinalizeDeclaratorGroup(Scope *S, const DeclSpec &DS,
                                          ArrayRef<Decl *> Group);
   DeclGroupPtrTy BuildDeclaratorGroup(MutableArrayRef<Decl *> Group);
 
   /// Should be called on all declarations that might have attached
   /// documentation comments.
   void ActOnDocumentableDecl(Decl *D);
   void ActOnDocumentableDecls(ArrayRef<Decl *> Group);
 
   enum class FnBodyKind {
     /// C++ [dcl.fct.def.general]p1
     /// function-body:
     ///   ctor-initializer[opt] compound-statement
     ///   function-try-block
     Other,
     ///   = default ;
     Default,
     ///   = delete ;
     Delete
   };
 
   void ActOnFinishKNRParamDeclarations(Scope *S, Declarator &D,
                                        SourceLocation LocAfterDecls);
   void CheckForFunctionRedefinition(
       FunctionDecl *FD, const FunctionDecl *EffectiveDefinition = nullptr,
       SkipBodyInfo *SkipBody = nullptr);
   Decl *ActOnStartOfFunctionDef(Scope *S, Declarator &D,
                                 MultiTemplateParamsArg TemplateParamLists,
                                 SkipBodyInfo *SkipBody = nullptr,
                                 FnBodyKind BodyKind = FnBodyKind::Other);
   Decl *ActOnStartOfFunctionDef(Scope *S, Decl *D,
                                 SkipBodyInfo *SkipBody = nullptr,
                                 FnBodyKind BodyKind = FnBodyKind::Other);
   void SetFunctionBodyKind(Decl *D, SourceLocation Loc, FnBodyKind BodyKind);
   void ActOnStartTrailingRequiresClause(Scope *S, Declarator &D);
   ExprResult ActOnFinishTrailingRequiresClause(ExprResult ConstraintExpr);
   ExprResult ActOnRequiresClause(ExprResult ConstraintExpr);
   void ActOnStartOfObjCMethodDef(Scope *S, Decl *D);
   bool isObjCMethodDecl(Decl *D) {
     return D && isa<ObjCMethodDecl>(D);
   }
 
   /// Determine whether we can delay parsing the body of a function or
   /// function template until it is used, assuming we don't care about emitting
   /// code for that function.
   ///
   /// This will be \c false if we may need the body of the function in the
   /// middle of parsing an expression (where it's impractical to switch to
   /// parsing a different function), for instance, if it's constexpr in C++11
   /// or has an 'auto' return type in C++14. These cases are essentially bugs.
   bool canDelayFunctionBody(const Declarator &D);
 
   /// Determine whether we can skip parsing the body of a function
   /// definition, assuming we don't care about analyzing its body or emitting
   /// code for that function.
   ///
   /// This will be \c false only if we may need the body of the function in
   /// order to parse the rest of the program (for instance, if it is
   /// \c constexpr in C++11 or has an 'auto' return type in C++14).
   bool canSkipFunctionBody(Decl *D);
 
   /// Determine whether \param D is function like (function or function
   /// template) for parsing.
   bool isDeclaratorFunctionLike(Declarator &D);
 
   void computeNRVO(Stmt *Body, sema::FunctionScopeInfo *Scope);
   Decl *ActOnFinishFunctionBody(Decl *Decl, Stmt *Body);
   Decl *ActOnFinishFunctionBody(Decl *Decl, Stmt *Body, bool IsInstantiation);
   Decl *ActOnSkippedFunctionBody(Decl *Decl);
   void ActOnFinishInlineFunctionDef(FunctionDecl *D);
 
   /// ActOnFinishDelayedAttribute - Invoked when we have finished parsing an
   /// attribute for which parsing is delayed.
   void ActOnFinishDelayedAttribute(Scope *S, Decl *D, ParsedAttributes &Attrs);
 
   /// Diagnose any unused parameters in the given sequence of
   /// ParmVarDecl pointers.
   void DiagnoseUnusedParameters(ArrayRef<ParmVarDecl *> Parameters);
 
   /// Diagnose whether the size of parameters or return value of a
   /// function or obj-c method definition is pass-by-value and larger than a
   /// specified threshold.
   void
   DiagnoseSizeOfParametersAndReturnValue(ArrayRef<ParmVarDecl *> Parameters,
                                          QualType ReturnTy, NamedDecl *D);
 
   void DiagnoseInvalidJumps(Stmt *Body);
   Decl *ActOnFileScopeAsmDecl(Expr *expr,
                               SourceLocation AsmLoc,
                               SourceLocation RParenLoc);
 
   Decl *ActOnTopLevelStmtDecl(Stmt *Statement);
 
   /// Handle a C++11 empty-declaration and attribute-declaration.
   Decl *ActOnEmptyDeclaration(Scope *S, const ParsedAttributesView &AttrList,
                               SourceLocation SemiLoc);
 
   enum class ModuleDeclKind {
     Interface,               ///< 'export module X;'
     Implementation,          ///< 'module X;'
     PartitionInterface,      ///< 'export module X:Y;'
     PartitionImplementation, ///< 'module X:Y;'
   };
 
   /// An enumeration to represent the transition of states in parsing module
   /// fragments and imports.  If we are not parsing a C++20 TU, or we find
   /// an error in state transition, the state is set to NotACXX20Module.
   enum class ModuleImportState {
     FirstDecl,      ///< Parsing the first decl in a TU.
     GlobalFragment, ///< after 'module;' but before 'module X;'
     ImportAllowed,  ///< after 'module X;' but before any non-import decl.
     ImportFinished, ///< after any non-import decl.
     PrivateFragmentImportAllowed,  ///< after 'module :private;' but before any
                                    ///< non-import decl.
     PrivateFragmentImportFinished, ///< after 'module :private;' but a
                                    ///< non-import decl has already been seen.
     NotACXX20Module ///< Not a C++20 TU, or an invalid state was found.
   };
 
 private:
   /// The parser has begun a translation unit to be compiled as a C++20
   /// Header Unit, helper for ActOnStartOfTranslationUnit() only.
   void HandleStartOfHeaderUnit();
 
 public:
   /// The parser has processed a module-declaration that begins the definition
   /// of a module interface or implementation.
   DeclGroupPtrTy ActOnModuleDecl(SourceLocation StartLoc,
                                  SourceLocation ModuleLoc, ModuleDeclKind MDK,
                                  ModuleIdPath Path, ModuleIdPath Partition,
                                  ModuleImportState &ImportState);
 
   /// The parser has processed a global-module-fragment declaration that begins
   /// the definition of the global module fragment of the current module unit.
   /// \param ModuleLoc The location of the 'module' keyword.
   DeclGroupPtrTy ActOnGlobalModuleFragmentDecl(SourceLocation ModuleLoc);
 
   /// The parser has processed a private-module-fragment declaration that begins
   /// the definition of the private module fragment of the current module unit.
   /// \param ModuleLoc The location of the 'module' keyword.
   /// \param PrivateLoc The location of the 'private' keyword.
   DeclGroupPtrTy ActOnPrivateModuleFragmentDecl(SourceLocation ModuleLoc,
                                                 SourceLocation PrivateLoc);
 
   /// The parser has processed a module import declaration.
   ///
   /// \param StartLoc The location of the first token in the declaration. This
   ///        could be the location of an '@', 'export', or 'import'.
   /// \param ExportLoc The location of the 'export' keyword, if any.
   /// \param ImportLoc The location of the 'import' keyword.
   /// \param Path The module toplevel name as an access path.
   /// \param IsPartition If the name is for a partition.
   DeclResult ActOnModuleImport(SourceLocation StartLoc,
                                SourceLocation ExportLoc,
                                SourceLocation ImportLoc, ModuleIdPath Path,
                                bool IsPartition = false);
   DeclResult ActOnModuleImport(SourceLocation StartLoc,
                                SourceLocation ExportLoc,
                                SourceLocation ImportLoc, Module *M,
                                ModuleIdPath Path = {});
 
   /// The parser has processed a module import translated from a
   /// #include or similar preprocessing directive.
   void ActOnModuleInclude(SourceLocation DirectiveLoc, Module *Mod);
   void BuildModuleInclude(SourceLocation DirectiveLoc, Module *Mod);
 
   /// The parsed has entered a submodule.
   void ActOnModuleBegin(SourceLocation DirectiveLoc, Module *Mod);
   /// The parser has left a submodule.
   void ActOnModuleEnd(SourceLocation DirectiveLoc, Module *Mod);
 
   /// Create an implicit import of the given module at the given
   /// source location, for error recovery, if possible.
   ///
   /// This routine is typically used when an entity found by name lookup
   /// is actually hidden within a module that we know about but the user
   /// has forgotten to import.
   void createImplicitModuleImportForErrorRecovery(SourceLocation Loc,
                                                   Module *Mod);
 
   /// Kinds of missing import. Note, the values of these enumerators correspond
   /// to %select values in diagnostics.
   enum class MissingImportKind {
     Declaration,
     Definition,
     DefaultArgument,
     ExplicitSpecialization,
     PartialSpecialization
   };
 
   /// Diagnose that the specified declaration needs to be visible but
   /// isn't, and suggest a module import that would resolve the problem.
   void diagnoseMissingImport(SourceLocation Loc, const NamedDecl *Decl,
                              MissingImportKind MIK, bool Recover = true);
   void diagnoseMissingImport(SourceLocation Loc, const NamedDecl *Decl,
                              SourceLocation DeclLoc, ArrayRef<Module *> Modules,
                              MissingImportKind MIK, bool Recover);
 
   Decl *ActOnStartExportDecl(Scope *S, SourceLocation ExportLoc,
                              SourceLocation LBraceLoc);
   Decl *ActOnFinishExportDecl(Scope *S, Decl *ExportDecl,
                               SourceLocation RBraceLoc);
 
   /// We've found a use of a templated declaration that would trigger an
   /// implicit instantiation. Check that any relevant explicit specializations
   /// and partial specializations are visible/reachable, and diagnose if not.
   void checkSpecializationVisibility(SourceLocation Loc, NamedDecl *Spec);
   void checkSpecializationReachability(SourceLocation Loc, NamedDecl *Spec);
 
   /// Retrieve a suitable printing policy for diagnostics.
   PrintingPolicy getPrintingPolicy() const {
     return getPrintingPolicy(Context, PP);
   }
 
   /// Retrieve a suitable printing policy for diagnostics.
   static PrintingPolicy getPrintingPolicy(const ASTContext &Ctx,
                                           const Preprocessor &PP);
 
   /// Scope actions.
   void ActOnPopScope(SourceLocation Loc, Scope *S);
   void ActOnTranslationUnitScope(Scope *S);
 
   Decl *ParsedFreeStandingDeclSpec(Scope *S, AccessSpecifier AS, DeclSpec &DS,
                                    const ParsedAttributesView &DeclAttrs,
                                    RecordDecl *&AnonRecord);
   Decl *ParsedFreeStandingDeclSpec(Scope *S, AccessSpecifier AS, DeclSpec &DS,
                                    const ParsedAttributesView &DeclAttrs,
                                    MultiTemplateParamsArg TemplateParams,
                                    bool IsExplicitInstantiation,
                                    RecordDecl *&AnonRecord);
 
   Decl *BuildAnonymousStructOrUnion(Scope *S, DeclSpec &DS,
                                     AccessSpecifier AS,
                                     RecordDecl *Record,
                                     const PrintingPolicy &Policy);
 
   Decl *BuildMicrosoftCAnonymousStruct(Scope *S, DeclSpec &DS,
                                        RecordDecl *Record);
 
   /// Common ways to introduce type names without a tag for use in diagnostics.
   /// Keep in sync with err_tag_reference_non_tag.
   enum NonTagKind {
     NTK_NonStruct,
     NTK_NonClass,
     NTK_NonUnion,
     NTK_NonEnum,
     NTK_Typedef,
     NTK_TypeAlias,
     NTK_Template,
     NTK_TypeAliasTemplate,
     NTK_TemplateTemplateArgument,
   };
 
   /// Given a non-tag type declaration, returns an enum useful for indicating
   /// what kind of non-tag type this is.
   NonTagKind getNonTagTypeDeclKind(const Decl *D, TagTypeKind TTK);
 
   bool isAcceptableTagRedeclaration(const TagDecl *Previous,
                                     TagTypeKind NewTag, bool isDefinition,
                                     SourceLocation NewTagLoc,
                                     const IdentifierInfo *Name);
 
   enum TagUseKind {
     TUK_Reference,   // Reference to a tag:  'struct foo *X;'
     TUK_Declaration, // Fwd decl of a tag:   'struct foo;'
     TUK_Definition,  // Definition of a tag: 'struct foo { int X; } Y;'
     TUK_Friend       // Friend declaration:  'friend struct foo;'
   };
 
   enum OffsetOfKind {
     // Not parsing a type within __builtin_offsetof.
     OOK_Outside,
     // Parsing a type within __builtin_offsetof.
     OOK_Builtin,
     // Parsing a type within macro "offsetof", defined in __buitin_offsetof
     // To improve our diagnostic message.
     OOK_Macro,
   };
 
   DeclResult ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK,
                       SourceLocation KWLoc, CXXScopeSpec &SS,
                       IdentifierInfo *Name, SourceLocation NameLoc,
                       const ParsedAttributesView &Attr, AccessSpecifier AS,
                       SourceLocation ModulePrivateLoc,
                       MultiTemplateParamsArg TemplateParameterLists,
                       bool &OwnedDecl, bool &IsDependent,
                       SourceLocation ScopedEnumKWLoc,
                       bool ScopedEnumUsesClassTag, TypeResult UnderlyingType,
                       bool IsTypeSpecifier, bool IsTemplateParamOrArg,
                       OffsetOfKind OOK, SkipBodyInfo *SkipBody = nullptr);
 
   DeclResult ActOnTemplatedFriendTag(Scope *S, SourceLocation FriendLoc,
                                      unsigned TagSpec, SourceLocation TagLoc,
                                      CXXScopeSpec &SS, IdentifierInfo *Name,
                                      SourceLocation NameLoc,
                                      const ParsedAttributesView &Attr,
                                      MultiTemplateParamsArg TempParamLists);
 
   TypeResult ActOnDependentTag(Scope *S,
                                unsigned TagSpec,
                                TagUseKind TUK,
                                const CXXScopeSpec &SS,
                                IdentifierInfo *Name,
                                SourceLocation TagLoc,
                                SourceLocation NameLoc);
 
   void ActOnDefs(Scope *S, Decl *TagD, SourceLocation DeclStart,
                  IdentifierInfo *ClassName,
                  SmallVectorImpl<Decl *> &Decls);
   Decl *ActOnField(Scope *S, Decl *TagD, SourceLocation DeclStart,
                    Declarator &D, Expr *BitfieldWidth);
 
   FieldDecl *HandleField(Scope *S, RecordDecl *TagD, SourceLocation DeclStart,
                          Declarator &D, Expr *BitfieldWidth,
                          InClassInitStyle InitStyle,
                          AccessSpecifier AS);
   MSPropertyDecl *HandleMSProperty(Scope *S, RecordDecl *TagD,
                                    SourceLocation DeclStart, Declarator &D,
                                    Expr *BitfieldWidth,
                                    InClassInitStyle InitStyle,
                                    AccessSpecifier AS,
                                    const ParsedAttr &MSPropertyAttr);
 
   FieldDecl *CheckFieldDecl(DeclarationName Name, QualType T,
                             TypeSourceInfo *TInfo,
                             RecordDecl *Record, SourceLocation Loc,
                             bool Mutable, Expr *BitfieldWidth,
                             InClassInitStyle InitStyle,
                             SourceLocation TSSL,
                             AccessSpecifier AS, NamedDecl *PrevDecl,
                             Declarator *D = nullptr);
 
   bool CheckNontrivialField(FieldDecl *FD);
   void DiagnoseNontrivial(const CXXRecordDecl *Record, CXXSpecialMember CSM);
 
   enum TrivialABIHandling {
     /// The triviality of a method unaffected by "trivial_abi".
     TAH_IgnoreTrivialABI,
 
     /// The triviality of a method affected by "trivial_abi".
     TAH_ConsiderTrivialABI
   };
 
   bool SpecialMemberIsTrivial(CXXMethodDecl *MD, CXXSpecialMember CSM,
                               TrivialABIHandling TAH = TAH_IgnoreTrivialABI,
                               bool Diagnose = false);
 
   /// For a defaulted function, the kind of defaulted function that it is.
   class DefaultedFunctionKind {
     CXXSpecialMember SpecialMember : 8;
     DefaultedComparisonKind Comparison : 8;
 
   public:
     DefaultedFunctionKind()
         : SpecialMember(CXXInvalid), Comparison(DefaultedComparisonKind::None) {
     }
     DefaultedFunctionKind(CXXSpecialMember CSM)
         : SpecialMember(CSM), Comparison(DefaultedComparisonKind::None) {}
     DefaultedFunctionKind(DefaultedComparisonKind Comp)
         : SpecialMember(CXXInvalid), Comparison(Comp) {}
 
     bool isSpecialMember() const { return SpecialMember != CXXInvalid; }
     bool isComparison() const {
       return Comparison != DefaultedComparisonKind::None;
     }
 
     explicit operator bool() const {
       return isSpecialMember() || isComparison();
     }
 
     CXXSpecialMember asSpecialMember() const { return SpecialMember; }
     DefaultedComparisonKind asComparison() const { return Comparison; }
 
     /// Get the index of this function kind for use in diagnostics.
     unsigned getDiagnosticIndex() const {
       static_assert(CXXInvalid > CXXDestructor,
                     "invalid should have highest index");
       static_assert((unsigned)DefaultedComparisonKind::None == 0,
                     "none should be equal to zero");
       return SpecialMember + (unsigned)Comparison;
     }
   };
 
   DefaultedFunctionKind getDefaultedFunctionKind(const FunctionDecl *FD);
 
   CXXSpecialMember getSpecialMember(const CXXMethodDecl *MD) {
     return getDefaultedFunctionKind(MD).asSpecialMember();
   }
   DefaultedComparisonKind getDefaultedComparisonKind(const FunctionDecl *FD) {
     return getDefaultedFunctionKind(FD).asComparison();
   }
 
   void ActOnLastBitfield(SourceLocation DeclStart,
                          SmallVectorImpl<Decl *> &AllIvarDecls);
   Decl *ActOnIvar(Scope *S, SourceLocation DeclStart,
                   Declarator &D, Expr *BitfieldWidth,
                   tok::ObjCKeywordKind visibility);
 
   // This is used for both record definitions and ObjC interface declarations.
   void ActOnFields(Scope *S, SourceLocation RecLoc, Decl *TagDecl,
                    ArrayRef<Decl *> Fields, SourceLocation LBrac,
                    SourceLocation RBrac, const ParsedAttributesView &AttrList);
 
   /// ActOnTagStartDefinition - Invoked when we have entered the
   /// scope of a tag's definition (e.g., for an enumeration, class,
   /// struct, or union).
   void ActOnTagStartDefinition(Scope *S, Decl *TagDecl);
 
   /// Perform ODR-like check for C/ObjC when merging tag types from modules.
   /// Differently from C++, actually parse the body and reject / error out
   /// in case of a structural mismatch.
   bool ActOnDuplicateDefinition(Decl *Prev, SkipBodyInfo &SkipBody);
 
   /// Check ODR hashes for C/ObjC when merging types from modules.
   /// Differently from C++, actually parse the body and reject in case
   /// of a mismatch.
   template <typename T,
             typename = std::enable_if_t<std::is_base_of<NamedDecl, T>::value>>
   bool ActOnDuplicateODRHashDefinition(T *Duplicate, T *Previous) {
     if (Duplicate->getODRHash() != Previous->getODRHash())
       return false;
 
     // Make the previous decl visible.
     makeMergedDefinitionVisible(Previous);
     return true;
   }
 
   typedef void *SkippedDefinitionContext;
 
   /// Invoked when we enter a tag definition that we're skipping.
   SkippedDefinitionContext ActOnTagStartSkippedDefinition(Scope *S, Decl *TD);
 
   void ActOnObjCContainerStartDefinition(ObjCContainerDecl *IDecl);
 
   /// ActOnStartCXXMemberDeclarations - Invoked when we have parsed a
   /// C++ record definition's base-specifiers clause and are starting its
   /// member declarations.
   void ActOnStartCXXMemberDeclarations(Scope *S, Decl *TagDecl,
                                        SourceLocation FinalLoc,
                                        bool IsFinalSpelledSealed,
                                        bool IsAbstract,
                                        SourceLocation LBraceLoc);
 
   /// ActOnTagFinishDefinition - Invoked once we have finished parsing
   /// the definition of a tag (enumeration, class, struct, or union).
   void ActOnTagFinishDefinition(Scope *S, Decl *TagDecl,
                                 SourceRange BraceRange);
 
   void ActOnTagFinishSkippedDefinition(SkippedDefinitionContext Context);
 
   void ActOnObjCContainerFinishDefinition();
 
   /// Invoked when we must temporarily exit the objective-c container
   /// scope for parsing/looking-up C constructs.
   ///
   /// Must be followed by a call to \see ActOnObjCReenterContainerContext
   void ActOnObjCTemporaryExitContainerContext(ObjCContainerDecl *ObjCCtx);
   void ActOnObjCReenterContainerContext(ObjCContainerDecl *ObjCCtx);
 
   /// ActOnTagDefinitionError - Invoked when there was an unrecoverable
   /// error parsing the definition of a tag.
   void ActOnTagDefinitionError(Scope *S, Decl *TagDecl);
 
   EnumConstantDecl *CheckEnumConstant(EnumDecl *Enum,
                                       EnumConstantDecl *LastEnumConst,
                                       SourceLocation IdLoc,
                                       IdentifierInfo *Id,
                                       Expr *val);
   bool CheckEnumUnderlyingType(TypeSourceInfo *TI);
   bool CheckEnumRedeclaration(SourceLocation EnumLoc, bool IsScoped,
                               QualType EnumUnderlyingTy, bool IsFixed,
                               const EnumDecl *Prev);
 
   /// Determine whether the body of an anonymous enumeration should be skipped.
   /// \param II The name of the first enumerator.
   SkipBodyInfo shouldSkipAnonEnumBody(Scope *S, IdentifierInfo *II,
                                       SourceLocation IILoc);
 
   Decl *ActOnEnumConstant(Scope *S, Decl *EnumDecl, Decl *LastEnumConstant,
                           SourceLocation IdLoc, IdentifierInfo *Id,
                           const ParsedAttributesView &Attrs,
                           SourceLocation EqualLoc, Expr *Val);
   void ActOnEnumBody(SourceLocation EnumLoc, SourceRange BraceRange,
                      Decl *EnumDecl, ArrayRef<Decl *> Elements, Scope *S,
                      const ParsedAttributesView &Attr);
 
   /// Set the current declaration context until it gets popped.
   void PushDeclContext(Scope *S, DeclContext *DC);
   void PopDeclContext();
 
   /// EnterDeclaratorContext - Used when we must lookup names in the context
   /// of a declarator's nested name specifier.
   void EnterDeclaratorContext(Scope *S, DeclContext *DC);
   void ExitDeclaratorContext(Scope *S);
 
   /// Enter a template parameter scope, after it's been associated with a particular
   /// DeclContext. Causes lookup within the scope to chain through enclosing contexts
   /// in the correct order.
   void EnterTemplatedContext(Scope *S, DeclContext *DC);
 
   /// Push the parameters of D, which must be a function, into scope.
   void ActOnReenterFunctionContext(Scope* S, Decl* D);
   void ActOnExitFunctionContext();
 
   /// If \p AllowLambda is true, treat lambda as function.
   DeclContext *getFunctionLevelDeclContext(bool AllowLambda = false) const;
 
   /// Returns a pointer to the innermost enclosing function, or nullptr if the
   /// current context is not inside a function. If \p AllowLambda is true,
   /// this can return the call operator of an enclosing lambda, otherwise
   /// lambdas are skipped when looking for an enclosing function.
   FunctionDecl *getCurFunctionDecl(bool AllowLambda = false) const;
 
   /// getCurMethodDecl - If inside of a method body, this returns a pointer to
   /// the method decl for the method being parsed.  If we're currently
   /// in a 'block', this returns the containing context.
   ObjCMethodDecl *getCurMethodDecl();
 
   /// getCurFunctionOrMethodDecl - Return the Decl for the current ObjC method
   /// or C function we're in, otherwise return null.  If we're currently
   /// in a 'block', this returns the containing context.
   NamedDecl *getCurFunctionOrMethodDecl() const;
 
   /// Add this decl to the scope shadowed decl chains.
   void PushOnScopeChains(NamedDecl *D, Scope *S, bool AddToContext = true);
 
   /// isDeclInScope - If 'Ctx' is a function/method, isDeclInScope returns true
   /// if 'D' is in Scope 'S', otherwise 'S' is ignored and isDeclInScope returns
   /// true if 'D' belongs to the given declaration context.
   ///
   /// \param AllowInlineNamespace If \c true, allow the declaration to be in the
   ///        enclosing namespace set of the context, rather than contained
   ///        directly within it.
   bool isDeclInScope(NamedDecl *D, DeclContext *Ctx, Scope *S = nullptr,
                      bool AllowInlineNamespace = false) const;
 
   /// Finds the scope corresponding to the given decl context, if it
   /// happens to be an enclosing scope.  Otherwise return NULL.
   static Scope *getScopeForDeclContext(Scope *S, DeclContext *DC);
 
   /// Subroutines of ActOnDeclarator().
   TypedefDecl *ParseTypedefDecl(Scope *S, Declarator &D, QualType T,
                                 TypeSourceInfo *TInfo);
   bool isIncompatibleTypedef(TypeDecl *Old, TypedefNameDecl *New);
 
   /// Describes the kind of merge to perform for availability
   /// attributes (including "deprecated", "unavailable", and "availability").
   enum AvailabilityMergeKind {
     /// Don't merge availability attributes at all.
     AMK_None,
     /// Merge availability attributes for a redeclaration, which requires
     /// an exact match.
     AMK_Redeclaration,
     /// Merge availability attributes for an override, which requires
     /// an exact match or a weakening of constraints.
     AMK_Override,
     /// Merge availability attributes for an implementation of
     /// a protocol requirement.
     AMK_ProtocolImplementation,
     /// Merge availability attributes for an implementation of
     /// an optional protocol requirement.
     AMK_OptionalProtocolImplementation
   };
 
   /// Describes the kind of priority given to an availability attribute.
   ///
   /// The sum of priorities deteremines the final priority of the attribute.
   /// The final priority determines how the attribute will be merged.
   /// An attribute with a lower priority will always remove higher priority
   /// attributes for the specified platform when it is being applied. An
   /// attribute with a higher priority will not be applied if the declaration
   /// already has an availability attribute with a lower priority for the
   /// specified platform. The final prirority values are not expected to match
   /// the values in this enumeration, but instead should be treated as a plain
   /// integer value. This enumeration just names the priority weights that are
   /// used to calculate that final vaue.
   enum AvailabilityPriority : int {
     /// The availability attribute was specified explicitly next to the
     /// declaration.
     AP_Explicit = 0,
 
     /// The availability attribute was applied using '#pragma clang attribute'.
     AP_PragmaClangAttribute = 1,
 
     /// The availability attribute for a specific platform was inferred from
     /// an availability attribute for another platform.
     AP_InferredFromOtherPlatform = 2
   };
 
   /// Attribute merging methods. Return true if a new attribute was added.
   AvailabilityAttr *
   mergeAvailabilityAttr(NamedDecl *D, const AttributeCommonInfo &CI,
                         IdentifierInfo *Platform, bool Implicit,
                         VersionTuple Introduced, VersionTuple Deprecated,
                         VersionTuple Obsoleted, bool IsUnavailable,
                         StringRef Message, bool IsStrict, StringRef Replacement,
                         AvailabilityMergeKind AMK, int Priority);
   TypeVisibilityAttr *
   mergeTypeVisibilityAttr(Decl *D, const AttributeCommonInfo &CI,
                           TypeVisibilityAttr::VisibilityType Vis);
   VisibilityAttr *mergeVisibilityAttr(Decl *D, const AttributeCommonInfo &CI,
                                       VisibilityAttr::VisibilityType Vis);
   UuidAttr *mergeUuidAttr(Decl *D, const AttributeCommonInfo &CI,
                           StringRef UuidAsWritten, MSGuidDecl *GuidDecl);
   DLLImportAttr *mergeDLLImportAttr(Decl *D, const AttributeCommonInfo &CI);
   DLLExportAttr *mergeDLLExportAttr(Decl *D, const AttributeCommonInfo &CI);
   MSInheritanceAttr *mergeMSInheritanceAttr(Decl *D,
                                             const AttributeCommonInfo &CI,
                                             bool BestCase,
                                             MSInheritanceModel Model);
   ErrorAttr *mergeErrorAttr(Decl *D, const AttributeCommonInfo &CI,
                             StringRef NewUserDiagnostic);
   FormatAttr *mergeFormatAttr(Decl *D, const AttributeCommonInfo &CI,
                               IdentifierInfo *Format, int FormatIdx,
                               int FirstArg);
   SectionAttr *mergeSectionAttr(Decl *D, const AttributeCommonInfo &CI,
                                 StringRef Name);
   CodeSegAttr *mergeCodeSegAttr(Decl *D, const AttributeCommonInfo &CI,
                                 StringRef Name);
   AlwaysInlineAttr *mergeAlwaysInlineAttr(Decl *D,
                                           const AttributeCommonInfo &CI,
                                           const IdentifierInfo *Ident);
   MinSizeAttr *mergeMinSizeAttr(Decl *D, const AttributeCommonInfo &CI);
   SwiftNameAttr *mergeSwiftNameAttr(Decl *D, const SwiftNameAttr &SNA,
                                     StringRef Name);
   OptimizeNoneAttr *mergeOptimizeNoneAttr(Decl *D,
                                           const AttributeCommonInfo &CI);
   InternalLinkageAttr *mergeInternalLinkageAttr(Decl *D, const ParsedAttr &AL);
   InternalLinkageAttr *mergeInternalLinkageAttr(Decl *D,
                                                 const InternalLinkageAttr &AL);
   WebAssemblyImportNameAttr *mergeImportNameAttr(
       Decl *D, const WebAssemblyImportNameAttr &AL);
   WebAssemblyImportModuleAttr *mergeImportModuleAttr(
       Decl *D, const WebAssemblyImportModuleAttr &AL);
   EnforceTCBAttr *mergeEnforceTCBAttr(Decl *D, const EnforceTCBAttr &AL);
   EnforceTCBLeafAttr *mergeEnforceTCBLeafAttr(Decl *D,
                                               const EnforceTCBLeafAttr &AL);
   BTFDeclTagAttr *mergeBTFDeclTagAttr(Decl *D, const BTFDeclTagAttr &AL);
   HLSLNumThreadsAttr *mergeHLSLNumThreadsAttr(Decl *D,
                                               const AttributeCommonInfo &AL,
                                               int X, int Y, int Z);
   HLSLShaderAttr *mergeHLSLShaderAttr(Decl *D, const AttributeCommonInfo &AL,
                                       HLSLShaderAttr::ShaderType ShaderType);
 
   void mergeDeclAttributes(NamedDecl *New, Decl *Old,
                            AvailabilityMergeKind AMK = AMK_Redeclaration);
   void MergeTypedefNameDecl(Scope *S, TypedefNameDecl *New,
                             LookupResult &OldDecls);
   bool MergeFunctionDecl(FunctionDecl *New, NamedDecl *&Old, Scope *S,
                          bool MergeTypeWithOld, bool NewDeclIsDefn);
   bool MergeCompatibleFunctionDecls(FunctionDecl *New, FunctionDecl *Old,
                                     Scope *S, bool MergeTypeWithOld);
   void mergeObjCMethodDecls(ObjCMethodDecl *New, ObjCMethodDecl *Old);
   void MergeVarDecl(VarDecl *New, LookupResult &Previous);
   void MergeVarDeclTypes(VarDecl *New, VarDecl *Old, bool MergeTypeWithOld);
   void MergeVarDeclExceptionSpecs(VarDecl *New, VarDecl *Old);
   bool checkVarDeclRedefinition(VarDecl *OldDefn, VarDecl *NewDefn);
   void notePreviousDefinition(const NamedDecl *Old, SourceLocation New);
   bool MergeCXXFunctionDecl(FunctionDecl *New, FunctionDecl *Old, Scope *S);
 
   // AssignmentAction - This is used by all the assignment diagnostic functions
   // to represent what is actually causing the operation
   enum AssignmentAction {
     AA_Assigning,
     AA_Passing,
     AA_Returning,
     AA_Converting,
     AA_Initializing,
     AA_Sending,
     AA_Casting,
     AA_Passing_CFAudited
   };
 
   /// C++ Overloading.
   enum OverloadKind {
     /// This is a legitimate overload: the existing declarations are
     /// functions or function templates with different signatures.
     Ovl_Overload,
 
     /// This is not an overload because the signature exactly matches
     /// an existing declaration.
     Ovl_Match,
 
     /// This is not an overload because the lookup results contain a
     /// non-function.
     Ovl_NonFunction
   };
   OverloadKind CheckOverload(Scope *S,
                              FunctionDecl *New,
                              const LookupResult &OldDecls,
                              NamedDecl *&OldDecl,
                              bool UseMemberUsingDeclRules);
   bool IsOverload(FunctionDecl *New, FunctionDecl *Old,
                   bool UseMemberUsingDeclRules, bool ConsiderCudaAttrs = true,
                   bool ConsiderRequiresClauses = true);
 
   // Calculates whether the expression Constraint depends on an enclosing
   // template, for the purposes of [temp.friend] p9.
   // TemplateDepth is the 'depth' of the friend function, which is used to
   // compare whether a declaration reference is referring to a containing
   // template, or just the current friend function. A 'lower' TemplateDepth in
   // the AST refers to a 'containing' template. As the constraint is
   // uninstantiated, this is relative to the 'top' of the TU.
   bool
   ConstraintExpressionDependsOnEnclosingTemplate(const FunctionDecl *Friend,
                                                  unsigned TemplateDepth,
                                                  const Expr *Constraint);
 
   // Calculates whether the friend function depends on an enclosing template for
   // the purposes of [temp.friend] p9.
   bool FriendConstraintsDependOnEnclosingTemplate(const FunctionDecl *FD);
 
   // Calculates whether two constraint expressions are equal irrespective of a
   // difference in 'depth'. This takes a pair of optional 'NamedDecl's 'Old' and
   // 'New', which are the "source" of the constraint, since this is necessary
   // for figuring out the relative 'depth' of the constraint. The depth of the
   // 'primary template' and the 'instantiated from' templates aren't necessarily
   // the same, such as a case when one is a 'friend' defined in a class.
   bool AreConstraintExpressionsEqual(const NamedDecl *Old,
                                      const Expr *OldConstr,
                                      const NamedDecl *New,
                                      const Expr *NewConstr);
 
   enum class AllowedExplicit {
     /// Allow no explicit functions to be used.
     None,
     /// Allow explicit conversion functions but not explicit constructors.
     Conversions,
     /// Allow both explicit conversion functions and explicit constructors.
     All
   };
 
   ImplicitConversionSequence
   TryImplicitConversion(Expr *From, QualType ToType,
                         bool SuppressUserConversions,
                         AllowedExplicit AllowExplicit,
                         bool InOverloadResolution,
                         bool CStyle,
                         bool AllowObjCWritebackConversion);
 
   bool IsIntegralPromotion(Expr *From, QualType FromType, QualType ToType);
   bool IsFloatingPointPromotion(QualType FromType, QualType ToType);
   bool IsComplexPromotion(QualType FromType, QualType ToType);
   bool IsPointerConversion(Expr *From, QualType FromType, QualType ToType,
                            bool InOverloadResolution,
                            QualType& ConvertedType, bool &IncompatibleObjC);
   bool isObjCPointerConversion(QualType FromType, QualType ToType,
                                QualType& ConvertedType, bool &IncompatibleObjC);
   bool isObjCWritebackConversion(QualType FromType, QualType ToType,
                                  QualType &ConvertedType);
   bool IsBlockPointerConversion(QualType FromType, QualType ToType,
                                 QualType& ConvertedType);
   bool FunctionParamTypesAreEqual(const FunctionProtoType *OldType,
                                   const FunctionProtoType *NewType,
                                   unsigned *ArgPos = nullptr,
                                   bool Reversed = false);
   void HandleFunctionTypeMismatch(PartialDiagnostic &PDiag,
                                   QualType FromType, QualType ToType);
 
   void maybeExtendBlockObject(ExprResult &E);
   CastKind PrepareCastToObjCObjectPointer(ExprResult &E);
   bool CheckPointerConversion(Expr *From, QualType ToType,
                               CastKind &Kind,
                               CXXCastPath& BasePath,
                               bool IgnoreBaseAccess,
                               bool Diagnose = true);
   bool IsMemberPointerConversion(Expr *From, QualType FromType, QualType ToType,
                                  bool InOverloadResolution,
                                  QualType &ConvertedType);
   bool CheckMemberPointerConversion(Expr *From, QualType ToType,
                                     CastKind &Kind,
                                     CXXCastPath &BasePath,
                                     bool IgnoreBaseAccess);
   bool IsQualificationConversion(QualType FromType, QualType ToType,
                                  bool CStyle, bool &ObjCLifetimeConversion);
   bool IsFunctionConversion(QualType FromType, QualType ToType,
                             QualType &ResultTy);
   bool DiagnoseMultipleUserDefinedConversion(Expr *From, QualType ToType);
   bool isSameOrCompatibleFunctionType(QualType Param, QualType Arg);
 
   bool CanPerformAggregateInitializationForOverloadResolution(
       const InitializedEntity &Entity, InitListExpr *From);
 
   bool IsStringInit(Expr *Init, const ArrayType *AT);
 
   bool CanPerformCopyInitialization(const InitializedEntity &Entity,
                                     ExprResult Init);
   ExprResult PerformCopyInitialization(const InitializedEntity &Entity,
                                        SourceLocation EqualLoc,
                                        ExprResult Init,
                                        bool TopLevelOfInitList = false,
                                        bool AllowExplicit = false);
   ExprResult PerformObjectArgumentInitialization(Expr *From,
                                                  NestedNameSpecifier *Qualifier,
                                                  NamedDecl *FoundDecl,
                                                  CXXMethodDecl *Method);
 
   /// Check that the lifetime of the initializer (and its subobjects) is
   /// sufficient for initializing the entity, and perform lifetime extension
   /// (when permitted) if not.
   void checkInitializerLifetime(const InitializedEntity &Entity, Expr *Init);
 
   ExprResult PerformContextuallyConvertToBool(Expr *From);
   ExprResult PerformContextuallyConvertToObjCPointer(Expr *From);
 
   /// Contexts in which a converted constant expression is required.
   enum CCEKind {
     CCEK_CaseValue,    ///< Expression in a case label.
     CCEK_Enumerator,   ///< Enumerator value with fixed underlying type.
     CCEK_TemplateArg,  ///< Value of a non-type template parameter.
     CCEK_ArrayBound,   ///< Array bound in array declarator or new-expression.
     CCEK_ExplicitBool, ///< Condition in an explicit(bool) specifier.
     CCEK_Noexcept,     ///< Condition in a noexcept(bool) specifier.
     CCEK_StaticAssertMessageSize, ///< Call to size() in a static assert
                                   ///< message.
     CCEK_StaticAssertMessageData, ///< Call to data() in a static assert
                                   ///< message.
   };
 
   ExprResult BuildConvertedConstantExpression(Expr *From, QualType T,
                                               CCEKind CCE,
                                               NamedDecl *Dest = nullptr);
 
   ExprResult CheckConvertedConstantExpression(Expr *From, QualType T,
                                               llvm::APSInt &Value, CCEKind CCE);
   ExprResult CheckConvertedConstantExpression(Expr *From, QualType T,
                                               APValue &Value, CCEKind CCE,
                                               NamedDecl *Dest = nullptr);
 
   /// Abstract base class used to perform a contextual implicit
   /// conversion from an expression to any type passing a filter.
   class ContextualImplicitConverter {
   public:
     bool Suppress;
     bool SuppressConversion;
 
     ContextualImplicitConverter(bool Suppress = false,
                                 bool SuppressConversion = false)
         : Suppress(Suppress), SuppressConversion(SuppressConversion) {}
 
     /// Determine whether the specified type is a valid destination type
     /// for this conversion.
     virtual bool match(QualType T) = 0;
 
     /// Emits a diagnostic complaining that the expression does not have
     /// integral or enumeration type.
     virtual SemaDiagnosticBuilder
     diagnoseNoMatch(Sema &S, SourceLocation Loc, QualType T) = 0;
 
     /// Emits a diagnostic when the expression has incomplete class type.
     virtual SemaDiagnosticBuilder
     diagnoseIncomplete(Sema &S, SourceLocation Loc, QualType T) = 0;
 
     /// Emits a diagnostic when the only matching conversion function
     /// is explicit.
     virtual SemaDiagnosticBuilder diagnoseExplicitConv(
         Sema &S, SourceLocation Loc, QualType T, QualType ConvTy) = 0;
 
     /// Emits a note for the explicit conversion function.
     virtual SemaDiagnosticBuilder
     noteExplicitConv(Sema &S, CXXConversionDecl *Conv, QualType ConvTy) = 0;
 
     /// Emits a diagnostic when there are multiple possible conversion
     /// functions.
     virtual SemaDiagnosticBuilder
     diagnoseAmbiguous(Sema &S, SourceLocation Loc, QualType T) = 0;
 
     /// Emits a note for one of the candidate conversions.
     virtual SemaDiagnosticBuilder
     noteAmbiguous(Sema &S, CXXConversionDecl *Conv, QualType ConvTy) = 0;
 
     /// Emits a diagnostic when we picked a conversion function
     /// (for cases when we are not allowed to pick a conversion function).
     virtual SemaDiagnosticBuilder diagnoseConversion(
         Sema &S, SourceLocation Loc, QualType T, QualType ConvTy) = 0;
 
     virtual ~ContextualImplicitConverter() {}
   };
 
   class ICEConvertDiagnoser : public ContextualImplicitConverter {
     bool AllowScopedEnumerations;
 
   public:
     ICEConvertDiagnoser(bool AllowScopedEnumerations,
                         bool Suppress, bool SuppressConversion)
         : ContextualImplicitConverter(Suppress, SuppressConversion),
           AllowScopedEnumerations(AllowScopedEnumerations) {}
 
     /// Match an integral or (possibly scoped) enumeration type.
     bool match(QualType T) override;
 
     SemaDiagnosticBuilder
     diagnoseNoMatch(Sema &S, SourceLocation Loc, QualType T) override {
       return diagnoseNotInt(S, Loc, T);
     }
 
     /// Emits a diagnostic complaining that the expression does not have
     /// integral or enumeration type.
     virtual SemaDiagnosticBuilder
     diagnoseNotInt(Sema &S, SourceLocation Loc, QualType T) = 0;
   };
 
   /// Perform a contextual implicit conversion.
   ExprResult PerformContextualImplicitConversion(
       SourceLocation Loc, Expr *FromE, ContextualImplicitConverter &Converter);
 
 
   enum ObjCSubscriptKind {
     OS_Array,
     OS_Dictionary,
     OS_Error
   };
   ObjCSubscriptKind CheckSubscriptingKind(Expr *FromE);
 
   // Note that LK_String is intentionally after the other literals, as
   // this is used for diagnostics logic.
   enum ObjCLiteralKind {
     LK_Array,
     LK_Dictionary,
     LK_Numeric,
     LK_Boxed,
     LK_String,
     LK_Block,
     LK_None
   };
   ObjCLiteralKind CheckLiteralKind(Expr *FromE);
 
   ExprResult PerformObjectMemberConversion(Expr *From,
                                            NestedNameSpecifier *Qualifier,
                                            NamedDecl *FoundDecl,
                                            NamedDecl *Member);
 
   // Members have to be NamespaceDecl* or TranslationUnitDecl*.
   // TODO: make this is a typesafe union.
   typedef llvm::SmallSetVector<DeclContext   *, 16> AssociatedNamespaceSet;
   typedef llvm::SmallSetVector<CXXRecordDecl *, 16> AssociatedClassSet;
 
   using ADLCallKind = CallExpr::ADLCallKind;
 
   void AddOverloadCandidate(
       FunctionDecl *Function, DeclAccessPair FoundDecl, ArrayRef<Expr *> Args,
       OverloadCandidateSet &CandidateSet, bool SuppressUserConversions = false,
       bool PartialOverloading = false, bool AllowExplicit = true,
       bool AllowExplicitConversion = false,
       ADLCallKind IsADLCandidate = ADLCallKind::NotADL,
       ConversionSequenceList EarlyConversions = std::nullopt,
       OverloadCandidateParamOrder PO = {},
       bool AggregateCandidateDeduction = false);
   void AddFunctionCandidates(const UnresolvedSetImpl &Functions,
                       ArrayRef<Expr *> Args,
                       OverloadCandidateSet &CandidateSet,
                       TemplateArgumentListInfo *ExplicitTemplateArgs = nullptr,
                       bool SuppressUserConversions = false,
                       bool PartialOverloading = false,
                       bool FirstArgumentIsBase = false);
   void AddMethodCandidate(DeclAccessPair FoundDecl,
                           QualType ObjectType,
                           Expr::Classification ObjectClassification,
                           ArrayRef<Expr *> Args,
                           OverloadCandidateSet& CandidateSet,
                           bool SuppressUserConversion = false,
                           OverloadCandidateParamOrder PO = {});
   void
   AddMethodCandidate(CXXMethodDecl *Method, DeclAccessPair FoundDecl,
                      CXXRecordDecl *ActingContext, QualType ObjectType,
                      Expr::Classification ObjectClassification,
                      ArrayRef<Expr *> Args, OverloadCandidateSet &CandidateSet,
                      bool SuppressUserConversions = false,
                      bool PartialOverloading = false,
                      ConversionSequenceList EarlyConversions = std::nullopt,
                      OverloadCandidateParamOrder PO = {});
   void AddMethodTemplateCandidate(FunctionTemplateDecl *MethodTmpl,
                                   DeclAccessPair FoundDecl,
                                   CXXRecordDecl *ActingContext,
                                  TemplateArgumentListInfo *ExplicitTemplateArgs,
                                   QualType ObjectType,
                                   Expr::Classification ObjectClassification,
                                   ArrayRef<Expr *> Args,
                                   OverloadCandidateSet& CandidateSet,
                                   bool SuppressUserConversions = false,
                                   bool PartialOverloading = false,
                                   OverloadCandidateParamOrder PO = {});
   void AddTemplateOverloadCandidate(
       FunctionTemplateDecl *FunctionTemplate, DeclAccessPair FoundDecl,
       TemplateArgumentListInfo *ExplicitTemplateArgs, ArrayRef<Expr *> Args,
       OverloadCandidateSet &CandidateSet, bool SuppressUserConversions = false,
       bool PartialOverloading = false, bool AllowExplicit = true,
       ADLCallKind IsADLCandidate = ADLCallKind::NotADL,
       OverloadCandidateParamOrder PO = {},
       bool AggregateCandidateDeduction = false);
   bool CheckNonDependentConversions(
       FunctionTemplateDecl *FunctionTemplate, ArrayRef<QualType> ParamTypes,
       ArrayRef<Expr *> Args, OverloadCandidateSet &CandidateSet,
       ConversionSequenceList &Conversions, bool SuppressUserConversions,
       CXXRecordDecl *ActingContext = nullptr, QualType ObjectType = QualType(),
       Expr::Classification ObjectClassification = {},
       OverloadCandidateParamOrder PO = {});
   void AddConversionCandidate(
       CXXConversionDecl *Conversion, DeclAccessPair FoundDecl,
       CXXRecordDecl *ActingContext, Expr *From, QualType ToType,
       OverloadCandidateSet &CandidateSet, bool AllowObjCConversionOnExplicit,
       bool AllowExplicit, bool AllowResultConversion = true);
   void AddTemplateConversionCandidate(
       FunctionTemplateDecl *FunctionTemplate, DeclAccessPair FoundDecl,
       CXXRecordDecl *ActingContext, Expr *From, QualType ToType,
       OverloadCandidateSet &CandidateSet, bool AllowObjCConversionOnExplicit,
       bool AllowExplicit, bool AllowResultConversion = true);
   void AddSurrogateCandidate(CXXConversionDecl *Conversion,
                              DeclAccessPair FoundDecl,
                              CXXRecordDecl *ActingContext,
                              const FunctionProtoType *Proto,
                              Expr *Object, ArrayRef<Expr *> Args,
                              OverloadCandidateSet& CandidateSet);
   void AddNonMemberOperatorCandidates(
       const UnresolvedSetImpl &Functions, ArrayRef<Expr *> Args,
       OverloadCandidateSet &CandidateSet,
       TemplateArgumentListInfo *ExplicitTemplateArgs = nullptr);
   void AddMemberOperatorCandidates(OverloadedOperatorKind Op,
                                    SourceLocation OpLoc, ArrayRef<Expr *> Args,
                                    OverloadCandidateSet &CandidateSet,
                                    OverloadCandidateParamOrder PO = {});
   void AddBuiltinCandidate(QualType *ParamTys, ArrayRef<Expr *> Args,
                            OverloadCandidateSet& CandidateSet,
                            bool IsAssignmentOperator = false,
                            unsigned NumContextualBoolArguments = 0);
   void AddBuiltinOperatorCandidates(OverloadedOperatorKind Op,
                                     SourceLocation OpLoc, ArrayRef<Expr *> Args,
                                     OverloadCandidateSet& CandidateSet);
   void AddArgumentDependentLookupCandidates(DeclarationName Name,
                                             SourceLocation Loc,
                                             ArrayRef<Expr *> Args,
                                 TemplateArgumentListInfo *ExplicitTemplateArgs,
                                             OverloadCandidateSet& CandidateSet,
                                             bool PartialOverloading = false);
 
   // Emit as a 'note' the specific overload candidate
   void NoteOverloadCandidate(
       const NamedDecl *Found, const FunctionDecl *Fn,
       OverloadCandidateRewriteKind RewriteKind = OverloadCandidateRewriteKind(),
       QualType DestType = QualType(), bool TakingAddress = false);
 
   // Emit as a series of 'note's all template and non-templates identified by
   // the expression Expr
   void NoteAllOverloadCandidates(Expr *E, QualType DestType = QualType(),
                                  bool TakingAddress = false);
 
   /// Check the enable_if expressions on the given function. Returns the first
   /// failing attribute, or NULL if they were all successful.
   EnableIfAttr *CheckEnableIf(FunctionDecl *Function, SourceLocation CallLoc,
                               ArrayRef<Expr *> Args,
                               bool MissingImplicitThis = false);
 
   /// Find the failed Boolean condition within a given Boolean
   /// constant expression, and describe it with a string.
   std::pair<Expr *, std::string> findFailedBooleanCondition(Expr *Cond);
 
   /// Emit diagnostics for the diagnose_if attributes on Function, ignoring any
   /// non-ArgDependent DiagnoseIfAttrs.
   ///
   /// Argument-dependent diagnose_if attributes should be checked each time a
   /// function is used as a direct callee of a function call.
   ///
   /// Returns true if any errors were emitted.
   bool diagnoseArgDependentDiagnoseIfAttrs(const FunctionDecl *Function,
                                            const Expr *ThisArg,
                                            ArrayRef<const Expr *> Args,
                                            SourceLocation Loc);
 
   /// Emit diagnostics for the diagnose_if attributes on Function, ignoring any
   /// ArgDependent DiagnoseIfAttrs.
   ///
   /// Argument-independent diagnose_if attributes should be checked on every use
   /// of a function.
   ///
   /// Returns true if any errors were emitted.
   bool diagnoseArgIndependentDiagnoseIfAttrs(const NamedDecl *ND,
                                              SourceLocation Loc);
 
   /// Returns whether the given function's address can be taken or not,
   /// optionally emitting a diagnostic if the address can't be taken.
   ///
   /// Returns false if taking the address of the function is illegal.
   bool checkAddressOfFunctionIsAvailable(const FunctionDecl *Function,
                                          bool Complain = false,
                                          SourceLocation Loc = SourceLocation());
 
   // [PossiblyAFunctionType]  -->   [Return]
   // NonFunctionType --> NonFunctionType
   // R (A) --> R(A)
   // R (*)(A) --> R (A)
   // R (&)(A) --> R (A)
   // R (S::*)(A) --> R (A)
   QualType ExtractUnqualifiedFunctionType(QualType PossiblyAFunctionType);
 
   FunctionDecl *
   ResolveAddressOfOverloadedFunction(Expr *AddressOfExpr,
                                      QualType TargetType,
                                      bool Complain,
                                      DeclAccessPair &Found,
                                      bool *pHadMultipleCandidates = nullptr);
 
   FunctionDecl *
   resolveAddressOfSingleOverloadCandidate(Expr *E, DeclAccessPair &FoundResult);
 
   bool resolveAndFixAddressOfSingleOverloadCandidate(
       ExprResult &SrcExpr, bool DoFunctionPointerConversion = false);
 
   FunctionDecl *ResolveSingleFunctionTemplateSpecialization(
       OverloadExpr *ovl, bool Complain = false, DeclAccessPair *Found = nullptr,
       TemplateSpecCandidateSet *FailedTSC = nullptr);
 
   bool ResolveAndFixSingleFunctionTemplateSpecialization(
       ExprResult &SrcExpr, bool DoFunctionPointerConversion = false,
       bool Complain = false, SourceRange OpRangeForComplaining = SourceRange(),
       QualType DestTypeForComplaining = QualType(),
       unsigned DiagIDForComplaining = 0);
 
   Expr *FixOverloadedFunctionReference(Expr *E,
                                        DeclAccessPair FoundDecl,
                                        FunctionDecl *Fn);
   ExprResult FixOverloadedFunctionReference(ExprResult,
                                             DeclAccessPair FoundDecl,
                                             FunctionDecl *Fn);
 
   void AddOverloadedCallCandidates(UnresolvedLookupExpr *ULE,
                                    ArrayRef<Expr *> Args,
                                    OverloadCandidateSet &CandidateSet,
                                    bool PartialOverloading = false);
   void AddOverloadedCallCandidates(
       LookupResult &R, TemplateArgumentListInfo *ExplicitTemplateArgs,
       ArrayRef<Expr *> Args, OverloadCandidateSet &CandidateSet);
 
   // An enum used to represent the different possible results of building a
   // range-based for loop.
   enum ForRangeStatus {
     FRS_Success,
     FRS_NoViableFunction,
     FRS_DiagnosticIssued
   };
 
   ForRangeStatus BuildForRangeBeginEndCall(SourceLocation Loc,
                                            SourceLocation RangeLoc,
                                            const DeclarationNameInfo &NameInfo,
                                            LookupResult &MemberLookup,
                                            OverloadCandidateSet *CandidateSet,
                                            Expr *Range, ExprResult *CallExpr);
 
   ExprResult BuildOverloadedCallExpr(Scope *S, Expr *Fn,
                                      UnresolvedLookupExpr *ULE,
                                      SourceLocation LParenLoc,
                                      MultiExprArg Args,
                                      SourceLocation RParenLoc,
                                      Expr *ExecConfig,
                                      bool AllowTypoCorrection=true,
                                      bool CalleesAddressIsTaken=false);
 
   bool buildOverloadedCallSet(Scope *S, Expr *Fn, UnresolvedLookupExpr *ULE,
                               MultiExprArg Args, SourceLocation RParenLoc,
                               OverloadCandidateSet *CandidateSet,
                               ExprResult *Result);
 
   ExprResult CreateUnresolvedLookupExpr(CXXRecordDecl *NamingClass,
                                         NestedNameSpecifierLoc NNSLoc,
                                         DeclarationNameInfo DNI,
                                         const UnresolvedSetImpl &Fns,
                                         bool PerformADL = true);
 
   ExprResult CreateOverloadedUnaryOp(SourceLocation OpLoc,
                                      UnaryOperatorKind Opc,
                                      const UnresolvedSetImpl &Fns,
                                      Expr *input, bool RequiresADL = true);
 
   void LookupOverloadedBinOp(OverloadCandidateSet &CandidateSet,
                              OverloadedOperatorKind Op,
                              const UnresolvedSetImpl &Fns,
                              ArrayRef<Expr *> Args, bool RequiresADL = true);
   ExprResult CreateOverloadedBinOp(SourceLocation OpLoc,
                                    BinaryOperatorKind Opc,
                                    const UnresolvedSetImpl &Fns,
                                    Expr *LHS, Expr *RHS,
                                    bool RequiresADL = true,
                                    bool AllowRewrittenCandidates = true,
                                    FunctionDecl *DefaultedFn = nullptr);
   ExprResult BuildSynthesizedThreeWayComparison(SourceLocation OpLoc,
                                                 const UnresolvedSetImpl &Fns,
                                                 Expr *LHS, Expr *RHS,
                                                 FunctionDecl *DefaultedFn);
 
   ExprResult CreateOverloadedArraySubscriptExpr(SourceLocation LLoc,
                                                 SourceLocation RLoc, Expr *Base,
                                                 MultiExprArg Args);
 
   ExprResult BuildCallToMemberFunction(Scope *S, Expr *MemExpr,
                                        SourceLocation LParenLoc,
                                        MultiExprArg Args,
                                        SourceLocation RParenLoc,
                                        Expr *ExecConfig = nullptr,
                                        bool IsExecConfig = false,
                                        bool AllowRecovery = false);
   ExprResult
   BuildCallToObjectOfClassType(Scope *S, Expr *Object, SourceLocation LParenLoc,
                                MultiExprArg Args,
                                SourceLocation RParenLoc);
 
   ExprResult BuildOverloadedArrowExpr(Scope *S, Expr *Base,
                                       SourceLocation OpLoc,
                                       bool *NoArrowOperatorFound = nullptr);
 
   /// CheckCallReturnType - Checks that a call expression's return type is
   /// complete. Returns true on failure. The location passed in is the location
   /// that best represents the call.
   bool CheckCallReturnType(QualType ReturnType, SourceLocation Loc,
                            CallExpr *CE, FunctionDecl *FD);
 
   /// Helpers for dealing with blocks and functions.
   bool CheckParmsForFunctionDef(ArrayRef<ParmVarDecl *> Parameters,
                                 bool CheckParameterNames);
   void CheckCXXDefaultArguments(FunctionDecl *FD);
   void CheckExtraCXXDefaultArguments(Declarator &D);
   Scope *getNonFieldDeclScope(Scope *S);
 
   /// \name Name lookup
   ///
   /// These routines provide name lookup that is used during semantic
   /// analysis to resolve the various kinds of names (identifiers,
   /// overloaded operator names, constructor names, etc.) into zero or
   /// more declarations within a particular scope. The major entry
   /// points are LookupName, which performs unqualified name lookup,
   /// and LookupQualifiedName, which performs qualified name lookup.
   ///
   /// All name lookup is performed based on some specific criteria,
   /// which specify what names will be visible to name lookup and how
   /// far name lookup should work. These criteria are important both
   /// for capturing language semantics (certain lookups will ignore
   /// certain names, for example) and for performance, since name
   /// lookup is often a bottleneck in the compilation of C++. Name
   /// lookup criteria is specified via the LookupCriteria enumeration.
   ///
   /// The results of name lookup can vary based on the kind of name
   /// lookup performed, the current language, and the translation
   /// unit. In C, for example, name lookup will either return nothing
   /// (no entity found) or a single declaration. In C++, name lookup
   /// can additionally refer to a set of overloaded functions or
   /// result in an ambiguity. All of the possible results of name
   /// lookup are captured by the LookupResult class, which provides
   /// the ability to distinguish among them.
   //@{
 
   /// Describes the kind of name lookup to perform.
   enum LookupNameKind {
     /// Ordinary name lookup, which finds ordinary names (functions,
     /// variables, typedefs, etc.) in C and most kinds of names
     /// (functions, variables, members, types, etc.) in C++.
     LookupOrdinaryName = 0,
     /// Tag name lookup, which finds the names of enums, classes,
     /// structs, and unions.
     LookupTagName,
     /// Label name lookup.
     LookupLabel,
     /// Member name lookup, which finds the names of
     /// class/struct/union members.
     LookupMemberName,
     /// Look up of an operator name (e.g., operator+) for use with
     /// operator overloading. This lookup is similar to ordinary name
     /// lookup, but will ignore any declarations that are class members.
     LookupOperatorName,
     /// Look up a name following ~ in a destructor name. This is an ordinary
     /// lookup, but prefers tags to typedefs.
     LookupDestructorName,
     /// Look up of a name that precedes the '::' scope resolution
     /// operator in C++. This lookup completely ignores operator, object,
     /// function, and enumerator names (C++ [basic.lookup.qual]p1).
     LookupNestedNameSpecifierName,
     /// Look up a namespace name within a C++ using directive or
     /// namespace alias definition, ignoring non-namespace names (C++
     /// [basic.lookup.udir]p1).
     LookupNamespaceName,
     /// Look up all declarations in a scope with the given name,
     /// including resolved using declarations.  This is appropriate
     /// for checking redeclarations for a using declaration.
     LookupUsingDeclName,
     /// Look up an ordinary name that is going to be redeclared as a
     /// name with linkage. This lookup ignores any declarations that
     /// are outside of the current scope unless they have linkage. See
     /// C99 6.2.2p4-5 and C++ [basic.link]p6.
     LookupRedeclarationWithLinkage,
     /// Look up a friend of a local class. This lookup does not look
     /// outside the innermost non-class scope. See C++11 [class.friend]p11.
     LookupLocalFriendName,
     /// Look up the name of an Objective-C protocol.
     LookupObjCProtocolName,
     /// Look up implicit 'self' parameter of an objective-c method.
     LookupObjCImplicitSelfParam,
     /// Look up the name of an OpenMP user-defined reduction operation.
     LookupOMPReductionName,
     /// Look up the name of an OpenMP user-defined mapper.
     LookupOMPMapperName,
     /// Look up any declaration with any name.
     LookupAnyName
   };
 
   /// Specifies whether (or how) name lookup is being performed for a
   /// redeclaration (vs. a reference).
   enum RedeclarationKind {
     /// The lookup is a reference to this name that is not for the
     /// purpose of redeclaring the name.
     NotForRedeclaration = 0,
     /// The lookup results will be used for redeclaration of a name,
     /// if an entity by that name already exists and is visible.
     ForVisibleRedeclaration,
     /// The lookup results will be used for redeclaration of a name
     /// with external linkage; non-visible lookup results with external linkage
     /// may also be found.
     ForExternalRedeclaration
   };
 
   RedeclarationKind forRedeclarationInCurContext() const {
     // A declaration with an owning module for linkage can never link against
     // anything that is not visible. We don't need to check linkage here; if
     // the context has internal linkage, redeclaration lookup won't find things
     // from other TUs, and we can't safely compute linkage yet in general.
     if (cast<Decl>(CurContext)
             ->getOwningModuleForLinkage(/*IgnoreLinkage*/true))
       return ForVisibleRedeclaration;
     return ForExternalRedeclaration;
   }
 
   /// The possible outcomes of name lookup for a literal operator.
   enum LiteralOperatorLookupResult {
     /// The lookup resulted in an error.
     LOLR_Error,
     /// The lookup found no match but no diagnostic was issued.
     LOLR_ErrorNoDiagnostic,
     /// The lookup found a single 'cooked' literal operator, which
     /// expects a normal literal to be built and passed to it.
     LOLR_Cooked,
     /// The lookup found a single 'raw' literal operator, which expects
     /// a string literal containing the spelling of the literal token.
     LOLR_Raw,
     /// The lookup found an overload set of literal operator templates,
     /// which expect the characters of the spelling of the literal token to be
     /// passed as a non-type template argument pack.
     LOLR_Template,
     /// The lookup found an overload set of literal operator templates,
     /// which expect the character type and characters of the spelling of the
     /// string literal token to be passed as template arguments.
     LOLR_StringTemplatePack,
   };
 
   SpecialMemberOverloadResult LookupSpecialMember(CXXRecordDecl *D,
                                                   CXXSpecialMember SM,
                                                   bool ConstArg,
                                                   bool VolatileArg,
                                                   bool RValueThis,
                                                   bool ConstThis,
                                                   bool VolatileThis);
 
   typedef std::function<void(const TypoCorrection &)> TypoDiagnosticGenerator;
   typedef std::function<ExprResult(Sema &, TypoExpr *, TypoCorrection)>
       TypoRecoveryCallback;
 
 private:
   bool CppLookupName(LookupResult &R, Scope *S);
 
   struct TypoExprState {
     std::unique_ptr<TypoCorrectionConsumer> Consumer;
     TypoDiagnosticGenerator DiagHandler;
     TypoRecoveryCallback RecoveryHandler;
     TypoExprState();
     TypoExprState(TypoExprState &&other) noexcept;
     TypoExprState &operator=(TypoExprState &&other) noexcept;
   };
 
   /// The set of unhandled TypoExprs and their associated state.
   llvm::MapVector<TypoExpr *, TypoExprState> DelayedTypos;
 
   /// Creates a new TypoExpr AST node.
   TypoExpr *createDelayedTypo(std::unique_ptr<TypoCorrectionConsumer> TCC,
                               TypoDiagnosticGenerator TDG,
                               TypoRecoveryCallback TRC, SourceLocation TypoLoc);
 
   // The set of known/encountered (unique, canonicalized) NamespaceDecls.
   //
   // The boolean value will be true to indicate that the namespace was loaded
   // from an AST/PCH file, or false otherwise.
   llvm::MapVector<NamespaceDecl*, bool> KnownNamespaces;
 
   /// Whether we have already loaded known namespaces from an extenal
   /// source.
   bool LoadedExternalKnownNamespaces;
 
   /// Helper for CorrectTypo and CorrectTypoDelayed used to create and
   /// populate a new TypoCorrectionConsumer. Returns nullptr if typo correction
   /// should be skipped entirely.
   std::unique_ptr<TypoCorrectionConsumer>
   makeTypoCorrectionConsumer(const DeclarationNameInfo &Typo,
                              Sema::LookupNameKind LookupKind, Scope *S,
                              CXXScopeSpec *SS,
                              CorrectionCandidateCallback &CCC,
                              DeclContext *MemberContext, bool EnteringContext,
                              const ObjCObjectPointerType *OPT,
                              bool ErrorRecovery);
 
 public:
   const TypoExprState &getTypoExprState(TypoExpr *TE) const;
 
   /// Clears the state of the given TypoExpr.
   void clearDelayedTypo(TypoExpr *TE);
 
   /// Look up a name, looking for a single declaration.  Return
   /// null if the results were absent, ambiguous, or overloaded.
   ///
   /// It is preferable to use the elaborated form and explicitly handle
   /// ambiguity and overloaded.
   NamedDecl *LookupSingleName(Scope *S, DeclarationName Name,
                               SourceLocation Loc,
                               LookupNameKind NameKind,
                               RedeclarationKind Redecl
                                 = NotForRedeclaration);
   bool LookupBuiltin(LookupResult &R);
   void LookupNecessaryTypesForBuiltin(Scope *S, unsigned ID);
   bool LookupName(LookupResult &R, Scope *S, bool AllowBuiltinCreation = false,
                   bool ForceNoCPlusPlus = false);
   bool LookupQualifiedName(LookupResult &R, DeclContext *LookupCtx,
                            bool InUnqualifiedLookup = false);
   bool LookupQualifiedName(LookupResult &R, DeclContext *LookupCtx,
                            CXXScopeSpec &SS);
   bool LookupParsedName(LookupResult &R, Scope *S, CXXScopeSpec *SS,
                         bool AllowBuiltinCreation = false,
                         bool EnteringContext = false);
   ObjCProtocolDecl *LookupProtocol(IdentifierInfo *II, SourceLocation IdLoc,
                                    RedeclarationKind Redecl
                                      = NotForRedeclaration);
   bool LookupInSuper(LookupResult &R, CXXRecordDecl *Class);
 
   void LookupOverloadedOperatorName(OverloadedOperatorKind Op, Scope *S,
                                     UnresolvedSetImpl &Functions);
 
   LabelDecl *LookupOrCreateLabel(IdentifierInfo *II, SourceLocation IdentLoc,
                                  SourceLocation GnuLabelLoc = SourceLocation());
 
   DeclContextLookupResult LookupConstructors(CXXRecordDecl *Class);
   CXXConstructorDecl *LookupDefaultConstructor(CXXRecordDecl *Class);
   CXXConstructorDecl *LookupCopyingConstructor(CXXRecordDecl *Class,
                                                unsigned Quals);
   CXXMethodDecl *LookupCopyingAssignment(CXXRecordDecl *Class, unsigned Quals,
                                          bool RValueThis, unsigned ThisQuals);
   CXXConstructorDecl *LookupMovingConstructor(CXXRecordDecl *Class,
                                               unsigned Quals);
   CXXMethodDecl *LookupMovingAssignment(CXXRecordDecl *Class, unsigned Quals,
                                         bool RValueThis, unsigned ThisQuals);
   CXXDestructorDecl *LookupDestructor(CXXRecordDecl *Class);
 
   bool checkLiteralOperatorId(const CXXScopeSpec &SS, const UnqualifiedId &Id,
                               bool IsUDSuffix);
   LiteralOperatorLookupResult
   LookupLiteralOperator(Scope *S, LookupResult &R, ArrayRef<QualType> ArgTys,
                         bool AllowRaw, bool AllowTemplate,
                         bool AllowStringTemplate, bool DiagnoseMissing,
                         StringLiteral *StringLit = nullptr);
   bool isKnownName(StringRef name);
 
   /// Status of the function emission on the CUDA/HIP/OpenMP host/device attrs.
   enum class FunctionEmissionStatus {
     Emitted,
     CUDADiscarded,     // Discarded due to CUDA/HIP hostness
     OMPDiscarded,      // Discarded due to OpenMP hostness
     TemplateDiscarded, // Discarded due to uninstantiated templates
     Unknown,
   };
   FunctionEmissionStatus getEmissionStatus(const FunctionDecl *Decl,
                                            bool Final = false);
 
   // Whether the callee should be ignored in CUDA/HIP/OpenMP host/device check.
   bool shouldIgnoreInHostDeviceCheck(FunctionDecl *Callee);
 
   void ArgumentDependentLookup(DeclarationName Name, SourceLocation Loc,
                                ArrayRef<Expr *> Args, ADLResult &Functions);
 
   void LookupVisibleDecls(Scope *S, LookupNameKind Kind,
                           VisibleDeclConsumer &Consumer,
                           bool IncludeGlobalScope = true,
                           bool LoadExternal = true);
   void LookupVisibleDecls(DeclContext *Ctx, LookupNameKind Kind,
                           VisibleDeclConsumer &Consumer,
                           bool IncludeGlobalScope = true,
                           bool IncludeDependentBases = false,
                           bool LoadExternal = true);
 
   enum CorrectTypoKind {
     CTK_NonError,     // CorrectTypo used in a non error recovery situation.
     CTK_ErrorRecovery // CorrectTypo used in normal error recovery.
   };
 
   TypoCorrection CorrectTypo(const DeclarationNameInfo &Typo,
                              Sema::LookupNameKind LookupKind,
                              Scope *S, CXXScopeSpec *SS,
                              CorrectionCandidateCallback &CCC,
                              CorrectTypoKind Mode,
                              DeclContext *MemberContext = nullptr,
                              bool EnteringContext = false,
                              const ObjCObjectPointerType *OPT = nullptr,
                              bool RecordFailure = true);
 
   TypoExpr *CorrectTypoDelayed(const DeclarationNameInfo &Typo,
                                Sema::LookupNameKind LookupKind, Scope *S,
                                CXXScopeSpec *SS,
                                CorrectionCandidateCallback &CCC,
                                TypoDiagnosticGenerator TDG,
                                TypoRecoveryCallback TRC, CorrectTypoKind Mode,
                                DeclContext *MemberContext = nullptr,
                                bool EnteringContext = false,
                                const ObjCObjectPointerType *OPT = nullptr);
 
   /// Process any TypoExprs in the given Expr and its children,
   /// generating diagnostics as appropriate and returning a new Expr if there
   /// were typos that were all successfully corrected and ExprError if one or
   /// more typos could not be corrected.
   ///
   /// \param E The Expr to check for TypoExprs.
   ///
   /// \param InitDecl A VarDecl to avoid because the Expr being corrected is its
   /// initializer.
   ///
   /// \param RecoverUncorrectedTypos If true, when typo correction fails, it
   /// will rebuild the given Expr with all TypoExprs degraded to RecoveryExprs.
   ///
   /// \param Filter A function applied to a newly rebuilt Expr to determine if
   /// it is an acceptable/usable result from a single combination of typo
   /// corrections. As long as the filter returns ExprError, different
   /// combinations of corrections will be tried until all are exhausted.
   ExprResult CorrectDelayedTyposInExpr(
       Expr *E, VarDecl *InitDecl = nullptr,
       bool RecoverUncorrectedTypos = false,
       llvm::function_ref<ExprResult(Expr *)> Filter =
           [](Expr *E) -> ExprResult { return E; });
 
   ExprResult CorrectDelayedTyposInExpr(
       ExprResult ER, VarDecl *InitDecl = nullptr,
       bool RecoverUncorrectedTypos = false,
       llvm::function_ref<ExprResult(Expr *)> Filter =
           [](Expr *E) -> ExprResult { return E; }) {
     return ER.isInvalid()
                ? ER
                : CorrectDelayedTyposInExpr(ER.get(), InitDecl,
                                            RecoverUncorrectedTypos, Filter);
   }
 
   void diagnoseTypo(const TypoCorrection &Correction,
                     const PartialDiagnostic &TypoDiag,
                     bool ErrorRecovery = true);
 
   void diagnoseTypo(const TypoCorrection &Correction,
                     const PartialDiagnostic &TypoDiag,
                     const PartialDiagnostic &PrevNote,
                     bool ErrorRecovery = true);
 
   void MarkTypoCorrectedFunctionDefinition(const NamedDecl *F);
 
   void FindAssociatedClassesAndNamespaces(SourceLocation InstantiationLoc,
                                           ArrayRef<Expr *> Args,
                                    AssociatedNamespaceSet &AssociatedNamespaces,
                                    AssociatedClassSet &AssociatedClasses);
 
   void FilterLookupForScope(LookupResult &R, DeclContext *Ctx, Scope *S,
                             bool ConsiderLinkage, bool AllowInlineNamespace);
 
   bool CheckRedeclarationModuleOwnership(NamedDecl *New, NamedDecl *Old);
   bool CheckRedeclarationExported(NamedDecl *New, NamedDecl *Old);
   bool CheckRedeclarationInModule(NamedDecl *New, NamedDecl *Old);
   bool IsRedefinitionInModule(const NamedDecl *New,
                                  const NamedDecl *Old) const;
 
   void DiagnoseAmbiguousLookup(LookupResult &Result);
   //@}
 
   /// Attempts to produce a RecoveryExpr after some AST node cannot be created.
   ExprResult CreateRecoveryExpr(SourceLocation Begin, SourceLocation End,
                                 ArrayRef<Expr *> SubExprs,
                                 QualType T = QualType());
 
   ObjCInterfaceDecl *getObjCInterfaceDecl(IdentifierInfo *&Id,
                                           SourceLocation IdLoc,
                                           bool TypoCorrection = false);
   FunctionDecl *CreateBuiltin(IdentifierInfo *II, QualType Type, unsigned ID,
                               SourceLocation Loc);
   NamedDecl *LazilyCreateBuiltin(IdentifierInfo *II, unsigned ID,
                                  Scope *S, bool ForRedeclaration,
                                  SourceLocation Loc);
   NamedDecl *ImplicitlyDefineFunction(SourceLocation Loc, IdentifierInfo &II,
                                       Scope *S);
   void AddKnownFunctionAttributesForReplaceableGlobalAllocationFunction(
       FunctionDecl *FD);
   void AddKnownFunctionAttributes(FunctionDecl *FD);
 
   // More parsing and symbol table subroutines.
 
   void ProcessPragmaWeak(Scope *S, Decl *D);
   // Decl attributes - this routine is the top level dispatcher.
   void ProcessDeclAttributes(Scope *S, Decl *D, const Declarator &PD);
   // Helper for delayed processing of attributes.
   void ProcessDeclAttributeDelayed(Decl *D,
                                    const ParsedAttributesView &AttrList);
 
   // Options for ProcessDeclAttributeList().
   struct ProcessDeclAttributeOptions {
     ProcessDeclAttributeOptions()
         : IncludeCXX11Attributes(true), IgnoreTypeAttributes(false) {}
 
     ProcessDeclAttributeOptions WithIncludeCXX11Attributes(bool Val) {
       ProcessDeclAttributeOptions Result = *this;
       Result.IncludeCXX11Attributes = Val;
       return Result;
     }
 
     ProcessDeclAttributeOptions WithIgnoreTypeAttributes(bool Val) {
       ProcessDeclAttributeOptions Result = *this;
       Result.IgnoreTypeAttributes = Val;
       return Result;
     }
 
     // Should C++11 attributes be processed?
     bool IncludeCXX11Attributes;
 
     // Should any type attributes encountered be ignored?
     // If this option is false, a diagnostic will be emitted for any type
     // attributes of a kind that does not "slide" from the declaration to
     // the decl-specifier-seq.
     bool IgnoreTypeAttributes;
   };
 
   void ProcessDeclAttributeList(Scope *S, Decl *D,
                                 const ParsedAttributesView &AttrList,
                                 const ProcessDeclAttributeOptions &Options =
                                     ProcessDeclAttributeOptions());
   bool ProcessAccessDeclAttributeList(AccessSpecDecl *ASDecl,
                                    const ParsedAttributesView &AttrList);
 
   void checkUnusedDeclAttributes(Declarator &D);
 
   /// Handles semantic checking for features that are common to all attributes,
   /// such as checking whether a parameter was properly specified, or the
   /// correct number of arguments were passed, etc. Returns true if the
   /// attribute has been diagnosed.
   bool checkCommonAttributeFeatures(const Decl *D, const ParsedAttr &A,
                                     bool SkipArgCountCheck = false);
   bool checkCommonAttributeFeatures(const Stmt *S, const ParsedAttr &A,
                                     bool SkipArgCountCheck = false);
 
   /// Determine if type T is a valid subject for a nonnull and similar
   /// attributes. By default, we look through references (the behavior used by
   /// nonnull), but if the second parameter is true, then we treat a reference
   /// type as valid.
   bool isValidPointerAttrType(QualType T, bool RefOkay = false);
 
   bool CheckRegparmAttr(const ParsedAttr &attr, unsigned &value);
   bool CheckCallingConvAttr(const ParsedAttr &attr, CallingConv &CC,
                             const FunctionDecl *FD = nullptr);
   bool CheckAttrTarget(const ParsedAttr &CurrAttr);
   bool CheckAttrNoArgs(const ParsedAttr &CurrAttr);
   bool checkStringLiteralArgumentAttr(const AttributeCommonInfo &CI,
                                       const Expr *E, StringRef &Str,
                                       SourceLocation *ArgLocation = nullptr);
   bool checkStringLiteralArgumentAttr(const ParsedAttr &Attr, unsigned ArgNum,
                                       StringRef &Str,
                                       SourceLocation *ArgLocation = nullptr);
   llvm::Error isValidSectionSpecifier(StringRef Str);
   bool checkSectionName(SourceLocation LiteralLoc, StringRef Str);
   bool checkTargetAttr(SourceLocation LiteralLoc, StringRef Str);
   bool checkTargetVersionAttr(SourceLocation LiteralLoc, StringRef &Str,
                               bool &isDefault);
   bool
   checkTargetClonesAttrString(SourceLocation LiteralLoc, StringRef Str,
                               const StringLiteral *Literal, bool &HasDefault,
                               bool &HasCommas, bool &HasNotDefault,
                               SmallVectorImpl<SmallString<64>> &StringsBuffer);
   bool checkMSInheritanceAttrOnDefinition(
       CXXRecordDecl *RD, SourceRange Range, bool BestCase,
       MSInheritanceModel SemanticSpelling);
 
   void CheckAlignasUnderalignment(Decl *D);
 
   bool CheckNoInlineAttr(const Stmt *OrigSt, const Stmt *CurSt,
                          const AttributeCommonInfo &A);
   bool CheckAlwaysInlineAttr(const Stmt *OrigSt, const Stmt *CurSt,
                              const AttributeCommonInfo &A);
 
   /// Adjust the calling convention of a method to be the ABI default if it
   /// wasn't specified explicitly.  This handles method types formed from
   /// function type typedefs and typename template arguments.
   void adjustMemberFunctionCC(QualType &T, bool IsStatic, bool IsCtorOrDtor,
                               SourceLocation Loc);
 
   // Check if there is an explicit attribute, but only look through parens.
   // The intent is to look for an attribute on the current declarator, but not
   // one that came from a typedef.
   bool hasExplicitCallingConv(QualType T);
 
   /// Get the outermost AttributedType node that sets a calling convention.
   /// Valid types should not have multiple attributes with different CCs.
   const AttributedType *getCallingConvAttributedType(QualType T) const;
 
   /// Process the attributes before creating an attributed statement. Returns
   /// the semantic attributes that have been processed.
   void ProcessStmtAttributes(Stmt *Stmt, const ParsedAttributes &InAttrs,
                              SmallVectorImpl<const Attr *> &OutAttrs);
 
   void WarnConflictingTypedMethods(ObjCMethodDecl *Method,
                                    ObjCMethodDecl *MethodDecl,
                                    bool IsProtocolMethodDecl);
 
   void CheckConflictingOverridingMethod(ObjCMethodDecl *Method,
                                    ObjCMethodDecl *Overridden,
                                    bool IsProtocolMethodDecl);
 
   /// WarnExactTypedMethods - This routine issues a warning if method
   /// implementation declaration matches exactly that of its declaration.
   void WarnExactTypedMethods(ObjCMethodDecl *Method,
                              ObjCMethodDecl *MethodDecl,
                              bool IsProtocolMethodDecl);
 
   typedef llvm::SmallPtrSet<Selector, 8> SelectorSet;
 
   /// CheckImplementationIvars - This routine checks if the instance variables
   /// listed in the implelementation match those listed in the interface.
   void CheckImplementationIvars(ObjCImplementationDecl *ImpDecl,
                                 ObjCIvarDecl **Fields, unsigned nIvars,
                                 SourceLocation Loc);
 
   /// ImplMethodsVsClassMethods - This is main routine to warn if any method
   /// remains unimplemented in the class or category \@implementation.
   void ImplMethodsVsClassMethods(Scope *S, ObjCImplDecl* IMPDecl,
                                  ObjCContainerDecl* IDecl,
                                  bool IncompleteImpl = false);
 
   /// DiagnoseUnimplementedProperties - This routine warns on those properties
   /// which must be implemented by this implementation.
   void DiagnoseUnimplementedProperties(Scope *S, ObjCImplDecl* IMPDecl,
                                        ObjCContainerDecl *CDecl,
                                        bool SynthesizeProperties);
 
   /// Diagnose any null-resettable synthesized setters.
   void diagnoseNullResettableSynthesizedSetters(const ObjCImplDecl *impDecl);
 
   /// DefaultSynthesizeProperties - This routine default synthesizes all
   /// properties which must be synthesized in the class's \@implementation.
   void DefaultSynthesizeProperties(Scope *S, ObjCImplDecl *IMPDecl,
                                    ObjCInterfaceDecl *IDecl,
                                    SourceLocation AtEnd);
   void DefaultSynthesizeProperties(Scope *S, Decl *D, SourceLocation AtEnd);
 
   /// IvarBacksCurrentMethodAccessor - This routine returns 'true' if 'IV' is
   /// an ivar synthesized for 'Method' and 'Method' is a property accessor
   /// declared in class 'IFace'.
   bool IvarBacksCurrentMethodAccessor(ObjCInterfaceDecl *IFace,
                                       ObjCMethodDecl *Method, ObjCIvarDecl *IV);
 
   /// DiagnoseUnusedBackingIvarInAccessor - Issue an 'unused' warning if ivar which
   /// backs the property is not used in the property's accessor.
   void DiagnoseUnusedBackingIvarInAccessor(Scope *S,
                                            const ObjCImplementationDecl *ImplD);
 
   /// GetIvarBackingPropertyAccessor - If method is a property setter/getter and
   /// it property has a backing ivar, returns this ivar; otherwise, returns NULL.
   /// It also returns ivar's property on success.
   ObjCIvarDecl *GetIvarBackingPropertyAccessor(const ObjCMethodDecl *Method,
                                                const ObjCPropertyDecl *&PDecl) const;
 
   /// Called by ActOnProperty to handle \@property declarations in
   /// class extensions.
   ObjCPropertyDecl *HandlePropertyInClassExtension(Scope *S,
                       SourceLocation AtLoc,
                       SourceLocation LParenLoc,
                       FieldDeclarator &FD,
                       Selector GetterSel,
                       SourceLocation GetterNameLoc,
                       Selector SetterSel,
                       SourceLocation SetterNameLoc,
                       const bool isReadWrite,
                       unsigned &Attributes,
                       const unsigned AttributesAsWritten,
                       QualType T,
                       TypeSourceInfo *TSI,
                       tok::ObjCKeywordKind MethodImplKind);
 
   /// Called by ActOnProperty and HandlePropertyInClassExtension to
   /// handle creating the ObjcPropertyDecl for a category or \@interface.
   ObjCPropertyDecl *CreatePropertyDecl(Scope *S,
                                        ObjCContainerDecl *CDecl,
                                        SourceLocation AtLoc,
                                        SourceLocation LParenLoc,
                                        FieldDeclarator &FD,
                                        Selector GetterSel,
                                        SourceLocation GetterNameLoc,
                                        Selector SetterSel,
                                        SourceLocation SetterNameLoc,
                                        const bool isReadWrite,
                                        const unsigned Attributes,
                                        const unsigned AttributesAsWritten,
                                        QualType T,
                                        TypeSourceInfo *TSI,
                                        tok::ObjCKeywordKind MethodImplKind,
                                        DeclContext *lexicalDC = nullptr);
 
   /// AtomicPropertySetterGetterRules - This routine enforces the rule (via
   /// warning) when atomic property has one but not the other user-declared
   /// setter or getter.
   void AtomicPropertySetterGetterRules(ObjCImplDecl* IMPDecl,
                                        ObjCInterfaceDecl* IDecl);
 
   void DiagnoseOwningPropertyGetterSynthesis(const ObjCImplementationDecl *D);
 
   void DiagnoseMissingDesignatedInitOverrides(
                                           const ObjCImplementationDecl *ImplD,
                                           const ObjCInterfaceDecl *IFD);
 
   void DiagnoseDuplicateIvars(ObjCInterfaceDecl *ID, ObjCInterfaceDecl *SID);
 
   enum MethodMatchStrategy {
     MMS_loose,
     MMS_strict
   };
 
   /// MatchTwoMethodDeclarations - Checks if two methods' type match and returns
   /// true, or false, accordingly.
   bool MatchTwoMethodDeclarations(const ObjCMethodDecl *Method,
                                   const ObjCMethodDecl *PrevMethod,
                                   MethodMatchStrategy strategy = MMS_strict);
 
   /// MatchAllMethodDeclarations - Check methods declaraed in interface or
   /// or protocol against those declared in their implementations.
   void MatchAllMethodDeclarations(const SelectorSet &InsMap,
                                   const SelectorSet &ClsMap,
                                   SelectorSet &InsMapSeen,
                                   SelectorSet &ClsMapSeen,
                                   ObjCImplDecl* IMPDecl,
                                   ObjCContainerDecl* IDecl,
                                   bool &IncompleteImpl,
                                   bool ImmediateClass,
                                   bool WarnCategoryMethodImpl=false);
 
   /// CheckCategoryVsClassMethodMatches - Checks that methods implemented in
   /// category matches with those implemented in its primary class and
   /// warns each time an exact match is found.
   void CheckCategoryVsClassMethodMatches(ObjCCategoryImplDecl *CatIMP);
 
   /// Add the given method to the list of globally-known methods.
   void addMethodToGlobalList(ObjCMethodList *List, ObjCMethodDecl *Method);
 
   /// Returns default addr space for method qualifiers.
   LangAS getDefaultCXXMethodAddrSpace() const;
 
 private:
   /// AddMethodToGlobalPool - Add an instance or factory method to the global
   /// pool. See descriptoin of AddInstanceMethodToGlobalPool.
   void AddMethodToGlobalPool(ObjCMethodDecl *Method, bool impl, bool instance);
 
   /// LookupMethodInGlobalPool - Returns the instance or factory method and
   /// optionally warns if there are multiple signatures.
   ObjCMethodDecl *LookupMethodInGlobalPool(Selector Sel, SourceRange R,
                                            bool receiverIdOrClass,
                                            bool instance);
 
 public:
   /// - Returns instance or factory methods in global method pool for
   /// given selector. It checks the desired kind first, if none is found, and
   /// parameter checkTheOther is set, it then checks the other kind. If no such
   /// method or only one method is found, function returns false; otherwise, it
   /// returns true.
   bool
   CollectMultipleMethodsInGlobalPool(Selector Sel,
                                      SmallVectorImpl<ObjCMethodDecl*>& Methods,
                                      bool InstanceFirst, bool CheckTheOther,
                                      const ObjCObjectType *TypeBound = nullptr);
 
   bool
   AreMultipleMethodsInGlobalPool(Selector Sel, ObjCMethodDecl *BestMethod,
                                  SourceRange R, bool receiverIdOrClass,
                                  SmallVectorImpl<ObjCMethodDecl*>& Methods);
 
   void
   DiagnoseMultipleMethodInGlobalPool(SmallVectorImpl<ObjCMethodDecl*> &Methods,
                                      Selector Sel, SourceRange R,
                                      bool receiverIdOrClass);
 
 private:
   /// - Returns a selector which best matches given argument list or
   /// nullptr if none could be found
   ObjCMethodDecl *SelectBestMethod(Selector Sel, MultiExprArg Args,
                                    bool IsInstance,
                                    SmallVectorImpl<ObjCMethodDecl*>& Methods);
 
 
   /// Record the typo correction failure and return an empty correction.
   TypoCorrection FailedCorrection(IdentifierInfo *Typo, SourceLocation TypoLoc,
                                   bool RecordFailure = true) {
     if (RecordFailure)
       TypoCorrectionFailures[Typo].insert(TypoLoc);
     return TypoCorrection();
   }
 
 public:
   /// AddInstanceMethodToGlobalPool - All instance methods in a translation
   /// unit are added to a global pool. This allows us to efficiently associate
   /// a selector with a method declaraation for purposes of typechecking
   /// messages sent to "id" (where the class of the object is unknown).
   void AddInstanceMethodToGlobalPool(ObjCMethodDecl *Method, bool impl=false) {
     AddMethodToGlobalPool(Method, impl, /*instance*/true);
   }
 
   /// AddFactoryMethodToGlobalPool - Same as above, but for factory methods.
   void AddFactoryMethodToGlobalPool(ObjCMethodDecl *Method, bool impl=false) {
     AddMethodToGlobalPool(Method, impl, /*instance*/false);
   }
 
   /// AddAnyMethodToGlobalPool - Add any method, instance or factory to global
   /// pool.
   void AddAnyMethodToGlobalPool(Decl *D);
 
   /// LookupInstanceMethodInGlobalPool - Returns the method and warns if
   /// there are multiple signatures.
   ObjCMethodDecl *LookupInstanceMethodInGlobalPool(Selector Sel, SourceRange R,
                                                    bool receiverIdOrClass=false) {
     return LookupMethodInGlobalPool(Sel, R, receiverIdOrClass,
                                     /*instance*/true);
   }
 
   /// LookupFactoryMethodInGlobalPool - Returns the method and warns if
   /// there are multiple signatures.
   ObjCMethodDecl *LookupFactoryMethodInGlobalPool(Selector Sel, SourceRange R,
                                                   bool receiverIdOrClass=false) {
     return LookupMethodInGlobalPool(Sel, R, receiverIdOrClass,
                                     /*instance*/false);
   }
 
   const ObjCMethodDecl *SelectorsForTypoCorrection(Selector Sel,
                               QualType ObjectType=QualType());
   /// LookupImplementedMethodInGlobalPool - Returns the method which has an
   /// implementation.
   ObjCMethodDecl *LookupImplementedMethodInGlobalPool(Selector Sel);
 
   /// CollectIvarsToConstructOrDestruct - Collect those ivars which require
   /// initialization.
   void CollectIvarsToConstructOrDestruct(ObjCInterfaceDecl *OI,
                                   SmallVectorImpl<ObjCIvarDecl*> &Ivars);
 
   //===--------------------------------------------------------------------===//
   // Statement Parsing Callbacks: SemaStmt.cpp.
 public:
   class FullExprArg {
   public:
     FullExprArg() : E(nullptr) { }
     FullExprArg(Sema &actions) : E(nullptr) { }
 
     ExprResult release() {
       return E;
     }
 
     Expr *get() const { return E; }
 
     Expr *operator->() {
       return E;
     }
 
   private:
     // FIXME: No need to make the entire Sema class a friend when it's just
     // Sema::MakeFullExpr that needs access to the constructor below.
     friend class Sema;
 
     explicit FullExprArg(Expr *expr) : E(expr) {}
 
     Expr *E;
   };
 
   FullExprArg MakeFullExpr(Expr *Arg) {
     return MakeFullExpr(Arg, Arg ? Arg->getExprLoc() : SourceLocation());
   }
   FullExprArg MakeFullExpr(Expr *Arg, SourceLocation CC) {
     return FullExprArg(
         ActOnFinishFullExpr(Arg, CC, /*DiscardedValue*/ false).get());
   }
   FullExprArg MakeFullDiscardedValueExpr(Expr *Arg) {
     ExprResult FE =
         ActOnFinishFullExpr(Arg, Arg ? Arg->getExprLoc() : SourceLocation(),
                             /*DiscardedValue*/ true);
     return FullExprArg(FE.get());
   }
 
   StmtResult ActOnExprStmt(ExprResult Arg, bool DiscardedValue = true);
   StmtResult ActOnExprStmtError();
 
   StmtResult ActOnNullStmt(SourceLocation SemiLoc,
                            bool HasLeadingEmptyMacro = false);
 
   void ActOnStartOfCompoundStmt(bool IsStmtExpr);
   void ActOnAfterCompoundStatementLeadingPragmas();
   void ActOnFinishOfCompoundStmt();
   StmtResult ActOnCompoundStmt(SourceLocation L, SourceLocation R,
                                ArrayRef<Stmt *> Elts, bool isStmtExpr);
 
   /// A RAII object to enter scope of a compound statement.
   class CompoundScopeRAII {
   public:
     CompoundScopeRAII(Sema &S, bool IsStmtExpr = false) : S(S) {
       S.ActOnStartOfCompoundStmt(IsStmtExpr);
     }
 
     ~CompoundScopeRAII() {
       S.ActOnFinishOfCompoundStmt();
     }
 
   private:
     Sema &S;
   };
 
   /// An RAII helper that pops function a function scope on exit.
   struct FunctionScopeRAII {
     Sema &S;
     bool Active;
     FunctionScopeRAII(Sema &S) : S(S), Active(true) {}
     ~FunctionScopeRAII() {
       if (Active)
         S.PopFunctionScopeInfo();
     }
     void disable() { Active = false; }
   };
 
   StmtResult ActOnDeclStmt(DeclGroupPtrTy Decl,
                                    SourceLocation StartLoc,
                                    SourceLocation EndLoc);
   void ActOnForEachDeclStmt(DeclGroupPtrTy Decl);
   StmtResult ActOnForEachLValueExpr(Expr *E);
   ExprResult ActOnCaseExpr(SourceLocation CaseLoc, ExprResult Val);
   StmtResult ActOnCaseStmt(SourceLocation CaseLoc, ExprResult LHS,
                            SourceLocation DotDotDotLoc, ExprResult RHS,
                            SourceLocation ColonLoc);
   void ActOnCaseStmtBody(Stmt *CaseStmt, Stmt *SubStmt);
 
   StmtResult ActOnDefaultStmt(SourceLocation DefaultLoc,
                                       SourceLocation ColonLoc,
                                       Stmt *SubStmt, Scope *CurScope);
   StmtResult ActOnLabelStmt(SourceLocation IdentLoc, LabelDecl *TheDecl,
                             SourceLocation ColonLoc, Stmt *SubStmt);
 
   StmtResult BuildAttributedStmt(SourceLocation AttrsLoc,
                                  ArrayRef<const Attr *> Attrs, Stmt *SubStmt);
   StmtResult ActOnAttributedStmt(const ParsedAttributes &AttrList,
                                  Stmt *SubStmt);
 
   class ConditionResult;
 
   StmtResult ActOnIfStmt(SourceLocation IfLoc, IfStatementKind StatementKind,
                          SourceLocation LParenLoc, Stmt *InitStmt,
                          ConditionResult Cond, SourceLocation RParenLoc,
                          Stmt *ThenVal, SourceLocation ElseLoc, Stmt *ElseVal);
   StmtResult BuildIfStmt(SourceLocation IfLoc, IfStatementKind StatementKind,
                          SourceLocation LParenLoc, Stmt *InitStmt,
                          ConditionResult Cond, SourceLocation RParenLoc,
                          Stmt *ThenVal, SourceLocation ElseLoc, Stmt *ElseVal);
   StmtResult ActOnStartOfSwitchStmt(SourceLocation SwitchLoc,
                                     SourceLocation LParenLoc, Stmt *InitStmt,
                                     ConditionResult Cond,
                                     SourceLocation RParenLoc);
   StmtResult ActOnFinishSwitchStmt(SourceLocation SwitchLoc,
                                            Stmt *Switch, Stmt *Body);
   StmtResult ActOnWhileStmt(SourceLocation WhileLoc, SourceLocation LParenLoc,
                             ConditionResult Cond, SourceLocation RParenLoc,
                             Stmt *Body);
   StmtResult ActOnDoStmt(SourceLocation DoLoc, Stmt *Body,
                          SourceLocation WhileLoc, SourceLocation CondLParen,
                          Expr *Cond, SourceLocation CondRParen);
 
   StmtResult ActOnForStmt(SourceLocation ForLoc,
                           SourceLocation LParenLoc,
                           Stmt *First,
                           ConditionResult Second,
                           FullExprArg Third,
                           SourceLocation RParenLoc,
                           Stmt *Body);
   ExprResult CheckObjCForCollectionOperand(SourceLocation forLoc,
                                            Expr *collection);
   StmtResult ActOnObjCForCollectionStmt(SourceLocation ForColLoc,
                                         Stmt *First, Expr *collection,
                                         SourceLocation RParenLoc);
   StmtResult FinishObjCForCollectionStmt(Stmt *ForCollection, Stmt *Body);
 
   enum BuildForRangeKind {
     /// Initial building of a for-range statement.
     BFRK_Build,
     /// Instantiation or recovery rebuild of a for-range statement. Don't
     /// attempt any typo-correction.
     BFRK_Rebuild,
     /// Determining whether a for-range statement could be built. Avoid any
     /// unnecessary or irreversible actions.
     BFRK_Check
   };
 
   StmtResult ActOnCXXForRangeStmt(Scope *S, SourceLocation ForLoc,
                                   SourceLocation CoawaitLoc,
                                   Stmt *InitStmt,
                                   Stmt *LoopVar,
                                   SourceLocation ColonLoc, Expr *Collection,
                                   SourceLocation RParenLoc,
                                   BuildForRangeKind Kind);
   StmtResult BuildCXXForRangeStmt(SourceLocation ForLoc,
                                   SourceLocation CoawaitLoc,
                                   Stmt *InitStmt,
                                   SourceLocation ColonLoc,
                                   Stmt *RangeDecl, Stmt *Begin, Stmt *End,
                                   Expr *Cond, Expr *Inc,
                                   Stmt *LoopVarDecl,
                                   SourceLocation RParenLoc,
                                   BuildForRangeKind Kind);
   StmtResult FinishCXXForRangeStmt(Stmt *ForRange, Stmt *Body);
 
   StmtResult ActOnGotoStmt(SourceLocation GotoLoc,
                            SourceLocation LabelLoc,
                            LabelDecl *TheDecl);
   StmtResult ActOnIndirectGotoStmt(SourceLocation GotoLoc,
                                    SourceLocation StarLoc,
                                    Expr *DestExp);
   StmtResult ActOnContinueStmt(SourceLocation ContinueLoc, Scope *CurScope);
   StmtResult ActOnBreakStmt(SourceLocation BreakLoc, Scope *CurScope);
 
   void ActOnCapturedRegionStart(SourceLocation Loc, Scope *CurScope,
                                 CapturedRegionKind Kind, unsigned NumParams);
   typedef std::pair<StringRef, QualType> CapturedParamNameType;
   void ActOnCapturedRegionStart(SourceLocation Loc, Scope *CurScope,
                                 CapturedRegionKind Kind,
                                 ArrayRef<CapturedParamNameType> Params,
                                 unsigned OpenMPCaptureLevel = 0);
   StmtResult ActOnCapturedRegionEnd(Stmt *S);
   void ActOnCapturedRegionError();
   RecordDecl *CreateCapturedStmtRecordDecl(CapturedDecl *&CD,
                                            SourceLocation Loc,
                                            unsigned NumParams);
 
   struct NamedReturnInfo {
     const VarDecl *Candidate;
 
     enum Status : uint8_t { None, MoveEligible, MoveEligibleAndCopyElidable };
     Status S;
 
     bool isMoveEligible() const { return S != None; };
     bool isCopyElidable() const { return S == MoveEligibleAndCopyElidable; }
   };
   enum class SimplerImplicitMoveMode { ForceOff, Normal, ForceOn };
   NamedReturnInfo getNamedReturnInfo(
       Expr *&E, SimplerImplicitMoveMode Mode = SimplerImplicitMoveMode::Normal);
   NamedReturnInfo getNamedReturnInfo(const VarDecl *VD);
   const VarDecl *getCopyElisionCandidate(NamedReturnInfo &Info,
                                          QualType ReturnType);
 
   ExprResult
   PerformMoveOrCopyInitialization(const InitializedEntity &Entity,
                                   const NamedReturnInfo &NRInfo, Expr *Value,
                                   bool SupressSimplerImplicitMoves = false);
 
   StmtResult ActOnReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp,
                              Scope *CurScope);
   StmtResult BuildReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp,
                              bool AllowRecovery = false);
   StmtResult ActOnCapScopeReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp,
                                      NamedReturnInfo &NRInfo,
                                      bool SupressSimplerImplicitMoves);
 
   StmtResult ActOnGCCAsmStmt(SourceLocation AsmLoc, bool IsSimple,
                              bool IsVolatile, unsigned NumOutputs,
                              unsigned NumInputs, IdentifierInfo **Names,
                              MultiExprArg Constraints, MultiExprArg Exprs,
                              Expr *AsmString, MultiExprArg Clobbers,
                              unsigned NumLabels,
                              SourceLocation RParenLoc);
 
   void FillInlineAsmIdentifierInfo(Expr *Res,
                                    llvm::InlineAsmIdentifierInfo &Info);
   ExprResult LookupInlineAsmIdentifier(CXXScopeSpec &SS,
                                        SourceLocation TemplateKWLoc,
                                        UnqualifiedId &Id,
                                        bool IsUnevaluatedContext);
   bool LookupInlineAsmField(StringRef Base, StringRef Member,
                             unsigned &Offset, SourceLocation AsmLoc);
   ExprResult LookupInlineAsmVarDeclField(Expr *RefExpr, StringRef Member,
                                          SourceLocation AsmLoc);
   StmtResult ActOnMSAsmStmt(SourceLocation AsmLoc, SourceLocation LBraceLoc,
                             ArrayRef<Token> AsmToks,
                             StringRef AsmString,
                             unsigned NumOutputs, unsigned NumInputs,
                             ArrayRef<StringRef> Constraints,
                             ArrayRef<StringRef> Clobbers,
                             ArrayRef<Expr*> Exprs,
                             SourceLocation EndLoc);
   LabelDecl *GetOrCreateMSAsmLabel(StringRef ExternalLabelName,
                                    SourceLocation Location,
                                    bool AlwaysCreate);
 
   VarDecl *BuildObjCExceptionDecl(TypeSourceInfo *TInfo, QualType ExceptionType,
                                   SourceLocation StartLoc,
                                   SourceLocation IdLoc, IdentifierInfo *Id,
                                   bool Invalid = false);
 
   Decl *ActOnObjCExceptionDecl(Scope *S, Declarator &D);
 
   StmtResult ActOnObjCAtCatchStmt(SourceLocation AtLoc, SourceLocation RParen,
                                   Decl *Parm, Stmt *Body);
 
   StmtResult ActOnObjCAtFinallyStmt(SourceLocation AtLoc, Stmt *Body);
 
   StmtResult ActOnObjCAtTryStmt(SourceLocation AtLoc, Stmt *Try,
                                 MultiStmtArg Catch, Stmt *Finally);
 
   StmtResult BuildObjCAtThrowStmt(SourceLocation AtLoc, Expr *Throw);
   StmtResult ActOnObjCAtThrowStmt(SourceLocation AtLoc, Expr *Throw,
                                   Scope *CurScope);
   ExprResult ActOnObjCAtSynchronizedOperand(SourceLocation atLoc,
                                             Expr *operand);
   StmtResult ActOnObjCAtSynchronizedStmt(SourceLocation AtLoc,
                                          Expr *SynchExpr,
                                          Stmt *SynchBody);
 
   StmtResult ActOnObjCAutoreleasePoolStmt(SourceLocation AtLoc, Stmt *Body);
 
   VarDecl *BuildExceptionDeclaration(Scope *S, TypeSourceInfo *TInfo,
                                      SourceLocation StartLoc,
                                      SourceLocation IdLoc,
                                      IdentifierInfo *Id);
 
   Decl *ActOnExceptionDeclarator(Scope *S, Declarator &D);
 
   StmtResult ActOnCXXCatchBlock(SourceLocation CatchLoc,
                                 Decl *ExDecl, Stmt *HandlerBlock);
   StmtResult ActOnCXXTryBlock(SourceLocation TryLoc, Stmt *TryBlock,
                               ArrayRef<Stmt *> Handlers);
 
   StmtResult ActOnSEHTryBlock(bool IsCXXTry, // try (true) or __try (false) ?
                               SourceLocation TryLoc, Stmt *TryBlock,
                               Stmt *Handler);
   StmtResult ActOnSEHExceptBlock(SourceLocation Loc,
                                  Expr *FilterExpr,
                                  Stmt *Block);
   void ActOnStartSEHFinallyBlock();
   void ActOnAbortSEHFinallyBlock();
   StmtResult ActOnFinishSEHFinallyBlock(SourceLocation Loc, Stmt *Block);
   StmtResult ActOnSEHLeaveStmt(SourceLocation Loc, Scope *CurScope);
 
   void DiagnoseReturnInConstructorExceptionHandler(CXXTryStmt *TryBlock);
 
   bool ShouldWarnIfUnusedFileScopedDecl(const DeclaratorDecl *D) const;
 
   /// If it's a file scoped decl that must warn if not used, keep track
   /// of it.
   void MarkUnusedFileScopedDecl(const DeclaratorDecl *D);
 
   typedef llvm::function_ref<void(SourceLocation Loc, PartialDiagnostic PD)>
       DiagReceiverTy;
 
   /// DiagnoseUnusedExprResult - If the statement passed in is an expression
   /// whose result is unused, warn.
   void DiagnoseUnusedExprResult(const Stmt *S, unsigned DiagID);
   void DiagnoseUnusedNestedTypedefs(const RecordDecl *D);
   void DiagnoseUnusedNestedTypedefs(const RecordDecl *D,
                                     DiagReceiverTy DiagReceiver);
   void DiagnoseUnusedDecl(const NamedDecl *ND);
   void DiagnoseUnusedDecl(const NamedDecl *ND, DiagReceiverTy DiagReceiver);
 
   /// If VD is set but not otherwise used, diagnose, for a parameter or a
   /// variable.
   void DiagnoseUnusedButSetDecl(const VarDecl *VD, DiagReceiverTy DiagReceiver);
 
   /// Emit \p DiagID if statement located on \p StmtLoc has a suspicious null
   /// statement as a \p Body, and it is located on the same line.
   ///
   /// This helps prevent bugs due to typos, such as:
   ///     if (condition);
   ///       do_stuff();
   void DiagnoseEmptyStmtBody(SourceLocation StmtLoc,
                              const Stmt *Body,
                              unsigned DiagID);
 
   /// Warn if a for/while loop statement \p S, which is followed by
   /// \p PossibleBody, has a suspicious null statement as a body.
   void DiagnoseEmptyLoopBody(const Stmt *S,
                              const Stmt *PossibleBody);
 
   /// Warn if a value is moved to itself.
   void DiagnoseSelfMove(const Expr *LHSExpr, const Expr *RHSExpr,
                         SourceLocation OpLoc);
 
   /// Returns a field in a CXXRecordDecl that has the same name as the decl \p
   /// SelfAssigned when inside a CXXMethodDecl.
   const FieldDecl *
   getSelfAssignmentClassMemberCandidate(const ValueDecl *SelfAssigned);
 
   /// Warn if we're implicitly casting from a _Nullable pointer type to a
   /// _Nonnull one.
   void diagnoseNullableToNonnullConversion(QualType DstType, QualType SrcType,
                                            SourceLocation Loc);
 
   /// Warn when implicitly casting 0 to nullptr.
   void diagnoseZeroToNullptrConversion(CastKind Kind, const Expr *E);
 
   ParsingDeclState PushParsingDeclaration(sema::DelayedDiagnosticPool &pool) {
     return DelayedDiagnostics.push(pool);
   }
   void PopParsingDeclaration(ParsingDeclState state, Decl *decl);
 
   typedef ProcessingContextState ParsingClassState;
   ParsingClassState PushParsingClass() {
     ParsingClassDepth++;
     return DelayedDiagnostics.pushUndelayed();
   }
   void PopParsingClass(ParsingClassState state) {
     ParsingClassDepth--;
     DelayedDiagnostics.popUndelayed(state);
   }
 
   void redelayDiagnostics(sema::DelayedDiagnosticPool &pool);
 
   void DiagnoseAvailabilityOfDecl(NamedDecl *D, ArrayRef<SourceLocation> Locs,
                                   const ObjCInterfaceDecl *UnknownObjCClass,
                                   bool ObjCPropertyAccess,
                                   bool AvoidPartialAvailabilityChecks = false,
                                   ObjCInterfaceDecl *ClassReceiver = nullptr);
 
   bool makeUnavailableInSystemHeader(SourceLocation loc,
                                      UnavailableAttr::ImplicitReason reason);
 
   /// Issue any -Wunguarded-availability warnings in \c FD
   void DiagnoseUnguardedAvailabilityViolations(Decl *FD);
 
   void handleDelayedAvailabilityCheck(sema::DelayedDiagnostic &DD, Decl *Ctx);
 
   //===--------------------------------------------------------------------===//
   // Expression Parsing Callbacks: SemaExpr.cpp.
 
   bool CanUseDecl(NamedDecl *D, bool TreatUnavailableAsInvalid);
   // A version of DiagnoseUseOfDecl that should be used if overload resolution
   // has been used to find this declaration, which means we don't have to bother
   // checking the trailing requires clause.
   bool DiagnoseUseOfOverloadedDecl(NamedDecl *D, SourceLocation Loc) {
     return DiagnoseUseOfDecl(
         D, Loc, /*UnknownObjCClass=*/nullptr, /*ObjCPropertyAccess=*/false,
         /*AvoidPartialAvailabilityChecks=*/false, /*ClassReceiver=*/nullptr,
         /*SkipTrailingRequiresClause=*/true);
   }
 
   bool DiagnoseUseOfDecl(NamedDecl *D, ArrayRef<SourceLocation> Locs,
                          const ObjCInterfaceDecl *UnknownObjCClass = nullptr,
                          bool ObjCPropertyAccess = false,
                          bool AvoidPartialAvailabilityChecks = false,
                          ObjCInterfaceDecl *ClassReciever = nullptr,
                          bool SkipTrailingRequiresClause = false);
   void NoteDeletedFunction(FunctionDecl *FD);
   void NoteDeletedInheritingConstructor(CXXConstructorDecl *CD);
   bool DiagnosePropertyAccessorMismatch(ObjCPropertyDecl *PD,
                                         ObjCMethodDecl *Getter,
                                         SourceLocation Loc);
   void DiagnoseSentinelCalls(NamedDecl *D, SourceLocation Loc,
                              ArrayRef<Expr *> Args);
 
   void PushExpressionEvaluationContext(
       ExpressionEvaluationContext NewContext, Decl *LambdaContextDecl = nullptr,
       ExpressionEvaluationContextRecord::ExpressionKind Type =
           ExpressionEvaluationContextRecord::EK_Other);
   enum ReuseLambdaContextDecl_t { ReuseLambdaContextDecl };
   void PushExpressionEvaluationContext(
       ExpressionEvaluationContext NewContext, ReuseLambdaContextDecl_t,
       ExpressionEvaluationContextRecord::ExpressionKind Type =
           ExpressionEvaluationContextRecord::EK_Other);
   void PopExpressionEvaluationContext();
 
   void DiscardCleanupsInEvaluationContext();
 
   ExprResult TransformToPotentiallyEvaluated(Expr *E);
   TypeSourceInfo *TransformToPotentiallyEvaluated(TypeSourceInfo *TInfo);
   ExprResult HandleExprEvaluationContextForTypeof(Expr *E);
 
   ExprResult CheckUnevaluatedOperand(Expr *E);
   void CheckUnusedVolatileAssignment(Expr *E);
 
   ExprResult ActOnConstantExpression(ExprResult Res);
 
   // Functions for marking a declaration referenced.  These functions also
   // contain the relevant logic for marking if a reference to a function or
   // variable is an odr-use (in the C++11 sense).  There are separate variants
   // for expressions referring to a decl; these exist because odr-use marking
   // needs to be delayed for some constant variables when we build one of the
   // named expressions.
   //
   // MightBeOdrUse indicates whether the use could possibly be an odr-use, and
   // should usually be true. This only needs to be set to false if the lack of
   // odr-use cannot be determined from the current context (for instance,
   // because the name denotes a virtual function and was written without an
   // explicit nested-name-specifier).
   void MarkAnyDeclReferenced(SourceLocation Loc, Decl *D, bool MightBeOdrUse);
   void MarkFunctionReferenced(SourceLocation Loc, FunctionDecl *Func,
                               bool MightBeOdrUse = true);
   void MarkVariableReferenced(SourceLocation Loc, VarDecl *Var);
   void MarkDeclRefReferenced(DeclRefExpr *E, const Expr *Base = nullptr);
   void MarkMemberReferenced(MemberExpr *E);
   void MarkFunctionParmPackReferenced(FunctionParmPackExpr *E);
   void MarkCaptureUsedInEnclosingContext(ValueDecl *Capture, SourceLocation Loc,
                                          unsigned CapturingScopeIndex);
 
   ExprResult CheckLValueToRValueConversionOperand(Expr *E);
   void CleanupVarDeclMarking();
 
   enum TryCaptureKind {
     TryCapture_Implicit, TryCapture_ExplicitByVal, TryCapture_ExplicitByRef
   };
 
   /// Try to capture the given variable.
   ///
   /// \param Var The variable to capture.
   ///
   /// \param Loc The location at which the capture occurs.
   ///
   /// \param Kind The kind of capture, which may be implicit (for either a
   /// block or a lambda), or explicit by-value or by-reference (for a lambda).
   ///
   /// \param EllipsisLoc The location of the ellipsis, if one is provided in
   /// an explicit lambda capture.
   ///
   /// \param BuildAndDiagnose Whether we are actually supposed to add the
   /// captures or diagnose errors. If false, this routine merely check whether
   /// the capture can occur without performing the capture itself or complaining
   /// if the variable cannot be captured.
   ///
   /// \param CaptureType Will be set to the type of the field used to capture
   /// this variable in the innermost block or lambda. Only valid when the
   /// variable can be captured.
   ///
   /// \param DeclRefType Will be set to the type of a reference to the capture
   /// from within the current scope. Only valid when the variable can be
   /// captured.
   ///
   /// \param FunctionScopeIndexToStopAt If non-null, it points to the index
   /// of the FunctionScopeInfo stack beyond which we do not attempt to capture.
   /// This is useful when enclosing lambdas must speculatively capture
   /// variables that may or may not be used in certain specializations of
   /// a nested generic lambda.
   ///
   /// \returns true if an error occurred (i.e., the variable cannot be
   /// captured) and false if the capture succeeded.
   bool tryCaptureVariable(ValueDecl *Var, SourceLocation Loc,
                           TryCaptureKind Kind, SourceLocation EllipsisLoc,
                           bool BuildAndDiagnose, QualType &CaptureType,
                           QualType &DeclRefType,
                           const unsigned *const FunctionScopeIndexToStopAt);
 
   /// Try to capture the given variable.
   bool tryCaptureVariable(ValueDecl *Var, SourceLocation Loc,
                           TryCaptureKind Kind = TryCapture_Implicit,
                           SourceLocation EllipsisLoc = SourceLocation());
 
   /// Checks if the variable must be captured.
   bool NeedToCaptureVariable(ValueDecl *Var, SourceLocation Loc);
 
   /// Given a variable, determine the type that a reference to that
   /// variable will have in the given scope.
   QualType getCapturedDeclRefType(ValueDecl *Var, SourceLocation Loc);
 
   /// Mark all of the declarations referenced within a particular AST node as
   /// referenced. Used when template instantiation instantiates a non-dependent
   /// type -- entities referenced by the type are now referenced.
   void MarkDeclarationsReferencedInType(SourceLocation Loc, QualType T);
   void MarkDeclarationsReferencedInExpr(
       Expr *E, bool SkipLocalVariables = false,
       ArrayRef<const Expr *> StopAt = std::nullopt);
 
   /// Try to recover by turning the given expression into a
   /// call.  Returns true if recovery was attempted or an error was
   /// emitted; this may also leave the ExprResult invalid.
   bool tryToRecoverWithCall(ExprResult &E, const PartialDiagnostic &PD,
                             bool ForceComplain = false,
                             bool (*IsPlausibleResult)(QualType) = nullptr);
 
   /// Figure out if an expression could be turned into a call.
   bool tryExprAsCall(Expr &E, QualType &ZeroArgCallReturnTy,
                      UnresolvedSetImpl &NonTemplateOverloads);
 
   /// Try to convert an expression \p E to type \p Ty. Returns the result of the
   /// conversion.
   ExprResult tryConvertExprToType(Expr *E, QualType Ty);
 
   /// Conditionally issue a diagnostic based on the statements's reachability
   /// analysis.
   ///
   /// \param Stmts If Stmts is non-empty, delay reporting the diagnostic until
   /// the function body is parsed, and then do a basic reachability analysis to
   /// determine if the statement is reachable. If it is unreachable, the
   /// diagnostic will not be emitted.
   bool DiagIfReachable(SourceLocation Loc, ArrayRef<const Stmt *> Stmts,
                        const PartialDiagnostic &PD);
 
   /// Conditionally issue a diagnostic based on the current
   /// evaluation context.
   ///
   /// \param Statement If Statement is non-null, delay reporting the
   /// diagnostic until the function body is parsed, and then do a basic
   /// reachability analysis to determine if the statement is reachable.
   /// If it is unreachable, the diagnostic will not be emitted.
   bool DiagRuntimeBehavior(SourceLocation Loc, const Stmt *Statement,
                            const PartialDiagnostic &PD);
   /// Similar, but diagnostic is only produced if all the specified statements
   /// are reachable.
   bool DiagRuntimeBehavior(SourceLocation Loc, ArrayRef<const Stmt*> Stmts,
                            const PartialDiagnostic &PD);
 
   // Primary Expressions.
   SourceRange getExprRange(Expr *E) const;
 
   ExprResult ActOnIdExpression(
       Scope *S, CXXScopeSpec &SS, SourceLocation TemplateKWLoc,
       UnqualifiedId &Id, bool HasTrailingLParen, bool IsAddressOfOperand,
       CorrectionCandidateCallback *CCC = nullptr,
       bool IsInlineAsmIdentifier = false, Token *KeywordReplacement = nullptr);
 
   void DecomposeUnqualifiedId(const UnqualifiedId &Id,
                               TemplateArgumentListInfo &Buffer,
                               DeclarationNameInfo &NameInfo,
                               const TemplateArgumentListInfo *&TemplateArgs);
 
   bool DiagnoseDependentMemberLookup(const LookupResult &R);
 
   bool
   DiagnoseEmptyLookup(Scope *S, CXXScopeSpec &SS, LookupResult &R,
                       CorrectionCandidateCallback &CCC,
                       TemplateArgumentListInfo *ExplicitTemplateArgs = nullptr,
                       ArrayRef<Expr *> Args = std::nullopt,
                       TypoExpr **Out = nullptr);
 
   DeclResult LookupIvarInObjCMethod(LookupResult &Lookup, Scope *S,
                                     IdentifierInfo *II);
   ExprResult BuildIvarRefExpr(Scope *S, SourceLocation Loc, ObjCIvarDecl *IV);
 
   ExprResult LookupInObjCMethod(LookupResult &LookUp, Scope *S,
                                 IdentifierInfo *II,
                                 bool AllowBuiltinCreation=false);
 
   ExprResult ActOnDependentIdExpression(const CXXScopeSpec &SS,
                                         SourceLocation TemplateKWLoc,
                                         const DeclarationNameInfo &NameInfo,
                                         bool isAddressOfOperand,
                                 const TemplateArgumentListInfo *TemplateArgs);
 
   /// If \p D cannot be odr-used in the current expression evaluation context,
   /// return a reason explaining why. Otherwise, return NOUR_None.
   NonOdrUseReason getNonOdrUseReasonInCurrentContext(ValueDecl *D);
 
   DeclRefExpr *BuildDeclRefExpr(ValueDecl *D, QualType Ty, ExprValueKind VK,
                                 SourceLocation Loc,
                                 const CXXScopeSpec *SS = nullptr);
   DeclRefExpr *
   BuildDeclRefExpr(ValueDecl *D, QualType Ty, ExprValueKind VK,
                    const DeclarationNameInfo &NameInfo,
                    const CXXScopeSpec *SS = nullptr,
                    NamedDecl *FoundD = nullptr,
                    SourceLocation TemplateKWLoc = SourceLocation(),
                    const TemplateArgumentListInfo *TemplateArgs = nullptr);
   DeclRefExpr *
   BuildDeclRefExpr(ValueDecl *D, QualType Ty, ExprValueKind VK,
                    const DeclarationNameInfo &NameInfo,
                    NestedNameSpecifierLoc NNS,
                    NamedDecl *FoundD = nullptr,
                    SourceLocation TemplateKWLoc = SourceLocation(),
                    const TemplateArgumentListInfo *TemplateArgs = nullptr);
 
   ExprResult
   BuildAnonymousStructUnionMemberReference(
       const CXXScopeSpec &SS,
       SourceLocation nameLoc,
       IndirectFieldDecl *indirectField,
       DeclAccessPair FoundDecl = DeclAccessPair::make(nullptr, AS_none),
       Expr *baseObjectExpr = nullptr,
       SourceLocation opLoc = SourceLocation());
 
   ExprResult BuildPossibleImplicitMemberExpr(
       const CXXScopeSpec &SS, SourceLocation TemplateKWLoc, LookupResult &R,
       const TemplateArgumentListInfo *TemplateArgs, const Scope *S,
       UnresolvedLookupExpr *AsULE = nullptr);
   ExprResult BuildImplicitMemberExpr(const CXXScopeSpec &SS,
                                      SourceLocation TemplateKWLoc,
                                      LookupResult &R,
                                 const TemplateArgumentListInfo *TemplateArgs,
                                      bool IsDefiniteInstance,
                                      const Scope *S);
   bool UseArgumentDependentLookup(const CXXScopeSpec &SS,
                                   const LookupResult &R,
                                   bool HasTrailingLParen);
 
   ExprResult
   BuildQualifiedDeclarationNameExpr(CXXScopeSpec &SS,
                                     const DeclarationNameInfo &NameInfo,
                                     bool IsAddressOfOperand, const Scope *S,
                                     TypeSourceInfo **RecoveryTSI = nullptr);
 
   ExprResult BuildDependentDeclRefExpr(const CXXScopeSpec &SS,
                                        SourceLocation TemplateKWLoc,
                                 const DeclarationNameInfo &NameInfo,
                                 const TemplateArgumentListInfo *TemplateArgs);
 
   ExprResult BuildDeclarationNameExpr(const CXXScopeSpec &SS,
                                       LookupResult &R,
                                       bool NeedsADL,
                                       bool AcceptInvalidDecl = false);
   ExprResult BuildDeclarationNameExpr(
       const CXXScopeSpec &SS, const DeclarationNameInfo &NameInfo, NamedDecl *D,
       NamedDecl *FoundD = nullptr,
       const TemplateArgumentListInfo *TemplateArgs = nullptr,
       bool AcceptInvalidDecl = false);
 
   ExprResult BuildLiteralOperatorCall(LookupResult &R,
                       DeclarationNameInfo &SuffixInfo,
                       ArrayRef<Expr *> Args,
                       SourceLocation LitEndLoc,
                       TemplateArgumentListInfo *ExplicitTemplateArgs = nullptr);
 
   ExprResult BuildPredefinedExpr(SourceLocation Loc,
                                  PredefinedExpr::IdentKind IK);
   ExprResult ActOnPredefinedExpr(SourceLocation Loc, tok::TokenKind Kind);
   ExprResult ActOnIntegerConstant(SourceLocation Loc, uint64_t Val);
 
   ExprResult BuildSYCLUniqueStableNameExpr(SourceLocation OpLoc,
                                            SourceLocation LParen,
                                            SourceLocation RParen,
                                            TypeSourceInfo *TSI);
   ExprResult ActOnSYCLUniqueStableNameExpr(SourceLocation OpLoc,
                                            SourceLocation LParen,
                                            SourceLocation RParen,
                                            ParsedType ParsedTy);
 
   bool CheckLoopHintExpr(Expr *E, SourceLocation Loc);
 
   ExprResult ActOnNumericConstant(const Token &Tok, Scope *UDLScope = nullptr);
   ExprResult ActOnCharacterConstant(const Token &Tok,
                                     Scope *UDLScope = nullptr);
   ExprResult ActOnParenExpr(SourceLocation L, SourceLocation R, Expr *E);
   ExprResult ActOnParenListExpr(SourceLocation L,
                                 SourceLocation R,
                                 MultiExprArg Val);
 
   /// ActOnStringLiteral - The specified tokens were lexed as pasted string
   /// fragments (e.g. "foo" "bar" L"baz").
   ExprResult ActOnStringLiteral(ArrayRef<Token> StringToks,
                                 Scope *UDLScope = nullptr);
 
   ExprResult ActOnUnevaluatedStringLiteral(ArrayRef<Token> StringToks);
 
   /// ControllingExprOrType is either an opaque pointer coming out of a
   /// ParsedType or an Expr *. FIXME: it'd be better to split this interface
   /// into two so we don't take a void *, but that's awkward because one of
   /// the operands is either a ParsedType or an Expr *, which doesn't lend
   /// itself to generic code very well.
   ExprResult ActOnGenericSelectionExpr(SourceLocation KeyLoc,
                                        SourceLocation DefaultLoc,
                                        SourceLocation RParenLoc,
                                        bool PredicateIsExpr,
                                        void *ControllingExprOrType,
                                        ArrayRef<ParsedType> ArgTypes,
                                        ArrayRef<Expr *> ArgExprs);
   /// ControllingExprOrType is either a TypeSourceInfo * or an Expr *. FIXME:
   /// it'd be better to split this interface into two so we don't take a
   /// void *, but see the FIXME on ActOnGenericSelectionExpr as to why that
   /// isn't a trivial change.
   ExprResult CreateGenericSelectionExpr(SourceLocation KeyLoc,
                                         SourceLocation DefaultLoc,
                                         SourceLocation RParenLoc,
                                         bool PredicateIsExpr,
                                         void *ControllingExprOrType,
                                         ArrayRef<TypeSourceInfo *> Types,
                                         ArrayRef<Expr *> Exprs);
 
   // Binary/Unary Operators.  'Tok' is the token for the operator.
   ExprResult CreateBuiltinUnaryOp(SourceLocation OpLoc, UnaryOperatorKind Opc,
                                   Expr *InputExpr, bool IsAfterAmp = false);
   ExprResult BuildUnaryOp(Scope *S, SourceLocation OpLoc, UnaryOperatorKind Opc,
                           Expr *Input, bool IsAfterAmp = false);
   ExprResult ActOnUnaryOp(Scope *S, SourceLocation OpLoc, tok::TokenKind Op,
                           Expr *Input, bool IsAfterAmp = false);
 
   bool isQualifiedMemberAccess(Expr *E);
   QualType CheckAddressOfOperand(ExprResult &Operand, SourceLocation OpLoc);
 
   bool CheckTypeTraitArity(unsigned Arity, SourceLocation Loc, size_t N);
 
   bool ActOnAlignasTypeArgument(StringRef KWName, ParsedType Ty,
                                 SourceLocation OpLoc, SourceRange R);
   bool CheckAlignasTypeArgument(StringRef KWName, TypeSourceInfo *TInfo,
                                 SourceLocation OpLoc, SourceRange R);
 
   ExprResult CreateUnaryExprOrTypeTraitExpr(TypeSourceInfo *TInfo,
                                             SourceLocation OpLoc,
                                             UnaryExprOrTypeTrait ExprKind,
                                             SourceRange R);
   ExprResult CreateUnaryExprOrTypeTraitExpr(Expr *E, SourceLocation OpLoc,
                                             UnaryExprOrTypeTrait ExprKind);
   ExprResult
     ActOnUnaryExprOrTypeTraitExpr(SourceLocation OpLoc,
                                   UnaryExprOrTypeTrait ExprKind,
                                   bool IsType, void *TyOrEx,
                                   SourceRange ArgRange);
 
   ExprResult CheckPlaceholderExpr(Expr *E);
   bool CheckVecStepExpr(Expr *E);
 
   bool CheckUnaryExprOrTypeTraitOperand(Expr *E, UnaryExprOrTypeTrait ExprKind);
   bool CheckUnaryExprOrTypeTraitOperand(QualType ExprType, SourceLocation OpLoc,
                                         SourceRange ExprRange,
                                         UnaryExprOrTypeTrait ExprKind,
                                         StringRef KWName);
   ExprResult ActOnSizeofParameterPackExpr(Scope *S,
                                           SourceLocation OpLoc,
                                           IdentifierInfo &Name,
                                           SourceLocation NameLoc,
                                           SourceLocation RParenLoc);
   ExprResult ActOnPostfixUnaryOp(Scope *S, SourceLocation OpLoc,
                                  tok::TokenKind Kind, Expr *Input);
 
   ExprResult ActOnArraySubscriptExpr(Scope *S, Expr *Base, SourceLocation LLoc,
                                      MultiExprArg ArgExprs,
                                      SourceLocation RLoc);
   ExprResult CreateBuiltinArraySubscriptExpr(Expr *Base, SourceLocation LLoc,
                                              Expr *Idx, SourceLocation RLoc);
 
   ExprResult CreateBuiltinMatrixSubscriptExpr(Expr *Base, Expr *RowIdx,
                                               Expr *ColumnIdx,
                                               SourceLocation RBLoc);
 
   ExprResult ActOnOMPArraySectionExpr(Expr *Base, SourceLocation LBLoc,
                                       Expr *LowerBound,
                                       SourceLocation ColonLocFirst,
                                       SourceLocation ColonLocSecond,
                                       Expr *Length, Expr *Stride,
                                       SourceLocation RBLoc);
   ExprResult ActOnOMPArrayShapingExpr(Expr *Base, SourceLocation LParenLoc,
                                       SourceLocation RParenLoc,
                                       ArrayRef<Expr *> Dims,
                                       ArrayRef<SourceRange> Brackets);
 
   /// Data structure for iterator expression.
   struct OMPIteratorData {
     IdentifierInfo *DeclIdent = nullptr;
     SourceLocation DeclIdentLoc;
     ParsedType Type;
     OMPIteratorExpr::IteratorRange Range;
     SourceLocation AssignLoc;
     SourceLocation ColonLoc;
     SourceLocation SecColonLoc;
   };
 
   ExprResult ActOnOMPIteratorExpr(Scope *S, SourceLocation IteratorKwLoc,
                                   SourceLocation LLoc, SourceLocation RLoc,
                                   ArrayRef<OMPIteratorData> Data);
 
   // This struct is for use by ActOnMemberAccess to allow
   // BuildMemberReferenceExpr to be able to reinvoke ActOnMemberAccess after
   // changing the access operator from a '.' to a '->' (to see if that is the
   // change needed to fix an error about an unknown member, e.g. when the class
   // defines a custom operator->).
   struct ActOnMemberAccessExtraArgs {
     Scope *S;
     UnqualifiedId &Id;
     Decl *ObjCImpDecl;
   };
 
   ExprResult BuildMemberReferenceExpr(
       Expr *Base, QualType BaseType, SourceLocation OpLoc, bool IsArrow,
       CXXScopeSpec &SS, SourceLocation TemplateKWLoc,
       NamedDecl *FirstQualifierInScope, const DeclarationNameInfo &NameInfo,
       const TemplateArgumentListInfo *TemplateArgs,
       const Scope *S,
       ActOnMemberAccessExtraArgs *ExtraArgs = nullptr);
 
   ExprResult
   BuildMemberReferenceExpr(Expr *Base, QualType BaseType, SourceLocation OpLoc,
                            bool IsArrow, const CXXScopeSpec &SS,
                            SourceLocation TemplateKWLoc,
                            NamedDecl *FirstQualifierInScope, LookupResult &R,
                            const TemplateArgumentListInfo *TemplateArgs,
                            const Scope *S,
                            bool SuppressQualifierCheck = false,
                            ActOnMemberAccessExtraArgs *ExtraArgs = nullptr);
 
   ExprResult BuildFieldReferenceExpr(Expr *BaseExpr, bool IsArrow,
                                      SourceLocation OpLoc,
                                      const CXXScopeSpec &SS, FieldDecl *Field,
                                      DeclAccessPair FoundDecl,
                                      const DeclarationNameInfo &MemberNameInfo);
 
   ExprResult PerformMemberExprBaseConversion(Expr *Base, bool IsArrow);
 
   bool CheckQualifiedMemberReference(Expr *BaseExpr, QualType BaseType,
                                      const CXXScopeSpec &SS,
                                      const LookupResult &R);
 
   ExprResult ActOnDependentMemberExpr(Expr *Base, QualType BaseType,
                                       bool IsArrow, SourceLocation OpLoc,
                                       const CXXScopeSpec &SS,
                                       SourceLocation TemplateKWLoc,
                                       NamedDecl *FirstQualifierInScope,
                                const DeclarationNameInfo &NameInfo,
                                const TemplateArgumentListInfo *TemplateArgs);
 
   ExprResult ActOnMemberAccessExpr(Scope *S, Expr *Base,
                                    SourceLocation OpLoc,
                                    tok::TokenKind OpKind,
                                    CXXScopeSpec &SS,
                                    SourceLocation TemplateKWLoc,
                                    UnqualifiedId &Member,
                                    Decl *ObjCImpDecl);
 
   MemberExpr *
   BuildMemberExpr(Expr *Base, bool IsArrow, SourceLocation OpLoc,
                   const CXXScopeSpec *SS, SourceLocation TemplateKWLoc,
                   ValueDecl *Member, DeclAccessPair FoundDecl,
                   bool HadMultipleCandidates,
                   const DeclarationNameInfo &MemberNameInfo, QualType Ty,
                   ExprValueKind VK, ExprObjectKind OK,
                   const TemplateArgumentListInfo *TemplateArgs = nullptr);
   MemberExpr *
   BuildMemberExpr(Expr *Base, bool IsArrow, SourceLocation OpLoc,
                   NestedNameSpecifierLoc NNS, SourceLocation TemplateKWLoc,
                   ValueDecl *Member, DeclAccessPair FoundDecl,
                   bool HadMultipleCandidates,
                   const DeclarationNameInfo &MemberNameInfo, QualType Ty,
                   ExprValueKind VK, ExprObjectKind OK,
                   const TemplateArgumentListInfo *TemplateArgs = nullptr);
 
   void ActOnDefaultCtorInitializers(Decl *CDtorDecl);
   bool ConvertArgumentsForCall(CallExpr *Call, Expr *Fn,
                                FunctionDecl *FDecl,
                                const FunctionProtoType *Proto,
                                ArrayRef<Expr *> Args,
                                SourceLocation RParenLoc,
                                bool ExecConfig = false);
   void CheckStaticArrayArgument(SourceLocation CallLoc,
                                 ParmVarDecl *Param,
                                 const Expr *ArgExpr);
 
   /// ActOnCallExpr - Handle a call to Fn with the specified array of arguments.
   /// This provides the location of the left/right parens and a list of comma
   /// locations.
   ExprResult ActOnCallExpr(Scope *S, Expr *Fn, SourceLocation LParenLoc,
                            MultiExprArg ArgExprs, SourceLocation RParenLoc,
                            Expr *ExecConfig = nullptr);
   ExprResult BuildCallExpr(Scope *S, Expr *Fn, SourceLocation LParenLoc,
                            MultiExprArg ArgExprs, SourceLocation RParenLoc,
                            Expr *ExecConfig = nullptr,
                            bool IsExecConfig = false,
                            bool AllowRecovery = false);
   Expr *BuildBuiltinCallExpr(SourceLocation Loc, Builtin::ID Id,
                              MultiExprArg CallArgs);
   enum class AtomicArgumentOrder { API, AST };
   ExprResult
   BuildAtomicExpr(SourceRange CallRange, SourceRange ExprRange,
                   SourceLocation RParenLoc, MultiExprArg Args,
                   AtomicExpr::AtomicOp Op,
                   AtomicArgumentOrder ArgOrder = AtomicArgumentOrder::API);
   ExprResult
   BuildResolvedCallExpr(Expr *Fn, NamedDecl *NDecl, SourceLocation LParenLoc,
                         ArrayRef<Expr *> Arg, SourceLocation RParenLoc,
                         Expr *Config = nullptr, bool IsExecConfig = false,
                         ADLCallKind UsesADL = ADLCallKind::NotADL);
 
   ExprResult ActOnCUDAExecConfigExpr(Scope *S, SourceLocation LLLLoc,
                                      MultiExprArg ExecConfig,
                                      SourceLocation GGGLoc);
 
   ExprResult ActOnCastExpr(Scope *S, SourceLocation LParenLoc,
                            Declarator &D, ParsedType &Ty,
                            SourceLocation RParenLoc, Expr *CastExpr);
   ExprResult BuildCStyleCastExpr(SourceLocation LParenLoc,
                                  TypeSourceInfo *Ty,
                                  SourceLocation RParenLoc,
                                  Expr *Op);
   CastKind PrepareScalarCast(ExprResult &src, QualType destType);
 
   /// Build an altivec or OpenCL literal.
   ExprResult BuildVectorLiteral(SourceLocation LParenLoc,
                                 SourceLocation RParenLoc, Expr *E,
                                 TypeSourceInfo *TInfo);
 
   ExprResult MaybeConvertParenListExprToParenExpr(Scope *S, Expr *ME);
 
   ExprResult ActOnCompoundLiteral(SourceLocation LParenLoc,
                                   ParsedType Ty,
                                   SourceLocation RParenLoc,
                                   Expr *InitExpr);
 
   ExprResult BuildCompoundLiteralExpr(SourceLocation LParenLoc,
                                       TypeSourceInfo *TInfo,
                                       SourceLocation RParenLoc,
                                       Expr *LiteralExpr);
 
   ExprResult ActOnInitList(SourceLocation LBraceLoc,
                            MultiExprArg InitArgList,
                            SourceLocation RBraceLoc);
 
   ExprResult BuildInitList(SourceLocation LBraceLoc,
                            MultiExprArg InitArgList,
                            SourceLocation RBraceLoc);
 
   ExprResult ActOnDesignatedInitializer(Designation &Desig,
                                         SourceLocation EqualOrColonLoc,
                                         bool GNUSyntax,
                                         ExprResult Init);
 
 private:
   static BinaryOperatorKind ConvertTokenKindToBinaryOpcode(tok::TokenKind Kind);
 
 public:
   ExprResult ActOnBinOp(Scope *S, SourceLocation TokLoc,
                         tok::TokenKind Kind, Expr *LHSExpr, Expr *RHSExpr);
   ExprResult BuildBinOp(Scope *S, SourceLocation OpLoc,
                         BinaryOperatorKind Opc, Expr *LHSExpr, Expr *RHSExpr);
   ExprResult CreateBuiltinBinOp(SourceLocation OpLoc, BinaryOperatorKind Opc,
                                 Expr *LHSExpr, Expr *RHSExpr);
   void LookupBinOp(Scope *S, SourceLocation OpLoc, BinaryOperatorKind Opc,
                    UnresolvedSetImpl &Functions);
 
   void DiagnoseCommaOperator(const Expr *LHS, SourceLocation Loc);
 
   /// ActOnConditionalOp - Parse a ?: operation.  Note that 'LHS' may be null
   /// in the case of a the GNU conditional expr extension.
   ExprResult ActOnConditionalOp(SourceLocation QuestionLoc,
                                 SourceLocation ColonLoc,
                                 Expr *CondExpr, Expr *LHSExpr, Expr *RHSExpr);
 
   /// ActOnAddrLabel - Parse the GNU address of label extension: "&&foo".
   ExprResult ActOnAddrLabel(SourceLocation OpLoc, SourceLocation LabLoc,
                             LabelDecl *TheDecl);
 
   void ActOnStartStmtExpr();
   ExprResult ActOnStmtExpr(Scope *S, SourceLocation LPLoc, Stmt *SubStmt,
                            SourceLocation RPLoc);
   ExprResult BuildStmtExpr(SourceLocation LPLoc, Stmt *SubStmt,
                            SourceLocation RPLoc, unsigned TemplateDepth);
   // Handle the final expression in a statement expression.
   ExprResult ActOnStmtExprResult(ExprResult E);
   void ActOnStmtExprError();
 
   // __builtin_offsetof(type, identifier(.identifier|[expr])*)
   struct OffsetOfComponent {
     SourceLocation LocStart, LocEnd;
     bool isBrackets;  // true if [expr], false if .ident
     union {
       IdentifierInfo *IdentInfo;
       Expr *E;
     } U;
   };
 
   /// __builtin_offsetof(type, a.b[123][456].c)
   ExprResult BuildBuiltinOffsetOf(SourceLocation BuiltinLoc,
                                   TypeSourceInfo *TInfo,
                                   ArrayRef<OffsetOfComponent> Components,
                                   SourceLocation RParenLoc);
   ExprResult ActOnBuiltinOffsetOf(Scope *S,
                                   SourceLocation BuiltinLoc,
                                   SourceLocation TypeLoc,
                                   ParsedType ParsedArgTy,
                                   ArrayRef<OffsetOfComponent> Components,
                                   SourceLocation RParenLoc);
 
   // __builtin_choose_expr(constExpr, expr1, expr2)
   ExprResult ActOnChooseExpr(SourceLocation BuiltinLoc,
                              Expr *CondExpr, Expr *LHSExpr,
                              Expr *RHSExpr, SourceLocation RPLoc);
 
   // __builtin_va_arg(expr, type)
   ExprResult ActOnVAArg(SourceLocation BuiltinLoc, Expr *E, ParsedType Ty,
                         SourceLocation RPLoc);
   ExprResult BuildVAArgExpr(SourceLocation BuiltinLoc, Expr *E,
                             TypeSourceInfo *TInfo, SourceLocation RPLoc);
 
   // __builtin_LINE(), __builtin_FUNCTION(), __builtin_FUNCSIG(),
   // __builtin_FILE(), __builtin_COLUMN(), __builtin_source_location()
   ExprResult ActOnSourceLocExpr(SourceLocExpr::IdentKind Kind,
                                 SourceLocation BuiltinLoc,
                                 SourceLocation RPLoc);
 
   // Build a potentially resolved SourceLocExpr.
   ExprResult BuildSourceLocExpr(SourceLocExpr::IdentKind Kind,
                                 QualType ResultTy, SourceLocation BuiltinLoc,
                                 SourceLocation RPLoc,
                                 DeclContext *ParentContext);
 
   // __null
   ExprResult ActOnGNUNullExpr(SourceLocation TokenLoc);
 
   bool CheckCaseExpression(Expr *E);
 
   /// Describes the result of an "if-exists" condition check.
   enum IfExistsResult {
     /// The symbol exists.
     IER_Exists,
 
     /// The symbol does not exist.
     IER_DoesNotExist,
 
     /// The name is a dependent name, so the results will differ
     /// from one instantiation to the next.
     IER_Dependent,
 
     /// An error occurred.
     IER_Error
   };
 
   IfExistsResult
   CheckMicrosoftIfExistsSymbol(Scope *S, CXXScopeSpec &SS,
                                const DeclarationNameInfo &TargetNameInfo);
 
   IfExistsResult
   CheckMicrosoftIfExistsSymbol(Scope *S, SourceLocation KeywordLoc,
                                bool IsIfExists, CXXScopeSpec &SS,
                                UnqualifiedId &Name);
 
   StmtResult BuildMSDependentExistsStmt(SourceLocation KeywordLoc,
                                         bool IsIfExists,
                                         NestedNameSpecifierLoc QualifierLoc,
                                         DeclarationNameInfo NameInfo,
                                         Stmt *Nested);
   StmtResult ActOnMSDependentExistsStmt(SourceLocation KeywordLoc,
                                         bool IsIfExists,
                                         CXXScopeSpec &SS, UnqualifiedId &Name,
                                         Stmt *Nested);
 
   //===------------------------- "Block" Extension ------------------------===//
 
   /// ActOnBlockStart - This callback is invoked when a block literal is
   /// started.
   void ActOnBlockStart(SourceLocation CaretLoc, Scope *CurScope);
 
   /// ActOnBlockArguments - This callback allows processing of block arguments.
   /// If there are no arguments, this is still invoked.
   void ActOnBlockArguments(SourceLocation CaretLoc, Declarator &ParamInfo,
                            Scope *CurScope);
 
   /// ActOnBlockError - If there is an error parsing a block, this callback
   /// is invoked to pop the information about the block from the action impl.
   void ActOnBlockError(SourceLocation CaretLoc, Scope *CurScope);
 
   /// ActOnBlockStmtExpr - This is called when the body of a block statement
   /// literal was successfully completed.  ^(int x){...}
   ExprResult ActOnBlockStmtExpr(SourceLocation CaretLoc, Stmt *Body,
                                 Scope *CurScope);
 
   //===---------------------------- Clang Extensions ----------------------===//
 
   /// __builtin_convertvector(...)
   ExprResult ActOnConvertVectorExpr(Expr *E, ParsedType ParsedDestTy,
                                     SourceLocation BuiltinLoc,
                                     SourceLocation RParenLoc);
 
   //===---------------------------- OpenCL Features -----------------------===//
 
   /// __builtin_astype(...)
   ExprResult ActOnAsTypeExpr(Expr *E, ParsedType ParsedDestTy,
                              SourceLocation BuiltinLoc,
                              SourceLocation RParenLoc);
   ExprResult BuildAsTypeExpr(Expr *E, QualType DestTy,
                              SourceLocation BuiltinLoc,
                              SourceLocation RParenLoc);
 
   //===---------------------------- HLSL Features -------------------------===//
   Decl *ActOnStartHLSLBuffer(Scope *BufferScope, bool CBuffer,
                              SourceLocation KwLoc, IdentifierInfo *Ident,
                              SourceLocation IdentLoc, SourceLocation LBrace);
   void ActOnFinishHLSLBuffer(Decl *Dcl, SourceLocation RBrace);
 
   //===---------------------------- C++ Features --------------------------===//
 
   // Act on C++ namespaces
   Decl *ActOnStartNamespaceDef(Scope *S, SourceLocation InlineLoc,
                                SourceLocation NamespaceLoc,
                                SourceLocation IdentLoc, IdentifierInfo *Ident,
                                SourceLocation LBrace,
                                const ParsedAttributesView &AttrList,
                                UsingDirectiveDecl *&UsingDecl, bool IsNested);
   void ActOnFinishNamespaceDef(Decl *Dcl, SourceLocation RBrace);
 
   NamespaceDecl *getStdNamespace() const;
   NamespaceDecl *getOrCreateStdNamespace();
 
   CXXRecordDecl *getStdBadAlloc() const;
   EnumDecl *getStdAlignValT() const;
 
 private:
   // A cache representing if we've fully checked the various comparison category
   // types stored in ASTContext. The bit-index corresponds to the integer value
   // of a ComparisonCategoryType enumerator.
   llvm::SmallBitVector FullyCheckedComparisonCategories;
 
   ValueDecl *tryLookupCtorInitMemberDecl(CXXRecordDecl *ClassDecl,
                                          CXXScopeSpec &SS,
                                          ParsedType TemplateTypeTy,
                                          IdentifierInfo *MemberOrBase);
 
 public:
   enum class ComparisonCategoryUsage {
     /// The '<=>' operator was used in an expression and a builtin operator
     /// was selected.
     OperatorInExpression,
     /// A defaulted 'operator<=>' needed the comparison category. This
     /// typically only applies to 'std::strong_ordering', due to the implicit
     /// fallback return value.
     DefaultedOperator,
   };
 
   /// Lookup the specified comparison category types in the standard
   ///   library, an check the VarDecls possibly returned by the operator<=>
   ///   builtins for that type.
   ///
   /// \return The type of the comparison category type corresponding to the
   ///   specified Kind, or a null type if an error occurs
   QualType CheckComparisonCategoryType(ComparisonCategoryType Kind,
                                        SourceLocation Loc,
                                        ComparisonCategoryUsage Usage);
 
   /// Tests whether Ty is an instance of std::initializer_list and, if
   /// it is and Element is not NULL, assigns the element type to Element.
   bool isStdInitializerList(QualType Ty, QualType *Element);
 
   /// Looks for the std::initializer_list template and instantiates it
   /// with Element, or emits an error if it's not found.
   ///
   /// \returns The instantiated template, or null on error.
   QualType BuildStdInitializerList(QualType Element, SourceLocation Loc);
 
   /// Determine whether Ctor is an initializer-list constructor, as
   /// defined in [dcl.init.list]p2.
   bool isInitListConstructor(const FunctionDecl *Ctor);
 
   Decl *ActOnUsingDirective(Scope *CurScope, SourceLocation UsingLoc,
                             SourceLocation NamespcLoc, CXXScopeSpec &SS,
                             SourceLocation IdentLoc,
                             IdentifierInfo *NamespcName,
                             const ParsedAttributesView &AttrList);
 
   void PushUsingDirective(Scope *S, UsingDirectiveDecl *UDir);
 
   Decl *ActOnNamespaceAliasDef(Scope *CurScope,
                                SourceLocation NamespaceLoc,
                                SourceLocation AliasLoc,
                                IdentifierInfo *Alias,
                                CXXScopeSpec &SS,
                                SourceLocation IdentLoc,
                                IdentifierInfo *Ident);
 
   void FilterUsingLookup(Scope *S, LookupResult &lookup);
   void HideUsingShadowDecl(Scope *S, UsingShadowDecl *Shadow);
   bool CheckUsingShadowDecl(BaseUsingDecl *BUD, NamedDecl *Target,
                             const LookupResult &PreviousDecls,
                             UsingShadowDecl *&PrevShadow);
   UsingShadowDecl *BuildUsingShadowDecl(Scope *S, BaseUsingDecl *BUD,
                                         NamedDecl *Target,
                                         UsingShadowDecl *PrevDecl);
 
   bool CheckUsingDeclRedeclaration(SourceLocation UsingLoc,
                                    bool HasTypenameKeyword,
                                    const CXXScopeSpec &SS,
                                    SourceLocation NameLoc,
                                    const LookupResult &Previous);
   bool CheckUsingDeclQualifier(SourceLocation UsingLoc, bool HasTypename,
                                const CXXScopeSpec &SS,
                                const DeclarationNameInfo &NameInfo,
                                SourceLocation NameLoc,
                                const LookupResult *R = nullptr,
                                const UsingDecl *UD = nullptr);
 
   NamedDecl *BuildUsingDeclaration(
       Scope *S, AccessSpecifier AS, SourceLocation UsingLoc,
       bool HasTypenameKeyword, SourceLocation TypenameLoc, CXXScopeSpec &SS,
       DeclarationNameInfo NameInfo, SourceLocation EllipsisLoc,
       const ParsedAttributesView &AttrList, bool IsInstantiation,
       bool IsUsingIfExists);
   NamedDecl *BuildUsingEnumDeclaration(Scope *S, AccessSpecifier AS,
                                        SourceLocation UsingLoc,
                                        SourceLocation EnumLoc,
                                        SourceLocation NameLoc,
                                        TypeSourceInfo *EnumType, EnumDecl *ED);
   NamedDecl *BuildUsingPackDecl(NamedDecl *InstantiatedFrom,
                                 ArrayRef<NamedDecl *> Expansions);
 
   bool CheckInheritingConstructorUsingDecl(UsingDecl *UD);
 
   /// Given a derived-class using shadow declaration for a constructor and the
   /// correspnding base class constructor, find or create the implicit
   /// synthesized derived class constructor to use for this initialization.
   CXXConstructorDecl *
   findInheritingConstructor(SourceLocation Loc, CXXConstructorDecl *BaseCtor,
                             ConstructorUsingShadowDecl *DerivedShadow);
 
   Decl *ActOnUsingDeclaration(Scope *CurScope, AccessSpecifier AS,
                               SourceLocation UsingLoc,
                               SourceLocation TypenameLoc, CXXScopeSpec &SS,
                               UnqualifiedId &Name, SourceLocation EllipsisLoc,
                               const ParsedAttributesView &AttrList);
   Decl *ActOnUsingEnumDeclaration(Scope *CurScope, AccessSpecifier AS,
                                   SourceLocation UsingLoc,
                                   SourceLocation EnumLoc,
                                   SourceLocation IdentLoc, IdentifierInfo &II,
                                   CXXScopeSpec *SS = nullptr);
   Decl *ActOnAliasDeclaration(Scope *CurScope, AccessSpecifier AS,
                               MultiTemplateParamsArg TemplateParams,
                               SourceLocation UsingLoc, UnqualifiedId &Name,
                               const ParsedAttributesView &AttrList,
                               TypeResult Type, Decl *DeclFromDeclSpec);
 
   /// BuildCXXConstructExpr - Creates a complete call to a constructor,
   /// including handling of its default argument expressions.
   ///
   /// \param ConstructKind - a CXXConstructExpr::ConstructionKind
   ExprResult
   BuildCXXConstructExpr(SourceLocation ConstructLoc, QualType DeclInitType,
                         NamedDecl *FoundDecl,
                         CXXConstructorDecl *Constructor, MultiExprArg Exprs,
                         bool HadMultipleCandidates, bool IsListInitialization,
                         bool IsStdInitListInitialization,
                         bool RequiresZeroInit, unsigned ConstructKind,
                         SourceRange ParenRange);
 
   /// Build a CXXConstructExpr whose constructor has already been resolved if
   /// it denotes an inherited constructor.
   ExprResult
   BuildCXXConstructExpr(SourceLocation ConstructLoc, QualType DeclInitType,
                         CXXConstructorDecl *Constructor, bool Elidable,
                         MultiExprArg Exprs,
                         bool HadMultipleCandidates, bool IsListInitialization,
                         bool IsStdInitListInitialization,
                         bool RequiresZeroInit, unsigned ConstructKind,
                         SourceRange ParenRange);
 
   // FIXME: Can we remove this and have the above BuildCXXConstructExpr check if
   // the constructor can be elidable?
   ExprResult
   BuildCXXConstructExpr(SourceLocation ConstructLoc, QualType DeclInitType,
                         NamedDecl *FoundDecl,
                         CXXConstructorDecl *Constructor, bool Elidable,
                         MultiExprArg Exprs, bool HadMultipleCandidates,
                         bool IsListInitialization,
                         bool IsStdInitListInitialization, bool RequiresZeroInit,
                         unsigned ConstructKind, SourceRange ParenRange);
 
   ExprResult ConvertMemberDefaultInitExpression(FieldDecl *FD, Expr *InitExpr,
                                                 SourceLocation InitLoc);
 
   ExprResult BuildCXXDefaultInitExpr(SourceLocation Loc, FieldDecl *Field);
 
 
   /// Instantiate or parse a C++ default argument expression as necessary.
   /// Return true on error.
   bool CheckCXXDefaultArgExpr(SourceLocation CallLoc, FunctionDecl *FD,
                               ParmVarDecl *Param, Expr *Init = nullptr,
                               bool SkipImmediateInvocations = true);
 
   /// BuildCXXDefaultArgExpr - Creates a CXXDefaultArgExpr, instantiating
   /// the default expr if needed.
   ExprResult BuildCXXDefaultArgExpr(SourceLocation CallLoc, FunctionDecl *FD,
                                     ParmVarDecl *Param, Expr *Init = nullptr);
 
   /// FinalizeVarWithDestructor - Prepare for calling destructor on the
   /// constructed variable.
   void FinalizeVarWithDestructor(VarDecl *VD, const RecordType *DeclInitType);
 
   /// Helper class that collects exception specifications for
   /// implicitly-declared special member functions.
   class ImplicitExceptionSpecification {
     // Pointer to allow copying
     Sema *Self;
     // We order exception specifications thus:
     // noexcept is the most restrictive, but is only used in C++11.
     // throw() comes next.
     // Then a throw(collected exceptions)
     // Finally no specification, which is expressed as noexcept(false).
     // throw(...) is used instead if any called function uses it.
     ExceptionSpecificationType ComputedEST;
     llvm::SmallPtrSet<CanQualType, 4> ExceptionsSeen;
     SmallVector<QualType, 4> Exceptions;
 
     void ClearExceptions() {
       ExceptionsSeen.clear();
       Exceptions.clear();
     }
 
   public:
     explicit ImplicitExceptionSpecification(Sema &Self)
       : Self(&Self), ComputedEST(EST_BasicNoexcept) {
       if (!Self.getLangOpts().CPlusPlus11)
         ComputedEST = EST_DynamicNone;
     }
 
     /// Get the computed exception specification type.
     ExceptionSpecificationType getExceptionSpecType() const {
       assert(!isComputedNoexcept(ComputedEST) &&
              "noexcept(expr) should not be a possible result");
       return ComputedEST;
     }
 
     /// The number of exceptions in the exception specification.
     unsigned size() const { return Exceptions.size(); }
 
     /// The set of exceptions in the exception specification.
     const QualType *data() const { return Exceptions.data(); }
 
     /// Integrate another called method into the collected data.
     void CalledDecl(SourceLocation CallLoc, const CXXMethodDecl *Method);
 
     /// Integrate an invoked expression into the collected data.
     void CalledExpr(Expr *E) { CalledStmt(E); }
 
     /// Integrate an invoked statement into the collected data.
     void CalledStmt(Stmt *S);
 
     /// Overwrite an EPI's exception specification with this
     /// computed exception specification.
     FunctionProtoType::ExceptionSpecInfo getExceptionSpec() const {
       FunctionProtoType::ExceptionSpecInfo ESI;
       ESI.Type = getExceptionSpecType();
       if (ESI.Type == EST_Dynamic) {
         ESI.Exceptions = Exceptions;
       } else if (ESI.Type == EST_None) {
         /// C++11 [except.spec]p14:
         ///   The exception-specification is noexcept(false) if the set of
         ///   potential exceptions of the special member function contains "any"
         ESI.Type = EST_NoexceptFalse;
         ESI.NoexceptExpr = Self->ActOnCXXBoolLiteral(SourceLocation(),
                                                      tok::kw_false).get();
       }
       return ESI;
     }
   };
 
   /// Evaluate the implicit exception specification for a defaulted
   /// special member function.
   void EvaluateImplicitExceptionSpec(SourceLocation Loc, FunctionDecl *FD);
 
   /// Check the given noexcept-specifier, convert its expression, and compute
   /// the appropriate ExceptionSpecificationType.
   ExprResult ActOnNoexceptSpec(Expr *NoexceptExpr,
                                ExceptionSpecificationType &EST);
 
   /// Check the given exception-specification and update the
   /// exception specification information with the results.
   void checkExceptionSpecification(bool IsTopLevel,
                                    ExceptionSpecificationType EST,
                                    ArrayRef<ParsedType> DynamicExceptions,
                                    ArrayRef<SourceRange> DynamicExceptionRanges,
                                    Expr *NoexceptExpr,
                                    SmallVectorImpl<QualType> &Exceptions,
                                    FunctionProtoType::ExceptionSpecInfo &ESI);
 
   /// Determine if we're in a case where we need to (incorrectly) eagerly
   /// parse an exception specification to work around a libstdc++ bug.
   bool isLibstdcxxEagerExceptionSpecHack(const Declarator &D);
 
   /// Add an exception-specification to the given member function
   /// (or member function template). The exception-specification was parsed
   /// after the method itself was declared.
   void actOnDelayedExceptionSpecification(Decl *Method,
          ExceptionSpecificationType EST,
          SourceRange SpecificationRange,
          ArrayRef<ParsedType> DynamicExceptions,
          ArrayRef<SourceRange> DynamicExceptionRanges,
          Expr *NoexceptExpr);
 
   class InheritedConstructorInfo;
 
   /// Determine if a special member function should have a deleted
   /// definition when it is defaulted.
   bool ShouldDeleteSpecialMember(CXXMethodDecl *MD, CXXSpecialMember CSM,
                                  InheritedConstructorInfo *ICI = nullptr,
                                  bool Diagnose = false);
 
   /// Produce notes explaining why a defaulted function was defined as deleted.
   void DiagnoseDeletedDefaultedFunction(FunctionDecl *FD);
 
   /// Declare the implicit default constructor for the given class.
   ///
   /// \param ClassDecl The class declaration into which the implicit
   /// default constructor will be added.
   ///
   /// \returns The implicitly-declared default constructor.
   CXXConstructorDecl *DeclareImplicitDefaultConstructor(
                                                      CXXRecordDecl *ClassDecl);
 
   /// DefineImplicitDefaultConstructor - Checks for feasibility of
   /// defining this constructor as the default constructor.
   void DefineImplicitDefaultConstructor(SourceLocation CurrentLocation,
                                         CXXConstructorDecl *Constructor);
 
   /// Declare the implicit destructor for the given class.
   ///
   /// \param ClassDecl The class declaration into which the implicit
   /// destructor will be added.
   ///
   /// \returns The implicitly-declared destructor.
   CXXDestructorDecl *DeclareImplicitDestructor(CXXRecordDecl *ClassDecl);
 
   /// DefineImplicitDestructor - Checks for feasibility of
   /// defining this destructor as the default destructor.
   void DefineImplicitDestructor(SourceLocation CurrentLocation,
                                 CXXDestructorDecl *Destructor);
 
   /// Build an exception spec for destructors that don't have one.
   ///
   /// C++11 says that user-defined destructors with no exception spec get one
   /// that looks as if the destructor was implicitly declared.
   void AdjustDestructorExceptionSpec(CXXDestructorDecl *Destructor);
 
   /// Define the specified inheriting constructor.
   void DefineInheritingConstructor(SourceLocation UseLoc,
                                    CXXConstructorDecl *Constructor);
 
   /// Declare the implicit copy constructor for the given class.
   ///
   /// \param ClassDecl The class declaration into which the implicit
   /// copy constructor will be added.
   ///
   /// \returns The implicitly-declared copy constructor.
   CXXConstructorDecl *DeclareImplicitCopyConstructor(CXXRecordDecl *ClassDecl);
 
   /// DefineImplicitCopyConstructor - Checks for feasibility of
   /// defining this constructor as the copy constructor.
   void DefineImplicitCopyConstructor(SourceLocation CurrentLocation,
                                      CXXConstructorDecl *Constructor);
 
   /// Declare the implicit move constructor for the given class.
   ///
   /// \param ClassDecl The Class declaration into which the implicit
   /// move constructor will be added.
   ///
   /// \returns The implicitly-declared move constructor, or NULL if it wasn't
   /// declared.
   CXXConstructorDecl *DeclareImplicitMoveConstructor(CXXRecordDecl *ClassDecl);
 
   /// DefineImplicitMoveConstructor - Checks for feasibility of
   /// defining this constructor as the move constructor.
   void DefineImplicitMoveConstructor(SourceLocation CurrentLocation,
                                      CXXConstructorDecl *Constructor);
 
   /// Declare the implicit copy assignment operator for the given class.
   ///
   /// \param ClassDecl The class declaration into which the implicit
   /// copy assignment operator will be added.
   ///
   /// \returns The implicitly-declared copy assignment operator.
   CXXMethodDecl *DeclareImplicitCopyAssignment(CXXRecordDecl *ClassDecl);
 
   /// Defines an implicitly-declared copy assignment operator.
   void DefineImplicitCopyAssignment(SourceLocation CurrentLocation,
                                     CXXMethodDecl *MethodDecl);
 
   /// Declare the implicit move assignment operator for the given class.
   ///
   /// \param ClassDecl The Class declaration into which the implicit
   /// move assignment operator will be added.
   ///
   /// \returns The implicitly-declared move assignment operator, or NULL if it
   /// wasn't declared.
   CXXMethodDecl *DeclareImplicitMoveAssignment(CXXRecordDecl *ClassDecl);
 
   /// Defines an implicitly-declared move assignment operator.
   void DefineImplicitMoveAssignment(SourceLocation CurrentLocation,
                                     CXXMethodDecl *MethodDecl);
 
   /// Force the declaration of any implicitly-declared members of this
   /// class.
   void ForceDeclarationOfImplicitMembers(CXXRecordDecl *Class);
 
   /// Check a completed declaration of an implicit special member.
   void CheckImplicitSpecialMemberDeclaration(Scope *S, FunctionDecl *FD);
 
   /// Determine whether the given function is an implicitly-deleted
   /// special member function.
   bool isImplicitlyDeleted(FunctionDecl *FD);
 
   /// Check whether 'this' shows up in the type of a static member
   /// function after the (naturally empty) cv-qualifier-seq would be.
   ///
   /// \returns true if an error occurred.
   bool checkThisInStaticMemberFunctionType(CXXMethodDecl *Method);
 
   /// Whether this' shows up in the exception specification of a static
   /// member function.
   bool checkThisInStaticMemberFunctionExceptionSpec(CXXMethodDecl *Method);
 
   /// Check whether 'this' shows up in the attributes of the given
   /// static member function.
   ///
   /// \returns true if an error occurred.
   bool checkThisInStaticMemberFunctionAttributes(CXXMethodDecl *Method);
 
   /// MaybeBindToTemporary - If the passed in expression has a record type with
   /// a non-trivial destructor, this will return CXXBindTemporaryExpr. Otherwise
   /// it simply returns the passed in expression.
   ExprResult MaybeBindToTemporary(Expr *E);
 
   /// Wrap the expression in a ConstantExpr if it is a potential immediate
   /// invocation.
   ExprResult CheckForImmediateInvocation(ExprResult E, FunctionDecl *Decl);
 
   bool CheckImmediateEscalatingFunctionDefinition(
       FunctionDecl *FD, const sema::FunctionScopeInfo *FSI);
 
   void MarkExpressionAsImmediateEscalating(Expr *E);
 
   void DiagnoseImmediateEscalatingReason(FunctionDecl *FD);
 
   bool CompleteConstructorCall(CXXConstructorDecl *Constructor,
                                QualType DeclInitType, MultiExprArg ArgsPtr,
                                SourceLocation Loc,
                                SmallVectorImpl<Expr *> &ConvertedArgs,
                                bool AllowExplicit = false,
                                bool IsListInitialization = false);
 
   ParsedType getInheritingConstructorName(CXXScopeSpec &SS,
                                           SourceLocation NameLoc,
                                           IdentifierInfo &Name);
 
   ParsedType getConstructorName(IdentifierInfo &II, SourceLocation NameLoc,
                                 Scope *S, CXXScopeSpec &SS,
                                 bool EnteringContext);
   ParsedType getDestructorName(SourceLocation TildeLoc,
                                IdentifierInfo &II, SourceLocation NameLoc,
                                Scope *S, CXXScopeSpec &SS,
                                ParsedType ObjectType,
                                bool EnteringContext);
 
   ParsedType getDestructorTypeForDecltype(const DeclSpec &DS,
                                           ParsedType ObjectType);
 
   // Checks that reinterpret casts don't have undefined behavior.
   void CheckCompatibleReinterpretCast(QualType SrcType, QualType DestType,
                                       bool IsDereference, SourceRange Range);
 
   // Checks that the vector type should be initialized from a scalar
   // by splatting the value rather than populating a single element.
   // This is the case for AltiVecVector types as well as with
   // AltiVecPixel and AltiVecBool when -faltivec-src-compat=xl is specified.
   bool ShouldSplatAltivecScalarInCast(const VectorType *VecTy);
 
   // Checks if the -faltivec-src-compat=gcc option is specified.
   // If so, AltiVecVector, AltiVecBool and AltiVecPixel types are
   // treated the same way as they are when trying to initialize
   // these vectors on gcc (an error is emitted).
   bool CheckAltivecInitFromScalar(SourceRange R, QualType VecTy,
                                   QualType SrcTy);
 
   /// ActOnCXXNamedCast - Parse
   /// {dynamic,static,reinterpret,const,addrspace}_cast's.
   ExprResult ActOnCXXNamedCast(SourceLocation OpLoc,
                                tok::TokenKind Kind,
                                SourceLocation LAngleBracketLoc,
                                Declarator &D,
                                SourceLocation RAngleBracketLoc,
                                SourceLocation LParenLoc,
                                Expr *E,
                                SourceLocation RParenLoc);
 
   ExprResult BuildCXXNamedCast(SourceLocation OpLoc,
                                tok::TokenKind Kind,
                                TypeSourceInfo *Ty,
                                Expr *E,
                                SourceRange AngleBrackets,
                                SourceRange Parens);
 
   ExprResult ActOnBuiltinBitCastExpr(SourceLocation KWLoc, Declarator &Dcl,
                                      ExprResult Operand,
                                      SourceLocation RParenLoc);
 
   ExprResult BuildBuiltinBitCastExpr(SourceLocation KWLoc, TypeSourceInfo *TSI,
                                      Expr *Operand, SourceLocation RParenLoc);
 
   ExprResult BuildCXXTypeId(QualType TypeInfoType,
                             SourceLocation TypeidLoc,
                             TypeSourceInfo *Operand,
                             SourceLocation RParenLoc);
   ExprResult BuildCXXTypeId(QualType TypeInfoType,
                             SourceLocation TypeidLoc,
                             Expr *Operand,
                             SourceLocation RParenLoc);
 
   /// ActOnCXXTypeid - Parse typeid( something ).
   ExprResult ActOnCXXTypeid(SourceLocation OpLoc,
                             SourceLocation LParenLoc, bool isType,
                             void *TyOrExpr,
                             SourceLocation RParenLoc);
 
   ExprResult BuildCXXUuidof(QualType TypeInfoType,
                             SourceLocation TypeidLoc,
                             TypeSourceInfo *Operand,
                             SourceLocation RParenLoc);
   ExprResult BuildCXXUuidof(QualType TypeInfoType,
                             SourceLocation TypeidLoc,
                             Expr *Operand,
                             SourceLocation RParenLoc);
 
   /// ActOnCXXUuidof - Parse __uuidof( something ).
   ExprResult ActOnCXXUuidof(SourceLocation OpLoc,
                             SourceLocation LParenLoc, bool isType,
                             void *TyOrExpr,
                             SourceLocation RParenLoc);
 
   /// Handle a C++1z fold-expression: ( expr op ... op expr ).
   ExprResult ActOnCXXFoldExpr(Scope *S, SourceLocation LParenLoc, Expr *LHS,
                               tok::TokenKind Operator,
                               SourceLocation EllipsisLoc, Expr *RHS,
                               SourceLocation RParenLoc);
   ExprResult BuildCXXFoldExpr(UnresolvedLookupExpr *Callee,
                               SourceLocation LParenLoc, Expr *LHS,
                               BinaryOperatorKind Operator,
                               SourceLocation EllipsisLoc, Expr *RHS,
                               SourceLocation RParenLoc,
                               std::optional<unsigned> NumExpansions);
   ExprResult BuildEmptyCXXFoldExpr(SourceLocation EllipsisLoc,
                                    BinaryOperatorKind Operator);
 
   //// ActOnCXXThis -  Parse 'this' pointer.
   ExprResult ActOnCXXThis(SourceLocation loc);
 
   /// Build a CXXThisExpr and mark it referenced in the current context.
   Expr *BuildCXXThisExpr(SourceLocation Loc, QualType Type, bool IsImplicit);
   void MarkThisReferenced(CXXThisExpr *This);
 
   /// Try to retrieve the type of the 'this' pointer.
   ///
   /// \returns The type of 'this', if possible. Otherwise, returns a NULL type.
   QualType getCurrentThisType();
 
   /// When non-NULL, the C++ 'this' expression is allowed despite the
   /// current context not being a non-static member function. In such cases,
   /// this provides the type used for 'this'.
   QualType CXXThisTypeOverride;
 
   /// RAII object used to temporarily allow the C++ 'this' expression
   /// to be used, with the given qualifiers on the current class type.
   class CXXThisScopeRAII {
     Sema &S;
     QualType OldCXXThisTypeOverride;
     bool Enabled;
 
   public:
     /// Introduce a new scope where 'this' may be allowed (when enabled),
     /// using the given declaration (which is either a class template or a
     /// class) along with the given qualifiers.
     /// along with the qualifiers placed on '*this'.
     CXXThisScopeRAII(Sema &S, Decl *ContextDecl, Qualifiers CXXThisTypeQuals,
                      bool Enabled = true);
 
     ~CXXThisScopeRAII();
   };
 
   /// Make sure the value of 'this' is actually available in the current
   /// context, if it is a potentially evaluated context.
   ///
   /// \param Loc The location at which the capture of 'this' occurs.
   ///
   /// \param Explicit Whether 'this' is explicitly captured in a lambda
   /// capture list.
   ///
   /// \param FunctionScopeIndexToStopAt If non-null, it points to the index
   /// of the FunctionScopeInfo stack beyond which we do not attempt to capture.
   /// This is useful when enclosing lambdas must speculatively capture
   /// 'this' that may or may not be used in certain specializations of
   /// a nested generic lambda (depending on whether the name resolves to
   /// a non-static member function or a static function).
   /// \return returns 'true' if failed, 'false' if success.
   bool CheckCXXThisCapture(SourceLocation Loc, bool Explicit = false,
       bool BuildAndDiagnose = true,
       const unsigned *const FunctionScopeIndexToStopAt = nullptr,
       bool ByCopy = false);
 
   /// Determine whether the given type is the type of *this that is used
   /// outside of the body of a member function for a type that is currently
   /// being defined.
   bool isThisOutsideMemberFunctionBody(QualType BaseType);
 
   /// ActOnCXXBoolLiteral - Parse {true,false} literals.
   ExprResult ActOnCXXBoolLiteral(SourceLocation OpLoc, tok::TokenKind Kind);
 
 
   /// ActOnObjCBoolLiteral - Parse {__objc_yes,__objc_no} literals.
   ExprResult ActOnObjCBoolLiteral(SourceLocation OpLoc, tok::TokenKind Kind);
 
   ExprResult
   ActOnObjCAvailabilityCheckExpr(llvm::ArrayRef<AvailabilitySpec> AvailSpecs,
                                  SourceLocation AtLoc, SourceLocation RParen);
 
   /// ActOnCXXNullPtrLiteral - Parse 'nullptr'.
   ExprResult ActOnCXXNullPtrLiteral(SourceLocation Loc);
 
   //// ActOnCXXThrow -  Parse throw expressions.
   ExprResult ActOnCXXThrow(Scope *S, SourceLocation OpLoc, Expr *expr);
   ExprResult BuildCXXThrow(SourceLocation OpLoc, Expr *Ex,
                            bool IsThrownVarInScope);
   bool CheckCXXThrowOperand(SourceLocation ThrowLoc, QualType ThrowTy, Expr *E);
 
   /// ActOnCXXTypeConstructExpr - Parse construction of a specified type.
   /// Can be interpreted either as function-style casting ("int(x)")
   /// or class type construction ("ClassType(x,y,z)")
   /// or creation of a value-initialized type ("int()").
   ExprResult ActOnCXXTypeConstructExpr(ParsedType TypeRep,
                                        SourceLocation LParenOrBraceLoc,
                                        MultiExprArg Exprs,
                                        SourceLocation RParenOrBraceLoc,
                                        bool ListInitialization);
 
   ExprResult BuildCXXTypeConstructExpr(TypeSourceInfo *Type,
                                        SourceLocation LParenLoc,
                                        MultiExprArg Exprs,
                                        SourceLocation RParenLoc,
                                        bool ListInitialization);
 
   /// ActOnCXXNew - Parsed a C++ 'new' expression.
   ExprResult ActOnCXXNew(SourceLocation StartLoc, bool UseGlobal,
                          SourceLocation PlacementLParen,
                          MultiExprArg PlacementArgs,
                          SourceLocation PlacementRParen,
                          SourceRange TypeIdParens, Declarator &D,
                          Expr *Initializer);
   ExprResult
   BuildCXXNew(SourceRange Range, bool UseGlobal, SourceLocation PlacementLParen,
               MultiExprArg PlacementArgs, SourceLocation PlacementRParen,
               SourceRange TypeIdParens, QualType AllocType,
               TypeSourceInfo *AllocTypeInfo, std::optional<Expr *> ArraySize,
               SourceRange DirectInitRange, Expr *Initializer);
 
   /// Determine whether \p FD is an aligned allocation or deallocation
   /// function that is unavailable.
   bool isUnavailableAlignedAllocationFunction(const FunctionDecl &FD) const;
 
   /// Produce diagnostics if \p FD is an aligned allocation or deallocation
   /// function that is unavailable.
   void diagnoseUnavailableAlignedAllocation(const FunctionDecl &FD,
                                             SourceLocation Loc);
 
   bool CheckAllocatedType(QualType AllocType, SourceLocation Loc,
                           SourceRange R);
 
   /// The scope in which to find allocation functions.
   enum AllocationFunctionScope {
     /// Only look for allocation functions in the global scope.
     AFS_Global,
     /// Only look for allocation functions in the scope of the
     /// allocated class.
     AFS_Class,
     /// Look for allocation functions in both the global scope
     /// and in the scope of the allocated class.
     AFS_Both
   };
 
   /// Finds the overloads of operator new and delete that are appropriate
   /// for the allocation.
   bool FindAllocationFunctions(SourceLocation StartLoc, SourceRange Range,
                                AllocationFunctionScope NewScope,
                                AllocationFunctionScope DeleteScope,
                                QualType AllocType, bool IsArray,
                                bool &PassAlignment, MultiExprArg PlaceArgs,
                                FunctionDecl *&OperatorNew,
                                FunctionDecl *&OperatorDelete,
                                bool Diagnose = true);
   void DeclareGlobalNewDelete();
   void DeclareGlobalAllocationFunction(DeclarationName Name, QualType Return,
                                        ArrayRef<QualType> Params);
 
   bool FindDeallocationFunction(SourceLocation StartLoc, CXXRecordDecl *RD,
                                 DeclarationName Name, FunctionDecl *&Operator,
                                 bool Diagnose = true, bool WantSize = false,
                                 bool WantAligned = false);
   FunctionDecl *FindUsualDeallocationFunction(SourceLocation StartLoc,
                                               bool CanProvideSize,
                                               bool Overaligned,
                                               DeclarationName Name);
   FunctionDecl *FindDeallocationFunctionForDestructor(SourceLocation StartLoc,
                                                       CXXRecordDecl *RD);
 
   /// ActOnCXXDelete - Parsed a C++ 'delete' expression
   ExprResult ActOnCXXDelete(SourceLocation StartLoc,
                             bool UseGlobal, bool ArrayForm,
                             Expr *Operand);
   void CheckVirtualDtorCall(CXXDestructorDecl *dtor, SourceLocation Loc,
                             bool IsDelete, bool CallCanBeVirtual,
                             bool WarnOnNonAbstractTypes,
                             SourceLocation DtorLoc);
 
   ExprResult ActOnNoexceptExpr(SourceLocation KeyLoc, SourceLocation LParen,
                                Expr *Operand, SourceLocation RParen);
   ExprResult BuildCXXNoexceptExpr(SourceLocation KeyLoc, Expr *Operand,
                                   SourceLocation RParen);
 
   /// Parsed one of the type trait support pseudo-functions.
   ExprResult ActOnTypeTrait(TypeTrait Kind, SourceLocation KWLoc,
                             ArrayRef<ParsedType> Args,
                             SourceLocation RParenLoc);
   ExprResult BuildTypeTrait(TypeTrait Kind, SourceLocation KWLoc,
                             ArrayRef<TypeSourceInfo *> Args,
                             SourceLocation RParenLoc);
 
   /// ActOnArrayTypeTrait - Parsed one of the binary type trait support
   /// pseudo-functions.
   ExprResult ActOnArrayTypeTrait(ArrayTypeTrait ATT,
                                  SourceLocation KWLoc,
                                  ParsedType LhsTy,
                                  Expr *DimExpr,
                                  SourceLocation RParen);
 
   ExprResult BuildArrayTypeTrait(ArrayTypeTrait ATT,
                                  SourceLocation KWLoc,
                                  TypeSourceInfo *TSInfo,
                                  Expr *DimExpr,
                                  SourceLocation RParen);
 
   /// ActOnExpressionTrait - Parsed one of the unary type trait support
   /// pseudo-functions.
   ExprResult ActOnExpressionTrait(ExpressionTrait OET,
                                   SourceLocation KWLoc,
                                   Expr *Queried,
                                   SourceLocation RParen);
 
   ExprResult BuildExpressionTrait(ExpressionTrait OET,
                                   SourceLocation KWLoc,
                                   Expr *Queried,
                                   SourceLocation RParen);
 
   ExprResult ActOnStartCXXMemberReference(Scope *S,
                                           Expr *Base,
                                           SourceLocation OpLoc,
                                           tok::TokenKind OpKind,
                                           ParsedType &ObjectType,
                                           bool &MayBePseudoDestructor);
 
   ExprResult BuildPseudoDestructorExpr(Expr *Base,
                                        SourceLocation OpLoc,
                                        tok::TokenKind OpKind,
                                        const CXXScopeSpec &SS,
                                        TypeSourceInfo *ScopeType,
                                        SourceLocation CCLoc,
                                        SourceLocation TildeLoc,
                                      PseudoDestructorTypeStorage DestroyedType);
 
   ExprResult ActOnPseudoDestructorExpr(Scope *S, Expr *Base,
                                        SourceLocation OpLoc,
                                        tok::TokenKind OpKind,
                                        CXXScopeSpec &SS,
                                        UnqualifiedId &FirstTypeName,
                                        SourceLocation CCLoc,
                                        SourceLocation TildeLoc,
                                        UnqualifiedId &SecondTypeName);
 
   ExprResult ActOnPseudoDestructorExpr(Scope *S, Expr *Base,
                                        SourceLocation OpLoc,
                                        tok::TokenKind OpKind,
                                        SourceLocation TildeLoc,
                                        const DeclSpec& DS);
 
   /// MaybeCreateExprWithCleanups - If the current full-expression
   /// requires any cleanups, surround it with a ExprWithCleanups node.
   /// Otherwise, just returns the passed-in expression.
   Expr *MaybeCreateExprWithCleanups(Expr *SubExpr);
   Stmt *MaybeCreateStmtWithCleanups(Stmt *SubStmt);
   ExprResult MaybeCreateExprWithCleanups(ExprResult SubExpr);
 
   MaterializeTemporaryExpr *
   CreateMaterializeTemporaryExpr(QualType T, Expr *Temporary,
                                  bool BoundToLvalueReference);
 
   ExprResult ActOnFinishFullExpr(Expr *Expr, bool DiscardedValue) {
     return ActOnFinishFullExpr(
         Expr, Expr ? Expr->getExprLoc() : SourceLocation(), DiscardedValue);
   }
   ExprResult ActOnFinishFullExpr(Expr *Expr, SourceLocation CC,
                                  bool DiscardedValue, bool IsConstexpr = false,
                                  bool IsTemplateArgument = false);
   StmtResult ActOnFinishFullStmt(Stmt *Stmt);
 
   // Marks SS invalid if it represents an incomplete type.
   bool RequireCompleteDeclContext(CXXScopeSpec &SS, DeclContext *DC);
   // Complete an enum decl, maybe without a scope spec.
   bool RequireCompleteEnumDecl(EnumDecl *D, SourceLocation L,
                                CXXScopeSpec *SS = nullptr);
 
   DeclContext *computeDeclContext(QualType T);
   DeclContext *computeDeclContext(const CXXScopeSpec &SS,
                                   bool EnteringContext = false);
   bool isDependentScopeSpecifier(const CXXScopeSpec &SS);
   CXXRecordDecl *getCurrentInstantiationOf(NestedNameSpecifier *NNS);
 
   /// The parser has parsed a global nested-name-specifier '::'.
   ///
   /// \param CCLoc The location of the '::'.
   ///
   /// \param SS The nested-name-specifier, which will be updated in-place
   /// to reflect the parsed nested-name-specifier.
   ///
   /// \returns true if an error occurred, false otherwise.
   bool ActOnCXXGlobalScopeSpecifier(SourceLocation CCLoc, CXXScopeSpec &SS);
 
   /// The parser has parsed a '__super' nested-name-specifier.
   ///
   /// \param SuperLoc The location of the '__super' keyword.
   ///
   /// \param ColonColonLoc The location of the '::'.
   ///
   /// \param SS The nested-name-specifier, which will be updated in-place
   /// to reflect the parsed nested-name-specifier.
   ///
   /// \returns true if an error occurred, false otherwise.
   bool ActOnSuperScopeSpecifier(SourceLocation SuperLoc,
                                 SourceLocation ColonColonLoc, CXXScopeSpec &SS);
 
   bool isAcceptableNestedNameSpecifier(const NamedDecl *SD,
                                        bool *CanCorrect = nullptr);
   NamedDecl *FindFirstQualifierInScope(Scope *S, NestedNameSpecifier *NNS);
 
   /// Keeps information about an identifier in a nested-name-spec.
   ///
   struct NestedNameSpecInfo {
     /// The type of the object, if we're parsing nested-name-specifier in
     /// a member access expression.
     ParsedType ObjectType;
 
     /// The identifier preceding the '::'.
     IdentifierInfo *Identifier;
 
     /// The location of the identifier.
     SourceLocation IdentifierLoc;
 
     /// The location of the '::'.
     SourceLocation CCLoc;
 
     /// Creates info object for the most typical case.
     NestedNameSpecInfo(IdentifierInfo *II, SourceLocation IdLoc,
              SourceLocation ColonColonLoc, ParsedType ObjectType = ParsedType())
       : ObjectType(ObjectType), Identifier(II), IdentifierLoc(IdLoc),
         CCLoc(ColonColonLoc) {
     }
 
     NestedNameSpecInfo(IdentifierInfo *II, SourceLocation IdLoc,
                        SourceLocation ColonColonLoc, QualType ObjectType)
       : ObjectType(ParsedType::make(ObjectType)), Identifier(II),
         IdentifierLoc(IdLoc), CCLoc(ColonColonLoc) {
     }
   };
 
   bool BuildCXXNestedNameSpecifier(Scope *S,
                                    NestedNameSpecInfo &IdInfo,
                                    bool EnteringContext,
                                    CXXScopeSpec &SS,
                                    NamedDecl *ScopeLookupResult,
                                    bool ErrorRecoveryLookup,
                                    bool *IsCorrectedToColon = nullptr,
                                    bool OnlyNamespace = false);
 
   /// The parser has parsed a nested-name-specifier 'identifier::'.
   ///
   /// \param S The scope in which this nested-name-specifier occurs.
   ///
   /// \param IdInfo Parser information about an identifier in the
   /// nested-name-spec.
   ///
   /// \param EnteringContext Whether we're entering the context nominated by
   /// this nested-name-specifier.
   ///
   /// \param SS The nested-name-specifier, which is both an input
   /// parameter (the nested-name-specifier before this type) and an
   /// output parameter (containing the full nested-name-specifier,
   /// including this new type).
   ///
   /// \param IsCorrectedToColon If not null, suggestions to replace '::' -> ':'
   /// are allowed.  The bool value pointed by this parameter is set to 'true'
   /// if the identifier is treated as if it was followed by ':', not '::'.
   ///
   /// \param OnlyNamespace If true, only considers namespaces in lookup.
   ///
   /// \returns true if an error occurred, false otherwise.
   bool ActOnCXXNestedNameSpecifier(Scope *S,
                                    NestedNameSpecInfo &IdInfo,
                                    bool EnteringContext,
                                    CXXScopeSpec &SS,
                                    bool *IsCorrectedToColon = nullptr,
                                    bool OnlyNamespace = false);
 
   ExprResult ActOnDecltypeExpression(Expr *E);
 
   bool ActOnCXXNestedNameSpecifierDecltype(CXXScopeSpec &SS,
                                            const DeclSpec &DS,
                                            SourceLocation ColonColonLoc);
 
   bool IsInvalidUnlessNestedName(Scope *S, CXXScopeSpec &SS,
                                  NestedNameSpecInfo &IdInfo,
                                  bool EnteringContext);
 
   /// The parser has parsed a nested-name-specifier
   /// 'template[opt] template-name < template-args >::'.
   ///
   /// \param S The scope in which this nested-name-specifier occurs.
   ///
   /// \param SS The nested-name-specifier, which is both an input
   /// parameter (the nested-name-specifier before this type) and an
   /// output parameter (containing the full nested-name-specifier,
   /// including this new type).
   ///
   /// \param TemplateKWLoc the location of the 'template' keyword, if any.
   /// \param TemplateName the template name.
   /// \param TemplateNameLoc The location of the template name.
   /// \param LAngleLoc The location of the opening angle bracket  ('<').
   /// \param TemplateArgs The template arguments.
   /// \param RAngleLoc The location of the closing angle bracket  ('>').
   /// \param CCLoc The location of the '::'.
   ///
   /// \param EnteringContext Whether we're entering the context of the
   /// nested-name-specifier.
   ///
   ///
   /// \returns true if an error occurred, false otherwise.
   bool ActOnCXXNestedNameSpecifier(Scope *S,
                                    CXXScopeSpec &SS,
                                    SourceLocation TemplateKWLoc,
                                    TemplateTy TemplateName,
                                    SourceLocation TemplateNameLoc,
                                    SourceLocation LAngleLoc,
                                    ASTTemplateArgsPtr TemplateArgs,
                                    SourceLocation RAngleLoc,
                                    SourceLocation CCLoc,
                                    bool EnteringContext);
 
   /// Given a C++ nested-name-specifier, produce an annotation value
   /// that the parser can use later to reconstruct the given
   /// nested-name-specifier.
   ///
   /// \param SS A nested-name-specifier.
   ///
   /// \returns A pointer containing all of the information in the
   /// nested-name-specifier \p SS.
   void *SaveNestedNameSpecifierAnnotation(CXXScopeSpec &SS);
 
   /// Given an annotation pointer for a nested-name-specifier, restore
   /// the nested-name-specifier structure.
   ///
   /// \param Annotation The annotation pointer, produced by
   /// \c SaveNestedNameSpecifierAnnotation().
   ///
   /// \param AnnotationRange The source range corresponding to the annotation.
   ///
   /// \param SS The nested-name-specifier that will be updated with the contents
   /// of the annotation pointer.
   void RestoreNestedNameSpecifierAnnotation(void *Annotation,
                                             SourceRange AnnotationRange,
                                             CXXScopeSpec &SS);
 
   bool ShouldEnterDeclaratorScope(Scope *S, const CXXScopeSpec &SS);
 
   /// ActOnCXXEnterDeclaratorScope - Called when a C++ scope specifier (global
   /// scope or nested-name-specifier) is parsed, part of a declarator-id.
   /// After this method is called, according to [C++ 3.4.3p3], names should be
   /// looked up in the declarator-id's scope, until the declarator is parsed and
   /// ActOnCXXExitDeclaratorScope is called.
   /// The 'SS' should be a non-empty valid CXXScopeSpec.
   bool ActOnCXXEnterDeclaratorScope(Scope *S, CXXScopeSpec &SS);
 
   /// ActOnCXXExitDeclaratorScope - Called when a declarator that previously
   /// invoked ActOnCXXEnterDeclaratorScope(), is finished. 'SS' is the same
   /// CXXScopeSpec that was passed to ActOnCXXEnterDeclaratorScope as well.
   /// Used to indicate that names should revert to being looked up in the
   /// defining scope.
   void ActOnCXXExitDeclaratorScope(Scope *S, const CXXScopeSpec &SS);
 
   /// ActOnCXXEnterDeclInitializer - Invoked when we are about to parse an
   /// initializer for the declaration 'Dcl'.
   /// After this method is called, according to [C++ 3.4.1p13], if 'Dcl' is a
   /// static data member of class X, names should be looked up in the scope of
   /// class X.
   void ActOnCXXEnterDeclInitializer(Scope *S, Decl *Dcl);
 
   /// ActOnCXXExitDeclInitializer - Invoked after we are finished parsing an
   /// initializer for the declaration 'Dcl'.
   void ActOnCXXExitDeclInitializer(Scope *S, Decl *Dcl);
 
   /// Create a new lambda closure type.
   CXXRecordDecl *createLambdaClosureType(SourceRange IntroducerRange,
                                          TypeSourceInfo *Info,
                                          unsigned LambdaDependencyKind,
                                          LambdaCaptureDefault CaptureDefault);
 
   /// Number lambda for linkage purposes if necessary.
   void handleLambdaNumbering(CXXRecordDecl *Class, CXXMethodDecl *Method,
                              std::optional<CXXRecordDecl::LambdaNumbering>
                                  NumberingOverride = std::nullopt);
 
   /// Endow the lambda scope info with the relevant properties.
   void buildLambdaScope(sema::LambdaScopeInfo *LSI, CXXMethodDecl *CallOperator,
                         SourceRange IntroducerRange,
                         LambdaCaptureDefault CaptureDefault,
                         SourceLocation CaptureDefaultLoc, bool ExplicitParams,
                         bool Mutable);
 
   CXXMethodDecl *CreateLambdaCallOperator(SourceRange IntroducerRange,
                                           CXXRecordDecl *Class);
   void CompleteLambdaCallOperator(
       CXXMethodDecl *Method, SourceLocation LambdaLoc,
       SourceLocation CallOperatorLoc, Expr *TrailingRequiresClause,
       TypeSourceInfo *MethodTyInfo, ConstexprSpecKind ConstexprKind,
       StorageClass SC, ArrayRef<ParmVarDecl *> Params,
       bool HasExplicitResultType);
 
   /// Perform initialization analysis of the init-capture and perform
   /// any implicit conversions such as an lvalue-to-rvalue conversion if
   /// not being used to initialize a reference.
   ParsedType actOnLambdaInitCaptureInitialization(
       SourceLocation Loc, bool ByRef, SourceLocation EllipsisLoc,
       IdentifierInfo *Id, LambdaCaptureInitKind InitKind, Expr *&Init) {
     return ParsedType::make(buildLambdaInitCaptureInitialization(
         Loc, ByRef, EllipsisLoc, std::nullopt, Id,
         InitKind != LambdaCaptureInitKind::CopyInit, Init));
   }
   QualType buildLambdaInitCaptureInitialization(
       SourceLocation Loc, bool ByRef, SourceLocation EllipsisLoc,
       std::optional<unsigned> NumExpansions, IdentifierInfo *Id,
       bool DirectInit, Expr *&Init);
 
   /// Create a dummy variable within the declcontext of the lambda's
   ///  call operator, for name lookup purposes for a lambda init capture.
   ///
   ///  CodeGen handles emission of lambda captures, ignoring these dummy
   ///  variables appropriately.
   VarDecl *createLambdaInitCaptureVarDecl(
       SourceLocation Loc, QualType InitCaptureType, SourceLocation EllipsisLoc,
       IdentifierInfo *Id, unsigned InitStyle, Expr *Init, DeclContext *DeclCtx);
 
   /// Add an init-capture to a lambda scope.
   void addInitCapture(sema::LambdaScopeInfo *LSI, VarDecl *Var, bool ByRef);
 
   /// Note that we have finished the explicit captures for the
   /// given lambda.
   void finishLambdaExplicitCaptures(sema::LambdaScopeInfo *LSI);
 
   /// Deduce a block or lambda's return type based on the return
   /// statements present in the body.
   void deduceClosureReturnType(sema::CapturingScopeInfo &CSI);
 
   /// Once the Lambdas capture are known, we can start to create the closure,
   /// call operator method, and keep track of the captures.
   /// We do the capture lookup here, but they are not actually captured until
   /// after we know what the qualifiers of the call operator are.
   void ActOnLambdaExpressionAfterIntroducer(LambdaIntroducer &Intro,
                                             Scope *CurContext);
 
   /// This is called after parsing the explicit template parameter list
   /// on a lambda (if it exists) in C++2a.
   void ActOnLambdaExplicitTemplateParameterList(LambdaIntroducer &Intro,
                                                 SourceLocation LAngleLoc,
                                                 ArrayRef<NamedDecl *> TParams,
                                                 SourceLocation RAngleLoc,
                                                 ExprResult RequiresClause);
 
   void ActOnLambdaClosureQualifiers(LambdaIntroducer &Intro,
                                     SourceLocation MutableLoc);
 
   void ActOnLambdaClosureParameters(
       Scope *LambdaScope,
       MutableArrayRef<DeclaratorChunk::ParamInfo> ParamInfo);
 
   /// ActOnStartOfLambdaDefinition - This is called just before we start
   /// parsing the body of a lambda; it analyzes the explicit captures and
   /// arguments, and sets up various data-structures for the body of the
   /// lambda.
   void ActOnStartOfLambdaDefinition(LambdaIntroducer &Intro,
                                     Declarator &ParamInfo, const DeclSpec &DS);
 
   /// ActOnLambdaError - If there is an error parsing a lambda, this callback
   /// is invoked to pop the information about the lambda.
   void ActOnLambdaError(SourceLocation StartLoc, Scope *CurScope,
                         bool IsInstantiation = false);
 
   /// ActOnLambdaExpr - This is called when the body of a lambda expression
   /// was successfully completed.
   ExprResult ActOnLambdaExpr(SourceLocation StartLoc, Stmt *Body,
                              Scope *CurScope);
 
   /// Does copying/destroying the captured variable have side effects?
   bool CaptureHasSideEffects(const sema::Capture &From);
 
   /// Diagnose if an explicit lambda capture is unused. Returns true if a
   /// diagnostic is emitted.
   bool DiagnoseUnusedLambdaCapture(SourceRange CaptureRange,
                                    const sema::Capture &From);
 
   /// Build a FieldDecl suitable to hold the given capture.
   FieldDecl *BuildCaptureField(RecordDecl *RD, const sema::Capture &Capture);
 
   /// Initialize the given capture with a suitable expression.
   ExprResult BuildCaptureInit(const sema::Capture &Capture,
                               SourceLocation ImplicitCaptureLoc,
                               bool IsOpenMPMapping = false);
 
   /// Complete a lambda-expression having processed and attached the
   /// lambda body.
   ExprResult BuildLambdaExpr(SourceLocation StartLoc, SourceLocation EndLoc,
                              sema::LambdaScopeInfo *LSI);
 
   /// Get the return type to use for a lambda's conversion function(s) to
   /// function pointer type, given the type of the call operator.
   QualType
   getLambdaConversionFunctionResultType(const FunctionProtoType *CallOpType,
                                         CallingConv CC);
 
   /// Define the "body" of the conversion from a lambda object to a
   /// function pointer.
   ///
   /// This routine doesn't actually define a sensible body; rather, it fills
   /// in the initialization expression needed to copy the lambda object into
   /// the block, and IR generation actually generates the real body of the
   /// block pointer conversion.
   void DefineImplicitLambdaToFunctionPointerConversion(
          SourceLocation CurrentLoc, CXXConversionDecl *Conv);
 
   /// Define the "body" of the conversion from a lambda object to a
   /// block pointer.
   ///
   /// This routine doesn't actually define a sensible body; rather, it fills
   /// in the initialization expression needed to copy the lambda object into
   /// the block, and IR generation actually generates the real body of the
   /// block pointer conversion.
   void DefineImplicitLambdaToBlockPointerConversion(SourceLocation CurrentLoc,
                                                     CXXConversionDecl *Conv);
 
   ExprResult BuildBlockForLambdaConversion(SourceLocation CurrentLocation,
                                            SourceLocation ConvLocation,
                                            CXXConversionDecl *Conv,
                                            Expr *Src);
 
+  sema::LambdaScopeInfo *RebuildLambdaScopeInfo(CXXMethodDecl *CallOperator);
+
+  class LambdaScopeForCallOperatorInstantiationRAII
+      : private FunctionScopeRAII {
+  public:
+    LambdaScopeForCallOperatorInstantiationRAII(
+        Sema &SemasRef, FunctionDecl *FD, MultiLevelTemplateArgumentList MLTAL,
+        LocalInstantiationScope &Scope);
+  };
+
   /// Check whether the given expression is a valid constraint expression.
   /// A diagnostic is emitted if it is not, false is returned, and
   /// PossibleNonPrimary will be set to true if the failure might be due to a
   /// non-primary expression being used as an atomic constraint.
   bool CheckConstraintExpression(const Expr *CE, Token NextToken = Token(),
                                  bool *PossibleNonPrimary = nullptr,
                                  bool IsTrailingRequiresClause = false);
 
 private:
   /// Caches pairs of template-like decls whose associated constraints were
   /// checked for subsumption and whether or not the first's constraints did in
   /// fact subsume the second's.
   llvm::DenseMap<std::pair<NamedDecl *, NamedDecl *>, bool> SubsumptionCache;
   /// Caches the normalized associated constraints of declarations (concepts or
   /// constrained declarations). If an error occurred while normalizing the
   /// associated constraints of the template or concept, nullptr will be cached
   /// here.
   llvm::DenseMap<NamedDecl *, NormalizedConstraint *>
       NormalizationCache;
 
   llvm::ContextualFoldingSet<ConstraintSatisfaction, const ASTContext &>
       SatisfactionCache;
 
   /// Introduce the instantiated function parameters into the local
   /// instantiation scope, and set the parameter names to those used
   /// in the template.
   bool addInstantiatedParametersToScope(
       FunctionDecl *Function, const FunctionDecl *PatternDecl,
       LocalInstantiationScope &Scope,
       const MultiLevelTemplateArgumentList &TemplateArgs);
 
   /// Introduce the instantiated captures of the lambda into the local
   /// instantiation scope.
   bool addInstantiatedCapturesToScope(
       FunctionDecl *Function, const FunctionDecl *PatternDecl,
       LocalInstantiationScope &Scope,
       const MultiLevelTemplateArgumentList &TemplateArgs);
 
   /// used by SetupConstraintCheckingTemplateArgumentsAndScope to recursively(in
   /// the case of lambdas) set up the LocalInstantiationScope of the current
   /// function.
   bool SetupConstraintScope(
       FunctionDecl *FD, std::optional<ArrayRef<TemplateArgument>> TemplateArgs,
       MultiLevelTemplateArgumentList MLTAL, LocalInstantiationScope &Scope);
 
   /// Used during constraint checking, sets up the constraint template argument
   /// lists, and calls SetupConstraintScope to set up the
   /// LocalInstantiationScope to have the proper set of ParVarDecls configured.
   std::optional<MultiLevelTemplateArgumentList>
   SetupConstraintCheckingTemplateArgumentsAndScope(
       FunctionDecl *FD, std::optional<ArrayRef<TemplateArgument>> TemplateArgs,
       LocalInstantiationScope &Scope);
 
 private:
   // The current stack of constraint satisfactions, so we can exit-early.
   using SatisfactionStackEntryTy =
       std::pair<const NamedDecl *, llvm::FoldingSetNodeID>;
   llvm::SmallVector<SatisfactionStackEntryTy, 10>
       SatisfactionStack;
 
 public:
   void PushSatisfactionStackEntry(const NamedDecl *D,
                                   const llvm::FoldingSetNodeID &ID) {
     const NamedDecl *Can = cast<NamedDecl>(D->getCanonicalDecl());
     SatisfactionStack.emplace_back(Can, ID);
   }
 
   void PopSatisfactionStackEntry() { SatisfactionStack.pop_back(); }
 
   bool SatisfactionStackContains(const NamedDecl *D,
                                  const llvm::FoldingSetNodeID &ID) const {
     const NamedDecl *Can = cast<NamedDecl>(D->getCanonicalDecl());
     return llvm::find(SatisfactionStack,
                       SatisfactionStackEntryTy{Can, ID}) !=
            SatisfactionStack.end();
   }
 
   // Resets the current SatisfactionStack for cases where we are instantiating
   // constraints as a 'side effect' of normal instantiation in a way that is not
   // indicative of recursive definition.
   class SatisfactionStackResetRAII {
     llvm::SmallVector<SatisfactionStackEntryTy, 10>
         BackupSatisfactionStack;
     Sema &SemaRef;
 
   public:
     SatisfactionStackResetRAII(Sema &S) : SemaRef(S) {
       SemaRef.SwapSatisfactionStack(BackupSatisfactionStack);
     }
 
     ~SatisfactionStackResetRAII() {
       SemaRef.SwapSatisfactionStack(BackupSatisfactionStack);
     }
   };
 
   void SwapSatisfactionStack(
       llvm::SmallVectorImpl<SatisfactionStackEntryTy> &NewSS) {
     SatisfactionStack.swap(NewSS);
   }
 
   const NormalizedConstraint *
   getNormalizedAssociatedConstraints(
       NamedDecl *ConstrainedDecl, ArrayRef<const Expr *> AssociatedConstraints);
 
   /// \brief Check whether the given declaration's associated constraints are
   /// at least as constrained than another declaration's according to the
   /// partial ordering of constraints.
   ///
   /// \param Result If no error occurred, receives the result of true if D1 is
   /// at least constrained than D2, and false otherwise.
   ///
   /// \returns true if an error occurred, false otherwise.
   bool IsAtLeastAsConstrained(NamedDecl *D1, MutableArrayRef<const Expr *> AC1,
                               NamedDecl *D2, MutableArrayRef<const Expr *> AC2,
                               bool &Result);
 
   /// If D1 was not at least as constrained as D2, but would've been if a pair
   /// of atomic constraints involved had been declared in a concept and not
   /// repeated in two separate places in code.
   /// \returns true if such a diagnostic was emitted, false otherwise.
   bool MaybeEmitAmbiguousAtomicConstraintsDiagnostic(NamedDecl *D1,
       ArrayRef<const Expr *> AC1, NamedDecl *D2, ArrayRef<const Expr *> AC2);
 
   /// \brief Check whether the given list of constraint expressions are
   /// satisfied (as if in a 'conjunction') given template arguments.
   /// \param Template the template-like entity that triggered the constraints
   /// check (either a concept or a constrained entity).
   /// \param ConstraintExprs a list of constraint expressions, treated as if
   /// they were 'AND'ed together.
   /// \param TemplateArgLists the list of template arguments to substitute into
   /// the constraint expression.
   /// \param TemplateIDRange The source range of the template id that
   /// caused the constraints check.
   /// \param Satisfaction if true is returned, will contain details of the
   /// satisfaction, with enough information to diagnose an unsatisfied
   /// expression.
   /// \returns true if an error occurred and satisfaction could not be checked,
   /// false otherwise.
   bool CheckConstraintSatisfaction(
       const NamedDecl *Template, ArrayRef<const Expr *> ConstraintExprs,
       const MultiLevelTemplateArgumentList &TemplateArgLists,
       SourceRange TemplateIDRange, ConstraintSatisfaction &Satisfaction) {
     llvm::SmallVector<Expr *, 4> Converted;
     return CheckConstraintSatisfaction(Template, ConstraintExprs, Converted,
                                        TemplateArgLists, TemplateIDRange,
                                        Satisfaction);
   }
 
   /// \brief Check whether the given list of constraint expressions are
   /// satisfied (as if in a 'conjunction') given template arguments.
   /// Additionally, takes an empty list of Expressions which is populated with
   /// the instantiated versions of the ConstraintExprs.
   /// \param Template the template-like entity that triggered the constraints
   /// check (either a concept or a constrained entity).
   /// \param ConstraintExprs a list of constraint expressions, treated as if
   /// they were 'AND'ed together.
   /// \param ConvertedConstraints a out parameter that will get populated with
   /// the instantiated version of the ConstraintExprs if we successfully checked
   /// satisfaction.
   /// \param TemplateArgList the multi-level list of template arguments to
   /// substitute into the constraint expression. This should be relative to the
   /// top-level (hence multi-level), since we need to instantiate fully at the
   /// time of checking.
   /// \param TemplateIDRange The source range of the template id that
   /// caused the constraints check.
   /// \param Satisfaction if true is returned, will contain details of the
   /// satisfaction, with enough information to diagnose an unsatisfied
   /// expression.
   /// \returns true if an error occurred and satisfaction could not be checked,
   /// false otherwise.
   bool CheckConstraintSatisfaction(
       const NamedDecl *Template, ArrayRef<const Expr *> ConstraintExprs,
       llvm::SmallVectorImpl<Expr *> &ConvertedConstraints,
       const MultiLevelTemplateArgumentList &TemplateArgList,
       SourceRange TemplateIDRange, ConstraintSatisfaction &Satisfaction);
 
   /// \brief Check whether the given non-dependent constraint expression is
   /// satisfied. Returns false and updates Satisfaction with the satisfaction
   /// verdict if successful, emits a diagnostic and returns true if an error
   /// occurred and satisfaction could not be determined.
   ///
   /// \returns true if an error occurred, false otherwise.
   bool CheckConstraintSatisfaction(const Expr *ConstraintExpr,
                                    ConstraintSatisfaction &Satisfaction);
 
   /// Check whether the given function decl's trailing requires clause is
   /// satisfied, if any. Returns false and updates Satisfaction with the
   /// satisfaction verdict if successful, emits a diagnostic and returns true if
   /// an error occurred and satisfaction could not be determined.
   ///
   /// \returns true if an error occurred, false otherwise.
   bool CheckFunctionConstraints(const FunctionDecl *FD,
                                 ConstraintSatisfaction &Satisfaction,
                                 SourceLocation UsageLoc = SourceLocation(),
                                 bool ForOverloadResolution = false);
 
   /// \brief Ensure that the given template arguments satisfy the constraints
   /// associated with the given template, emitting a diagnostic if they do not.
   ///
   /// \param Template The template to which the template arguments are being
   /// provided.
   ///
   /// \param TemplateArgs The converted, canonicalized template arguments.
   ///
   /// \param TemplateIDRange The source range of the template id that
   /// caused the constraints check.
   ///
   /// \returns true if the constrains are not satisfied or could not be checked
   /// for satisfaction, false if the constraints are satisfied.
   bool EnsureTemplateArgumentListConstraints(
       TemplateDecl *Template,
       const MultiLevelTemplateArgumentList &TemplateArgs,
       SourceRange TemplateIDRange);
 
   /// \brief Emit diagnostics explaining why a constraint expression was deemed
   /// unsatisfied.
   /// \param First whether this is the first time an unsatisfied constraint is
   /// diagnosed for this error.
   void
   DiagnoseUnsatisfiedConstraint(const ConstraintSatisfaction &Satisfaction,
                                 bool First = true);
 
   /// \brief Emit diagnostics explaining why a constraint expression was deemed
   /// unsatisfied.
   void
   DiagnoseUnsatisfiedConstraint(const ASTConstraintSatisfaction &Satisfaction,
                                 bool First = true);
 
   // ParseObjCStringLiteral - Parse Objective-C string literals.
   ExprResult ParseObjCStringLiteral(SourceLocation *AtLocs,
                                     ArrayRef<Expr *> Strings);
 
   ExprResult BuildObjCStringLiteral(SourceLocation AtLoc, StringLiteral *S);
 
   /// BuildObjCNumericLiteral - builds an ObjCBoxedExpr AST node for the
   /// numeric literal expression. Type of the expression will be "NSNumber *"
   /// or "id" if NSNumber is unavailable.
   ExprResult BuildObjCNumericLiteral(SourceLocation AtLoc, Expr *Number);
   ExprResult ActOnObjCBoolLiteral(SourceLocation AtLoc, SourceLocation ValueLoc,
                                   bool Value);
   ExprResult BuildObjCArrayLiteral(SourceRange SR, MultiExprArg Elements);
 
   /// BuildObjCBoxedExpr - builds an ObjCBoxedExpr AST node for the
   /// '@' prefixed parenthesized expression. The type of the expression will
   /// either be "NSNumber *", "NSString *" or "NSValue *" depending on the type
   /// of ValueType, which is allowed to be a built-in numeric type, "char *",
   /// "const char *" or C structure with attribute 'objc_boxable'.
   ExprResult BuildObjCBoxedExpr(SourceRange SR, Expr *ValueExpr);
 
   ExprResult BuildObjCSubscriptExpression(SourceLocation RB, Expr *BaseExpr,
                                           Expr *IndexExpr,
                                           ObjCMethodDecl *getterMethod,
                                           ObjCMethodDecl *setterMethod);
 
   ExprResult BuildObjCDictionaryLiteral(SourceRange SR,
                                MutableArrayRef<ObjCDictionaryElement> Elements);
 
   ExprResult BuildObjCEncodeExpression(SourceLocation AtLoc,
                                   TypeSourceInfo *EncodedTypeInfo,
                                   SourceLocation RParenLoc);
   ExprResult BuildCXXMemberCallExpr(Expr *Exp, NamedDecl *FoundDecl,
                                     CXXConversionDecl *Method,
                                     bool HadMultipleCandidates);
 
   ExprResult ParseObjCEncodeExpression(SourceLocation AtLoc,
                                        SourceLocation EncodeLoc,
                                        SourceLocation LParenLoc,
                                        ParsedType Ty,
                                        SourceLocation RParenLoc);
 
   /// ParseObjCSelectorExpression - Build selector expression for \@selector
   ExprResult ParseObjCSelectorExpression(Selector Sel,
                                          SourceLocation AtLoc,
                                          SourceLocation SelLoc,
                                          SourceLocation LParenLoc,
                                          SourceLocation RParenLoc,
                                          bool WarnMultipleSelectors);
 
   /// ParseObjCProtocolExpression - Build protocol expression for \@protocol
   ExprResult ParseObjCProtocolExpression(IdentifierInfo * ProtocolName,
                                          SourceLocation AtLoc,
                                          SourceLocation ProtoLoc,
                                          SourceLocation LParenLoc,
                                          SourceLocation ProtoIdLoc,
                                          SourceLocation RParenLoc);
 
   //===--------------------------------------------------------------------===//
   // C++ Declarations
   //
   Decl *ActOnStartLinkageSpecification(Scope *S,
                                        SourceLocation ExternLoc,
                                        Expr *LangStr,
                                        SourceLocation LBraceLoc);
   Decl *ActOnFinishLinkageSpecification(Scope *S,
                                         Decl *LinkageSpec,
                                         SourceLocation RBraceLoc);
 
 
   //===--------------------------------------------------------------------===//
   // C++ Classes
   //
   CXXRecordDecl *getCurrentClass(Scope *S, const CXXScopeSpec *SS);
   bool isCurrentClassName(const IdentifierInfo &II, Scope *S,
                           const CXXScopeSpec *SS = nullptr);
   bool isCurrentClassNameTypo(IdentifierInfo *&II, const CXXScopeSpec *SS);
 
   bool ActOnAccessSpecifier(AccessSpecifier Access, SourceLocation ASLoc,
                             SourceLocation ColonLoc,
                             const ParsedAttributesView &Attrs);
 
   NamedDecl *ActOnCXXMemberDeclarator(Scope *S, AccessSpecifier AS,
                                  Declarator &D,
                                  MultiTemplateParamsArg TemplateParameterLists,
                                  Expr *BitfieldWidth, const VirtSpecifiers &VS,
                                  InClassInitStyle InitStyle);
 
   void ActOnStartCXXInClassMemberInitializer();
   void ActOnFinishCXXInClassMemberInitializer(Decl *VarDecl,
                                               SourceLocation EqualLoc,
                                               Expr *Init);
 
   MemInitResult ActOnMemInitializer(Decl *ConstructorD,
                                     Scope *S,
                                     CXXScopeSpec &SS,
                                     IdentifierInfo *MemberOrBase,
                                     ParsedType TemplateTypeTy,
                                     const DeclSpec &DS,
                                     SourceLocation IdLoc,
                                     SourceLocation LParenLoc,
                                     ArrayRef<Expr *> Args,
                                     SourceLocation RParenLoc,
                                     SourceLocation EllipsisLoc);
 
   MemInitResult ActOnMemInitializer(Decl *ConstructorD,
                                     Scope *S,
                                     CXXScopeSpec &SS,
                                     IdentifierInfo *MemberOrBase,
                                     ParsedType TemplateTypeTy,
                                     const DeclSpec &DS,
                                     SourceLocation IdLoc,
                                     Expr *InitList,
                                     SourceLocation EllipsisLoc);
 
   MemInitResult BuildMemInitializer(Decl *ConstructorD,
                                     Scope *S,
                                     CXXScopeSpec &SS,
                                     IdentifierInfo *MemberOrBase,
                                     ParsedType TemplateTypeTy,
                                     const DeclSpec &DS,
                                     SourceLocation IdLoc,
                                     Expr *Init,
                                     SourceLocation EllipsisLoc);
 
   MemInitResult BuildMemberInitializer(ValueDecl *Member,
                                        Expr *Init,
                                        SourceLocation IdLoc);
 
   MemInitResult BuildBaseInitializer(QualType BaseType,
                                      TypeSourceInfo *BaseTInfo,
                                      Expr *Init,
                                      CXXRecordDecl *ClassDecl,
                                      SourceLocation EllipsisLoc);
 
   MemInitResult BuildDelegatingInitializer(TypeSourceInfo *TInfo,
                                            Expr *Init,
                                            CXXRecordDecl *ClassDecl);
 
   bool SetDelegatingInitializer(CXXConstructorDecl *Constructor,
                                 CXXCtorInitializer *Initializer);
 
   bool SetCtorInitializers(
       CXXConstructorDecl *Constructor, bool AnyErrors,
       ArrayRef<CXXCtorInitializer *> Initializers = std::nullopt);
 
   void SetIvarInitializers(ObjCImplementationDecl *ObjCImplementation);
 
 
   /// MarkBaseAndMemberDestructorsReferenced - Given a record decl,
   /// mark all the non-trivial destructors of its members and bases as
   /// referenced.
   void MarkBaseAndMemberDestructorsReferenced(SourceLocation Loc,
                                               CXXRecordDecl *Record);
 
   /// Mark destructors of virtual bases of this class referenced. In the Itanium
   /// C++ ABI, this is done when emitting a destructor for any non-abstract
   /// class. In the Microsoft C++ ABI, this is done any time a class's
   /// destructor is referenced.
   void MarkVirtualBaseDestructorsReferenced(
       SourceLocation Location, CXXRecordDecl *ClassDecl,
       llvm::SmallPtrSetImpl<const RecordType *> *DirectVirtualBases = nullptr);
 
   /// Do semantic checks to allow the complete destructor variant to be emitted
   /// when the destructor is defined in another translation unit. In the Itanium
   /// C++ ABI, destructor variants are emitted together. In the MS C++ ABI, they
   /// can be emitted in separate TUs. To emit the complete variant, run a subset
   /// of the checks performed when emitting a regular destructor.
   void CheckCompleteDestructorVariant(SourceLocation CurrentLocation,
                                       CXXDestructorDecl *Dtor);
 
   /// The list of classes whose vtables have been used within
   /// this translation unit, and the source locations at which the
   /// first use occurred.
   typedef std::pair<CXXRecordDecl*, SourceLocation> VTableUse;
 
   /// The list of vtables that are required but have not yet been
   /// materialized.
   SmallVector<VTableUse, 16> VTableUses;
 
   /// The set of classes whose vtables have been used within
   /// this translation unit, and a bit that will be true if the vtable is
   /// required to be emitted (otherwise, it should be emitted only if needed
   /// by code generation).
   llvm::DenseMap<CXXRecordDecl *, bool> VTablesUsed;
 
   /// Load any externally-stored vtable uses.
   void LoadExternalVTableUses();
 
   /// Note that the vtable for the given class was used at the
   /// given location.
   void MarkVTableUsed(SourceLocation Loc, CXXRecordDecl *Class,
                       bool DefinitionRequired = false);
 
   /// Mark the exception specifications of all virtual member functions
   /// in the given class as needed.
   void MarkVirtualMemberExceptionSpecsNeeded(SourceLocation Loc,
                                              const CXXRecordDecl *RD);
 
   /// MarkVirtualMembersReferenced - Will mark all members of the given
   /// CXXRecordDecl referenced.
   void MarkVirtualMembersReferenced(SourceLocation Loc, const CXXRecordDecl *RD,
                                     bool ConstexprOnly = false);
 
   /// Define all of the vtables that have been used in this
   /// translation unit and reference any virtual members used by those
   /// vtables.
   ///
   /// \returns true if any work was done, false otherwise.
   bool DefineUsedVTables();
 
   void AddImplicitlyDeclaredMembersToClass(CXXRecordDecl *ClassDecl);
 
   void ActOnMemInitializers(Decl *ConstructorDecl,
                             SourceLocation ColonLoc,
                             ArrayRef<CXXCtorInitializer*> MemInits,
                             bool AnyErrors);
 
   /// Check class-level dllimport/dllexport attribute. The caller must
   /// ensure that referenceDLLExportedClassMethods is called some point later
   /// when all outer classes of Class are complete.
   void checkClassLevelDLLAttribute(CXXRecordDecl *Class);
   void checkClassLevelCodeSegAttribute(CXXRecordDecl *Class);
 
   void referenceDLLExportedClassMethods();
 
   void propagateDLLAttrToBaseClassTemplate(
       CXXRecordDecl *Class, Attr *ClassAttr,
       ClassTemplateSpecializationDecl *BaseTemplateSpec,
       SourceLocation BaseLoc);
 
   /// Add gsl::Pointer attribute to std::container::iterator
   /// \param ND The declaration that introduces the name
   /// std::container::iterator. \param UnderlyingRecord The record named by ND.
   void inferGslPointerAttribute(NamedDecl *ND, CXXRecordDecl *UnderlyingRecord);
 
   /// Add [[gsl::Owner]] and [[gsl::Pointer]] attributes for std:: types.
   void inferGslOwnerPointerAttribute(CXXRecordDecl *Record);
 
   /// Add [[gsl::Pointer]] attributes for std:: types.
   void inferGslPointerAttribute(TypedefNameDecl *TD);
 
   void CheckCompletedCXXClass(Scope *S, CXXRecordDecl *Record);
 
   /// Check that the C++ class annoated with "trivial_abi" satisfies all the
   /// conditions that are needed for the attribute to have an effect.
   void checkIllFormedTrivialABIStruct(CXXRecordDecl &RD);
 
   void ActOnFinishCXXMemberSpecification(Scope *S, SourceLocation RLoc,
                                          Decl *TagDecl, SourceLocation LBrac,
                                          SourceLocation RBrac,
                                          const ParsedAttributesView &AttrList);
   void ActOnFinishCXXMemberDecls();
   void ActOnFinishCXXNonNestedClass();
 
   void ActOnReenterCXXMethodParameter(Scope *S, ParmVarDecl *Param);
   unsigned ActOnReenterTemplateScope(Decl *Template,
                                      llvm::function_ref<Scope *()> EnterScope);
   void ActOnStartDelayedMemberDeclarations(Scope *S, Decl *Record);
   void ActOnStartDelayedCXXMethodDeclaration(Scope *S, Decl *Method);
   void ActOnDelayedCXXMethodParameter(Scope *S, Decl *Param);
   void ActOnFinishDelayedMemberDeclarations(Scope *S, Decl *Record);
   void ActOnFinishDelayedCXXMethodDeclaration(Scope *S, Decl *Method);
   void ActOnFinishDelayedMemberInitializers(Decl *Record);
   void MarkAsLateParsedTemplate(FunctionDecl *FD, Decl *FnD,
                                 CachedTokens &Toks);
   void UnmarkAsLateParsedTemplate(FunctionDecl *FD);
   bool IsInsideALocalClassWithinATemplateFunction();
 
   bool EvaluateStaticAssertMessageAsString(Expr *Message, std::string &Result,
                                            ASTContext &Ctx,
                                            bool ErrorOnInvalidMessage);
   Decl *ActOnStaticAssertDeclaration(SourceLocation StaticAssertLoc,
                                      Expr *AssertExpr,
                                      Expr *AssertMessageExpr,
                                      SourceLocation RParenLoc);
   Decl *BuildStaticAssertDeclaration(SourceLocation StaticAssertLoc,
                                      Expr *AssertExpr, Expr *AssertMessageExpr,
                                      SourceLocation RParenLoc, bool Failed);
   void DiagnoseStaticAssertDetails(const Expr *E);
 
   FriendDecl *CheckFriendTypeDecl(SourceLocation LocStart,
                                   SourceLocation FriendLoc,
                                   TypeSourceInfo *TSInfo);
   Decl *ActOnFriendTypeDecl(Scope *S, const DeclSpec &DS,
                             MultiTemplateParamsArg TemplateParams);
   NamedDecl *ActOnFriendFunctionDecl(Scope *S, Declarator &D,
                                      MultiTemplateParamsArg TemplateParams);
 
   QualType CheckConstructorDeclarator(Declarator &D, QualType R,
                                       StorageClass& SC);
   void CheckConstructor(CXXConstructorDecl *Constructor);
   QualType CheckDestructorDeclarator(Declarator &D, QualType R,
                                      StorageClass& SC);
   bool CheckDestructor(CXXDestructorDecl *Destructor);
   void CheckConversionDeclarator(Declarator &D, QualType &R,
                                  StorageClass& SC);
   Decl *ActOnConversionDeclarator(CXXConversionDecl *Conversion);
   bool CheckDeductionGuideDeclarator(Declarator &D, QualType &R,
                                      StorageClass &SC);
   void CheckDeductionGuideTemplate(FunctionTemplateDecl *TD);
 
   void CheckExplicitlyDefaultedFunction(Scope *S, FunctionDecl *MD);
 
   bool CheckExplicitlyDefaultedSpecialMember(CXXMethodDecl *MD,
                                              CXXSpecialMember CSM,
                                              SourceLocation DefaultLoc);
   void CheckDelayedMemberExceptionSpecs();
 
   bool CheckExplicitlyDefaultedComparison(Scope *S, FunctionDecl *MD,
                                           DefaultedComparisonKind DCK);
   void DeclareImplicitEqualityComparison(CXXRecordDecl *RD,
                                          FunctionDecl *Spaceship);
   void DefineDefaultedComparison(SourceLocation Loc, FunctionDecl *FD,
                                  DefaultedComparisonKind DCK);
 
   //===--------------------------------------------------------------------===//
   // C++ Derived Classes
   //
 
   /// ActOnBaseSpecifier - Parsed a base specifier
   CXXBaseSpecifier *CheckBaseSpecifier(CXXRecordDecl *Class,
                                        SourceRange SpecifierRange,
                                        bool Virtual, AccessSpecifier Access,
                                        TypeSourceInfo *TInfo,
                                        SourceLocation EllipsisLoc);
 
   BaseResult ActOnBaseSpecifier(Decl *classdecl, SourceRange SpecifierRange,
                                 const ParsedAttributesView &Attrs, bool Virtual,
                                 AccessSpecifier Access, ParsedType basetype,
                                 SourceLocation BaseLoc,
                                 SourceLocation EllipsisLoc);
 
   bool AttachBaseSpecifiers(CXXRecordDecl *Class,
                             MutableArrayRef<CXXBaseSpecifier *> Bases);
   void ActOnBaseSpecifiers(Decl *ClassDecl,
                            MutableArrayRef<CXXBaseSpecifier *> Bases);
 
   bool IsDerivedFrom(SourceLocation Loc, QualType Derived, QualType Base);
   bool IsDerivedFrom(SourceLocation Loc, QualType Derived, QualType Base,
                      CXXBasePaths &Paths);
 
   // FIXME: I don't like this name.
   void BuildBasePathArray(const CXXBasePaths &Paths, CXXCastPath &BasePath);
 
   bool CheckDerivedToBaseConversion(QualType Derived, QualType Base,
                                     SourceLocation Loc, SourceRange Range,
                                     CXXCastPath *BasePath = nullptr,
                                     bool IgnoreAccess = false);
   bool CheckDerivedToBaseConversion(QualType Derived, QualType Base,
                                     unsigned InaccessibleBaseID,
                                     unsigned AmbiguousBaseConvID,
                                     SourceLocation Loc, SourceRange Range,
                                     DeclarationName Name,
                                     CXXCastPath *BasePath,
                                     bool IgnoreAccess = false);
 
   std::string getAmbiguousPathsDisplayString(CXXBasePaths &Paths);
 
   bool CheckOverridingFunctionAttributes(const CXXMethodDecl *New,
                                          const CXXMethodDecl *Old);
 
   /// CheckOverridingFunctionReturnType - Checks whether the return types are
   /// covariant, according to C++ [class.virtual]p5.
   bool CheckOverridingFunctionReturnType(const CXXMethodDecl *New,
                                          const CXXMethodDecl *Old);
 
   /// CheckOverridingFunctionExceptionSpec - Checks whether the exception
   /// spec is a subset of base spec.
   bool CheckOverridingFunctionExceptionSpec(const CXXMethodDecl *New,
                                             const CXXMethodDecl *Old);
 
   bool CheckPureMethod(CXXMethodDecl *Method, SourceRange InitRange);
 
   /// CheckOverrideControl - Check C++11 override control semantics.
   void CheckOverrideControl(NamedDecl *D);
 
   /// DiagnoseAbsenceOfOverrideControl - Diagnose if 'override' keyword was
   /// not used in the declaration of an overriding method.
   void DiagnoseAbsenceOfOverrideControl(NamedDecl *D, bool Inconsistent);
 
   /// CheckForFunctionMarkedFinal - Checks whether a virtual member function
   /// overrides a virtual member function marked 'final', according to
   /// C++11 [class.virtual]p4.
   bool CheckIfOverriddenFunctionIsMarkedFinal(const CXXMethodDecl *New,
                                               const CXXMethodDecl *Old);
 
 
   //===--------------------------------------------------------------------===//
   // C++ Access Control
   //
 
   enum AccessResult {
     AR_accessible,
     AR_inaccessible,
     AR_dependent,
     AR_delayed
   };
 
   bool SetMemberAccessSpecifier(NamedDecl *MemberDecl,
                                 NamedDecl *PrevMemberDecl,
                                 AccessSpecifier LexicalAS);
 
   AccessResult CheckUnresolvedMemberAccess(UnresolvedMemberExpr *E,
                                            DeclAccessPair FoundDecl);
   AccessResult CheckUnresolvedLookupAccess(UnresolvedLookupExpr *E,
                                            DeclAccessPair FoundDecl);
   AccessResult CheckAllocationAccess(SourceLocation OperatorLoc,
                                      SourceRange PlacementRange,
                                      CXXRecordDecl *NamingClass,
                                      DeclAccessPair FoundDecl,
                                      bool Diagnose = true);
   AccessResult CheckConstructorAccess(SourceLocation Loc,
                                       CXXConstructorDecl *D,
                                       DeclAccessPair FoundDecl,
                                       const InitializedEntity &Entity,
                                       bool IsCopyBindingRefToTemp = false);
   AccessResult CheckConstructorAccess(SourceLocation Loc,
                                       CXXConstructorDecl *D,
                                       DeclAccessPair FoundDecl,
                                       const InitializedEntity &Entity,
                                       const PartialDiagnostic &PDiag);
   AccessResult CheckDestructorAccess(SourceLocation Loc,
                                      CXXDestructorDecl *Dtor,
                                      const PartialDiagnostic &PDiag,
                                      QualType objectType = QualType());
   AccessResult CheckFriendAccess(NamedDecl *D);
   AccessResult CheckMemberAccess(SourceLocation UseLoc,
                                  CXXRecordDecl *NamingClass,
                                  DeclAccessPair Found);
   AccessResult
   CheckStructuredBindingMemberAccess(SourceLocation UseLoc,
                                      CXXRecordDecl *DecomposedClass,
                                      DeclAccessPair Field);
   AccessResult CheckMemberOperatorAccess(SourceLocation Loc, Expr *ObjectExpr,
                                          const SourceRange &,
                                          DeclAccessPair FoundDecl);
   AccessResult CheckMemberOperatorAccess(SourceLocation Loc,
                                          Expr *ObjectExpr,
                                          Expr *ArgExpr,
                                          DeclAccessPair FoundDecl);
   AccessResult CheckMemberOperatorAccess(SourceLocation Loc, Expr *ObjectExpr,
                                          ArrayRef<Expr *> ArgExprs,
                                          DeclAccessPair FoundDecl);
   AccessResult CheckAddressOfMemberAccess(Expr *OvlExpr,
                                           DeclAccessPair FoundDecl);
   AccessResult CheckBaseClassAccess(SourceLocation AccessLoc,
                                     QualType Base, QualType Derived,
                                     const CXXBasePath &Path,
                                     unsigned DiagID,
                                     bool ForceCheck = false,
                                     bool ForceUnprivileged = false);
   void CheckLookupAccess(const LookupResult &R);
   bool IsSimplyAccessible(NamedDecl *Decl, CXXRecordDecl *NamingClass,
                           QualType BaseType);
   bool isMemberAccessibleForDeletion(CXXRecordDecl *NamingClass,
                                      DeclAccessPair Found, QualType ObjectType,
                                      SourceLocation Loc,
                                      const PartialDiagnostic &Diag);
   bool isMemberAccessibleForDeletion(CXXRecordDecl *NamingClass,
                                      DeclAccessPair Found,
                                      QualType ObjectType) {
     return isMemberAccessibleForDeletion(NamingClass, Found, ObjectType,
                                          SourceLocation(), PDiag());
   }
 
   void HandleDependentAccessCheck(const DependentDiagnostic &DD,
                          const MultiLevelTemplateArgumentList &TemplateArgs);
   void PerformDependentDiagnostics(const DeclContext *Pattern,
                         const MultiLevelTemplateArgumentList &TemplateArgs);
 
   void HandleDelayedAccessCheck(sema::DelayedDiagnostic &DD, Decl *Ctx);
 
   /// When true, access checking violations are treated as SFINAE
   /// failures rather than hard errors.
   bool AccessCheckingSFINAE;
 
   enum AbstractDiagSelID {
     AbstractNone = -1,
     AbstractReturnType,
     AbstractParamType,
     AbstractVariableType,
     AbstractFieldType,
     AbstractIvarType,
     AbstractSynthesizedIvarType,
     AbstractArrayType
   };
 
   bool isAbstractType(SourceLocation Loc, QualType T);
   bool RequireNonAbstractType(SourceLocation Loc, QualType T,
                               TypeDiagnoser &Diagnoser);
   template <typename... Ts>
   bool RequireNonAbstractType(SourceLocation Loc, QualType T, unsigned DiagID,
                               const Ts &...Args) {
     BoundTypeDiagnoser<Ts...> Diagnoser(DiagID, Args...);
     return RequireNonAbstractType(Loc, T, Diagnoser);
   }
 
   void DiagnoseAbstractType(const CXXRecordDecl *RD);
 
   //===--------------------------------------------------------------------===//
   // C++ Overloaded Operators [C++ 13.5]
   //
 
   bool CheckOverloadedOperatorDeclaration(FunctionDecl *FnDecl);
 
   bool CheckLiteralOperatorDeclaration(FunctionDecl *FnDecl);
 
   //===--------------------------------------------------------------------===//
   // C++ Templates [C++ 14]
   //
   void FilterAcceptableTemplateNames(LookupResult &R,
                                      bool AllowFunctionTemplates = true,
                                      bool AllowDependent = true);
   bool hasAnyAcceptableTemplateNames(LookupResult &R,
                                      bool AllowFunctionTemplates = true,
                                      bool AllowDependent = true,
                                      bool AllowNonTemplateFunctions = false);
   /// Try to interpret the lookup result D as a template-name.
   ///
   /// \param D A declaration found by name lookup.
   /// \param AllowFunctionTemplates Whether function templates should be
   ///        considered valid results.
   /// \param AllowDependent Whether unresolved using declarations (that might
   ///        name templates) should be considered valid results.
   static NamedDecl *getAsTemplateNameDecl(NamedDecl *D,
                                           bool AllowFunctionTemplates = true,
                                           bool AllowDependent = true);
 
   enum TemplateNameIsRequiredTag { TemplateNameIsRequired };
   /// Whether and why a template name is required in this lookup.
   class RequiredTemplateKind {
   public:
     /// Template name is required if TemplateKWLoc is valid.
     RequiredTemplateKind(SourceLocation TemplateKWLoc = SourceLocation())
         : TemplateKW(TemplateKWLoc) {}
     /// Template name is unconditionally required.
     RequiredTemplateKind(TemplateNameIsRequiredTag) {}
 
     SourceLocation getTemplateKeywordLoc() const {
       return TemplateKW.value_or(SourceLocation());
     }
     bool hasTemplateKeyword() const { return getTemplateKeywordLoc().isValid(); }
     bool isRequired() const { return TemplateKW != SourceLocation(); }
     explicit operator bool() const { return isRequired(); }
 
   private:
     std::optional<SourceLocation> TemplateKW;
   };
 
   enum class AssumedTemplateKind {
     /// This is not assumed to be a template name.
     None,
     /// This is assumed to be a template name because lookup found nothing.
     FoundNothing,
     /// This is assumed to be a template name because lookup found one or more
     /// functions (but no function templates).
     FoundFunctions,
   };
   bool LookupTemplateName(
       LookupResult &R, Scope *S, CXXScopeSpec &SS, QualType ObjectType,
       bool EnteringContext, bool &MemberOfUnknownSpecialization,
       RequiredTemplateKind RequiredTemplate = SourceLocation(),
       AssumedTemplateKind *ATK = nullptr, bool AllowTypoCorrection = true);
 
   TemplateNameKind isTemplateName(Scope *S,
                                   CXXScopeSpec &SS,
                                   bool hasTemplateKeyword,
                                   const UnqualifiedId &Name,
                                   ParsedType ObjectType,
                                   bool EnteringContext,
                                   TemplateTy &Template,
                                   bool &MemberOfUnknownSpecialization,
                                   bool Disambiguation = false);
 
   /// Try to resolve an undeclared template name as a type template.
   ///
   /// Sets II to the identifier corresponding to the template name, and updates
   /// Name to a corresponding (typo-corrected) type template name and TNK to
   /// the corresponding kind, if possible.
   void ActOnUndeclaredTypeTemplateName(Scope *S, TemplateTy &Name,
                                        TemplateNameKind &TNK,
                                        SourceLocation NameLoc,
                                        IdentifierInfo *&II);
 
   bool resolveAssumedTemplateNameAsType(Scope *S, TemplateName &Name,
                                         SourceLocation NameLoc,
                                         bool Diagnose = true);
 
   /// Determine whether a particular identifier might be the name in a C++1z
   /// deduction-guide declaration.
   bool isDeductionGuideName(Scope *S, const IdentifierInfo &Name,
                             SourceLocation NameLoc, CXXScopeSpec &SS,
                             ParsedTemplateTy *Template = nullptr);
 
   bool DiagnoseUnknownTemplateName(const IdentifierInfo &II,
                                    SourceLocation IILoc,
                                    Scope *S,
                                    const CXXScopeSpec *SS,
                                    TemplateTy &SuggestedTemplate,
                                    TemplateNameKind &SuggestedKind);
 
   bool DiagnoseUninstantiableTemplate(SourceLocation PointOfInstantiation,
                                       NamedDecl *Instantiation,
                                       bool InstantiatedFromMember,
                                       const NamedDecl *Pattern,
                                       const NamedDecl *PatternDef,
                                       TemplateSpecializationKind TSK,
                                       bool Complain = true);
 
   void DiagnoseTemplateParameterShadow(SourceLocation Loc, Decl *PrevDecl);
   TemplateDecl *AdjustDeclIfTemplate(Decl *&Decl);
 
   NamedDecl *ActOnTypeParameter(Scope *S, bool Typename,
                                 SourceLocation EllipsisLoc,
                                 SourceLocation KeyLoc,
                                 IdentifierInfo *ParamName,
                                 SourceLocation ParamNameLoc,
                                 unsigned Depth, unsigned Position,
                                 SourceLocation EqualLoc,
                                 ParsedType DefaultArg, bool HasTypeConstraint);
 
   bool CheckTypeConstraint(TemplateIdAnnotation *TypeConstraint);
 
   bool ActOnTypeConstraint(const CXXScopeSpec &SS,
                            TemplateIdAnnotation *TypeConstraint,
                            TemplateTypeParmDecl *ConstrainedParameter,
                            SourceLocation EllipsisLoc);
   bool BuildTypeConstraint(const CXXScopeSpec &SS,
                            TemplateIdAnnotation *TypeConstraint,
                            TemplateTypeParmDecl *ConstrainedParameter,
                            SourceLocation EllipsisLoc,
                            bool AllowUnexpandedPack);
 
   bool AttachTypeConstraint(NestedNameSpecifierLoc NS,
                             DeclarationNameInfo NameInfo,
                             ConceptDecl *NamedConcept,
                             const TemplateArgumentListInfo *TemplateArgs,
                             TemplateTypeParmDecl *ConstrainedParameter,
                             SourceLocation EllipsisLoc);
 
   bool AttachTypeConstraint(AutoTypeLoc TL,
                             NonTypeTemplateParmDecl *NewConstrainedParm,
                             NonTypeTemplateParmDecl *OrigConstrainedParm,
                             SourceLocation EllipsisLoc);
 
   bool RequireStructuralType(QualType T, SourceLocation Loc);
 
   QualType CheckNonTypeTemplateParameterType(TypeSourceInfo *&TSI,
                                              SourceLocation Loc);
   QualType CheckNonTypeTemplateParameterType(QualType T, SourceLocation Loc);
 
   NamedDecl *ActOnNonTypeTemplateParameter(Scope *S, Declarator &D,
                                       unsigned Depth,
                                       unsigned Position,
                                       SourceLocation EqualLoc,
                                       Expr *DefaultArg);
   NamedDecl *ActOnTemplateTemplateParameter(Scope *S,
                                        SourceLocation TmpLoc,
                                        TemplateParameterList *Params,
                                        SourceLocation EllipsisLoc,
                                        IdentifierInfo *ParamName,
                                        SourceLocation ParamNameLoc,
                                        unsigned Depth,
                                        unsigned Position,
                                        SourceLocation EqualLoc,
                                        ParsedTemplateArgument DefaultArg);
 
   TemplateParameterList *
   ActOnTemplateParameterList(unsigned Depth,
                              SourceLocation ExportLoc,
                              SourceLocation TemplateLoc,
                              SourceLocation LAngleLoc,
                              ArrayRef<NamedDecl *> Params,
                              SourceLocation RAngleLoc,
                              Expr *RequiresClause);
 
   /// The context in which we are checking a template parameter list.
   enum TemplateParamListContext {
     TPC_ClassTemplate,
     TPC_VarTemplate,
     TPC_FunctionTemplate,
     TPC_ClassTemplateMember,
     TPC_FriendClassTemplate,
     TPC_FriendFunctionTemplate,
     TPC_FriendFunctionTemplateDefinition,
     TPC_TypeAliasTemplate
   };
 
   bool CheckTemplateParameterList(TemplateParameterList *NewParams,
                                   TemplateParameterList *OldParams,
                                   TemplateParamListContext TPC,
                                   SkipBodyInfo *SkipBody = nullptr);
   TemplateParameterList *MatchTemplateParametersToScopeSpecifier(
       SourceLocation DeclStartLoc, SourceLocation DeclLoc,
       const CXXScopeSpec &SS, TemplateIdAnnotation *TemplateId,
       ArrayRef<TemplateParameterList *> ParamLists,
       bool IsFriend, bool &IsMemberSpecialization, bool &Invalid,
       bool SuppressDiagnostic = false);
 
   DeclResult CheckClassTemplate(
       Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
       CXXScopeSpec &SS, IdentifierInfo *Name, SourceLocation NameLoc,
       const ParsedAttributesView &Attr, TemplateParameterList *TemplateParams,
       AccessSpecifier AS, SourceLocation ModulePrivateLoc,
       SourceLocation FriendLoc, unsigned NumOuterTemplateParamLists,
       TemplateParameterList **OuterTemplateParamLists,
       SkipBodyInfo *SkipBody = nullptr);
 
   TemplateArgumentLoc getTrivialTemplateArgumentLoc(const TemplateArgument &Arg,
                                                     QualType NTTPType,
                                                     SourceLocation Loc);
 
   /// Get a template argument mapping the given template parameter to itself,
   /// e.g. for X in \c template<int X>, this would return an expression template
   /// argument referencing X.
   TemplateArgumentLoc getIdentityTemplateArgumentLoc(NamedDecl *Param,
                                                      SourceLocation Location);
 
   void translateTemplateArguments(const ASTTemplateArgsPtr &In,
                                   TemplateArgumentListInfo &Out);
 
   ParsedTemplateArgument ActOnTemplateTypeArgument(TypeResult ParsedType);
 
   void NoteAllFoundTemplates(TemplateName Name);
 
   QualType CheckTemplateIdType(TemplateName Template,
                                SourceLocation TemplateLoc,
                               TemplateArgumentListInfo &TemplateArgs);
 
   TypeResult
   ActOnTemplateIdType(Scope *S, CXXScopeSpec &SS, SourceLocation TemplateKWLoc,
                       TemplateTy Template, IdentifierInfo *TemplateII,
                       SourceLocation TemplateIILoc, SourceLocation LAngleLoc,
                       ASTTemplateArgsPtr TemplateArgs, SourceLocation RAngleLoc,
                       bool IsCtorOrDtorName = false, bool IsClassName = false,
                       ImplicitTypenameContext AllowImplicitTypename =
                           ImplicitTypenameContext::No);
 
   /// Parsed an elaborated-type-specifier that refers to a template-id,
   /// such as \c class T::template apply<U>.
   TypeResult ActOnTagTemplateIdType(TagUseKind TUK,
                                     TypeSpecifierType TagSpec,
                                     SourceLocation TagLoc,
                                     CXXScopeSpec &SS,
                                     SourceLocation TemplateKWLoc,
                                     TemplateTy TemplateD,
                                     SourceLocation TemplateLoc,
                                     SourceLocation LAngleLoc,
                                     ASTTemplateArgsPtr TemplateArgsIn,
                                     SourceLocation RAngleLoc);
 
   DeclResult ActOnVarTemplateSpecialization(
       Scope *S, Declarator &D, TypeSourceInfo *DI,
       SourceLocation TemplateKWLoc, TemplateParameterList *TemplateParams,
       StorageClass SC, bool IsPartialSpecialization);
 
   /// Get the specialization of the given variable template corresponding to
   /// the specified argument list, or a null-but-valid result if the arguments
   /// are dependent.
   DeclResult CheckVarTemplateId(VarTemplateDecl *Template,
                                 SourceLocation TemplateLoc,
                                 SourceLocation TemplateNameLoc,
                                 const TemplateArgumentListInfo &TemplateArgs);
 
   /// Form a reference to the specialization of the given variable template
   /// corresponding to the specified argument list, or a null-but-valid result
   /// if the arguments are dependent.
   ExprResult CheckVarTemplateId(const CXXScopeSpec &SS,
                                 const DeclarationNameInfo &NameInfo,
                                 VarTemplateDecl *Template,
                                 SourceLocation TemplateLoc,
                                 const TemplateArgumentListInfo *TemplateArgs);
 
   ExprResult
   CheckConceptTemplateId(const CXXScopeSpec &SS,
                          SourceLocation TemplateKWLoc,
                          const DeclarationNameInfo &ConceptNameInfo,
                          NamedDecl *FoundDecl, ConceptDecl *NamedConcept,
                          const TemplateArgumentListInfo *TemplateArgs);
 
   void diagnoseMissingTemplateArguments(TemplateName Name, SourceLocation Loc);
 
   ExprResult BuildTemplateIdExpr(const CXXScopeSpec &SS,
                                  SourceLocation TemplateKWLoc,
                                  LookupResult &R,
                                  bool RequiresADL,
                                const TemplateArgumentListInfo *TemplateArgs);
 
   ExprResult BuildQualifiedTemplateIdExpr(CXXScopeSpec &SS,
                                           SourceLocation TemplateKWLoc,
                                const DeclarationNameInfo &NameInfo,
                                const TemplateArgumentListInfo *TemplateArgs);
 
   TemplateNameKind ActOnTemplateName(
       Scope *S, CXXScopeSpec &SS, SourceLocation TemplateKWLoc,
       const UnqualifiedId &Name, ParsedType ObjectType, bool EnteringContext,
       TemplateTy &Template, bool AllowInjectedClassName = false);
 
   DeclResult ActOnClassTemplateSpecialization(
       Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
       SourceLocation ModulePrivateLoc, CXXScopeSpec &SS,
       TemplateIdAnnotation &TemplateId, const ParsedAttributesView &Attr,
       MultiTemplateParamsArg TemplateParameterLists,
       SkipBodyInfo *SkipBody = nullptr);
 
   bool CheckTemplatePartialSpecializationArgs(SourceLocation Loc,
                                               TemplateDecl *PrimaryTemplate,
                                               unsigned NumExplicitArgs,
                                               ArrayRef<TemplateArgument> Args);
   void CheckTemplatePartialSpecialization(
       ClassTemplatePartialSpecializationDecl *Partial);
   void CheckTemplatePartialSpecialization(
       VarTemplatePartialSpecializationDecl *Partial);
 
   Decl *ActOnTemplateDeclarator(Scope *S,
                                 MultiTemplateParamsArg TemplateParameterLists,
                                 Declarator &D);
 
   bool
   CheckSpecializationInstantiationRedecl(SourceLocation NewLoc,
                                          TemplateSpecializationKind NewTSK,
                                          NamedDecl *PrevDecl,
                                          TemplateSpecializationKind PrevTSK,
                                          SourceLocation PrevPtOfInstantiation,
                                          bool &SuppressNew);
 
   bool CheckDependentFunctionTemplateSpecialization(FunctionDecl *FD,
                     const TemplateArgumentListInfo &ExplicitTemplateArgs,
                                                     LookupResult &Previous);
 
   bool CheckFunctionTemplateSpecialization(
       FunctionDecl *FD, TemplateArgumentListInfo *ExplicitTemplateArgs,
       LookupResult &Previous, bool QualifiedFriend = false);
   bool CheckMemberSpecialization(NamedDecl *Member, LookupResult &Previous);
   void CompleteMemberSpecialization(NamedDecl *Member, LookupResult &Previous);
 
   DeclResult ActOnExplicitInstantiation(
       Scope *S, SourceLocation ExternLoc, SourceLocation TemplateLoc,
       unsigned TagSpec, SourceLocation KWLoc, const CXXScopeSpec &SS,
       TemplateTy Template, SourceLocation TemplateNameLoc,
       SourceLocation LAngleLoc, ASTTemplateArgsPtr TemplateArgs,
       SourceLocation RAngleLoc, const ParsedAttributesView &Attr);
 
   DeclResult ActOnExplicitInstantiation(Scope *S, SourceLocation ExternLoc,
                                         SourceLocation TemplateLoc,
                                         unsigned TagSpec, SourceLocation KWLoc,
                                         CXXScopeSpec &SS, IdentifierInfo *Name,
                                         SourceLocation NameLoc,
                                         const ParsedAttributesView &Attr);
 
   DeclResult ActOnExplicitInstantiation(Scope *S,
                                         SourceLocation ExternLoc,
                                         SourceLocation TemplateLoc,
                                         Declarator &D);
 
   TemplateArgumentLoc SubstDefaultTemplateArgumentIfAvailable(
       TemplateDecl *Template, SourceLocation TemplateLoc,
       SourceLocation RAngleLoc, Decl *Param,
       ArrayRef<TemplateArgument> SugaredConverted,
       ArrayRef<TemplateArgument> CanonicalConverted, bool &HasDefaultArg);
 
   /// Specifies the context in which a particular template
   /// argument is being checked.
   enum CheckTemplateArgumentKind {
     /// The template argument was specified in the code or was
     /// instantiated with some deduced template arguments.
     CTAK_Specified,
 
     /// The template argument was deduced via template argument
     /// deduction.
     CTAK_Deduced,
 
     /// The template argument was deduced from an array bound
     /// via template argument deduction.
     CTAK_DeducedFromArrayBound
   };
 
   bool
   CheckTemplateArgument(NamedDecl *Param, TemplateArgumentLoc &Arg,
                         NamedDecl *Template, SourceLocation TemplateLoc,
                         SourceLocation RAngleLoc, unsigned ArgumentPackIndex,
                         SmallVectorImpl<TemplateArgument> &SugaredConverted,
                         SmallVectorImpl<TemplateArgument> &CanonicalConverted,
                         CheckTemplateArgumentKind CTAK);
 
   /// Check that the given template arguments can be provided to
   /// the given template, converting the arguments along the way.
   ///
   /// \param Template The template to which the template arguments are being
   /// provided.
   ///
   /// \param TemplateLoc The location of the template name in the source.
   ///
   /// \param TemplateArgs The list of template arguments. If the template is
   /// a template template parameter, this function may extend the set of
   /// template arguments to also include substituted, defaulted template
   /// arguments.
   ///
   /// \param PartialTemplateArgs True if the list of template arguments is
   /// intentionally partial, e.g., because we're checking just the initial
   /// set of template arguments.
   ///
   /// \param Converted Will receive the converted, canonicalized template
   /// arguments.
   ///
   /// \param UpdateArgsWithConversions If \c true, update \p TemplateArgs to
   /// contain the converted forms of the template arguments as written.
   /// Otherwise, \p TemplateArgs will not be modified.
   ///
   /// \param ConstraintsNotSatisfied If provided, and an error occurred, will
   /// receive true if the cause for the error is the associated constraints of
   /// the template not being satisfied by the template arguments.
   ///
   /// \returns true if an error occurred, false otherwise.
   bool CheckTemplateArgumentList(
       TemplateDecl *Template, SourceLocation TemplateLoc,
       TemplateArgumentListInfo &TemplateArgs, bool PartialTemplateArgs,
       SmallVectorImpl<TemplateArgument> &SugaredConverted,
       SmallVectorImpl<TemplateArgument> &CanonicalConverted,
       bool UpdateArgsWithConversions = true,
       bool *ConstraintsNotSatisfied = nullptr);
 
   bool CheckTemplateTypeArgument(
       TemplateTypeParmDecl *Param, TemplateArgumentLoc &Arg,
       SmallVectorImpl<TemplateArgument> &SugaredConverted,
       SmallVectorImpl<TemplateArgument> &CanonicalConverted);
 
   bool CheckTemplateArgument(TypeSourceInfo *Arg);
   ExprResult CheckTemplateArgument(NonTypeTemplateParmDecl *Param,
                                    QualType InstantiatedParamType, Expr *Arg,
                                    TemplateArgument &SugaredConverted,
                                    TemplateArgument &CanonicalConverted,
                                    CheckTemplateArgumentKind CTAK);
   bool CheckTemplateTemplateArgument(TemplateTemplateParmDecl *Param,
                                      TemplateParameterList *Params,
                                      TemplateArgumentLoc &Arg);
 
   ExprResult
   BuildExpressionFromDeclTemplateArgument(const TemplateArgument &Arg,
                                           QualType ParamType,
                                           SourceLocation Loc);
   ExprResult
   BuildExpressionFromIntegralTemplateArgument(const TemplateArgument &Arg,
                                               SourceLocation Loc);
 
   /// Enumeration describing how template parameter lists are compared
   /// for equality.
   enum TemplateParameterListEqualKind {
     /// We are matching the template parameter lists of two templates
     /// that might be redeclarations.
     ///
     /// \code
     /// template<typename T> struct X;
     /// template<typename T> struct X;
     /// \endcode
     TPL_TemplateMatch,
 
     /// We are matching the template parameter lists of two template
     /// template parameters as part of matching the template parameter lists
     /// of two templates that might be redeclarations.
     ///
     /// \code
     /// template<template<int I> class TT> struct X;
     /// template<template<int Value> class Other> struct X;
     /// \endcode
     TPL_TemplateTemplateParmMatch,
 
     /// We are matching the template parameter lists of a template
     /// template argument against the template parameter lists of a template
     /// template parameter.
     ///
     /// \code
     /// template<template<int Value> class Metafun> struct X;
     /// template<int Value> struct integer_c;
     /// X<integer_c> xic;
     /// \endcode
     TPL_TemplateTemplateArgumentMatch,
 
     /// We are determining whether the template-parameters are equivalent
     /// according to C++ [temp.over.link]/6. This comparison does not consider
     /// constraints.
     ///
     /// \code
     /// template<C1 T> void f(T);
     /// template<C2 T> void f(T);
     /// \endcode
     TPL_TemplateParamsEquivalent,
   };
 
   bool TemplateParameterListsAreEqual(
       const NamedDecl *NewInstFrom, TemplateParameterList *New,
       const NamedDecl *OldInstFrom, TemplateParameterList *Old, bool Complain,
       TemplateParameterListEqualKind Kind,
       SourceLocation TemplateArgLoc = SourceLocation());
 
   bool TemplateParameterListsAreEqual(
       TemplateParameterList *New, TemplateParameterList *Old, bool Complain,
       TemplateParameterListEqualKind Kind,
       SourceLocation TemplateArgLoc = SourceLocation()) {
     return TemplateParameterListsAreEqual(nullptr, New, nullptr, Old, Complain,
                                           Kind, TemplateArgLoc);
   }
 
   bool CheckTemplateDeclScope(Scope *S, TemplateParameterList *TemplateParams);
 
   /// Called when the parser has parsed a C++ typename
   /// specifier, e.g., "typename T::type".
   ///
   /// \param S The scope in which this typename type occurs.
   /// \param TypenameLoc the location of the 'typename' keyword
   /// \param SS the nested-name-specifier following the typename (e.g., 'T::').
   /// \param II the identifier we're retrieving (e.g., 'type' in the example).
   /// \param IdLoc the location of the identifier.
   /// \param IsImplicitTypename context where T::type refers to a type.
   TypeResult ActOnTypenameType(
       Scope *S, SourceLocation TypenameLoc, const CXXScopeSpec &SS,
       const IdentifierInfo &II, SourceLocation IdLoc,
       ImplicitTypenameContext IsImplicitTypename = ImplicitTypenameContext::No);
 
   /// Called when the parser has parsed a C++ typename
   /// specifier that ends in a template-id, e.g.,
   /// "typename MetaFun::template apply<T1, T2>".
   ///
   /// \param S The scope in which this typename type occurs.
   /// \param TypenameLoc the location of the 'typename' keyword
   /// \param SS the nested-name-specifier following the typename (e.g., 'T::').
   /// \param TemplateLoc the location of the 'template' keyword, if any.
   /// \param TemplateName The template name.
   /// \param TemplateII The identifier used to name the template.
   /// \param TemplateIILoc The location of the template name.
   /// \param LAngleLoc The location of the opening angle bracket  ('<').
   /// \param TemplateArgs The template arguments.
   /// \param RAngleLoc The location of the closing angle bracket  ('>').
   TypeResult
   ActOnTypenameType(Scope *S, SourceLocation TypenameLoc,
                     const CXXScopeSpec &SS,
                     SourceLocation TemplateLoc,
                     TemplateTy TemplateName,
                     IdentifierInfo *TemplateII,
                     SourceLocation TemplateIILoc,
                     SourceLocation LAngleLoc,
                     ASTTemplateArgsPtr TemplateArgs,
                     SourceLocation RAngleLoc);
 
   QualType CheckTypenameType(ElaboratedTypeKeyword Keyword,
                              SourceLocation KeywordLoc,
                              NestedNameSpecifierLoc QualifierLoc,
                              const IdentifierInfo &II,
                              SourceLocation IILoc,
                              TypeSourceInfo **TSI,
                              bool DeducedTSTContext);
 
   QualType CheckTypenameType(ElaboratedTypeKeyword Keyword,
                              SourceLocation KeywordLoc,
                              NestedNameSpecifierLoc QualifierLoc,
                              const IdentifierInfo &II,
                              SourceLocation IILoc,
                              bool DeducedTSTContext = true);
 
 
   TypeSourceInfo *RebuildTypeInCurrentInstantiation(TypeSourceInfo *T,
                                                     SourceLocation Loc,
                                                     DeclarationName Name);
   bool RebuildNestedNameSpecifierInCurrentInstantiation(CXXScopeSpec &SS);
 
   ExprResult RebuildExprInCurrentInstantiation(Expr *E);
   bool RebuildTemplateParamsInCurrentInstantiation(
                                                 TemplateParameterList *Params);
 
   std::string
   getTemplateArgumentBindingsText(const TemplateParameterList *Params,
                                   const TemplateArgumentList &Args);
 
   std::string
   getTemplateArgumentBindingsText(const TemplateParameterList *Params,
                                   const TemplateArgument *Args,
                                   unsigned NumArgs);
 
   //===--------------------------------------------------------------------===//
   // C++ Concepts
   //===--------------------------------------------------------------------===//
   Decl *ActOnConceptDefinition(
       Scope *S, MultiTemplateParamsArg TemplateParameterLists,
       IdentifierInfo *Name, SourceLocation NameLoc, Expr *ConstraintExpr);
 
   void CheckConceptRedefinition(ConceptDecl *NewDecl, LookupResult &Previous,
                                 bool &AddToScope);
 
   RequiresExprBodyDecl *
   ActOnStartRequiresExpr(SourceLocation RequiresKWLoc,
                          ArrayRef<ParmVarDecl *> LocalParameters,
                          Scope *BodyScope);
   void ActOnFinishRequiresExpr();
   concepts::Requirement *ActOnSimpleRequirement(Expr *E);
   concepts::Requirement *ActOnTypeRequirement(
       SourceLocation TypenameKWLoc, CXXScopeSpec &SS, SourceLocation NameLoc,
       IdentifierInfo *TypeName, TemplateIdAnnotation *TemplateId);
   concepts::Requirement *ActOnCompoundRequirement(Expr *E,
                                                   SourceLocation NoexceptLoc);
   concepts::Requirement *
   ActOnCompoundRequirement(
       Expr *E, SourceLocation NoexceptLoc, CXXScopeSpec &SS,
       TemplateIdAnnotation *TypeConstraint, unsigned Depth);
   concepts::Requirement *ActOnNestedRequirement(Expr *Constraint);
   concepts::ExprRequirement *
   BuildExprRequirement(
       Expr *E, bool IsSatisfied, SourceLocation NoexceptLoc,
       concepts::ExprRequirement::ReturnTypeRequirement ReturnTypeRequirement);
   concepts::ExprRequirement *
   BuildExprRequirement(
       concepts::Requirement::SubstitutionDiagnostic *ExprSubstDiag,
       bool IsSatisfied, SourceLocation NoexceptLoc,
       concepts::ExprRequirement::ReturnTypeRequirement ReturnTypeRequirement);
   concepts::TypeRequirement *BuildTypeRequirement(TypeSourceInfo *Type);
   concepts::TypeRequirement *
   BuildTypeRequirement(
       concepts::Requirement::SubstitutionDiagnostic *SubstDiag);
   concepts::NestedRequirement *BuildNestedRequirement(Expr *E);
   concepts::NestedRequirement *
   BuildNestedRequirement(StringRef InvalidConstraintEntity,
                          const ASTConstraintSatisfaction &Satisfaction);
   ExprResult ActOnRequiresExpr(SourceLocation RequiresKWLoc,
                                RequiresExprBodyDecl *Body,
                                ArrayRef<ParmVarDecl *> LocalParameters,
                                ArrayRef<concepts::Requirement *> Requirements,
                                SourceLocation ClosingBraceLoc);
 
   //===--------------------------------------------------------------------===//
   // C++ Variadic Templates (C++0x [temp.variadic])
   //===--------------------------------------------------------------------===//
 
   /// Determine whether an unexpanded parameter pack might be permitted in this
   /// location. Useful for error recovery.
   bool isUnexpandedParameterPackPermitted();
 
   /// The context in which an unexpanded parameter pack is
   /// being diagnosed.
   ///
   /// Note that the values of this enumeration line up with the first
   /// argument to the \c err_unexpanded_parameter_pack diagnostic.
   enum UnexpandedParameterPackContext {
     /// An arbitrary expression.
     UPPC_Expression = 0,
 
     /// The base type of a class type.
     UPPC_BaseType,
 
     /// The type of an arbitrary declaration.
     UPPC_DeclarationType,
 
     /// The type of a data member.
     UPPC_DataMemberType,
 
     /// The size of a bit-field.
     UPPC_BitFieldWidth,
 
     /// The expression in a static assertion.
     UPPC_StaticAssertExpression,
 
     /// The fixed underlying type of an enumeration.
     UPPC_FixedUnderlyingType,
 
     /// The enumerator value.
     UPPC_EnumeratorValue,
 
     /// A using declaration.
     UPPC_UsingDeclaration,
 
     /// A friend declaration.
     UPPC_FriendDeclaration,
 
     /// A declaration qualifier.
     UPPC_DeclarationQualifier,
 
     /// An initializer.
     UPPC_Initializer,
 
     /// A default argument.
     UPPC_DefaultArgument,
 
     /// The type of a non-type template parameter.
     UPPC_NonTypeTemplateParameterType,
 
     /// The type of an exception.
     UPPC_ExceptionType,
 
     /// Partial specialization.
     UPPC_PartialSpecialization,
 
     /// Microsoft __if_exists.
     UPPC_IfExists,
 
     /// Microsoft __if_not_exists.
     UPPC_IfNotExists,
 
     /// Lambda expression.
     UPPC_Lambda,
 
     /// Block expression.
     UPPC_Block,
 
     /// A type constraint.
     UPPC_TypeConstraint,
 
     // A requirement in a requires-expression.
     UPPC_Requirement,
 
     // A requires-clause.
     UPPC_RequiresClause,
   };
 
   /// Diagnose unexpanded parameter packs.
   ///
   /// \param Loc The location at which we should emit the diagnostic.
   ///
   /// \param UPPC The context in which we are diagnosing unexpanded
   /// parameter packs.
   ///
   /// \param Unexpanded the set of unexpanded parameter packs.
   ///
   /// \returns true if an error occurred, false otherwise.
   bool DiagnoseUnexpandedParameterPacks(SourceLocation Loc,
                                         UnexpandedParameterPackContext UPPC,
                                   ArrayRef<UnexpandedParameterPack> Unexpanded);
 
   /// If the given type contains an unexpanded parameter pack,
   /// diagnose the error.
   ///
   /// \param Loc The source location where a diagnostc should be emitted.
   ///
   /// \param T The type that is being checked for unexpanded parameter
   /// packs.
   ///
   /// \returns true if an error occurred, false otherwise.
   bool DiagnoseUnexpandedParameterPack(SourceLocation Loc, TypeSourceInfo *T,
                                        UnexpandedParameterPackContext UPPC);
 
   /// If the given expression contains an unexpanded parameter
   /// pack, diagnose the error.
   ///
   /// \param E The expression that is being checked for unexpanded
   /// parameter packs.
   ///
   /// \returns true if an error occurred, false otherwise.
   bool DiagnoseUnexpandedParameterPack(Expr *E,
                        UnexpandedParameterPackContext UPPC = UPPC_Expression);
 
   /// If the given requirees-expression contains an unexpanded reference to one
   /// of its own parameter packs, diagnose the error.
   ///
   /// \param RE The requiress-expression that is being checked for unexpanded
   /// parameter packs.
   ///
   /// \returns true if an error occurred, false otherwise.
   bool DiagnoseUnexpandedParameterPackInRequiresExpr(RequiresExpr *RE);
 
   /// If the given nested-name-specifier contains an unexpanded
   /// parameter pack, diagnose the error.
   ///
   /// \param SS The nested-name-specifier that is being checked for
   /// unexpanded parameter packs.
   ///
   /// \returns true if an error occurred, false otherwise.
   bool DiagnoseUnexpandedParameterPack(const CXXScopeSpec &SS,
                                        UnexpandedParameterPackContext UPPC);
 
   /// If the given name contains an unexpanded parameter pack,
   /// diagnose the error.
   ///
   /// \param NameInfo The name (with source location information) that
   /// is being checked for unexpanded parameter packs.
   ///
   /// \returns true if an error occurred, false otherwise.
   bool DiagnoseUnexpandedParameterPack(const DeclarationNameInfo &NameInfo,
                                        UnexpandedParameterPackContext UPPC);
 
   /// If the given template name contains an unexpanded parameter pack,
   /// diagnose the error.
   ///
   /// \param Loc The location of the template name.
   ///
   /// \param Template The template name that is being checked for unexpanded
   /// parameter packs.
   ///
   /// \returns true if an error occurred, false otherwise.
   bool DiagnoseUnexpandedParameterPack(SourceLocation Loc,
                                        TemplateName Template,
                                        UnexpandedParameterPackContext UPPC);
 
   /// If the given template argument contains an unexpanded parameter
   /// pack, diagnose the error.
   ///
   /// \param Arg The template argument that is being checked for unexpanded
   /// parameter packs.
   ///
   /// \returns true if an error occurred, false otherwise.
   bool DiagnoseUnexpandedParameterPack(TemplateArgumentLoc Arg,
                                        UnexpandedParameterPackContext UPPC);
 
   /// Collect the set of unexpanded parameter packs within the given
   /// template argument.
   ///
   /// \param Arg The template argument that will be traversed to find
   /// unexpanded parameter packs.
   void collectUnexpandedParameterPacks(TemplateArgument Arg,
                    SmallVectorImpl<UnexpandedParameterPack> &Unexpanded);
 
   /// Collect the set of unexpanded parameter packs within the given
   /// template argument.
   ///
   /// \param Arg The template argument that will be traversed to find
   /// unexpanded parameter packs.
   void collectUnexpandedParameterPacks(TemplateArgumentLoc Arg,
                     SmallVectorImpl<UnexpandedParameterPack> &Unexpanded);
 
   /// Collect the set of unexpanded parameter packs within the given
   /// type.
   ///
   /// \param T The type that will be traversed to find
   /// unexpanded parameter packs.
   void collectUnexpandedParameterPacks(QualType T,
                    SmallVectorImpl<UnexpandedParameterPack> &Unexpanded);
 
   /// Collect the set of unexpanded parameter packs within the given
   /// type.
   ///
   /// \param TL The type that will be traversed to find
   /// unexpanded parameter packs.
   void collectUnexpandedParameterPacks(TypeLoc TL,
                    SmallVectorImpl<UnexpandedParameterPack> &Unexpanded);
 
   /// Collect the set of unexpanded parameter packs within the given
   /// nested-name-specifier.
   ///
   /// \param NNS The nested-name-specifier that will be traversed to find
   /// unexpanded parameter packs.
   void collectUnexpandedParameterPacks(NestedNameSpecifierLoc NNS,
                          SmallVectorImpl<UnexpandedParameterPack> &Unexpanded);
 
   /// Collect the set of unexpanded parameter packs within the given
   /// name.
   ///
   /// \param NameInfo The name that will be traversed to find
   /// unexpanded parameter packs.
   void collectUnexpandedParameterPacks(const DeclarationNameInfo &NameInfo,
                          SmallVectorImpl<UnexpandedParameterPack> &Unexpanded);
 
   /// Invoked when parsing a template argument followed by an
   /// ellipsis, which creates a pack expansion.
   ///
   /// \param Arg The template argument preceding the ellipsis, which
   /// may already be invalid.
   ///
   /// \param EllipsisLoc The location of the ellipsis.
   ParsedTemplateArgument ActOnPackExpansion(const ParsedTemplateArgument &Arg,
                                             SourceLocation EllipsisLoc);
 
   /// Invoked when parsing a type followed by an ellipsis, which
   /// creates a pack expansion.
   ///
   /// \param Type The type preceding the ellipsis, which will become
   /// the pattern of the pack expansion.
   ///
   /// \param EllipsisLoc The location of the ellipsis.
   TypeResult ActOnPackExpansion(ParsedType Type, SourceLocation EllipsisLoc);
 
   /// Construct a pack expansion type from the pattern of the pack
   /// expansion.
   TypeSourceInfo *CheckPackExpansion(TypeSourceInfo *Pattern,
                                      SourceLocation EllipsisLoc,
                                      std::optional<unsigned> NumExpansions);
 
   /// Construct a pack expansion type from the pattern of the pack
   /// expansion.
   QualType CheckPackExpansion(QualType Pattern, SourceRange PatternRange,
                               SourceLocation EllipsisLoc,
                               std::optional<unsigned> NumExpansions);
 
   /// Invoked when parsing an expression followed by an ellipsis, which
   /// creates a pack expansion.
   ///
   /// \param Pattern The expression preceding the ellipsis, which will become
   /// the pattern of the pack expansion.
   ///
   /// \param EllipsisLoc The location of the ellipsis.
   ExprResult ActOnPackExpansion(Expr *Pattern, SourceLocation EllipsisLoc);
 
   /// Invoked when parsing an expression followed by an ellipsis, which
   /// creates a pack expansion.
   ///
   /// \param Pattern The expression preceding the ellipsis, which will become
   /// the pattern of the pack expansion.
   ///
   /// \param EllipsisLoc The location of the ellipsis.
   ExprResult CheckPackExpansion(Expr *Pattern, SourceLocation EllipsisLoc,
                                 std::optional<unsigned> NumExpansions);
 
   /// Determine whether we could expand a pack expansion with the
   /// given set of parameter packs into separate arguments by repeatedly
   /// transforming the pattern.
   ///
   /// \param EllipsisLoc The location of the ellipsis that identifies the
   /// pack expansion.
   ///
   /// \param PatternRange The source range that covers the entire pattern of
   /// the pack expansion.
   ///
   /// \param Unexpanded The set of unexpanded parameter packs within the
   /// pattern.
   ///
   /// \param ShouldExpand Will be set to \c true if the transformer should
   /// expand the corresponding pack expansions into separate arguments. When
   /// set, \c NumExpansions must also be set.
   ///
   /// \param RetainExpansion Whether the caller should add an unexpanded
   /// pack expansion after all of the expanded arguments. This is used
   /// when extending explicitly-specified template argument packs per
   /// C++0x [temp.arg.explicit]p9.
   ///
   /// \param NumExpansions The number of separate arguments that will be in
   /// the expanded form of the corresponding pack expansion. This is both an
   /// input and an output parameter, which can be set by the caller if the
   /// number of expansions is known a priori (e.g., due to a prior substitution)
   /// and will be set by the callee when the number of expansions is known.
   /// The callee must set this value when \c ShouldExpand is \c true; it may
   /// set this value in other cases.
   ///
   /// \returns true if an error occurred (e.g., because the parameter packs
   /// are to be instantiated with arguments of different lengths), false
   /// otherwise. If false, \c ShouldExpand (and possibly \c NumExpansions)
   /// must be set.
   bool CheckParameterPacksForExpansion(
       SourceLocation EllipsisLoc, SourceRange PatternRange,
       ArrayRef<UnexpandedParameterPack> Unexpanded,
       const MultiLevelTemplateArgumentList &TemplateArgs, bool &ShouldExpand,
       bool &RetainExpansion, std::optional<unsigned> &NumExpansions);
 
   /// Determine the number of arguments in the given pack expansion
   /// type.
   ///
   /// This routine assumes that the number of arguments in the expansion is
   /// consistent across all of the unexpanded parameter packs in its pattern.
   ///
   /// Returns an empty Optional if the type can't be expanded.
   std::optional<unsigned> getNumArgumentsInExpansion(
       QualType T, const MultiLevelTemplateArgumentList &TemplateArgs);
 
   /// Determine whether the given declarator contains any unexpanded
   /// parameter packs.
   ///
   /// This routine is used by the parser to disambiguate function declarators
   /// with an ellipsis prior to the ')', e.g.,
   ///
   /// \code
   ///   void f(T...);
   /// \endcode
   ///
   /// To determine whether we have an (unnamed) function parameter pack or
   /// a variadic function.
   ///
   /// \returns true if the declarator contains any unexpanded parameter packs,
   /// false otherwise.
   bool containsUnexpandedParameterPacks(Declarator &D);
 
   /// Returns the pattern of the pack expansion for a template argument.
   ///
   /// \param OrigLoc The template argument to expand.
   ///
   /// \param Ellipsis Will be set to the location of the ellipsis.
   ///
   /// \param NumExpansions Will be set to the number of expansions that will
   /// be generated from this pack expansion, if known a priori.
   TemplateArgumentLoc getTemplateArgumentPackExpansionPattern(
       TemplateArgumentLoc OrigLoc, SourceLocation &Ellipsis,
       std::optional<unsigned> &NumExpansions) const;
 
   /// Given a template argument that contains an unexpanded parameter pack, but
   /// which has already been substituted, attempt to determine the number of
   /// elements that will be produced once this argument is fully-expanded.
   ///
   /// This is intended for use when transforming 'sizeof...(Arg)' in order to
   /// avoid actually expanding the pack where possible.
   std::optional<unsigned> getFullyPackExpandedSize(TemplateArgument Arg);
 
   //===--------------------------------------------------------------------===//
   // C++ Template Argument Deduction (C++ [temp.deduct])
   //===--------------------------------------------------------------------===//
 
   /// Adjust the type \p ArgFunctionType to match the calling convention,
   /// noreturn, and optionally the exception specification of \p FunctionType.
   /// Deduction often wants to ignore these properties when matching function
   /// types.
   QualType adjustCCAndNoReturn(QualType ArgFunctionType, QualType FunctionType,
                                bool AdjustExceptionSpec = false);
 
   /// Describes the result of template argument deduction.
   ///
   /// The TemplateDeductionResult enumeration describes the result of
   /// template argument deduction, as returned from
   /// DeduceTemplateArguments(). The separate TemplateDeductionInfo
   /// structure provides additional information about the results of
   /// template argument deduction, e.g., the deduced template argument
   /// list (if successful) or the specific template parameters or
   /// deduced arguments that were involved in the failure.
   enum TemplateDeductionResult {
     /// Template argument deduction was successful.
     TDK_Success = 0,
     /// The declaration was invalid; do nothing.
     TDK_Invalid,
     /// Template argument deduction exceeded the maximum template
     /// instantiation depth (which has already been diagnosed).
     TDK_InstantiationDepth,
     /// Template argument deduction did not deduce a value
     /// for every template parameter.
     TDK_Incomplete,
     /// Template argument deduction did not deduce a value for every
     /// expansion of an expanded template parameter pack.
     TDK_IncompletePack,
     /// Template argument deduction produced inconsistent
     /// deduced values for the given template parameter.
     TDK_Inconsistent,
     /// Template argument deduction failed due to inconsistent
     /// cv-qualifiers on a template parameter type that would
     /// otherwise be deduced, e.g., we tried to deduce T in "const T"
     /// but were given a non-const "X".
     TDK_Underqualified,
     /// Substitution of the deduced template argument values
     /// resulted in an error.
     TDK_SubstitutionFailure,
     /// After substituting deduced template arguments, a dependent
     /// parameter type did not match the corresponding argument.
     TDK_DeducedMismatch,
     /// After substituting deduced template arguments, an element of
     /// a dependent parameter type did not match the corresponding element
     /// of the corresponding argument (when deducing from an initializer list).
     TDK_DeducedMismatchNested,
     /// A non-depnedent component of the parameter did not match the
     /// corresponding component of the argument.
     TDK_NonDeducedMismatch,
     /// When performing template argument deduction for a function
     /// template, there were too many call arguments.
     TDK_TooManyArguments,
     /// When performing template argument deduction for a function
     /// template, there were too few call arguments.
     TDK_TooFewArguments,
     /// The explicitly-specified template arguments were not valid
     /// template arguments for the given template.
     TDK_InvalidExplicitArguments,
     /// Checking non-dependent argument conversions failed.
     TDK_NonDependentConversionFailure,
     /// The deduced arguments did not satisfy the constraints associated
     /// with the template.
     TDK_ConstraintsNotSatisfied,
     /// Deduction failed; that's all we know.
     TDK_MiscellaneousDeductionFailure,
     /// CUDA Target attributes do not match.
     TDK_CUDATargetMismatch,
     /// Some error which was already diagnosed.
     TDK_AlreadyDiagnosed
   };
 
   TemplateDeductionResult
   DeduceTemplateArguments(ClassTemplatePartialSpecializationDecl *Partial,
                           const TemplateArgumentList &TemplateArgs,
                           sema::TemplateDeductionInfo &Info);
 
   TemplateDeductionResult
   DeduceTemplateArguments(VarTemplatePartialSpecializationDecl *Partial,
                           const TemplateArgumentList &TemplateArgs,
                           sema::TemplateDeductionInfo &Info);
 
   TemplateDeductionResult SubstituteExplicitTemplateArguments(
       FunctionTemplateDecl *FunctionTemplate,
       TemplateArgumentListInfo &ExplicitTemplateArgs,
       SmallVectorImpl<DeducedTemplateArgument> &Deduced,
       SmallVectorImpl<QualType> &ParamTypes, QualType *FunctionType,
       sema::TemplateDeductionInfo &Info);
 
   /// brief A function argument from which we performed template argument
   // deduction for a call.
   struct OriginalCallArg {
     OriginalCallArg(QualType OriginalParamType, bool DecomposedParam,
                     unsigned ArgIdx, QualType OriginalArgType)
         : OriginalParamType(OriginalParamType),
           DecomposedParam(DecomposedParam), ArgIdx(ArgIdx),
           OriginalArgType(OriginalArgType) {}
 
     QualType OriginalParamType;
     bool DecomposedParam;
     unsigned ArgIdx;
     QualType OriginalArgType;
   };
 
   TemplateDeductionResult FinishTemplateArgumentDeduction(
       FunctionTemplateDecl *FunctionTemplate,
       SmallVectorImpl<DeducedTemplateArgument> &Deduced,
       unsigned NumExplicitlySpecified, FunctionDecl *&Specialization,
       sema::TemplateDeductionInfo &Info,
       SmallVectorImpl<OriginalCallArg> const *OriginalCallArgs = nullptr,
       bool PartialOverloading = false,
       llvm::function_ref<bool()> CheckNonDependent = []{ return false; });
 
   TemplateDeductionResult DeduceTemplateArguments(
       FunctionTemplateDecl *FunctionTemplate,
       TemplateArgumentListInfo *ExplicitTemplateArgs, ArrayRef<Expr *> Args,
       FunctionDecl *&Specialization, sema::TemplateDeductionInfo &Info,
       bool PartialOverloading, bool AggregateDeductionCandidate,
       llvm::function_ref<bool(ArrayRef<QualType>)> CheckNonDependent);
 
   TemplateDeductionResult
   DeduceTemplateArguments(FunctionTemplateDecl *FunctionTemplate,
                           TemplateArgumentListInfo *ExplicitTemplateArgs,
                           QualType ArgFunctionType,
                           FunctionDecl *&Specialization,
                           sema::TemplateDeductionInfo &Info,
                           bool IsAddressOfFunction = false);
 
   TemplateDeductionResult
   DeduceTemplateArguments(FunctionTemplateDecl *FunctionTemplate,
                           QualType ToType,
                           CXXConversionDecl *&Specialization,
                           sema::TemplateDeductionInfo &Info);
 
   TemplateDeductionResult
   DeduceTemplateArguments(FunctionTemplateDecl *FunctionTemplate,
                           TemplateArgumentListInfo *ExplicitTemplateArgs,
                           FunctionDecl *&Specialization,
                           sema::TemplateDeductionInfo &Info,
                           bool IsAddressOfFunction = false);
 
   /// Substitute Replacement for \p auto in \p TypeWithAuto
   QualType SubstAutoType(QualType TypeWithAuto, QualType Replacement);
   /// Substitute Replacement for auto in TypeWithAuto
   TypeSourceInfo* SubstAutoTypeSourceInfo(TypeSourceInfo *TypeWithAuto,
                                           QualType Replacement);
 
   // Substitute auto in TypeWithAuto for a Dependent auto type
   QualType SubstAutoTypeDependent(QualType TypeWithAuto);
 
   // Substitute auto in TypeWithAuto for a Dependent auto type
   TypeSourceInfo *
   SubstAutoTypeSourceInfoDependent(TypeSourceInfo *TypeWithAuto);
 
   /// Completely replace the \c auto in \p TypeWithAuto by
   /// \p Replacement. This does not retain any \c auto type sugar.
   QualType ReplaceAutoType(QualType TypeWithAuto, QualType Replacement);
   TypeSourceInfo *ReplaceAutoTypeSourceInfo(TypeSourceInfo *TypeWithAuto,
                                             QualType Replacement);
 
   TemplateDeductionResult
   DeduceAutoType(TypeLoc AutoTypeLoc, Expr *Initializer, QualType &Result,
                  sema::TemplateDeductionInfo &Info,
                  bool DependentDeduction = false,
                  bool IgnoreConstraints = false,
                  TemplateSpecCandidateSet *FailedTSC = nullptr);
   void DiagnoseAutoDeductionFailure(VarDecl *VDecl, Expr *Init);
   bool DeduceReturnType(FunctionDecl *FD, SourceLocation Loc,
                         bool Diagnose = true);
 
   bool CheckIfFunctionSpecializationIsImmediate(FunctionDecl *FD,
                                                 SourceLocation Loc);
 
   /// Declare implicit deduction guides for a class template if we've
   /// not already done so.
   void DeclareImplicitDeductionGuides(TemplateDecl *Template,
                                       SourceLocation Loc);
   FunctionTemplateDecl *DeclareImplicitDeductionGuideFromInitList(
       TemplateDecl *Template, MutableArrayRef<QualType> ParamTypes,
       SourceLocation Loc);
   llvm::DenseMap<unsigned, CXXDeductionGuideDecl *>
       AggregateDeductionCandidates;
 
   QualType DeduceTemplateSpecializationFromInitializer(
       TypeSourceInfo *TInfo, const InitializedEntity &Entity,
       const InitializationKind &Kind, MultiExprArg Init,
       ParenListExpr *PL = nullptr);
 
   QualType deduceVarTypeFromInitializer(VarDecl *VDecl, DeclarationName Name,
                                         QualType Type, TypeSourceInfo *TSI,
                                         SourceRange Range, bool DirectInit,
                                         Expr *Init);
 
   TypeLoc getReturnTypeLoc(FunctionDecl *FD) const;
 
   bool DeduceFunctionTypeFromReturnExpr(FunctionDecl *FD,
                                         SourceLocation ReturnLoc, Expr *RetExpr,
                                         const AutoType *AT);
 
   FunctionTemplateDecl *getMoreSpecializedTemplate(
       FunctionTemplateDecl *FT1, FunctionTemplateDecl *FT2, SourceLocation Loc,
       TemplatePartialOrderingContext TPOC, unsigned NumCallArguments1,
       unsigned NumCallArguments2, bool Reversed = false);
   UnresolvedSetIterator
   getMostSpecialized(UnresolvedSetIterator SBegin, UnresolvedSetIterator SEnd,
                      TemplateSpecCandidateSet &FailedCandidates,
                      SourceLocation Loc,
                      const PartialDiagnostic &NoneDiag,
                      const PartialDiagnostic &AmbigDiag,
                      const PartialDiagnostic &CandidateDiag,
                      bool Complain = true, QualType TargetType = QualType());
 
   ClassTemplatePartialSpecializationDecl *
   getMoreSpecializedPartialSpecialization(
                                   ClassTemplatePartialSpecializationDecl *PS1,
                                   ClassTemplatePartialSpecializationDecl *PS2,
                                   SourceLocation Loc);
 
   bool isMoreSpecializedThanPrimary(ClassTemplatePartialSpecializationDecl *T,
                                     sema::TemplateDeductionInfo &Info);
 
   VarTemplatePartialSpecializationDecl *getMoreSpecializedPartialSpecialization(
       VarTemplatePartialSpecializationDecl *PS1,
       VarTemplatePartialSpecializationDecl *PS2, SourceLocation Loc);
 
   bool isMoreSpecializedThanPrimary(VarTemplatePartialSpecializationDecl *T,
                                     sema::TemplateDeductionInfo &Info);
 
   bool isTemplateTemplateParameterAtLeastAsSpecializedAs(
       TemplateParameterList *PParam, TemplateDecl *AArg, SourceLocation Loc);
 
   void MarkUsedTemplateParameters(const Expr *E, bool OnlyDeduced,
                                   unsigned Depth, llvm::SmallBitVector &Used);
 
   void MarkUsedTemplateParameters(const TemplateArgumentList &TemplateArgs,
                                   bool OnlyDeduced,
                                   unsigned Depth,
                                   llvm::SmallBitVector &Used);
   void MarkDeducedTemplateParameters(
                                   const FunctionTemplateDecl *FunctionTemplate,
                                   llvm::SmallBitVector &Deduced) {
     return MarkDeducedTemplateParameters(Context, FunctionTemplate, Deduced);
   }
   static void MarkDeducedTemplateParameters(ASTContext &Ctx,
                                   const FunctionTemplateDecl *FunctionTemplate,
                                   llvm::SmallBitVector &Deduced);
 
   //===--------------------------------------------------------------------===//
   // C++ Template Instantiation
   //
 
   MultiLevelTemplateArgumentList
   getTemplateInstantiationArgs(const NamedDecl *D, bool Final = false,
                                const TemplateArgumentList *Innermost = nullptr,
                                bool RelativeToPrimary = false,
                                const FunctionDecl *Pattern = nullptr,
                                bool ForConstraintInstantiation = false,
                                bool SkipForSpecialization = false);
 
   /// A context in which code is being synthesized (where a source location
   /// alone is not sufficient to identify the context). This covers template
   /// instantiation and various forms of implicitly-generated functions.
   struct CodeSynthesisContext {
     /// The kind of template instantiation we are performing
     enum SynthesisKind {
       /// We are instantiating a template declaration. The entity is
       /// the declaration we're instantiating (e.g., a CXXRecordDecl).
       TemplateInstantiation,
 
       /// We are instantiating a default argument for a template
       /// parameter. The Entity is the template parameter whose argument is
       /// being instantiated, the Template is the template, and the
       /// TemplateArgs/NumTemplateArguments provide the template arguments as
       /// specified.
       DefaultTemplateArgumentInstantiation,
 
       /// We are instantiating a default argument for a function.
       /// The Entity is the ParmVarDecl, and TemplateArgs/NumTemplateArgs
       /// provides the template arguments as specified.
       DefaultFunctionArgumentInstantiation,
 
       /// We are substituting explicit template arguments provided for
       /// a function template. The entity is a FunctionTemplateDecl.
       ExplicitTemplateArgumentSubstitution,
 
       /// We are substituting template argument determined as part of
       /// template argument deduction for either a class template
       /// partial specialization or a function template. The
       /// Entity is either a {Class|Var}TemplatePartialSpecializationDecl or
       /// a TemplateDecl.
       DeducedTemplateArgumentSubstitution,
 
       /// We are substituting into a lambda expression.
       LambdaExpressionSubstitution,
 
       /// We are substituting prior template arguments into a new
       /// template parameter. The template parameter itself is either a
       /// NonTypeTemplateParmDecl or a TemplateTemplateParmDecl.
       PriorTemplateArgumentSubstitution,
 
       /// We are checking the validity of a default template argument that
       /// has been used when naming a template-id.
       DefaultTemplateArgumentChecking,
 
       /// We are computing the exception specification for a defaulted special
       /// member function.
       ExceptionSpecEvaluation,
 
       /// We are instantiating the exception specification for a function
       /// template which was deferred until it was needed.
       ExceptionSpecInstantiation,
 
       /// We are instantiating a requirement of a requires expression.
       RequirementInstantiation,
 
       /// We are checking the satisfaction of a nested requirement of a requires
       /// expression.
       NestedRequirementConstraintsCheck,
 
       /// We are declaring an implicit special member function.
       DeclaringSpecialMember,
 
       /// We are declaring an implicit 'operator==' for a defaulted
       /// 'operator<=>'.
       DeclaringImplicitEqualityComparison,
 
       /// We are defining a synthesized function (such as a defaulted special
       /// member).
       DefiningSynthesizedFunction,
 
       // We are checking the constraints associated with a constrained entity or
       // the constraint expression of a concept. This includes the checks that
       // atomic constraints have the type 'bool' and that they can be constant
       // evaluated.
       ConstraintsCheck,
 
       // We are substituting template arguments into a constraint expression.
       ConstraintSubstitution,
 
       // We are normalizing a constraint expression.
       ConstraintNormalization,
 
       // Instantiating a Requires Expression parameter clause.
       RequirementParameterInstantiation,
 
       // We are substituting into the parameter mapping of an atomic constraint
       // during normalization.
       ParameterMappingSubstitution,
 
       /// We are rewriting a comparison operator in terms of an operator<=>.
       RewritingOperatorAsSpaceship,
 
       /// We are initializing a structured binding.
       InitializingStructuredBinding,
 
       /// We are marking a class as __dllexport.
       MarkingClassDllexported,
 
       /// We are building an implied call from __builtin_dump_struct. The
       /// arguments are in CallArgs.
       BuildingBuiltinDumpStructCall,
 
       /// Added for Template instantiation observation.
       /// Memoization means we are _not_ instantiating a template because
       /// it is already instantiated (but we entered a context where we
       /// would have had to if it was not already instantiated).
       Memoization,
 
       /// We are building deduction guides for a class.
       BuildingDeductionGuides,
     } Kind;
 
     /// Was the enclosing context a non-instantiation SFINAE context?
     bool SavedInNonInstantiationSFINAEContext;
 
     /// The point of instantiation or synthesis within the source code.
     SourceLocation PointOfInstantiation;
 
     /// The entity that is being synthesized.
     Decl *Entity;
 
     /// The template (or partial specialization) in which we are
     /// performing the instantiation, for substitutions of prior template
     /// arguments.
     NamedDecl *Template;
 
     union {
       /// The list of template arguments we are substituting, if they
       /// are not part of the entity.
       const TemplateArgument *TemplateArgs;
 
       /// The list of argument expressions in a synthesized call.
       const Expr *const *CallArgs;
     };
 
     // FIXME: Wrap this union around more members, or perhaps store the
     // kind-specific members in the RAII object owning the context.
     union {
       /// The number of template arguments in TemplateArgs.
       unsigned NumTemplateArgs;
 
       /// The number of expressions in CallArgs.
       unsigned NumCallArgs;
 
       /// The special member being declared or defined.
       CXXSpecialMember SpecialMember;
     };
 
     ArrayRef<TemplateArgument> template_arguments() const {
       assert(Kind != DeclaringSpecialMember);
       return {TemplateArgs, NumTemplateArgs};
     }
 
     /// The template deduction info object associated with the
     /// substitution or checking of explicit or deduced template arguments.
     sema::TemplateDeductionInfo *DeductionInfo;
 
     /// The source range that covers the construct that cause
     /// the instantiation, e.g., the template-id that causes a class
     /// template instantiation.
     SourceRange InstantiationRange;
 
     CodeSynthesisContext()
         : Kind(TemplateInstantiation),
           SavedInNonInstantiationSFINAEContext(false), Entity(nullptr),
           Template(nullptr), TemplateArgs(nullptr), NumTemplateArgs(0),
           DeductionInfo(nullptr) {}
 
     /// Determines whether this template is an actual instantiation
     /// that should be counted toward the maximum instantiation depth.
     bool isInstantiationRecord() const;
   };
 
   /// List of active code synthesis contexts.
   ///
   /// This vector is treated as a stack. As synthesis of one entity requires
   /// synthesis of another, additional contexts are pushed onto the stack.
   SmallVector<CodeSynthesisContext, 16> CodeSynthesisContexts;
 
   /// Specializations whose definitions are currently being instantiated.
   llvm::DenseSet<std::pair<Decl *, unsigned>> InstantiatingSpecializations;
 
   /// Non-dependent types used in templates that have already been instantiated
   /// by some template instantiation.
   llvm::DenseSet<QualType> InstantiatedNonDependentTypes;
 
   /// Extra modules inspected when performing a lookup during a template
   /// instantiation. Computed lazily.
   SmallVector<Module*, 16> CodeSynthesisContextLookupModules;
 
   /// Cache of additional modules that should be used for name lookup
   /// within the current template instantiation. Computed lazily; use
   /// getLookupModules() to get a complete set.
   llvm::DenseSet<Module*> LookupModulesCache;
 
   /// Get the set of additional modules that should be checked during
   /// name lookup. A module and its imports become visible when instanting a
   /// template defined within it.
   llvm::DenseSet<Module*> &getLookupModules();
 
   /// Map from the most recent declaration of a namespace to the most
   /// recent visible declaration of that namespace.
   llvm::DenseMap<NamedDecl*, NamedDecl*> VisibleNamespaceCache;
 
   /// Whether we are in a SFINAE context that is not associated with
   /// template instantiation.
   ///
   /// This is used when setting up a SFINAE trap (\c see SFINAETrap) outside
   /// of a template instantiation or template argument deduction.
   bool InNonInstantiationSFINAEContext;
 
   /// The number of \p CodeSynthesisContexts that are not template
   /// instantiations and, therefore, should not be counted as part of the
   /// instantiation depth.
   ///
   /// When the instantiation depth reaches the user-configurable limit
   /// \p LangOptions::InstantiationDepth we will abort instantiation.
   // FIXME: Should we have a similar limit for other forms of synthesis?
   unsigned NonInstantiationEntries;
 
   /// The depth of the context stack at the point when the most recent
   /// error or warning was produced.
   ///
   /// This value is used to suppress printing of redundant context stacks
   /// when there are multiple errors or warnings in the same instantiation.
   // FIXME: Does this belong in Sema? It's tough to implement it anywhere else.
   unsigned LastEmittedCodeSynthesisContextDepth = 0;
 
   /// The template instantiation callbacks to trace or track
   /// instantiations (objects can be chained).
   ///
   /// This callbacks is used to print, trace or track template
   /// instantiations as they are being constructed.
   std::vector<std::unique_ptr<TemplateInstantiationCallback>>
       TemplateInstCallbacks;
 
   /// The current index into pack expansion arguments that will be
   /// used for substitution of parameter packs.
   ///
   /// The pack expansion index will be -1 to indicate that parameter packs
   /// should be instantiated as themselves. Otherwise, the index specifies
   /// which argument within the parameter pack will be used for substitution.
   int ArgumentPackSubstitutionIndex;
 
   /// RAII object used to change the argument pack substitution index
   /// within a \c Sema object.
   ///
   /// See \c ArgumentPackSubstitutionIndex for more information.
   class ArgumentPackSubstitutionIndexRAII {
     Sema &Self;
     int OldSubstitutionIndex;
 
   public:
     ArgumentPackSubstitutionIndexRAII(Sema &Self, int NewSubstitutionIndex)
       : Self(Self), OldSubstitutionIndex(Self.ArgumentPackSubstitutionIndex) {
       Self.ArgumentPackSubstitutionIndex = NewSubstitutionIndex;
     }
 
     ~ArgumentPackSubstitutionIndexRAII() {
       Self.ArgumentPackSubstitutionIndex = OldSubstitutionIndex;
     }
   };
 
   friend class ArgumentPackSubstitutionRAII;
 
   /// For each declaration that involved template argument deduction, the
   /// set of diagnostics that were suppressed during that template argument
   /// deduction.
   ///
   /// FIXME: Serialize this structure to the AST file.
   typedef llvm::DenseMap<Decl *, SmallVector<PartialDiagnosticAt, 1> >
     SuppressedDiagnosticsMap;
   SuppressedDiagnosticsMap SuppressedDiagnostics;
 
   /// A stack object to be created when performing template
   /// instantiation.
   ///
   /// Construction of an object of type \c InstantiatingTemplate
   /// pushes the current instantiation onto the stack of active
   /// instantiations. If the size of this stack exceeds the maximum
   /// number of recursive template instantiations, construction
   /// produces an error and evaluates true.
   ///
   /// Destruction of this object will pop the named instantiation off
   /// the stack.
   struct InstantiatingTemplate {
     /// Note that we are instantiating a class template,
     /// function template, variable template, alias template,
     /// or a member thereof.
     InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
                           Decl *Entity,
                           SourceRange InstantiationRange = SourceRange());
 
     struct ExceptionSpecification {};
     /// Note that we are instantiating an exception specification
     /// of a function template.
     InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
                           FunctionDecl *Entity, ExceptionSpecification,
                           SourceRange InstantiationRange = SourceRange());
 
     /// Note that we are instantiating a default argument in a
     /// template-id.
     InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
                           TemplateParameter Param, TemplateDecl *Template,
                           ArrayRef<TemplateArgument> TemplateArgs,
                           SourceRange InstantiationRange = SourceRange());
 
     /// Note that we are substituting either explicitly-specified or
     /// deduced template arguments during function template argument deduction.
     InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
                           FunctionTemplateDecl *FunctionTemplate,
                           ArrayRef<TemplateArgument> TemplateArgs,
                           CodeSynthesisContext::SynthesisKind Kind,
                           sema::TemplateDeductionInfo &DeductionInfo,
                           SourceRange InstantiationRange = SourceRange());
 
     /// Note that we are instantiating as part of template
     /// argument deduction for a class template declaration.
     InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
                           TemplateDecl *Template,
                           ArrayRef<TemplateArgument> TemplateArgs,
                           sema::TemplateDeductionInfo &DeductionInfo,
                           SourceRange InstantiationRange = SourceRange());
 
     /// Note that we are instantiating as part of template
     /// argument deduction for a class template partial
     /// specialization.
     InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
                           ClassTemplatePartialSpecializationDecl *PartialSpec,
                           ArrayRef<TemplateArgument> TemplateArgs,
                           sema::TemplateDeductionInfo &DeductionInfo,
                           SourceRange InstantiationRange = SourceRange());
 
     /// Note that we are instantiating as part of template
     /// argument deduction for a variable template partial
     /// specialization.
     InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
                           VarTemplatePartialSpecializationDecl *PartialSpec,
                           ArrayRef<TemplateArgument> TemplateArgs,
                           sema::TemplateDeductionInfo &DeductionInfo,
                           SourceRange InstantiationRange = SourceRange());
 
     /// Note that we are instantiating a default argument for a function
     /// parameter.
     InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
                           ParmVarDecl *Param,
                           ArrayRef<TemplateArgument> TemplateArgs,
                           SourceRange InstantiationRange = SourceRange());
 
     /// Note that we are substituting prior template arguments into a
     /// non-type parameter.
     InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
                           NamedDecl *Template,
                           NonTypeTemplateParmDecl *Param,
                           ArrayRef<TemplateArgument> TemplateArgs,
                           SourceRange InstantiationRange);
 
     /// Note that we are substituting prior template arguments into a
     /// template template parameter.
     InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
                           NamedDecl *Template,
                           TemplateTemplateParmDecl *Param,
                           ArrayRef<TemplateArgument> TemplateArgs,
                           SourceRange InstantiationRange);
 
     /// Note that we are checking the default template argument
     /// against the template parameter for a given template-id.
     InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
                           TemplateDecl *Template,
                           NamedDecl *Param,
                           ArrayRef<TemplateArgument> TemplateArgs,
                           SourceRange InstantiationRange);
 
     struct ConstraintsCheck {};
     /// \brief Note that we are checking the constraints associated with some
     /// constrained entity (a concept declaration or a template with associated
     /// constraints).
     InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
                           ConstraintsCheck, NamedDecl *Template,
                           ArrayRef<TemplateArgument> TemplateArgs,
                           SourceRange InstantiationRange);
 
     struct ConstraintSubstitution {};
     /// \brief Note that we are checking a constraint expression associated
     /// with a template declaration or as part of the satisfaction check of a
     /// concept.
     InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
                           ConstraintSubstitution, NamedDecl *Template,
                           sema::TemplateDeductionInfo &DeductionInfo,
                           SourceRange InstantiationRange);
 
     struct ConstraintNormalization {};
     /// \brief Note that we are normalizing a constraint expression.
     InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
                           ConstraintNormalization, NamedDecl *Template,
                           SourceRange InstantiationRange);
 
     struct ParameterMappingSubstitution {};
     /// \brief Note that we are subtituting into the parameter mapping of an
     /// atomic constraint during constraint normalization.
     InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
                           ParameterMappingSubstitution, NamedDecl *Template,
                           SourceRange InstantiationRange);
 
     /// \brief Note that we are substituting template arguments into a part of
     /// a requirement of a requires expression.
     InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
                           concepts::Requirement *Req,
                           sema::TemplateDeductionInfo &DeductionInfo,
                           SourceRange InstantiationRange = SourceRange());
 
     /// \brief Note that we are checking the satisfaction of the constraint
     /// expression inside of a nested requirement.
     InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
                           concepts::NestedRequirement *Req, ConstraintsCheck,
                           SourceRange InstantiationRange = SourceRange());
 
     /// \brief Note that we are checking a requires clause.
     InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
                           const RequiresExpr *E,
                           sema::TemplateDeductionInfo &DeductionInfo,
                           SourceRange InstantiationRange);
 
     struct BuildingDeductionGuidesTag {};
     /// \brief Note that we are building deduction guides.
     InstantiatingTemplate(Sema &SemaRef, SourceLocation PointOfInstantiation,
                           TemplateDecl *Entity, BuildingDeductionGuidesTag,
                           SourceRange InstantiationRange = SourceRange());
 
     /// Note that we have finished instantiating this template.
     void Clear();
 
     ~InstantiatingTemplate() { Clear(); }
 
     /// Determines whether we have exceeded the maximum
     /// recursive template instantiations.
     bool isInvalid() const { return Invalid; }
 
     /// Determine whether we are already instantiating this
     /// specialization in some surrounding active instantiation.
     bool isAlreadyInstantiating() const { return AlreadyInstantiating; }
 
   private:
     Sema &SemaRef;
     bool Invalid;
     bool AlreadyInstantiating;
     bool CheckInstantiationDepth(SourceLocation PointOfInstantiation,
                                  SourceRange InstantiationRange);
 
     InstantiatingTemplate(
         Sema &SemaRef, CodeSynthesisContext::SynthesisKind Kind,
         SourceLocation PointOfInstantiation, SourceRange InstantiationRange,
         Decl *Entity, NamedDecl *Template = nullptr,
         ArrayRef<TemplateArgument> TemplateArgs = std::nullopt,
         sema::TemplateDeductionInfo *DeductionInfo = nullptr);
 
     InstantiatingTemplate(const InstantiatingTemplate&) = delete;
 
     InstantiatingTemplate&
     operator=(const InstantiatingTemplate&) = delete;
   };
 
   void pushCodeSynthesisContext(CodeSynthesisContext Ctx);
   void popCodeSynthesisContext();
 
   /// Determine whether we are currently performing template instantiation.
   bool inTemplateInstantiation() const {
     return CodeSynthesisContexts.size() > NonInstantiationEntries;
   }
 
   void PrintContextStack() {
     if (!CodeSynthesisContexts.empty() &&
         CodeSynthesisContexts.size() != LastEmittedCodeSynthesisContextDepth) {
       PrintInstantiationStack();
       LastEmittedCodeSynthesisContextDepth = CodeSynthesisContexts.size();
     }
     if (PragmaAttributeCurrentTargetDecl)
       PrintPragmaAttributeInstantiationPoint();
   }
   void PrintInstantiationStack();
 
   void PrintPragmaAttributeInstantiationPoint();
 
   /// Determines whether we are currently in a context where
   /// template argument substitution failures are not considered
   /// errors.
   ///
   /// \returns An empty \c Optional if we're not in a SFINAE context.
   /// Otherwise, contains a pointer that, if non-NULL, contains the nearest
   /// template-deduction context object, which can be used to capture
   /// diagnostics that will be suppressed.
   std::optional<sema::TemplateDeductionInfo *> isSFINAEContext() const;
 
   /// Determines whether we are currently in a context that
   /// is not evaluated as per C++ [expr] p5.
   bool isUnevaluatedContext() const {
     assert(!ExprEvalContexts.empty() &&
            "Must be in an expression evaluation context");
     return ExprEvalContexts.back().isUnevaluated();
   }
 
   bool isConstantEvaluatedContext() const {
     assert(!ExprEvalContexts.empty() &&
            "Must be in an expression evaluation context");
     return ExprEvalContexts.back().isConstantEvaluated();
   }
 
   bool isImmediateFunctionContext() const {
     assert(!ExprEvalContexts.empty() &&
            "Must be in an expression evaluation context");
     return ExprEvalContexts.back().isImmediateFunctionContext();
   }
 
   bool isCheckingDefaultArgumentOrInitializer() const {
     assert(!ExprEvalContexts.empty() &&
            "Must be in an expression evaluation context");
     const ExpressionEvaluationContextRecord &Ctx = ExprEvalContexts.back();
     return (Ctx.Context ==
             ExpressionEvaluationContext::PotentiallyEvaluatedIfUsed) ||
            Ctx.IsCurrentlyCheckingDefaultArgumentOrInitializer;
   }
 
   std::optional<ExpressionEvaluationContextRecord::InitializationContext>
   InnermostDeclarationWithDelayedImmediateInvocations() const {
     assert(!ExprEvalContexts.empty() &&
            "Must be in an expression evaluation context");
     for (const auto &Ctx : llvm::reverse(ExprEvalContexts)) {
       if (Ctx.Context == ExpressionEvaluationContext::PotentiallyEvaluated &&
           Ctx.DelayedDefaultInitializationContext)
         return Ctx.DelayedDefaultInitializationContext;
       if (Ctx.isConstantEvaluated() || Ctx.isImmediateFunctionContext() ||
           Ctx.isUnevaluated())
         break;
     }
     return std::nullopt;
   }
 
   std::optional<ExpressionEvaluationContextRecord::InitializationContext>
   OutermostDeclarationWithDelayedImmediateInvocations() const {
     assert(!ExprEvalContexts.empty() &&
            "Must be in an expression evaluation context");
     std::optional<ExpressionEvaluationContextRecord::InitializationContext> Res;
     for (auto &Ctx : llvm::reverse(ExprEvalContexts)) {
       if (Ctx.Context == ExpressionEvaluationContext::PotentiallyEvaluated &&
           !Ctx.DelayedDefaultInitializationContext && Res)
         break;
       if (Ctx.isConstantEvaluated() || Ctx.isImmediateFunctionContext() ||
           Ctx.isUnevaluated())
         break;
       Res = Ctx.DelayedDefaultInitializationContext;
     }
     return Res;
   }
 
   /// RAII class used to determine whether SFINAE has
   /// trapped any errors that occur during template argument
   /// deduction.
   class SFINAETrap {
     Sema &SemaRef;
     unsigned PrevSFINAEErrors;
     bool PrevInNonInstantiationSFINAEContext;
     bool PrevAccessCheckingSFINAE;
     bool PrevLastDiagnosticIgnored;
 
   public:
     explicit SFINAETrap(Sema &SemaRef, bool AccessCheckingSFINAE = false)
       : SemaRef(SemaRef), PrevSFINAEErrors(SemaRef.NumSFINAEErrors),
         PrevInNonInstantiationSFINAEContext(
                                       SemaRef.InNonInstantiationSFINAEContext),
         PrevAccessCheckingSFINAE(SemaRef.AccessCheckingSFINAE),
         PrevLastDiagnosticIgnored(
             SemaRef.getDiagnostics().isLastDiagnosticIgnored())
     {
       if (!SemaRef.isSFINAEContext())
         SemaRef.InNonInstantiationSFINAEContext = true;
       SemaRef.AccessCheckingSFINAE = AccessCheckingSFINAE;
     }
 
     ~SFINAETrap() {
       SemaRef.NumSFINAEErrors = PrevSFINAEErrors;
       SemaRef.InNonInstantiationSFINAEContext
         = PrevInNonInstantiationSFINAEContext;
       SemaRef.AccessCheckingSFINAE = PrevAccessCheckingSFINAE;
       SemaRef.getDiagnostics().setLastDiagnosticIgnored(
           PrevLastDiagnosticIgnored);
     }
 
     /// Determine whether any SFINAE errors have been trapped.
     bool hasErrorOccurred() const {
       return SemaRef.NumSFINAEErrors > PrevSFINAEErrors;
     }
   };
 
   /// RAII class used to indicate that we are performing provisional
   /// semantic analysis to determine the validity of a construct, so
   /// typo-correction and diagnostics in the immediate context (not within
   /// implicitly-instantiated templates) should be suppressed.
   class TentativeAnalysisScope {
     Sema &SemaRef;
     // FIXME: Using a SFINAETrap for this is a hack.
     SFINAETrap Trap;
     bool PrevDisableTypoCorrection;
   public:
     explicit TentativeAnalysisScope(Sema &SemaRef)
         : SemaRef(SemaRef), Trap(SemaRef, true),
           PrevDisableTypoCorrection(SemaRef.DisableTypoCorrection) {
       SemaRef.DisableTypoCorrection = true;
     }
     ~TentativeAnalysisScope() {
       SemaRef.DisableTypoCorrection = PrevDisableTypoCorrection;
     }
   };
 
   /// The current instantiation scope used to store local
   /// variables.
   LocalInstantiationScope *CurrentInstantiationScope;
 
   /// Tracks whether we are in a context where typo correction is
   /// disabled.
   bool DisableTypoCorrection;
 
   /// The number of typos corrected by CorrectTypo.
   unsigned TyposCorrected;
 
   typedef llvm::SmallSet<SourceLocation, 2> SrcLocSet;
   typedef llvm::DenseMap<IdentifierInfo *, SrcLocSet> IdentifierSourceLocations;
 
   /// A cache containing identifiers for which typo correction failed and
   /// their locations, so that repeated attempts to correct an identifier in a
   /// given location are ignored if typo correction already failed for it.
   IdentifierSourceLocations TypoCorrectionFailures;
 
   /// Worker object for performing CFG-based warnings.
   sema::AnalysisBasedWarnings AnalysisWarnings;
   threadSafety::BeforeSet *ThreadSafetyDeclCache;
 
   /// An entity for which implicit template instantiation is required.
   ///
   /// The source location associated with the declaration is the first place in
   /// the source code where the declaration was "used". It is not necessarily
   /// the point of instantiation (which will be either before or after the
   /// namespace-scope declaration that triggered this implicit instantiation),
   /// However, it is the location that diagnostics should generally refer to,
   /// because users will need to know what code triggered the instantiation.
   typedef std::pair<ValueDecl *, SourceLocation> PendingImplicitInstantiation;
 
   /// The queue of implicit template instantiations that are required
   /// but have not yet been performed.
   std::deque<PendingImplicitInstantiation> PendingInstantiations;
 
   /// Queue of implicit template instantiations that cannot be performed
   /// eagerly.
   SmallVector<PendingImplicitInstantiation, 1> LateParsedInstantiations;
 
   SmallVector<SmallVector<VTableUse, 16>, 8> SavedVTableUses;
   SmallVector<std::deque<PendingImplicitInstantiation>, 8>
       SavedPendingInstantiations;
 
   class GlobalEagerInstantiationScope {
   public:
     GlobalEagerInstantiationScope(Sema &S, bool Enabled)
         : S(S), Enabled(Enabled) {
       if (!Enabled) return;
 
       S.SavedPendingInstantiations.emplace_back();
       S.SavedPendingInstantiations.back().swap(S.PendingInstantiations);
 
       S.SavedVTableUses.emplace_back();
       S.SavedVTableUses.back().swap(S.VTableUses);
     }
 
     void perform() {
       if (Enabled) {
         S.DefineUsedVTables();
         S.PerformPendingInstantiations();
       }
     }
 
     ~GlobalEagerInstantiationScope() {
       if (!Enabled) return;
 
       // Restore the set of pending vtables.
       assert(S.VTableUses.empty() &&
              "VTableUses should be empty before it is discarded.");
       S.VTableUses.swap(S.SavedVTableUses.back());
       S.SavedVTableUses.pop_back();
 
       // Restore the set of pending implicit instantiations.
       if (S.TUKind != TU_Prefix || !S.LangOpts.PCHInstantiateTemplates) {
         assert(S.PendingInstantiations.empty() &&
                "PendingInstantiations should be empty before it is discarded.");
         S.PendingInstantiations.swap(S.SavedPendingInstantiations.back());
         S.SavedPendingInstantiations.pop_back();
       } else {
         // Template instantiations in the PCH may be delayed until the TU.
         S.PendingInstantiations.swap(S.SavedPendingInstantiations.back());
         S.PendingInstantiations.insert(
             S.PendingInstantiations.end(),
             S.SavedPendingInstantiations.back().begin(),
             S.SavedPendingInstantiations.back().end());
         S.SavedPendingInstantiations.pop_back();
       }
     }
 
   private:
     Sema &S;
     bool Enabled;
   };
 
   /// The queue of implicit template instantiations that are required
   /// and must be performed within the current local scope.
   ///
   /// This queue is only used for member functions of local classes in
   /// templates, which must be instantiated in the same scope as their
   /// enclosing function, so that they can reference function-local
   /// types, static variables, enumerators, etc.
   std::deque<PendingImplicitInstantiation> PendingLocalImplicitInstantiations;
 
   class LocalEagerInstantiationScope {
   public:
     LocalEagerInstantiationScope(Sema &S) : S(S) {
       SavedPendingLocalImplicitInstantiations.swap(
           S.PendingLocalImplicitInstantiations);
     }
 
     void perform() { S.PerformPendingInstantiations(/*LocalOnly=*/true); }
 
     ~LocalEagerInstantiationScope() {
       assert(S.PendingLocalImplicitInstantiations.empty() &&
              "there shouldn't be any pending local implicit instantiations");
       SavedPendingLocalImplicitInstantiations.swap(
           S.PendingLocalImplicitInstantiations);
     }
 
   private:
     Sema &S;
     std::deque<PendingImplicitInstantiation>
         SavedPendingLocalImplicitInstantiations;
   };
 
   /// A helper class for building up ExtParameterInfos.
   class ExtParameterInfoBuilder {
     SmallVector<FunctionProtoType::ExtParameterInfo, 16> Infos;
     bool HasInteresting = false;
 
   public:
     /// Set the ExtParameterInfo for the parameter at the given index,
     ///
     void set(unsigned index, FunctionProtoType::ExtParameterInfo info) {
       assert(Infos.size() <= index);
       Infos.resize(index);
       Infos.push_back(info);
 
       if (!HasInteresting)
         HasInteresting = (info != FunctionProtoType::ExtParameterInfo());
     }
 
     /// Return a pointer (suitable for setting in an ExtProtoInfo) to the
     /// ExtParameterInfo array we've built up.
     const FunctionProtoType::ExtParameterInfo *
     getPointerOrNull(unsigned numParams) {
       if (!HasInteresting) return nullptr;
       Infos.resize(numParams);
       return Infos.data();
     }
   };
 
   void PerformPendingInstantiations(bool LocalOnly = false);
 
   TypeSourceInfo *SubstType(TypeSourceInfo *T,
                             const MultiLevelTemplateArgumentList &TemplateArgs,
                             SourceLocation Loc, DeclarationName Entity,
                             bool AllowDeducedTST = false);
 
   QualType SubstType(QualType T,
                      const MultiLevelTemplateArgumentList &TemplateArgs,
                      SourceLocation Loc, DeclarationName Entity);
 
   TypeSourceInfo *SubstType(TypeLoc TL,
                             const MultiLevelTemplateArgumentList &TemplateArgs,
                             SourceLocation Loc, DeclarationName Entity);
 
   TypeSourceInfo *SubstFunctionDeclType(
       TypeSourceInfo *T, const MultiLevelTemplateArgumentList &TemplateArgs,
       SourceLocation Loc, DeclarationName Entity, CXXRecordDecl *ThisContext,
       Qualifiers ThisTypeQuals, bool EvaluateConstraints = true);
   void SubstExceptionSpec(FunctionDecl *New, const FunctionProtoType *Proto,
                           const MultiLevelTemplateArgumentList &Args);
   bool SubstExceptionSpec(SourceLocation Loc,
                           FunctionProtoType::ExceptionSpecInfo &ESI,
                           SmallVectorImpl<QualType> &ExceptionStorage,
                           const MultiLevelTemplateArgumentList &Args);
   ParmVarDecl *
   SubstParmVarDecl(ParmVarDecl *D,
                    const MultiLevelTemplateArgumentList &TemplateArgs,
                    int indexAdjustment, std::optional<unsigned> NumExpansions,
                    bool ExpectParameterPack, bool EvaluateConstraints = true);
   bool SubstParmTypes(SourceLocation Loc, ArrayRef<ParmVarDecl *> Params,
                       const FunctionProtoType::ExtParameterInfo *ExtParamInfos,
                       const MultiLevelTemplateArgumentList &TemplateArgs,
                       SmallVectorImpl<QualType> &ParamTypes,
                       SmallVectorImpl<ParmVarDecl *> *OutParams,
                       ExtParameterInfoBuilder &ParamInfos);
   bool SubstDefaultArgument(SourceLocation Loc, ParmVarDecl *Param,
                             const MultiLevelTemplateArgumentList &TemplateArgs,
                             bool ForCallExpr = false);
   ExprResult SubstExpr(Expr *E,
                        const MultiLevelTemplateArgumentList &TemplateArgs);
 
   // A RAII type used by the TemplateDeclInstantiator and TemplateInstantiator
   // to disable constraint evaluation, then restore the state.
   template <typename InstTy> struct ConstraintEvalRAII {
     InstTy &TI;
     bool OldValue;
 
     ConstraintEvalRAII(InstTy &TI)
         : TI(TI), OldValue(TI.getEvaluateConstraints()) {
       TI.setEvaluateConstraints(false);
     }
     ~ConstraintEvalRAII() { TI.setEvaluateConstraints(OldValue); }
   };
 
   // Unlike the above, this evaluates constraints, which should only happen at
   // 'constraint checking' time.
   ExprResult
   SubstConstraintExpr(Expr *E,
                       const MultiLevelTemplateArgumentList &TemplateArgs);
 
   /// Substitute the given template arguments into a list of
   /// expressions, expanding pack expansions if required.
   ///
   /// \param Exprs The list of expressions to substitute into.
   ///
   /// \param IsCall Whether this is some form of call, in which case
   /// default arguments will be dropped.
   ///
   /// \param TemplateArgs The set of template arguments to substitute.
   ///
   /// \param Outputs Will receive all of the substituted arguments.
   ///
   /// \returns true if an error occurred, false otherwise.
   bool SubstExprs(ArrayRef<Expr *> Exprs, bool IsCall,
                   const MultiLevelTemplateArgumentList &TemplateArgs,
                   SmallVectorImpl<Expr *> &Outputs);
 
   StmtResult SubstStmt(Stmt *S,
                        const MultiLevelTemplateArgumentList &TemplateArgs);
 
   TemplateParameterList *
   SubstTemplateParams(TemplateParameterList *Params, DeclContext *Owner,
                       const MultiLevelTemplateArgumentList &TemplateArgs,
                       bool EvaluateConstraints = true);
 
   bool
   SubstTemplateArguments(ArrayRef<TemplateArgumentLoc> Args,
                          const MultiLevelTemplateArgumentList &TemplateArgs,
                          TemplateArgumentListInfo &Outputs);
 
   Decl *SubstDecl(Decl *D, DeclContext *Owner,
                   const MultiLevelTemplateArgumentList &TemplateArgs);
 
   /// Substitute the name and return type of a defaulted 'operator<=>' to form
   /// an implicit 'operator=='.
   FunctionDecl *SubstSpaceshipAsEqualEqual(CXXRecordDecl *RD,
                                            FunctionDecl *Spaceship);
 
   ExprResult SubstInitializer(Expr *E,
                        const MultiLevelTemplateArgumentList &TemplateArgs,
                        bool CXXDirectInit);
 
   bool
   SubstBaseSpecifiers(CXXRecordDecl *Instantiation,
                       CXXRecordDecl *Pattern,
                       const MultiLevelTemplateArgumentList &TemplateArgs);
 
   bool
   InstantiateClass(SourceLocation PointOfInstantiation,
                    CXXRecordDecl *Instantiation, CXXRecordDecl *Pattern,
                    const MultiLevelTemplateArgumentList &TemplateArgs,
                    TemplateSpecializationKind TSK,
                    bool Complain = true);
 
   bool InstantiateEnum(SourceLocation PointOfInstantiation,
                        EnumDecl *Instantiation, EnumDecl *Pattern,
                        const MultiLevelTemplateArgumentList &TemplateArgs,
                        TemplateSpecializationKind TSK);
 
   bool InstantiateInClassInitializer(
       SourceLocation PointOfInstantiation, FieldDecl *Instantiation,
       FieldDecl *Pattern, const MultiLevelTemplateArgumentList &TemplateArgs);
 
   struct LateInstantiatedAttribute {
     const Attr *TmplAttr;
     LocalInstantiationScope *Scope;
     Decl *NewDecl;
 
     LateInstantiatedAttribute(const Attr *A, LocalInstantiationScope *S,
                               Decl *D)
       : TmplAttr(A), Scope(S), NewDecl(D)
     { }
   };
   typedef SmallVector<LateInstantiatedAttribute, 16> LateInstantiatedAttrVec;
 
   void InstantiateAttrs(const MultiLevelTemplateArgumentList &TemplateArgs,
                         const Decl *Pattern, Decl *Inst,
                         LateInstantiatedAttrVec *LateAttrs = nullptr,
                         LocalInstantiationScope *OuterMostScope = nullptr);
   void updateAttrsForLateParsedTemplate(const Decl *Pattern, Decl *Inst);
 
   void
   InstantiateAttrsForDecl(const MultiLevelTemplateArgumentList &TemplateArgs,
                           const Decl *Pattern, Decl *Inst,
                           LateInstantiatedAttrVec *LateAttrs = nullptr,
                           LocalInstantiationScope *OuterMostScope = nullptr);
 
   void InstantiateDefaultCtorDefaultArgs(CXXConstructorDecl *Ctor);
 
   bool usesPartialOrExplicitSpecialization(
       SourceLocation Loc, ClassTemplateSpecializationDecl *ClassTemplateSpec);
 
   bool
   InstantiateClassTemplateSpecialization(SourceLocation PointOfInstantiation,
                            ClassTemplateSpecializationDecl *ClassTemplateSpec,
                            TemplateSpecializationKind TSK,
                            bool Complain = true);
 
   void InstantiateClassMembers(SourceLocation PointOfInstantiation,
                                CXXRecordDecl *Instantiation,
                             const MultiLevelTemplateArgumentList &TemplateArgs,
                                TemplateSpecializationKind TSK);
 
   void InstantiateClassTemplateSpecializationMembers(
                                           SourceLocation PointOfInstantiation,
                            ClassTemplateSpecializationDecl *ClassTemplateSpec,
                                                 TemplateSpecializationKind TSK);
 
   NestedNameSpecifierLoc
   SubstNestedNameSpecifierLoc(NestedNameSpecifierLoc NNS,
                            const MultiLevelTemplateArgumentList &TemplateArgs);
 
   DeclarationNameInfo
   SubstDeclarationNameInfo(const DeclarationNameInfo &NameInfo,
                            const MultiLevelTemplateArgumentList &TemplateArgs);
   TemplateName
   SubstTemplateName(NestedNameSpecifierLoc QualifierLoc, TemplateName Name,
                     SourceLocation Loc,
                     const MultiLevelTemplateArgumentList &TemplateArgs);
 
   bool SubstTypeConstraint(TemplateTypeParmDecl *Inst, const TypeConstraint *TC,
                            const MultiLevelTemplateArgumentList &TemplateArgs,
                            bool EvaluateConstraint);
 
   bool InstantiateDefaultArgument(SourceLocation CallLoc, FunctionDecl *FD,
                                   ParmVarDecl *Param);
   void InstantiateExceptionSpec(SourceLocation PointOfInstantiation,
                                 FunctionDecl *Function);
   bool CheckInstantiatedFunctionTemplateConstraints(
       SourceLocation PointOfInstantiation, FunctionDecl *Decl,
       ArrayRef<TemplateArgument> TemplateArgs,
       ConstraintSatisfaction &Satisfaction);
   FunctionDecl *InstantiateFunctionDeclaration(FunctionTemplateDecl *FTD,
                                                const TemplateArgumentList *Args,
                                                SourceLocation Loc);
   void InstantiateFunctionDefinition(SourceLocation PointOfInstantiation,
                                      FunctionDecl *Function,
                                      bool Recursive = false,
                                      bool DefinitionRequired = false,
                                      bool AtEndOfTU = false);
   VarTemplateSpecializationDecl *BuildVarTemplateInstantiation(
       VarTemplateDecl *VarTemplate, VarDecl *FromVar,
       const TemplateArgumentList &TemplateArgList,
       const TemplateArgumentListInfo &TemplateArgsInfo,
       SmallVectorImpl<TemplateArgument> &Converted,
       SourceLocation PointOfInstantiation,
       LateInstantiatedAttrVec *LateAttrs = nullptr,
       LocalInstantiationScope *StartingScope = nullptr);
   VarTemplateSpecializationDecl *CompleteVarTemplateSpecializationDecl(
       VarTemplateSpecializationDecl *VarSpec, VarDecl *PatternDecl,
       const MultiLevelTemplateArgumentList &TemplateArgs);
   void
   BuildVariableInstantiation(VarDecl *NewVar, VarDecl *OldVar,
                              const MultiLevelTemplateArgumentList &TemplateArgs,
                              LateInstantiatedAttrVec *LateAttrs,
                              DeclContext *Owner,
                              LocalInstantiationScope *StartingScope,
                              bool InstantiatingVarTemplate = false,
                              VarTemplateSpecializationDecl *PrevVTSD = nullptr);
 
   void InstantiateVariableInitializer(
       VarDecl *Var, VarDecl *OldVar,
       const MultiLevelTemplateArgumentList &TemplateArgs);
   void InstantiateVariableDefinition(SourceLocation PointOfInstantiation,
                                      VarDecl *Var, bool Recursive = false,
                                      bool DefinitionRequired = false,
                                      bool AtEndOfTU = false);
 
   void InstantiateMemInitializers(CXXConstructorDecl *New,
                                   const CXXConstructorDecl *Tmpl,
                             const MultiLevelTemplateArgumentList &TemplateArgs);
 
   NamedDecl *FindInstantiatedDecl(SourceLocation Loc, NamedDecl *D,
                           const MultiLevelTemplateArgumentList &TemplateArgs,
                           bool FindingInstantiatedContext = false);
   DeclContext *FindInstantiatedContext(SourceLocation Loc, DeclContext *DC,
                           const MultiLevelTemplateArgumentList &TemplateArgs);
 
   // Objective-C declarations.
   enum ObjCContainerKind {
     OCK_None = -1,
     OCK_Interface = 0,
     OCK_Protocol,
     OCK_Category,
     OCK_ClassExtension,
     OCK_Implementation,
     OCK_CategoryImplementation
   };
   ObjCContainerKind getObjCContainerKind() const;
 
   DeclResult actOnObjCTypeParam(Scope *S,
                                 ObjCTypeParamVariance variance,
                                 SourceLocation varianceLoc,
                                 unsigned index,
                                 IdentifierInfo *paramName,
                                 SourceLocation paramLoc,
                                 SourceLocation colonLoc,
                                 ParsedType typeBound);
 
   ObjCTypeParamList *actOnObjCTypeParamList(Scope *S, SourceLocation lAngleLoc,
                                             ArrayRef<Decl *> typeParams,
                                             SourceLocation rAngleLoc);
   void popObjCTypeParamList(Scope *S, ObjCTypeParamList *typeParamList);
 
   ObjCInterfaceDecl *ActOnStartClassInterface(
       Scope *S, SourceLocation AtInterfaceLoc, IdentifierInfo *ClassName,
       SourceLocation ClassLoc, ObjCTypeParamList *typeParamList,
       IdentifierInfo *SuperName, SourceLocation SuperLoc,
       ArrayRef<ParsedType> SuperTypeArgs, SourceRange SuperTypeArgsRange,
       Decl *const *ProtoRefs, unsigned NumProtoRefs,
       const SourceLocation *ProtoLocs, SourceLocation EndProtoLoc,
       const ParsedAttributesView &AttrList, SkipBodyInfo *SkipBody);
 
   void ActOnSuperClassOfClassInterface(Scope *S,
                                        SourceLocation AtInterfaceLoc,
                                        ObjCInterfaceDecl *IDecl,
                                        IdentifierInfo *ClassName,
                                        SourceLocation ClassLoc,
                                        IdentifierInfo *SuperName,
                                        SourceLocation SuperLoc,
                                        ArrayRef<ParsedType> SuperTypeArgs,
                                        SourceRange SuperTypeArgsRange);
 
   void ActOnTypedefedProtocols(SmallVectorImpl<Decl *> &ProtocolRefs,
                                SmallVectorImpl<SourceLocation> &ProtocolLocs,
                                IdentifierInfo *SuperName,
                                SourceLocation SuperLoc);
 
   Decl *ActOnCompatibilityAlias(
                     SourceLocation AtCompatibilityAliasLoc,
                     IdentifierInfo *AliasName,  SourceLocation AliasLocation,
                     IdentifierInfo *ClassName, SourceLocation ClassLocation);
 
   bool CheckForwardProtocolDeclarationForCircularDependency(
     IdentifierInfo *PName,
     SourceLocation &PLoc, SourceLocation PrevLoc,
     const ObjCList<ObjCProtocolDecl> &PList);
 
   ObjCProtocolDecl *ActOnStartProtocolInterface(
       SourceLocation AtProtoInterfaceLoc, IdentifierInfo *ProtocolName,
       SourceLocation ProtocolLoc, Decl *const *ProtoRefNames,
       unsigned NumProtoRefs, const SourceLocation *ProtoLocs,
       SourceLocation EndProtoLoc, const ParsedAttributesView &AttrList,
       SkipBodyInfo *SkipBody);
 
   ObjCCategoryDecl *ActOnStartCategoryInterface(
       SourceLocation AtInterfaceLoc, IdentifierInfo *ClassName,
       SourceLocation ClassLoc, ObjCTypeParamList *typeParamList,
       IdentifierInfo *CategoryName, SourceLocation CategoryLoc,
       Decl *const *ProtoRefs, unsigned NumProtoRefs,
       const SourceLocation *ProtoLocs, SourceLocation EndProtoLoc,
       const ParsedAttributesView &AttrList);
 
   ObjCImplementationDecl *ActOnStartClassImplementation(
       SourceLocation AtClassImplLoc, IdentifierInfo *ClassName,
       SourceLocation ClassLoc, IdentifierInfo *SuperClassname,
       SourceLocation SuperClassLoc, const ParsedAttributesView &AttrList);
 
   ObjCCategoryImplDecl *ActOnStartCategoryImplementation(
       SourceLocation AtCatImplLoc, IdentifierInfo *ClassName,
       SourceLocation ClassLoc, IdentifierInfo *CatName, SourceLocation CatLoc,
       const ParsedAttributesView &AttrList);
 
   DeclGroupPtrTy ActOnFinishObjCImplementation(Decl *ObjCImpDecl,
                                                ArrayRef<Decl *> Decls);
 
   DeclGroupPtrTy ActOnForwardClassDeclaration(SourceLocation Loc,
                    IdentifierInfo **IdentList,
                    SourceLocation *IdentLocs,
                    ArrayRef<ObjCTypeParamList *> TypeParamLists,
                    unsigned NumElts);
 
   DeclGroupPtrTy
   ActOnForwardProtocolDeclaration(SourceLocation AtProtoclLoc,
                                   ArrayRef<IdentifierLocPair> IdentList,
                                   const ParsedAttributesView &attrList);
 
   void FindProtocolDeclaration(bool WarnOnDeclarations, bool ForObjCContainer,
                                ArrayRef<IdentifierLocPair> ProtocolId,
                                SmallVectorImpl<Decl *> &Protocols);
 
   void DiagnoseTypeArgsAndProtocols(IdentifierInfo *ProtocolId,
                                     SourceLocation ProtocolLoc,
                                     IdentifierInfo *TypeArgId,
                                     SourceLocation TypeArgLoc,
                                     bool SelectProtocolFirst = false);
 
   /// Given a list of identifiers (and their locations), resolve the
   /// names to either Objective-C protocol qualifiers or type
   /// arguments, as appropriate.
   void actOnObjCTypeArgsOrProtocolQualifiers(
          Scope *S,
          ParsedType baseType,
          SourceLocation lAngleLoc,
          ArrayRef<IdentifierInfo *> identifiers,
          ArrayRef<SourceLocation> identifierLocs,
          SourceLocation rAngleLoc,
          SourceLocation &typeArgsLAngleLoc,
          SmallVectorImpl<ParsedType> &typeArgs,
          SourceLocation &typeArgsRAngleLoc,
          SourceLocation &protocolLAngleLoc,
          SmallVectorImpl<Decl *> &protocols,
          SourceLocation &protocolRAngleLoc,
          bool warnOnIncompleteProtocols);
 
   /// Build a an Objective-C protocol-qualified 'id' type where no
   /// base type was specified.
   TypeResult actOnObjCProtocolQualifierType(
                SourceLocation lAngleLoc,
                ArrayRef<Decl *> protocols,
                ArrayRef<SourceLocation> protocolLocs,
                SourceLocation rAngleLoc);
 
   /// Build a specialized and/or protocol-qualified Objective-C type.
   TypeResult actOnObjCTypeArgsAndProtocolQualifiers(
                Scope *S,
                SourceLocation Loc,
                ParsedType BaseType,
                SourceLocation TypeArgsLAngleLoc,
                ArrayRef<ParsedType> TypeArgs,
                SourceLocation TypeArgsRAngleLoc,
                SourceLocation ProtocolLAngleLoc,
                ArrayRef<Decl *> Protocols,
                ArrayRef<SourceLocation> ProtocolLocs,
                SourceLocation ProtocolRAngleLoc);
 
   /// Build an Objective-C type parameter type.
   QualType BuildObjCTypeParamType(const ObjCTypeParamDecl *Decl,
                                   SourceLocation ProtocolLAngleLoc,
                                   ArrayRef<ObjCProtocolDecl *> Protocols,
                                   ArrayRef<SourceLocation> ProtocolLocs,
                                   SourceLocation ProtocolRAngleLoc,
                                   bool FailOnError = false);
 
   /// Build an Objective-C object pointer type.
   QualType BuildObjCObjectType(
       QualType BaseType, SourceLocation Loc, SourceLocation TypeArgsLAngleLoc,
       ArrayRef<TypeSourceInfo *> TypeArgs, SourceLocation TypeArgsRAngleLoc,
       SourceLocation ProtocolLAngleLoc, ArrayRef<ObjCProtocolDecl *> Protocols,
       ArrayRef<SourceLocation> ProtocolLocs, SourceLocation ProtocolRAngleLoc,
       bool FailOnError, bool Rebuilding);
 
   /// Ensure attributes are consistent with type.
   /// \param [in, out] Attributes The attributes to check; they will
   /// be modified to be consistent with \p PropertyTy.
   void CheckObjCPropertyAttributes(Decl *PropertyPtrTy,
                                    SourceLocation Loc,
                                    unsigned &Attributes,
                                    bool propertyInPrimaryClass);
 
   /// Process the specified property declaration and create decls for the
   /// setters and getters as needed.
   /// \param property The property declaration being processed
   void ProcessPropertyDecl(ObjCPropertyDecl *property);
 
 
   void DiagnosePropertyMismatch(ObjCPropertyDecl *Property,
                                 ObjCPropertyDecl *SuperProperty,
                                 const IdentifierInfo *Name,
                                 bool OverridingProtocolProperty);
 
   void DiagnoseClassExtensionDupMethods(ObjCCategoryDecl *CAT,
                                         ObjCInterfaceDecl *ID);
 
   Decl *ActOnAtEnd(Scope *S, SourceRange AtEnd,
                    ArrayRef<Decl *> allMethods = std::nullopt,
                    ArrayRef<DeclGroupPtrTy> allTUVars = std::nullopt);
 
   Decl *ActOnProperty(Scope *S, SourceLocation AtLoc,
                       SourceLocation LParenLoc,
                       FieldDeclarator &FD, ObjCDeclSpec &ODS,
                       Selector GetterSel, Selector SetterSel,
                       tok::ObjCKeywordKind MethodImplKind,
                       DeclContext *lexicalDC = nullptr);
 
   Decl *ActOnPropertyImplDecl(Scope *S,
                               SourceLocation AtLoc,
                               SourceLocation PropertyLoc,
                               bool ImplKind,
                               IdentifierInfo *PropertyId,
                               IdentifierInfo *PropertyIvar,
                               SourceLocation PropertyIvarLoc,
                               ObjCPropertyQueryKind QueryKind);
 
   enum ObjCSpecialMethodKind {
     OSMK_None,
     OSMK_Alloc,
     OSMK_New,
     OSMK_Copy,
     OSMK_RetainingInit,
     OSMK_NonRetainingInit
   };
 
   struct ObjCArgInfo {
     IdentifierInfo *Name;
     SourceLocation NameLoc;
     // The Type is null if no type was specified, and the DeclSpec is invalid
     // in this case.
     ParsedType Type;
     ObjCDeclSpec DeclSpec;
 
     /// ArgAttrs - Attribute list for this argument.
     ParsedAttributesView ArgAttrs;
   };
 
   Decl *ActOnMethodDeclaration(
       Scope *S,
       SourceLocation BeginLoc, // location of the + or -.
       SourceLocation EndLoc,   // location of the ; or {.
       tok::TokenKind MethodType, ObjCDeclSpec &ReturnQT, ParsedType ReturnType,
       ArrayRef<SourceLocation> SelectorLocs, Selector Sel,
       // optional arguments. The number of types/arguments is obtained
       // from the Sel.getNumArgs().
       ObjCArgInfo *ArgInfo, DeclaratorChunk::ParamInfo *CParamInfo,
       unsigned CNumArgs, // c-style args
       const ParsedAttributesView &AttrList, tok::ObjCKeywordKind MethodImplKind,
       bool isVariadic, bool MethodDefinition);
 
   ObjCMethodDecl *LookupMethodInQualifiedType(Selector Sel,
                                               const ObjCObjectPointerType *OPT,
                                               bool IsInstance);
   ObjCMethodDecl *LookupMethodInObjectType(Selector Sel, QualType Ty,
                                            bool IsInstance);
 
   bool CheckARCMethodDecl(ObjCMethodDecl *method);
   bool inferObjCARCLifetime(ValueDecl *decl);
 
   void deduceOpenCLAddressSpace(ValueDecl *decl);
 
   ExprResult
   HandleExprPropertyRefExpr(const ObjCObjectPointerType *OPT,
                             Expr *BaseExpr,
                             SourceLocation OpLoc,
                             DeclarationName MemberName,
                             SourceLocation MemberLoc,
                             SourceLocation SuperLoc, QualType SuperType,
                             bool Super);
 
   ExprResult
   ActOnClassPropertyRefExpr(IdentifierInfo &receiverName,
                             IdentifierInfo &propertyName,
                             SourceLocation receiverNameLoc,
                             SourceLocation propertyNameLoc);
 
   ObjCMethodDecl *tryCaptureObjCSelf(SourceLocation Loc);
 
   /// Describes the kind of message expression indicated by a message
   /// send that starts with an identifier.
   enum ObjCMessageKind {
     /// The message is sent to 'super'.
     ObjCSuperMessage,
     /// The message is an instance message.
     ObjCInstanceMessage,
     /// The message is a class message, and the identifier is a type
     /// name.
     ObjCClassMessage
   };
 
   ObjCMessageKind getObjCMessageKind(Scope *S,
                                      IdentifierInfo *Name,
                                      SourceLocation NameLoc,
                                      bool IsSuper,
                                      bool HasTrailingDot,
                                      ParsedType &ReceiverType);
 
   ExprResult ActOnSuperMessage(Scope *S, SourceLocation SuperLoc,
                                Selector Sel,
                                SourceLocation LBracLoc,
                                ArrayRef<SourceLocation> SelectorLocs,
                                SourceLocation RBracLoc,
                                MultiExprArg Args);
 
   ExprResult BuildClassMessage(TypeSourceInfo *ReceiverTypeInfo,
                                QualType ReceiverType,
                                SourceLocation SuperLoc,
                                Selector Sel,
                                ObjCMethodDecl *Method,
                                SourceLocation LBracLoc,
                                ArrayRef<SourceLocation> SelectorLocs,
                                SourceLocation RBracLoc,
                                MultiExprArg Args,
                                bool isImplicit = false);
 
   ExprResult BuildClassMessageImplicit(QualType ReceiverType,
                                        bool isSuperReceiver,
                                        SourceLocation Loc,
                                        Selector Sel,
                                        ObjCMethodDecl *Method,
                                        MultiExprArg Args);
 
   ExprResult ActOnClassMessage(Scope *S,
                                ParsedType Receiver,
                                Selector Sel,
                                SourceLocation LBracLoc,
                                ArrayRef<SourceLocation> SelectorLocs,
                                SourceLocation RBracLoc,
                                MultiExprArg Args);
 
   ExprResult BuildInstanceMessage(Expr *Receiver,
                                   QualType ReceiverType,
                                   SourceLocation SuperLoc,
                                   Selector Sel,
                                   ObjCMethodDecl *Method,
                                   SourceLocation LBracLoc,
                                   ArrayRef<SourceLocation> SelectorLocs,
                                   SourceLocation RBracLoc,
                                   MultiExprArg Args,
                                   bool isImplicit = false);
 
   ExprResult BuildInstanceMessageImplicit(Expr *Receiver,
                                           QualType ReceiverType,
                                           SourceLocation Loc,
                                           Selector Sel,
                                           ObjCMethodDecl *Method,
                                           MultiExprArg Args);
 
   ExprResult ActOnInstanceMessage(Scope *S,
                                   Expr *Receiver,
                                   Selector Sel,
                                   SourceLocation LBracLoc,
                                   ArrayRef<SourceLocation> SelectorLocs,
                                   SourceLocation RBracLoc,
                                   MultiExprArg Args);
 
   ExprResult BuildObjCBridgedCast(SourceLocation LParenLoc,
                                   ObjCBridgeCastKind Kind,
                                   SourceLocation BridgeKeywordLoc,
                                   TypeSourceInfo *TSInfo,
                                   Expr *SubExpr);
 
   ExprResult ActOnObjCBridgedCast(Scope *S,
                                   SourceLocation LParenLoc,
                                   ObjCBridgeCastKind Kind,
                                   SourceLocation BridgeKeywordLoc,
                                   ParsedType Type,
                                   SourceLocation RParenLoc,
                                   Expr *SubExpr);
 
   void CheckTollFreeBridgeCast(QualType castType, Expr *castExpr);
 
   void CheckObjCBridgeRelatedCast(QualType castType, Expr *castExpr);
 
   bool CheckTollFreeBridgeStaticCast(QualType castType, Expr *castExpr,
                                      CastKind &Kind);
 
   bool checkObjCBridgeRelatedComponents(SourceLocation Loc,
                                         QualType DestType, QualType SrcType,
                                         ObjCInterfaceDecl *&RelatedClass,
                                         ObjCMethodDecl *&ClassMethod,
                                         ObjCMethodDecl *&InstanceMethod,
                                         TypedefNameDecl *&TDNDecl,
                                         bool CfToNs, bool Diagnose = true);
 
   bool CheckObjCBridgeRelatedConversions(SourceLocation Loc,
                                          QualType DestType, QualType SrcType,
                                          Expr *&SrcExpr, bool Diagnose = true);
 
   bool CheckConversionToObjCLiteral(QualType DstType, Expr *&SrcExpr,
                                     bool Diagnose = true);
 
   bool checkInitMethod(ObjCMethodDecl *method, QualType receiverTypeIfCall);
 
   /// Check whether the given new method is a valid override of the
   /// given overridden method, and set any properties that should be inherited.
   void CheckObjCMethodOverride(ObjCMethodDecl *NewMethod,
                                const ObjCMethodDecl *Overridden);
 
   /// Describes the compatibility of a result type with its method.
   enum ResultTypeCompatibilityKind {
     RTC_Compatible,
     RTC_Incompatible,
     RTC_Unknown
   };
 
   void CheckObjCMethodDirectOverrides(ObjCMethodDecl *method,
                                       ObjCMethodDecl *overridden);
 
   void CheckObjCMethodOverrides(ObjCMethodDecl *ObjCMethod,
                                 ObjCInterfaceDecl *CurrentClass,
                                 ResultTypeCompatibilityKind RTC);
 
   enum PragmaOptionsAlignKind {
     POAK_Native,  // #pragma options align=native
     POAK_Natural, // #pragma options align=natural
     POAK_Packed,  // #pragma options align=packed
     POAK_Power,   // #pragma options align=power
     POAK_Mac68k,  // #pragma options align=mac68k
     POAK_Reset    // #pragma options align=reset
   };
 
   /// ActOnPragmaClangSection - Called on well formed \#pragma clang section
   void ActOnPragmaClangSection(SourceLocation PragmaLoc,
                                PragmaClangSectionAction Action,
                                PragmaClangSectionKind SecKind, StringRef SecName);
 
   /// ActOnPragmaOptionsAlign - Called on well formed \#pragma options align.
   void ActOnPragmaOptionsAlign(PragmaOptionsAlignKind Kind,
                                SourceLocation PragmaLoc);
 
   /// ActOnPragmaPack - Called on well formed \#pragma pack(...).
   void ActOnPragmaPack(SourceLocation PragmaLoc, PragmaMsStackAction Action,
                        StringRef SlotLabel, Expr *Alignment);
 
   enum class PragmaAlignPackDiagnoseKind {
     NonDefaultStateAtInclude,
     ChangedStateAtExit
   };
 
   void DiagnoseNonDefaultPragmaAlignPack(PragmaAlignPackDiagnoseKind Kind,
                                          SourceLocation IncludeLoc);
   void DiagnoseUnterminatedPragmaAlignPack();
 
   /// ActOnPragmaMSStrictGuardStackCheck - Called on well formed \#pragma
   /// strict_gs_check.
   void ActOnPragmaMSStrictGuardStackCheck(SourceLocation PragmaLocation,
                                           PragmaMsStackAction Action,
                                           bool Value);
 
   /// ActOnPragmaMSStruct - Called on well formed \#pragma ms_struct [on|off].
   void ActOnPragmaMSStruct(PragmaMSStructKind Kind);
 
   /// ActOnPragmaMSComment - Called on well formed
   /// \#pragma comment(kind, "arg").
   void ActOnPragmaMSComment(SourceLocation CommentLoc, PragmaMSCommentKind Kind,
                             StringRef Arg);
 
   /// ActOnPragmaMSPointersToMembers - called on well formed \#pragma
   /// pointers_to_members(representation method[, general purpose
   /// representation]).
   void ActOnPragmaMSPointersToMembers(
       LangOptions::PragmaMSPointersToMembersKind Kind,
       SourceLocation PragmaLoc);
 
   /// Called on well formed \#pragma vtordisp().
   void ActOnPragmaMSVtorDisp(PragmaMsStackAction Action,
                              SourceLocation PragmaLoc,
                              MSVtorDispMode Value);
 
   enum PragmaSectionKind {
     PSK_DataSeg,
     PSK_BSSSeg,
     PSK_ConstSeg,
     PSK_CodeSeg,
   };
 
   bool UnifySection(StringRef SectionName, int SectionFlags,
                     NamedDecl *TheDecl);
   bool UnifySection(StringRef SectionName,
                     int SectionFlags,
                     SourceLocation PragmaSectionLocation);
 
   /// Called on well formed \#pragma bss_seg/data_seg/const_seg/code_seg.
   void ActOnPragmaMSSeg(SourceLocation PragmaLocation,
                         PragmaMsStackAction Action,
                         llvm::StringRef StackSlotLabel,
                         StringLiteral *SegmentName,
                         llvm::StringRef PragmaName);
 
   /// Called on well formed \#pragma section().
   void ActOnPragmaMSSection(SourceLocation PragmaLocation,
                             int SectionFlags, StringLiteral *SegmentName);
 
   /// Called on well-formed \#pragma init_seg().
   void ActOnPragmaMSInitSeg(SourceLocation PragmaLocation,
                             StringLiteral *SegmentName);
 
   /// Called on well-formed \#pragma alloc_text().
   void ActOnPragmaMSAllocText(
       SourceLocation PragmaLocation, StringRef Section,
       const SmallVector<std::tuple<IdentifierInfo *, SourceLocation>>
           &Functions);
 
   /// Called on #pragma clang __debug dump II
   void ActOnPragmaDump(Scope *S, SourceLocation Loc, IdentifierInfo *II);
 
   /// Called on #pragma clang __debug dump E
   void ActOnPragmaDump(Expr *E);
 
   /// ActOnPragmaDetectMismatch - Call on well-formed \#pragma detect_mismatch
   void ActOnPragmaDetectMismatch(SourceLocation Loc, StringRef Name,
                                  StringRef Value);
 
   /// Are precise floating point semantics currently enabled?
   bool isPreciseFPEnabled() {
     return !CurFPFeatures.getAllowFPReassociate() &&
            !CurFPFeatures.getNoSignedZero() &&
            !CurFPFeatures.getAllowReciprocal() &&
            !CurFPFeatures.getAllowApproxFunc();
   }
 
   void ActOnPragmaFPEvalMethod(SourceLocation Loc,
                                LangOptions::FPEvalMethodKind Value);
 
   /// ActOnPragmaFloatControl - Call on well-formed \#pragma float_control
   void ActOnPragmaFloatControl(SourceLocation Loc, PragmaMsStackAction Action,
                                PragmaFloatControlKind Value);
 
   /// ActOnPragmaUnused - Called on well-formed '\#pragma unused'.
   void ActOnPragmaUnused(const Token &Identifier,
                          Scope *curScope,
                          SourceLocation PragmaLoc);
 
   /// ActOnPragmaVisibility - Called on well formed \#pragma GCC visibility... .
   void ActOnPragmaVisibility(const IdentifierInfo* VisType,
                              SourceLocation PragmaLoc);
 
   NamedDecl *DeclClonePragmaWeak(NamedDecl *ND, const IdentifierInfo *II,
                                  SourceLocation Loc);
   void DeclApplyPragmaWeak(Scope *S, NamedDecl *ND, const WeakInfo &W);
 
   /// ActOnPragmaWeakID - Called on well formed \#pragma weak ident.
   void ActOnPragmaWeakID(IdentifierInfo* WeakName,
                          SourceLocation PragmaLoc,
                          SourceLocation WeakNameLoc);
 
   /// ActOnPragmaRedefineExtname - Called on well formed
   /// \#pragma redefine_extname oldname newname.
   void ActOnPragmaRedefineExtname(IdentifierInfo* WeakName,
                                   IdentifierInfo* AliasName,
                                   SourceLocation PragmaLoc,
                                   SourceLocation WeakNameLoc,
                                   SourceLocation AliasNameLoc);
 
   /// ActOnPragmaWeakAlias - Called on well formed \#pragma weak ident = ident.
   void ActOnPragmaWeakAlias(IdentifierInfo* WeakName,
                             IdentifierInfo* AliasName,
                             SourceLocation PragmaLoc,
                             SourceLocation WeakNameLoc,
                             SourceLocation AliasNameLoc);
 
   /// ActOnPragmaFPContract - Called on well formed
   /// \#pragma {STDC,OPENCL} FP_CONTRACT and
   /// \#pragma clang fp contract
   void ActOnPragmaFPContract(SourceLocation Loc, LangOptions::FPModeKind FPC);
 
   /// Called on well formed
   /// \#pragma clang fp reassociate
   void ActOnPragmaFPReassociate(SourceLocation Loc, bool IsEnabled);
 
   /// ActOnPragmaFenvAccess - Called on well formed
   /// \#pragma STDC FENV_ACCESS
   void ActOnPragmaFEnvAccess(SourceLocation Loc, bool IsEnabled);
 
   /// Called on well formed '\#pragma clang fp' that has option 'exceptions'.
   void ActOnPragmaFPExceptions(SourceLocation Loc,
                                LangOptions::FPExceptionModeKind);
 
   /// Called to set constant rounding mode for floating point operations.
   void ActOnPragmaFEnvRound(SourceLocation Loc, llvm::RoundingMode);
 
   /// Called to set exception behavior for floating point operations.
   void setExceptionMode(SourceLocation Loc, LangOptions::FPExceptionModeKind);
 
   /// AddAlignmentAttributesForRecord - Adds any needed alignment attributes to
   /// a the record decl, to handle '\#pragma pack' and '\#pragma options align'.
   void AddAlignmentAttributesForRecord(RecordDecl *RD);
 
   /// AddMsStructLayoutForRecord - Adds ms_struct layout attribute to record.
   void AddMsStructLayoutForRecord(RecordDecl *RD);
 
   /// PushNamespaceVisibilityAttr - Note that we've entered a
   /// namespace with a visibility attribute.
   void PushNamespaceVisibilityAttr(const VisibilityAttr *Attr,
                                    SourceLocation Loc);
 
   /// AddPushedVisibilityAttribute - If '\#pragma GCC visibility' was used,
   /// add an appropriate visibility attribute.
   void AddPushedVisibilityAttribute(Decl *RD);
 
   /// PopPragmaVisibility - Pop the top element of the visibility stack; used
   /// for '\#pragma GCC visibility' and visibility attributes on namespaces.
   void PopPragmaVisibility(bool IsNamespaceEnd, SourceLocation EndLoc);
 
   /// FreeVisContext - Deallocate and null out VisContext.
   void FreeVisContext();
 
   /// AddCFAuditedAttribute - Check whether we're currently within
   /// '\#pragma clang arc_cf_code_audited' and, if so, consider adding
   /// the appropriate attribute.
   void AddCFAuditedAttribute(Decl *D);
 
   void ActOnPragmaAttributeAttribute(ParsedAttr &Attribute,
                                      SourceLocation PragmaLoc,
                                      attr::ParsedSubjectMatchRuleSet Rules);
   void ActOnPragmaAttributeEmptyPush(SourceLocation PragmaLoc,
                                      const IdentifierInfo *Namespace);
 
   /// Called on well-formed '\#pragma clang attribute pop'.
   void ActOnPragmaAttributePop(SourceLocation PragmaLoc,
                                const IdentifierInfo *Namespace);
 
   /// Adds the attributes that have been specified using the
   /// '\#pragma clang attribute push' directives to the given declaration.
   void AddPragmaAttributes(Scope *S, Decl *D);
 
   void DiagnoseUnterminatedPragmaAttribute();
 
   /// Called on well formed \#pragma clang optimize.
   void ActOnPragmaOptimize(bool On, SourceLocation PragmaLoc);
 
   /// #pragma optimize("[optimization-list]", on | off).
   void ActOnPragmaMSOptimize(SourceLocation Loc, bool IsOn);
 
   /// Call on well formed \#pragma function.
   void
   ActOnPragmaMSFunction(SourceLocation Loc,
                         const llvm::SmallVectorImpl<StringRef> &NoBuiltins);
 
   /// Get the location for the currently active "\#pragma clang optimize
   /// off". If this location is invalid, then the state of the pragma is "on".
   SourceLocation getOptimizeOffPragmaLocation() const {
     return OptimizeOffPragmaLocation;
   }
 
   /// Only called on function definitions; if there is a pragma in scope
   /// with the effect of a range-based optnone, consider marking the function
   /// with attribute optnone.
   void AddRangeBasedOptnone(FunctionDecl *FD);
 
   /// Only called on function definitions; if there is a `#pragma alloc_text`
   /// that decides which code section the function should be in, add
   /// attribute section to the function.
   void AddSectionMSAllocText(FunctionDecl *FD);
 
   /// Adds the 'optnone' attribute to the function declaration if there
   /// are no conflicts; Loc represents the location causing the 'optnone'
   /// attribute to be added (usually because of a pragma).
   void AddOptnoneAttributeIfNoConflicts(FunctionDecl *FD, SourceLocation Loc);
 
   /// Only called on function definitions; if there is a MSVC #pragma optimize
   /// in scope, consider changing the function's attributes based on the
   /// optimization list passed to the pragma.
   void ModifyFnAttributesMSPragmaOptimize(FunctionDecl *FD);
 
   /// Only called on function definitions; if there is a pragma in scope
   /// with the effect of a range-based no_builtin, consider marking the function
   /// with attribute no_builtin.
   void AddImplicitMSFunctionNoBuiltinAttr(FunctionDecl *FD);
 
   /// AddAlignedAttr - Adds an aligned attribute to a particular declaration.
   void AddAlignedAttr(Decl *D, const AttributeCommonInfo &CI, Expr *E,
                       bool IsPackExpansion);
   void AddAlignedAttr(Decl *D, const AttributeCommonInfo &CI, TypeSourceInfo *T,
                       bool IsPackExpansion);
 
   /// AddAssumeAlignedAttr - Adds an assume_aligned attribute to a particular
   /// declaration.
   void AddAssumeAlignedAttr(Decl *D, const AttributeCommonInfo &CI, Expr *E,
                             Expr *OE);
 
   /// AddAllocAlignAttr - Adds an alloc_align attribute to a particular
   /// declaration.
   void AddAllocAlignAttr(Decl *D, const AttributeCommonInfo &CI,
                          Expr *ParamExpr);
 
   /// AddAlignValueAttr - Adds an align_value attribute to a particular
   /// declaration.
   void AddAlignValueAttr(Decl *D, const AttributeCommonInfo &CI, Expr *E);
 
   /// AddAnnotationAttr - Adds an annotation Annot with Args arguments to D.
   void AddAnnotationAttr(Decl *D, const AttributeCommonInfo &CI,
                          StringRef Annot, MutableArrayRef<Expr *> Args);
 
   /// ConstantFoldAttrArgs - Folds attribute arguments into ConstantExprs
   /// (unless they are value dependent or type dependent). Returns false
   /// and emits a diagnostic if one or more of the arguments could not be
   /// folded into a constant.
   bool ConstantFoldAttrArgs(const AttributeCommonInfo &CI,
                             MutableArrayRef<Expr *> Args);
 
   /// AddLaunchBoundsAttr - Adds a launch_bounds attribute to a particular
   /// declaration.
   void AddLaunchBoundsAttr(Decl *D, const AttributeCommonInfo &CI,
                            Expr *MaxThreads, Expr *MinBlocks);
 
   /// AddModeAttr - Adds a mode attribute to a particular declaration.
   void AddModeAttr(Decl *D, const AttributeCommonInfo &CI, IdentifierInfo *Name,
                    bool InInstantiation = false);
 
   void AddParameterABIAttr(Decl *D, const AttributeCommonInfo &CI,
                            ParameterABI ABI);
 
   enum class RetainOwnershipKind {NS, CF, OS};
   void AddXConsumedAttr(Decl *D, const AttributeCommonInfo &CI,
                         RetainOwnershipKind K, bool IsTemplateInstantiation);
 
   /// addAMDGPUFlatWorkGroupSizeAttr - Adds an amdgpu_flat_work_group_size
   /// attribute to a particular declaration.
   void addAMDGPUFlatWorkGroupSizeAttr(Decl *D, const AttributeCommonInfo &CI,
                                       Expr *Min, Expr *Max);
 
   /// addAMDGPUWavePersEUAttr - Adds an amdgpu_waves_per_eu attribute to a
   /// particular declaration.
   void addAMDGPUWavesPerEUAttr(Decl *D, const AttributeCommonInfo &CI,
                                Expr *Min, Expr *Max);
 
   bool checkNSReturnsRetainedReturnType(SourceLocation loc, QualType type);
 
   //===--------------------------------------------------------------------===//
   // C++ Coroutines
   //
   bool ActOnCoroutineBodyStart(Scope *S, SourceLocation KwLoc,
                                StringRef Keyword);
   ExprResult ActOnCoawaitExpr(Scope *S, SourceLocation KwLoc, Expr *E);
   ExprResult ActOnCoyieldExpr(Scope *S, SourceLocation KwLoc, Expr *E);
   StmtResult ActOnCoreturnStmt(Scope *S, SourceLocation KwLoc, Expr *E);
 
   ExprResult BuildOperatorCoawaitLookupExpr(Scope *S, SourceLocation Loc);
   ExprResult BuildOperatorCoawaitCall(SourceLocation Loc, Expr *E,
                                       UnresolvedLookupExpr *Lookup);
   ExprResult BuildResolvedCoawaitExpr(SourceLocation KwLoc, Expr *Operand,
                                       Expr *Awaiter, bool IsImplicit = false);
   ExprResult BuildUnresolvedCoawaitExpr(SourceLocation KwLoc, Expr *Operand,
                                         UnresolvedLookupExpr *Lookup);
   ExprResult BuildCoyieldExpr(SourceLocation KwLoc, Expr *E);
   StmtResult BuildCoreturnStmt(SourceLocation KwLoc, Expr *E,
                                bool IsImplicit = false);
   StmtResult BuildCoroutineBodyStmt(CoroutineBodyStmt::CtorArgs);
   bool buildCoroutineParameterMoves(SourceLocation Loc);
   VarDecl *buildCoroutinePromise(SourceLocation Loc);
   void CheckCompletedCoroutineBody(FunctionDecl *FD, Stmt *&Body);
   /// Lookup 'coroutine_traits' in std namespace and std::experimental
   /// namespace. The namespace found is recorded in Namespace.
   ClassTemplateDecl *lookupCoroutineTraits(SourceLocation KwLoc,
                                            SourceLocation FuncLoc);
   /// Check that the expression co_await promise.final_suspend() shall not be
   /// potentially-throwing.
   bool checkFinalSuspendNoThrow(const Stmt *FinalSuspend);
 
   //===--------------------------------------------------------------------===//
   // OpenMP directives and clauses.
   //
 private:
   void *VarDataSharingAttributesStack;
 
   struct DeclareTargetContextInfo {
     struct MapInfo {
       OMPDeclareTargetDeclAttr::MapTypeTy MT;
       SourceLocation Loc;
     };
     /// Explicitly listed variables and functions in a 'to' or 'link' clause.
     llvm::DenseMap<NamedDecl *, MapInfo> ExplicitlyMapped;
 
     /// The 'device_type' as parsed from the clause.
     OMPDeclareTargetDeclAttr::DevTypeTy DT = OMPDeclareTargetDeclAttr::DT_Any;
 
     /// The directive kind, `begin declare target` or `declare target`.
     OpenMPDirectiveKind Kind;
 
     /// The directive with indirect clause.
     std::optional<Expr *> Indirect;
 
     /// The directive location.
     SourceLocation Loc;
 
     DeclareTargetContextInfo(OpenMPDirectiveKind Kind, SourceLocation Loc)
         : Kind(Kind), Loc(Loc) {}
   };
 
   /// Number of nested '#pragma omp declare target' directives.
   SmallVector<DeclareTargetContextInfo, 4> DeclareTargetNesting;
 
   /// Initialization of data-sharing attributes stack.
   void InitDataSharingAttributesStack();
   void DestroyDataSharingAttributesStack();
 
   /// Returns OpenMP nesting level for current directive.
   unsigned getOpenMPNestingLevel() const;
 
   /// Adjusts the function scopes index for the target-based regions.
   void adjustOpenMPTargetScopeIndex(unsigned &FunctionScopesIndex,
                                     unsigned Level) const;
 
   /// Returns the number of scopes associated with the construct on the given
   /// OpenMP level.
   int getNumberOfConstructScopes(unsigned Level) const;
 
   /// Push new OpenMP function region for non-capturing function.
   void pushOpenMPFunctionRegion();
 
   /// Pop OpenMP function region for non-capturing function.
   void popOpenMPFunctionRegion(const sema::FunctionScopeInfo *OldFSI);
 
   /// Analyzes and checks a loop nest for use by a loop transformation.
   ///
   /// \param Kind          The loop transformation directive kind.
   /// \param NumLoops      How many nested loops the directive is expecting.
   /// \param AStmt         Associated statement of the transformation directive.
   /// \param LoopHelpers   [out] The loop analysis result.
   /// \param Body          [out] The body code nested in \p NumLoops loop.
   /// \param OriginalInits [out] Collection of statements and declarations that
   ///                      must have been executed/declared before entering the
   ///                      loop.
   ///
   /// \return Whether there was any error.
   bool checkTransformableLoopNest(
       OpenMPDirectiveKind Kind, Stmt *AStmt, int NumLoops,
       SmallVectorImpl<OMPLoopBasedDirective::HelperExprs> &LoopHelpers,
       Stmt *&Body,
       SmallVectorImpl<SmallVector<llvm::PointerUnion<Stmt *, Decl *>, 0>>
           &OriginalInits);
 
   /// Helper to keep information about the current `omp begin/end declare
   /// variant` nesting.
   struct OMPDeclareVariantScope {
     /// The associated OpenMP context selector.
     OMPTraitInfo *TI;
 
     /// The associated OpenMP context selector mangling.
     std::string NameSuffix;
 
     OMPDeclareVariantScope(OMPTraitInfo &TI);
   };
 
   /// Return the OMPTraitInfo for the surrounding scope, if any.
   OMPTraitInfo *getOMPTraitInfoForSurroundingScope() {
     return OMPDeclareVariantScopes.empty() ? nullptr
                                            : OMPDeclareVariantScopes.back().TI;
   }
 
   /// The current `omp begin/end declare variant` scopes.
   SmallVector<OMPDeclareVariantScope, 4> OMPDeclareVariantScopes;
 
   /// The current `omp begin/end assumes` scopes.
   SmallVector<AssumptionAttr *, 4> OMPAssumeScoped;
 
   /// All `omp assumes` we encountered so far.
   SmallVector<AssumptionAttr *, 4> OMPAssumeGlobal;
 
 public:
   /// The declarator \p D defines a function in the scope \p S which is nested
   /// in an `omp begin/end declare variant` scope. In this method we create a
   /// declaration for \p D and rename \p D according to the OpenMP context
   /// selector of the surrounding scope. Return all base functions in \p Bases.
   void ActOnStartOfFunctionDefinitionInOpenMPDeclareVariantScope(
       Scope *S, Declarator &D, MultiTemplateParamsArg TemplateParameterLists,
       SmallVectorImpl<FunctionDecl *> &Bases);
 
   /// Register \p D as specialization of all base functions in \p Bases in the
   /// current `omp begin/end declare variant` scope.
   void ActOnFinishedFunctionDefinitionInOpenMPDeclareVariantScope(
       Decl *D, SmallVectorImpl<FunctionDecl *> &Bases);
 
   /// Act on \p D, a function definition inside of an `omp [begin/end] assumes`.
   void ActOnFinishedFunctionDefinitionInOpenMPAssumeScope(Decl *D);
 
   /// Can we exit an OpenMP declare variant scope at the moment.
   bool isInOpenMPDeclareVariantScope() const {
     return !OMPDeclareVariantScopes.empty();
   }
 
   ExprResult
   VerifyPositiveIntegerConstantInClause(Expr *Op, OpenMPClauseKind CKind,
                                         bool StrictlyPositive = true,
                                         bool SuppressExprDiags = false);
 
   /// Given the potential call expression \p Call, determine if there is a
   /// specialization via the OpenMP declare variant mechanism available. If
   /// there is, return the specialized call expression, otherwise return the
   /// original \p Call.
   ExprResult ActOnOpenMPCall(ExprResult Call, Scope *Scope,
                              SourceLocation LParenLoc, MultiExprArg ArgExprs,
                              SourceLocation RParenLoc, Expr *ExecConfig);
 
   /// Handle a `omp begin declare variant`.
   void ActOnOpenMPBeginDeclareVariant(SourceLocation Loc, OMPTraitInfo &TI);
 
   /// Handle a `omp end declare variant`.
   void ActOnOpenMPEndDeclareVariant();
 
   /// Checks if the variant/multiversion functions are compatible.
   bool areMultiversionVariantFunctionsCompatible(
       const FunctionDecl *OldFD, const FunctionDecl *NewFD,
       const PartialDiagnostic &NoProtoDiagID,
       const PartialDiagnosticAt &NoteCausedDiagIDAt,
       const PartialDiagnosticAt &NoSupportDiagIDAt,
       const PartialDiagnosticAt &DiffDiagIDAt, bool TemplatesSupported,
       bool ConstexprSupported, bool CLinkageMayDiffer);
 
   /// Function tries to capture lambda's captured variables in the OpenMP region
   /// before the original lambda is captured.
   void tryCaptureOpenMPLambdas(ValueDecl *V);
 
   /// Return true if the provided declaration \a VD should be captured by
   /// reference.
   /// \param Level Relative level of nested OpenMP construct for that the check
   /// is performed.
   /// \param OpenMPCaptureLevel Capture level within an OpenMP construct.
   bool isOpenMPCapturedByRef(const ValueDecl *D, unsigned Level,
                              unsigned OpenMPCaptureLevel) const;
 
   /// Check if the specified variable is used in one of the private
   /// clauses (private, firstprivate, lastprivate, reduction etc.) in OpenMP
   /// constructs.
   VarDecl *isOpenMPCapturedDecl(ValueDecl *D, bool CheckScopeInfo = false,
                                 unsigned StopAt = 0);
 
   /// The member expression(this->fd) needs to be rebuilt in the template
   /// instantiation to generate private copy for OpenMP when default
   /// clause is used. The function will return true if default
   /// cluse is used.
   bool isOpenMPRebuildMemberExpr(ValueDecl *D);
 
   ExprResult getOpenMPCapturedExpr(VarDecl *Capture, ExprValueKind VK,
                                    ExprObjectKind OK, SourceLocation Loc);
 
   /// If the current region is a loop-based region, mark the start of the loop
   /// construct.
   void startOpenMPLoop();
 
   /// If the current region is a range loop-based region, mark the start of the
   /// loop construct.
   void startOpenMPCXXRangeFor();
 
   /// Check if the specified variable is used in 'private' clause.
   /// \param Level Relative level of nested OpenMP construct for that the check
   /// is performed.
   OpenMPClauseKind isOpenMPPrivateDecl(ValueDecl *D, unsigned Level,
                                        unsigned CapLevel) const;
 
   /// Sets OpenMP capture kind (OMPC_private, OMPC_firstprivate, OMPC_map etc.)
   /// for \p FD based on DSA for the provided corresponding captured declaration
   /// \p D.
   void setOpenMPCaptureKind(FieldDecl *FD, const ValueDecl *D, unsigned Level);
 
   /// Check if the specified variable is captured  by 'target' directive.
   /// \param Level Relative level of nested OpenMP construct for that the check
   /// is performed.
   bool isOpenMPTargetCapturedDecl(const ValueDecl *D, unsigned Level,
                                   unsigned CaptureLevel) const;
 
   /// Check if the specified global variable must be captured  by outer capture
   /// regions.
   /// \param Level Relative level of nested OpenMP construct for that
   /// the check is performed.
   bool isOpenMPGlobalCapturedDecl(ValueDecl *D, unsigned Level,
                                   unsigned CaptureLevel) const;
 
   ExprResult PerformOpenMPImplicitIntegerConversion(SourceLocation OpLoc,
                                                     Expr *Op);
   /// Called on start of new data sharing attribute block.
   void StartOpenMPDSABlock(OpenMPDirectiveKind K,
                            const DeclarationNameInfo &DirName, Scope *CurScope,
                            SourceLocation Loc);
   /// Start analysis of clauses.
   void StartOpenMPClause(OpenMPClauseKind K);
   /// End analysis of clauses.
   void EndOpenMPClause();
   /// Called on end of data sharing attribute block.
   void EndOpenMPDSABlock(Stmt *CurDirective);
 
   /// Check if the current region is an OpenMP loop region and if it is,
   /// mark loop control variable, used in \p Init for loop initialization, as
   /// private by default.
   /// \param Init First part of the for loop.
   void ActOnOpenMPLoopInitialization(SourceLocation ForLoc, Stmt *Init);
 
   /// Called on well-formed '\#pragma omp metadirective' after parsing
   /// of the  associated statement.
   StmtResult ActOnOpenMPMetaDirective(ArrayRef<OMPClause *> Clauses,
                                       Stmt *AStmt, SourceLocation StartLoc,
                                       SourceLocation EndLoc);
 
   // OpenMP directives and clauses.
   /// Called on correct id-expression from the '#pragma omp
   /// threadprivate'.
   ExprResult ActOnOpenMPIdExpression(Scope *CurScope, CXXScopeSpec &ScopeSpec,
                                      const DeclarationNameInfo &Id,
                                      OpenMPDirectiveKind Kind);
   /// Called on well-formed '#pragma omp threadprivate'.
   DeclGroupPtrTy ActOnOpenMPThreadprivateDirective(
                                      SourceLocation Loc,
                                      ArrayRef<Expr *> VarList);
   /// Builds a new OpenMPThreadPrivateDecl and checks its correctness.
   OMPThreadPrivateDecl *CheckOMPThreadPrivateDecl(SourceLocation Loc,
                                                   ArrayRef<Expr *> VarList);
   /// Called on well-formed '#pragma omp allocate'.
   DeclGroupPtrTy ActOnOpenMPAllocateDirective(SourceLocation Loc,
                                               ArrayRef<Expr *> VarList,
                                               ArrayRef<OMPClause *> Clauses,
                                               DeclContext *Owner = nullptr);
 
   /// Called on well-formed '#pragma omp [begin] assume[s]'.
   void ActOnOpenMPAssumesDirective(SourceLocation Loc,
                                    OpenMPDirectiveKind DKind,
                                    ArrayRef<std::string> Assumptions,
                                    bool SkippedClauses);
 
   /// Check if there is an active global `omp begin assumes` directive.
   bool isInOpenMPAssumeScope() const { return !OMPAssumeScoped.empty(); }
 
   /// Check if there is an active global `omp assumes` directive.
   bool hasGlobalOpenMPAssumes() const { return !OMPAssumeGlobal.empty(); }
 
   /// Called on well-formed '#pragma omp end assumes'.
   void ActOnOpenMPEndAssumesDirective();
 
   /// Called on well-formed '#pragma omp requires'.
   DeclGroupPtrTy ActOnOpenMPRequiresDirective(SourceLocation Loc,
                                               ArrayRef<OMPClause *> ClauseList);
   /// Check restrictions on Requires directive
   OMPRequiresDecl *CheckOMPRequiresDecl(SourceLocation Loc,
                                         ArrayRef<OMPClause *> Clauses);
   /// Check if the specified type is allowed to be used in 'omp declare
   /// reduction' construct.
   QualType ActOnOpenMPDeclareReductionType(SourceLocation TyLoc,
                                            TypeResult ParsedType);
   /// Called on start of '#pragma omp declare reduction'.
   DeclGroupPtrTy ActOnOpenMPDeclareReductionDirectiveStart(
       Scope *S, DeclContext *DC, DeclarationName Name,
       ArrayRef<std::pair<QualType, SourceLocation>> ReductionTypes,
       AccessSpecifier AS, Decl *PrevDeclInScope = nullptr);
   /// Initialize declare reduction construct initializer.
   void ActOnOpenMPDeclareReductionCombinerStart(Scope *S, Decl *D);
   /// Finish current declare reduction construct initializer.
   void ActOnOpenMPDeclareReductionCombinerEnd(Decl *D, Expr *Combiner);
   /// Initialize declare reduction construct initializer.
   /// \return omp_priv variable.
   VarDecl *ActOnOpenMPDeclareReductionInitializerStart(Scope *S, Decl *D);
   /// Finish current declare reduction construct initializer.
   void ActOnOpenMPDeclareReductionInitializerEnd(Decl *D, Expr *Initializer,
                                                  VarDecl *OmpPrivParm);
   /// Called at the end of '#pragma omp declare reduction'.
   DeclGroupPtrTy ActOnOpenMPDeclareReductionDirectiveEnd(
       Scope *S, DeclGroupPtrTy DeclReductions, bool IsValid);
 
   /// Check variable declaration in 'omp declare mapper' construct.
   TypeResult ActOnOpenMPDeclareMapperVarDecl(Scope *S, Declarator &D);
   /// Check if the specified type is allowed to be used in 'omp declare
   /// mapper' construct.
   QualType ActOnOpenMPDeclareMapperType(SourceLocation TyLoc,
                                         TypeResult ParsedType);
   /// Called on start of '#pragma omp declare mapper'.
   DeclGroupPtrTy ActOnOpenMPDeclareMapperDirective(
       Scope *S, DeclContext *DC, DeclarationName Name, QualType MapperType,
       SourceLocation StartLoc, DeclarationName VN, AccessSpecifier AS,
       Expr *MapperVarRef, ArrayRef<OMPClause *> Clauses,
       Decl *PrevDeclInScope = nullptr);
   /// Build the mapper variable of '#pragma omp declare mapper'.
   ExprResult ActOnOpenMPDeclareMapperDirectiveVarDecl(Scope *S,
                                                       QualType MapperType,
                                                       SourceLocation StartLoc,
                                                       DeclarationName VN);
   void ActOnOpenMPIteratorVarDecl(VarDecl *VD);
   bool isOpenMPDeclareMapperVarDeclAllowed(const VarDecl *VD) const;
   const ValueDecl *getOpenMPDeclareMapperVarName() const;
 
   /// Called on the start of target region i.e. '#pragma omp declare target'.
   bool ActOnStartOpenMPDeclareTargetContext(DeclareTargetContextInfo &DTCI);
 
   /// Called at the end of target region i.e. '#pragma omp end declare target'.
   const DeclareTargetContextInfo ActOnOpenMPEndDeclareTargetDirective();
 
   /// Called once a target context is completed, that can be when a
   /// '#pragma omp end declare target' was encountered or when a
   /// '#pragma omp declare target' without declaration-definition-seq was
   /// encountered.
   void ActOnFinishedOpenMPDeclareTargetContext(DeclareTargetContextInfo &DTCI);
 
   /// Report unterminated 'omp declare target' or 'omp begin declare target' at
   /// the end of a compilation unit.
   void DiagnoseUnterminatedOpenMPDeclareTarget();
 
   /// Searches for the provided declaration name for OpenMP declare target
   /// directive.
   NamedDecl *lookupOpenMPDeclareTargetName(Scope *CurScope,
                                            CXXScopeSpec &ScopeSpec,
                                            const DeclarationNameInfo &Id);
 
   /// Called on correct id-expression from the '#pragma omp declare target'.
   void ActOnOpenMPDeclareTargetName(NamedDecl *ND, SourceLocation Loc,
                                     OMPDeclareTargetDeclAttr::MapTypeTy MT,
                                     DeclareTargetContextInfo &DTCI);
 
   /// Check declaration inside target region.
   void
   checkDeclIsAllowedInOpenMPTarget(Expr *E, Decl *D,
                                    SourceLocation IdLoc = SourceLocation());
 
   /// Adds OMPDeclareTargetDeclAttr to referenced variables in declare target
   /// directive.
   void ActOnOpenMPDeclareTargetInitializer(Decl *D);
 
   /// Finishes analysis of the deferred functions calls that may be declared as
   /// host/nohost during device/host compilation.
   void finalizeOpenMPDelayedAnalysis(const FunctionDecl *Caller,
                                      const FunctionDecl *Callee,
                                      SourceLocation Loc);
 
   /// Return true if currently in OpenMP task with untied clause context.
   bool isInOpenMPTaskUntiedContext() const;
 
   /// Return true inside OpenMP declare target region.
   bool isInOpenMPDeclareTargetContext() const {
     return !DeclareTargetNesting.empty();
   }
   /// Return true inside OpenMP target region.
   bool isInOpenMPTargetExecutionDirective() const;
 
   /// Return the number of captured regions created for an OpenMP directive.
   static int getOpenMPCaptureLevels(OpenMPDirectiveKind Kind);
 
   /// Initialization of captured region for OpenMP region.
   void ActOnOpenMPRegionStart(OpenMPDirectiveKind DKind, Scope *CurScope);
 
   /// Called for syntactical loops (ForStmt or CXXForRangeStmt) associated to
   /// an OpenMP loop directive.
   StmtResult ActOnOpenMPCanonicalLoop(Stmt *AStmt);
 
   /// Process a canonical OpenMP loop nest that can either be a canonical
   /// literal loop (ForStmt or CXXForRangeStmt), or the generated loop of an
   /// OpenMP loop transformation construct.
   StmtResult ActOnOpenMPLoopnest(Stmt *AStmt);
 
   /// End of OpenMP region.
   ///
   /// \param S Statement associated with the current OpenMP region.
   /// \param Clauses List of clauses for the current OpenMP region.
   ///
   /// \returns Statement for finished OpenMP region.
   StmtResult ActOnOpenMPRegionEnd(StmtResult S, ArrayRef<OMPClause *> Clauses);
   StmtResult ActOnOpenMPExecutableDirective(
       OpenMPDirectiveKind Kind, const DeclarationNameInfo &DirName,
       OpenMPDirectiveKind CancelRegion, ArrayRef<OMPClause *> Clauses,
       Stmt *AStmt, SourceLocation StartLoc, SourceLocation EndLoc);
   /// Called on well-formed '\#pragma omp parallel' after parsing
   /// of the  associated statement.
   StmtResult ActOnOpenMPParallelDirective(ArrayRef<OMPClause *> Clauses,
                                           Stmt *AStmt,
                                           SourceLocation StartLoc,
                                           SourceLocation EndLoc);
   using VarsWithInheritedDSAType =
       llvm::SmallDenseMap<const ValueDecl *, const Expr *, 4>;
   /// Called on well-formed '\#pragma omp simd' after parsing
   /// of the associated statement.
   StmtResult
   ActOnOpenMPSimdDirective(ArrayRef<OMPClause *> Clauses, Stmt *AStmt,
                            SourceLocation StartLoc, SourceLocation EndLoc,
                            VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '#pragma omp tile' after parsing of its clauses and
   /// the associated statement.
   StmtResult ActOnOpenMPTileDirective(ArrayRef<OMPClause *> Clauses,
                                       Stmt *AStmt, SourceLocation StartLoc,
                                       SourceLocation EndLoc);
   /// Called on well-formed '#pragma omp unroll' after parsing of its clauses
   /// and the associated statement.
   StmtResult ActOnOpenMPUnrollDirective(ArrayRef<OMPClause *> Clauses,
                                         Stmt *AStmt, SourceLocation StartLoc,
                                         SourceLocation EndLoc);
   /// Called on well-formed '\#pragma omp for' after parsing
   /// of the associated statement.
   StmtResult
   ActOnOpenMPForDirective(ArrayRef<OMPClause *> Clauses, Stmt *AStmt,
                           SourceLocation StartLoc, SourceLocation EndLoc,
                           VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp for simd' after parsing
   /// of the associated statement.
   StmtResult
   ActOnOpenMPForSimdDirective(ArrayRef<OMPClause *> Clauses, Stmt *AStmt,
                               SourceLocation StartLoc, SourceLocation EndLoc,
                               VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp sections' after parsing
   /// of the associated statement.
   StmtResult ActOnOpenMPSectionsDirective(ArrayRef<OMPClause *> Clauses,
                                           Stmt *AStmt, SourceLocation StartLoc,
                                           SourceLocation EndLoc);
   /// Called on well-formed '\#pragma omp section' after parsing of the
   /// associated statement.
   StmtResult ActOnOpenMPSectionDirective(Stmt *AStmt, SourceLocation StartLoc,
                                          SourceLocation EndLoc);
   /// Called on well-formed '\#pragma omp single' after parsing of the
   /// associated statement.
   StmtResult ActOnOpenMPSingleDirective(ArrayRef<OMPClause *> Clauses,
                                         Stmt *AStmt, SourceLocation StartLoc,
                                         SourceLocation EndLoc);
   /// Called on well-formed '\#pragma omp master' after parsing of the
   /// associated statement.
   StmtResult ActOnOpenMPMasterDirective(Stmt *AStmt, SourceLocation StartLoc,
                                         SourceLocation EndLoc);
   /// Called on well-formed '\#pragma omp critical' after parsing of the
   /// associated statement.
   StmtResult ActOnOpenMPCriticalDirective(const DeclarationNameInfo &DirName,
                                           ArrayRef<OMPClause *> Clauses,
                                           Stmt *AStmt, SourceLocation StartLoc,
                                           SourceLocation EndLoc);
   /// Called on well-formed '\#pragma omp parallel for' after parsing
   /// of the  associated statement.
   StmtResult ActOnOpenMPParallelForDirective(
       ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
       SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp parallel for simd' after
   /// parsing of the  associated statement.
   StmtResult ActOnOpenMPParallelForSimdDirective(
       ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
       SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp parallel master' after
   /// parsing of the  associated statement.
   StmtResult ActOnOpenMPParallelMasterDirective(ArrayRef<OMPClause *> Clauses,
                                                 Stmt *AStmt,
                                                 SourceLocation StartLoc,
                                                 SourceLocation EndLoc);
   /// Called on well-formed '\#pragma omp parallel masked' after
   /// parsing of the associated statement.
   StmtResult ActOnOpenMPParallelMaskedDirective(ArrayRef<OMPClause *> Clauses,
                                                 Stmt *AStmt,
                                                 SourceLocation StartLoc,
                                                 SourceLocation EndLoc);
   /// Called on well-formed '\#pragma omp parallel sections' after
   /// parsing of the  associated statement.
   StmtResult ActOnOpenMPParallelSectionsDirective(ArrayRef<OMPClause *> Clauses,
                                                   Stmt *AStmt,
                                                   SourceLocation StartLoc,
                                                   SourceLocation EndLoc);
   /// Called on well-formed '\#pragma omp task' after parsing of the
   /// associated statement.
   StmtResult ActOnOpenMPTaskDirective(ArrayRef<OMPClause *> Clauses,
                                       Stmt *AStmt, SourceLocation StartLoc,
                                       SourceLocation EndLoc);
   /// Called on well-formed '\#pragma omp taskyield'.
   StmtResult ActOnOpenMPTaskyieldDirective(SourceLocation StartLoc,
                                            SourceLocation EndLoc);
   /// Called on well-formed '\#pragma omp error'.
   /// Error direcitive is allowed in both declared and excutable contexts.
   /// Adding InExContext to identify which context is called from.
   StmtResult ActOnOpenMPErrorDirective(ArrayRef<OMPClause *> Clauses,
                                        SourceLocation StartLoc,
                                        SourceLocation EndLoc,
                                        bool InExContext = true);
   /// Called on well-formed '\#pragma omp barrier'.
   StmtResult ActOnOpenMPBarrierDirective(SourceLocation StartLoc,
                                          SourceLocation EndLoc);
   /// Called on well-formed '\#pragma omp taskwait'.
   StmtResult ActOnOpenMPTaskwaitDirective(ArrayRef<OMPClause *> Clauses,
                                           SourceLocation StartLoc,
                                           SourceLocation EndLoc);
   /// Called on well-formed '\#pragma omp taskgroup'.
   StmtResult ActOnOpenMPTaskgroupDirective(ArrayRef<OMPClause *> Clauses,
                                            Stmt *AStmt, SourceLocation StartLoc,
                                            SourceLocation EndLoc);
   /// Called on well-formed '\#pragma omp flush'.
   StmtResult ActOnOpenMPFlushDirective(ArrayRef<OMPClause *> Clauses,
                                        SourceLocation StartLoc,
                                        SourceLocation EndLoc);
   /// Called on well-formed '\#pragma omp depobj'.
   StmtResult ActOnOpenMPDepobjDirective(ArrayRef<OMPClause *> Clauses,
                                         SourceLocation StartLoc,
                                         SourceLocation EndLoc);
   /// Called on well-formed '\#pragma omp scan'.
   StmtResult ActOnOpenMPScanDirective(ArrayRef<OMPClause *> Clauses,
                                       SourceLocation StartLoc,
                                       SourceLocation EndLoc);
   /// Called on well-formed '\#pragma omp ordered' after parsing of the
   /// associated statement.
   StmtResult ActOnOpenMPOrderedDirective(ArrayRef<OMPClause *> Clauses,
                                          Stmt *AStmt, SourceLocation StartLoc,
                                          SourceLocation EndLoc);
   /// Called on well-formed '\#pragma omp atomic' after parsing of the
   /// associated statement.
   StmtResult ActOnOpenMPAtomicDirective(ArrayRef<OMPClause *> Clauses,
                                         Stmt *AStmt, SourceLocation StartLoc,
                                         SourceLocation EndLoc);
   /// Called on well-formed '\#pragma omp target' after parsing of the
   /// associated statement.
   StmtResult ActOnOpenMPTargetDirective(ArrayRef<OMPClause *> Clauses,
                                         Stmt *AStmt, SourceLocation StartLoc,
                                         SourceLocation EndLoc);
   /// Called on well-formed '\#pragma omp target data' after parsing of
   /// the associated statement.
   StmtResult ActOnOpenMPTargetDataDirective(ArrayRef<OMPClause *> Clauses,
                                             Stmt *AStmt, SourceLocation StartLoc,
                                             SourceLocation EndLoc);
   /// Called on well-formed '\#pragma omp target enter data' after
   /// parsing of the associated statement.
   StmtResult ActOnOpenMPTargetEnterDataDirective(ArrayRef<OMPClause *> Clauses,
                                                  SourceLocation StartLoc,
                                                  SourceLocation EndLoc,
                                                  Stmt *AStmt);
   /// Called on well-formed '\#pragma omp target exit data' after
   /// parsing of the associated statement.
   StmtResult ActOnOpenMPTargetExitDataDirective(ArrayRef<OMPClause *> Clauses,
                                                 SourceLocation StartLoc,
                                                 SourceLocation EndLoc,
                                                 Stmt *AStmt);
   /// Called on well-formed '\#pragma omp target parallel' after
   /// parsing of the associated statement.
   StmtResult ActOnOpenMPTargetParallelDirective(ArrayRef<OMPClause *> Clauses,
                                                 Stmt *AStmt,
                                                 SourceLocation StartLoc,
                                                 SourceLocation EndLoc);
   /// Called on well-formed '\#pragma omp target parallel for' after
   /// parsing of the  associated statement.
   StmtResult ActOnOpenMPTargetParallelForDirective(
       ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
       SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp teams' after parsing of the
   /// associated statement.
   StmtResult ActOnOpenMPTeamsDirective(ArrayRef<OMPClause *> Clauses,
                                        Stmt *AStmt, SourceLocation StartLoc,
                                        SourceLocation EndLoc);
   /// Called on well-formed '\#pragma omp teams loop' after parsing of the
   /// associated statement.
   StmtResult ActOnOpenMPTeamsGenericLoopDirective(
       ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
       SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp target teams loop' after parsing of
   /// the associated statement.
   StmtResult ActOnOpenMPTargetTeamsGenericLoopDirective(
       ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
       SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp parallel loop' after parsing of the
   /// associated statement.
   StmtResult ActOnOpenMPParallelGenericLoopDirective(
       ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
       SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp target parallel loop' after parsing
   /// of the associated statement.
   StmtResult ActOnOpenMPTargetParallelGenericLoopDirective(
       ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
       SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp cancellation point'.
   StmtResult
   ActOnOpenMPCancellationPointDirective(SourceLocation StartLoc,
                                         SourceLocation EndLoc,
                                         OpenMPDirectiveKind CancelRegion);
   /// Called on well-formed '\#pragma omp cancel'.
   StmtResult ActOnOpenMPCancelDirective(ArrayRef<OMPClause *> Clauses,
                                         SourceLocation StartLoc,
                                         SourceLocation EndLoc,
                                         OpenMPDirectiveKind CancelRegion);
   /// Called on well-formed '\#pragma omp taskloop' after parsing of the
   /// associated statement.
   StmtResult
   ActOnOpenMPTaskLoopDirective(ArrayRef<OMPClause *> Clauses, Stmt *AStmt,
                                SourceLocation StartLoc, SourceLocation EndLoc,
                                VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp taskloop simd' after parsing of
   /// the associated statement.
   StmtResult ActOnOpenMPTaskLoopSimdDirective(
       ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
       SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp master taskloop' after parsing of the
   /// associated statement.
   StmtResult ActOnOpenMPMasterTaskLoopDirective(
       ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
       SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp master taskloop simd' after parsing of
   /// the associated statement.
   StmtResult ActOnOpenMPMasterTaskLoopSimdDirective(
       ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
       SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp parallel master taskloop' after
   /// parsing of the associated statement.
   StmtResult ActOnOpenMPParallelMasterTaskLoopDirective(
       ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
       SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp parallel master taskloop simd' after
   /// parsing of the associated statement.
   StmtResult ActOnOpenMPParallelMasterTaskLoopSimdDirective(
       ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
       SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp masked taskloop' after parsing of the
   /// associated statement.
   StmtResult ActOnOpenMPMaskedTaskLoopDirective(
       ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
       SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp masked taskloop simd' after parsing of
   /// the associated statement.
   StmtResult ActOnOpenMPMaskedTaskLoopSimdDirective(
       ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
       SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp parallel masked taskloop' after
   /// parsing of the associated statement.
   StmtResult ActOnOpenMPParallelMaskedTaskLoopDirective(
       ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
       SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp parallel masked taskloop simd' after
   /// parsing of the associated statement.
   StmtResult ActOnOpenMPParallelMaskedTaskLoopSimdDirective(
       ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
       SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp distribute' after parsing
   /// of the associated statement.
   StmtResult
   ActOnOpenMPDistributeDirective(ArrayRef<OMPClause *> Clauses, Stmt *AStmt,
                                  SourceLocation StartLoc, SourceLocation EndLoc,
                                  VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp target update'.
   StmtResult ActOnOpenMPTargetUpdateDirective(ArrayRef<OMPClause *> Clauses,
                                               SourceLocation StartLoc,
                                               SourceLocation EndLoc,
                                               Stmt *AStmt);
   /// Called on well-formed '\#pragma omp distribute parallel for' after
   /// parsing of the associated statement.
   StmtResult ActOnOpenMPDistributeParallelForDirective(
       ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
       SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp distribute parallel for simd'
   /// after parsing of the associated statement.
   StmtResult ActOnOpenMPDistributeParallelForSimdDirective(
       ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
       SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp distribute simd' after
   /// parsing of the associated statement.
   StmtResult ActOnOpenMPDistributeSimdDirective(
       ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
       SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp target parallel for simd' after
   /// parsing of the associated statement.
   StmtResult ActOnOpenMPTargetParallelForSimdDirective(
       ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
       SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp target simd' after parsing of
   /// the associated statement.
   StmtResult
   ActOnOpenMPTargetSimdDirective(ArrayRef<OMPClause *> Clauses, Stmt *AStmt,
                                  SourceLocation StartLoc, SourceLocation EndLoc,
                                  VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp teams distribute' after parsing of
   /// the associated statement.
   StmtResult ActOnOpenMPTeamsDistributeDirective(
       ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
       SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp teams distribute simd' after parsing
   /// of the associated statement.
   StmtResult ActOnOpenMPTeamsDistributeSimdDirective(
       ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
       SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp teams distribute parallel for simd'
   /// after parsing of the associated statement.
   StmtResult ActOnOpenMPTeamsDistributeParallelForSimdDirective(
       ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
       SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp teams distribute parallel for'
   /// after parsing of the associated statement.
   StmtResult ActOnOpenMPTeamsDistributeParallelForDirective(
       ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
       SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp target teams' after parsing of the
   /// associated statement.
   StmtResult ActOnOpenMPTargetTeamsDirective(ArrayRef<OMPClause *> Clauses,
                                              Stmt *AStmt,
                                              SourceLocation StartLoc,
                                              SourceLocation EndLoc);
   /// Called on well-formed '\#pragma omp target teams distribute' after parsing
   /// of the associated statement.
   StmtResult ActOnOpenMPTargetTeamsDistributeDirective(
       ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
       SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp target teams distribute parallel for'
   /// after parsing of the associated statement.
   StmtResult ActOnOpenMPTargetTeamsDistributeParallelForDirective(
       ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
       SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp target teams distribute parallel for
   /// simd' after parsing of the associated statement.
   StmtResult ActOnOpenMPTargetTeamsDistributeParallelForSimdDirective(
       ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
       SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp target teams distribute simd' after
   /// parsing of the associated statement.
   StmtResult ActOnOpenMPTargetTeamsDistributeSimdDirective(
       ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
       SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
   /// Called on well-formed '\#pragma omp interop'.
   StmtResult ActOnOpenMPInteropDirective(ArrayRef<OMPClause *> Clauses,
                                          SourceLocation StartLoc,
                                          SourceLocation EndLoc);
   /// Called on well-formed '\#pragma omp dispatch' after parsing of the
   // /associated statement.
   StmtResult ActOnOpenMPDispatchDirective(ArrayRef<OMPClause *> Clauses,
                                           Stmt *AStmt, SourceLocation StartLoc,
                                           SourceLocation EndLoc);
   /// Called on well-formed '\#pragma omp masked' after parsing of the
   // /associated statement.
   StmtResult ActOnOpenMPMaskedDirective(ArrayRef<OMPClause *> Clauses,
                                         Stmt *AStmt, SourceLocation StartLoc,
                                         SourceLocation EndLoc);
 
   /// Called on well-formed '\#pragma omp loop' after parsing of the
   /// associated statement.
   StmtResult ActOnOpenMPGenericLoopDirective(
       ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
       SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
 
   /// Checks correctness of linear modifiers.
   bool CheckOpenMPLinearModifier(OpenMPLinearClauseKind LinKind,
                                  SourceLocation LinLoc);
   /// Checks that the specified declaration matches requirements for the linear
   /// decls.
   bool CheckOpenMPLinearDecl(const ValueDecl *D, SourceLocation ELoc,
                              OpenMPLinearClauseKind LinKind, QualType Type,
                              bool IsDeclareSimd = false);
 
   /// Called on well-formed '\#pragma omp declare simd' after parsing of
   /// the associated method/function.
   DeclGroupPtrTy ActOnOpenMPDeclareSimdDirective(
       DeclGroupPtrTy DG, OMPDeclareSimdDeclAttr::BranchStateTy BS,
       Expr *Simdlen, ArrayRef<Expr *> Uniforms, ArrayRef<Expr *> Aligneds,
       ArrayRef<Expr *> Alignments, ArrayRef<Expr *> Linears,
       ArrayRef<unsigned> LinModifiers, ArrayRef<Expr *> Steps, SourceRange SR);
 
   /// Checks '\#pragma omp declare variant' variant function and original
   /// functions after parsing of the associated method/function.
   /// \param DG Function declaration to which declare variant directive is
   /// applied to.
   /// \param VariantRef Expression that references the variant function, which
   /// must be used instead of the original one, specified in \p DG.
   /// \param TI The trait info object representing the match clause.
   /// \param NumAppendArgs The number of omp_interop_t arguments to account for
   /// in checking.
   /// \returns std::nullopt, if the function/variant function are not compatible
   /// with the pragma, pair of original function/variant ref expression
   /// otherwise.
   std::optional<std::pair<FunctionDecl *, Expr *>>
   checkOpenMPDeclareVariantFunction(DeclGroupPtrTy DG, Expr *VariantRef,
                                     OMPTraitInfo &TI, unsigned NumAppendArgs,
                                     SourceRange SR);
 
   /// Called on well-formed '\#pragma omp declare variant' after parsing of
   /// the associated method/function.
   /// \param FD Function declaration to which declare variant directive is
   /// applied to.
   /// \param VariantRef Expression that references the variant function, which
   /// must be used instead of the original one, specified in \p DG.
   /// \param TI The context traits associated with the function variant.
   /// \param AdjustArgsNothing The list of 'nothing' arguments.
   /// \param AdjustArgsNeedDevicePtr The list of 'need_device_ptr' arguments.
   /// \param AppendArgs The list of 'append_args' arguments.
   /// \param AdjustArgsLoc The Location of an 'adjust_args' clause.
   /// \param AppendArgsLoc The Location of an 'append_args' clause.
   /// \param SR The SourceRange of the 'declare variant' directive.
   void ActOnOpenMPDeclareVariantDirective(
       FunctionDecl *FD, Expr *VariantRef, OMPTraitInfo &TI,
       ArrayRef<Expr *> AdjustArgsNothing,
       ArrayRef<Expr *> AdjustArgsNeedDevicePtr,
       ArrayRef<OMPInteropInfo> AppendArgs, SourceLocation AdjustArgsLoc,
       SourceLocation AppendArgsLoc, SourceRange SR);
 
   OMPClause *ActOnOpenMPSingleExprClause(OpenMPClauseKind Kind,
                                          Expr *Expr,
                                          SourceLocation StartLoc,
                                          SourceLocation LParenLoc,
                                          SourceLocation EndLoc);
   /// Called on well-formed 'allocator' clause.
   OMPClause *ActOnOpenMPAllocatorClause(Expr *Allocator,
                                         SourceLocation StartLoc,
                                         SourceLocation LParenLoc,
                                         SourceLocation EndLoc);
   /// Called on well-formed 'if' clause.
   OMPClause *ActOnOpenMPIfClause(OpenMPDirectiveKind NameModifier,
                                  Expr *Condition, SourceLocation StartLoc,
                                  SourceLocation LParenLoc,
                                  SourceLocation NameModifierLoc,
                                  SourceLocation ColonLoc,
                                  SourceLocation EndLoc);
   /// Called on well-formed 'final' clause.
   OMPClause *ActOnOpenMPFinalClause(Expr *Condition, SourceLocation StartLoc,
                                     SourceLocation LParenLoc,
                                     SourceLocation EndLoc);
   /// Called on well-formed 'num_threads' clause.
   OMPClause *ActOnOpenMPNumThreadsClause(Expr *NumThreads,
                                          SourceLocation StartLoc,
                                          SourceLocation LParenLoc,
                                          SourceLocation EndLoc);
   /// Called on well-formed 'align' clause.
   OMPClause *ActOnOpenMPAlignClause(Expr *Alignment, SourceLocation StartLoc,
                                     SourceLocation LParenLoc,
                                     SourceLocation EndLoc);
   /// Called on well-formed 'safelen' clause.
   OMPClause *ActOnOpenMPSafelenClause(Expr *Length,
                                       SourceLocation StartLoc,
                                       SourceLocation LParenLoc,
                                       SourceLocation EndLoc);
   /// Called on well-formed 'simdlen' clause.
   OMPClause *ActOnOpenMPSimdlenClause(Expr *Length, SourceLocation StartLoc,
                                       SourceLocation LParenLoc,
                                       SourceLocation EndLoc);
   /// Called on well-form 'sizes' clause.
   OMPClause *ActOnOpenMPSizesClause(ArrayRef<Expr *> SizeExprs,
                                     SourceLocation StartLoc,
                                     SourceLocation LParenLoc,
                                     SourceLocation EndLoc);
   /// Called on well-form 'full' clauses.
   OMPClause *ActOnOpenMPFullClause(SourceLocation StartLoc,
                                    SourceLocation EndLoc);
   /// Called on well-form 'partial' clauses.
   OMPClause *ActOnOpenMPPartialClause(Expr *FactorExpr, SourceLocation StartLoc,
                                       SourceLocation LParenLoc,
                                       SourceLocation EndLoc);
   /// Called on well-formed 'collapse' clause.
   OMPClause *ActOnOpenMPCollapseClause(Expr *NumForLoops,
                                        SourceLocation StartLoc,
                                        SourceLocation LParenLoc,
                                        SourceLocation EndLoc);
   /// Called on well-formed 'ordered' clause.
   OMPClause *
   ActOnOpenMPOrderedClause(SourceLocation StartLoc, SourceLocation EndLoc,
                            SourceLocation LParenLoc = SourceLocation(),
                            Expr *NumForLoops = nullptr);
   /// Called on well-formed 'grainsize' clause.
   OMPClause *ActOnOpenMPGrainsizeClause(OpenMPGrainsizeClauseModifier Modifier,
                                         Expr *Size, SourceLocation StartLoc,
                                         SourceLocation LParenLoc,
                                         SourceLocation ModifierLoc,
                                         SourceLocation EndLoc);
   /// Called on well-formed 'num_tasks' clause.
   OMPClause *ActOnOpenMPNumTasksClause(OpenMPNumTasksClauseModifier Modifier,
                                        Expr *NumTasks, SourceLocation StartLoc,
                                        SourceLocation LParenLoc,
                                        SourceLocation ModifierLoc,
                                        SourceLocation EndLoc);
   /// Called on well-formed 'hint' clause.
   OMPClause *ActOnOpenMPHintClause(Expr *Hint, SourceLocation StartLoc,
                                    SourceLocation LParenLoc,
                                    SourceLocation EndLoc);
   /// Called on well-formed 'detach' clause.
   OMPClause *ActOnOpenMPDetachClause(Expr *Evt, SourceLocation StartLoc,
                                      SourceLocation LParenLoc,
                                      SourceLocation EndLoc);
 
   OMPClause *ActOnOpenMPSimpleClause(OpenMPClauseKind Kind,
                                      unsigned Argument,
                                      SourceLocation ArgumentLoc,
                                      SourceLocation StartLoc,
                                      SourceLocation LParenLoc,
                                      SourceLocation EndLoc);
   /// Called on well-formed 'when' clause.
   OMPClause *ActOnOpenMPWhenClause(OMPTraitInfo &TI, SourceLocation StartLoc,
                                    SourceLocation LParenLoc,
                                    SourceLocation EndLoc);
   /// Called on well-formed 'default' clause.
   OMPClause *ActOnOpenMPDefaultClause(llvm::omp::DefaultKind Kind,
                                       SourceLocation KindLoc,
                                       SourceLocation StartLoc,
                                       SourceLocation LParenLoc,
                                       SourceLocation EndLoc);
   /// Called on well-formed 'proc_bind' clause.
   OMPClause *ActOnOpenMPProcBindClause(llvm::omp::ProcBindKind Kind,
                                        SourceLocation KindLoc,
                                        SourceLocation StartLoc,
                                        SourceLocation LParenLoc,
                                        SourceLocation EndLoc);
   /// Called on well-formed 'order' clause.
   OMPClause *ActOnOpenMPOrderClause(OpenMPOrderClauseModifier Modifier,
                                     OpenMPOrderClauseKind Kind,
                                     SourceLocation StartLoc,
                                     SourceLocation LParenLoc,
                                     SourceLocation MLoc, SourceLocation KindLoc,
                                     SourceLocation EndLoc);
   /// Called on well-formed 'update' clause.
   OMPClause *ActOnOpenMPUpdateClause(OpenMPDependClauseKind Kind,
                                      SourceLocation KindLoc,
                                      SourceLocation StartLoc,
                                      SourceLocation LParenLoc,
                                      SourceLocation EndLoc);
 
   OMPClause *ActOnOpenMPSingleExprWithArgClause(
       OpenMPClauseKind Kind, ArrayRef<unsigned> Arguments, Expr *Expr,
       SourceLocation StartLoc, SourceLocation LParenLoc,
       ArrayRef<SourceLocation> ArgumentsLoc, SourceLocation DelimLoc,
       SourceLocation EndLoc);
   /// Called on well-formed 'schedule' clause.
   OMPClause *ActOnOpenMPScheduleClause(
       OpenMPScheduleClauseModifier M1, OpenMPScheduleClauseModifier M2,
       OpenMPScheduleClauseKind Kind, Expr *ChunkSize, SourceLocation StartLoc,
       SourceLocation LParenLoc, SourceLocation M1Loc, SourceLocation M2Loc,
       SourceLocation KindLoc, SourceLocation CommaLoc, SourceLocation EndLoc);
 
   OMPClause *ActOnOpenMPClause(OpenMPClauseKind Kind, SourceLocation StartLoc,
                                SourceLocation EndLoc);
   /// Called on well-formed 'nowait' clause.
   OMPClause *ActOnOpenMPNowaitClause(SourceLocation StartLoc,
                                      SourceLocation EndLoc);
   /// Called on well-formed 'untied' clause.
   OMPClause *ActOnOpenMPUntiedClause(SourceLocation StartLoc,
                                      SourceLocation EndLoc);
   /// Called on well-formed 'mergeable' clause.
   OMPClause *ActOnOpenMPMergeableClause(SourceLocation StartLoc,
                                         SourceLocation EndLoc);
   /// Called on well-formed 'read' clause.
   OMPClause *ActOnOpenMPReadClause(SourceLocation StartLoc,
                                    SourceLocation EndLoc);
   /// Called on well-formed 'write' clause.
   OMPClause *ActOnOpenMPWriteClause(SourceLocation StartLoc,
                                     SourceLocation EndLoc);
   /// Called on well-formed 'update' clause.
   OMPClause *ActOnOpenMPUpdateClause(SourceLocation StartLoc,
                                      SourceLocation EndLoc);
   /// Called on well-formed 'capture' clause.
   OMPClause *ActOnOpenMPCaptureClause(SourceLocation StartLoc,
                                       SourceLocation EndLoc);
   /// Called on well-formed 'compare' clause.
   OMPClause *ActOnOpenMPCompareClause(SourceLocation StartLoc,
                                       SourceLocation EndLoc);
   /// Called on well-formed 'seq_cst' clause.
   OMPClause *ActOnOpenMPSeqCstClause(SourceLocation StartLoc,
                                      SourceLocation EndLoc);
   /// Called on well-formed 'acq_rel' clause.
   OMPClause *ActOnOpenMPAcqRelClause(SourceLocation StartLoc,
                                      SourceLocation EndLoc);
   /// Called on well-formed 'acquire' clause.
   OMPClause *ActOnOpenMPAcquireClause(SourceLocation StartLoc,
                                       SourceLocation EndLoc);
   /// Called on well-formed 'release' clause.
   OMPClause *ActOnOpenMPReleaseClause(SourceLocation StartLoc,
                                       SourceLocation EndLoc);
   /// Called on well-formed 'relaxed' clause.
   OMPClause *ActOnOpenMPRelaxedClause(SourceLocation StartLoc,
                                       SourceLocation EndLoc);
 
   /// Called on well-formed 'init' clause.
   OMPClause *
   ActOnOpenMPInitClause(Expr *InteropVar, OMPInteropInfo &InteropInfo,
                         SourceLocation StartLoc, SourceLocation LParenLoc,
                         SourceLocation VarLoc, SourceLocation EndLoc);
 
   /// Called on well-formed 'use' clause.
   OMPClause *ActOnOpenMPUseClause(Expr *InteropVar, SourceLocation StartLoc,
                                   SourceLocation LParenLoc,
                                   SourceLocation VarLoc, SourceLocation EndLoc);
 
   /// Called on well-formed 'destroy' clause.
   OMPClause *ActOnOpenMPDestroyClause(Expr *InteropVar, SourceLocation StartLoc,
                                       SourceLocation LParenLoc,
                                       SourceLocation VarLoc,
                                       SourceLocation EndLoc);
   /// Called on well-formed 'novariants' clause.
   OMPClause *ActOnOpenMPNovariantsClause(Expr *Condition,
                                          SourceLocation StartLoc,
                                          SourceLocation LParenLoc,
                                          SourceLocation EndLoc);
   /// Called on well-formed 'nocontext' clause.
   OMPClause *ActOnOpenMPNocontextClause(Expr *Condition,
                                         SourceLocation StartLoc,
                                         SourceLocation LParenLoc,
                                         SourceLocation EndLoc);
   /// Called on well-formed 'filter' clause.
   OMPClause *ActOnOpenMPFilterClause(Expr *ThreadID, SourceLocation StartLoc,
                                      SourceLocation LParenLoc,
                                      SourceLocation EndLoc);
   /// Called on well-formed 'threads' clause.
   OMPClause *ActOnOpenMPThreadsClause(SourceLocation StartLoc,
                                       SourceLocation EndLoc);
   /// Called on well-formed 'simd' clause.
   OMPClause *ActOnOpenMPSIMDClause(SourceLocation StartLoc,
                                    SourceLocation EndLoc);
   /// Called on well-formed 'nogroup' clause.
   OMPClause *ActOnOpenMPNogroupClause(SourceLocation StartLoc,
                                       SourceLocation EndLoc);
   /// Called on well-formed 'unified_address' clause.
   OMPClause *ActOnOpenMPUnifiedAddressClause(SourceLocation StartLoc,
                                              SourceLocation EndLoc);
 
   /// Called on well-formed 'unified_address' clause.
   OMPClause *ActOnOpenMPUnifiedSharedMemoryClause(SourceLocation StartLoc,
                                                   SourceLocation EndLoc);
 
   /// Called on well-formed 'reverse_offload' clause.
   OMPClause *ActOnOpenMPReverseOffloadClause(SourceLocation StartLoc,
                                              SourceLocation EndLoc);
 
   /// Called on well-formed 'dynamic_allocators' clause.
   OMPClause *ActOnOpenMPDynamicAllocatorsClause(SourceLocation StartLoc,
                                                 SourceLocation EndLoc);
 
   /// Called on well-formed 'atomic_default_mem_order' clause.
   OMPClause *ActOnOpenMPAtomicDefaultMemOrderClause(
       OpenMPAtomicDefaultMemOrderClauseKind Kind, SourceLocation KindLoc,
       SourceLocation StartLoc, SourceLocation LParenLoc, SourceLocation EndLoc);
 
   /// Called on well-formed 'at' clause.
   OMPClause *ActOnOpenMPAtClause(OpenMPAtClauseKind Kind,
                                  SourceLocation KindLoc,
                                  SourceLocation StartLoc,
                                  SourceLocation LParenLoc,
                                  SourceLocation EndLoc);
 
   /// Called on well-formed 'severity' clause.
   OMPClause *ActOnOpenMPSeverityClause(OpenMPSeverityClauseKind Kind,
                                        SourceLocation KindLoc,
                                        SourceLocation StartLoc,
                                        SourceLocation LParenLoc,
                                        SourceLocation EndLoc);
 
   /// Called on well-formed 'message' clause.
   /// passing string for message.
   OMPClause *ActOnOpenMPMessageClause(Expr *MS, SourceLocation StartLoc,
                                       SourceLocation LParenLoc,
                                       SourceLocation EndLoc);
 
   /// Data used for processing a list of variables in OpenMP clauses.
   struct OpenMPVarListDataTy final {
     Expr *DepModOrTailExpr = nullptr;
     Expr *IteratorExpr = nullptr;
     SourceLocation ColonLoc;
     SourceLocation RLoc;
     CXXScopeSpec ReductionOrMapperIdScopeSpec;
     DeclarationNameInfo ReductionOrMapperId;
     int ExtraModifier = -1; ///< Additional modifier for linear, map, depend or
                             ///< lastprivate clause.
     SmallVector<OpenMPMapModifierKind, NumberOfOMPMapClauseModifiers>
         MapTypeModifiers;
     SmallVector<SourceLocation, NumberOfOMPMapClauseModifiers>
         MapTypeModifiersLoc;
     SmallVector<OpenMPMotionModifierKind, NumberOfOMPMotionModifiers>
         MotionModifiers;
     SmallVector<SourceLocation, NumberOfOMPMotionModifiers> MotionModifiersLoc;
     bool IsMapTypeImplicit = false;
     SourceLocation ExtraModifierLoc;
     SourceLocation OmpAllMemoryLoc;
   };
 
   OMPClause *ActOnOpenMPVarListClause(OpenMPClauseKind Kind,
                                       ArrayRef<Expr *> Vars,
                                       const OMPVarListLocTy &Locs,
                                       OpenMPVarListDataTy &Data);
   /// Called on well-formed 'inclusive' clause.
   OMPClause *ActOnOpenMPInclusiveClause(ArrayRef<Expr *> VarList,
                                         SourceLocation StartLoc,
                                         SourceLocation LParenLoc,
                                         SourceLocation EndLoc);
   /// Called on well-formed 'exclusive' clause.
   OMPClause *ActOnOpenMPExclusiveClause(ArrayRef<Expr *> VarList,
                                         SourceLocation StartLoc,
                                         SourceLocation LParenLoc,
                                         SourceLocation EndLoc);
   /// Called on well-formed 'allocate' clause.
   OMPClause *
   ActOnOpenMPAllocateClause(Expr *Allocator, ArrayRef<Expr *> VarList,
                             SourceLocation StartLoc, SourceLocation ColonLoc,
                             SourceLocation LParenLoc, SourceLocation EndLoc);
   /// Called on well-formed 'private' clause.
   OMPClause *ActOnOpenMPPrivateClause(ArrayRef<Expr *> VarList,
                                       SourceLocation StartLoc,
                                       SourceLocation LParenLoc,
                                       SourceLocation EndLoc);
   /// Called on well-formed 'firstprivate' clause.
   OMPClause *ActOnOpenMPFirstprivateClause(ArrayRef<Expr *> VarList,
                                            SourceLocation StartLoc,
                                            SourceLocation LParenLoc,
                                            SourceLocation EndLoc);
   /// Called on well-formed 'lastprivate' clause.
   OMPClause *ActOnOpenMPLastprivateClause(
       ArrayRef<Expr *> VarList, OpenMPLastprivateModifier LPKind,
       SourceLocation LPKindLoc, SourceLocation ColonLoc,
       SourceLocation StartLoc, SourceLocation LParenLoc, SourceLocation EndLoc);
   /// Called on well-formed 'shared' clause.
   OMPClause *ActOnOpenMPSharedClause(ArrayRef<Expr *> VarList,
                                      SourceLocation StartLoc,
                                      SourceLocation LParenLoc,
                                      SourceLocation EndLoc);
   /// Called on well-formed 'reduction' clause.
   OMPClause *ActOnOpenMPReductionClause(
       ArrayRef<Expr *> VarList, OpenMPReductionClauseModifier Modifier,
       SourceLocation StartLoc, SourceLocation LParenLoc,
       SourceLocation ModifierLoc, SourceLocation ColonLoc,
       SourceLocation EndLoc, CXXScopeSpec &ReductionIdScopeSpec,
       const DeclarationNameInfo &ReductionId,
       ArrayRef<Expr *> UnresolvedReductions = std::nullopt);
   /// Called on well-formed 'task_reduction' clause.
   OMPClause *ActOnOpenMPTaskReductionClause(
       ArrayRef<Expr *> VarList, SourceLocation StartLoc,
       SourceLocation LParenLoc, SourceLocation ColonLoc, SourceLocation EndLoc,
       CXXScopeSpec &ReductionIdScopeSpec,
       const DeclarationNameInfo &ReductionId,
       ArrayRef<Expr *> UnresolvedReductions = std::nullopt);
   /// Called on well-formed 'in_reduction' clause.
   OMPClause *ActOnOpenMPInReductionClause(
       ArrayRef<Expr *> VarList, SourceLocation StartLoc,
       SourceLocation LParenLoc, SourceLocation ColonLoc, SourceLocation EndLoc,
       CXXScopeSpec &ReductionIdScopeSpec,
       const DeclarationNameInfo &ReductionId,
       ArrayRef<Expr *> UnresolvedReductions = std::nullopt);
   /// Called on well-formed 'linear' clause.
   OMPClause *
   ActOnOpenMPLinearClause(ArrayRef<Expr *> VarList, Expr *Step,
                           SourceLocation StartLoc, SourceLocation LParenLoc,
                           OpenMPLinearClauseKind LinKind, SourceLocation LinLoc,
                           SourceLocation ColonLoc, SourceLocation EndLoc);
   /// Called on well-formed 'aligned' clause.
   OMPClause *ActOnOpenMPAlignedClause(ArrayRef<Expr *> VarList,
                                       Expr *Alignment,
                                       SourceLocation StartLoc,
                                       SourceLocation LParenLoc,
                                       SourceLocation ColonLoc,
                                       SourceLocation EndLoc);
   /// Called on well-formed 'copyin' clause.
   OMPClause *ActOnOpenMPCopyinClause(ArrayRef<Expr *> VarList,
                                      SourceLocation StartLoc,
                                      SourceLocation LParenLoc,
                                      SourceLocation EndLoc);
   /// Called on well-formed 'copyprivate' clause.
   OMPClause *ActOnOpenMPCopyprivateClause(ArrayRef<Expr *> VarList,
                                           SourceLocation StartLoc,
                                           SourceLocation LParenLoc,
                                           SourceLocation EndLoc);
   /// Called on well-formed 'flush' pseudo clause.
   OMPClause *ActOnOpenMPFlushClause(ArrayRef<Expr *> VarList,
                                     SourceLocation StartLoc,
                                     SourceLocation LParenLoc,
                                     SourceLocation EndLoc);
   /// Called on well-formed 'depobj' pseudo clause.
   OMPClause *ActOnOpenMPDepobjClause(Expr *Depobj, SourceLocation StartLoc,
                                      SourceLocation LParenLoc,
                                      SourceLocation EndLoc);
   /// Called on well-formed 'depend' clause.
   OMPClause *ActOnOpenMPDependClause(const OMPDependClause::DependDataTy &Data,
                                      Expr *DepModifier,
                                      ArrayRef<Expr *> VarList,
                                      SourceLocation StartLoc,
                                      SourceLocation LParenLoc,
                                      SourceLocation EndLoc);
   /// Called on well-formed 'device' clause.
   OMPClause *ActOnOpenMPDeviceClause(OpenMPDeviceClauseModifier Modifier,
                                      Expr *Device, SourceLocation StartLoc,
                                      SourceLocation LParenLoc,
                                      SourceLocation ModifierLoc,
                                      SourceLocation EndLoc);
   /// Called on well-formed 'map' clause.
   OMPClause *ActOnOpenMPMapClause(
       Expr *IteratorModifier, ArrayRef<OpenMPMapModifierKind> MapTypeModifiers,
       ArrayRef<SourceLocation> MapTypeModifiersLoc,
       CXXScopeSpec &MapperIdScopeSpec, DeclarationNameInfo &MapperId,
       OpenMPMapClauseKind MapType, bool IsMapTypeImplicit,
       SourceLocation MapLoc, SourceLocation ColonLoc, ArrayRef<Expr *> VarList,
       const OMPVarListLocTy &Locs, bool NoDiagnose = false,
       ArrayRef<Expr *> UnresolvedMappers = std::nullopt);
   /// Called on well-formed 'num_teams' clause.
   OMPClause *ActOnOpenMPNumTeamsClause(Expr *NumTeams, SourceLocation StartLoc,
                                        SourceLocation LParenLoc,
                                        SourceLocation EndLoc);
   /// Called on well-formed 'thread_limit' clause.
   OMPClause *ActOnOpenMPThreadLimitClause(Expr *ThreadLimit,
                                           SourceLocation StartLoc,
                                           SourceLocation LParenLoc,
                                           SourceLocation EndLoc);
   /// Called on well-formed 'priority' clause.
   OMPClause *ActOnOpenMPPriorityClause(Expr *Priority, SourceLocation StartLoc,
                                        SourceLocation LParenLoc,
                                        SourceLocation EndLoc);
   /// Called on well-formed 'dist_schedule' clause.
   OMPClause *ActOnOpenMPDistScheduleClause(
       OpenMPDistScheduleClauseKind Kind, Expr *ChunkSize,
       SourceLocation StartLoc, SourceLocation LParenLoc, SourceLocation KindLoc,
       SourceLocation CommaLoc, SourceLocation EndLoc);
   /// Called on well-formed 'defaultmap' clause.
   OMPClause *ActOnOpenMPDefaultmapClause(
       OpenMPDefaultmapClauseModifier M, OpenMPDefaultmapClauseKind Kind,
       SourceLocation StartLoc, SourceLocation LParenLoc, SourceLocation MLoc,
       SourceLocation KindLoc, SourceLocation EndLoc);
   /// Called on well-formed 'to' clause.
   OMPClause *
   ActOnOpenMPToClause(ArrayRef<OpenMPMotionModifierKind> MotionModifiers,
                       ArrayRef<SourceLocation> MotionModifiersLoc,
                       CXXScopeSpec &MapperIdScopeSpec,
                       DeclarationNameInfo &MapperId, SourceLocation ColonLoc,
                       ArrayRef<Expr *> VarList, const OMPVarListLocTy &Locs,
                       ArrayRef<Expr *> UnresolvedMappers = std::nullopt);
   /// Called on well-formed 'from' clause.
   OMPClause *
   ActOnOpenMPFromClause(ArrayRef<OpenMPMotionModifierKind> MotionModifiers,
                         ArrayRef<SourceLocation> MotionModifiersLoc,
                         CXXScopeSpec &MapperIdScopeSpec,
                         DeclarationNameInfo &MapperId, SourceLocation ColonLoc,
                         ArrayRef<Expr *> VarList, const OMPVarListLocTy &Locs,
                         ArrayRef<Expr *> UnresolvedMappers = std::nullopt);
   /// Called on well-formed 'use_device_ptr' clause.
   OMPClause *ActOnOpenMPUseDevicePtrClause(ArrayRef<Expr *> VarList,
                                            const OMPVarListLocTy &Locs);
   /// Called on well-formed 'use_device_addr' clause.
   OMPClause *ActOnOpenMPUseDeviceAddrClause(ArrayRef<Expr *> VarList,
                                             const OMPVarListLocTy &Locs);
   /// Called on well-formed 'is_device_ptr' clause.
   OMPClause *ActOnOpenMPIsDevicePtrClause(ArrayRef<Expr *> VarList,
                                           const OMPVarListLocTy &Locs);
   /// Called on well-formed 'has_device_addr' clause.
   OMPClause *ActOnOpenMPHasDeviceAddrClause(ArrayRef<Expr *> VarList,
                                             const OMPVarListLocTy &Locs);
   /// Called on well-formed 'nontemporal' clause.
   OMPClause *ActOnOpenMPNontemporalClause(ArrayRef<Expr *> VarList,
                                           SourceLocation StartLoc,
                                           SourceLocation LParenLoc,
                                           SourceLocation EndLoc);
 
   /// Data for list of allocators.
   struct UsesAllocatorsData {
     /// Allocator.
     Expr *Allocator = nullptr;
     /// Allocator traits.
     Expr *AllocatorTraits = nullptr;
     /// Locations of '(' and ')' symbols.
     SourceLocation LParenLoc, RParenLoc;
   };
   /// Called on well-formed 'uses_allocators' clause.
   OMPClause *ActOnOpenMPUsesAllocatorClause(SourceLocation StartLoc,
                                             SourceLocation LParenLoc,
                                             SourceLocation EndLoc,
                                             ArrayRef<UsesAllocatorsData> Data);
   /// Called on well-formed 'affinity' clause.
   OMPClause *ActOnOpenMPAffinityClause(SourceLocation StartLoc,
                                        SourceLocation LParenLoc,
                                        SourceLocation ColonLoc,
                                        SourceLocation EndLoc, Expr *Modifier,
                                        ArrayRef<Expr *> Locators);
   /// Called on a well-formed 'bind' clause.
   OMPClause *ActOnOpenMPBindClause(OpenMPBindClauseKind Kind,
                                    SourceLocation KindLoc,
                                    SourceLocation StartLoc,
                                    SourceLocation LParenLoc,
                                    SourceLocation EndLoc);
 
   /// Called on a well-formed 'ompx_dyn_cgroup_mem' clause.
   OMPClause *ActOnOpenMPXDynCGroupMemClause(Expr *Size, SourceLocation StartLoc,
                                             SourceLocation LParenLoc,
                                             SourceLocation EndLoc);
 
   /// Called on well-formed 'doacross' clause.
   OMPClause *
   ActOnOpenMPDoacrossClause(OpenMPDoacrossClauseModifier DepType,
                             SourceLocation DepLoc, SourceLocation ColonLoc,
                             ArrayRef<Expr *> VarList, SourceLocation StartLoc,
                             SourceLocation LParenLoc, SourceLocation EndLoc);
 
   /// The kind of conversion being performed.
   enum CheckedConversionKind {
     /// An implicit conversion.
     CCK_ImplicitConversion,
     /// A C-style cast.
     CCK_CStyleCast,
     /// A functional-style cast.
     CCK_FunctionalCast,
     /// A cast other than a C-style cast.
     CCK_OtherCast,
     /// A conversion for an operand of a builtin overloaded operator.
     CCK_ForBuiltinOverloadedOp
   };
 
   static bool isCast(CheckedConversionKind CCK) {
     return CCK == CCK_CStyleCast || CCK == CCK_FunctionalCast ||
            CCK == CCK_OtherCast;
   }
 
   /// ImpCastExprToType - If Expr is not of type 'Type', insert an implicit
   /// cast.  If there is already an implicit cast, merge into the existing one.
   /// If isLvalue, the result of the cast is an lvalue.
   ExprResult
   ImpCastExprToType(Expr *E, QualType Type, CastKind CK,
                     ExprValueKind VK = VK_PRValue,
                     const CXXCastPath *BasePath = nullptr,
                     CheckedConversionKind CCK = CCK_ImplicitConversion);
 
   /// ScalarTypeToBooleanCastKind - Returns the cast kind corresponding
   /// to the conversion from scalar type ScalarTy to the Boolean type.
   static CastKind ScalarTypeToBooleanCastKind(QualType ScalarTy);
 
   /// IgnoredValueConversions - Given that an expression's result is
   /// syntactically ignored, perform any conversions that are
   /// required.
   ExprResult IgnoredValueConversions(Expr *E);
 
   // UsualUnaryConversions - promotes integers (C99 6.3.1.1p2) and converts
   // functions and arrays to their respective pointers (C99 6.3.2.1).
   ExprResult UsualUnaryConversions(Expr *E);
 
   /// CallExprUnaryConversions - a special case of an unary conversion
   /// performed on a function designator of a call expression.
   ExprResult CallExprUnaryConversions(Expr *E);
 
   // DefaultFunctionArrayConversion - converts functions and arrays
   // to their respective pointers (C99 6.3.2.1).
   ExprResult DefaultFunctionArrayConversion(Expr *E, bool Diagnose = true);
 
   // DefaultFunctionArrayLvalueConversion - converts functions and
   // arrays to their respective pointers and performs the
   // lvalue-to-rvalue conversion.
   ExprResult DefaultFunctionArrayLvalueConversion(Expr *E,
                                                   bool Diagnose = true);
 
   // DefaultLvalueConversion - performs lvalue-to-rvalue conversion on
   // the operand. This function is a no-op if the operand has a function type
   // or an array type.
   ExprResult DefaultLvalueConversion(Expr *E);
 
   // DefaultArgumentPromotion (C99 6.5.2.2p6). Used for function calls that
   // do not have a prototype. Integer promotions are performed on each
   // argument, and arguments that have type float are promoted to double.
   ExprResult DefaultArgumentPromotion(Expr *E);
 
   /// If \p E is a prvalue denoting an unmaterialized temporary, materialize
   /// it as an xvalue. In C++98, the result will still be a prvalue, because
   /// we don't have xvalues there.
   ExprResult TemporaryMaterializationConversion(Expr *E);
 
   // Used for emitting the right warning by DefaultVariadicArgumentPromotion
   enum VariadicCallType {
     VariadicFunction,
     VariadicBlock,
     VariadicMethod,
     VariadicConstructor,
     VariadicDoesNotApply
   };
 
   VariadicCallType getVariadicCallType(FunctionDecl *FDecl,
                                        const FunctionProtoType *Proto,
                                        Expr *Fn);
 
   // Used for determining in which context a type is allowed to be passed to a
   // vararg function.
   enum VarArgKind {
     VAK_Valid,
     VAK_ValidInCXX11,
     VAK_Undefined,
     VAK_MSVCUndefined,
     VAK_Invalid
   };
 
   // Determines which VarArgKind fits an expression.
   VarArgKind isValidVarArgType(const QualType &Ty);
 
   /// Check to see if the given expression is a valid argument to a variadic
   /// function, issuing a diagnostic if not.
   void checkVariadicArgument(const Expr *E, VariadicCallType CT);
 
   /// Check whether the given statement can have musttail applied to it,
   /// issuing a diagnostic and returning false if not. In the success case,
   /// the statement is rewritten to remove implicit nodes from the return
   /// value.
   bool checkAndRewriteMustTailAttr(Stmt *St, const Attr &MTA);
 
 private:
   /// Check whether the given statement can have musttail applied to it,
   /// issuing a diagnostic and returning false if not.
   bool checkMustTailAttr(const Stmt *St, const Attr &MTA);
 
 public:
   /// Check to see if a given expression could have '.c_str()' called on it.
   bool hasCStrMethod(const Expr *E);
 
   /// GatherArgumentsForCall - Collector argument expressions for various
   /// form of call prototypes.
   bool GatherArgumentsForCall(SourceLocation CallLoc, FunctionDecl *FDecl,
                               const FunctionProtoType *Proto,
                               unsigned FirstParam, ArrayRef<Expr *> Args,
                               SmallVectorImpl<Expr *> &AllArgs,
                               VariadicCallType CallType = VariadicDoesNotApply,
                               bool AllowExplicit = false,
                               bool IsListInitialization = false);
 
   // DefaultVariadicArgumentPromotion - Like DefaultArgumentPromotion, but
   // will create a runtime trap if the resulting type is not a POD type.
   ExprResult DefaultVariadicArgumentPromotion(Expr *E, VariadicCallType CT,
                                               FunctionDecl *FDecl);
 
   /// Context in which we're performing a usual arithmetic conversion.
   enum ArithConvKind {
     /// An arithmetic operation.
     ACK_Arithmetic,
     /// A bitwise operation.
     ACK_BitwiseOp,
     /// A comparison.
     ACK_Comparison,
     /// A conditional (?:) operator.
     ACK_Conditional,
     /// A compound assignment expression.
     ACK_CompAssign,
   };
 
   // UsualArithmeticConversions - performs the UsualUnaryConversions on it's
   // operands and then handles various conversions that are common to binary
   // operators (C99 6.3.1.8). If both operands aren't arithmetic, this
   // routine returns the first non-arithmetic type found. The client is
   // responsible for emitting appropriate error diagnostics.
   QualType UsualArithmeticConversions(ExprResult &LHS, ExprResult &RHS,
                                       SourceLocation Loc, ArithConvKind ACK);
 
   /// AssignConvertType - All of the 'assignment' semantic checks return this
   /// enum to indicate whether the assignment was allowed.  These checks are
   /// done for simple assignments, as well as initialization, return from
   /// function, argument passing, etc.  The query is phrased in terms of a
   /// source and destination type.
   enum AssignConvertType {
     /// Compatible - the types are compatible according to the standard.
     Compatible,
 
     /// PointerToInt - The assignment converts a pointer to an int, which we
     /// accept as an extension.
     PointerToInt,
 
     /// IntToPointer - The assignment converts an int to a pointer, which we
     /// accept as an extension.
     IntToPointer,
 
     /// FunctionVoidPointer - The assignment is between a function pointer and
     /// void*, which the standard doesn't allow, but we accept as an extension.
     FunctionVoidPointer,
 
     /// IncompatiblePointer - The assignment is between two pointers types that
     /// are not compatible, but we accept them as an extension.
     IncompatiblePointer,
 
     /// IncompatibleFunctionPointer - The assignment is between two function
     /// pointers types that are not compatible, but we accept them as an
     /// extension.
     IncompatibleFunctionPointer,
 
     /// IncompatibleFunctionPointerStrict - The assignment is between two
     /// function pointer types that are not identical, but are compatible,
     /// unless compiled with -fsanitize=cfi, in which case the type mismatch
     /// may trip an indirect call runtime check.
     IncompatibleFunctionPointerStrict,
 
     /// IncompatiblePointerSign - The assignment is between two pointers types
     /// which point to integers which have a different sign, but are otherwise
     /// identical. This is a subset of the above, but broken out because it's by
     /// far the most common case of incompatible pointers.
     IncompatiblePointerSign,
 
     /// CompatiblePointerDiscardsQualifiers - The assignment discards
     /// c/v/r qualifiers, which we accept as an extension.
     CompatiblePointerDiscardsQualifiers,
 
     /// IncompatiblePointerDiscardsQualifiers - The assignment
     /// discards qualifiers that we don't permit to be discarded,
     /// like address spaces.
     IncompatiblePointerDiscardsQualifiers,
 
     /// IncompatibleNestedPointerAddressSpaceMismatch - The assignment
     /// changes address spaces in nested pointer types which is not allowed.
     /// For instance, converting __private int ** to __generic int ** is
     /// illegal even though __private could be converted to __generic.
     IncompatibleNestedPointerAddressSpaceMismatch,
 
     /// IncompatibleNestedPointerQualifiers - The assignment is between two
     /// nested pointer types, and the qualifiers other than the first two
     /// levels differ e.g. char ** -> const char **, but we accept them as an
     /// extension.
     IncompatibleNestedPointerQualifiers,
 
     /// IncompatibleVectors - The assignment is between two vector types that
     /// have the same size, which we accept as an extension.
     IncompatibleVectors,
 
     /// IntToBlockPointer - The assignment converts an int to a block
     /// pointer. We disallow this.
     IntToBlockPointer,
 
     /// IncompatibleBlockPointer - The assignment is between two block
     /// pointers types that are not compatible.
     IncompatibleBlockPointer,
 
     /// IncompatibleObjCQualifiedId - The assignment is between a qualified
     /// id type and something else (that is incompatible with it). For example,
     /// "id <XXX>" = "Foo *", where "Foo *" doesn't implement the XXX protocol.
     IncompatibleObjCQualifiedId,
 
     /// IncompatibleObjCWeakRef - Assigning a weak-unavailable object to an
     /// object with __weak qualifier.
     IncompatibleObjCWeakRef,
 
     /// Incompatible - We reject this conversion outright, it is invalid to
     /// represent it in the AST.
     Incompatible
   };
 
   /// DiagnoseAssignmentResult - Emit a diagnostic, if required, for the
   /// assignment conversion type specified by ConvTy.  This returns true if the
   /// conversion was invalid or false if the conversion was accepted.
   bool DiagnoseAssignmentResult(AssignConvertType ConvTy,
                                 SourceLocation Loc,
                                 QualType DstType, QualType SrcType,
                                 Expr *SrcExpr, AssignmentAction Action,
                                 bool *Complained = nullptr);
 
   /// IsValueInFlagEnum - Determine if a value is allowed as part of a flag
   /// enum. If AllowMask is true, then we also allow the complement of a valid
   /// value, to be used as a mask.
   bool IsValueInFlagEnum(const EnumDecl *ED, const llvm::APInt &Val,
                          bool AllowMask) const;
 
   /// DiagnoseAssignmentEnum - Warn if assignment to enum is a constant
   /// integer not in the range of enum values.
   void DiagnoseAssignmentEnum(QualType DstType, QualType SrcType,
                               Expr *SrcExpr);
 
   /// CheckAssignmentConstraints - Perform type checking for assignment,
   /// argument passing, variable initialization, and function return values.
   /// C99 6.5.16.
   AssignConvertType CheckAssignmentConstraints(SourceLocation Loc,
                                                QualType LHSType,
                                                QualType RHSType);
 
   /// Check assignment constraints and optionally prepare for a conversion of
   /// the RHS to the LHS type. The conversion is prepared for if ConvertRHS
   /// is true.
   AssignConvertType CheckAssignmentConstraints(QualType LHSType,
                                                ExprResult &RHS,
                                                CastKind &Kind,
                                                bool ConvertRHS = true);
 
   /// Check assignment constraints for an assignment of RHS to LHSType.
   ///
   /// \param LHSType The destination type for the assignment.
   /// \param RHS The source expression for the assignment.
   /// \param Diagnose If \c true, diagnostics may be produced when checking
   ///        for assignability. If a diagnostic is produced, \p RHS will be
   ///        set to ExprError(). Note that this function may still return
   ///        without producing a diagnostic, even for an invalid assignment.
   /// \param DiagnoseCFAudited If \c true, the target is a function parameter
   ///        in an audited Core Foundation API and does not need to be checked
   ///        for ARC retain issues.
   /// \param ConvertRHS If \c true, \p RHS will be updated to model the
   ///        conversions necessary to perform the assignment. If \c false,
   ///        \p Diagnose must also be \c false.
   AssignConvertType CheckSingleAssignmentConstraints(
       QualType LHSType, ExprResult &RHS, bool Diagnose = true,
       bool DiagnoseCFAudited = false, bool ConvertRHS = true);
 
   // If the lhs type is a transparent union, check whether we
   // can initialize the transparent union with the given expression.
   AssignConvertType CheckTransparentUnionArgumentConstraints(QualType ArgType,
                                                              ExprResult &RHS);
 
   bool IsStringLiteralToNonConstPointerConversion(Expr *From, QualType ToType);
 
   bool CheckExceptionSpecCompatibility(Expr *From, QualType ToType);
 
   ExprResult PerformImplicitConversion(Expr *From, QualType ToType,
                                        AssignmentAction Action,
                                        bool AllowExplicit = false);
   ExprResult PerformImplicitConversion(Expr *From, QualType ToType,
                                        const ImplicitConversionSequence& ICS,
                                        AssignmentAction Action,
                                        CheckedConversionKind CCK
                                           = CCK_ImplicitConversion);
   ExprResult PerformImplicitConversion(Expr *From, QualType ToType,
                                        const StandardConversionSequence& SCS,
                                        AssignmentAction Action,
                                        CheckedConversionKind CCK);
 
   ExprResult PerformQualificationConversion(
       Expr *E, QualType Ty, ExprValueKind VK = VK_PRValue,
       CheckedConversionKind CCK = CCK_ImplicitConversion);
 
   /// the following "Check" methods will return a valid/converted QualType
   /// or a null QualType (indicating an error diagnostic was issued).
 
   /// type checking binary operators (subroutines of CreateBuiltinBinOp).
   QualType InvalidOperands(SourceLocation Loc, ExprResult &LHS,
                            ExprResult &RHS);
   QualType InvalidLogicalVectorOperands(SourceLocation Loc, ExprResult &LHS,
                                  ExprResult &RHS);
   QualType CheckPointerToMemberOperands( // C++ 5.5
     ExprResult &LHS, ExprResult &RHS, ExprValueKind &VK,
     SourceLocation OpLoc, bool isIndirect);
   QualType CheckMultiplyDivideOperands( // C99 6.5.5
     ExprResult &LHS, ExprResult &RHS, SourceLocation Loc, bool IsCompAssign,
     bool IsDivide);
   QualType CheckRemainderOperands( // C99 6.5.5
     ExprResult &LHS, ExprResult &RHS, SourceLocation Loc,
     bool IsCompAssign = false);
   QualType CheckAdditionOperands( // C99 6.5.6
     ExprResult &LHS, ExprResult &RHS, SourceLocation Loc,
     BinaryOperatorKind Opc, QualType* CompLHSTy = nullptr);
   QualType CheckSubtractionOperands( // C99 6.5.6
     ExprResult &LHS, ExprResult &RHS, SourceLocation Loc,
     QualType* CompLHSTy = nullptr);
   QualType CheckShiftOperands( // C99 6.5.7
     ExprResult &LHS, ExprResult &RHS, SourceLocation Loc,
     BinaryOperatorKind Opc, bool IsCompAssign = false);
   void CheckPtrComparisonWithNullChar(ExprResult &E, ExprResult &NullE);
   QualType CheckCompareOperands( // C99 6.5.8/9
       ExprResult &LHS, ExprResult &RHS, SourceLocation Loc,
       BinaryOperatorKind Opc);
   QualType CheckBitwiseOperands( // C99 6.5.[10...12]
       ExprResult &LHS, ExprResult &RHS, SourceLocation Loc,
       BinaryOperatorKind Opc);
   QualType CheckLogicalOperands( // C99 6.5.[13,14]
     ExprResult &LHS, ExprResult &RHS, SourceLocation Loc,
     BinaryOperatorKind Opc);
   // CheckAssignmentOperands is used for both simple and compound assignment.
   // For simple assignment, pass both expressions and a null converted type.
   // For compound assignment, pass both expressions and the converted type.
   QualType CheckAssignmentOperands( // C99 6.5.16.[1,2]
       Expr *LHSExpr, ExprResult &RHS, SourceLocation Loc, QualType CompoundType,
       BinaryOperatorKind Opc);
 
   ExprResult checkPseudoObjectIncDec(Scope *S, SourceLocation OpLoc,
                                      UnaryOperatorKind Opcode, Expr *Op);
   ExprResult checkPseudoObjectAssignment(Scope *S, SourceLocation OpLoc,
                                          BinaryOperatorKind Opcode,
                                          Expr *LHS, Expr *RHS);
   ExprResult checkPseudoObjectRValue(Expr *E);
   Expr *recreateSyntacticForm(PseudoObjectExpr *E);
 
   QualType CheckConditionalOperands( // C99 6.5.15
     ExprResult &Cond, ExprResult &LHS, ExprResult &RHS,
     ExprValueKind &VK, ExprObjectKind &OK, SourceLocation QuestionLoc);
   QualType CXXCheckConditionalOperands( // C++ 5.16
     ExprResult &cond, ExprResult &lhs, ExprResult &rhs,
     ExprValueKind &VK, ExprObjectKind &OK, SourceLocation questionLoc);
   QualType CheckVectorConditionalTypes(ExprResult &Cond, ExprResult &LHS,
                                        ExprResult &RHS,
                                        SourceLocation QuestionLoc);
 
   QualType CheckSizelessVectorConditionalTypes(ExprResult &Cond,
                                                ExprResult &LHS, ExprResult &RHS,
                                                SourceLocation QuestionLoc);
   QualType FindCompositePointerType(SourceLocation Loc, Expr *&E1, Expr *&E2,
                                     bool ConvertArgs = true);
   QualType FindCompositePointerType(SourceLocation Loc,
                                     ExprResult &E1, ExprResult &E2,
                                     bool ConvertArgs = true) {
     Expr *E1Tmp = E1.get(), *E2Tmp = E2.get();
     QualType Composite =
         FindCompositePointerType(Loc, E1Tmp, E2Tmp, ConvertArgs);
     E1 = E1Tmp;
     E2 = E2Tmp;
     return Composite;
   }
 
   QualType FindCompositeObjCPointerType(ExprResult &LHS, ExprResult &RHS,
                                         SourceLocation QuestionLoc);
 
   bool DiagnoseConditionalForNull(Expr *LHSExpr, Expr *RHSExpr,
                                   SourceLocation QuestionLoc);
 
   void DiagnoseAlwaysNonNullPointer(Expr *E,
                                     Expr::NullPointerConstantKind NullType,
                                     bool IsEqual, SourceRange Range);
 
   /// type checking for vector binary operators.
   QualType CheckVectorOperands(ExprResult &LHS, ExprResult &RHS,
                                SourceLocation Loc, bool IsCompAssign,
                                bool AllowBothBool, bool AllowBoolConversion,
                                bool AllowBoolOperation, bool ReportInvalid);
   QualType GetSignedVectorType(QualType V);
   QualType GetSignedSizelessVectorType(QualType V);
   QualType CheckVectorCompareOperands(ExprResult &LHS, ExprResult &RHS,
                                       SourceLocation Loc,
                                       BinaryOperatorKind Opc);
   QualType CheckSizelessVectorCompareOperands(ExprResult &LHS, ExprResult &RHS,
                                               SourceLocation Loc,
                                               BinaryOperatorKind Opc);
   QualType CheckVectorLogicalOperands(ExprResult &LHS, ExprResult &RHS,
                                       SourceLocation Loc);
 
   // type checking for sizeless vector binary operators.
   QualType CheckSizelessVectorOperands(ExprResult &LHS, ExprResult &RHS,
                                        SourceLocation Loc, bool IsCompAssign,
                                        ArithConvKind OperationKind);
 
   /// Type checking for matrix binary operators.
   QualType CheckMatrixElementwiseOperands(ExprResult &LHS, ExprResult &RHS,
                                           SourceLocation Loc,
                                           bool IsCompAssign);
   QualType CheckMatrixMultiplyOperands(ExprResult &LHS, ExprResult &RHS,
                                        SourceLocation Loc, bool IsCompAssign);
 
   bool isValidSveBitcast(QualType srcType, QualType destType);
   bool isValidRVVBitcast(QualType srcType, QualType destType);
 
   bool areMatrixTypesOfTheSameDimension(QualType srcTy, QualType destTy);
 
   bool areVectorTypesSameSize(QualType srcType, QualType destType);
   bool areLaxCompatibleVectorTypes(QualType srcType, QualType destType);
   bool isLaxVectorConversion(QualType srcType, QualType destType);
   bool anyAltivecTypes(QualType srcType, QualType destType);
 
   /// type checking declaration initializers (C99 6.7.8)
   bool CheckForConstantInitializer(Expr *e, QualType t);
 
   // type checking C++ declaration initializers (C++ [dcl.init]).
 
   /// ReferenceCompareResult - Expresses the result of comparing two
   /// types (cv1 T1 and cv2 T2) to determine their compatibility for the
   /// purposes of initialization by reference (C++ [dcl.init.ref]p4).
   enum ReferenceCompareResult {
     /// Ref_Incompatible - The two types are incompatible, so direct
     /// reference binding is not possible.
     Ref_Incompatible = 0,
     /// Ref_Related - The two types are reference-related, which means
     /// that their unqualified forms (T1 and T2) are either the same
     /// or T1 is a base class of T2.
     Ref_Related,
     /// Ref_Compatible - The two types are reference-compatible.
     Ref_Compatible
   };
 
   // Fake up a scoped enumeration that still contextually converts to bool.
   struct ReferenceConversionsScope {
     /// The conversions that would be performed on an lvalue of type T2 when
     /// binding a reference of type T1 to it, as determined when evaluating
     /// whether T1 is reference-compatible with T2.
     enum ReferenceConversions {
       Qualification = 0x1,
       NestedQualification = 0x2,
       Function = 0x4,
       DerivedToBase = 0x8,
       ObjC = 0x10,
       ObjCLifetime = 0x20,
 
       LLVM_MARK_AS_BITMASK_ENUM(/*LargestValue=*/ObjCLifetime)
     };
   };
   using ReferenceConversions = ReferenceConversionsScope::ReferenceConversions;
 
   ReferenceCompareResult
   CompareReferenceRelationship(SourceLocation Loc, QualType T1, QualType T2,
                                ReferenceConversions *Conv = nullptr);
 
   ExprResult checkUnknownAnyCast(SourceRange TypeRange, QualType CastType,
                                  Expr *CastExpr, CastKind &CastKind,
                                  ExprValueKind &VK, CXXCastPath &Path);
 
   /// Force an expression with unknown-type to an expression of the
   /// given type.
   ExprResult forceUnknownAnyToType(Expr *E, QualType ToType);
 
   /// Type-check an expression that's being passed to an
   /// __unknown_anytype parameter.
   ExprResult checkUnknownAnyArg(SourceLocation callLoc,
                                 Expr *result, QualType &paramType);
 
   // CheckMatrixCast - Check type constraints for matrix casts.
   // We allow casting between matrixes of the same dimensions i.e. when they
   // have the same number of rows and column. Returns true if the cast is
   // invalid.
   bool CheckMatrixCast(SourceRange R, QualType DestTy, QualType SrcTy,
                        CastKind &Kind);
 
   // CheckVectorCast - check type constraints for vectors.
   // Since vectors are an extension, there are no C standard reference for this.
   // We allow casting between vectors and integer datatypes of the same size.
   // returns true if the cast is invalid
   bool CheckVectorCast(SourceRange R, QualType VectorTy, QualType Ty,
                        CastKind &Kind);
 
   /// Prepare `SplattedExpr` for a vector splat operation, adding
   /// implicit casts if necessary.
   ExprResult prepareVectorSplat(QualType VectorTy, Expr *SplattedExpr);
 
   // CheckExtVectorCast - check type constraints for extended vectors.
   // Since vectors are an extension, there are no C standard reference for this.
   // We allow casting between vectors and integer datatypes of the same size,
   // or vectors and the element type of that vector.
   // returns the cast expr
   ExprResult CheckExtVectorCast(SourceRange R, QualType DestTy, Expr *CastExpr,
                                 CastKind &Kind);
 
   ExprResult BuildCXXFunctionalCastExpr(TypeSourceInfo *TInfo, QualType Type,
                                         SourceLocation LParenLoc,
                                         Expr *CastExpr,
                                         SourceLocation RParenLoc);
 
   enum ARCConversionResult { ACR_okay, ACR_unbridged, ACR_error };
 
   /// Checks for invalid conversions and casts between
   /// retainable pointers and other pointer kinds for ARC and Weak.
   ARCConversionResult CheckObjCConversion(SourceRange castRange,
                                           QualType castType, Expr *&op,
                                           CheckedConversionKind CCK,
                                           bool Diagnose = true,
                                           bool DiagnoseCFAudited = false,
                                           BinaryOperatorKind Opc = BO_PtrMemD
                                           );
 
   Expr *stripARCUnbridgedCast(Expr *e);
   void diagnoseARCUnbridgedCast(Expr *e);
 
   bool CheckObjCARCUnavailableWeakConversion(QualType castType,
                                              QualType ExprType);
 
   /// checkRetainCycles - Check whether an Objective-C message send
   /// might create an obvious retain cycle.
   void checkRetainCycles(ObjCMessageExpr *msg);
   void checkRetainCycles(Expr *receiver, Expr *argument);
   void checkRetainCycles(VarDecl *Var, Expr *Init);
 
   /// checkUnsafeAssigns - Check whether +1 expr is being assigned
   /// to weak/__unsafe_unretained type.
   bool checkUnsafeAssigns(SourceLocation Loc, QualType LHS, Expr *RHS);
 
   /// checkUnsafeExprAssigns - Check whether +1 expr is being assigned
   /// to weak/__unsafe_unretained expression.
   void checkUnsafeExprAssigns(SourceLocation Loc, Expr *LHS, Expr *RHS);
 
   /// CheckMessageArgumentTypes - Check types in an Obj-C message send.
   /// \param Method - May be null.
   /// \param [out] ReturnType - The return type of the send.
   /// \return true iff there were any incompatible types.
   bool CheckMessageArgumentTypes(const Expr *Receiver, QualType ReceiverType,
                                  MultiExprArg Args, Selector Sel,
                                  ArrayRef<SourceLocation> SelectorLocs,
                                  ObjCMethodDecl *Method, bool isClassMessage,
                                  bool isSuperMessage, SourceLocation lbrac,
                                  SourceLocation rbrac, SourceRange RecRange,
                                  QualType &ReturnType, ExprValueKind &VK);
 
   /// Determine the result of a message send expression based on
   /// the type of the receiver, the method expected to receive the message,
   /// and the form of the message send.
   QualType getMessageSendResultType(const Expr *Receiver, QualType ReceiverType,
                                     ObjCMethodDecl *Method, bool isClassMessage,
                                     bool isSuperMessage);
 
   /// If the given expression involves a message send to a method
   /// with a related result type, emit a note describing what happened.
   void EmitRelatedResultTypeNote(const Expr *E);
 
   /// Given that we had incompatible pointer types in a return
   /// statement, check whether we're in a method with a related result
   /// type, and if so, emit a note describing what happened.
   void EmitRelatedResultTypeNoteForReturn(QualType destType);
 
   class ConditionResult {
     Decl *ConditionVar;
     FullExprArg Condition;
     bool Invalid;
     std::optional<bool> KnownValue;
 
     friend class Sema;
     ConditionResult(Sema &S, Decl *ConditionVar, FullExprArg Condition,
                     bool IsConstexpr)
         : ConditionVar(ConditionVar), Condition(Condition), Invalid(false) {
       if (IsConstexpr && Condition.get()) {
         if (std::optional<llvm::APSInt> Val =
                 Condition.get()->getIntegerConstantExpr(S.Context)) {
           KnownValue = !!(*Val);
         }
       }
     }
     explicit ConditionResult(bool Invalid)
         : ConditionVar(nullptr), Condition(nullptr), Invalid(Invalid),
           KnownValue(std::nullopt) {}
 
   public:
     ConditionResult() : ConditionResult(false) {}
     bool isInvalid() const { return Invalid; }
     std::pair<VarDecl *, Expr *> get() const {
       return std::make_pair(cast_or_null<VarDecl>(ConditionVar),
                             Condition.get());
     }
     std::optional<bool> getKnownValue() const { return KnownValue; }
   };
   static ConditionResult ConditionError() { return ConditionResult(true); }
 
   enum class ConditionKind {
     Boolean,     ///< A boolean condition, from 'if', 'while', 'for', or 'do'.
     ConstexprIf, ///< A constant boolean condition from 'if constexpr'.
     Switch       ///< An integral condition for a 'switch' statement.
   };
   QualType PreferredConditionType(ConditionKind K) const {
     return K == ConditionKind::Switch ? Context.IntTy : Context.BoolTy;
   }
 
   ConditionResult ActOnCondition(Scope *S, SourceLocation Loc, Expr *SubExpr,
                                  ConditionKind CK, bool MissingOK = false);
 
   ConditionResult ActOnConditionVariable(Decl *ConditionVar,
                                          SourceLocation StmtLoc,
                                          ConditionKind CK);
 
   DeclResult ActOnCXXConditionDeclaration(Scope *S, Declarator &D);
 
   ExprResult CheckConditionVariable(VarDecl *ConditionVar,
                                     SourceLocation StmtLoc,
                                     ConditionKind CK);
   ExprResult CheckSwitchCondition(SourceLocation SwitchLoc, Expr *Cond);
 
   /// CheckBooleanCondition - Diagnose problems involving the use of
   /// the given expression as a boolean condition (e.g. in an if
   /// statement).  Also performs the standard function and array
   /// decays, possibly changing the input variable.
   ///
   /// \param Loc - A location associated with the condition, e.g. the
   /// 'if' keyword.
   /// \return true iff there were any errors
   ExprResult CheckBooleanCondition(SourceLocation Loc, Expr *E,
                                    bool IsConstexpr = false);
 
   /// ActOnExplicitBoolSpecifier - Build an ExplicitSpecifier from an expression
   /// found in an explicit(bool) specifier.
   ExplicitSpecifier ActOnExplicitBoolSpecifier(Expr *E);
 
   /// tryResolveExplicitSpecifier - Attempt to resolve the explict specifier.
   /// Returns true if the explicit specifier is now resolved.
   bool tryResolveExplicitSpecifier(ExplicitSpecifier &ExplicitSpec);
 
   /// DiagnoseAssignmentAsCondition - Given that an expression is
   /// being used as a boolean condition, warn if it's an assignment.
   void DiagnoseAssignmentAsCondition(Expr *E);
 
   /// Redundant parentheses over an equality comparison can indicate
   /// that the user intended an assignment used as condition.
   void DiagnoseEqualityWithExtraParens(ParenExpr *ParenE);
 
   /// CheckCXXBooleanCondition - Returns true if conversion to bool is invalid.
   ExprResult CheckCXXBooleanCondition(Expr *CondExpr, bool IsConstexpr = false);
 
   /// Checks that the Objective-C declaration is declared in the global scope.
   /// Emits an error and marks the declaration as invalid if it's not declared
   /// in the global scope.
   bool CheckObjCDeclScope(Decl *D);
 
   /// Abstract base class used for diagnosing integer constant
   /// expression violations.
   class VerifyICEDiagnoser {
   public:
     bool Suppress;
 
     VerifyICEDiagnoser(bool Suppress = false) : Suppress(Suppress) { }
 
     virtual SemaDiagnosticBuilder
     diagnoseNotICEType(Sema &S, SourceLocation Loc, QualType T);
     virtual SemaDiagnosticBuilder diagnoseNotICE(Sema &S,
                                                  SourceLocation Loc) = 0;
     virtual SemaDiagnosticBuilder diagnoseFold(Sema &S, SourceLocation Loc);
     virtual ~VerifyICEDiagnoser() {}
   };
 
   enum AllowFoldKind {
     NoFold,
     AllowFold,
   };
 
   /// VerifyIntegerConstantExpression - Verifies that an expression is an ICE,
   /// and reports the appropriate diagnostics. Returns false on success.
   /// Can optionally return the value of the expression.
   ExprResult VerifyIntegerConstantExpression(Expr *E, llvm::APSInt *Result,
                                              VerifyICEDiagnoser &Diagnoser,
                                              AllowFoldKind CanFold = NoFold);
   ExprResult VerifyIntegerConstantExpression(Expr *E, llvm::APSInt *Result,
                                              unsigned DiagID,
                                              AllowFoldKind CanFold = NoFold);
   ExprResult VerifyIntegerConstantExpression(Expr *E,
                                              llvm::APSInt *Result = nullptr,
                                              AllowFoldKind CanFold = NoFold);
   ExprResult VerifyIntegerConstantExpression(Expr *E,
                                              AllowFoldKind CanFold = NoFold) {
     return VerifyIntegerConstantExpression(E, nullptr, CanFold);
   }
 
   /// VerifyBitField - verifies that a bit field expression is an ICE and has
   /// the correct width, and that the field type is valid.
   /// Returns false on success.
   ExprResult VerifyBitField(SourceLocation FieldLoc, IdentifierInfo *FieldName,
                             QualType FieldTy, bool IsMsStruct, Expr *BitWidth);
 
 private:
   unsigned ForceCUDAHostDeviceDepth = 0;
 
 public:
   /// Increments our count of the number of times we've seen a pragma forcing
   /// functions to be __host__ __device__.  So long as this count is greater
   /// than zero, all functions encountered will be __host__ __device__.
   void PushForceCUDAHostDevice();
 
   /// Decrements our count of the number of times we've seen a pragma forcing
   /// functions to be __host__ __device__.  Returns false if the count is 0
   /// before incrementing, so you can emit an error.
   bool PopForceCUDAHostDevice();
 
   /// Diagnostics that are emitted only if we discover that the given function
   /// must be codegen'ed.  Because handling these correctly adds overhead to
   /// compilation, this is currently only enabled for CUDA compilations.
   llvm::DenseMap<CanonicalDeclPtr<const FunctionDecl>,
                  std::vector<PartialDiagnosticAt>>
       DeviceDeferredDiags;
 
   /// A pair of a canonical FunctionDecl and a SourceLocation.  When used as the
   /// key in a hashtable, both the FD and location are hashed.
   struct FunctionDeclAndLoc {
     CanonicalDeclPtr<const FunctionDecl> FD;
     SourceLocation Loc;
   };
 
   /// FunctionDecls and SourceLocations for which CheckCUDACall has emitted a
   /// (maybe deferred) "bad call" diagnostic.  We use this to avoid emitting the
   /// same deferred diag twice.
   llvm::DenseSet<FunctionDeclAndLoc> LocsWithCUDACallDiags;
 
   /// An inverse call graph, mapping known-emitted functions to one of their
   /// known-emitted callers (plus the location of the call).
   ///
   /// Functions that we can tell a priori must be emitted aren't added to this
   /// map.
   llvm::DenseMap</* Callee = */ CanonicalDeclPtr<const FunctionDecl>,
                  /* Caller = */ FunctionDeclAndLoc>
       DeviceKnownEmittedFns;
 
   /// Creates a SemaDiagnosticBuilder that emits the diagnostic if the current
   /// context is "used as device code".
   ///
   /// - If CurContext is a __host__ function, does not emit any diagnostics
   ///   unless \p EmitOnBothSides is true.
   /// - If CurContext is a __device__ or __global__ function, emits the
   ///   diagnostics immediately.
   /// - If CurContext is a __host__ __device__ function and we are compiling for
   ///   the device, creates a diagnostic which is emitted if and when we realize
   ///   that the function will be codegen'ed.
   ///
   /// Example usage:
   ///
   ///  // Variable-length arrays are not allowed in CUDA device code.
   ///  if (CUDADiagIfDeviceCode(Loc, diag::err_cuda_vla) << CurrentCUDATarget())
   ///    return ExprError();
   ///  // Otherwise, continue parsing as normal.
   SemaDiagnosticBuilder CUDADiagIfDeviceCode(SourceLocation Loc,
                                              unsigned DiagID);
 
   /// Creates a SemaDiagnosticBuilder that emits the diagnostic if the current
   /// context is "used as host code".
   ///
   /// Same as CUDADiagIfDeviceCode, with "host" and "device" switched.
   SemaDiagnosticBuilder CUDADiagIfHostCode(SourceLocation Loc, unsigned DiagID);
 
   /// Creates a SemaDiagnosticBuilder that emits the diagnostic if the current
   /// context is "used as device code".
   ///
   /// - If CurContext is a `declare target` function or it is known that the
   /// function is emitted for the device, emits the diagnostics immediately.
   /// - If CurContext is a non-`declare target` function and we are compiling
   ///   for the device, creates a diagnostic which is emitted if and when we
   ///   realize that the function will be codegen'ed.
   ///
   /// Example usage:
   ///
   ///  // Variable-length arrays are not allowed in NVPTX device code.
   ///  if (diagIfOpenMPDeviceCode(Loc, diag::err_vla_unsupported))
   ///    return ExprError();
   ///  // Otherwise, continue parsing as normal.
   SemaDiagnosticBuilder diagIfOpenMPDeviceCode(SourceLocation Loc,
                                                unsigned DiagID,
                                                const FunctionDecl *FD);
 
   /// Creates a SemaDiagnosticBuilder that emits the diagnostic if the current
   /// context is "used as host code".
   ///
   /// - If CurContext is a `declare target` function or it is known that the
   /// function is emitted for the host, emits the diagnostics immediately.
   /// - If CurContext is a non-host function, just ignore it.
   ///
   /// Example usage:
   ///
   ///  // Variable-length arrays are not allowed in NVPTX device code.
   ///  if (diagIfOpenMPHostode(Loc, diag::err_vla_unsupported))
   ///    return ExprError();
   ///  // Otherwise, continue parsing as normal.
   SemaDiagnosticBuilder diagIfOpenMPHostCode(SourceLocation Loc,
                                              unsigned DiagID,
                                              const FunctionDecl *FD);
 
   SemaDiagnosticBuilder targetDiag(SourceLocation Loc, unsigned DiagID,
                                    const FunctionDecl *FD = nullptr);
   SemaDiagnosticBuilder targetDiag(SourceLocation Loc,
                                    const PartialDiagnostic &PD,
                                    const FunctionDecl *FD = nullptr) {
     return targetDiag(Loc, PD.getDiagID(), FD) << PD;
   }
 
   /// Check if the type is allowed to be used for the current target.
   void checkTypeSupport(QualType Ty, SourceLocation Loc,
                         ValueDecl *D = nullptr);
 
   enum CUDAFunctionTarget {
     CFT_Device,
     CFT_Global,
     CFT_Host,
     CFT_HostDevice,
     CFT_InvalidTarget
   };
 
   /// Determines whether the given function is a CUDA device/host/kernel/etc.
   /// function.
   ///
   /// Use this rather than examining the function's attributes yourself -- you
   /// will get it wrong.  Returns CFT_Host if D is null.
   CUDAFunctionTarget IdentifyCUDATarget(const FunctionDecl *D,
                                         bool IgnoreImplicitHDAttr = false);
   CUDAFunctionTarget IdentifyCUDATarget(const ParsedAttributesView &Attrs);
 
   enum CUDAVariableTarget {
     CVT_Device,  /// Emitted on device side with a shadow variable on host side
     CVT_Host,    /// Emitted on host side only
     CVT_Both,    /// Emitted on both sides with different addresses
     CVT_Unified, /// Emitted as a unified address, e.g. managed variables
   };
   /// Determines whether the given variable is emitted on host or device side.
   CUDAVariableTarget IdentifyCUDATarget(const VarDecl *D);
 
   /// Gets the CUDA target for the current context.
   CUDAFunctionTarget CurrentCUDATarget() {
     return IdentifyCUDATarget(dyn_cast<FunctionDecl>(CurContext));
   }
 
   static bool isCUDAImplicitHostDeviceFunction(const FunctionDecl *D);
 
   // CUDA function call preference. Must be ordered numerically from
   // worst to best.
   enum CUDAFunctionPreference {
     CFP_Never,      // Invalid caller/callee combination.
     CFP_WrongSide,  // Calls from host-device to host or device
                     // function that do not match current compilation
                     // mode.
     CFP_HostDevice, // Any calls to host/device functions.
     CFP_SameSide,   // Calls from host-device to host or device
                     // function matching current compilation mode.
     CFP_Native,     // host-to-host or device-to-device calls.
   };
 
   /// Identifies relative preference of a given Caller/Callee
   /// combination, based on their host/device attributes.
   /// \param Caller function which needs address of \p Callee.
   ///               nullptr in case of global context.
   /// \param Callee target function
   ///
   /// \returns preference value for particular Caller/Callee combination.
   CUDAFunctionPreference IdentifyCUDAPreference(const FunctionDecl *Caller,
                                                 const FunctionDecl *Callee);
 
   /// Determines whether Caller may invoke Callee, based on their CUDA
   /// host/device attributes.  Returns false if the call is not allowed.
   ///
   /// Note: Will return true for CFP_WrongSide calls.  These may appear in
   /// semantically correct CUDA programs, but only if they're never codegen'ed.
   bool IsAllowedCUDACall(const FunctionDecl *Caller,
                          const FunctionDecl *Callee) {
     return IdentifyCUDAPreference(Caller, Callee) != CFP_Never;
   }
 
   /// May add implicit CUDAHostAttr and CUDADeviceAttr attributes to FD,
   /// depending on FD and the current compilation settings.
   void maybeAddCUDAHostDeviceAttrs(FunctionDecl *FD,
                                    const LookupResult &Previous);
 
   /// May add implicit CUDAConstantAttr attribute to VD, depending on VD
   /// and current compilation settings.
   void MaybeAddCUDAConstantAttr(VarDecl *VD);
 
 public:
   /// Check whether we're allowed to call Callee from the current context.
   ///
   /// - If the call is never allowed in a semantically-correct program
   ///   (CFP_Never), emits an error and returns false.
   ///
   /// - If the call is allowed in semantically-correct programs, but only if
   ///   it's never codegen'ed (CFP_WrongSide), creates a deferred diagnostic to
   ///   be emitted if and when the caller is codegen'ed, and returns true.
   ///
   ///   Will only create deferred diagnostics for a given SourceLocation once,
   ///   so you can safely call this multiple times without generating duplicate
   ///   deferred errors.
   ///
   /// - Otherwise, returns true without emitting any diagnostics.
   bool CheckCUDACall(SourceLocation Loc, FunctionDecl *Callee);
 
   void CUDACheckLambdaCapture(CXXMethodDecl *D, const sema::Capture &Capture);
 
   /// Set __device__ or __host__ __device__ attributes on the given lambda
   /// operator() method.
   ///
   /// CUDA lambdas by default is host device function unless it has explicit
   /// host or device attribute.
   void CUDASetLambdaAttrs(CXXMethodDecl *Method);
 
   /// Finds a function in \p Matches with highest calling priority
   /// from \p Caller context and erases all functions with lower
   /// calling priority.
   void EraseUnwantedCUDAMatches(
       const FunctionDecl *Caller,
       SmallVectorImpl<std::pair<DeclAccessPair, FunctionDecl *>> &Matches);
 
   /// Given a implicit special member, infer its CUDA target from the
   /// calls it needs to make to underlying base/field special members.
   /// \param ClassDecl the class for which the member is being created.
   /// \param CSM the kind of special member.
   /// \param MemberDecl the special member itself.
   /// \param ConstRHS true if this is a copy operation with a const object on
   ///        its RHS.
   /// \param Diagnose true if this call should emit diagnostics.
   /// \return true if there was an error inferring.
   /// The result of this call is implicit CUDA target attribute(s) attached to
   /// the member declaration.
   bool inferCUDATargetForImplicitSpecialMember(CXXRecordDecl *ClassDecl,
                                                CXXSpecialMember CSM,
                                                CXXMethodDecl *MemberDecl,
                                                bool ConstRHS,
                                                bool Diagnose);
 
   /// \return true if \p CD can be considered empty according to CUDA
   /// (E.2.3.1 in CUDA 7.5 Programming guide).
   bool isEmptyCudaConstructor(SourceLocation Loc, CXXConstructorDecl *CD);
   bool isEmptyCudaDestructor(SourceLocation Loc, CXXDestructorDecl *CD);
 
   // \brief Checks that initializers of \p Var satisfy CUDA restrictions. In
   // case of error emits appropriate diagnostic and invalidates \p Var.
   //
   // \details CUDA allows only empty constructors as initializers for global
   // variables (see E.2.3.1, CUDA 7.5). The same restriction also applies to all
   // __shared__ variables whether they are local or not (they all are implicitly
   // static in CUDA). One exception is that CUDA allows constant initializers
   // for __constant__ and __device__ variables.
   void checkAllowedCUDAInitializer(VarDecl *VD);
 
   /// Check whether NewFD is a valid overload for CUDA. Emits
   /// diagnostics and invalidates NewFD if not.
   void checkCUDATargetOverload(FunctionDecl *NewFD,
                                const LookupResult &Previous);
   /// Copies target attributes from the template TD to the function FD.
   void inheritCUDATargetAttrs(FunctionDecl *FD, const FunctionTemplateDecl &TD);
 
   /// Returns the name of the launch configuration function.  This is the name
   /// of the function that will be called to configure kernel call, with the
   /// parameters specified via <<<>>>.
   std::string getCudaConfigureFuncName() const;
 
   /// \name Code completion
   //@{
   /// Describes the context in which code completion occurs.
   enum ParserCompletionContext {
     /// Code completion occurs at top-level or namespace context.
     PCC_Namespace,
     /// Code completion occurs within a class, struct, or union.
     PCC_Class,
     /// Code completion occurs within an Objective-C interface, protocol,
     /// or category.
     PCC_ObjCInterface,
     /// Code completion occurs within an Objective-C implementation or
     /// category implementation
     PCC_ObjCImplementation,
     /// Code completion occurs within the list of instance variables
     /// in an Objective-C interface, protocol, category, or implementation.
     PCC_ObjCInstanceVariableList,
     /// Code completion occurs following one or more template
     /// headers.
     PCC_Template,
     /// Code completion occurs following one or more template
     /// headers within a class.
     PCC_MemberTemplate,
     /// Code completion occurs within an expression.
     PCC_Expression,
     /// Code completion occurs within a statement, which may
     /// also be an expression or a declaration.
     PCC_Statement,
     /// Code completion occurs at the beginning of the
     /// initialization statement (or expression) in a for loop.
     PCC_ForInit,
     /// Code completion occurs within the condition of an if,
     /// while, switch, or for statement.
     PCC_Condition,
     /// Code completion occurs within the body of a function on a
     /// recovery path, where we do not have a specific handle on our position
     /// in the grammar.
     PCC_RecoveryInFunction,
     /// Code completion occurs where only a type is permitted.
     PCC_Type,
     /// Code completion occurs in a parenthesized expression, which
     /// might also be a type cast.
     PCC_ParenthesizedExpression,
     /// Code completion occurs within a sequence of declaration
     /// specifiers within a function, method, or block.
     PCC_LocalDeclarationSpecifiers
   };
 
   void CodeCompleteModuleImport(SourceLocation ImportLoc, ModuleIdPath Path);
   void CodeCompleteOrdinaryName(Scope *S,
                                 ParserCompletionContext CompletionContext);
   void CodeCompleteDeclSpec(Scope *S, DeclSpec &DS,
                             bool AllowNonIdentifiers,
                             bool AllowNestedNameSpecifiers);
 
   struct CodeCompleteExpressionData;
   void CodeCompleteExpression(Scope *S,
                               const CodeCompleteExpressionData &Data);
   void CodeCompleteExpression(Scope *S, QualType PreferredType,
                               bool IsParenthesized = false);
   void CodeCompleteMemberReferenceExpr(Scope *S, Expr *Base, Expr *OtherOpBase,
                                        SourceLocation OpLoc, bool IsArrow,
                                        bool IsBaseExprStatement,
                                        QualType PreferredType);
   void CodeCompletePostfixExpression(Scope *S, ExprResult LHS,
                                      QualType PreferredType);
   void CodeCompleteTag(Scope *S, unsigned TagSpec);
   void CodeCompleteTypeQualifiers(DeclSpec &DS);
   void CodeCompleteFunctionQualifiers(DeclSpec &DS, Declarator &D,
                                       const VirtSpecifiers *VS = nullptr);
   void CodeCompleteBracketDeclarator(Scope *S);
   void CodeCompleteCase(Scope *S);
   enum class AttributeCompletion {
     Attribute,
     Scope,
     None,
   };
   void CodeCompleteAttribute(
       AttributeCommonInfo::Syntax Syntax,
       AttributeCompletion Completion = AttributeCompletion::Attribute,
       const IdentifierInfo *Scope = nullptr);
   /// Determines the preferred type of the current function argument, by
   /// examining the signatures of all possible overloads.
   /// Returns null if unknown or ambiguous, or if code completion is off.
   ///
   /// If the code completion point has been reached, also reports the function
   /// signatures that were considered.
   ///
   /// FIXME: rename to GuessCallArgumentType to reduce confusion.
   QualType ProduceCallSignatureHelp(Expr *Fn, ArrayRef<Expr *> Args,
                                     SourceLocation OpenParLoc);
   QualType ProduceConstructorSignatureHelp(QualType Type, SourceLocation Loc,
                                            ArrayRef<Expr *> Args,
                                            SourceLocation OpenParLoc,
                                            bool Braced);
   QualType ProduceCtorInitMemberSignatureHelp(
       Decl *ConstructorDecl, CXXScopeSpec SS, ParsedType TemplateTypeTy,
       ArrayRef<Expr *> ArgExprs, IdentifierInfo *II, SourceLocation OpenParLoc,
       bool Braced);
   QualType ProduceTemplateArgumentSignatureHelp(
       TemplateTy, ArrayRef<ParsedTemplateArgument>, SourceLocation LAngleLoc);
   void CodeCompleteInitializer(Scope *S, Decl *D);
   /// Trigger code completion for a record of \p BaseType. \p InitExprs are
   /// expressions in the initializer list seen so far and \p D is the current
   /// Designation being parsed.
   void CodeCompleteDesignator(const QualType BaseType,
                               llvm::ArrayRef<Expr *> InitExprs,
                               const Designation &D);
   void CodeCompleteAfterIf(Scope *S, bool IsBracedThen);
 
   void CodeCompleteQualifiedId(Scope *S, CXXScopeSpec &SS, bool EnteringContext,
                                bool IsUsingDeclaration, QualType BaseType,
                                QualType PreferredType);
   void CodeCompleteUsing(Scope *S);
   void CodeCompleteUsingDirective(Scope *S);
   void CodeCompleteNamespaceDecl(Scope *S);
   void CodeCompleteNamespaceAliasDecl(Scope *S);
   void CodeCompleteOperatorName(Scope *S);
   void CodeCompleteConstructorInitializer(
                                 Decl *Constructor,
                                 ArrayRef<CXXCtorInitializer *> Initializers);
 
   void CodeCompleteLambdaIntroducer(Scope *S, LambdaIntroducer &Intro,
                                     bool AfterAmpersand);
   void CodeCompleteAfterFunctionEquals(Declarator &D);
 
   void CodeCompleteObjCAtDirective(Scope *S);
   void CodeCompleteObjCAtVisibility(Scope *S);
   void CodeCompleteObjCAtStatement(Scope *S);
   void CodeCompleteObjCAtExpression(Scope *S);
   void CodeCompleteObjCPropertyFlags(Scope *S, ObjCDeclSpec &ODS);
   void CodeCompleteObjCPropertyGetter(Scope *S);
   void CodeCompleteObjCPropertySetter(Scope *S);
   void CodeCompleteObjCPassingType(Scope *S, ObjCDeclSpec &DS,
                                    bool IsParameter);
   void CodeCompleteObjCMessageReceiver(Scope *S);
   void CodeCompleteObjCSuperMessage(Scope *S, SourceLocation SuperLoc,
                                     ArrayRef<IdentifierInfo *> SelIdents,
                                     bool AtArgumentExpression);
   void CodeCompleteObjCClassMessage(Scope *S, ParsedType Receiver,
                                     ArrayRef<IdentifierInfo *> SelIdents,
                                     bool AtArgumentExpression,
                                     bool IsSuper = false);
   void CodeCompleteObjCInstanceMessage(Scope *S, Expr *Receiver,
                                        ArrayRef<IdentifierInfo *> SelIdents,
                                        bool AtArgumentExpression,
                                        ObjCInterfaceDecl *Super = nullptr);
   void CodeCompleteObjCForCollection(Scope *S,
                                      DeclGroupPtrTy IterationVar);
   void CodeCompleteObjCSelector(Scope *S,
                                 ArrayRef<IdentifierInfo *> SelIdents);
   void CodeCompleteObjCProtocolReferences(
                                          ArrayRef<IdentifierLocPair> Protocols);
   void CodeCompleteObjCProtocolDecl(Scope *S);
   void CodeCompleteObjCInterfaceDecl(Scope *S);
   void CodeCompleteObjCClassForwardDecl(Scope *S);
   void CodeCompleteObjCSuperclass(Scope *S,
                                   IdentifierInfo *ClassName,
                                   SourceLocation ClassNameLoc);
   void CodeCompleteObjCImplementationDecl(Scope *S);
   void CodeCompleteObjCInterfaceCategory(Scope *S,
                                          IdentifierInfo *ClassName,
                                          SourceLocation ClassNameLoc);
   void CodeCompleteObjCImplementationCategory(Scope *S,
                                               IdentifierInfo *ClassName,
                                               SourceLocation ClassNameLoc);
   void CodeCompleteObjCPropertyDefinition(Scope *S);
   void CodeCompleteObjCPropertySynthesizeIvar(Scope *S,
                                               IdentifierInfo *PropertyName);
   void CodeCompleteObjCMethodDecl(Scope *S,
                                   std::optional<bool> IsInstanceMethod,
                                   ParsedType ReturnType);
   void CodeCompleteObjCMethodDeclSelector(Scope *S,
                                           bool IsInstanceMethod,
                                           bool AtParameterName,
                                           ParsedType ReturnType,
                                           ArrayRef<IdentifierInfo *> SelIdents);
   void CodeCompleteObjCClassPropertyRefExpr(Scope *S, IdentifierInfo &ClassName,
                                             SourceLocation ClassNameLoc,
                                             bool IsBaseExprStatement);
   void CodeCompletePreprocessorDirective(bool InConditional);
   void CodeCompleteInPreprocessorConditionalExclusion(Scope *S);
   void CodeCompletePreprocessorMacroName(bool IsDefinition);
   void CodeCompletePreprocessorExpression();
   void CodeCompletePreprocessorMacroArgument(Scope *S,
                                              IdentifierInfo *Macro,
                                              MacroInfo *MacroInfo,
                                              unsigned Argument);
   void CodeCompleteIncludedFile(llvm::StringRef Dir, bool IsAngled);
   void CodeCompleteNaturalLanguage();
   void CodeCompleteAvailabilityPlatformName();
   void GatherGlobalCodeCompletions(CodeCompletionAllocator &Allocator,
                                    CodeCompletionTUInfo &CCTUInfo,
                   SmallVectorImpl<CodeCompletionResult> &Results);
   //@}
 
   //===--------------------------------------------------------------------===//
   // Extra semantic analysis beyond the C type system
 
 public:
   SourceLocation getLocationOfStringLiteralByte(const StringLiteral *SL,
                                                 unsigned ByteNo) const;
 
   enum FormatArgumentPassingKind {
     FAPK_Fixed,    // values to format are fixed (no C-style variadic arguments)
     FAPK_Variadic, // values to format are passed as variadic arguments
     FAPK_VAList,   // values to format are passed in a va_list
   };
 
   // Used to grab the relevant information from a FormatAttr and a
   // FunctionDeclaration.
   struct FormatStringInfo {
     unsigned FormatIdx;
     unsigned FirstDataArg;
     FormatArgumentPassingKind ArgPassingKind;
   };
 
   static bool getFormatStringInfo(const FormatAttr *Format, bool IsCXXMember,
                                   bool IsVariadic, FormatStringInfo *FSI);
 
 private:
   void CheckArrayAccess(const Expr *BaseExpr, const Expr *IndexExpr,
                         const ArraySubscriptExpr *ASE = nullptr,
                         bool AllowOnePastEnd = true, bool IndexNegated = false);
   void CheckArrayAccess(const Expr *E);
 
   bool CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall,
                          const FunctionProtoType *Proto);
   bool CheckObjCMethodCall(ObjCMethodDecl *Method, SourceLocation loc,
                            ArrayRef<const Expr *> Args);
   bool CheckPointerCall(NamedDecl *NDecl, CallExpr *TheCall,
                         const FunctionProtoType *Proto);
   bool CheckOtherCall(CallExpr *TheCall, const FunctionProtoType *Proto);
   void CheckConstructorCall(FunctionDecl *FDecl, QualType ThisType,
                             ArrayRef<const Expr *> Args,
                             const FunctionProtoType *Proto, SourceLocation Loc);
 
   void checkAIXMemberAlignment(SourceLocation Loc, const Expr *Arg);
 
   void CheckArgAlignment(SourceLocation Loc, NamedDecl *FDecl,
                          StringRef ParamName, QualType ArgTy, QualType ParamTy);
 
   void checkCall(NamedDecl *FDecl, const FunctionProtoType *Proto,
                  const Expr *ThisArg, ArrayRef<const Expr *> Args,
                  bool IsMemberFunction, SourceLocation Loc, SourceRange Range,
                  VariadicCallType CallType);
 
   bool CheckObjCString(Expr *Arg);
   ExprResult CheckOSLogFormatStringArg(Expr *Arg);
 
   ExprResult CheckBuiltinFunctionCall(FunctionDecl *FDecl,
                                       unsigned BuiltinID, CallExpr *TheCall);
 
   bool CheckTSBuiltinFunctionCall(const TargetInfo &TI, unsigned BuiltinID,
                                   CallExpr *TheCall);
 
   void checkFortifiedBuiltinMemoryFunction(FunctionDecl *FD, CallExpr *TheCall);
 
   bool CheckARMBuiltinExclusiveCall(unsigned BuiltinID, CallExpr *TheCall,
                                     unsigned MaxWidth);
   bool CheckNeonBuiltinFunctionCall(const TargetInfo &TI, unsigned BuiltinID,
                                     CallExpr *TheCall);
   bool CheckMVEBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall);
   bool CheckSVEBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall);
   bool CheckCDEBuiltinFunctionCall(const TargetInfo &TI, unsigned BuiltinID,
                                    CallExpr *TheCall);
   bool CheckARMCoprocessorImmediate(const TargetInfo &TI, const Expr *CoprocArg,
                                     bool WantCDE);
   bool CheckARMBuiltinFunctionCall(const TargetInfo &TI, unsigned BuiltinID,
                                    CallExpr *TheCall);
 
   bool CheckAArch64BuiltinFunctionCall(const TargetInfo &TI, unsigned BuiltinID,
                                        CallExpr *TheCall);
   bool CheckBPFBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall);
   bool CheckHexagonBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall);
   bool CheckHexagonBuiltinArgument(unsigned BuiltinID, CallExpr *TheCall);
   bool CheckMipsBuiltinFunctionCall(const TargetInfo &TI, unsigned BuiltinID,
                                     CallExpr *TheCall);
   bool CheckMipsBuiltinCpu(const TargetInfo &TI, unsigned BuiltinID,
                            CallExpr *TheCall);
   bool CheckMipsBuiltinArgument(unsigned BuiltinID, CallExpr *TheCall);
   bool CheckSystemZBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall);
   bool CheckX86BuiltinRoundingOrSAE(unsigned BuiltinID, CallExpr *TheCall);
   bool CheckX86BuiltinGatherScatterScale(unsigned BuiltinID, CallExpr *TheCall);
   bool CheckX86BuiltinTileArguments(unsigned BuiltinID, CallExpr *TheCall);
   bool CheckX86BuiltinTileArgumentsRange(CallExpr *TheCall,
                                          ArrayRef<int> ArgNums);
   bool CheckX86BuiltinTileDuplicate(CallExpr *TheCall, ArrayRef<int> ArgNums);
   bool CheckX86BuiltinTileRangeAndDuplicate(CallExpr *TheCall,
                                             ArrayRef<int> ArgNums);
   bool CheckX86BuiltinFunctionCall(const TargetInfo &TI, unsigned BuiltinID,
                                    CallExpr *TheCall);
   bool CheckPPCBuiltinFunctionCall(const TargetInfo &TI, unsigned BuiltinID,
                                    CallExpr *TheCall);
   bool CheckAMDGCNBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall);
   bool CheckRISCVLMUL(CallExpr *TheCall, unsigned ArgNum);
   bool CheckRISCVBuiltinFunctionCall(const TargetInfo &TI, unsigned BuiltinID,
                                      CallExpr *TheCall);
   void checkRVVTypeSupport(QualType Ty, SourceLocation Loc, ValueDecl *D);
   bool CheckLoongArchBuiltinFunctionCall(const TargetInfo &TI,
                                          unsigned BuiltinID, CallExpr *TheCall);
   bool CheckWebAssemblyBuiltinFunctionCall(const TargetInfo &TI,
                                            unsigned BuiltinID,
                                            CallExpr *TheCall);
   bool CheckNVPTXBuiltinFunctionCall(const TargetInfo &TI, unsigned BuiltinID,
                                      CallExpr *TheCall);
 
   bool SemaBuiltinVAStart(unsigned BuiltinID, CallExpr *TheCall);
   bool SemaBuiltinVAStartARMMicrosoft(CallExpr *Call);
   bool SemaBuiltinUnorderedCompare(CallExpr *TheCall);
   bool SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs);
   bool SemaBuiltinComplex(CallExpr *TheCall);
   bool SemaBuiltinVSX(CallExpr *TheCall);
   bool SemaBuiltinOSLogFormat(CallExpr *TheCall);
   bool SemaValueIsRunOfOnes(CallExpr *TheCall, unsigned ArgNum);
 
 public:
   // Used by C++ template instantiation.
   ExprResult SemaBuiltinShuffleVector(CallExpr *TheCall);
   ExprResult SemaConvertVectorExpr(Expr *E, TypeSourceInfo *TInfo,
                                    SourceLocation BuiltinLoc,
                                    SourceLocation RParenLoc);
 
 private:
   bool SemaBuiltinPrefetch(CallExpr *TheCall);
   bool SemaBuiltinAllocaWithAlign(CallExpr *TheCall);
   bool SemaBuiltinArithmeticFence(CallExpr *TheCall);
   bool SemaBuiltinAssume(CallExpr *TheCall);
   bool SemaBuiltinAssumeAligned(CallExpr *TheCall);
   bool SemaBuiltinLongjmp(CallExpr *TheCall);
   bool SemaBuiltinSetjmp(CallExpr *TheCall);
   ExprResult SemaBuiltinAtomicOverloaded(ExprResult TheCallResult);
   ExprResult SemaBuiltinNontemporalOverloaded(ExprResult TheCallResult);
   ExprResult SemaAtomicOpsOverloaded(ExprResult TheCallResult,
                                      AtomicExpr::AtomicOp Op);
   ExprResult SemaBuiltinOperatorNewDeleteOverloaded(ExprResult TheCallResult,
                                                     bool IsDelete);
   bool SemaBuiltinConstantArg(CallExpr *TheCall, int ArgNum,
                               llvm::APSInt &Result);
   bool SemaBuiltinConstantArgRange(CallExpr *TheCall, int ArgNum, int Low,
                                    int High, bool RangeIsError = true);
   bool SemaBuiltinConstantArgMultiple(CallExpr *TheCall, int ArgNum,
                                       unsigned Multiple);
   bool SemaBuiltinConstantArgPower2(CallExpr *TheCall, int ArgNum);
   bool SemaBuiltinConstantArgShiftedByte(CallExpr *TheCall, int ArgNum,
                                          unsigned ArgBits);
   bool SemaBuiltinConstantArgShiftedByteOrXXFF(CallExpr *TheCall, int ArgNum,
                                                unsigned ArgBits);
   bool SemaBuiltinARMSpecialReg(unsigned BuiltinID, CallExpr *TheCall,
                                 int ArgNum, unsigned ExpectedFieldNum,
                                 bool AllowName);
   bool SemaBuiltinARMMemoryTaggingCall(unsigned BuiltinID, CallExpr *TheCall);
   bool SemaBuiltinPPCMMACall(CallExpr *TheCall, unsigned BuiltinID,
                              const char *TypeDesc);
 
   bool CheckPPCMMAType(QualType Type, SourceLocation TypeLoc);
 
   bool SemaBuiltinElementwiseMath(CallExpr *TheCall);
   bool SemaBuiltinElementwiseTernaryMath(CallExpr *TheCall);
   bool PrepareBuiltinElementwiseMathOneArgCall(CallExpr *TheCall);
   bool PrepareBuiltinReduceMathOneArgCall(CallExpr *TheCall);
 
   bool SemaBuiltinNonDeterministicValue(CallExpr *TheCall);
 
   // Matrix builtin handling.
   ExprResult SemaBuiltinMatrixTranspose(CallExpr *TheCall,
                                         ExprResult CallResult);
   ExprResult SemaBuiltinMatrixColumnMajorLoad(CallExpr *TheCall,
                                               ExprResult CallResult);
   ExprResult SemaBuiltinMatrixColumnMajorStore(CallExpr *TheCall,
                                                ExprResult CallResult);
 
   // WebAssembly builtin handling.
   bool BuiltinWasmRefNullExtern(CallExpr *TheCall);
   bool BuiltinWasmRefNullFunc(CallExpr *TheCall);
   bool BuiltinWasmTableGet(CallExpr *TheCall);
   bool BuiltinWasmTableSet(CallExpr *TheCall);
   bool BuiltinWasmTableSize(CallExpr *TheCall);
   bool BuiltinWasmTableGrow(CallExpr *TheCall);
   bool BuiltinWasmTableFill(CallExpr *TheCall);
   bool BuiltinWasmTableCopy(CallExpr *TheCall);
 
 public:
   enum FormatStringType {
     FST_Scanf,
     FST_Printf,
     FST_NSString,
     FST_Strftime,
     FST_Strfmon,
     FST_Kprintf,
     FST_FreeBSDKPrintf,
     FST_OSTrace,
     FST_OSLog,
     FST_Unknown
   };
   static FormatStringType GetFormatStringType(const FormatAttr *Format);
 
   bool FormatStringHasSArg(const StringLiteral *FExpr);
 
   static bool GetFormatNSStringIdx(const FormatAttr *Format, unsigned &Idx);
 
 private:
   bool CheckFormatArguments(const FormatAttr *Format,
                             ArrayRef<const Expr *> Args, bool IsCXXMember,
                             VariadicCallType CallType, SourceLocation Loc,
                             SourceRange Range,
                             llvm::SmallBitVector &CheckedVarArgs);
   bool CheckFormatArguments(ArrayRef<const Expr *> Args,
                             FormatArgumentPassingKind FAPK, unsigned format_idx,
                             unsigned firstDataArg, FormatStringType Type,
                             VariadicCallType CallType, SourceLocation Loc,
                             SourceRange range,
                             llvm::SmallBitVector &CheckedVarArgs);
 
   void CheckAbsoluteValueFunction(const CallExpr *Call,
                                   const FunctionDecl *FDecl);
 
   void CheckMaxUnsignedZero(const CallExpr *Call, const FunctionDecl *FDecl);
 
   void CheckMemaccessArguments(const CallExpr *Call,
                                unsigned BId,
                                IdentifierInfo *FnName);
 
   void CheckStrlcpycatArguments(const CallExpr *Call,
                                 IdentifierInfo *FnName);
 
   void CheckStrncatArguments(const CallExpr *Call,
                              IdentifierInfo *FnName);
 
   void CheckFreeArguments(const CallExpr *E);
 
   void CheckReturnValExpr(Expr *RetValExp, QualType lhsType,
                           SourceLocation ReturnLoc,
                           bool isObjCMethod = false,
                           const AttrVec *Attrs = nullptr,
                           const FunctionDecl *FD = nullptr);
 
 public:
   void CheckFloatComparison(SourceLocation Loc, Expr *LHS, Expr *RHS,
                             BinaryOperatorKind Opcode);
 
 private:
   void CheckImplicitConversions(Expr *E, SourceLocation CC = SourceLocation());
   void CheckBoolLikeConversion(Expr *E, SourceLocation CC);
   void CheckForIntOverflow(const Expr *E);
   void CheckUnsequencedOperations(const Expr *E);
 
   /// Perform semantic checks on a completed expression. This will either
   /// be a full-expression or a default argument expression.
   void CheckCompletedExpr(Expr *E, SourceLocation CheckLoc = SourceLocation(),
                           bool IsConstexpr = false);
 
   void CheckBitFieldInitialization(SourceLocation InitLoc, FieldDecl *Field,
                                    Expr *Init);
 
   /// Check if there is a field shadowing.
   void CheckShadowInheritedFields(const SourceLocation &Loc,
                                   DeclarationName FieldName,
                                   const CXXRecordDecl *RD,
                                   bool DeclIsField = true);
 
   /// Check if the given expression contains 'break' or 'continue'
   /// statement that produces control flow different from GCC.
   void CheckBreakContinueBinding(Expr *E);
 
   /// Check whether receiver is mutable ObjC container which
   /// attempts to add itself into the container
   void CheckObjCCircularContainer(ObjCMessageExpr *Message);
 
   void CheckTCBEnforcement(const SourceLocation CallExprLoc,
                            const NamedDecl *Callee);
 
   void AnalyzeDeleteExprMismatch(const CXXDeleteExpr *DE);
   void AnalyzeDeleteExprMismatch(FieldDecl *Field, SourceLocation DeleteLoc,
                                  bool DeleteWasArrayForm);
 public:
   /// Register a magic integral constant to be used as a type tag.
   void RegisterTypeTagForDatatype(const IdentifierInfo *ArgumentKind,
                                   uint64_t MagicValue, QualType Type,
                                   bool LayoutCompatible, bool MustBeNull);
 
   struct TypeTagData {
     TypeTagData() {}
 
     TypeTagData(QualType Type, bool LayoutCompatible, bool MustBeNull) :
         Type(Type), LayoutCompatible(LayoutCompatible),
         MustBeNull(MustBeNull)
     {}
 
     QualType Type;
 
     /// If true, \c Type should be compared with other expression's types for
     /// layout-compatibility.
     unsigned LayoutCompatible : 1;
     unsigned MustBeNull : 1;
   };
 
   /// A pair of ArgumentKind identifier and magic value.  This uniquely
   /// identifies the magic value.
   typedef std::pair<const IdentifierInfo *, uint64_t> TypeTagMagicValue;
 
 private:
   /// A map from magic value to type information.
   std::unique_ptr<llvm::DenseMap<TypeTagMagicValue, TypeTagData>>
       TypeTagForDatatypeMagicValues;
 
   /// Peform checks on a call of a function with argument_with_type_tag
   /// or pointer_with_type_tag attributes.
   void CheckArgumentWithTypeTag(const ArgumentWithTypeTagAttr *Attr,
                                 const ArrayRef<const Expr *> ExprArgs,
                                 SourceLocation CallSiteLoc);
 
   /// Check if we are taking the address of a packed field
   /// as this may be a problem if the pointer value is dereferenced.
   void CheckAddressOfPackedMember(Expr *rhs);
 
   /// The parser's current scope.
   ///
   /// The parser maintains this state here.
   Scope *CurScope;
 
   mutable IdentifierInfo *Ident_super;
 
   /// Nullability type specifiers.
   IdentifierInfo *Ident__Nonnull = nullptr;
   IdentifierInfo *Ident__Nullable = nullptr;
   IdentifierInfo *Ident__Nullable_result = nullptr;
   IdentifierInfo *Ident__Null_unspecified = nullptr;
 
   IdentifierInfo *Ident_NSError = nullptr;
 
   /// The handler for the FileChanged preprocessor events.
   ///
   /// Used for diagnostics that implement custom semantic analysis for #include
   /// directives, like -Wpragma-pack.
   sema::SemaPPCallbacks *SemaPPCallbackHandler;
 
 protected:
   friend class Parser;
   friend class InitializationSequence;
   friend class ASTReader;
   friend class ASTDeclReader;
   friend class ASTWriter;
 
 public:
   /// Retrieve the keyword associated
   IdentifierInfo *getNullabilityKeyword(NullabilityKind nullability);
 
   /// The struct behind the CFErrorRef pointer.
   RecordDecl *CFError = nullptr;
   bool isCFError(RecordDecl *D);
 
   /// Retrieve the identifier "NSError".
   IdentifierInfo *getNSErrorIdent();
 
   /// Retrieve the parser's current scope.
   ///
   /// This routine must only be used when it is certain that semantic analysis
   /// and the parser are in precisely the same context, which is not the case
   /// when, e.g., we are performing any kind of template instantiation.
   /// Therefore, the only safe places to use this scope are in the parser
   /// itself and in routines directly invoked from the parser and *never* from
   /// template substitution or instantiation.
   Scope *getCurScope() const { return CurScope; }
 
   void incrementMSManglingNumber() const {
     return CurScope->incrementMSManglingNumber();
   }
 
   IdentifierInfo *getSuperIdentifier() const;
 
   ObjCContainerDecl *getObjCDeclContext() const;
 
   DeclContext *getCurLexicalContext() const {
     return OriginalLexicalContext ? OriginalLexicalContext : CurContext;
   }
 
   const DeclContext *getCurObjCLexicalContext() const {
     const DeclContext *DC = getCurLexicalContext();
     // A category implicitly has the attribute of the interface.
     if (const ObjCCategoryDecl *CatD = dyn_cast<ObjCCategoryDecl>(DC))
       DC = CatD->getClassInterface();
     return DC;
   }
 
   /// Determine the number of levels of enclosing template parameters. This is
   /// only usable while parsing. Note that this does not include dependent
   /// contexts in which no template parameters have yet been declared, such as
   /// in a terse function template or generic lambda before the first 'auto' is
   /// encountered.
   unsigned getTemplateDepth(Scope *S) const;
 
   /// To be used for checking whether the arguments being passed to
   /// function exceeds the number of parameters expected for it.
   static bool TooManyArguments(size_t NumParams, size_t NumArgs,
                                bool PartialOverloading = false) {
     // We check whether we're just after a comma in code-completion.
     if (NumArgs > 0 && PartialOverloading)
       return NumArgs + 1 > NumParams; // If so, we view as an extra argument.
     return NumArgs > NumParams;
   }
 
   // Emitting members of dllexported classes is delayed until the class
   // (including field initializers) is fully parsed.
   SmallVector<CXXRecordDecl*, 4> DelayedDllExportClasses;
   SmallVector<CXXMethodDecl*, 4> DelayedDllExportMemberFunctions;
 
 private:
   int ParsingClassDepth = 0;
 
   class SavePendingParsedClassStateRAII {
   public:
     SavePendingParsedClassStateRAII(Sema &S) : S(S) { swapSavedState(); }
 
     ~SavePendingParsedClassStateRAII() {
       assert(S.DelayedOverridingExceptionSpecChecks.empty() &&
              "there shouldn't be any pending delayed exception spec checks");
       assert(S.DelayedEquivalentExceptionSpecChecks.empty() &&
              "there shouldn't be any pending delayed exception spec checks");
       swapSavedState();
     }
 
   private:
     Sema &S;
     decltype(DelayedOverridingExceptionSpecChecks)
         SavedOverridingExceptionSpecChecks;
     decltype(DelayedEquivalentExceptionSpecChecks)
         SavedEquivalentExceptionSpecChecks;
 
     void swapSavedState() {
       SavedOverridingExceptionSpecChecks.swap(
           S.DelayedOverridingExceptionSpecChecks);
       SavedEquivalentExceptionSpecChecks.swap(
           S.DelayedEquivalentExceptionSpecChecks);
     }
   };
 
   /// Helper class that collects misaligned member designations and
   /// their location info for delayed diagnostics.
   struct MisalignedMember {
     Expr *E;
     RecordDecl *RD;
     ValueDecl *MD;
     CharUnits Alignment;
 
     MisalignedMember() : E(), RD(), MD() {}
     MisalignedMember(Expr *E, RecordDecl *RD, ValueDecl *MD,
                      CharUnits Alignment)
         : E(E), RD(RD), MD(MD), Alignment(Alignment) {}
     explicit MisalignedMember(Expr *E)
         : MisalignedMember(E, nullptr, nullptr, CharUnits()) {}
 
     bool operator==(const MisalignedMember &m) { return this->E == m.E; }
   };
   /// Small set of gathered accesses to potentially misaligned members
   /// due to the packed attribute.
   SmallVector<MisalignedMember, 4> MisalignedMembers;
 
   /// Adds an expression to the set of gathered misaligned members.
   void AddPotentialMisalignedMembers(Expr *E, RecordDecl *RD, ValueDecl *MD,
                                      CharUnits Alignment);
 
 public:
   /// Diagnoses the current set of gathered accesses. This typically
   /// happens at full expression level. The set is cleared after emitting the
   /// diagnostics.
   void DiagnoseMisalignedMembers();
 
   /// This function checks if the expression is in the sef of potentially
   /// misaligned members and it is converted to some pointer type T with lower
   /// or equal alignment requirements. If so it removes it. This is used when
   /// we do not want to diagnose such misaligned access (e.g. in conversions to
   /// void*).
   void DiscardMisalignedMemberAddress(const Type *T, Expr *E);
 
   /// This function calls Action when it determines that E designates a
   /// misaligned member due to the packed attribute. This is used to emit
   /// local diagnostics like in reference binding.
   void RefersToMemberWithReducedAlignment(
       Expr *E,
       llvm::function_ref<void(Expr *, RecordDecl *, FieldDecl *, CharUnits)>
           Action);
 
   /// Describes the reason a calling convention specification was ignored, used
   /// for diagnostics.
   enum class CallingConventionIgnoredReason {
     ForThisTarget = 0,
     VariadicFunction,
     ConstructorDestructor,
     BuiltinFunction
   };
   /// Creates a SemaDiagnosticBuilder that emits the diagnostic if the current
   /// context is "used as device code".
   ///
   /// - If CurLexicalContext is a kernel function or it is known that the
   ///   function will be emitted for the device, emits the diagnostics
   ///   immediately.
   /// - If CurLexicalContext is a function and we are compiling
   ///   for the device, but we don't know that this function will be codegen'ed
   ///   for devive yet, creates a diagnostic which is emitted if and when we
   ///   realize that the function will be codegen'ed.
   ///
   /// Example usage:
   ///
   /// Diagnose __float128 type usage only from SYCL device code if the current
   /// target doesn't support it
   /// if (!S.Context.getTargetInfo().hasFloat128Type() &&
   ///     S.getLangOpts().SYCLIsDevice)
   ///   SYCLDiagIfDeviceCode(Loc, diag::err_type_unsupported) << "__float128";
   SemaDiagnosticBuilder SYCLDiagIfDeviceCode(SourceLocation Loc,
                                              unsigned DiagID);
 
   void deepTypeCheckForSYCLDevice(SourceLocation UsedAt,
                                   llvm::DenseSet<QualType> Visited,
                                   ValueDecl *DeclToCheck);
 };
 
 DeductionFailureInfo
 MakeDeductionFailureInfo(ASTContext &Context, Sema::TemplateDeductionResult TDK,
                          sema::TemplateDeductionInfo &Info);
 
 /// Contains a late templated function.
 /// Will be parsed at the end of the translation unit, used by Sema & Parser.
 struct LateParsedTemplate {
   CachedTokens Toks;
   /// The template function declaration to be late parsed.
   Decl *D;
   /// Floating-point options in the point of definition.
   FPOptions FPO;
 };
 
 template <>
 void Sema::PragmaStack<Sema::AlignPackInfo>::Act(SourceLocation PragmaLocation,
                                                  PragmaMsStackAction Action,
                                                  llvm::StringRef StackSlotLabel,
                                                  AlignPackInfo Value);
 
 std::unique_ptr<sema::RISCVIntrinsicManager>
 CreateRISCVIntrinsicManager(Sema &S);
 } // end namespace clang
 
 namespace llvm {
 // Hash a FunctionDeclAndLoc by looking at both its FunctionDecl and its
 // SourceLocation.
 template <> struct DenseMapInfo<clang::Sema::FunctionDeclAndLoc> {
   using FunctionDeclAndLoc = clang::Sema::FunctionDeclAndLoc;
   using FDBaseInfo =
       DenseMapInfo<clang::CanonicalDeclPtr<const clang::FunctionDecl>>;
 
   static FunctionDeclAndLoc getEmptyKey() {
     return {FDBaseInfo::getEmptyKey(), clang::SourceLocation()};
   }
 
   static FunctionDeclAndLoc getTombstoneKey() {
     return {FDBaseInfo::getTombstoneKey(), clang::SourceLocation()};
   }
 
   static unsigned getHashValue(const FunctionDeclAndLoc &FDL) {
     return hash_combine(FDBaseInfo::getHashValue(FDL.FD),
                         FDL.Loc.getHashValue());
   }
 
   static bool isEqual(const FunctionDeclAndLoc &LHS,
                       const FunctionDeclAndLoc &RHS) {
     return LHS.FD == RHS.FD && LHS.Loc == RHS.Loc;
   }
 };
 } // namespace llvm
 
 #endif
diff --git a/contrib/llvm-project/clang/lib/Sema/SemaConcept.cpp b/contrib/llvm-project/clang/lib/Sema/SemaConcept.cpp
index f24b549dd2ef..d1fa8e783122 100755
--- a/contrib/llvm-project/clang/lib/Sema/SemaConcept.cpp
+++ b/contrib/llvm-project/clang/lib/Sema/SemaConcept.cpp
@@ -1,1639 +1,1628 @@
 //===-- SemaConcept.cpp - Semantic Analysis for Constraints and Concepts --===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 //  This file implements semantic analysis for C++ constraints and concepts.
 //
 //===----------------------------------------------------------------------===//
 
 #include "clang/Sema/SemaConcept.h"
 #include "TreeTransform.h"
 #include "clang/AST/ASTLambda.h"
+#include "clang/AST/DeclCXX.h"
 #include "clang/AST/ExprConcepts.h"
 #include "clang/AST/RecursiveASTVisitor.h"
 #include "clang/Basic/OperatorPrecedence.h"
 #include "clang/Sema/EnterExpressionEvaluationContext.h"
 #include "clang/Sema/Initialization.h"
 #include "clang/Sema/Overload.h"
+#include "clang/Sema/ScopeInfo.h"
 #include "clang/Sema/Sema.h"
 #include "clang/Sema/SemaDiagnostic.h"
 #include "clang/Sema/SemaInternal.h"
 #include "clang/Sema/Template.h"
 #include "clang/Sema/TemplateDeduction.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/PointerUnion.h"
 #include "llvm/ADT/StringExtras.h"
 #include <optional>
 
 using namespace clang;
 using namespace sema;
 
 namespace {
 class LogicalBinOp {
   SourceLocation Loc;
   OverloadedOperatorKind Op = OO_None;
   const Expr *LHS = nullptr;
   const Expr *RHS = nullptr;
 
 public:
   LogicalBinOp(const Expr *E) {
     if (auto *BO = dyn_cast<BinaryOperator>(E)) {
       Op = BinaryOperator::getOverloadedOperator(BO->getOpcode());
       LHS = BO->getLHS();
       RHS = BO->getRHS();
       Loc = BO->getExprLoc();
     } else if (auto *OO = dyn_cast<CXXOperatorCallExpr>(E)) {
       // If OO is not || or && it might not have exactly 2 arguments.
       if (OO->getNumArgs() == 2) {
         Op = OO->getOperator();
         LHS = OO->getArg(0);
         RHS = OO->getArg(1);
         Loc = OO->getOperatorLoc();
       }
     }
   }
 
   bool isAnd() const { return Op == OO_AmpAmp; }
   bool isOr() const { return Op == OO_PipePipe; }
   explicit operator bool() const { return isAnd() || isOr(); }
 
   const Expr *getLHS() const { return LHS; }
   const Expr *getRHS() const { return RHS; }
 
   ExprResult recreateBinOp(Sema &SemaRef, ExprResult LHS) const {
     return recreateBinOp(SemaRef, LHS, const_cast<Expr *>(getRHS()));
   }
 
   ExprResult recreateBinOp(Sema &SemaRef, ExprResult LHS,
                            ExprResult RHS) const {
     assert((isAnd() || isOr()) && "Not the right kind of op?");
     assert((!LHS.isInvalid() && !RHS.isInvalid()) && "not good expressions?");
 
     if (!LHS.isUsable() || !RHS.isUsable())
       return ExprEmpty();
 
     // We should just be able to 'normalize' these to the builtin Binary
     // Operator, since that is how they are evaluated in constriant checks.
     return BinaryOperator::Create(SemaRef.Context, LHS.get(), RHS.get(),
                                   BinaryOperator::getOverloadedOpcode(Op),
                                   SemaRef.Context.BoolTy, VK_PRValue,
                                   OK_Ordinary, Loc, FPOptionsOverride{});
   }
 };
 }
 
 bool Sema::CheckConstraintExpression(const Expr *ConstraintExpression,
                                      Token NextToken, bool *PossibleNonPrimary,
                                      bool IsTrailingRequiresClause) {
   // C++2a [temp.constr.atomic]p1
   // ..E shall be a constant expression of type bool.
 
   ConstraintExpression = ConstraintExpression->IgnoreParenImpCasts();
 
   if (LogicalBinOp BO = ConstraintExpression) {
     return CheckConstraintExpression(BO.getLHS(), NextToken,
                                      PossibleNonPrimary) &&
            CheckConstraintExpression(BO.getRHS(), NextToken,
                                      PossibleNonPrimary);
   } else if (auto *C = dyn_cast<ExprWithCleanups>(ConstraintExpression))
     return CheckConstraintExpression(C->getSubExpr(), NextToken,
                                      PossibleNonPrimary);
 
   QualType Type = ConstraintExpression->getType();
 
   auto CheckForNonPrimary = [&] {
     if (!PossibleNonPrimary)
       return;
 
     *PossibleNonPrimary =
         // We have the following case:
         // template<typename> requires func(0) struct S { };
         // The user probably isn't aware of the parentheses required around
         // the function call, and we're only going to parse 'func' as the
         // primary-expression, and complain that it is of non-bool type.
         //
         // However, if we're in a lambda, this might also be:
         // []<typename> requires var () {};
         // Which also looks like a function call due to the lambda parentheses,
         // but unlike the first case, isn't an error, so this check is skipped.
         (NextToken.is(tok::l_paren) &&
          (IsTrailingRequiresClause ||
           (Type->isDependentType() &&
            isa<UnresolvedLookupExpr>(ConstraintExpression) &&
            !dyn_cast_if_present<LambdaScopeInfo>(getCurFunction())) ||
           Type->isFunctionType() ||
           Type->isSpecificBuiltinType(BuiltinType::Overload))) ||
         // We have the following case:
         // template<typename T> requires size_<T> == 0 struct S { };
         // The user probably isn't aware of the parentheses required around
         // the binary operator, and we're only going to parse 'func' as the
         // first operand, and complain that it is of non-bool type.
         getBinOpPrecedence(NextToken.getKind(),
                            /*GreaterThanIsOperator=*/true,
                            getLangOpts().CPlusPlus11) > prec::LogicalAnd;
   };
 
   // An atomic constraint!
   if (ConstraintExpression->isTypeDependent()) {
     CheckForNonPrimary();
     return true;
   }
 
   if (!Context.hasSameUnqualifiedType(Type, Context.BoolTy)) {
     Diag(ConstraintExpression->getExprLoc(),
          diag::err_non_bool_atomic_constraint) << Type
         << ConstraintExpression->getSourceRange();
     CheckForNonPrimary();
     return false;
   }
 
   if (PossibleNonPrimary)
       *PossibleNonPrimary = false;
   return true;
 }
 
 namespace {
 struct SatisfactionStackRAII {
   Sema &SemaRef;
   bool Inserted = false;
   SatisfactionStackRAII(Sema &SemaRef, const NamedDecl *ND,
                         const llvm::FoldingSetNodeID &FSNID)
       : SemaRef(SemaRef) {
       if (ND) {
       SemaRef.PushSatisfactionStackEntry(ND, FSNID);
       Inserted = true;
       }
   }
   ~SatisfactionStackRAII() {
         if (Inserted)
           SemaRef.PopSatisfactionStackEntry();
   }
 };
 } // namespace
 
 template <typename AtomicEvaluator>
 static ExprResult
 calculateConstraintSatisfaction(Sema &S, const Expr *ConstraintExpr,
                                 ConstraintSatisfaction &Satisfaction,
                                 AtomicEvaluator &&Evaluator) {
   ConstraintExpr = ConstraintExpr->IgnoreParenImpCasts();
 
   if (LogicalBinOp BO = ConstraintExpr) {
     ExprResult LHSRes = calculateConstraintSatisfaction(
         S, BO.getLHS(), Satisfaction, Evaluator);
 
     if (LHSRes.isInvalid())
       return ExprError();
 
     bool IsLHSSatisfied = Satisfaction.IsSatisfied;
 
     if (BO.isOr() && IsLHSSatisfied)
       // [temp.constr.op] p3
       //    A disjunction is a constraint taking two operands. To determine if
       //    a disjunction is satisfied, the satisfaction of the first operand
       //    is checked. If that is satisfied, the disjunction is satisfied.
       //    Otherwise, the disjunction is satisfied if and only if the second
       //    operand is satisfied.
       // LHS is instantiated while RHS is not. Skip creating invalid BinaryOp.
       return LHSRes;
 
     if (BO.isAnd() && !IsLHSSatisfied)
       // [temp.constr.op] p2
       //    A conjunction is a constraint taking two operands. To determine if
       //    a conjunction is satisfied, the satisfaction of the first operand
       //    is checked. If that is not satisfied, the conjunction is not
       //    satisfied. Otherwise, the conjunction is satisfied if and only if
       //    the second operand is satisfied.
       // LHS is instantiated while RHS is not. Skip creating invalid BinaryOp.
       return LHSRes;
 
     ExprResult RHSRes = calculateConstraintSatisfaction(
         S, BO.getRHS(), Satisfaction, std::forward<AtomicEvaluator>(Evaluator));
     if (RHSRes.isInvalid())
       return ExprError();
 
     return BO.recreateBinOp(S, LHSRes, RHSRes);
   }
 
   if (auto *C = dyn_cast<ExprWithCleanups>(ConstraintExpr)) {
     // These aren't evaluated, so we don't care about cleanups, so we can just
     // evaluate these as if the cleanups didn't exist.
     return calculateConstraintSatisfaction(
         S, C->getSubExpr(), Satisfaction,
         std::forward<AtomicEvaluator>(Evaluator));
   }
 
   // An atomic constraint expression
   ExprResult SubstitutedAtomicExpr = Evaluator(ConstraintExpr);
 
   if (SubstitutedAtomicExpr.isInvalid())
     return ExprError();
 
   if (!SubstitutedAtomicExpr.isUsable())
     // Evaluator has decided satisfaction without yielding an expression.
     return ExprEmpty();
 
   // We don't have the ability to evaluate this, since it contains a
   // RecoveryExpr, so we want to fail overload resolution.  Otherwise,
   // we'd potentially pick up a different overload, and cause confusing
   // diagnostics. SO, add a failure detail that will cause us to make this
   // overload set not viable.
   if (SubstitutedAtomicExpr.get()->containsErrors()) {
     Satisfaction.IsSatisfied = false;
     Satisfaction.ContainsErrors = true;
 
     PartialDiagnostic Msg = S.PDiag(diag::note_constraint_references_error);
     SmallString<128> DiagString;
     DiagString = ": ";
     Msg.EmitToString(S.getDiagnostics(), DiagString);
     unsigned MessageSize = DiagString.size();
     char *Mem = new (S.Context) char[MessageSize];
     memcpy(Mem, DiagString.c_str(), MessageSize);
     Satisfaction.Details.emplace_back(
         ConstraintExpr,
         new (S.Context) ConstraintSatisfaction::SubstitutionDiagnostic{
             SubstitutedAtomicExpr.get()->getBeginLoc(),
             StringRef(Mem, MessageSize)});
     return SubstitutedAtomicExpr;
   }
 
   EnterExpressionEvaluationContext ConstantEvaluated(
       S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
   SmallVector<PartialDiagnosticAt, 2> EvaluationDiags;
   Expr::EvalResult EvalResult;
   EvalResult.Diag = &EvaluationDiags;
   if (!SubstitutedAtomicExpr.get()->EvaluateAsConstantExpr(EvalResult,
                                                            S.Context) ||
       !EvaluationDiags.empty()) {
     // C++2a [temp.constr.atomic]p1
     //   ...E shall be a constant expression of type bool.
     S.Diag(SubstitutedAtomicExpr.get()->getBeginLoc(),
            diag::err_non_constant_constraint_expression)
         << SubstitutedAtomicExpr.get()->getSourceRange();
     for (const PartialDiagnosticAt &PDiag : EvaluationDiags)
       S.Diag(PDiag.first, PDiag.second);
     return ExprError();
   }
 
   assert(EvalResult.Val.isInt() &&
          "evaluating bool expression didn't produce int");
   Satisfaction.IsSatisfied = EvalResult.Val.getInt().getBoolValue();
   if (!Satisfaction.IsSatisfied)
     Satisfaction.Details.emplace_back(ConstraintExpr,
                                       SubstitutedAtomicExpr.get());
 
   return SubstitutedAtomicExpr;
 }
 
 static bool
 DiagRecursiveConstraintEval(Sema &S, llvm::FoldingSetNodeID &ID,
                             const NamedDecl *Templ, const Expr *E,
                             const MultiLevelTemplateArgumentList &MLTAL) {
   E->Profile(ID, S.Context, /*Canonical=*/true);
   for (const auto &List : MLTAL)
     for (const auto &TemplateArg : List.Args)
       TemplateArg.Profile(ID, S.Context);
 
   // Note that we have to do this with our own collection, because there are
   // times where a constraint-expression check can cause us to need to evaluate
   // other constriants that are unrelated, such as when evaluating a recovery
   // expression, or when trying to determine the constexpr-ness of special
   // members. Otherwise we could just use the
   // Sema::InstantiatingTemplate::isAlreadyBeingInstantiated function.
   if (S.SatisfactionStackContains(Templ, ID)) {
     S.Diag(E->getExprLoc(), diag::err_constraint_depends_on_self)
         << const_cast<Expr *>(E) << E->getSourceRange();
     return true;
   }
 
   return false;
 }
 
 static ExprResult calculateConstraintSatisfaction(
     Sema &S, const NamedDecl *Template, SourceLocation TemplateNameLoc,
     const MultiLevelTemplateArgumentList &MLTAL, const Expr *ConstraintExpr,
     ConstraintSatisfaction &Satisfaction) {
   return calculateConstraintSatisfaction(
       S, ConstraintExpr, Satisfaction, [&](const Expr *AtomicExpr) {
         EnterExpressionEvaluationContext ConstantEvaluated(
             S, Sema::ExpressionEvaluationContext::ConstantEvaluated,
             Sema::ReuseLambdaContextDecl);
 
         // Atomic constraint - substitute arguments and check satisfaction.
         ExprResult SubstitutedExpression;
         {
           TemplateDeductionInfo Info(TemplateNameLoc);
           Sema::InstantiatingTemplate Inst(S, AtomicExpr->getBeginLoc(),
               Sema::InstantiatingTemplate::ConstraintSubstitution{},
               const_cast<NamedDecl *>(Template), Info,
               AtomicExpr->getSourceRange());
           if (Inst.isInvalid())
             return ExprError();
 
           llvm::FoldingSetNodeID ID;
           if (Template &&
               DiagRecursiveConstraintEval(S, ID, Template, AtomicExpr, MLTAL)) {
             Satisfaction.IsSatisfied = false;
             Satisfaction.ContainsErrors = true;
             return ExprEmpty();
           }
 
           SatisfactionStackRAII StackRAII(S, Template, ID);
 
           // We do not want error diagnostics escaping here.
           Sema::SFINAETrap Trap(S);
           SubstitutedExpression =
               S.SubstConstraintExpr(const_cast<Expr *>(AtomicExpr), MLTAL);
 
           if (SubstitutedExpression.isInvalid() || Trap.hasErrorOccurred()) {
             // C++2a [temp.constr.atomic]p1
             //   ...If substitution results in an invalid type or expression, the
             //   constraint is not satisfied.
             if (!Trap.hasErrorOccurred())
               // A non-SFINAE error has occurred as a result of this
               // substitution.
               return ExprError();
 
             PartialDiagnosticAt SubstDiag{SourceLocation(),
                                           PartialDiagnostic::NullDiagnostic()};
             Info.takeSFINAEDiagnostic(SubstDiag);
             // FIXME: Concepts: This is an unfortunate consequence of there
             //  being no serialization code for PartialDiagnostics and the fact
             //  that serializing them would likely take a lot more storage than
             //  just storing them as strings. We would still like, in the
             //  future, to serialize the proper PartialDiagnostic as serializing
             //  it as a string defeats the purpose of the diagnostic mechanism.
             SmallString<128> DiagString;
             DiagString = ": ";
             SubstDiag.second.EmitToString(S.getDiagnostics(), DiagString);
             unsigned MessageSize = DiagString.size();
             char *Mem = new (S.Context) char[MessageSize];
             memcpy(Mem, DiagString.c_str(), MessageSize);
             Satisfaction.Details.emplace_back(
                 AtomicExpr,
                 new (S.Context) ConstraintSatisfaction::SubstitutionDiagnostic{
                         SubstDiag.first, StringRef(Mem, MessageSize)});
             Satisfaction.IsSatisfied = false;
             return ExprEmpty();
           }
         }
 
         if (!S.CheckConstraintExpression(SubstitutedExpression.get()))
           return ExprError();
 
         // [temp.constr.atomic]p3: To determine if an atomic constraint is
         // satisfied, the parameter mapping and template arguments are first
         // substituted into its expression.  If substitution results in an
         // invalid type or expression, the constraint is not satisfied.
         // Otherwise, the lvalue-to-rvalue conversion is performed if necessary,
         // and E shall be a constant expression of type bool.
         //
         // Perform the L to R Value conversion if necessary. We do so for all
         // non-PRValue categories, else we fail to extend the lifetime of
         // temporaries, and that fails the constant expression check.
         if (!SubstitutedExpression.get()->isPRValue())
           SubstitutedExpression = ImplicitCastExpr::Create(
               S.Context, SubstitutedExpression.get()->getType(),
               CK_LValueToRValue, SubstitutedExpression.get(),
               /*BasePath=*/nullptr, VK_PRValue, FPOptionsOverride());
 
         return SubstitutedExpression;
       });
 }
 
 static bool CheckConstraintSatisfaction(
     Sema &S, const NamedDecl *Template, ArrayRef<const Expr *> ConstraintExprs,
     llvm::SmallVectorImpl<Expr *> &Converted,
     const MultiLevelTemplateArgumentList &TemplateArgsLists,
     SourceRange TemplateIDRange, ConstraintSatisfaction &Satisfaction) {
   if (ConstraintExprs.empty()) {
     Satisfaction.IsSatisfied = true;
     return false;
   }
 
   if (TemplateArgsLists.isAnyArgInstantiationDependent()) {
     // No need to check satisfaction for dependent constraint expressions.
     Satisfaction.IsSatisfied = true;
     return false;
   }
 
   ArrayRef<TemplateArgument> TemplateArgs =
       TemplateArgsLists.getNumSubstitutedLevels() > 0
           ? TemplateArgsLists.getOutermost()
           : ArrayRef<TemplateArgument> {};
   Sema::InstantiatingTemplate Inst(S, TemplateIDRange.getBegin(),
       Sema::InstantiatingTemplate::ConstraintsCheck{},
       const_cast<NamedDecl *>(Template), TemplateArgs, TemplateIDRange);
   if (Inst.isInvalid())
     return true;
 
   for (const Expr *ConstraintExpr : ConstraintExprs) {
     ExprResult Res = calculateConstraintSatisfaction(
         S, Template, TemplateIDRange.getBegin(), TemplateArgsLists,
         ConstraintExpr, Satisfaction);
     if (Res.isInvalid())
       return true;
 
     Converted.push_back(Res.get());
     if (!Satisfaction.IsSatisfied) {
       // Backfill the 'converted' list with nulls so we can keep the Converted
       // and unconverted lists in sync.
       Converted.append(ConstraintExprs.size() - Converted.size(), nullptr);
       // [temp.constr.op] p2
       // [...] To determine if a conjunction is satisfied, the satisfaction
       // of the first operand is checked. If that is not satisfied, the
       // conjunction is not satisfied. [...]
       return false;
     }
   }
   return false;
 }
 
 bool Sema::CheckConstraintSatisfaction(
     const NamedDecl *Template, ArrayRef<const Expr *> ConstraintExprs,
     llvm::SmallVectorImpl<Expr *> &ConvertedConstraints,
     const MultiLevelTemplateArgumentList &TemplateArgsLists,
     SourceRange TemplateIDRange, ConstraintSatisfaction &OutSatisfaction) {
   if (ConstraintExprs.empty()) {
     OutSatisfaction.IsSatisfied = true;
     return false;
   }
   if (!Template) {
     return ::CheckConstraintSatisfaction(
         *this, nullptr, ConstraintExprs, ConvertedConstraints,
         TemplateArgsLists, TemplateIDRange, OutSatisfaction);
   }
 
   // A list of the template argument list flattened in a predictible manner for
   // the purposes of caching. The ConstraintSatisfaction type is in AST so it
   // has no access to the MultiLevelTemplateArgumentList, so this has to happen
   // here.
   llvm::SmallVector<TemplateArgument, 4> FlattenedArgs;
   for (auto List : TemplateArgsLists)
     FlattenedArgs.insert(FlattenedArgs.end(), List.Args.begin(),
                          List.Args.end());
 
   llvm::FoldingSetNodeID ID;
   ConstraintSatisfaction::Profile(ID, Context, Template, FlattenedArgs);
   void *InsertPos;
   if (auto *Cached = SatisfactionCache.FindNodeOrInsertPos(ID, InsertPos)) {
     OutSatisfaction = *Cached;
     return false;
   }
 
   auto Satisfaction =
       std::make_unique<ConstraintSatisfaction>(Template, FlattenedArgs);
   if (::CheckConstraintSatisfaction(*this, Template, ConstraintExprs,
                                     ConvertedConstraints, TemplateArgsLists,
                                     TemplateIDRange, *Satisfaction)) {
     OutSatisfaction = *Satisfaction;
     return true;
   }
 
   if (auto *Cached = SatisfactionCache.FindNodeOrInsertPos(ID, InsertPos)) {
     // The evaluation of this constraint resulted in us trying to re-evaluate it
     // recursively. This isn't really possible, except we try to form a
     // RecoveryExpr as a part of the evaluation.  If this is the case, just
     // return the 'cached' version (which will have the same result), and save
     // ourselves the extra-insert. If it ever becomes possible to legitimately
     // recursively check a constraint, we should skip checking the 'inner' one
     // above, and replace the cached version with this one, as it would be more
     // specific.
     OutSatisfaction = *Cached;
     return false;
   }
 
   // Else we can simply add this satisfaction to the list.
   OutSatisfaction = *Satisfaction;
   // We cannot use InsertPos here because CheckConstraintSatisfaction might have
   // invalidated it.
   // Note that entries of SatisfactionCache are deleted in Sema's destructor.
   SatisfactionCache.InsertNode(Satisfaction.release());
   return false;
 }
 
 bool Sema::CheckConstraintSatisfaction(const Expr *ConstraintExpr,
                                        ConstraintSatisfaction &Satisfaction) {
   return calculateConstraintSatisfaction(
              *this, ConstraintExpr, Satisfaction,
              [this](const Expr *AtomicExpr) -> ExprResult {
                // We only do this to immitate lvalue-to-rvalue conversion.
                return PerformContextuallyConvertToBool(
                    const_cast<Expr *>(AtomicExpr));
              })
       .isInvalid();
 }
 
 bool Sema::addInstantiatedCapturesToScope(
     FunctionDecl *Function, const FunctionDecl *PatternDecl,
     LocalInstantiationScope &Scope,
     const MultiLevelTemplateArgumentList &TemplateArgs) {
   const auto *LambdaClass = cast<CXXMethodDecl>(Function)->getParent();
   const auto *LambdaPattern = cast<CXXMethodDecl>(PatternDecl)->getParent();
 
   unsigned Instantiated = 0;
 
   auto AddSingleCapture = [&](const ValueDecl *CapturedPattern,
                               unsigned Index) {
     ValueDecl *CapturedVar = LambdaClass->getCapture(Index)->getCapturedVar();
-    if (cast<CXXMethodDecl>(Function)->isConst()) {
-      QualType T = CapturedVar->getType();
-      T.addConst();
-      CapturedVar->setType(T);
-    }
     if (CapturedVar->isInitCapture())
       Scope.InstantiatedLocal(CapturedPattern, CapturedVar);
   };
 
   for (const LambdaCapture &CapturePattern : LambdaPattern->captures()) {
     if (!CapturePattern.capturesVariable()) {
       Instantiated++;
       continue;
     }
     const ValueDecl *CapturedPattern = CapturePattern.getCapturedVar();
     if (!CapturedPattern->isParameterPack()) {
       AddSingleCapture(CapturedPattern, Instantiated++);
     } else {
       Scope.MakeInstantiatedLocalArgPack(CapturedPattern);
       std::optional<unsigned> NumArgumentsInExpansion =
           getNumArgumentsInExpansion(CapturedPattern->getType(), TemplateArgs);
       if (!NumArgumentsInExpansion)
         continue;
       for (unsigned Arg = 0; Arg < *NumArgumentsInExpansion; ++Arg)
         AddSingleCapture(CapturedPattern, Instantiated++);
     }
   }
   return false;
 }
 
 bool Sema::SetupConstraintScope(
     FunctionDecl *FD, std::optional<ArrayRef<TemplateArgument>> TemplateArgs,
     MultiLevelTemplateArgumentList MLTAL, LocalInstantiationScope &Scope) {
   if (FD->isTemplateInstantiation() && FD->getPrimaryTemplate()) {
     FunctionTemplateDecl *PrimaryTemplate = FD->getPrimaryTemplate();
     InstantiatingTemplate Inst(
         *this, FD->getPointOfInstantiation(),
         Sema::InstantiatingTemplate::ConstraintsCheck{}, PrimaryTemplate,
         TemplateArgs ? *TemplateArgs : ArrayRef<TemplateArgument>{},
         SourceRange());
     if (Inst.isInvalid())
       return true;
 
     // addInstantiatedParametersToScope creates a map of 'uninstantiated' to
     // 'instantiated' parameters and adds it to the context. For the case where
     // this function is a template being instantiated NOW, we also need to add
     // the list of current template arguments to the list so that they also can
     // be picked out of the map.
     if (auto *SpecArgs = FD->getTemplateSpecializationArgs()) {
       MultiLevelTemplateArgumentList JustTemplArgs(FD, SpecArgs->asArray(),
                                                    /*Final=*/false);
       if (addInstantiatedParametersToScope(
               FD, PrimaryTemplate->getTemplatedDecl(), Scope, JustTemplArgs))
         return true;
     }
 
     // If this is a member function, make sure we get the parameters that
     // reference the original primary template.
     if (const auto *FromMemTempl =
             PrimaryTemplate->getInstantiatedFromMemberTemplate()) {
       if (addInstantiatedParametersToScope(FD, FromMemTempl->getTemplatedDecl(),
                                            Scope, MLTAL))
         return true;
-      // Make sure the captures are also added to the instantiation scope.
-      if (isLambdaCallOperator(FD) &&
-          addInstantiatedCapturesToScope(FD, FromMemTempl->getTemplatedDecl(),
-                                         Scope, MLTAL))
-        return true;
     }
 
     return false;
   }
 
   if (FD->getTemplatedKind() == FunctionDecl::TK_MemberSpecialization ||
       FD->getTemplatedKind() == FunctionDecl::TK_DependentNonTemplate) {
     FunctionDecl *InstantiatedFrom =
         FD->getTemplatedKind() == FunctionDecl::TK_MemberSpecialization
             ? FD->getInstantiatedFromMemberFunction()
             : FD->getInstantiatedFromDecl();
 
     InstantiatingTemplate Inst(
         *this, FD->getPointOfInstantiation(),
         Sema::InstantiatingTemplate::ConstraintsCheck{}, InstantiatedFrom,
         TemplateArgs ? *TemplateArgs : ArrayRef<TemplateArgument>{},
         SourceRange());
     if (Inst.isInvalid())
       return true;
 
     // Case where this was not a template, but instantiated as a
     // child-function.
     if (addInstantiatedParametersToScope(FD, InstantiatedFrom, Scope, MLTAL))
       return true;
-
-    // Make sure the captures are also added to the instantiation scope.
-    if (isLambdaCallOperator(FD) &&
-        addInstantiatedCapturesToScope(FD, InstantiatedFrom, Scope, MLTAL))
-      return true;
   }
 
   return false;
 }
 
 // This function collects all of the template arguments for the purposes of
 // constraint-instantiation and checking.
 std::optional<MultiLevelTemplateArgumentList>
 Sema::SetupConstraintCheckingTemplateArgumentsAndScope(
     FunctionDecl *FD, std::optional<ArrayRef<TemplateArgument>> TemplateArgs,
     LocalInstantiationScope &Scope) {
   MultiLevelTemplateArgumentList MLTAL;
 
   // Collect the list of template arguments relative to the 'primary' template.
   // We need the entire list, since the constraint is completely uninstantiated
   // at this point.
   MLTAL =
       getTemplateInstantiationArgs(FD, /*Final=*/false, /*Innermost=*/nullptr,
                                    /*RelativeToPrimary=*/true,
                                    /*Pattern=*/nullptr,
                                    /*ForConstraintInstantiation=*/true);
   if (SetupConstraintScope(FD, TemplateArgs, MLTAL, Scope))
     return std::nullopt;
 
   return MLTAL;
 }
 
 bool Sema::CheckFunctionConstraints(const FunctionDecl *FD,
                                     ConstraintSatisfaction &Satisfaction,
                                     SourceLocation UsageLoc,
                                     bool ForOverloadResolution) {
   // Don't check constraints if the function is dependent. Also don't check if
   // this is a function template specialization, as the call to
   // CheckinstantiatedFunctionTemplateConstraints after this will check it
   // better.
   if (FD->isDependentContext() ||
       FD->getTemplatedKind() ==
           FunctionDecl::TK_FunctionTemplateSpecialization) {
     Satisfaction.IsSatisfied = true;
     return false;
   }
 
   // A lambda conversion operator has the same constraints as the call operator
   // and constraints checking relies on whether we are in a lambda call operator
   // (and may refer to its parameters), so check the call operator instead.
   if (const auto *MD = dyn_cast<CXXConversionDecl>(FD);
       MD && isLambdaConversionOperator(const_cast<CXXConversionDecl *>(MD)))
     return CheckFunctionConstraints(MD->getParent()->getLambdaCallOperator(),
                                     Satisfaction, UsageLoc,
                                     ForOverloadResolution);
 
   DeclContext *CtxToSave = const_cast<FunctionDecl *>(FD);
 
   while (isLambdaCallOperator(CtxToSave) || FD->isTransparentContext()) {
     if (isLambdaCallOperator(CtxToSave))
       CtxToSave = CtxToSave->getParent()->getParent();
     else
       CtxToSave = CtxToSave->getNonTransparentContext();
   }
 
   ContextRAII SavedContext{*this, CtxToSave};
   LocalInstantiationScope Scope(*this, !ForOverloadResolution ||
                                            isLambdaCallOperator(FD));
   std::optional<MultiLevelTemplateArgumentList> MLTAL =
       SetupConstraintCheckingTemplateArgumentsAndScope(
           const_cast<FunctionDecl *>(FD), {}, Scope);
 
   if (!MLTAL)
     return true;
 
   Qualifiers ThisQuals;
   CXXRecordDecl *Record = nullptr;
   if (auto *Method = dyn_cast<CXXMethodDecl>(FD)) {
     ThisQuals = Method->getMethodQualifiers();
     Record = const_cast<CXXRecordDecl *>(Method->getParent());
   }
   CXXThisScopeRAII ThisScope(*this, Record, ThisQuals, Record != nullptr);
+
+  LambdaScopeForCallOperatorInstantiationRAII LambdaScope(
+      *this, const_cast<FunctionDecl *>(FD), *MLTAL, Scope);
+
   return CheckConstraintSatisfaction(
       FD, {FD->getTrailingRequiresClause()}, *MLTAL,
       SourceRange(UsageLoc.isValid() ? UsageLoc : FD->getLocation()),
       Satisfaction);
 }
 
 
 // Figure out the to-translation-unit depth for this function declaration for
 // the purpose of seeing if they differ by constraints. This isn't the same as
 // getTemplateDepth, because it includes already instantiated parents.
 static unsigned
 CalculateTemplateDepthForConstraints(Sema &S, const NamedDecl *ND,
                                      bool SkipForSpecialization = false) {
   MultiLevelTemplateArgumentList MLTAL = S.getTemplateInstantiationArgs(
       ND, /*Final=*/false, /*Innermost=*/nullptr, /*RelativeToPrimary=*/true,
       /*Pattern=*/nullptr,
       /*ForConstraintInstantiation=*/true, SkipForSpecialization);
   return MLTAL.getNumLevels();
 }
 
 namespace {
   class AdjustConstraintDepth : public TreeTransform<AdjustConstraintDepth> {
   unsigned TemplateDepth = 0;
   public:
   using inherited = TreeTransform<AdjustConstraintDepth>;
   AdjustConstraintDepth(Sema &SemaRef, unsigned TemplateDepth)
       : inherited(SemaRef), TemplateDepth(TemplateDepth) {}
 
   using inherited::TransformTemplateTypeParmType;
   QualType TransformTemplateTypeParmType(TypeLocBuilder &TLB,
                                          TemplateTypeParmTypeLoc TL, bool) {
     const TemplateTypeParmType *T = TL.getTypePtr();
 
     TemplateTypeParmDecl *NewTTPDecl = nullptr;
     if (TemplateTypeParmDecl *OldTTPDecl = T->getDecl())
       NewTTPDecl = cast_or_null<TemplateTypeParmDecl>(
           TransformDecl(TL.getNameLoc(), OldTTPDecl));
 
     QualType Result = getSema().Context.getTemplateTypeParmType(
         T->getDepth() + TemplateDepth, T->getIndex(), T->isParameterPack(),
         NewTTPDecl);
     TemplateTypeParmTypeLoc NewTL = TLB.push<TemplateTypeParmTypeLoc>(Result);
     NewTL.setNameLoc(TL.getNameLoc());
     return Result;
   }
   };
 } // namespace
 
 static const Expr *SubstituteConstraintExpression(Sema &S, const NamedDecl *ND,
                                                   const Expr *ConstrExpr) {
   MultiLevelTemplateArgumentList MLTAL = S.getTemplateInstantiationArgs(
       ND, /*Final=*/false, /*Innermost=*/nullptr,
       /*RelativeToPrimary=*/true,
       /*Pattern=*/nullptr, /*ForConstraintInstantiation=*/true,
       /*SkipForSpecialization*/ false);
   if (MLTAL.getNumSubstitutedLevels() == 0)
     return ConstrExpr;
 
   Sema::SFINAETrap SFINAE(S, /*AccessCheckingSFINAE=*/false);
 
   Sema::InstantiatingTemplate Inst(
       S, ND->getLocation(),
       Sema::InstantiatingTemplate::ConstraintNormalization{},
       const_cast<NamedDecl *>(ND), SourceRange{});
 
   if (Inst.isInvalid())
     return nullptr;
 
   std::optional<Sema::CXXThisScopeRAII> ThisScope;
   if (auto *RD = dyn_cast<CXXRecordDecl>(ND->getDeclContext()))
     ThisScope.emplace(S, const_cast<CXXRecordDecl *>(RD), Qualifiers());
   ExprResult SubstConstr =
       S.SubstConstraintExpr(const_cast<clang::Expr *>(ConstrExpr), MLTAL);
   if (SFINAE.hasErrorOccurred() || !SubstConstr.isUsable())
     return nullptr;
   return SubstConstr.get();
 }
 
 bool Sema::AreConstraintExpressionsEqual(const NamedDecl *Old,
                                          const Expr *OldConstr,
                                          const NamedDecl *New,
                                          const Expr *NewConstr) {
   if (OldConstr == NewConstr)
     return true;
   // C++ [temp.constr.decl]p4
   if (Old && New && Old != New &&
       Old->getLexicalDeclContext() != New->getLexicalDeclContext()) {
     if (const Expr *SubstConstr =
             SubstituteConstraintExpression(*this, Old, OldConstr))
       OldConstr = SubstConstr;
     else
       return false;
     if (const Expr *SubstConstr =
             SubstituteConstraintExpression(*this, New, NewConstr))
       NewConstr = SubstConstr;
     else
       return false;
   }
 
   llvm::FoldingSetNodeID ID1, ID2;
   OldConstr->Profile(ID1, Context, /*Canonical=*/true);
   NewConstr->Profile(ID2, Context, /*Canonical=*/true);
   return ID1 == ID2;
 }
 
 bool Sema::FriendConstraintsDependOnEnclosingTemplate(const FunctionDecl *FD) {
   assert(FD->getFriendObjectKind() && "Must be a friend!");
 
   // The logic for non-templates is handled in ASTContext::isSameEntity, so we
   // don't have to bother checking 'DependsOnEnclosingTemplate' for a
   // non-function-template.
   assert(FD->getDescribedFunctionTemplate() &&
          "Non-function templates don't need to be checked");
 
   SmallVector<const Expr *, 3> ACs;
   FD->getDescribedFunctionTemplate()->getAssociatedConstraints(ACs);
 
   unsigned OldTemplateDepth = CalculateTemplateDepthForConstraints(*this, FD);
   for (const Expr *Constraint : ACs)
     if (ConstraintExpressionDependsOnEnclosingTemplate(FD, OldTemplateDepth,
                                                        Constraint))
       return true;
 
   return false;
 }
 
 bool Sema::EnsureTemplateArgumentListConstraints(
     TemplateDecl *TD, const MultiLevelTemplateArgumentList &TemplateArgsLists,
     SourceRange TemplateIDRange) {
   ConstraintSatisfaction Satisfaction;
   llvm::SmallVector<const Expr *, 3> AssociatedConstraints;
   TD->getAssociatedConstraints(AssociatedConstraints);
   if (CheckConstraintSatisfaction(TD, AssociatedConstraints, TemplateArgsLists,
                                   TemplateIDRange, Satisfaction))
     return true;
 
   if (!Satisfaction.IsSatisfied) {
     SmallString<128> TemplateArgString;
     TemplateArgString = " ";
     TemplateArgString += getTemplateArgumentBindingsText(
         TD->getTemplateParameters(), TemplateArgsLists.getInnermost().data(),
         TemplateArgsLists.getInnermost().size());
 
     Diag(TemplateIDRange.getBegin(),
          diag::err_template_arg_list_constraints_not_satisfied)
         << (int)getTemplateNameKindForDiagnostics(TemplateName(TD)) << TD
         << TemplateArgString << TemplateIDRange;
     DiagnoseUnsatisfiedConstraint(Satisfaction);
     return true;
   }
   return false;
 }
 
 bool Sema::CheckInstantiatedFunctionTemplateConstraints(
     SourceLocation PointOfInstantiation, FunctionDecl *Decl,
     ArrayRef<TemplateArgument> TemplateArgs,
     ConstraintSatisfaction &Satisfaction) {
   // In most cases we're not going to have constraints, so check for that first.
   FunctionTemplateDecl *Template = Decl->getPrimaryTemplate();
   // Note - code synthesis context for the constraints check is created
   // inside CheckConstraintsSatisfaction.
   SmallVector<const Expr *, 3> TemplateAC;
   Template->getAssociatedConstraints(TemplateAC);
   if (TemplateAC.empty()) {
     Satisfaction.IsSatisfied = true;
     return false;
   }
 
   // Enter the scope of this instantiation. We don't use
   // PushDeclContext because we don't have a scope.
   Sema::ContextRAII savedContext(*this, Decl);
   LocalInstantiationScope Scope(*this);
 
   std::optional<MultiLevelTemplateArgumentList> MLTAL =
       SetupConstraintCheckingTemplateArgumentsAndScope(Decl, TemplateArgs,
                                                        Scope);
 
   if (!MLTAL)
     return true;
 
   Qualifiers ThisQuals;
   CXXRecordDecl *Record = nullptr;
   if (auto *Method = dyn_cast<CXXMethodDecl>(Decl)) {
     ThisQuals = Method->getMethodQualifiers();
     Record = Method->getParent();
   }
+
   CXXThisScopeRAII ThisScope(*this, Record, ThisQuals, Record != nullptr);
-  FunctionScopeRAII FuncScope(*this);
-  if (isLambdaCallOperator(Decl))
-    PushLambdaScope();
-  else
-    FuncScope.disable();
+  LambdaScopeForCallOperatorInstantiationRAII LambdaScope(
+      *this, const_cast<FunctionDecl *>(Decl), *MLTAL, Scope);
 
   llvm::SmallVector<Expr *, 1> Converted;
   return CheckConstraintSatisfaction(Template, TemplateAC, Converted, *MLTAL,
                                      PointOfInstantiation, Satisfaction);
 }
 
 static void diagnoseUnsatisfiedRequirement(Sema &S,
                                            concepts::ExprRequirement *Req,
                                            bool First) {
   assert(!Req->isSatisfied()
          && "Diagnose() can only be used on an unsatisfied requirement");
   switch (Req->getSatisfactionStatus()) {
     case concepts::ExprRequirement::SS_Dependent:
       llvm_unreachable("Diagnosing a dependent requirement");
       break;
     case concepts::ExprRequirement::SS_ExprSubstitutionFailure: {
       auto *SubstDiag = Req->getExprSubstitutionDiagnostic();
       if (!SubstDiag->DiagMessage.empty())
         S.Diag(SubstDiag->DiagLoc,
                diag::note_expr_requirement_expr_substitution_error)
                << (int)First << SubstDiag->SubstitutedEntity
                << SubstDiag->DiagMessage;
       else
         S.Diag(SubstDiag->DiagLoc,
                diag::note_expr_requirement_expr_unknown_substitution_error)
             << (int)First << SubstDiag->SubstitutedEntity;
       break;
     }
     case concepts::ExprRequirement::SS_NoexceptNotMet:
       S.Diag(Req->getNoexceptLoc(),
              diag::note_expr_requirement_noexcept_not_met)
           << (int)First << Req->getExpr();
       break;
     case concepts::ExprRequirement::SS_TypeRequirementSubstitutionFailure: {
       auto *SubstDiag =
           Req->getReturnTypeRequirement().getSubstitutionDiagnostic();
       if (!SubstDiag->DiagMessage.empty())
         S.Diag(SubstDiag->DiagLoc,
                diag::note_expr_requirement_type_requirement_substitution_error)
             << (int)First << SubstDiag->SubstitutedEntity
             << SubstDiag->DiagMessage;
       else
         S.Diag(SubstDiag->DiagLoc,
                diag::note_expr_requirement_type_requirement_unknown_substitution_error)
             << (int)First << SubstDiag->SubstitutedEntity;
       break;
     }
     case concepts::ExprRequirement::SS_ConstraintsNotSatisfied: {
       ConceptSpecializationExpr *ConstraintExpr =
           Req->getReturnTypeRequirementSubstitutedConstraintExpr();
       if (ConstraintExpr->getTemplateArgsAsWritten()->NumTemplateArgs == 1) {
         // A simple case - expr type is the type being constrained and the concept
         // was not provided arguments.
         Expr *e = Req->getExpr();
         S.Diag(e->getBeginLoc(),
                diag::note_expr_requirement_constraints_not_satisfied_simple)
             << (int)First << S.Context.getReferenceQualifiedType(e)
             << ConstraintExpr->getNamedConcept();
       } else {
         S.Diag(ConstraintExpr->getBeginLoc(),
                diag::note_expr_requirement_constraints_not_satisfied)
             << (int)First << ConstraintExpr;
       }
       S.DiagnoseUnsatisfiedConstraint(ConstraintExpr->getSatisfaction());
       break;
     }
     case concepts::ExprRequirement::SS_Satisfied:
       llvm_unreachable("We checked this above");
   }
 }
 
 static void diagnoseUnsatisfiedRequirement(Sema &S,
                                            concepts::TypeRequirement *Req,
                                            bool First) {
   assert(!Req->isSatisfied()
          && "Diagnose() can only be used on an unsatisfied requirement");
   switch (Req->getSatisfactionStatus()) {
   case concepts::TypeRequirement::SS_Dependent:
     llvm_unreachable("Diagnosing a dependent requirement");
     return;
   case concepts::TypeRequirement::SS_SubstitutionFailure: {
     auto *SubstDiag = Req->getSubstitutionDiagnostic();
     if (!SubstDiag->DiagMessage.empty())
       S.Diag(SubstDiag->DiagLoc,
              diag::note_type_requirement_substitution_error) << (int)First
           << SubstDiag->SubstitutedEntity << SubstDiag->DiagMessage;
     else
       S.Diag(SubstDiag->DiagLoc,
              diag::note_type_requirement_unknown_substitution_error)
           << (int)First << SubstDiag->SubstitutedEntity;
     return;
   }
   default:
     llvm_unreachable("Unknown satisfaction status");
     return;
   }
 }
 static void diagnoseWellFormedUnsatisfiedConstraintExpr(Sema &S,
                                                         Expr *SubstExpr,
                                                         bool First = true);
 
 static void diagnoseUnsatisfiedRequirement(Sema &S,
                                            concepts::NestedRequirement *Req,
                                            bool First) {
   using SubstitutionDiagnostic = std::pair<SourceLocation, StringRef>;
   for (auto &Pair : Req->getConstraintSatisfaction()) {
     if (auto *SubstDiag = Pair.second.dyn_cast<SubstitutionDiagnostic *>())
       S.Diag(SubstDiag->first, diag::note_nested_requirement_substitution_error)
           << (int)First << Req->getInvalidConstraintEntity() << SubstDiag->second;
     else
       diagnoseWellFormedUnsatisfiedConstraintExpr(
           S, Pair.second.dyn_cast<Expr *>(), First);
     First = false;
   }
 }
 
 static void diagnoseWellFormedUnsatisfiedConstraintExpr(Sema &S,
                                                         Expr *SubstExpr,
                                                         bool First) {
   SubstExpr = SubstExpr->IgnoreParenImpCasts();
   if (BinaryOperator *BO = dyn_cast<BinaryOperator>(SubstExpr)) {
     switch (BO->getOpcode()) {
     // These two cases will in practice only be reached when using fold
     // expressions with || and &&, since otherwise the || and && will have been
     // broken down into atomic constraints during satisfaction checking.
     case BO_LOr:
       // Or evaluated to false - meaning both RHS and LHS evaluated to false.
       diagnoseWellFormedUnsatisfiedConstraintExpr(S, BO->getLHS(), First);
       diagnoseWellFormedUnsatisfiedConstraintExpr(S, BO->getRHS(),
                                                   /*First=*/false);
       return;
     case BO_LAnd: {
       bool LHSSatisfied =
           BO->getLHS()->EvaluateKnownConstInt(S.Context).getBoolValue();
       if (LHSSatisfied) {
         // LHS is true, so RHS must be false.
         diagnoseWellFormedUnsatisfiedConstraintExpr(S, BO->getRHS(), First);
         return;
       }
       // LHS is false
       diagnoseWellFormedUnsatisfiedConstraintExpr(S, BO->getLHS(), First);
 
       // RHS might also be false
       bool RHSSatisfied =
           BO->getRHS()->EvaluateKnownConstInt(S.Context).getBoolValue();
       if (!RHSSatisfied)
         diagnoseWellFormedUnsatisfiedConstraintExpr(S, BO->getRHS(),
                                                     /*First=*/false);
       return;
     }
     case BO_GE:
     case BO_LE:
     case BO_GT:
     case BO_LT:
     case BO_EQ:
     case BO_NE:
       if (BO->getLHS()->getType()->isIntegerType() &&
           BO->getRHS()->getType()->isIntegerType()) {
         Expr::EvalResult SimplifiedLHS;
         Expr::EvalResult SimplifiedRHS;
         BO->getLHS()->EvaluateAsInt(SimplifiedLHS, S.Context,
                                     Expr::SE_NoSideEffects,
                                     /*InConstantContext=*/true);
         BO->getRHS()->EvaluateAsInt(SimplifiedRHS, S.Context,
                                     Expr::SE_NoSideEffects,
                                     /*InConstantContext=*/true);
         if (!SimplifiedLHS.Diag && ! SimplifiedRHS.Diag) {
           S.Diag(SubstExpr->getBeginLoc(),
                  diag::note_atomic_constraint_evaluated_to_false_elaborated)
               << (int)First << SubstExpr
               << toString(SimplifiedLHS.Val.getInt(), 10)
               << BinaryOperator::getOpcodeStr(BO->getOpcode())
               << toString(SimplifiedRHS.Val.getInt(), 10);
           return;
         }
       }
       break;
 
     default:
       break;
     }
   } else if (auto *CSE = dyn_cast<ConceptSpecializationExpr>(SubstExpr)) {
     if (CSE->getTemplateArgsAsWritten()->NumTemplateArgs == 1) {
       S.Diag(
           CSE->getSourceRange().getBegin(),
           diag::
           note_single_arg_concept_specialization_constraint_evaluated_to_false)
           << (int)First
           << CSE->getTemplateArgsAsWritten()->arguments()[0].getArgument()
           << CSE->getNamedConcept();
     } else {
       S.Diag(SubstExpr->getSourceRange().getBegin(),
              diag::note_concept_specialization_constraint_evaluated_to_false)
           << (int)First << CSE;
     }
     S.DiagnoseUnsatisfiedConstraint(CSE->getSatisfaction());
     return;
   } else if (auto *RE = dyn_cast<RequiresExpr>(SubstExpr)) {
     // FIXME: RequiresExpr should store dependent diagnostics.
     for (concepts::Requirement *Req : RE->getRequirements())
       if (!Req->isDependent() && !Req->isSatisfied()) {
         if (auto *E = dyn_cast<concepts::ExprRequirement>(Req))
           diagnoseUnsatisfiedRequirement(S, E, First);
         else if (auto *T = dyn_cast<concepts::TypeRequirement>(Req))
           diagnoseUnsatisfiedRequirement(S, T, First);
         else
           diagnoseUnsatisfiedRequirement(
               S, cast<concepts::NestedRequirement>(Req), First);
         break;
       }
     return;
   }
 
   S.Diag(SubstExpr->getSourceRange().getBegin(),
          diag::note_atomic_constraint_evaluated_to_false)
       << (int)First << SubstExpr;
 }
 
 template<typename SubstitutionDiagnostic>
 static void diagnoseUnsatisfiedConstraintExpr(
     Sema &S, const Expr *E,
     const llvm::PointerUnion<Expr *, SubstitutionDiagnostic *> &Record,
     bool First = true) {
   if (auto *Diag = Record.template dyn_cast<SubstitutionDiagnostic *>()){
     S.Diag(Diag->first, diag::note_substituted_constraint_expr_is_ill_formed)
         << Diag->second;
     return;
   }
 
   diagnoseWellFormedUnsatisfiedConstraintExpr(S,
       Record.template get<Expr *>(), First);
 }
 
 void
 Sema::DiagnoseUnsatisfiedConstraint(const ConstraintSatisfaction& Satisfaction,
                                     bool First) {
   assert(!Satisfaction.IsSatisfied &&
          "Attempted to diagnose a satisfied constraint");
   for (auto &Pair : Satisfaction.Details) {
     diagnoseUnsatisfiedConstraintExpr(*this, Pair.first, Pair.second, First);
     First = false;
   }
 }
 
 void Sema::DiagnoseUnsatisfiedConstraint(
     const ASTConstraintSatisfaction &Satisfaction,
     bool First) {
   assert(!Satisfaction.IsSatisfied &&
          "Attempted to diagnose a satisfied constraint");
   for (auto &Pair : Satisfaction) {
     diagnoseUnsatisfiedConstraintExpr(*this, Pair.first, Pair.second, First);
     First = false;
   }
 }
 
 const NormalizedConstraint *
 Sema::getNormalizedAssociatedConstraints(
     NamedDecl *ConstrainedDecl, ArrayRef<const Expr *> AssociatedConstraints) {
   // In case the ConstrainedDecl comes from modules, it is necessary to use
   // the canonical decl to avoid different atomic constraints with the 'same'
   // declarations.
   ConstrainedDecl = cast<NamedDecl>(ConstrainedDecl->getCanonicalDecl());
 
   auto CacheEntry = NormalizationCache.find(ConstrainedDecl);
   if (CacheEntry == NormalizationCache.end()) {
     auto Normalized =
         NormalizedConstraint::fromConstraintExprs(*this, ConstrainedDecl,
                                                   AssociatedConstraints);
     CacheEntry =
         NormalizationCache
             .try_emplace(ConstrainedDecl,
                          Normalized
                              ? new (Context) NormalizedConstraint(
                                  std::move(*Normalized))
                              : nullptr)
             .first;
   }
   return CacheEntry->second;
 }
 
 static bool
 substituteParameterMappings(Sema &S, NormalizedConstraint &N,
                             ConceptDecl *Concept,
                             const MultiLevelTemplateArgumentList &MLTAL,
                             const ASTTemplateArgumentListInfo *ArgsAsWritten) {
   if (!N.isAtomic()) {
     if (substituteParameterMappings(S, N.getLHS(), Concept, MLTAL,
                                     ArgsAsWritten))
       return true;
     return substituteParameterMappings(S, N.getRHS(), Concept, MLTAL,
                                        ArgsAsWritten);
   }
   TemplateParameterList *TemplateParams = Concept->getTemplateParameters();
 
   AtomicConstraint &Atomic = *N.getAtomicConstraint();
   TemplateArgumentListInfo SubstArgs;
   if (!Atomic.ParameterMapping) {
     llvm::SmallBitVector OccurringIndices(TemplateParams->size());
     S.MarkUsedTemplateParameters(Atomic.ConstraintExpr, /*OnlyDeduced=*/false,
                                  /*Depth=*/0, OccurringIndices);
     TemplateArgumentLoc *TempArgs =
         new (S.Context) TemplateArgumentLoc[OccurringIndices.count()];
     for (unsigned I = 0, J = 0, C = TemplateParams->size(); I != C; ++I)
       if (OccurringIndices[I])
         new (&(TempArgs)[J++])
             TemplateArgumentLoc(S.getIdentityTemplateArgumentLoc(
                 TemplateParams->begin()[I],
                 // Here we assume we do not support things like
                 // template<typename A, typename B>
                 // concept C = ...;
                 //
                 // template<typename... Ts> requires C<Ts...>
                 // struct S { };
                 // The above currently yields a diagnostic.
                 // We still might have default arguments for concept parameters.
                 ArgsAsWritten->NumTemplateArgs > I
                     ? ArgsAsWritten->arguments()[I].getLocation()
                     : SourceLocation()));
     Atomic.ParameterMapping.emplace(TempArgs,  OccurringIndices.count());
   }
   Sema::InstantiatingTemplate Inst(
       S, ArgsAsWritten->arguments().front().getSourceRange().getBegin(),
       Sema::InstantiatingTemplate::ParameterMappingSubstitution{}, Concept,
       ArgsAsWritten->arguments().front().getSourceRange());
   if (S.SubstTemplateArguments(*Atomic.ParameterMapping, MLTAL, SubstArgs))
     return true;
 
   TemplateArgumentLoc *TempArgs =
       new (S.Context) TemplateArgumentLoc[SubstArgs.size()];
   std::copy(SubstArgs.arguments().begin(), SubstArgs.arguments().end(),
             TempArgs);
   Atomic.ParameterMapping.emplace(TempArgs, SubstArgs.size());
   return false;
 }
 
 static bool substituteParameterMappings(Sema &S, NormalizedConstraint &N,
                                         const ConceptSpecializationExpr *CSE) {
   TemplateArgumentList TAL{TemplateArgumentList::OnStack,
                            CSE->getTemplateArguments()};
   MultiLevelTemplateArgumentList MLTAL = S.getTemplateInstantiationArgs(
       CSE->getNamedConcept(), /*Final=*/false, &TAL,
       /*RelativeToPrimary=*/true,
       /*Pattern=*/nullptr,
       /*ForConstraintInstantiation=*/true);
 
   return substituteParameterMappings(S, N, CSE->getNamedConcept(), MLTAL,
                                      CSE->getTemplateArgsAsWritten());
 }
 
 std::optional<NormalizedConstraint>
 NormalizedConstraint::fromConstraintExprs(Sema &S, NamedDecl *D,
                                           ArrayRef<const Expr *> E) {
   assert(E.size() != 0);
   auto Conjunction = fromConstraintExpr(S, D, E[0]);
   if (!Conjunction)
     return std::nullopt;
   for (unsigned I = 1; I < E.size(); ++I) {
     auto Next = fromConstraintExpr(S, D, E[I]);
     if (!Next)
       return std::nullopt;
     *Conjunction = NormalizedConstraint(S.Context, std::move(*Conjunction),
                                         std::move(*Next), CCK_Conjunction);
   }
   return Conjunction;
 }
 
 std::optional<NormalizedConstraint>
 NormalizedConstraint::fromConstraintExpr(Sema &S, NamedDecl *D, const Expr *E) {
   assert(E != nullptr);
 
   // C++ [temp.constr.normal]p1.1
   // [...]
   // - The normal form of an expression (E) is the normal form of E.
   // [...]
   E = E->IgnoreParenImpCasts();
 
   // C++2a [temp.param]p4:
   //     [...] If T is not a pack, then E is E', otherwise E is (E' && ...).
   // Fold expression is considered atomic constraints per current wording.
   // See http://cplusplus.github.io/concepts-ts/ts-active.html#28
 
   if (LogicalBinOp BO = E) {
     auto LHS = fromConstraintExpr(S, D, BO.getLHS());
     if (!LHS)
       return std::nullopt;
     auto RHS = fromConstraintExpr(S, D, BO.getRHS());
     if (!RHS)
       return std::nullopt;
 
     return NormalizedConstraint(S.Context, std::move(*LHS), std::move(*RHS),
                                 BO.isAnd() ? CCK_Conjunction : CCK_Disjunction);
   } else if (auto *CSE = dyn_cast<const ConceptSpecializationExpr>(E)) {
     const NormalizedConstraint *SubNF;
     {
       Sema::InstantiatingTemplate Inst(
           S, CSE->getExprLoc(),
           Sema::InstantiatingTemplate::ConstraintNormalization{}, D,
           CSE->getSourceRange());
       // C++ [temp.constr.normal]p1.1
       // [...]
       // The normal form of an id-expression of the form C<A1, A2, ..., AN>,
       // where C names a concept, is the normal form of the
       // constraint-expression of C, after substituting A1, A2, ..., AN for C’s
       // respective template parameters in the parameter mappings in each atomic
       // constraint. If any such substitution results in an invalid type or
       // expression, the program is ill-formed; no diagnostic is required.
       // [...]
       ConceptDecl *CD = CSE->getNamedConcept();
       SubNF = S.getNormalizedAssociatedConstraints(CD,
                                                    {CD->getConstraintExpr()});
       if (!SubNF)
         return std::nullopt;
     }
 
     std::optional<NormalizedConstraint> New;
     New.emplace(S.Context, *SubNF);
 
     if (substituteParameterMappings(S, *New, CSE))
       return std::nullopt;
 
     return New;
   }
   return NormalizedConstraint{new (S.Context) AtomicConstraint(S, E)};
 }
 
 using NormalForm =
     llvm::SmallVector<llvm::SmallVector<AtomicConstraint *, 2>, 4>;
 
 static NormalForm makeCNF(const NormalizedConstraint &Normalized) {
   if (Normalized.isAtomic())
     return {{Normalized.getAtomicConstraint()}};
 
   NormalForm LCNF = makeCNF(Normalized.getLHS());
   NormalForm RCNF = makeCNF(Normalized.getRHS());
   if (Normalized.getCompoundKind() == NormalizedConstraint::CCK_Conjunction) {
     LCNF.reserve(LCNF.size() + RCNF.size());
     while (!RCNF.empty())
       LCNF.push_back(RCNF.pop_back_val());
     return LCNF;
   }
 
   // Disjunction
   NormalForm Res;
   Res.reserve(LCNF.size() * RCNF.size());
   for (auto &LDisjunction : LCNF)
     for (auto &RDisjunction : RCNF) {
       NormalForm::value_type Combined;
       Combined.reserve(LDisjunction.size() + RDisjunction.size());
       std::copy(LDisjunction.begin(), LDisjunction.end(),
                 std::back_inserter(Combined));
       std::copy(RDisjunction.begin(), RDisjunction.end(),
                 std::back_inserter(Combined));
       Res.emplace_back(Combined);
     }
   return Res;
 }
 
 static NormalForm makeDNF(const NormalizedConstraint &Normalized) {
   if (Normalized.isAtomic())
     return {{Normalized.getAtomicConstraint()}};
 
   NormalForm LDNF = makeDNF(Normalized.getLHS());
   NormalForm RDNF = makeDNF(Normalized.getRHS());
   if (Normalized.getCompoundKind() == NormalizedConstraint::CCK_Disjunction) {
     LDNF.reserve(LDNF.size() + RDNF.size());
     while (!RDNF.empty())
       LDNF.push_back(RDNF.pop_back_val());
     return LDNF;
   }
 
   // Conjunction
   NormalForm Res;
   Res.reserve(LDNF.size() * RDNF.size());
   for (auto &LConjunction : LDNF) {
     for (auto &RConjunction : RDNF) {
       NormalForm::value_type Combined;
       Combined.reserve(LConjunction.size() + RConjunction.size());
       std::copy(LConjunction.begin(), LConjunction.end(),
                 std::back_inserter(Combined));
       std::copy(RConjunction.begin(), RConjunction.end(),
                 std::back_inserter(Combined));
       Res.emplace_back(Combined);
     }
   }
   return Res;
 }
 
 template<typename AtomicSubsumptionEvaluator>
 static bool subsumes(const NormalForm &PDNF, const NormalForm &QCNF,
                      AtomicSubsumptionEvaluator E) {
   // C++ [temp.constr.order] p2
   //   Then, P subsumes Q if and only if, for every disjunctive clause Pi in the
   //   disjunctive normal form of P, Pi subsumes every conjunctive clause Qj in
   //   the conjuctive normal form of Q, where [...]
   for (const auto &Pi : PDNF) {
     for (const auto &Qj : QCNF) {
       // C++ [temp.constr.order] p2
       //   - [...] a disjunctive clause Pi subsumes a conjunctive clause Qj if
       //     and only if there exists an atomic constraint Pia in Pi for which
       //     there exists an atomic constraint, Qjb, in Qj such that Pia
       //     subsumes Qjb.
       bool Found = false;
       for (const AtomicConstraint *Pia : Pi) {
         for (const AtomicConstraint *Qjb : Qj) {
           if (E(*Pia, *Qjb)) {
             Found = true;
             break;
           }
         }
         if (Found)
           break;
       }
       if (!Found)
         return false;
     }
   }
   return true;
 }
 
 template<typename AtomicSubsumptionEvaluator>
 static bool subsumes(Sema &S, NamedDecl *DP, ArrayRef<const Expr *> P,
                      NamedDecl *DQ, ArrayRef<const Expr *> Q, bool &Subsumes,
                      AtomicSubsumptionEvaluator E) {
   // C++ [temp.constr.order] p2
   //   In order to determine if a constraint P subsumes a constraint Q, P is
   //   transformed into disjunctive normal form, and Q is transformed into
   //   conjunctive normal form. [...]
   auto *PNormalized = S.getNormalizedAssociatedConstraints(DP, P);
   if (!PNormalized)
     return true;
   const NormalForm PDNF = makeDNF(*PNormalized);
 
   auto *QNormalized = S.getNormalizedAssociatedConstraints(DQ, Q);
   if (!QNormalized)
     return true;
   const NormalForm QCNF = makeCNF(*QNormalized);
 
   Subsumes = subsumes(PDNF, QCNF, E);
   return false;
 }
 
 bool Sema::IsAtLeastAsConstrained(NamedDecl *D1,
                                   MutableArrayRef<const Expr *> AC1,
                                   NamedDecl *D2,
                                   MutableArrayRef<const Expr *> AC2,
                                   bool &Result) {
   if (const auto *FD1 = dyn_cast<FunctionDecl>(D1)) {
     auto IsExpectedEntity = [](const FunctionDecl *FD) {
       FunctionDecl::TemplatedKind Kind = FD->getTemplatedKind();
       return Kind == FunctionDecl::TK_NonTemplate ||
              Kind == FunctionDecl::TK_FunctionTemplate;
     };
     const auto *FD2 = dyn_cast<FunctionDecl>(D2);
     (void)IsExpectedEntity;
     (void)FD1;
     (void)FD2;
     assert(IsExpectedEntity(FD1) && FD2 && IsExpectedEntity(FD2) &&
            "use non-instantiated function declaration for constraints partial "
            "ordering");
   }
 
   if (AC1.empty()) {
     Result = AC2.empty();
     return false;
   }
   if (AC2.empty()) {
     // TD1 has associated constraints and TD2 does not.
     Result = true;
     return false;
   }
 
   std::pair<NamedDecl *, NamedDecl *> Key{D1, D2};
   auto CacheEntry = SubsumptionCache.find(Key);
   if (CacheEntry != SubsumptionCache.end()) {
     Result = CacheEntry->second;
     return false;
   }
 
   unsigned Depth1 = CalculateTemplateDepthForConstraints(*this, D1, true);
   unsigned Depth2 = CalculateTemplateDepthForConstraints(*this, D2, true);
 
   for (size_t I = 0; I != AC1.size() && I != AC2.size(); ++I) {
     if (Depth2 > Depth1) {
       AC1[I] = AdjustConstraintDepth(*this, Depth2 - Depth1)
                    .TransformExpr(const_cast<Expr *>(AC1[I]))
                    .get();
     } else if (Depth1 > Depth2) {
       AC2[I] = AdjustConstraintDepth(*this, Depth1 - Depth2)
                    .TransformExpr(const_cast<Expr *>(AC2[I]))
                    .get();
     }
   }
 
   if (subsumes(*this, D1, AC1, D2, AC2, Result,
         [this] (const AtomicConstraint &A, const AtomicConstraint &B) {
           return A.subsumes(Context, B);
         }))
     return true;
   SubsumptionCache.try_emplace(Key, Result);
   return false;
 }
 
 bool Sema::MaybeEmitAmbiguousAtomicConstraintsDiagnostic(NamedDecl *D1,
     ArrayRef<const Expr *> AC1, NamedDecl *D2, ArrayRef<const Expr *> AC2) {
   if (isSFINAEContext())
     // No need to work here because our notes would be discarded.
     return false;
 
   if (AC1.empty() || AC2.empty())
     return false;
 
   auto NormalExprEvaluator =
       [this] (const AtomicConstraint &A, const AtomicConstraint &B) {
         return A.subsumes(Context, B);
       };
 
   const Expr *AmbiguousAtomic1 = nullptr, *AmbiguousAtomic2 = nullptr;
   auto IdenticalExprEvaluator =
       [&] (const AtomicConstraint &A, const AtomicConstraint &B) {
         if (!A.hasMatchingParameterMapping(Context, B))
           return false;
         const Expr *EA = A.ConstraintExpr, *EB = B.ConstraintExpr;
         if (EA == EB)
           return true;
 
         // Not the same source level expression - are the expressions
         // identical?
         llvm::FoldingSetNodeID IDA, IDB;
         EA->Profile(IDA, Context, /*Canonical=*/true);
         EB->Profile(IDB, Context, /*Canonical=*/true);
         if (IDA != IDB)
           return false;
 
         AmbiguousAtomic1 = EA;
         AmbiguousAtomic2 = EB;
         return true;
       };
 
   {
     // The subsumption checks might cause diagnostics
     SFINAETrap Trap(*this);
     auto *Normalized1 = getNormalizedAssociatedConstraints(D1, AC1);
     if (!Normalized1)
       return false;
     const NormalForm DNF1 = makeDNF(*Normalized1);
     const NormalForm CNF1 = makeCNF(*Normalized1);
 
     auto *Normalized2 = getNormalizedAssociatedConstraints(D2, AC2);
     if (!Normalized2)
       return false;
     const NormalForm DNF2 = makeDNF(*Normalized2);
     const NormalForm CNF2 = makeCNF(*Normalized2);
 
     bool Is1AtLeastAs2Normally = subsumes(DNF1, CNF2, NormalExprEvaluator);
     bool Is2AtLeastAs1Normally = subsumes(DNF2, CNF1, NormalExprEvaluator);
     bool Is1AtLeastAs2 = subsumes(DNF1, CNF2, IdenticalExprEvaluator);
     bool Is2AtLeastAs1 = subsumes(DNF2, CNF1, IdenticalExprEvaluator);
     if (Is1AtLeastAs2 == Is1AtLeastAs2Normally &&
         Is2AtLeastAs1 == Is2AtLeastAs1Normally)
       // Same result - no ambiguity was caused by identical atomic expressions.
       return false;
   }
 
   // A different result! Some ambiguous atomic constraint(s) caused a difference
   assert(AmbiguousAtomic1 && AmbiguousAtomic2);
 
   Diag(AmbiguousAtomic1->getBeginLoc(), diag::note_ambiguous_atomic_constraints)
       << AmbiguousAtomic1->getSourceRange();
   Diag(AmbiguousAtomic2->getBeginLoc(),
        diag::note_ambiguous_atomic_constraints_similar_expression)
       << AmbiguousAtomic2->getSourceRange();
   return true;
 }
 
 concepts::ExprRequirement::ExprRequirement(
     Expr *E, bool IsSimple, SourceLocation NoexceptLoc,
     ReturnTypeRequirement Req, SatisfactionStatus Status,
     ConceptSpecializationExpr *SubstitutedConstraintExpr) :
     Requirement(IsSimple ? RK_Simple : RK_Compound, Status == SS_Dependent,
                 Status == SS_Dependent &&
                 (E->containsUnexpandedParameterPack() ||
                  Req.containsUnexpandedParameterPack()),
                 Status == SS_Satisfied), Value(E), NoexceptLoc(NoexceptLoc),
     TypeReq(Req), SubstitutedConstraintExpr(SubstitutedConstraintExpr),
     Status(Status) {
   assert((!IsSimple || (Req.isEmpty() && NoexceptLoc.isInvalid())) &&
          "Simple requirement must not have a return type requirement or a "
          "noexcept specification");
   assert((Status > SS_TypeRequirementSubstitutionFailure && Req.isTypeConstraint()) ==
          (SubstitutedConstraintExpr != nullptr));
 }
 
 concepts::ExprRequirement::ExprRequirement(
     SubstitutionDiagnostic *ExprSubstDiag, bool IsSimple,
     SourceLocation NoexceptLoc, ReturnTypeRequirement Req) :
     Requirement(IsSimple ? RK_Simple : RK_Compound, Req.isDependent(),
                 Req.containsUnexpandedParameterPack(), /*IsSatisfied=*/false),
     Value(ExprSubstDiag), NoexceptLoc(NoexceptLoc), TypeReq(Req),
     Status(SS_ExprSubstitutionFailure) {
   assert((!IsSimple || (Req.isEmpty() && NoexceptLoc.isInvalid())) &&
          "Simple requirement must not have a return type requirement or a "
          "noexcept specification");
 }
 
 concepts::ExprRequirement::ReturnTypeRequirement::
 ReturnTypeRequirement(TemplateParameterList *TPL) :
     TypeConstraintInfo(TPL, false) {
   assert(TPL->size() == 1);
   const TypeConstraint *TC =
       cast<TemplateTypeParmDecl>(TPL->getParam(0))->getTypeConstraint();
   assert(TC &&
          "TPL must have a template type parameter with a type constraint");
   auto *Constraint =
       cast<ConceptSpecializationExpr>(TC->getImmediatelyDeclaredConstraint());
   bool Dependent =
       Constraint->getTemplateArgsAsWritten() &&
       TemplateSpecializationType::anyInstantiationDependentTemplateArguments(
           Constraint->getTemplateArgsAsWritten()->arguments().drop_front(1));
   TypeConstraintInfo.setInt(Dependent ? true : false);
 }
 
 concepts::TypeRequirement::TypeRequirement(TypeSourceInfo *T) :
     Requirement(RK_Type, T->getType()->isInstantiationDependentType(),
                 T->getType()->containsUnexpandedParameterPack(),
                 // We reach this ctor with either dependent types (in which
                 // IsSatisfied doesn't matter) or with non-dependent type in
                 // which the existence of the type indicates satisfaction.
                 /*IsSatisfied=*/true),
     Value(T),
     Status(T->getType()->isInstantiationDependentType() ? SS_Dependent
                                                         : SS_Satisfied) {}
diff --git a/contrib/llvm-project/clang/lib/Sema/SemaDecl.cpp b/contrib/llvm-project/clang/lib/Sema/SemaDecl.cpp
index 21b5781a71cd..fab2865ec5a1 100644
--- a/contrib/llvm-project/clang/lib/Sema/SemaDecl.cpp
+++ b/contrib/llvm-project/clang/lib/Sema/SemaDecl.cpp
@@ -1,20109 +1,20113 @@
 //===--- SemaDecl.cpp - Semantic Analysis for Declarations ----------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 //  This file implements semantic analysis for declarations.
 //
 //===----------------------------------------------------------------------===//
 
 #include "TypeLocBuilder.h"
 #include "clang/AST/ASTConsumer.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/ASTLambda.h"
 #include "clang/AST/CXXInheritance.h"
 #include "clang/AST/CharUnits.h"
 #include "clang/AST/CommentDiagnostic.h"
 #include "clang/AST/DeclCXX.h"
 #include "clang/AST/DeclObjC.h"
 #include "clang/AST/DeclTemplate.h"
 #include "clang/AST/EvaluatedExprVisitor.h"
 #include "clang/AST/Expr.h"
 #include "clang/AST/ExprCXX.h"
 #include "clang/AST/NonTrivialTypeVisitor.h"
 #include "clang/AST/Randstruct.h"
 #include "clang/AST/StmtCXX.h"
 #include "clang/Basic/Builtins.h"
 #include "clang/Basic/HLSLRuntime.h"
 #include "clang/Basic/PartialDiagnostic.h"
 #include "clang/Basic/SourceManager.h"
 #include "clang/Basic/TargetInfo.h"
 #include "clang/Lex/HeaderSearch.h" // TODO: Sema shouldn't depend on Lex
 #include "clang/Lex/Lexer.h" // TODO: Extract static functions to fix layering.
 #include "clang/Lex/ModuleLoader.h" // TODO: Sema shouldn't depend on Lex
 #include "clang/Lex/Preprocessor.h" // Included for isCodeCompletionEnabled()
 #include "clang/Sema/CXXFieldCollector.h"
 #include "clang/Sema/DeclSpec.h"
 #include "clang/Sema/DelayedDiagnostic.h"
 #include "clang/Sema/Initialization.h"
 #include "clang/Sema/Lookup.h"
 #include "clang/Sema/ParsedTemplate.h"
 #include "clang/Sema/Scope.h"
 #include "clang/Sema/ScopeInfo.h"
 #include "clang/Sema/SemaInternal.h"
 #include "clang/Sema/Template.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/TargetParser/Triple.h"
 #include <algorithm>
 #include <cstring>
 #include <functional>
 #include <optional>
 #include <unordered_map>
 
 using namespace clang;
 using namespace sema;
 
 Sema::DeclGroupPtrTy Sema::ConvertDeclToDeclGroup(Decl *Ptr, Decl *OwnedType) {
   if (OwnedType) {
     Decl *Group[2] = { OwnedType, Ptr };
     return DeclGroupPtrTy::make(DeclGroupRef::Create(Context, Group, 2));
   }
 
   return DeclGroupPtrTy::make(DeclGroupRef(Ptr));
 }
 
 namespace {
 
 class TypeNameValidatorCCC final : public CorrectionCandidateCallback {
  public:
    TypeNameValidatorCCC(bool AllowInvalid, bool WantClass = false,
                         bool AllowTemplates = false,
                         bool AllowNonTemplates = true)
        : AllowInvalidDecl(AllowInvalid), WantClassName(WantClass),
          AllowTemplates(AllowTemplates), AllowNonTemplates(AllowNonTemplates) {
      WantExpressionKeywords = false;
      WantCXXNamedCasts = false;
      WantRemainingKeywords = false;
   }
 
   bool ValidateCandidate(const TypoCorrection &candidate) override {
     if (NamedDecl *ND = candidate.getCorrectionDecl()) {
       if (!AllowInvalidDecl && ND->isInvalidDecl())
         return false;
 
       if (getAsTypeTemplateDecl(ND))
         return AllowTemplates;
 
       bool IsType = isa<TypeDecl>(ND) || isa<ObjCInterfaceDecl>(ND);
       if (!IsType)
         return false;
 
       if (AllowNonTemplates)
         return true;
 
       // An injected-class-name of a class template (specialization) is valid
       // as a template or as a non-template.
       if (AllowTemplates) {
         auto *RD = dyn_cast<CXXRecordDecl>(ND);
         if (!RD || !RD->isInjectedClassName())
           return false;
         RD = cast<CXXRecordDecl>(RD->getDeclContext());
         return RD->getDescribedClassTemplate() ||
                isa<ClassTemplateSpecializationDecl>(RD);
       }
 
       return false;
     }
 
     return !WantClassName && candidate.isKeyword();
   }
 
   std::unique_ptr<CorrectionCandidateCallback> clone() override {
     return std::make_unique<TypeNameValidatorCCC>(*this);
   }
 
  private:
   bool AllowInvalidDecl;
   bool WantClassName;
   bool AllowTemplates;
   bool AllowNonTemplates;
 };
 
 } // end anonymous namespace
 
 /// Determine whether the token kind starts a simple-type-specifier.
 bool Sema::isSimpleTypeSpecifier(tok::TokenKind Kind) const {
   switch (Kind) {
   // FIXME: Take into account the current language when deciding whether a
   // token kind is a valid type specifier
   case tok::kw_short:
   case tok::kw_long:
   case tok::kw___int64:
   case tok::kw___int128:
   case tok::kw_signed:
   case tok::kw_unsigned:
   case tok::kw_void:
   case tok::kw_char:
   case tok::kw_int:
   case tok::kw_half:
   case tok::kw_float:
   case tok::kw_double:
   case tok::kw___bf16:
   case tok::kw__Float16:
   case tok::kw___float128:
   case tok::kw___ibm128:
   case tok::kw_wchar_t:
   case tok::kw_bool:
 #define TRANSFORM_TYPE_TRAIT_DEF(_, Trait) case tok::kw___##Trait:
 #include "clang/Basic/TransformTypeTraits.def"
   case tok::kw___auto_type:
     return true;
 
   case tok::annot_typename:
   case tok::kw_char16_t:
   case tok::kw_char32_t:
   case tok::kw_typeof:
   case tok::annot_decltype:
   case tok::kw_decltype:
     return getLangOpts().CPlusPlus;
 
   case tok::kw_char8_t:
     return getLangOpts().Char8;
 
   default:
     break;
   }
 
   return false;
 }
 
 namespace {
 enum class UnqualifiedTypeNameLookupResult {
   NotFound,
   FoundNonType,
   FoundType
 };
 } // end anonymous namespace
 
 /// Tries to perform unqualified lookup of the type decls in bases for
 /// dependent class.
 /// \return \a NotFound if no any decls is found, \a FoundNotType if found not a
 /// type decl, \a FoundType if only type decls are found.
 static UnqualifiedTypeNameLookupResult
 lookupUnqualifiedTypeNameInBase(Sema &S, const IdentifierInfo &II,
                                 SourceLocation NameLoc,
                                 const CXXRecordDecl *RD) {
   if (!RD->hasDefinition())
     return UnqualifiedTypeNameLookupResult::NotFound;
   // Look for type decls in base classes.
   UnqualifiedTypeNameLookupResult FoundTypeDecl =
       UnqualifiedTypeNameLookupResult::NotFound;
   for (const auto &Base : RD->bases()) {
     const CXXRecordDecl *BaseRD = nullptr;
     if (auto *BaseTT = Base.getType()->getAs<TagType>())
       BaseRD = BaseTT->getAsCXXRecordDecl();
     else if (auto *TST = Base.getType()->getAs<TemplateSpecializationType>()) {
       // Look for type decls in dependent base classes that have known primary
       // templates.
       if (!TST || !TST->isDependentType())
         continue;
       auto *TD = TST->getTemplateName().getAsTemplateDecl();
       if (!TD)
         continue;
       if (auto *BasePrimaryTemplate =
           dyn_cast_or_null<CXXRecordDecl>(TD->getTemplatedDecl())) {
         if (BasePrimaryTemplate->getCanonicalDecl() != RD->getCanonicalDecl())
           BaseRD = BasePrimaryTemplate;
         else if (auto *CTD = dyn_cast<ClassTemplateDecl>(TD)) {
           if (const ClassTemplatePartialSpecializationDecl *PS =
                   CTD->findPartialSpecialization(Base.getType()))
             if (PS->getCanonicalDecl() != RD->getCanonicalDecl())
               BaseRD = PS;
         }
       }
     }
     if (BaseRD) {
       for (NamedDecl *ND : BaseRD->lookup(&II)) {
         if (!isa<TypeDecl>(ND))
           return UnqualifiedTypeNameLookupResult::FoundNonType;
         FoundTypeDecl = UnqualifiedTypeNameLookupResult::FoundType;
       }
       if (FoundTypeDecl == UnqualifiedTypeNameLookupResult::NotFound) {
         switch (lookupUnqualifiedTypeNameInBase(S, II, NameLoc, BaseRD)) {
         case UnqualifiedTypeNameLookupResult::FoundNonType:
           return UnqualifiedTypeNameLookupResult::FoundNonType;
         case UnqualifiedTypeNameLookupResult::FoundType:
           FoundTypeDecl = UnqualifiedTypeNameLookupResult::FoundType;
           break;
         case UnqualifiedTypeNameLookupResult::NotFound:
           break;
         }
       }
     }
   }
 
   return FoundTypeDecl;
 }
 
 static ParsedType recoverFromTypeInKnownDependentBase(Sema &S,
                                                       const IdentifierInfo &II,
                                                       SourceLocation NameLoc) {
   // Lookup in the parent class template context, if any.
   const CXXRecordDecl *RD = nullptr;
   UnqualifiedTypeNameLookupResult FoundTypeDecl =
       UnqualifiedTypeNameLookupResult::NotFound;
   for (DeclContext *DC = S.CurContext;
        DC && FoundTypeDecl == UnqualifiedTypeNameLookupResult::NotFound;
        DC = DC->getParent()) {
     // Look for type decls in dependent base classes that have known primary
     // templates.
     RD = dyn_cast<CXXRecordDecl>(DC);
     if (RD && RD->getDescribedClassTemplate())
       FoundTypeDecl = lookupUnqualifiedTypeNameInBase(S, II, NameLoc, RD);
   }
   if (FoundTypeDecl != UnqualifiedTypeNameLookupResult::FoundType)
     return nullptr;
 
   // We found some types in dependent base classes.  Recover as if the user
   // wrote 'typename MyClass::II' instead of 'II'.  We'll fully resolve the
   // lookup during template instantiation.
   S.Diag(NameLoc, diag::ext_found_in_dependent_base) << &II;
 
   ASTContext &Context = S.Context;
   auto *NNS = NestedNameSpecifier::Create(Context, nullptr, false,
                                           cast<Type>(Context.getRecordType(RD)));
   QualType T = Context.getDependentNameType(ETK_Typename, NNS, &II);
 
   CXXScopeSpec SS;
   SS.MakeTrivial(Context, NNS, SourceRange(NameLoc));
 
   TypeLocBuilder Builder;
   DependentNameTypeLoc DepTL = Builder.push<DependentNameTypeLoc>(T);
   DepTL.setNameLoc(NameLoc);
   DepTL.setElaboratedKeywordLoc(SourceLocation());
   DepTL.setQualifierLoc(SS.getWithLocInContext(Context));
   return S.CreateParsedType(T, Builder.getTypeSourceInfo(Context, T));
 }
 
 /// Build a ParsedType for a simple-type-specifier with a nested-name-specifier.
 static ParsedType buildNamedType(Sema &S, const CXXScopeSpec *SS, QualType T,
                                  SourceLocation NameLoc,
                                  bool WantNontrivialTypeSourceInfo = true) {
   switch (T->getTypeClass()) {
   case Type::DeducedTemplateSpecialization:
   case Type::Enum:
   case Type::InjectedClassName:
   case Type::Record:
   case Type::Typedef:
   case Type::UnresolvedUsing:
   case Type::Using:
     break;
   // These can never be qualified so an ElaboratedType node
   // would carry no additional meaning.
   case Type::ObjCInterface:
   case Type::ObjCTypeParam:
   case Type::TemplateTypeParm:
     return ParsedType::make(T);
   default:
     llvm_unreachable("Unexpected Type Class");
   }
 
   if (!SS || SS->isEmpty())
     return ParsedType::make(
         S.Context.getElaboratedType(ETK_None, nullptr, T, nullptr));
 
   QualType ElTy = S.getElaboratedType(ETK_None, *SS, T);
   if (!WantNontrivialTypeSourceInfo)
     return ParsedType::make(ElTy);
 
   TypeLocBuilder Builder;
   Builder.pushTypeSpec(T).setNameLoc(NameLoc);
   ElaboratedTypeLoc ElabTL = Builder.push<ElaboratedTypeLoc>(ElTy);
   ElabTL.setElaboratedKeywordLoc(SourceLocation());
   ElabTL.setQualifierLoc(SS->getWithLocInContext(S.Context));
   return S.CreateParsedType(ElTy, Builder.getTypeSourceInfo(S.Context, ElTy));
 }
 
 /// If the identifier refers to a type name within this scope,
 /// return the declaration of that type.
 ///
 /// This routine performs ordinary name lookup of the identifier II
 /// within the given scope, with optional C++ scope specifier SS, to
 /// determine whether the name refers to a type. If so, returns an
 /// opaque pointer (actually a QualType) corresponding to that
 /// type. Otherwise, returns NULL.
 ParsedType Sema::getTypeName(const IdentifierInfo &II, SourceLocation NameLoc,
                              Scope *S, CXXScopeSpec *SS, bool isClassName,
                              bool HasTrailingDot, ParsedType ObjectTypePtr,
                              bool IsCtorOrDtorName,
                              bool WantNontrivialTypeSourceInfo,
                              bool IsClassTemplateDeductionContext,
                              ImplicitTypenameContext AllowImplicitTypename,
                              IdentifierInfo **CorrectedII) {
   // FIXME: Consider allowing this outside C++1z mode as an extension.
   bool AllowDeducedTemplate = IsClassTemplateDeductionContext &&
                               getLangOpts().CPlusPlus17 && !IsCtorOrDtorName &&
                               !isClassName && !HasTrailingDot;
 
   // Determine where we will perform name lookup.
   DeclContext *LookupCtx = nullptr;
   if (ObjectTypePtr) {
     QualType ObjectType = ObjectTypePtr.get();
     if (ObjectType->isRecordType())
       LookupCtx = computeDeclContext(ObjectType);
   } else if (SS && SS->isNotEmpty()) {
     LookupCtx = computeDeclContext(*SS, false);
 
     if (!LookupCtx) {
       if (isDependentScopeSpecifier(*SS)) {
         // C++ [temp.res]p3:
         //   A qualified-id that refers to a type and in which the
         //   nested-name-specifier depends on a template-parameter (14.6.2)
         //   shall be prefixed by the keyword typename to indicate that the
         //   qualified-id denotes a type, forming an
         //   elaborated-type-specifier (7.1.5.3).
         //
         // We therefore do not perform any name lookup if the result would
         // refer to a member of an unknown specialization.
         // In C++2a, in several contexts a 'typename' is not required. Also
         // allow this as an extension.
         if (AllowImplicitTypename == ImplicitTypenameContext::No &&
             !isClassName && !IsCtorOrDtorName)
           return nullptr;
         bool IsImplicitTypename = !isClassName && !IsCtorOrDtorName;
         if (IsImplicitTypename) {
           SourceLocation QualifiedLoc = SS->getRange().getBegin();
           if (getLangOpts().CPlusPlus20)
             Diag(QualifiedLoc, diag::warn_cxx17_compat_implicit_typename);
           else
             Diag(QualifiedLoc, diag::ext_implicit_typename)
                 << SS->getScopeRep() << II.getName()
                 << FixItHint::CreateInsertion(QualifiedLoc, "typename ");
         }
 
         // We know from the grammar that this name refers to a type,
         // so build a dependent node to describe the type.
         if (WantNontrivialTypeSourceInfo)
           return ActOnTypenameType(S, SourceLocation(), *SS, II, NameLoc,
                                    (ImplicitTypenameContext)IsImplicitTypename)
               .get();
 
         NestedNameSpecifierLoc QualifierLoc = SS->getWithLocInContext(Context);
         QualType T =
             CheckTypenameType(IsImplicitTypename ? ETK_Typename : ETK_None,
                               SourceLocation(), QualifierLoc, II, NameLoc);
         return ParsedType::make(T);
       }
 
       return nullptr;
     }
 
     if (!LookupCtx->isDependentContext() &&
         RequireCompleteDeclContext(*SS, LookupCtx))
       return nullptr;
   }
 
   // FIXME: LookupNestedNameSpecifierName isn't the right kind of
   // lookup for class-names.
   LookupNameKind Kind = isClassName ? LookupNestedNameSpecifierName :
                                       LookupOrdinaryName;
   LookupResult Result(*this, &II, NameLoc, Kind);
   if (LookupCtx) {
     // Perform "qualified" name lookup into the declaration context we
     // computed, which is either the type of the base of a member access
     // expression or the declaration context associated with a prior
     // nested-name-specifier.
     LookupQualifiedName(Result, LookupCtx);
 
     if (ObjectTypePtr && Result.empty()) {
       // C++ [basic.lookup.classref]p3:
       //   If the unqualified-id is ~type-name, the type-name is looked up
       //   in the context of the entire postfix-expression. If the type T of
       //   the object expression is of a class type C, the type-name is also
       //   looked up in the scope of class C. At least one of the lookups shall
       //   find a name that refers to (possibly cv-qualified) T.
       LookupName(Result, S);
     }
   } else {
     // Perform unqualified name lookup.
     LookupName(Result, S);
 
     // For unqualified lookup in a class template in MSVC mode, look into
     // dependent base classes where the primary class template is known.
     if (Result.empty() && getLangOpts().MSVCCompat && (!SS || SS->isEmpty())) {
       if (ParsedType TypeInBase =
               recoverFromTypeInKnownDependentBase(*this, II, NameLoc))
         return TypeInBase;
     }
   }
 
   NamedDecl *IIDecl = nullptr;
   UsingShadowDecl *FoundUsingShadow = nullptr;
   switch (Result.getResultKind()) {
   case LookupResult::NotFound:
   case LookupResult::NotFoundInCurrentInstantiation:
     if (CorrectedII) {
       TypeNameValidatorCCC CCC(/*AllowInvalid=*/true, isClassName,
                                AllowDeducedTemplate);
       TypoCorrection Correction = CorrectTypo(Result.getLookupNameInfo(), Kind,
                                               S, SS, CCC, CTK_ErrorRecovery);
       IdentifierInfo *NewII = Correction.getCorrectionAsIdentifierInfo();
       TemplateTy Template;
       bool MemberOfUnknownSpecialization;
       UnqualifiedId TemplateName;
       TemplateName.setIdentifier(NewII, NameLoc);
       NestedNameSpecifier *NNS = Correction.getCorrectionSpecifier();
       CXXScopeSpec NewSS, *NewSSPtr = SS;
       if (SS && NNS) {
         NewSS.MakeTrivial(Context, NNS, SourceRange(NameLoc));
         NewSSPtr = &NewSS;
       }
       if (Correction && (NNS || NewII != &II) &&
           // Ignore a correction to a template type as the to-be-corrected
           // identifier is not a template (typo correction for template names
           // is handled elsewhere).
           !(getLangOpts().CPlusPlus && NewSSPtr &&
             isTemplateName(S, *NewSSPtr, false, TemplateName, nullptr, false,
                            Template, MemberOfUnknownSpecialization))) {
         ParsedType Ty = getTypeName(*NewII, NameLoc, S, NewSSPtr,
                                     isClassName, HasTrailingDot, ObjectTypePtr,
                                     IsCtorOrDtorName,
                                     WantNontrivialTypeSourceInfo,
                                     IsClassTemplateDeductionContext);
         if (Ty) {
           diagnoseTypo(Correction,
                        PDiag(diag::err_unknown_type_or_class_name_suggest)
                          << Result.getLookupName() << isClassName);
           if (SS && NNS)
             SS->MakeTrivial(Context, NNS, SourceRange(NameLoc));
           *CorrectedII = NewII;
           return Ty;
         }
       }
     }
     // If typo correction failed or was not performed, fall through
     [[fallthrough]];
   case LookupResult::FoundOverloaded:
   case LookupResult::FoundUnresolvedValue:
     Result.suppressDiagnostics();
     return nullptr;
 
   case LookupResult::Ambiguous:
     // Recover from type-hiding ambiguities by hiding the type.  We'll
     // do the lookup again when looking for an object, and we can
     // diagnose the error then.  If we don't do this, then the error
     // about hiding the type will be immediately followed by an error
     // that only makes sense if the identifier was treated like a type.
     if (Result.getAmbiguityKind() == LookupResult::AmbiguousTagHiding) {
       Result.suppressDiagnostics();
       return nullptr;
     }
 
     // Look to see if we have a type anywhere in the list of results.
     for (LookupResult::iterator Res = Result.begin(), ResEnd = Result.end();
          Res != ResEnd; ++Res) {
       NamedDecl *RealRes = (*Res)->getUnderlyingDecl();
       if (isa<TypeDecl, ObjCInterfaceDecl, UnresolvedUsingIfExistsDecl>(
               RealRes) ||
           (AllowDeducedTemplate && getAsTypeTemplateDecl(RealRes))) {
         if (!IIDecl ||
             // Make the selection of the recovery decl deterministic.
             RealRes->getLocation() < IIDecl->getLocation()) {
           IIDecl = RealRes;
           FoundUsingShadow = dyn_cast<UsingShadowDecl>(*Res);
         }
       }
     }
 
     if (!IIDecl) {
       // None of the entities we found is a type, so there is no way
       // to even assume that the result is a type. In this case, don't
       // complain about the ambiguity. The parser will either try to
       // perform this lookup again (e.g., as an object name), which
       // will produce the ambiguity, or will complain that it expected
       // a type name.
       Result.suppressDiagnostics();
       return nullptr;
     }
 
     // We found a type within the ambiguous lookup; diagnose the
     // ambiguity and then return that type. This might be the right
     // answer, or it might not be, but it suppresses any attempt to
     // perform the name lookup again.
     break;
 
   case LookupResult::Found:
     IIDecl = Result.getFoundDecl();
     FoundUsingShadow = dyn_cast<UsingShadowDecl>(*Result.begin());
     break;
   }
 
   assert(IIDecl && "Didn't find decl");
 
   QualType T;
   if (TypeDecl *TD = dyn_cast<TypeDecl>(IIDecl)) {
     // C++ [class.qual]p2: A lookup that would find the injected-class-name
     // instead names the constructors of the class, except when naming a class.
     // This is ill-formed when we're not actually forming a ctor or dtor name.
     auto *LookupRD = dyn_cast_or_null<CXXRecordDecl>(LookupCtx);
     auto *FoundRD = dyn_cast<CXXRecordDecl>(TD);
     if (!isClassName && !IsCtorOrDtorName && LookupRD && FoundRD &&
         FoundRD->isInjectedClassName() &&
         declaresSameEntity(LookupRD, cast<Decl>(FoundRD->getParent())))
       Diag(NameLoc, diag::err_out_of_line_qualified_id_type_names_constructor)
           << &II << /*Type*/1;
 
     DiagnoseUseOfDecl(IIDecl, NameLoc);
 
     T = Context.getTypeDeclType(TD);
     MarkAnyDeclReferenced(TD->getLocation(), TD, /*OdrUse=*/false);
   } else if (ObjCInterfaceDecl *IDecl = dyn_cast<ObjCInterfaceDecl>(IIDecl)) {
     (void)DiagnoseUseOfDecl(IDecl, NameLoc);
     if (!HasTrailingDot)
       T = Context.getObjCInterfaceType(IDecl);
     FoundUsingShadow = nullptr; // FIXME: Target must be a TypeDecl.
   } else if (auto *UD = dyn_cast<UnresolvedUsingIfExistsDecl>(IIDecl)) {
     (void)DiagnoseUseOfDecl(UD, NameLoc);
     // Recover with 'int'
     return ParsedType::make(Context.IntTy);
   } else if (AllowDeducedTemplate) {
     if (auto *TD = getAsTypeTemplateDecl(IIDecl)) {
       assert(!FoundUsingShadow || FoundUsingShadow->getTargetDecl() == TD);
       TemplateName Template =
           FoundUsingShadow ? TemplateName(FoundUsingShadow) : TemplateName(TD);
       T = Context.getDeducedTemplateSpecializationType(Template, QualType(),
                                                        false);
       // Don't wrap in a further UsingType.
       FoundUsingShadow = nullptr;
     }
   }
 
   if (T.isNull()) {
     // If it's not plausibly a type, suppress diagnostics.
     Result.suppressDiagnostics();
     return nullptr;
   }
 
   if (FoundUsingShadow)
     T = Context.getUsingType(FoundUsingShadow, T);
 
   return buildNamedType(*this, SS, T, NameLoc, WantNontrivialTypeSourceInfo);
 }
 
 // Builds a fake NNS for the given decl context.
 static NestedNameSpecifier *
 synthesizeCurrentNestedNameSpecifier(ASTContext &Context, DeclContext *DC) {
   for (;; DC = DC->getLookupParent()) {
     DC = DC->getPrimaryContext();
     auto *ND = dyn_cast<NamespaceDecl>(DC);
     if (ND && !ND->isInline() && !ND->isAnonymousNamespace())
       return NestedNameSpecifier::Create(Context, nullptr, ND);
     else if (auto *RD = dyn_cast<CXXRecordDecl>(DC))
       return NestedNameSpecifier::Create(Context, nullptr, RD->isTemplateDecl(),
                                          RD->getTypeForDecl());
     else if (isa<TranslationUnitDecl>(DC))
       return NestedNameSpecifier::GlobalSpecifier(Context);
   }
   llvm_unreachable("something isn't in TU scope?");
 }
 
 /// Find the parent class with dependent bases of the innermost enclosing method
 /// context. Do not look for enclosing CXXRecordDecls directly, or we will end
 /// up allowing unqualified dependent type names at class-level, which MSVC
 /// correctly rejects.
 static const CXXRecordDecl *
 findRecordWithDependentBasesOfEnclosingMethod(const DeclContext *DC) {
   for (; DC && DC->isDependentContext(); DC = DC->getLookupParent()) {
     DC = DC->getPrimaryContext();
     if (const auto *MD = dyn_cast<CXXMethodDecl>(DC))
       if (MD->getParent()->hasAnyDependentBases())
         return MD->getParent();
   }
   return nullptr;
 }
 
 ParsedType Sema::ActOnMSVCUnknownTypeName(const IdentifierInfo &II,
                                           SourceLocation NameLoc,
                                           bool IsTemplateTypeArg) {
   assert(getLangOpts().MSVCCompat && "shouldn't be called in non-MSVC mode");
 
   NestedNameSpecifier *NNS = nullptr;
   if (IsTemplateTypeArg && getCurScope()->isTemplateParamScope()) {
     // If we weren't able to parse a default template argument, delay lookup
     // until instantiation time by making a non-dependent DependentTypeName. We
     // pretend we saw a NestedNameSpecifier referring to the current scope, and
     // lookup is retried.
     // FIXME: This hurts our diagnostic quality, since we get errors like "no
     // type named 'Foo' in 'current_namespace'" when the user didn't write any
     // name specifiers.
     NNS = synthesizeCurrentNestedNameSpecifier(Context, CurContext);
     Diag(NameLoc, diag::ext_ms_delayed_template_argument) << &II;
   } else if (const CXXRecordDecl *RD =
                  findRecordWithDependentBasesOfEnclosingMethod(CurContext)) {
     // Build a DependentNameType that will perform lookup into RD at
     // instantiation time.
     NNS = NestedNameSpecifier::Create(Context, nullptr, RD->isTemplateDecl(),
                                       RD->getTypeForDecl());
 
     // Diagnose that this identifier was undeclared, and retry the lookup during
     // template instantiation.
     Diag(NameLoc, diag::ext_undeclared_unqual_id_with_dependent_base) << &II
                                                                       << RD;
   } else {
     // This is not a situation that we should recover from.
     return ParsedType();
   }
 
   QualType T = Context.getDependentNameType(ETK_None, NNS, &II);
 
   // Build type location information.  We synthesized the qualifier, so we have
   // to build a fake NestedNameSpecifierLoc.
   NestedNameSpecifierLocBuilder NNSLocBuilder;
   NNSLocBuilder.MakeTrivial(Context, NNS, SourceRange(NameLoc));
   NestedNameSpecifierLoc QualifierLoc = NNSLocBuilder.getWithLocInContext(Context);
 
   TypeLocBuilder Builder;
   DependentNameTypeLoc DepTL = Builder.push<DependentNameTypeLoc>(T);
   DepTL.setNameLoc(NameLoc);
   DepTL.setElaboratedKeywordLoc(SourceLocation());
   DepTL.setQualifierLoc(QualifierLoc);
   return CreateParsedType(T, Builder.getTypeSourceInfo(Context, T));
 }
 
 /// isTagName() - This method is called *for error recovery purposes only*
 /// to determine if the specified name is a valid tag name ("struct foo").  If
 /// so, this returns the TST for the tag corresponding to it (TST_enum,
 /// TST_union, TST_struct, TST_interface, TST_class).  This is used to diagnose
 /// cases in C where the user forgot to specify the tag.
 DeclSpec::TST Sema::isTagName(IdentifierInfo &II, Scope *S) {
   // Do a tag name lookup in this scope.
   LookupResult R(*this, &II, SourceLocation(), LookupTagName);
   LookupName(R, S, false);
   R.suppressDiagnostics();
   if (R.getResultKind() == LookupResult::Found)
     if (const TagDecl *TD = R.getAsSingle<TagDecl>()) {
       switch (TD->getTagKind()) {
       case TTK_Struct: return DeclSpec::TST_struct;
       case TTK_Interface: return DeclSpec::TST_interface;
       case TTK_Union:  return DeclSpec::TST_union;
       case TTK_Class:  return DeclSpec::TST_class;
       case TTK_Enum:   return DeclSpec::TST_enum;
       }
     }
 
   return DeclSpec::TST_unspecified;
 }
 
 /// isMicrosoftMissingTypename - In Microsoft mode, within class scope,
 /// if a CXXScopeSpec's type is equal to the type of one of the base classes
 /// then downgrade the missing typename error to a warning.
 /// This is needed for MSVC compatibility; Example:
 /// @code
 /// template<class T> class A {
 /// public:
 ///   typedef int TYPE;
 /// };
 /// template<class T> class B : public A<T> {
 /// public:
 ///   A<T>::TYPE a; // no typename required because A<T> is a base class.
 /// };
 /// @endcode
 bool Sema::isMicrosoftMissingTypename(const CXXScopeSpec *SS, Scope *S) {
   if (CurContext->isRecord()) {
     if (SS->getScopeRep()->getKind() == NestedNameSpecifier::Super)
       return true;
 
     const Type *Ty = SS->getScopeRep()->getAsType();
 
     CXXRecordDecl *RD = cast<CXXRecordDecl>(CurContext);
     for (const auto &Base : RD->bases())
       if (Ty && Context.hasSameUnqualifiedType(QualType(Ty, 1), Base.getType()))
         return true;
     return S->isFunctionPrototypeScope();
   }
   return CurContext->isFunctionOrMethod() || S->isFunctionPrototypeScope();
 }
 
 void Sema::DiagnoseUnknownTypeName(IdentifierInfo *&II,
                                    SourceLocation IILoc,
                                    Scope *S,
                                    CXXScopeSpec *SS,
                                    ParsedType &SuggestedType,
                                    bool IsTemplateName) {
   // Don't report typename errors for editor placeholders.
   if (II->isEditorPlaceholder())
     return;
   // We don't have anything to suggest (yet).
   SuggestedType = nullptr;
 
   // There may have been a typo in the name of the type. Look up typo
   // results, in case we have something that we can suggest.
   TypeNameValidatorCCC CCC(/*AllowInvalid=*/false, /*WantClass=*/false,
                            /*AllowTemplates=*/IsTemplateName,
                            /*AllowNonTemplates=*/!IsTemplateName);
   if (TypoCorrection Corrected =
           CorrectTypo(DeclarationNameInfo(II, IILoc), LookupOrdinaryName, S, SS,
                       CCC, CTK_ErrorRecovery)) {
     // FIXME: Support error recovery for the template-name case.
     bool CanRecover = !IsTemplateName;
     if (Corrected.isKeyword()) {
       // We corrected to a keyword.
       diagnoseTypo(Corrected,
                    PDiag(IsTemplateName ? diag::err_no_template_suggest
                                         : diag::err_unknown_typename_suggest)
                        << II);
       II = Corrected.getCorrectionAsIdentifierInfo();
     } else {
       // We found a similarly-named type or interface; suggest that.
       if (!SS || !SS->isSet()) {
         diagnoseTypo(Corrected,
                      PDiag(IsTemplateName ? diag::err_no_template_suggest
                                           : diag::err_unknown_typename_suggest)
                          << II, CanRecover);
       } else if (DeclContext *DC = computeDeclContext(*SS, false)) {
         std::string CorrectedStr(Corrected.getAsString(getLangOpts()));
         bool DroppedSpecifier = Corrected.WillReplaceSpecifier() &&
                                 II->getName().equals(CorrectedStr);
         diagnoseTypo(Corrected,
                      PDiag(IsTemplateName
                                ? diag::err_no_member_template_suggest
                                : diag::err_unknown_nested_typename_suggest)
                          << II << DC << DroppedSpecifier << SS->getRange(),
                      CanRecover);
       } else {
         llvm_unreachable("could not have corrected a typo here");
       }
 
       if (!CanRecover)
         return;
 
       CXXScopeSpec tmpSS;
       if (Corrected.getCorrectionSpecifier())
         tmpSS.MakeTrivial(Context, Corrected.getCorrectionSpecifier(),
                           SourceRange(IILoc));
       // FIXME: Support class template argument deduction here.
       SuggestedType =
           getTypeName(*Corrected.getCorrectionAsIdentifierInfo(), IILoc, S,
                       tmpSS.isSet() ? &tmpSS : SS, false, false, nullptr,
                       /*IsCtorOrDtorName=*/false,
                       /*WantNontrivialTypeSourceInfo=*/true);
     }
     return;
   }
 
   if (getLangOpts().CPlusPlus && !IsTemplateName) {
     // See if II is a class template that the user forgot to pass arguments to.
     UnqualifiedId Name;
     Name.setIdentifier(II, IILoc);
     CXXScopeSpec EmptySS;
     TemplateTy TemplateResult;
     bool MemberOfUnknownSpecialization;
     if (isTemplateName(S, SS ? *SS : EmptySS, /*hasTemplateKeyword=*/false,
                        Name, nullptr, true, TemplateResult,
                        MemberOfUnknownSpecialization) == TNK_Type_template) {
       diagnoseMissingTemplateArguments(TemplateResult.get(), IILoc);
       return;
     }
   }
 
   // FIXME: Should we move the logic that tries to recover from a missing tag
   // (struct, union, enum) from Parser::ParseImplicitInt here, instead?
 
   if (!SS || (!SS->isSet() && !SS->isInvalid()))
     Diag(IILoc, IsTemplateName ? diag::err_no_template
                                : diag::err_unknown_typename)
         << II;
   else if (DeclContext *DC = computeDeclContext(*SS, false))
     Diag(IILoc, IsTemplateName ? diag::err_no_member_template
                                : diag::err_typename_nested_not_found)
         << II << DC << SS->getRange();
   else if (SS->isValid() && SS->getScopeRep()->containsErrors()) {
     SuggestedType =
         ActOnTypenameType(S, SourceLocation(), *SS, *II, IILoc).get();
   } else if (isDependentScopeSpecifier(*SS)) {
     unsigned DiagID = diag::err_typename_missing;
     if (getLangOpts().MSVCCompat && isMicrosoftMissingTypename(SS, S))
       DiagID = diag::ext_typename_missing;
 
     Diag(SS->getRange().getBegin(), DiagID)
       << SS->getScopeRep() << II->getName()
       << SourceRange(SS->getRange().getBegin(), IILoc)
       << FixItHint::CreateInsertion(SS->getRange().getBegin(), "typename ");
     SuggestedType = ActOnTypenameType(S, SourceLocation(),
                                       *SS, *II, IILoc).get();
   } else {
     assert(SS && SS->isInvalid() &&
            "Invalid scope specifier has already been diagnosed");
   }
 }
 
 /// Determine whether the given result set contains either a type name
 /// or
 static bool isResultTypeOrTemplate(LookupResult &R, const Token &NextToken) {
   bool CheckTemplate = R.getSema().getLangOpts().CPlusPlus &&
                        NextToken.is(tok::less);
 
   for (LookupResult::iterator I = R.begin(), IEnd = R.end(); I != IEnd; ++I) {
     if (isa<TypeDecl>(*I) || isa<ObjCInterfaceDecl>(*I))
       return true;
 
     if (CheckTemplate && isa<TemplateDecl>(*I))
       return true;
   }
 
   return false;
 }
 
 static bool isTagTypeWithMissingTag(Sema &SemaRef, LookupResult &Result,
                                     Scope *S, CXXScopeSpec &SS,
                                     IdentifierInfo *&Name,
                                     SourceLocation NameLoc) {
   LookupResult R(SemaRef, Name, NameLoc, Sema::LookupTagName);
   SemaRef.LookupParsedName(R, S, &SS);
   if (TagDecl *Tag = R.getAsSingle<TagDecl>()) {
     StringRef FixItTagName;
     switch (Tag->getTagKind()) {
       case TTK_Class:
         FixItTagName = "class ";
         break;
 
       case TTK_Enum:
         FixItTagName = "enum ";
         break;
 
       case TTK_Struct:
         FixItTagName = "struct ";
         break;
 
       case TTK_Interface:
         FixItTagName = "__interface ";
         break;
 
       case TTK_Union:
         FixItTagName = "union ";
         break;
     }
 
     StringRef TagName = FixItTagName.drop_back();
     SemaRef.Diag(NameLoc, diag::err_use_of_tag_name_without_tag)
       << Name << TagName << SemaRef.getLangOpts().CPlusPlus
       << FixItHint::CreateInsertion(NameLoc, FixItTagName);
 
     for (LookupResult::iterator I = Result.begin(), IEnd = Result.end();
          I != IEnd; ++I)
       SemaRef.Diag((*I)->getLocation(), diag::note_decl_hiding_tag_type)
         << Name << TagName;
 
     // Replace lookup results with just the tag decl.
     Result.clear(Sema::LookupTagName);
     SemaRef.LookupParsedName(Result, S, &SS);
     return true;
   }
 
   return false;
 }
 
 Sema::NameClassification Sema::ClassifyName(Scope *S, CXXScopeSpec &SS,
                                             IdentifierInfo *&Name,
                                             SourceLocation NameLoc,
                                             const Token &NextToken,
                                             CorrectionCandidateCallback *CCC) {
   DeclarationNameInfo NameInfo(Name, NameLoc);
   ObjCMethodDecl *CurMethod = getCurMethodDecl();
 
   assert(NextToken.isNot(tok::coloncolon) &&
          "parse nested name specifiers before calling ClassifyName");
   if (getLangOpts().CPlusPlus && SS.isSet() &&
       isCurrentClassName(*Name, S, &SS)) {
     // Per [class.qual]p2, this names the constructors of SS, not the
     // injected-class-name. We don't have a classification for that.
     // There's not much point caching this result, since the parser
     // will reject it later.
     return NameClassification::Unknown();
   }
 
   LookupResult Result(*this, Name, NameLoc, LookupOrdinaryName);
   LookupParsedName(Result, S, &SS, !CurMethod);
 
   if (SS.isInvalid())
     return NameClassification::Error();
 
   // For unqualified lookup in a class template in MSVC mode, look into
   // dependent base classes where the primary class template is known.
   if (Result.empty() && SS.isEmpty() && getLangOpts().MSVCCompat) {
     if (ParsedType TypeInBase =
             recoverFromTypeInKnownDependentBase(*this, *Name, NameLoc))
       return TypeInBase;
   }
 
   // Perform lookup for Objective-C instance variables (including automatically
   // synthesized instance variables), if we're in an Objective-C method.
   // FIXME: This lookup really, really needs to be folded in to the normal
   // unqualified lookup mechanism.
   if (SS.isEmpty() && CurMethod && !isResultTypeOrTemplate(Result, NextToken)) {
     DeclResult Ivar = LookupIvarInObjCMethod(Result, S, Name);
     if (Ivar.isInvalid())
       return NameClassification::Error();
     if (Ivar.isUsable())
       return NameClassification::NonType(cast<NamedDecl>(Ivar.get()));
 
     // We defer builtin creation until after ivar lookup inside ObjC methods.
     if (Result.empty())
       LookupBuiltin(Result);
   }
 
   bool SecondTry = false;
   bool IsFilteredTemplateName = false;
 
 Corrected:
   switch (Result.getResultKind()) {
   case LookupResult::NotFound:
     // If an unqualified-id is followed by a '(', then we have a function
     // call.
     if (SS.isEmpty() && NextToken.is(tok::l_paren)) {
       // In C++, this is an ADL-only call.
       // FIXME: Reference?
       if (getLangOpts().CPlusPlus)
         return NameClassification::UndeclaredNonType();
 
       // C90 6.3.2.2:
       //   If the expression that precedes the parenthesized argument list in a
       //   function call consists solely of an identifier, and if no
       //   declaration is visible for this identifier, the identifier is
       //   implicitly declared exactly as if, in the innermost block containing
       //   the function call, the declaration
       //
       //     extern int identifier ();
       //
       //   appeared.
       //
       // We also allow this in C99 as an extension. However, this is not
       // allowed in all language modes as functions without prototypes may not
       // be supported.
       if (getLangOpts().implicitFunctionsAllowed()) {
         if (NamedDecl *D = ImplicitlyDefineFunction(NameLoc, *Name, S))
           return NameClassification::NonType(D);
       }
     }
 
     if (getLangOpts().CPlusPlus20 && SS.isEmpty() && NextToken.is(tok::less)) {
       // In C++20 onwards, this could be an ADL-only call to a function
       // template, and we're required to assume that this is a template name.
       //
       // FIXME: Find a way to still do typo correction in this case.
       TemplateName Template =
           Context.getAssumedTemplateName(NameInfo.getName());
       return NameClassification::UndeclaredTemplate(Template);
     }
 
     // In C, we first see whether there is a tag type by the same name, in
     // which case it's likely that the user just forgot to write "enum",
     // "struct", or "union".
     if (!getLangOpts().CPlusPlus && !SecondTry &&
         isTagTypeWithMissingTag(*this, Result, S, SS, Name, NameLoc)) {
       break;
     }
 
     // Perform typo correction to determine if there is another name that is
     // close to this name.
     if (!SecondTry && CCC) {
       SecondTry = true;
       if (TypoCorrection Corrected =
               CorrectTypo(Result.getLookupNameInfo(), Result.getLookupKind(), S,
                           &SS, *CCC, CTK_ErrorRecovery)) {
         unsigned UnqualifiedDiag = diag::err_undeclared_var_use_suggest;
         unsigned QualifiedDiag = diag::err_no_member_suggest;
 
         NamedDecl *FirstDecl = Corrected.getFoundDecl();
         NamedDecl *UnderlyingFirstDecl = Corrected.getCorrectionDecl();
         if (getLangOpts().CPlusPlus && NextToken.is(tok::less) &&
             UnderlyingFirstDecl && isa<TemplateDecl>(UnderlyingFirstDecl)) {
           UnqualifiedDiag = diag::err_no_template_suggest;
           QualifiedDiag = diag::err_no_member_template_suggest;
         } else if (UnderlyingFirstDecl &&
                    (isa<TypeDecl>(UnderlyingFirstDecl) ||
                     isa<ObjCInterfaceDecl>(UnderlyingFirstDecl) ||
                     isa<ObjCCompatibleAliasDecl>(UnderlyingFirstDecl))) {
           UnqualifiedDiag = diag::err_unknown_typename_suggest;
           QualifiedDiag = diag::err_unknown_nested_typename_suggest;
         }
 
         if (SS.isEmpty()) {
           diagnoseTypo(Corrected, PDiag(UnqualifiedDiag) << Name);
         } else {// FIXME: is this even reachable? Test it.
           std::string CorrectedStr(Corrected.getAsString(getLangOpts()));
           bool DroppedSpecifier = Corrected.WillReplaceSpecifier() &&
                                   Name->getName().equals(CorrectedStr);
           diagnoseTypo(Corrected, PDiag(QualifiedDiag)
                                     << Name << computeDeclContext(SS, false)
                                     << DroppedSpecifier << SS.getRange());
         }
 
         // Update the name, so that the caller has the new name.
         Name = Corrected.getCorrectionAsIdentifierInfo();
 
         // Typo correction corrected to a keyword.
         if (Corrected.isKeyword())
           return Name;
 
         // Also update the LookupResult...
         // FIXME: This should probably go away at some point
         Result.clear();
         Result.setLookupName(Corrected.getCorrection());
         if (FirstDecl)
           Result.addDecl(FirstDecl);
 
         // If we found an Objective-C instance variable, let
         // LookupInObjCMethod build the appropriate expression to
         // reference the ivar.
         // FIXME: This is a gross hack.
         if (ObjCIvarDecl *Ivar = Result.getAsSingle<ObjCIvarDecl>()) {
           DeclResult R =
               LookupIvarInObjCMethod(Result, S, Ivar->getIdentifier());
           if (R.isInvalid())
             return NameClassification::Error();
           if (R.isUsable())
             return NameClassification::NonType(Ivar);
         }
 
         goto Corrected;
       }
     }
 
     // We failed to correct; just fall through and let the parser deal with it.
     Result.suppressDiagnostics();
     return NameClassification::Unknown();
 
   case LookupResult::NotFoundInCurrentInstantiation: {
     // We performed name lookup into the current instantiation, and there were
     // dependent bases, so we treat this result the same way as any other
     // dependent nested-name-specifier.
 
     // C++ [temp.res]p2:
     //   A name used in a template declaration or definition and that is
     //   dependent on a template-parameter is assumed not to name a type
     //   unless the applicable name lookup finds a type name or the name is
     //   qualified by the keyword typename.
     //
     // FIXME: If the next token is '<', we might want to ask the parser to
     // perform some heroics to see if we actually have a
     // template-argument-list, which would indicate a missing 'template'
     // keyword here.
     return NameClassification::DependentNonType();
   }
 
   case LookupResult::Found:
   case LookupResult::FoundOverloaded:
   case LookupResult::FoundUnresolvedValue:
     break;
 
   case LookupResult::Ambiguous:
     if (getLangOpts().CPlusPlus && NextToken.is(tok::less) &&
         hasAnyAcceptableTemplateNames(Result, /*AllowFunctionTemplates=*/true,
                                       /*AllowDependent=*/false)) {
       // C++ [temp.local]p3:
       //   A lookup that finds an injected-class-name (10.2) can result in an
       //   ambiguity in certain cases (for example, if it is found in more than
       //   one base class). If all of the injected-class-names that are found
       //   refer to specializations of the same class template, and if the name
       //   is followed by a template-argument-list, the reference refers to the
       //   class template itself and not a specialization thereof, and is not
       //   ambiguous.
       //
       // This filtering can make an ambiguous result into an unambiguous one,
       // so try again after filtering out template names.
       FilterAcceptableTemplateNames(Result);
       if (!Result.isAmbiguous()) {
         IsFilteredTemplateName = true;
         break;
       }
     }
 
     // Diagnose the ambiguity and return an error.
     return NameClassification::Error();
   }
 
   if (getLangOpts().CPlusPlus && NextToken.is(tok::less) &&
       (IsFilteredTemplateName ||
        hasAnyAcceptableTemplateNames(
            Result, /*AllowFunctionTemplates=*/true,
            /*AllowDependent=*/false,
            /*AllowNonTemplateFunctions*/ SS.isEmpty() &&
                getLangOpts().CPlusPlus20))) {
     // C++ [temp.names]p3:
     //   After name lookup (3.4) finds that a name is a template-name or that
     //   an operator-function-id or a literal- operator-id refers to a set of
     //   overloaded functions any member of which is a function template if
     //   this is followed by a <, the < is always taken as the delimiter of a
     //   template-argument-list and never as the less-than operator.
     // C++2a [temp.names]p2:
     //   A name is also considered to refer to a template if it is an
     //   unqualified-id followed by a < and name lookup finds either one
     //   or more functions or finds nothing.
     if (!IsFilteredTemplateName)
       FilterAcceptableTemplateNames(Result);
 
     bool IsFunctionTemplate;
     bool IsVarTemplate;
     TemplateName Template;
     if (Result.end() - Result.begin() > 1) {
       IsFunctionTemplate = true;
       Template = Context.getOverloadedTemplateName(Result.begin(),
                                                    Result.end());
     } else if (!Result.empty()) {
       auto *TD = cast<TemplateDecl>(getAsTemplateNameDecl(
           *Result.begin(), /*AllowFunctionTemplates=*/true,
           /*AllowDependent=*/false));
       IsFunctionTemplate = isa<FunctionTemplateDecl>(TD);
       IsVarTemplate = isa<VarTemplateDecl>(TD);
 
       UsingShadowDecl *FoundUsingShadow =
           dyn_cast<UsingShadowDecl>(*Result.begin());
       assert(!FoundUsingShadow ||
              TD == cast<TemplateDecl>(FoundUsingShadow->getTargetDecl()));
       Template =
           FoundUsingShadow ? TemplateName(FoundUsingShadow) : TemplateName(TD);
       if (SS.isNotEmpty())
         Template = Context.getQualifiedTemplateName(SS.getScopeRep(),
                                                     /*TemplateKeyword=*/false,
                                                     Template);
     } else {
       // All results were non-template functions. This is a function template
       // name.
       IsFunctionTemplate = true;
       Template = Context.getAssumedTemplateName(NameInfo.getName());
     }
 
     if (IsFunctionTemplate) {
       // Function templates always go through overload resolution, at which
       // point we'll perform the various checks (e.g., accessibility) we need
       // to based on which function we selected.
       Result.suppressDiagnostics();
 
       return NameClassification::FunctionTemplate(Template);
     }
 
     return IsVarTemplate ? NameClassification::VarTemplate(Template)
                          : NameClassification::TypeTemplate(Template);
   }
 
   auto BuildTypeFor = [&](TypeDecl *Type, NamedDecl *Found) {
     QualType T = Context.getTypeDeclType(Type);
     if (const auto *USD = dyn_cast<UsingShadowDecl>(Found))
       T = Context.getUsingType(USD, T);
     return buildNamedType(*this, &SS, T, NameLoc);
   };
 
   NamedDecl *FirstDecl = (*Result.begin())->getUnderlyingDecl();
   if (TypeDecl *Type = dyn_cast<TypeDecl>(FirstDecl)) {
     DiagnoseUseOfDecl(Type, NameLoc);
     MarkAnyDeclReferenced(Type->getLocation(), Type, /*OdrUse=*/false);
     return BuildTypeFor(Type, *Result.begin());
   }
 
   ObjCInterfaceDecl *Class = dyn_cast<ObjCInterfaceDecl>(FirstDecl);
   if (!Class) {
     // FIXME: It's unfortunate that we don't have a Type node for handling this.
     if (ObjCCompatibleAliasDecl *Alias =
             dyn_cast<ObjCCompatibleAliasDecl>(FirstDecl))
       Class = Alias->getClassInterface();
   }
 
   if (Class) {
     DiagnoseUseOfDecl(Class, NameLoc);
 
     if (NextToken.is(tok::period)) {
       // Interface. <something> is parsed as a property reference expression.
       // Just return "unknown" as a fall-through for now.
       Result.suppressDiagnostics();
       return NameClassification::Unknown();
     }
 
     QualType T = Context.getObjCInterfaceType(Class);
     return ParsedType::make(T);
   }
 
   if (isa<ConceptDecl>(FirstDecl))
     return NameClassification::Concept(
         TemplateName(cast<TemplateDecl>(FirstDecl)));
 
   if (auto *EmptyD = dyn_cast<UnresolvedUsingIfExistsDecl>(FirstDecl)) {
     (void)DiagnoseUseOfDecl(EmptyD, NameLoc);
     return NameClassification::Error();
   }
 
   // We can have a type template here if we're classifying a template argument.
   if (isa<TemplateDecl>(FirstDecl) && !isa<FunctionTemplateDecl>(FirstDecl) &&
       !isa<VarTemplateDecl>(FirstDecl))
     return NameClassification::TypeTemplate(
         TemplateName(cast<TemplateDecl>(FirstDecl)));
 
   // Check for a tag type hidden by a non-type decl in a few cases where it
   // seems likely a type is wanted instead of the non-type that was found.
   bool NextIsOp = NextToken.isOneOf(tok::amp, tok::star);
   if ((NextToken.is(tok::identifier) ||
        (NextIsOp &&
         FirstDecl->getUnderlyingDecl()->isFunctionOrFunctionTemplate())) &&
       isTagTypeWithMissingTag(*this, Result, S, SS, Name, NameLoc)) {
     TypeDecl *Type = Result.getAsSingle<TypeDecl>();
     DiagnoseUseOfDecl(Type, NameLoc);
     return BuildTypeFor(Type, *Result.begin());
   }
 
   // If we already know which single declaration is referenced, just annotate
   // that declaration directly. Defer resolving even non-overloaded class
   // member accesses, as we need to defer certain access checks until we know
   // the context.
   bool ADL = UseArgumentDependentLookup(SS, Result, NextToken.is(tok::l_paren));
   if (Result.isSingleResult() && !ADL &&
       (!FirstDecl->isCXXClassMember() || isa<EnumConstantDecl>(FirstDecl)))
     return NameClassification::NonType(Result.getRepresentativeDecl());
 
   // Otherwise, this is an overload set that we will need to resolve later.
   Result.suppressDiagnostics();
   return NameClassification::OverloadSet(UnresolvedLookupExpr::Create(
       Context, Result.getNamingClass(), SS.getWithLocInContext(Context),
       Result.getLookupNameInfo(), ADL, Result.isOverloadedResult(),
       Result.begin(), Result.end()));
 }
 
 ExprResult
 Sema::ActOnNameClassifiedAsUndeclaredNonType(IdentifierInfo *Name,
                                              SourceLocation NameLoc) {
   assert(getLangOpts().CPlusPlus && "ADL-only call in C?");
   CXXScopeSpec SS;
   LookupResult Result(*this, Name, NameLoc, LookupOrdinaryName);
   return BuildDeclarationNameExpr(SS, Result, /*ADL=*/true);
 }
 
 ExprResult
 Sema::ActOnNameClassifiedAsDependentNonType(const CXXScopeSpec &SS,
                                             IdentifierInfo *Name,
                                             SourceLocation NameLoc,
                                             bool IsAddressOfOperand) {
   DeclarationNameInfo NameInfo(Name, NameLoc);
   return ActOnDependentIdExpression(SS, /*TemplateKWLoc=*/SourceLocation(),
                                     NameInfo, IsAddressOfOperand,
                                     /*TemplateArgs=*/nullptr);
 }
 
 ExprResult Sema::ActOnNameClassifiedAsNonType(Scope *S, const CXXScopeSpec &SS,
                                               NamedDecl *Found,
                                               SourceLocation NameLoc,
                                               const Token &NextToken) {
   if (getCurMethodDecl() && SS.isEmpty())
     if (auto *Ivar = dyn_cast<ObjCIvarDecl>(Found->getUnderlyingDecl()))
       return BuildIvarRefExpr(S, NameLoc, Ivar);
 
   // Reconstruct the lookup result.
   LookupResult Result(*this, Found->getDeclName(), NameLoc, LookupOrdinaryName);
   Result.addDecl(Found);
   Result.resolveKind();
 
   bool ADL = UseArgumentDependentLookup(SS, Result, NextToken.is(tok::l_paren));
   return BuildDeclarationNameExpr(SS, Result, ADL, /*AcceptInvalidDecl=*/true);
 }
 
 ExprResult Sema::ActOnNameClassifiedAsOverloadSet(Scope *S, Expr *E) {
   // For an implicit class member access, transform the result into a member
   // access expression if necessary.
   auto *ULE = cast<UnresolvedLookupExpr>(E);
   if ((*ULE->decls_begin())->isCXXClassMember()) {
     CXXScopeSpec SS;
     SS.Adopt(ULE->getQualifierLoc());
 
     // Reconstruct the lookup result.
     LookupResult Result(*this, ULE->getName(), ULE->getNameLoc(),
                         LookupOrdinaryName);
     Result.setNamingClass(ULE->getNamingClass());
     for (auto I = ULE->decls_begin(), E = ULE->decls_end(); I != E; ++I)
       Result.addDecl(*I, I.getAccess());
     Result.resolveKind();
     return BuildPossibleImplicitMemberExpr(SS, SourceLocation(), Result,
                                            nullptr, S);
   }
 
   // Otherwise, this is already in the form we needed, and no further checks
   // are necessary.
   return ULE;
 }
 
 Sema::TemplateNameKindForDiagnostics
 Sema::getTemplateNameKindForDiagnostics(TemplateName Name) {
   auto *TD = Name.getAsTemplateDecl();
   if (!TD)
     return TemplateNameKindForDiagnostics::DependentTemplate;
   if (isa<ClassTemplateDecl>(TD))
     return TemplateNameKindForDiagnostics::ClassTemplate;
   if (isa<FunctionTemplateDecl>(TD))
     return TemplateNameKindForDiagnostics::FunctionTemplate;
   if (isa<VarTemplateDecl>(TD))
     return TemplateNameKindForDiagnostics::VarTemplate;
   if (isa<TypeAliasTemplateDecl>(TD))
     return TemplateNameKindForDiagnostics::AliasTemplate;
   if (isa<TemplateTemplateParmDecl>(TD))
     return TemplateNameKindForDiagnostics::TemplateTemplateParam;
   if (isa<ConceptDecl>(TD))
     return TemplateNameKindForDiagnostics::Concept;
   return TemplateNameKindForDiagnostics::DependentTemplate;
 }
 
 void Sema::PushDeclContext(Scope *S, DeclContext *DC) {
   assert(DC->getLexicalParent() == CurContext &&
       "The next DeclContext should be lexically contained in the current one.");
   CurContext = DC;
   S->setEntity(DC);
 }
 
 void Sema::PopDeclContext() {
   assert(CurContext && "DeclContext imbalance!");
 
   CurContext = CurContext->getLexicalParent();
   assert(CurContext && "Popped translation unit!");
 }
 
 Sema::SkippedDefinitionContext Sema::ActOnTagStartSkippedDefinition(Scope *S,
                                                                     Decl *D) {
   // Unlike PushDeclContext, the context to which we return is not necessarily
   // the containing DC of TD, because the new context will be some pre-existing
   // TagDecl definition instead of a fresh one.
   auto Result = static_cast<SkippedDefinitionContext>(CurContext);
   CurContext = cast<TagDecl>(D)->getDefinition();
   assert(CurContext && "skipping definition of undefined tag");
   // Start lookups from the parent of the current context; we don't want to look
   // into the pre-existing complete definition.
   S->setEntity(CurContext->getLookupParent());
   return Result;
 }
 
 void Sema::ActOnTagFinishSkippedDefinition(SkippedDefinitionContext Context) {
   CurContext = static_cast<decltype(CurContext)>(Context);
 }
 
 /// EnterDeclaratorContext - Used when we must lookup names in the context
 /// of a declarator's nested name specifier.
 ///
 void Sema::EnterDeclaratorContext(Scope *S, DeclContext *DC) {
   // C++0x [basic.lookup.unqual]p13:
   //   A name used in the definition of a static data member of class
   //   X (after the qualified-id of the static member) is looked up as
   //   if the name was used in a member function of X.
   // C++0x [basic.lookup.unqual]p14:
   //   If a variable member of a namespace is defined outside of the
   //   scope of its namespace then any name used in the definition of
   //   the variable member (after the declarator-id) is looked up as
   //   if the definition of the variable member occurred in its
   //   namespace.
   // Both of these imply that we should push a scope whose context
   // is the semantic context of the declaration.  We can't use
   // PushDeclContext here because that context is not necessarily
   // lexically contained in the current context.  Fortunately,
   // the containing scope should have the appropriate information.
 
   assert(!S->getEntity() && "scope already has entity");
 
 #ifndef NDEBUG
   Scope *Ancestor = S->getParent();
   while (!Ancestor->getEntity()) Ancestor = Ancestor->getParent();
   assert(Ancestor->getEntity() == CurContext && "ancestor context mismatch");
 #endif
 
   CurContext = DC;
   S->setEntity(DC);
 
   if (S->getParent()->isTemplateParamScope()) {
     // Also set the corresponding entities for all immediately-enclosing
     // template parameter scopes.
     EnterTemplatedContext(S->getParent(), DC);
   }
 }
 
 void Sema::ExitDeclaratorContext(Scope *S) {
   assert(S->getEntity() == CurContext && "Context imbalance!");
 
   // Switch back to the lexical context.  The safety of this is
   // enforced by an assert in EnterDeclaratorContext.
   Scope *Ancestor = S->getParent();
   while (!Ancestor->getEntity()) Ancestor = Ancestor->getParent();
   CurContext = Ancestor->getEntity();
 
   // We don't need to do anything with the scope, which is going to
   // disappear.
 }
 
 void Sema::EnterTemplatedContext(Scope *S, DeclContext *DC) {
   assert(S->isTemplateParamScope() &&
          "expected to be initializing a template parameter scope");
 
   // C++20 [temp.local]p7:
   //   In the definition of a member of a class template that appears outside
   //   of the class template definition, the name of a member of the class
   //   template hides the name of a template-parameter of any enclosing class
   //   templates (but not a template-parameter of the member if the member is a
   //   class or function template).
   // C++20 [temp.local]p9:
   //   In the definition of a class template or in the definition of a member
   //   of such a template that appears outside of the template definition, for
   //   each non-dependent base class (13.8.2.1), if the name of the base class
   //   or the name of a member of the base class is the same as the name of a
   //   template-parameter, the base class name or member name hides the
   //   template-parameter name (6.4.10).
   //
   // This means that a template parameter scope should be searched immediately
   // after searching the DeclContext for which it is a template parameter
   // scope. For example, for
   //   template<typename T> template<typename U> template<typename V>
   //     void N::A<T>::B<U>::f(...)
   // we search V then B<U> (and base classes) then U then A<T> (and base
   // classes) then T then N then ::.
   unsigned ScopeDepth = getTemplateDepth(S);
   for (; S && S->isTemplateParamScope(); S = S->getParent(), --ScopeDepth) {
     DeclContext *SearchDCAfterScope = DC;
     for (; DC; DC = DC->getLookupParent()) {
       if (const TemplateParameterList *TPL =
               cast<Decl>(DC)->getDescribedTemplateParams()) {
         unsigned DCDepth = TPL->getDepth() + 1;
         if (DCDepth > ScopeDepth)
           continue;
         if (ScopeDepth == DCDepth)
           SearchDCAfterScope = DC = DC->getLookupParent();
         break;
       }
     }
     S->setLookupEntity(SearchDCAfterScope);
   }
 }
 
 void Sema::ActOnReenterFunctionContext(Scope* S, Decl *D) {
   // We assume that the caller has already called
   // ActOnReenterTemplateScope so getTemplatedDecl() works.
   FunctionDecl *FD = D->getAsFunction();
   if (!FD)
     return;
 
   // Same implementation as PushDeclContext, but enters the context
   // from the lexical parent, rather than the top-level class.
   assert(CurContext == FD->getLexicalParent() &&
     "The next DeclContext should be lexically contained in the current one.");
   CurContext = FD;
   S->setEntity(CurContext);
 
   for (unsigned P = 0, NumParams = FD->getNumParams(); P < NumParams; ++P) {
     ParmVarDecl *Param = FD->getParamDecl(P);
     // If the parameter has an identifier, then add it to the scope
     if (Param->getIdentifier()) {
       S->AddDecl(Param);
       IdResolver.AddDecl(Param);
     }
   }
 }
 
 void Sema::ActOnExitFunctionContext() {
   // Same implementation as PopDeclContext, but returns to the lexical parent,
   // rather than the top-level class.
   assert(CurContext && "DeclContext imbalance!");
   CurContext = CurContext->getLexicalParent();
   assert(CurContext && "Popped translation unit!");
 }
 
 /// Determine whether overloading is allowed for a new function
 /// declaration considering prior declarations of the same name.
 ///
 /// This routine determines whether overloading is possible, not
 /// whether a new declaration actually overloads a previous one.
 /// It will return true in C++ (where overloads are alway permitted)
 /// or, as a C extension, when either the new declaration or a
 /// previous one is declared with the 'overloadable' attribute.
 static bool AllowOverloadingOfFunction(const LookupResult &Previous,
                                        ASTContext &Context,
                                        const FunctionDecl *New) {
   if (Context.getLangOpts().CPlusPlus || New->hasAttr<OverloadableAttr>())
     return true;
 
   // Multiversion function declarations are not overloads in the
   // usual sense of that term, but lookup will report that an
   // overload set was found if more than one multiversion function
   // declaration is present for the same name. It is therefore
   // inadequate to assume that some prior declaration(s) had
   // the overloadable attribute; checking is required. Since one
   // declaration is permitted to omit the attribute, it is necessary
   // to check at least two; hence the 'any_of' check below. Note that
   // the overloadable attribute is implicitly added to declarations
   // that were required to have it but did not.
   if (Previous.getResultKind() == LookupResult::FoundOverloaded) {
     return llvm::any_of(Previous, [](const NamedDecl *ND) {
       return ND->hasAttr<OverloadableAttr>();
     });
   } else if (Previous.getResultKind() == LookupResult::Found)
     return Previous.getFoundDecl()->hasAttr<OverloadableAttr>();
 
   return false;
 }
 
 /// Add this decl to the scope shadowed decl chains.
 void Sema::PushOnScopeChains(NamedDecl *D, Scope *S, bool AddToContext) {
   // Move up the scope chain until we find the nearest enclosing
   // non-transparent context. The declaration will be introduced into this
   // scope.
   while (S->getEntity() && S->getEntity()->isTransparentContext())
     S = S->getParent();
 
   // Add scoped declarations into their context, so that they can be
   // found later. Declarations without a context won't be inserted
   // into any context.
   if (AddToContext)
     CurContext->addDecl(D);
 
   // Out-of-line definitions shouldn't be pushed into scope in C++, unless they
   // are function-local declarations.
   if (getLangOpts().CPlusPlus && D->isOutOfLine() && !S->getFnParent())
     return;
 
   // Template instantiations should also not be pushed into scope.
   if (isa<FunctionDecl>(D) &&
       cast<FunctionDecl>(D)->isFunctionTemplateSpecialization())
     return;
 
   // If this replaces anything in the current scope,
   IdentifierResolver::iterator I = IdResolver.begin(D->getDeclName()),
                                IEnd = IdResolver.end();
   for (; I != IEnd; ++I) {
     if (S->isDeclScope(*I) && D->declarationReplaces(*I)) {
       S->RemoveDecl(*I);
       IdResolver.RemoveDecl(*I);
 
       // Should only need to replace one decl.
       break;
     }
   }
 
   S->AddDecl(D);
 
   if (isa<LabelDecl>(D) && !cast<LabelDecl>(D)->isGnuLocal()) {
     // Implicitly-generated labels may end up getting generated in an order that
     // isn't strictly lexical, which breaks name lookup. Be careful to insert
     // the label at the appropriate place in the identifier chain.
     for (I = IdResolver.begin(D->getDeclName()); I != IEnd; ++I) {
       DeclContext *IDC = (*I)->getLexicalDeclContext()->getRedeclContext();
       if (IDC == CurContext) {
         if (!S->isDeclScope(*I))
           continue;
       } else if (IDC->Encloses(CurContext))
         break;
     }
 
     IdResolver.InsertDeclAfter(I, D);
   } else {
     IdResolver.AddDecl(D);
   }
   warnOnReservedIdentifier(D);
 }
 
 bool Sema::isDeclInScope(NamedDecl *D, DeclContext *Ctx, Scope *S,
                          bool AllowInlineNamespace) const {
   return IdResolver.isDeclInScope(D, Ctx, S, AllowInlineNamespace);
 }
 
 Scope *Sema::getScopeForDeclContext(Scope *S, DeclContext *DC) {
   DeclContext *TargetDC = DC->getPrimaryContext();
   do {
     if (DeclContext *ScopeDC = S->getEntity())
       if (ScopeDC->getPrimaryContext() == TargetDC)
         return S;
   } while ((S = S->getParent()));
 
   return nullptr;
 }
 
 static bool isOutOfScopePreviousDeclaration(NamedDecl *,
                                             DeclContext*,
                                             ASTContext&);
 
 /// Filters out lookup results that don't fall within the given scope
 /// as determined by isDeclInScope.
 void Sema::FilterLookupForScope(LookupResult &R, DeclContext *Ctx, Scope *S,
                                 bool ConsiderLinkage,
                                 bool AllowInlineNamespace) {
   LookupResult::Filter F = R.makeFilter();
   while (F.hasNext()) {
     NamedDecl *D = F.next();
 
     if (isDeclInScope(D, Ctx, S, AllowInlineNamespace))
       continue;
 
     if (ConsiderLinkage && isOutOfScopePreviousDeclaration(D, Ctx, Context))
       continue;
 
     F.erase();
   }
 
   F.done();
 }
 
 /// We've determined that \p New is a redeclaration of \p Old. Check that they
 /// have compatible owning modules.
 bool Sema::CheckRedeclarationModuleOwnership(NamedDecl *New, NamedDecl *Old) {
   // [module.interface]p7:
   // A declaration is attached to a module as follows:
   // - If the declaration is a non-dependent friend declaration that nominates a
   // function with a declarator-id that is a qualified-id or template-id or that
   // nominates a class other than with an elaborated-type-specifier with neither
   // a nested-name-specifier nor a simple-template-id, it is attached to the
   // module to which the friend is attached ([basic.link]).
   if (New->getFriendObjectKind() &&
       Old->getOwningModuleForLinkage() != New->getOwningModuleForLinkage()) {
     New->setLocalOwningModule(Old->getOwningModule());
     makeMergedDefinitionVisible(New);
     return false;
   }
 
   Module *NewM = New->getOwningModule();
   Module *OldM = Old->getOwningModule();
 
   if (NewM && NewM->isPrivateModule())
     NewM = NewM->Parent;
   if (OldM && OldM->isPrivateModule())
     OldM = OldM->Parent;
 
   if (NewM == OldM)
     return false;
 
   if (NewM && OldM) {
     // A module implementation unit has visibility of the decls in its
     // implicitly imported interface.
     if (NewM->isModuleImplementation() && OldM == ThePrimaryInterface)
       return false;
 
     // Partitions are part of the module, but a partition could import another
     // module, so verify that the PMIs agree.
     if ((NewM->isModulePartition() || OldM->isModulePartition()) &&
         NewM->getPrimaryModuleInterfaceName() ==
             OldM->getPrimaryModuleInterfaceName())
       return false;
   }
 
   bool NewIsModuleInterface = NewM && NewM->isModulePurview();
   bool OldIsModuleInterface = OldM && OldM->isModulePurview();
   if (NewIsModuleInterface || OldIsModuleInterface) {
     // C++ Modules TS [basic.def.odr] 6.2/6.7 [sic]:
     //   if a declaration of D [...] appears in the purview of a module, all
     //   other such declarations shall appear in the purview of the same module
     Diag(New->getLocation(), diag::err_mismatched_owning_module)
       << New
       << NewIsModuleInterface
       << (NewIsModuleInterface ? NewM->getFullModuleName() : "")
       << OldIsModuleInterface
       << (OldIsModuleInterface ? OldM->getFullModuleName() : "");
     Diag(Old->getLocation(), diag::note_previous_declaration);
     New->setInvalidDecl();
     return true;
   }
 
   return false;
 }
 
 // [module.interface]p6:
 // A redeclaration of an entity X is implicitly exported if X was introduced by
 // an exported declaration; otherwise it shall not be exported.
 bool Sema::CheckRedeclarationExported(NamedDecl *New, NamedDecl *Old) {
   // [module.interface]p1:
   // An export-declaration shall inhabit a namespace scope.
   //
   // So it is meaningless to talk about redeclaration which is not at namespace
   // scope.
   if (!New->getLexicalDeclContext()
            ->getNonTransparentContext()
            ->isFileContext() ||
       !Old->getLexicalDeclContext()
            ->getNonTransparentContext()
            ->isFileContext())
     return false;
 
   bool IsNewExported = New->isInExportDeclContext();
   bool IsOldExported = Old->isInExportDeclContext();
 
   // It should be irrevelant if both of them are not exported.
   if (!IsNewExported && !IsOldExported)
     return false;
 
   if (IsOldExported)
     return false;
 
   assert(IsNewExported);
 
   auto Lk = Old->getFormalLinkage();
   int S = 0;
   if (Lk == Linkage::InternalLinkage)
     S = 1;
   else if (Lk == Linkage::ModuleLinkage)
     S = 2;
   Diag(New->getLocation(), diag::err_redeclaration_non_exported) << New << S;
   Diag(Old->getLocation(), diag::note_previous_declaration);
   return true;
 }
 
 // A wrapper function for checking the semantic restrictions of
 // a redeclaration within a module.
 bool Sema::CheckRedeclarationInModule(NamedDecl *New, NamedDecl *Old) {
   if (CheckRedeclarationModuleOwnership(New, Old))
     return true;
 
   if (CheckRedeclarationExported(New, Old))
     return true;
 
   return false;
 }
 
 // Check the redefinition in C++20 Modules.
 //
 // [basic.def.odr]p14:
 // For any definable item D with definitions in multiple translation units,
 // - if D is a non-inline non-templated function or variable, or
 // - if the definitions in different translation units do not satisfy the
 // following requirements,
 //   the program is ill-formed; a diagnostic is required only if the definable
 //   item is attached to a named module and a prior definition is reachable at
 //   the point where a later definition occurs.
 // - Each such definition shall not be attached to a named module
 // ([module.unit]).
 // - Each such definition shall consist of the same sequence of tokens, ...
 // ...
 //
 // Return true if the redefinition is not allowed. Return false otherwise.
 bool Sema::IsRedefinitionInModule(const NamedDecl *New,
                                      const NamedDecl *Old) const {
   assert(getASTContext().isSameEntity(New, Old) &&
          "New and Old are not the same definition, we should diagnostic it "
          "immediately instead of checking it.");
   assert(const_cast<Sema *>(this)->isReachable(New) &&
          const_cast<Sema *>(this)->isReachable(Old) &&
          "We shouldn't see unreachable definitions here.");
 
   Module *NewM = New->getOwningModule();
   Module *OldM = Old->getOwningModule();
 
   // We only checks for named modules here. The header like modules is skipped.
   // FIXME: This is not right if we import the header like modules in the module
   // purview.
   //
   // For example, assuming "header.h" provides definition for `D`.
   // ```C++
   // //--- M.cppm
   // export module M;
   // import "header.h"; // or #include "header.h" but import it by clang modules
   // actually.
   //
   // //--- Use.cpp
   // import M;
   // import "header.h"; // or uses clang modules.
   // ```
   //
   // In this case, `D` has multiple definitions in multiple TU (M.cppm and
   // Use.cpp) and `D` is attached to a named module `M`. The compiler should
   // reject it. But the current implementation couldn't detect the case since we
   // don't record the information about the importee modules.
   //
   // But this might not be painful in practice. Since the design of C++20 Named
   // Modules suggests us to use headers in global module fragment instead of
   // module purview.
   if (NewM && NewM->isHeaderLikeModule())
     NewM = nullptr;
   if (OldM && OldM->isHeaderLikeModule())
     OldM = nullptr;
 
   if (!NewM && !OldM)
     return true;
 
   // [basic.def.odr]p14.3
   // Each such definition shall not be attached to a named module
   // ([module.unit]).
   if ((NewM && NewM->isModulePurview()) || (OldM && OldM->isModulePurview()))
     return true;
 
   // Then New and Old lives in the same TU if their share one same module unit.
   if (NewM)
     NewM = NewM->getTopLevelModule();
   if (OldM)
     OldM = OldM->getTopLevelModule();
   return OldM == NewM;
 }
 
 static bool isUsingDeclNotAtClassScope(NamedDecl *D) {
   if (D->getDeclContext()->isFileContext())
     return false;
 
   return isa<UsingShadowDecl>(D) ||
          isa<UnresolvedUsingTypenameDecl>(D) ||
          isa<UnresolvedUsingValueDecl>(D);
 }
 
 /// Removes using shadow declarations not at class scope from the lookup
 /// results.
 static void RemoveUsingDecls(LookupResult &R) {
   LookupResult::Filter F = R.makeFilter();
   while (F.hasNext())
     if (isUsingDeclNotAtClassScope(F.next()))
       F.erase();
 
   F.done();
 }
 
 /// Check for this common pattern:
 /// @code
 /// class S {
 ///   S(const S&); // DO NOT IMPLEMENT
 ///   void operator=(const S&); // DO NOT IMPLEMENT
 /// };
 /// @endcode
 static bool IsDisallowedCopyOrAssign(const CXXMethodDecl *D) {
   // FIXME: Should check for private access too but access is set after we get
   // the decl here.
   if (D->doesThisDeclarationHaveABody())
     return false;
 
   if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(D))
     return CD->isCopyConstructor();
   return D->isCopyAssignmentOperator();
 }
 
 // We need this to handle
 //
 // typedef struct {
 //   void *foo() { return 0; }
 // } A;
 //
 // When we see foo we don't know if after the typedef we will get 'A' or '*A'
 // for example. If 'A', foo will have external linkage. If we have '*A',
 // foo will have no linkage. Since we can't know until we get to the end
 // of the typedef, this function finds out if D might have non-external linkage.
 // Callers should verify at the end of the TU if it D has external linkage or
 // not.
 bool Sema::mightHaveNonExternalLinkage(const DeclaratorDecl *D) {
   const DeclContext *DC = D->getDeclContext();
   while (!DC->isTranslationUnit()) {
     if (const RecordDecl *RD = dyn_cast<RecordDecl>(DC)){
       if (!RD->hasNameForLinkage())
         return true;
     }
     DC = DC->getParent();
   }
 
   return !D->isExternallyVisible();
 }
 
 // FIXME: This needs to be refactored; some other isInMainFile users want
 // these semantics.
 static bool isMainFileLoc(const Sema &S, SourceLocation Loc) {
   if (S.TUKind != TU_Complete || S.getLangOpts().IsHeaderFile)
     return false;
   return S.SourceMgr.isInMainFile(Loc);
 }
 
 bool Sema::ShouldWarnIfUnusedFileScopedDecl(const DeclaratorDecl *D) const {
   assert(D);
 
   if (D->isInvalidDecl() || D->isUsed() || D->hasAttr<UnusedAttr>())
     return false;
 
   // Ignore all entities declared within templates, and out-of-line definitions
   // of members of class templates.
   if (D->getDeclContext()->isDependentContext() ||
       D->getLexicalDeclContext()->isDependentContext())
     return false;
 
   if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
     if (FD->getTemplateSpecializationKind() == TSK_ImplicitInstantiation)
       return false;
     // A non-out-of-line declaration of a member specialization was implicitly
     // instantiated; it's the out-of-line declaration that we're interested in.
     if (FD->getTemplateSpecializationKind() == TSK_ExplicitSpecialization &&
         FD->getMemberSpecializationInfo() && !FD->isOutOfLine())
       return false;
 
     if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD)) {
       if (MD->isVirtual() || IsDisallowedCopyOrAssign(MD))
         return false;
     } else {
       // 'static inline' functions are defined in headers; don't warn.
       if (FD->isInlined() && !isMainFileLoc(*this, FD->getLocation()))
         return false;
     }
 
     if (FD->doesThisDeclarationHaveABody() &&
         Context.DeclMustBeEmitted(FD))
       return false;
   } else if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
     // Constants and utility variables are defined in headers with internal
     // linkage; don't warn.  (Unlike functions, there isn't a convenient marker
     // like "inline".)
     if (!isMainFileLoc(*this, VD->getLocation()))
       return false;
 
     if (Context.DeclMustBeEmitted(VD))
       return false;
 
     if (VD->isStaticDataMember() &&
         VD->getTemplateSpecializationKind() == TSK_ImplicitInstantiation)
       return false;
     if (VD->isStaticDataMember() &&
         VD->getTemplateSpecializationKind() == TSK_ExplicitSpecialization &&
         VD->getMemberSpecializationInfo() && !VD->isOutOfLine())
       return false;
 
     if (VD->isInline() && !isMainFileLoc(*this, VD->getLocation()))
       return false;
   } else {
     return false;
   }
 
   // Only warn for unused decls internal to the translation unit.
   // FIXME: This seems like a bogus check; it suppresses -Wunused-function
   // for inline functions defined in the main source file, for instance.
   return mightHaveNonExternalLinkage(D);
 }
 
 void Sema::MarkUnusedFileScopedDecl(const DeclaratorDecl *D) {
   if (!D)
     return;
 
   if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
     const FunctionDecl *First = FD->getFirstDecl();
     if (FD != First && ShouldWarnIfUnusedFileScopedDecl(First))
       return; // First should already be in the vector.
   }
 
   if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
     const VarDecl *First = VD->getFirstDecl();
     if (VD != First && ShouldWarnIfUnusedFileScopedDecl(First))
       return; // First should already be in the vector.
   }
 
   if (ShouldWarnIfUnusedFileScopedDecl(D))
     UnusedFileScopedDecls.push_back(D);
 }
 
 static bool ShouldDiagnoseUnusedDecl(const NamedDecl *D) {
   if (D->isInvalidDecl())
     return false;
 
   if (auto *DD = dyn_cast<DecompositionDecl>(D)) {
     // For a decomposition declaration, warn if none of the bindings are
     // referenced, instead of if the variable itself is referenced (which
     // it is, by the bindings' expressions).
     for (auto *BD : DD->bindings())
       if (BD->isReferenced())
         return false;
   } else if (!D->getDeclName()) {
     return false;
   } else if (D->isReferenced() || D->isUsed()) {
     return false;
   }
 
   if (D->hasAttr<UnusedAttr>() || D->hasAttr<ObjCPreciseLifetimeAttr>() ||
       D->hasAttr<CleanupAttr>())
     return false;
 
   if (isa<LabelDecl>(D))
     return true;
 
   // Except for labels, we only care about unused decls that are local to
   // functions.
   bool WithinFunction = D->getDeclContext()->isFunctionOrMethod();
   if (const auto *R = dyn_cast<CXXRecordDecl>(D->getDeclContext()))
     // For dependent types, the diagnostic is deferred.
     WithinFunction =
         WithinFunction || (R->isLocalClass() && !R->isDependentType());
   if (!WithinFunction)
     return false;
 
   if (isa<TypedefNameDecl>(D))
     return true;
 
   // White-list anything that isn't a local variable.
   if (!isa<VarDecl>(D) || isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D))
     return false;
 
   // Types of valid local variables should be complete, so this should succeed.
   if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
 
     const Expr *Init = VD->getInit();
     if (const auto *Cleanups = dyn_cast_or_null<ExprWithCleanups>(Init))
       Init = Cleanups->getSubExpr();
 
     const auto *Ty = VD->getType().getTypePtr();
 
     // Only look at the outermost level of typedef.
     if (const TypedefType *TT = Ty->getAs<TypedefType>()) {
       // Allow anything marked with __attribute__((unused)).
       if (TT->getDecl()->hasAttr<UnusedAttr>())
         return false;
     }
 
     // Warn for reference variables whose initializtion performs lifetime
     // extension.
     if (const auto *MTE = dyn_cast_or_null<MaterializeTemporaryExpr>(Init)) {
       if (MTE->getExtendingDecl()) {
         Ty = VD->getType().getNonReferenceType().getTypePtr();
         Init = MTE->getSubExpr()->IgnoreImplicitAsWritten();
       }
     }
 
     // If we failed to complete the type for some reason, or if the type is
     // dependent, don't diagnose the variable.
     if (Ty->isIncompleteType() || Ty->isDependentType())
       return false;
 
     // Look at the element type to ensure that the warning behaviour is
     // consistent for both scalars and arrays.
     Ty = Ty->getBaseElementTypeUnsafe();
 
     if (const TagType *TT = Ty->getAs<TagType>()) {
       const TagDecl *Tag = TT->getDecl();
       if (Tag->hasAttr<UnusedAttr>())
         return false;
 
       if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(Tag)) {
         if (!RD->hasTrivialDestructor() && !RD->hasAttr<WarnUnusedAttr>())
           return false;
 
         if (Init) {
           const CXXConstructExpr *Construct =
             dyn_cast<CXXConstructExpr>(Init);
           if (Construct && !Construct->isElidable()) {
             CXXConstructorDecl *CD = Construct->getConstructor();
             if (!CD->isTrivial() && !RD->hasAttr<WarnUnusedAttr>() &&
                 (VD->getInit()->isValueDependent() || !VD->evaluateValue()))
               return false;
           }
 
           // Suppress the warning if we don't know how this is constructed, and
           // it could possibly be non-trivial constructor.
           if (Init->isTypeDependent()) {
             for (const CXXConstructorDecl *Ctor : RD->ctors())
               if (!Ctor->isTrivial())
                 return false;
           }
 
           // Suppress the warning if the constructor is unresolved because
           // its arguments are dependent.
           if (isa<CXXUnresolvedConstructExpr>(Init))
             return false;
         }
       }
     }
 
     // TODO: __attribute__((unused)) templates?
   }
 
   return true;
 }
 
 static void GenerateFixForUnusedDecl(const NamedDecl *D, ASTContext &Ctx,
                                      FixItHint &Hint) {
   if (isa<LabelDecl>(D)) {
     SourceLocation AfterColon = Lexer::findLocationAfterToken(
         D->getEndLoc(), tok::colon, Ctx.getSourceManager(), Ctx.getLangOpts(),
         /*SkipTrailingWhitespaceAndNewline=*/false);
     if (AfterColon.isInvalid())
       return;
     Hint = FixItHint::CreateRemoval(
         CharSourceRange::getCharRange(D->getBeginLoc(), AfterColon));
   }
 }
 
 void Sema::DiagnoseUnusedNestedTypedefs(const RecordDecl *D) {
   DiagnoseUnusedNestedTypedefs(
       D, [this](SourceLocation Loc, PartialDiagnostic PD) { Diag(Loc, PD); });
 }
 
 void Sema::DiagnoseUnusedNestedTypedefs(const RecordDecl *D,
                                         DiagReceiverTy DiagReceiver) {
   if (D->getTypeForDecl()->isDependentType())
     return;
 
   for (auto *TmpD : D->decls()) {
     if (const auto *T = dyn_cast<TypedefNameDecl>(TmpD))
       DiagnoseUnusedDecl(T, DiagReceiver);
     else if(const auto *R = dyn_cast<RecordDecl>(TmpD))
       DiagnoseUnusedNestedTypedefs(R, DiagReceiver);
   }
 }
 
 void Sema::DiagnoseUnusedDecl(const NamedDecl *D) {
   DiagnoseUnusedDecl(
       D, [this](SourceLocation Loc, PartialDiagnostic PD) { Diag(Loc, PD); });
 }
 
 /// DiagnoseUnusedDecl - Emit warnings about declarations that are not used
 /// unless they are marked attr(unused).
 void Sema::DiagnoseUnusedDecl(const NamedDecl *D, DiagReceiverTy DiagReceiver) {
   if (!ShouldDiagnoseUnusedDecl(D))
     return;
 
   if (auto *TD = dyn_cast<TypedefNameDecl>(D)) {
     // typedefs can be referenced later on, so the diagnostics are emitted
     // at end-of-translation-unit.
     UnusedLocalTypedefNameCandidates.insert(TD);
     return;
   }
 
   FixItHint Hint;
   GenerateFixForUnusedDecl(D, Context, Hint);
 
   unsigned DiagID;
   if (isa<VarDecl>(D) && cast<VarDecl>(D)->isExceptionVariable())
     DiagID = diag::warn_unused_exception_param;
   else if (isa<LabelDecl>(D))
     DiagID = diag::warn_unused_label;
   else
     DiagID = diag::warn_unused_variable;
 
   SourceLocation DiagLoc = D->getLocation();
   DiagReceiver(DiagLoc, PDiag(DiagID) << D << Hint << SourceRange(DiagLoc));
 }
 
 void Sema::DiagnoseUnusedButSetDecl(const VarDecl *VD,
                                     DiagReceiverTy DiagReceiver) {
   // If it's not referenced, it can't be set. If it has the Cleanup attribute,
   // it's not really unused.
   if (!VD->isReferenced() || !VD->getDeclName() || VD->hasAttr<UnusedAttr>() ||
       VD->hasAttr<CleanupAttr>())
     return;
 
   const auto *Ty = VD->getType().getTypePtr()->getBaseElementTypeUnsafe();
 
   if (Ty->isReferenceType() || Ty->isDependentType())
     return;
 
   if (const TagType *TT = Ty->getAs<TagType>()) {
     const TagDecl *Tag = TT->getDecl();
     if (Tag->hasAttr<UnusedAttr>())
       return;
     // In C++, don't warn for record types that don't have WarnUnusedAttr, to
     // mimic gcc's behavior.
     if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(Tag)) {
       if (!RD->hasAttr<WarnUnusedAttr>())
         return;
     }
   }
 
   // Don't warn about __block Objective-C pointer variables, as they might
   // be assigned in the block but not used elsewhere for the purpose of lifetime
   // extension.
   if (VD->hasAttr<BlocksAttr>() && Ty->isObjCObjectPointerType())
     return;
 
   // Don't warn about Objective-C pointer variables with precise lifetime
   // semantics; they can be used to ensure ARC releases the object at a known
   // time, which may mean assignment but no other references.
   if (VD->hasAttr<ObjCPreciseLifetimeAttr>() && Ty->isObjCObjectPointerType())
     return;
 
   auto iter = RefsMinusAssignments.find(VD);
   if (iter == RefsMinusAssignments.end())
     return;
 
   assert(iter->getSecond() >= 0 &&
          "Found a negative number of references to a VarDecl");
   if (iter->getSecond() != 0)
     return;
   unsigned DiagID = isa<ParmVarDecl>(VD) ? diag::warn_unused_but_set_parameter
                                          : diag::warn_unused_but_set_variable;
   DiagReceiver(VD->getLocation(), PDiag(DiagID) << VD);
 }
 
 static void CheckPoppedLabel(LabelDecl *L, Sema &S,
                              Sema::DiagReceiverTy DiagReceiver) {
   // Verify that we have no forward references left.  If so, there was a goto
   // or address of a label taken, but no definition of it.  Label fwd
   // definitions are indicated with a null substmt which is also not a resolved
   // MS inline assembly label name.
   bool Diagnose = false;
   if (L->isMSAsmLabel())
     Diagnose = !L->isResolvedMSAsmLabel();
   else
     Diagnose = L->getStmt() == nullptr;
   if (Diagnose)
     DiagReceiver(L->getLocation(), S.PDiag(diag::err_undeclared_label_use)
                                        << L);
 }
 
 void Sema::ActOnPopScope(SourceLocation Loc, Scope *S) {
   S->applyNRVO();
 
   if (S->decl_empty()) return;
   assert((S->getFlags() & (Scope::DeclScope | Scope::TemplateParamScope)) &&
          "Scope shouldn't contain decls!");
 
   /// We visit the decls in non-deterministic order, but we want diagnostics
   /// emitted in deterministic order. Collect any diagnostic that may be emitted
   /// and sort the diagnostics before emitting them, after we visited all decls.
   struct LocAndDiag {
     SourceLocation Loc;
     std::optional<SourceLocation> PreviousDeclLoc;
     PartialDiagnostic PD;
   };
   SmallVector<LocAndDiag, 16> DeclDiags;
   auto addDiag = [&DeclDiags](SourceLocation Loc, PartialDiagnostic PD) {
     DeclDiags.push_back(LocAndDiag{Loc, std::nullopt, std::move(PD)});
   };
   auto addDiagWithPrev = [&DeclDiags](SourceLocation Loc,
                                       SourceLocation PreviousDeclLoc,
                                       PartialDiagnostic PD) {
     DeclDiags.push_back(LocAndDiag{Loc, PreviousDeclLoc, std::move(PD)});
   };
 
   for (auto *TmpD : S->decls()) {
     assert(TmpD && "This decl didn't get pushed??");
 
     assert(isa<NamedDecl>(TmpD) && "Decl isn't NamedDecl?");
     NamedDecl *D = cast<NamedDecl>(TmpD);
 
     // Diagnose unused variables in this scope.
     if (!S->hasUnrecoverableErrorOccurred()) {
       DiagnoseUnusedDecl(D, addDiag);
       if (const auto *RD = dyn_cast<RecordDecl>(D))
         DiagnoseUnusedNestedTypedefs(RD, addDiag);
       if (VarDecl *VD = dyn_cast<VarDecl>(D)) {
         DiagnoseUnusedButSetDecl(VD, addDiag);
         RefsMinusAssignments.erase(VD);
       }
     }
 
     if (!D->getDeclName()) continue;
 
     // If this was a forward reference to a label, verify it was defined.
     if (LabelDecl *LD = dyn_cast<LabelDecl>(D))
       CheckPoppedLabel(LD, *this, addDiag);
 
     // Remove this name from our lexical scope, and warn on it if we haven't
     // already.
     IdResolver.RemoveDecl(D);
     auto ShadowI = ShadowingDecls.find(D);
     if (ShadowI != ShadowingDecls.end()) {
       if (const auto *FD = dyn_cast<FieldDecl>(ShadowI->second)) {
         addDiagWithPrev(D->getLocation(), FD->getLocation(),
                         PDiag(diag::warn_ctor_parm_shadows_field)
                             << D << FD << FD->getParent());
       }
       ShadowingDecls.erase(ShadowI);
     }
   }
 
   llvm::sort(DeclDiags,
              [](const LocAndDiag &LHS, const LocAndDiag &RHS) -> bool {
                // The particular order for diagnostics is not important, as long
                // as the order is deterministic. Using the raw location is going
                // to generally be in source order unless there are macro
                // expansions involved.
                return LHS.Loc.getRawEncoding() < RHS.Loc.getRawEncoding();
              });
   for (const LocAndDiag &D : DeclDiags) {
     Diag(D.Loc, D.PD);
     if (D.PreviousDeclLoc)
       Diag(*D.PreviousDeclLoc, diag::note_previous_declaration);
   }
 }
 
 /// Look for an Objective-C class in the translation unit.
 ///
 /// \param Id The name of the Objective-C class we're looking for. If
 /// typo-correction fixes this name, the Id will be updated
 /// to the fixed name.
 ///
 /// \param IdLoc The location of the name in the translation unit.
 ///
 /// \param DoTypoCorrection If true, this routine will attempt typo correction
 /// if there is no class with the given name.
 ///
 /// \returns The declaration of the named Objective-C class, or NULL if the
 /// class could not be found.
 ObjCInterfaceDecl *Sema::getObjCInterfaceDecl(IdentifierInfo *&Id,
                                               SourceLocation IdLoc,
                                               bool DoTypoCorrection) {
   // The third "scope" argument is 0 since we aren't enabling lazy built-in
   // creation from this context.
   NamedDecl *IDecl = LookupSingleName(TUScope, Id, IdLoc, LookupOrdinaryName);
 
   if (!IDecl && DoTypoCorrection) {
     // Perform typo correction at the given location, but only if we
     // find an Objective-C class name.
     DeclFilterCCC<ObjCInterfaceDecl> CCC{};
     if (TypoCorrection C =
             CorrectTypo(DeclarationNameInfo(Id, IdLoc), LookupOrdinaryName,
                         TUScope, nullptr, CCC, CTK_ErrorRecovery)) {
       diagnoseTypo(C, PDiag(diag::err_undef_interface_suggest) << Id);
       IDecl = C.getCorrectionDeclAs<ObjCInterfaceDecl>();
       Id = IDecl->getIdentifier();
     }
   }
   ObjCInterfaceDecl *Def = dyn_cast_or_null<ObjCInterfaceDecl>(IDecl);
   // This routine must always return a class definition, if any.
   if (Def && Def->getDefinition())
       Def = Def->getDefinition();
   return Def;
 }
 
 /// getNonFieldDeclScope - Retrieves the innermost scope, starting
 /// from S, where a non-field would be declared. This routine copes
 /// with the difference between C and C++ scoping rules in structs and
 /// unions. For example, the following code is well-formed in C but
 /// ill-formed in C++:
 /// @code
 /// struct S6 {
 ///   enum { BAR } e;
 /// };
 ///
 /// void test_S6() {
 ///   struct S6 a;
 ///   a.e = BAR;
 /// }
 /// @endcode
 /// For the declaration of BAR, this routine will return a different
 /// scope. The scope S will be the scope of the unnamed enumeration
 /// within S6. In C++, this routine will return the scope associated
 /// with S6, because the enumeration's scope is a transparent
 /// context but structures can contain non-field names. In C, this
 /// routine will return the translation unit scope, since the
 /// enumeration's scope is a transparent context and structures cannot
 /// contain non-field names.
 Scope *Sema::getNonFieldDeclScope(Scope *S) {
   while (((S->getFlags() & Scope::DeclScope) == 0) ||
          (S->getEntity() && S->getEntity()->isTransparentContext()) ||
          (S->isClassScope() && !getLangOpts().CPlusPlus))
     S = S->getParent();
   return S;
 }
 
 static StringRef getHeaderName(Builtin::Context &BuiltinInfo, unsigned ID,
                                ASTContext::GetBuiltinTypeError Error) {
   switch (Error) {
   case ASTContext::GE_None:
     return "";
   case ASTContext::GE_Missing_type:
     return BuiltinInfo.getHeaderName(ID);
   case ASTContext::GE_Missing_stdio:
     return "stdio.h";
   case ASTContext::GE_Missing_setjmp:
     return "setjmp.h";
   case ASTContext::GE_Missing_ucontext:
     return "ucontext.h";
   }
   llvm_unreachable("unhandled error kind");
 }
 
 FunctionDecl *Sema::CreateBuiltin(IdentifierInfo *II, QualType Type,
                                   unsigned ID, SourceLocation Loc) {
   DeclContext *Parent = Context.getTranslationUnitDecl();
 
   if (getLangOpts().CPlusPlus) {
     LinkageSpecDecl *CLinkageDecl = LinkageSpecDecl::Create(
         Context, Parent, Loc, Loc, LinkageSpecDecl::lang_c, false);
     CLinkageDecl->setImplicit();
     Parent->addDecl(CLinkageDecl);
     Parent = CLinkageDecl;
   }
 
   FunctionDecl *New = FunctionDecl::Create(Context, Parent, Loc, Loc, II, Type,
                                            /*TInfo=*/nullptr, SC_Extern,
                                            getCurFPFeatures().isFPConstrained(),
                                            false, Type->isFunctionProtoType());
   New->setImplicit();
   New->addAttr(BuiltinAttr::CreateImplicit(Context, ID));
 
   // Create Decl objects for each parameter, adding them to the
   // FunctionDecl.
   if (const FunctionProtoType *FT = dyn_cast<FunctionProtoType>(Type)) {
     SmallVector<ParmVarDecl *, 16> Params;
     for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i) {
       ParmVarDecl *parm = ParmVarDecl::Create(
           Context, New, SourceLocation(), SourceLocation(), nullptr,
           FT->getParamType(i), /*TInfo=*/nullptr, SC_None, nullptr);
       parm->setScopeInfo(0, i);
       Params.push_back(parm);
     }
     New->setParams(Params);
   }
 
   AddKnownFunctionAttributes(New);
   return New;
 }
 
 /// LazilyCreateBuiltin - The specified Builtin-ID was first used at
 /// file scope.  lazily create a decl for it. ForRedeclaration is true
 /// if we're creating this built-in in anticipation of redeclaring the
 /// built-in.
 NamedDecl *Sema::LazilyCreateBuiltin(IdentifierInfo *II, unsigned ID,
                                      Scope *S, bool ForRedeclaration,
                                      SourceLocation Loc) {
   LookupNecessaryTypesForBuiltin(S, ID);
 
   ASTContext::GetBuiltinTypeError Error;
   QualType R = Context.GetBuiltinType(ID, Error);
   if (Error) {
     if (!ForRedeclaration)
       return nullptr;
 
     // If we have a builtin without an associated type we should not emit a
     // warning when we were not able to find a type for it.
     if (Error == ASTContext::GE_Missing_type ||
         Context.BuiltinInfo.allowTypeMismatch(ID))
       return nullptr;
 
     // If we could not find a type for setjmp it is because the jmp_buf type was
     // not defined prior to the setjmp declaration.
     if (Error == ASTContext::GE_Missing_setjmp) {
       Diag(Loc, diag::warn_implicit_decl_no_jmp_buf)
           << Context.BuiltinInfo.getName(ID);
       return nullptr;
     }
 
     // Generally, we emit a warning that the declaration requires the
     // appropriate header.
     Diag(Loc, diag::warn_implicit_decl_requires_sysheader)
         << getHeaderName(Context.BuiltinInfo, ID, Error)
         << Context.BuiltinInfo.getName(ID);
     return nullptr;
   }
 
   if (!ForRedeclaration &&
       (Context.BuiltinInfo.isPredefinedLibFunction(ID) ||
        Context.BuiltinInfo.isHeaderDependentFunction(ID))) {
     Diag(Loc, LangOpts.C99 ? diag::ext_implicit_lib_function_decl_c99
                            : diag::ext_implicit_lib_function_decl)
         << Context.BuiltinInfo.getName(ID) << R;
     if (const char *Header = Context.BuiltinInfo.getHeaderName(ID))
       Diag(Loc, diag::note_include_header_or_declare)
           << Header << Context.BuiltinInfo.getName(ID);
   }
 
   if (R.isNull())
     return nullptr;
 
   FunctionDecl *New = CreateBuiltin(II, R, ID, Loc);
   RegisterLocallyScopedExternCDecl(New, S);
 
   // TUScope is the translation-unit scope to insert this function into.
   // FIXME: This is hideous. We need to teach PushOnScopeChains to
   // relate Scopes to DeclContexts, and probably eliminate CurContext
   // entirely, but we're not there yet.
   DeclContext *SavedContext = CurContext;
   CurContext = New->getDeclContext();
   PushOnScopeChains(New, TUScope);
   CurContext = SavedContext;
   return New;
 }
 
 /// Typedef declarations don't have linkage, but they still denote the same
 /// entity if their types are the same.
 /// FIXME: This is notionally doing the same thing as ASTReaderDecl's
 /// isSameEntity.
 static void filterNonConflictingPreviousTypedefDecls(Sema &S,
                                                      TypedefNameDecl *Decl,
                                                      LookupResult &Previous) {
   // This is only interesting when modules are enabled.
   if (!S.getLangOpts().Modules && !S.getLangOpts().ModulesLocalVisibility)
     return;
 
   // Empty sets are uninteresting.
   if (Previous.empty())
     return;
 
   LookupResult::Filter Filter = Previous.makeFilter();
   while (Filter.hasNext()) {
     NamedDecl *Old = Filter.next();
 
     // Non-hidden declarations are never ignored.
     if (S.isVisible(Old))
       continue;
 
     // Declarations of the same entity are not ignored, even if they have
     // different linkages.
     if (auto *OldTD = dyn_cast<TypedefNameDecl>(Old)) {
       if (S.Context.hasSameType(OldTD->getUnderlyingType(),
                                 Decl->getUnderlyingType()))
         continue;
 
       // If both declarations give a tag declaration a typedef name for linkage
       // purposes, then they declare the same entity.
       if (OldTD->getAnonDeclWithTypedefName(/*AnyRedecl*/true) &&
           Decl->getAnonDeclWithTypedefName())
         continue;
     }
 
     Filter.erase();
   }
 
   Filter.done();
 }
 
 bool Sema::isIncompatibleTypedef(TypeDecl *Old, TypedefNameDecl *New) {
   QualType OldType;
   if (TypedefNameDecl *OldTypedef = dyn_cast<TypedefNameDecl>(Old))
     OldType = OldTypedef->getUnderlyingType();
   else
     OldType = Context.getTypeDeclType(Old);
   QualType NewType = New->getUnderlyingType();
 
   if (NewType->isVariablyModifiedType()) {
     // Must not redefine a typedef with a variably-modified type.
     int Kind = isa<TypeAliasDecl>(Old) ? 1 : 0;
     Diag(New->getLocation(), diag::err_redefinition_variably_modified_typedef)
       << Kind << NewType;
     if (Old->getLocation().isValid())
       notePreviousDefinition(Old, New->getLocation());
     New->setInvalidDecl();
     return true;
   }
 
   if (OldType != NewType &&
       !OldType->isDependentType() &&
       !NewType->isDependentType() &&
       !Context.hasSameType(OldType, NewType)) {
     int Kind = isa<TypeAliasDecl>(Old) ? 1 : 0;
     Diag(New->getLocation(), diag::err_redefinition_different_typedef)
       << Kind << NewType << OldType;
     if (Old->getLocation().isValid())
       notePreviousDefinition(Old, New->getLocation());
     New->setInvalidDecl();
     return true;
   }
   return false;
 }
 
 /// MergeTypedefNameDecl - We just parsed a typedef 'New' which has the
 /// same name and scope as a previous declaration 'Old'.  Figure out
 /// how to resolve this situation, merging decls or emitting
 /// diagnostics as appropriate. If there was an error, set New to be invalid.
 ///
 void Sema::MergeTypedefNameDecl(Scope *S, TypedefNameDecl *New,
                                 LookupResult &OldDecls) {
   // If the new decl is known invalid already, don't bother doing any
   // merging checks.
   if (New->isInvalidDecl()) return;
 
   // Allow multiple definitions for ObjC built-in typedefs.
   // FIXME: Verify the underlying types are equivalent!
   if (getLangOpts().ObjC) {
     const IdentifierInfo *TypeID = New->getIdentifier();
     switch (TypeID->getLength()) {
     default: break;
     case 2:
       {
         if (!TypeID->isStr("id"))
           break;
         QualType T = New->getUnderlyingType();
         if (!T->isPointerType())
           break;
         if (!T->isVoidPointerType()) {
           QualType PT = T->castAs<PointerType>()->getPointeeType();
           if (!PT->isStructureType())
             break;
         }
         Context.setObjCIdRedefinitionType(T);
         // Install the built-in type for 'id', ignoring the current definition.
         New->setTypeForDecl(Context.getObjCIdType().getTypePtr());
         return;
       }
     case 5:
       if (!TypeID->isStr("Class"))
         break;
       Context.setObjCClassRedefinitionType(New->getUnderlyingType());
       // Install the built-in type for 'Class', ignoring the current definition.
       New->setTypeForDecl(Context.getObjCClassType().getTypePtr());
       return;
     case 3:
       if (!TypeID->isStr("SEL"))
         break;
       Context.setObjCSelRedefinitionType(New->getUnderlyingType());
       // Install the built-in type for 'SEL', ignoring the current definition.
       New->setTypeForDecl(Context.getObjCSelType().getTypePtr());
       return;
     }
     // Fall through - the typedef name was not a builtin type.
   }
 
   // Verify the old decl was also a type.
   TypeDecl *Old = OldDecls.getAsSingle<TypeDecl>();
   if (!Old) {
     Diag(New->getLocation(), diag::err_redefinition_different_kind)
       << New->getDeclName();
 
     NamedDecl *OldD = OldDecls.getRepresentativeDecl();
     if (OldD->getLocation().isValid())
       notePreviousDefinition(OldD, New->getLocation());
 
     return New->setInvalidDecl();
   }
 
   // If the old declaration is invalid, just give up here.
   if (Old->isInvalidDecl())
     return New->setInvalidDecl();
 
   if (auto *OldTD = dyn_cast<TypedefNameDecl>(Old)) {
     auto *OldTag = OldTD->getAnonDeclWithTypedefName(/*AnyRedecl*/true);
     auto *NewTag = New->getAnonDeclWithTypedefName();
     NamedDecl *Hidden = nullptr;
     if (OldTag && NewTag &&
         OldTag->getCanonicalDecl() != NewTag->getCanonicalDecl() &&
         !hasVisibleDefinition(OldTag, &Hidden)) {
       // There is a definition of this tag, but it is not visible. Use it
       // instead of our tag.
       New->setTypeForDecl(OldTD->getTypeForDecl());
       if (OldTD->isModed())
         New->setModedTypeSourceInfo(OldTD->getTypeSourceInfo(),
                                     OldTD->getUnderlyingType());
       else
         New->setTypeSourceInfo(OldTD->getTypeSourceInfo());
 
       // Make the old tag definition visible.
       makeMergedDefinitionVisible(Hidden);
 
       // If this was an unscoped enumeration, yank all of its enumerators
       // out of the scope.
       if (isa<EnumDecl>(NewTag)) {
         Scope *EnumScope = getNonFieldDeclScope(S);
         for (auto *D : NewTag->decls()) {
           auto *ED = cast<EnumConstantDecl>(D);
           assert(EnumScope->isDeclScope(ED));
           EnumScope->RemoveDecl(ED);
           IdResolver.RemoveDecl(ED);
           ED->getLexicalDeclContext()->removeDecl(ED);
         }
       }
     }
   }
 
   // If the typedef types are not identical, reject them in all languages and
   // with any extensions enabled.
   if (isIncompatibleTypedef(Old, New))
     return;
 
   // The types match.  Link up the redeclaration chain and merge attributes if
   // the old declaration was a typedef.
   if (TypedefNameDecl *Typedef = dyn_cast<TypedefNameDecl>(Old)) {
     New->setPreviousDecl(Typedef);
     mergeDeclAttributes(New, Old);
   }
 
   if (getLangOpts().MicrosoftExt)
     return;
 
   if (getLangOpts().CPlusPlus) {
     // C++ [dcl.typedef]p2:
     //   In a given non-class scope, a typedef specifier can be used to
     //   redefine the name of any type declared in that scope to refer
     //   to the type to which it already refers.
     if (!isa<CXXRecordDecl>(CurContext))
       return;
 
     // C++0x [dcl.typedef]p4:
     //   In a given class scope, a typedef specifier can be used to redefine
     //   any class-name declared in that scope that is not also a typedef-name
     //   to refer to the type to which it already refers.
     //
     // This wording came in via DR424, which was a correction to the
     // wording in DR56, which accidentally banned code like:
     //
     //   struct S {
     //     typedef struct A { } A;
     //   };
     //
     // in the C++03 standard. We implement the C++0x semantics, which
     // allow the above but disallow
     //
     //   struct S {
     //     typedef int I;
     //     typedef int I;
     //   };
     //
     // since that was the intent of DR56.
     if (!isa<TypedefNameDecl>(Old))
       return;
 
     Diag(New->getLocation(), diag::err_redefinition)
       << New->getDeclName();
     notePreviousDefinition(Old, New->getLocation());
     return New->setInvalidDecl();
   }
 
   // Modules always permit redefinition of typedefs, as does C11.
   if (getLangOpts().Modules || getLangOpts().C11)
     return;
 
   // If we have a redefinition of a typedef in C, emit a warning.  This warning
   // is normally mapped to an error, but can be controlled with
   // -Wtypedef-redefinition.  If either the original or the redefinition is
   // in a system header, don't emit this for compatibility with GCC.
   if (getDiagnostics().getSuppressSystemWarnings() &&
       // Some standard types are defined implicitly in Clang (e.g. OpenCL).
       (Old->isImplicit() ||
        Context.getSourceManager().isInSystemHeader(Old->getLocation()) ||
        Context.getSourceManager().isInSystemHeader(New->getLocation())))
     return;
 
   Diag(New->getLocation(), diag::ext_redefinition_of_typedef)
     << New->getDeclName();
   notePreviousDefinition(Old, New->getLocation());
 }
 
 /// DeclhasAttr - returns true if decl Declaration already has the target
 /// attribute.
 static bool DeclHasAttr(const Decl *D, const Attr *A) {
   const OwnershipAttr *OA = dyn_cast<OwnershipAttr>(A);
   const AnnotateAttr *Ann = dyn_cast<AnnotateAttr>(A);
   for (const auto *i : D->attrs())
     if (i->getKind() == A->getKind()) {
       if (Ann) {
         if (Ann->getAnnotation() == cast<AnnotateAttr>(i)->getAnnotation())
           return true;
         continue;
       }
       // FIXME: Don't hardcode this check
       if (OA && isa<OwnershipAttr>(i))
         return OA->getOwnKind() == cast<OwnershipAttr>(i)->getOwnKind();
       return true;
     }
 
   return false;
 }
 
 static bool isAttributeTargetADefinition(Decl *D) {
   if (VarDecl *VD = dyn_cast<VarDecl>(D))
     return VD->isThisDeclarationADefinition();
   if (TagDecl *TD = dyn_cast<TagDecl>(D))
     return TD->isCompleteDefinition() || TD->isBeingDefined();
   return true;
 }
 
 /// Merge alignment attributes from \p Old to \p New, taking into account the
 /// special semantics of C11's _Alignas specifier and C++11's alignas attribute.
 ///
 /// \return \c true if any attributes were added to \p New.
 static bool mergeAlignedAttrs(Sema &S, NamedDecl *New, Decl *Old) {
   // Look for alignas attributes on Old, and pick out whichever attribute
   // specifies the strictest alignment requirement.
   AlignedAttr *OldAlignasAttr = nullptr;
   AlignedAttr *OldStrictestAlignAttr = nullptr;
   unsigned OldAlign = 0;
   for (auto *I : Old->specific_attrs<AlignedAttr>()) {
     // FIXME: We have no way of representing inherited dependent alignments
     // in a case like:
     //   template<int A, int B> struct alignas(A) X;
     //   template<int A, int B> struct alignas(B) X {};
     // For now, we just ignore any alignas attributes which are not on the
     // definition in such a case.
     if (I->isAlignmentDependent())
       return false;
 
     if (I->isAlignas())
       OldAlignasAttr = I;
 
     unsigned Align = I->getAlignment(S.Context);
     if (Align > OldAlign) {
       OldAlign = Align;
       OldStrictestAlignAttr = I;
     }
   }
 
   // Look for alignas attributes on New.
   AlignedAttr *NewAlignasAttr = nullptr;
   unsigned NewAlign = 0;
   for (auto *I : New->specific_attrs<AlignedAttr>()) {
     if (I->isAlignmentDependent())
       return false;
 
     if (I->isAlignas())
       NewAlignasAttr = I;
 
     unsigned Align = I->getAlignment(S.Context);
     if (Align > NewAlign)
       NewAlign = Align;
   }
 
   if (OldAlignasAttr && NewAlignasAttr && OldAlign != NewAlign) {
     // Both declarations have 'alignas' attributes. We require them to match.
     // C++11 [dcl.align]p6 and C11 6.7.5/7 both come close to saying this, but
     // fall short. (If two declarations both have alignas, they must both match
     // every definition, and so must match each other if there is a definition.)
 
     // If either declaration only contains 'alignas(0)' specifiers, then it
     // specifies the natural alignment for the type.
     if (OldAlign == 0 || NewAlign == 0) {
       QualType Ty;
       if (ValueDecl *VD = dyn_cast<ValueDecl>(New))
         Ty = VD->getType();
       else
         Ty = S.Context.getTagDeclType(cast<TagDecl>(New));
 
       if (OldAlign == 0)
         OldAlign = S.Context.getTypeAlign(Ty);
       if (NewAlign == 0)
         NewAlign = S.Context.getTypeAlign(Ty);
     }
 
     if (OldAlign != NewAlign) {
       S.Diag(NewAlignasAttr->getLocation(), diag::err_alignas_mismatch)
         << (unsigned)S.Context.toCharUnitsFromBits(OldAlign).getQuantity()
         << (unsigned)S.Context.toCharUnitsFromBits(NewAlign).getQuantity();
       S.Diag(OldAlignasAttr->getLocation(), diag::note_previous_declaration);
     }
   }
 
   if (OldAlignasAttr && !NewAlignasAttr && isAttributeTargetADefinition(New)) {
     // C++11 [dcl.align]p6:
     //   if any declaration of an entity has an alignment-specifier,
     //   every defining declaration of that entity shall specify an
     //   equivalent alignment.
     // C11 6.7.5/7:
     //   If the definition of an object does not have an alignment
     //   specifier, any other declaration of that object shall also
     //   have no alignment specifier.
     S.Diag(New->getLocation(), diag::err_alignas_missing_on_definition)
       << OldAlignasAttr;
     S.Diag(OldAlignasAttr->getLocation(), diag::note_alignas_on_declaration)
       << OldAlignasAttr;
   }
 
   bool AnyAdded = false;
 
   // Ensure we have an attribute representing the strictest alignment.
   if (OldAlign > NewAlign) {
     AlignedAttr *Clone = OldStrictestAlignAttr->clone(S.Context);
     Clone->setInherited(true);
     New->addAttr(Clone);
     AnyAdded = true;
   }
 
   // Ensure we have an alignas attribute if the old declaration had one.
   if (OldAlignasAttr && !NewAlignasAttr &&
       !(AnyAdded && OldStrictestAlignAttr->isAlignas())) {
     AlignedAttr *Clone = OldAlignasAttr->clone(S.Context);
     Clone->setInherited(true);
     New->addAttr(Clone);
     AnyAdded = true;
   }
 
   return AnyAdded;
 }
 
 #define WANT_DECL_MERGE_LOGIC
 #include "clang/Sema/AttrParsedAttrImpl.inc"
 #undef WANT_DECL_MERGE_LOGIC
 
 static bool mergeDeclAttribute(Sema &S, NamedDecl *D,
                                const InheritableAttr *Attr,
                                Sema::AvailabilityMergeKind AMK) {
   // Diagnose any mutual exclusions between the attribute that we want to add
   // and attributes that already exist on the declaration.
   if (!DiagnoseMutualExclusions(S, D, Attr))
     return false;
 
   // This function copies an attribute Attr from a previous declaration to the
   // new declaration D if the new declaration doesn't itself have that attribute
   // yet or if that attribute allows duplicates.
   // If you're adding a new attribute that requires logic different from
   // "use explicit attribute on decl if present, else use attribute from
   // previous decl", for example if the attribute needs to be consistent
   // between redeclarations, you need to call a custom merge function here.
   InheritableAttr *NewAttr = nullptr;
   if (const auto *AA = dyn_cast<AvailabilityAttr>(Attr))
     NewAttr = S.mergeAvailabilityAttr(
         D, *AA, AA->getPlatform(), AA->isImplicit(), AA->getIntroduced(),
         AA->getDeprecated(), AA->getObsoleted(), AA->getUnavailable(),
         AA->getMessage(), AA->getStrict(), AA->getReplacement(), AMK,
         AA->getPriority());
   else if (const auto *VA = dyn_cast<VisibilityAttr>(Attr))
     NewAttr = S.mergeVisibilityAttr(D, *VA, VA->getVisibility());
   else if (const auto *VA = dyn_cast<TypeVisibilityAttr>(Attr))
     NewAttr = S.mergeTypeVisibilityAttr(D, *VA, VA->getVisibility());
   else if (const auto *ImportA = dyn_cast<DLLImportAttr>(Attr))
     NewAttr = S.mergeDLLImportAttr(D, *ImportA);
   else if (const auto *ExportA = dyn_cast<DLLExportAttr>(Attr))
     NewAttr = S.mergeDLLExportAttr(D, *ExportA);
   else if (const auto *EA = dyn_cast<ErrorAttr>(Attr))
     NewAttr = S.mergeErrorAttr(D, *EA, EA->getUserDiagnostic());
   else if (const auto *FA = dyn_cast<FormatAttr>(Attr))
     NewAttr = S.mergeFormatAttr(D, *FA, FA->getType(), FA->getFormatIdx(),
                                 FA->getFirstArg());
   else if (const auto *SA = dyn_cast<SectionAttr>(Attr))
     NewAttr = S.mergeSectionAttr(D, *SA, SA->getName());
   else if (const auto *CSA = dyn_cast<CodeSegAttr>(Attr))
     NewAttr = S.mergeCodeSegAttr(D, *CSA, CSA->getName());
   else if (const auto *IA = dyn_cast<MSInheritanceAttr>(Attr))
     NewAttr = S.mergeMSInheritanceAttr(D, *IA, IA->getBestCase(),
                                        IA->getInheritanceModel());
   else if (const auto *AA = dyn_cast<AlwaysInlineAttr>(Attr))
     NewAttr = S.mergeAlwaysInlineAttr(D, *AA,
                                       &S.Context.Idents.get(AA->getSpelling()));
   else if (S.getLangOpts().CUDA && isa<FunctionDecl>(D) &&
            (isa<CUDAHostAttr>(Attr) || isa<CUDADeviceAttr>(Attr) ||
             isa<CUDAGlobalAttr>(Attr))) {
     // CUDA target attributes are part of function signature for
     // overloading purposes and must not be merged.
     return false;
   } else if (const auto *MA = dyn_cast<MinSizeAttr>(Attr))
     NewAttr = S.mergeMinSizeAttr(D, *MA);
   else if (const auto *SNA = dyn_cast<SwiftNameAttr>(Attr))
     NewAttr = S.mergeSwiftNameAttr(D, *SNA, SNA->getName());
   else if (const auto *OA = dyn_cast<OptimizeNoneAttr>(Attr))
     NewAttr = S.mergeOptimizeNoneAttr(D, *OA);
   else if (const auto *InternalLinkageA = dyn_cast<InternalLinkageAttr>(Attr))
     NewAttr = S.mergeInternalLinkageAttr(D, *InternalLinkageA);
   else if (isa<AlignedAttr>(Attr))
     // AlignedAttrs are handled separately, because we need to handle all
     // such attributes on a declaration at the same time.
     NewAttr = nullptr;
   else if ((isa<DeprecatedAttr>(Attr) || isa<UnavailableAttr>(Attr)) &&
            (AMK == Sema::AMK_Override ||
             AMK == Sema::AMK_ProtocolImplementation ||
             AMK == Sema::AMK_OptionalProtocolImplementation))
     NewAttr = nullptr;
   else if (const auto *UA = dyn_cast<UuidAttr>(Attr))
     NewAttr = S.mergeUuidAttr(D, *UA, UA->getGuid(), UA->getGuidDecl());
   else if (const auto *IMA = dyn_cast<WebAssemblyImportModuleAttr>(Attr))
     NewAttr = S.mergeImportModuleAttr(D, *IMA);
   else if (const auto *INA = dyn_cast<WebAssemblyImportNameAttr>(Attr))
     NewAttr = S.mergeImportNameAttr(D, *INA);
   else if (const auto *TCBA = dyn_cast<EnforceTCBAttr>(Attr))
     NewAttr = S.mergeEnforceTCBAttr(D, *TCBA);
   else if (const auto *TCBLA = dyn_cast<EnforceTCBLeafAttr>(Attr))
     NewAttr = S.mergeEnforceTCBLeafAttr(D, *TCBLA);
   else if (const auto *BTFA = dyn_cast<BTFDeclTagAttr>(Attr))
     NewAttr = S.mergeBTFDeclTagAttr(D, *BTFA);
   else if (const auto *NT = dyn_cast<HLSLNumThreadsAttr>(Attr))
     NewAttr =
         S.mergeHLSLNumThreadsAttr(D, *NT, NT->getX(), NT->getY(), NT->getZ());
   else if (const auto *SA = dyn_cast<HLSLShaderAttr>(Attr))
     NewAttr = S.mergeHLSLShaderAttr(D, *SA, SA->getType());
   else if (Attr->shouldInheritEvenIfAlreadyPresent() || !DeclHasAttr(D, Attr))
     NewAttr = cast<InheritableAttr>(Attr->clone(S.Context));
 
   if (NewAttr) {
     NewAttr->setInherited(true);
     D->addAttr(NewAttr);
     if (isa<MSInheritanceAttr>(NewAttr))
       S.Consumer.AssignInheritanceModel(cast<CXXRecordDecl>(D));
     return true;
   }
 
   return false;
 }
 
 static const NamedDecl *getDefinition(const Decl *D) {
   if (const TagDecl *TD = dyn_cast<TagDecl>(D))
     return TD->getDefinition();
   if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
     const VarDecl *Def = VD->getDefinition();
     if (Def)
       return Def;
     return VD->getActingDefinition();
   }
   if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
     const FunctionDecl *Def = nullptr;
     if (FD->isDefined(Def, true))
       return Def;
   }
   return nullptr;
 }
 
 static bool hasAttribute(const Decl *D, attr::Kind Kind) {
   for (const auto *Attribute : D->attrs())
     if (Attribute->getKind() == Kind)
       return true;
   return false;
 }
 
 /// checkNewAttributesAfterDef - If we already have a definition, check that
 /// there are no new attributes in this declaration.
 static void checkNewAttributesAfterDef(Sema &S, Decl *New, const Decl *Old) {
   if (!New->hasAttrs())
     return;
 
   const NamedDecl *Def = getDefinition(Old);
   if (!Def || Def == New)
     return;
 
   AttrVec &NewAttributes = New->getAttrs();
   for (unsigned I = 0, E = NewAttributes.size(); I != E;) {
     const Attr *NewAttribute = NewAttributes[I];
 
     if (isa<AliasAttr>(NewAttribute) || isa<IFuncAttr>(NewAttribute)) {
       if (FunctionDecl *FD = dyn_cast<FunctionDecl>(New)) {
         Sema::SkipBodyInfo SkipBody;
         S.CheckForFunctionRedefinition(FD, cast<FunctionDecl>(Def), &SkipBody);
 
         // If we're skipping this definition, drop the "alias" attribute.
         if (SkipBody.ShouldSkip) {
           NewAttributes.erase(NewAttributes.begin() + I);
           --E;
           continue;
         }
       } else {
         VarDecl *VD = cast<VarDecl>(New);
         unsigned Diag = cast<VarDecl>(Def)->isThisDeclarationADefinition() ==
                                 VarDecl::TentativeDefinition
                             ? diag::err_alias_after_tentative
                             : diag::err_redefinition;
         S.Diag(VD->getLocation(), Diag) << VD->getDeclName();
         if (Diag == diag::err_redefinition)
           S.notePreviousDefinition(Def, VD->getLocation());
         else
           S.Diag(Def->getLocation(), diag::note_previous_definition);
         VD->setInvalidDecl();
       }
       ++I;
       continue;
     }
 
     if (const VarDecl *VD = dyn_cast<VarDecl>(Def)) {
       // Tentative definitions are only interesting for the alias check above.
       if (VD->isThisDeclarationADefinition() != VarDecl::Definition) {
         ++I;
         continue;
       }
     }
 
     if (hasAttribute(Def, NewAttribute->getKind())) {
       ++I;
       continue; // regular attr merging will take care of validating this.
     }
 
     if (isa<C11NoReturnAttr>(NewAttribute)) {
       // C's _Noreturn is allowed to be added to a function after it is defined.
       ++I;
       continue;
     } else if (isa<UuidAttr>(NewAttribute)) {
       // msvc will allow a subsequent definition to add an uuid to a class
       ++I;
       continue;
     } else if (const AlignedAttr *AA = dyn_cast<AlignedAttr>(NewAttribute)) {
       if (AA->isAlignas()) {
         // C++11 [dcl.align]p6:
         //   if any declaration of an entity has an alignment-specifier,
         //   every defining declaration of that entity shall specify an
         //   equivalent alignment.
         // C11 6.7.5/7:
         //   If the definition of an object does not have an alignment
         //   specifier, any other declaration of that object shall also
         //   have no alignment specifier.
         S.Diag(Def->getLocation(), diag::err_alignas_missing_on_definition)
           << AA;
         S.Diag(NewAttribute->getLocation(), diag::note_alignas_on_declaration)
           << AA;
         NewAttributes.erase(NewAttributes.begin() + I);
         --E;
         continue;
       }
     } else if (isa<LoaderUninitializedAttr>(NewAttribute)) {
       // If there is a C definition followed by a redeclaration with this
       // attribute then there are two different definitions. In C++, prefer the
       // standard diagnostics.
       if (!S.getLangOpts().CPlusPlus) {
         S.Diag(NewAttribute->getLocation(),
                diag::err_loader_uninitialized_redeclaration);
         S.Diag(Def->getLocation(), diag::note_previous_definition);
         NewAttributes.erase(NewAttributes.begin() + I);
         --E;
         continue;
       }
     } else if (isa<SelectAnyAttr>(NewAttribute) &&
                cast<VarDecl>(New)->isInline() &&
                !cast<VarDecl>(New)->isInlineSpecified()) {
       // Don't warn about applying selectany to implicitly inline variables.
       // Older compilers and language modes would require the use of selectany
       // to make such variables inline, and it would have no effect if we
       // honored it.
       ++I;
       continue;
     } else if (isa<OMPDeclareVariantAttr>(NewAttribute)) {
       // We allow to add OMP[Begin]DeclareVariantAttr to be added to
       // declarations after definitions.
       ++I;
       continue;
     }
 
     S.Diag(NewAttribute->getLocation(),
            diag::warn_attribute_precede_definition);
     S.Diag(Def->getLocation(), diag::note_previous_definition);
     NewAttributes.erase(NewAttributes.begin() + I);
     --E;
   }
 }
 
 static void diagnoseMissingConstinit(Sema &S, const VarDecl *InitDecl,
                                      const ConstInitAttr *CIAttr,
                                      bool AttrBeforeInit) {
   SourceLocation InsertLoc = InitDecl->getInnerLocStart();
 
   // Figure out a good way to write this specifier on the old declaration.
   // FIXME: We should just use the spelling of CIAttr, but we don't preserve
   // enough of the attribute list spelling information to extract that without
   // heroics.
   std::string SuitableSpelling;
   if (S.getLangOpts().CPlusPlus20)
     SuitableSpelling = std::string(
         S.PP.getLastMacroWithSpelling(InsertLoc, {tok::kw_constinit}));
   if (SuitableSpelling.empty() && S.getLangOpts().CPlusPlus11)
     SuitableSpelling = std::string(S.PP.getLastMacroWithSpelling(
         InsertLoc, {tok::l_square, tok::l_square,
                     S.PP.getIdentifierInfo("clang"), tok::coloncolon,
                     S.PP.getIdentifierInfo("require_constant_initialization"),
                     tok::r_square, tok::r_square}));
   if (SuitableSpelling.empty())
     SuitableSpelling = std::string(S.PP.getLastMacroWithSpelling(
         InsertLoc, {tok::kw___attribute, tok::l_paren, tok::r_paren,
                     S.PP.getIdentifierInfo("require_constant_initialization"),
                     tok::r_paren, tok::r_paren}));
   if (SuitableSpelling.empty() && S.getLangOpts().CPlusPlus20)
     SuitableSpelling = "constinit";
   if (SuitableSpelling.empty() && S.getLangOpts().CPlusPlus11)
     SuitableSpelling = "[[clang::require_constant_initialization]]";
   if (SuitableSpelling.empty())
     SuitableSpelling = "__attribute__((require_constant_initialization))";
   SuitableSpelling += " ";
 
   if (AttrBeforeInit) {
     // extern constinit int a;
     // int a = 0; // error (missing 'constinit'), accepted as extension
     assert(CIAttr->isConstinit() && "should not diagnose this for attribute");
     S.Diag(InitDecl->getLocation(), diag::ext_constinit_missing)
         << InitDecl << FixItHint::CreateInsertion(InsertLoc, SuitableSpelling);
     S.Diag(CIAttr->getLocation(), diag::note_constinit_specified_here);
   } else {
     // int a = 0;
     // constinit extern int a; // error (missing 'constinit')
     S.Diag(CIAttr->getLocation(),
            CIAttr->isConstinit() ? diag::err_constinit_added_too_late
                                  : diag::warn_require_const_init_added_too_late)
         << FixItHint::CreateRemoval(SourceRange(CIAttr->getLocation()));
     S.Diag(InitDecl->getLocation(), diag::note_constinit_missing_here)
         << CIAttr->isConstinit()
         << FixItHint::CreateInsertion(InsertLoc, SuitableSpelling);
   }
 }
 
 /// mergeDeclAttributes - Copy attributes from the Old decl to the New one.
 void Sema::mergeDeclAttributes(NamedDecl *New, Decl *Old,
                                AvailabilityMergeKind AMK) {
   if (UsedAttr *OldAttr = Old->getMostRecentDecl()->getAttr<UsedAttr>()) {
     UsedAttr *NewAttr = OldAttr->clone(Context);
     NewAttr->setInherited(true);
     New->addAttr(NewAttr);
   }
   if (RetainAttr *OldAttr = Old->getMostRecentDecl()->getAttr<RetainAttr>()) {
     RetainAttr *NewAttr = OldAttr->clone(Context);
     NewAttr->setInherited(true);
     New->addAttr(NewAttr);
   }
 
   if (!Old->hasAttrs() && !New->hasAttrs())
     return;
 
   // [dcl.constinit]p1:
   //   If the [constinit] specifier is applied to any declaration of a
   //   variable, it shall be applied to the initializing declaration.
   const auto *OldConstInit = Old->getAttr<ConstInitAttr>();
   const auto *NewConstInit = New->getAttr<ConstInitAttr>();
   if (bool(OldConstInit) != bool(NewConstInit)) {
     const auto *OldVD = cast<VarDecl>(Old);
     auto *NewVD = cast<VarDecl>(New);
 
     // Find the initializing declaration. Note that we might not have linked
     // the new declaration into the redeclaration chain yet.
     const VarDecl *InitDecl = OldVD->getInitializingDeclaration();
     if (!InitDecl &&
         (NewVD->hasInit() || NewVD->isThisDeclarationADefinition()))
       InitDecl = NewVD;
 
     if (InitDecl == NewVD) {
       // This is the initializing declaration. If it would inherit 'constinit',
       // that's ill-formed. (Note that we do not apply this to the attribute
       // form).
       if (OldConstInit && OldConstInit->isConstinit())
         diagnoseMissingConstinit(*this, NewVD, OldConstInit,
                                  /*AttrBeforeInit=*/true);
     } else if (NewConstInit) {
       // This is the first time we've been told that this declaration should
       // have a constant initializer. If we already saw the initializing
       // declaration, this is too late.
       if (InitDecl && InitDecl != NewVD) {
         diagnoseMissingConstinit(*this, InitDecl, NewConstInit,
                                  /*AttrBeforeInit=*/false);
         NewVD->dropAttr<ConstInitAttr>();
       }
     }
   }
 
   // Attributes declared post-definition are currently ignored.
   checkNewAttributesAfterDef(*this, New, Old);
 
   if (AsmLabelAttr *NewA = New->getAttr<AsmLabelAttr>()) {
     if (AsmLabelAttr *OldA = Old->getAttr<AsmLabelAttr>()) {
       if (!OldA->isEquivalent(NewA)) {
         // This redeclaration changes __asm__ label.
         Diag(New->getLocation(), diag::err_different_asm_label);
         Diag(OldA->getLocation(), diag::note_previous_declaration);
       }
     } else if (Old->isUsed()) {
       // This redeclaration adds an __asm__ label to a declaration that has
       // already been ODR-used.
       Diag(New->getLocation(), diag::err_late_asm_label_name)
         << isa<FunctionDecl>(Old) << New->getAttr<AsmLabelAttr>()->getRange();
     }
   }
 
   // Re-declaration cannot add abi_tag's.
   if (const auto *NewAbiTagAttr = New->getAttr<AbiTagAttr>()) {
     if (const auto *OldAbiTagAttr = Old->getAttr<AbiTagAttr>()) {
       for (const auto &NewTag : NewAbiTagAttr->tags()) {
         if (!llvm::is_contained(OldAbiTagAttr->tags(), NewTag)) {
           Diag(NewAbiTagAttr->getLocation(),
                diag::err_new_abi_tag_on_redeclaration)
               << NewTag;
           Diag(OldAbiTagAttr->getLocation(), diag::note_previous_declaration);
         }
       }
     } else {
       Diag(NewAbiTagAttr->getLocation(), diag::err_abi_tag_on_redeclaration);
       Diag(Old->getLocation(), diag::note_previous_declaration);
     }
   }
 
   // This redeclaration adds a section attribute.
   if (New->hasAttr<SectionAttr>() && !Old->hasAttr<SectionAttr>()) {
     if (auto *VD = dyn_cast<VarDecl>(New)) {
       if (VD->isThisDeclarationADefinition() == VarDecl::DeclarationOnly) {
         Diag(New->getLocation(), diag::warn_attribute_section_on_redeclaration);
         Diag(Old->getLocation(), diag::note_previous_declaration);
       }
     }
   }
 
   // Redeclaration adds code-seg attribute.
   const auto *NewCSA = New->getAttr<CodeSegAttr>();
   if (NewCSA && !Old->hasAttr<CodeSegAttr>() &&
       !NewCSA->isImplicit() && isa<CXXMethodDecl>(New)) {
     Diag(New->getLocation(), diag::warn_mismatched_section)
          << 0 /*codeseg*/;
     Diag(Old->getLocation(), diag::note_previous_declaration);
   }
 
   if (!Old->hasAttrs())
     return;
 
   bool foundAny = New->hasAttrs();
 
   // Ensure that any moving of objects within the allocated map is done before
   // we process them.
   if (!foundAny) New->setAttrs(AttrVec());
 
   for (auto *I : Old->specific_attrs<InheritableAttr>()) {
     // Ignore deprecated/unavailable/availability attributes if requested.
     AvailabilityMergeKind LocalAMK = AMK_None;
     if (isa<DeprecatedAttr>(I) ||
         isa<UnavailableAttr>(I) ||
         isa<AvailabilityAttr>(I)) {
       switch (AMK) {
       case AMK_None:
         continue;
 
       case AMK_Redeclaration:
       case AMK_Override:
       case AMK_ProtocolImplementation:
       case AMK_OptionalProtocolImplementation:
         LocalAMK = AMK;
         break;
       }
     }
 
     // Already handled.
     if (isa<UsedAttr>(I) || isa<RetainAttr>(I))
       continue;
 
     if (mergeDeclAttribute(*this, New, I, LocalAMK))
       foundAny = true;
   }
 
   if (mergeAlignedAttrs(*this, New, Old))
     foundAny = true;
 
   if (!foundAny) New->dropAttrs();
 }
 
 /// mergeParamDeclAttributes - Copy attributes from the old parameter
 /// to the new one.
 static void mergeParamDeclAttributes(ParmVarDecl *newDecl,
                                      const ParmVarDecl *oldDecl,
                                      Sema &S) {
   // C++11 [dcl.attr.depend]p2:
   //   The first declaration of a function shall specify the
   //   carries_dependency attribute for its declarator-id if any declaration
   //   of the function specifies the carries_dependency attribute.
   const CarriesDependencyAttr *CDA = newDecl->getAttr<CarriesDependencyAttr>();
   if (CDA && !oldDecl->hasAttr<CarriesDependencyAttr>()) {
     S.Diag(CDA->getLocation(),
            diag::err_carries_dependency_missing_on_first_decl) << 1/*Param*/;
     // Find the first declaration of the parameter.
     // FIXME: Should we build redeclaration chains for function parameters?
     const FunctionDecl *FirstFD =
       cast<FunctionDecl>(oldDecl->getDeclContext())->getFirstDecl();
     const ParmVarDecl *FirstVD =
       FirstFD->getParamDecl(oldDecl->getFunctionScopeIndex());
     S.Diag(FirstVD->getLocation(),
            diag::note_carries_dependency_missing_first_decl) << 1/*Param*/;
   }
 
   if (!oldDecl->hasAttrs())
     return;
 
   bool foundAny = newDecl->hasAttrs();
 
   // Ensure that any moving of objects within the allocated map is
   // done before we process them.
   if (!foundAny) newDecl->setAttrs(AttrVec());
 
   for (const auto *I : oldDecl->specific_attrs<InheritableParamAttr>()) {
     if (!DeclHasAttr(newDecl, I)) {
       InheritableAttr *newAttr =
         cast<InheritableParamAttr>(I->clone(S.Context));
       newAttr->setInherited(true);
       newDecl->addAttr(newAttr);
       foundAny = true;
     }
   }
 
   if (!foundAny) newDecl->dropAttrs();
 }
 
 static bool EquivalentArrayTypes(QualType Old, QualType New,
                                  const ASTContext &Ctx) {
 
   auto NoSizeInfo = [&Ctx](QualType Ty) {
     if (Ty->isIncompleteArrayType() || Ty->isPointerType())
       return true;
     if (const auto *VAT = Ctx.getAsVariableArrayType(Ty))
       return VAT->getSizeModifier() == ArrayType::ArraySizeModifier::Star;
     return false;
   };
 
   // `type[]` is equivalent to `type *` and `type[*]`.
   if (NoSizeInfo(Old) && NoSizeInfo(New))
     return true;
 
   // Don't try to compare VLA sizes, unless one of them has the star modifier.
   if (Old->isVariableArrayType() && New->isVariableArrayType()) {
     const auto *OldVAT = Ctx.getAsVariableArrayType(Old);
     const auto *NewVAT = Ctx.getAsVariableArrayType(New);
     if ((OldVAT->getSizeModifier() == ArrayType::ArraySizeModifier::Star) ^
         (NewVAT->getSizeModifier() == ArrayType::ArraySizeModifier::Star))
       return false;
     return true;
   }
 
   // Only compare size, ignore Size modifiers and CVR.
   if (Old->isConstantArrayType() && New->isConstantArrayType()) {
     return Ctx.getAsConstantArrayType(Old)->getSize() ==
            Ctx.getAsConstantArrayType(New)->getSize();
   }
 
   // Don't try to compare dependent sized array
   if (Old->isDependentSizedArrayType() && New->isDependentSizedArrayType()) {
     return true;
   }
 
   return Old == New;
 }
 
 static void mergeParamDeclTypes(ParmVarDecl *NewParam,
                                 const ParmVarDecl *OldParam,
                                 Sema &S) {
   if (auto Oldnullability = OldParam->getType()->getNullability()) {
     if (auto Newnullability = NewParam->getType()->getNullability()) {
       if (*Oldnullability != *Newnullability) {
         S.Diag(NewParam->getLocation(), diag::warn_mismatched_nullability_attr)
           << DiagNullabilityKind(
                *Newnullability,
                ((NewParam->getObjCDeclQualifier() & Decl::OBJC_TQ_CSNullability)
                 != 0))
           << DiagNullabilityKind(
                *Oldnullability,
                ((OldParam->getObjCDeclQualifier() & Decl::OBJC_TQ_CSNullability)
                 != 0));
         S.Diag(OldParam->getLocation(), diag::note_previous_declaration);
       }
     } else {
       QualType NewT = NewParam->getType();
       NewT = S.Context.getAttributedType(
                          AttributedType::getNullabilityAttrKind(*Oldnullability),
                          NewT, NewT);
       NewParam->setType(NewT);
     }
   }
   const auto *OldParamDT = dyn_cast<DecayedType>(OldParam->getType());
   const auto *NewParamDT = dyn_cast<DecayedType>(NewParam->getType());
   if (OldParamDT && NewParamDT &&
       OldParamDT->getPointeeType() == NewParamDT->getPointeeType()) {
     QualType OldParamOT = OldParamDT->getOriginalType();
     QualType NewParamOT = NewParamDT->getOriginalType();
     if (!EquivalentArrayTypes(OldParamOT, NewParamOT, S.getASTContext())) {
       S.Diag(NewParam->getLocation(), diag::warn_inconsistent_array_form)
           << NewParam << NewParamOT;
       S.Diag(OldParam->getLocation(), diag::note_previous_declaration_as)
           << OldParamOT;
     }
   }
 }
 
 namespace {
 
 /// Used in MergeFunctionDecl to keep track of function parameters in
 /// C.
 struct GNUCompatibleParamWarning {
   ParmVarDecl *OldParm;
   ParmVarDecl *NewParm;
   QualType PromotedType;
 };
 
 } // end anonymous namespace
 
 // Determine whether the previous declaration was a definition, implicit
 // declaration, or a declaration.
 template <typename T>
 static std::pair<diag::kind, SourceLocation>
 getNoteDiagForInvalidRedeclaration(const T *Old, const T *New) {
   diag::kind PrevDiag;
   SourceLocation OldLocation = Old->getLocation();
   if (Old->isThisDeclarationADefinition())
     PrevDiag = diag::note_previous_definition;
   else if (Old->isImplicit()) {
     PrevDiag = diag::note_previous_implicit_declaration;
     if (const auto *FD = dyn_cast<FunctionDecl>(Old)) {
       if (FD->getBuiltinID())
         PrevDiag = diag::note_previous_builtin_declaration;
     }
     if (OldLocation.isInvalid())
       OldLocation = New->getLocation();
   } else
     PrevDiag = diag::note_previous_declaration;
   return std::make_pair(PrevDiag, OldLocation);
 }
 
 /// canRedefineFunction - checks if a function can be redefined. Currently,
 /// only extern inline functions can be redefined, and even then only in
 /// GNU89 mode.
 static bool canRedefineFunction(const FunctionDecl *FD,
                                 const LangOptions& LangOpts) {
   return ((FD->hasAttr<GNUInlineAttr>() || LangOpts.GNUInline) &&
           !LangOpts.CPlusPlus &&
           FD->isInlineSpecified() &&
           FD->getStorageClass() == SC_Extern);
 }
 
 const AttributedType *Sema::getCallingConvAttributedType(QualType T) const {
   const AttributedType *AT = T->getAs<AttributedType>();
   while (AT && !AT->isCallingConv())
     AT = AT->getModifiedType()->getAs<AttributedType>();
   return AT;
 }
 
 template <typename T>
 static bool haveIncompatibleLanguageLinkages(const T *Old, const T *New) {
   const DeclContext *DC = Old->getDeclContext();
   if (DC->isRecord())
     return false;
 
   LanguageLinkage OldLinkage = Old->getLanguageLinkage();
   if (OldLinkage == CXXLanguageLinkage && New->isInExternCContext())
     return true;
   if (OldLinkage == CLanguageLinkage && New->isInExternCXXContext())
     return true;
   return false;
 }
 
 template<typename T> static bool isExternC(T *D) { return D->isExternC(); }
 static bool isExternC(VarTemplateDecl *) { return false; }
 static bool isExternC(FunctionTemplateDecl *) { return false; }
 
 /// Check whether a redeclaration of an entity introduced by a
 /// using-declaration is valid, given that we know it's not an overload
 /// (nor a hidden tag declaration).
 template<typename ExpectedDecl>
 static bool checkUsingShadowRedecl(Sema &S, UsingShadowDecl *OldS,
                                    ExpectedDecl *New) {
   // C++11 [basic.scope.declarative]p4:
   //   Given a set of declarations in a single declarative region, each of
   //   which specifies the same unqualified name,
   //   -- they shall all refer to the same entity, or all refer to functions
   //      and function templates; or
   //   -- exactly one declaration shall declare a class name or enumeration
   //      name that is not a typedef name and the other declarations shall all
   //      refer to the same variable or enumerator, or all refer to functions
   //      and function templates; in this case the class name or enumeration
   //      name is hidden (3.3.10).
 
   // C++11 [namespace.udecl]p14:
   //   If a function declaration in namespace scope or block scope has the
   //   same name and the same parameter-type-list as a function introduced
   //   by a using-declaration, and the declarations do not declare the same
   //   function, the program is ill-formed.
 
   auto *Old = dyn_cast<ExpectedDecl>(OldS->getTargetDecl());
   if (Old &&
       !Old->getDeclContext()->getRedeclContext()->Equals(
           New->getDeclContext()->getRedeclContext()) &&
       !(isExternC(Old) && isExternC(New)))
     Old = nullptr;
 
   if (!Old) {
     S.Diag(New->getLocation(), diag::err_using_decl_conflict_reverse);
     S.Diag(OldS->getTargetDecl()->getLocation(), diag::note_using_decl_target);
     S.Diag(OldS->getIntroducer()->getLocation(), diag::note_using_decl) << 0;
     return true;
   }
   return false;
 }
 
 static bool hasIdenticalPassObjectSizeAttrs(const FunctionDecl *A,
                                             const FunctionDecl *B) {
   assert(A->getNumParams() == B->getNumParams());
 
   auto AttrEq = [](const ParmVarDecl *A, const ParmVarDecl *B) {
     const auto *AttrA = A->getAttr<PassObjectSizeAttr>();
     const auto *AttrB = B->getAttr<PassObjectSizeAttr>();
     if (AttrA == AttrB)
       return true;
     return AttrA && AttrB && AttrA->getType() == AttrB->getType() &&
            AttrA->isDynamic() == AttrB->isDynamic();
   };
 
   return std::equal(A->param_begin(), A->param_end(), B->param_begin(), AttrEq);
 }
 
 /// If necessary, adjust the semantic declaration context for a qualified
 /// declaration to name the correct inline namespace within the qualifier.
 static void adjustDeclContextForDeclaratorDecl(DeclaratorDecl *NewD,
                                                DeclaratorDecl *OldD) {
   // The only case where we need to update the DeclContext is when
   // redeclaration lookup for a qualified name finds a declaration
   // in an inline namespace within the context named by the qualifier:
   //
   //   inline namespace N { int f(); }
   //   int ::f(); // Sema DC needs adjusting from :: to N::.
   //
   // For unqualified declarations, the semantic context *can* change
   // along the redeclaration chain (for local extern declarations,
   // extern "C" declarations, and friend declarations in particular).
   if (!NewD->getQualifier())
     return;
 
   // NewD is probably already in the right context.
   auto *NamedDC = NewD->getDeclContext()->getRedeclContext();
   auto *SemaDC = OldD->getDeclContext()->getRedeclContext();
   if (NamedDC->Equals(SemaDC))
     return;
 
   assert((NamedDC->InEnclosingNamespaceSetOf(SemaDC) ||
           NewD->isInvalidDecl() || OldD->isInvalidDecl()) &&
          "unexpected context for redeclaration");
 
   auto *LexDC = NewD->getLexicalDeclContext();
   auto FixSemaDC = [=](NamedDecl *D) {
     if (!D)
       return;
     D->setDeclContext(SemaDC);
     D->setLexicalDeclContext(LexDC);
   };
 
   FixSemaDC(NewD);
   if (auto *FD = dyn_cast<FunctionDecl>(NewD))
     FixSemaDC(FD->getDescribedFunctionTemplate());
   else if (auto *VD = dyn_cast<VarDecl>(NewD))
     FixSemaDC(VD->getDescribedVarTemplate());
 }
 
 /// MergeFunctionDecl - We just parsed a function 'New' from
 /// declarator D which has the same name and scope as a previous
 /// declaration 'Old'.  Figure out how to resolve this situation,
 /// merging decls or emitting diagnostics as appropriate.
 ///
 /// In C++, New and Old must be declarations that are not
 /// overloaded. Use IsOverload to determine whether New and Old are
 /// overloaded, and to select the Old declaration that New should be
 /// merged with.
 ///
 /// Returns true if there was an error, false otherwise.
 bool Sema::MergeFunctionDecl(FunctionDecl *New, NamedDecl *&OldD, Scope *S,
                              bool MergeTypeWithOld, bool NewDeclIsDefn) {
   // Verify the old decl was also a function.
   FunctionDecl *Old = OldD->getAsFunction();
   if (!Old) {
     if (UsingShadowDecl *Shadow = dyn_cast<UsingShadowDecl>(OldD)) {
       if (New->getFriendObjectKind()) {
         Diag(New->getLocation(), diag::err_using_decl_friend);
         Diag(Shadow->getTargetDecl()->getLocation(),
              diag::note_using_decl_target);
         Diag(Shadow->getIntroducer()->getLocation(), diag::note_using_decl)
             << 0;
         return true;
       }
 
       // Check whether the two declarations might declare the same function or
       // function template.
       if (FunctionTemplateDecl *NewTemplate =
               New->getDescribedFunctionTemplate()) {
         if (checkUsingShadowRedecl<FunctionTemplateDecl>(*this, Shadow,
                                                          NewTemplate))
           return true;
         OldD = Old = cast<FunctionTemplateDecl>(Shadow->getTargetDecl())
                          ->getAsFunction();
       } else {
         if (checkUsingShadowRedecl<FunctionDecl>(*this, Shadow, New))
           return true;
         OldD = Old = cast<FunctionDecl>(Shadow->getTargetDecl());
       }
     } else {
       Diag(New->getLocation(), diag::err_redefinition_different_kind)
         << New->getDeclName();
       notePreviousDefinition(OldD, New->getLocation());
       return true;
     }
   }
 
   // If the old declaration was found in an inline namespace and the new
   // declaration was qualified, update the DeclContext to match.
   adjustDeclContextForDeclaratorDecl(New, Old);
 
   // If the old declaration is invalid, just give up here.
   if (Old->isInvalidDecl())
     return true;
 
   // Disallow redeclaration of some builtins.
   if (!getASTContext().canBuiltinBeRedeclared(Old)) {
     Diag(New->getLocation(), diag::err_builtin_redeclare) << Old->getDeclName();
     Diag(Old->getLocation(), diag::note_previous_builtin_declaration)
         << Old << Old->getType();
     return true;
   }
 
   diag::kind PrevDiag;
   SourceLocation OldLocation;
   std::tie(PrevDiag, OldLocation) =
       getNoteDiagForInvalidRedeclaration(Old, New);
 
   // Don't complain about this if we're in GNU89 mode and the old function
   // is an extern inline function.
   // Don't complain about specializations. They are not supposed to have
   // storage classes.
   if (!isa<CXXMethodDecl>(New) && !isa<CXXMethodDecl>(Old) &&
       New->getStorageClass() == SC_Static &&
       Old->hasExternalFormalLinkage() &&
       !New->getTemplateSpecializationInfo() &&
       !canRedefineFunction(Old, getLangOpts())) {
     if (getLangOpts().MicrosoftExt) {
       Diag(New->getLocation(), diag::ext_static_non_static) << New;
       Diag(OldLocation, PrevDiag) << Old << Old->getType();
     } else {
       Diag(New->getLocation(), diag::err_static_non_static) << New;
       Diag(OldLocation, PrevDiag) << Old << Old->getType();
       return true;
     }
   }
 
   if (const auto *ILA = New->getAttr<InternalLinkageAttr>())
     if (!Old->hasAttr<InternalLinkageAttr>()) {
       Diag(New->getLocation(), diag::err_attribute_missing_on_first_decl)
           << ILA;
       Diag(Old->getLocation(), diag::note_previous_declaration);
       New->dropAttr<InternalLinkageAttr>();
     }
 
   if (auto *EA = New->getAttr<ErrorAttr>()) {
     if (!Old->hasAttr<ErrorAttr>()) {
       Diag(EA->getLocation(), diag::err_attribute_missing_on_first_decl) << EA;
       Diag(Old->getLocation(), diag::note_previous_declaration);
       New->dropAttr<ErrorAttr>();
     }
   }
 
   if (CheckRedeclarationInModule(New, Old))
     return true;
 
   if (!getLangOpts().CPlusPlus) {
     bool OldOvl = Old->hasAttr<OverloadableAttr>();
     if (OldOvl != New->hasAttr<OverloadableAttr>() && !Old->isImplicit()) {
       Diag(New->getLocation(), diag::err_attribute_overloadable_mismatch)
         << New << OldOvl;
 
       // Try our best to find a decl that actually has the overloadable
       // attribute for the note. In most cases (e.g. programs with only one
       // broken declaration/definition), this won't matter.
       //
       // FIXME: We could do this if we juggled some extra state in
       // OverloadableAttr, rather than just removing it.
       const Decl *DiagOld = Old;
       if (OldOvl) {
         auto OldIter = llvm::find_if(Old->redecls(), [](const Decl *D) {
           const auto *A = D->getAttr<OverloadableAttr>();
           return A && !A->isImplicit();
         });
         // If we've implicitly added *all* of the overloadable attrs to this
         // chain, emitting a "previous redecl" note is pointless.
         DiagOld = OldIter == Old->redecls_end() ? nullptr : *OldIter;
       }
 
       if (DiagOld)
         Diag(DiagOld->getLocation(),
              diag::note_attribute_overloadable_prev_overload)
           << OldOvl;
 
       if (OldOvl)
         New->addAttr(OverloadableAttr::CreateImplicit(Context));
       else
         New->dropAttr<OverloadableAttr>();
     }
   }
 
   // If a function is first declared with a calling convention, but is later
   // declared or defined without one, all following decls assume the calling
   // convention of the first.
   //
   // It's OK if a function is first declared without a calling convention,
   // but is later declared or defined with the default calling convention.
   //
   // To test if either decl has an explicit calling convention, we look for
   // AttributedType sugar nodes on the type as written.  If they are missing or
   // were canonicalized away, we assume the calling convention was implicit.
   //
   // Note also that we DO NOT return at this point, because we still have
   // other tests to run.
   QualType OldQType = Context.getCanonicalType(Old->getType());
   QualType NewQType = Context.getCanonicalType(New->getType());
   const FunctionType *OldType = cast<FunctionType>(OldQType);
   const FunctionType *NewType = cast<FunctionType>(NewQType);
   FunctionType::ExtInfo OldTypeInfo = OldType->getExtInfo();
   FunctionType::ExtInfo NewTypeInfo = NewType->getExtInfo();
   bool RequiresAdjustment = false;
 
   if (OldTypeInfo.getCC() != NewTypeInfo.getCC()) {
     FunctionDecl *First = Old->getFirstDecl();
     const FunctionType *FT =
         First->getType().getCanonicalType()->castAs<FunctionType>();
     FunctionType::ExtInfo FI = FT->getExtInfo();
     bool NewCCExplicit = getCallingConvAttributedType(New->getType());
     if (!NewCCExplicit) {
       // Inherit the CC from the previous declaration if it was specified
       // there but not here.
       NewTypeInfo = NewTypeInfo.withCallingConv(OldTypeInfo.getCC());
       RequiresAdjustment = true;
     } else if (Old->getBuiltinID()) {
       // Builtin attribute isn't propagated to the new one yet at this point,
       // so we check if the old one is a builtin.
 
       // Calling Conventions on a Builtin aren't really useful and setting a
       // default calling convention and cdecl'ing some builtin redeclarations is
       // common, so warn and ignore the calling convention on the redeclaration.
       Diag(New->getLocation(), diag::warn_cconv_unsupported)
           << FunctionType::getNameForCallConv(NewTypeInfo.getCC())
           << (int)CallingConventionIgnoredReason::BuiltinFunction;
       NewTypeInfo = NewTypeInfo.withCallingConv(OldTypeInfo.getCC());
       RequiresAdjustment = true;
     } else {
       // Calling conventions aren't compatible, so complain.
       bool FirstCCExplicit = getCallingConvAttributedType(First->getType());
       Diag(New->getLocation(), diag::err_cconv_change)
         << FunctionType::getNameForCallConv(NewTypeInfo.getCC())
         << !FirstCCExplicit
         << (!FirstCCExplicit ? "" :
             FunctionType::getNameForCallConv(FI.getCC()));
 
       // Put the note on the first decl, since it is the one that matters.
       Diag(First->getLocation(), diag::note_previous_declaration);
       return true;
     }
   }
 
   // FIXME: diagnose the other way around?
   if (OldTypeInfo.getNoReturn() && !NewTypeInfo.getNoReturn()) {
     NewTypeInfo = NewTypeInfo.withNoReturn(true);
     RequiresAdjustment = true;
   }
 
   // Merge regparm attribute.
   if (OldTypeInfo.getHasRegParm() != NewTypeInfo.getHasRegParm() ||
       OldTypeInfo.getRegParm() != NewTypeInfo.getRegParm()) {
     if (NewTypeInfo.getHasRegParm()) {
       Diag(New->getLocation(), diag::err_regparm_mismatch)
         << NewType->getRegParmType()
         << OldType->getRegParmType();
       Diag(OldLocation, diag::note_previous_declaration);
       return true;
     }
 
     NewTypeInfo = NewTypeInfo.withRegParm(OldTypeInfo.getRegParm());
     RequiresAdjustment = true;
   }
 
   // Merge ns_returns_retained attribute.
   if (OldTypeInfo.getProducesResult() != NewTypeInfo.getProducesResult()) {
     if (NewTypeInfo.getProducesResult()) {
       Diag(New->getLocation(), diag::err_function_attribute_mismatch)
           << "'ns_returns_retained'";
       Diag(OldLocation, diag::note_previous_declaration);
       return true;
     }
 
     NewTypeInfo = NewTypeInfo.withProducesResult(true);
     RequiresAdjustment = true;
   }
 
   if (OldTypeInfo.getNoCallerSavedRegs() !=
       NewTypeInfo.getNoCallerSavedRegs()) {
     if (NewTypeInfo.getNoCallerSavedRegs()) {
       AnyX86NoCallerSavedRegistersAttr *Attr =
         New->getAttr<AnyX86NoCallerSavedRegistersAttr>();
       Diag(New->getLocation(), diag::err_function_attribute_mismatch) << Attr;
       Diag(OldLocation, diag::note_previous_declaration);
       return true;
     }
 
     NewTypeInfo = NewTypeInfo.withNoCallerSavedRegs(true);
     RequiresAdjustment = true;
   }
 
   if (RequiresAdjustment) {
     const FunctionType *AdjustedType = New->getType()->getAs<FunctionType>();
     AdjustedType = Context.adjustFunctionType(AdjustedType, NewTypeInfo);
     New->setType(QualType(AdjustedType, 0));
     NewQType = Context.getCanonicalType(New->getType());
   }
 
   // If this redeclaration makes the function inline, we may need to add it to
   // UndefinedButUsed.
   if (!Old->isInlined() && New->isInlined() &&
       !New->hasAttr<GNUInlineAttr>() &&
       !getLangOpts().GNUInline &&
       Old->isUsed(false) &&
       !Old->isDefined() && !New->isThisDeclarationADefinition())
     UndefinedButUsed.insert(std::make_pair(Old->getCanonicalDecl(),
                                            SourceLocation()));
 
   // If this redeclaration makes it newly gnu_inline, we don't want to warn
   // about it.
   if (New->hasAttr<GNUInlineAttr>() &&
       Old->isInlined() && !Old->hasAttr<GNUInlineAttr>()) {
     UndefinedButUsed.erase(Old->getCanonicalDecl());
   }
 
   // If pass_object_size params don't match up perfectly, this isn't a valid
   // redeclaration.
   if (Old->getNumParams() > 0 && Old->getNumParams() == New->getNumParams() &&
       !hasIdenticalPassObjectSizeAttrs(Old, New)) {
     Diag(New->getLocation(), diag::err_different_pass_object_size_params)
         << New->getDeclName();
     Diag(OldLocation, PrevDiag) << Old << Old->getType();
     return true;
   }
 
   if (getLangOpts().CPlusPlus) {
     // C++1z [over.load]p2
     //   Certain function declarations cannot be overloaded:
     //     -- Function declarations that differ only in the return type,
     //        the exception specification, or both cannot be overloaded.
 
     // Check the exception specifications match. This may recompute the type of
     // both Old and New if it resolved exception specifications, so grab the
     // types again after this. Because this updates the type, we do this before
     // any of the other checks below, which may update the "de facto" NewQType
     // but do not necessarily update the type of New.
     if (CheckEquivalentExceptionSpec(Old, New))
       return true;
     OldQType = Context.getCanonicalType(Old->getType());
     NewQType = Context.getCanonicalType(New->getType());
 
     // Go back to the type source info to compare the declared return types,
     // per C++1y [dcl.type.auto]p13:
     //   Redeclarations or specializations of a function or function template
     //   with a declared return type that uses a placeholder type shall also
     //   use that placeholder, not a deduced type.
     QualType OldDeclaredReturnType = Old->getDeclaredReturnType();
     QualType NewDeclaredReturnType = New->getDeclaredReturnType();
     if (!Context.hasSameType(OldDeclaredReturnType, NewDeclaredReturnType) &&
         canFullyTypeCheckRedeclaration(New, Old, NewDeclaredReturnType,
                                        OldDeclaredReturnType)) {
       QualType ResQT;
       if (NewDeclaredReturnType->isObjCObjectPointerType() &&
           OldDeclaredReturnType->isObjCObjectPointerType())
         // FIXME: This does the wrong thing for a deduced return type.
         ResQT = Context.mergeObjCGCQualifiers(NewQType, OldQType);
       if (ResQT.isNull()) {
         if (New->isCXXClassMember() && New->isOutOfLine())
           Diag(New->getLocation(), diag::err_member_def_does_not_match_ret_type)
               << New << New->getReturnTypeSourceRange();
         else
           Diag(New->getLocation(), diag::err_ovl_diff_return_type)
               << New->getReturnTypeSourceRange();
         Diag(OldLocation, PrevDiag) << Old << Old->getType()
                                     << Old->getReturnTypeSourceRange();
         return true;
       }
       else
         NewQType = ResQT;
     }
 
     QualType OldReturnType = OldType->getReturnType();
     QualType NewReturnType = cast<FunctionType>(NewQType)->getReturnType();
     if (OldReturnType != NewReturnType) {
       // If this function has a deduced return type and has already been
       // defined, copy the deduced value from the old declaration.
       AutoType *OldAT = Old->getReturnType()->getContainedAutoType();
       if (OldAT && OldAT->isDeduced()) {
         QualType DT = OldAT->getDeducedType();
         if (DT.isNull()) {
           New->setType(SubstAutoTypeDependent(New->getType()));
           NewQType = Context.getCanonicalType(SubstAutoTypeDependent(NewQType));
         } else {
           New->setType(SubstAutoType(New->getType(), DT));
           NewQType = Context.getCanonicalType(SubstAutoType(NewQType, DT));
         }
       }
     }
 
     const CXXMethodDecl *OldMethod = dyn_cast<CXXMethodDecl>(Old);
     CXXMethodDecl *NewMethod = dyn_cast<CXXMethodDecl>(New);
     if (OldMethod && NewMethod) {
       // Preserve triviality.
       NewMethod->setTrivial(OldMethod->isTrivial());
 
       // MSVC allows explicit template specialization at class scope:
       // 2 CXXMethodDecls referring to the same function will be injected.
       // We don't want a redeclaration error.
       bool IsClassScopeExplicitSpecialization =
                               OldMethod->isFunctionTemplateSpecialization() &&
                               NewMethod->isFunctionTemplateSpecialization();
       bool isFriend = NewMethod->getFriendObjectKind();
 
       if (!isFriend && NewMethod->getLexicalDeclContext()->isRecord() &&
           !IsClassScopeExplicitSpecialization) {
         //    -- Member function declarations with the same name and the
         //       same parameter types cannot be overloaded if any of them
         //       is a static member function declaration.
         if (OldMethod->isStatic() != NewMethod->isStatic()) {
           Diag(New->getLocation(), diag::err_ovl_static_nonstatic_member);
           Diag(OldLocation, PrevDiag) << Old << Old->getType();
           return true;
         }
 
         // C++ [class.mem]p1:
         //   [...] A member shall not be declared twice in the
         //   member-specification, except that a nested class or member
         //   class template can be declared and then later defined.
         if (!inTemplateInstantiation()) {
           unsigned NewDiag;
           if (isa<CXXConstructorDecl>(OldMethod))
             NewDiag = diag::err_constructor_redeclared;
           else if (isa<CXXDestructorDecl>(NewMethod))
             NewDiag = diag::err_destructor_redeclared;
           else if (isa<CXXConversionDecl>(NewMethod))
             NewDiag = diag::err_conv_function_redeclared;
           else
             NewDiag = diag::err_member_redeclared;
 
           Diag(New->getLocation(), NewDiag);
         } else {
           Diag(New->getLocation(), diag::err_member_redeclared_in_instantiation)
             << New << New->getType();
         }
         Diag(OldLocation, PrevDiag) << Old << Old->getType();
         return true;
 
       // Complain if this is an explicit declaration of a special
       // member that was initially declared implicitly.
       //
       // As an exception, it's okay to befriend such methods in order
       // to permit the implicit constructor/destructor/operator calls.
       } else if (OldMethod->isImplicit()) {
         if (isFriend) {
           NewMethod->setImplicit();
         } else {
           Diag(NewMethod->getLocation(),
                diag::err_definition_of_implicitly_declared_member)
             << New << getSpecialMember(OldMethod);
           return true;
         }
       } else if (OldMethod->getFirstDecl()->isExplicitlyDefaulted() && !isFriend) {
         Diag(NewMethod->getLocation(),
              diag::err_definition_of_explicitly_defaulted_member)
           << getSpecialMember(OldMethod);
         return true;
       }
     }
 
     // C++11 [dcl.attr.noreturn]p1:
     //   The first declaration of a function shall specify the noreturn
     //   attribute if any declaration of that function specifies the noreturn
     //   attribute.
     if (const auto *NRA = New->getAttr<CXX11NoReturnAttr>())
       if (!Old->hasAttr<CXX11NoReturnAttr>()) {
         Diag(NRA->getLocation(), diag::err_attribute_missing_on_first_decl)
             << NRA;
         Diag(Old->getLocation(), diag::note_previous_declaration);
       }
 
     // C++11 [dcl.attr.depend]p2:
     //   The first declaration of a function shall specify the
     //   carries_dependency attribute for its declarator-id if any declaration
     //   of the function specifies the carries_dependency attribute.
     const CarriesDependencyAttr *CDA = New->getAttr<CarriesDependencyAttr>();
     if (CDA && !Old->hasAttr<CarriesDependencyAttr>()) {
       Diag(CDA->getLocation(),
            diag::err_carries_dependency_missing_on_first_decl) << 0/*Function*/;
       Diag(Old->getFirstDecl()->getLocation(),
            diag::note_carries_dependency_missing_first_decl) << 0/*Function*/;
     }
 
     // (C++98 8.3.5p3):
     //   All declarations for a function shall agree exactly in both the
     //   return type and the parameter-type-list.
     // We also want to respect all the extended bits except noreturn.
 
     // noreturn should now match unless the old type info didn't have it.
     QualType OldQTypeForComparison = OldQType;
     if (!OldTypeInfo.getNoReturn() && NewTypeInfo.getNoReturn()) {
       auto *OldType = OldQType->castAs<FunctionProtoType>();
       const FunctionType *OldTypeForComparison
         = Context.adjustFunctionType(OldType, OldTypeInfo.withNoReturn(true));
       OldQTypeForComparison = QualType(OldTypeForComparison, 0);
       assert(OldQTypeForComparison.isCanonical());
     }
 
     if (haveIncompatibleLanguageLinkages(Old, New)) {
       // As a special case, retain the language linkage from previous
       // declarations of a friend function as an extension.
       //
       // This liberal interpretation of C++ [class.friend]p3 matches GCC/MSVC
       // and is useful because there's otherwise no way to specify language
       // linkage within class scope.
       //
       // Check cautiously as the friend object kind isn't yet complete.
       if (New->getFriendObjectKind() != Decl::FOK_None) {
         Diag(New->getLocation(), diag::ext_retained_language_linkage) << New;
         Diag(OldLocation, PrevDiag);
       } else {
         Diag(New->getLocation(), diag::err_different_language_linkage) << New;
         Diag(OldLocation, PrevDiag);
         return true;
       }
     }
 
     // If the function types are compatible, merge the declarations. Ignore the
     // exception specifier because it was already checked above in
     // CheckEquivalentExceptionSpec, and we don't want follow-on diagnostics
     // about incompatible types under -fms-compatibility.
     if (Context.hasSameFunctionTypeIgnoringExceptionSpec(OldQTypeForComparison,
                                                          NewQType))
       return MergeCompatibleFunctionDecls(New, Old, S, MergeTypeWithOld);
 
     // If the types are imprecise (due to dependent constructs in friends or
     // local extern declarations), it's OK if they differ. We'll check again
     // during instantiation.
     if (!canFullyTypeCheckRedeclaration(New, Old, NewQType, OldQType))
       return false;
 
     // Fall through for conflicting redeclarations and redefinitions.
   }
 
   // C: Function types need to be compatible, not identical. This handles
   // duplicate function decls like "void f(int); void f(enum X);" properly.
   if (!getLangOpts().CPlusPlus) {
     // C99 6.7.5.3p15: ...If one type has a parameter type list and the other
     // type is specified by a function definition that contains a (possibly
     // empty) identifier list, both shall agree in the number of parameters
     // and the type of each parameter shall be compatible with the type that
     // results from the application of default argument promotions to the
     // type of the corresponding identifier. ...
     // This cannot be handled by ASTContext::typesAreCompatible() because that
     // doesn't know whether the function type is for a definition or not when
     // eventually calling ASTContext::mergeFunctionTypes(). The only situation
     // we need to cover here is that the number of arguments agree as the
     // default argument promotion rules were already checked by
     // ASTContext::typesAreCompatible().
     if (Old->hasPrototype() && !New->hasWrittenPrototype() && NewDeclIsDefn &&
         Old->getNumParams() != New->getNumParams() && !Old->isImplicit()) {
       if (Old->hasInheritedPrototype())
         Old = Old->getCanonicalDecl();
       Diag(New->getLocation(), diag::err_conflicting_types) << New;
       Diag(Old->getLocation(), PrevDiag) << Old << Old->getType();
       return true;
     }
 
     // If we are merging two functions where only one of them has a prototype,
     // we may have enough information to decide to issue a diagnostic that the
     // function without a protoype will change behavior in C2x. This handles
     // cases like:
     //   void i(); void i(int j);
     //   void i(int j); void i();
     //   void i(); void i(int j) {}
     // See ActOnFinishFunctionBody() for other cases of the behavior change
     // diagnostic. See GetFullTypeForDeclarator() for handling of a function
     // type without a prototype.
     if (New->hasWrittenPrototype() != Old->hasWrittenPrototype() &&
         !New->isImplicit() && !Old->isImplicit()) {
       const FunctionDecl *WithProto, *WithoutProto;
       if (New->hasWrittenPrototype()) {
         WithProto = New;
         WithoutProto = Old;
       } else {
         WithProto = Old;
         WithoutProto = New;
       }
 
       if (WithProto->getNumParams() != 0) {
         if (WithoutProto->getBuiltinID() == 0 && !WithoutProto->isImplicit()) {
           // The one without the prototype will be changing behavior in C2x, so
           // warn about that one so long as it's a user-visible declaration.
           bool IsWithoutProtoADef = false, IsWithProtoADef = false;
           if (WithoutProto == New)
             IsWithoutProtoADef = NewDeclIsDefn;
           else
             IsWithProtoADef = NewDeclIsDefn;
           Diag(WithoutProto->getLocation(),
                diag::warn_non_prototype_changes_behavior)
               << IsWithoutProtoADef << (WithoutProto->getNumParams() ? 0 : 1)
               << (WithoutProto == Old) << IsWithProtoADef;
 
           // The reason the one without the prototype will be changing behavior
           // is because of the one with the prototype, so note that so long as
           // it's a user-visible declaration. There is one exception to this:
           // when the new declaration is a definition without a prototype, the
           // old declaration with a prototype is not the cause of the issue,
           // and that does not need to be noted because the one with a
           // prototype will not change behavior in C2x.
           if (WithProto->getBuiltinID() == 0 && !WithProto->isImplicit() &&
               !IsWithoutProtoADef)
             Diag(WithProto->getLocation(), diag::note_conflicting_prototype);
         }
       }
     }
 
     if (Context.typesAreCompatible(OldQType, NewQType)) {
       const FunctionType *OldFuncType = OldQType->getAs<FunctionType>();
       const FunctionType *NewFuncType = NewQType->getAs<FunctionType>();
       const FunctionProtoType *OldProto = nullptr;
       if (MergeTypeWithOld && isa<FunctionNoProtoType>(NewFuncType) &&
           (OldProto = dyn_cast<FunctionProtoType>(OldFuncType))) {
         // The old declaration provided a function prototype, but the
         // new declaration does not. Merge in the prototype.
         assert(!OldProto->hasExceptionSpec() && "Exception spec in C");
         NewQType = Context.getFunctionType(NewFuncType->getReturnType(),
                                            OldProto->getParamTypes(),
                                            OldProto->getExtProtoInfo());
         New->setType(NewQType);
         New->setHasInheritedPrototype();
 
         // Synthesize parameters with the same types.
         SmallVector<ParmVarDecl *, 16> Params;
         for (const auto &ParamType : OldProto->param_types()) {
           ParmVarDecl *Param = ParmVarDecl::Create(
               Context, New, SourceLocation(), SourceLocation(), nullptr,
               ParamType, /*TInfo=*/nullptr, SC_None, nullptr);
           Param->setScopeInfo(0, Params.size());
           Param->setImplicit();
           Params.push_back(Param);
         }
 
         New->setParams(Params);
       }
 
       return MergeCompatibleFunctionDecls(New, Old, S, MergeTypeWithOld);
     }
   }
 
   // Check if the function types are compatible when pointer size address
   // spaces are ignored.
   if (Context.hasSameFunctionTypeIgnoringPtrSizes(OldQType, NewQType))
     return false;
 
   // GNU C permits a K&R definition to follow a prototype declaration
   // if the declared types of the parameters in the K&R definition
   // match the types in the prototype declaration, even when the
   // promoted types of the parameters from the K&R definition differ
   // from the types in the prototype. GCC then keeps the types from
   // the prototype.
   //
   // If a variadic prototype is followed by a non-variadic K&R definition,
   // the K&R definition becomes variadic.  This is sort of an edge case, but
   // it's legal per the standard depending on how you read C99 6.7.5.3p15 and
   // C99 6.9.1p8.
   if (!getLangOpts().CPlusPlus &&
       Old->hasPrototype() && !New->hasPrototype() &&
       New->getType()->getAs<FunctionProtoType>() &&
       Old->getNumParams() == New->getNumParams()) {
     SmallVector<QualType, 16> ArgTypes;
     SmallVector<GNUCompatibleParamWarning, 16> Warnings;
     const FunctionProtoType *OldProto
       = Old->getType()->getAs<FunctionProtoType>();
     const FunctionProtoType *NewProto
       = New->getType()->getAs<FunctionProtoType>();
 
     // Determine whether this is the GNU C extension.
     QualType MergedReturn = Context.mergeTypes(OldProto->getReturnType(),
                                                NewProto->getReturnType());
     bool LooseCompatible = !MergedReturn.isNull();
     for (unsigned Idx = 0, End = Old->getNumParams();
          LooseCompatible && Idx != End; ++Idx) {
       ParmVarDecl *OldParm = Old->getParamDecl(Idx);
       ParmVarDecl *NewParm = New->getParamDecl(Idx);
       if (Context.typesAreCompatible(OldParm->getType(),
                                      NewProto->getParamType(Idx))) {
         ArgTypes.push_back(NewParm->getType());
       } else if (Context.typesAreCompatible(OldParm->getType(),
                                             NewParm->getType(),
                                             /*CompareUnqualified=*/true)) {
         GNUCompatibleParamWarning Warn = { OldParm, NewParm,
                                            NewProto->getParamType(Idx) };
         Warnings.push_back(Warn);
         ArgTypes.push_back(NewParm->getType());
       } else
         LooseCompatible = false;
     }
 
     if (LooseCompatible) {
       for (unsigned Warn = 0; Warn < Warnings.size(); ++Warn) {
         Diag(Warnings[Warn].NewParm->getLocation(),
              diag::ext_param_promoted_not_compatible_with_prototype)
           << Warnings[Warn].PromotedType
           << Warnings[Warn].OldParm->getType();
         if (Warnings[Warn].OldParm->getLocation().isValid())
           Diag(Warnings[Warn].OldParm->getLocation(),
                diag::note_previous_declaration);
       }
 
       if (MergeTypeWithOld)
         New->setType(Context.getFunctionType(MergedReturn, ArgTypes,
                                              OldProto->getExtProtoInfo()));
       return MergeCompatibleFunctionDecls(New, Old, S, MergeTypeWithOld);
     }
 
     // Fall through to diagnose conflicting types.
   }
 
   // A function that has already been declared has been redeclared or
   // defined with a different type; show an appropriate diagnostic.
 
   // If the previous declaration was an implicitly-generated builtin
   // declaration, then at the very least we should use a specialized note.
   unsigned BuiltinID;
   if (Old->isImplicit() && (BuiltinID = Old->getBuiltinID())) {
     // If it's actually a library-defined builtin function like 'malloc'
     // or 'printf', just warn about the incompatible redeclaration.
     if (Context.BuiltinInfo.isPredefinedLibFunction(BuiltinID)) {
       Diag(New->getLocation(), diag::warn_redecl_library_builtin) << New;
       Diag(OldLocation, diag::note_previous_builtin_declaration)
         << Old << Old->getType();
       return false;
     }
 
     PrevDiag = diag::note_previous_builtin_declaration;
   }
 
   Diag(New->getLocation(), diag::err_conflicting_types) << New->getDeclName();
   Diag(OldLocation, PrevDiag) << Old << Old->getType();
   return true;
 }
 
 /// Completes the merge of two function declarations that are
 /// known to be compatible.
 ///
 /// This routine handles the merging of attributes and other
 /// properties of function declarations from the old declaration to
 /// the new declaration, once we know that New is in fact a
 /// redeclaration of Old.
 ///
 /// \returns false
 bool Sema::MergeCompatibleFunctionDecls(FunctionDecl *New, FunctionDecl *Old,
                                         Scope *S, bool MergeTypeWithOld) {
   // Merge the attributes
   mergeDeclAttributes(New, Old);
 
   // Merge "pure" flag.
   if (Old->isPure())
     New->setPure();
 
   // Merge "used" flag.
   if (Old->getMostRecentDecl()->isUsed(false))
     New->setIsUsed();
 
   // Merge attributes from the parameters.  These can mismatch with K&R
   // declarations.
   if (New->getNumParams() == Old->getNumParams())
       for (unsigned i = 0, e = New->getNumParams(); i != e; ++i) {
         ParmVarDecl *NewParam = New->getParamDecl(i);
         ParmVarDecl *OldParam = Old->getParamDecl(i);
         mergeParamDeclAttributes(NewParam, OldParam, *this);
         mergeParamDeclTypes(NewParam, OldParam, *this);
       }
 
   if (getLangOpts().CPlusPlus)
     return MergeCXXFunctionDecl(New, Old, S);
 
   // Merge the function types so the we get the composite types for the return
   // and argument types. Per C11 6.2.7/4, only update the type if the old decl
   // was visible.
   QualType Merged = Context.mergeTypes(Old->getType(), New->getType());
   if (!Merged.isNull() && MergeTypeWithOld)
     New->setType(Merged);
 
   return false;
 }
 
 void Sema::mergeObjCMethodDecls(ObjCMethodDecl *newMethod,
                                 ObjCMethodDecl *oldMethod) {
   // Merge the attributes, including deprecated/unavailable
   AvailabilityMergeKind MergeKind =
       isa<ObjCProtocolDecl>(oldMethod->getDeclContext())
           ? (oldMethod->isOptional() ? AMK_OptionalProtocolImplementation
                                      : AMK_ProtocolImplementation)
           : isa<ObjCImplDecl>(newMethod->getDeclContext()) ? AMK_Redeclaration
                                                            : AMK_Override;
 
   mergeDeclAttributes(newMethod, oldMethod, MergeKind);
 
   // Merge attributes from the parameters.
   ObjCMethodDecl::param_const_iterator oi = oldMethod->param_begin(),
                                        oe = oldMethod->param_end();
   for (ObjCMethodDecl::param_iterator
          ni = newMethod->param_begin(), ne = newMethod->param_end();
        ni != ne && oi != oe; ++ni, ++oi)
     mergeParamDeclAttributes(*ni, *oi, *this);
 
   CheckObjCMethodOverride(newMethod, oldMethod);
 }
 
 static void diagnoseVarDeclTypeMismatch(Sema &S, VarDecl *New, VarDecl* Old) {
   assert(!S.Context.hasSameType(New->getType(), Old->getType()));
 
   S.Diag(New->getLocation(), New->isThisDeclarationADefinition()
          ? diag::err_redefinition_different_type
          : diag::err_redeclaration_different_type)
     << New->getDeclName() << New->getType() << Old->getType();
 
   diag::kind PrevDiag;
   SourceLocation OldLocation;
   std::tie(PrevDiag, OldLocation)
     = getNoteDiagForInvalidRedeclaration(Old, New);
   S.Diag(OldLocation, PrevDiag) << Old << Old->getType();
   New->setInvalidDecl();
 }
 
 /// MergeVarDeclTypes - We parsed a variable 'New' which has the same name and
 /// scope as a previous declaration 'Old'.  Figure out how to merge their types,
 /// emitting diagnostics as appropriate.
 ///
 /// Declarations using the auto type specifier (C++ [decl.spec.auto]) call back
 /// to here in AddInitializerToDecl. We can't check them before the initializer
 /// is attached.
 void Sema::MergeVarDeclTypes(VarDecl *New, VarDecl *Old,
                              bool MergeTypeWithOld) {
   if (New->isInvalidDecl() || Old->isInvalidDecl() || New->getType()->containsErrors() || Old->getType()->containsErrors())
     return;
 
   QualType MergedT;
   if (getLangOpts().CPlusPlus) {
     if (New->getType()->isUndeducedType()) {
       // We don't know what the new type is until the initializer is attached.
       return;
     } else if (Context.hasSameType(New->getType(), Old->getType())) {
       // These could still be something that needs exception specs checked.
       return MergeVarDeclExceptionSpecs(New, Old);
     }
     // C++ [basic.link]p10:
     //   [...] the types specified by all declarations referring to a given
     //   object or function shall be identical, except that declarations for an
     //   array object can specify array types that differ by the presence or
     //   absence of a major array bound (8.3.4).
     else if (Old->getType()->isArrayType() && New->getType()->isArrayType()) {
       const ArrayType *OldArray = Context.getAsArrayType(Old->getType());
       const ArrayType *NewArray = Context.getAsArrayType(New->getType());
 
       // We are merging a variable declaration New into Old. If it has an array
       // bound, and that bound differs from Old's bound, we should diagnose the
       // mismatch.
       if (!NewArray->isIncompleteArrayType() && !NewArray->isDependentType()) {
         for (VarDecl *PrevVD = Old->getMostRecentDecl(); PrevVD;
              PrevVD = PrevVD->getPreviousDecl()) {
           QualType PrevVDTy = PrevVD->getType();
           if (PrevVDTy->isIncompleteArrayType() || PrevVDTy->isDependentType())
             continue;
 
           if (!Context.hasSameType(New->getType(), PrevVDTy))
             return diagnoseVarDeclTypeMismatch(*this, New, PrevVD);
         }
       }
 
       if (OldArray->isIncompleteArrayType() && NewArray->isArrayType()) {
         if (Context.hasSameType(OldArray->getElementType(),
                                 NewArray->getElementType()))
           MergedT = New->getType();
       }
       // FIXME: Check visibility. New is hidden but has a complete type. If New
       // has no array bound, it should not inherit one from Old, if Old is not
       // visible.
       else if (OldArray->isArrayType() && NewArray->isIncompleteArrayType()) {
         if (Context.hasSameType(OldArray->getElementType(),
                                 NewArray->getElementType()))
           MergedT = Old->getType();
       }
     }
     else if (New->getType()->isObjCObjectPointerType() &&
                Old->getType()->isObjCObjectPointerType()) {
       MergedT = Context.mergeObjCGCQualifiers(New->getType(),
                                               Old->getType());
     }
   } else {
     // C 6.2.7p2:
     //   All declarations that refer to the same object or function shall have
     //   compatible type.
     MergedT = Context.mergeTypes(New->getType(), Old->getType());
   }
   if (MergedT.isNull()) {
     // It's OK if we couldn't merge types if either type is dependent, for a
     // block-scope variable. In other cases (static data members of class
     // templates, variable templates, ...), we require the types to be
     // equivalent.
     // FIXME: The C++ standard doesn't say anything about this.
     if ((New->getType()->isDependentType() ||
          Old->getType()->isDependentType()) && New->isLocalVarDecl()) {
       // If the old type was dependent, we can't merge with it, so the new type
       // becomes dependent for now. We'll reproduce the original type when we
       // instantiate the TypeSourceInfo for the variable.
       if (!New->getType()->isDependentType() && MergeTypeWithOld)
         New->setType(Context.DependentTy);
       return;
     }
     return diagnoseVarDeclTypeMismatch(*this, New, Old);
   }
 
   // Don't actually update the type on the new declaration if the old
   // declaration was an extern declaration in a different scope.
   if (MergeTypeWithOld)
     New->setType(MergedT);
 }
 
 static bool mergeTypeWithPrevious(Sema &S, VarDecl *NewVD, VarDecl *OldVD,
                                   LookupResult &Previous) {
   // C11 6.2.7p4:
   //   For an identifier with internal or external linkage declared
   //   in a scope in which a prior declaration of that identifier is
   //   visible, if the prior declaration specifies internal or
   //   external linkage, the type of the identifier at the later
   //   declaration becomes the composite type.
   //
   // If the variable isn't visible, we do not merge with its type.
   if (Previous.isShadowed())
     return false;
 
   if (S.getLangOpts().CPlusPlus) {
     // C++11 [dcl.array]p3:
     //   If there is a preceding declaration of the entity in the same
     //   scope in which the bound was specified, an omitted array bound
     //   is taken to be the same as in that earlier declaration.
     return NewVD->isPreviousDeclInSameBlockScope() ||
            (!OldVD->getLexicalDeclContext()->isFunctionOrMethod() &&
             !NewVD->getLexicalDeclContext()->isFunctionOrMethod());
   } else {
     // If the old declaration was function-local, don't merge with its
     // type unless we're in the same function.
     return !OldVD->getLexicalDeclContext()->isFunctionOrMethod() ||
            OldVD->getLexicalDeclContext() == NewVD->getLexicalDeclContext();
   }
 }
 
 /// MergeVarDecl - We just parsed a variable 'New' which has the same name
 /// and scope as a previous declaration 'Old'.  Figure out how to resolve this
 /// situation, merging decls or emitting diagnostics as appropriate.
 ///
 /// Tentative definition rules (C99 6.9.2p2) are checked by
 /// FinalizeDeclaratorGroup. Unfortunately, we can't analyze tentative
 /// definitions here, since the initializer hasn't been attached.
 ///
 void Sema::MergeVarDecl(VarDecl *New, LookupResult &Previous) {
   // If the new decl is already invalid, don't do any other checking.
   if (New->isInvalidDecl())
     return;
 
   if (!shouldLinkPossiblyHiddenDecl(Previous, New))
     return;
 
   VarTemplateDecl *NewTemplate = New->getDescribedVarTemplate();
 
   // Verify the old decl was also a variable or variable template.
   VarDecl *Old = nullptr;
   VarTemplateDecl *OldTemplate = nullptr;
   if (Previous.isSingleResult()) {
     if (NewTemplate) {
       OldTemplate = dyn_cast<VarTemplateDecl>(Previous.getFoundDecl());
       Old = OldTemplate ? OldTemplate->getTemplatedDecl() : nullptr;
 
       if (auto *Shadow =
               dyn_cast<UsingShadowDecl>(Previous.getRepresentativeDecl()))
         if (checkUsingShadowRedecl<VarTemplateDecl>(*this, Shadow, NewTemplate))
           return New->setInvalidDecl();
     } else {
       Old = dyn_cast<VarDecl>(Previous.getFoundDecl());
 
       if (auto *Shadow =
               dyn_cast<UsingShadowDecl>(Previous.getRepresentativeDecl()))
         if (checkUsingShadowRedecl<VarDecl>(*this, Shadow, New))
           return New->setInvalidDecl();
     }
   }
   if (!Old) {
     Diag(New->getLocation(), diag::err_redefinition_different_kind)
         << New->getDeclName();
     notePreviousDefinition(Previous.getRepresentativeDecl(),
                            New->getLocation());
     return New->setInvalidDecl();
   }
 
   // If the old declaration was found in an inline namespace and the new
   // declaration was qualified, update the DeclContext to match.
   adjustDeclContextForDeclaratorDecl(New, Old);
 
   // Ensure the template parameters are compatible.
   if (NewTemplate &&
       !TemplateParameterListsAreEqual(NewTemplate->getTemplateParameters(),
                                       OldTemplate->getTemplateParameters(),
                                       /*Complain=*/true, TPL_TemplateMatch))
     return New->setInvalidDecl();
 
   // C++ [class.mem]p1:
   //   A member shall not be declared twice in the member-specification [...]
   //
   // Here, we need only consider static data members.
   if (Old->isStaticDataMember() && !New->isOutOfLine()) {
     Diag(New->getLocation(), diag::err_duplicate_member)
       << New->getIdentifier();
     Diag(Old->getLocation(), diag::note_previous_declaration);
     New->setInvalidDecl();
   }
 
   mergeDeclAttributes(New, Old);
   // Warn if an already-declared variable is made a weak_import in a subsequent
   // declaration
   if (New->hasAttr<WeakImportAttr>() &&
       Old->getStorageClass() == SC_None &&
       !Old->hasAttr<WeakImportAttr>()) {
     Diag(New->getLocation(), diag::warn_weak_import) << New->getDeclName();
     Diag(Old->getLocation(), diag::note_previous_declaration);
     // Remove weak_import attribute on new declaration.
     New->dropAttr<WeakImportAttr>();
   }
 
   if (const auto *ILA = New->getAttr<InternalLinkageAttr>())
     if (!Old->hasAttr<InternalLinkageAttr>()) {
       Diag(New->getLocation(), diag::err_attribute_missing_on_first_decl)
           << ILA;
       Diag(Old->getLocation(), diag::note_previous_declaration);
       New->dropAttr<InternalLinkageAttr>();
     }
 
   // Merge the types.
   VarDecl *MostRecent = Old->getMostRecentDecl();
   if (MostRecent != Old) {
     MergeVarDeclTypes(New, MostRecent,
                       mergeTypeWithPrevious(*this, New, MostRecent, Previous));
     if (New->isInvalidDecl())
       return;
   }
 
   MergeVarDeclTypes(New, Old, mergeTypeWithPrevious(*this, New, Old, Previous));
   if (New->isInvalidDecl())
     return;
 
   diag::kind PrevDiag;
   SourceLocation OldLocation;
   std::tie(PrevDiag, OldLocation) =
       getNoteDiagForInvalidRedeclaration(Old, New);
 
   // [dcl.stc]p8: Check if we have a non-static decl followed by a static.
   if (New->getStorageClass() == SC_Static &&
       !New->isStaticDataMember() &&
       Old->hasExternalFormalLinkage()) {
     if (getLangOpts().MicrosoftExt) {
       Diag(New->getLocation(), diag::ext_static_non_static)
           << New->getDeclName();
       Diag(OldLocation, PrevDiag);
     } else {
       Diag(New->getLocation(), diag::err_static_non_static)
           << New->getDeclName();
       Diag(OldLocation, PrevDiag);
       return New->setInvalidDecl();
     }
   }
   // C99 6.2.2p4:
   //   For an identifier declared with the storage-class specifier
   //   extern in a scope in which a prior declaration of that
   //   identifier is visible,23) if the prior declaration specifies
   //   internal or external linkage, the linkage of the identifier at
   //   the later declaration is the same as the linkage specified at
   //   the prior declaration. If no prior declaration is visible, or
   //   if the prior declaration specifies no linkage, then the
   //   identifier has external linkage.
   if (New->hasExternalStorage() && Old->hasLinkage())
     /* Okay */;
   else if (New->getCanonicalDecl()->getStorageClass() != SC_Static &&
            !New->isStaticDataMember() &&
            Old->getCanonicalDecl()->getStorageClass() == SC_Static) {
     Diag(New->getLocation(), diag::err_non_static_static) << New->getDeclName();
     Diag(OldLocation, PrevDiag);
     return New->setInvalidDecl();
   }
 
   // Check if extern is followed by non-extern and vice-versa.
   if (New->hasExternalStorage() &&
       !Old->hasLinkage() && Old->isLocalVarDeclOrParm()) {
     Diag(New->getLocation(), diag::err_extern_non_extern) << New->getDeclName();
     Diag(OldLocation, PrevDiag);
     return New->setInvalidDecl();
   }
   if (Old->hasLinkage() && New->isLocalVarDeclOrParm() &&
       !New->hasExternalStorage()) {
     Diag(New->getLocation(), diag::err_non_extern_extern) << New->getDeclName();
     Diag(OldLocation, PrevDiag);
     return New->setInvalidDecl();
   }
 
   if (CheckRedeclarationInModule(New, Old))
     return;
 
   // Variables with external linkage are analyzed in FinalizeDeclaratorGroup.
 
   // FIXME: The test for external storage here seems wrong? We still
   // need to check for mismatches.
   if (!New->hasExternalStorage() && !New->isFileVarDecl() &&
       // Don't complain about out-of-line definitions of static members.
       !(Old->getLexicalDeclContext()->isRecord() &&
         !New->getLexicalDeclContext()->isRecord())) {
     Diag(New->getLocation(), diag::err_redefinition) << New->getDeclName();
     Diag(OldLocation, PrevDiag);
     return New->setInvalidDecl();
   }
 
   if (New->isInline() && !Old->getMostRecentDecl()->isInline()) {
     if (VarDecl *Def = Old->getDefinition()) {
       // C++1z [dcl.fcn.spec]p4:
       //   If the definition of a variable appears in a translation unit before
       //   its first declaration as inline, the program is ill-formed.
       Diag(New->getLocation(), diag::err_inline_decl_follows_def) << New;
       Diag(Def->getLocation(), diag::note_previous_definition);
     }
   }
 
   // If this redeclaration makes the variable inline, we may need to add it to
   // UndefinedButUsed.
   if (!Old->isInline() && New->isInline() && Old->isUsed(false) &&
       !Old->getDefinition() && !New->isThisDeclarationADefinition())
     UndefinedButUsed.insert(std::make_pair(Old->getCanonicalDecl(),
                                            SourceLocation()));
 
   if (New->getTLSKind() != Old->getTLSKind()) {
     if (!Old->getTLSKind()) {
       Diag(New->getLocation(), diag::err_thread_non_thread) << New->getDeclName();
       Diag(OldLocation, PrevDiag);
     } else if (!New->getTLSKind()) {
       Diag(New->getLocation(), diag::err_non_thread_thread) << New->getDeclName();
       Diag(OldLocation, PrevDiag);
     } else {
       // Do not allow redeclaration to change the variable between requiring
       // static and dynamic initialization.
       // FIXME: GCC allows this, but uses the TLS keyword on the first
       // declaration to determine the kind. Do we need to be compatible here?
       Diag(New->getLocation(), diag::err_thread_thread_different_kind)
         << New->getDeclName() << (New->getTLSKind() == VarDecl::TLS_Dynamic);
       Diag(OldLocation, PrevDiag);
     }
   }
 
   // C++ doesn't have tentative definitions, so go right ahead and check here.
   if (getLangOpts().CPlusPlus) {
     if (Old->isStaticDataMember() && Old->getCanonicalDecl()->isInline() &&
         Old->getCanonicalDecl()->isConstexpr()) {
       // This definition won't be a definition any more once it's been merged.
       Diag(New->getLocation(),
            diag::warn_deprecated_redundant_constexpr_static_def);
     } else if (New->isThisDeclarationADefinition() == VarDecl::Definition) {
       VarDecl *Def = Old->getDefinition();
       if (Def && checkVarDeclRedefinition(Def, New))
         return;
     }
   }
 
   if (haveIncompatibleLanguageLinkages(Old, New)) {
     Diag(New->getLocation(), diag::err_different_language_linkage) << New;
     Diag(OldLocation, PrevDiag);
     New->setInvalidDecl();
     return;
   }
 
   // Merge "used" flag.
   if (Old->getMostRecentDecl()->isUsed(false))
     New->setIsUsed();
 
   // Keep a chain of previous declarations.
   New->setPreviousDecl(Old);
   if (NewTemplate)
     NewTemplate->setPreviousDecl(OldTemplate);
 
   // Inherit access appropriately.
   New->setAccess(Old->getAccess());
   if (NewTemplate)
     NewTemplate->setAccess(New->getAccess());
 
   if (Old->isInline())
     New->setImplicitlyInline();
 }
 
 void Sema::notePreviousDefinition(const NamedDecl *Old, SourceLocation New) {
   SourceManager &SrcMgr = getSourceManager();
   auto FNewDecLoc = SrcMgr.getDecomposedLoc(New);
   auto FOldDecLoc = SrcMgr.getDecomposedLoc(Old->getLocation());
   auto *FNew = SrcMgr.getFileEntryForID(FNewDecLoc.first);
   auto *FOld = SrcMgr.getFileEntryForID(FOldDecLoc.first);
   auto &HSI = PP.getHeaderSearchInfo();
   StringRef HdrFilename =
       SrcMgr.getFilename(SrcMgr.getSpellingLoc(Old->getLocation()));
 
   auto noteFromModuleOrInclude = [&](Module *Mod,
                                      SourceLocation IncLoc) -> bool {
     // Redefinition errors with modules are common with non modular mapped
     // headers, example: a non-modular header H in module A that also gets
     // included directly in a TU. Pointing twice to the same header/definition
     // is confusing, try to get better diagnostics when modules is on.
     if (IncLoc.isValid()) {
       if (Mod) {
         Diag(IncLoc, diag::note_redefinition_modules_same_file)
             << HdrFilename.str() << Mod->getFullModuleName();
         if (!Mod->DefinitionLoc.isInvalid())
           Diag(Mod->DefinitionLoc, diag::note_defined_here)
               << Mod->getFullModuleName();
       } else {
         Diag(IncLoc, diag::note_redefinition_include_same_file)
             << HdrFilename.str();
       }
       return true;
     }
 
     return false;
   };
 
   // Is it the same file and same offset? Provide more information on why
   // this leads to a redefinition error.
   if (FNew == FOld && FNewDecLoc.second == FOldDecLoc.second) {
     SourceLocation OldIncLoc = SrcMgr.getIncludeLoc(FOldDecLoc.first);
     SourceLocation NewIncLoc = SrcMgr.getIncludeLoc(FNewDecLoc.first);
     bool EmittedDiag =
         noteFromModuleOrInclude(Old->getOwningModule(), OldIncLoc);
     EmittedDiag |= noteFromModuleOrInclude(getCurrentModule(), NewIncLoc);
 
     // If the header has no guards, emit a note suggesting one.
     if (FOld && !HSI.isFileMultipleIncludeGuarded(FOld))
       Diag(Old->getLocation(), diag::note_use_ifdef_guards);
 
     if (EmittedDiag)
       return;
   }
 
   // Redefinition coming from different files or couldn't do better above.
   if (Old->getLocation().isValid())
     Diag(Old->getLocation(), diag::note_previous_definition);
 }
 
 /// We've just determined that \p Old and \p New both appear to be definitions
 /// of the same variable. Either diagnose or fix the problem.
 bool Sema::checkVarDeclRedefinition(VarDecl *Old, VarDecl *New) {
   if (!hasVisibleDefinition(Old) &&
       (New->getFormalLinkage() == InternalLinkage ||
        New->isInline() ||
        isa<VarTemplateSpecializationDecl>(New) ||
        New->getDescribedVarTemplate() ||
        New->getNumTemplateParameterLists() ||
        New->getDeclContext()->isDependentContext())) {
     // The previous definition is hidden, and multiple definitions are
     // permitted (in separate TUs). Demote this to a declaration.
     New->demoteThisDefinitionToDeclaration();
 
     // Make the canonical definition visible.
     if (auto *OldTD = Old->getDescribedVarTemplate())
       makeMergedDefinitionVisible(OldTD);
     makeMergedDefinitionVisible(Old);
     return false;
   } else {
     Diag(New->getLocation(), diag::err_redefinition) << New;
     notePreviousDefinition(Old, New->getLocation());
     New->setInvalidDecl();
     return true;
   }
 }
 
 /// ParsedFreeStandingDeclSpec - This method is invoked when a declspec with
 /// no declarator (e.g. "struct foo;") is parsed.
 Decl *Sema::ParsedFreeStandingDeclSpec(Scope *S, AccessSpecifier AS,
                                        DeclSpec &DS,
                                        const ParsedAttributesView &DeclAttrs,
                                        RecordDecl *&AnonRecord) {
   return ParsedFreeStandingDeclSpec(
       S, AS, DS, DeclAttrs, MultiTemplateParamsArg(), false, AnonRecord);
 }
 
 // The MS ABI changed between VS2013 and VS2015 with regard to numbers used to
 // disambiguate entities defined in different scopes.
 // While the VS2015 ABI fixes potential miscompiles, it is also breaks
 // compatibility.
 // We will pick our mangling number depending on which version of MSVC is being
 // targeted.
 static unsigned getMSManglingNumber(const LangOptions &LO, Scope *S) {
   return LO.isCompatibleWithMSVC(LangOptions::MSVC2015)
              ? S->getMSCurManglingNumber()
              : S->getMSLastManglingNumber();
 }
 
 void Sema::handleTagNumbering(const TagDecl *Tag, Scope *TagScope) {
   if (!Context.getLangOpts().CPlusPlus)
     return;
 
   if (isa<CXXRecordDecl>(Tag->getParent())) {
     // If this tag is the direct child of a class, number it if
     // it is anonymous.
     if (!Tag->getName().empty() || Tag->getTypedefNameForAnonDecl())
       return;
     MangleNumberingContext &MCtx =
         Context.getManglingNumberContext(Tag->getParent());
     Context.setManglingNumber(
         Tag, MCtx.getManglingNumber(
                  Tag, getMSManglingNumber(getLangOpts(), TagScope)));
     return;
   }
 
   // If this tag isn't a direct child of a class, number it if it is local.
   MangleNumberingContext *MCtx;
   Decl *ManglingContextDecl;
   std::tie(MCtx, ManglingContextDecl) =
       getCurrentMangleNumberContext(Tag->getDeclContext());
   if (MCtx) {
     Context.setManglingNumber(
         Tag, MCtx->getManglingNumber(
                  Tag, getMSManglingNumber(getLangOpts(), TagScope)));
   }
 }
 
 namespace {
 struct NonCLikeKind {
   enum {
     None,
     BaseClass,
     DefaultMemberInit,
     Lambda,
     Friend,
     OtherMember,
     Invalid,
   } Kind = None;
   SourceRange Range;
 
   explicit operator bool() { return Kind != None; }
 };
 }
 
 /// Determine whether a class is C-like, according to the rules of C++
 /// [dcl.typedef] for anonymous classes with typedef names for linkage.
 static NonCLikeKind getNonCLikeKindForAnonymousStruct(const CXXRecordDecl *RD) {
   if (RD->isInvalidDecl())
     return {NonCLikeKind::Invalid, {}};
 
   // C++ [dcl.typedef]p9: [P1766R1]
   //   An unnamed class with a typedef name for linkage purposes shall not
   //
   //    -- have any base classes
   if (RD->getNumBases())
     return {NonCLikeKind::BaseClass,
             SourceRange(RD->bases_begin()->getBeginLoc(),
                         RD->bases_end()[-1].getEndLoc())};
   bool Invalid = false;
   for (Decl *D : RD->decls()) {
     // Don't complain about things we already diagnosed.
     if (D->isInvalidDecl()) {
       Invalid = true;
       continue;
     }
 
     //  -- have any [...] default member initializers
     if (auto *FD = dyn_cast<FieldDecl>(D)) {
       if (FD->hasInClassInitializer()) {
         auto *Init = FD->getInClassInitializer();
         return {NonCLikeKind::DefaultMemberInit,
                 Init ? Init->getSourceRange() : D->getSourceRange()};
       }
       continue;
     }
 
     // FIXME: We don't allow friend declarations. This violates the wording of
     // P1766, but not the intent.
     if (isa<FriendDecl>(D))
       return {NonCLikeKind::Friend, D->getSourceRange()};
 
     //  -- declare any members other than non-static data members, member
     //     enumerations, or member classes,
     if (isa<StaticAssertDecl>(D) || isa<IndirectFieldDecl>(D) ||
         isa<EnumDecl>(D))
       continue;
     auto *MemberRD = dyn_cast<CXXRecordDecl>(D);
     if (!MemberRD) {
       if (D->isImplicit())
         continue;
       return {NonCLikeKind::OtherMember, D->getSourceRange()};
     }
 
     //  -- contain a lambda-expression,
     if (MemberRD->isLambda())
       return {NonCLikeKind::Lambda, MemberRD->getSourceRange()};
 
     //  and all member classes shall also satisfy these requirements
     //  (recursively).
     if (MemberRD->isThisDeclarationADefinition()) {
       if (auto Kind = getNonCLikeKindForAnonymousStruct(MemberRD))
         return Kind;
     }
   }
 
   return {Invalid ? NonCLikeKind::Invalid : NonCLikeKind::None, {}};
 }
 
 void Sema::setTagNameForLinkagePurposes(TagDecl *TagFromDeclSpec,
                                         TypedefNameDecl *NewTD) {
   if (TagFromDeclSpec->isInvalidDecl())
     return;
 
   // Do nothing if the tag already has a name for linkage purposes.
   if (TagFromDeclSpec->hasNameForLinkage())
     return;
 
   // A well-formed anonymous tag must always be a TUK_Definition.
   assert(TagFromDeclSpec->isThisDeclarationADefinition());
 
   // The type must match the tag exactly;  no qualifiers allowed.
   if (!Context.hasSameType(NewTD->getUnderlyingType(),
                            Context.getTagDeclType(TagFromDeclSpec))) {
     if (getLangOpts().CPlusPlus)
       Context.addTypedefNameForUnnamedTagDecl(TagFromDeclSpec, NewTD);
     return;
   }
 
   // C++ [dcl.typedef]p9: [P1766R1, applied as DR]
   //   An unnamed class with a typedef name for linkage purposes shall [be
   //   C-like].
   //
   // FIXME: Also diagnose if we've already computed the linkage. That ideally
   // shouldn't happen, but there are constructs that the language rule doesn't
   // disallow for which we can't reasonably avoid computing linkage early.
   const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(TagFromDeclSpec);
   NonCLikeKind NonCLike = RD ? getNonCLikeKindForAnonymousStruct(RD)
                              : NonCLikeKind();
   bool ChangesLinkage = TagFromDeclSpec->hasLinkageBeenComputed();
   if (NonCLike || ChangesLinkage) {
     if (NonCLike.Kind == NonCLikeKind::Invalid)
       return;
 
     unsigned DiagID = diag::ext_non_c_like_anon_struct_in_typedef;
     if (ChangesLinkage) {
       // If the linkage changes, we can't accept this as an extension.
       if (NonCLike.Kind == NonCLikeKind::None)
         DiagID = diag::err_typedef_changes_linkage;
       else
         DiagID = diag::err_non_c_like_anon_struct_in_typedef;
     }
 
     SourceLocation FixitLoc =
         getLocForEndOfToken(TagFromDeclSpec->getInnerLocStart());
     llvm::SmallString<40> TextToInsert;
     TextToInsert += ' ';
     TextToInsert += NewTD->getIdentifier()->getName();
 
     Diag(FixitLoc, DiagID)
       << isa<TypeAliasDecl>(NewTD)
       << FixItHint::CreateInsertion(FixitLoc, TextToInsert);
     if (NonCLike.Kind != NonCLikeKind::None) {
       Diag(NonCLike.Range.getBegin(), diag::note_non_c_like_anon_struct)
         << NonCLike.Kind - 1 << NonCLike.Range;
     }
     Diag(NewTD->getLocation(), diag::note_typedef_for_linkage_here)
       << NewTD << isa<TypeAliasDecl>(NewTD);
 
     if (ChangesLinkage)
       return;
   }
 
   // Otherwise, set this as the anon-decl typedef for the tag.
   TagFromDeclSpec->setTypedefNameForAnonDecl(NewTD);
 }
 
 static unsigned GetDiagnosticTypeSpecifierID(const DeclSpec &DS) {
   DeclSpec::TST T = DS.getTypeSpecType();
   switch (T) {
   case DeclSpec::TST_class:
     return 0;
   case DeclSpec::TST_struct:
     return 1;
   case DeclSpec::TST_interface:
     return 2;
   case DeclSpec::TST_union:
     return 3;
   case DeclSpec::TST_enum:
     if (const auto *ED = dyn_cast<EnumDecl>(DS.getRepAsDecl())) {
       if (ED->isScopedUsingClassTag())
         return 5;
       if (ED->isScoped())
         return 6;
     }
     return 4;
   default:
     llvm_unreachable("unexpected type specifier");
   }
 }
 /// ParsedFreeStandingDeclSpec - This method is invoked when a declspec with
 /// no declarator (e.g. "struct foo;") is parsed. It also accepts template
 /// parameters to cope with template friend declarations.
 Decl *Sema::ParsedFreeStandingDeclSpec(Scope *S, AccessSpecifier AS,
                                        DeclSpec &DS,
                                        const ParsedAttributesView &DeclAttrs,
                                        MultiTemplateParamsArg TemplateParams,
                                        bool IsExplicitInstantiation,
                                        RecordDecl *&AnonRecord) {
   Decl *TagD = nullptr;
   TagDecl *Tag = nullptr;
   if (DS.getTypeSpecType() == DeclSpec::TST_class ||
       DS.getTypeSpecType() == DeclSpec::TST_struct ||
       DS.getTypeSpecType() == DeclSpec::TST_interface ||
       DS.getTypeSpecType() == DeclSpec::TST_union ||
       DS.getTypeSpecType() == DeclSpec::TST_enum) {
     TagD = DS.getRepAsDecl();
 
     if (!TagD) // We probably had an error
       return nullptr;
 
     // Note that the above type specs guarantee that the
     // type rep is a Decl, whereas in many of the others
     // it's a Type.
     if (isa<TagDecl>(TagD))
       Tag = cast<TagDecl>(TagD);
     else if (ClassTemplateDecl *CTD = dyn_cast<ClassTemplateDecl>(TagD))
       Tag = CTD->getTemplatedDecl();
   }
 
   if (Tag) {
     handleTagNumbering(Tag, S);
     Tag->setFreeStanding();
     if (Tag->isInvalidDecl())
       return Tag;
   }
 
   if (unsigned TypeQuals = DS.getTypeQualifiers()) {
     // Enforce C99 6.7.3p2: "Types other than pointer types derived from object
     // or incomplete types shall not be restrict-qualified."
     if (TypeQuals & DeclSpec::TQ_restrict)
       Diag(DS.getRestrictSpecLoc(),
            diag::err_typecheck_invalid_restrict_not_pointer_noarg)
            << DS.getSourceRange();
   }
 
   if (DS.isInlineSpecified())
     Diag(DS.getInlineSpecLoc(), diag::err_inline_non_function)
         << getLangOpts().CPlusPlus17;
 
   if (DS.hasConstexprSpecifier()) {
     // C++0x [dcl.constexpr]p1: constexpr can only be applied to declarations
     // and definitions of functions and variables.
     // C++2a [dcl.constexpr]p1: The consteval specifier shall be applied only to
     // the declaration of a function or function template
     if (Tag)
       Diag(DS.getConstexprSpecLoc(), diag::err_constexpr_tag)
           << GetDiagnosticTypeSpecifierID(DS)
           << static_cast<int>(DS.getConstexprSpecifier());
     else
       Diag(DS.getConstexprSpecLoc(), diag::err_constexpr_wrong_decl_kind)
           << static_cast<int>(DS.getConstexprSpecifier());
     // Don't emit warnings after this error.
     return TagD;
   }
 
   DiagnoseFunctionSpecifiers(DS);
 
   if (DS.isFriendSpecified()) {
     // If we're dealing with a decl but not a TagDecl, assume that
     // whatever routines created it handled the friendship aspect.
     if (TagD && !Tag)
       return nullptr;
     return ActOnFriendTypeDecl(S, DS, TemplateParams);
   }
 
   const CXXScopeSpec &SS = DS.getTypeSpecScope();
   bool IsExplicitSpecialization =
     !TemplateParams.empty() && TemplateParams.back()->size() == 0;
   if (Tag && SS.isNotEmpty() && !Tag->isCompleteDefinition() &&
       !IsExplicitInstantiation && !IsExplicitSpecialization &&
       !isa<ClassTemplatePartialSpecializationDecl>(Tag)) {
     // Per C++ [dcl.type.elab]p1, a class declaration cannot have a
     // nested-name-specifier unless it is an explicit instantiation
     // or an explicit specialization.
     //
     // FIXME: We allow class template partial specializations here too, per the
     // obvious intent of DR1819.
     //
     // Per C++ [dcl.enum]p1, an opaque-enum-declaration can't either.
     Diag(SS.getBeginLoc(), diag::err_standalone_class_nested_name_specifier)
         << GetDiagnosticTypeSpecifierID(DS) << SS.getRange();
     return nullptr;
   }
 
   // Track whether this decl-specifier declares anything.
   bool DeclaresAnything = true;
 
   // Handle anonymous struct definitions.
   if (RecordDecl *Record = dyn_cast_or_null<RecordDecl>(Tag)) {
     if (!Record->getDeclName() && Record->isCompleteDefinition() &&
         DS.getStorageClassSpec() != DeclSpec::SCS_typedef) {
       if (getLangOpts().CPlusPlus ||
           Record->getDeclContext()->isRecord()) {
         // If CurContext is a DeclContext that can contain statements,
         // RecursiveASTVisitor won't visit the decls that
         // BuildAnonymousStructOrUnion() will put into CurContext.
         // Also store them here so that they can be part of the
         // DeclStmt that gets created in this case.
         // FIXME: Also return the IndirectFieldDecls created by
         // BuildAnonymousStructOr union, for the same reason?
         if (CurContext->isFunctionOrMethod())
           AnonRecord = Record;
         return BuildAnonymousStructOrUnion(S, DS, AS, Record,
                                            Context.getPrintingPolicy());
       }
 
       DeclaresAnything = false;
     }
   }
 
   // C11 6.7.2.1p2:
   //   A struct-declaration that does not declare an anonymous structure or
   //   anonymous union shall contain a struct-declarator-list.
   //
   // This rule also existed in C89 and C99; the grammar for struct-declaration
   // did not permit a struct-declaration without a struct-declarator-list.
   if (!getLangOpts().CPlusPlus && CurContext->isRecord() &&
       DS.getStorageClassSpec() == DeclSpec::SCS_unspecified) {
     // Check for Microsoft C extension: anonymous struct/union member.
     // Handle 2 kinds of anonymous struct/union:
     //   struct STRUCT;
     //   union UNION;
     // and
     //   STRUCT_TYPE;  <- where STRUCT_TYPE is a typedef struct.
     //   UNION_TYPE;   <- where UNION_TYPE is a typedef union.
     if ((Tag && Tag->getDeclName()) ||
         DS.getTypeSpecType() == DeclSpec::TST_typename) {
       RecordDecl *Record = nullptr;
       if (Tag)
         Record = dyn_cast<RecordDecl>(Tag);
       else if (const RecordType *RT =
                    DS.getRepAsType().get()->getAsStructureType())
         Record = RT->getDecl();
       else if (const RecordType *UT = DS.getRepAsType().get()->getAsUnionType())
         Record = UT->getDecl();
 
       if (Record && getLangOpts().MicrosoftExt) {
         Diag(DS.getBeginLoc(), diag::ext_ms_anonymous_record)
             << Record->isUnion() << DS.getSourceRange();
         return BuildMicrosoftCAnonymousStruct(S, DS, Record);
       }
 
       DeclaresAnything = false;
     }
   }
 
   // Skip all the checks below if we have a type error.
   if (DS.getTypeSpecType() == DeclSpec::TST_error ||
       (TagD && TagD->isInvalidDecl()))
     return TagD;
 
   if (getLangOpts().CPlusPlus &&
       DS.getStorageClassSpec() != DeclSpec::SCS_typedef)
     if (EnumDecl *Enum = dyn_cast_or_null<EnumDecl>(Tag))
       if (Enum->enumerator_begin() == Enum->enumerator_end() &&
           !Enum->getIdentifier() && !Enum->isInvalidDecl())
         DeclaresAnything = false;
 
   if (!DS.isMissingDeclaratorOk()) {
     // Customize diagnostic for a typedef missing a name.
     if (DS.getStorageClassSpec() == DeclSpec::SCS_typedef)
       Diag(DS.getBeginLoc(), diag::ext_typedef_without_a_name)
           << DS.getSourceRange();
     else
       DeclaresAnything = false;
   }
 
   if (DS.isModulePrivateSpecified() &&
       Tag && Tag->getDeclContext()->isFunctionOrMethod())
     Diag(DS.getModulePrivateSpecLoc(), diag::err_module_private_local_class)
       << Tag->getTagKind()
       << FixItHint::CreateRemoval(DS.getModulePrivateSpecLoc());
 
   ActOnDocumentableDecl(TagD);
 
   // C 6.7/2:
   //   A declaration [...] shall declare at least a declarator [...], a tag,
   //   or the members of an enumeration.
   // C++ [dcl.dcl]p3:
   //   [If there are no declarators], and except for the declaration of an
   //   unnamed bit-field, the decl-specifier-seq shall introduce one or more
   //   names into the program, or shall redeclare a name introduced by a
   //   previous declaration.
   if (!DeclaresAnything) {
     // In C, we allow this as a (popular) extension / bug. Don't bother
     // producing further diagnostics for redundant qualifiers after this.
     Diag(DS.getBeginLoc(), (IsExplicitInstantiation || !TemplateParams.empty())
                                ? diag::err_no_declarators
                                : diag::ext_no_declarators)
         << DS.getSourceRange();
     return TagD;
   }
 
   // C++ [dcl.stc]p1:
   //   If a storage-class-specifier appears in a decl-specifier-seq, [...] the
   //   init-declarator-list of the declaration shall not be empty.
   // C++ [dcl.fct.spec]p1:
   //   If a cv-qualifier appears in a decl-specifier-seq, the
   //   init-declarator-list of the declaration shall not be empty.
   //
   // Spurious qualifiers here appear to be valid in C.
   unsigned DiagID = diag::warn_standalone_specifier;
   if (getLangOpts().CPlusPlus)
     DiagID = diag::ext_standalone_specifier;
 
   // Note that a linkage-specification sets a storage class, but
   // 'extern "C" struct foo;' is actually valid and not theoretically
   // useless.
   if (DeclSpec::SCS SCS = DS.getStorageClassSpec()) {
     if (SCS == DeclSpec::SCS_mutable)
       // Since mutable is not a viable storage class specifier in C, there is
       // no reason to treat it as an extension. Instead, diagnose as an error.
       Diag(DS.getStorageClassSpecLoc(), diag::err_mutable_nonmember);
     else if (!DS.isExternInLinkageSpec() && SCS != DeclSpec::SCS_typedef)
       Diag(DS.getStorageClassSpecLoc(), DiagID)
         << DeclSpec::getSpecifierName(SCS);
   }
 
   if (DeclSpec::TSCS TSCS = DS.getThreadStorageClassSpec())
     Diag(DS.getThreadStorageClassSpecLoc(), DiagID)
       << DeclSpec::getSpecifierName(TSCS);
   if (DS.getTypeQualifiers()) {
     if (DS.getTypeQualifiers() & DeclSpec::TQ_const)
       Diag(DS.getConstSpecLoc(), DiagID) << "const";
     if (DS.getTypeQualifiers() & DeclSpec::TQ_volatile)
       Diag(DS.getConstSpecLoc(), DiagID) << "volatile";
     // Restrict is covered above.
     if (DS.getTypeQualifiers() & DeclSpec::TQ_atomic)
       Diag(DS.getAtomicSpecLoc(), DiagID) << "_Atomic";
     if (DS.getTypeQualifiers() & DeclSpec::TQ_unaligned)
       Diag(DS.getUnalignedSpecLoc(), DiagID) << "__unaligned";
   }
 
   // Warn about ignored type attributes, for example:
   // __attribute__((aligned)) struct A;
   // Attributes should be placed after tag to apply to type declaration.
   if (!DS.getAttributes().empty() || !DeclAttrs.empty()) {
     DeclSpec::TST TypeSpecType = DS.getTypeSpecType();
     if (TypeSpecType == DeclSpec::TST_class ||
         TypeSpecType == DeclSpec::TST_struct ||
         TypeSpecType == DeclSpec::TST_interface ||
         TypeSpecType == DeclSpec::TST_union ||
         TypeSpecType == DeclSpec::TST_enum) {
       for (const ParsedAttr &AL : DS.getAttributes())
         Diag(AL.getLoc(), AL.isRegularKeywordAttribute()
                               ? diag::err_declspec_keyword_has_no_effect
                               : diag::warn_declspec_attribute_ignored)
             << AL << GetDiagnosticTypeSpecifierID(DS);
       for (const ParsedAttr &AL : DeclAttrs)
         Diag(AL.getLoc(), AL.isRegularKeywordAttribute()
                               ? diag::err_declspec_keyword_has_no_effect
                               : diag::warn_declspec_attribute_ignored)
             << AL << GetDiagnosticTypeSpecifierID(DS);
     }
   }
 
   return TagD;
 }
 
 /// We are trying to inject an anonymous member into the given scope;
 /// check if there's an existing declaration that can't be overloaded.
 ///
 /// \return true if this is a forbidden redeclaration
 static bool CheckAnonMemberRedeclaration(Sema &SemaRef,
                                          Scope *S,
                                          DeclContext *Owner,
                                          DeclarationName Name,
                                          SourceLocation NameLoc,
                                          bool IsUnion) {
   LookupResult R(SemaRef, Name, NameLoc, Sema::LookupMemberName,
                  Sema::ForVisibleRedeclaration);
   if (!SemaRef.LookupName(R, S)) return false;
 
   // Pick a representative declaration.
   NamedDecl *PrevDecl = R.getRepresentativeDecl()->getUnderlyingDecl();
   assert(PrevDecl && "Expected a non-null Decl");
 
   if (!SemaRef.isDeclInScope(PrevDecl, Owner, S))
     return false;
 
   SemaRef.Diag(NameLoc, diag::err_anonymous_record_member_redecl)
     << IsUnion << Name;
   SemaRef.Diag(PrevDecl->getLocation(), diag::note_previous_declaration);
 
   return true;
 }
 
 /// InjectAnonymousStructOrUnionMembers - Inject the members of the
 /// anonymous struct or union AnonRecord into the owning context Owner
 /// and scope S. This routine will be invoked just after we realize
 /// that an unnamed union or struct is actually an anonymous union or
 /// struct, e.g.,
 ///
 /// @code
 /// union {
 ///   int i;
 ///   float f;
 /// }; // InjectAnonymousStructOrUnionMembers called here to inject i and
 ///    // f into the surrounding scope.x
 /// @endcode
 ///
 /// This routine is recursive, injecting the names of nested anonymous
 /// structs/unions into the owning context and scope as well.
 static bool
 InjectAnonymousStructOrUnionMembers(Sema &SemaRef, Scope *S, DeclContext *Owner,
                                     RecordDecl *AnonRecord, AccessSpecifier AS,
                                     SmallVectorImpl<NamedDecl *> &Chaining) {
   bool Invalid = false;
 
   // Look every FieldDecl and IndirectFieldDecl with a name.
   for (auto *D : AnonRecord->decls()) {
     if ((isa<FieldDecl>(D) || isa<IndirectFieldDecl>(D)) &&
         cast<NamedDecl>(D)->getDeclName()) {
       ValueDecl *VD = cast<ValueDecl>(D);
       if (CheckAnonMemberRedeclaration(SemaRef, S, Owner, VD->getDeclName(),
                                        VD->getLocation(),
                                        AnonRecord->isUnion())) {
         // C++ [class.union]p2:
         //   The names of the members of an anonymous union shall be
         //   distinct from the names of any other entity in the
         //   scope in which the anonymous union is declared.
         Invalid = true;
       } else {
         // C++ [class.union]p2:
         //   For the purpose of name lookup, after the anonymous union
         //   definition, the members of the anonymous union are
         //   considered to have been defined in the scope in which the
         //   anonymous union is declared.
         unsigned OldChainingSize = Chaining.size();
         if (IndirectFieldDecl *IF = dyn_cast<IndirectFieldDecl>(VD))
           Chaining.append(IF->chain_begin(), IF->chain_end());
         else
           Chaining.push_back(VD);
 
         assert(Chaining.size() >= 2);
         NamedDecl **NamedChain =
           new (SemaRef.Context)NamedDecl*[Chaining.size()];
         for (unsigned i = 0; i < Chaining.size(); i++)
           NamedChain[i] = Chaining[i];
 
         IndirectFieldDecl *IndirectField = IndirectFieldDecl::Create(
             SemaRef.Context, Owner, VD->getLocation(), VD->getIdentifier(),
             VD->getType(), {NamedChain, Chaining.size()});
 
         for (const auto *Attr : VD->attrs())
           IndirectField->addAttr(Attr->clone(SemaRef.Context));
 
         IndirectField->setAccess(AS);
         IndirectField->setImplicit();
         SemaRef.PushOnScopeChains(IndirectField, S);
 
         // That includes picking up the appropriate access specifier.
         if (AS != AS_none) IndirectField->setAccess(AS);
 
         Chaining.resize(OldChainingSize);
       }
     }
   }
 
   return Invalid;
 }
 
 /// StorageClassSpecToVarDeclStorageClass - Maps a DeclSpec::SCS to
 /// a VarDecl::StorageClass. Any error reporting is up to the caller:
 /// illegal input values are mapped to SC_None.
 static StorageClass
 StorageClassSpecToVarDeclStorageClass(const DeclSpec &DS) {
   DeclSpec::SCS StorageClassSpec = DS.getStorageClassSpec();
   assert(StorageClassSpec != DeclSpec::SCS_typedef &&
          "Parser allowed 'typedef' as storage class VarDecl.");
   switch (StorageClassSpec) {
   case DeclSpec::SCS_unspecified:    return SC_None;
   case DeclSpec::SCS_extern:
     if (DS.isExternInLinkageSpec())
       return SC_None;
     return SC_Extern;
   case DeclSpec::SCS_static:         return SC_Static;
   case DeclSpec::SCS_auto:           return SC_Auto;
   case DeclSpec::SCS_register:       return SC_Register;
   case DeclSpec::SCS_private_extern: return SC_PrivateExtern;
     // Illegal SCSs map to None: error reporting is up to the caller.
   case DeclSpec::SCS_mutable:        // Fall through.
   case DeclSpec::SCS_typedef:        return SC_None;
   }
   llvm_unreachable("unknown storage class specifier");
 }
 
 static SourceLocation findDefaultInitializer(const CXXRecordDecl *Record) {
   assert(Record->hasInClassInitializer());
 
   for (const auto *I : Record->decls()) {
     const auto *FD = dyn_cast<FieldDecl>(I);
     if (const auto *IFD = dyn_cast<IndirectFieldDecl>(I))
       FD = IFD->getAnonField();
     if (FD && FD->hasInClassInitializer())
       return FD->getLocation();
   }
 
   llvm_unreachable("couldn't find in-class initializer");
 }
 
 static void checkDuplicateDefaultInit(Sema &S, CXXRecordDecl *Parent,
                                       SourceLocation DefaultInitLoc) {
   if (!Parent->isUnion() || !Parent->hasInClassInitializer())
     return;
 
   S.Diag(DefaultInitLoc, diag::err_multiple_mem_union_initialization);
   S.Diag(findDefaultInitializer(Parent), diag::note_previous_initializer) << 0;
 }
 
 static void checkDuplicateDefaultInit(Sema &S, CXXRecordDecl *Parent,
                                       CXXRecordDecl *AnonUnion) {
   if (!Parent->isUnion() || !Parent->hasInClassInitializer())
     return;
 
   checkDuplicateDefaultInit(S, Parent, findDefaultInitializer(AnonUnion));
 }
 
 /// BuildAnonymousStructOrUnion - Handle the declaration of an
 /// anonymous structure or union. Anonymous unions are a C++ feature
 /// (C++ [class.union]) and a C11 feature; anonymous structures
 /// are a C11 feature and GNU C++ extension.
 Decl *Sema::BuildAnonymousStructOrUnion(Scope *S, DeclSpec &DS,
                                         AccessSpecifier AS,
                                         RecordDecl *Record,
                                         const PrintingPolicy &Policy) {
   DeclContext *Owner = Record->getDeclContext();
 
   // Diagnose whether this anonymous struct/union is an extension.
   if (Record->isUnion() && !getLangOpts().CPlusPlus && !getLangOpts().C11)
     Diag(Record->getLocation(), diag::ext_anonymous_union);
   else if (!Record->isUnion() && getLangOpts().CPlusPlus)
     Diag(Record->getLocation(), diag::ext_gnu_anonymous_struct);
   else if (!Record->isUnion() && !getLangOpts().C11)
     Diag(Record->getLocation(), diag::ext_c11_anonymous_struct);
 
   // C and C++ require different kinds of checks for anonymous
   // structs/unions.
   bool Invalid = false;
   if (getLangOpts().CPlusPlus) {
     const char *PrevSpec = nullptr;
     if (Record->isUnion()) {
       // C++ [class.union]p6:
       // C++17 [class.union.anon]p2:
       //   Anonymous unions declared in a named namespace or in the
       //   global namespace shall be declared static.
       unsigned DiagID;
       DeclContext *OwnerScope = Owner->getRedeclContext();
       if (DS.getStorageClassSpec() != DeclSpec::SCS_static &&
           (OwnerScope->isTranslationUnit() ||
            (OwnerScope->isNamespace() &&
             !cast<NamespaceDecl>(OwnerScope)->isAnonymousNamespace()))) {
         Diag(Record->getLocation(), diag::err_anonymous_union_not_static)
           << FixItHint::CreateInsertion(Record->getLocation(), "static ");
 
         // Recover by adding 'static'.
         DS.SetStorageClassSpec(*this, DeclSpec::SCS_static, SourceLocation(),
                                PrevSpec, DiagID, Policy);
       }
       // C++ [class.union]p6:
       //   A storage class is not allowed in a declaration of an
       //   anonymous union in a class scope.
       else if (DS.getStorageClassSpec() != DeclSpec::SCS_unspecified &&
                isa<RecordDecl>(Owner)) {
         Diag(DS.getStorageClassSpecLoc(),
              diag::err_anonymous_union_with_storage_spec)
           << FixItHint::CreateRemoval(DS.getStorageClassSpecLoc());
 
         // Recover by removing the storage specifier.
         DS.SetStorageClassSpec(*this, DeclSpec::SCS_unspecified,
                                SourceLocation(),
                                PrevSpec, DiagID, Context.getPrintingPolicy());
       }
     }
 
     // Ignore const/volatile/restrict qualifiers.
     if (DS.getTypeQualifiers()) {
       if (DS.getTypeQualifiers() & DeclSpec::TQ_const)
         Diag(DS.getConstSpecLoc(), diag::ext_anonymous_struct_union_qualified)
           << Record->isUnion() << "const"
           << FixItHint::CreateRemoval(DS.getConstSpecLoc());
       if (DS.getTypeQualifiers() & DeclSpec::TQ_volatile)
         Diag(DS.getVolatileSpecLoc(),
              diag::ext_anonymous_struct_union_qualified)
           << Record->isUnion() << "volatile"
           << FixItHint::CreateRemoval(DS.getVolatileSpecLoc());
       if (DS.getTypeQualifiers() & DeclSpec::TQ_restrict)
         Diag(DS.getRestrictSpecLoc(),
              diag::ext_anonymous_struct_union_qualified)
           << Record->isUnion() << "restrict"
           << FixItHint::CreateRemoval(DS.getRestrictSpecLoc());
       if (DS.getTypeQualifiers() & DeclSpec::TQ_atomic)
         Diag(DS.getAtomicSpecLoc(),
              diag::ext_anonymous_struct_union_qualified)
           << Record->isUnion() << "_Atomic"
           << FixItHint::CreateRemoval(DS.getAtomicSpecLoc());
       if (DS.getTypeQualifiers() & DeclSpec::TQ_unaligned)
         Diag(DS.getUnalignedSpecLoc(),
              diag::ext_anonymous_struct_union_qualified)
           << Record->isUnion() << "__unaligned"
           << FixItHint::CreateRemoval(DS.getUnalignedSpecLoc());
 
       DS.ClearTypeQualifiers();
     }
 
     // C++ [class.union]p2:
     //   The member-specification of an anonymous union shall only
     //   define non-static data members. [Note: nested types and
     //   functions cannot be declared within an anonymous union. ]
     for (auto *Mem : Record->decls()) {
       // Ignore invalid declarations; we already diagnosed them.
       if (Mem->isInvalidDecl())
         continue;
 
       if (auto *FD = dyn_cast<FieldDecl>(Mem)) {
         // C++ [class.union]p3:
         //   An anonymous union shall not have private or protected
         //   members (clause 11).
         assert(FD->getAccess() != AS_none);
         if (FD->getAccess() != AS_public) {
           Diag(FD->getLocation(), diag::err_anonymous_record_nonpublic_member)
             << Record->isUnion() << (FD->getAccess() == AS_protected);
           Invalid = true;
         }
 
         // C++ [class.union]p1
         //   An object of a class with a non-trivial constructor, a non-trivial
         //   copy constructor, a non-trivial destructor, or a non-trivial copy
         //   assignment operator cannot be a member of a union, nor can an
         //   array of such objects.
         if (CheckNontrivialField(FD))
           Invalid = true;
       } else if (Mem->isImplicit()) {
         // Any implicit members are fine.
       } else if (isa<TagDecl>(Mem) && Mem->getDeclContext() != Record) {
         // This is a type that showed up in an
         // elaborated-type-specifier inside the anonymous struct or
         // union, but which actually declares a type outside of the
         // anonymous struct or union. It's okay.
       } else if (auto *MemRecord = dyn_cast<RecordDecl>(Mem)) {
         if (!MemRecord->isAnonymousStructOrUnion() &&
             MemRecord->getDeclName()) {
           // Visual C++ allows type definition in anonymous struct or union.
           if (getLangOpts().MicrosoftExt)
             Diag(MemRecord->getLocation(), diag::ext_anonymous_record_with_type)
               << Record->isUnion();
           else {
             // This is a nested type declaration.
             Diag(MemRecord->getLocation(), diag::err_anonymous_record_with_type)
               << Record->isUnion();
             Invalid = true;
           }
         } else {
           // This is an anonymous type definition within another anonymous type.
           // This is a popular extension, provided by Plan9, MSVC and GCC, but
           // not part of standard C++.
           Diag(MemRecord->getLocation(),
                diag::ext_anonymous_record_with_anonymous_type)
             << Record->isUnion();
         }
       } else if (isa<AccessSpecDecl>(Mem)) {
         // Any access specifier is fine.
       } else if (isa<StaticAssertDecl>(Mem)) {
         // In C++1z, static_assert declarations are also fine.
       } else {
         // We have something that isn't a non-static data
         // member. Complain about it.
         unsigned DK = diag::err_anonymous_record_bad_member;
         if (isa<TypeDecl>(Mem))
           DK = diag::err_anonymous_record_with_type;
         else if (isa<FunctionDecl>(Mem))
           DK = diag::err_anonymous_record_with_function;
         else if (isa<VarDecl>(Mem))
           DK = diag::err_anonymous_record_with_static;
 
         // Visual C++ allows type definition in anonymous struct or union.
         if (getLangOpts().MicrosoftExt &&
             DK == diag::err_anonymous_record_with_type)
           Diag(Mem->getLocation(), diag::ext_anonymous_record_with_type)
             << Record->isUnion();
         else {
           Diag(Mem->getLocation(), DK) << Record->isUnion();
           Invalid = true;
         }
       }
     }
 
     // C++11 [class.union]p8 (DR1460):
     //   At most one variant member of a union may have a
     //   brace-or-equal-initializer.
     if (cast<CXXRecordDecl>(Record)->hasInClassInitializer() &&
         Owner->isRecord())
       checkDuplicateDefaultInit(*this, cast<CXXRecordDecl>(Owner),
                                 cast<CXXRecordDecl>(Record));
   }
 
   if (!Record->isUnion() && !Owner->isRecord()) {
     Diag(Record->getLocation(), diag::err_anonymous_struct_not_member)
       << getLangOpts().CPlusPlus;
     Invalid = true;
   }
 
   // C++ [dcl.dcl]p3:
   //   [If there are no declarators], and except for the declaration of an
   //   unnamed bit-field, the decl-specifier-seq shall introduce one or more
   //   names into the program
   // C++ [class.mem]p2:
   //   each such member-declaration shall either declare at least one member
   //   name of the class or declare at least one unnamed bit-field
   //
   // For C this is an error even for a named struct, and is diagnosed elsewhere.
   if (getLangOpts().CPlusPlus && Record->field_empty())
     Diag(DS.getBeginLoc(), diag::ext_no_declarators) << DS.getSourceRange();
 
   // Mock up a declarator.
   Declarator Dc(DS, ParsedAttributesView::none(), DeclaratorContext::Member);
   TypeSourceInfo *TInfo = GetTypeForDeclarator(Dc, S);
   assert(TInfo && "couldn't build declarator info for anonymous struct/union");
 
   // Create a declaration for this anonymous struct/union.
   NamedDecl *Anon = nullptr;
   if (RecordDecl *OwningClass = dyn_cast<RecordDecl>(Owner)) {
     Anon = FieldDecl::Create(
         Context, OwningClass, DS.getBeginLoc(), Record->getLocation(),
         /*IdentifierInfo=*/nullptr, Context.getTypeDeclType(Record), TInfo,
         /*BitWidth=*/nullptr, /*Mutable=*/false,
         /*InitStyle=*/ICIS_NoInit);
     Anon->setAccess(AS);
     ProcessDeclAttributes(S, Anon, Dc);
 
     if (getLangOpts().CPlusPlus)
       FieldCollector->Add(cast<FieldDecl>(Anon));
   } else {
     DeclSpec::SCS SCSpec = DS.getStorageClassSpec();
     StorageClass SC = StorageClassSpecToVarDeclStorageClass(DS);
     if (SCSpec == DeclSpec::SCS_mutable) {
       // mutable can only appear on non-static class members, so it's always
       // an error here
       Diag(Record->getLocation(), diag::err_mutable_nonmember);
       Invalid = true;
       SC = SC_None;
     }
 
     Anon = VarDecl::Create(Context, Owner, DS.getBeginLoc(),
                            Record->getLocation(), /*IdentifierInfo=*/nullptr,
                            Context.getTypeDeclType(Record), TInfo, SC);
     ProcessDeclAttributes(S, Anon, Dc);
 
     // Default-initialize the implicit variable. This initialization will be
     // trivial in almost all cases, except if a union member has an in-class
     // initializer:
     //   union { int n = 0; };
     ActOnUninitializedDecl(Anon);
   }
   Anon->setImplicit();
 
   // Mark this as an anonymous struct/union type.
   Record->setAnonymousStructOrUnion(true);
 
   // Add the anonymous struct/union object to the current
   // context. We'll be referencing this object when we refer to one of
   // its members.
   Owner->addDecl(Anon);
 
   // Inject the members of the anonymous struct/union into the owning
   // context and into the identifier resolver chain for name lookup
   // purposes.
   SmallVector<NamedDecl*, 2> Chain;
   Chain.push_back(Anon);
 
   if (InjectAnonymousStructOrUnionMembers(*this, S, Owner, Record, AS, Chain))
     Invalid = true;
 
   if (VarDecl *NewVD = dyn_cast<VarDecl>(Anon)) {
     if (getLangOpts().CPlusPlus && NewVD->isStaticLocal()) {
       MangleNumberingContext *MCtx;
       Decl *ManglingContextDecl;
       std::tie(MCtx, ManglingContextDecl) =
           getCurrentMangleNumberContext(NewVD->getDeclContext());
       if (MCtx) {
         Context.setManglingNumber(
             NewVD, MCtx->getManglingNumber(
                        NewVD, getMSManglingNumber(getLangOpts(), S)));
         Context.setStaticLocalNumber(NewVD, MCtx->getStaticLocalNumber(NewVD));
       }
     }
   }
 
   if (Invalid)
     Anon->setInvalidDecl();
 
   return Anon;
 }
 
 /// BuildMicrosoftCAnonymousStruct - Handle the declaration of an
 /// Microsoft C anonymous structure.
 /// Ref: http://msdn.microsoft.com/en-us/library/z2cx9y4f.aspx
 /// Example:
 ///
 /// struct A { int a; };
 /// struct B { struct A; int b; };
 ///
 /// void foo() {
 ///   B var;
 ///   var.a = 3;
 /// }
 ///
 Decl *Sema::BuildMicrosoftCAnonymousStruct(Scope *S, DeclSpec &DS,
                                            RecordDecl *Record) {
   assert(Record && "expected a record!");
 
   // Mock up a declarator.
   Declarator Dc(DS, ParsedAttributesView::none(), DeclaratorContext::TypeName);
   TypeSourceInfo *TInfo = GetTypeForDeclarator(Dc, S);
   assert(TInfo && "couldn't build declarator info for anonymous struct");
 
   auto *ParentDecl = cast<RecordDecl>(CurContext);
   QualType RecTy = Context.getTypeDeclType(Record);
 
   // Create a declaration for this anonymous struct.
   NamedDecl *Anon =
       FieldDecl::Create(Context, ParentDecl, DS.getBeginLoc(), DS.getBeginLoc(),
                         /*IdentifierInfo=*/nullptr, RecTy, TInfo,
                         /*BitWidth=*/nullptr, /*Mutable=*/false,
                         /*InitStyle=*/ICIS_NoInit);
   Anon->setImplicit();
 
   // Add the anonymous struct object to the current context.
   CurContext->addDecl(Anon);
 
   // Inject the members of the anonymous struct into the current
   // context and into the identifier resolver chain for name lookup
   // purposes.
   SmallVector<NamedDecl*, 2> Chain;
   Chain.push_back(Anon);
 
   RecordDecl *RecordDef = Record->getDefinition();
   if (RequireCompleteSizedType(Anon->getLocation(), RecTy,
                                diag::err_field_incomplete_or_sizeless) ||
       InjectAnonymousStructOrUnionMembers(*this, S, CurContext, RecordDef,
                                           AS_none, Chain)) {
     Anon->setInvalidDecl();
     ParentDecl->setInvalidDecl();
   }
 
   return Anon;
 }
 
 /// GetNameForDeclarator - Determine the full declaration name for the
 /// given Declarator.
 DeclarationNameInfo Sema::GetNameForDeclarator(Declarator &D) {
   return GetNameFromUnqualifiedId(D.getName());
 }
 
 /// Retrieves the declaration name from a parsed unqualified-id.
 DeclarationNameInfo
 Sema::GetNameFromUnqualifiedId(const UnqualifiedId &Name) {
   DeclarationNameInfo NameInfo;
   NameInfo.setLoc(Name.StartLocation);
 
   switch (Name.getKind()) {
 
   case UnqualifiedIdKind::IK_ImplicitSelfParam:
   case UnqualifiedIdKind::IK_Identifier:
     NameInfo.setName(Name.Identifier);
     return NameInfo;
 
   case UnqualifiedIdKind::IK_DeductionGuideName: {
     // C++ [temp.deduct.guide]p3:
     //   The simple-template-id shall name a class template specialization.
     //   The template-name shall be the same identifier as the template-name
     //   of the simple-template-id.
     // These together intend to imply that the template-name shall name a
     // class template.
     // FIXME: template<typename T> struct X {};
     //        template<typename T> using Y = X<T>;
     //        Y(int) -> Y<int>;
     //   satisfies these rules but does not name a class template.
     TemplateName TN = Name.TemplateName.get().get();
     auto *Template = TN.getAsTemplateDecl();
     if (!Template || !isa<ClassTemplateDecl>(Template)) {
       Diag(Name.StartLocation,
            diag::err_deduction_guide_name_not_class_template)
         << (int)getTemplateNameKindForDiagnostics(TN) << TN;
       if (Template)
         Diag(Template->getLocation(), diag::note_template_decl_here);
       return DeclarationNameInfo();
     }
 
     NameInfo.setName(
         Context.DeclarationNames.getCXXDeductionGuideName(Template));
     return NameInfo;
   }
 
   case UnqualifiedIdKind::IK_OperatorFunctionId:
     NameInfo.setName(Context.DeclarationNames.getCXXOperatorName(
                                            Name.OperatorFunctionId.Operator));
     NameInfo.setCXXOperatorNameRange(SourceRange(
         Name.OperatorFunctionId.SymbolLocations[0], Name.EndLocation));
     return NameInfo;
 
   case UnqualifiedIdKind::IK_LiteralOperatorId:
     NameInfo.setName(Context.DeclarationNames.getCXXLiteralOperatorName(
                                                            Name.Identifier));
     NameInfo.setCXXLiteralOperatorNameLoc(Name.EndLocation);
     return NameInfo;
 
   case UnqualifiedIdKind::IK_ConversionFunctionId: {
     TypeSourceInfo *TInfo;
     QualType Ty = GetTypeFromParser(Name.ConversionFunctionId, &TInfo);
     if (Ty.isNull())
       return DeclarationNameInfo();
     NameInfo.setName(Context.DeclarationNames.getCXXConversionFunctionName(
                                                Context.getCanonicalType(Ty)));
     NameInfo.setNamedTypeInfo(TInfo);
     return NameInfo;
   }
 
   case UnqualifiedIdKind::IK_ConstructorName: {
     TypeSourceInfo *TInfo;
     QualType Ty = GetTypeFromParser(Name.ConstructorName, &TInfo);
     if (Ty.isNull())
       return DeclarationNameInfo();
     NameInfo.setName(Context.DeclarationNames.getCXXConstructorName(
                                               Context.getCanonicalType(Ty)));
     NameInfo.setNamedTypeInfo(TInfo);
     return NameInfo;
   }
 
   case UnqualifiedIdKind::IK_ConstructorTemplateId: {
     // In well-formed code, we can only have a constructor
     // template-id that refers to the current context, so go there
     // to find the actual type being constructed.
     CXXRecordDecl *CurClass = dyn_cast<CXXRecordDecl>(CurContext);
     if (!CurClass || CurClass->getIdentifier() != Name.TemplateId->Name)
       return DeclarationNameInfo();
 
     // Determine the type of the class being constructed.
     QualType CurClassType = Context.getTypeDeclType(CurClass);
 
     // FIXME: Check two things: that the template-id names the same type as
     // CurClassType, and that the template-id does not occur when the name
     // was qualified.
 
     NameInfo.setName(Context.DeclarationNames.getCXXConstructorName(
                                     Context.getCanonicalType(CurClassType)));
     // FIXME: should we retrieve TypeSourceInfo?
     NameInfo.setNamedTypeInfo(nullptr);
     return NameInfo;
   }
 
   case UnqualifiedIdKind::IK_DestructorName: {
     TypeSourceInfo *TInfo;
     QualType Ty = GetTypeFromParser(Name.DestructorName, &TInfo);
     if (Ty.isNull())
       return DeclarationNameInfo();
     NameInfo.setName(Context.DeclarationNames.getCXXDestructorName(
                                               Context.getCanonicalType(Ty)));
     NameInfo.setNamedTypeInfo(TInfo);
     return NameInfo;
   }
 
   case UnqualifiedIdKind::IK_TemplateId: {
     TemplateName TName = Name.TemplateId->Template.get();
     SourceLocation TNameLoc = Name.TemplateId->TemplateNameLoc;
     return Context.getNameForTemplate(TName, TNameLoc);
   }
 
   } // switch (Name.getKind())
 
   llvm_unreachable("Unknown name kind");
 }
 
 static QualType getCoreType(QualType Ty) {
   do {
     if (Ty->isPointerType() || Ty->isReferenceType())
       Ty = Ty->getPointeeType();
     else if (Ty->isArrayType())
       Ty = Ty->castAsArrayTypeUnsafe()->getElementType();
     else
       return Ty.withoutLocalFastQualifiers();
   } while (true);
 }
 
 /// hasSimilarParameters - Determine whether the C++ functions Declaration
 /// and Definition have "nearly" matching parameters. This heuristic is
 /// used to improve diagnostics in the case where an out-of-line function
 /// definition doesn't match any declaration within the class or namespace.
 /// Also sets Params to the list of indices to the parameters that differ
 /// between the declaration and the definition. If hasSimilarParameters
 /// returns true and Params is empty, then all of the parameters match.
 static bool hasSimilarParameters(ASTContext &Context,
                                      FunctionDecl *Declaration,
                                      FunctionDecl *Definition,
                                      SmallVectorImpl<unsigned> &Params) {
   Params.clear();
   if (Declaration->param_size() != Definition->param_size())
     return false;
   for (unsigned Idx = 0; Idx < Declaration->param_size(); ++Idx) {
     QualType DeclParamTy = Declaration->getParamDecl(Idx)->getType();
     QualType DefParamTy = Definition->getParamDecl(Idx)->getType();
 
     // The parameter types are identical
     if (Context.hasSameUnqualifiedType(DefParamTy, DeclParamTy))
       continue;
 
     QualType DeclParamBaseTy = getCoreType(DeclParamTy);
     QualType DefParamBaseTy = getCoreType(DefParamTy);
     const IdentifierInfo *DeclTyName = DeclParamBaseTy.getBaseTypeIdentifier();
     const IdentifierInfo *DefTyName = DefParamBaseTy.getBaseTypeIdentifier();
 
     if (Context.hasSameUnqualifiedType(DeclParamBaseTy, DefParamBaseTy) ||
         (DeclTyName && DeclTyName == DefTyName))
       Params.push_back(Idx);
     else  // The two parameters aren't even close
       return false;
   }
 
   return true;
 }
 
 /// RebuildDeclaratorInCurrentInstantiation - Checks whether the given
 /// declarator needs to be rebuilt in the current instantiation.
 /// Any bits of declarator which appear before the name are valid for
 /// consideration here.  That's specifically the type in the decl spec
 /// and the base type in any member-pointer chunks.
 static bool RebuildDeclaratorInCurrentInstantiation(Sema &S, Declarator &D,
                                                     DeclarationName Name) {
   // The types we specifically need to rebuild are:
   //   - typenames, typeofs, and decltypes
   //   - types which will become injected class names
   // Of course, we also need to rebuild any type referencing such a
   // type.  It's safest to just say "dependent", but we call out a
   // few cases here.
 
   DeclSpec &DS = D.getMutableDeclSpec();
   switch (DS.getTypeSpecType()) {
   case DeclSpec::TST_typename:
   case DeclSpec::TST_typeofType:
   case DeclSpec::TST_typeof_unqualType:
 #define TRANSFORM_TYPE_TRAIT_DEF(_, Trait) case DeclSpec::TST_##Trait:
 #include "clang/Basic/TransformTypeTraits.def"
   case DeclSpec::TST_atomic: {
     // Grab the type from the parser.
     TypeSourceInfo *TSI = nullptr;
     QualType T = S.GetTypeFromParser(DS.getRepAsType(), &TSI);
     if (T.isNull() || !T->isInstantiationDependentType()) break;
 
     // Make sure there's a type source info.  This isn't really much
     // of a waste; most dependent types should have type source info
     // attached already.
     if (!TSI)
       TSI = S.Context.getTrivialTypeSourceInfo(T, DS.getTypeSpecTypeLoc());
 
     // Rebuild the type in the current instantiation.
     TSI = S.RebuildTypeInCurrentInstantiation(TSI, D.getIdentifierLoc(), Name);
     if (!TSI) return true;
 
     // Store the new type back in the decl spec.
     ParsedType LocType = S.CreateParsedType(TSI->getType(), TSI);
     DS.UpdateTypeRep(LocType);
     break;
   }
 
   case DeclSpec::TST_decltype:
   case DeclSpec::TST_typeof_unqualExpr:
   case DeclSpec::TST_typeofExpr: {
     Expr *E = DS.getRepAsExpr();
     ExprResult Result = S.RebuildExprInCurrentInstantiation(E);
     if (Result.isInvalid()) return true;
     DS.UpdateExprRep(Result.get());
     break;
   }
 
   default:
     // Nothing to do for these decl specs.
     break;
   }
 
   // It doesn't matter what order we do this in.
   for (unsigned I = 0, E = D.getNumTypeObjects(); I != E; ++I) {
     DeclaratorChunk &Chunk = D.getTypeObject(I);
 
     // The only type information in the declarator which can come
     // before the declaration name is the base type of a member
     // pointer.
     if (Chunk.Kind != DeclaratorChunk::MemberPointer)
       continue;
 
     // Rebuild the scope specifier in-place.
     CXXScopeSpec &SS = Chunk.Mem.Scope();
     if (S.RebuildNestedNameSpecifierInCurrentInstantiation(SS))
       return true;
   }
 
   return false;
 }
 
 /// Returns true if the declaration is declared in a system header or from a
 /// system macro.
 static bool isFromSystemHeader(SourceManager &SM, const Decl *D) {
   return SM.isInSystemHeader(D->getLocation()) ||
          SM.isInSystemMacro(D->getLocation());
 }
 
 void Sema::warnOnReservedIdentifier(const NamedDecl *D) {
   // Avoid warning twice on the same identifier, and don't warn on redeclaration
   // of system decl.
   if (D->getPreviousDecl() || D->isImplicit())
     return;
   ReservedIdentifierStatus Status = D->isReserved(getLangOpts());
   if (Status != ReservedIdentifierStatus::NotReserved &&
       !isFromSystemHeader(Context.getSourceManager(), D)) {
     Diag(D->getLocation(), diag::warn_reserved_extern_symbol)
         << D << static_cast<int>(Status);
   }
 }
 
 Decl *Sema::ActOnDeclarator(Scope *S, Declarator &D) {
   D.setFunctionDefinitionKind(FunctionDefinitionKind::Declaration);
 
   // Check if we are in an `omp begin/end declare variant` scope. Handle this
   // declaration only if the `bind_to_declaration` extension is set.
   SmallVector<FunctionDecl *, 4> Bases;
   if (LangOpts.OpenMP && isInOpenMPDeclareVariantScope())
     if (getOMPTraitInfoForSurroundingScope()->isExtensionActive(llvm::omp::TraitProperty::
               implementation_extension_bind_to_declaration))
     ActOnStartOfFunctionDefinitionInOpenMPDeclareVariantScope(
         S, D, MultiTemplateParamsArg(), Bases);
 
   Decl *Dcl = HandleDeclarator(S, D, MultiTemplateParamsArg());
 
   if (OriginalLexicalContext && OriginalLexicalContext->isObjCContainer() &&
       Dcl && Dcl->getDeclContext()->isFileContext())
     Dcl->setTopLevelDeclInObjCContainer();
 
   if (!Bases.empty())
     ActOnFinishedFunctionDefinitionInOpenMPDeclareVariantScope(Dcl, Bases);
 
   return Dcl;
 }
 
 /// DiagnoseClassNameShadow - Implement C++ [class.mem]p13:
 ///   If T is the name of a class, then each of the following shall have a
 ///   name different from T:
 ///     - every static data member of class T;
 ///     - every member function of class T
 ///     - every member of class T that is itself a type;
 /// \returns true if the declaration name violates these rules.
 bool Sema::DiagnoseClassNameShadow(DeclContext *DC,
                                    DeclarationNameInfo NameInfo) {
   DeclarationName Name = NameInfo.getName();
 
   CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(DC);
   while (Record && Record->isAnonymousStructOrUnion())
     Record = dyn_cast<CXXRecordDecl>(Record->getParent());
   if (Record && Record->getIdentifier() && Record->getDeclName() == Name) {
     Diag(NameInfo.getLoc(), diag::err_member_name_of_class) << Name;
     return true;
   }
 
   return false;
 }
 
 /// Diagnose a declaration whose declarator-id has the given
 /// nested-name-specifier.
 ///
 /// \param SS The nested-name-specifier of the declarator-id.
 ///
 /// \param DC The declaration context to which the nested-name-specifier
 /// resolves.
 ///
 /// \param Name The name of the entity being declared.
 ///
 /// \param Loc The location of the name of the entity being declared.
 ///
 /// \param IsTemplateId Whether the name is a (simple-)template-id, and thus
 /// we're declaring an explicit / partial specialization / instantiation.
 ///
 /// \returns true if we cannot safely recover from this error, false otherwise.
 bool Sema::diagnoseQualifiedDeclaration(CXXScopeSpec &SS, DeclContext *DC,
                                         DeclarationName Name,
                                         SourceLocation Loc, bool IsTemplateId) {
   DeclContext *Cur = CurContext;
   while (isa<LinkageSpecDecl>(Cur) || isa<CapturedDecl>(Cur))
     Cur = Cur->getParent();
 
   // If the user provided a superfluous scope specifier that refers back to the
   // class in which the entity is already declared, diagnose and ignore it.
   //
   // class X {
   //   void X::f();
   // };
   //
   // Note, it was once ill-formed to give redundant qualification in all
   // contexts, but that rule was removed by DR482.
   if (Cur->Equals(DC)) {
     if (Cur->isRecord()) {
       Diag(Loc, LangOpts.MicrosoftExt ? diag::warn_member_extra_qualification
                                       : diag::err_member_extra_qualification)
         << Name << FixItHint::CreateRemoval(SS.getRange());
       SS.clear();
     } else {
       Diag(Loc, diag::warn_namespace_member_extra_qualification) << Name;
     }
     return false;
   }
 
   // Check whether the qualifying scope encloses the scope of the original
   // declaration. For a template-id, we perform the checks in
   // CheckTemplateSpecializationScope.
   if (!Cur->Encloses(DC) && !IsTemplateId) {
     if (Cur->isRecord())
       Diag(Loc, diag::err_member_qualification)
         << Name << SS.getRange();
     else if (isa<TranslationUnitDecl>(DC))
       Diag(Loc, diag::err_invalid_declarator_global_scope)
         << Name << SS.getRange();
     else if (isa<FunctionDecl>(Cur))
       Diag(Loc, diag::err_invalid_declarator_in_function)
         << Name << SS.getRange();
     else if (isa<BlockDecl>(Cur))
       Diag(Loc, diag::err_invalid_declarator_in_block)
         << Name << SS.getRange();
     else if (isa<ExportDecl>(Cur)) {
       if (!isa<NamespaceDecl>(DC))
         Diag(Loc, diag::err_export_non_namespace_scope_name)
             << Name << SS.getRange();
       else
         // The cases that DC is not NamespaceDecl should be handled in
         // CheckRedeclarationExported.
         return false;
     } else
       Diag(Loc, diag::err_invalid_declarator_scope)
       << Name << cast<NamedDecl>(Cur) << cast<NamedDecl>(DC) << SS.getRange();
 
     return true;
   }
 
   if (Cur->isRecord()) {
     // Cannot qualify members within a class.
     Diag(Loc, diag::err_member_qualification)
       << Name << SS.getRange();
     SS.clear();
 
     // C++ constructors and destructors with incorrect scopes can break
     // our AST invariants by having the wrong underlying types. If
     // that's the case, then drop this declaration entirely.
     if ((Name.getNameKind() == DeclarationName::CXXConstructorName ||
          Name.getNameKind() == DeclarationName::CXXDestructorName) &&
         !Context.hasSameType(Name.getCXXNameType(),
                              Context.getTypeDeclType(cast<CXXRecordDecl>(Cur))))
       return true;
 
     return false;
   }
 
   // C++11 [dcl.meaning]p1:
   //   [...] "The nested-name-specifier of the qualified declarator-id shall
   //   not begin with a decltype-specifer"
   NestedNameSpecifierLoc SpecLoc(SS.getScopeRep(), SS.location_data());
   while (SpecLoc.getPrefix())
     SpecLoc = SpecLoc.getPrefix();
   if (isa_and_nonnull<DecltypeType>(
           SpecLoc.getNestedNameSpecifier()->getAsType()))
     Diag(Loc, diag::err_decltype_in_declarator)
       << SpecLoc.getTypeLoc().getSourceRange();
 
   return false;
 }
 
 NamedDecl *Sema::HandleDeclarator(Scope *S, Declarator &D,
                                   MultiTemplateParamsArg TemplateParamLists) {
   // TODO: consider using NameInfo for diagnostic.
   DeclarationNameInfo NameInfo = GetNameForDeclarator(D);
   DeclarationName Name = NameInfo.getName();
 
   // All of these full declarators require an identifier.  If it doesn't have
   // one, the ParsedFreeStandingDeclSpec action should be used.
   if (D.isDecompositionDeclarator()) {
     return ActOnDecompositionDeclarator(S, D, TemplateParamLists);
   } else if (!Name) {
     if (!D.isInvalidType())  // Reject this if we think it is valid.
       Diag(D.getDeclSpec().getBeginLoc(), diag::err_declarator_need_ident)
           << D.getDeclSpec().getSourceRange() << D.getSourceRange();
     return nullptr;
   } else if (DiagnoseUnexpandedParameterPack(NameInfo, UPPC_DeclarationType))
     return nullptr;
 
   // The scope passed in may not be a decl scope.  Zip up the scope tree until
   // we find one that is.
   while ((S->getFlags() & Scope::DeclScope) == 0 ||
          (S->getFlags() & Scope::TemplateParamScope) != 0)
     S = S->getParent();
 
   DeclContext *DC = CurContext;
   if (D.getCXXScopeSpec().isInvalid())
     D.setInvalidType();
   else if (D.getCXXScopeSpec().isSet()) {
     if (DiagnoseUnexpandedParameterPack(D.getCXXScopeSpec(),
                                         UPPC_DeclarationQualifier))
       return nullptr;
 
     bool EnteringContext = !D.getDeclSpec().isFriendSpecified();
     DC = computeDeclContext(D.getCXXScopeSpec(), EnteringContext);
     if (!DC || isa<EnumDecl>(DC)) {
       // If we could not compute the declaration context, it's because the
       // declaration context is dependent but does not refer to a class,
       // class template, or class template partial specialization. Complain
       // and return early, to avoid the coming semantic disaster.
       Diag(D.getIdentifierLoc(),
            diag::err_template_qualified_declarator_no_match)
         << D.getCXXScopeSpec().getScopeRep()
         << D.getCXXScopeSpec().getRange();
       return nullptr;
     }
     bool IsDependentContext = DC->isDependentContext();
 
     if (!IsDependentContext &&
         RequireCompleteDeclContext(D.getCXXScopeSpec(), DC))
       return nullptr;
 
     // If a class is incomplete, do not parse entities inside it.
     if (isa<CXXRecordDecl>(DC) && !cast<CXXRecordDecl>(DC)->hasDefinition()) {
       Diag(D.getIdentifierLoc(),
            diag::err_member_def_undefined_record)
         << Name << DC << D.getCXXScopeSpec().getRange();
       return nullptr;
     }
     if (!D.getDeclSpec().isFriendSpecified()) {
       if (diagnoseQualifiedDeclaration(
               D.getCXXScopeSpec(), DC, Name, D.getIdentifierLoc(),
               D.getName().getKind() == UnqualifiedIdKind::IK_TemplateId)) {
         if (DC->isRecord())
           return nullptr;
 
         D.setInvalidType();
       }
     }
 
     // Check whether we need to rebuild the type of the given
     // declaration in the current instantiation.
     if (EnteringContext && IsDependentContext &&
         TemplateParamLists.size() != 0) {
       ContextRAII SavedContext(*this, DC);
       if (RebuildDeclaratorInCurrentInstantiation(*this, D, Name))
         D.setInvalidType();
     }
   }
 
   TypeSourceInfo *TInfo = GetTypeForDeclarator(D, S);
   QualType R = TInfo->getType();
 
   if (DiagnoseUnexpandedParameterPack(D.getIdentifierLoc(), TInfo,
                                       UPPC_DeclarationType))
     D.setInvalidType();
 
   LookupResult Previous(*this, NameInfo, LookupOrdinaryName,
                         forRedeclarationInCurContext());
 
   // See if this is a redefinition of a variable in the same scope.
   if (!D.getCXXScopeSpec().isSet()) {
     bool IsLinkageLookup = false;
     bool CreateBuiltins = false;
 
     // If the declaration we're planning to build will be a function
     // or object with linkage, then look for another declaration with
     // linkage (C99 6.2.2p4-5 and C++ [basic.link]p6).
     //
     // If the declaration we're planning to build will be declared with
     // external linkage in the translation unit, create any builtin with
     // the same name.
     if (D.getDeclSpec().getStorageClassSpec() == DeclSpec::SCS_typedef)
       /* Do nothing*/;
     else if (CurContext->isFunctionOrMethod() &&
              (D.getDeclSpec().getStorageClassSpec() == DeclSpec::SCS_extern ||
               R->isFunctionType())) {
       IsLinkageLookup = true;
       CreateBuiltins =
           CurContext->getEnclosingNamespaceContext()->isTranslationUnit();
     } else if (CurContext->getRedeclContext()->isTranslationUnit() &&
                D.getDeclSpec().getStorageClassSpec() != DeclSpec::SCS_static)
       CreateBuiltins = true;
 
     if (IsLinkageLookup) {
       Previous.clear(LookupRedeclarationWithLinkage);
       Previous.setRedeclarationKind(ForExternalRedeclaration);
     }
 
     LookupName(Previous, S, CreateBuiltins);
   } else { // Something like "int foo::x;"
     LookupQualifiedName(Previous, DC);
 
     // C++ [dcl.meaning]p1:
     //   When the declarator-id is qualified, the declaration shall refer to a
     //  previously declared member of the class or namespace to which the
     //  qualifier refers (or, in the case of a namespace, of an element of the
     //  inline namespace set of that namespace (7.3.1)) or to a specialization
     //  thereof; [...]
     //
     // Note that we already checked the context above, and that we do not have
     // enough information to make sure that Previous contains the declaration
     // we want to match. For example, given:
     //
     //   class X {
     //     void f();
     //     void f(float);
     //   };
     //
     //   void X::f(int) { } // ill-formed
     //
     // In this case, Previous will point to the overload set
     // containing the two f's declared in X, but neither of them
     // matches.
 
     RemoveUsingDecls(Previous);
   }
 
   if (Previous.isSingleResult() &&
       Previous.getFoundDecl()->isTemplateParameter()) {
     // Maybe we will complain about the shadowed template parameter.
     if (!D.isInvalidType())
       DiagnoseTemplateParameterShadow(D.getIdentifierLoc(),
                                       Previous.getFoundDecl());
 
     // Just pretend that we didn't see the previous declaration.
     Previous.clear();
   }
 
   if (!R->isFunctionType() && DiagnoseClassNameShadow(DC, NameInfo))
     // Forget that the previous declaration is the injected-class-name.
     Previous.clear();
 
   // In C++, the previous declaration we find might be a tag type
   // (class or enum). In this case, the new declaration will hide the
   // tag type. Note that this applies to functions, function templates, and
   // variables, but not to typedefs (C++ [dcl.typedef]p4) or variable templates.
   if (Previous.isSingleTagDecl() &&
       D.getDeclSpec().getStorageClassSpec() != DeclSpec::SCS_typedef &&
       (TemplateParamLists.size() == 0 || R->isFunctionType()))
     Previous.clear();
 
   // Check that there are no default arguments other than in the parameters
   // of a function declaration (C++ only).
   if (getLangOpts().CPlusPlus)
     CheckExtraCXXDefaultArguments(D);
 
   NamedDecl *New;
 
   bool AddToScope = true;
   if (D.getDeclSpec().getStorageClassSpec() == DeclSpec::SCS_typedef) {
     if (TemplateParamLists.size()) {
       Diag(D.getIdentifierLoc(), diag::err_template_typedef);
       return nullptr;
     }
 
     New = ActOnTypedefDeclarator(S, D, DC, TInfo, Previous);
   } else if (R->isFunctionType()) {
     New = ActOnFunctionDeclarator(S, D, DC, TInfo, Previous,
                                   TemplateParamLists,
                                   AddToScope);
   } else {
     New = ActOnVariableDeclarator(S, D, DC, TInfo, Previous, TemplateParamLists,
                                   AddToScope);
   }
 
   if (!New)
     return nullptr;
 
   // If this has an identifier and is not a function template specialization,
   // add it to the scope stack.
   if (New->getDeclName() && AddToScope)
     PushOnScopeChains(New, S);
 
   if (isInOpenMPDeclareTargetContext())
     checkDeclIsAllowedInOpenMPTarget(nullptr, New);
 
   return New;
 }
 
 /// Helper method to turn variable array types into constant array
 /// types in certain situations which would otherwise be errors (for
 /// GCC compatibility).
 static QualType TryToFixInvalidVariablyModifiedType(QualType T,
                                                     ASTContext &Context,
                                                     bool &SizeIsNegative,
                                                     llvm::APSInt &Oversized) {
   // This method tries to turn a variable array into a constant
   // array even when the size isn't an ICE.  This is necessary
   // for compatibility with code that depends on gcc's buggy
   // constant expression folding, like struct {char x[(int)(char*)2];}
   SizeIsNegative = false;
   Oversized = 0;
 
   if (T->isDependentType())
     return QualType();
 
   QualifierCollector Qs;
   const Type *Ty = Qs.strip(T);
 
   if (const PointerType* PTy = dyn_cast<PointerType>(Ty)) {
     QualType Pointee = PTy->getPointeeType();
     QualType FixedType =
         TryToFixInvalidVariablyModifiedType(Pointee, Context, SizeIsNegative,
                                             Oversized);
     if (FixedType.isNull()) return FixedType;
     FixedType = Context.getPointerType(FixedType);
     return Qs.apply(Context, FixedType);
   }
   if (const ParenType* PTy = dyn_cast<ParenType>(Ty)) {
     QualType Inner = PTy->getInnerType();
     QualType FixedType =
         TryToFixInvalidVariablyModifiedType(Inner, Context, SizeIsNegative,
                                             Oversized);
     if (FixedType.isNull()) return FixedType;
     FixedType = Context.getParenType(FixedType);
     return Qs.apply(Context, FixedType);
   }
 
   const VariableArrayType* VLATy = dyn_cast<VariableArrayType>(T);
   if (!VLATy)
     return QualType();
 
   QualType ElemTy = VLATy->getElementType();
   if (ElemTy->isVariablyModifiedType()) {
     ElemTy = TryToFixInvalidVariablyModifiedType(ElemTy, Context,
                                                  SizeIsNegative, Oversized);
     if (ElemTy.isNull())
       return QualType();
   }
 
   Expr::EvalResult Result;
   if (!VLATy->getSizeExpr() ||
       !VLATy->getSizeExpr()->EvaluateAsInt(Result, Context))
     return QualType();
 
   llvm::APSInt Res = Result.Val.getInt();
 
   // Check whether the array size is negative.
   if (Res.isSigned() && Res.isNegative()) {
     SizeIsNegative = true;
     return QualType();
   }
 
   // Check whether the array is too large to be addressed.
   unsigned ActiveSizeBits =
       (!ElemTy->isDependentType() && !ElemTy->isVariablyModifiedType() &&
        !ElemTy->isIncompleteType() && !ElemTy->isUndeducedType())
           ? ConstantArrayType::getNumAddressingBits(Context, ElemTy, Res)
           : Res.getActiveBits();
   if (ActiveSizeBits > ConstantArrayType::getMaxSizeBits(Context)) {
     Oversized = Res;
     return QualType();
   }
 
   QualType FoldedArrayType = Context.getConstantArrayType(
       ElemTy, Res, VLATy->getSizeExpr(), ArrayType::Normal, 0);
   return Qs.apply(Context, FoldedArrayType);
 }
 
 static void
 FixInvalidVariablyModifiedTypeLoc(TypeLoc SrcTL, TypeLoc DstTL) {
   SrcTL = SrcTL.getUnqualifiedLoc();
   DstTL = DstTL.getUnqualifiedLoc();
   if (PointerTypeLoc SrcPTL = SrcTL.getAs<PointerTypeLoc>()) {
     PointerTypeLoc DstPTL = DstTL.castAs<PointerTypeLoc>();
     FixInvalidVariablyModifiedTypeLoc(SrcPTL.getPointeeLoc(),
                                       DstPTL.getPointeeLoc());
     DstPTL.setStarLoc(SrcPTL.getStarLoc());
     return;
   }
   if (ParenTypeLoc SrcPTL = SrcTL.getAs<ParenTypeLoc>()) {
     ParenTypeLoc DstPTL = DstTL.castAs<ParenTypeLoc>();
     FixInvalidVariablyModifiedTypeLoc(SrcPTL.getInnerLoc(),
                                       DstPTL.getInnerLoc());
     DstPTL.setLParenLoc(SrcPTL.getLParenLoc());
     DstPTL.setRParenLoc(SrcPTL.getRParenLoc());
     return;
   }
   ArrayTypeLoc SrcATL = SrcTL.castAs<ArrayTypeLoc>();
   ArrayTypeLoc DstATL = DstTL.castAs<ArrayTypeLoc>();
   TypeLoc SrcElemTL = SrcATL.getElementLoc();
   TypeLoc DstElemTL = DstATL.getElementLoc();
   if (VariableArrayTypeLoc SrcElemATL =
           SrcElemTL.getAs<VariableArrayTypeLoc>()) {
     ConstantArrayTypeLoc DstElemATL = DstElemTL.castAs<ConstantArrayTypeLoc>();
     FixInvalidVariablyModifiedTypeLoc(SrcElemATL, DstElemATL);
   } else {
     DstElemTL.initializeFullCopy(SrcElemTL);
   }
   DstATL.setLBracketLoc(SrcATL.getLBracketLoc());
   DstATL.setSizeExpr(SrcATL.getSizeExpr());
   DstATL.setRBracketLoc(SrcATL.getRBracketLoc());
 }
 
 /// Helper method to turn variable array types into constant array
 /// types in certain situations which would otherwise be errors (for
 /// GCC compatibility).
 static TypeSourceInfo*
 TryToFixInvalidVariablyModifiedTypeSourceInfo(TypeSourceInfo *TInfo,
                                               ASTContext &Context,
                                               bool &SizeIsNegative,
                                               llvm::APSInt &Oversized) {
   QualType FixedTy
     = TryToFixInvalidVariablyModifiedType(TInfo->getType(), Context,
                                           SizeIsNegative, Oversized);
   if (FixedTy.isNull())
     return nullptr;
   TypeSourceInfo *FixedTInfo = Context.getTrivialTypeSourceInfo(FixedTy);
   FixInvalidVariablyModifiedTypeLoc(TInfo->getTypeLoc(),
                                     FixedTInfo->getTypeLoc());
   return FixedTInfo;
 }
 
 /// Attempt to fold a variable-sized type to a constant-sized type, returning
 /// true if we were successful.
 bool Sema::tryToFixVariablyModifiedVarType(TypeSourceInfo *&TInfo,
                                            QualType &T, SourceLocation Loc,
                                            unsigned FailedFoldDiagID) {
   bool SizeIsNegative;
   llvm::APSInt Oversized;
   TypeSourceInfo *FixedTInfo = TryToFixInvalidVariablyModifiedTypeSourceInfo(
       TInfo, Context, SizeIsNegative, Oversized);
   if (FixedTInfo) {
     Diag(Loc, diag::ext_vla_folded_to_constant);
     TInfo = FixedTInfo;
     T = FixedTInfo->getType();
     return true;
   }
 
   if (SizeIsNegative)
     Diag(Loc, diag::err_typecheck_negative_array_size);
   else if (Oversized.getBoolValue())
     Diag(Loc, diag::err_array_too_large) << toString(Oversized, 10);
   else if (FailedFoldDiagID)
     Diag(Loc, FailedFoldDiagID);
   return false;
 }
 
 /// Register the given locally-scoped extern "C" declaration so
 /// that it can be found later for redeclarations. We include any extern "C"
 /// declaration that is not visible in the translation unit here, not just
 /// function-scope declarations.
 void
 Sema::RegisterLocallyScopedExternCDecl(NamedDecl *ND, Scope *S) {
   if (!getLangOpts().CPlusPlus &&
       ND->getLexicalDeclContext()->getRedeclContext()->isTranslationUnit())
     // Don't need to track declarations in the TU in C.
     return;
 
   // Note that we have a locally-scoped external with this name.
   Context.getExternCContextDecl()->makeDeclVisibleInContext(ND);
 }
 
 NamedDecl *Sema::findLocallyScopedExternCDecl(DeclarationName Name) {
   // FIXME: We can have multiple results via __attribute__((overloadable)).
   auto Result = Context.getExternCContextDecl()->lookup(Name);
   return Result.empty() ? nullptr : *Result.begin();
 }
 
 /// Diagnose function specifiers on a declaration of an identifier that
 /// does not identify a function.
 void Sema::DiagnoseFunctionSpecifiers(const DeclSpec &DS) {
   // FIXME: We should probably indicate the identifier in question to avoid
   // confusion for constructs like "virtual int a(), b;"
   if (DS.isVirtualSpecified())
     Diag(DS.getVirtualSpecLoc(),
          diag::err_virtual_non_function);
 
   if (DS.hasExplicitSpecifier())
     Diag(DS.getExplicitSpecLoc(),
          diag::err_explicit_non_function);
 
   if (DS.isNoreturnSpecified())
     Diag(DS.getNoreturnSpecLoc(),
          diag::err_noreturn_non_function);
 }
 
 NamedDecl*
 Sema::ActOnTypedefDeclarator(Scope* S, Declarator& D, DeclContext* DC,
                              TypeSourceInfo *TInfo, LookupResult &Previous) {
   // Typedef declarators cannot be qualified (C++ [dcl.meaning]p1).
   if (D.getCXXScopeSpec().isSet()) {
     Diag(D.getIdentifierLoc(), diag::err_qualified_typedef_declarator)
       << D.getCXXScopeSpec().getRange();
     D.setInvalidType();
     // Pretend we didn't see the scope specifier.
     DC = CurContext;
     Previous.clear();
   }
 
   DiagnoseFunctionSpecifiers(D.getDeclSpec());
 
   if (D.getDeclSpec().isInlineSpecified())
     Diag(D.getDeclSpec().getInlineSpecLoc(), diag::err_inline_non_function)
         << getLangOpts().CPlusPlus17;
   if (D.getDeclSpec().hasConstexprSpecifier())
     Diag(D.getDeclSpec().getConstexprSpecLoc(), diag::err_invalid_constexpr)
         << 1 << static_cast<int>(D.getDeclSpec().getConstexprSpecifier());
 
   if (D.getName().getKind() != UnqualifiedIdKind::IK_Identifier) {
     if (D.getName().getKind() == UnqualifiedIdKind::IK_DeductionGuideName)
       Diag(D.getName().StartLocation,
            diag::err_deduction_guide_invalid_specifier)
           << "typedef";
     else
       Diag(D.getName().StartLocation, diag::err_typedef_not_identifier)
           << D.getName().getSourceRange();
     return nullptr;
   }
 
   TypedefDecl *NewTD = ParseTypedefDecl(S, D, TInfo->getType(), TInfo);
   if (!NewTD) return nullptr;
 
   // Handle attributes prior to checking for duplicates in MergeVarDecl
   ProcessDeclAttributes(S, NewTD, D);
 
   CheckTypedefForVariablyModifiedType(S, NewTD);
 
   bool Redeclaration = D.isRedeclaration();
   NamedDecl *ND = ActOnTypedefNameDecl(S, DC, NewTD, Previous, Redeclaration);
   D.setRedeclaration(Redeclaration);
   return ND;
 }
 
 void
 Sema::CheckTypedefForVariablyModifiedType(Scope *S, TypedefNameDecl *NewTD) {
   // C99 6.7.7p2: If a typedef name specifies a variably modified type
   // then it shall have block scope.
   // Note that variably modified types must be fixed before merging the decl so
   // that redeclarations will match.
   TypeSourceInfo *TInfo = NewTD->getTypeSourceInfo();
   QualType T = TInfo->getType();
   if (T->isVariablyModifiedType()) {
     setFunctionHasBranchProtectedScope();
 
     if (S->getFnParent() == nullptr) {
       bool SizeIsNegative;
       llvm::APSInt Oversized;
       TypeSourceInfo *FixedTInfo =
         TryToFixInvalidVariablyModifiedTypeSourceInfo(TInfo, Context,
                                                       SizeIsNegative,
                                                       Oversized);
       if (FixedTInfo) {
         Diag(NewTD->getLocation(), diag::ext_vla_folded_to_constant);
         NewTD->setTypeSourceInfo(FixedTInfo);
       } else {
         if (SizeIsNegative)
           Diag(NewTD->getLocation(), diag::err_typecheck_negative_array_size);
         else if (T->isVariableArrayType())
           Diag(NewTD->getLocation(), diag::err_vla_decl_in_file_scope);
         else if (Oversized.getBoolValue())
           Diag(NewTD->getLocation(), diag::err_array_too_large)
             << toString(Oversized, 10);
         else
           Diag(NewTD->getLocation(), diag::err_vm_decl_in_file_scope);
         NewTD->setInvalidDecl();
       }
     }
   }
 }
 
 /// ActOnTypedefNameDecl - Perform semantic checking for a declaration which
 /// declares a typedef-name, either using the 'typedef' type specifier or via
 /// a C++0x [dcl.typedef]p2 alias-declaration: 'using T = A;'.
 NamedDecl*
 Sema::ActOnTypedefNameDecl(Scope *S, DeclContext *DC, TypedefNameDecl *NewTD,
                            LookupResult &Previous, bool &Redeclaration) {
 
   // Find the shadowed declaration before filtering for scope.
   NamedDecl *ShadowedDecl = getShadowedDeclaration(NewTD, Previous);
 
   // Merge the decl with the existing one if appropriate. If the decl is
   // in an outer scope, it isn't the same thing.
   FilterLookupForScope(Previous, DC, S, /*ConsiderLinkage*/false,
                        /*AllowInlineNamespace*/false);
   filterNonConflictingPreviousTypedefDecls(*this, NewTD, Previous);
   if (!Previous.empty()) {
     Redeclaration = true;
     MergeTypedefNameDecl(S, NewTD, Previous);
   } else {
     inferGslPointerAttribute(NewTD);
   }
 
   if (ShadowedDecl && !Redeclaration)
     CheckShadow(NewTD, ShadowedDecl, Previous);
 
   // If this is the C FILE type, notify the AST context.
   if (IdentifierInfo *II = NewTD->getIdentifier())
     if (!NewTD->isInvalidDecl() &&
         NewTD->getDeclContext()->getRedeclContext()->isTranslationUnit()) {
       switch (II->getInterestingIdentifierID()) {
       case tok::InterestingIdentifierKind::FILE:
         Context.setFILEDecl(NewTD);
         break;
       case tok::InterestingIdentifierKind::jmp_buf:
         Context.setjmp_bufDecl(NewTD);
         break;
       case tok::InterestingIdentifierKind::sigjmp_buf:
         Context.setsigjmp_bufDecl(NewTD);
         break;
       case tok::InterestingIdentifierKind::ucontext_t:
         Context.setucontext_tDecl(NewTD);
         break;
       case tok::InterestingIdentifierKind::float_t:
       case tok::InterestingIdentifierKind::double_t:
         NewTD->addAttr(AvailableOnlyInDefaultEvalMethodAttr::Create(Context));
         break;
       default:
         break;
       }
     }
 
   return NewTD;
 }
 
 /// Determines whether the given declaration is an out-of-scope
 /// previous declaration.
 ///
 /// This routine should be invoked when name lookup has found a
 /// previous declaration (PrevDecl) that is not in the scope where a
 /// new declaration by the same name is being introduced. If the new
 /// declaration occurs in a local scope, previous declarations with
 /// linkage may still be considered previous declarations (C99
 /// 6.2.2p4-5, C++ [basic.link]p6).
 ///
 /// \param PrevDecl the previous declaration found by name
 /// lookup
 ///
 /// \param DC the context in which the new declaration is being
 /// declared.
 ///
 /// \returns true if PrevDecl is an out-of-scope previous declaration
 /// for a new delcaration with the same name.
 static bool
 isOutOfScopePreviousDeclaration(NamedDecl *PrevDecl, DeclContext *DC,
                                 ASTContext &Context) {
   if (!PrevDecl)
     return false;
 
   if (!PrevDecl->hasLinkage())
     return false;
 
   if (Context.getLangOpts().CPlusPlus) {
     // C++ [basic.link]p6:
     //   If there is a visible declaration of an entity with linkage
     //   having the same name and type, ignoring entities declared
     //   outside the innermost enclosing namespace scope, the block
     //   scope declaration declares that same entity and receives the
     //   linkage of the previous declaration.
     DeclContext *OuterContext = DC->getRedeclContext();
     if (!OuterContext->isFunctionOrMethod())
       // This rule only applies to block-scope declarations.
       return false;
 
     DeclContext *PrevOuterContext = PrevDecl->getDeclContext();
     if (PrevOuterContext->isRecord())
       // We found a member function: ignore it.
       return false;
 
     // Find the innermost enclosing namespace for the new and
     // previous declarations.
     OuterContext = OuterContext->getEnclosingNamespaceContext();
     PrevOuterContext = PrevOuterContext->getEnclosingNamespaceContext();
 
     // The previous declaration is in a different namespace, so it
     // isn't the same function.
     if (!OuterContext->Equals(PrevOuterContext))
       return false;
   }
 
   return true;
 }
 
 static void SetNestedNameSpecifier(Sema &S, DeclaratorDecl *DD, Declarator &D) {
   CXXScopeSpec &SS = D.getCXXScopeSpec();
   if (!SS.isSet()) return;
   DD->setQualifierInfo(SS.getWithLocInContext(S.Context));
 }
 
 bool Sema::inferObjCARCLifetime(ValueDecl *decl) {
   QualType type = decl->getType();
   Qualifiers::ObjCLifetime lifetime = type.getObjCLifetime();
   if (lifetime == Qualifiers::OCL_Autoreleasing) {
     // Various kinds of declaration aren't allowed to be __autoreleasing.
     unsigned kind = -1U;
     if (VarDecl *var = dyn_cast<VarDecl>(decl)) {
       if (var->hasAttr<BlocksAttr>())
         kind = 0; // __block
       else if (!var->hasLocalStorage())
         kind = 1; // global
     } else if (isa<ObjCIvarDecl>(decl)) {
       kind = 3; // ivar
     } else if (isa<FieldDecl>(decl)) {
       kind = 2; // field
     }
 
     if (kind != -1U) {
       Diag(decl->getLocation(), diag::err_arc_autoreleasing_var)
         << kind;
     }
   } else if (lifetime == Qualifiers::OCL_None) {
     // Try to infer lifetime.
     if (!type->isObjCLifetimeType())
       return false;
 
     lifetime = type->getObjCARCImplicitLifetime();
     type = Context.getLifetimeQualifiedType(type, lifetime);
     decl->setType(type);
   }
 
   if (VarDecl *var = dyn_cast<VarDecl>(decl)) {
     // Thread-local variables cannot have lifetime.
     if (lifetime && lifetime != Qualifiers::OCL_ExplicitNone &&
         var->getTLSKind()) {
       Diag(var->getLocation(), diag::err_arc_thread_ownership)
         << var->getType();
       return true;
     }
   }
 
   return false;
 }
 
 void Sema::deduceOpenCLAddressSpace(ValueDecl *Decl) {
   if (Decl->getType().hasAddressSpace())
     return;
   if (Decl->getType()->isDependentType())
     return;
   if (VarDecl *Var = dyn_cast<VarDecl>(Decl)) {
     QualType Type = Var->getType();
     if (Type->isSamplerT() || Type->isVoidType())
       return;
     LangAS ImplAS = LangAS::opencl_private;
     // OpenCL C v3.0 s6.7.8 - For OpenCL C 2.0 or with the
     // __opencl_c_program_scope_global_variables feature, the address space
     // for a variable at program scope or a static or extern variable inside
     // a function are inferred to be __global.
     if (getOpenCLOptions().areProgramScopeVariablesSupported(getLangOpts()) &&
         Var->hasGlobalStorage())
       ImplAS = LangAS::opencl_global;
     // If the original type from a decayed type is an array type and that array
     // type has no address space yet, deduce it now.
     if (auto DT = dyn_cast<DecayedType>(Type)) {
       auto OrigTy = DT->getOriginalType();
       if (!OrigTy.hasAddressSpace() && OrigTy->isArrayType()) {
         // Add the address space to the original array type and then propagate
         // that to the element type through `getAsArrayType`.
         OrigTy = Context.getAddrSpaceQualType(OrigTy, ImplAS);
         OrigTy = QualType(Context.getAsArrayType(OrigTy), 0);
         // Re-generate the decayed type.
         Type = Context.getDecayedType(OrigTy);
       }
     }
     Type = Context.getAddrSpaceQualType(Type, ImplAS);
     // Apply any qualifiers (including address space) from the array type to
     // the element type. This implements C99 6.7.3p8: "If the specification of
     // an array type includes any type qualifiers, the element type is so
     // qualified, not the array type."
     if (Type->isArrayType())
       Type = QualType(Context.getAsArrayType(Type), 0);
     Decl->setType(Type);
   }
 }
 
 static void checkAttributesAfterMerging(Sema &S, NamedDecl &ND) {
   // Ensure that an auto decl is deduced otherwise the checks below might cache
   // the wrong linkage.
   assert(S.ParsingInitForAutoVars.count(&ND) == 0);
 
   // 'weak' only applies to declarations with external linkage.
   if (WeakAttr *Attr = ND.getAttr<WeakAttr>()) {
     if (!ND.isExternallyVisible()) {
       S.Diag(Attr->getLocation(), diag::err_attribute_weak_static);
       ND.dropAttr<WeakAttr>();
     }
   }
   if (WeakRefAttr *Attr = ND.getAttr<WeakRefAttr>()) {
     if (ND.isExternallyVisible()) {
       S.Diag(Attr->getLocation(), diag::err_attribute_weakref_not_static);
       ND.dropAttr<WeakRefAttr>();
       ND.dropAttr<AliasAttr>();
     }
   }
 
   if (auto *VD = dyn_cast<VarDecl>(&ND)) {
     if (VD->hasInit()) {
       if (const auto *Attr = VD->getAttr<AliasAttr>()) {
         assert(VD->isThisDeclarationADefinition() &&
                !VD->isExternallyVisible() && "Broken AliasAttr handled late!");
         S.Diag(Attr->getLocation(), diag::err_alias_is_definition) << VD << 0;
         VD->dropAttr<AliasAttr>();
       }
     }
   }
 
   // 'selectany' only applies to externally visible variable declarations.
   // It does not apply to functions.
   if (SelectAnyAttr *Attr = ND.getAttr<SelectAnyAttr>()) {
     if (isa<FunctionDecl>(ND) || !ND.isExternallyVisible()) {
       S.Diag(Attr->getLocation(),
              diag::err_attribute_selectany_non_extern_data);
       ND.dropAttr<SelectAnyAttr>();
     }
   }
 
   if (const InheritableAttr *Attr = getDLLAttr(&ND)) {
     auto *VD = dyn_cast<VarDecl>(&ND);
     bool IsAnonymousNS = false;
     bool IsMicrosoft = S.Context.getTargetInfo().getCXXABI().isMicrosoft();
     if (VD) {
       const NamespaceDecl *NS = dyn_cast<NamespaceDecl>(VD->getDeclContext());
       while (NS && !IsAnonymousNS) {
         IsAnonymousNS = NS->isAnonymousNamespace();
         NS = dyn_cast<NamespaceDecl>(NS->getParent());
       }
     }
     // dll attributes require external linkage. Static locals may have external
     // linkage but still cannot be explicitly imported or exported.
     // In Microsoft mode, a variable defined in anonymous namespace must have
     // external linkage in order to be exported.
     bool AnonNSInMicrosoftMode = IsAnonymousNS && IsMicrosoft;
     if ((ND.isExternallyVisible() && AnonNSInMicrosoftMode) ||
         (!AnonNSInMicrosoftMode &&
          (!ND.isExternallyVisible() || (VD && VD->isStaticLocal())))) {
       S.Diag(ND.getLocation(), diag::err_attribute_dll_not_extern)
         << &ND << Attr;
       ND.setInvalidDecl();
     }
   }
 
   // Check the attributes on the function type, if any.
   if (const auto *FD = dyn_cast<FunctionDecl>(&ND)) {
     // Don't declare this variable in the second operand of the for-statement;
     // GCC miscompiles that by ending its lifetime before evaluating the
     // third operand. See gcc.gnu.org/PR86769.
     AttributedTypeLoc ATL;
     for (TypeLoc TL = FD->getTypeSourceInfo()->getTypeLoc();
          (ATL = TL.getAsAdjusted<AttributedTypeLoc>());
          TL = ATL.getModifiedLoc()) {
       // The [[lifetimebound]] attribute can be applied to the implicit object
       // parameter of a non-static member function (other than a ctor or dtor)
       // by applying it to the function type.
       if (const auto *A = ATL.getAttrAs<LifetimeBoundAttr>()) {
         const auto *MD = dyn_cast<CXXMethodDecl>(FD);
         if (!MD || MD->isStatic()) {
           S.Diag(A->getLocation(), diag::err_lifetimebound_no_object_param)
               << !MD << A->getRange();
         } else if (isa<CXXConstructorDecl>(MD) || isa<CXXDestructorDecl>(MD)) {
           S.Diag(A->getLocation(), diag::err_lifetimebound_ctor_dtor)
               << isa<CXXDestructorDecl>(MD) << A->getRange();
         }
       }
     }
   }
 }
 
 static void checkDLLAttributeRedeclaration(Sema &S, NamedDecl *OldDecl,
                                            NamedDecl *NewDecl,
                                            bool IsSpecialization,
                                            bool IsDefinition) {
   if (OldDecl->isInvalidDecl() || NewDecl->isInvalidDecl())
     return;
 
   bool IsTemplate = false;
   if (TemplateDecl *OldTD = dyn_cast<TemplateDecl>(OldDecl)) {
     OldDecl = OldTD->getTemplatedDecl();
     IsTemplate = true;
     if (!IsSpecialization)
       IsDefinition = false;
   }
   if (TemplateDecl *NewTD = dyn_cast<TemplateDecl>(NewDecl)) {
     NewDecl = NewTD->getTemplatedDecl();
     IsTemplate = true;
   }
 
   if (!OldDecl || !NewDecl)
     return;
 
   const DLLImportAttr *OldImportAttr = OldDecl->getAttr<DLLImportAttr>();
   const DLLExportAttr *OldExportAttr = OldDecl->getAttr<DLLExportAttr>();
   const DLLImportAttr *NewImportAttr = NewDecl->getAttr<DLLImportAttr>();
   const DLLExportAttr *NewExportAttr = NewDecl->getAttr<DLLExportAttr>();
 
   // dllimport and dllexport are inheritable attributes so we have to exclude
   // inherited attribute instances.
   bool HasNewAttr = (NewImportAttr && !NewImportAttr->isInherited()) ||
                     (NewExportAttr && !NewExportAttr->isInherited());
 
   // A redeclaration is not allowed to add a dllimport or dllexport attribute,
   // the only exception being explicit specializations.
   // Implicitly generated declarations are also excluded for now because there
   // is no other way to switch these to use dllimport or dllexport.
   bool AddsAttr = !(OldImportAttr || OldExportAttr) && HasNewAttr;
 
   if (AddsAttr && !IsSpecialization && !OldDecl->isImplicit()) {
     // Allow with a warning for free functions and global variables.
     bool JustWarn = false;
     if (!OldDecl->isCXXClassMember()) {
       auto *VD = dyn_cast<VarDecl>(OldDecl);
       if (VD && !VD->getDescribedVarTemplate())
         JustWarn = true;
       auto *FD = dyn_cast<FunctionDecl>(OldDecl);
       if (FD && FD->getTemplatedKind() == FunctionDecl::TK_NonTemplate)
         JustWarn = true;
     }
 
     // We cannot change a declaration that's been used because IR has already
     // been emitted. Dllimported functions will still work though (modulo
     // address equality) as they can use the thunk.
     if (OldDecl->isUsed())
       if (!isa<FunctionDecl>(OldDecl) || !NewImportAttr)
         JustWarn = false;
 
     unsigned DiagID = JustWarn ? diag::warn_attribute_dll_redeclaration
                                : diag::err_attribute_dll_redeclaration;
     S.Diag(NewDecl->getLocation(), DiagID)
         << NewDecl
         << (NewImportAttr ? (const Attr *)NewImportAttr : NewExportAttr);
     S.Diag(OldDecl->getLocation(), diag::note_previous_declaration);
     if (!JustWarn) {
       NewDecl->setInvalidDecl();
       return;
     }
   }
 
   // A redeclaration is not allowed to drop a dllimport attribute, the only
   // exceptions being inline function definitions (except for function
   // templates), local extern declarations, qualified friend declarations or
   // special MSVC extension: in the last case, the declaration is treated as if
   // it were marked dllexport.
   bool IsInline = false, IsStaticDataMember = false, IsQualifiedFriend = false;
   bool IsMicrosoftABI  = S.Context.getTargetInfo().shouldDLLImportComdatSymbols();
   if (const auto *VD = dyn_cast<VarDecl>(NewDecl)) {
     // Ignore static data because out-of-line definitions are diagnosed
     // separately.
     IsStaticDataMember = VD->isStaticDataMember();
     IsDefinition = VD->isThisDeclarationADefinition(S.Context) !=
                    VarDecl::DeclarationOnly;
   } else if (const auto *FD = dyn_cast<FunctionDecl>(NewDecl)) {
     IsInline = FD->isInlined();
     IsQualifiedFriend = FD->getQualifier() &&
                         FD->getFriendObjectKind() == Decl::FOK_Declared;
   }
 
   if (OldImportAttr && !HasNewAttr &&
       (!IsInline || (IsMicrosoftABI && IsTemplate)) && !IsStaticDataMember &&
       !NewDecl->isLocalExternDecl() && !IsQualifiedFriend) {
     if (IsMicrosoftABI && IsDefinition) {
       if (IsSpecialization) {
         S.Diag(
             NewDecl->getLocation(),
             diag::err_attribute_dllimport_function_specialization_definition);
         S.Diag(OldImportAttr->getLocation(), diag::note_attribute);
         NewDecl->dropAttr<DLLImportAttr>();
       } else {
         S.Diag(NewDecl->getLocation(),
                diag::warn_redeclaration_without_import_attribute)
             << NewDecl;
         S.Diag(OldDecl->getLocation(), diag::note_previous_declaration);
         NewDecl->dropAttr<DLLImportAttr>();
         NewDecl->addAttr(DLLExportAttr::CreateImplicit(
             S.Context, NewImportAttr->getRange()));
       }
     } else if (IsMicrosoftABI && IsSpecialization) {
       assert(!IsDefinition);
       // MSVC allows this. Keep the inherited attribute.
     } else {
       S.Diag(NewDecl->getLocation(),
              diag::warn_redeclaration_without_attribute_prev_attribute_ignored)
           << NewDecl << OldImportAttr;
       S.Diag(OldDecl->getLocation(), diag::note_previous_declaration);
       S.Diag(OldImportAttr->getLocation(), diag::note_previous_attribute);
       OldDecl->dropAttr<DLLImportAttr>();
       NewDecl->dropAttr<DLLImportAttr>();
     }
   } else if (IsInline && OldImportAttr && !IsMicrosoftABI) {
     // In MinGW, seeing a function declared inline drops the dllimport
     // attribute.
     OldDecl->dropAttr<DLLImportAttr>();
     NewDecl->dropAttr<DLLImportAttr>();
     S.Diag(NewDecl->getLocation(),
            diag::warn_dllimport_dropped_from_inline_function)
         << NewDecl << OldImportAttr;
   }
 
   // A specialization of a class template member function is processed here
   // since it's a redeclaration. If the parent class is dllexport, the
   // specialization inherits that attribute. This doesn't happen automatically
   // since the parent class isn't instantiated until later.
   if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(NewDecl)) {
     if (MD->getTemplatedKind() == FunctionDecl::TK_MemberSpecialization &&
         !NewImportAttr && !NewExportAttr) {
       if (const DLLExportAttr *ParentExportAttr =
               MD->getParent()->getAttr<DLLExportAttr>()) {
         DLLExportAttr *NewAttr = ParentExportAttr->clone(S.Context);
         NewAttr->setInherited(true);
         NewDecl->addAttr(NewAttr);
       }
     }
   }
 }
 
 /// Given that we are within the definition of the given function,
 /// will that definition behave like C99's 'inline', where the
 /// definition is discarded except for optimization purposes?
 static bool isFunctionDefinitionDiscarded(Sema &S, FunctionDecl *FD) {
   // Try to avoid calling GetGVALinkageForFunction.
 
   // All cases of this require the 'inline' keyword.
   if (!FD->isInlined()) return false;
 
   // This is only possible in C++ with the gnu_inline attribute.
   if (S.getLangOpts().CPlusPlus && !FD->hasAttr<GNUInlineAttr>())
     return false;
 
   // Okay, go ahead and call the relatively-more-expensive function.
   return S.Context.GetGVALinkageForFunction(FD) == GVA_AvailableExternally;
 }
 
 /// Determine whether a variable is extern "C" prior to attaching
 /// an initializer. We can't just call isExternC() here, because that
 /// will also compute and cache whether the declaration is externally
 /// visible, which might change when we attach the initializer.
 ///
 /// This can only be used if the declaration is known to not be a
 /// redeclaration of an internal linkage declaration.
 ///
 /// For instance:
 ///
 ///   auto x = []{};
 ///
 /// Attaching the initializer here makes this declaration not externally
 /// visible, because its type has internal linkage.
 ///
 /// FIXME: This is a hack.
 template<typename T>
 static bool isIncompleteDeclExternC(Sema &S, const T *D) {
   if (S.getLangOpts().CPlusPlus) {
     // In C++, the overloadable attribute negates the effects of extern "C".
     if (!D->isInExternCContext() || D->template hasAttr<OverloadableAttr>())
       return false;
 
     // So do CUDA's host/device attributes.
     if (S.getLangOpts().CUDA && (D->template hasAttr<CUDADeviceAttr>() ||
                                  D->template hasAttr<CUDAHostAttr>()))
       return false;
   }
   return D->isExternC();
 }
 
 static bool shouldConsiderLinkage(const VarDecl *VD) {
   const DeclContext *DC = VD->getDeclContext()->getRedeclContext();
   if (DC->isFunctionOrMethod() || isa<OMPDeclareReductionDecl>(DC) ||
       isa<OMPDeclareMapperDecl>(DC))
     return VD->hasExternalStorage();
   if (DC->isFileContext())
     return true;
   if (DC->isRecord())
     return false;
   if (DC->getDeclKind() == Decl::HLSLBuffer)
     return false;
 
   if (isa<RequiresExprBodyDecl>(DC))
     return false;
   llvm_unreachable("Unexpected context");
 }
 
 static bool shouldConsiderLinkage(const FunctionDecl *FD) {
   const DeclContext *DC = FD->getDeclContext()->getRedeclContext();
   if (DC->isFileContext() || DC->isFunctionOrMethod() ||
       isa<OMPDeclareReductionDecl>(DC) || isa<OMPDeclareMapperDecl>(DC))
     return true;
   if (DC->isRecord())
     return false;
   llvm_unreachable("Unexpected context");
 }
 
 static bool hasParsedAttr(Scope *S, const Declarator &PD,
                           ParsedAttr::Kind Kind) {
   // Check decl attributes on the DeclSpec.
   if (PD.getDeclSpec().getAttributes().hasAttribute(Kind))
     return true;
 
   // Walk the declarator structure, checking decl attributes that were in a type
   // position to the decl itself.
   for (unsigned I = 0, E = PD.getNumTypeObjects(); I != E; ++I) {
     if (PD.getTypeObject(I).getAttrs().hasAttribute(Kind))
       return true;
   }
 
   // Finally, check attributes on the decl itself.
   return PD.getAttributes().hasAttribute(Kind) ||
          PD.getDeclarationAttributes().hasAttribute(Kind);
 }
 
 /// Adjust the \c DeclContext for a function or variable that might be a
 /// function-local external declaration.
 bool Sema::adjustContextForLocalExternDecl(DeclContext *&DC) {
   if (!DC->isFunctionOrMethod())
     return false;
 
   // If this is a local extern function or variable declared within a function
   // template, don't add it into the enclosing namespace scope until it is
   // instantiated; it might have a dependent type right now.
   if (DC->isDependentContext())
     return true;
 
   // C++11 [basic.link]p7:
   //   When a block scope declaration of an entity with linkage is not found to
   //   refer to some other declaration, then that entity is a member of the
   //   innermost enclosing namespace.
   //
   // Per C++11 [namespace.def]p6, the innermost enclosing namespace is a
   // semantically-enclosing namespace, not a lexically-enclosing one.
   while (!DC->isFileContext() && !isa<LinkageSpecDecl>(DC))
     DC = DC->getParent();
   return true;
 }
 
 /// Returns true if given declaration has external C language linkage.
 static bool isDeclExternC(const Decl *D) {
   if (const auto *FD = dyn_cast<FunctionDecl>(D))
     return FD->isExternC();
   if (const auto *VD = dyn_cast<VarDecl>(D))
     return VD->isExternC();
 
   llvm_unreachable("Unknown type of decl!");
 }
 
 /// Returns true if there hasn't been any invalid type diagnosed.
 static bool diagnoseOpenCLTypes(Sema &Se, VarDecl *NewVD) {
   DeclContext *DC = NewVD->getDeclContext();
   QualType R = NewVD->getType();
 
   // OpenCL v2.0 s6.9.b - Image type can only be used as a function argument.
   // OpenCL v2.0 s6.13.16.1 - Pipe type can only be used as a function
   // argument.
   if (R->isImageType() || R->isPipeType()) {
     Se.Diag(NewVD->getLocation(),
             diag::err_opencl_type_can_only_be_used_as_function_parameter)
         << R;
     NewVD->setInvalidDecl();
     return false;
   }
 
   // OpenCL v1.2 s6.9.r:
   // The event type cannot be used to declare a program scope variable.
   // OpenCL v2.0 s6.9.q:
   // The clk_event_t and reserve_id_t types cannot be declared in program
   // scope.
   if (NewVD->hasGlobalStorage() && !NewVD->isStaticLocal()) {
     if (R->isReserveIDT() || R->isClkEventT() || R->isEventT()) {
       Se.Diag(NewVD->getLocation(),
               diag::err_invalid_type_for_program_scope_var)
           << R;
       NewVD->setInvalidDecl();
       return false;
     }
   }
 
   // OpenCL v1.0 s6.8.a.3: Pointers to functions are not allowed.
   if (!Se.getOpenCLOptions().isAvailableOption("__cl_clang_function_pointers",
                                                Se.getLangOpts())) {
     QualType NR = R.getCanonicalType();
     while (NR->isPointerType() || NR->isMemberFunctionPointerType() ||
            NR->isReferenceType()) {
       if (NR->isFunctionPointerType() || NR->isMemberFunctionPointerType() ||
           NR->isFunctionReferenceType()) {
         Se.Diag(NewVD->getLocation(), diag::err_opencl_function_pointer)
             << NR->isReferenceType();
         NewVD->setInvalidDecl();
         return false;
       }
       NR = NR->getPointeeType();
     }
   }
 
   if (!Se.getOpenCLOptions().isAvailableOption("cl_khr_fp16",
                                                Se.getLangOpts())) {
     // OpenCL v1.2 s6.1.1.1: reject declaring variables of the half and
     // half array type (unless the cl_khr_fp16 extension is enabled).
     if (Se.Context.getBaseElementType(R)->isHalfType()) {
       Se.Diag(NewVD->getLocation(), diag::err_opencl_half_declaration) << R;
       NewVD->setInvalidDecl();
       return false;
     }
   }
 
   // OpenCL v1.2 s6.9.r:
   // The event type cannot be used with the __local, __constant and __global
   // address space qualifiers.
   if (R->isEventT()) {
     if (R.getAddressSpace() != LangAS::opencl_private) {
       Se.Diag(NewVD->getBeginLoc(), diag::err_event_t_addr_space_qual);
       NewVD->setInvalidDecl();
       return false;
     }
   }
 
   if (R->isSamplerT()) {
     // OpenCL v1.2 s6.9.b p4:
     // The sampler type cannot be used with the __local and __global address
     // space qualifiers.
     if (R.getAddressSpace() == LangAS::opencl_local ||
         R.getAddressSpace() == LangAS::opencl_global) {
       Se.Diag(NewVD->getLocation(), diag::err_wrong_sampler_addressspace);
       NewVD->setInvalidDecl();
     }
 
     // OpenCL v1.2 s6.12.14.1:
     // A global sampler must be declared with either the constant address
     // space qualifier or with the const qualifier.
     if (DC->isTranslationUnit() &&
         !(R.getAddressSpace() == LangAS::opencl_constant ||
           R.isConstQualified())) {
       Se.Diag(NewVD->getLocation(), diag::err_opencl_nonconst_global_sampler);
       NewVD->setInvalidDecl();
     }
     if (NewVD->isInvalidDecl())
       return false;
   }
 
   return true;
 }
 
 template <typename AttrTy>
 static void copyAttrFromTypedefToDecl(Sema &S, Decl *D, const TypedefType *TT) {
   const TypedefNameDecl *TND = TT->getDecl();
   if (const auto *Attribute = TND->getAttr<AttrTy>()) {
     AttrTy *Clone = Attribute->clone(S.Context);
     Clone->setInherited(true);
     D->addAttr(Clone);
   }
 }
 
 // This function emits warning and a corresponding note based on the
 // ReadOnlyPlacementAttr attribute. The warning checks that all global variable
 // declarations of an annotated type must be const qualified.
 void emitReadOnlyPlacementAttrWarning(Sema &S, const VarDecl *VD) {
   QualType VarType = VD->getType().getCanonicalType();
 
   // Ignore local declarations (for now) and those with const qualification.
   // TODO: Local variables should not be allowed if their type declaration has
   // ReadOnlyPlacementAttr attribute. To be handled in follow-up patch.
   if (!VD || VD->hasLocalStorage() || VD->getType().isConstQualified())
     return;
 
   if (VarType->isArrayType()) {
     // Retrieve element type for array declarations.
     VarType = S.getASTContext().getBaseElementType(VarType);
   }
 
   const RecordDecl *RD = VarType->getAsRecordDecl();
 
   // Check if the record declaration is present and if it has any attributes.
   if (RD == nullptr)
     return;
 
   if (const auto *ConstDecl = RD->getAttr<ReadOnlyPlacementAttr>()) {
     S.Diag(VD->getLocation(), diag::warn_var_decl_not_read_only) << RD;
     S.Diag(ConstDecl->getLocation(), diag::note_enforce_read_only_placement);
     return;
   }
 }
 
 NamedDecl *Sema::ActOnVariableDeclarator(
     Scope *S, Declarator &D, DeclContext *DC, TypeSourceInfo *TInfo,
     LookupResult &Previous, MultiTemplateParamsArg TemplateParamLists,
     bool &AddToScope, ArrayRef<BindingDecl *> Bindings) {
   QualType R = TInfo->getType();
   DeclarationName Name = GetNameForDeclarator(D).getName();
 
   IdentifierInfo *II = Name.getAsIdentifierInfo();
 
   if (D.isDecompositionDeclarator()) {
     // Take the name of the first declarator as our name for diagnostic
     // purposes.
     auto &Decomp = D.getDecompositionDeclarator();
     if (!Decomp.bindings().empty()) {
       II = Decomp.bindings()[0].Name;
       Name = II;
     }
   } else if (!II) {
     Diag(D.getIdentifierLoc(), diag::err_bad_variable_name) << Name;
     return nullptr;
   }
 
 
   DeclSpec::SCS SCSpec = D.getDeclSpec().getStorageClassSpec();
   StorageClass SC = StorageClassSpecToVarDeclStorageClass(D.getDeclSpec());
 
   // dllimport globals without explicit storage class are treated as extern. We
   // have to change the storage class this early to get the right DeclContext.
   if (SC == SC_None && !DC->isRecord() &&
       hasParsedAttr(S, D, ParsedAttr::AT_DLLImport) &&
       !hasParsedAttr(S, D, ParsedAttr::AT_DLLExport))
     SC = SC_Extern;
 
   DeclContext *OriginalDC = DC;
   bool IsLocalExternDecl = SC == SC_Extern &&
                            adjustContextForLocalExternDecl(DC);
 
   if (SCSpec == DeclSpec::SCS_mutable) {
     // mutable can only appear on non-static class members, so it's always
     // an error here
     Diag(D.getIdentifierLoc(), diag::err_mutable_nonmember);
     D.setInvalidType();
     SC = SC_None;
   }
 
   if (getLangOpts().CPlusPlus11 && SCSpec == DeclSpec::SCS_register &&
       !D.getAsmLabel() && !getSourceManager().isInSystemMacro(
                               D.getDeclSpec().getStorageClassSpecLoc())) {
     // In C++11, the 'register' storage class specifier is deprecated.
     // Suppress the warning in system macros, it's used in macros in some
     // popular C system headers, such as in glibc's htonl() macro.
     Diag(D.getDeclSpec().getStorageClassSpecLoc(),
          getLangOpts().CPlusPlus17 ? diag::ext_register_storage_class
                                    : diag::warn_deprecated_register)
       << FixItHint::CreateRemoval(D.getDeclSpec().getStorageClassSpecLoc());
   }
 
   DiagnoseFunctionSpecifiers(D.getDeclSpec());
 
   if (!DC->isRecord() && S->getFnParent() == nullptr) {
     // C99 6.9p2: The storage-class specifiers auto and register shall not
     // appear in the declaration specifiers in an external declaration.
     // Global Register+Asm is a GNU extension we support.
     if (SC == SC_Auto || (SC == SC_Register && !D.getAsmLabel())) {
       Diag(D.getIdentifierLoc(), diag::err_typecheck_sclass_fscope);
       D.setInvalidType();
     }
   }
 
   // If this variable has a VLA type and an initializer, try to
   // fold to a constant-sized type. This is otherwise invalid.
   if (D.hasInitializer() && R->isVariableArrayType())
     tryToFixVariablyModifiedVarType(TInfo, R, D.getIdentifierLoc(),
                                     /*DiagID=*/0);
 
   bool IsMemberSpecialization = false;
   bool IsVariableTemplateSpecialization = false;
   bool IsPartialSpecialization = false;
   bool IsVariableTemplate = false;
   VarDecl *NewVD = nullptr;
   VarTemplateDecl *NewTemplate = nullptr;
   TemplateParameterList *TemplateParams = nullptr;
   if (!getLangOpts().CPlusPlus) {
     NewVD = VarDecl::Create(Context, DC, D.getBeginLoc(), D.getIdentifierLoc(),
                             II, R, TInfo, SC);
 
     if (R->getContainedDeducedType())
       ParsingInitForAutoVars.insert(NewVD);
 
     if (D.isInvalidType())
       NewVD->setInvalidDecl();
 
     if (NewVD->getType().hasNonTrivialToPrimitiveDestructCUnion() &&
         NewVD->hasLocalStorage())
       checkNonTrivialCUnion(NewVD->getType(), NewVD->getLocation(),
                             NTCUC_AutoVar, NTCUK_Destruct);
   } else {
     bool Invalid = false;
 
     if (DC->isRecord() && !CurContext->isRecord()) {
       // This is an out-of-line definition of a static data member.
       switch (SC) {
       case SC_None:
         break;
       case SC_Static:
         Diag(D.getDeclSpec().getStorageClassSpecLoc(),
              diag::err_static_out_of_line)
           << FixItHint::CreateRemoval(D.getDeclSpec().getStorageClassSpecLoc());
         break;
       case SC_Auto:
       case SC_Register:
       case SC_Extern:
         // [dcl.stc] p2: The auto or register specifiers shall be applied only
         // to names of variables declared in a block or to function parameters.
         // [dcl.stc] p6: The extern specifier cannot be used in the declaration
         // of class members
 
         Diag(D.getDeclSpec().getStorageClassSpecLoc(),
              diag::err_storage_class_for_static_member)
           << FixItHint::CreateRemoval(D.getDeclSpec().getStorageClassSpecLoc());
         break;
       case SC_PrivateExtern:
         llvm_unreachable("C storage class in c++!");
       }
     }
 
     if (SC == SC_Static && CurContext->isRecord()) {
       if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(DC)) {
         // Walk up the enclosing DeclContexts to check for any that are
         // incompatible with static data members.
         const DeclContext *FunctionOrMethod = nullptr;
         const CXXRecordDecl *AnonStruct = nullptr;
         for (DeclContext *Ctxt = DC; Ctxt; Ctxt = Ctxt->getParent()) {
           if (Ctxt->isFunctionOrMethod()) {
             FunctionOrMethod = Ctxt;
             break;
           }
           const CXXRecordDecl *ParentDecl = dyn_cast<CXXRecordDecl>(Ctxt);
           if (ParentDecl && !ParentDecl->getDeclName()) {
             AnonStruct = ParentDecl;
             break;
           }
         }
         if (FunctionOrMethod) {
           // C++ [class.static.data]p5: A local class shall not have static data
           // members.
           Diag(D.getIdentifierLoc(),
                diag::err_static_data_member_not_allowed_in_local_class)
             << Name << RD->getDeclName() << RD->getTagKind();
         } else if (AnonStruct) {
           // C++ [class.static.data]p4: Unnamed classes and classes contained
           // directly or indirectly within unnamed classes shall not contain
           // static data members.
           Diag(D.getIdentifierLoc(),
                diag::err_static_data_member_not_allowed_in_anon_struct)
             << Name << AnonStruct->getTagKind();
           Invalid = true;
         } else if (RD->isUnion()) {
           // C++98 [class.union]p1: If a union contains a static data member,
           // the program is ill-formed. C++11 drops this restriction.
           Diag(D.getIdentifierLoc(),
                getLangOpts().CPlusPlus11
                  ? diag::warn_cxx98_compat_static_data_member_in_union
                  : diag::ext_static_data_member_in_union) << Name;
         }
       }
     }
 
     // Match up the template parameter lists with the scope specifier, then
     // determine whether we have a template or a template specialization.
     bool InvalidScope = false;
     TemplateParams = MatchTemplateParametersToScopeSpecifier(
         D.getDeclSpec().getBeginLoc(), D.getIdentifierLoc(),
         D.getCXXScopeSpec(),
         D.getName().getKind() == UnqualifiedIdKind::IK_TemplateId
             ? D.getName().TemplateId
             : nullptr,
         TemplateParamLists,
         /*never a friend*/ false, IsMemberSpecialization, InvalidScope);
     Invalid |= InvalidScope;
 
     if (TemplateParams) {
       if (!TemplateParams->size() &&
           D.getName().getKind() != UnqualifiedIdKind::IK_TemplateId) {
         // There is an extraneous 'template<>' for this variable. Complain
         // about it, but allow the declaration of the variable.
         Diag(TemplateParams->getTemplateLoc(),
              diag::err_template_variable_noparams)
           << II
           << SourceRange(TemplateParams->getTemplateLoc(),
                          TemplateParams->getRAngleLoc());
         TemplateParams = nullptr;
       } else {
         // Check that we can declare a template here.
         if (CheckTemplateDeclScope(S, TemplateParams))
           return nullptr;
 
         if (D.getName().getKind() == UnqualifiedIdKind::IK_TemplateId) {
           // This is an explicit specialization or a partial specialization.
           IsVariableTemplateSpecialization = true;
           IsPartialSpecialization = TemplateParams->size() > 0;
         } else { // if (TemplateParams->size() > 0)
           // This is a template declaration.
           IsVariableTemplate = true;
 
           // Only C++1y supports variable templates (N3651).
           Diag(D.getIdentifierLoc(),
                getLangOpts().CPlusPlus14
                    ? diag::warn_cxx11_compat_variable_template
                    : diag::ext_variable_template);
         }
       }
     } else {
       // Check that we can declare a member specialization here.
       if (!TemplateParamLists.empty() && IsMemberSpecialization &&
           CheckTemplateDeclScope(S, TemplateParamLists.back()))
         return nullptr;
       assert((Invalid ||
               D.getName().getKind() != UnqualifiedIdKind::IK_TemplateId) &&
              "should have a 'template<>' for this decl");
     }
 
     if (IsVariableTemplateSpecialization) {
       SourceLocation TemplateKWLoc =
           TemplateParamLists.size() > 0
               ? TemplateParamLists[0]->getTemplateLoc()
               : SourceLocation();
       DeclResult Res = ActOnVarTemplateSpecialization(
           S, D, TInfo, TemplateKWLoc, TemplateParams, SC,
           IsPartialSpecialization);
       if (Res.isInvalid())
         return nullptr;
       NewVD = cast<VarDecl>(Res.get());
       AddToScope = false;
     } else if (D.isDecompositionDeclarator()) {
       NewVD = DecompositionDecl::Create(Context, DC, D.getBeginLoc(),
                                         D.getIdentifierLoc(), R, TInfo, SC,
                                         Bindings);
     } else
       NewVD = VarDecl::Create(Context, DC, D.getBeginLoc(),
                               D.getIdentifierLoc(), II, R, TInfo, SC);
 
     // If this is supposed to be a variable template, create it as such.
     if (IsVariableTemplate) {
       NewTemplate =
           VarTemplateDecl::Create(Context, DC, D.getIdentifierLoc(), Name,
                                   TemplateParams, NewVD);
       NewVD->setDescribedVarTemplate(NewTemplate);
     }
 
     // If this decl has an auto type in need of deduction, make a note of the
     // Decl so we can diagnose uses of it in its own initializer.
     if (R->getContainedDeducedType())
       ParsingInitForAutoVars.insert(NewVD);
 
     if (D.isInvalidType() || Invalid) {
       NewVD->setInvalidDecl();
       if (NewTemplate)
         NewTemplate->setInvalidDecl();
     }
 
     SetNestedNameSpecifier(*this, NewVD, D);
 
     // If we have any template parameter lists that don't directly belong to
     // the variable (matching the scope specifier), store them.
     // An explicit variable template specialization does not own any template
     // parameter lists.
     bool IsExplicitSpecialization =
         IsVariableTemplateSpecialization && !IsPartialSpecialization;
     unsigned VDTemplateParamLists =
         (TemplateParams && !IsExplicitSpecialization) ? 1 : 0;
     if (TemplateParamLists.size() > VDTemplateParamLists)
       NewVD->setTemplateParameterListsInfo(
           Context, TemplateParamLists.drop_back(VDTemplateParamLists));
   }
 
   if (D.getDeclSpec().isInlineSpecified()) {
     if (!getLangOpts().CPlusPlus) {
       Diag(D.getDeclSpec().getInlineSpecLoc(), diag::err_inline_non_function)
           << 0;
     } else if (CurContext->isFunctionOrMethod()) {
       // 'inline' is not allowed on block scope variable declaration.
       Diag(D.getDeclSpec().getInlineSpecLoc(),
            diag::err_inline_declaration_block_scope) << Name
         << FixItHint::CreateRemoval(D.getDeclSpec().getInlineSpecLoc());
     } else {
       Diag(D.getDeclSpec().getInlineSpecLoc(),
            getLangOpts().CPlusPlus17 ? diag::warn_cxx14_compat_inline_variable
                                      : diag::ext_inline_variable);
       NewVD->setInlineSpecified();
     }
   }
 
   // Set the lexical context. If the declarator has a C++ scope specifier, the
   // lexical context will be different from the semantic context.
   NewVD->setLexicalDeclContext(CurContext);
   if (NewTemplate)
     NewTemplate->setLexicalDeclContext(CurContext);
 
   if (IsLocalExternDecl) {
     if (D.isDecompositionDeclarator())
       for (auto *B : Bindings)
         B->setLocalExternDecl();
     else
       NewVD->setLocalExternDecl();
   }
 
   bool EmitTLSUnsupportedError = false;
   if (DeclSpec::TSCS TSCS = D.getDeclSpec().getThreadStorageClassSpec()) {
     // C++11 [dcl.stc]p4:
     //   When thread_local is applied to a variable of block scope the
     //   storage-class-specifier static is implied if it does not appear
     //   explicitly.
     // Core issue: 'static' is not implied if the variable is declared
     //   'extern'.
     if (NewVD->hasLocalStorage() &&
         (SCSpec != DeclSpec::SCS_unspecified ||
          TSCS != DeclSpec::TSCS_thread_local ||
          !DC->isFunctionOrMethod()))
       Diag(D.getDeclSpec().getThreadStorageClassSpecLoc(),
            diag::err_thread_non_global)
         << DeclSpec::getSpecifierName(TSCS);
     else if (!Context.getTargetInfo().isTLSSupported()) {
       if (getLangOpts().CUDA || getLangOpts().OpenMPIsTargetDevice ||
           getLangOpts().SYCLIsDevice) {
         // Postpone error emission until we've collected attributes required to
         // figure out whether it's a host or device variable and whether the
         // error should be ignored.
         EmitTLSUnsupportedError = true;
         // We still need to mark the variable as TLS so it shows up in AST with
         // proper storage class for other tools to use even if we're not going
         // to emit any code for it.
         NewVD->setTSCSpec(TSCS);
       } else
         Diag(D.getDeclSpec().getThreadStorageClassSpecLoc(),
              diag::err_thread_unsupported);
     } else
       NewVD->setTSCSpec(TSCS);
   }
 
   switch (D.getDeclSpec().getConstexprSpecifier()) {
   case ConstexprSpecKind::Unspecified:
     break;
 
   case ConstexprSpecKind::Consteval:
     Diag(D.getDeclSpec().getConstexprSpecLoc(),
          diag::err_constexpr_wrong_decl_kind)
         << static_cast<int>(D.getDeclSpec().getConstexprSpecifier());
     [[fallthrough]];
 
   case ConstexprSpecKind::Constexpr:
     NewVD->setConstexpr(true);
     // C++1z [dcl.spec.constexpr]p1:
     //   A static data member declared with the constexpr specifier is
     //   implicitly an inline variable.
     if (NewVD->isStaticDataMember() &&
         (getLangOpts().CPlusPlus17 ||
          Context.getTargetInfo().getCXXABI().isMicrosoft()))
       NewVD->setImplicitlyInline();
     break;
 
   case ConstexprSpecKind::Constinit:
     if (!NewVD->hasGlobalStorage())
       Diag(D.getDeclSpec().getConstexprSpecLoc(),
            diag::err_constinit_local_variable);
     else
       NewVD->addAttr(
           ConstInitAttr::Create(Context, D.getDeclSpec().getConstexprSpecLoc(),
                                 ConstInitAttr::Keyword_constinit));
     break;
   }
 
   // C99 6.7.4p3
   //   An inline definition of a function with external linkage shall
   //   not contain a definition of a modifiable object with static or
   //   thread storage duration...
   // We only apply this when the function is required to be defined
   // elsewhere, i.e. when the function is not 'extern inline'.  Note
   // that a local variable with thread storage duration still has to
   // be marked 'static'.  Also note that it's possible to get these
   // semantics in C++ using __attribute__((gnu_inline)).
   if (SC == SC_Static && S->getFnParent() != nullptr &&
       !NewVD->getType().isConstQualified()) {
     FunctionDecl *CurFD = getCurFunctionDecl();
     if (CurFD && isFunctionDefinitionDiscarded(*this, CurFD)) {
       Diag(D.getDeclSpec().getStorageClassSpecLoc(),
            diag::warn_static_local_in_extern_inline);
       MaybeSuggestAddingStaticToDecl(CurFD);
     }
   }
 
   if (D.getDeclSpec().isModulePrivateSpecified()) {
     if (IsVariableTemplateSpecialization)
       Diag(NewVD->getLocation(), diag::err_module_private_specialization)
           << (IsPartialSpecialization ? 1 : 0)
           << FixItHint::CreateRemoval(
                  D.getDeclSpec().getModulePrivateSpecLoc());
     else if (IsMemberSpecialization)
       Diag(NewVD->getLocation(), diag::err_module_private_specialization)
         << 2
         << FixItHint::CreateRemoval(D.getDeclSpec().getModulePrivateSpecLoc());
     else if (NewVD->hasLocalStorage())
       Diag(NewVD->getLocation(), diag::err_module_private_local)
           << 0 << NewVD
           << SourceRange(D.getDeclSpec().getModulePrivateSpecLoc())
           << FixItHint::CreateRemoval(
                  D.getDeclSpec().getModulePrivateSpecLoc());
     else {
       NewVD->setModulePrivate();
       if (NewTemplate)
         NewTemplate->setModulePrivate();
       for (auto *B : Bindings)
         B->setModulePrivate();
     }
   }
 
   if (getLangOpts().OpenCL) {
     deduceOpenCLAddressSpace(NewVD);
 
     DeclSpec::TSCS TSC = D.getDeclSpec().getThreadStorageClassSpec();
     if (TSC != TSCS_unspecified) {
       Diag(D.getDeclSpec().getThreadStorageClassSpecLoc(),
            diag::err_opencl_unknown_type_specifier)
           << getLangOpts().getOpenCLVersionString()
           << DeclSpec::getSpecifierName(TSC) << 1;
       NewVD->setInvalidDecl();
     }
   }
 
   // WebAssembly tables are always in address space 1 (wasm_var). Don't apply
   // address space if the table has local storage (semantic checks elsewhere
   // will produce an error anyway).
   if (const auto *ATy = dyn_cast<ArrayType>(NewVD->getType())) {
     if (ATy && ATy->getElementType().isWebAssemblyReferenceType() &&
         !NewVD->hasLocalStorage()) {
       QualType Type = Context.getAddrSpaceQualType(
           NewVD->getType(), Context.getLangASForBuiltinAddressSpace(1));
       NewVD->setType(Type);
     }
   }
 
   // Handle attributes prior to checking for duplicates in MergeVarDecl
   ProcessDeclAttributes(S, NewVD, D);
 
   // FIXME: This is probably the wrong location to be doing this and we should
   // probably be doing this for more attributes (especially for function
   // pointer attributes such as format, warn_unused_result, etc.). Ideally
   // the code to copy attributes would be generated by TableGen.
   if (R->isFunctionPointerType())
     if (const auto *TT = R->getAs<TypedefType>())
       copyAttrFromTypedefToDecl<AllocSizeAttr>(*this, NewVD, TT);
 
   if (getLangOpts().CUDA || getLangOpts().OpenMPIsTargetDevice ||
       getLangOpts().SYCLIsDevice) {
     if (EmitTLSUnsupportedError &&
         ((getLangOpts().CUDA && DeclAttrsMatchCUDAMode(getLangOpts(), NewVD)) ||
          (getLangOpts().OpenMPIsTargetDevice &&
           OMPDeclareTargetDeclAttr::isDeclareTargetDeclaration(NewVD))))
       Diag(D.getDeclSpec().getThreadStorageClassSpecLoc(),
            diag::err_thread_unsupported);
 
     if (EmitTLSUnsupportedError &&
         (LangOpts.SYCLIsDevice ||
          (LangOpts.OpenMP && LangOpts.OpenMPIsTargetDevice)))
       targetDiag(D.getIdentifierLoc(), diag::err_thread_unsupported);
     // CUDA B.2.5: "__shared__ and __constant__ variables have implied static
     // storage [duration]."
     if (SC == SC_None && S->getFnParent() != nullptr &&
         (NewVD->hasAttr<CUDASharedAttr>() ||
          NewVD->hasAttr<CUDAConstantAttr>())) {
       NewVD->setStorageClass(SC_Static);
     }
   }
 
   // Ensure that dllimport globals without explicit storage class are treated as
   // extern. The storage class is set above using parsed attributes. Now we can
   // check the VarDecl itself.
   assert(!NewVD->hasAttr<DLLImportAttr>() ||
          NewVD->getAttr<DLLImportAttr>()->isInherited() ||
          NewVD->isStaticDataMember() || NewVD->getStorageClass() != SC_None);
 
   // In auto-retain/release, infer strong retension for variables of
   // retainable type.
   if (getLangOpts().ObjCAutoRefCount && inferObjCARCLifetime(NewVD))
     NewVD->setInvalidDecl();
 
   // Handle GNU asm-label extension (encoded as an attribute).
   if (Expr *E = (Expr*)D.getAsmLabel()) {
     // The parser guarantees this is a string.
     StringLiteral *SE = cast<StringLiteral>(E);
     StringRef Label = SE->getString();
     if (S->getFnParent() != nullptr) {
       switch (SC) {
       case SC_None:
       case SC_Auto:
         Diag(E->getExprLoc(), diag::warn_asm_label_on_auto_decl) << Label;
         break;
       case SC_Register:
         // Local Named register
         if (!Context.getTargetInfo().isValidGCCRegisterName(Label) &&
             DeclAttrsMatchCUDAMode(getLangOpts(), getCurFunctionDecl()))
           Diag(E->getExprLoc(), diag::err_asm_unknown_register_name) << Label;
         break;
       case SC_Static:
       case SC_Extern:
       case SC_PrivateExtern:
         break;
       }
     } else if (SC == SC_Register) {
       // Global Named register
       if (DeclAttrsMatchCUDAMode(getLangOpts(), NewVD)) {
         const auto &TI = Context.getTargetInfo();
         bool HasSizeMismatch;
 
         if (!TI.isValidGCCRegisterName(Label))
           Diag(E->getExprLoc(), diag::err_asm_unknown_register_name) << Label;
         else if (!TI.validateGlobalRegisterVariable(Label,
                                                     Context.getTypeSize(R),
                                                     HasSizeMismatch))
           Diag(E->getExprLoc(), diag::err_asm_invalid_global_var_reg) << Label;
         else if (HasSizeMismatch)
           Diag(E->getExprLoc(), diag::err_asm_register_size_mismatch) << Label;
       }
 
       if (!R->isIntegralType(Context) && !R->isPointerType()) {
         Diag(D.getBeginLoc(), diag::err_asm_bad_register_type);
         NewVD->setInvalidDecl(true);
       }
     }
 
     NewVD->addAttr(AsmLabelAttr::Create(Context, Label,
                                         /*IsLiteralLabel=*/true,
                                         SE->getStrTokenLoc(0)));
   } else if (!ExtnameUndeclaredIdentifiers.empty()) {
     llvm::DenseMap<IdentifierInfo*,AsmLabelAttr*>::iterator I =
       ExtnameUndeclaredIdentifiers.find(NewVD->getIdentifier());
     if (I != ExtnameUndeclaredIdentifiers.end()) {
       if (isDeclExternC(NewVD)) {
         NewVD->addAttr(I->second);
         ExtnameUndeclaredIdentifiers.erase(I);
       } else
         Diag(NewVD->getLocation(), diag::warn_redefine_extname_not_applied)
             << /*Variable*/1 << NewVD;
     }
   }
 
   // Find the shadowed declaration before filtering for scope.
   NamedDecl *ShadowedDecl = D.getCXXScopeSpec().isEmpty()
                                 ? getShadowedDeclaration(NewVD, Previous)
                                 : nullptr;
 
   // Don't consider existing declarations that are in a different
   // scope and are out-of-semantic-context declarations (if the new
   // declaration has linkage).
   FilterLookupForScope(Previous, OriginalDC, S, shouldConsiderLinkage(NewVD),
                        D.getCXXScopeSpec().isNotEmpty() ||
                        IsMemberSpecialization ||
                        IsVariableTemplateSpecialization);
 
   // Check whether the previous declaration is in the same block scope. This
   // affects whether we merge types with it, per C++11 [dcl.array]p3.
   if (getLangOpts().CPlusPlus &&
       NewVD->isLocalVarDecl() && NewVD->hasExternalStorage())
     NewVD->setPreviousDeclInSameBlockScope(
         Previous.isSingleResult() && !Previous.isShadowed() &&
         isDeclInScope(Previous.getFoundDecl(), OriginalDC, S, false));
 
   if (!getLangOpts().CPlusPlus) {
     D.setRedeclaration(CheckVariableDeclaration(NewVD, Previous));
   } else {
     // If this is an explicit specialization of a static data member, check it.
     if (IsMemberSpecialization && !NewVD->isInvalidDecl() &&
         CheckMemberSpecialization(NewVD, Previous))
       NewVD->setInvalidDecl();
 
     // Merge the decl with the existing one if appropriate.
     if (!Previous.empty()) {
       if (Previous.isSingleResult() &&
           isa<FieldDecl>(Previous.getFoundDecl()) &&
           D.getCXXScopeSpec().isSet()) {
         // The user tried to define a non-static data member
         // out-of-line (C++ [dcl.meaning]p1).
         Diag(NewVD->getLocation(), diag::err_nonstatic_member_out_of_line)
           << D.getCXXScopeSpec().getRange();
         Previous.clear();
         NewVD->setInvalidDecl();
       }
     } else if (D.getCXXScopeSpec().isSet()) {
       // No previous declaration in the qualifying scope.
       Diag(D.getIdentifierLoc(), diag::err_no_member)
         << Name << computeDeclContext(D.getCXXScopeSpec(), true)
         << D.getCXXScopeSpec().getRange();
       NewVD->setInvalidDecl();
     }
 
     if (!IsVariableTemplateSpecialization)
       D.setRedeclaration(CheckVariableDeclaration(NewVD, Previous));
 
     // CheckVariableDeclaration will set NewVD as invalid if something is in
     // error like WebAssembly tables being declared as arrays with a non-zero
     // size, but then parsing continues and emits further errors on that line.
     // To avoid that we check here if it happened and return nullptr.
     if (NewVD->getType()->isWebAssemblyTableType() && NewVD->isInvalidDecl())
       return nullptr;
 
     if (NewTemplate) {
       VarTemplateDecl *PrevVarTemplate =
           NewVD->getPreviousDecl()
               ? NewVD->getPreviousDecl()->getDescribedVarTemplate()
               : nullptr;
 
       // Check the template parameter list of this declaration, possibly
       // merging in the template parameter list from the previous variable
       // template declaration.
       if (CheckTemplateParameterList(
               TemplateParams,
               PrevVarTemplate ? PrevVarTemplate->getTemplateParameters()
                               : nullptr,
               (D.getCXXScopeSpec().isSet() && DC && DC->isRecord() &&
                DC->isDependentContext())
                   ? TPC_ClassTemplateMember
                   : TPC_VarTemplate))
         NewVD->setInvalidDecl();
 
       // If we are providing an explicit specialization of a static variable
       // template, make a note of that.
       if (PrevVarTemplate &&
           PrevVarTemplate->getInstantiatedFromMemberTemplate())
         PrevVarTemplate->setMemberSpecialization();
     }
   }
 
   // Diagnose shadowed variables iff this isn't a redeclaration.
   if (ShadowedDecl && !D.isRedeclaration())
     CheckShadow(NewVD, ShadowedDecl, Previous);
 
   ProcessPragmaWeak(S, NewVD);
 
   // If this is the first declaration of an extern C variable, update
   // the map of such variables.
   if (NewVD->isFirstDecl() && !NewVD->isInvalidDecl() &&
       isIncompleteDeclExternC(*this, NewVD))
     RegisterLocallyScopedExternCDecl(NewVD, S);
 
   if (getLangOpts().CPlusPlus && NewVD->isStaticLocal()) {
     MangleNumberingContext *MCtx;
     Decl *ManglingContextDecl;
     std::tie(MCtx, ManglingContextDecl) =
         getCurrentMangleNumberContext(NewVD->getDeclContext());
     if (MCtx) {
       Context.setManglingNumber(
           NewVD, MCtx->getManglingNumber(
                      NewVD, getMSManglingNumber(getLangOpts(), S)));
       Context.setStaticLocalNumber(NewVD, MCtx->getStaticLocalNumber(NewVD));
     }
   }
 
   // Special handling of variable named 'main'.
   if (Name.getAsIdentifierInfo() && Name.getAsIdentifierInfo()->isStr("main") &&
       NewVD->getDeclContext()->getRedeclContext()->isTranslationUnit() &&
       !getLangOpts().Freestanding && !NewVD->getDescribedVarTemplate()) {
 
     // C++ [basic.start.main]p3
     // A program that declares a variable main at global scope is ill-formed.
     if (getLangOpts().CPlusPlus)
       Diag(D.getBeginLoc(), diag::err_main_global_variable);
 
     // In C, and external-linkage variable named main results in undefined
     // behavior.
     else if (NewVD->hasExternalFormalLinkage())
       Diag(D.getBeginLoc(), diag::warn_main_redefined);
   }
 
   if (D.isRedeclaration() && !Previous.empty()) {
     NamedDecl *Prev = Previous.getRepresentativeDecl();
     checkDLLAttributeRedeclaration(*this, Prev, NewVD, IsMemberSpecialization,
                                    D.isFunctionDefinition());
   }
 
   if (NewTemplate) {
     if (NewVD->isInvalidDecl())
       NewTemplate->setInvalidDecl();
     ActOnDocumentableDecl(NewTemplate);
     return NewTemplate;
   }
 
   if (IsMemberSpecialization && !NewVD->isInvalidDecl())
     CompleteMemberSpecialization(NewVD, Previous);
 
   emitReadOnlyPlacementAttrWarning(*this, NewVD);
 
   return NewVD;
 }
 
 /// Enum describing the %select options in diag::warn_decl_shadow.
 enum ShadowedDeclKind {
   SDK_Local,
   SDK_Global,
   SDK_StaticMember,
   SDK_Field,
   SDK_Typedef,
   SDK_Using,
   SDK_StructuredBinding
 };
 
 /// Determine what kind of declaration we're shadowing.
 static ShadowedDeclKind computeShadowedDeclKind(const NamedDecl *ShadowedDecl,
                                                 const DeclContext *OldDC) {
   if (isa<TypeAliasDecl>(ShadowedDecl))
     return SDK_Using;
   else if (isa<TypedefDecl>(ShadowedDecl))
     return SDK_Typedef;
   else if (isa<BindingDecl>(ShadowedDecl))
     return SDK_StructuredBinding;
   else if (isa<RecordDecl>(OldDC))
     return isa<FieldDecl>(ShadowedDecl) ? SDK_Field : SDK_StaticMember;
 
   return OldDC->isFileContext() ? SDK_Global : SDK_Local;
 }
 
 /// Return the location of the capture if the given lambda captures the given
 /// variable \p VD, or an invalid source location otherwise.
 static SourceLocation getCaptureLocation(const LambdaScopeInfo *LSI,
                                          const VarDecl *VD) {
   for (const Capture &Capture : LSI->Captures) {
     if (Capture.isVariableCapture() && Capture.getVariable() == VD)
       return Capture.getLocation();
   }
   return SourceLocation();
 }
 
 static bool shouldWarnIfShadowedDecl(const DiagnosticsEngine &Diags,
                                      const LookupResult &R) {
   // Only diagnose if we're shadowing an unambiguous field or variable.
   if (R.getResultKind() != LookupResult::Found)
     return false;
 
   // Return false if warning is ignored.
   return !Diags.isIgnored(diag::warn_decl_shadow, R.getNameLoc());
 }
 
 /// Return the declaration shadowed by the given variable \p D, or null
 /// if it doesn't shadow any declaration or shadowing warnings are disabled.
 NamedDecl *Sema::getShadowedDeclaration(const VarDecl *D,
                                         const LookupResult &R) {
   if (!shouldWarnIfShadowedDecl(Diags, R))
     return nullptr;
 
   // Don't diagnose declarations at file scope.
   if (D->hasGlobalStorage() && !D->isStaticLocal())
     return nullptr;
 
   NamedDecl *ShadowedDecl = R.getFoundDecl();
   return isa<VarDecl, FieldDecl, BindingDecl>(ShadowedDecl) ? ShadowedDecl
                                                             : nullptr;
 }
 
 /// Return the declaration shadowed by the given typedef \p D, or null
 /// if it doesn't shadow any declaration or shadowing warnings are disabled.
 NamedDecl *Sema::getShadowedDeclaration(const TypedefNameDecl *D,
                                         const LookupResult &R) {
   // Don't warn if typedef declaration is part of a class
   if (D->getDeclContext()->isRecord())
     return nullptr;
 
   if (!shouldWarnIfShadowedDecl(Diags, R))
     return nullptr;
 
   NamedDecl *ShadowedDecl = R.getFoundDecl();
   return isa<TypedefNameDecl>(ShadowedDecl) ? ShadowedDecl : nullptr;
 }
 
 /// Return the declaration shadowed by the given variable \p D, or null
 /// if it doesn't shadow any declaration or shadowing warnings are disabled.
 NamedDecl *Sema::getShadowedDeclaration(const BindingDecl *D,
                                         const LookupResult &R) {
   if (!shouldWarnIfShadowedDecl(Diags, R))
     return nullptr;
 
   NamedDecl *ShadowedDecl = R.getFoundDecl();
   return isa<VarDecl, FieldDecl, BindingDecl>(ShadowedDecl) ? ShadowedDecl
                                                             : nullptr;
 }
 
 /// Diagnose variable or built-in function shadowing.  Implements
 /// -Wshadow.
 ///
 /// This method is called whenever a VarDecl is added to a "useful"
 /// scope.
 ///
 /// \param ShadowedDecl the declaration that is shadowed by the given variable
 /// \param R the lookup of the name
 ///
 void Sema::CheckShadow(NamedDecl *D, NamedDecl *ShadowedDecl,
                        const LookupResult &R) {
   DeclContext *NewDC = D->getDeclContext();
 
   if (FieldDecl *FD = dyn_cast<FieldDecl>(ShadowedDecl)) {
     // Fields are not shadowed by variables in C++ static methods.
     if (CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(NewDC))
       if (MD->isStatic())
         return;
 
     // Fields shadowed by constructor parameters are a special case. Usually
     // the constructor initializes the field with the parameter.
     if (isa<CXXConstructorDecl>(NewDC))
       if (const auto PVD = dyn_cast<ParmVarDecl>(D)) {
         // Remember that this was shadowed so we can either warn about its
         // modification or its existence depending on warning settings.
         ShadowingDecls.insert({PVD->getCanonicalDecl(), FD});
         return;
       }
   }
 
   if (VarDecl *shadowedVar = dyn_cast<VarDecl>(ShadowedDecl))
     if (shadowedVar->isExternC()) {
       // For shadowing external vars, make sure that we point to the global
       // declaration, not a locally scoped extern declaration.
       for (auto *I : shadowedVar->redecls())
         if (I->isFileVarDecl()) {
           ShadowedDecl = I;
           break;
         }
     }
 
   DeclContext *OldDC = ShadowedDecl->getDeclContext()->getRedeclContext();
 
   unsigned WarningDiag = diag::warn_decl_shadow;
   SourceLocation CaptureLoc;
   if (isa<VarDecl>(D) && isa<VarDecl>(ShadowedDecl) && NewDC &&
       isa<CXXMethodDecl>(NewDC)) {
     if (const auto *RD = dyn_cast<CXXRecordDecl>(NewDC->getParent())) {
       if (RD->isLambda() && OldDC->Encloses(NewDC->getLexicalParent())) {
         if (RD->getLambdaCaptureDefault() == LCD_None) {
           // Try to avoid warnings for lambdas with an explicit capture list.
           const auto *LSI = cast<LambdaScopeInfo>(getCurFunction());
           // Warn only when the lambda captures the shadowed decl explicitly.
           CaptureLoc = getCaptureLocation(LSI, cast<VarDecl>(ShadowedDecl));
           if (CaptureLoc.isInvalid())
             WarningDiag = diag::warn_decl_shadow_uncaptured_local;
         } else {
           // Remember that this was shadowed so we can avoid the warning if the
           // shadowed decl isn't captured and the warning settings allow it.
           cast<LambdaScopeInfo>(getCurFunction())
               ->ShadowingDecls.push_back(
                   {cast<VarDecl>(D), cast<VarDecl>(ShadowedDecl)});
           return;
         }
       }
 
       if (cast<VarDecl>(ShadowedDecl)->hasLocalStorage()) {
         // A variable can't shadow a local variable in an enclosing scope, if
         // they are separated by a non-capturing declaration context.
         for (DeclContext *ParentDC = NewDC;
              ParentDC && !ParentDC->Equals(OldDC);
              ParentDC = getLambdaAwareParentOfDeclContext(ParentDC)) {
           // Only block literals, captured statements, and lambda expressions
           // can capture; other scopes don't.
           if (!isa<BlockDecl>(ParentDC) && !isa<CapturedDecl>(ParentDC) &&
               !isLambdaCallOperator(ParentDC)) {
             return;
           }
         }
       }
     }
   }
 
   // Only warn about certain kinds of shadowing for class members.
   if (NewDC && NewDC->isRecord()) {
     // In particular, don't warn about shadowing non-class members.
     if (!OldDC->isRecord())
       return;
 
     // TODO: should we warn about static data members shadowing
     // static data members from base classes?
 
     // TODO: don't diagnose for inaccessible shadowed members.
     // This is hard to do perfectly because we might friend the
     // shadowing context, but that's just a false negative.
   }
 
 
   DeclarationName Name = R.getLookupName();
 
   // Emit warning and note.
   ShadowedDeclKind Kind = computeShadowedDeclKind(ShadowedDecl, OldDC);
   Diag(R.getNameLoc(), WarningDiag) << Name << Kind << OldDC;
   if (!CaptureLoc.isInvalid())
     Diag(CaptureLoc, diag::note_var_explicitly_captured_here)
         << Name << /*explicitly*/ 1;
   Diag(ShadowedDecl->getLocation(), diag::note_previous_declaration);
 }
 
 /// Diagnose shadowing for variables shadowed in the lambda record \p LambdaRD
 /// when these variables are captured by the lambda.
 void Sema::DiagnoseShadowingLambdaDecls(const LambdaScopeInfo *LSI) {
   for (const auto &Shadow : LSI->ShadowingDecls) {
     const VarDecl *ShadowedDecl = Shadow.ShadowedDecl;
     // Try to avoid the warning when the shadowed decl isn't captured.
     SourceLocation CaptureLoc = getCaptureLocation(LSI, ShadowedDecl);
     const DeclContext *OldDC = ShadowedDecl->getDeclContext();
     Diag(Shadow.VD->getLocation(), CaptureLoc.isInvalid()
                                        ? diag::warn_decl_shadow_uncaptured_local
                                        : diag::warn_decl_shadow)
         << Shadow.VD->getDeclName()
         << computeShadowedDeclKind(ShadowedDecl, OldDC) << OldDC;
     if (!CaptureLoc.isInvalid())
       Diag(CaptureLoc, diag::note_var_explicitly_captured_here)
           << Shadow.VD->getDeclName() << /*explicitly*/ 0;
     Diag(ShadowedDecl->getLocation(), diag::note_previous_declaration);
   }
 }
 
 /// Check -Wshadow without the advantage of a previous lookup.
 void Sema::CheckShadow(Scope *S, VarDecl *D) {
   if (Diags.isIgnored(diag::warn_decl_shadow, D->getLocation()))
     return;
 
   LookupResult R(*this, D->getDeclName(), D->getLocation(),
                  Sema::LookupOrdinaryName, Sema::ForVisibleRedeclaration);
   LookupName(R, S);
   if (NamedDecl *ShadowedDecl = getShadowedDeclaration(D, R))
     CheckShadow(D, ShadowedDecl, R);
 }
 
 /// Check if 'E', which is an expression that is about to be modified, refers
 /// to a constructor parameter that shadows a field.
 void Sema::CheckShadowingDeclModification(Expr *E, SourceLocation Loc) {
   // Quickly ignore expressions that can't be shadowing ctor parameters.
   if (!getLangOpts().CPlusPlus || ShadowingDecls.empty())
     return;
   E = E->IgnoreParenImpCasts();
   auto *DRE = dyn_cast<DeclRefExpr>(E);
   if (!DRE)
     return;
   const NamedDecl *D = cast<NamedDecl>(DRE->getDecl()->getCanonicalDecl());
   auto I = ShadowingDecls.find(D);
   if (I == ShadowingDecls.end())
     return;
   const NamedDecl *ShadowedDecl = I->second;
   const DeclContext *OldDC = ShadowedDecl->getDeclContext();
   Diag(Loc, diag::warn_modifying_shadowing_decl) << D << OldDC;
   Diag(D->getLocation(), diag::note_var_declared_here) << D;
   Diag(ShadowedDecl->getLocation(), diag::note_previous_declaration);
 
   // Avoid issuing multiple warnings about the same decl.
   ShadowingDecls.erase(I);
 }
 
 /// Check for conflict between this global or extern "C" declaration and
 /// previous global or extern "C" declarations. This is only used in C++.
 template<typename T>
 static bool checkGlobalOrExternCConflict(
     Sema &S, const T *ND, bool IsGlobal, LookupResult &Previous) {
   assert(S.getLangOpts().CPlusPlus && "only C++ has extern \"C\"");
   NamedDecl *Prev = S.findLocallyScopedExternCDecl(ND->getDeclName());
 
   if (!Prev && IsGlobal && !isIncompleteDeclExternC(S, ND)) {
     // The common case: this global doesn't conflict with any extern "C"
     // declaration.
     return false;
   }
 
   if (Prev) {
     if (!IsGlobal || isIncompleteDeclExternC(S, ND)) {
       // Both the old and new declarations have C language linkage. This is a
       // redeclaration.
       Previous.clear();
       Previous.addDecl(Prev);
       return true;
     }
 
     // This is a global, non-extern "C" declaration, and there is a previous
     // non-global extern "C" declaration. Diagnose if this is a variable
     // declaration.
     if (!isa<VarDecl>(ND))
       return false;
   } else {
     // The declaration is extern "C". Check for any declaration in the
     // translation unit which might conflict.
     if (IsGlobal) {
       // We have already performed the lookup into the translation unit.
       IsGlobal = false;
       for (LookupResult::iterator I = Previous.begin(), E = Previous.end();
            I != E; ++I) {
         if (isa<VarDecl>(*I)) {
           Prev = *I;
           break;
         }
       }
     } else {
       DeclContext::lookup_result R =
           S.Context.getTranslationUnitDecl()->lookup(ND->getDeclName());
       for (DeclContext::lookup_result::iterator I = R.begin(), E = R.end();
            I != E; ++I) {
         if (isa<VarDecl>(*I)) {
           Prev = *I;
           break;
         }
         // FIXME: If we have any other entity with this name in global scope,
         // the declaration is ill-formed, but that is a defect: it breaks the
         // 'stat' hack, for instance. Only variables can have mangled name
         // clashes with extern "C" declarations, so only they deserve a
         // diagnostic.
       }
     }
 
     if (!Prev)
       return false;
   }
 
   // Use the first declaration's location to ensure we point at something which
   // is lexically inside an extern "C" linkage-spec.
   assert(Prev && "should have found a previous declaration to diagnose");
   if (FunctionDecl *FD = dyn_cast<FunctionDecl>(Prev))
     Prev = FD->getFirstDecl();
   else
     Prev = cast<VarDecl>(Prev)->getFirstDecl();
 
   S.Diag(ND->getLocation(), diag::err_extern_c_global_conflict)
     << IsGlobal << ND;
   S.Diag(Prev->getLocation(), diag::note_extern_c_global_conflict)
     << IsGlobal;
   return false;
 }
 
 /// Apply special rules for handling extern "C" declarations. Returns \c true
 /// if we have found that this is a redeclaration of some prior entity.
 ///
 /// Per C++ [dcl.link]p6:
 ///   Two declarations [for a function or variable] with C language linkage
 ///   with the same name that appear in different scopes refer to the same
 ///   [entity]. An entity with C language linkage shall not be declared with
 ///   the same name as an entity in global scope.
 template<typename T>
 static bool checkForConflictWithNonVisibleExternC(Sema &S, const T *ND,
                                                   LookupResult &Previous) {
   if (!S.getLangOpts().CPlusPlus) {
     // In C, when declaring a global variable, look for a corresponding 'extern'
     // variable declared in function scope. We don't need this in C++, because
     // we find local extern decls in the surrounding file-scope DeclContext.
     if (ND->getDeclContext()->getRedeclContext()->isTranslationUnit()) {
       if (NamedDecl *Prev = S.findLocallyScopedExternCDecl(ND->getDeclName())) {
         Previous.clear();
         Previous.addDecl(Prev);
         return true;
       }
     }
     return false;
   }
 
   // A declaration in the translation unit can conflict with an extern "C"
   // declaration.
   if (ND->getDeclContext()->getRedeclContext()->isTranslationUnit())
     return checkGlobalOrExternCConflict(S, ND, /*IsGlobal*/true, Previous);
 
   // An extern "C" declaration can conflict with a declaration in the
   // translation unit or can be a redeclaration of an extern "C" declaration
   // in another scope.
   if (isIncompleteDeclExternC(S,ND))
     return checkGlobalOrExternCConflict(S, ND, /*IsGlobal*/false, Previous);
 
   // Neither global nor extern "C": nothing to do.
   return false;
 }
 
 void Sema::CheckVariableDeclarationType(VarDecl *NewVD) {
   // If the decl is already known invalid, don't check it.
   if (NewVD->isInvalidDecl())
     return;
 
   QualType T = NewVD->getType();
 
   // Defer checking an 'auto' type until its initializer is attached.
   if (T->isUndeducedType())
     return;
 
   if (NewVD->hasAttrs())
     CheckAlignasUnderalignment(NewVD);
 
   if (T->isObjCObjectType()) {
     Diag(NewVD->getLocation(), diag::err_statically_allocated_object)
       << FixItHint::CreateInsertion(NewVD->getLocation(), "*");
     T = Context.getObjCObjectPointerType(T);
     NewVD->setType(T);
   }
 
   // Emit an error if an address space was applied to decl with local storage.
   // This includes arrays of objects with address space qualifiers, but not
   // automatic variables that point to other address spaces.
   // ISO/IEC TR 18037 S5.1.2
   if (!getLangOpts().OpenCL && NewVD->hasLocalStorage() &&
       T.getAddressSpace() != LangAS::Default) {
     Diag(NewVD->getLocation(), diag::err_as_qualified_auto_decl) << 0;
     NewVD->setInvalidDecl();
     return;
   }
 
   // OpenCL v1.2 s6.8 - The static qualifier is valid only in program
   // scope.
   if (getLangOpts().OpenCLVersion == 120 &&
       !getOpenCLOptions().isAvailableOption("cl_clang_storage_class_specifiers",
                                             getLangOpts()) &&
       NewVD->isStaticLocal()) {
     Diag(NewVD->getLocation(), diag::err_static_function_scope);
     NewVD->setInvalidDecl();
     return;
   }
 
   if (getLangOpts().OpenCL) {
     if (!diagnoseOpenCLTypes(*this, NewVD))
       return;
 
     // OpenCL v2.0 s6.12.5 - The __block storage type is not supported.
     if (NewVD->hasAttr<BlocksAttr>()) {
       Diag(NewVD->getLocation(), diag::err_opencl_block_storage_type);
       return;
     }
 
     if (T->isBlockPointerType()) {
       // OpenCL v2.0 s6.12.5 - Any block declaration must be const qualified and
       // can't use 'extern' storage class.
       if (!T.isConstQualified()) {
         Diag(NewVD->getLocation(), diag::err_opencl_invalid_block_declaration)
             << 0 /*const*/;
         NewVD->setInvalidDecl();
         return;
       }
       if (NewVD->hasExternalStorage()) {
         Diag(NewVD->getLocation(), diag::err_opencl_extern_block_declaration);
         NewVD->setInvalidDecl();
         return;
       }
     }
 
     // FIXME: Adding local AS in C++ for OpenCL might make sense.
     if (NewVD->isFileVarDecl() || NewVD->isStaticLocal() ||
         NewVD->hasExternalStorage()) {
       if (!T->isSamplerT() && !T->isDependentType() &&
           !(T.getAddressSpace() == LangAS::opencl_constant ||
             (T.getAddressSpace() == LangAS::opencl_global &&
              getOpenCLOptions().areProgramScopeVariablesSupported(
                  getLangOpts())))) {
         int Scope = NewVD->isStaticLocal() | NewVD->hasExternalStorage() << 1;
         if (getOpenCLOptions().areProgramScopeVariablesSupported(getLangOpts()))
           Diag(NewVD->getLocation(), diag::err_opencl_global_invalid_addr_space)
               << Scope << "global or constant";
         else
           Diag(NewVD->getLocation(), diag::err_opencl_global_invalid_addr_space)
               << Scope << "constant";
         NewVD->setInvalidDecl();
         return;
       }
     } else {
       if (T.getAddressSpace() == LangAS::opencl_global) {
         Diag(NewVD->getLocation(), diag::err_opencl_function_variable)
             << 1 /*is any function*/ << "global";
         NewVD->setInvalidDecl();
         return;
       }
       if (T.getAddressSpace() == LangAS::opencl_constant ||
           T.getAddressSpace() == LangAS::opencl_local) {
         FunctionDecl *FD = getCurFunctionDecl();
         // OpenCL v1.1 s6.5.2 and s6.5.3: no local or constant variables
         // in functions.
         if (FD && !FD->hasAttr<OpenCLKernelAttr>()) {
           if (T.getAddressSpace() == LangAS::opencl_constant)
             Diag(NewVD->getLocation(), diag::err_opencl_function_variable)
                 << 0 /*non-kernel only*/ << "constant";
           else
             Diag(NewVD->getLocation(), diag::err_opencl_function_variable)
                 << 0 /*non-kernel only*/ << "local";
           NewVD->setInvalidDecl();
           return;
         }
         // OpenCL v2.0 s6.5.2 and s6.5.3: local and constant variables must be
         // in the outermost scope of a kernel function.
         if (FD && FD->hasAttr<OpenCLKernelAttr>()) {
           if (!getCurScope()->isFunctionScope()) {
             if (T.getAddressSpace() == LangAS::opencl_constant)
               Diag(NewVD->getLocation(), diag::err_opencl_addrspace_scope)
                   << "constant";
             else
               Diag(NewVD->getLocation(), diag::err_opencl_addrspace_scope)
                   << "local";
             NewVD->setInvalidDecl();
             return;
           }
         }
       } else if (T.getAddressSpace() != LangAS::opencl_private &&
                  // If we are parsing a template we didn't deduce an addr
                  // space yet.
                  T.getAddressSpace() != LangAS::Default) {
         // Do not allow other address spaces on automatic variable.
         Diag(NewVD->getLocation(), diag::err_as_qualified_auto_decl) << 1;
         NewVD->setInvalidDecl();
         return;
       }
     }
   }
 
   if (NewVD->hasLocalStorage() && T.isObjCGCWeak()
       && !NewVD->hasAttr<BlocksAttr>()) {
     if (getLangOpts().getGC() != LangOptions::NonGC)
       Diag(NewVD->getLocation(), diag::warn_gc_attribute_weak_on_local);
     else {
       assert(!getLangOpts().ObjCAutoRefCount);
       Diag(NewVD->getLocation(), diag::warn_attribute_weak_on_local);
     }
   }
 
   // WebAssembly tables must be static with a zero length and can't be
   // declared within functions.
   if (T->isWebAssemblyTableType()) {
     if (getCurScope()->getParent()) { // Parent is null at top-level
       Diag(NewVD->getLocation(), diag::err_wasm_table_in_function);
       NewVD->setInvalidDecl();
       return;
     }
     if (NewVD->getStorageClass() != SC_Static) {
       Diag(NewVD->getLocation(), diag::err_wasm_table_must_be_static);
       NewVD->setInvalidDecl();
       return;
     }
     const auto *ATy = dyn_cast<ConstantArrayType>(T.getTypePtr());
     if (!ATy || ATy->getSize().getSExtValue() != 0) {
       Diag(NewVD->getLocation(),
            diag::err_typecheck_wasm_table_must_have_zero_length);
       NewVD->setInvalidDecl();
       return;
     }
   }
 
   bool isVM = T->isVariablyModifiedType();
   if (isVM || NewVD->hasAttr<CleanupAttr>() ||
       NewVD->hasAttr<BlocksAttr>())
     setFunctionHasBranchProtectedScope();
 
   if ((isVM && NewVD->hasLinkage()) ||
       (T->isVariableArrayType() && NewVD->hasGlobalStorage())) {
     bool SizeIsNegative;
     llvm::APSInt Oversized;
     TypeSourceInfo *FixedTInfo = TryToFixInvalidVariablyModifiedTypeSourceInfo(
         NewVD->getTypeSourceInfo(), Context, SizeIsNegative, Oversized);
     QualType FixedT;
     if (FixedTInfo &&  T == NewVD->getTypeSourceInfo()->getType())
       FixedT = FixedTInfo->getType();
     else if (FixedTInfo) {
       // Type and type-as-written are canonically different. We need to fix up
       // both types separately.
       FixedT = TryToFixInvalidVariablyModifiedType(T, Context, SizeIsNegative,
                                                    Oversized);
     }
     if ((!FixedTInfo || FixedT.isNull()) && T->isVariableArrayType()) {
       const VariableArrayType *VAT = Context.getAsVariableArrayType(T);
       // FIXME: This won't give the correct result for
       // int a[10][n];
       SourceRange SizeRange = VAT->getSizeExpr()->getSourceRange();
 
       if (NewVD->isFileVarDecl())
         Diag(NewVD->getLocation(), diag::err_vla_decl_in_file_scope)
         << SizeRange;
       else if (NewVD->isStaticLocal())
         Diag(NewVD->getLocation(), diag::err_vla_decl_has_static_storage)
         << SizeRange;
       else
         Diag(NewVD->getLocation(), diag::err_vla_decl_has_extern_linkage)
         << SizeRange;
       NewVD->setInvalidDecl();
       return;
     }
 
     if (!FixedTInfo) {
       if (NewVD->isFileVarDecl())
         Diag(NewVD->getLocation(), diag::err_vm_decl_in_file_scope);
       else
         Diag(NewVD->getLocation(), diag::err_vm_decl_has_extern_linkage);
       NewVD->setInvalidDecl();
       return;
     }
 
     Diag(NewVD->getLocation(), diag::ext_vla_folded_to_constant);
     NewVD->setType(FixedT);
     NewVD->setTypeSourceInfo(FixedTInfo);
   }
 
   if (T->isVoidType()) {
     // C++98 [dcl.stc]p5: The extern specifier can be applied only to the names
     //                    of objects and functions.
     if (NewVD->isThisDeclarationADefinition() || getLangOpts().CPlusPlus) {
       Diag(NewVD->getLocation(), diag::err_typecheck_decl_incomplete_type)
         << T;
       NewVD->setInvalidDecl();
       return;
     }
   }
 
   if (!NewVD->hasLocalStorage() && NewVD->hasAttr<BlocksAttr>()) {
     Diag(NewVD->getLocation(), diag::err_block_on_nonlocal);
     NewVD->setInvalidDecl();
     return;
   }
 
   if (!NewVD->hasLocalStorage() && T->isSizelessType() &&
       !T.isWebAssemblyReferenceType()) {
     Diag(NewVD->getLocation(), diag::err_sizeless_nonlocal) << T;
     NewVD->setInvalidDecl();
     return;
   }
 
   if (isVM && NewVD->hasAttr<BlocksAttr>()) {
     Diag(NewVD->getLocation(), diag::err_block_on_vm);
     NewVD->setInvalidDecl();
     return;
   }
 
   if (NewVD->isConstexpr() && !T->isDependentType() &&
       RequireLiteralType(NewVD->getLocation(), T,
                          diag::err_constexpr_var_non_literal)) {
     NewVD->setInvalidDecl();
     return;
   }
 
   // PPC MMA non-pointer types are not allowed as non-local variable types.
   if (Context.getTargetInfo().getTriple().isPPC64() &&
       !NewVD->isLocalVarDecl() &&
       CheckPPCMMAType(T, NewVD->getLocation())) {
     NewVD->setInvalidDecl();
     return;
   }
 
   // Check that SVE types are only used in functions with SVE available.
   if (T->isSVESizelessBuiltinType() && isa<FunctionDecl>(CurContext)) {
     const FunctionDecl *FD = cast<FunctionDecl>(CurContext);
     llvm::StringMap<bool> CallerFeatureMap;
     Context.getFunctionFeatureMap(CallerFeatureMap, FD);
     if (!Builtin::evaluateRequiredTargetFeatures(
         "sve", CallerFeatureMap)) {
       Diag(NewVD->getLocation(), diag::err_sve_vector_in_non_sve_target) << T;
       NewVD->setInvalidDecl();
       return;
     }
   }
 
   if (T->isRVVType())
     checkRVVTypeSupport(T, NewVD->getLocation(), cast<ValueDecl>(CurContext));
 }
 
 /// Perform semantic checking on a newly-created variable
 /// declaration.
 ///
 /// This routine performs all of the type-checking required for a
 /// variable declaration once it has been built. It is used both to
 /// check variables after they have been parsed and their declarators
 /// have been translated into a declaration, and to check variables
 /// that have been instantiated from a template.
 ///
 /// Sets NewVD->isInvalidDecl() if an error was encountered.
 ///
 /// Returns true if the variable declaration is a redeclaration.
 bool Sema::CheckVariableDeclaration(VarDecl *NewVD, LookupResult &Previous) {
   CheckVariableDeclarationType(NewVD);
 
   // If the decl is already known invalid, don't check it.
   if (NewVD->isInvalidDecl())
     return false;
 
   // If we did not find anything by this name, look for a non-visible
   // extern "C" declaration with the same name.
   if (Previous.empty() &&
       checkForConflictWithNonVisibleExternC(*this, NewVD, Previous))
     Previous.setShadowed();
 
   if (!Previous.empty()) {
     MergeVarDecl(NewVD, Previous);
     return true;
   }
   return false;
 }
 
 /// AddOverriddenMethods - See if a method overrides any in the base classes,
 /// and if so, check that it's a valid override and remember it.
 bool Sema::AddOverriddenMethods(CXXRecordDecl *DC, CXXMethodDecl *MD) {
   llvm::SmallPtrSet<const CXXMethodDecl*, 4> Overridden;
 
   // Look for methods in base classes that this method might override.
   CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/false,
                      /*DetectVirtual=*/false);
   auto VisitBase = [&] (const CXXBaseSpecifier *Specifier, CXXBasePath &Path) {
     CXXRecordDecl *BaseRecord = Specifier->getType()->getAsCXXRecordDecl();
     DeclarationName Name = MD->getDeclName();
 
     if (Name.getNameKind() == DeclarationName::CXXDestructorName) {
       // We really want to find the base class destructor here.
       QualType T = Context.getTypeDeclType(BaseRecord);
       CanQualType CT = Context.getCanonicalType(T);
       Name = Context.DeclarationNames.getCXXDestructorName(CT);
     }
 
     for (NamedDecl *BaseND : BaseRecord->lookup(Name)) {
       CXXMethodDecl *BaseMD =
           dyn_cast<CXXMethodDecl>(BaseND->getCanonicalDecl());
       if (!BaseMD || !BaseMD->isVirtual() ||
           IsOverload(MD, BaseMD, /*UseMemberUsingDeclRules=*/false,
                      /*ConsiderCudaAttrs=*/true,
                      // C++2a [class.virtual]p2 does not consider requires
                      // clauses when overriding.
                      /*ConsiderRequiresClauses=*/false))
         continue;
 
       if (Overridden.insert(BaseMD).second) {
         MD->addOverriddenMethod(BaseMD);
         CheckOverridingFunctionReturnType(MD, BaseMD);
         CheckOverridingFunctionAttributes(MD, BaseMD);
         CheckOverridingFunctionExceptionSpec(MD, BaseMD);
         CheckIfOverriddenFunctionIsMarkedFinal(MD, BaseMD);
       }
 
       // A method can only override one function from each base class. We
       // don't track indirectly overridden methods from bases of bases.
       return true;
     }
 
     return false;
   };
 
   DC->lookupInBases(VisitBase, Paths);
   return !Overridden.empty();
 }
 
 namespace {
   // Struct for holding all of the extra arguments needed by
   // DiagnoseInvalidRedeclaration to call Sema::ActOnFunctionDeclarator.
   struct ActOnFDArgs {
     Scope *S;
     Declarator &D;
     MultiTemplateParamsArg TemplateParamLists;
     bool AddToScope;
   };
 } // end anonymous namespace
 
 namespace {
 
 // Callback to only accept typo corrections that have a non-zero edit distance.
 // Also only accept corrections that have the same parent decl.
 class DifferentNameValidatorCCC final : public CorrectionCandidateCallback {
  public:
   DifferentNameValidatorCCC(ASTContext &Context, FunctionDecl *TypoFD,
                             CXXRecordDecl *Parent)
       : Context(Context), OriginalFD(TypoFD),
         ExpectedParent(Parent ? Parent->getCanonicalDecl() : nullptr) {}
 
   bool ValidateCandidate(const TypoCorrection &candidate) override {
     if (candidate.getEditDistance() == 0)
       return false;
 
     SmallVector<unsigned, 1> MismatchedParams;
     for (TypoCorrection::const_decl_iterator CDecl = candidate.begin(),
                                           CDeclEnd = candidate.end();
          CDecl != CDeclEnd; ++CDecl) {
       FunctionDecl *FD = dyn_cast<FunctionDecl>(*CDecl);
 
       if (FD && !FD->hasBody() &&
           hasSimilarParameters(Context, FD, OriginalFD, MismatchedParams)) {
         if (CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD)) {
           CXXRecordDecl *Parent = MD->getParent();
           if (Parent && Parent->getCanonicalDecl() == ExpectedParent)
             return true;
         } else if (!ExpectedParent) {
           return true;
         }
       }
     }
 
     return false;
   }
 
   std::unique_ptr<CorrectionCandidateCallback> clone() override {
     return std::make_unique<DifferentNameValidatorCCC>(*this);
   }
 
  private:
   ASTContext &Context;
   FunctionDecl *OriginalFD;
   CXXRecordDecl *ExpectedParent;
 };
 
 } // end anonymous namespace
 
 void Sema::MarkTypoCorrectedFunctionDefinition(const NamedDecl *F) {
   TypoCorrectedFunctionDefinitions.insert(F);
 }
 
 /// Generate diagnostics for an invalid function redeclaration.
 ///
 /// This routine handles generating the diagnostic messages for an invalid
 /// function redeclaration, including finding possible similar declarations
 /// or performing typo correction if there are no previous declarations with
 /// the same name.
 ///
 /// Returns a NamedDecl iff typo correction was performed and substituting in
 /// the new declaration name does not cause new errors.
 static NamedDecl *DiagnoseInvalidRedeclaration(
     Sema &SemaRef, LookupResult &Previous, FunctionDecl *NewFD,
     ActOnFDArgs &ExtraArgs, bool IsLocalFriend, Scope *S) {
   DeclarationName Name = NewFD->getDeclName();
   DeclContext *NewDC = NewFD->getDeclContext();
   SmallVector<unsigned, 1> MismatchedParams;
   SmallVector<std::pair<FunctionDecl *, unsigned>, 1> NearMatches;
   TypoCorrection Correction;
   bool IsDefinition = ExtraArgs.D.isFunctionDefinition();
   unsigned DiagMsg =
     IsLocalFriend ? diag::err_no_matching_local_friend :
     NewFD->getFriendObjectKind() ? diag::err_qualified_friend_no_match :
     diag::err_member_decl_does_not_match;
   LookupResult Prev(SemaRef, Name, NewFD->getLocation(),
                     IsLocalFriend ? Sema::LookupLocalFriendName
                                   : Sema::LookupOrdinaryName,
                     Sema::ForVisibleRedeclaration);
 
   NewFD->setInvalidDecl();
   if (IsLocalFriend)
     SemaRef.LookupName(Prev, S);
   else
     SemaRef.LookupQualifiedName(Prev, NewDC);
   assert(!Prev.isAmbiguous() &&
          "Cannot have an ambiguity in previous-declaration lookup");
   CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(NewFD);
   DifferentNameValidatorCCC CCC(SemaRef.Context, NewFD,
                                 MD ? MD->getParent() : nullptr);
   if (!Prev.empty()) {
     for (LookupResult::iterator Func = Prev.begin(), FuncEnd = Prev.end();
          Func != FuncEnd; ++Func) {
       FunctionDecl *FD = dyn_cast<FunctionDecl>(*Func);
       if (FD &&
           hasSimilarParameters(SemaRef.Context, FD, NewFD, MismatchedParams)) {
         // Add 1 to the index so that 0 can mean the mismatch didn't
         // involve a parameter
         unsigned ParamNum =
             MismatchedParams.empty() ? 0 : MismatchedParams.front() + 1;
         NearMatches.push_back(std::make_pair(FD, ParamNum));
       }
     }
   // If the qualified name lookup yielded nothing, try typo correction
   } else if ((Correction = SemaRef.CorrectTypo(
                   Prev.getLookupNameInfo(), Prev.getLookupKind(), S,
                   &ExtraArgs.D.getCXXScopeSpec(), CCC, Sema::CTK_ErrorRecovery,
                   IsLocalFriend ? nullptr : NewDC))) {
     // Set up everything for the call to ActOnFunctionDeclarator
     ExtraArgs.D.SetIdentifier(Correction.getCorrectionAsIdentifierInfo(),
                               ExtraArgs.D.getIdentifierLoc());
     Previous.clear();
     Previous.setLookupName(Correction.getCorrection());
     for (TypoCorrection::decl_iterator CDecl = Correction.begin(),
                                     CDeclEnd = Correction.end();
          CDecl != CDeclEnd; ++CDecl) {
       FunctionDecl *FD = dyn_cast<FunctionDecl>(*CDecl);
       if (FD && !FD->hasBody() &&
           hasSimilarParameters(SemaRef.Context, FD, NewFD, MismatchedParams)) {
         Previous.addDecl(FD);
       }
     }
     bool wasRedeclaration = ExtraArgs.D.isRedeclaration();
 
     NamedDecl *Result;
     // Retry building the function declaration with the new previous
     // declarations, and with errors suppressed.
     {
       // Trap errors.
       Sema::SFINAETrap Trap(SemaRef);
 
       // TODO: Refactor ActOnFunctionDeclarator so that we can call only the
       // pieces need to verify the typo-corrected C++ declaration and hopefully
       // eliminate the need for the parameter pack ExtraArgs.
       Result = SemaRef.ActOnFunctionDeclarator(
           ExtraArgs.S, ExtraArgs.D,
           Correction.getCorrectionDecl()->getDeclContext(),
           NewFD->getTypeSourceInfo(), Previous, ExtraArgs.TemplateParamLists,
           ExtraArgs.AddToScope);
 
       if (Trap.hasErrorOccurred())
         Result = nullptr;
     }
 
     if (Result) {
       // Determine which correction we picked.
       Decl *Canonical = Result->getCanonicalDecl();
       for (LookupResult::iterator I = Previous.begin(), E = Previous.end();
            I != E; ++I)
         if ((*I)->getCanonicalDecl() == Canonical)
           Correction.setCorrectionDecl(*I);
 
       // Let Sema know about the correction.
       SemaRef.MarkTypoCorrectedFunctionDefinition(Result);
       SemaRef.diagnoseTypo(
           Correction,
           SemaRef.PDiag(IsLocalFriend
                           ? diag::err_no_matching_local_friend_suggest
                           : diag::err_member_decl_does_not_match_suggest)
             << Name << NewDC << IsDefinition);
       return Result;
     }
 
     // Pretend the typo correction never occurred
     ExtraArgs.D.SetIdentifier(Name.getAsIdentifierInfo(),
                               ExtraArgs.D.getIdentifierLoc());
     ExtraArgs.D.setRedeclaration(wasRedeclaration);
     Previous.clear();
     Previous.setLookupName(Name);
   }
 
   SemaRef.Diag(NewFD->getLocation(), DiagMsg)
       << Name << NewDC << IsDefinition << NewFD->getLocation();
 
   bool NewFDisConst = false;
   if (CXXMethodDecl *NewMD = dyn_cast<CXXMethodDecl>(NewFD))
     NewFDisConst = NewMD->isConst();
 
   for (SmallVectorImpl<std::pair<FunctionDecl *, unsigned> >::iterator
        NearMatch = NearMatches.begin(), NearMatchEnd = NearMatches.end();
        NearMatch != NearMatchEnd; ++NearMatch) {
     FunctionDecl *FD = NearMatch->first;
     CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD);
     bool FDisConst = MD && MD->isConst();
     bool IsMember = MD || !IsLocalFriend;
 
     // FIXME: These notes are poorly worded for the local friend case.
     if (unsigned Idx = NearMatch->second) {
       ParmVarDecl *FDParam = FD->getParamDecl(Idx-1);
       SourceLocation Loc = FDParam->getTypeSpecStartLoc();
       if (Loc.isInvalid()) Loc = FD->getLocation();
       SemaRef.Diag(Loc, IsMember ? diag::note_member_def_close_param_match
                                  : diag::note_local_decl_close_param_match)
         << Idx << FDParam->getType()
         << NewFD->getParamDecl(Idx - 1)->getType();
     } else if (FDisConst != NewFDisConst) {
       SemaRef.Diag(FD->getLocation(), diag::note_member_def_close_const_match)
           << NewFDisConst << FD->getSourceRange().getEnd()
           << (NewFDisConst
                   ? FixItHint::CreateRemoval(ExtraArgs.D.getFunctionTypeInfo()
                                                  .getConstQualifierLoc())
                   : FixItHint::CreateInsertion(ExtraArgs.D.getFunctionTypeInfo()
                                                    .getRParenLoc()
                                                    .getLocWithOffset(1),
                                                " const"));
     } else
       SemaRef.Diag(FD->getLocation(),
                    IsMember ? diag::note_member_def_close_match
                             : diag::note_local_decl_close_match);
   }
   return nullptr;
 }
 
 static StorageClass getFunctionStorageClass(Sema &SemaRef, Declarator &D) {
   switch (D.getDeclSpec().getStorageClassSpec()) {
   default: llvm_unreachable("Unknown storage class!");
   case DeclSpec::SCS_auto:
   case DeclSpec::SCS_register:
   case DeclSpec::SCS_mutable:
     SemaRef.Diag(D.getDeclSpec().getStorageClassSpecLoc(),
                  diag::err_typecheck_sclass_func);
     D.getMutableDeclSpec().ClearStorageClassSpecs();
     D.setInvalidType();
     break;
   case DeclSpec::SCS_unspecified: break;
   case DeclSpec::SCS_extern:
     if (D.getDeclSpec().isExternInLinkageSpec())
       return SC_None;
     return SC_Extern;
   case DeclSpec::SCS_static: {
     if (SemaRef.CurContext->getRedeclContext()->isFunctionOrMethod()) {
       // C99 6.7.1p5:
       //   The declaration of an identifier for a function that has
       //   block scope shall have no explicit storage-class specifier
       //   other than extern
       // See also (C++ [dcl.stc]p4).
       SemaRef.Diag(D.getDeclSpec().getStorageClassSpecLoc(),
                    diag::err_static_block_func);
       break;
     } else
       return SC_Static;
   }
   case DeclSpec::SCS_private_extern: return SC_PrivateExtern;
   }
 
   // No explicit storage class has already been returned
   return SC_None;
 }
 
 static FunctionDecl *CreateNewFunctionDecl(Sema &SemaRef, Declarator &D,
                                            DeclContext *DC, QualType &R,
                                            TypeSourceInfo *TInfo,
                                            StorageClass SC,
                                            bool &IsVirtualOkay) {
   DeclarationNameInfo NameInfo = SemaRef.GetNameForDeclarator(D);
   DeclarationName Name = NameInfo.getName();
 
   FunctionDecl *NewFD = nullptr;
   bool isInline = D.getDeclSpec().isInlineSpecified();
 
   if (!SemaRef.getLangOpts().CPlusPlus) {
     // Determine whether the function was written with a prototype. This is
     // true when:
     //   - there is a prototype in the declarator, or
     //   - the type R of the function is some kind of typedef or other non-
     //     attributed reference to a type name (which eventually refers to a
     //     function type). Note, we can't always look at the adjusted type to
     //     check this case because attributes may cause a non-function
     //     declarator to still have a function type. e.g.,
     //       typedef void func(int a);
     //       __attribute__((noreturn)) func other_func; // This has a prototype
     bool HasPrototype =
         (D.isFunctionDeclarator() && D.getFunctionTypeInfo().hasPrototype) ||
         (D.getDeclSpec().isTypeRep() &&
          SemaRef.GetTypeFromParser(D.getDeclSpec().getRepAsType(), nullptr)
              ->isFunctionProtoType()) ||
         (!R->getAsAdjusted<FunctionType>() && R->isFunctionProtoType());
     assert(
         (HasPrototype || !SemaRef.getLangOpts().requiresStrictPrototypes()) &&
         "Strict prototypes are required");
 
     NewFD = FunctionDecl::Create(
         SemaRef.Context, DC, D.getBeginLoc(), NameInfo, R, TInfo, SC,
         SemaRef.getCurFPFeatures().isFPConstrained(), isInline, HasPrototype,
         ConstexprSpecKind::Unspecified,
         /*TrailingRequiresClause=*/nullptr);
     if (D.isInvalidType())
       NewFD->setInvalidDecl();
 
     return NewFD;
   }
 
   ExplicitSpecifier ExplicitSpecifier = D.getDeclSpec().getExplicitSpecifier();
 
   ConstexprSpecKind ConstexprKind = D.getDeclSpec().getConstexprSpecifier();
   if (ConstexprKind == ConstexprSpecKind::Constinit) {
     SemaRef.Diag(D.getDeclSpec().getConstexprSpecLoc(),
                  diag::err_constexpr_wrong_decl_kind)
         << static_cast<int>(ConstexprKind);
     ConstexprKind = ConstexprSpecKind::Unspecified;
     D.getMutableDeclSpec().ClearConstexprSpec();
   }
   Expr *TrailingRequiresClause = D.getTrailingRequiresClause();
 
   if (Name.getNameKind() == DeclarationName::CXXConstructorName) {
     // This is a C++ constructor declaration.
     assert(DC->isRecord() &&
            "Constructors can only be declared in a member context");
 
     R = SemaRef.CheckConstructorDeclarator(D, R, SC);
     return CXXConstructorDecl::Create(
         SemaRef.Context, cast<CXXRecordDecl>(DC), D.getBeginLoc(), NameInfo, R,
         TInfo, ExplicitSpecifier, SemaRef.getCurFPFeatures().isFPConstrained(),
         isInline, /*isImplicitlyDeclared=*/false, ConstexprKind,
         InheritedConstructor(), TrailingRequiresClause);
 
   } else if (Name.getNameKind() == DeclarationName::CXXDestructorName) {
     // This is a C++ destructor declaration.
     if (DC->isRecord()) {
       R = SemaRef.CheckDestructorDeclarator(D, R, SC);
       CXXRecordDecl *Record = cast<CXXRecordDecl>(DC);
       CXXDestructorDecl *NewDD = CXXDestructorDecl::Create(
           SemaRef.Context, Record, D.getBeginLoc(), NameInfo, R, TInfo,
           SemaRef.getCurFPFeatures().isFPConstrained(), isInline,
           /*isImplicitlyDeclared=*/false, ConstexprKind,
           TrailingRequiresClause);
       // User defined destructors start as not selected if the class definition is still
       // not done.
       if (Record->isBeingDefined())
         NewDD->setIneligibleOrNotSelected(true);
 
       // If the destructor needs an implicit exception specification, set it
       // now. FIXME: It'd be nice to be able to create the right type to start
       // with, but the type needs to reference the destructor declaration.
       if (SemaRef.getLangOpts().CPlusPlus11)
         SemaRef.AdjustDestructorExceptionSpec(NewDD);
 
       IsVirtualOkay = true;
       return NewDD;
 
     } else {
       SemaRef.Diag(D.getIdentifierLoc(), diag::err_destructor_not_member);
       D.setInvalidType();
 
       // Create a FunctionDecl to satisfy the function definition parsing
       // code path.
       return FunctionDecl::Create(
           SemaRef.Context, DC, D.getBeginLoc(), D.getIdentifierLoc(), Name, R,
           TInfo, SC, SemaRef.getCurFPFeatures().isFPConstrained(), isInline,
           /*hasPrototype=*/true, ConstexprKind, TrailingRequiresClause);
     }
 
   } else if (Name.getNameKind() == DeclarationName::CXXConversionFunctionName) {
     if (!DC->isRecord()) {
       SemaRef.Diag(D.getIdentifierLoc(),
            diag::err_conv_function_not_member);
       return nullptr;
     }
 
     SemaRef.CheckConversionDeclarator(D, R, SC);
     if (D.isInvalidType())
       return nullptr;
 
     IsVirtualOkay = true;
     return CXXConversionDecl::Create(
         SemaRef.Context, cast<CXXRecordDecl>(DC), D.getBeginLoc(), NameInfo, R,
         TInfo, SemaRef.getCurFPFeatures().isFPConstrained(), isInline,
         ExplicitSpecifier, ConstexprKind, SourceLocation(),
         TrailingRequiresClause);
 
   } else if (Name.getNameKind() == DeclarationName::CXXDeductionGuideName) {
     if (TrailingRequiresClause)
       SemaRef.Diag(TrailingRequiresClause->getBeginLoc(),
                    diag::err_trailing_requires_clause_on_deduction_guide)
           << TrailingRequiresClause->getSourceRange();
     if (SemaRef.CheckDeductionGuideDeclarator(D, R, SC))
       return nullptr;
     return CXXDeductionGuideDecl::Create(SemaRef.Context, DC, D.getBeginLoc(),
                                          ExplicitSpecifier, NameInfo, R, TInfo,
                                          D.getEndLoc());
   } else if (DC->isRecord()) {
     // If the name of the function is the same as the name of the record,
     // then this must be an invalid constructor that has a return type.
     // (The parser checks for a return type and makes the declarator a
     // constructor if it has no return type).
     if (Name.getAsIdentifierInfo() &&
         Name.getAsIdentifierInfo() == cast<CXXRecordDecl>(DC)->getIdentifier()){
       SemaRef.Diag(D.getIdentifierLoc(), diag::err_constructor_return_type)
         << SourceRange(D.getDeclSpec().getTypeSpecTypeLoc())
         << SourceRange(D.getIdentifierLoc());
       return nullptr;
     }
 
     // This is a C++ method declaration.
     CXXMethodDecl *Ret = CXXMethodDecl::Create(
         SemaRef.Context, cast<CXXRecordDecl>(DC), D.getBeginLoc(), NameInfo, R,
         TInfo, SC, SemaRef.getCurFPFeatures().isFPConstrained(), isInline,
         ConstexprKind, SourceLocation(), TrailingRequiresClause);
     IsVirtualOkay = !Ret->isStatic();
     return Ret;
   } else {
     bool isFriend =
         SemaRef.getLangOpts().CPlusPlus && D.getDeclSpec().isFriendSpecified();
     if (!isFriend && SemaRef.CurContext->isRecord())
       return nullptr;
 
     // Determine whether the function was written with a
     // prototype. This true when:
     //   - we're in C++ (where every function has a prototype),
     return FunctionDecl::Create(
         SemaRef.Context, DC, D.getBeginLoc(), NameInfo, R, TInfo, SC,
         SemaRef.getCurFPFeatures().isFPConstrained(), isInline,
         true /*HasPrototype*/, ConstexprKind, TrailingRequiresClause);
   }
 }
 
 enum OpenCLParamType {
   ValidKernelParam,
   PtrPtrKernelParam,
   PtrKernelParam,
   InvalidAddrSpacePtrKernelParam,
   InvalidKernelParam,
   RecordKernelParam
 };
 
 static bool isOpenCLSizeDependentType(ASTContext &C, QualType Ty) {
   // Size dependent types are just typedefs to normal integer types
   // (e.g. unsigned long), so we cannot distinguish them from other typedefs to
   // integers other than by their names.
   StringRef SizeTypeNames[] = {"size_t", "intptr_t", "uintptr_t", "ptrdiff_t"};
 
   // Remove typedefs one by one until we reach a typedef
   // for a size dependent type.
   QualType DesugaredTy = Ty;
   do {
     ArrayRef<StringRef> Names(SizeTypeNames);
     auto Match = llvm::find(Names, DesugaredTy.getUnqualifiedType().getAsString());
     if (Names.end() != Match)
       return true;
 
     Ty = DesugaredTy;
     DesugaredTy = Ty.getSingleStepDesugaredType(C);
   } while (DesugaredTy != Ty);
 
   return false;
 }
 
 static OpenCLParamType getOpenCLKernelParameterType(Sema &S, QualType PT) {
   if (PT->isDependentType())
     return InvalidKernelParam;
 
   if (PT->isPointerType() || PT->isReferenceType()) {
     QualType PointeeType = PT->getPointeeType();
     if (PointeeType.getAddressSpace() == LangAS::opencl_generic ||
         PointeeType.getAddressSpace() == LangAS::opencl_private ||
         PointeeType.getAddressSpace() == LangAS::Default)
       return InvalidAddrSpacePtrKernelParam;
 
     if (PointeeType->isPointerType()) {
       // This is a pointer to pointer parameter.
       // Recursively check inner type.
       OpenCLParamType ParamKind = getOpenCLKernelParameterType(S, PointeeType);
       if (ParamKind == InvalidAddrSpacePtrKernelParam ||
           ParamKind == InvalidKernelParam)
         return ParamKind;
 
       // OpenCL v3.0 s6.11.a:
       // A restriction to pass pointers to pointers only applies to OpenCL C
       // v1.2 or below.
       if (S.getLangOpts().getOpenCLCompatibleVersion() > 120)
         return ValidKernelParam;
 
       return PtrPtrKernelParam;
     }
 
     // C++ for OpenCL v1.0 s2.4:
     // Moreover the types used in parameters of the kernel functions must be:
     // Standard layout types for pointer parameters. The same applies to
     // reference if an implementation supports them in kernel parameters.
     if (S.getLangOpts().OpenCLCPlusPlus &&
         !S.getOpenCLOptions().isAvailableOption(
             "__cl_clang_non_portable_kernel_param_types", S.getLangOpts())) {
      auto CXXRec = PointeeType.getCanonicalType()->getAsCXXRecordDecl();
      bool IsStandardLayoutType = true;
      if (CXXRec) {
        // If template type is not ODR-used its definition is only available
        // in the template definition not its instantiation.
        // FIXME: This logic doesn't work for types that depend on template
        // parameter (PR58590).
        if (!CXXRec->hasDefinition())
          CXXRec = CXXRec->getTemplateInstantiationPattern();
        if (!CXXRec || !CXXRec->hasDefinition() || !CXXRec->isStandardLayout())
          IsStandardLayoutType = false;
      }
      if (!PointeeType->isAtomicType() && !PointeeType->isVoidType() &&
         !IsStandardLayoutType)
       return InvalidKernelParam;
     }
 
     // OpenCL v1.2 s6.9.p:
     // A restriction to pass pointers only applies to OpenCL C v1.2 or below.
     if (S.getLangOpts().getOpenCLCompatibleVersion() > 120)
       return ValidKernelParam;
 
     return PtrKernelParam;
   }
 
   // OpenCL v1.2 s6.9.k:
   // Arguments to kernel functions in a program cannot be declared with the
   // built-in scalar types bool, half, size_t, ptrdiff_t, intptr_t, and
   // uintptr_t or a struct and/or union that contain fields declared to be one
   // of these built-in scalar types.
   if (isOpenCLSizeDependentType(S.getASTContext(), PT))
     return InvalidKernelParam;
 
   if (PT->isImageType())
     return PtrKernelParam;
 
   if (PT->isBooleanType() || PT->isEventT() || PT->isReserveIDT())
     return InvalidKernelParam;
 
   // OpenCL extension spec v1.2 s9.5:
   // This extension adds support for half scalar and vector types as built-in
   // types that can be used for arithmetic operations, conversions etc.
   if (!S.getOpenCLOptions().isAvailableOption("cl_khr_fp16", S.getLangOpts()) &&
       PT->isHalfType())
     return InvalidKernelParam;
 
   // Look into an array argument to check if it has a forbidden type.
   if (PT->isArrayType()) {
     const Type *UnderlyingTy = PT->getPointeeOrArrayElementType();
     // Call ourself to check an underlying type of an array. Since the
     // getPointeeOrArrayElementType returns an innermost type which is not an
     // array, this recursive call only happens once.
     return getOpenCLKernelParameterType(S, QualType(UnderlyingTy, 0));
   }
 
   // C++ for OpenCL v1.0 s2.4:
   // Moreover the types used in parameters of the kernel functions must be:
   // Trivial and standard-layout types C++17 [basic.types] (plain old data
   // types) for parameters passed by value;
   if (S.getLangOpts().OpenCLCPlusPlus &&
       !S.getOpenCLOptions().isAvailableOption(
           "__cl_clang_non_portable_kernel_param_types", S.getLangOpts()) &&
       !PT->isOpenCLSpecificType() && !PT.isPODType(S.Context))
     return InvalidKernelParam;
 
   if (PT->isRecordType())
     return RecordKernelParam;
 
   return ValidKernelParam;
 }
 
 static void checkIsValidOpenCLKernelParameter(
   Sema &S,
   Declarator &D,
   ParmVarDecl *Param,
   llvm::SmallPtrSetImpl<const Type *> &ValidTypes) {
   QualType PT = Param->getType();
 
   // Cache the valid types we encounter to avoid rechecking structs that are
   // used again
   if (ValidTypes.count(PT.getTypePtr()))
     return;
 
   switch (getOpenCLKernelParameterType(S, PT)) {
   case PtrPtrKernelParam:
     // OpenCL v3.0 s6.11.a:
     // A kernel function argument cannot be declared as a pointer to a pointer
     // type. [...] This restriction only applies to OpenCL C 1.2 or below.
     S.Diag(Param->getLocation(), diag::err_opencl_ptrptr_kernel_param);
     D.setInvalidType();
     return;
 
   case InvalidAddrSpacePtrKernelParam:
     // OpenCL v1.0 s6.5:
     // __kernel function arguments declared to be a pointer of a type can point
     // to one of the following address spaces only : __global, __local or
     // __constant.
     S.Diag(Param->getLocation(), diag::err_kernel_arg_address_space);
     D.setInvalidType();
     return;
 
     // OpenCL v1.2 s6.9.k:
     // Arguments to kernel functions in a program cannot be declared with the
     // built-in scalar types bool, half, size_t, ptrdiff_t, intptr_t, and
     // uintptr_t or a struct and/or union that contain fields declared to be
     // one of these built-in scalar types.
 
   case InvalidKernelParam:
     // OpenCL v1.2 s6.8 n:
     // A kernel function argument cannot be declared
     // of event_t type.
     // Do not diagnose half type since it is diagnosed as invalid argument
     // type for any function elsewhere.
     if (!PT->isHalfType()) {
       S.Diag(Param->getLocation(), diag::err_bad_kernel_param_type) << PT;
 
       // Explain what typedefs are involved.
       const TypedefType *Typedef = nullptr;
       while ((Typedef = PT->getAs<TypedefType>())) {
         SourceLocation Loc = Typedef->getDecl()->getLocation();
         // SourceLocation may be invalid for a built-in type.
         if (Loc.isValid())
           S.Diag(Loc, diag::note_entity_declared_at) << PT;
         PT = Typedef->desugar();
       }
     }
 
     D.setInvalidType();
     return;
 
   case PtrKernelParam:
   case ValidKernelParam:
     ValidTypes.insert(PT.getTypePtr());
     return;
 
   case RecordKernelParam:
     break;
   }
 
   // Track nested structs we will inspect
   SmallVector<const Decl *, 4> VisitStack;
 
   // Track where we are in the nested structs. Items will migrate from
   // VisitStack to HistoryStack as we do the DFS for bad field.
   SmallVector<const FieldDecl *, 4> HistoryStack;
   HistoryStack.push_back(nullptr);
 
   // At this point we already handled everything except of a RecordType or
   // an ArrayType of a RecordType.
   assert((PT->isArrayType() || PT->isRecordType()) && "Unexpected type.");
   const RecordType *RecTy =
       PT->getPointeeOrArrayElementType()->getAs<RecordType>();
   const RecordDecl *OrigRecDecl = RecTy->getDecl();
 
   VisitStack.push_back(RecTy->getDecl());
   assert(VisitStack.back() && "First decl null?");
 
   do {
     const Decl *Next = VisitStack.pop_back_val();
     if (!Next) {
       assert(!HistoryStack.empty());
       // Found a marker, we have gone up a level
       if (const FieldDecl *Hist = HistoryStack.pop_back_val())
         ValidTypes.insert(Hist->getType().getTypePtr());
 
       continue;
     }
 
     // Adds everything except the original parameter declaration (which is not a
     // field itself) to the history stack.
     const RecordDecl *RD;
     if (const FieldDecl *Field = dyn_cast<FieldDecl>(Next)) {
       HistoryStack.push_back(Field);
 
       QualType FieldTy = Field->getType();
       // Other field types (known to be valid or invalid) are handled while we
       // walk around RecordDecl::fields().
       assert((FieldTy->isArrayType() || FieldTy->isRecordType()) &&
              "Unexpected type.");
       const Type *FieldRecTy = FieldTy->getPointeeOrArrayElementType();
 
       RD = FieldRecTy->castAs<RecordType>()->getDecl();
     } else {
       RD = cast<RecordDecl>(Next);
     }
 
     // Add a null marker so we know when we've gone back up a level
     VisitStack.push_back(nullptr);
 
     for (const auto *FD : RD->fields()) {
       QualType QT = FD->getType();
 
       if (ValidTypes.count(QT.getTypePtr()))
         continue;
 
       OpenCLParamType ParamType = getOpenCLKernelParameterType(S, QT);
       if (ParamType == ValidKernelParam)
         continue;
 
       if (ParamType == RecordKernelParam) {
         VisitStack.push_back(FD);
         continue;
       }
 
       // OpenCL v1.2 s6.9.p:
       // Arguments to kernel functions that are declared to be a struct or union
       // do not allow OpenCL objects to be passed as elements of the struct or
       // union. This restriction was lifted in OpenCL v2.0 with the introduction
       // of SVM.
       if (ParamType == PtrKernelParam || ParamType == PtrPtrKernelParam ||
           ParamType == InvalidAddrSpacePtrKernelParam) {
         S.Diag(Param->getLocation(),
                diag::err_record_with_pointers_kernel_param)
           << PT->isUnionType()
           << PT;
       } else {
         S.Diag(Param->getLocation(), diag::err_bad_kernel_param_type) << PT;
       }
 
       S.Diag(OrigRecDecl->getLocation(), diag::note_within_field_of_type)
           << OrigRecDecl->getDeclName();
 
       // We have an error, now let's go back up through history and show where
       // the offending field came from
       for (ArrayRef<const FieldDecl *>::const_iterator
                I = HistoryStack.begin() + 1,
                E = HistoryStack.end();
            I != E; ++I) {
         const FieldDecl *OuterField = *I;
         S.Diag(OuterField->getLocation(), diag::note_within_field_of_type)
           << OuterField->getType();
       }
 
       S.Diag(FD->getLocation(), diag::note_illegal_field_declared_here)
         << QT->isPointerType()
         << QT;
       D.setInvalidType();
       return;
     }
   } while (!VisitStack.empty());
 }
 
 /// Find the DeclContext in which a tag is implicitly declared if we see an
 /// elaborated type specifier in the specified context, and lookup finds
 /// nothing.
 static DeclContext *getTagInjectionContext(DeclContext *DC) {
   while (!DC->isFileContext() && !DC->isFunctionOrMethod())
     DC = DC->getParent();
   return DC;
 }
 
 /// Find the Scope in which a tag is implicitly declared if we see an
 /// elaborated type specifier in the specified context, and lookup finds
 /// nothing.
 static Scope *getTagInjectionScope(Scope *S, const LangOptions &LangOpts) {
   while (S->isClassScope() ||
          (LangOpts.CPlusPlus &&
           S->isFunctionPrototypeScope()) ||
          ((S->getFlags() & Scope::DeclScope) == 0) ||
          (S->getEntity() && S->getEntity()->isTransparentContext()))
     S = S->getParent();
   return S;
 }
 
 /// Determine whether a declaration matches a known function in namespace std.
 static bool isStdBuiltin(ASTContext &Ctx, FunctionDecl *FD,
                          unsigned BuiltinID) {
   switch (BuiltinID) {
   case Builtin::BI__GetExceptionInfo:
     // No type checking whatsoever.
     return Ctx.getTargetInfo().getCXXABI().isMicrosoft();
 
   case Builtin::BIaddressof:
   case Builtin::BI__addressof:
   case Builtin::BIforward:
   case Builtin::BIforward_like:
   case Builtin::BImove:
   case Builtin::BImove_if_noexcept:
   case Builtin::BIas_const: {
     // Ensure that we don't treat the algorithm
     //   OutputIt std::move(InputIt, InputIt, OutputIt)
     // as the builtin std::move.
     const auto *FPT = FD->getType()->castAs<FunctionProtoType>();
     return FPT->getNumParams() == 1 && !FPT->isVariadic();
   }
 
   default:
     return false;
   }
 }
 
 NamedDecl*
 Sema::ActOnFunctionDeclarator(Scope *S, Declarator &D, DeclContext *DC,
                               TypeSourceInfo *TInfo, LookupResult &Previous,
                               MultiTemplateParamsArg TemplateParamListsRef,
                               bool &AddToScope) {
   QualType R = TInfo->getType();
 
   assert(R->isFunctionType());
   if (R.getCanonicalType()->castAs<FunctionType>()->getCmseNSCallAttr())
     Diag(D.getIdentifierLoc(), diag::err_function_decl_cmse_ns_call);
 
   SmallVector<TemplateParameterList *, 4> TemplateParamLists;
   llvm::append_range(TemplateParamLists, TemplateParamListsRef);
   if (TemplateParameterList *Invented = D.getInventedTemplateParameterList()) {
     if (!TemplateParamLists.empty() &&
         Invented->getDepth() == TemplateParamLists.back()->getDepth())
       TemplateParamLists.back() = Invented;
     else
       TemplateParamLists.push_back(Invented);
   }
 
   // TODO: consider using NameInfo for diagnostic.
   DeclarationNameInfo NameInfo = GetNameForDeclarator(D);
   DeclarationName Name = NameInfo.getName();
   StorageClass SC = getFunctionStorageClass(*this, D);
 
   if (DeclSpec::TSCS TSCS = D.getDeclSpec().getThreadStorageClassSpec())
     Diag(D.getDeclSpec().getThreadStorageClassSpecLoc(),
          diag::err_invalid_thread)
       << DeclSpec::getSpecifierName(TSCS);
 
   if (D.isFirstDeclarationOfMember())
     adjustMemberFunctionCC(R, D.isStaticMember(), D.isCtorOrDtor(),
                            D.getIdentifierLoc());
 
   bool isFriend = false;
   FunctionTemplateDecl *FunctionTemplate = nullptr;
   bool isMemberSpecialization = false;
   bool isFunctionTemplateSpecialization = false;
 
   bool isDependentClassScopeExplicitSpecialization = false;
   bool HasExplicitTemplateArgs = false;
   TemplateArgumentListInfo TemplateArgs;
 
   bool isVirtualOkay = false;
 
   DeclContext *OriginalDC = DC;
   bool IsLocalExternDecl = adjustContextForLocalExternDecl(DC);
 
   FunctionDecl *NewFD = CreateNewFunctionDecl(*this, D, DC, R, TInfo, SC,
                                               isVirtualOkay);
   if (!NewFD) return nullptr;
 
   if (OriginalLexicalContext && OriginalLexicalContext->isObjCContainer())
     NewFD->setTopLevelDeclInObjCContainer();
 
   // Set the lexical context. If this is a function-scope declaration, or has a
   // C++ scope specifier, or is the object of a friend declaration, the lexical
   // context will be different from the semantic context.
   NewFD->setLexicalDeclContext(CurContext);
 
   if (IsLocalExternDecl)
     NewFD->setLocalExternDecl();
 
   if (getLangOpts().CPlusPlus) {
     // The rules for implicit inlines changed in C++20 for methods and friends
     // with an in-class definition (when such a definition is not attached to
     // the global module).  User-specified 'inline' overrides this (set when
     // the function decl is created above).
     // FIXME: We need a better way to separate C++ standard and clang modules.
     bool ImplicitInlineCXX20 = !getLangOpts().CPlusPlusModules ||
                                !NewFD->getOwningModule() ||
                                NewFD->getOwningModule()->isGlobalModule() ||
                                NewFD->getOwningModule()->isHeaderLikeModule();
     bool isInline = D.getDeclSpec().isInlineSpecified();
     bool isVirtual = D.getDeclSpec().isVirtualSpecified();
     bool hasExplicit = D.getDeclSpec().hasExplicitSpecifier();
     isFriend = D.getDeclSpec().isFriendSpecified();
     if (isFriend && !isInline && D.isFunctionDefinition()) {
       // Pre-C++20 [class.friend]p5
       //   A function can be defined in a friend declaration of a
       //   class . . . . Such a function is implicitly inline.
       // Post C++20 [class.friend]p7
       //   Such a function is implicitly an inline function if it is attached
       //   to the global module.
       NewFD->setImplicitlyInline(ImplicitInlineCXX20);
     }
 
     // If this is a method defined in an __interface, and is not a constructor
     // or an overloaded operator, then set the pure flag (isVirtual will already
     // return true).
     if (const CXXRecordDecl *Parent =
           dyn_cast<CXXRecordDecl>(NewFD->getDeclContext())) {
       if (Parent->isInterface() && cast<CXXMethodDecl>(NewFD)->isUserProvided())
         NewFD->setPure(true);
 
       // C++ [class.union]p2
       //   A union can have member functions, but not virtual functions.
       if (isVirtual && Parent->isUnion()) {
         Diag(D.getDeclSpec().getVirtualSpecLoc(), diag::err_virtual_in_union);
         NewFD->setInvalidDecl();
       }
       if ((Parent->isClass() || Parent->isStruct()) &&
           Parent->hasAttr<SYCLSpecialClassAttr>() &&
           NewFD->getKind() == Decl::Kind::CXXMethod && NewFD->getIdentifier() &&
           NewFD->getName() == "__init" && D.isFunctionDefinition()) {
         if (auto *Def = Parent->getDefinition())
           Def->setInitMethod(true);
       }
     }
 
     SetNestedNameSpecifier(*this, NewFD, D);
     isMemberSpecialization = false;
     isFunctionTemplateSpecialization = false;
     if (D.isInvalidType())
       NewFD->setInvalidDecl();
 
     // Match up the template parameter lists with the scope specifier, then
     // determine whether we have a template or a template specialization.
     bool Invalid = false;
     TemplateParameterList *TemplateParams =
         MatchTemplateParametersToScopeSpecifier(
             D.getDeclSpec().getBeginLoc(), D.getIdentifierLoc(),
             D.getCXXScopeSpec(),
             D.getName().getKind() == UnqualifiedIdKind::IK_TemplateId
                 ? D.getName().TemplateId
                 : nullptr,
             TemplateParamLists, isFriend, isMemberSpecialization,
             Invalid);
     if (TemplateParams) {
       // Check that we can declare a template here.
       if (CheckTemplateDeclScope(S, TemplateParams))
         NewFD->setInvalidDecl();
 
       if (TemplateParams->size() > 0) {
         // This is a function template
 
         // A destructor cannot be a template.
         if (Name.getNameKind() == DeclarationName::CXXDestructorName) {
           Diag(NewFD->getLocation(), diag::err_destructor_template);
           NewFD->setInvalidDecl();
         }
 
         // If we're adding a template to a dependent context, we may need to
         // rebuilding some of the types used within the template parameter list,
         // now that we know what the current instantiation is.
         if (DC->isDependentContext()) {
           ContextRAII SavedContext(*this, DC);
           if (RebuildTemplateParamsInCurrentInstantiation(TemplateParams))
             Invalid = true;
         }
 
         FunctionTemplate = FunctionTemplateDecl::Create(Context, DC,
                                                         NewFD->getLocation(),
                                                         Name, TemplateParams,
                                                         NewFD);
         FunctionTemplate->setLexicalDeclContext(CurContext);
         NewFD->setDescribedFunctionTemplate(FunctionTemplate);
 
         // For source fidelity, store the other template param lists.
         if (TemplateParamLists.size() > 1) {
           NewFD->setTemplateParameterListsInfo(Context,
               ArrayRef<TemplateParameterList *>(TemplateParamLists)
                   .drop_back(1));
         }
       } else {
         // This is a function template specialization.
         isFunctionTemplateSpecialization = true;
         // For source fidelity, store all the template param lists.
         if (TemplateParamLists.size() > 0)
           NewFD->setTemplateParameterListsInfo(Context, TemplateParamLists);
 
         // C++0x [temp.expl.spec]p20 forbids "template<> friend void foo(int);".
         if (isFriend) {
           // We want to remove the "template<>", found here.
           SourceRange RemoveRange = TemplateParams->getSourceRange();
 
           // If we remove the template<> and the name is not a
           // template-id, we're actually silently creating a problem:
           // the friend declaration will refer to an untemplated decl,
           // and clearly the user wants a template specialization.  So
           // we need to insert '<>' after the name.
           SourceLocation InsertLoc;
           if (D.getName().getKind() != UnqualifiedIdKind::IK_TemplateId) {
             InsertLoc = D.getName().getSourceRange().getEnd();
             InsertLoc = getLocForEndOfToken(InsertLoc);
           }
 
           Diag(D.getIdentifierLoc(), diag::err_template_spec_decl_friend)
             << Name << RemoveRange
             << FixItHint::CreateRemoval(RemoveRange)
             << FixItHint::CreateInsertion(InsertLoc, "<>");
           Invalid = true;
         }
       }
     } else {
       // Check that we can declare a template here.
       if (!TemplateParamLists.empty() && isMemberSpecialization &&
           CheckTemplateDeclScope(S, TemplateParamLists.back()))
         NewFD->setInvalidDecl();
 
       // All template param lists were matched against the scope specifier:
       // this is NOT (an explicit specialization of) a template.
       if (TemplateParamLists.size() > 0)
         // For source fidelity, store all the template param lists.
         NewFD->setTemplateParameterListsInfo(Context, TemplateParamLists);
     }
 
     if (Invalid) {
       NewFD->setInvalidDecl();
       if (FunctionTemplate)
         FunctionTemplate->setInvalidDecl();
     }
 
     // C++ [dcl.fct.spec]p5:
     //   The virtual specifier shall only be used in declarations of
     //   nonstatic class member functions that appear within a
     //   member-specification of a class declaration; see 10.3.
     //
     if (isVirtual && !NewFD->isInvalidDecl()) {
       if (!isVirtualOkay) {
         Diag(D.getDeclSpec().getVirtualSpecLoc(),
              diag::err_virtual_non_function);
       } else if (!CurContext->isRecord()) {
         // 'virtual' was specified outside of the class.
         Diag(D.getDeclSpec().getVirtualSpecLoc(),
              diag::err_virtual_out_of_class)
           << FixItHint::CreateRemoval(D.getDeclSpec().getVirtualSpecLoc());
       } else if (NewFD->getDescribedFunctionTemplate()) {
         // C++ [temp.mem]p3:
         //  A member function template shall not be virtual.
         Diag(D.getDeclSpec().getVirtualSpecLoc(),
              diag::err_virtual_member_function_template)
           << FixItHint::CreateRemoval(D.getDeclSpec().getVirtualSpecLoc());
       } else {
         // Okay: Add virtual to the method.
         NewFD->setVirtualAsWritten(true);
       }
 
       if (getLangOpts().CPlusPlus14 &&
           NewFD->getReturnType()->isUndeducedType())
         Diag(D.getDeclSpec().getVirtualSpecLoc(), diag::err_auto_fn_virtual);
     }
 
     if (getLangOpts().CPlusPlus14 &&
         (NewFD->isDependentContext() ||
          (isFriend && CurContext->isDependentContext())) &&
         NewFD->getReturnType()->isUndeducedType()) {
       // If the function template is referenced directly (for instance, as a
       // member of the current instantiation), pretend it has a dependent type.
       // This is not really justified by the standard, but is the only sane
       // thing to do.
       // FIXME: For a friend function, we have not marked the function as being
       // a friend yet, so 'isDependentContext' on the FD doesn't work.
       const FunctionProtoType *FPT =
           NewFD->getType()->castAs<FunctionProtoType>();
       QualType Result = SubstAutoTypeDependent(FPT->getReturnType());
       NewFD->setType(Context.getFunctionType(Result, FPT->getParamTypes(),
                                              FPT->getExtProtoInfo()));
     }
 
     // C++ [dcl.fct.spec]p3:
     //  The inline specifier shall not appear on a block scope function
     //  declaration.
     if (isInline && !NewFD->isInvalidDecl()) {
       if (CurContext->isFunctionOrMethod()) {
         // 'inline' is not allowed on block scope function declaration.
         Diag(D.getDeclSpec().getInlineSpecLoc(),
              diag::err_inline_declaration_block_scope) << Name
           << FixItHint::CreateRemoval(D.getDeclSpec().getInlineSpecLoc());
       }
     }
 
     // C++ [dcl.fct.spec]p6:
     //  The explicit specifier shall be used only in the declaration of a
     //  constructor or conversion function within its class definition;
     //  see 12.3.1 and 12.3.2.
     if (hasExplicit && !NewFD->isInvalidDecl() &&
         !isa<CXXDeductionGuideDecl>(NewFD)) {
       if (!CurContext->isRecord()) {
         // 'explicit' was specified outside of the class.
         Diag(D.getDeclSpec().getExplicitSpecLoc(),
              diag::err_explicit_out_of_class)
             << FixItHint::CreateRemoval(D.getDeclSpec().getExplicitSpecRange());
       } else if (!isa<CXXConstructorDecl>(NewFD) &&
                  !isa<CXXConversionDecl>(NewFD)) {
         // 'explicit' was specified on a function that wasn't a constructor
         // or conversion function.
         Diag(D.getDeclSpec().getExplicitSpecLoc(),
              diag::err_explicit_non_ctor_or_conv_function)
             << FixItHint::CreateRemoval(D.getDeclSpec().getExplicitSpecRange());
       }
     }
 
     ConstexprSpecKind ConstexprKind = D.getDeclSpec().getConstexprSpecifier();
     if (ConstexprKind != ConstexprSpecKind::Unspecified) {
       // C++11 [dcl.constexpr]p2: constexpr functions and constexpr constructors
       // are implicitly inline.
       NewFD->setImplicitlyInline();
 
       // C++11 [dcl.constexpr]p3: functions declared constexpr are required to
       // be either constructors or to return a literal type. Therefore,
       // destructors cannot be declared constexpr.
       if (isa<CXXDestructorDecl>(NewFD) &&
           (!getLangOpts().CPlusPlus20 ||
            ConstexprKind == ConstexprSpecKind::Consteval)) {
         Diag(D.getDeclSpec().getConstexprSpecLoc(), diag::err_constexpr_dtor)
             << static_cast<int>(ConstexprKind);
         NewFD->setConstexprKind(getLangOpts().CPlusPlus20
                                     ? ConstexprSpecKind::Unspecified
                                     : ConstexprSpecKind::Constexpr);
       }
       // C++20 [dcl.constexpr]p2: An allocation function, or a
       // deallocation function shall not be declared with the consteval
       // specifier.
       if (ConstexprKind == ConstexprSpecKind::Consteval &&
           (NewFD->getOverloadedOperator() == OO_New ||
            NewFD->getOverloadedOperator() == OO_Array_New ||
            NewFD->getOverloadedOperator() == OO_Delete ||
            NewFD->getOverloadedOperator() == OO_Array_Delete)) {
         Diag(D.getDeclSpec().getConstexprSpecLoc(),
              diag::err_invalid_consteval_decl_kind)
             << NewFD;
         NewFD->setConstexprKind(ConstexprSpecKind::Constexpr);
       }
     }
 
     // If __module_private__ was specified, mark the function accordingly.
     if (D.getDeclSpec().isModulePrivateSpecified()) {
       if (isFunctionTemplateSpecialization) {
         SourceLocation ModulePrivateLoc
           = D.getDeclSpec().getModulePrivateSpecLoc();
         Diag(ModulePrivateLoc, diag::err_module_private_specialization)
           << 0
           << FixItHint::CreateRemoval(ModulePrivateLoc);
       } else {
         NewFD->setModulePrivate();
         if (FunctionTemplate)
           FunctionTemplate->setModulePrivate();
       }
     }
 
     if (isFriend) {
       if (FunctionTemplate) {
         FunctionTemplate->setObjectOfFriendDecl();
         FunctionTemplate->setAccess(AS_public);
       }
       NewFD->setObjectOfFriendDecl();
       NewFD->setAccess(AS_public);
     }
 
     // If a function is defined as defaulted or deleted, mark it as such now.
     // We'll do the relevant checks on defaulted / deleted functions later.
     switch (D.getFunctionDefinitionKind()) {
     case FunctionDefinitionKind::Declaration:
     case FunctionDefinitionKind::Definition:
       break;
 
     case FunctionDefinitionKind::Defaulted:
       NewFD->setDefaulted();
       break;
 
     case FunctionDefinitionKind::Deleted:
       NewFD->setDeletedAsWritten();
       break;
     }
 
     if (isa<CXXMethodDecl>(NewFD) && DC == CurContext &&
         D.isFunctionDefinition() && !isInline) {
       // Pre C++20 [class.mfct]p2:
       //   A member function may be defined (8.4) in its class definition, in
       //   which case it is an inline member function (7.1.2)
       // Post C++20 [class.mfct]p1:
       //   If a member function is attached to the global module and is defined
       //   in its class definition, it is inline.
       NewFD->setImplicitlyInline(ImplicitInlineCXX20);
     }
 
     if (SC == SC_Static && isa<CXXMethodDecl>(NewFD) &&
         !CurContext->isRecord()) {
       // C++ [class.static]p1:
       //   A data or function member of a class may be declared static
       //   in a class definition, in which case it is a static member of
       //   the class.
 
       // Complain about the 'static' specifier if it's on an out-of-line
       // member function definition.
 
       // MSVC permits the use of a 'static' storage specifier on an out-of-line
       // member function template declaration and class member template
       // declaration (MSVC versions before 2015), warn about this.
       Diag(D.getDeclSpec().getStorageClassSpecLoc(),
            ((!getLangOpts().isCompatibleWithMSVC(LangOptions::MSVC2015) &&
              cast<CXXRecordDecl>(DC)->getDescribedClassTemplate()) ||
            (getLangOpts().MSVCCompat && NewFD->getDescribedFunctionTemplate()))
            ? diag::ext_static_out_of_line : diag::err_static_out_of_line)
         << FixItHint::CreateRemoval(D.getDeclSpec().getStorageClassSpecLoc());
     }
 
     // C++11 [except.spec]p15:
     //   A deallocation function with no exception-specification is treated
     //   as if it were specified with noexcept(true).
     const FunctionProtoType *FPT = R->getAs<FunctionProtoType>();
     if ((Name.getCXXOverloadedOperator() == OO_Delete ||
          Name.getCXXOverloadedOperator() == OO_Array_Delete) &&
         getLangOpts().CPlusPlus11 && FPT && !FPT->hasExceptionSpec())
       NewFD->setType(Context.getFunctionType(
           FPT->getReturnType(), FPT->getParamTypes(),
           FPT->getExtProtoInfo().withExceptionSpec(EST_BasicNoexcept)));
 
     // C++20 [dcl.inline]/7
     // If an inline function or variable that is attached to a named module
     // is declared in a definition domain, it shall be defined in that
     // domain.
     // So, if the current declaration does not have a definition, we must
     // check at the end of the TU (or when the PMF starts) to see that we
     // have a definition at that point.
     if (isInline && !D.isFunctionDefinition() && getLangOpts().CPlusPlus20 &&
         NewFD->hasOwningModule() &&
         NewFD->getOwningModule()->isModulePurview()) {
       PendingInlineFuncDecls.insert(NewFD);
     }
   }
 
   // Filter out previous declarations that don't match the scope.
   FilterLookupForScope(Previous, OriginalDC, S, shouldConsiderLinkage(NewFD),
                        D.getCXXScopeSpec().isNotEmpty() ||
                        isMemberSpecialization ||
                        isFunctionTemplateSpecialization);
 
   // Handle GNU asm-label extension (encoded as an attribute).
   if (Expr *E = (Expr*) D.getAsmLabel()) {
     // The parser guarantees this is a string.
     StringLiteral *SE = cast<StringLiteral>(E);
     NewFD->addAttr(AsmLabelAttr::Create(Context, SE->getString(),
                                         /*IsLiteralLabel=*/true,
                                         SE->getStrTokenLoc(0)));
   } else if (!ExtnameUndeclaredIdentifiers.empty()) {
     llvm::DenseMap<IdentifierInfo*,AsmLabelAttr*>::iterator I =
       ExtnameUndeclaredIdentifiers.find(NewFD->getIdentifier());
     if (I != ExtnameUndeclaredIdentifiers.end()) {
       if (isDeclExternC(NewFD)) {
         NewFD->addAttr(I->second);
         ExtnameUndeclaredIdentifiers.erase(I);
       } else
         Diag(NewFD->getLocation(), diag::warn_redefine_extname_not_applied)
             << /*Variable*/0 << NewFD;
     }
   }
 
   // Copy the parameter declarations from the declarator D to the function
   // declaration NewFD, if they are available.  First scavenge them into Params.
   SmallVector<ParmVarDecl*, 16> Params;
   unsigned FTIIdx;
   if (D.isFunctionDeclarator(FTIIdx)) {
     DeclaratorChunk::FunctionTypeInfo &FTI = D.getTypeObject(FTIIdx).Fun;
 
     // Check for C99 6.7.5.3p10 - foo(void) is a non-varargs
     // function that takes no arguments, not a function that takes a
     // single void argument.
     // We let through "const void" here because Sema::GetTypeForDeclarator
     // already checks for that case.
     if (FTIHasNonVoidParameters(FTI) && FTI.Params[0].Param) {
       for (unsigned i = 0, e = FTI.NumParams; i != e; ++i) {
         ParmVarDecl *Param = cast<ParmVarDecl>(FTI.Params[i].Param);
         assert(Param->getDeclContext() != NewFD && "Was set before ?");
         Param->setDeclContext(NewFD);
         Params.push_back(Param);
 
         if (Param->isInvalidDecl())
           NewFD->setInvalidDecl();
       }
     }
 
     if (!getLangOpts().CPlusPlus) {
       // In C, find all the tag declarations from the prototype and move them
       // into the function DeclContext. Remove them from the surrounding tag
       // injection context of the function, which is typically but not always
       // the TU.
       DeclContext *PrototypeTagContext =
           getTagInjectionContext(NewFD->getLexicalDeclContext());
       for (NamedDecl *NonParmDecl : FTI.getDeclsInPrototype()) {
         auto *TD = dyn_cast<TagDecl>(NonParmDecl);
 
         // We don't want to reparent enumerators. Look at their parent enum
         // instead.
         if (!TD) {
           if (auto *ECD = dyn_cast<EnumConstantDecl>(NonParmDecl))
             TD = cast<EnumDecl>(ECD->getDeclContext());
         }
         if (!TD)
           continue;
         DeclContext *TagDC = TD->getLexicalDeclContext();
         if (!TagDC->containsDecl(TD))
           continue;
         TagDC->removeDecl(TD);
         TD->setDeclContext(NewFD);
         NewFD->addDecl(TD);
 
         // Preserve the lexical DeclContext if it is not the surrounding tag
         // injection context of the FD. In this example, the semantic context of
         // E will be f and the lexical context will be S, while both the
         // semantic and lexical contexts of S will be f:
         //   void f(struct S { enum E { a } f; } s);
         if (TagDC != PrototypeTagContext)
           TD->setLexicalDeclContext(TagDC);
       }
     }
   } else if (const FunctionProtoType *FT = R->getAs<FunctionProtoType>()) {
     // When we're declaring a function with a typedef, typeof, etc as in the
     // following example, we'll need to synthesize (unnamed)
     // parameters for use in the declaration.
     //
     // @code
     // typedef void fn(int);
     // fn f;
     // @endcode
 
     // Synthesize a parameter for each argument type.
     for (const auto &AI : FT->param_types()) {
       ParmVarDecl *Param =
           BuildParmVarDeclForTypedef(NewFD, D.getIdentifierLoc(), AI);
       Param->setScopeInfo(0, Params.size());
       Params.push_back(Param);
     }
   } else {
     assert(R->isFunctionNoProtoType() && NewFD->getNumParams() == 0 &&
            "Should not need args for typedef of non-prototype fn");
   }
 
   // Finally, we know we have the right number of parameters, install them.
   NewFD->setParams(Params);
 
   if (D.getDeclSpec().isNoreturnSpecified())
     NewFD->addAttr(
         C11NoReturnAttr::Create(Context, D.getDeclSpec().getNoreturnSpecLoc()));
 
   // Functions returning a variably modified type violate C99 6.7.5.2p2
   // because all functions have linkage.
   if (!NewFD->isInvalidDecl() &&
       NewFD->getReturnType()->isVariablyModifiedType()) {
     Diag(NewFD->getLocation(), diag::err_vm_func_decl);
     NewFD->setInvalidDecl();
   }
 
   // Apply an implicit SectionAttr if '#pragma clang section text' is active
   if (PragmaClangTextSection.Valid && D.isFunctionDefinition() &&
       !NewFD->hasAttr<SectionAttr>())
     NewFD->addAttr(PragmaClangTextSectionAttr::CreateImplicit(
         Context, PragmaClangTextSection.SectionName,
         PragmaClangTextSection.PragmaLocation));
 
   // Apply an implicit SectionAttr if #pragma code_seg is active.
   if (CodeSegStack.CurrentValue && D.isFunctionDefinition() &&
       !NewFD->hasAttr<SectionAttr>()) {
     NewFD->addAttr(SectionAttr::CreateImplicit(
         Context, CodeSegStack.CurrentValue->getString(),
         CodeSegStack.CurrentPragmaLocation, SectionAttr::Declspec_allocate));
     if (UnifySection(CodeSegStack.CurrentValue->getString(),
                      ASTContext::PSF_Implicit | ASTContext::PSF_Execute |
                          ASTContext::PSF_Read,
                      NewFD))
       NewFD->dropAttr<SectionAttr>();
   }
 
   // Apply an implicit StrictGuardStackCheckAttr if #pragma strict_gs_check is
   // active.
   if (StrictGuardStackCheckStack.CurrentValue && D.isFunctionDefinition() &&
       !NewFD->hasAttr<StrictGuardStackCheckAttr>())
     NewFD->addAttr(StrictGuardStackCheckAttr::CreateImplicit(
         Context, PragmaClangTextSection.PragmaLocation));
 
   // Apply an implicit CodeSegAttr from class declspec or
   // apply an implicit SectionAttr from #pragma code_seg if active.
   if (!NewFD->hasAttr<CodeSegAttr>()) {
     if (Attr *SAttr = getImplicitCodeSegOrSectionAttrForFunction(NewFD,
                                                                  D.isFunctionDefinition())) {
       NewFD->addAttr(SAttr);
     }
   }
 
   // Handle attributes.
   ProcessDeclAttributes(S, NewFD, D);
   const auto *NewTVA = NewFD->getAttr<TargetVersionAttr>();
   if (NewTVA && !NewTVA->isDefaultVersion() &&
       !Context.getTargetInfo().hasFeature("fmv")) {
     // Don't add to scope fmv functions declarations if fmv disabled
     AddToScope = false;
     return NewFD;
   }
 
   if (getLangOpts().OpenCL) {
     // OpenCL v1.1 s6.5: Using an address space qualifier in a function return
     // type declaration will generate a compilation error.
     LangAS AddressSpace = NewFD->getReturnType().getAddressSpace();
     if (AddressSpace != LangAS::Default) {
       Diag(NewFD->getLocation(), diag::err_return_value_with_address_space);
       NewFD->setInvalidDecl();
     }
   }
 
   if (getLangOpts().HLSL) {
     auto &TargetInfo = getASTContext().getTargetInfo();
     // Skip operator overload which not identifier.
     // Also make sure NewFD is in translation-unit scope.
     if (!NewFD->isInvalidDecl() && Name.isIdentifier() &&
         NewFD->getName() == TargetInfo.getTargetOpts().HLSLEntry &&
         S->getDepth() == 0) {
       CheckHLSLEntryPoint(NewFD);
       if (!NewFD->isInvalidDecl()) {
         auto Env = TargetInfo.getTriple().getEnvironment();
         HLSLShaderAttr::ShaderType ShaderType =
             static_cast<HLSLShaderAttr::ShaderType>(
                 hlsl::getStageFromEnvironment(Env));
         // To share code with HLSLShaderAttr, add HLSLShaderAttr to entry
         // function.
         if (HLSLShaderAttr *NT = NewFD->getAttr<HLSLShaderAttr>()) {
           if (NT->getType() != ShaderType)
             Diag(NT->getLocation(), diag::err_hlsl_entry_shader_attr_mismatch)
                 << NT;
         } else {
           NewFD->addAttr(HLSLShaderAttr::Create(Context, ShaderType,
                                                 NewFD->getBeginLoc()));
         }
       }
     }
     // HLSL does not support specifying an address space on a function return
     // type.
     LangAS AddressSpace = NewFD->getReturnType().getAddressSpace();
     if (AddressSpace != LangAS::Default) {
       Diag(NewFD->getLocation(), diag::err_return_value_with_address_space);
       NewFD->setInvalidDecl();
     }
   }
 
   if (!getLangOpts().CPlusPlus) {
     // Perform semantic checking on the function declaration.
     if (!NewFD->isInvalidDecl() && NewFD->isMain())
       CheckMain(NewFD, D.getDeclSpec());
 
     if (!NewFD->isInvalidDecl() && NewFD->isMSVCRTEntryPoint())
       CheckMSVCRTEntryPoint(NewFD);
 
     if (!NewFD->isInvalidDecl())
       D.setRedeclaration(CheckFunctionDeclaration(S, NewFD, Previous,
                                                   isMemberSpecialization,
                                                   D.isFunctionDefinition()));
     else if (!Previous.empty())
       // Recover gracefully from an invalid redeclaration.
       D.setRedeclaration(true);
     assert((NewFD->isInvalidDecl() || !D.isRedeclaration() ||
             Previous.getResultKind() != LookupResult::FoundOverloaded) &&
            "previous declaration set still overloaded");
 
     // Diagnose no-prototype function declarations with calling conventions that
     // don't support variadic calls. Only do this in C and do it after merging
     // possibly prototyped redeclarations.
     const FunctionType *FT = NewFD->getType()->castAs<FunctionType>();
     if (isa<FunctionNoProtoType>(FT) && !D.isFunctionDefinition()) {
       CallingConv CC = FT->getExtInfo().getCC();
       if (!supportsVariadicCall(CC)) {
         // Windows system headers sometimes accidentally use stdcall without
         // (void) parameters, so we relax this to a warning.
         int DiagID =
             CC == CC_X86StdCall ? diag::warn_cconv_knr : diag::err_cconv_knr;
         Diag(NewFD->getLocation(), DiagID)
             << FunctionType::getNameForCallConv(CC);
       }
     }
 
    if (NewFD->getReturnType().hasNonTrivialToPrimitiveDestructCUnion() ||
        NewFD->getReturnType().hasNonTrivialToPrimitiveCopyCUnion())
      checkNonTrivialCUnion(NewFD->getReturnType(),
                            NewFD->getReturnTypeSourceRange().getBegin(),
                            NTCUC_FunctionReturn, NTCUK_Destruct|NTCUK_Copy);
   } else {
     // C++11 [replacement.functions]p3:
     //  The program's definitions shall not be specified as inline.
     //
     // N.B. We diagnose declarations instead of definitions per LWG issue 2340.
     //
     // Suppress the diagnostic if the function is __attribute__((used)), since
     // that forces an external definition to be emitted.
     if (D.getDeclSpec().isInlineSpecified() &&
         NewFD->isReplaceableGlobalAllocationFunction() &&
         !NewFD->hasAttr<UsedAttr>())
       Diag(D.getDeclSpec().getInlineSpecLoc(),
            diag::ext_operator_new_delete_declared_inline)
         << NewFD->getDeclName();
 
     // If the declarator is a template-id, translate the parser's template
     // argument list into our AST format.
     if (D.getName().getKind() == UnqualifiedIdKind::IK_TemplateId) {
       TemplateIdAnnotation *TemplateId = D.getName().TemplateId;
       TemplateArgs.setLAngleLoc(TemplateId->LAngleLoc);
       TemplateArgs.setRAngleLoc(TemplateId->RAngleLoc);
       ASTTemplateArgsPtr TemplateArgsPtr(TemplateId->getTemplateArgs(),
                                          TemplateId->NumArgs);
       translateTemplateArguments(TemplateArgsPtr,
                                  TemplateArgs);
 
       HasExplicitTemplateArgs = true;
 
       if (NewFD->isInvalidDecl()) {
         HasExplicitTemplateArgs = false;
       } else if (FunctionTemplate) {
         // Function template with explicit template arguments.
         Diag(D.getIdentifierLoc(), diag::err_function_template_partial_spec)
           << SourceRange(TemplateId->LAngleLoc, TemplateId->RAngleLoc);
 
         HasExplicitTemplateArgs = false;
       } else {
         assert((isFunctionTemplateSpecialization ||
                 D.getDeclSpec().isFriendSpecified()) &&
                "should have a 'template<>' for this decl");
         // "friend void foo<>(int);" is an implicit specialization decl.
         isFunctionTemplateSpecialization = true;
       }
     } else if (isFriend && isFunctionTemplateSpecialization) {
       // This combination is only possible in a recovery case;  the user
       // wrote something like:
       //   template <> friend void foo(int);
       // which we're recovering from as if the user had written:
       //   friend void foo<>(int);
       // Go ahead and fake up a template id.
       HasExplicitTemplateArgs = true;
       TemplateArgs.setLAngleLoc(D.getIdentifierLoc());
       TemplateArgs.setRAngleLoc(D.getIdentifierLoc());
     }
 
     // We do not add HD attributes to specializations here because
     // they may have different constexpr-ness compared to their
     // templates and, after maybeAddCUDAHostDeviceAttrs() is applied,
     // may end up with different effective targets. Instead, a
     // specialization inherits its target attributes from its template
     // in the CheckFunctionTemplateSpecialization() call below.
     if (getLangOpts().CUDA && !isFunctionTemplateSpecialization)
       maybeAddCUDAHostDeviceAttrs(NewFD, Previous);
 
     // If it's a friend (and only if it's a friend), it's possible
     // that either the specialized function type or the specialized
     // template is dependent, and therefore matching will fail.  In
     // this case, don't check the specialization yet.
     if (isFunctionTemplateSpecialization && isFriend &&
         (NewFD->getType()->isDependentType() || DC->isDependentContext() ||
          TemplateSpecializationType::anyInstantiationDependentTemplateArguments(
              TemplateArgs.arguments()))) {
       assert(HasExplicitTemplateArgs &&
              "friend function specialization without template args");
       if (CheckDependentFunctionTemplateSpecialization(NewFD, TemplateArgs,
                                                        Previous))
         NewFD->setInvalidDecl();
     } else if (isFunctionTemplateSpecialization) {
       if (CurContext->isDependentContext() && CurContext->isRecord()
           && !isFriend) {
         isDependentClassScopeExplicitSpecialization = true;
       } else if (!NewFD->isInvalidDecl() &&
                  CheckFunctionTemplateSpecialization(
                      NewFD, (HasExplicitTemplateArgs ? &TemplateArgs : nullptr),
                      Previous))
         NewFD->setInvalidDecl();
 
       // C++ [dcl.stc]p1:
       //   A storage-class-specifier shall not be specified in an explicit
       //   specialization (14.7.3)
       FunctionTemplateSpecializationInfo *Info =
           NewFD->getTemplateSpecializationInfo();
       if (Info && SC != SC_None) {
         if (SC != Info->getTemplate()->getTemplatedDecl()->getStorageClass())
           Diag(NewFD->getLocation(),
                diag::err_explicit_specialization_inconsistent_storage_class)
             << SC
             << FixItHint::CreateRemoval(
                                       D.getDeclSpec().getStorageClassSpecLoc());
 
         else
           Diag(NewFD->getLocation(),
                diag::ext_explicit_specialization_storage_class)
             << FixItHint::CreateRemoval(
                                       D.getDeclSpec().getStorageClassSpecLoc());
       }
     } else if (isMemberSpecialization && isa<CXXMethodDecl>(NewFD)) {
       if (CheckMemberSpecialization(NewFD, Previous))
           NewFD->setInvalidDecl();
     }
 
     // Perform semantic checking on the function declaration.
     if (!isDependentClassScopeExplicitSpecialization) {
       if (!NewFD->isInvalidDecl() && NewFD->isMain())
         CheckMain(NewFD, D.getDeclSpec());
 
       if (!NewFD->isInvalidDecl() && NewFD->isMSVCRTEntryPoint())
         CheckMSVCRTEntryPoint(NewFD);
 
       if (!NewFD->isInvalidDecl())
         D.setRedeclaration(CheckFunctionDeclaration(S, NewFD, Previous,
                                                     isMemberSpecialization,
                                                     D.isFunctionDefinition()));
       else if (!Previous.empty())
         // Recover gracefully from an invalid redeclaration.
         D.setRedeclaration(true);
     }
 
     assert((NewFD->isInvalidDecl() || NewFD->isMultiVersion() ||
             !D.isRedeclaration() ||
             Previous.getResultKind() != LookupResult::FoundOverloaded) &&
            "previous declaration set still overloaded");
 
     NamedDecl *PrincipalDecl = (FunctionTemplate
                                 ? cast<NamedDecl>(FunctionTemplate)
                                 : NewFD);
 
     if (isFriend && NewFD->getPreviousDecl()) {
       AccessSpecifier Access = AS_public;
       if (!NewFD->isInvalidDecl())
         Access = NewFD->getPreviousDecl()->getAccess();
 
       NewFD->setAccess(Access);
       if (FunctionTemplate) FunctionTemplate->setAccess(Access);
     }
 
     if (NewFD->isOverloadedOperator() && !DC->isRecord() &&
         PrincipalDecl->isInIdentifierNamespace(Decl::IDNS_Ordinary))
       PrincipalDecl->setNonMemberOperator();
 
     // If we have a function template, check the template parameter
     // list. This will check and merge default template arguments.
     if (FunctionTemplate) {
       FunctionTemplateDecl *PrevTemplate =
                                      FunctionTemplate->getPreviousDecl();
       CheckTemplateParameterList(FunctionTemplate->getTemplateParameters(),
                        PrevTemplate ? PrevTemplate->getTemplateParameters()
                                     : nullptr,
                             D.getDeclSpec().isFriendSpecified()
                               ? (D.isFunctionDefinition()
                                    ? TPC_FriendFunctionTemplateDefinition
                                    : TPC_FriendFunctionTemplate)
                               : (D.getCXXScopeSpec().isSet() &&
                                  DC && DC->isRecord() &&
                                  DC->isDependentContext())
                                   ? TPC_ClassTemplateMember
                                   : TPC_FunctionTemplate);
     }
 
     if (NewFD->isInvalidDecl()) {
       // Ignore all the rest of this.
     } else if (!D.isRedeclaration()) {
       struct ActOnFDArgs ExtraArgs = { S, D, TemplateParamLists,
                                        AddToScope };
       // Fake up an access specifier if it's supposed to be a class member.
       if (isa<CXXRecordDecl>(NewFD->getDeclContext()))
         NewFD->setAccess(AS_public);
 
       // Qualified decls generally require a previous declaration.
       if (D.getCXXScopeSpec().isSet()) {
         // ...with the major exception of templated-scope or
         // dependent-scope friend declarations.
 
         // TODO: we currently also suppress this check in dependent
         // contexts because (1) the parameter depth will be off when
         // matching friend templates and (2) we might actually be
         // selecting a friend based on a dependent factor.  But there
         // are situations where these conditions don't apply and we
         // can actually do this check immediately.
         //
         // Unless the scope is dependent, it's always an error if qualified
         // redeclaration lookup found nothing at all. Diagnose that now;
         // nothing will diagnose that error later.
         if (isFriend &&
             (D.getCXXScopeSpec().getScopeRep()->isDependent() ||
              (!Previous.empty() && CurContext->isDependentContext()))) {
           // ignore these
         } else if (NewFD->isCPUDispatchMultiVersion() ||
                    NewFD->isCPUSpecificMultiVersion()) {
           // ignore this, we allow the redeclaration behavior here to create new
           // versions of the function.
         } else {
           // The user tried to provide an out-of-line definition for a
           // function that is a member of a class or namespace, but there
           // was no such member function declared (C++ [class.mfct]p2,
           // C++ [namespace.memdef]p2). For example:
           //
           // class X {
           //   void f() const;
           // };
           //
           // void X::f() { } // ill-formed
           //
           // Complain about this problem, and attempt to suggest close
           // matches (e.g., those that differ only in cv-qualifiers and
           // whether the parameter types are references).
 
           if (NamedDecl *Result = DiagnoseInvalidRedeclaration(
                   *this, Previous, NewFD, ExtraArgs, false, nullptr)) {
             AddToScope = ExtraArgs.AddToScope;
             return Result;
           }
         }
 
         // Unqualified local friend declarations are required to resolve
         // to something.
       } else if (isFriend && cast<CXXRecordDecl>(CurContext)->isLocalClass()) {
         if (NamedDecl *Result = DiagnoseInvalidRedeclaration(
                 *this, Previous, NewFD, ExtraArgs, true, S)) {
           AddToScope = ExtraArgs.AddToScope;
           return Result;
         }
       }
     } else if (!D.isFunctionDefinition() &&
                isa<CXXMethodDecl>(NewFD) && NewFD->isOutOfLine() &&
                !isFriend && !isFunctionTemplateSpecialization &&
                !isMemberSpecialization) {
       // An out-of-line member function declaration must also be a
       // definition (C++ [class.mfct]p2).
       // Note that this is not the case for explicit specializations of
       // function templates or member functions of class templates, per
       // C++ [temp.expl.spec]p2. We also allow these declarations as an
       // extension for compatibility with old SWIG code which likes to
       // generate them.
       Diag(NewFD->getLocation(), diag::ext_out_of_line_declaration)
         << D.getCXXScopeSpec().getRange();
     }
   }
 
   // If this is the first declaration of a library builtin function, add
   // attributes as appropriate.
   if (!D.isRedeclaration()) {
     if (IdentifierInfo *II = Previous.getLookupName().getAsIdentifierInfo()) {
       if (unsigned BuiltinID = II->getBuiltinID()) {
         bool InStdNamespace = Context.BuiltinInfo.isInStdNamespace(BuiltinID);
         if (!InStdNamespace &&
             NewFD->getDeclContext()->getRedeclContext()->isFileContext()) {
           if (NewFD->getLanguageLinkage() == CLanguageLinkage) {
             // Validate the type matches unless this builtin is specified as
             // matching regardless of its declared type.
             if (Context.BuiltinInfo.allowTypeMismatch(BuiltinID)) {
               NewFD->addAttr(BuiltinAttr::CreateImplicit(Context, BuiltinID));
             } else {
               ASTContext::GetBuiltinTypeError Error;
               LookupNecessaryTypesForBuiltin(S, BuiltinID);
               QualType BuiltinType = Context.GetBuiltinType(BuiltinID, Error);
 
               if (!Error && !BuiltinType.isNull() &&
                   Context.hasSameFunctionTypeIgnoringExceptionSpec(
                       NewFD->getType(), BuiltinType))
                 NewFD->addAttr(BuiltinAttr::CreateImplicit(Context, BuiltinID));
             }
           }
         } else if (InStdNamespace && NewFD->isInStdNamespace() &&
                    isStdBuiltin(Context, NewFD, BuiltinID)) {
           NewFD->addAttr(BuiltinAttr::CreateImplicit(Context, BuiltinID));
         }
       }
     }
   }
 
   ProcessPragmaWeak(S, NewFD);
   checkAttributesAfterMerging(*this, *NewFD);
 
   AddKnownFunctionAttributes(NewFD);
 
   if (NewFD->hasAttr<OverloadableAttr>() &&
       !NewFD->getType()->getAs<FunctionProtoType>()) {
     Diag(NewFD->getLocation(),
          diag::err_attribute_overloadable_no_prototype)
       << NewFD;
     NewFD->dropAttr<OverloadableAttr>();
   }
 
   // If there's a #pragma GCC visibility in scope, and this isn't a class
   // member, set the visibility of this function.
   if (!DC->isRecord() && NewFD->isExternallyVisible())
     AddPushedVisibilityAttribute(NewFD);
 
   // If there's a #pragma clang arc_cf_code_audited in scope, consider
   // marking the function.
   AddCFAuditedAttribute(NewFD);
 
   // If this is a function definition, check if we have to apply any
   // attributes (i.e. optnone and no_builtin) due to a pragma.
   if (D.isFunctionDefinition()) {
     AddRangeBasedOptnone(NewFD);
     AddImplicitMSFunctionNoBuiltinAttr(NewFD);
     AddSectionMSAllocText(NewFD);
     ModifyFnAttributesMSPragmaOptimize(NewFD);
   }
 
   // If this is the first declaration of an extern C variable, update
   // the map of such variables.
   if (NewFD->isFirstDecl() && !NewFD->isInvalidDecl() &&
       isIncompleteDeclExternC(*this, NewFD))
     RegisterLocallyScopedExternCDecl(NewFD, S);
 
   // Set this FunctionDecl's range up to the right paren.
   NewFD->setRangeEnd(D.getSourceRange().getEnd());
 
   if (D.isRedeclaration() && !Previous.empty()) {
     NamedDecl *Prev = Previous.getRepresentativeDecl();
     checkDLLAttributeRedeclaration(*this, Prev, NewFD,
                                    isMemberSpecialization ||
                                        isFunctionTemplateSpecialization,
                                    D.isFunctionDefinition());
   }
 
   if (getLangOpts().CUDA) {
     IdentifierInfo *II = NewFD->getIdentifier();
     if (II && II->isStr(getCudaConfigureFuncName()) &&
         !NewFD->isInvalidDecl() &&
         NewFD->getDeclContext()->getRedeclContext()->isTranslationUnit()) {
       if (!R->castAs<FunctionType>()->getReturnType()->isScalarType())
         Diag(NewFD->getLocation(), diag::err_config_scalar_return)
             << getCudaConfigureFuncName();
       Context.setcudaConfigureCallDecl(NewFD);
     }
 
     // Variadic functions, other than a *declaration* of printf, are not allowed
     // in device-side CUDA code, unless someone passed
     // -fcuda-allow-variadic-functions.
     if (!getLangOpts().CUDAAllowVariadicFunctions && NewFD->isVariadic() &&
         (NewFD->hasAttr<CUDADeviceAttr>() ||
          NewFD->hasAttr<CUDAGlobalAttr>()) &&
         !(II && II->isStr("printf") && NewFD->isExternC() &&
           !D.isFunctionDefinition())) {
       Diag(NewFD->getLocation(), diag::err_variadic_device_fn);
     }
   }
 
   MarkUnusedFileScopedDecl(NewFD);
 
 
 
   if (getLangOpts().OpenCL && NewFD->hasAttr<OpenCLKernelAttr>()) {
     // OpenCL v1.2 s6.8 static is invalid for kernel functions.
     if (SC == SC_Static) {
       Diag(D.getIdentifierLoc(), diag::err_static_kernel);
       D.setInvalidType();
     }
 
     // OpenCL v1.2, s6.9 -- Kernels can only have return type void.
     if (!NewFD->getReturnType()->isVoidType()) {
       SourceRange RTRange = NewFD->getReturnTypeSourceRange();
       Diag(D.getIdentifierLoc(), diag::err_expected_kernel_void_return_type)
           << (RTRange.isValid() ? FixItHint::CreateReplacement(RTRange, "void")
                                 : FixItHint());
       D.setInvalidType();
     }
 
     llvm::SmallPtrSet<const Type *, 16> ValidTypes;
     for (auto *Param : NewFD->parameters())
       checkIsValidOpenCLKernelParameter(*this, D, Param, ValidTypes);
 
     if (getLangOpts().OpenCLCPlusPlus) {
       if (DC->isRecord()) {
         Diag(D.getIdentifierLoc(), diag::err_method_kernel);
         D.setInvalidType();
       }
       if (FunctionTemplate) {
         Diag(D.getIdentifierLoc(), diag::err_template_kernel);
         D.setInvalidType();
       }
     }
   }
 
   if (getLangOpts().CPlusPlus) {
     // Precalculate whether this is a friend function template with a constraint
     // that depends on an enclosing template, per [temp.friend]p9.
     if (isFriend && FunctionTemplate &&
         FriendConstraintsDependOnEnclosingTemplate(NewFD))
       NewFD->setFriendConstraintRefersToEnclosingTemplate(true);
 
     if (FunctionTemplate) {
       if (NewFD->isInvalidDecl())
         FunctionTemplate->setInvalidDecl();
       return FunctionTemplate;
     }
 
     if (isMemberSpecialization && !NewFD->isInvalidDecl())
       CompleteMemberSpecialization(NewFD, Previous);
   }
 
   for (const ParmVarDecl *Param : NewFD->parameters()) {
     QualType PT = Param->getType();
 
     // OpenCL 2.0 pipe restrictions forbids pipe packet types to be non-value
     // types.
     if (getLangOpts().getOpenCLCompatibleVersion() >= 200) {
       if(const PipeType *PipeTy = PT->getAs<PipeType>()) {
         QualType ElemTy = PipeTy->getElementType();
           if (ElemTy->isReferenceType() || ElemTy->isPointerType()) {
             Diag(Param->getTypeSpecStartLoc(), diag::err_reference_pipe_type );
             D.setInvalidType();
           }
       }
     }
     // WebAssembly tables can't be used as function parameters.
     if (Context.getTargetInfo().getTriple().isWasm()) {
       if (PT->getUnqualifiedDesugaredType()->isWebAssemblyTableType()) {
         Diag(Param->getTypeSpecStartLoc(),
              diag::err_wasm_table_as_function_parameter);
         D.setInvalidType();
       }
     }
   }
 
   // Here we have an function template explicit specialization at class scope.
   // The actual specialization will be postponed to template instatiation
   // time via the ClassScopeFunctionSpecializationDecl node.
   if (isDependentClassScopeExplicitSpecialization) {
     ClassScopeFunctionSpecializationDecl *NewSpec =
                          ClassScopeFunctionSpecializationDecl::Create(
                                 Context, CurContext, NewFD->getLocation(),
                                 cast<CXXMethodDecl>(NewFD),
                                 HasExplicitTemplateArgs, TemplateArgs);
     CurContext->addDecl(NewSpec);
     AddToScope = false;
   }
 
   // Diagnose availability attributes. Availability cannot be used on functions
   // that are run during load/unload.
   if (const auto *attr = NewFD->getAttr<AvailabilityAttr>()) {
     if (NewFD->hasAttr<ConstructorAttr>()) {
       Diag(attr->getLocation(), diag::warn_availability_on_static_initializer)
           << 1;
       NewFD->dropAttr<AvailabilityAttr>();
     }
     if (NewFD->hasAttr<DestructorAttr>()) {
       Diag(attr->getLocation(), diag::warn_availability_on_static_initializer)
           << 2;
       NewFD->dropAttr<AvailabilityAttr>();
     }
   }
 
   // Diagnose no_builtin attribute on function declaration that are not a
   // definition.
   // FIXME: We should really be doing this in
   // SemaDeclAttr.cpp::handleNoBuiltinAttr, unfortunately we only have access to
   // the FunctionDecl and at this point of the code
   // FunctionDecl::isThisDeclarationADefinition() which always returns `false`
   // because Sema::ActOnStartOfFunctionDef has not been called yet.
   if (const auto *NBA = NewFD->getAttr<NoBuiltinAttr>())
     switch (D.getFunctionDefinitionKind()) {
     case FunctionDefinitionKind::Defaulted:
     case FunctionDefinitionKind::Deleted:
       Diag(NBA->getLocation(),
            diag::err_attribute_no_builtin_on_defaulted_deleted_function)
           << NBA->getSpelling();
       break;
     case FunctionDefinitionKind::Declaration:
       Diag(NBA->getLocation(), diag::err_attribute_no_builtin_on_non_definition)
           << NBA->getSpelling();
       break;
     case FunctionDefinitionKind::Definition:
       break;
     }
 
   return NewFD;
 }
 
 /// Return a CodeSegAttr from a containing class.  The Microsoft docs say
 /// when __declspec(code_seg) "is applied to a class, all member functions of
 /// the class and nested classes -- this includes compiler-generated special
 /// member functions -- are put in the specified segment."
 /// The actual behavior is a little more complicated. The Microsoft compiler
 /// won't check outer classes if there is an active value from #pragma code_seg.
 /// The CodeSeg is always applied from the direct parent but only from outer
 /// classes when the #pragma code_seg stack is empty. See:
 /// https://reviews.llvm.org/D22931, the Microsoft feedback page is no longer
 /// available since MS has removed the page.
 static Attr *getImplicitCodeSegAttrFromClass(Sema &S, const FunctionDecl *FD) {
   const auto *Method = dyn_cast<CXXMethodDecl>(FD);
   if (!Method)
     return nullptr;
   const CXXRecordDecl *Parent = Method->getParent();
   if (const auto *SAttr = Parent->getAttr<CodeSegAttr>()) {
     Attr *NewAttr = SAttr->clone(S.getASTContext());
     NewAttr->setImplicit(true);
     return NewAttr;
   }
 
   // The Microsoft compiler won't check outer classes for the CodeSeg
   // when the #pragma code_seg stack is active.
   if (S.CodeSegStack.CurrentValue)
    return nullptr;
 
   while ((Parent = dyn_cast<CXXRecordDecl>(Parent->getParent()))) {
     if (const auto *SAttr = Parent->getAttr<CodeSegAttr>()) {
       Attr *NewAttr = SAttr->clone(S.getASTContext());
       NewAttr->setImplicit(true);
       return NewAttr;
     }
   }
   return nullptr;
 }
 
 /// Returns an implicit CodeSegAttr if a __declspec(code_seg) is found on a
 /// containing class. Otherwise it will return implicit SectionAttr if the
 /// function is a definition and there is an active value on CodeSegStack
 /// (from the current #pragma code-seg value).
 ///
 /// \param FD Function being declared.
 /// \param IsDefinition Whether it is a definition or just a declaration.
 /// \returns A CodeSegAttr or SectionAttr to apply to the function or
 ///          nullptr if no attribute should be added.
 Attr *Sema::getImplicitCodeSegOrSectionAttrForFunction(const FunctionDecl *FD,
                                                        bool IsDefinition) {
   if (Attr *A = getImplicitCodeSegAttrFromClass(*this, FD))
     return A;
   if (!FD->hasAttr<SectionAttr>() && IsDefinition &&
       CodeSegStack.CurrentValue)
     return SectionAttr::CreateImplicit(
         getASTContext(), CodeSegStack.CurrentValue->getString(),
         CodeSegStack.CurrentPragmaLocation, SectionAttr::Declspec_allocate);
   return nullptr;
 }
 
 /// Determines if we can perform a correct type check for \p D as a
 /// redeclaration of \p PrevDecl. If not, we can generally still perform a
 /// best-effort check.
 ///
 /// \param NewD The new declaration.
 /// \param OldD The old declaration.
 /// \param NewT The portion of the type of the new declaration to check.
 /// \param OldT The portion of the type of the old declaration to check.
 bool Sema::canFullyTypeCheckRedeclaration(ValueDecl *NewD, ValueDecl *OldD,
                                           QualType NewT, QualType OldT) {
   if (!NewD->getLexicalDeclContext()->isDependentContext())
     return true;
 
   // For dependently-typed local extern declarations and friends, we can't
   // perform a correct type check in general until instantiation:
   //
   //   int f();
   //   template<typename T> void g() { T f(); }
   //
   // (valid if g() is only instantiated with T = int).
   if (NewT->isDependentType() &&
       (NewD->isLocalExternDecl() || NewD->getFriendObjectKind()))
     return false;
 
   // Similarly, if the previous declaration was a dependent local extern
   // declaration, we don't really know its type yet.
   if (OldT->isDependentType() && OldD->isLocalExternDecl())
     return false;
 
   return true;
 }
 
 /// Checks if the new declaration declared in dependent context must be
 /// put in the same redeclaration chain as the specified declaration.
 ///
 /// \param D Declaration that is checked.
 /// \param PrevDecl Previous declaration found with proper lookup method for the
 ///                 same declaration name.
 /// \returns True if D must be added to the redeclaration chain which PrevDecl
 ///          belongs to.
 ///
 bool Sema::shouldLinkDependentDeclWithPrevious(Decl *D, Decl *PrevDecl) {
   if (!D->getLexicalDeclContext()->isDependentContext())
     return true;
 
   // Don't chain dependent friend function definitions until instantiation, to
   // permit cases like
   //
   //   void func();
   //   template<typename T> class C1 { friend void func() {} };
   //   template<typename T> class C2 { friend void func() {} };
   //
   // ... which is valid if only one of C1 and C2 is ever instantiated.
   //
   // FIXME: This need only apply to function definitions. For now, we proxy
   // this by checking for a file-scope function. We do not want this to apply
   // to friend declarations nominating member functions, because that gets in
   // the way of access checks.
   if (D->getFriendObjectKind() && D->getDeclContext()->isFileContext())
     return false;
 
   auto *VD = dyn_cast<ValueDecl>(D);
   auto *PrevVD = dyn_cast<ValueDecl>(PrevDecl);
   return !VD || !PrevVD ||
          canFullyTypeCheckRedeclaration(VD, PrevVD, VD->getType(),
                                         PrevVD->getType());
 }
 
 /// Check the target or target_version attribute of the function for
 /// MultiVersion validity.
 ///
 /// Returns true if there was an error, false otherwise.
 static bool CheckMultiVersionValue(Sema &S, const FunctionDecl *FD) {
   const auto *TA = FD->getAttr<TargetAttr>();
   const auto *TVA = FD->getAttr<TargetVersionAttr>();
   assert(
       (TA || TVA) &&
       "MultiVersion candidate requires a target or target_version attribute");
   const TargetInfo &TargetInfo = S.Context.getTargetInfo();
   enum ErrType { Feature = 0, Architecture = 1 };
 
   if (TA) {
     ParsedTargetAttr ParseInfo =
         S.getASTContext().getTargetInfo().parseTargetAttr(TA->getFeaturesStr());
     if (!ParseInfo.CPU.empty() && !TargetInfo.validateCpuIs(ParseInfo.CPU)) {
       S.Diag(FD->getLocation(), diag::err_bad_multiversion_option)
           << Architecture << ParseInfo.CPU;
       return true;
     }
     for (const auto &Feat : ParseInfo.Features) {
       auto BareFeat = StringRef{Feat}.substr(1);
       if (Feat[0] == '-') {
         S.Diag(FD->getLocation(), diag::err_bad_multiversion_option)
             << Feature << ("no-" + BareFeat).str();
         return true;
       }
 
       if (!TargetInfo.validateCpuSupports(BareFeat) ||
           !TargetInfo.isValidFeatureName(BareFeat)) {
         S.Diag(FD->getLocation(), diag::err_bad_multiversion_option)
             << Feature << BareFeat;
         return true;
       }
     }
   }
 
   if (TVA) {
     llvm::SmallVector<StringRef, 8> Feats;
     TVA->getFeatures(Feats);
     for (const auto &Feat : Feats) {
       if (!TargetInfo.validateCpuSupports(Feat)) {
         S.Diag(FD->getLocation(), diag::err_bad_multiversion_option)
             << Feature << Feat;
         return true;
       }
     }
   }
   return false;
 }
 
 // Provide a white-list of attributes that are allowed to be combined with
 // multiversion functions.
 static bool AttrCompatibleWithMultiVersion(attr::Kind Kind,
                                            MultiVersionKind MVKind) {
   // Note: this list/diagnosis must match the list in
   // checkMultiversionAttributesAllSame.
   switch (Kind) {
   default:
     return false;
   case attr::Used:
     return MVKind == MultiVersionKind::Target;
   case attr::NonNull:
   case attr::NoThrow:
     return true;
   }
 }
 
 static bool checkNonMultiVersionCompatAttributes(Sema &S,
                                                  const FunctionDecl *FD,
                                                  const FunctionDecl *CausedFD,
                                                  MultiVersionKind MVKind) {
   const auto Diagnose = [FD, CausedFD, MVKind](Sema &S, const Attr *A) {
     S.Diag(FD->getLocation(), diag::err_multiversion_disallowed_other_attr)
         << static_cast<unsigned>(MVKind) << A;
     if (CausedFD)
       S.Diag(CausedFD->getLocation(), diag::note_multiversioning_caused_here);
     return true;
   };
 
   for (const Attr *A : FD->attrs()) {
     switch (A->getKind()) {
     case attr::CPUDispatch:
     case attr::CPUSpecific:
       if (MVKind != MultiVersionKind::CPUDispatch &&
           MVKind != MultiVersionKind::CPUSpecific)
         return Diagnose(S, A);
       break;
     case attr::Target:
       if (MVKind != MultiVersionKind::Target)
         return Diagnose(S, A);
       break;
     case attr::TargetVersion:
       if (MVKind != MultiVersionKind::TargetVersion)
         return Diagnose(S, A);
       break;
     case attr::TargetClones:
       if (MVKind != MultiVersionKind::TargetClones)
         return Diagnose(S, A);
       break;
     default:
       if (!AttrCompatibleWithMultiVersion(A->getKind(), MVKind))
         return Diagnose(S, A);
       break;
     }
   }
   return false;
 }
 
 bool Sema::areMultiversionVariantFunctionsCompatible(
     const FunctionDecl *OldFD, const FunctionDecl *NewFD,
     const PartialDiagnostic &NoProtoDiagID,
     const PartialDiagnosticAt &NoteCausedDiagIDAt,
     const PartialDiagnosticAt &NoSupportDiagIDAt,
     const PartialDiagnosticAt &DiffDiagIDAt, bool TemplatesSupported,
     bool ConstexprSupported, bool CLinkageMayDiffer) {
   enum DoesntSupport {
     FuncTemplates = 0,
     VirtFuncs = 1,
     DeducedReturn = 2,
     Constructors = 3,
     Destructors = 4,
     DeletedFuncs = 5,
     DefaultedFuncs = 6,
     ConstexprFuncs = 7,
     ConstevalFuncs = 8,
     Lambda = 9,
   };
   enum Different {
     CallingConv = 0,
     ReturnType = 1,
     ConstexprSpec = 2,
     InlineSpec = 3,
     Linkage = 4,
     LanguageLinkage = 5,
   };
 
   if (NoProtoDiagID.getDiagID() != 0 && OldFD &&
       !OldFD->getType()->getAs<FunctionProtoType>()) {
     Diag(OldFD->getLocation(), NoProtoDiagID);
     Diag(NoteCausedDiagIDAt.first, NoteCausedDiagIDAt.second);
     return true;
   }
 
   if (NoProtoDiagID.getDiagID() != 0 &&
       !NewFD->getType()->getAs<FunctionProtoType>())
     return Diag(NewFD->getLocation(), NoProtoDiagID);
 
   if (!TemplatesSupported &&
       NewFD->getTemplatedKind() == FunctionDecl::TK_FunctionTemplate)
     return Diag(NoSupportDiagIDAt.first, NoSupportDiagIDAt.second)
            << FuncTemplates;
 
   if (const auto *NewCXXFD = dyn_cast<CXXMethodDecl>(NewFD)) {
     if (NewCXXFD->isVirtual())
       return Diag(NoSupportDiagIDAt.first, NoSupportDiagIDAt.second)
              << VirtFuncs;
 
     if (isa<CXXConstructorDecl>(NewCXXFD))
       return Diag(NoSupportDiagIDAt.first, NoSupportDiagIDAt.second)
              << Constructors;
 
     if (isa<CXXDestructorDecl>(NewCXXFD))
       return Diag(NoSupportDiagIDAt.first, NoSupportDiagIDAt.second)
              << Destructors;
   }
 
   if (NewFD->isDeleted())
     return Diag(NoSupportDiagIDAt.first, NoSupportDiagIDAt.second)
            << DeletedFuncs;
 
   if (NewFD->isDefaulted())
     return Diag(NoSupportDiagIDAt.first, NoSupportDiagIDAt.second)
            << DefaultedFuncs;
 
   if (!ConstexprSupported && NewFD->isConstexpr())
     return Diag(NoSupportDiagIDAt.first, NoSupportDiagIDAt.second)
            << (NewFD->isConsteval() ? ConstevalFuncs : ConstexprFuncs);
 
   QualType NewQType = Context.getCanonicalType(NewFD->getType());
   const auto *NewType = cast<FunctionType>(NewQType);
   QualType NewReturnType = NewType->getReturnType();
 
   if (NewReturnType->isUndeducedType())
     return Diag(NoSupportDiagIDAt.first, NoSupportDiagIDAt.second)
            << DeducedReturn;
 
   // Ensure the return type is identical.
   if (OldFD) {
     QualType OldQType = Context.getCanonicalType(OldFD->getType());
     const auto *OldType = cast<FunctionType>(OldQType);
     FunctionType::ExtInfo OldTypeInfo = OldType->getExtInfo();
     FunctionType::ExtInfo NewTypeInfo = NewType->getExtInfo();
 
     if (OldTypeInfo.getCC() != NewTypeInfo.getCC())
       return Diag(DiffDiagIDAt.first, DiffDiagIDAt.second) << CallingConv;
 
     QualType OldReturnType = OldType->getReturnType();
 
     if (OldReturnType != NewReturnType)
       return Diag(DiffDiagIDAt.first, DiffDiagIDAt.second) << ReturnType;
 
     if (OldFD->getConstexprKind() != NewFD->getConstexprKind())
       return Diag(DiffDiagIDAt.first, DiffDiagIDAt.second) << ConstexprSpec;
 
     if (OldFD->isInlineSpecified() != NewFD->isInlineSpecified())
       return Diag(DiffDiagIDAt.first, DiffDiagIDAt.second) << InlineSpec;
 
     if (OldFD->getFormalLinkage() != NewFD->getFormalLinkage())
       return Diag(DiffDiagIDAt.first, DiffDiagIDAt.second) << Linkage;
 
     if (!CLinkageMayDiffer && OldFD->isExternC() != NewFD->isExternC())
       return Diag(DiffDiagIDAt.first, DiffDiagIDAt.second) << LanguageLinkage;
 
     if (CheckEquivalentExceptionSpec(
             OldFD->getType()->getAs<FunctionProtoType>(), OldFD->getLocation(),
             NewFD->getType()->getAs<FunctionProtoType>(), NewFD->getLocation()))
       return true;
   }
   return false;
 }
 
 static bool CheckMultiVersionAdditionalRules(Sema &S, const FunctionDecl *OldFD,
                                              const FunctionDecl *NewFD,
                                              bool CausesMV,
                                              MultiVersionKind MVKind) {
   if (!S.getASTContext().getTargetInfo().supportsMultiVersioning()) {
     S.Diag(NewFD->getLocation(), diag::err_multiversion_not_supported);
     if (OldFD)
       S.Diag(OldFD->getLocation(), diag::note_previous_declaration);
     return true;
   }
 
   bool IsCPUSpecificCPUDispatchMVKind =
       MVKind == MultiVersionKind::CPUDispatch ||
       MVKind == MultiVersionKind::CPUSpecific;
 
   if (CausesMV && OldFD &&
       checkNonMultiVersionCompatAttributes(S, OldFD, NewFD, MVKind))
     return true;
 
   if (checkNonMultiVersionCompatAttributes(S, NewFD, nullptr, MVKind))
     return true;
 
   // Only allow transition to MultiVersion if it hasn't been used.
   if (OldFD && CausesMV && OldFD->isUsed(false))
     return S.Diag(NewFD->getLocation(), diag::err_multiversion_after_used);
 
   return S.areMultiversionVariantFunctionsCompatible(
       OldFD, NewFD, S.PDiag(diag::err_multiversion_noproto),
       PartialDiagnosticAt(NewFD->getLocation(),
                           S.PDiag(diag::note_multiversioning_caused_here)),
       PartialDiagnosticAt(NewFD->getLocation(),
                           S.PDiag(diag::err_multiversion_doesnt_support)
                               << static_cast<unsigned>(MVKind)),
       PartialDiagnosticAt(NewFD->getLocation(),
                           S.PDiag(diag::err_multiversion_diff)),
       /*TemplatesSupported=*/false,
       /*ConstexprSupported=*/!IsCPUSpecificCPUDispatchMVKind,
       /*CLinkageMayDiffer=*/false);
 }
 
 /// Check the validity of a multiversion function declaration that is the
 /// first of its kind. Also sets the multiversion'ness' of the function itself.
 ///
 /// This sets NewFD->isInvalidDecl() to true if there was an error.
 ///
 /// Returns true if there was an error, false otherwise.
 static bool CheckMultiVersionFirstFunction(Sema &S, FunctionDecl *FD) {
   MultiVersionKind MVKind = FD->getMultiVersionKind();
   assert(MVKind != MultiVersionKind::None &&
          "Function lacks multiversion attribute");
   const auto *TA = FD->getAttr<TargetAttr>();
   const auto *TVA = FD->getAttr<TargetVersionAttr>();
   // Target and target_version only causes MV if it is default, otherwise this
   // is a normal function.
   if ((TA && !TA->isDefaultVersion()) || (TVA && !TVA->isDefaultVersion()))
     return false;
 
   if ((TA || TVA) && CheckMultiVersionValue(S, FD)) {
     FD->setInvalidDecl();
     return true;
   }
 
   if (CheckMultiVersionAdditionalRules(S, nullptr, FD, true, MVKind)) {
     FD->setInvalidDecl();
     return true;
   }
 
   FD->setIsMultiVersion();
   return false;
 }
 
 static bool PreviousDeclsHaveMultiVersionAttribute(const FunctionDecl *FD) {
   for (const Decl *D = FD->getPreviousDecl(); D; D = D->getPreviousDecl()) {
     if (D->getAsFunction()->getMultiVersionKind() != MultiVersionKind::None)
       return true;
   }
 
   return false;
 }
 
 static bool CheckTargetCausesMultiVersioning(Sema &S, FunctionDecl *OldFD,
                                              FunctionDecl *NewFD,
                                              bool &Redeclaration,
                                              NamedDecl *&OldDecl,
                                              LookupResult &Previous) {
   const auto *NewTA = NewFD->getAttr<TargetAttr>();
   const auto *NewTVA = NewFD->getAttr<TargetVersionAttr>();
   const auto *OldTA = OldFD->getAttr<TargetAttr>();
   const auto *OldTVA = OldFD->getAttr<TargetVersionAttr>();
   // If the old decl is NOT MultiVersioned yet, and we don't cause that
   // to change, this is a simple redeclaration.
   if ((NewTA && !NewTA->isDefaultVersion() &&
        (!OldTA || OldTA->getFeaturesStr() == NewTA->getFeaturesStr())) ||
       (NewTVA && !NewTVA->isDefaultVersion() &&
        (!OldTVA || OldTVA->getName() == NewTVA->getName())))
     return false;
 
   // Otherwise, this decl causes MultiVersioning.
   if (CheckMultiVersionAdditionalRules(S, OldFD, NewFD, true,
                                        NewTVA ? MultiVersionKind::TargetVersion
                                               : MultiVersionKind::Target)) {
     NewFD->setInvalidDecl();
     return true;
   }
 
   if (CheckMultiVersionValue(S, NewFD)) {
     NewFD->setInvalidDecl();
     return true;
   }
 
   // If this is 'default', permit the forward declaration.
   if (!OldFD->isMultiVersion() &&
       ((NewTA && NewTA->isDefaultVersion() && !OldTA) ||
        (NewTVA && NewTVA->isDefaultVersion() && !OldTVA))) {
     Redeclaration = true;
     OldDecl = OldFD;
     OldFD->setIsMultiVersion();
     NewFD->setIsMultiVersion();
     return false;
   }
 
   if (CheckMultiVersionValue(S, OldFD)) {
     S.Diag(NewFD->getLocation(), diag::note_multiversioning_caused_here);
     NewFD->setInvalidDecl();
     return true;
   }
 
   if (NewTA) {
     ParsedTargetAttr OldParsed =
         S.getASTContext().getTargetInfo().parseTargetAttr(
             OldTA->getFeaturesStr());
     llvm::sort(OldParsed.Features);
     ParsedTargetAttr NewParsed =
         S.getASTContext().getTargetInfo().parseTargetAttr(
             NewTA->getFeaturesStr());
     // Sort order doesn't matter, it just needs to be consistent.
     llvm::sort(NewParsed.Features);
     if (OldParsed == NewParsed) {
       S.Diag(NewFD->getLocation(), diag::err_multiversion_duplicate);
       S.Diag(OldFD->getLocation(), diag::note_previous_declaration);
       NewFD->setInvalidDecl();
       return true;
     }
   }
 
   if (NewTVA) {
     llvm::SmallVector<StringRef, 8> Feats;
     OldTVA->getFeatures(Feats);
     llvm::sort(Feats);
     llvm::SmallVector<StringRef, 8> NewFeats;
     NewTVA->getFeatures(NewFeats);
     llvm::sort(NewFeats);
 
     if (Feats == NewFeats) {
       S.Diag(NewFD->getLocation(), diag::err_multiversion_duplicate);
       S.Diag(OldFD->getLocation(), diag::note_previous_declaration);
       NewFD->setInvalidDecl();
       return true;
     }
   }
 
   for (const auto *FD : OldFD->redecls()) {
     const auto *CurTA = FD->getAttr<TargetAttr>();
     const auto *CurTVA = FD->getAttr<TargetVersionAttr>();
     // We allow forward declarations before ANY multiversioning attributes, but
     // nothing after the fact.
     if (PreviousDeclsHaveMultiVersionAttribute(FD) &&
         ((NewTA && (!CurTA || CurTA->isInherited())) ||
          (NewTVA && (!CurTVA || CurTVA->isInherited())))) {
       S.Diag(FD->getLocation(), diag::err_multiversion_required_in_redecl)
           << (NewTA ? 0 : 2);
       S.Diag(NewFD->getLocation(), diag::note_multiversioning_caused_here);
       NewFD->setInvalidDecl();
       return true;
     }
   }
 
   OldFD->setIsMultiVersion();
   NewFD->setIsMultiVersion();
   Redeclaration = false;
   OldDecl = nullptr;
   Previous.clear();
   return false;
 }
 
 static bool MultiVersionTypesCompatible(MultiVersionKind Old,
                                         MultiVersionKind New) {
   if (Old == New || Old == MultiVersionKind::None ||
       New == MultiVersionKind::None)
     return true;
 
   return (Old == MultiVersionKind::CPUDispatch &&
           New == MultiVersionKind::CPUSpecific) ||
          (Old == MultiVersionKind::CPUSpecific &&
           New == MultiVersionKind::CPUDispatch);
 }
 
 /// Check the validity of a new function declaration being added to an existing
 /// multiversioned declaration collection.
 static bool CheckMultiVersionAdditionalDecl(
     Sema &S, FunctionDecl *OldFD, FunctionDecl *NewFD,
     MultiVersionKind NewMVKind, const CPUDispatchAttr *NewCPUDisp,
     const CPUSpecificAttr *NewCPUSpec, const TargetClonesAttr *NewClones,
     bool &Redeclaration, NamedDecl *&OldDecl, LookupResult &Previous) {
   const auto *NewTA = NewFD->getAttr<TargetAttr>();
   const auto *NewTVA = NewFD->getAttr<TargetVersionAttr>();
   MultiVersionKind OldMVKind = OldFD->getMultiVersionKind();
   // Disallow mixing of multiversioning types.
   if (!MultiVersionTypesCompatible(OldMVKind, NewMVKind)) {
     S.Diag(NewFD->getLocation(), diag::err_multiversion_types_mixed);
     S.Diag(OldFD->getLocation(), diag::note_previous_declaration);
     NewFD->setInvalidDecl();
     return true;
   }
 
   ParsedTargetAttr NewParsed;
   if (NewTA) {
     NewParsed = S.getASTContext().getTargetInfo().parseTargetAttr(
         NewTA->getFeaturesStr());
     llvm::sort(NewParsed.Features);
   }
   llvm::SmallVector<StringRef, 8> NewFeats;
   if (NewTVA) {
     NewTVA->getFeatures(NewFeats);
     llvm::sort(NewFeats);
   }
 
   bool UseMemberUsingDeclRules =
       S.CurContext->isRecord() && !NewFD->getFriendObjectKind();
 
   bool MayNeedOverloadableChecks =
       AllowOverloadingOfFunction(Previous, S.Context, NewFD);
 
   // Next, check ALL non-invalid non-overloads to see if this is a redeclaration
   // of a previous member of the MultiVersion set.
   for (NamedDecl *ND : Previous) {
     FunctionDecl *CurFD = ND->getAsFunction();
     if (!CurFD || CurFD->isInvalidDecl())
       continue;
     if (MayNeedOverloadableChecks &&
         S.IsOverload(NewFD, CurFD, UseMemberUsingDeclRules))
       continue;
 
     if (NewMVKind == MultiVersionKind::None &&
         OldMVKind == MultiVersionKind::TargetVersion) {
       NewFD->addAttr(TargetVersionAttr::CreateImplicit(
           S.Context, "default", NewFD->getSourceRange()));
       NewFD->setIsMultiVersion();
       NewMVKind = MultiVersionKind::TargetVersion;
       if (!NewTVA) {
         NewTVA = NewFD->getAttr<TargetVersionAttr>();
         NewTVA->getFeatures(NewFeats);
         llvm::sort(NewFeats);
       }
     }
 
     switch (NewMVKind) {
     case MultiVersionKind::None:
       assert(OldMVKind == MultiVersionKind::TargetClones &&
              "Only target_clones can be omitted in subsequent declarations");
       break;
     case MultiVersionKind::Target: {
       const auto *CurTA = CurFD->getAttr<TargetAttr>();
       if (CurTA->getFeaturesStr() == NewTA->getFeaturesStr()) {
         NewFD->setIsMultiVersion();
         Redeclaration = true;
         OldDecl = ND;
         return false;
       }
 
       ParsedTargetAttr CurParsed =
           S.getASTContext().getTargetInfo().parseTargetAttr(
               CurTA->getFeaturesStr());
       llvm::sort(CurParsed.Features);
       if (CurParsed == NewParsed) {
         S.Diag(NewFD->getLocation(), diag::err_multiversion_duplicate);
         S.Diag(CurFD->getLocation(), diag::note_previous_declaration);
         NewFD->setInvalidDecl();
         return true;
       }
       break;
     }
     case MultiVersionKind::TargetVersion: {
       const auto *CurTVA = CurFD->getAttr<TargetVersionAttr>();
       if (CurTVA->getName() == NewTVA->getName()) {
         NewFD->setIsMultiVersion();
         Redeclaration = true;
         OldDecl = ND;
         return false;
       }
       llvm::SmallVector<StringRef, 8> CurFeats;
       if (CurTVA) {
         CurTVA->getFeatures(CurFeats);
         llvm::sort(CurFeats);
       }
       if (CurFeats == NewFeats) {
         S.Diag(NewFD->getLocation(), diag::err_multiversion_duplicate);
         S.Diag(CurFD->getLocation(), diag::note_previous_declaration);
         NewFD->setInvalidDecl();
         return true;
       }
       break;
     }
     case MultiVersionKind::TargetClones: {
       const auto *CurClones = CurFD->getAttr<TargetClonesAttr>();
       Redeclaration = true;
       OldDecl = CurFD;
       NewFD->setIsMultiVersion();
 
       if (CurClones && NewClones &&
           (CurClones->featuresStrs_size() != NewClones->featuresStrs_size() ||
            !std::equal(CurClones->featuresStrs_begin(),
                        CurClones->featuresStrs_end(),
                        NewClones->featuresStrs_begin()))) {
         S.Diag(NewFD->getLocation(), diag::err_target_clone_doesnt_match);
         S.Diag(CurFD->getLocation(), diag::note_previous_declaration);
         NewFD->setInvalidDecl();
         return true;
       }
 
       return false;
     }
     case MultiVersionKind::CPUSpecific:
     case MultiVersionKind::CPUDispatch: {
       const auto *CurCPUSpec = CurFD->getAttr<CPUSpecificAttr>();
       const auto *CurCPUDisp = CurFD->getAttr<CPUDispatchAttr>();
       // Handle CPUDispatch/CPUSpecific versions.
       // Only 1 CPUDispatch function is allowed, this will make it go through
       // the redeclaration errors.
       if (NewMVKind == MultiVersionKind::CPUDispatch &&
           CurFD->hasAttr<CPUDispatchAttr>()) {
         if (CurCPUDisp->cpus_size() == NewCPUDisp->cpus_size() &&
             std::equal(
                 CurCPUDisp->cpus_begin(), CurCPUDisp->cpus_end(),
                 NewCPUDisp->cpus_begin(),
                 [](const IdentifierInfo *Cur, const IdentifierInfo *New) {
                   return Cur->getName() == New->getName();
                 })) {
           NewFD->setIsMultiVersion();
           Redeclaration = true;
           OldDecl = ND;
           return false;
         }
 
         // If the declarations don't match, this is an error condition.
         S.Diag(NewFD->getLocation(), diag::err_cpu_dispatch_mismatch);
         S.Diag(CurFD->getLocation(), diag::note_previous_declaration);
         NewFD->setInvalidDecl();
         return true;
       }
       if (NewMVKind == MultiVersionKind::CPUSpecific && CurCPUSpec) {
         if (CurCPUSpec->cpus_size() == NewCPUSpec->cpus_size() &&
             std::equal(
                 CurCPUSpec->cpus_begin(), CurCPUSpec->cpus_end(),
                 NewCPUSpec->cpus_begin(),
                 [](const IdentifierInfo *Cur, const IdentifierInfo *New) {
                   return Cur->getName() == New->getName();
                 })) {
           NewFD->setIsMultiVersion();
           Redeclaration = true;
           OldDecl = ND;
           return false;
         }
 
         // Only 1 version of CPUSpecific is allowed for each CPU.
         for (const IdentifierInfo *CurII : CurCPUSpec->cpus()) {
           for (const IdentifierInfo *NewII : NewCPUSpec->cpus()) {
             if (CurII == NewII) {
               S.Diag(NewFD->getLocation(), diag::err_cpu_specific_multiple_defs)
                   << NewII;
               S.Diag(CurFD->getLocation(), diag::note_previous_declaration);
               NewFD->setInvalidDecl();
               return true;
             }
           }
         }
       }
       break;
     }
     }
   }
 
   // Else, this is simply a non-redecl case.  Checking the 'value' is only
   // necessary in the Target case, since The CPUSpecific/Dispatch cases are
   // handled in the attribute adding step.
   if ((NewMVKind == MultiVersionKind::TargetVersion ||
        NewMVKind == MultiVersionKind::Target) &&
       CheckMultiVersionValue(S, NewFD)) {
     NewFD->setInvalidDecl();
     return true;
   }
 
   if (CheckMultiVersionAdditionalRules(S, OldFD, NewFD,
                                        !OldFD->isMultiVersion(), NewMVKind)) {
     NewFD->setInvalidDecl();
     return true;
   }
 
   // Permit forward declarations in the case where these two are compatible.
   if (!OldFD->isMultiVersion()) {
     OldFD->setIsMultiVersion();
     NewFD->setIsMultiVersion();
     Redeclaration = true;
     OldDecl = OldFD;
     return false;
   }
 
   NewFD->setIsMultiVersion();
   Redeclaration = false;
   OldDecl = nullptr;
   Previous.clear();
   return false;
 }
 
 /// Check the validity of a mulitversion function declaration.
 /// Also sets the multiversion'ness' of the function itself.
 ///
 /// This sets NewFD->isInvalidDecl() to true if there was an error.
 ///
 /// Returns true if there was an error, false otherwise.
 static bool CheckMultiVersionFunction(Sema &S, FunctionDecl *NewFD,
                                       bool &Redeclaration, NamedDecl *&OldDecl,
                                       LookupResult &Previous) {
   const auto *NewTA = NewFD->getAttr<TargetAttr>();
   const auto *NewTVA = NewFD->getAttr<TargetVersionAttr>();
   const auto *NewCPUDisp = NewFD->getAttr<CPUDispatchAttr>();
   const auto *NewCPUSpec = NewFD->getAttr<CPUSpecificAttr>();
   const auto *NewClones = NewFD->getAttr<TargetClonesAttr>();
   MultiVersionKind MVKind = NewFD->getMultiVersionKind();
 
   // Main isn't allowed to become a multiversion function, however it IS
   // permitted to have 'main' be marked with the 'target' optimization hint,
   // for 'target_version' only default is allowed.
   if (NewFD->isMain()) {
     if (MVKind != MultiVersionKind::None &&
         !(MVKind == MultiVersionKind::Target && !NewTA->isDefaultVersion()) &&
         !(MVKind == MultiVersionKind::TargetVersion &&
           NewTVA->isDefaultVersion())) {
       S.Diag(NewFD->getLocation(), diag::err_multiversion_not_allowed_on_main);
       NewFD->setInvalidDecl();
       return true;
     }
     return false;
   }
 
   // Target attribute on AArch64 is not used for multiversioning
   if (NewTA && S.getASTContext().getTargetInfo().getTriple().isAArch64())
     return false;
 
   if (!OldDecl || !OldDecl->getAsFunction() ||
       OldDecl->getDeclContext()->getRedeclContext() !=
           NewFD->getDeclContext()->getRedeclContext()) {
     // If there's no previous declaration, AND this isn't attempting to cause
     // multiversioning, this isn't an error condition.
     if (MVKind == MultiVersionKind::None)
       return false;
     return CheckMultiVersionFirstFunction(S, NewFD);
   }
 
   FunctionDecl *OldFD = OldDecl->getAsFunction();
 
   if (!OldFD->isMultiVersion() && MVKind == MultiVersionKind::None) {
     // No target_version attributes mean default
     if (!NewTVA) {
       const auto *OldTVA = OldFD->getAttr<TargetVersionAttr>();
       if (OldTVA) {
         NewFD->addAttr(TargetVersionAttr::CreateImplicit(
             S.Context, "default", NewFD->getSourceRange()));
         NewFD->setIsMultiVersion();
         OldFD->setIsMultiVersion();
         OldDecl = OldFD;
         Redeclaration = true;
         return true;
       }
     }
     return false;
   }
 
   // Multiversioned redeclarations aren't allowed to omit the attribute, except
   // for target_clones and target_version.
   if (OldFD->isMultiVersion() && MVKind == MultiVersionKind::None &&
       OldFD->getMultiVersionKind() != MultiVersionKind::TargetClones &&
       OldFD->getMultiVersionKind() != MultiVersionKind::TargetVersion) {
     S.Diag(NewFD->getLocation(), diag::err_multiversion_required_in_redecl)
         << (OldFD->getMultiVersionKind() != MultiVersionKind::Target);
     NewFD->setInvalidDecl();
     return true;
   }
 
   if (!OldFD->isMultiVersion()) {
     switch (MVKind) {
     case MultiVersionKind::Target:
     case MultiVersionKind::TargetVersion:
       return CheckTargetCausesMultiVersioning(S, OldFD, NewFD, Redeclaration,
                                               OldDecl, Previous);
     case MultiVersionKind::TargetClones:
       if (OldFD->isUsed(false)) {
         NewFD->setInvalidDecl();
         return S.Diag(NewFD->getLocation(), diag::err_multiversion_after_used);
       }
       OldFD->setIsMultiVersion();
       break;
 
     case MultiVersionKind::CPUDispatch:
     case MultiVersionKind::CPUSpecific:
     case MultiVersionKind::None:
       break;
     }
   }
 
   // At this point, we have a multiversion function decl (in OldFD) AND an
   // appropriate attribute in the current function decl.  Resolve that these are
   // still compatible with previous declarations.
   return CheckMultiVersionAdditionalDecl(S, OldFD, NewFD, MVKind, NewCPUDisp,
                                          NewCPUSpec, NewClones, Redeclaration,
                                          OldDecl, Previous);
 }
 
 /// Perform semantic checking of a new function declaration.
 ///
 /// Performs semantic analysis of the new function declaration
 /// NewFD. This routine performs all semantic checking that does not
 /// require the actual declarator involved in the declaration, and is
 /// used both for the declaration of functions as they are parsed
 /// (called via ActOnDeclarator) and for the declaration of functions
 /// that have been instantiated via C++ template instantiation (called
 /// via InstantiateDecl).
 ///
 /// \param IsMemberSpecialization whether this new function declaration is
 /// a member specialization (that replaces any definition provided by the
 /// previous declaration).
 ///
 /// This sets NewFD->isInvalidDecl() to true if there was an error.
 ///
 /// \returns true if the function declaration is a redeclaration.
 bool Sema::CheckFunctionDeclaration(Scope *S, FunctionDecl *NewFD,
                                     LookupResult &Previous,
                                     bool IsMemberSpecialization,
                                     bool DeclIsDefn) {
   assert(!NewFD->getReturnType()->isVariablyModifiedType() &&
          "Variably modified return types are not handled here");
 
   // Determine whether the type of this function should be merged with
   // a previous visible declaration. This never happens for functions in C++,
   // and always happens in C if the previous declaration was visible.
   bool MergeTypeWithPrevious = !getLangOpts().CPlusPlus &&
                                !Previous.isShadowed();
 
   bool Redeclaration = false;
   NamedDecl *OldDecl = nullptr;
   bool MayNeedOverloadableChecks = false;
 
   // Merge or overload the declaration with an existing declaration of
   // the same name, if appropriate.
   if (!Previous.empty()) {
     // Determine whether NewFD is an overload of PrevDecl or
     // a declaration that requires merging. If it's an overload,
     // there's no more work to do here; we'll just add the new
     // function to the scope.
     if (!AllowOverloadingOfFunction(Previous, Context, NewFD)) {
       NamedDecl *Candidate = Previous.getRepresentativeDecl();
       if (shouldLinkPossiblyHiddenDecl(Candidate, NewFD)) {
         Redeclaration = true;
         OldDecl = Candidate;
       }
     } else {
       MayNeedOverloadableChecks = true;
       switch (CheckOverload(S, NewFD, Previous, OldDecl,
                             /*NewIsUsingDecl*/ false)) {
       case Ovl_Match:
         Redeclaration = true;
         break;
 
       case Ovl_NonFunction:
         Redeclaration = true;
         break;
 
       case Ovl_Overload:
         Redeclaration = false;
         break;
       }
     }
   }
 
   // Check for a previous extern "C" declaration with this name.
   if (!Redeclaration &&
       checkForConflictWithNonVisibleExternC(*this, NewFD, Previous)) {
     if (!Previous.empty()) {
       // This is an extern "C" declaration with the same name as a previous
       // declaration, and thus redeclares that entity...
       Redeclaration = true;
       OldDecl = Previous.getFoundDecl();
       MergeTypeWithPrevious = false;
 
       // ... except in the presence of __attribute__((overloadable)).
       if (OldDecl->hasAttr<OverloadableAttr>() ||
           NewFD->hasAttr<OverloadableAttr>()) {
         if (IsOverload(NewFD, cast<FunctionDecl>(OldDecl), false)) {
           MayNeedOverloadableChecks = true;
           Redeclaration = false;
           OldDecl = nullptr;
         }
       }
     }
   }
 
   if (CheckMultiVersionFunction(*this, NewFD, Redeclaration, OldDecl, Previous))
     return Redeclaration;
 
   // PPC MMA non-pointer types are not allowed as function return types.
   if (Context.getTargetInfo().getTriple().isPPC64() &&
       CheckPPCMMAType(NewFD->getReturnType(), NewFD->getLocation())) {
     NewFD->setInvalidDecl();
   }
 
   // C++11 [dcl.constexpr]p8:
   //   A constexpr specifier for a non-static member function that is not
   //   a constructor declares that member function to be const.
   //
   // This needs to be delayed until we know whether this is an out-of-line
   // definition of a static member function.
   //
   // This rule is not present in C++1y, so we produce a backwards
   // compatibility warning whenever it happens in C++11.
   CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(NewFD);
   if (!getLangOpts().CPlusPlus14 && MD && MD->isConstexpr() &&
       !MD->isStatic() && !isa<CXXConstructorDecl>(MD) &&
       !isa<CXXDestructorDecl>(MD) && !MD->getMethodQualifiers().hasConst()) {
     CXXMethodDecl *OldMD = nullptr;
     if (OldDecl)
       OldMD = dyn_cast_or_null<CXXMethodDecl>(OldDecl->getAsFunction());
     if (!OldMD || !OldMD->isStatic()) {
       const FunctionProtoType *FPT =
         MD->getType()->castAs<FunctionProtoType>();
       FunctionProtoType::ExtProtoInfo EPI = FPT->getExtProtoInfo();
       EPI.TypeQuals.addConst();
       MD->setType(Context.getFunctionType(FPT->getReturnType(),
                                           FPT->getParamTypes(), EPI));
 
       // Warn that we did this, if we're not performing template instantiation.
       // In that case, we'll have warned already when the template was defined.
       if (!inTemplateInstantiation()) {
         SourceLocation AddConstLoc;
         if (FunctionTypeLoc FTL = MD->getTypeSourceInfo()->getTypeLoc()
                 .IgnoreParens().getAs<FunctionTypeLoc>())
           AddConstLoc = getLocForEndOfToken(FTL.getRParenLoc());
 
         Diag(MD->getLocation(), diag::warn_cxx14_compat_constexpr_not_const)
           << FixItHint::CreateInsertion(AddConstLoc, " const");
       }
     }
   }
 
   if (Redeclaration) {
     // NewFD and OldDecl represent declarations that need to be
     // merged.
     if (MergeFunctionDecl(NewFD, OldDecl, S, MergeTypeWithPrevious,
                           DeclIsDefn)) {
       NewFD->setInvalidDecl();
       return Redeclaration;
     }
 
     Previous.clear();
     Previous.addDecl(OldDecl);
 
     if (FunctionTemplateDecl *OldTemplateDecl =
             dyn_cast<FunctionTemplateDecl>(OldDecl)) {
       auto *OldFD = OldTemplateDecl->getTemplatedDecl();
       FunctionTemplateDecl *NewTemplateDecl
         = NewFD->getDescribedFunctionTemplate();
       assert(NewTemplateDecl && "Template/non-template mismatch");
 
       // The call to MergeFunctionDecl above may have created some state in
       // NewTemplateDecl that needs to be merged with OldTemplateDecl before we
       // can add it as a redeclaration.
       NewTemplateDecl->mergePrevDecl(OldTemplateDecl);
 
       NewFD->setPreviousDeclaration(OldFD);
       if (NewFD->isCXXClassMember()) {
         NewFD->setAccess(OldTemplateDecl->getAccess());
         NewTemplateDecl->setAccess(OldTemplateDecl->getAccess());
       }
 
       // If this is an explicit specialization of a member that is a function
       // template, mark it as a member specialization.
       if (IsMemberSpecialization &&
           NewTemplateDecl->getInstantiatedFromMemberTemplate()) {
         NewTemplateDecl->setMemberSpecialization();
         assert(OldTemplateDecl->isMemberSpecialization());
         // Explicit specializations of a member template do not inherit deleted
         // status from the parent member template that they are specializing.
         if (OldFD->isDeleted()) {
           // FIXME: This assert will not hold in the presence of modules.
           assert(OldFD->getCanonicalDecl() == OldFD);
           // FIXME: We need an update record for this AST mutation.
           OldFD->setDeletedAsWritten(false);
         }
       }
 
     } else {
       if (shouldLinkDependentDeclWithPrevious(NewFD, OldDecl)) {
         auto *OldFD = cast<FunctionDecl>(OldDecl);
         // This needs to happen first so that 'inline' propagates.
         NewFD->setPreviousDeclaration(OldFD);
         if (NewFD->isCXXClassMember())
           NewFD->setAccess(OldFD->getAccess());
       }
     }
   } else if (!getLangOpts().CPlusPlus && MayNeedOverloadableChecks &&
              !NewFD->getAttr<OverloadableAttr>()) {
     assert((Previous.empty() ||
             llvm::any_of(Previous,
                          [](const NamedDecl *ND) {
                            return ND->hasAttr<OverloadableAttr>();
                          })) &&
            "Non-redecls shouldn't happen without overloadable present");
 
     auto OtherUnmarkedIter = llvm::find_if(Previous, [](const NamedDecl *ND) {
       const auto *FD = dyn_cast<FunctionDecl>(ND);
       return FD && !FD->hasAttr<OverloadableAttr>();
     });
 
     if (OtherUnmarkedIter != Previous.end()) {
       Diag(NewFD->getLocation(),
            diag::err_attribute_overloadable_multiple_unmarked_overloads);
       Diag((*OtherUnmarkedIter)->getLocation(),
            diag::note_attribute_overloadable_prev_overload)
           << false;
 
       NewFD->addAttr(OverloadableAttr::CreateImplicit(Context));
     }
   }
 
   if (LangOpts.OpenMP)
     ActOnFinishedFunctionDefinitionInOpenMPAssumeScope(NewFD);
 
   // Semantic checking for this function declaration (in isolation).
 
   if (getLangOpts().CPlusPlus) {
     // C++-specific checks.
     if (CXXConstructorDecl *Constructor = dyn_cast<CXXConstructorDecl>(NewFD)) {
       CheckConstructor(Constructor);
     } else if (CXXDestructorDecl *Destructor =
                    dyn_cast<CXXDestructorDecl>(NewFD)) {
       // We check here for invalid destructor names.
       // If we have a friend destructor declaration that is dependent, we can't
       // diagnose right away because cases like this are still valid:
       // template <class T> struct A { friend T::X::~Y(); };
       // struct B { struct Y { ~Y(); }; using X = Y; };
       // template struct A<B>;
       if (NewFD->getFriendObjectKind() == Decl::FriendObjectKind::FOK_None ||
           !Destructor->getThisType()->isDependentType()) {
         CXXRecordDecl *Record = Destructor->getParent();
         QualType ClassType = Context.getTypeDeclType(Record);
 
         DeclarationName Name = Context.DeclarationNames.getCXXDestructorName(
             Context.getCanonicalType(ClassType));
         if (NewFD->getDeclName() != Name) {
           Diag(NewFD->getLocation(), diag::err_destructor_name);
           NewFD->setInvalidDecl();
           return Redeclaration;
         }
       }
     } else if (auto *Guide = dyn_cast<CXXDeductionGuideDecl>(NewFD)) {
       if (auto *TD = Guide->getDescribedFunctionTemplate())
         CheckDeductionGuideTemplate(TD);
 
       // A deduction guide is not on the list of entities that can be
       // explicitly specialized.
       if (Guide->getTemplateSpecializationKind() == TSK_ExplicitSpecialization)
         Diag(Guide->getBeginLoc(), diag::err_deduction_guide_specialized)
             << /*explicit specialization*/ 1;
     }
 
     // Find any virtual functions that this function overrides.
     if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(NewFD)) {
       if (!Method->isFunctionTemplateSpecialization() &&
           !Method->getDescribedFunctionTemplate() &&
           Method->isCanonicalDecl()) {
         AddOverriddenMethods(Method->getParent(), Method);
       }
       if (Method->isVirtual() && NewFD->getTrailingRequiresClause())
         // C++2a [class.virtual]p6
         // A virtual method shall not have a requires-clause.
         Diag(NewFD->getTrailingRequiresClause()->getBeginLoc(),
              diag::err_constrained_virtual_method);
 
       if (Method->isStatic())
         checkThisInStaticMemberFunctionType(Method);
     }
 
     // C++20: dcl.decl.general p4:
     // The optional requires-clause ([temp.pre]) in an init-declarator or
     // member-declarator shall be present only if the declarator declares a
     // templated function ([dcl.fct]).
     if (Expr *TRC = NewFD->getTrailingRequiresClause()) {
       // [temp.pre]/8:
       // An entity is templated if it is
       // - a template,
       // - an entity defined ([basic.def]) or created ([class.temporary]) in a
       // templated entity,
       // - a member of a templated entity,
       // - an enumerator for an enumeration that is a templated entity, or
       // - the closure type of a lambda-expression ([expr.prim.lambda.closure])
       // appearing in the declaration of a templated entity. [Note 6: A local
       // class, a local or block variable, or a friend function defined in a
       // templated entity is a templated entity.  — end note]
       //
       // A templated function is a function template or a function that is
       // templated. A templated class is a class template or a class that is
       // templated. A templated variable is a variable template or a variable
       // that is templated.
 
       if (!NewFD->getDescribedFunctionTemplate() && // -a template
           // defined... in a templated entity
           !(DeclIsDefn && NewFD->isTemplated()) &&
           // a member of a templated entity
           !(isa<CXXMethodDecl>(NewFD) && NewFD->isTemplated()) &&
           // Don't complain about instantiations, they've already had these
           // rules + others enforced.
           !NewFD->isTemplateInstantiation()) {
         Diag(TRC->getBeginLoc(), diag::err_constrained_non_templated_function);
       }
     }
 
     if (CXXConversionDecl *Conversion = dyn_cast<CXXConversionDecl>(NewFD))
       ActOnConversionDeclarator(Conversion);
 
     // Extra checking for C++ overloaded operators (C++ [over.oper]).
     if (NewFD->isOverloadedOperator() &&
         CheckOverloadedOperatorDeclaration(NewFD)) {
       NewFD->setInvalidDecl();
       return Redeclaration;
     }
 
     // Extra checking for C++0x literal operators (C++0x [over.literal]).
     if (NewFD->getLiteralIdentifier() &&
         CheckLiteralOperatorDeclaration(NewFD)) {
       NewFD->setInvalidDecl();
       return Redeclaration;
     }
 
     // In C++, check default arguments now that we have merged decls. Unless
     // the lexical context is the class, because in this case this is done
     // during delayed parsing anyway.
     if (!CurContext->isRecord())
       CheckCXXDefaultArguments(NewFD);
 
     // If this function is declared as being extern "C", then check to see if
     // the function returns a UDT (class, struct, or union type) that is not C
     // compatible, and if it does, warn the user.
     // But, issue any diagnostic on the first declaration only.
     if (Previous.empty() && NewFD->isExternC()) {
       QualType R = NewFD->getReturnType();
       if (R->isIncompleteType() && !R->isVoidType())
         Diag(NewFD->getLocation(), diag::warn_return_value_udt_incomplete)
             << NewFD << R;
       else if (!R.isPODType(Context) && !R->isVoidType() &&
                !R->isObjCObjectPointerType())
         Diag(NewFD->getLocation(), diag::warn_return_value_udt) << NewFD << R;
     }
 
     // C++1z [dcl.fct]p6:
     //   [...] whether the function has a non-throwing exception-specification
     //   [is] part of the function type
     //
     // This results in an ABI break between C++14 and C++17 for functions whose
     // declared type includes an exception-specification in a parameter or
     // return type. (Exception specifications on the function itself are OK in
     // most cases, and exception specifications are not permitted in most other
     // contexts where they could make it into a mangling.)
     if (!getLangOpts().CPlusPlus17 && !NewFD->getPrimaryTemplate()) {
       auto HasNoexcept = [&](QualType T) -> bool {
         // Strip off declarator chunks that could be between us and a function
         // type. We don't need to look far, exception specifications are very
         // restricted prior to C++17.
         if (auto *RT = T->getAs<ReferenceType>())
           T = RT->getPointeeType();
         else if (T->isAnyPointerType())
           T = T->getPointeeType();
         else if (auto *MPT = T->getAs<MemberPointerType>())
           T = MPT->getPointeeType();
         if (auto *FPT = T->getAs<FunctionProtoType>())
           if (FPT->isNothrow())
             return true;
         return false;
       };
 
       auto *FPT = NewFD->getType()->castAs<FunctionProtoType>();
       bool AnyNoexcept = HasNoexcept(FPT->getReturnType());
       for (QualType T : FPT->param_types())
         AnyNoexcept |= HasNoexcept(T);
       if (AnyNoexcept)
         Diag(NewFD->getLocation(),
              diag::warn_cxx17_compat_exception_spec_in_signature)
             << NewFD;
     }
 
     if (!Redeclaration && LangOpts.CUDA)
       checkCUDATargetOverload(NewFD, Previous);
   }
   return Redeclaration;
 }
 
 void Sema::CheckMain(FunctionDecl* FD, const DeclSpec& DS) {
   // C++11 [basic.start.main]p3:
   //   A program that [...] declares main to be inline, static or
   //   constexpr is ill-formed.
   // C11 6.7.4p4:  In a hosted environment, no function specifier(s) shall
   //   appear in a declaration of main.
   // static main is not an error under C99, but we should warn about it.
   // We accept _Noreturn main as an extension.
   if (FD->getStorageClass() == SC_Static)
     Diag(DS.getStorageClassSpecLoc(), getLangOpts().CPlusPlus
          ? diag::err_static_main : diag::warn_static_main)
       << FixItHint::CreateRemoval(DS.getStorageClassSpecLoc());
   if (FD->isInlineSpecified())
     Diag(DS.getInlineSpecLoc(), diag::err_inline_main)
       << FixItHint::CreateRemoval(DS.getInlineSpecLoc());
   if (DS.isNoreturnSpecified()) {
     SourceLocation NoreturnLoc = DS.getNoreturnSpecLoc();
     SourceRange NoreturnRange(NoreturnLoc, getLocForEndOfToken(NoreturnLoc));
     Diag(NoreturnLoc, diag::ext_noreturn_main);
     Diag(NoreturnLoc, diag::note_main_remove_noreturn)
       << FixItHint::CreateRemoval(NoreturnRange);
   }
   if (FD->isConstexpr()) {
     Diag(DS.getConstexprSpecLoc(), diag::err_constexpr_main)
         << FD->isConsteval()
         << FixItHint::CreateRemoval(DS.getConstexprSpecLoc());
     FD->setConstexprKind(ConstexprSpecKind::Unspecified);
   }
 
   if (getLangOpts().OpenCL) {
     Diag(FD->getLocation(), diag::err_opencl_no_main)
         << FD->hasAttr<OpenCLKernelAttr>();
     FD->setInvalidDecl();
     return;
   }
 
   // Functions named main in hlsl are default entries, but don't have specific
   // signatures they are required to conform to.
   if (getLangOpts().HLSL)
     return;
 
   QualType T = FD->getType();
   assert(T->isFunctionType() && "function decl is not of function type");
   const FunctionType* FT = T->castAs<FunctionType>();
 
   // Set default calling convention for main()
   if (FT->getCallConv() != CC_C) {
     FT = Context.adjustFunctionType(FT, FT->getExtInfo().withCallingConv(CC_C));
     FD->setType(QualType(FT, 0));
     T = Context.getCanonicalType(FD->getType());
   }
 
   if (getLangOpts().GNUMode && !getLangOpts().CPlusPlus) {
     // In C with GNU extensions we allow main() to have non-integer return
     // type, but we should warn about the extension, and we disable the
     // implicit-return-zero rule.
 
     // GCC in C mode accepts qualified 'int'.
     if (Context.hasSameUnqualifiedType(FT->getReturnType(), Context.IntTy))
       FD->setHasImplicitReturnZero(true);
     else {
       Diag(FD->getTypeSpecStartLoc(), diag::ext_main_returns_nonint);
       SourceRange RTRange = FD->getReturnTypeSourceRange();
       if (RTRange.isValid())
         Diag(RTRange.getBegin(), diag::note_main_change_return_type)
             << FixItHint::CreateReplacement(RTRange, "int");
     }
   } else {
     // In C and C++, main magically returns 0 if you fall off the end;
     // set the flag which tells us that.
     // This is C++ [basic.start.main]p5 and C99 5.1.2.2.3.
 
     // All the standards say that main() should return 'int'.
     if (Context.hasSameType(FT->getReturnType(), Context.IntTy))
       FD->setHasImplicitReturnZero(true);
     else {
       // Otherwise, this is just a flat-out error.
       SourceRange RTRange = FD->getReturnTypeSourceRange();
       Diag(FD->getTypeSpecStartLoc(), diag::err_main_returns_nonint)
           << (RTRange.isValid() ? FixItHint::CreateReplacement(RTRange, "int")
                                 : FixItHint());
       FD->setInvalidDecl(true);
     }
   }
 
   // Treat protoless main() as nullary.
   if (isa<FunctionNoProtoType>(FT)) return;
 
   const FunctionProtoType* FTP = cast<const FunctionProtoType>(FT);
   unsigned nparams = FTP->getNumParams();
   assert(FD->getNumParams() == nparams);
 
   bool HasExtraParameters = (nparams > 3);
 
   if (FTP->isVariadic()) {
     Diag(FD->getLocation(), diag::ext_variadic_main);
     // FIXME: if we had information about the location of the ellipsis, we
     // could add a FixIt hint to remove it as a parameter.
   }
 
   // Darwin passes an undocumented fourth argument of type char**.  If
   // other platforms start sprouting these, the logic below will start
   // getting shifty.
   if (nparams == 4 && Context.getTargetInfo().getTriple().isOSDarwin())
     HasExtraParameters = false;
 
   if (HasExtraParameters) {
     Diag(FD->getLocation(), diag::err_main_surplus_args) << nparams;
     FD->setInvalidDecl(true);
     nparams = 3;
   }
 
   // FIXME: a lot of the following diagnostics would be improved
   // if we had some location information about types.
 
   QualType CharPP =
     Context.getPointerType(Context.getPointerType(Context.CharTy));
   QualType Expected[] = { Context.IntTy, CharPP, CharPP, CharPP };
 
   for (unsigned i = 0; i < nparams; ++i) {
     QualType AT = FTP->getParamType(i);
 
     bool mismatch = true;
 
     if (Context.hasSameUnqualifiedType(AT, Expected[i]))
       mismatch = false;
     else if (Expected[i] == CharPP) {
       // As an extension, the following forms are okay:
       //   char const **
       //   char const * const *
       //   char * const *
 
       QualifierCollector qs;
       const PointerType* PT;
       if ((PT = qs.strip(AT)->getAs<PointerType>()) &&
           (PT = qs.strip(PT->getPointeeType())->getAs<PointerType>()) &&
           Context.hasSameType(QualType(qs.strip(PT->getPointeeType()), 0),
                               Context.CharTy)) {
         qs.removeConst();
         mismatch = !qs.empty();
       }
     }
 
     if (mismatch) {
       Diag(FD->getLocation(), diag::err_main_arg_wrong) << i << Expected[i];
       // TODO: suggest replacing given type with expected type
       FD->setInvalidDecl(true);
     }
   }
 
   if (nparams == 1 && !FD->isInvalidDecl()) {
     Diag(FD->getLocation(), diag::warn_main_one_arg);
   }
 
   if (!FD->isInvalidDecl() && FD->getDescribedFunctionTemplate()) {
     Diag(FD->getLocation(), diag::err_mainlike_template_decl) << FD;
     FD->setInvalidDecl();
   }
 }
 
 static bool isDefaultStdCall(FunctionDecl *FD, Sema &S) {
 
   // Default calling convention for main and wmain is __cdecl
   if (FD->getName() == "main" || FD->getName() == "wmain")
     return false;
 
   // Default calling convention for MinGW is __cdecl
   const llvm::Triple &T = S.Context.getTargetInfo().getTriple();
   if (T.isWindowsGNUEnvironment())
     return false;
 
   // Default calling convention for WinMain, wWinMain and DllMain
   // is __stdcall on 32 bit Windows
   if (T.isOSWindows() && T.getArch() == llvm::Triple::x86)
     return true;
 
   return false;
 }
 
 void Sema::CheckMSVCRTEntryPoint(FunctionDecl *FD) {
   QualType T = FD->getType();
   assert(T->isFunctionType() && "function decl is not of function type");
   const FunctionType *FT = T->castAs<FunctionType>();
 
   // Set an implicit return of 'zero' if the function can return some integral,
   // enumeration, pointer or nullptr type.
   if (FT->getReturnType()->isIntegralOrEnumerationType() ||
       FT->getReturnType()->isAnyPointerType() ||
       FT->getReturnType()->isNullPtrType())
     // DllMain is exempt because a return value of zero means it failed.
     if (FD->getName() != "DllMain")
       FD->setHasImplicitReturnZero(true);
 
   // Explicity specified calling conventions are applied to MSVC entry points
   if (!hasExplicitCallingConv(T)) {
     if (isDefaultStdCall(FD, *this)) {
       if (FT->getCallConv() != CC_X86StdCall) {
         FT = Context.adjustFunctionType(
             FT, FT->getExtInfo().withCallingConv(CC_X86StdCall));
         FD->setType(QualType(FT, 0));
       }
     } else if (FT->getCallConv() != CC_C) {
       FT = Context.adjustFunctionType(FT,
                                       FT->getExtInfo().withCallingConv(CC_C));
       FD->setType(QualType(FT, 0));
     }
   }
 
   if (!FD->isInvalidDecl() && FD->getDescribedFunctionTemplate()) {
     Diag(FD->getLocation(), diag::err_mainlike_template_decl) << FD;
     FD->setInvalidDecl();
   }
 }
 
 void Sema::CheckHLSLEntryPoint(FunctionDecl *FD) {
   auto &TargetInfo = getASTContext().getTargetInfo();
   auto const Triple = TargetInfo.getTriple();
   switch (Triple.getEnvironment()) {
   default:
     // FIXME: check all shader profiles.
     break;
   case llvm::Triple::EnvironmentType::Compute:
     if (!FD->hasAttr<HLSLNumThreadsAttr>()) {
       Diag(FD->getLocation(), diag::err_hlsl_missing_numthreads)
           << Triple.getEnvironmentName();
       FD->setInvalidDecl();
     }
     break;
   }
 
   for (const auto *Param : FD->parameters()) {
     if (!Param->hasAttr<HLSLAnnotationAttr>()) {
       // FIXME: Handle struct parameters where annotations are on struct fields.
       // See: https://github.com/llvm/llvm-project/issues/57875
       Diag(FD->getLocation(), diag::err_hlsl_missing_semantic_annotation);
       Diag(Param->getLocation(), diag::note_previous_decl) << Param;
       FD->setInvalidDecl();
     }
   }
   // FIXME: Verify return type semantic annotation.
 }
 
 bool Sema::CheckForConstantInitializer(Expr *Init, QualType DclT) {
   // FIXME: Need strict checking.  In C89, we need to check for
   // any assignment, increment, decrement, function-calls, or
   // commas outside of a sizeof.  In C99, it's the same list,
   // except that the aforementioned are allowed in unevaluated
   // expressions.  Everything else falls under the
   // "may accept other forms of constant expressions" exception.
   //
   // Regular C++ code will not end up here (exceptions: language extensions,
   // OpenCL C++ etc), so the constant expression rules there don't matter.
   if (Init->isValueDependent()) {
     assert(Init->containsErrors() &&
            "Dependent code should only occur in error-recovery path.");
     return true;
   }
   const Expr *Culprit;
   if (Init->isConstantInitializer(Context, false, &Culprit))
     return false;
   Diag(Culprit->getExprLoc(), diag::err_init_element_not_constant)
     << Culprit->getSourceRange();
   return true;
 }
 
 namespace {
   // Visits an initialization expression to see if OrigDecl is evaluated in
   // its own initialization and throws a warning if it does.
   class SelfReferenceChecker
       : public EvaluatedExprVisitor<SelfReferenceChecker> {
     Sema &S;
     Decl *OrigDecl;
     bool isRecordType;
     bool isPODType;
     bool isReferenceType;
 
     bool isInitList;
     llvm::SmallVector<unsigned, 4> InitFieldIndex;
 
   public:
     typedef EvaluatedExprVisitor<SelfReferenceChecker> Inherited;
 
     SelfReferenceChecker(Sema &S, Decl *OrigDecl) : Inherited(S.Context),
                                                     S(S), OrigDecl(OrigDecl) {
       isPODType = false;
       isRecordType = false;
       isReferenceType = false;
       isInitList = false;
       if (ValueDecl *VD = dyn_cast<ValueDecl>(OrigDecl)) {
         isPODType = VD->getType().isPODType(S.Context);
         isRecordType = VD->getType()->isRecordType();
         isReferenceType = VD->getType()->isReferenceType();
       }
     }
 
     // For most expressions, just call the visitor.  For initializer lists,
     // track the index of the field being initialized since fields are
     // initialized in order allowing use of previously initialized fields.
     void CheckExpr(Expr *E) {
       InitListExpr *InitList = dyn_cast<InitListExpr>(E);
       if (!InitList) {
         Visit(E);
         return;
       }
 
       // Track and increment the index here.
       isInitList = true;
       InitFieldIndex.push_back(0);
       for (auto *Child : InitList->children()) {
         CheckExpr(cast<Expr>(Child));
         ++InitFieldIndex.back();
       }
       InitFieldIndex.pop_back();
     }
 
     // Returns true if MemberExpr is checked and no further checking is needed.
     // Returns false if additional checking is required.
     bool CheckInitListMemberExpr(MemberExpr *E, bool CheckReference) {
       llvm::SmallVector<FieldDecl*, 4> Fields;
       Expr *Base = E;
       bool ReferenceField = false;
 
       // Get the field members used.
       while (MemberExpr *ME = dyn_cast<MemberExpr>(Base)) {
         FieldDecl *FD = dyn_cast<FieldDecl>(ME->getMemberDecl());
         if (!FD)
           return false;
         Fields.push_back(FD);
         if (FD->getType()->isReferenceType())
           ReferenceField = true;
         Base = ME->getBase()->IgnoreParenImpCasts();
       }
 
       // Keep checking only if the base Decl is the same.
       DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Base);
       if (!DRE || DRE->getDecl() != OrigDecl)
         return false;
 
       // A reference field can be bound to an unininitialized field.
       if (CheckReference && !ReferenceField)
         return true;
 
       // Convert FieldDecls to their index number.
       llvm::SmallVector<unsigned, 4> UsedFieldIndex;
       for (const FieldDecl *I : llvm::reverse(Fields))
         UsedFieldIndex.push_back(I->getFieldIndex());
 
       // See if a warning is needed by checking the first difference in index
       // numbers.  If field being used has index less than the field being
       // initialized, then the use is safe.
       for (auto UsedIter = UsedFieldIndex.begin(),
                 UsedEnd = UsedFieldIndex.end(),
                 OrigIter = InitFieldIndex.begin(),
                 OrigEnd = InitFieldIndex.end();
            UsedIter != UsedEnd && OrigIter != OrigEnd; ++UsedIter, ++OrigIter) {
         if (*UsedIter < *OrigIter)
           return true;
         if (*UsedIter > *OrigIter)
           break;
       }
 
       // TODO: Add a different warning which will print the field names.
       HandleDeclRefExpr(DRE);
       return true;
     }
 
     // For most expressions, the cast is directly above the DeclRefExpr.
     // For conditional operators, the cast can be outside the conditional
     // operator if both expressions are DeclRefExpr's.
     void HandleValue(Expr *E) {
       E = E->IgnoreParens();
       if (DeclRefExpr* DRE = dyn_cast<DeclRefExpr>(E)) {
         HandleDeclRefExpr(DRE);
         return;
       }
 
       if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
         Visit(CO->getCond());
         HandleValue(CO->getTrueExpr());
         HandleValue(CO->getFalseExpr());
         return;
       }
 
       if (BinaryConditionalOperator *BCO =
               dyn_cast<BinaryConditionalOperator>(E)) {
         Visit(BCO->getCond());
         HandleValue(BCO->getFalseExpr());
         return;
       }
 
       if (OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(E)) {
         HandleValue(OVE->getSourceExpr());
         return;
       }
 
       if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
         if (BO->getOpcode() == BO_Comma) {
           Visit(BO->getLHS());
           HandleValue(BO->getRHS());
           return;
         }
       }
 
       if (isa<MemberExpr>(E)) {
         if (isInitList) {
           if (CheckInitListMemberExpr(cast<MemberExpr>(E),
                                       false /*CheckReference*/))
             return;
         }
 
         Expr *Base = E->IgnoreParenImpCasts();
         while (MemberExpr *ME = dyn_cast<MemberExpr>(Base)) {
           // Check for static member variables and don't warn on them.
           if (!isa<FieldDecl>(ME->getMemberDecl()))
             return;
           Base = ME->getBase()->IgnoreParenImpCasts();
         }
         if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Base))
           HandleDeclRefExpr(DRE);
         return;
       }
 
       Visit(E);
     }
 
     // Reference types not handled in HandleValue are handled here since all
     // uses of references are bad, not just r-value uses.
     void VisitDeclRefExpr(DeclRefExpr *E) {
       if (isReferenceType)
         HandleDeclRefExpr(E);
     }
 
     void VisitImplicitCastExpr(ImplicitCastExpr *E) {
       if (E->getCastKind() == CK_LValueToRValue) {
         HandleValue(E->getSubExpr());
         return;
       }
 
       Inherited::VisitImplicitCastExpr(E);
     }
 
     void VisitMemberExpr(MemberExpr *E) {
       if (isInitList) {
         if (CheckInitListMemberExpr(E, true /*CheckReference*/))
           return;
       }
 
       // Don't warn on arrays since they can be treated as pointers.
       if (E->getType()->canDecayToPointerType()) return;
 
       // Warn when a non-static method call is followed by non-static member
       // field accesses, which is followed by a DeclRefExpr.
       CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(E->getMemberDecl());
       bool Warn = (MD && !MD->isStatic());
       Expr *Base = E->getBase()->IgnoreParenImpCasts();
       while (MemberExpr *ME = dyn_cast<MemberExpr>(Base)) {
         if (!isa<FieldDecl>(ME->getMemberDecl()))
           Warn = false;
         Base = ME->getBase()->IgnoreParenImpCasts();
       }
 
       if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Base)) {
         if (Warn)
           HandleDeclRefExpr(DRE);
         return;
       }
 
       // The base of a MemberExpr is not a MemberExpr or a DeclRefExpr.
       // Visit that expression.
       Visit(Base);
     }
 
     void VisitCXXOperatorCallExpr(CXXOperatorCallExpr *E) {
       Expr *Callee = E->getCallee();
 
       if (isa<UnresolvedLookupExpr>(Callee))
         return Inherited::VisitCXXOperatorCallExpr(E);
 
       Visit(Callee);
       for (auto Arg: E->arguments())
         HandleValue(Arg->IgnoreParenImpCasts());
     }
 
     void VisitUnaryOperator(UnaryOperator *E) {
       // For POD record types, addresses of its own members are well-defined.
       if (E->getOpcode() == UO_AddrOf && isRecordType &&
           isa<MemberExpr>(E->getSubExpr()->IgnoreParens())) {
         if (!isPODType)
           HandleValue(E->getSubExpr());
         return;
       }
 
       if (E->isIncrementDecrementOp()) {
         HandleValue(E->getSubExpr());
         return;
       }
 
       Inherited::VisitUnaryOperator(E);
     }
 
     void VisitObjCMessageExpr(ObjCMessageExpr *E) {}
 
     void VisitCXXConstructExpr(CXXConstructExpr *E) {
       if (E->getConstructor()->isCopyConstructor()) {
         Expr *ArgExpr = E->getArg(0);
         if (InitListExpr *ILE = dyn_cast<InitListExpr>(ArgExpr))
           if (ILE->getNumInits() == 1)
             ArgExpr = ILE->getInit(0);
         if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(ArgExpr))
           if (ICE->getCastKind() == CK_NoOp)
             ArgExpr = ICE->getSubExpr();
         HandleValue(ArgExpr);
         return;
       }
       Inherited::VisitCXXConstructExpr(E);
     }
 
     void VisitCallExpr(CallExpr *E) {
       // Treat std::move as a use.
       if (E->isCallToStdMove()) {
         HandleValue(E->getArg(0));
         return;
       }
 
       Inherited::VisitCallExpr(E);
     }
 
     void VisitBinaryOperator(BinaryOperator *E) {
       if (E->isCompoundAssignmentOp()) {
         HandleValue(E->getLHS());
         Visit(E->getRHS());
         return;
       }
 
       Inherited::VisitBinaryOperator(E);
     }
 
     // A custom visitor for BinaryConditionalOperator is needed because the
     // regular visitor would check the condition and true expression separately
     // but both point to the same place giving duplicate diagnostics.
     void VisitBinaryConditionalOperator(BinaryConditionalOperator *E) {
       Visit(E->getCond());
       Visit(E->getFalseExpr());
     }
 
     void HandleDeclRefExpr(DeclRefExpr *DRE) {
       Decl* ReferenceDecl = DRE->getDecl();
       if (OrigDecl != ReferenceDecl) return;
       unsigned diag;
       if (isReferenceType) {
         diag = diag::warn_uninit_self_reference_in_reference_init;
       } else if (cast<VarDecl>(OrigDecl)->isStaticLocal()) {
         diag = diag::warn_static_self_reference_in_init;
       } else if (isa<TranslationUnitDecl>(OrigDecl->getDeclContext()) ||
                  isa<NamespaceDecl>(OrigDecl->getDeclContext()) ||
                  DRE->getDecl()->getType()->isRecordType()) {
         diag = diag::warn_uninit_self_reference_in_init;
       } else {
         // Local variables will be handled by the CFG analysis.
         return;
       }
 
       S.DiagRuntimeBehavior(DRE->getBeginLoc(), DRE,
                             S.PDiag(diag)
                                 << DRE->getDecl() << OrigDecl->getLocation()
                                 << DRE->getSourceRange());
     }
   };
 
   /// CheckSelfReference - Warns if OrigDecl is used in expression E.
   static void CheckSelfReference(Sema &S, Decl* OrigDecl, Expr *E,
                                  bool DirectInit) {
     // Parameters arguments are occassionially constructed with itself,
     // for instance, in recursive functions.  Skip them.
     if (isa<ParmVarDecl>(OrigDecl))
       return;
 
     E = E->IgnoreParens();
 
     // Skip checking T a = a where T is not a record or reference type.
     // Doing so is a way to silence uninitialized warnings.
     if (!DirectInit && !cast<VarDecl>(OrigDecl)->getType()->isRecordType())
       if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E))
         if (ICE->getCastKind() == CK_LValueToRValue)
           if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(ICE->getSubExpr()))
             if (DRE->getDecl() == OrigDecl)
               return;
 
     SelfReferenceChecker(S, OrigDecl).CheckExpr(E);
   }
 } // end anonymous namespace
 
 namespace {
   // Simple wrapper to add the name of a variable or (if no variable is
   // available) a DeclarationName into a diagnostic.
   struct VarDeclOrName {
     VarDecl *VDecl;
     DeclarationName Name;
 
     friend const Sema::SemaDiagnosticBuilder &
     operator<<(const Sema::SemaDiagnosticBuilder &Diag, VarDeclOrName VN) {
       return VN.VDecl ? Diag << VN.VDecl : Diag << VN.Name;
     }
   };
 } // end anonymous namespace
 
 QualType Sema::deduceVarTypeFromInitializer(VarDecl *VDecl,
                                             DeclarationName Name, QualType Type,
                                             TypeSourceInfo *TSI,
                                             SourceRange Range, bool DirectInit,
                                             Expr *Init) {
   bool IsInitCapture = !VDecl;
   assert((!VDecl || !VDecl->isInitCapture()) &&
          "init captures are expected to be deduced prior to initialization");
 
   VarDeclOrName VN{VDecl, Name};
 
   DeducedType *Deduced = Type->getContainedDeducedType();
   assert(Deduced && "deduceVarTypeFromInitializer for non-deduced type");
 
   // C++11 [dcl.spec.auto]p3
   if (!Init) {
     assert(VDecl && "no init for init capture deduction?");
 
     // Except for class argument deduction, and then for an initializing
     // declaration only, i.e. no static at class scope or extern.
     if (!isa<DeducedTemplateSpecializationType>(Deduced) ||
         VDecl->hasExternalStorage() ||
         VDecl->isStaticDataMember()) {
       Diag(VDecl->getLocation(), diag::err_auto_var_requires_init)
         << VDecl->getDeclName() << Type;
       return QualType();
     }
   }
 
   ArrayRef<Expr*> DeduceInits;
   if (Init)
     DeduceInits = Init;
 
   auto *PL = dyn_cast_if_present<ParenListExpr>(Init);
   if (DirectInit && PL)
     DeduceInits = PL->exprs();
 
   if (isa<DeducedTemplateSpecializationType>(Deduced)) {
     assert(VDecl && "non-auto type for init capture deduction?");
     InitializedEntity Entity = InitializedEntity::InitializeVariable(VDecl);
     InitializationKind Kind = InitializationKind::CreateForInit(
         VDecl->getLocation(), DirectInit, Init);
     // FIXME: Initialization should not be taking a mutable list of inits.
     SmallVector<Expr*, 8> InitsCopy(DeduceInits.begin(), DeduceInits.end());
     return DeduceTemplateSpecializationFromInitializer(TSI, Entity, Kind,
                                                        InitsCopy, PL);
   }
 
   if (DirectInit) {
     if (auto *IL = dyn_cast<InitListExpr>(Init))
       DeduceInits = IL->inits();
   }
 
   // Deduction only works if we have exactly one source expression.
   if (DeduceInits.empty()) {
     // It isn't possible to write this directly, but it is possible to
     // end up in this situation with "auto x(some_pack...);"
     Diag(Init->getBeginLoc(), IsInitCapture
                                   ? diag::err_init_capture_no_expression
                                   : diag::err_auto_var_init_no_expression)
         << VN << Type << Range;
     return QualType();
   }
 
   if (DeduceInits.size() > 1) {
     Diag(DeduceInits[1]->getBeginLoc(),
          IsInitCapture ? diag::err_init_capture_multiple_expressions
                        : diag::err_auto_var_init_multiple_expressions)
         << VN << Type << Range;
     return QualType();
   }
 
   Expr *DeduceInit = DeduceInits[0];
   if (DirectInit && isa<InitListExpr>(DeduceInit)) {
     Diag(Init->getBeginLoc(), IsInitCapture
                                   ? diag::err_init_capture_paren_braces
                                   : diag::err_auto_var_init_paren_braces)
         << isa<InitListExpr>(Init) << VN << Type << Range;
     return QualType();
   }
 
   // Expressions default to 'id' when we're in a debugger.
   bool DefaultedAnyToId = false;
   if (getLangOpts().DebuggerCastResultToId &&
       Init->getType() == Context.UnknownAnyTy && !IsInitCapture) {
     ExprResult Result = forceUnknownAnyToType(Init, Context.getObjCIdType());
     if (Result.isInvalid()) {
       return QualType();
     }
     Init = Result.get();
     DefaultedAnyToId = true;
   }
 
   // C++ [dcl.decomp]p1:
   //   If the assignment-expression [...] has array type A and no ref-qualifier
   //   is present, e has type cv A
   if (VDecl && isa<DecompositionDecl>(VDecl) &&
       Context.hasSameUnqualifiedType(Type, Context.getAutoDeductType()) &&
       DeduceInit->getType()->isConstantArrayType())
     return Context.getQualifiedType(DeduceInit->getType(),
                                     Type.getQualifiers());
 
   QualType DeducedType;
   TemplateDeductionInfo Info(DeduceInit->getExprLoc());
   TemplateDeductionResult Result =
       DeduceAutoType(TSI->getTypeLoc(), DeduceInit, DeducedType, Info);
   if (Result != TDK_Success && Result != TDK_AlreadyDiagnosed) {
     if (!IsInitCapture)
       DiagnoseAutoDeductionFailure(VDecl, DeduceInit);
     else if (isa<InitListExpr>(Init))
       Diag(Range.getBegin(),
            diag::err_init_capture_deduction_failure_from_init_list)
           << VN
           << (DeduceInit->getType().isNull() ? TSI->getType()
                                              : DeduceInit->getType())
           << DeduceInit->getSourceRange();
     else
       Diag(Range.getBegin(), diag::err_init_capture_deduction_failure)
           << VN << TSI->getType()
           << (DeduceInit->getType().isNull() ? TSI->getType()
                                              : DeduceInit->getType())
           << DeduceInit->getSourceRange();
   }
 
   // Warn if we deduced 'id'. 'auto' usually implies type-safety, but using
   // 'id' instead of a specific object type prevents most of our usual
   // checks.
   // We only want to warn outside of template instantiations, though:
   // inside a template, the 'id' could have come from a parameter.
   if (!inTemplateInstantiation() && !DefaultedAnyToId && !IsInitCapture &&
       !DeducedType.isNull() && DeducedType->isObjCIdType()) {
     SourceLocation Loc = TSI->getTypeLoc().getBeginLoc();
     Diag(Loc, diag::warn_auto_var_is_id) << VN << Range;
   }
 
   return DeducedType;
 }
 
 bool Sema::DeduceVariableDeclarationType(VarDecl *VDecl, bool DirectInit,
                                          Expr *Init) {
   assert(!Init || !Init->containsErrors());
   QualType DeducedType = deduceVarTypeFromInitializer(
       VDecl, VDecl->getDeclName(), VDecl->getType(), VDecl->getTypeSourceInfo(),
       VDecl->getSourceRange(), DirectInit, Init);
   if (DeducedType.isNull()) {
     VDecl->setInvalidDecl();
     return true;
   }
 
   VDecl->setType(DeducedType);
   assert(VDecl->isLinkageValid());
 
   // In ARC, infer lifetime.
   if (getLangOpts().ObjCAutoRefCount && inferObjCARCLifetime(VDecl))
     VDecl->setInvalidDecl();
 
   if (getLangOpts().OpenCL)
     deduceOpenCLAddressSpace(VDecl);
 
   // If this is a redeclaration, check that the type we just deduced matches
   // the previously declared type.
   if (VarDecl *Old = VDecl->getPreviousDecl()) {
     // We never need to merge the type, because we cannot form an incomplete
     // array of auto, nor deduce such a type.
     MergeVarDeclTypes(VDecl, Old, /*MergeTypeWithPrevious*/ false);
   }
 
   // Check the deduced type is valid for a variable declaration.
   CheckVariableDeclarationType(VDecl);
   return VDecl->isInvalidDecl();
 }
 
 void Sema::checkNonTrivialCUnionInInitializer(const Expr *Init,
                                               SourceLocation Loc) {
   if (auto *EWC = dyn_cast<ExprWithCleanups>(Init))
     Init = EWC->getSubExpr();
 
   if (auto *CE = dyn_cast<ConstantExpr>(Init))
     Init = CE->getSubExpr();
 
   QualType InitType = Init->getType();
   assert((InitType.hasNonTrivialToPrimitiveDefaultInitializeCUnion() ||
           InitType.hasNonTrivialToPrimitiveCopyCUnion()) &&
          "shouldn't be called if type doesn't have a non-trivial C struct");
   if (auto *ILE = dyn_cast<InitListExpr>(Init)) {
     for (auto *I : ILE->inits()) {
       if (!I->getType().hasNonTrivialToPrimitiveDefaultInitializeCUnion() &&
           !I->getType().hasNonTrivialToPrimitiveCopyCUnion())
         continue;
       SourceLocation SL = I->getExprLoc();
       checkNonTrivialCUnionInInitializer(I, SL.isValid() ? SL : Loc);
     }
     return;
   }
 
   if (isa<ImplicitValueInitExpr>(Init)) {
     if (InitType.hasNonTrivialToPrimitiveDefaultInitializeCUnion())
       checkNonTrivialCUnion(InitType, Loc, NTCUC_DefaultInitializedObject,
                             NTCUK_Init);
   } else {
     // Assume all other explicit initializers involving copying some existing
     // object.
     // TODO: ignore any explicit initializers where we can guarantee
     // copy-elision.
     if (InitType.hasNonTrivialToPrimitiveCopyCUnion())
       checkNonTrivialCUnion(InitType, Loc, NTCUC_CopyInit, NTCUK_Copy);
   }
 }
 
 namespace {
 
 bool shouldIgnoreForRecordTriviality(const FieldDecl *FD) {
   // Ignore unavailable fields. A field can be marked as unavailable explicitly
   // in the source code or implicitly by the compiler if it is in a union
   // defined in a system header and has non-trivial ObjC ownership
   // qualifications. We don't want those fields to participate in determining
   // whether the containing union is non-trivial.
   return FD->hasAttr<UnavailableAttr>();
 }
 
 struct DiagNonTrivalCUnionDefaultInitializeVisitor
     : DefaultInitializedTypeVisitor<DiagNonTrivalCUnionDefaultInitializeVisitor,
                                     void> {
   using Super =
       DefaultInitializedTypeVisitor<DiagNonTrivalCUnionDefaultInitializeVisitor,
                                     void>;
 
   DiagNonTrivalCUnionDefaultInitializeVisitor(
       QualType OrigTy, SourceLocation OrigLoc,
       Sema::NonTrivialCUnionContext UseContext, Sema &S)
       : OrigTy(OrigTy), OrigLoc(OrigLoc), UseContext(UseContext), S(S) {}
 
   void visitWithKind(QualType::PrimitiveDefaultInitializeKind PDIK, QualType QT,
                      const FieldDecl *FD, bool InNonTrivialUnion) {
     if (const auto *AT = S.Context.getAsArrayType(QT))
       return this->asDerived().visit(S.Context.getBaseElementType(AT), FD,
                                      InNonTrivialUnion);
     return Super::visitWithKind(PDIK, QT, FD, InNonTrivialUnion);
   }
 
   void visitARCStrong(QualType QT, const FieldDecl *FD,
                       bool InNonTrivialUnion) {
     if (InNonTrivialUnion)
       S.Diag(FD->getLocation(), diag::note_non_trivial_c_union)
           << 1 << 0 << QT << FD->getName();
   }
 
   void visitARCWeak(QualType QT, const FieldDecl *FD, bool InNonTrivialUnion) {
     if (InNonTrivialUnion)
       S.Diag(FD->getLocation(), diag::note_non_trivial_c_union)
           << 1 << 0 << QT << FD->getName();
   }
 
   void visitStruct(QualType QT, const FieldDecl *FD, bool InNonTrivialUnion) {
     const RecordDecl *RD = QT->castAs<RecordType>()->getDecl();
     if (RD->isUnion()) {
       if (OrigLoc.isValid()) {
         bool IsUnion = false;
         if (auto *OrigRD = OrigTy->getAsRecordDecl())
           IsUnion = OrigRD->isUnion();
         S.Diag(OrigLoc, diag::err_non_trivial_c_union_in_invalid_context)
             << 0 << OrigTy << IsUnion << UseContext;
         // Reset OrigLoc so that this diagnostic is emitted only once.
         OrigLoc = SourceLocation();
       }
       InNonTrivialUnion = true;
     }
 
     if (InNonTrivialUnion)
       S.Diag(RD->getLocation(), diag::note_non_trivial_c_union)
           << 0 << 0 << QT.getUnqualifiedType() << "";
 
     for (const FieldDecl *FD : RD->fields())
       if (!shouldIgnoreForRecordTriviality(FD))
         asDerived().visit(FD->getType(), FD, InNonTrivialUnion);
   }
 
   void visitTrivial(QualType QT, const FieldDecl *FD, bool InNonTrivialUnion) {}
 
   // The non-trivial C union type or the struct/union type that contains a
   // non-trivial C union.
   QualType OrigTy;
   SourceLocation OrigLoc;
   Sema::NonTrivialCUnionContext UseContext;
   Sema &S;
 };
 
 struct DiagNonTrivalCUnionDestructedTypeVisitor
     : DestructedTypeVisitor<DiagNonTrivalCUnionDestructedTypeVisitor, void> {
   using Super =
       DestructedTypeVisitor<DiagNonTrivalCUnionDestructedTypeVisitor, void>;
 
   DiagNonTrivalCUnionDestructedTypeVisitor(
       QualType OrigTy, SourceLocation OrigLoc,
       Sema::NonTrivialCUnionContext UseContext, Sema &S)
       : OrigTy(OrigTy), OrigLoc(OrigLoc), UseContext(UseContext), S(S) {}
 
   void visitWithKind(QualType::DestructionKind DK, QualType QT,
                      const FieldDecl *FD, bool InNonTrivialUnion) {
     if (const auto *AT = S.Context.getAsArrayType(QT))
       return this->asDerived().visit(S.Context.getBaseElementType(AT), FD,
                                      InNonTrivialUnion);
     return Super::visitWithKind(DK, QT, FD, InNonTrivialUnion);
   }
 
   void visitARCStrong(QualType QT, const FieldDecl *FD,
                       bool InNonTrivialUnion) {
     if (InNonTrivialUnion)
       S.Diag(FD->getLocation(), diag::note_non_trivial_c_union)
           << 1 << 1 << QT << FD->getName();
   }
 
   void visitARCWeak(QualType QT, const FieldDecl *FD, bool InNonTrivialUnion) {
     if (InNonTrivialUnion)
       S.Diag(FD->getLocation(), diag::note_non_trivial_c_union)
           << 1 << 1 << QT << FD->getName();
   }
 
   void visitStruct(QualType QT, const FieldDecl *FD, bool InNonTrivialUnion) {
     const RecordDecl *RD = QT->castAs<RecordType>()->getDecl();
     if (RD->isUnion()) {
       if (OrigLoc.isValid()) {
         bool IsUnion = false;
         if (auto *OrigRD = OrigTy->getAsRecordDecl())
           IsUnion = OrigRD->isUnion();
         S.Diag(OrigLoc, diag::err_non_trivial_c_union_in_invalid_context)
             << 1 << OrigTy << IsUnion << UseContext;
         // Reset OrigLoc so that this diagnostic is emitted only once.
         OrigLoc = SourceLocation();
       }
       InNonTrivialUnion = true;
     }
 
     if (InNonTrivialUnion)
       S.Diag(RD->getLocation(), diag::note_non_trivial_c_union)
           << 0 << 1 << QT.getUnqualifiedType() << "";
 
     for (const FieldDecl *FD : RD->fields())
       if (!shouldIgnoreForRecordTriviality(FD))
         asDerived().visit(FD->getType(), FD, InNonTrivialUnion);
   }
 
   void visitTrivial(QualType QT, const FieldDecl *FD, bool InNonTrivialUnion) {}
   void visitCXXDestructor(QualType QT, const FieldDecl *FD,
                           bool InNonTrivialUnion) {}
 
   // The non-trivial C union type or the struct/union type that contains a
   // non-trivial C union.
   QualType OrigTy;
   SourceLocation OrigLoc;
   Sema::NonTrivialCUnionContext UseContext;
   Sema &S;
 };
 
 struct DiagNonTrivalCUnionCopyVisitor
     : CopiedTypeVisitor<DiagNonTrivalCUnionCopyVisitor, false, void> {
   using Super = CopiedTypeVisitor<DiagNonTrivalCUnionCopyVisitor, false, void>;
 
   DiagNonTrivalCUnionCopyVisitor(QualType OrigTy, SourceLocation OrigLoc,
                                  Sema::NonTrivialCUnionContext UseContext,
                                  Sema &S)
       : OrigTy(OrigTy), OrigLoc(OrigLoc), UseContext(UseContext), S(S) {}
 
   void visitWithKind(QualType::PrimitiveCopyKind PCK, QualType QT,
                      const FieldDecl *FD, bool InNonTrivialUnion) {
     if (const auto *AT = S.Context.getAsArrayType(QT))
       return this->asDerived().visit(S.Context.getBaseElementType(AT), FD,
                                      InNonTrivialUnion);
     return Super::visitWithKind(PCK, QT, FD, InNonTrivialUnion);
   }
 
   void visitARCStrong(QualType QT, const FieldDecl *FD,
                       bool InNonTrivialUnion) {
     if (InNonTrivialUnion)
       S.Diag(FD->getLocation(), diag::note_non_trivial_c_union)
           << 1 << 2 << QT << FD->getName();
   }
 
   void visitARCWeak(QualType QT, const FieldDecl *FD, bool InNonTrivialUnion) {
     if (InNonTrivialUnion)
       S.Diag(FD->getLocation(), diag::note_non_trivial_c_union)
           << 1 << 2 << QT << FD->getName();
   }
 
   void visitStruct(QualType QT, const FieldDecl *FD, bool InNonTrivialUnion) {
     const RecordDecl *RD = QT->castAs<RecordType>()->getDecl();
     if (RD->isUnion()) {
       if (OrigLoc.isValid()) {
         bool IsUnion = false;
         if (auto *OrigRD = OrigTy->getAsRecordDecl())
           IsUnion = OrigRD->isUnion();
         S.Diag(OrigLoc, diag::err_non_trivial_c_union_in_invalid_context)
             << 2 << OrigTy << IsUnion << UseContext;
         // Reset OrigLoc so that this diagnostic is emitted only once.
         OrigLoc = SourceLocation();
       }
       InNonTrivialUnion = true;
     }
 
     if (InNonTrivialUnion)
       S.Diag(RD->getLocation(), diag::note_non_trivial_c_union)
           << 0 << 2 << QT.getUnqualifiedType() << "";
 
     for (const FieldDecl *FD : RD->fields())
       if (!shouldIgnoreForRecordTriviality(FD))
         asDerived().visit(FD->getType(), FD, InNonTrivialUnion);
   }
 
   void preVisit(QualType::PrimitiveCopyKind PCK, QualType QT,
                 const FieldDecl *FD, bool InNonTrivialUnion) {}
   void visitTrivial(QualType QT, const FieldDecl *FD, bool InNonTrivialUnion) {}
   void visitVolatileTrivial(QualType QT, const FieldDecl *FD,
                             bool InNonTrivialUnion) {}
 
   // The non-trivial C union type or the struct/union type that contains a
   // non-trivial C union.
   QualType OrigTy;
   SourceLocation OrigLoc;
   Sema::NonTrivialCUnionContext UseContext;
   Sema &S;
 };
 
 } // namespace
 
 void Sema::checkNonTrivialCUnion(QualType QT, SourceLocation Loc,
                                  NonTrivialCUnionContext UseContext,
                                  unsigned NonTrivialKind) {
   assert((QT.hasNonTrivialToPrimitiveDefaultInitializeCUnion() ||
           QT.hasNonTrivialToPrimitiveDestructCUnion() ||
           QT.hasNonTrivialToPrimitiveCopyCUnion()) &&
          "shouldn't be called if type doesn't have a non-trivial C union");
 
   if ((NonTrivialKind & NTCUK_Init) &&
       QT.hasNonTrivialToPrimitiveDefaultInitializeCUnion())
     DiagNonTrivalCUnionDefaultInitializeVisitor(QT, Loc, UseContext, *this)
         .visit(QT, nullptr, false);
   if ((NonTrivialKind & NTCUK_Destruct) &&
       QT.hasNonTrivialToPrimitiveDestructCUnion())
     DiagNonTrivalCUnionDestructedTypeVisitor(QT, Loc, UseContext, *this)
         .visit(QT, nullptr, false);
   if ((NonTrivialKind & NTCUK_Copy) && QT.hasNonTrivialToPrimitiveCopyCUnion())
     DiagNonTrivalCUnionCopyVisitor(QT, Loc, UseContext, *this)
         .visit(QT, nullptr, false);
 }
 
 /// AddInitializerToDecl - Adds the initializer Init to the
 /// declaration dcl. If DirectInit is true, this is C++ direct
 /// initialization rather than copy initialization.
 void Sema::AddInitializerToDecl(Decl *RealDecl, Expr *Init, bool DirectInit) {
   // If there is no declaration, there was an error parsing it.  Just ignore
   // the initializer.
   if (!RealDecl || RealDecl->isInvalidDecl()) {
     CorrectDelayedTyposInExpr(Init, dyn_cast_or_null<VarDecl>(RealDecl));
     return;
   }
 
   if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(RealDecl)) {
     // Pure-specifiers are handled in ActOnPureSpecifier.
     Diag(Method->getLocation(), diag::err_member_function_initialization)
       << Method->getDeclName() << Init->getSourceRange();
     Method->setInvalidDecl();
     return;
   }
 
   VarDecl *VDecl = dyn_cast<VarDecl>(RealDecl);
   if (!VDecl) {
     assert(!isa<FieldDecl>(RealDecl) && "field init shouldn't get here");
     Diag(RealDecl->getLocation(), diag::err_illegal_initializer);
     RealDecl->setInvalidDecl();
     return;
   }
 
   // WebAssembly tables can't be used to initialise a variable.
   if (Init && !Init->getType().isNull() &&
       Init->getType()->isWebAssemblyTableType()) {
     Diag(Init->getExprLoc(), diag::err_wasm_table_art) << 0;
     VDecl->setInvalidDecl();
     return;
   }
 
   // C++11 [decl.spec.auto]p6. Deduce the type which 'auto' stands in for.
   if (VDecl->getType()->isUndeducedType()) {
     // Attempt typo correction early so that the type of the init expression can
     // be deduced based on the chosen correction if the original init contains a
     // TypoExpr.
     ExprResult Res = CorrectDelayedTyposInExpr(Init, VDecl);
     if (!Res.isUsable()) {
       // There are unresolved typos in Init, just drop them.
       // FIXME: improve the recovery strategy to preserve the Init.
       RealDecl->setInvalidDecl();
       return;
     }
     if (Res.get()->containsErrors()) {
       // Invalidate the decl as we don't know the type for recovery-expr yet.
       RealDecl->setInvalidDecl();
       VDecl->setInit(Res.get());
       return;
     }
     Init = Res.get();
 
     if (DeduceVariableDeclarationType(VDecl, DirectInit, Init))
       return;
   }
 
   // dllimport cannot be used on variable definitions.
   if (VDecl->hasAttr<DLLImportAttr>() && !VDecl->isStaticDataMember()) {
     Diag(VDecl->getLocation(), diag::err_attribute_dllimport_data_definition);
     VDecl->setInvalidDecl();
     return;
   }
 
   // C99 6.7.8p5. If the declaration of an identifier has block scope, and
   // the identifier has external or internal linkage, the declaration shall
   // have no initializer for the identifier.
   // C++14 [dcl.init]p5 is the same restriction for C++.
   if (VDecl->isLocalVarDecl() && VDecl->hasExternalStorage()) {
     Diag(VDecl->getLocation(), diag::err_block_extern_cant_init);
     VDecl->setInvalidDecl();
     return;
   }
 
   if (!VDecl->getType()->isDependentType()) {
     // A definition must end up with a complete type, which means it must be
     // complete with the restriction that an array type might be completed by
     // the initializer; note that later code assumes this restriction.
     QualType BaseDeclType = VDecl->getType();
     if (const ArrayType *Array = Context.getAsIncompleteArrayType(BaseDeclType))
       BaseDeclType = Array->getElementType();
     if (RequireCompleteType(VDecl->getLocation(), BaseDeclType,
                             diag::err_typecheck_decl_incomplete_type)) {
       RealDecl->setInvalidDecl();
       return;
     }
 
     // The variable can not have an abstract class type.
     if (RequireNonAbstractType(VDecl->getLocation(), VDecl->getType(),
                                diag::err_abstract_type_in_decl,
                                AbstractVariableType))
       VDecl->setInvalidDecl();
   }
 
   // C++ [module.import/6] external definitions are not permitted in header
   // units.
   if (getLangOpts().CPlusPlusModules && currentModuleIsHeaderUnit() &&
       !VDecl->isInvalidDecl() && VDecl->isThisDeclarationADefinition() &&
       VDecl->getFormalLinkage() == Linkage::ExternalLinkage &&
       !VDecl->isInline() && !VDecl->isTemplated() &&
       !isa<VarTemplateSpecializationDecl>(VDecl)) {
     Diag(VDecl->getLocation(), diag::err_extern_def_in_header_unit);
     VDecl->setInvalidDecl();
   }
 
   // If adding the initializer will turn this declaration into a definition,
   // and we already have a definition for this variable, diagnose or otherwise
   // handle the situation.
   if (VarDecl *Def = VDecl->getDefinition())
     if (Def != VDecl &&
         (!VDecl->isStaticDataMember() || VDecl->isOutOfLine()) &&
         !VDecl->isThisDeclarationADemotedDefinition() &&
         checkVarDeclRedefinition(Def, VDecl))
       return;
 
   if (getLangOpts().CPlusPlus) {
     // C++ [class.static.data]p4
     //   If a static data member is of const integral or const
     //   enumeration type, its declaration in the class definition can
     //   specify a constant-initializer which shall be an integral
     //   constant expression (5.19). In that case, the member can appear
     //   in integral constant expressions. The member shall still be
     //   defined in a namespace scope if it is used in the program and the
     //   namespace scope definition shall not contain an initializer.
     //
     // We already performed a redefinition check above, but for static
     // data members we also need to check whether there was an in-class
     // declaration with an initializer.
     if (VDecl->isStaticDataMember() && VDecl->getCanonicalDecl()->hasInit()) {
       Diag(Init->getExprLoc(), diag::err_static_data_member_reinitialization)
           << VDecl->getDeclName();
       Diag(VDecl->getCanonicalDecl()->getInit()->getExprLoc(),
            diag::note_previous_initializer)
           << 0;
       return;
     }
 
     if (VDecl->hasLocalStorage())
       setFunctionHasBranchProtectedScope();
 
     if (DiagnoseUnexpandedParameterPack(Init, UPPC_Initializer)) {
       VDecl->setInvalidDecl();
       return;
     }
   }
 
   // OpenCL 1.1 6.5.2: "Variables allocated in the __local address space inside
   // a kernel function cannot be initialized."
   if (VDecl->getType().getAddressSpace() == LangAS::opencl_local) {
     Diag(VDecl->getLocation(), diag::err_local_cant_init);
     VDecl->setInvalidDecl();
     return;
   }
 
   // The LoaderUninitialized attribute acts as a definition (of undef).
   if (VDecl->hasAttr<LoaderUninitializedAttr>()) {
     Diag(VDecl->getLocation(), diag::err_loader_uninitialized_cant_init);
     VDecl->setInvalidDecl();
     return;
   }
 
   // Get the decls type and save a reference for later, since
   // CheckInitializerTypes may change it.
   QualType DclT = VDecl->getType(), SavT = DclT;
 
   // Expressions default to 'id' when we're in a debugger
   // and we are assigning it to a variable of Objective-C pointer type.
   if (getLangOpts().DebuggerCastResultToId && DclT->isObjCObjectPointerType() &&
       Init->getType() == Context.UnknownAnyTy) {
     ExprResult Result = forceUnknownAnyToType(Init, Context.getObjCIdType());
     if (Result.isInvalid()) {
       VDecl->setInvalidDecl();
       return;
     }
     Init = Result.get();
   }
 
   // Perform the initialization.
   ParenListExpr *CXXDirectInit = dyn_cast<ParenListExpr>(Init);
   bool IsParenListInit = false;
   if (!VDecl->isInvalidDecl()) {
     InitializedEntity Entity = InitializedEntity::InitializeVariable(VDecl);
     InitializationKind Kind = InitializationKind::CreateForInit(
         VDecl->getLocation(), DirectInit, Init);
 
     MultiExprArg Args = Init;
     if (CXXDirectInit)
       Args = MultiExprArg(CXXDirectInit->getExprs(),
                           CXXDirectInit->getNumExprs());
 
     // Try to correct any TypoExprs in the initialization arguments.
     for (size_t Idx = 0; Idx < Args.size(); ++Idx) {
       ExprResult Res = CorrectDelayedTyposInExpr(
           Args[Idx], VDecl, /*RecoverUncorrectedTypos=*/true,
           [this, Entity, Kind](Expr *E) {
             InitializationSequence Init(*this, Entity, Kind, MultiExprArg(E));
             return Init.Failed() ? ExprError() : E;
           });
       if (Res.isInvalid()) {
         VDecl->setInvalidDecl();
       } else if (Res.get() != Args[Idx]) {
         Args[Idx] = Res.get();
       }
     }
     if (VDecl->isInvalidDecl())
       return;
 
     InitializationSequence InitSeq(*this, Entity, Kind, Args,
                                    /*TopLevelOfInitList=*/false,
                                    /*TreatUnavailableAsInvalid=*/false);
     ExprResult Result = InitSeq.Perform(*this, Entity, Kind, Args, &DclT);
     if (Result.isInvalid()) {
       // If the provided initializer fails to initialize the var decl,
       // we attach a recovery expr for better recovery.
       auto RecoveryExpr =
           CreateRecoveryExpr(Init->getBeginLoc(), Init->getEndLoc(), Args);
       if (RecoveryExpr.get())
         VDecl->setInit(RecoveryExpr.get());
       return;
     }
 
     Init = Result.getAs<Expr>();
     IsParenListInit = !InitSeq.steps().empty() &&
                       InitSeq.step_begin()->Kind ==
                           InitializationSequence::SK_ParenthesizedListInit;
   }
 
   // Check for self-references within variable initializers.
   // Variables declared within a function/method body (except for references)
   // are handled by a dataflow analysis.
   // This is undefined behavior in C++, but valid in C.
   if (getLangOpts().CPlusPlus)
     if (!VDecl->hasLocalStorage() || VDecl->getType()->isRecordType() ||
         VDecl->getType()->isReferenceType())
       CheckSelfReference(*this, RealDecl, Init, DirectInit);
 
   // If the type changed, it means we had an incomplete type that was
   // completed by the initializer. For example:
   //   int ary[] = { 1, 3, 5 };
   // "ary" transitions from an IncompleteArrayType to a ConstantArrayType.
   if (!VDecl->isInvalidDecl() && (DclT != SavT))
     VDecl->setType(DclT);
 
   if (!VDecl->isInvalidDecl()) {
     checkUnsafeAssigns(VDecl->getLocation(), VDecl->getType(), Init);
 
     if (VDecl->hasAttr<BlocksAttr>())
       checkRetainCycles(VDecl, Init);
 
     // It is safe to assign a weak reference into a strong variable.
     // Although this code can still have problems:
     //   id x = self.weakProp;
     //   id y = self.weakProp;
     // we do not warn to warn spuriously when 'x' and 'y' are on separate
     // paths through the function. This should be revisited if
     // -Wrepeated-use-of-weak is made flow-sensitive.
     if (FunctionScopeInfo *FSI = getCurFunction())
       if ((VDecl->getType().getObjCLifetime() == Qualifiers::OCL_Strong ||
            VDecl->getType().isNonWeakInMRRWithObjCWeak(Context)) &&
           !Diags.isIgnored(diag::warn_arc_repeated_use_of_weak,
                            Init->getBeginLoc()))
         FSI->markSafeWeakUse(Init);
   }
 
   // The initialization is usually a full-expression.
   //
   // FIXME: If this is a braced initialization of an aggregate, it is not
   // an expression, and each individual field initializer is a separate
   // full-expression. For instance, in:
   //
   //   struct Temp { ~Temp(); };
   //   struct S { S(Temp); };
   //   struct T { S a, b; } t = { Temp(), Temp() }
   //
   // we should destroy the first Temp before constructing the second.
   ExprResult Result =
       ActOnFinishFullExpr(Init, VDecl->getLocation(),
                           /*DiscardedValue*/ false, VDecl->isConstexpr());
   if (Result.isInvalid()) {
     VDecl->setInvalidDecl();
     return;
   }
   Init = Result.get();
 
   // Attach the initializer to the decl.
   VDecl->setInit(Init);
 
   if (VDecl->isLocalVarDecl()) {
     // Don't check the initializer if the declaration is malformed.
     if (VDecl->isInvalidDecl()) {
       // do nothing
 
     // OpenCL v1.2 s6.5.3: __constant locals must be constant-initialized.
     // This is true even in C++ for OpenCL.
     } else if (VDecl->getType().getAddressSpace() == LangAS::opencl_constant) {
       CheckForConstantInitializer(Init, DclT);
 
     // Otherwise, C++ does not restrict the initializer.
     } else if (getLangOpts().CPlusPlus) {
       // do nothing
 
     // C99 6.7.8p4: All the expressions in an initializer for an object that has
     // static storage duration shall be constant expressions or string literals.
     } else if (VDecl->getStorageClass() == SC_Static) {
       CheckForConstantInitializer(Init, DclT);
 
     // C89 is stricter than C99 for aggregate initializers.
     // C89 6.5.7p3: All the expressions [...] in an initializer list
     // for an object that has aggregate or union type shall be
     // constant expressions.
     } else if (!getLangOpts().C99 && VDecl->getType()->isAggregateType() &&
                isa<InitListExpr>(Init)) {
       const Expr *Culprit;
       if (!Init->isConstantInitializer(Context, false, &Culprit)) {
         Diag(Culprit->getExprLoc(),
              diag::ext_aggregate_init_not_constant)
           << Culprit->getSourceRange();
       }
     }
 
     if (auto *E = dyn_cast<ExprWithCleanups>(Init))
       if (auto *BE = dyn_cast<BlockExpr>(E->getSubExpr()->IgnoreParens()))
         if (VDecl->hasLocalStorage())
           BE->getBlockDecl()->setCanAvoidCopyToHeap();
   } else if (VDecl->isStaticDataMember() && !VDecl->isInline() &&
              VDecl->getLexicalDeclContext()->isRecord()) {
     // This is an in-class initialization for a static data member, e.g.,
     //
     // struct S {
     //   static const int value = 17;
     // };
 
     // C++ [class.mem]p4:
     //   A member-declarator can contain a constant-initializer only
     //   if it declares a static member (9.4) of const integral or
     //   const enumeration type, see 9.4.2.
     //
     // C++11 [class.static.data]p3:
     //   If a non-volatile non-inline const static data member is of integral
     //   or enumeration type, its declaration in the class definition can
     //   specify a brace-or-equal-initializer in which every initializer-clause
     //   that is an assignment-expression is a constant expression. A static
     //   data member of literal type can be declared in the class definition
     //   with the constexpr specifier; if so, its declaration shall specify a
     //   brace-or-equal-initializer in which every initializer-clause that is
     //   an assignment-expression is a constant expression.
 
     // Do nothing on dependent types.
     if (DclT->isDependentType()) {
 
     // Allow any 'static constexpr' members, whether or not they are of literal
     // type. We separately check that every constexpr variable is of literal
     // type.
     } else if (VDecl->isConstexpr()) {
 
     // Require constness.
     } else if (!DclT.isConstQualified()) {
       Diag(VDecl->getLocation(), diag::err_in_class_initializer_non_const)
         << Init->getSourceRange();
       VDecl->setInvalidDecl();
 
     // We allow integer constant expressions in all cases.
     } else if (DclT->isIntegralOrEnumerationType()) {
       // Check whether the expression is a constant expression.
       SourceLocation Loc;
       if (getLangOpts().CPlusPlus11 && DclT.isVolatileQualified())
         // In C++11, a non-constexpr const static data member with an
         // in-class initializer cannot be volatile.
         Diag(VDecl->getLocation(), diag::err_in_class_initializer_volatile);
       else if (Init->isValueDependent())
         ; // Nothing to check.
       else if (Init->isIntegerConstantExpr(Context, &Loc))
         ; // Ok, it's an ICE!
       else if (Init->getType()->isScopedEnumeralType() &&
                Init->isCXX11ConstantExpr(Context))
         ; // Ok, it is a scoped-enum constant expression.
       else if (Init->isEvaluatable(Context)) {
         // If we can constant fold the initializer through heroics, accept it,
         // but report this as a use of an extension for -pedantic.
         Diag(Loc, diag::ext_in_class_initializer_non_constant)
           << Init->getSourceRange();
       } else {
         // Otherwise, this is some crazy unknown case.  Report the issue at the
         // location provided by the isIntegerConstantExpr failed check.
         Diag(Loc, diag::err_in_class_initializer_non_constant)
           << Init->getSourceRange();
         VDecl->setInvalidDecl();
       }
 
     // We allow foldable floating-point constants as an extension.
     } else if (DclT->isFloatingType()) { // also permits complex, which is ok
       // In C++98, this is a GNU extension. In C++11, it is not, but we support
       // it anyway and provide a fixit to add the 'constexpr'.
       if (getLangOpts().CPlusPlus11) {
         Diag(VDecl->getLocation(),
              diag::ext_in_class_initializer_float_type_cxx11)
             << DclT << Init->getSourceRange();
         Diag(VDecl->getBeginLoc(),
              diag::note_in_class_initializer_float_type_cxx11)
             << FixItHint::CreateInsertion(VDecl->getBeginLoc(), "constexpr ");
       } else {
         Diag(VDecl->getLocation(), diag::ext_in_class_initializer_float_type)
           << DclT << Init->getSourceRange();
 
         if (!Init->isValueDependent() && !Init->isEvaluatable(Context)) {
           Diag(Init->getExprLoc(), diag::err_in_class_initializer_non_constant)
             << Init->getSourceRange();
           VDecl->setInvalidDecl();
         }
       }
 
     // Suggest adding 'constexpr' in C++11 for literal types.
     } else if (getLangOpts().CPlusPlus11 && DclT->isLiteralType(Context)) {
       Diag(VDecl->getLocation(), diag::err_in_class_initializer_literal_type)
           << DclT << Init->getSourceRange()
           << FixItHint::CreateInsertion(VDecl->getBeginLoc(), "constexpr ");
       VDecl->setConstexpr(true);
 
     } else {
       Diag(VDecl->getLocation(), diag::err_in_class_initializer_bad_type)
         << DclT << Init->getSourceRange();
       VDecl->setInvalidDecl();
     }
   } else if (VDecl->isFileVarDecl()) {
     // In C, extern is typically used to avoid tentative definitions when
     // declaring variables in headers, but adding an intializer makes it a
     // definition. This is somewhat confusing, so GCC and Clang both warn on it.
     // In C++, extern is often used to give implictly static const variables
     // external linkage, so don't warn in that case. If selectany is present,
     // this might be header code intended for C and C++ inclusion, so apply the
     // C++ rules.
     if (VDecl->getStorageClass() == SC_Extern &&
         ((!getLangOpts().CPlusPlus && !VDecl->hasAttr<SelectAnyAttr>()) ||
          !Context.getBaseElementType(VDecl->getType()).isConstQualified()) &&
         !(getLangOpts().CPlusPlus && VDecl->isExternC()) &&
         !isTemplateInstantiation(VDecl->getTemplateSpecializationKind()))
       Diag(VDecl->getLocation(), diag::warn_extern_init);
 
     // In Microsoft C++ mode, a const variable defined in namespace scope has
     // external linkage by default if the variable is declared with
     // __declspec(dllexport).
     if (Context.getTargetInfo().getCXXABI().isMicrosoft() &&
         getLangOpts().CPlusPlus && VDecl->getType().isConstQualified() &&
         VDecl->hasAttr<DLLExportAttr>() && VDecl->getDefinition())
       VDecl->setStorageClass(SC_Extern);
 
     // C99 6.7.8p4. All file scoped initializers need to be constant.
     if (!getLangOpts().CPlusPlus && !VDecl->isInvalidDecl())
       CheckForConstantInitializer(Init, DclT);
   }
 
   QualType InitType = Init->getType();
   if (!InitType.isNull() &&
       (InitType.hasNonTrivialToPrimitiveDefaultInitializeCUnion() ||
        InitType.hasNonTrivialToPrimitiveCopyCUnion()))
     checkNonTrivialCUnionInInitializer(Init, Init->getExprLoc());
 
   // We will represent direct-initialization similarly to copy-initialization:
   //    int x(1);  -as-> int x = 1;
   //    ClassType x(a,b,c); -as-> ClassType x = ClassType(a,b,c);
   //
   // Clients that want to distinguish between the two forms, can check for
   // direct initializer using VarDecl::getInitStyle().
   // A major benefit is that clients that don't particularly care about which
   // exactly form was it (like the CodeGen) can handle both cases without
   // special case code.
 
   // C++ 8.5p11:
   // The form of initialization (using parentheses or '=') is generally
   // insignificant, but does matter when the entity being initialized has a
   // class type.
   if (CXXDirectInit) {
     assert(DirectInit && "Call-style initializer must be direct init.");
     VDecl->setInitStyle(IsParenListInit ? VarDecl::ParenListInit
                                         : VarDecl::CallInit);
   } else if (DirectInit) {
     // This must be list-initialization. No other way is direct-initialization.
     VDecl->setInitStyle(VarDecl::ListInit);
   }
 
   if (LangOpts.OpenMP &&
       (LangOpts.OpenMPIsTargetDevice || !LangOpts.OMPTargetTriples.empty()) &&
       VDecl->isFileVarDecl())
     DeclsToCheckForDeferredDiags.insert(VDecl);
   CheckCompleteVariableDeclaration(VDecl);
 }
 
 /// ActOnInitializerError - Given that there was an error parsing an
 /// initializer for the given declaration, try to at least re-establish
 /// invariants such as whether a variable's type is either dependent or
 /// complete.
 void Sema::ActOnInitializerError(Decl *D) {
   // Our main concern here is re-establishing invariants like "a
   // variable's type is either dependent or complete".
   if (!D || D->isInvalidDecl()) return;
 
   VarDecl *VD = dyn_cast<VarDecl>(D);
   if (!VD) return;
 
   // Bindings are not usable if we can't make sense of the initializer.
   if (auto *DD = dyn_cast<DecompositionDecl>(D))
     for (auto *BD : DD->bindings())
       BD->setInvalidDecl();
 
   // Auto types are meaningless if we can't make sense of the initializer.
   if (VD->getType()->isUndeducedType()) {
     D->setInvalidDecl();
     return;
   }
 
   QualType Ty = VD->getType();
   if (Ty->isDependentType()) return;
 
   // Require a complete type.
   if (RequireCompleteType(VD->getLocation(),
                           Context.getBaseElementType(Ty),
                           diag::err_typecheck_decl_incomplete_type)) {
     VD->setInvalidDecl();
     return;
   }
 
   // Require a non-abstract type.
   if (RequireNonAbstractType(VD->getLocation(), Ty,
                              diag::err_abstract_type_in_decl,
                              AbstractVariableType)) {
     VD->setInvalidDecl();
     return;
   }
 
   // Don't bother complaining about constructors or destructors,
   // though.
 }
 
 void Sema::ActOnUninitializedDecl(Decl *RealDecl) {
   // If there is no declaration, there was an error parsing it. Just ignore it.
   if (!RealDecl)
     return;
 
   if (VarDecl *Var = dyn_cast<VarDecl>(RealDecl)) {
     QualType Type = Var->getType();
 
     // C++1z [dcl.dcl]p1 grammar implies that an initializer is mandatory.
     if (isa<DecompositionDecl>(RealDecl)) {
       Diag(Var->getLocation(), diag::err_decomp_decl_requires_init) << Var;
       Var->setInvalidDecl();
       return;
     }
 
     if (Type->isUndeducedType() &&
         DeduceVariableDeclarationType(Var, false, nullptr))
       return;
 
     // C++11 [class.static.data]p3: A static data member can be declared with
     // the constexpr specifier; if so, its declaration shall specify
     // a brace-or-equal-initializer.
     // C++11 [dcl.constexpr]p1: The constexpr specifier shall be applied only to
     // the definition of a variable [...] or the declaration of a static data
     // member.
     if (Var->isConstexpr() && !Var->isThisDeclarationADefinition() &&
         !Var->isThisDeclarationADemotedDefinition()) {
       if (Var->isStaticDataMember()) {
         // C++1z removes the relevant rule; the in-class declaration is always
         // a definition there.
         if (!getLangOpts().CPlusPlus17 &&
             !Context.getTargetInfo().getCXXABI().isMicrosoft()) {
           Diag(Var->getLocation(),
                diag::err_constexpr_static_mem_var_requires_init)
               << Var;
           Var->setInvalidDecl();
           return;
         }
       } else {
         Diag(Var->getLocation(), diag::err_invalid_constexpr_var_decl);
         Var->setInvalidDecl();
         return;
       }
     }
 
     // OpenCL v1.1 s6.5.3: variables declared in the constant address space must
     // be initialized.
     if (!Var->isInvalidDecl() &&
         Var->getType().getAddressSpace() == LangAS::opencl_constant &&
         Var->getStorageClass() != SC_Extern && !Var->getInit()) {
       bool HasConstExprDefaultConstructor = false;
       if (CXXRecordDecl *RD = Var->getType()->getAsCXXRecordDecl()) {
         for (auto *Ctor : RD->ctors()) {
           if (Ctor->isConstexpr() && Ctor->getNumParams() == 0 &&
               Ctor->getMethodQualifiers().getAddressSpace() ==
                   LangAS::opencl_constant) {
             HasConstExprDefaultConstructor = true;
           }
         }
       }
       if (!HasConstExprDefaultConstructor) {
         Diag(Var->getLocation(), diag::err_opencl_constant_no_init);
         Var->setInvalidDecl();
         return;
       }
     }
 
     if (!Var->isInvalidDecl() && RealDecl->hasAttr<LoaderUninitializedAttr>()) {
       if (Var->getStorageClass() == SC_Extern) {
         Diag(Var->getLocation(), diag::err_loader_uninitialized_extern_decl)
             << Var;
         Var->setInvalidDecl();
         return;
       }
       if (RequireCompleteType(Var->getLocation(), Var->getType(),
                               diag::err_typecheck_decl_incomplete_type)) {
         Var->setInvalidDecl();
         return;
       }
       if (CXXRecordDecl *RD = Var->getType()->getAsCXXRecordDecl()) {
         if (!RD->hasTrivialDefaultConstructor()) {
           Diag(Var->getLocation(), diag::err_loader_uninitialized_trivial_ctor);
           Var->setInvalidDecl();
           return;
         }
       }
       // The declaration is unitialized, no need for further checks.
       return;
     }
 
     VarDecl::DefinitionKind DefKind = Var->isThisDeclarationADefinition();
     if (!Var->isInvalidDecl() && DefKind != VarDecl::DeclarationOnly &&
         Var->getType().hasNonTrivialToPrimitiveDefaultInitializeCUnion())
       checkNonTrivialCUnion(Var->getType(), Var->getLocation(),
                             NTCUC_DefaultInitializedObject, NTCUK_Init);
 
 
     switch (DefKind) {
     case VarDecl::Definition:
       if (!Var->isStaticDataMember() || !Var->getAnyInitializer())
         break;
 
       // We have an out-of-line definition of a static data member
       // that has an in-class initializer, so we type-check this like
       // a declaration.
       //
       [[fallthrough]];
 
     case VarDecl::DeclarationOnly:
       // It's only a declaration.
 
       // Block scope. C99 6.7p7: If an identifier for an object is
       // declared with no linkage (C99 6.2.2p6), the type for the
       // object shall be complete.
       if (!Type->isDependentType() && Var->isLocalVarDecl() &&
           !Var->hasLinkage() && !Var->isInvalidDecl() &&
           RequireCompleteType(Var->getLocation(), Type,
                               diag::err_typecheck_decl_incomplete_type))
         Var->setInvalidDecl();
 
       // Make sure that the type is not abstract.
       if (!Type->isDependentType() && !Var->isInvalidDecl() &&
           RequireNonAbstractType(Var->getLocation(), Type,
                                  diag::err_abstract_type_in_decl,
                                  AbstractVariableType))
         Var->setInvalidDecl();
       if (!Type->isDependentType() && !Var->isInvalidDecl() &&
           Var->getStorageClass() == SC_PrivateExtern) {
         Diag(Var->getLocation(), diag::warn_private_extern);
         Diag(Var->getLocation(), diag::note_private_extern);
       }
 
       if (Context.getTargetInfo().allowDebugInfoForExternalRef() &&
           !Var->isInvalidDecl())
         ExternalDeclarations.push_back(Var);
 
       return;
 
     case VarDecl::TentativeDefinition:
       // File scope. C99 6.9.2p2: A declaration of an identifier for an
       // object that has file scope without an initializer, and without a
       // storage-class specifier or with the storage-class specifier "static",
       // constitutes a tentative definition. Note: A tentative definition with
       // external linkage is valid (C99 6.2.2p5).
       if (!Var->isInvalidDecl()) {
         if (const IncompleteArrayType *ArrayT
                                     = Context.getAsIncompleteArrayType(Type)) {
           if (RequireCompleteSizedType(
                   Var->getLocation(), ArrayT->getElementType(),
                   diag::err_array_incomplete_or_sizeless_type))
             Var->setInvalidDecl();
         } else if (Var->getStorageClass() == SC_Static) {
           // C99 6.9.2p3: If the declaration of an identifier for an object is
           // a tentative definition and has internal linkage (C99 6.2.2p3), the
           // declared type shall not be an incomplete type.
           // NOTE: code such as the following
           //     static struct s;
           //     struct s { int a; };
           // is accepted by gcc. Hence here we issue a warning instead of
           // an error and we do not invalidate the static declaration.
           // NOTE: to avoid multiple warnings, only check the first declaration.
           if (Var->isFirstDecl())
             RequireCompleteType(Var->getLocation(), Type,
                                 diag::ext_typecheck_decl_incomplete_type);
         }
       }
 
       // Record the tentative definition; we're done.
       if (!Var->isInvalidDecl())
         TentativeDefinitions.push_back(Var);
       return;
     }
 
     // Provide a specific diagnostic for uninitialized variable
     // definitions with incomplete array type.
     if (Type->isIncompleteArrayType()) {
       if (Var->isConstexpr())
         Diag(Var->getLocation(), diag::err_constexpr_var_requires_const_init)
             << Var;
       else
         Diag(Var->getLocation(),
              diag::err_typecheck_incomplete_array_needs_initializer);
       Var->setInvalidDecl();
       return;
     }
 
     // Provide a specific diagnostic for uninitialized variable
     // definitions with reference type.
     if (Type->isReferenceType()) {
       Diag(Var->getLocation(), diag::err_reference_var_requires_init)
           << Var << SourceRange(Var->getLocation(), Var->getLocation());
       return;
     }
 
     // Do not attempt to type-check the default initializer for a
     // variable with dependent type.
     if (Type->isDependentType())
       return;
 
     if (Var->isInvalidDecl())
       return;
 
     if (!Var->hasAttr<AliasAttr>()) {
       if (RequireCompleteType(Var->getLocation(),
                               Context.getBaseElementType(Type),
                               diag::err_typecheck_decl_incomplete_type)) {
         Var->setInvalidDecl();
         return;
       }
     } else {
       return;
     }
 
     // The variable can not have an abstract class type.
     if (RequireNonAbstractType(Var->getLocation(), Type,
                                diag::err_abstract_type_in_decl,
                                AbstractVariableType)) {
       Var->setInvalidDecl();
       return;
     }
 
     // Check for jumps past the implicit initializer.  C++0x
     // clarifies that this applies to a "variable with automatic
     // storage duration", not a "local variable".
     // C++11 [stmt.dcl]p3
     //   A program that jumps from a point where a variable with automatic
     //   storage duration is not in scope to a point where it is in scope is
     //   ill-formed unless the variable has scalar type, class type with a
     //   trivial default constructor and a trivial destructor, a cv-qualified
     //   version of one of these types, or an array of one of the preceding
     //   types and is declared without an initializer.
     if (getLangOpts().CPlusPlus && Var->hasLocalStorage()) {
       if (const RecordType *Record
             = Context.getBaseElementType(Type)->getAs<RecordType>()) {
         CXXRecordDecl *CXXRecord = cast<CXXRecordDecl>(Record->getDecl());
         // Mark the function (if we're in one) for further checking even if the
         // looser rules of C++11 do not require such checks, so that we can
         // diagnose incompatibilities with C++98.
         if (!CXXRecord->isPOD())
           setFunctionHasBranchProtectedScope();
       }
     }
     // In OpenCL, we can't initialize objects in the __local address space,
     // even implicitly, so don't synthesize an implicit initializer.
     if (getLangOpts().OpenCL &&
         Var->getType().getAddressSpace() == LangAS::opencl_local)
       return;
     // C++03 [dcl.init]p9:
     //   If no initializer is specified for an object, and the
     //   object is of (possibly cv-qualified) non-POD class type (or
     //   array thereof), the object shall be default-initialized; if
     //   the object is of const-qualified type, the underlying class
     //   type shall have a user-declared default
     //   constructor. Otherwise, if no initializer is specified for
     //   a non- static object, the object and its subobjects, if
     //   any, have an indeterminate initial value); if the object
     //   or any of its subobjects are of const-qualified type, the
     //   program is ill-formed.
     // C++0x [dcl.init]p11:
     //   If no initializer is specified for an object, the object is
     //   default-initialized; [...].
     InitializedEntity Entity = InitializedEntity::InitializeVariable(Var);
     InitializationKind Kind
       = InitializationKind::CreateDefault(Var->getLocation());
 
     InitializationSequence InitSeq(*this, Entity, Kind, std::nullopt);
     ExprResult Init = InitSeq.Perform(*this, Entity, Kind, std::nullopt);
 
     if (Init.get()) {
       Var->setInit(MaybeCreateExprWithCleanups(Init.get()));
       // This is important for template substitution.
       Var->setInitStyle(VarDecl::CallInit);
     } else if (Init.isInvalid()) {
       // If default-init fails, attach a recovery-expr initializer to track
       // that initialization was attempted and failed.
       auto RecoveryExpr =
           CreateRecoveryExpr(Var->getLocation(), Var->getLocation(), {});
       if (RecoveryExpr.get())
         Var->setInit(RecoveryExpr.get());
     }
 
     CheckCompleteVariableDeclaration(Var);
   }
 }
 
 void Sema::ActOnCXXForRangeDecl(Decl *D) {
   // If there is no declaration, there was an error parsing it. Ignore it.
   if (!D)
     return;
 
   VarDecl *VD = dyn_cast<VarDecl>(D);
   if (!VD) {
     Diag(D->getLocation(), diag::err_for_range_decl_must_be_var);
     D->setInvalidDecl();
     return;
   }
 
   VD->setCXXForRangeDecl(true);
 
   // for-range-declaration cannot be given a storage class specifier.
   int Error = -1;
   switch (VD->getStorageClass()) {
   case SC_None:
     break;
   case SC_Extern:
     Error = 0;
     break;
   case SC_Static:
     Error = 1;
     break;
   case SC_PrivateExtern:
     Error = 2;
     break;
   case SC_Auto:
     Error = 3;
     break;
   case SC_Register:
     Error = 4;
     break;
   }
 
   // for-range-declaration cannot be given a storage class specifier con't.
   switch (VD->getTSCSpec()) {
   case TSCS_thread_local:
     Error = 6;
     break;
   case TSCS___thread:
   case TSCS__Thread_local:
   case TSCS_unspecified:
     break;
   }
 
   if (Error != -1) {
     Diag(VD->getOuterLocStart(), diag::err_for_range_storage_class)
         << VD << Error;
     D->setInvalidDecl();
   }
 }
 
 StmtResult Sema::ActOnCXXForRangeIdentifier(Scope *S, SourceLocation IdentLoc,
                                             IdentifierInfo *Ident,
                                             ParsedAttributes &Attrs) {
   // C++1y [stmt.iter]p1:
   //   A range-based for statement of the form
   //      for ( for-range-identifier : for-range-initializer ) statement
   //   is equivalent to
   //      for ( auto&& for-range-identifier : for-range-initializer ) statement
   DeclSpec DS(Attrs.getPool().getFactory());
 
   const char *PrevSpec;
   unsigned DiagID;
   DS.SetTypeSpecType(DeclSpec::TST_auto, IdentLoc, PrevSpec, DiagID,
                      getPrintingPolicy());
 
   Declarator D(DS, ParsedAttributesView::none(), DeclaratorContext::ForInit);
   D.SetIdentifier(Ident, IdentLoc);
   D.takeAttributes(Attrs);
 
   D.AddTypeInfo(DeclaratorChunk::getReference(0, IdentLoc, /*lvalue*/ false),
                 IdentLoc);
   Decl *Var = ActOnDeclarator(S, D);
   cast<VarDecl>(Var)->setCXXForRangeDecl(true);
   FinalizeDeclaration(Var);
   return ActOnDeclStmt(FinalizeDeclaratorGroup(S, DS, Var), IdentLoc,
                        Attrs.Range.getEnd().isValid() ? Attrs.Range.getEnd()
                                                       : IdentLoc);
 }
 
 void Sema::CheckCompleteVariableDeclaration(VarDecl *var) {
   if (var->isInvalidDecl()) return;
 
   MaybeAddCUDAConstantAttr(var);
 
   if (getLangOpts().OpenCL) {
     // OpenCL v2.0 s6.12.5 - Every block variable declaration must have an
     // initialiser
     if (var->getTypeSourceInfo()->getType()->isBlockPointerType() &&
         !var->hasInit()) {
       Diag(var->getLocation(), diag::err_opencl_invalid_block_declaration)
           << 1 /*Init*/;
       var->setInvalidDecl();
       return;
     }
   }
 
   // In Objective-C, don't allow jumps past the implicit initialization of a
   // local retaining variable.
   if (getLangOpts().ObjC &&
       var->hasLocalStorage()) {
     switch (var->getType().getObjCLifetime()) {
     case Qualifiers::OCL_None:
     case Qualifiers::OCL_ExplicitNone:
     case Qualifiers::OCL_Autoreleasing:
       break;
 
     case Qualifiers::OCL_Weak:
     case Qualifiers::OCL_Strong:
       setFunctionHasBranchProtectedScope();
       break;
     }
   }
 
   if (var->hasLocalStorage() &&
       var->getType().isDestructedType() == QualType::DK_nontrivial_c_struct)
     setFunctionHasBranchProtectedScope();
 
   // Warn about externally-visible variables being defined without a
   // prior declaration.  We only want to do this for global
   // declarations, but we also specifically need to avoid doing it for
   // class members because the linkage of an anonymous class can
   // change if it's later given a typedef name.
   if (var->isThisDeclarationADefinition() &&
       var->getDeclContext()->getRedeclContext()->isFileContext() &&
       var->isExternallyVisible() && var->hasLinkage() &&
       !var->isInline() && !var->getDescribedVarTemplate() &&
       !isa<VarTemplatePartialSpecializationDecl>(var) &&
       !isTemplateInstantiation(var->getTemplateSpecializationKind()) &&
       !getDiagnostics().isIgnored(diag::warn_missing_variable_declarations,
                                   var->getLocation())) {
     // Find a previous declaration that's not a definition.
     VarDecl *prev = var->getPreviousDecl();
     while (prev && prev->isThisDeclarationADefinition())
       prev = prev->getPreviousDecl();
 
     if (!prev) {
       Diag(var->getLocation(), diag::warn_missing_variable_declarations) << var;
       Diag(var->getTypeSpecStartLoc(), diag::note_static_for_internal_linkage)
           << /* variable */ 0;
     }
   }
 
   // Cache the result of checking for constant initialization.
   std::optional<bool> CacheHasConstInit;
   const Expr *CacheCulprit = nullptr;
   auto checkConstInit = [&]() mutable {
     if (!CacheHasConstInit)
       CacheHasConstInit = var->getInit()->isConstantInitializer(
             Context, var->getType()->isReferenceType(), &CacheCulprit);
     return *CacheHasConstInit;
   };
 
   if (var->getTLSKind() == VarDecl::TLS_Static) {
     if (var->getType().isDestructedType()) {
       // GNU C++98 edits for __thread, [basic.start.term]p3:
       //   The type of an object with thread storage duration shall not
       //   have a non-trivial destructor.
       Diag(var->getLocation(), diag::err_thread_nontrivial_dtor);
       if (getLangOpts().CPlusPlus11)
         Diag(var->getLocation(), diag::note_use_thread_local);
     } else if (getLangOpts().CPlusPlus && var->hasInit()) {
       if (!checkConstInit()) {
         // GNU C++98 edits for __thread, [basic.start.init]p4:
         //   An object of thread storage duration shall not require dynamic
         //   initialization.
         // FIXME: Need strict checking here.
         Diag(CacheCulprit->getExprLoc(), diag::err_thread_dynamic_init)
           << CacheCulprit->getSourceRange();
         if (getLangOpts().CPlusPlus11)
           Diag(var->getLocation(), diag::note_use_thread_local);
       }
     }
   }
 
 
   if (!var->getType()->isStructureType() && var->hasInit() &&
       isa<InitListExpr>(var->getInit())) {
     const auto *ILE = cast<InitListExpr>(var->getInit());
     unsigned NumInits = ILE->getNumInits();
     if (NumInits > 2)
       for (unsigned I = 0; I < NumInits; ++I) {
         const auto *Init = ILE->getInit(I);
         if (!Init)
           break;
         const auto *SL = dyn_cast<StringLiteral>(Init->IgnoreImpCasts());
         if (!SL)
           break;
 
         unsigned NumConcat = SL->getNumConcatenated();
         // Diagnose missing comma in string array initialization.
         // Do not warn when all the elements in the initializer are concatenated
         // together. Do not warn for macros too.
         if (NumConcat == 2 && !SL->getBeginLoc().isMacroID()) {
           bool OnlyOneMissingComma = true;
           for (unsigned J = I + 1; J < NumInits; ++J) {
             const auto *Init = ILE->getInit(J);
             if (!Init)
               break;
             const auto *SLJ = dyn_cast<StringLiteral>(Init->IgnoreImpCasts());
             if (!SLJ || SLJ->getNumConcatenated() > 1) {
               OnlyOneMissingComma = false;
               break;
             }
           }
 
           if (OnlyOneMissingComma) {
             SmallVector<FixItHint, 1> Hints;
             for (unsigned i = 0; i < NumConcat - 1; ++i)
               Hints.push_back(FixItHint::CreateInsertion(
                   PP.getLocForEndOfToken(SL->getStrTokenLoc(i)), ","));
 
             Diag(SL->getStrTokenLoc(1),
                  diag::warn_concatenated_literal_array_init)
                 << Hints;
             Diag(SL->getBeginLoc(),
                  diag::note_concatenated_string_literal_silence);
           }
           // In any case, stop now.
           break;
         }
       }
   }
 
 
   QualType type = var->getType();
 
   if (var->hasAttr<BlocksAttr>())
     getCurFunction()->addByrefBlockVar(var);
 
   Expr *Init = var->getInit();
   bool GlobalStorage = var->hasGlobalStorage();
   bool IsGlobal = GlobalStorage && !var->isStaticLocal();
   QualType baseType = Context.getBaseElementType(type);
   bool HasConstInit = true;
 
   // Check whether the initializer is sufficiently constant.
   if (getLangOpts().CPlusPlus && !type->isDependentType() && Init &&
       !Init->isValueDependent() &&
       (GlobalStorage || var->isConstexpr() ||
        var->mightBeUsableInConstantExpressions(Context))) {
     // If this variable might have a constant initializer or might be usable in
     // constant expressions, check whether or not it actually is now.  We can't
     // do this lazily, because the result might depend on things that change
     // later, such as which constexpr functions happen to be defined.
     SmallVector<PartialDiagnosticAt, 8> Notes;
     if (!getLangOpts().CPlusPlus11) {
       // Prior to C++11, in contexts where a constant initializer is required,
       // the set of valid constant initializers is described by syntactic rules
       // in [expr.const]p2-6.
       // FIXME: Stricter checking for these rules would be useful for constinit /
       // -Wglobal-constructors.
       HasConstInit = checkConstInit();
 
       // Compute and cache the constant value, and remember that we have a
       // constant initializer.
       if (HasConstInit) {
         (void)var->checkForConstantInitialization(Notes);
         Notes.clear();
       } else if (CacheCulprit) {
         Notes.emplace_back(CacheCulprit->getExprLoc(),
                            PDiag(diag::note_invalid_subexpr_in_const_expr));
         Notes.back().second << CacheCulprit->getSourceRange();
       }
     } else {
       // Evaluate the initializer to see if it's a constant initializer.
       HasConstInit = var->checkForConstantInitialization(Notes);
     }
 
     if (HasConstInit) {
       // FIXME: Consider replacing the initializer with a ConstantExpr.
     } else if (var->isConstexpr()) {
       SourceLocation DiagLoc = var->getLocation();
       // If the note doesn't add any useful information other than a source
       // location, fold it into the primary diagnostic.
       if (Notes.size() == 1 && Notes[0].second.getDiagID() ==
                                    diag::note_invalid_subexpr_in_const_expr) {
         DiagLoc = Notes[0].first;
         Notes.clear();
       }
       Diag(DiagLoc, diag::err_constexpr_var_requires_const_init)
           << var << Init->getSourceRange();
       for (unsigned I = 0, N = Notes.size(); I != N; ++I)
         Diag(Notes[I].first, Notes[I].second);
     } else if (GlobalStorage && var->hasAttr<ConstInitAttr>()) {
       auto *Attr = var->getAttr<ConstInitAttr>();
       Diag(var->getLocation(), diag::err_require_constant_init_failed)
           << Init->getSourceRange();
       Diag(Attr->getLocation(), diag::note_declared_required_constant_init_here)
           << Attr->getRange() << Attr->isConstinit();
       for (auto &it : Notes)
         Diag(it.first, it.second);
     } else if (IsGlobal &&
                !getDiagnostics().isIgnored(diag::warn_global_constructor,
                                            var->getLocation())) {
       // Warn about globals which don't have a constant initializer.  Don't
       // warn about globals with a non-trivial destructor because we already
       // warned about them.
       CXXRecordDecl *RD = baseType->getAsCXXRecordDecl();
       if (!(RD && !RD->hasTrivialDestructor())) {
         // checkConstInit() here permits trivial default initialization even in
         // C++11 onwards, where such an initializer is not a constant initializer
         // but nonetheless doesn't require a global constructor.
         if (!checkConstInit())
           Diag(var->getLocation(), diag::warn_global_constructor)
               << Init->getSourceRange();
       }
     }
   }
 
   // Apply section attributes and pragmas to global variables.
   if (GlobalStorage && var->isThisDeclarationADefinition() &&
       !inTemplateInstantiation()) {
     PragmaStack<StringLiteral *> *Stack = nullptr;
     int SectionFlags = ASTContext::PSF_Read;
     if (var->getType().isConstQualified()) {
       if (HasConstInit)
         Stack = &ConstSegStack;
       else {
         Stack = &BSSSegStack;
         SectionFlags |= ASTContext::PSF_Write;
       }
     } else if (var->hasInit() && HasConstInit) {
       Stack = &DataSegStack;
       SectionFlags |= ASTContext::PSF_Write;
     } else {
       Stack = &BSSSegStack;
       SectionFlags |= ASTContext::PSF_Write;
     }
     if (const SectionAttr *SA = var->getAttr<SectionAttr>()) {
       if (SA->getSyntax() == AttributeCommonInfo::AS_Declspec)
         SectionFlags |= ASTContext::PSF_Implicit;
       UnifySection(SA->getName(), SectionFlags, var);
     } else if (Stack->CurrentValue) {
       SectionFlags |= ASTContext::PSF_Implicit;
       auto SectionName = Stack->CurrentValue->getString();
       var->addAttr(SectionAttr::CreateImplicit(Context, SectionName,
                                                Stack->CurrentPragmaLocation,
                                                SectionAttr::Declspec_allocate));
       if (UnifySection(SectionName, SectionFlags, var))
         var->dropAttr<SectionAttr>();
     }
 
     // Apply the init_seg attribute if this has an initializer.  If the
     // initializer turns out to not be dynamic, we'll end up ignoring this
     // attribute.
     if (CurInitSeg && var->getInit())
       var->addAttr(InitSegAttr::CreateImplicit(Context, CurInitSeg->getString(),
                                                CurInitSegLoc));
   }
 
   // All the following checks are C++ only.
   if (!getLangOpts().CPlusPlus) {
     // If this variable must be emitted, add it as an initializer for the
     // current module.
     if (Context.DeclMustBeEmitted(var) && !ModuleScopes.empty())
       Context.addModuleInitializer(ModuleScopes.back().Module, var);
     return;
   }
 
   // Require the destructor.
   if (!type->isDependentType())
     if (const RecordType *recordType = baseType->getAs<RecordType>())
       FinalizeVarWithDestructor(var, recordType);
 
   // If this variable must be emitted, add it as an initializer for the current
   // module.
   if (Context.DeclMustBeEmitted(var) && !ModuleScopes.empty())
     Context.addModuleInitializer(ModuleScopes.back().Module, var);
 
   // Build the bindings if this is a structured binding declaration.
   if (auto *DD = dyn_cast<DecompositionDecl>(var))
     CheckCompleteDecompositionDeclaration(DD);
 }
 
 /// Check if VD needs to be dllexport/dllimport due to being in a
 /// dllexport/import function.
 void Sema::CheckStaticLocalForDllExport(VarDecl *VD) {
   assert(VD->isStaticLocal());
 
   auto *FD = dyn_cast_or_null<FunctionDecl>(VD->getParentFunctionOrMethod());
 
   // Find outermost function when VD is in lambda function.
   while (FD && !getDLLAttr(FD) &&
          !FD->hasAttr<DLLExportStaticLocalAttr>() &&
          !FD->hasAttr<DLLImportStaticLocalAttr>()) {
     FD = dyn_cast_or_null<FunctionDecl>(FD->getParentFunctionOrMethod());
   }
 
   if (!FD)
     return;
 
   // Static locals inherit dll attributes from their function.
   if (Attr *A = getDLLAttr(FD)) {
     auto *NewAttr = cast<InheritableAttr>(A->clone(getASTContext()));
     NewAttr->setInherited(true);
     VD->addAttr(NewAttr);
   } else if (Attr *A = FD->getAttr<DLLExportStaticLocalAttr>()) {
     auto *NewAttr = DLLExportAttr::CreateImplicit(getASTContext(), *A);
     NewAttr->setInherited(true);
     VD->addAttr(NewAttr);
 
     // Export this function to enforce exporting this static variable even
     // if it is not used in this compilation unit.
     if (!FD->hasAttr<DLLExportAttr>())
       FD->addAttr(NewAttr);
 
   } else if (Attr *A = FD->getAttr<DLLImportStaticLocalAttr>()) {
     auto *NewAttr = DLLImportAttr::CreateImplicit(getASTContext(), *A);
     NewAttr->setInherited(true);
     VD->addAttr(NewAttr);
   }
 }
 
 void Sema::CheckThreadLocalForLargeAlignment(VarDecl *VD) {
   assert(VD->getTLSKind());
 
   // Perform TLS alignment check here after attributes attached to the variable
   // which may affect the alignment have been processed. Only perform the check
   // if the target has a maximum TLS alignment (zero means no constraints).
   if (unsigned MaxAlign = Context.getTargetInfo().getMaxTLSAlign()) {
     // Protect the check so that it's not performed on dependent types and
     // dependent alignments (we can't determine the alignment in that case).
     if (!VD->hasDependentAlignment()) {
       CharUnits MaxAlignChars = Context.toCharUnitsFromBits(MaxAlign);
       if (Context.getDeclAlign(VD) > MaxAlignChars) {
         Diag(VD->getLocation(), diag::err_tls_var_aligned_over_maximum)
             << (unsigned)Context.getDeclAlign(VD).getQuantity() << VD
             << (unsigned)MaxAlignChars.getQuantity();
       }
     }
   }
 }
 
 /// FinalizeDeclaration - called by ParseDeclarationAfterDeclarator to perform
 /// any semantic actions necessary after any initializer has been attached.
 void Sema::FinalizeDeclaration(Decl *ThisDecl) {
   // Note that we are no longer parsing the initializer for this declaration.
   ParsingInitForAutoVars.erase(ThisDecl);
 
   VarDecl *VD = dyn_cast_or_null<VarDecl>(ThisDecl);
   if (!VD)
     return;
 
   // Apply an implicit SectionAttr if '#pragma clang section bss|data|rodata' is active
   if (VD->hasGlobalStorage() && VD->isThisDeclarationADefinition() &&
       !inTemplateInstantiation() && !VD->hasAttr<SectionAttr>()) {
     if (PragmaClangBSSSection.Valid)
       VD->addAttr(PragmaClangBSSSectionAttr::CreateImplicit(
           Context, PragmaClangBSSSection.SectionName,
           PragmaClangBSSSection.PragmaLocation));
     if (PragmaClangDataSection.Valid)
       VD->addAttr(PragmaClangDataSectionAttr::CreateImplicit(
           Context, PragmaClangDataSection.SectionName,
           PragmaClangDataSection.PragmaLocation));
     if (PragmaClangRodataSection.Valid)
       VD->addAttr(PragmaClangRodataSectionAttr::CreateImplicit(
           Context, PragmaClangRodataSection.SectionName,
           PragmaClangRodataSection.PragmaLocation));
     if (PragmaClangRelroSection.Valid)
       VD->addAttr(PragmaClangRelroSectionAttr::CreateImplicit(
           Context, PragmaClangRelroSection.SectionName,
           PragmaClangRelroSection.PragmaLocation));
   }
 
   if (auto *DD = dyn_cast<DecompositionDecl>(ThisDecl)) {
     for (auto *BD : DD->bindings()) {
       FinalizeDeclaration(BD);
     }
   }
 
   checkAttributesAfterMerging(*this, *VD);
 
   if (VD->isStaticLocal())
     CheckStaticLocalForDllExport(VD);
 
   if (VD->getTLSKind())
     CheckThreadLocalForLargeAlignment(VD);
 
   // Perform check for initializers of device-side global variables.
   // CUDA allows empty constructors as initializers (see E.2.3.1, CUDA
   // 7.5). We must also apply the same checks to all __shared__
   // variables whether they are local or not. CUDA also allows
   // constant initializers for __constant__ and __device__ variables.
   if (getLangOpts().CUDA)
     checkAllowedCUDAInitializer(VD);
 
   // Grab the dllimport or dllexport attribute off of the VarDecl.
   const InheritableAttr *DLLAttr = getDLLAttr(VD);
 
   // Imported static data members cannot be defined out-of-line.
   if (const auto *IA = dyn_cast_or_null<DLLImportAttr>(DLLAttr)) {
     if (VD->isStaticDataMember() && VD->isOutOfLine() &&
         VD->isThisDeclarationADefinition()) {
       // We allow definitions of dllimport class template static data members
       // with a warning.
       CXXRecordDecl *Context =
         cast<CXXRecordDecl>(VD->getFirstDecl()->getDeclContext());
       bool IsClassTemplateMember =
           isa<ClassTemplatePartialSpecializationDecl>(Context) ||
           Context->getDescribedClassTemplate();
 
       Diag(VD->getLocation(),
            IsClassTemplateMember
                ? diag::warn_attribute_dllimport_static_field_definition
                : diag::err_attribute_dllimport_static_field_definition);
       Diag(IA->getLocation(), diag::note_attribute);
       if (!IsClassTemplateMember)
         VD->setInvalidDecl();
     }
   }
 
   // dllimport/dllexport variables cannot be thread local, their TLS index
   // isn't exported with the variable.
   if (DLLAttr && VD->getTLSKind()) {
     auto *F = dyn_cast_or_null<FunctionDecl>(VD->getParentFunctionOrMethod());
     if (F && getDLLAttr(F)) {
       assert(VD->isStaticLocal());
       // But if this is a static local in a dlimport/dllexport function, the
       // function will never be inlined, which means the var would never be
       // imported, so having it marked import/export is safe.
     } else {
       Diag(VD->getLocation(), diag::err_attribute_dll_thread_local) << VD
                                                                     << DLLAttr;
       VD->setInvalidDecl();
     }
   }
 
   if (UsedAttr *Attr = VD->getAttr<UsedAttr>()) {
     if (!Attr->isInherited() && !VD->isThisDeclarationADefinition()) {
       Diag(Attr->getLocation(), diag::warn_attribute_ignored_on_non_definition)
           << Attr;
       VD->dropAttr<UsedAttr>();
     }
   }
   if (RetainAttr *Attr = VD->getAttr<RetainAttr>()) {
     if (!Attr->isInherited() && !VD->isThisDeclarationADefinition()) {
       Diag(Attr->getLocation(), diag::warn_attribute_ignored_on_non_definition)
           << Attr;
       VD->dropAttr<RetainAttr>();
     }
   }
 
   const DeclContext *DC = VD->getDeclContext();
   // If there's a #pragma GCC visibility in scope, and this isn't a class
   // member, set the visibility of this variable.
   if (DC->getRedeclContext()->isFileContext() && VD->isExternallyVisible())
     AddPushedVisibilityAttribute(VD);
 
   // FIXME: Warn on unused var template partial specializations.
   if (VD->isFileVarDecl() && !isa<VarTemplatePartialSpecializationDecl>(VD))
     MarkUnusedFileScopedDecl(VD);
 
   // Now we have parsed the initializer and can update the table of magic
   // tag values.
   if (!VD->hasAttr<TypeTagForDatatypeAttr>() ||
       !VD->getType()->isIntegralOrEnumerationType())
     return;
 
   for (const auto *I : ThisDecl->specific_attrs<TypeTagForDatatypeAttr>()) {
     const Expr *MagicValueExpr = VD->getInit();
     if (!MagicValueExpr) {
       continue;
     }
     std::optional<llvm::APSInt> MagicValueInt;
     if (!(MagicValueInt = MagicValueExpr->getIntegerConstantExpr(Context))) {
       Diag(I->getRange().getBegin(),
            diag::err_type_tag_for_datatype_not_ice)
         << LangOpts.CPlusPlus << MagicValueExpr->getSourceRange();
       continue;
     }
     if (MagicValueInt->getActiveBits() > 64) {
       Diag(I->getRange().getBegin(),
            diag::err_type_tag_for_datatype_too_large)
         << LangOpts.CPlusPlus << MagicValueExpr->getSourceRange();
       continue;
     }
     uint64_t MagicValue = MagicValueInt->getZExtValue();
     RegisterTypeTagForDatatype(I->getArgumentKind(),
                                MagicValue,
                                I->getMatchingCType(),
                                I->getLayoutCompatible(),
                                I->getMustBeNull());
   }
 }
 
 static bool hasDeducedAuto(DeclaratorDecl *DD) {
   auto *VD = dyn_cast<VarDecl>(DD);
   return VD && !VD->getType()->hasAutoForTrailingReturnType();
 }
 
 Sema::DeclGroupPtrTy Sema::FinalizeDeclaratorGroup(Scope *S, const DeclSpec &DS,
                                                    ArrayRef<Decl *> Group) {
   SmallVector<Decl*, 8> Decls;
 
   if (DS.isTypeSpecOwned())
     Decls.push_back(DS.getRepAsDecl());
 
   DeclaratorDecl *FirstDeclaratorInGroup = nullptr;
   DecompositionDecl *FirstDecompDeclaratorInGroup = nullptr;
   bool DiagnosedMultipleDecomps = false;
   DeclaratorDecl *FirstNonDeducedAutoInGroup = nullptr;
   bool DiagnosedNonDeducedAuto = false;
 
   for (unsigned i = 0, e = Group.size(); i != e; ++i) {
     if (Decl *D = Group[i]) {
       // Check if the Decl has been declared in '#pragma omp declare target'
       // directive and has static storage duration.
       if (auto *VD = dyn_cast<VarDecl>(D);
           LangOpts.OpenMP && VD && VD->hasAttr<OMPDeclareTargetDeclAttr>() &&
           VD->hasGlobalStorage())
         ActOnOpenMPDeclareTargetInitializer(D);
       // For declarators, there are some additional syntactic-ish checks we need
       // to perform.
       if (auto *DD = dyn_cast<DeclaratorDecl>(D)) {
         if (!FirstDeclaratorInGroup)
           FirstDeclaratorInGroup = DD;
         if (!FirstDecompDeclaratorInGroup)
           FirstDecompDeclaratorInGroup = dyn_cast<DecompositionDecl>(D);
         if (!FirstNonDeducedAutoInGroup && DS.hasAutoTypeSpec() &&
             !hasDeducedAuto(DD))
           FirstNonDeducedAutoInGroup = DD;
 
         if (FirstDeclaratorInGroup != DD) {
           // A decomposition declaration cannot be combined with any other
           // declaration in the same group.
           if (FirstDecompDeclaratorInGroup && !DiagnosedMultipleDecomps) {
             Diag(FirstDecompDeclaratorInGroup->getLocation(),
                  diag::err_decomp_decl_not_alone)
                 << FirstDeclaratorInGroup->getSourceRange()
                 << DD->getSourceRange();
             DiagnosedMultipleDecomps = true;
           }
 
           // A declarator that uses 'auto' in any way other than to declare a
           // variable with a deduced type cannot be combined with any other
           // declarator in the same group.
           if (FirstNonDeducedAutoInGroup && !DiagnosedNonDeducedAuto) {
             Diag(FirstNonDeducedAutoInGroup->getLocation(),
                  diag::err_auto_non_deduced_not_alone)
                 << FirstNonDeducedAutoInGroup->getType()
                        ->hasAutoForTrailingReturnType()
                 << FirstDeclaratorInGroup->getSourceRange()
                 << DD->getSourceRange();
             DiagnosedNonDeducedAuto = true;
           }
         }
       }
 
       Decls.push_back(D);
     }
   }
 
   if (DeclSpec::isDeclRep(DS.getTypeSpecType())) {
     if (TagDecl *Tag = dyn_cast_or_null<TagDecl>(DS.getRepAsDecl())) {
       handleTagNumbering(Tag, S);
       if (FirstDeclaratorInGroup && !Tag->hasNameForLinkage() &&
           getLangOpts().CPlusPlus)
         Context.addDeclaratorForUnnamedTagDecl(Tag, FirstDeclaratorInGroup);
     }
   }
 
   return BuildDeclaratorGroup(Decls);
 }
 
 /// BuildDeclaratorGroup - convert a list of declarations into a declaration
 /// group, performing any necessary semantic checking.
 Sema::DeclGroupPtrTy
 Sema::BuildDeclaratorGroup(MutableArrayRef<Decl *> Group) {
   // C++14 [dcl.spec.auto]p7: (DR1347)
   //   If the type that replaces the placeholder type is not the same in each
   //   deduction, the program is ill-formed.
   if (Group.size() > 1) {
     QualType Deduced;
     VarDecl *DeducedDecl = nullptr;
     for (unsigned i = 0, e = Group.size(); i != e; ++i) {
       VarDecl *D = dyn_cast<VarDecl>(Group[i]);
       if (!D || D->isInvalidDecl())
         break;
       DeducedType *DT = D->getType()->getContainedDeducedType();
       if (!DT || DT->getDeducedType().isNull())
         continue;
       if (Deduced.isNull()) {
         Deduced = DT->getDeducedType();
         DeducedDecl = D;
       } else if (!Context.hasSameType(DT->getDeducedType(), Deduced)) {
         auto *AT = dyn_cast<AutoType>(DT);
         auto Dia = Diag(D->getTypeSourceInfo()->getTypeLoc().getBeginLoc(),
                         diag::err_auto_different_deductions)
                    << (AT ? (unsigned)AT->getKeyword() : 3) << Deduced
                    << DeducedDecl->getDeclName() << DT->getDeducedType()
                    << D->getDeclName();
         if (DeducedDecl->hasInit())
           Dia << DeducedDecl->getInit()->getSourceRange();
         if (D->getInit())
           Dia << D->getInit()->getSourceRange();
         D->setInvalidDecl();
         break;
       }
     }
   }
 
   ActOnDocumentableDecls(Group);
 
   return DeclGroupPtrTy::make(
       DeclGroupRef::Create(Context, Group.data(), Group.size()));
 }
 
 void Sema::ActOnDocumentableDecl(Decl *D) {
   ActOnDocumentableDecls(D);
 }
 
 void Sema::ActOnDocumentableDecls(ArrayRef<Decl *> Group) {
   // Don't parse the comment if Doxygen diagnostics are ignored.
   if (Group.empty() || !Group[0])
     return;
 
   if (Diags.isIgnored(diag::warn_doc_param_not_found,
                       Group[0]->getLocation()) &&
       Diags.isIgnored(diag::warn_unknown_comment_command_name,
                       Group[0]->getLocation()))
     return;
 
   if (Group.size() >= 2) {
     // This is a decl group.  Normally it will contain only declarations
     // produced from declarator list.  But in case we have any definitions or
     // additional declaration references:
     //   'typedef struct S {} S;'
     //   'typedef struct S *S;'
     //   'struct S *pS;'
     // FinalizeDeclaratorGroup adds these as separate declarations.
     Decl *MaybeTagDecl = Group[0];
     if (MaybeTagDecl && isa<TagDecl>(MaybeTagDecl)) {
       Group = Group.slice(1);
     }
   }
 
   // FIMXE: We assume every Decl in the group is in the same file.
   // This is false when preprocessor constructs the group from decls in
   // different files (e. g. macros or #include).
   Context.attachCommentsToJustParsedDecls(Group, &getPreprocessor());
 }
 
 /// Common checks for a parameter-declaration that should apply to both function
 /// parameters and non-type template parameters.
 void Sema::CheckFunctionOrTemplateParamDeclarator(Scope *S, Declarator &D) {
   // Check that there are no default arguments inside the type of this
   // parameter.
   if (getLangOpts().CPlusPlus)
     CheckExtraCXXDefaultArguments(D);
 
   // Parameter declarators cannot be qualified (C++ [dcl.meaning]p1).
   if (D.getCXXScopeSpec().isSet()) {
     Diag(D.getIdentifierLoc(), diag::err_qualified_param_declarator)
       << D.getCXXScopeSpec().getRange();
   }
 
   // [dcl.meaning]p1: An unqualified-id occurring in a declarator-id shall be a
   // simple identifier except [...irrelevant cases...].
   switch (D.getName().getKind()) {
   case UnqualifiedIdKind::IK_Identifier:
     break;
 
   case UnqualifiedIdKind::IK_OperatorFunctionId:
   case UnqualifiedIdKind::IK_ConversionFunctionId:
   case UnqualifiedIdKind::IK_LiteralOperatorId:
   case UnqualifiedIdKind::IK_ConstructorName:
   case UnqualifiedIdKind::IK_DestructorName:
   case UnqualifiedIdKind::IK_ImplicitSelfParam:
   case UnqualifiedIdKind::IK_DeductionGuideName:
     Diag(D.getIdentifierLoc(), diag::err_bad_parameter_name)
       << GetNameForDeclarator(D).getName();
     break;
 
   case UnqualifiedIdKind::IK_TemplateId:
   case UnqualifiedIdKind::IK_ConstructorTemplateId:
     // GetNameForDeclarator would not produce a useful name in this case.
     Diag(D.getIdentifierLoc(), diag::err_bad_parameter_name_template_id);
     break;
   }
 }
 
 /// ActOnParamDeclarator - Called from Parser::ParseFunctionDeclarator()
 /// to introduce parameters into function prototype scope.
 Decl *Sema::ActOnParamDeclarator(Scope *S, Declarator &D) {
   const DeclSpec &DS = D.getDeclSpec();
 
   // Verify C99 6.7.5.3p2: The only SCS allowed is 'register'.
 
   // C++03 [dcl.stc]p2 also permits 'auto'.
   StorageClass SC = SC_None;
   if (DS.getStorageClassSpec() == DeclSpec::SCS_register) {
     SC = SC_Register;
     // In C++11, the 'register' storage class specifier is deprecated.
     // In C++17, it is not allowed, but we tolerate it as an extension.
     if (getLangOpts().CPlusPlus11) {
       Diag(DS.getStorageClassSpecLoc(),
            getLangOpts().CPlusPlus17 ? diag::ext_register_storage_class
                                      : diag::warn_deprecated_register)
         << FixItHint::CreateRemoval(DS.getStorageClassSpecLoc());
     }
   } else if (getLangOpts().CPlusPlus &&
              DS.getStorageClassSpec() == DeclSpec::SCS_auto) {
     SC = SC_Auto;
   } else if (DS.getStorageClassSpec() != DeclSpec::SCS_unspecified) {
     Diag(DS.getStorageClassSpecLoc(),
          diag::err_invalid_storage_class_in_func_decl);
     D.getMutableDeclSpec().ClearStorageClassSpecs();
   }
 
   if (DeclSpec::TSCS TSCS = DS.getThreadStorageClassSpec())
     Diag(DS.getThreadStorageClassSpecLoc(), diag::err_invalid_thread)
       << DeclSpec::getSpecifierName(TSCS);
   if (DS.isInlineSpecified())
     Diag(DS.getInlineSpecLoc(), diag::err_inline_non_function)
         << getLangOpts().CPlusPlus17;
   if (DS.hasConstexprSpecifier())
     Diag(DS.getConstexprSpecLoc(), diag::err_invalid_constexpr)
         << 0 << static_cast<int>(D.getDeclSpec().getConstexprSpecifier());
 
   DiagnoseFunctionSpecifiers(DS);
 
   CheckFunctionOrTemplateParamDeclarator(S, D);
 
   TypeSourceInfo *TInfo = GetTypeForDeclarator(D, S);
   QualType parmDeclType = TInfo->getType();
 
   // Check for redeclaration of parameters, e.g. int foo(int x, int x);
   IdentifierInfo *II = D.getIdentifier();
   if (II) {
     LookupResult R(*this, II, D.getIdentifierLoc(), LookupOrdinaryName,
                    ForVisibleRedeclaration);
     LookupName(R, S);
     if (R.isSingleResult()) {
       NamedDecl *PrevDecl = R.getFoundDecl();
       if (PrevDecl->isTemplateParameter()) {
         // Maybe we will complain about the shadowed template parameter.
         DiagnoseTemplateParameterShadow(D.getIdentifierLoc(), PrevDecl);
         // Just pretend that we didn't see the previous declaration.
         PrevDecl = nullptr;
       } else if (S->isDeclScope(PrevDecl)) {
         Diag(D.getIdentifierLoc(), diag::err_param_redefinition) << II;
         Diag(PrevDecl->getLocation(), diag::note_previous_declaration);
 
         // Recover by removing the name
         II = nullptr;
         D.SetIdentifier(nullptr, D.getIdentifierLoc());
         D.setInvalidType(true);
       }
     }
   }
 
   // Temporarily put parameter variables in the translation unit, not
   // the enclosing context.  This prevents them from accidentally
   // looking like class members in C++.
   ParmVarDecl *New =
       CheckParameter(Context.getTranslationUnitDecl(), D.getBeginLoc(),
                      D.getIdentifierLoc(), II, parmDeclType, TInfo, SC);
 
   if (D.isInvalidType())
     New->setInvalidDecl();
 
   assert(S->isFunctionPrototypeScope());
   assert(S->getFunctionPrototypeDepth() >= 1);
   New->setScopeInfo(S->getFunctionPrototypeDepth() - 1,
                     S->getNextFunctionPrototypeIndex());
 
   // Add the parameter declaration into this scope.
   S->AddDecl(New);
   if (II)
     IdResolver.AddDecl(New);
 
   ProcessDeclAttributes(S, New, D);
 
   if (D.getDeclSpec().isModulePrivateSpecified())
     Diag(New->getLocation(), diag::err_module_private_local)
         << 1 << New << SourceRange(D.getDeclSpec().getModulePrivateSpecLoc())
         << FixItHint::CreateRemoval(D.getDeclSpec().getModulePrivateSpecLoc());
 
   if (New->hasAttr<BlocksAttr>()) {
     Diag(New->getLocation(), diag::err_block_on_nonlocal);
   }
 
   if (getLangOpts().OpenCL)
     deduceOpenCLAddressSpace(New);
 
   return New;
 }
 
 /// Synthesizes a variable for a parameter arising from a
 /// typedef.
 ParmVarDecl *Sema::BuildParmVarDeclForTypedef(DeclContext *DC,
                                               SourceLocation Loc,
                                               QualType T) {
   /* FIXME: setting StartLoc == Loc.
      Would it be worth to modify callers so as to provide proper source
      location for the unnamed parameters, embedding the parameter's type? */
   ParmVarDecl *Param = ParmVarDecl::Create(Context, DC, Loc, Loc, nullptr,
                                 T, Context.getTrivialTypeSourceInfo(T, Loc),
                                            SC_None, nullptr);
   Param->setImplicit();
   return Param;
 }
 
 void Sema::DiagnoseUnusedParameters(ArrayRef<ParmVarDecl *> Parameters) {
   // Don't diagnose unused-parameter errors in template instantiations; we
   // will already have done so in the template itself.
   if (inTemplateInstantiation())
     return;
 
   for (const ParmVarDecl *Parameter : Parameters) {
     if (!Parameter->isReferenced() && Parameter->getDeclName() &&
         !Parameter->hasAttr<UnusedAttr>()) {
       Diag(Parameter->getLocation(), diag::warn_unused_parameter)
         << Parameter->getDeclName();
     }
   }
 }
 
 void Sema::DiagnoseSizeOfParametersAndReturnValue(
     ArrayRef<ParmVarDecl *> Parameters, QualType ReturnTy, NamedDecl *D) {
   if (LangOpts.NumLargeByValueCopy == 0) // No check.
     return;
 
   // Warn if the return value is pass-by-value and larger than the specified
   // threshold.
   if (!ReturnTy->isDependentType() && ReturnTy.isPODType(Context)) {
     unsigned Size = Context.getTypeSizeInChars(ReturnTy).getQuantity();
     if (Size > LangOpts.NumLargeByValueCopy)
       Diag(D->getLocation(), diag::warn_return_value_size) << D << Size;
   }
 
   // Warn if any parameter is pass-by-value and larger than the specified
   // threshold.
   for (const ParmVarDecl *Parameter : Parameters) {
     QualType T = Parameter->getType();
     if (T->isDependentType() || !T.isPODType(Context))
       continue;
     unsigned Size = Context.getTypeSizeInChars(T).getQuantity();
     if (Size > LangOpts.NumLargeByValueCopy)
       Diag(Parameter->getLocation(), diag::warn_parameter_size)
           << Parameter << Size;
   }
 }
 
 ParmVarDecl *Sema::CheckParameter(DeclContext *DC, SourceLocation StartLoc,
                                   SourceLocation NameLoc, IdentifierInfo *Name,
                                   QualType T, TypeSourceInfo *TSInfo,
                                   StorageClass SC) {
   // In ARC, infer a lifetime qualifier for appropriate parameter types.
   if (getLangOpts().ObjCAutoRefCount &&
       T.getObjCLifetime() == Qualifiers::OCL_None &&
       T->isObjCLifetimeType()) {
 
     Qualifiers::ObjCLifetime lifetime;
 
     // Special cases for arrays:
     //   - if it's const, use __unsafe_unretained
     //   - otherwise, it's an error
     if (T->isArrayType()) {
       if (!T.isConstQualified()) {
         if (DelayedDiagnostics.shouldDelayDiagnostics())
           DelayedDiagnostics.add(
               sema::DelayedDiagnostic::makeForbiddenType(
               NameLoc, diag::err_arc_array_param_no_ownership, T, false));
         else
           Diag(NameLoc, diag::err_arc_array_param_no_ownership)
               << TSInfo->getTypeLoc().getSourceRange();
       }
       lifetime = Qualifiers::OCL_ExplicitNone;
     } else {
       lifetime = T->getObjCARCImplicitLifetime();
     }
     T = Context.getLifetimeQualifiedType(T, lifetime);
   }
 
   ParmVarDecl *New = ParmVarDecl::Create(Context, DC, StartLoc, NameLoc, Name,
                                          Context.getAdjustedParameterType(T),
                                          TSInfo, SC, nullptr);
 
   // Make a note if we created a new pack in the scope of a lambda, so that
   // we know that references to that pack must also be expanded within the
   // lambda scope.
   if (New->isParameterPack())
     if (auto *LSI = getEnclosingLambda())
       LSI->LocalPacks.push_back(New);
 
   if (New->getType().hasNonTrivialToPrimitiveDestructCUnion() ||
       New->getType().hasNonTrivialToPrimitiveCopyCUnion())
     checkNonTrivialCUnion(New->getType(), New->getLocation(),
                           NTCUC_FunctionParam, NTCUK_Destruct|NTCUK_Copy);
 
   // Parameter declarators cannot be interface types. All ObjC objects are
   // passed by reference.
   if (T->isObjCObjectType()) {
     SourceLocation TypeEndLoc =
         getLocForEndOfToken(TSInfo->getTypeLoc().getEndLoc());
     Diag(NameLoc,
          diag::err_object_cannot_be_passed_returned_by_value) << 1 << T
       << FixItHint::CreateInsertion(TypeEndLoc, "*");
     T = Context.getObjCObjectPointerType(T);
     New->setType(T);
   }
 
   // ISO/IEC TR 18037 S6.7.3: "The type of an object with automatic storage
   // duration shall not be qualified by an address-space qualifier."
   // Since all parameters have automatic store duration, they can not have
   // an address space.
   if (T.getAddressSpace() != LangAS::Default &&
       // OpenCL allows function arguments declared to be an array of a type
       // to be qualified with an address space.
       !(getLangOpts().OpenCL &&
         (T->isArrayType() || T.getAddressSpace() == LangAS::opencl_private)) &&
       // WebAssembly allows reference types as parameters. Funcref in particular
       // lives in a different address space.
       !(T->isFunctionPointerType() &&
         T.getAddressSpace() == LangAS::wasm_funcref)) {
     Diag(NameLoc, diag::err_arg_with_address_space);
     New->setInvalidDecl();
   }
 
   // PPC MMA non-pointer types are not allowed as function argument types.
   if (Context.getTargetInfo().getTriple().isPPC64() &&
       CheckPPCMMAType(New->getOriginalType(), New->getLocation())) {
     New->setInvalidDecl();
   }
 
   return New;
 }
 
 void Sema::ActOnFinishKNRParamDeclarations(Scope *S, Declarator &D,
                                            SourceLocation LocAfterDecls) {
   DeclaratorChunk::FunctionTypeInfo &FTI = D.getFunctionTypeInfo();
 
   // C99 6.9.1p6 "If a declarator includes an identifier list, each declaration
   // in the declaration list shall have at least one declarator, those
   // declarators shall only declare identifiers from the identifier list, and
   // every identifier in the identifier list shall be declared.
   //
   // C89 3.7.1p5 "If a declarator includes an identifier list, only the
   // identifiers it names shall be declared in the declaration list."
   //
   // This is why we only diagnose in C99 and later. Note, the other conditions
   // listed are checked elsewhere.
   if (!FTI.hasPrototype) {
     for (int i = FTI.NumParams; i != 0; /* decrement in loop */) {
       --i;
       if (FTI.Params[i].Param == nullptr) {
         if (getLangOpts().C99) {
           SmallString<256> Code;
           llvm::raw_svector_ostream(Code)
               << "  int " << FTI.Params[i].Ident->getName() << ";\n";
           Diag(FTI.Params[i].IdentLoc, diag::ext_param_not_declared)
               << FTI.Params[i].Ident
               << FixItHint::CreateInsertion(LocAfterDecls, Code);
         }
 
         // Implicitly declare the argument as type 'int' for lack of a better
         // type.
         AttributeFactory attrs;
         DeclSpec DS(attrs);
         const char* PrevSpec; // unused
         unsigned DiagID; // unused
         DS.SetTypeSpecType(DeclSpec::TST_int, FTI.Params[i].IdentLoc, PrevSpec,
                            DiagID, Context.getPrintingPolicy());
         // Use the identifier location for the type source range.
         DS.SetRangeStart(FTI.Params[i].IdentLoc);
         DS.SetRangeEnd(FTI.Params[i].IdentLoc);
         Declarator ParamD(DS, ParsedAttributesView::none(),
                           DeclaratorContext::KNRTypeList);
         ParamD.SetIdentifier(FTI.Params[i].Ident, FTI.Params[i].IdentLoc);
         FTI.Params[i].Param = ActOnParamDeclarator(S, ParamD);
       }
     }
   }
 }
 
 Decl *
 Sema::ActOnStartOfFunctionDef(Scope *FnBodyScope, Declarator &D,
                               MultiTemplateParamsArg TemplateParameterLists,
                               SkipBodyInfo *SkipBody, FnBodyKind BodyKind) {
   assert(getCurFunctionDecl() == nullptr && "Function parsing confused");
   assert(D.isFunctionDeclarator() && "Not a function declarator!");
   Scope *ParentScope = FnBodyScope->getParent();
 
   // Check if we are in an `omp begin/end declare variant` scope. If we are, and
   // we define a non-templated function definition, we will create a declaration
   // instead (=BaseFD), and emit the definition with a mangled name afterwards.
   // The base function declaration will have the equivalent of an `omp declare
   // variant` annotation which specifies the mangled definition as a
   // specialization function under the OpenMP context defined as part of the
   // `omp begin declare variant`.
   SmallVector<FunctionDecl *, 4> Bases;
   if (LangOpts.OpenMP && isInOpenMPDeclareVariantScope())
     ActOnStartOfFunctionDefinitionInOpenMPDeclareVariantScope(
         ParentScope, D, TemplateParameterLists, Bases);
 
   D.setFunctionDefinitionKind(FunctionDefinitionKind::Definition);
   Decl *DP = HandleDeclarator(ParentScope, D, TemplateParameterLists);
   Decl *Dcl = ActOnStartOfFunctionDef(FnBodyScope, DP, SkipBody, BodyKind);
 
   if (!Bases.empty())
     ActOnFinishedFunctionDefinitionInOpenMPDeclareVariantScope(Dcl, Bases);
 
   return Dcl;
 }
 
 void Sema::ActOnFinishInlineFunctionDef(FunctionDecl *D) {
   Consumer.HandleInlineFunctionDefinition(D);
 }
 
 static bool FindPossiblePrototype(const FunctionDecl *FD,
                                   const FunctionDecl *&PossiblePrototype) {
   for (const FunctionDecl *Prev = FD->getPreviousDecl(); Prev;
        Prev = Prev->getPreviousDecl()) {
     // Ignore any declarations that occur in function or method
     // scope, because they aren't visible from the header.
     if (Prev->getLexicalDeclContext()->isFunctionOrMethod())
       continue;
 
     PossiblePrototype = Prev;
     return Prev->getType()->isFunctionProtoType();
   }
   return false;
 }
 
 static bool
 ShouldWarnAboutMissingPrototype(const FunctionDecl *FD,
                                 const FunctionDecl *&PossiblePrototype) {
   // Don't warn about invalid declarations.
   if (FD->isInvalidDecl())
     return false;
 
   // Or declarations that aren't global.
   if (!FD->isGlobal())
     return false;
 
   // Don't warn about C++ member functions.
   if (isa<CXXMethodDecl>(FD))
     return false;
 
   // Don't warn about 'main'.
   if (isa<TranslationUnitDecl>(FD->getDeclContext()->getRedeclContext()))
     if (IdentifierInfo *II = FD->getIdentifier())
       if (II->isStr("main") || II->isStr("efi_main"))
         return false;
 
   // Don't warn about inline functions.
   if (FD->isInlined())
     return false;
 
   // Don't warn about function templates.
   if (FD->getDescribedFunctionTemplate())
     return false;
 
   // Don't warn about function template specializations.
   if (FD->isFunctionTemplateSpecialization())
     return false;
 
   // Don't warn for OpenCL kernels.
   if (FD->hasAttr<OpenCLKernelAttr>())
     return false;
 
   // Don't warn on explicitly deleted functions.
   if (FD->isDeleted())
     return false;
 
   // Don't warn on implicitly local functions (such as having local-typed
   // parameters).
   if (!FD->isExternallyVisible())
     return false;
 
   // If we were able to find a potential prototype, don't warn.
   if (FindPossiblePrototype(FD, PossiblePrototype))
     return false;
 
   return true;
 }
 
 void
 Sema::CheckForFunctionRedefinition(FunctionDecl *FD,
                                    const FunctionDecl *EffectiveDefinition,
                                    SkipBodyInfo *SkipBody) {
   const FunctionDecl *Definition = EffectiveDefinition;
   if (!Definition &&
       !FD->isDefined(Definition, /*CheckForPendingFriendDefinition*/ true))
     return;
 
   if (Definition->getFriendObjectKind() != Decl::FOK_None) {
     if (FunctionDecl *OrigDef = Definition->getInstantiatedFromMemberFunction()) {
       if (FunctionDecl *OrigFD = FD->getInstantiatedFromMemberFunction()) {
         // A merged copy of the same function, instantiated as a member of
         // the same class, is OK.
         if (declaresSameEntity(OrigFD, OrigDef) &&
             declaresSameEntity(cast<Decl>(Definition->getLexicalDeclContext()),
                                cast<Decl>(FD->getLexicalDeclContext())))
           return;
       }
     }
   }
 
   if (canRedefineFunction(Definition, getLangOpts()))
     return;
 
   // Don't emit an error when this is redefinition of a typo-corrected
   // definition.
   if (TypoCorrectedFunctionDefinitions.count(Definition))
     return;
 
   // If we don't have a visible definition of the function, and it's inline or
   // a template, skip the new definition.
   if (SkipBody && !hasVisibleDefinition(Definition) &&
       (Definition->getFormalLinkage() == InternalLinkage ||
        Definition->isInlined() ||
        Definition->getDescribedFunctionTemplate() ||
        Definition->getNumTemplateParameterLists())) {
     SkipBody->ShouldSkip = true;
     SkipBody->Previous = const_cast<FunctionDecl*>(Definition);
     if (auto *TD = Definition->getDescribedFunctionTemplate())
       makeMergedDefinitionVisible(TD);
     makeMergedDefinitionVisible(const_cast<FunctionDecl*>(Definition));
     return;
   }
 
   if (getLangOpts().GNUMode && Definition->isInlineSpecified() &&
       Definition->getStorageClass() == SC_Extern)
     Diag(FD->getLocation(), diag::err_redefinition_extern_inline)
         << FD << getLangOpts().CPlusPlus;
   else
     Diag(FD->getLocation(), diag::err_redefinition) << FD;
 
   Diag(Definition->getLocation(), diag::note_previous_definition);
   FD->setInvalidDecl();
 }
 
-static void RebuildLambdaScopeInfo(CXXMethodDecl *CallOperator,
-                                   Sema &S) {
-  CXXRecordDecl *const LambdaClass = CallOperator->getParent();
+LambdaScopeInfo *Sema::RebuildLambdaScopeInfo(CXXMethodDecl *CallOperator) {
+  CXXRecordDecl *LambdaClass = CallOperator->getParent();
 
-  LambdaScopeInfo *LSI = S.PushLambdaScope();
+  LambdaScopeInfo *LSI = PushLambdaScope();
   LSI->CallOperator = CallOperator;
   LSI->Lambda = LambdaClass;
   LSI->ReturnType = CallOperator->getReturnType();
+  // This function in calls in situation where the context of the call operator
+  // is not entered, so we set AfterParameterList to false, so that
+  // `tryCaptureVariable` finds explicit captures in the appropriate context.
+  LSI->AfterParameterList = false;
   const LambdaCaptureDefault LCD = LambdaClass->getLambdaCaptureDefault();
 
   if (LCD == LCD_None)
     LSI->ImpCaptureStyle = CapturingScopeInfo::ImpCap_None;
   else if (LCD == LCD_ByCopy)
     LSI->ImpCaptureStyle = CapturingScopeInfo::ImpCap_LambdaByval;
   else if (LCD == LCD_ByRef)
     LSI->ImpCaptureStyle = CapturingScopeInfo::ImpCap_LambdaByref;
   DeclarationNameInfo DNI = CallOperator->getNameInfo();
 
   LSI->IntroducerRange = DNI.getCXXOperatorNameRange();
   LSI->Mutable = !CallOperator->isConst();
 
   // Add the captures to the LSI so they can be noted as already
   // captured within tryCaptureVar.
   auto I = LambdaClass->field_begin();
   for (const auto &C : LambdaClass->captures()) {
     if (C.capturesVariable()) {
       ValueDecl *VD = C.getCapturedVar();
       if (VD->isInitCapture())
-        S.CurrentInstantiationScope->InstantiatedLocal(VD, VD);
+        CurrentInstantiationScope->InstantiatedLocal(VD, VD);
       const bool ByRef = C.getCaptureKind() == LCK_ByRef;
       LSI->addCapture(VD, /*IsBlock*/false, ByRef,
           /*RefersToEnclosingVariableOrCapture*/true, C.getLocation(),
           /*EllipsisLoc*/C.isPackExpansion()
                          ? C.getEllipsisLoc() : SourceLocation(),
           I->getType(), /*Invalid*/false);
 
     } else if (C.capturesThis()) {
       LSI->addThisCapture(/*Nested*/ false, C.getLocation(), I->getType(),
                           C.getCaptureKind() == LCK_StarThis);
     } else {
       LSI->addVLATypeCapture(C.getLocation(), I->getCapturedVLAType(),
                              I->getType());
     }
     ++I;
   }
+  return LSI;
 }
 
 Decl *Sema::ActOnStartOfFunctionDef(Scope *FnBodyScope, Decl *D,
                                     SkipBodyInfo *SkipBody,
                                     FnBodyKind BodyKind) {
   if (!D) {
     // Parsing the function declaration failed in some way. Push on a fake scope
     // anyway so we can try to parse the function body.
     PushFunctionScope();
     PushExpressionEvaluationContext(ExprEvalContexts.back().Context);
     return D;
   }
 
   FunctionDecl *FD = nullptr;
 
   if (FunctionTemplateDecl *FunTmpl = dyn_cast<FunctionTemplateDecl>(D))
     FD = FunTmpl->getTemplatedDecl();
   else
     FD = cast<FunctionDecl>(D);
 
   // Do not push if it is a lambda because one is already pushed when building
   // the lambda in ActOnStartOfLambdaDefinition().
   if (!isLambdaCallOperator(FD))
     // [expr.const]/p14.1
     // An expression or conversion is in an immediate function context if it is
     // potentially evaluated and either: its innermost enclosing non-block scope
     // is a function parameter scope of an immediate function.
     PushExpressionEvaluationContext(
         FD->isConsteval() ? ExpressionEvaluationContext::ImmediateFunctionContext
                           : ExprEvalContexts.back().Context);
 
   // Each ExpressionEvaluationContextRecord also keeps track of whether the
   // context is nested in an immediate function context, so smaller contexts
   // that appear inside immediate functions (like variable initializers) are
   // considered to be inside an immediate function context even though by
   // themselves they are not immediate function contexts. But when a new
   // function is entered, we need to reset this tracking, since the entered
   // function might be not an immediate function.
   ExprEvalContexts.back().InImmediateFunctionContext = FD->isConsteval();
   ExprEvalContexts.back().InImmediateEscalatingFunctionContext =
       getLangOpts().CPlusPlus20 && FD->isImmediateEscalating();
 
   // Check for defining attributes before the check for redefinition.
   if (const auto *Attr = FD->getAttr<AliasAttr>()) {
     Diag(Attr->getLocation(), diag::err_alias_is_definition) << FD << 0;
     FD->dropAttr<AliasAttr>();
     FD->setInvalidDecl();
   }
   if (const auto *Attr = FD->getAttr<IFuncAttr>()) {
     Diag(Attr->getLocation(), diag::err_alias_is_definition) << FD << 1;
     FD->dropAttr<IFuncAttr>();
     FD->setInvalidDecl();
   }
   if (const auto *Attr = FD->getAttr<TargetVersionAttr>()) {
     if (!Context.getTargetInfo().hasFeature("fmv") &&
         !Attr->isDefaultVersion()) {
       // If function multi versioning disabled skip parsing function body
       // defined with non-default target_version attribute
       if (SkipBody)
         SkipBody->ShouldSkip = true;
       return nullptr;
     }
   }
 
   if (auto *Ctor = dyn_cast<CXXConstructorDecl>(FD)) {
     if (Ctor->getTemplateSpecializationKind() == TSK_ExplicitSpecialization &&
         Ctor->isDefaultConstructor() &&
         Context.getTargetInfo().getCXXABI().isMicrosoft()) {
       // If this is an MS ABI dllexport default constructor, instantiate any
       // default arguments.
       InstantiateDefaultCtorDefaultArgs(Ctor);
     }
   }
 
   // See if this is a redefinition. If 'will have body' (or similar) is already
   // set, then these checks were already performed when it was set.
   if (!FD->willHaveBody() && !FD->isLateTemplateParsed() &&
       !FD->isThisDeclarationInstantiatedFromAFriendDefinition()) {
     CheckForFunctionRedefinition(FD, nullptr, SkipBody);
 
     // If we're skipping the body, we're done. Don't enter the scope.
     if (SkipBody && SkipBody->ShouldSkip)
       return D;
   }
 
   // Mark this function as "will have a body eventually".  This lets users to
   // call e.g. isInlineDefinitionExternallyVisible while we're still parsing
   // this function.
   FD->setWillHaveBody();
 
   // If we are instantiating a generic lambda call operator, push
   // a LambdaScopeInfo onto the function stack.  But use the information
   // that's already been calculated (ActOnLambdaExpr) to prime the current
   // LambdaScopeInfo.
   // When the template operator is being specialized, the LambdaScopeInfo,
   // has to be properly restored so that tryCaptureVariable doesn't try
   // and capture any new variables. In addition when calculating potential
   // captures during transformation of nested lambdas, it is necessary to
   // have the LSI properly restored.
   if (isGenericLambdaCallOperatorSpecialization(FD)) {
     assert(inTemplateInstantiation() &&
            "There should be an active template instantiation on the stack "
            "when instantiating a generic lambda!");
-    RebuildLambdaScopeInfo(cast<CXXMethodDecl>(D), *this);
+    RebuildLambdaScopeInfo(cast<CXXMethodDecl>(D));
   } else {
     // Enter a new function scope
     PushFunctionScope();
   }
 
   // Builtin functions cannot be defined.
   if (unsigned BuiltinID = FD->getBuiltinID()) {
     if (!Context.BuiltinInfo.isPredefinedLibFunction(BuiltinID) &&
         !Context.BuiltinInfo.isPredefinedRuntimeFunction(BuiltinID)) {
       Diag(FD->getLocation(), diag::err_builtin_definition) << FD;
       FD->setInvalidDecl();
     }
   }
 
   // The return type of a function definition must be complete (C99 6.9.1p3).
   // C++23 [dcl.fct.def.general]/p2
   // The type of [...] the return for a function definition
   // shall not be a (possibly cv-qualified) class type that is incomplete
   // or abstract within the function body unless the function is deleted.
   QualType ResultType = FD->getReturnType();
   if (!ResultType->isDependentType() && !ResultType->isVoidType() &&
       !FD->isInvalidDecl() && BodyKind != FnBodyKind::Delete &&
       (RequireCompleteType(FD->getLocation(), ResultType,
                            diag::err_func_def_incomplete_result) ||
        RequireNonAbstractType(FD->getLocation(), FD->getReturnType(),
                               diag::err_abstract_type_in_decl,
                               AbstractReturnType)))
     FD->setInvalidDecl();
 
   if (FnBodyScope)
     PushDeclContext(FnBodyScope, FD);
 
   // Check the validity of our function parameters
   if (BodyKind != FnBodyKind::Delete)
     CheckParmsForFunctionDef(FD->parameters(),
                              /*CheckParameterNames=*/true);
 
   // Add non-parameter declarations already in the function to the current
   // scope.
   if (FnBodyScope) {
     for (Decl *NPD : FD->decls()) {
       auto *NonParmDecl = dyn_cast<NamedDecl>(NPD);
       if (!NonParmDecl)
         continue;
       assert(!isa<ParmVarDecl>(NonParmDecl) &&
              "parameters should not be in newly created FD yet");
 
       // If the decl has a name, make it accessible in the current scope.
       if (NonParmDecl->getDeclName())
         PushOnScopeChains(NonParmDecl, FnBodyScope, /*AddToContext=*/false);
 
       // Similarly, dive into enums and fish their constants out, making them
       // accessible in this scope.
       if (auto *ED = dyn_cast<EnumDecl>(NonParmDecl)) {
         for (auto *EI : ED->enumerators())
           PushOnScopeChains(EI, FnBodyScope, /*AddToContext=*/false);
       }
     }
   }
 
   // Introduce our parameters into the function scope
   for (auto *Param : FD->parameters()) {
     Param->setOwningFunction(FD);
 
     // If this has an identifier, add it to the scope stack.
     if (Param->getIdentifier() && FnBodyScope) {
       CheckShadow(FnBodyScope, Param);
 
       PushOnScopeChains(Param, FnBodyScope);
     }
   }
 
   // C++ [module.import/6] external definitions are not permitted in header
   // units.  Deleted and Defaulted functions are implicitly inline (but the
   // inline state is not set at this point, so check the BodyKind explicitly).
   // FIXME: Consider an alternate location for the test where the inlined()
   // state is complete.
   if (getLangOpts().CPlusPlusModules && currentModuleIsHeaderUnit() &&
       !FD->isInvalidDecl() && !FD->isInlined() &&
       BodyKind != FnBodyKind::Delete && BodyKind != FnBodyKind::Default &&
       FD->getFormalLinkage() == Linkage::ExternalLinkage &&
       !FD->isTemplated() && !FD->isTemplateInstantiation()) {
     assert(FD->isThisDeclarationADefinition());
     Diag(FD->getLocation(), diag::err_extern_def_in_header_unit);
     FD->setInvalidDecl();
   }
 
   // Ensure that the function's exception specification is instantiated.
   if (const FunctionProtoType *FPT = FD->getType()->getAs<FunctionProtoType>())
     ResolveExceptionSpec(D->getLocation(), FPT);
 
   // dllimport cannot be applied to non-inline function definitions.
   if (FD->hasAttr<DLLImportAttr>() && !FD->isInlined() &&
       !FD->isTemplateInstantiation()) {
     assert(!FD->hasAttr<DLLExportAttr>());
     Diag(FD->getLocation(), diag::err_attribute_dllimport_function_definition);
     FD->setInvalidDecl();
     return D;
   }
   // We want to attach documentation to original Decl (which might be
   // a function template).
   ActOnDocumentableDecl(D);
   if (getCurLexicalContext()->isObjCContainer() &&
       getCurLexicalContext()->getDeclKind() != Decl::ObjCCategoryImpl &&
       getCurLexicalContext()->getDeclKind() != Decl::ObjCImplementation)
     Diag(FD->getLocation(), diag::warn_function_def_in_objc_container);
 
   return D;
 }
 
 /// Given the set of return statements within a function body,
 /// compute the variables that are subject to the named return value
 /// optimization.
 ///
 /// Each of the variables that is subject to the named return value
 /// optimization will be marked as NRVO variables in the AST, and any
 /// return statement that has a marked NRVO variable as its NRVO candidate can
 /// use the named return value optimization.
 ///
 /// This function applies a very simplistic algorithm for NRVO: if every return
 /// statement in the scope of a variable has the same NRVO candidate, that
 /// candidate is an NRVO variable.
 void Sema::computeNRVO(Stmt *Body, FunctionScopeInfo *Scope) {
   ReturnStmt **Returns = Scope->Returns.data();
 
   for (unsigned I = 0, E = Scope->Returns.size(); I != E; ++I) {
     if (const VarDecl *NRVOCandidate = Returns[I]->getNRVOCandidate()) {
       if (!NRVOCandidate->isNRVOVariable())
         Returns[I]->setNRVOCandidate(nullptr);
     }
   }
 }
 
 bool Sema::canDelayFunctionBody(const Declarator &D) {
   // We can't delay parsing the body of a constexpr function template (yet).
   if (D.getDeclSpec().hasConstexprSpecifier())
     return false;
 
   // We can't delay parsing the body of a function template with a deduced
   // return type (yet).
   if (D.getDeclSpec().hasAutoTypeSpec()) {
     // If the placeholder introduces a non-deduced trailing return type,
     // we can still delay parsing it.
     if (D.getNumTypeObjects()) {
       const auto &Outer = D.getTypeObject(D.getNumTypeObjects() - 1);
       if (Outer.Kind == DeclaratorChunk::Function &&
           Outer.Fun.hasTrailingReturnType()) {
         QualType Ty = GetTypeFromParser(Outer.Fun.getTrailingReturnType());
         return Ty.isNull() || !Ty->isUndeducedType();
       }
     }
     return false;
   }
 
   return true;
 }
 
 bool Sema::canSkipFunctionBody(Decl *D) {
   // We cannot skip the body of a function (or function template) which is
   // constexpr, since we may need to evaluate its body in order to parse the
   // rest of the file.
   // We cannot skip the body of a function with an undeduced return type,
   // because any callers of that function need to know the type.
   if (const FunctionDecl *FD = D->getAsFunction()) {
     if (FD->isConstexpr())
       return false;
     // We can't simply call Type::isUndeducedType here, because inside template
     // auto can be deduced to a dependent type, which is not considered
     // "undeduced".
     if (FD->getReturnType()->getContainedDeducedType())
       return false;
   }
   return Consumer.shouldSkipFunctionBody(D);
 }
 
 Decl *Sema::ActOnSkippedFunctionBody(Decl *Decl) {
   if (!Decl)
     return nullptr;
   if (FunctionDecl *FD = Decl->getAsFunction())
     FD->setHasSkippedBody();
   else if (ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(Decl))
     MD->setHasSkippedBody();
   return Decl;
 }
 
 Decl *Sema::ActOnFinishFunctionBody(Decl *D, Stmt *BodyArg) {
   return ActOnFinishFunctionBody(D, BodyArg, false);
 }
 
 /// RAII object that pops an ExpressionEvaluationContext when exiting a function
 /// body.
 class ExitFunctionBodyRAII {
 public:
   ExitFunctionBodyRAII(Sema &S, bool IsLambda) : S(S), IsLambda(IsLambda) {}
   ~ExitFunctionBodyRAII() {
     if (!IsLambda)
       S.PopExpressionEvaluationContext();
   }
 
 private:
   Sema &S;
   bool IsLambda = false;
 };
 
 static void diagnoseImplicitlyRetainedSelf(Sema &S) {
   llvm::DenseMap<const BlockDecl *, bool> EscapeInfo;
 
   auto IsOrNestedInEscapingBlock = [&](const BlockDecl *BD) {
     if (EscapeInfo.count(BD))
       return EscapeInfo[BD];
 
     bool R = false;
     const BlockDecl *CurBD = BD;
 
     do {
       R = !CurBD->doesNotEscape();
       if (R)
         break;
       CurBD = CurBD->getParent()->getInnermostBlockDecl();
     } while (CurBD);
 
     return EscapeInfo[BD] = R;
   };
 
   // If the location where 'self' is implicitly retained is inside a escaping
   // block, emit a diagnostic.
   for (const std::pair<SourceLocation, const BlockDecl *> &P :
        S.ImplicitlyRetainedSelfLocs)
     if (IsOrNestedInEscapingBlock(P.second))
       S.Diag(P.first, diag::warn_implicitly_retains_self)
           << FixItHint::CreateInsertion(P.first, "self->");
 }
 
 Decl *Sema::ActOnFinishFunctionBody(Decl *dcl, Stmt *Body,
                                     bool IsInstantiation) {
   FunctionScopeInfo *FSI = getCurFunction();
   FunctionDecl *FD = dcl ? dcl->getAsFunction() : nullptr;
 
   if (FSI->UsesFPIntrin && FD && !FD->hasAttr<StrictFPAttr>())
     FD->addAttr(StrictFPAttr::CreateImplicit(Context));
 
   sema::AnalysisBasedWarnings::Policy WP = AnalysisWarnings.getDefaultPolicy();
   sema::AnalysisBasedWarnings::Policy *ActivePolicy = nullptr;
 
   if (getLangOpts().Coroutines && FSI->isCoroutine())
     CheckCompletedCoroutineBody(FD, Body);
 
   {
     // Do not call PopExpressionEvaluationContext() if it is a lambda because
     // one is already popped when finishing the lambda in BuildLambdaExpr().
     // This is meant to pop the context added in ActOnStartOfFunctionDef().
     ExitFunctionBodyRAII ExitRAII(*this, isLambdaCallOperator(FD));
     if (FD) {
       FD->setBody(Body);
       FD->setWillHaveBody(false);
       CheckImmediateEscalatingFunctionDefinition(FD, FSI);
 
       if (getLangOpts().CPlusPlus14) {
         if (!FD->isInvalidDecl() && Body && !FD->isDependentContext() &&
             FD->getReturnType()->isUndeducedType()) {
           // For a function with a deduced result type to return void,
           // the result type as written must be 'auto' or 'decltype(auto)',
           // possibly cv-qualified or constrained, but not ref-qualified.
           if (!FD->getReturnType()->getAs<AutoType>()) {
             Diag(dcl->getLocation(), diag::err_auto_fn_no_return_but_not_auto)
                 << FD->getReturnType();
             FD->setInvalidDecl();
           } else {
             // Falling off the end of the function is the same as 'return;'.
             Expr *Dummy = nullptr;
             if (DeduceFunctionTypeFromReturnExpr(
                     FD, dcl->getLocation(), Dummy,
                     FD->getReturnType()->getAs<AutoType>()))
               FD->setInvalidDecl();
           }
         }
       } else if (getLangOpts().CPlusPlus11 && isLambdaCallOperator(FD)) {
         // In C++11, we don't use 'auto' deduction rules for lambda call
         // operators because we don't support return type deduction.
         auto *LSI = getCurLambda();
         if (LSI->HasImplicitReturnType) {
           deduceClosureReturnType(*LSI);
 
           // C++11 [expr.prim.lambda]p4:
           //   [...] if there are no return statements in the compound-statement
           //   [the deduced type is] the type void
           QualType RetType =
               LSI->ReturnType.isNull() ? Context.VoidTy : LSI->ReturnType;
 
           // Update the return type to the deduced type.
           const auto *Proto = FD->getType()->castAs<FunctionProtoType>();
           FD->setType(Context.getFunctionType(RetType, Proto->getParamTypes(),
                                               Proto->getExtProtoInfo()));
         }
       }
 
       // If the function implicitly returns zero (like 'main') or is naked,
       // don't complain about missing return statements.
       if (FD->hasImplicitReturnZero() || FD->hasAttr<NakedAttr>())
         WP.disableCheckFallThrough();
 
       // MSVC permits the use of pure specifier (=0) on function definition,
       // defined at class scope, warn about this non-standard construct.
       if (getLangOpts().MicrosoftExt && FD->isPure() && !FD->isOutOfLine())
         Diag(FD->getLocation(), diag::ext_pure_function_definition);
 
       if (!FD->isInvalidDecl()) {
         // Don't diagnose unused parameters of defaulted, deleted or naked
         // functions.
         if (!FD->isDeleted() && !FD->isDefaulted() && !FD->hasSkippedBody() &&
             !FD->hasAttr<NakedAttr>())
           DiagnoseUnusedParameters(FD->parameters());
         DiagnoseSizeOfParametersAndReturnValue(FD->parameters(),
                                                FD->getReturnType(), FD);
 
         // If this is a structor, we need a vtable.
         if (CXXConstructorDecl *Constructor = dyn_cast<CXXConstructorDecl>(FD))
           MarkVTableUsed(FD->getLocation(), Constructor->getParent());
         else if (CXXDestructorDecl *Destructor =
                      dyn_cast<CXXDestructorDecl>(FD))
           MarkVTableUsed(FD->getLocation(), Destructor->getParent());
 
         // Try to apply the named return value optimization. We have to check
         // if we can do this here because lambdas keep return statements around
         // to deduce an implicit return type.
         if (FD->getReturnType()->isRecordType() &&
             (!getLangOpts().CPlusPlus || !FD->isDependentContext()))
           computeNRVO(Body, FSI);
       }
 
       // GNU warning -Wmissing-prototypes:
       //   Warn if a global function is defined without a previous
       //   prototype declaration. This warning is issued even if the
       //   definition itself provides a prototype. The aim is to detect
       //   global functions that fail to be declared in header files.
       const FunctionDecl *PossiblePrototype = nullptr;
       if (ShouldWarnAboutMissingPrototype(FD, PossiblePrototype)) {
         Diag(FD->getLocation(), diag::warn_missing_prototype) << FD;
 
         if (PossiblePrototype) {
           // We found a declaration that is not a prototype,
           // but that could be a zero-parameter prototype
           if (TypeSourceInfo *TI = PossiblePrototype->getTypeSourceInfo()) {
             TypeLoc TL = TI->getTypeLoc();
             if (FunctionNoProtoTypeLoc FTL = TL.getAs<FunctionNoProtoTypeLoc>())
               Diag(PossiblePrototype->getLocation(),
                    diag::note_declaration_not_a_prototype)
                   << (FD->getNumParams() != 0)
                   << (FD->getNumParams() == 0 ? FixItHint::CreateInsertion(
                                                     FTL.getRParenLoc(), "void")
                                               : FixItHint{});
           }
         } else {
           // Returns true if the token beginning at this Loc is `const`.
           auto isLocAtConst = [&](SourceLocation Loc, const SourceManager &SM,
                                   const LangOptions &LangOpts) {
             std::pair<FileID, unsigned> LocInfo = SM.getDecomposedLoc(Loc);
             if (LocInfo.first.isInvalid())
               return false;
 
             bool Invalid = false;
             StringRef Buffer = SM.getBufferData(LocInfo.first, &Invalid);
             if (Invalid)
               return false;
 
             if (LocInfo.second > Buffer.size())
               return false;
 
             const char *LexStart = Buffer.data() + LocInfo.second;
             StringRef StartTok(LexStart, Buffer.size() - LocInfo.second);
 
             return StartTok.consume_front("const") &&
                    (StartTok.empty() || isWhitespace(StartTok[0]) ||
                     StartTok.startswith("/*") || StartTok.startswith("//"));
           };
 
           auto findBeginLoc = [&]() {
             // If the return type has `const` qualifier, we want to insert
             // `static` before `const` (and not before the typename).
             if ((FD->getReturnType()->isAnyPointerType() &&
                  FD->getReturnType()->getPointeeType().isConstQualified()) ||
                 FD->getReturnType().isConstQualified()) {
               // But only do this if we can determine where the `const` is.
 
               if (isLocAtConst(FD->getBeginLoc(), getSourceManager(),
                                getLangOpts()))
 
                 return FD->getBeginLoc();
             }
             return FD->getTypeSpecStartLoc();
           };
           Diag(FD->getTypeSpecStartLoc(),
                diag::note_static_for_internal_linkage)
               << /* function */ 1
               << (FD->getStorageClass() == SC_None
                       ? FixItHint::CreateInsertion(findBeginLoc(), "static ")
                       : FixItHint{});
         }
       }
 
       // We might not have found a prototype because we didn't wish to warn on
       // the lack of a missing prototype. Try again without the checks for
       // whether we want to warn on the missing prototype.
       if (!PossiblePrototype)
         (void)FindPossiblePrototype(FD, PossiblePrototype);
 
       // If the function being defined does not have a prototype, then we may
       // need to diagnose it as changing behavior in C2x because we now know
       // whether the function accepts arguments or not. This only handles the
       // case where the definition has no prototype but does have parameters
       // and either there is no previous potential prototype, or the previous
       // potential prototype also has no actual prototype. This handles cases
       // like:
       //   void f(); void f(a) int a; {}
       //   void g(a) int a; {}
       // See MergeFunctionDecl() for other cases of the behavior change
       // diagnostic. See GetFullTypeForDeclarator() for handling of a function
       // type without a prototype.
       if (!FD->hasWrittenPrototype() && FD->getNumParams() != 0 &&
           (!PossiblePrototype || (!PossiblePrototype->hasWrittenPrototype() &&
                                   !PossiblePrototype->isImplicit()))) {
         // The function definition has parameters, so this will change behavior
         // in C2x. If there is a possible prototype, it comes before the
         // function definition.
         // FIXME: The declaration may have already been diagnosed as being
         // deprecated in GetFullTypeForDeclarator() if it had no arguments, but
         // there's no way to test for the "changes behavior" condition in
         // SemaType.cpp when forming the declaration's function type. So, we do
         // this awkward dance instead.
         //
         // If we have a possible prototype and it declares a function with a
         // prototype, we don't want to diagnose it; if we have a possible
         // prototype and it has no prototype, it may have already been
         // diagnosed in SemaType.cpp as deprecated depending on whether
         // -Wstrict-prototypes is enabled. If we already warned about it being
         // deprecated, add a note that it also changes behavior. If we didn't
         // warn about it being deprecated (because the diagnostic is not
         // enabled), warn now that it is deprecated and changes behavior.
 
         // This K&R C function definition definitely changes behavior in C2x,
         // so diagnose it.
         Diag(FD->getLocation(), diag::warn_non_prototype_changes_behavior)
             << /*definition*/ 1 << /* not supported in C2x */ 0;
 
         // If we have a possible prototype for the function which is a user-
         // visible declaration, we already tested that it has no prototype.
         // This will change behavior in C2x. This gets a warning rather than a
         // note because it's the same behavior-changing problem as with the
         // definition.
         if (PossiblePrototype)
           Diag(PossiblePrototype->getLocation(),
                diag::warn_non_prototype_changes_behavior)
               << /*declaration*/ 0 << /* conflicting */ 1 << /*subsequent*/ 1
               << /*definition*/ 1;
       }
 
       // Warn on CPUDispatch with an actual body.
       if (FD->isMultiVersion() && FD->hasAttr<CPUDispatchAttr>() && Body)
         if (const auto *CmpndBody = dyn_cast<CompoundStmt>(Body))
           if (!CmpndBody->body_empty())
             Diag(CmpndBody->body_front()->getBeginLoc(),
                  diag::warn_dispatch_body_ignored);
 
       if (auto *MD = dyn_cast<CXXMethodDecl>(FD)) {
         const CXXMethodDecl *KeyFunction;
         if (MD->isOutOfLine() && (MD = MD->getCanonicalDecl()) &&
             MD->isVirtual() &&
             (KeyFunction = Context.getCurrentKeyFunction(MD->getParent())) &&
             MD == KeyFunction->getCanonicalDecl()) {
           // Update the key-function state if necessary for this ABI.
           if (FD->isInlined() &&
               !Context.getTargetInfo().getCXXABI().canKeyFunctionBeInline()) {
             Context.setNonKeyFunction(MD);
 
             // If the newly-chosen key function is already defined, then we
             // need to mark the vtable as used retroactively.
             KeyFunction = Context.getCurrentKeyFunction(MD->getParent());
             const FunctionDecl *Definition;
             if (KeyFunction && KeyFunction->isDefined(Definition))
               MarkVTableUsed(Definition->getLocation(), MD->getParent(), true);
           } else {
             // We just defined they key function; mark the vtable as used.
             MarkVTableUsed(FD->getLocation(), MD->getParent(), true);
           }
         }
       }
 
       assert(
           (FD == getCurFunctionDecl() || getCurLambda()->CallOperator == FD) &&
           "Function parsing confused");
     } else if (ObjCMethodDecl *MD = dyn_cast_or_null<ObjCMethodDecl>(dcl)) {
       assert(MD == getCurMethodDecl() && "Method parsing confused");
       MD->setBody(Body);
       if (!MD->isInvalidDecl()) {
         DiagnoseSizeOfParametersAndReturnValue(MD->parameters(),
                                                MD->getReturnType(), MD);
 
         if (Body)
           computeNRVO(Body, FSI);
       }
       if (FSI->ObjCShouldCallSuper) {
         Diag(MD->getEndLoc(), diag::warn_objc_missing_super_call)
             << MD->getSelector().getAsString();
         FSI->ObjCShouldCallSuper = false;
       }
       if (FSI->ObjCWarnForNoDesignatedInitChain) {
         const ObjCMethodDecl *InitMethod = nullptr;
         bool isDesignated =
             MD->isDesignatedInitializerForTheInterface(&InitMethod);
         assert(isDesignated && InitMethod);
         (void)isDesignated;
 
         auto superIsNSObject = [&](const ObjCMethodDecl *MD) {
           auto IFace = MD->getClassInterface();
           if (!IFace)
             return false;
           auto SuperD = IFace->getSuperClass();
           if (!SuperD)
             return false;
           return SuperD->getIdentifier() ==
                  NSAPIObj->getNSClassId(NSAPI::ClassId_NSObject);
         };
         // Don't issue this warning for unavailable inits or direct subclasses
         // of NSObject.
         if (!MD->isUnavailable() && !superIsNSObject(MD)) {
           Diag(MD->getLocation(),
                diag::warn_objc_designated_init_missing_super_call);
           Diag(InitMethod->getLocation(),
                diag::note_objc_designated_init_marked_here);
         }
         FSI->ObjCWarnForNoDesignatedInitChain = false;
       }
       if (FSI->ObjCWarnForNoInitDelegation) {
         // Don't issue this warning for unavaialable inits.
         if (!MD->isUnavailable())
           Diag(MD->getLocation(),
                diag::warn_objc_secondary_init_missing_init_call);
         FSI->ObjCWarnForNoInitDelegation = false;
       }
 
       diagnoseImplicitlyRetainedSelf(*this);
     } else {
       // Parsing the function declaration failed in some way. Pop the fake scope
       // we pushed on.
       PopFunctionScopeInfo(ActivePolicy, dcl);
       return nullptr;
     }
 
     if (Body && FSI->HasPotentialAvailabilityViolations)
       DiagnoseUnguardedAvailabilityViolations(dcl);
 
     assert(!FSI->ObjCShouldCallSuper &&
            "This should only be set for ObjC methods, which should have been "
            "handled in the block above.");
 
     // Verify and clean out per-function state.
     if (Body && (!FD || !FD->isDefaulted())) {
       // C++ constructors that have function-try-blocks can't have return
       // statements in the handlers of that block. (C++ [except.handle]p14)
       // Verify this.
       if (FD && isa<CXXConstructorDecl>(FD) && isa<CXXTryStmt>(Body))
         DiagnoseReturnInConstructorExceptionHandler(cast<CXXTryStmt>(Body));
 
       // Verify that gotos and switch cases don't jump into scopes illegally.
       if (FSI->NeedsScopeChecking() && !PP.isCodeCompletionEnabled())
         DiagnoseInvalidJumps(Body);
 
       if (CXXDestructorDecl *Destructor = dyn_cast<CXXDestructorDecl>(dcl)) {
         if (!Destructor->getParent()->isDependentType())
           CheckDestructor(Destructor);
 
         MarkBaseAndMemberDestructorsReferenced(Destructor->getLocation(),
                                                Destructor->getParent());
       }
 
       // If any errors have occurred, clear out any temporaries that may have
       // been leftover. This ensures that these temporaries won't be picked up
       // for deletion in some later function.
       if (hasUncompilableErrorOccurred() ||
           getDiagnostics().getSuppressAllDiagnostics()) {
         DiscardCleanupsInEvaluationContext();
       }
       if (!hasUncompilableErrorOccurred() && !isa<FunctionTemplateDecl>(dcl)) {
         // Since the body is valid, issue any analysis-based warnings that are
         // enabled.
         ActivePolicy = &WP;
       }
 
       if (!IsInstantiation && FD && FD->isConstexpr() && !FD->isInvalidDecl() &&
           !CheckConstexprFunctionDefinition(FD, CheckConstexprKind::Diagnose))
         FD->setInvalidDecl();
 
       if (FD && FD->hasAttr<NakedAttr>()) {
         for (const Stmt *S : Body->children()) {
           // Allow local register variables without initializer as they don't
           // require prologue.
           bool RegisterVariables = false;
           if (auto *DS = dyn_cast<DeclStmt>(S)) {
             for (const auto *Decl : DS->decls()) {
               if (const auto *Var = dyn_cast<VarDecl>(Decl)) {
                 RegisterVariables =
                     Var->hasAttr<AsmLabelAttr>() && !Var->hasInit();
                 if (!RegisterVariables)
                   break;
               }
             }
           }
           if (RegisterVariables)
             continue;
           if (!isa<AsmStmt>(S) && !isa<NullStmt>(S)) {
             Diag(S->getBeginLoc(), diag::err_non_asm_stmt_in_naked_function);
             Diag(FD->getAttr<NakedAttr>()->getLocation(), diag::note_attribute);
             FD->setInvalidDecl();
             break;
           }
         }
       }
 
       assert(ExprCleanupObjects.size() ==
                  ExprEvalContexts.back().NumCleanupObjects &&
              "Leftover temporaries in function");
       assert(!Cleanup.exprNeedsCleanups() &&
              "Unaccounted cleanups in function");
       assert(MaybeODRUseExprs.empty() &&
              "Leftover expressions for odr-use checking");
     }
   } // Pops the ExitFunctionBodyRAII scope, which needs to happen before we pop
     // the declaration context below. Otherwise, we're unable to transform
     // 'this' expressions when transforming immediate context functions.
 
   if (!IsInstantiation)
     PopDeclContext();
 
   PopFunctionScopeInfo(ActivePolicy, dcl);
   // If any errors have occurred, clear out any temporaries that may have
   // been leftover. This ensures that these temporaries won't be picked up for
   // deletion in some later function.
   if (hasUncompilableErrorOccurred()) {
     DiscardCleanupsInEvaluationContext();
   }
 
   if (FD && ((LangOpts.OpenMP && (LangOpts.OpenMPIsTargetDevice ||
                                   !LangOpts.OMPTargetTriples.empty())) ||
              LangOpts.CUDA || LangOpts.SYCLIsDevice)) {
     auto ES = getEmissionStatus(FD);
     if (ES == Sema::FunctionEmissionStatus::Emitted ||
         ES == Sema::FunctionEmissionStatus::Unknown)
       DeclsToCheckForDeferredDiags.insert(FD);
   }
 
   if (FD && !FD->isDeleted())
     checkTypeSupport(FD->getType(), FD->getLocation(), FD);
 
   return dcl;
 }
 
 /// When we finish delayed parsing of an attribute, we must attach it to the
 /// relevant Decl.
 void Sema::ActOnFinishDelayedAttribute(Scope *S, Decl *D,
                                        ParsedAttributes &Attrs) {
   // Always attach attributes to the underlying decl.
   if (TemplateDecl *TD = dyn_cast<TemplateDecl>(D))
     D = TD->getTemplatedDecl();
   ProcessDeclAttributeList(S, D, Attrs);
 
   if (CXXMethodDecl *Method = dyn_cast_or_null<CXXMethodDecl>(D))
     if (Method->isStatic())
       checkThisInStaticMemberFunctionAttributes(Method);
 }
 
 /// ImplicitlyDefineFunction - An undeclared identifier was used in a function
 /// call, forming a call to an implicitly defined function (per C99 6.5.1p2).
 NamedDecl *Sema::ImplicitlyDefineFunction(SourceLocation Loc,
                                           IdentifierInfo &II, Scope *S) {
   // It is not valid to implicitly define a function in C2x.
   assert(LangOpts.implicitFunctionsAllowed() &&
          "Implicit function declarations aren't allowed in this language mode");
 
   // Find the scope in which the identifier is injected and the corresponding
   // DeclContext.
   // FIXME: C89 does not say what happens if there is no enclosing block scope.
   // In that case, we inject the declaration into the translation unit scope
   // instead.
   Scope *BlockScope = S;
   while (!BlockScope->isCompoundStmtScope() && BlockScope->getParent())
     BlockScope = BlockScope->getParent();
 
   // Loop until we find a DeclContext that is either a function/method or the
   // translation unit, which are the only two valid places to implicitly define
   // a function. This avoids accidentally defining the function within a tag
   // declaration, for example.
   Scope *ContextScope = BlockScope;
   while (!ContextScope->getEntity() ||
          (!ContextScope->getEntity()->isFunctionOrMethod() &&
           !ContextScope->getEntity()->isTranslationUnit()))
     ContextScope = ContextScope->getParent();
   ContextRAII SavedContext(*this, ContextScope->getEntity());
 
   // Before we produce a declaration for an implicitly defined
   // function, see whether there was a locally-scoped declaration of
   // this name as a function or variable. If so, use that
   // (non-visible) declaration, and complain about it.
   NamedDecl *ExternCPrev = findLocallyScopedExternCDecl(&II);
   if (ExternCPrev) {
     // We still need to inject the function into the enclosing block scope so
     // that later (non-call) uses can see it.
     PushOnScopeChains(ExternCPrev, BlockScope, /*AddToContext*/false);
 
     // C89 footnote 38:
     //   If in fact it is not defined as having type "function returning int",
     //   the behavior is undefined.
     if (!isa<FunctionDecl>(ExternCPrev) ||
         !Context.typesAreCompatible(
             cast<FunctionDecl>(ExternCPrev)->getType(),
             Context.getFunctionNoProtoType(Context.IntTy))) {
       Diag(Loc, diag::ext_use_out_of_scope_declaration)
           << ExternCPrev << !getLangOpts().C99;
       Diag(ExternCPrev->getLocation(), diag::note_previous_declaration);
       return ExternCPrev;
     }
   }
 
   // Extension in C99 (defaults to error). Legal in C89, but warn about it.
   unsigned diag_id;
   if (II.getName().startswith("__builtin_"))
     diag_id = diag::warn_builtin_unknown;
   // OpenCL v2.0 s6.9.u - Implicit function declaration is not supported.
   else if (getLangOpts().C99)
     diag_id = diag::ext_implicit_function_decl_c99;
   else
     diag_id = diag::warn_implicit_function_decl;
 
   TypoCorrection Corrected;
   // Because typo correction is expensive, only do it if the implicit
   // function declaration is going to be treated as an error.
   //
   // Perform the correction before issuing the main diagnostic, as some
   // consumers use typo-correction callbacks to enhance the main diagnostic.
   if (S && !ExternCPrev &&
       (Diags.getDiagnosticLevel(diag_id, Loc) >= DiagnosticsEngine::Error)) {
     DeclFilterCCC<FunctionDecl> CCC{};
     Corrected = CorrectTypo(DeclarationNameInfo(&II, Loc), LookupOrdinaryName,
                             S, nullptr, CCC, CTK_NonError);
   }
 
   Diag(Loc, diag_id) << &II;
   if (Corrected) {
     // If the correction is going to suggest an implicitly defined function,
     // skip the correction as not being a particularly good idea.
     bool Diagnose = true;
     if (const auto *D = Corrected.getCorrectionDecl())
       Diagnose = !D->isImplicit();
     if (Diagnose)
       diagnoseTypo(Corrected, PDiag(diag::note_function_suggestion),
                    /*ErrorRecovery*/ false);
   }
 
   // If we found a prior declaration of this function, don't bother building
   // another one. We've already pushed that one into scope, so there's nothing
   // more to do.
   if (ExternCPrev)
     return ExternCPrev;
 
   // Set a Declarator for the implicit definition: int foo();
   const char *Dummy;
   AttributeFactory attrFactory;
   DeclSpec DS(attrFactory);
   unsigned DiagID;
   bool Error = DS.SetTypeSpecType(DeclSpec::TST_int, Loc, Dummy, DiagID,
                                   Context.getPrintingPolicy());
   (void)Error; // Silence warning.
   assert(!Error && "Error setting up implicit decl!");
   SourceLocation NoLoc;
   Declarator D(DS, ParsedAttributesView::none(), DeclaratorContext::Block);
   D.AddTypeInfo(DeclaratorChunk::getFunction(/*HasProto=*/false,
                                              /*IsAmbiguous=*/false,
                                              /*LParenLoc=*/NoLoc,
                                              /*Params=*/nullptr,
                                              /*NumParams=*/0,
                                              /*EllipsisLoc=*/NoLoc,
                                              /*RParenLoc=*/NoLoc,
                                              /*RefQualifierIsLvalueRef=*/true,
                                              /*RefQualifierLoc=*/NoLoc,
                                              /*MutableLoc=*/NoLoc, EST_None,
                                              /*ESpecRange=*/SourceRange(),
                                              /*Exceptions=*/nullptr,
                                              /*ExceptionRanges=*/nullptr,
                                              /*NumExceptions=*/0,
                                              /*NoexceptExpr=*/nullptr,
                                              /*ExceptionSpecTokens=*/nullptr,
                                              /*DeclsInPrototype=*/std::nullopt,
                                              Loc, Loc, D),
                 std::move(DS.getAttributes()), SourceLocation());
   D.SetIdentifier(&II, Loc);
 
   // Insert this function into the enclosing block scope.
   FunctionDecl *FD = cast<FunctionDecl>(ActOnDeclarator(BlockScope, D));
   FD->setImplicit();
 
   AddKnownFunctionAttributes(FD);
 
   return FD;
 }
 
 /// If this function is a C++ replaceable global allocation function
 /// (C++2a [basic.stc.dynamic.allocation], C++2a [new.delete]),
 /// adds any function attributes that we know a priori based on the standard.
 ///
 /// We need to check for duplicate attributes both here and where user-written
 /// attributes are applied to declarations.
 void Sema::AddKnownFunctionAttributesForReplaceableGlobalAllocationFunction(
     FunctionDecl *FD) {
   if (FD->isInvalidDecl())
     return;
 
   if (FD->getDeclName().getCXXOverloadedOperator() != OO_New &&
       FD->getDeclName().getCXXOverloadedOperator() != OO_Array_New)
     return;
 
   std::optional<unsigned> AlignmentParam;
   bool IsNothrow = false;
   if (!FD->isReplaceableGlobalAllocationFunction(&AlignmentParam, &IsNothrow))
     return;
 
   // C++2a [basic.stc.dynamic.allocation]p4:
   //   An allocation function that has a non-throwing exception specification
   //   indicates failure by returning a null pointer value. Any other allocation
   //   function never returns a null pointer value and indicates failure only by
   //   throwing an exception [...]
   //
   // However, -fcheck-new invalidates this possible assumption, so don't add
   // NonNull when that is enabled.
   if (!IsNothrow && !FD->hasAttr<ReturnsNonNullAttr>() &&
       !getLangOpts().CheckNew)
     FD->addAttr(ReturnsNonNullAttr::CreateImplicit(Context, FD->getLocation()));
 
   // C++2a [basic.stc.dynamic.allocation]p2:
   //   An allocation function attempts to allocate the requested amount of
   //   storage. [...] If the request succeeds, the value returned by a
   //   replaceable allocation function is a [...] pointer value p0 different
   //   from any previously returned value p1 [...]
   //
   // However, this particular information is being added in codegen,
   // because there is an opt-out switch for it (-fno-assume-sane-operator-new)
 
   // C++2a [basic.stc.dynamic.allocation]p2:
   //   An allocation function attempts to allocate the requested amount of
   //   storage. If it is successful, it returns the address of the start of a
   //   block of storage whose length in bytes is at least as large as the
   //   requested size.
   if (!FD->hasAttr<AllocSizeAttr>()) {
     FD->addAttr(AllocSizeAttr::CreateImplicit(
         Context, /*ElemSizeParam=*/ParamIdx(1, FD),
         /*NumElemsParam=*/ParamIdx(), FD->getLocation()));
   }
 
   // C++2a [basic.stc.dynamic.allocation]p3:
   //   For an allocation function [...], the pointer returned on a successful
   //   call shall represent the address of storage that is aligned as follows:
   //   (3.1) If the allocation function takes an argument of type
   //         std​::​align_­val_­t, the storage will have the alignment
   //         specified by the value of this argument.
   if (AlignmentParam && !FD->hasAttr<AllocAlignAttr>()) {
     FD->addAttr(AllocAlignAttr::CreateImplicit(
         Context, ParamIdx(*AlignmentParam, FD), FD->getLocation()));
   }
 
   // FIXME:
   // C++2a [basic.stc.dynamic.allocation]p3:
   //   For an allocation function [...], the pointer returned on a successful
   //   call shall represent the address of storage that is aligned as follows:
   //   (3.2) Otherwise, if the allocation function is named operator new[],
   //         the storage is aligned for any object that does not have
   //         new-extended alignment ([basic.align]) and is no larger than the
   //         requested size.
   //   (3.3) Otherwise, the storage is aligned for any object that does not
   //         have new-extended alignment and is of the requested size.
 }
 
 /// Adds any function attributes that we know a priori based on
 /// the declaration of this function.
 ///
 /// These attributes can apply both to implicitly-declared builtins
 /// (like __builtin___printf_chk) or to library-declared functions
 /// like NSLog or printf.
 ///
 /// We need to check for duplicate attributes both here and where user-written
 /// attributes are applied to declarations.
 void Sema::AddKnownFunctionAttributes(FunctionDecl *FD) {
   if (FD->isInvalidDecl())
     return;
 
   // If this is a built-in function, map its builtin attributes to
   // actual attributes.
   if (unsigned BuiltinID = FD->getBuiltinID()) {
     // Handle printf-formatting attributes.
     unsigned FormatIdx;
     bool HasVAListArg;
     if (Context.BuiltinInfo.isPrintfLike(BuiltinID, FormatIdx, HasVAListArg)) {
       if (!FD->hasAttr<FormatAttr>()) {
         const char *fmt = "printf";
         unsigned int NumParams = FD->getNumParams();
         if (FormatIdx < NumParams && // NumParams may be 0 (e.g. vfprintf)
             FD->getParamDecl(FormatIdx)->getType()->isObjCObjectPointerType())
           fmt = "NSString";
         FD->addAttr(FormatAttr::CreateImplicit(Context,
                                                &Context.Idents.get(fmt),
                                                FormatIdx+1,
                                                HasVAListArg ? 0 : FormatIdx+2,
                                                FD->getLocation()));
       }
     }
     if (Context.BuiltinInfo.isScanfLike(BuiltinID, FormatIdx,
                                              HasVAListArg)) {
      if (!FD->hasAttr<FormatAttr>())
        FD->addAttr(FormatAttr::CreateImplicit(Context,
                                               &Context.Idents.get("scanf"),
                                               FormatIdx+1,
                                               HasVAListArg ? 0 : FormatIdx+2,
                                               FD->getLocation()));
     }
 
     // Handle automatically recognized callbacks.
     SmallVector<int, 4> Encoding;
     if (!FD->hasAttr<CallbackAttr>() &&
         Context.BuiltinInfo.performsCallback(BuiltinID, Encoding))
       FD->addAttr(CallbackAttr::CreateImplicit(
           Context, Encoding.data(), Encoding.size(), FD->getLocation()));
 
     // Mark const if we don't care about errno and/or floating point exceptions
     // that are the only thing preventing the function from being const. This
     // allows IRgen to use LLVM intrinsics for such functions.
     bool NoExceptions =
         getLangOpts().getDefaultExceptionMode() == LangOptions::FPE_Ignore;
     bool ConstWithoutErrnoAndExceptions =
         Context.BuiltinInfo.isConstWithoutErrnoAndExceptions(BuiltinID);
     bool ConstWithoutExceptions =
         Context.BuiltinInfo.isConstWithoutExceptions(BuiltinID);
     if (!FD->hasAttr<ConstAttr>() &&
         (ConstWithoutErrnoAndExceptions || ConstWithoutExceptions) &&
         (!ConstWithoutErrnoAndExceptions ||
          (!getLangOpts().MathErrno && NoExceptions)) &&
         (!ConstWithoutExceptions || NoExceptions))
       FD->addAttr(ConstAttr::CreateImplicit(Context, FD->getLocation()));
 
     // We make "fma" on GNU or Windows const because we know it does not set
     // errno in those environments even though it could set errno based on the
     // C standard.
     const llvm::Triple &Trip = Context.getTargetInfo().getTriple();
     if ((Trip.isGNUEnvironment() || Trip.isOSMSVCRT()) &&
         !FD->hasAttr<ConstAttr>()) {
       switch (BuiltinID) {
       case Builtin::BI__builtin_fma:
       case Builtin::BI__builtin_fmaf:
       case Builtin::BI__builtin_fmal:
       case Builtin::BIfma:
       case Builtin::BIfmaf:
       case Builtin::BIfmal:
         FD->addAttr(ConstAttr::CreateImplicit(Context, FD->getLocation()));
         break;
       default:
         break;
       }
     }
 
     if (Context.BuiltinInfo.isReturnsTwice(BuiltinID) &&
         !FD->hasAttr<ReturnsTwiceAttr>())
       FD->addAttr(ReturnsTwiceAttr::CreateImplicit(Context,
                                          FD->getLocation()));
     if (Context.BuiltinInfo.isNoThrow(BuiltinID) && !FD->hasAttr<NoThrowAttr>())
       FD->addAttr(NoThrowAttr::CreateImplicit(Context, FD->getLocation()));
     if (Context.BuiltinInfo.isPure(BuiltinID) && !FD->hasAttr<PureAttr>())
       FD->addAttr(PureAttr::CreateImplicit(Context, FD->getLocation()));
     if (Context.BuiltinInfo.isConst(BuiltinID) && !FD->hasAttr<ConstAttr>())
       FD->addAttr(ConstAttr::CreateImplicit(Context, FD->getLocation()));
     if (getLangOpts().CUDA && Context.BuiltinInfo.isTSBuiltin(BuiltinID) &&
         !FD->hasAttr<CUDADeviceAttr>() && !FD->hasAttr<CUDAHostAttr>()) {
       // Add the appropriate attribute, depending on the CUDA compilation mode
       // and which target the builtin belongs to. For example, during host
       // compilation, aux builtins are __device__, while the rest are __host__.
       if (getLangOpts().CUDAIsDevice !=
           Context.BuiltinInfo.isAuxBuiltinID(BuiltinID))
         FD->addAttr(CUDADeviceAttr::CreateImplicit(Context, FD->getLocation()));
       else
         FD->addAttr(CUDAHostAttr::CreateImplicit(Context, FD->getLocation()));
     }
 
     // Add known guaranteed alignment for allocation functions.
     switch (BuiltinID) {
     case Builtin::BImemalign:
     case Builtin::BIaligned_alloc:
       if (!FD->hasAttr<AllocAlignAttr>())
         FD->addAttr(AllocAlignAttr::CreateImplicit(Context, ParamIdx(1, FD),
                                                    FD->getLocation()));
       break;
     default:
       break;
     }
 
     // Add allocsize attribute for allocation functions.
     switch (BuiltinID) {
     case Builtin::BIcalloc:
       FD->addAttr(AllocSizeAttr::CreateImplicit(
           Context, ParamIdx(1, FD), ParamIdx(2, FD), FD->getLocation()));
       break;
     case Builtin::BImemalign:
     case Builtin::BIaligned_alloc:
     case Builtin::BIrealloc:
       FD->addAttr(AllocSizeAttr::CreateImplicit(Context, ParamIdx(2, FD),
                                                 ParamIdx(), FD->getLocation()));
       break;
     case Builtin::BImalloc:
       FD->addAttr(AllocSizeAttr::CreateImplicit(Context, ParamIdx(1, FD),
                                                 ParamIdx(), FD->getLocation()));
       break;
     default:
       break;
     }
 
     // Add lifetime attribute to std::move, std::fowrard et al.
     switch (BuiltinID) {
     case Builtin::BIaddressof:
     case Builtin::BI__addressof:
     case Builtin::BI__builtin_addressof:
     case Builtin::BIas_const:
     case Builtin::BIforward:
     case Builtin::BIforward_like:
     case Builtin::BImove:
     case Builtin::BImove_if_noexcept:
       if (ParmVarDecl *P = FD->getParamDecl(0u);
           !P->hasAttr<LifetimeBoundAttr>())
         P->addAttr(
             LifetimeBoundAttr::CreateImplicit(Context, FD->getLocation()));
       break;
     default:
       break;
     }
   }
 
   AddKnownFunctionAttributesForReplaceableGlobalAllocationFunction(FD);
 
   // If C++ exceptions are enabled but we are told extern "C" functions cannot
   // throw, add an implicit nothrow attribute to any extern "C" function we come
   // across.
   if (getLangOpts().CXXExceptions && getLangOpts().ExternCNoUnwind &&
       FD->isExternC() && !FD->hasAttr<NoThrowAttr>()) {
     const auto *FPT = FD->getType()->getAs<FunctionProtoType>();
     if (!FPT || FPT->getExceptionSpecType() == EST_None)
       FD->addAttr(NoThrowAttr::CreateImplicit(Context, FD->getLocation()));
   }
 
   IdentifierInfo *Name = FD->getIdentifier();
   if (!Name)
     return;
   if ((!getLangOpts().CPlusPlus &&
        FD->getDeclContext()->isTranslationUnit()) ||
       (isa<LinkageSpecDecl>(FD->getDeclContext()) &&
        cast<LinkageSpecDecl>(FD->getDeclContext())->getLanguage() ==
        LinkageSpecDecl::lang_c)) {
     // Okay: this could be a libc/libm/Objective-C function we know
     // about.
   } else
     return;
 
   if (Name->isStr("asprintf") || Name->isStr("vasprintf")) {
     // FIXME: asprintf and vasprintf aren't C99 functions. Should they be
     // target-specific builtins, perhaps?
     if (!FD->hasAttr<FormatAttr>())
       FD->addAttr(FormatAttr::CreateImplicit(Context,
                                              &Context.Idents.get("printf"), 2,
                                              Name->isStr("vasprintf") ? 0 : 3,
                                              FD->getLocation()));
   }
 
   if (Name->isStr("__CFStringMakeConstantString")) {
     // We already have a __builtin___CFStringMakeConstantString,
     // but builds that use -fno-constant-cfstrings don't go through that.
     if (!FD->hasAttr<FormatArgAttr>())
       FD->addAttr(FormatArgAttr::CreateImplicit(Context, ParamIdx(1, FD),
                                                 FD->getLocation()));
   }
 }
 
 TypedefDecl *Sema::ParseTypedefDecl(Scope *S, Declarator &D, QualType T,
                                     TypeSourceInfo *TInfo) {
   assert(D.getIdentifier() && "Wrong callback for declspec without declarator");
   assert(!T.isNull() && "GetTypeForDeclarator() returned null type");
 
   if (!TInfo) {
     assert(D.isInvalidType() && "no declarator info for valid type");
     TInfo = Context.getTrivialTypeSourceInfo(T);
   }
 
   // Scope manipulation handled by caller.
   TypedefDecl *NewTD =
       TypedefDecl::Create(Context, CurContext, D.getBeginLoc(),
                           D.getIdentifierLoc(), D.getIdentifier(), TInfo);
 
   // Bail out immediately if we have an invalid declaration.
   if (D.isInvalidType()) {
     NewTD->setInvalidDecl();
     return NewTD;
   }
 
   if (D.getDeclSpec().isModulePrivateSpecified()) {
     if (CurContext->isFunctionOrMethod())
       Diag(NewTD->getLocation(), diag::err_module_private_local)
           << 2 << NewTD
           << SourceRange(D.getDeclSpec().getModulePrivateSpecLoc())
           << FixItHint::CreateRemoval(
                  D.getDeclSpec().getModulePrivateSpecLoc());
     else
       NewTD->setModulePrivate();
   }
 
   // C++ [dcl.typedef]p8:
   //   If the typedef declaration defines an unnamed class (or
   //   enum), the first typedef-name declared by the declaration
   //   to be that class type (or enum type) is used to denote the
   //   class type (or enum type) for linkage purposes only.
   // We need to check whether the type was declared in the declaration.
   switch (D.getDeclSpec().getTypeSpecType()) {
   case TST_enum:
   case TST_struct:
   case TST_interface:
   case TST_union:
   case TST_class: {
     TagDecl *tagFromDeclSpec = cast<TagDecl>(D.getDeclSpec().getRepAsDecl());
     setTagNameForLinkagePurposes(tagFromDeclSpec, NewTD);
     break;
   }
 
   default:
     break;
   }
 
   return NewTD;
 }
 
 /// Check that this is a valid underlying type for an enum declaration.
 bool Sema::CheckEnumUnderlyingType(TypeSourceInfo *TI) {
   SourceLocation UnderlyingLoc = TI->getTypeLoc().getBeginLoc();
   QualType T = TI->getType();
 
   if (T->isDependentType())
     return false;
 
   // This doesn't use 'isIntegralType' despite the error message mentioning
   // integral type because isIntegralType would also allow enum types in C.
   if (const BuiltinType *BT = T->getAs<BuiltinType>())
     if (BT->isInteger())
       return false;
 
   if (T->isBitIntType())
     return false;
 
   return Diag(UnderlyingLoc, diag::err_enum_invalid_underlying) << T;
 }
 
 /// Check whether this is a valid redeclaration of a previous enumeration.
 /// \return true if the redeclaration was invalid.
 bool Sema::CheckEnumRedeclaration(SourceLocation EnumLoc, bool IsScoped,
                                   QualType EnumUnderlyingTy, bool IsFixed,
                                   const EnumDecl *Prev) {
   if (IsScoped != Prev->isScoped()) {
     Diag(EnumLoc, diag::err_enum_redeclare_scoped_mismatch)
       << Prev->isScoped();
     Diag(Prev->getLocation(), diag::note_previous_declaration);
     return true;
   }
 
   if (IsFixed && Prev->isFixed()) {
     if (!EnumUnderlyingTy->isDependentType() &&
         !Prev->getIntegerType()->isDependentType() &&
         !Context.hasSameUnqualifiedType(EnumUnderlyingTy,
                                         Prev->getIntegerType())) {
       // TODO: Highlight the underlying type of the redeclaration.
       Diag(EnumLoc, diag::err_enum_redeclare_type_mismatch)
         << EnumUnderlyingTy << Prev->getIntegerType();
       Diag(Prev->getLocation(), diag::note_previous_declaration)
           << Prev->getIntegerTypeRange();
       return true;
     }
   } else if (IsFixed != Prev->isFixed()) {
     Diag(EnumLoc, diag::err_enum_redeclare_fixed_mismatch)
       << Prev->isFixed();
     Diag(Prev->getLocation(), diag::note_previous_declaration);
     return true;
   }
 
   return false;
 }
 
 /// Get diagnostic %select index for tag kind for
 /// redeclaration diagnostic message.
 /// WARNING: Indexes apply to particular diagnostics only!
 ///
 /// \returns diagnostic %select index.
 static unsigned getRedeclDiagFromTagKind(TagTypeKind Tag) {
   switch (Tag) {
   case TTK_Struct: return 0;
   case TTK_Interface: return 1;
   case TTK_Class:  return 2;
   default: llvm_unreachable("Invalid tag kind for redecl diagnostic!");
   }
 }
 
 /// Determine if tag kind is a class-key compatible with
 /// class for redeclaration (class, struct, or __interface).
 ///
 /// \returns true iff the tag kind is compatible.
 static bool isClassCompatTagKind(TagTypeKind Tag)
 {
   return Tag == TTK_Struct || Tag == TTK_Class || Tag == TTK_Interface;
 }
 
 Sema::NonTagKind Sema::getNonTagTypeDeclKind(const Decl *PrevDecl,
                                              TagTypeKind TTK) {
   if (isa<TypedefDecl>(PrevDecl))
     return NTK_Typedef;
   else if (isa<TypeAliasDecl>(PrevDecl))
     return NTK_TypeAlias;
   else if (isa<ClassTemplateDecl>(PrevDecl))
     return NTK_Template;
   else if (isa<TypeAliasTemplateDecl>(PrevDecl))
     return NTK_TypeAliasTemplate;
   else if (isa<TemplateTemplateParmDecl>(PrevDecl))
     return NTK_TemplateTemplateArgument;
   switch (TTK) {
   case TTK_Struct:
   case TTK_Interface:
   case TTK_Class:
     return getLangOpts().CPlusPlus ? NTK_NonClass : NTK_NonStruct;
   case TTK_Union:
     return NTK_NonUnion;
   case TTK_Enum:
     return NTK_NonEnum;
   }
   llvm_unreachable("invalid TTK");
 }
 
 /// Determine whether a tag with a given kind is acceptable
 /// as a redeclaration of the given tag declaration.
 ///
 /// \returns true if the new tag kind is acceptable, false otherwise.
 bool Sema::isAcceptableTagRedeclaration(const TagDecl *Previous,
                                         TagTypeKind NewTag, bool isDefinition,
                                         SourceLocation NewTagLoc,
                                         const IdentifierInfo *Name) {
   // C++ [dcl.type.elab]p3:
   //   The class-key or enum keyword present in the
   //   elaborated-type-specifier shall agree in kind with the
   //   declaration to which the name in the elaborated-type-specifier
   //   refers. This rule also applies to the form of
   //   elaborated-type-specifier that declares a class-name or
   //   friend class since it can be construed as referring to the
   //   definition of the class. Thus, in any
   //   elaborated-type-specifier, the enum keyword shall be used to
   //   refer to an enumeration (7.2), the union class-key shall be
   //   used to refer to a union (clause 9), and either the class or
   //   struct class-key shall be used to refer to a class (clause 9)
   //   declared using the class or struct class-key.
   TagTypeKind OldTag = Previous->getTagKind();
   if (OldTag != NewTag &&
       !(isClassCompatTagKind(OldTag) && isClassCompatTagKind(NewTag)))
     return false;
 
   // Tags are compatible, but we might still want to warn on mismatched tags.
   // Non-class tags can't be mismatched at this point.
   if (!isClassCompatTagKind(NewTag))
     return true;
 
   // Declarations for which -Wmismatched-tags is disabled are entirely ignored
   // by our warning analysis. We don't want to warn about mismatches with (eg)
   // declarations in system headers that are designed to be specialized, but if
   // a user asks us to warn, we should warn if their code contains mismatched
   // declarations.
   auto IsIgnoredLoc = [&](SourceLocation Loc) {
     return getDiagnostics().isIgnored(diag::warn_struct_class_tag_mismatch,
                                       Loc);
   };
   if (IsIgnoredLoc(NewTagLoc))
     return true;
 
   auto IsIgnored = [&](const TagDecl *Tag) {
     return IsIgnoredLoc(Tag->getLocation());
   };
   while (IsIgnored(Previous)) {
     Previous = Previous->getPreviousDecl();
     if (!Previous)
       return true;
     OldTag = Previous->getTagKind();
   }
 
   bool isTemplate = false;
   if (const CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(Previous))
     isTemplate = Record->getDescribedClassTemplate();
 
   if (inTemplateInstantiation()) {
     if (OldTag != NewTag) {
       // In a template instantiation, do not offer fix-its for tag mismatches
       // since they usually mess up the template instead of fixing the problem.
       Diag(NewTagLoc, diag::warn_struct_class_tag_mismatch)
         << getRedeclDiagFromTagKind(NewTag) << isTemplate << Name
         << getRedeclDiagFromTagKind(OldTag);
       // FIXME: Note previous location?
     }
     return true;
   }
 
   if (isDefinition) {
     // On definitions, check all previous tags and issue a fix-it for each
     // one that doesn't match the current tag.
     if (Previous->getDefinition()) {
       // Don't suggest fix-its for redefinitions.
       return true;
     }
 
     bool previousMismatch = false;
     for (const TagDecl *I : Previous->redecls()) {
       if (I->getTagKind() != NewTag) {
         // Ignore previous declarations for which the warning was disabled.
         if (IsIgnored(I))
           continue;
 
         if (!previousMismatch) {
           previousMismatch = true;
           Diag(NewTagLoc, diag::warn_struct_class_previous_tag_mismatch)
             << getRedeclDiagFromTagKind(NewTag) << isTemplate << Name
             << getRedeclDiagFromTagKind(I->getTagKind());
         }
         Diag(I->getInnerLocStart(), diag::note_struct_class_suggestion)
           << getRedeclDiagFromTagKind(NewTag)
           << FixItHint::CreateReplacement(I->getInnerLocStart(),
                TypeWithKeyword::getTagTypeKindName(NewTag));
       }
     }
     return true;
   }
 
   // Identify the prevailing tag kind: this is the kind of the definition (if
   // there is a non-ignored definition), or otherwise the kind of the prior
   // (non-ignored) declaration.
   const TagDecl *PrevDef = Previous->getDefinition();
   if (PrevDef && IsIgnored(PrevDef))
     PrevDef = nullptr;
   const TagDecl *Redecl = PrevDef ? PrevDef : Previous;
   if (Redecl->getTagKind() != NewTag) {
     Diag(NewTagLoc, diag::warn_struct_class_tag_mismatch)
       << getRedeclDiagFromTagKind(NewTag) << isTemplate << Name
       << getRedeclDiagFromTagKind(OldTag);
     Diag(Redecl->getLocation(), diag::note_previous_use);
 
     // If there is a previous definition, suggest a fix-it.
     if (PrevDef) {
       Diag(NewTagLoc, diag::note_struct_class_suggestion)
         << getRedeclDiagFromTagKind(Redecl->getTagKind())
         << FixItHint::CreateReplacement(SourceRange(NewTagLoc),
              TypeWithKeyword::getTagTypeKindName(Redecl->getTagKind()));
     }
   }
 
   return true;
 }
 
 /// Add a minimal nested name specifier fixit hint to allow lookup of a tag name
 /// from an outer enclosing namespace or file scope inside a friend declaration.
 /// This should provide the commented out code in the following snippet:
 ///   namespace N {
 ///     struct X;
 ///     namespace M {
 ///       struct Y { friend struct /*N::*/ X; };
 ///     }
 ///   }
 static FixItHint createFriendTagNNSFixIt(Sema &SemaRef, NamedDecl *ND, Scope *S,
                                          SourceLocation NameLoc) {
   // While the decl is in a namespace, do repeated lookup of that name and see
   // if we get the same namespace back.  If we do not, continue until
   // translation unit scope, at which point we have a fully qualified NNS.
   SmallVector<IdentifierInfo *, 4> Namespaces;
   DeclContext *DC = ND->getDeclContext()->getRedeclContext();
   for (; !DC->isTranslationUnit(); DC = DC->getParent()) {
     // This tag should be declared in a namespace, which can only be enclosed by
     // other namespaces.  Bail if there's an anonymous namespace in the chain.
     NamespaceDecl *Namespace = dyn_cast<NamespaceDecl>(DC);
     if (!Namespace || Namespace->isAnonymousNamespace())
       return FixItHint();
     IdentifierInfo *II = Namespace->getIdentifier();
     Namespaces.push_back(II);
     NamedDecl *Lookup = SemaRef.LookupSingleName(
         S, II, NameLoc, Sema::LookupNestedNameSpecifierName);
     if (Lookup == Namespace)
       break;
   }
 
   // Once we have all the namespaces, reverse them to go outermost first, and
   // build an NNS.
   SmallString<64> Insertion;
   llvm::raw_svector_ostream OS(Insertion);
   if (DC->isTranslationUnit())
     OS << "::";
   std::reverse(Namespaces.begin(), Namespaces.end());
   for (auto *II : Namespaces)
     OS << II->getName() << "::";
   return FixItHint::CreateInsertion(NameLoc, Insertion);
 }
 
 /// Determine whether a tag originally declared in context \p OldDC can
 /// be redeclared with an unqualified name in \p NewDC (assuming name lookup
 /// found a declaration in \p OldDC as a previous decl, perhaps through a
 /// using-declaration).
 static bool isAcceptableTagRedeclContext(Sema &S, DeclContext *OldDC,
                                          DeclContext *NewDC) {
   OldDC = OldDC->getRedeclContext();
   NewDC = NewDC->getRedeclContext();
 
   if (OldDC->Equals(NewDC))
     return true;
 
   // In MSVC mode, we allow a redeclaration if the contexts are related (either
   // encloses the other).
   if (S.getLangOpts().MSVCCompat &&
       (OldDC->Encloses(NewDC) || NewDC->Encloses(OldDC)))
     return true;
 
   return false;
 }
 
 /// This is invoked when we see 'struct foo' or 'struct {'.  In the
 /// former case, Name will be non-null.  In the later case, Name will be null.
 /// TagSpec indicates what kind of tag this is. TUK indicates whether this is a
 /// reference/declaration/definition of a tag.
 ///
 /// \param IsTypeSpecifier \c true if this is a type-specifier (or
 /// trailing-type-specifier) other than one in an alias-declaration.
 ///
 /// \param SkipBody If non-null, will be set to indicate if the caller should
 /// skip the definition of this tag and treat it as if it were a declaration.
 DeclResult
 Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
                CXXScopeSpec &SS, IdentifierInfo *Name, SourceLocation NameLoc,
                const ParsedAttributesView &Attrs, AccessSpecifier AS,
                SourceLocation ModulePrivateLoc,
                MultiTemplateParamsArg TemplateParameterLists, bool &OwnedDecl,
                bool &IsDependent, SourceLocation ScopedEnumKWLoc,
                bool ScopedEnumUsesClassTag, TypeResult UnderlyingType,
                bool IsTypeSpecifier, bool IsTemplateParamOrArg,
                OffsetOfKind OOK, SkipBodyInfo *SkipBody) {
   // If this is not a definition, it must have a name.
   IdentifierInfo *OrigName = Name;
   assert((Name != nullptr || TUK == TUK_Definition) &&
          "Nameless record must be a definition!");
   assert(TemplateParameterLists.size() == 0 || TUK != TUK_Reference);
 
   OwnedDecl = false;
   TagTypeKind Kind = TypeWithKeyword::getTagTypeKindForTypeSpec(TagSpec);
   bool ScopedEnum = ScopedEnumKWLoc.isValid();
 
   // FIXME: Check member specializations more carefully.
   bool isMemberSpecialization = false;
   bool Invalid = false;
 
   // We only need to do this matching if we have template parameters
   // or a scope specifier, which also conveniently avoids this work
   // for non-C++ cases.
   if (TemplateParameterLists.size() > 0 ||
       (SS.isNotEmpty() && TUK != TUK_Reference)) {
     if (TemplateParameterList *TemplateParams =
             MatchTemplateParametersToScopeSpecifier(
                 KWLoc, NameLoc, SS, nullptr, TemplateParameterLists,
                 TUK == TUK_Friend, isMemberSpecialization, Invalid)) {
       if (Kind == TTK_Enum) {
         Diag(KWLoc, diag::err_enum_template);
         return true;
       }
 
       if (TemplateParams->size() > 0) {
         // This is a declaration or definition of a class template (which may
         // be a member of another template).
 
         if (Invalid)
           return true;
 
         OwnedDecl = false;
         DeclResult Result = CheckClassTemplate(
             S, TagSpec, TUK, KWLoc, SS, Name, NameLoc, Attrs, TemplateParams,
             AS, ModulePrivateLoc,
             /*FriendLoc*/ SourceLocation(), TemplateParameterLists.size() - 1,
             TemplateParameterLists.data(), SkipBody);
         return Result.get();
       } else {
         // The "template<>" header is extraneous.
         Diag(TemplateParams->getTemplateLoc(), diag::err_template_tag_noparams)
           << TypeWithKeyword::getTagTypeKindName(Kind) << Name;
         isMemberSpecialization = true;
       }
     }
 
     if (!TemplateParameterLists.empty() && isMemberSpecialization &&
         CheckTemplateDeclScope(S, TemplateParameterLists.back()))
       return true;
   }
 
   // Figure out the underlying type if this a enum declaration. We need to do
   // this early, because it's needed to detect if this is an incompatible
   // redeclaration.
   llvm::PointerUnion<const Type*, TypeSourceInfo*> EnumUnderlying;
   bool IsFixed = !UnderlyingType.isUnset() || ScopedEnum;
 
   if (Kind == TTK_Enum) {
     if (UnderlyingType.isInvalid() || (!UnderlyingType.get() && ScopedEnum)) {
       // No underlying type explicitly specified, or we failed to parse the
       // type, default to int.
       EnumUnderlying = Context.IntTy.getTypePtr();
     } else if (UnderlyingType.get()) {
       // C++0x 7.2p2: The type-specifier-seq of an enum-base shall name an
       // integral type; any cv-qualification is ignored.
       TypeSourceInfo *TI = nullptr;
       GetTypeFromParser(UnderlyingType.get(), &TI);
       EnumUnderlying = TI;
 
       if (CheckEnumUnderlyingType(TI))
         // Recover by falling back to int.
         EnumUnderlying = Context.IntTy.getTypePtr();
 
       if (DiagnoseUnexpandedParameterPack(TI->getTypeLoc().getBeginLoc(), TI,
                                           UPPC_FixedUnderlyingType))
         EnumUnderlying = Context.IntTy.getTypePtr();
 
     } else if (Context.getTargetInfo().getTriple().isWindowsMSVCEnvironment()) {
       // For MSVC ABI compatibility, unfixed enums must use an underlying type
       // of 'int'. However, if this is an unfixed forward declaration, don't set
       // the underlying type unless the user enables -fms-compatibility. This
       // makes unfixed forward declared enums incomplete and is more conforming.
       if (TUK == TUK_Definition || getLangOpts().MSVCCompat)
         EnumUnderlying = Context.IntTy.getTypePtr();
     }
   }
 
   DeclContext *SearchDC = CurContext;
   DeclContext *DC = CurContext;
   bool isStdBadAlloc = false;
   bool isStdAlignValT = false;
 
   RedeclarationKind Redecl = forRedeclarationInCurContext();
   if (TUK == TUK_Friend || TUK == TUK_Reference)
     Redecl = NotForRedeclaration;
 
   /// Create a new tag decl in C/ObjC. Since the ODR-like semantics for ObjC/C
   /// implemented asks for structural equivalence checking, the returned decl
   /// here is passed back to the parser, allowing the tag body to be parsed.
   auto createTagFromNewDecl = [&]() -> TagDecl * {
     assert(!getLangOpts().CPlusPlus && "not meant for C++ usage");
     // If there is an identifier, use the location of the identifier as the
     // location of the decl, otherwise use the location of the struct/union
     // keyword.
     SourceLocation Loc = NameLoc.isValid() ? NameLoc : KWLoc;
     TagDecl *New = nullptr;
 
     if (Kind == TTK_Enum) {
       New = EnumDecl::Create(Context, SearchDC, KWLoc, Loc, Name, nullptr,
                              ScopedEnum, ScopedEnumUsesClassTag, IsFixed);
       // If this is an undefined enum, bail.
       if (TUK != TUK_Definition && !Invalid)
         return nullptr;
       if (EnumUnderlying) {
         EnumDecl *ED = cast<EnumDecl>(New);
         if (TypeSourceInfo *TI = EnumUnderlying.dyn_cast<TypeSourceInfo *>())
           ED->setIntegerTypeSourceInfo(TI);
         else
           ED->setIntegerType(QualType(EnumUnderlying.get<const Type *>(), 0));
         QualType EnumTy = ED->getIntegerType();
         ED->setPromotionType(Context.isPromotableIntegerType(EnumTy)
                                  ? Context.getPromotedIntegerType(EnumTy)
                                  : EnumTy);
       }
     } else { // struct/union
       New = RecordDecl::Create(Context, Kind, SearchDC, KWLoc, Loc, Name,
                                nullptr);
     }
 
     if (RecordDecl *RD = dyn_cast<RecordDecl>(New)) {
       // Add alignment attributes if necessary; these attributes are checked
       // when the ASTContext lays out the structure.
       //
       // It is important for implementing the correct semantics that this
       // happen here (in ActOnTag). The #pragma pack stack is
       // maintained as a result of parser callbacks which can occur at
       // many points during the parsing of a struct declaration (because
       // the #pragma tokens are effectively skipped over during the
       // parsing of the struct).
       if (TUK == TUK_Definition && (!SkipBody || !SkipBody->ShouldSkip)) {
         AddAlignmentAttributesForRecord(RD);
         AddMsStructLayoutForRecord(RD);
       }
     }
     New->setLexicalDeclContext(CurContext);
     return New;
   };
 
   LookupResult Previous(*this, Name, NameLoc, LookupTagName, Redecl);
   if (Name && SS.isNotEmpty()) {
     // We have a nested-name tag ('struct foo::bar').
 
     // Check for invalid 'foo::'.
     if (SS.isInvalid()) {
       Name = nullptr;
       goto CreateNewDecl;
     }
 
     // If this is a friend or a reference to a class in a dependent
     // context, don't try to make a decl for it.
     if (TUK == TUK_Friend || TUK == TUK_Reference) {
       DC = computeDeclContext(SS, false);
       if (!DC) {
         IsDependent = true;
         return true;
       }
     } else {
       DC = computeDeclContext(SS, true);
       if (!DC) {
         Diag(SS.getRange().getBegin(), diag::err_dependent_nested_name_spec)
           << SS.getRange();
         return true;
       }
     }
 
     if (RequireCompleteDeclContext(SS, DC))
       return true;
 
     SearchDC = DC;
     // Look-up name inside 'foo::'.
     LookupQualifiedName(Previous, DC);
 
     if (Previous.isAmbiguous())
       return true;
 
     if (Previous.empty()) {
       // Name lookup did not find anything. However, if the
       // nested-name-specifier refers to the current instantiation,
       // and that current instantiation has any dependent base
       // classes, we might find something at instantiation time: treat
       // this as a dependent elaborated-type-specifier.
       // But this only makes any sense for reference-like lookups.
       if (Previous.wasNotFoundInCurrentInstantiation() &&
           (TUK == TUK_Reference || TUK == TUK_Friend)) {
         IsDependent = true;
         return true;
       }
 
       // A tag 'foo::bar' must already exist.
       Diag(NameLoc, diag::err_not_tag_in_scope)
         << Kind << Name << DC << SS.getRange();
       Name = nullptr;
       Invalid = true;
       goto CreateNewDecl;
     }
   } else if (Name) {
     // C++14 [class.mem]p14:
     //   If T is the name of a class, then each of the following shall have a
     //   name different from T:
     //    -- every member of class T that is itself a type
     if (TUK != TUK_Reference && TUK != TUK_Friend &&
         DiagnoseClassNameShadow(SearchDC, DeclarationNameInfo(Name, NameLoc)))
       return true;
 
     // If this is a named struct, check to see if there was a previous forward
     // declaration or definition.
     // FIXME: We're looking into outer scopes here, even when we
     // shouldn't be. Doing so can result in ambiguities that we
     // shouldn't be diagnosing.
     LookupName(Previous, S);
 
     // When declaring or defining a tag, ignore ambiguities introduced
     // by types using'ed into this scope.
     if (Previous.isAmbiguous() &&
         (TUK == TUK_Definition || TUK == TUK_Declaration)) {
       LookupResult::Filter F = Previous.makeFilter();
       while (F.hasNext()) {
         NamedDecl *ND = F.next();
         if (!ND->getDeclContext()->getRedeclContext()->Equals(
                 SearchDC->getRedeclContext()))
           F.erase();
       }
       F.done();
     }
 
     // C++11 [namespace.memdef]p3:
     //   If the name in a friend declaration is neither qualified nor
     //   a template-id and the declaration is a function or an
     //   elaborated-type-specifier, the lookup to determine whether
     //   the entity has been previously declared shall not consider
     //   any scopes outside the innermost enclosing namespace.
     //
     // MSVC doesn't implement the above rule for types, so a friend tag
     // declaration may be a redeclaration of a type declared in an enclosing
     // scope.  They do implement this rule for friend functions.
     //
     // Does it matter that this should be by scope instead of by
     // semantic context?
     if (!Previous.empty() && TUK == TUK_Friend) {
       DeclContext *EnclosingNS = SearchDC->getEnclosingNamespaceContext();
       LookupResult::Filter F = Previous.makeFilter();
       bool FriendSawTagOutsideEnclosingNamespace = false;
       while (F.hasNext()) {
         NamedDecl *ND = F.next();
         DeclContext *DC = ND->getDeclContext()->getRedeclContext();
         if (DC->isFileContext() &&
             !EnclosingNS->Encloses(ND->getDeclContext())) {
           if (getLangOpts().MSVCCompat)
             FriendSawTagOutsideEnclosingNamespace = true;
           else
             F.erase();
         }
       }
       F.done();
 
       // Diagnose this MSVC extension in the easy case where lookup would have
       // unambiguously found something outside the enclosing namespace.
       if (Previous.isSingleResult() && FriendSawTagOutsideEnclosingNamespace) {
         NamedDecl *ND = Previous.getFoundDecl();
         Diag(NameLoc, diag::ext_friend_tag_redecl_outside_namespace)
             << createFriendTagNNSFixIt(*this, ND, S, NameLoc);
       }
     }
 
     // Note:  there used to be some attempt at recovery here.
     if (Previous.isAmbiguous())
       return true;
 
     if (!getLangOpts().CPlusPlus && TUK != TUK_Reference) {
       // FIXME: This makes sure that we ignore the contexts associated
       // with C structs, unions, and enums when looking for a matching
       // tag declaration or definition. See the similar lookup tweak
       // in Sema::LookupName; is there a better way to deal with this?
       while (isa<RecordDecl, EnumDecl, ObjCContainerDecl>(SearchDC))
         SearchDC = SearchDC->getParent();
     } else if (getLangOpts().CPlusPlus) {
       // Inside ObjCContainer want to keep it as a lexical decl context but go
       // past it (most often to TranslationUnit) to find the semantic decl
       // context.
       while (isa<ObjCContainerDecl>(SearchDC))
         SearchDC = SearchDC->getParent();
     }
   } else if (getLangOpts().CPlusPlus) {
     // Don't use ObjCContainerDecl as the semantic decl context for anonymous
     // TagDecl the same way as we skip it for named TagDecl.
     while (isa<ObjCContainerDecl>(SearchDC))
       SearchDC = SearchDC->getParent();
   }
 
   if (Previous.isSingleResult() &&
       Previous.getFoundDecl()->isTemplateParameter()) {
     // Maybe we will complain about the shadowed template parameter.
     DiagnoseTemplateParameterShadow(NameLoc, Previous.getFoundDecl());
     // Just pretend that we didn't see the previous declaration.
     Previous.clear();
   }
 
   if (getLangOpts().CPlusPlus && Name && DC && StdNamespace &&
       DC->Equals(getStdNamespace())) {
     if (Name->isStr("bad_alloc")) {
       // This is a declaration of or a reference to "std::bad_alloc".
       isStdBadAlloc = true;
 
       // If std::bad_alloc has been implicitly declared (but made invisible to
       // name lookup), fill in this implicit declaration as the previous
       // declaration, so that the declarations get chained appropriately.
       if (Previous.empty() && StdBadAlloc)
         Previous.addDecl(getStdBadAlloc());
     } else if (Name->isStr("align_val_t")) {
       isStdAlignValT = true;
       if (Previous.empty() && StdAlignValT)
         Previous.addDecl(getStdAlignValT());
     }
   }
 
   // If we didn't find a previous declaration, and this is a reference
   // (or friend reference), move to the correct scope.  In C++, we
   // also need to do a redeclaration lookup there, just in case
   // there's a shadow friend decl.
   if (Name && Previous.empty() &&
       (TUK == TUK_Reference || TUK == TUK_Friend || IsTemplateParamOrArg)) {
     if (Invalid) goto CreateNewDecl;
     assert(SS.isEmpty());
 
     if (TUK == TUK_Reference || IsTemplateParamOrArg) {
       // C++ [basic.scope.pdecl]p5:
       //   -- for an elaborated-type-specifier of the form
       //
       //          class-key identifier
       //
       //      if the elaborated-type-specifier is used in the
       //      decl-specifier-seq or parameter-declaration-clause of a
       //      function defined in namespace scope, the identifier is
       //      declared as a class-name in the namespace that contains
       //      the declaration; otherwise, except as a friend
       //      declaration, the identifier is declared in the smallest
       //      non-class, non-function-prototype scope that contains the
       //      declaration.
       //
       // C99 6.7.2.3p8 has a similar (but not identical!) provision for
       // C structs and unions.
       //
       // It is an error in C++ to declare (rather than define) an enum
       // type, including via an elaborated type specifier.  We'll
       // diagnose that later; for now, declare the enum in the same
       // scope as we would have picked for any other tag type.
       //
       // GNU C also supports this behavior as part of its incomplete
       // enum types extension, while GNU C++ does not.
       //
       // Find the context where we'll be declaring the tag.
       // FIXME: We would like to maintain the current DeclContext as the
       // lexical context,
       SearchDC = getTagInjectionContext(SearchDC);
 
       // Find the scope where we'll be declaring the tag.
       S = getTagInjectionScope(S, getLangOpts());
     } else {
       assert(TUK == TUK_Friend);
       CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(SearchDC);
 
       // C++ [namespace.memdef]p3:
       //   If a friend declaration in a non-local class first declares a
       //   class or function, the friend class or function is a member of
       //   the innermost enclosing namespace.
       SearchDC = RD->isLocalClass() ? RD->isLocalClass()
                                     : SearchDC->getEnclosingNamespaceContext();
     }
 
     // In C++, we need to do a redeclaration lookup to properly
     // diagnose some problems.
     // FIXME: redeclaration lookup is also used (with and without C++) to find a
     // hidden declaration so that we don't get ambiguity errors when using a
     // type declared by an elaborated-type-specifier.  In C that is not correct
     // and we should instead merge compatible types found by lookup.
     if (getLangOpts().CPlusPlus) {
       // FIXME: This can perform qualified lookups into function contexts,
       // which are meaningless.
       Previous.setRedeclarationKind(forRedeclarationInCurContext());
       LookupQualifiedName(Previous, SearchDC);
     } else {
       Previous.setRedeclarationKind(forRedeclarationInCurContext());
       LookupName(Previous, S);
     }
   }
 
   // If we have a known previous declaration to use, then use it.
   if (Previous.empty() && SkipBody && SkipBody->Previous)
     Previous.addDecl(SkipBody->Previous);
 
   if (!Previous.empty()) {
     NamedDecl *PrevDecl = Previous.getFoundDecl();
     NamedDecl *DirectPrevDecl = Previous.getRepresentativeDecl();
 
     // It's okay to have a tag decl in the same scope as a typedef
     // which hides a tag decl in the same scope.  Finding this
     // with a redeclaration lookup can only actually happen in C++.
     //
     // This is also okay for elaborated-type-specifiers, which is
     // technically forbidden by the current standard but which is
     // okay according to the likely resolution of an open issue;
     // see http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#407
     if (getLangOpts().CPlusPlus) {
       if (TypedefNameDecl *TD = dyn_cast<TypedefNameDecl>(PrevDecl)) {
         if (const TagType *TT = TD->getUnderlyingType()->getAs<TagType>()) {
           TagDecl *Tag = TT->getDecl();
           if (Tag->getDeclName() == Name &&
               Tag->getDeclContext()->getRedeclContext()
                           ->Equals(TD->getDeclContext()->getRedeclContext())) {
             PrevDecl = Tag;
             Previous.clear();
             Previous.addDecl(Tag);
             Previous.resolveKind();
           }
         }
       }
     }
 
     // If this is a redeclaration of a using shadow declaration, it must
     // declare a tag in the same context. In MSVC mode, we allow a
     // redefinition if either context is within the other.
     if (auto *Shadow = dyn_cast<UsingShadowDecl>(DirectPrevDecl)) {
       auto *OldTag = dyn_cast<TagDecl>(PrevDecl);
       if (SS.isEmpty() && TUK != TUK_Reference && TUK != TUK_Friend &&
           isDeclInScope(Shadow, SearchDC, S, isMemberSpecialization) &&
           !(OldTag && isAcceptableTagRedeclContext(
                           *this, OldTag->getDeclContext(), SearchDC))) {
         Diag(KWLoc, diag::err_using_decl_conflict_reverse);
         Diag(Shadow->getTargetDecl()->getLocation(),
              diag::note_using_decl_target);
         Diag(Shadow->getIntroducer()->getLocation(), diag::note_using_decl)
             << 0;
         // Recover by ignoring the old declaration.
         Previous.clear();
         goto CreateNewDecl;
       }
     }
 
     if (TagDecl *PrevTagDecl = dyn_cast<TagDecl>(PrevDecl)) {
       // If this is a use of a previous tag, or if the tag is already declared
       // in the same scope (so that the definition/declaration completes or
       // rementions the tag), reuse the decl.
       if (TUK == TUK_Reference || TUK == TUK_Friend ||
           isDeclInScope(DirectPrevDecl, SearchDC, S,
                         SS.isNotEmpty() || isMemberSpecialization)) {
         // Make sure that this wasn't declared as an enum and now used as a
         // struct or something similar.
         if (!isAcceptableTagRedeclaration(PrevTagDecl, Kind,
                                           TUK == TUK_Definition, KWLoc,
                                           Name)) {
           bool SafeToContinue
             = (PrevTagDecl->getTagKind() != TTK_Enum &&
                Kind != TTK_Enum);
           if (SafeToContinue)
             Diag(KWLoc, diag::err_use_with_wrong_tag)
               << Name
               << FixItHint::CreateReplacement(SourceRange(KWLoc),
                                               PrevTagDecl->getKindName());
           else
             Diag(KWLoc, diag::err_use_with_wrong_tag) << Name;
           Diag(PrevTagDecl->getLocation(), diag::note_previous_use);
 
           if (SafeToContinue)
             Kind = PrevTagDecl->getTagKind();
           else {
             // Recover by making this an anonymous redefinition.
             Name = nullptr;
             Previous.clear();
             Invalid = true;
           }
         }
 
         if (Kind == TTK_Enum && PrevTagDecl->getTagKind() == TTK_Enum) {
           const EnumDecl *PrevEnum = cast<EnumDecl>(PrevTagDecl);
           if (TUK == TUK_Reference || TUK == TUK_Friend)
             return PrevTagDecl;
 
           QualType EnumUnderlyingTy;
           if (TypeSourceInfo *TI = EnumUnderlying.dyn_cast<TypeSourceInfo*>())
             EnumUnderlyingTy = TI->getType().getUnqualifiedType();
           else if (const Type *T = EnumUnderlying.dyn_cast<const Type*>())
             EnumUnderlyingTy = QualType(T, 0);
 
           // All conflicts with previous declarations are recovered by
           // returning the previous declaration, unless this is a definition,
           // in which case we want the caller to bail out.
           if (CheckEnumRedeclaration(NameLoc.isValid() ? NameLoc : KWLoc,
                                      ScopedEnum, EnumUnderlyingTy,
                                      IsFixed, PrevEnum))
             return TUK == TUK_Declaration ? PrevTagDecl : nullptr;
         }
 
         // C++11 [class.mem]p1:
         //   A member shall not be declared twice in the member-specification,
         //   except that a nested class or member class template can be declared
         //   and then later defined.
         if (TUK == TUK_Declaration && PrevDecl->isCXXClassMember() &&
             S->isDeclScope(PrevDecl)) {
           Diag(NameLoc, diag::ext_member_redeclared);
           Diag(PrevTagDecl->getLocation(), diag::note_previous_declaration);
         }
 
         if (!Invalid) {
           // If this is a use, just return the declaration we found, unless
           // we have attributes.
           if (TUK == TUK_Reference || TUK == TUK_Friend) {
             if (!Attrs.empty()) {
               // FIXME: Diagnose these attributes. For now, we create a new
               // declaration to hold them.
             } else if (TUK == TUK_Reference &&
                        (PrevTagDecl->getFriendObjectKind() ==
                             Decl::FOK_Undeclared ||
                         PrevDecl->getOwningModule() != getCurrentModule()) &&
                        SS.isEmpty()) {
               // This declaration is a reference to an existing entity, but
               // has different visibility from that entity: it either makes
               // a friend visible or it makes a type visible in a new module.
               // In either case, create a new declaration. We only do this if
               // the declaration would have meant the same thing if no prior
               // declaration were found, that is, if it was found in the same
               // scope where we would have injected a declaration.
               if (!getTagInjectionContext(CurContext)->getRedeclContext()
                        ->Equals(PrevDecl->getDeclContext()->getRedeclContext()))
                 return PrevTagDecl;
               // This is in the injected scope, create a new declaration in
               // that scope.
               S = getTagInjectionScope(S, getLangOpts());
             } else {
               return PrevTagDecl;
             }
           }
 
           // Diagnose attempts to redefine a tag.
           if (TUK == TUK_Definition) {
             if (NamedDecl *Def = PrevTagDecl->getDefinition()) {
               // If we're defining a specialization and the previous definition
               // is from an implicit instantiation, don't emit an error
               // here; we'll catch this in the general case below.
               bool IsExplicitSpecializationAfterInstantiation = false;
               if (isMemberSpecialization) {
                 if (CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(Def))
                   IsExplicitSpecializationAfterInstantiation =
                     RD->getTemplateSpecializationKind() !=
                     TSK_ExplicitSpecialization;
                 else if (EnumDecl *ED = dyn_cast<EnumDecl>(Def))
                   IsExplicitSpecializationAfterInstantiation =
                     ED->getTemplateSpecializationKind() !=
                     TSK_ExplicitSpecialization;
               }
 
               // Note that clang allows ODR-like semantics for ObjC/C, i.e., do
               // not keep more that one definition around (merge them). However,
               // ensure the decl passes the structural compatibility check in
               // C11 6.2.7/1 (or 6.1.2.6/1 in C89).
               NamedDecl *Hidden = nullptr;
               if (SkipBody && !hasVisibleDefinition(Def, &Hidden)) {
                 // There is a definition of this tag, but it is not visible. We
                 // explicitly make use of C++'s one definition rule here, and
                 // assume that this definition is identical to the hidden one
                 // we already have. Make the existing definition visible and
                 // use it in place of this one.
                 if (!getLangOpts().CPlusPlus) {
                   // Postpone making the old definition visible until after we
                   // complete parsing the new one and do the structural
                   // comparison.
                   SkipBody->CheckSameAsPrevious = true;
                   SkipBody->New = createTagFromNewDecl();
                   SkipBody->Previous = Def;
                   return Def;
                 } else {
                   SkipBody->ShouldSkip = true;
                   SkipBody->Previous = Def;
                   makeMergedDefinitionVisible(Hidden);
                   // Carry on and handle it like a normal definition. We'll
                   // skip starting the definitiion later.
                 }
               } else if (!IsExplicitSpecializationAfterInstantiation) {
                 // A redeclaration in function prototype scope in C isn't
                 // visible elsewhere, so merely issue a warning.
                 if (!getLangOpts().CPlusPlus && S->containedInPrototypeScope())
                   Diag(NameLoc, diag::warn_redefinition_in_param_list) << Name;
                 else
                   Diag(NameLoc, diag::err_redefinition) << Name;
                 notePreviousDefinition(Def,
                                        NameLoc.isValid() ? NameLoc : KWLoc);
                 // If this is a redefinition, recover by making this
                 // struct be anonymous, which will make any later
                 // references get the previous definition.
                 Name = nullptr;
                 Previous.clear();
                 Invalid = true;
               }
             } else {
               // If the type is currently being defined, complain
               // about a nested redefinition.
               auto *TD = Context.getTagDeclType(PrevTagDecl)->getAsTagDecl();
               if (TD->isBeingDefined()) {
                 Diag(NameLoc, diag::err_nested_redefinition) << Name;
                 Diag(PrevTagDecl->getLocation(),
                      diag::note_previous_definition);
                 Name = nullptr;
                 Previous.clear();
                 Invalid = true;
               }
             }
 
             // Okay, this is definition of a previously declared or referenced
             // tag. We're going to create a new Decl for it.
           }
 
           // Okay, we're going to make a redeclaration.  If this is some kind
           // of reference, make sure we build the redeclaration in the same DC
           // as the original, and ignore the current access specifier.
           if (TUK == TUK_Friend || TUK == TUK_Reference) {
             SearchDC = PrevTagDecl->getDeclContext();
             AS = AS_none;
           }
         }
         // If we get here we have (another) forward declaration or we
         // have a definition.  Just create a new decl.
 
       } else {
         // If we get here, this is a definition of a new tag type in a nested
         // scope, e.g. "struct foo; void bar() { struct foo; }", just create a
         // new decl/type.  We set PrevDecl to NULL so that the entities
         // have distinct types.
         Previous.clear();
       }
       // If we get here, we're going to create a new Decl. If PrevDecl
       // is non-NULL, it's a definition of the tag declared by
       // PrevDecl. If it's NULL, we have a new definition.
 
     // Otherwise, PrevDecl is not a tag, but was found with tag
     // lookup.  This is only actually possible in C++, where a few
     // things like templates still live in the tag namespace.
     } else {
       // Use a better diagnostic if an elaborated-type-specifier
       // found the wrong kind of type on the first
       // (non-redeclaration) lookup.
       if ((TUK == TUK_Reference || TUK == TUK_Friend) &&
           !Previous.isForRedeclaration()) {
         NonTagKind NTK = getNonTagTypeDeclKind(PrevDecl, Kind);
         Diag(NameLoc, diag::err_tag_reference_non_tag) << PrevDecl << NTK
                                                        << Kind;
         Diag(PrevDecl->getLocation(), diag::note_declared_at);
         Invalid = true;
 
       // Otherwise, only diagnose if the declaration is in scope.
       } else if (!isDeclInScope(DirectPrevDecl, SearchDC, S,
                                 SS.isNotEmpty() || isMemberSpecialization)) {
         // do nothing
 
       // Diagnose implicit declarations introduced by elaborated types.
       } else if (TUK == TUK_Reference || TUK == TUK_Friend) {
         NonTagKind NTK = getNonTagTypeDeclKind(PrevDecl, Kind);
         Diag(NameLoc, diag::err_tag_reference_conflict) << NTK;
         Diag(PrevDecl->getLocation(), diag::note_previous_decl) << PrevDecl;
         Invalid = true;
 
       // Otherwise it's a declaration.  Call out a particularly common
       // case here.
       } else if (TypedefNameDecl *TND = dyn_cast<TypedefNameDecl>(PrevDecl)) {
         unsigned Kind = 0;
         if (isa<TypeAliasDecl>(PrevDecl)) Kind = 1;
         Diag(NameLoc, diag::err_tag_definition_of_typedef)
           << Name << Kind << TND->getUnderlyingType();
         Diag(PrevDecl->getLocation(), diag::note_previous_decl) << PrevDecl;
         Invalid = true;
 
       // Otherwise, diagnose.
       } else {
         // The tag name clashes with something else in the target scope,
         // issue an error and recover by making this tag be anonymous.
         Diag(NameLoc, diag::err_redefinition_different_kind) << Name;
         notePreviousDefinition(PrevDecl, NameLoc);
         Name = nullptr;
         Invalid = true;
       }
 
       // The existing declaration isn't relevant to us; we're in a
       // new scope, so clear out the previous declaration.
       Previous.clear();
     }
   }
 
 CreateNewDecl:
 
   TagDecl *PrevDecl = nullptr;
   if (Previous.isSingleResult())
     PrevDecl = cast<TagDecl>(Previous.getFoundDecl());
 
   // If there is an identifier, use the location of the identifier as the
   // location of the decl, otherwise use the location of the struct/union
   // keyword.
   SourceLocation Loc = NameLoc.isValid() ? NameLoc : KWLoc;
 
   // Otherwise, create a new declaration. If there is a previous
   // declaration of the same entity, the two will be linked via
   // PrevDecl.
   TagDecl *New;
 
   if (Kind == TTK_Enum) {
     // FIXME: Tag decls should be chained to any simultaneous vardecls, e.g.:
     // enum X { A, B, C } D;    D should chain to X.
     New = EnumDecl::Create(Context, SearchDC, KWLoc, Loc, Name,
                            cast_or_null<EnumDecl>(PrevDecl), ScopedEnum,
                            ScopedEnumUsesClassTag, IsFixed);
 
     if (isStdAlignValT && (!StdAlignValT || getStdAlignValT()->isImplicit()))
       StdAlignValT = cast<EnumDecl>(New);
 
     // If this is an undefined enum, warn.
     if (TUK != TUK_Definition && !Invalid) {
       TagDecl *Def;
       if (IsFixed && cast<EnumDecl>(New)->isFixed()) {
         // C++0x: 7.2p2: opaque-enum-declaration.
         // Conflicts are diagnosed above. Do nothing.
       }
       else if (PrevDecl && (Def = cast<EnumDecl>(PrevDecl)->getDefinition())) {
         Diag(Loc, diag::ext_forward_ref_enum_def)
           << New;
         Diag(Def->getLocation(), diag::note_previous_definition);
       } else {
         unsigned DiagID = diag::ext_forward_ref_enum;
         if (getLangOpts().MSVCCompat)
           DiagID = diag::ext_ms_forward_ref_enum;
         else if (getLangOpts().CPlusPlus)
           DiagID = diag::err_forward_ref_enum;
         Diag(Loc, DiagID);
       }
     }
 
     if (EnumUnderlying) {
       EnumDecl *ED = cast<EnumDecl>(New);
       if (TypeSourceInfo *TI = EnumUnderlying.dyn_cast<TypeSourceInfo*>())
         ED->setIntegerTypeSourceInfo(TI);
       else
         ED->setIntegerType(QualType(EnumUnderlying.get<const Type *>(), 0));
       QualType EnumTy = ED->getIntegerType();
       ED->setPromotionType(Context.isPromotableIntegerType(EnumTy)
                                ? Context.getPromotedIntegerType(EnumTy)
                                : EnumTy);
       assert(ED->isComplete() && "enum with type should be complete");
     }
   } else {
     // struct/union/class
 
     // FIXME: Tag decls should be chained to any simultaneous vardecls, e.g.:
     // struct X { int A; } D;    D should chain to X.
     if (getLangOpts().CPlusPlus) {
       // FIXME: Look for a way to use RecordDecl for simple structs.
       New = CXXRecordDecl::Create(Context, Kind, SearchDC, KWLoc, Loc, Name,
                                   cast_or_null<CXXRecordDecl>(PrevDecl));
 
       if (isStdBadAlloc && (!StdBadAlloc || getStdBadAlloc()->isImplicit()))
         StdBadAlloc = cast<CXXRecordDecl>(New);
     } else
       New = RecordDecl::Create(Context, Kind, SearchDC, KWLoc, Loc, Name,
                                cast_or_null<RecordDecl>(PrevDecl));
   }
 
   if (OOK != OOK_Outside && TUK == TUK_Definition && !getLangOpts().CPlusPlus)
     Diag(New->getLocation(), diag::ext_type_defined_in_offsetof)
         << (OOK == OOK_Macro) << New->getSourceRange();
 
   // C++11 [dcl.type]p3:
   //   A type-specifier-seq shall not define a class or enumeration [...].
   if (!Invalid && getLangOpts().CPlusPlus &&
       (IsTypeSpecifier || IsTemplateParamOrArg) && TUK == TUK_Definition) {
     Diag(New->getLocation(), diag::err_type_defined_in_type_specifier)
       << Context.getTagDeclType(New);
     Invalid = true;
   }
 
   if (!Invalid && getLangOpts().CPlusPlus && TUK == TUK_Definition &&
       DC->getDeclKind() == Decl::Enum) {
     Diag(New->getLocation(), diag::err_type_defined_in_enum)
       << Context.getTagDeclType(New);
     Invalid = true;
   }
 
   // Maybe add qualifier info.
   if (SS.isNotEmpty()) {
     if (SS.isSet()) {
       // If this is either a declaration or a definition, check the
       // nested-name-specifier against the current context.
       if ((TUK == TUK_Definition || TUK == TUK_Declaration) &&
           diagnoseQualifiedDeclaration(SS, DC, OrigName, Loc,
                                        isMemberSpecialization))
         Invalid = true;
 
       New->setQualifierInfo(SS.getWithLocInContext(Context));
       if (TemplateParameterLists.size() > 0) {
         New->setTemplateParameterListsInfo(Context, TemplateParameterLists);
       }
     }
     else
       Invalid = true;
   }
 
   if (RecordDecl *RD = dyn_cast<RecordDecl>(New)) {
     // Add alignment attributes if necessary; these attributes are checked when
     // the ASTContext lays out the structure.
     //
     // It is important for implementing the correct semantics that this
     // happen here (in ActOnTag). The #pragma pack stack is
     // maintained as a result of parser callbacks which can occur at
     // many points during the parsing of a struct declaration (because
     // the #pragma tokens are effectively skipped over during the
     // parsing of the struct).
     if (TUK == TUK_Definition && (!SkipBody || !SkipBody->ShouldSkip)) {
       AddAlignmentAttributesForRecord(RD);
       AddMsStructLayoutForRecord(RD);
     }
   }
 
   if (ModulePrivateLoc.isValid()) {
     if (isMemberSpecialization)
       Diag(New->getLocation(), diag::err_module_private_specialization)
         << 2
         << FixItHint::CreateRemoval(ModulePrivateLoc);
     // __module_private__ does not apply to local classes. However, we only
     // diagnose this as an error when the declaration specifiers are
     // freestanding. Here, we just ignore the __module_private__.
     else if (!SearchDC->isFunctionOrMethod())
       New->setModulePrivate();
   }
 
   // If this is a specialization of a member class (of a class template),
   // check the specialization.
   if (isMemberSpecialization && CheckMemberSpecialization(New, Previous))
     Invalid = true;
 
   // If we're declaring or defining a tag in function prototype scope in C,
   // note that this type can only be used within the function and add it to
   // the list of decls to inject into the function definition scope.
   if ((Name || Kind == TTK_Enum) &&
       getNonFieldDeclScope(S)->isFunctionPrototypeScope()) {
     if (getLangOpts().CPlusPlus) {
       // C++ [dcl.fct]p6:
       //   Types shall not be defined in return or parameter types.
       if (TUK == TUK_Definition && !IsTypeSpecifier) {
         Diag(Loc, diag::err_type_defined_in_param_type)
             << Name;
         Invalid = true;
       }
     } else if (!PrevDecl) {
       Diag(Loc, diag::warn_decl_in_param_list) << Context.getTagDeclType(New);
     }
   }
 
   if (Invalid)
     New->setInvalidDecl();
 
   // Set the lexical context. If the tag has a C++ scope specifier, the
   // lexical context will be different from the semantic context.
   New->setLexicalDeclContext(CurContext);
 
   // Mark this as a friend decl if applicable.
   // In Microsoft mode, a friend declaration also acts as a forward
   // declaration so we always pass true to setObjectOfFriendDecl to make
   // the tag name visible.
   if (TUK == TUK_Friend)
     New->setObjectOfFriendDecl(getLangOpts().MSVCCompat);
 
   // Set the access specifier.
   if (!Invalid && SearchDC->isRecord())
     SetMemberAccessSpecifier(New, PrevDecl, AS);
 
   if (PrevDecl)
     CheckRedeclarationInModule(New, PrevDecl);
 
   if (TUK == TUK_Definition && (!SkipBody || !SkipBody->ShouldSkip))
     New->startDefinition();
 
   ProcessDeclAttributeList(S, New, Attrs);
   AddPragmaAttributes(S, New);
 
   // If this has an identifier, add it to the scope stack.
   if (TUK == TUK_Friend) {
     // We might be replacing an existing declaration in the lookup tables;
     // if so, borrow its access specifier.
     if (PrevDecl)
       New->setAccess(PrevDecl->getAccess());
 
     DeclContext *DC = New->getDeclContext()->getRedeclContext();
     DC->makeDeclVisibleInContext(New);
     if (Name) // can be null along some error paths
       if (Scope *EnclosingScope = getScopeForDeclContext(S, DC))
         PushOnScopeChains(New, EnclosingScope, /* AddToContext = */ false);
   } else if (Name) {
     S = getNonFieldDeclScope(S);
     PushOnScopeChains(New, S, true);
   } else {
     CurContext->addDecl(New);
   }
 
   // If this is the C FILE type, notify the AST context.
   if (IdentifierInfo *II = New->getIdentifier())
     if (!New->isInvalidDecl() &&
         New->getDeclContext()->getRedeclContext()->isTranslationUnit() &&
         II->isStr("FILE"))
       Context.setFILEDecl(New);
 
   if (PrevDecl)
     mergeDeclAttributes(New, PrevDecl);
 
   if (auto *CXXRD = dyn_cast<CXXRecordDecl>(New))
     inferGslOwnerPointerAttribute(CXXRD);
 
   // If there's a #pragma GCC visibility in scope, set the visibility of this
   // record.
   AddPushedVisibilityAttribute(New);
 
   if (isMemberSpecialization && !New->isInvalidDecl())
     CompleteMemberSpecialization(New, Previous);
 
   OwnedDecl = true;
   // In C++, don't return an invalid declaration. We can't recover well from
   // the cases where we make the type anonymous.
   if (Invalid && getLangOpts().CPlusPlus) {
     if (New->isBeingDefined())
       if (auto RD = dyn_cast<RecordDecl>(New))
         RD->completeDefinition();
     return true;
   } else if (SkipBody && SkipBody->ShouldSkip) {
     return SkipBody->Previous;
   } else {
     return New;
   }
 }
 
 void Sema::ActOnTagStartDefinition(Scope *S, Decl *TagD) {
   AdjustDeclIfTemplate(TagD);
   TagDecl *Tag = cast<TagDecl>(TagD);
 
   // Enter the tag context.
   PushDeclContext(S, Tag);
 
   ActOnDocumentableDecl(TagD);
 
   // If there's a #pragma GCC visibility in scope, set the visibility of this
   // record.
   AddPushedVisibilityAttribute(Tag);
 }
 
 bool Sema::ActOnDuplicateDefinition(Decl *Prev, SkipBodyInfo &SkipBody) {
   if (!hasStructuralCompatLayout(Prev, SkipBody.New))
     return false;
 
   // Make the previous decl visible.
   makeMergedDefinitionVisible(SkipBody.Previous);
   return true;
 }
 
 void Sema::ActOnObjCContainerStartDefinition(ObjCContainerDecl *IDecl) {
   assert(IDecl->getLexicalParent() == CurContext &&
       "The next DeclContext should be lexically contained in the current one.");
   CurContext = IDecl;
 }
 
 void Sema::ActOnStartCXXMemberDeclarations(Scope *S, Decl *TagD,
                                            SourceLocation FinalLoc,
                                            bool IsFinalSpelledSealed,
                                            bool IsAbstract,
                                            SourceLocation LBraceLoc) {
   AdjustDeclIfTemplate(TagD);
   CXXRecordDecl *Record = cast<CXXRecordDecl>(TagD);
 
   FieldCollector->StartClass();
 
   if (!Record->getIdentifier())
     return;
 
   if (IsAbstract)
     Record->markAbstract();
 
   if (FinalLoc.isValid()) {
     Record->addAttr(FinalAttr::Create(Context, FinalLoc,
                                       IsFinalSpelledSealed
                                           ? FinalAttr::Keyword_sealed
                                           : FinalAttr::Keyword_final));
   }
   // C++ [class]p2:
   //   [...] The class-name is also inserted into the scope of the
   //   class itself; this is known as the injected-class-name. For
   //   purposes of access checking, the injected-class-name is treated
   //   as if it were a public member name.
   CXXRecordDecl *InjectedClassName = CXXRecordDecl::Create(
       Context, Record->getTagKind(), CurContext, Record->getBeginLoc(),
       Record->getLocation(), Record->getIdentifier(),
       /*PrevDecl=*/nullptr,
       /*DelayTypeCreation=*/true);
   Context.getTypeDeclType(InjectedClassName, Record);
   InjectedClassName->setImplicit();
   InjectedClassName->setAccess(AS_public);
   if (ClassTemplateDecl *Template = Record->getDescribedClassTemplate())
       InjectedClassName->setDescribedClassTemplate(Template);
   PushOnScopeChains(InjectedClassName, S);
   assert(InjectedClassName->isInjectedClassName() &&
          "Broken injected-class-name");
 }
 
 void Sema::ActOnTagFinishDefinition(Scope *S, Decl *TagD,
                                     SourceRange BraceRange) {
   AdjustDeclIfTemplate(TagD);
   TagDecl *Tag = cast<TagDecl>(TagD);
   Tag->setBraceRange(BraceRange);
 
   // Make sure we "complete" the definition even it is invalid.
   if (Tag->isBeingDefined()) {
     assert(Tag->isInvalidDecl() && "We should already have completed it");
     if (RecordDecl *RD = dyn_cast<RecordDecl>(Tag))
       RD->completeDefinition();
   }
 
   if (auto *RD = dyn_cast<CXXRecordDecl>(Tag)) {
     FieldCollector->FinishClass();
     if (RD->hasAttr<SYCLSpecialClassAttr>()) {
       auto *Def = RD->getDefinition();
       assert(Def && "The record is expected to have a completed definition");
       unsigned NumInitMethods = 0;
       for (auto *Method : Def->methods()) {
         if (!Method->getIdentifier())
             continue;
         if (Method->getName() == "__init")
           NumInitMethods++;
       }
       if (NumInitMethods > 1 || !Def->hasInitMethod())
         Diag(RD->getLocation(), diag::err_sycl_special_type_num_init_method);
     }
   }
 
   // Exit this scope of this tag's definition.
   PopDeclContext();
 
   if (getCurLexicalContext()->isObjCContainer() &&
       Tag->getDeclContext()->isFileContext())
     Tag->setTopLevelDeclInObjCContainer();
 
   // Notify the consumer that we've defined a tag.
   if (!Tag->isInvalidDecl())
     Consumer.HandleTagDeclDefinition(Tag);
 
   // Clangs implementation of #pragma align(packed) differs in bitfield layout
   // from XLs and instead matches the XL #pragma pack(1) behavior.
   if (Context.getTargetInfo().getTriple().isOSAIX() &&
       AlignPackStack.hasValue()) {
     AlignPackInfo APInfo = AlignPackStack.CurrentValue;
     // Only diagnose #pragma align(packed).
     if (!APInfo.IsAlignAttr() || APInfo.getAlignMode() != AlignPackInfo::Packed)
       return;
     const RecordDecl *RD = dyn_cast<RecordDecl>(Tag);
     if (!RD)
       return;
     // Only warn if there is at least 1 bitfield member.
     if (llvm::any_of(RD->fields(),
                      [](const FieldDecl *FD) { return FD->isBitField(); }))
       Diag(BraceRange.getBegin(), diag::warn_pragma_align_not_xl_compatible);
   }
 }
 
 void Sema::ActOnObjCContainerFinishDefinition() {
   // Exit this scope of this interface definition.
   PopDeclContext();
 }
 
 void Sema::ActOnObjCTemporaryExitContainerContext(ObjCContainerDecl *ObjCCtx) {
   assert(ObjCCtx == CurContext && "Mismatch of container contexts");
   OriginalLexicalContext = ObjCCtx;
   ActOnObjCContainerFinishDefinition();
 }
 
 void Sema::ActOnObjCReenterContainerContext(ObjCContainerDecl *ObjCCtx) {
   ActOnObjCContainerStartDefinition(ObjCCtx);
   OriginalLexicalContext = nullptr;
 }
 
 void Sema::ActOnTagDefinitionError(Scope *S, Decl *TagD) {
   AdjustDeclIfTemplate(TagD);
   TagDecl *Tag = cast<TagDecl>(TagD);
   Tag->setInvalidDecl();
 
   // Make sure we "complete" the definition even it is invalid.
   if (Tag->isBeingDefined()) {
     if (RecordDecl *RD = dyn_cast<RecordDecl>(Tag))
       RD->completeDefinition();
   }
 
   // We're undoing ActOnTagStartDefinition here, not
   // ActOnStartCXXMemberDeclarations, so we don't have to mess with
   // the FieldCollector.
 
   PopDeclContext();
 }
 
 // Note that FieldName may be null for anonymous bitfields.
 ExprResult Sema::VerifyBitField(SourceLocation FieldLoc,
                                 IdentifierInfo *FieldName, QualType FieldTy,
                                 bool IsMsStruct, Expr *BitWidth) {
   assert(BitWidth);
   if (BitWidth->containsErrors())
     return ExprError();
 
   // C99 6.7.2.1p4 - verify the field type.
   // C++ 9.6p3: A bit-field shall have integral or enumeration type.
   if (!FieldTy->isDependentType() && !FieldTy->isIntegralOrEnumerationType()) {
     // Handle incomplete and sizeless types with a specific error.
     if (RequireCompleteSizedType(FieldLoc, FieldTy,
                                  diag::err_field_incomplete_or_sizeless))
       return ExprError();
     if (FieldName)
       return Diag(FieldLoc, diag::err_not_integral_type_bitfield)
         << FieldName << FieldTy << BitWidth->getSourceRange();
     return Diag(FieldLoc, diag::err_not_integral_type_anon_bitfield)
       << FieldTy << BitWidth->getSourceRange();
   } else if (DiagnoseUnexpandedParameterPack(const_cast<Expr *>(BitWidth),
                                              UPPC_BitFieldWidth))
     return ExprError();
 
   // If the bit-width is type- or value-dependent, don't try to check
   // it now.
   if (BitWidth->isValueDependent() || BitWidth->isTypeDependent())
     return BitWidth;
 
   llvm::APSInt Value;
   ExprResult ICE = VerifyIntegerConstantExpression(BitWidth, &Value, AllowFold);
   if (ICE.isInvalid())
     return ICE;
   BitWidth = ICE.get();
 
   // Zero-width bitfield is ok for anonymous field.
   if (Value == 0 && FieldName)
     return Diag(FieldLoc, diag::err_bitfield_has_zero_width) << FieldName;
 
   if (Value.isSigned() && Value.isNegative()) {
     if (FieldName)
       return Diag(FieldLoc, diag::err_bitfield_has_negative_width)
                << FieldName << toString(Value, 10);
     return Diag(FieldLoc, diag::err_anon_bitfield_has_negative_width)
       << toString(Value, 10);
   }
 
   // The size of the bit-field must not exceed our maximum permitted object
   // size.
   if (Value.getActiveBits() > ConstantArrayType::getMaxSizeBits(Context)) {
     return Diag(FieldLoc, diag::err_bitfield_too_wide)
            << !FieldName << FieldName << toString(Value, 10);
   }
 
   if (!FieldTy->isDependentType()) {
     uint64_t TypeStorageSize = Context.getTypeSize(FieldTy);
     uint64_t TypeWidth = Context.getIntWidth(FieldTy);
     bool BitfieldIsOverwide = Value.ugt(TypeWidth);
 
     // Over-wide bitfields are an error in C or when using the MSVC bitfield
     // ABI.
     bool CStdConstraintViolation =
         BitfieldIsOverwide && !getLangOpts().CPlusPlus;
     bool MSBitfieldViolation =
         Value.ugt(TypeStorageSize) &&
         (IsMsStruct || Context.getTargetInfo().getCXXABI().isMicrosoft());
     if (CStdConstraintViolation || MSBitfieldViolation) {
       unsigned DiagWidth =
           CStdConstraintViolation ? TypeWidth : TypeStorageSize;
       return Diag(FieldLoc, diag::err_bitfield_width_exceeds_type_width)
              << (bool)FieldName << FieldName << toString(Value, 10)
              << !CStdConstraintViolation << DiagWidth;
     }
 
     // Warn on types where the user might conceivably expect to get all
     // specified bits as value bits: that's all integral types other than
     // 'bool'.
     if (BitfieldIsOverwide && !FieldTy->isBooleanType() && FieldName) {
       Diag(FieldLoc, diag::warn_bitfield_width_exceeds_type_width)
           << FieldName << toString(Value, 10)
           << (unsigned)TypeWidth;
     }
   }
 
   return BitWidth;
 }
 
 /// ActOnField - Each field of a C struct/union is passed into this in order
 /// to create a FieldDecl object for it.
 Decl *Sema::ActOnField(Scope *S, Decl *TagD, SourceLocation DeclStart,
                        Declarator &D, Expr *BitfieldWidth) {
   FieldDecl *Res = HandleField(S, cast_or_null<RecordDecl>(TagD),
                                DeclStart, D, static_cast<Expr*>(BitfieldWidth),
                                /*InitStyle=*/ICIS_NoInit, AS_public);
   return Res;
 }
 
 /// HandleField - Analyze a field of a C struct or a C++ data member.
 ///
 FieldDecl *Sema::HandleField(Scope *S, RecordDecl *Record,
                              SourceLocation DeclStart,
                              Declarator &D, Expr *BitWidth,
                              InClassInitStyle InitStyle,
                              AccessSpecifier AS) {
   if (D.isDecompositionDeclarator()) {
     const DecompositionDeclarator &Decomp = D.getDecompositionDeclarator();
     Diag(Decomp.getLSquareLoc(), diag::err_decomp_decl_context)
       << Decomp.getSourceRange();
     return nullptr;
   }
 
   IdentifierInfo *II = D.getIdentifier();
   SourceLocation Loc = DeclStart;
   if (II) Loc = D.getIdentifierLoc();
 
   TypeSourceInfo *TInfo = GetTypeForDeclarator(D, S);
   QualType T = TInfo->getType();
   if (getLangOpts().CPlusPlus) {
     CheckExtraCXXDefaultArguments(D);
 
     if (DiagnoseUnexpandedParameterPack(D.getIdentifierLoc(), TInfo,
                                         UPPC_DataMemberType)) {
       D.setInvalidType();
       T = Context.IntTy;
       TInfo = Context.getTrivialTypeSourceInfo(T, Loc);
     }
   }
 
   DiagnoseFunctionSpecifiers(D.getDeclSpec());
 
   if (D.getDeclSpec().isInlineSpecified())
     Diag(D.getDeclSpec().getInlineSpecLoc(), diag::err_inline_non_function)
         << getLangOpts().CPlusPlus17;
   if (DeclSpec::TSCS TSCS = D.getDeclSpec().getThreadStorageClassSpec())
     Diag(D.getDeclSpec().getThreadStorageClassSpecLoc(),
          diag::err_invalid_thread)
       << DeclSpec::getSpecifierName(TSCS);
 
   // Check to see if this name was declared as a member previously
   NamedDecl *PrevDecl = nullptr;
   LookupResult Previous(*this, II, Loc, LookupMemberName,
                         ForVisibleRedeclaration);
   LookupName(Previous, S);
   switch (Previous.getResultKind()) {
     case LookupResult::Found:
     case LookupResult::FoundUnresolvedValue:
       PrevDecl = Previous.getAsSingle<NamedDecl>();
       break;
 
     case LookupResult::FoundOverloaded:
       PrevDecl = Previous.getRepresentativeDecl();
       break;
 
     case LookupResult::NotFound:
     case LookupResult::NotFoundInCurrentInstantiation:
     case LookupResult::Ambiguous:
       break;
   }
   Previous.suppressDiagnostics();
 
   if (PrevDecl && PrevDecl->isTemplateParameter()) {
     // Maybe we will complain about the shadowed template parameter.
     DiagnoseTemplateParameterShadow(D.getIdentifierLoc(), PrevDecl);
     // Just pretend that we didn't see the previous declaration.
     PrevDecl = nullptr;
   }
 
   if (PrevDecl && !isDeclInScope(PrevDecl, Record, S))
     PrevDecl = nullptr;
 
   bool Mutable
     = (D.getDeclSpec().getStorageClassSpec() == DeclSpec::SCS_mutable);
   SourceLocation TSSL = D.getBeginLoc();
   FieldDecl *NewFD
     = CheckFieldDecl(II, T, TInfo, Record, Loc, Mutable, BitWidth, InitStyle,
                      TSSL, AS, PrevDecl, &D);
 
   if (NewFD->isInvalidDecl())
     Record->setInvalidDecl();
 
   if (D.getDeclSpec().isModulePrivateSpecified())
     NewFD->setModulePrivate();
 
   if (NewFD->isInvalidDecl() && PrevDecl) {
     // Don't introduce NewFD into scope; there's already something
     // with the same name in the same scope.
   } else if (II) {
     PushOnScopeChains(NewFD, S);
   } else
     Record->addDecl(NewFD);
 
   return NewFD;
 }
 
 /// Build a new FieldDecl and check its well-formedness.
 ///
 /// This routine builds a new FieldDecl given the fields name, type,
 /// record, etc. \p PrevDecl should refer to any previous declaration
 /// with the same name and in the same scope as the field to be
 /// created.
 ///
 /// \returns a new FieldDecl.
 ///
 /// \todo The Declarator argument is a hack. It will be removed once
 FieldDecl *Sema::CheckFieldDecl(DeclarationName Name, QualType T,
                                 TypeSourceInfo *TInfo,
                                 RecordDecl *Record, SourceLocation Loc,
                                 bool Mutable, Expr *BitWidth,
                                 InClassInitStyle InitStyle,
                                 SourceLocation TSSL,
                                 AccessSpecifier AS, NamedDecl *PrevDecl,
                                 Declarator *D) {
   IdentifierInfo *II = Name.getAsIdentifierInfo();
   bool InvalidDecl = false;
   if (D) InvalidDecl = D->isInvalidType();
 
   // If we receive a broken type, recover by assuming 'int' and
   // marking this declaration as invalid.
   if (T.isNull() || T->containsErrors()) {
     InvalidDecl = true;
     T = Context.IntTy;
   }
 
   QualType EltTy = Context.getBaseElementType(T);
   if (!EltTy->isDependentType() && !EltTy->containsErrors()) {
     if (RequireCompleteSizedType(Loc, EltTy,
                                  diag::err_field_incomplete_or_sizeless)) {
       // Fields of incomplete type force their record to be invalid.
       Record->setInvalidDecl();
       InvalidDecl = true;
     } else {
       NamedDecl *Def;
       EltTy->isIncompleteType(&Def);
       if (Def && Def->isInvalidDecl()) {
         Record->setInvalidDecl();
         InvalidDecl = true;
       }
     }
   }
 
   // TR 18037 does not allow fields to be declared with address space
   if (T.hasAddressSpace() || T->isDependentAddressSpaceType() ||
       T->getBaseElementTypeUnsafe()->isDependentAddressSpaceType()) {
     Diag(Loc, diag::err_field_with_address_space);
     Record->setInvalidDecl();
     InvalidDecl = true;
   }
 
   if (LangOpts.OpenCL) {
     // OpenCL v1.2 s6.9b,r & OpenCL v2.0 s6.12.5 - The following types cannot be
     // used as structure or union field: image, sampler, event or block types.
     if (T->isEventT() || T->isImageType() || T->isSamplerT() ||
         T->isBlockPointerType()) {
       Diag(Loc, diag::err_opencl_type_struct_or_union_field) << T;
       Record->setInvalidDecl();
       InvalidDecl = true;
     }
     // OpenCL v1.2 s6.9.c: bitfields are not supported, unless Clang extension
     // is enabled.
     if (BitWidth && !getOpenCLOptions().isAvailableOption(
                         "__cl_clang_bitfields", LangOpts)) {
       Diag(Loc, diag::err_opencl_bitfields);
       InvalidDecl = true;
     }
   }
 
   // Anonymous bit-fields cannot be cv-qualified (CWG 2229).
   if (!InvalidDecl && getLangOpts().CPlusPlus && !II && BitWidth &&
       T.hasQualifiers()) {
     InvalidDecl = true;
     Diag(Loc, diag::err_anon_bitfield_qualifiers);
   }
 
   // C99 6.7.2.1p8: A member of a structure or union may have any type other
   // than a variably modified type.
   if (!InvalidDecl && T->isVariablyModifiedType()) {
     if (!tryToFixVariablyModifiedVarType(
             TInfo, T, Loc, diag::err_typecheck_field_variable_size))
       InvalidDecl = true;
   }
 
   // Fields can not have abstract class types
   if (!InvalidDecl && RequireNonAbstractType(Loc, T,
                                              diag::err_abstract_type_in_decl,
                                              AbstractFieldType))
     InvalidDecl = true;
 
   if (InvalidDecl)
     BitWidth = nullptr;
   // If this is declared as a bit-field, check the bit-field.
   if (BitWidth) {
     BitWidth =
         VerifyBitField(Loc, II, T, Record->isMsStruct(Context), BitWidth).get();
     if (!BitWidth) {
       InvalidDecl = true;
       BitWidth = nullptr;
     }
   }
 
   // Check that 'mutable' is consistent with the type of the declaration.
   if (!InvalidDecl && Mutable) {
     unsigned DiagID = 0;
     if (T->isReferenceType())
       DiagID = getLangOpts().MSVCCompat ? diag::ext_mutable_reference
                                         : diag::err_mutable_reference;
     else if (T.isConstQualified())
       DiagID = diag::err_mutable_const;
 
     if (DiagID) {
       SourceLocation ErrLoc = Loc;
       if (D && D->getDeclSpec().getStorageClassSpecLoc().isValid())
         ErrLoc = D->getDeclSpec().getStorageClassSpecLoc();
       Diag(ErrLoc, DiagID);
       if (DiagID != diag::ext_mutable_reference) {
         Mutable = false;
         InvalidDecl = true;
       }
     }
   }
 
   // C++11 [class.union]p8 (DR1460):
   //   At most one variant member of a union may have a
   //   brace-or-equal-initializer.
   if (InitStyle != ICIS_NoInit)
     checkDuplicateDefaultInit(*this, cast<CXXRecordDecl>(Record), Loc);
 
   FieldDecl *NewFD = FieldDecl::Create(Context, Record, TSSL, Loc, II, T, TInfo,
                                        BitWidth, Mutable, InitStyle);
   if (InvalidDecl)
     NewFD->setInvalidDecl();
 
   if (PrevDecl && !isa<TagDecl>(PrevDecl)) {
     Diag(Loc, diag::err_duplicate_member) << II;
     Diag(PrevDecl->getLocation(), diag::note_previous_declaration);
     NewFD->setInvalidDecl();
   }
 
   if (!InvalidDecl && getLangOpts().CPlusPlus) {
     if (Record->isUnion()) {
       if (const RecordType *RT = EltTy->getAs<RecordType>()) {
         CXXRecordDecl* RDecl = cast<CXXRecordDecl>(RT->getDecl());
         if (RDecl->getDefinition()) {
           // C++ [class.union]p1: An object of a class with a non-trivial
           // constructor, a non-trivial copy constructor, a non-trivial
           // destructor, or a non-trivial copy assignment operator
           // cannot be a member of a union, nor can an array of such
           // objects.
           if (CheckNontrivialField(NewFD))
             NewFD->setInvalidDecl();
         }
       }
 
       // C++ [class.union]p1: If a union contains a member of reference type,
       // the program is ill-formed, except when compiling with MSVC extensions
       // enabled.
       if (EltTy->isReferenceType()) {
         Diag(NewFD->getLocation(), getLangOpts().MicrosoftExt ?
                                     diag::ext_union_member_of_reference_type :
                                     diag::err_union_member_of_reference_type)
           << NewFD->getDeclName() << EltTy;
         if (!getLangOpts().MicrosoftExt)
           NewFD->setInvalidDecl();
       }
     }
   }
 
   // FIXME: We need to pass in the attributes given an AST
   // representation, not a parser representation.
   if (D) {
     // FIXME: The current scope is almost... but not entirely... correct here.
     ProcessDeclAttributes(getCurScope(), NewFD, *D);
 
     if (NewFD->hasAttrs())
       CheckAlignasUnderalignment(NewFD);
   }
 
   // In auto-retain/release, infer strong retension for fields of
   // retainable type.
   if (getLangOpts().ObjCAutoRefCount && inferObjCARCLifetime(NewFD))
     NewFD->setInvalidDecl();
 
   if (T.isObjCGCWeak())
     Diag(Loc, diag::warn_attribute_weak_on_field);
 
   // PPC MMA non-pointer types are not allowed as field types.
   if (Context.getTargetInfo().getTriple().isPPC64() &&
       CheckPPCMMAType(T, NewFD->getLocation()))
     NewFD->setInvalidDecl();
 
   NewFD->setAccess(AS);
   return NewFD;
 }
 
 bool Sema::CheckNontrivialField(FieldDecl *FD) {
   assert(FD);
   assert(getLangOpts().CPlusPlus && "valid check only for C++");
 
   if (FD->isInvalidDecl() || FD->getType()->isDependentType())
     return false;
 
   QualType EltTy = Context.getBaseElementType(FD->getType());
   if (const RecordType *RT = EltTy->getAs<RecordType>()) {
     CXXRecordDecl *RDecl = cast<CXXRecordDecl>(RT->getDecl());
     if (RDecl->getDefinition()) {
       // We check for copy constructors before constructors
       // because otherwise we'll never get complaints about
       // copy constructors.
 
       CXXSpecialMember member = CXXInvalid;
       // We're required to check for any non-trivial constructors. Since the
       // implicit default constructor is suppressed if there are any
       // user-declared constructors, we just need to check that there is a
       // trivial default constructor and a trivial copy constructor. (We don't
       // worry about move constructors here, since this is a C++98 check.)
       if (RDecl->hasNonTrivialCopyConstructor())
         member = CXXCopyConstructor;
       else if (!RDecl->hasTrivialDefaultConstructor())
         member = CXXDefaultConstructor;
       else if (RDecl->hasNonTrivialCopyAssignment())
         member = CXXCopyAssignment;
       else if (RDecl->hasNonTrivialDestructor())
         member = CXXDestructor;
 
       if (member != CXXInvalid) {
         if (!getLangOpts().CPlusPlus11 &&
             getLangOpts().ObjCAutoRefCount && RDecl->hasObjectMember()) {
           // Objective-C++ ARC: it is an error to have a non-trivial field of
           // a union. However, system headers in Objective-C programs
           // occasionally have Objective-C lifetime objects within unions,
           // and rather than cause the program to fail, we make those
           // members unavailable.
           SourceLocation Loc = FD->getLocation();
           if (getSourceManager().isInSystemHeader(Loc)) {
             if (!FD->hasAttr<UnavailableAttr>())
               FD->addAttr(UnavailableAttr::CreateImplicit(Context, "",
                             UnavailableAttr::IR_ARCFieldWithOwnership, Loc));
             return false;
           }
         }
 
         Diag(FD->getLocation(), getLangOpts().CPlusPlus11 ?
                diag::warn_cxx98_compat_nontrivial_union_or_anon_struct_member :
                diag::err_illegal_union_or_anon_struct_member)
           << FD->getParent()->isUnion() << FD->getDeclName() << member;
         DiagnoseNontrivial(RDecl, member);
         return !getLangOpts().CPlusPlus11;
       }
     }
   }
 
   return false;
 }
 
 /// TranslateIvarVisibility - Translate visibility from a token ID to an
 ///  AST enum value.
 static ObjCIvarDecl::AccessControl
 TranslateIvarVisibility(tok::ObjCKeywordKind ivarVisibility) {
   switch (ivarVisibility) {
   default: llvm_unreachable("Unknown visitibility kind");
   case tok::objc_private: return ObjCIvarDecl::Private;
   case tok::objc_public: return ObjCIvarDecl::Public;
   case tok::objc_protected: return ObjCIvarDecl::Protected;
   case tok::objc_package: return ObjCIvarDecl::Package;
   }
 }
 
 /// ActOnIvar - Each ivar field of an objective-c class is passed into this
 /// in order to create an IvarDecl object for it.
 Decl *Sema::ActOnIvar(Scope *S,
                                 SourceLocation DeclStart,
                                 Declarator &D, Expr *BitfieldWidth,
                                 tok::ObjCKeywordKind Visibility) {
 
   IdentifierInfo *II = D.getIdentifier();
   Expr *BitWidth = (Expr*)BitfieldWidth;
   SourceLocation Loc = DeclStart;
   if (II) Loc = D.getIdentifierLoc();
 
   // FIXME: Unnamed fields can be handled in various different ways, for
   // example, unnamed unions inject all members into the struct namespace!
 
   TypeSourceInfo *TInfo = GetTypeForDeclarator(D, S);
   QualType T = TInfo->getType();
 
   if (BitWidth) {
     // 6.7.2.1p3, 6.7.2.1p4
     BitWidth = VerifyBitField(Loc, II, T, /*IsMsStruct*/false, BitWidth).get();
     if (!BitWidth)
       D.setInvalidType();
   } else {
     // Not a bitfield.
 
     // validate II.
 
   }
   if (T->isReferenceType()) {
     Diag(Loc, diag::err_ivar_reference_type);
     D.setInvalidType();
   }
   // C99 6.7.2.1p8: A member of a structure or union may have any type other
   // than a variably modified type.
   else if (T->isVariablyModifiedType()) {
     if (!tryToFixVariablyModifiedVarType(
             TInfo, T, Loc, diag::err_typecheck_ivar_variable_size))
       D.setInvalidType();
   }
 
   // Get the visibility (access control) for this ivar.
   ObjCIvarDecl::AccessControl ac =
     Visibility != tok::objc_not_keyword ? TranslateIvarVisibility(Visibility)
                                         : ObjCIvarDecl::None;
   // Must set ivar's DeclContext to its enclosing interface.
   ObjCContainerDecl *EnclosingDecl = cast<ObjCContainerDecl>(CurContext);
   if (!EnclosingDecl || EnclosingDecl->isInvalidDecl())
     return nullptr;
   ObjCContainerDecl *EnclosingContext;
   if (ObjCImplementationDecl *IMPDecl =
       dyn_cast<ObjCImplementationDecl>(EnclosingDecl)) {
     if (LangOpts.ObjCRuntime.isFragile()) {
     // Case of ivar declared in an implementation. Context is that of its class.
       EnclosingContext = IMPDecl->getClassInterface();
       assert(EnclosingContext && "Implementation has no class interface!");
     }
     else
       EnclosingContext = EnclosingDecl;
   } else {
     if (ObjCCategoryDecl *CDecl =
         dyn_cast<ObjCCategoryDecl>(EnclosingDecl)) {
       if (LangOpts.ObjCRuntime.isFragile() || !CDecl->IsClassExtension()) {
         Diag(Loc, diag::err_misplaced_ivar) << CDecl->IsClassExtension();
         return nullptr;
       }
     }
     EnclosingContext = EnclosingDecl;
   }
 
   // Construct the decl.
   ObjCIvarDecl *NewID = ObjCIvarDecl::Create(Context, EnclosingContext,
                                              DeclStart, Loc, II, T,
                                              TInfo, ac, (Expr *)BitfieldWidth);
 
   if (II) {
     NamedDecl *PrevDecl = LookupSingleName(S, II, Loc, LookupMemberName,
                                            ForVisibleRedeclaration);
     if (PrevDecl && isDeclInScope(PrevDecl, EnclosingContext, S)
         && !isa<TagDecl>(PrevDecl)) {
       Diag(Loc, diag::err_duplicate_member) << II;
       Diag(PrevDecl->getLocation(), diag::note_previous_declaration);
       NewID->setInvalidDecl();
     }
   }
 
   // Process attributes attached to the ivar.
   ProcessDeclAttributes(S, NewID, D);
 
   if (D.isInvalidType())
     NewID->setInvalidDecl();
 
   // In ARC, infer 'retaining' for ivars of retainable type.
   if (getLangOpts().ObjCAutoRefCount && inferObjCARCLifetime(NewID))
     NewID->setInvalidDecl();
 
   if (D.getDeclSpec().isModulePrivateSpecified())
     NewID->setModulePrivate();
 
   if (II) {
     // FIXME: When interfaces are DeclContexts, we'll need to add
     // these to the interface.
     S->AddDecl(NewID);
     IdResolver.AddDecl(NewID);
   }
 
   if (LangOpts.ObjCRuntime.isNonFragile() &&
       !NewID->isInvalidDecl() && isa<ObjCInterfaceDecl>(EnclosingDecl))
     Diag(Loc, diag::warn_ivars_in_interface);
 
   return NewID;
 }
 
 /// ActOnLastBitfield - This routine handles synthesized bitfields rules for
 /// class and class extensions. For every class \@interface and class
 /// extension \@interface, if the last ivar is a bitfield of any type,
 /// then add an implicit `char :0` ivar to the end of that interface.
 void Sema::ActOnLastBitfield(SourceLocation DeclLoc,
                              SmallVectorImpl<Decl *> &AllIvarDecls) {
   if (LangOpts.ObjCRuntime.isFragile() || AllIvarDecls.empty())
     return;
 
   Decl *ivarDecl = AllIvarDecls[AllIvarDecls.size()-1];
   ObjCIvarDecl *Ivar = cast<ObjCIvarDecl>(ivarDecl);
 
   if (!Ivar->isBitField() || Ivar->isZeroLengthBitField(Context))
     return;
   ObjCInterfaceDecl *ID = dyn_cast<ObjCInterfaceDecl>(CurContext);
   if (!ID) {
     if (ObjCCategoryDecl *CD = dyn_cast<ObjCCategoryDecl>(CurContext)) {
       if (!CD->IsClassExtension())
         return;
     }
     // No need to add this to end of @implementation.
     else
       return;
   }
   // All conditions are met. Add a new bitfield to the tail end of ivars.
   llvm::APInt Zero(Context.getTypeSize(Context.IntTy), 0);
   Expr * BW = IntegerLiteral::Create(Context, Zero, Context.IntTy, DeclLoc);
 
   Ivar = ObjCIvarDecl::Create(Context, cast<ObjCContainerDecl>(CurContext),
                               DeclLoc, DeclLoc, nullptr,
                               Context.CharTy,
                               Context.getTrivialTypeSourceInfo(Context.CharTy,
                                                                DeclLoc),
                               ObjCIvarDecl::Private, BW,
                               true);
   AllIvarDecls.push_back(Ivar);
 }
 
 /// [class.dtor]p4:
 ///   At the end of the definition of a class, overload resolution is
 ///   performed among the prospective destructors declared in that class with
 ///   an empty argument list to select the destructor for the class, also
 ///   known as the selected destructor.
 ///
 /// We do the overload resolution here, then mark the selected constructor in the AST.
 /// Later CXXRecordDecl::getDestructor() will return the selected constructor.
 static void ComputeSelectedDestructor(Sema &S, CXXRecordDecl *Record) {
   if (!Record->hasUserDeclaredDestructor()) {
     return;
   }
 
   SourceLocation Loc = Record->getLocation();
   OverloadCandidateSet OCS(Loc, OverloadCandidateSet::CSK_Normal);
 
   for (auto *Decl : Record->decls()) {
     if (auto *DD = dyn_cast<CXXDestructorDecl>(Decl)) {
       if (DD->isInvalidDecl())
         continue;
       S.AddOverloadCandidate(DD, DeclAccessPair::make(DD, DD->getAccess()), {},
                              OCS);
       assert(DD->isIneligibleOrNotSelected() && "Selecting a destructor but a destructor was already selected.");
     }
   }
 
   if (OCS.empty()) {
     return;
   }
   OverloadCandidateSet::iterator Best;
   unsigned Msg = 0;
   OverloadCandidateDisplayKind DisplayKind;
 
   switch (OCS.BestViableFunction(S, Loc, Best)) {
   case OR_Success:
   case OR_Deleted:
     Record->addedSelectedDestructor(dyn_cast<CXXDestructorDecl>(Best->Function));
     break;
 
   case OR_Ambiguous:
     Msg = diag::err_ambiguous_destructor;
     DisplayKind = OCD_AmbiguousCandidates;
     break;
 
   case OR_No_Viable_Function:
     Msg = diag::err_no_viable_destructor;
     DisplayKind = OCD_AllCandidates;
     break;
   }
 
   if (Msg) {
     // OpenCL have got their own thing going with destructors. It's slightly broken,
     // but we allow it.
     if (!S.LangOpts.OpenCL) {
       PartialDiagnostic Diag = S.PDiag(Msg) << Record;
       OCS.NoteCandidates(PartialDiagnosticAt(Loc, Diag), S, DisplayKind, {});
       Record->setInvalidDecl();
     }
     // It's a bit hacky: At this point we've raised an error but we want the
     // rest of the compiler to continue somehow working. However almost
     // everything we'll try to do with the class will depend on there being a
     // destructor. So let's pretend the first one is selected and hope for the
     // best.
     Record->addedSelectedDestructor(dyn_cast<CXXDestructorDecl>(OCS.begin()->Function));
   }
 }
 
 /// [class.mem.special]p5
 /// Two special member functions are of the same kind if:
 /// - they are both default constructors,
 /// - they are both copy or move constructors with the same first parameter
 ///   type, or
 /// - they are both copy or move assignment operators with the same first
 ///   parameter type and the same cv-qualifiers and ref-qualifier, if any.
 static bool AreSpecialMemberFunctionsSameKind(ASTContext &Context,
                                               CXXMethodDecl *M1,
                                               CXXMethodDecl *M2,
                                               Sema::CXXSpecialMember CSM) {
   // We don't want to compare templates to non-templates: See
   // https://github.com/llvm/llvm-project/issues/59206
   if (CSM == Sema::CXXDefaultConstructor)
     return bool(M1->getDescribedFunctionTemplate()) ==
            bool(M2->getDescribedFunctionTemplate());
   if (!Context.hasSameType(M1->getParamDecl(0)->getType(),
                            M2->getParamDecl(0)->getType()))
     return false;
   if (!Context.hasSameType(M1->getThisType(), M2->getThisType()))
     return false;
 
   return true;
 }
 
 /// [class.mem.special]p6:
 /// An eligible special member function is a special member function for which:
 /// - the function is not deleted,
 /// - the associated constraints, if any, are satisfied, and
 /// - no special member function of the same kind whose associated constraints
 ///   [CWG2595], if any, are satisfied is more constrained.
 static void SetEligibleMethods(Sema &S, CXXRecordDecl *Record,
                                ArrayRef<CXXMethodDecl *> Methods,
                                Sema::CXXSpecialMember CSM) {
   SmallVector<bool, 4> SatisfactionStatus;
 
   for (CXXMethodDecl *Method : Methods) {
     const Expr *Constraints = Method->getTrailingRequiresClause();
     if (!Constraints)
       SatisfactionStatus.push_back(true);
     else {
       ConstraintSatisfaction Satisfaction;
       if (S.CheckFunctionConstraints(Method, Satisfaction))
         SatisfactionStatus.push_back(false);
       else
         SatisfactionStatus.push_back(Satisfaction.IsSatisfied);
     }
   }
 
   for (size_t i = 0; i < Methods.size(); i++) {
     if (!SatisfactionStatus[i])
       continue;
     CXXMethodDecl *Method = Methods[i];
     CXXMethodDecl *OrigMethod = Method;
     if (FunctionDecl *MF = OrigMethod->getInstantiatedFromMemberFunction())
       OrigMethod = cast<CXXMethodDecl>(MF);
 
     const Expr *Constraints = OrigMethod->getTrailingRequiresClause();
     bool AnotherMethodIsMoreConstrained = false;
     for (size_t j = 0; j < Methods.size(); j++) {
       if (i == j || !SatisfactionStatus[j])
         continue;
       CXXMethodDecl *OtherMethod = Methods[j];
       if (FunctionDecl *MF = OtherMethod->getInstantiatedFromMemberFunction())
         OtherMethod = cast<CXXMethodDecl>(MF);
 
       if (!AreSpecialMemberFunctionsSameKind(S.Context, OrigMethod, OtherMethod,
                                              CSM))
         continue;
 
       const Expr *OtherConstraints = OtherMethod->getTrailingRequiresClause();
       if (!OtherConstraints)
         continue;
       if (!Constraints) {
         AnotherMethodIsMoreConstrained = true;
         break;
       }
       if (S.IsAtLeastAsConstrained(OtherMethod, {OtherConstraints}, OrigMethod,
                                    {Constraints},
                                    AnotherMethodIsMoreConstrained)) {
         // There was an error with the constraints comparison. Exit the loop
         // and don't consider this function eligible.
         AnotherMethodIsMoreConstrained = true;
       }
       if (AnotherMethodIsMoreConstrained)
         break;
     }
     // FIXME: Do not consider deleted methods as eligible after implementing
     // DR1734 and DR1496.
     if (!AnotherMethodIsMoreConstrained) {
       Method->setIneligibleOrNotSelected(false);
       Record->addedEligibleSpecialMemberFunction(Method, 1 << CSM);
     }
   }
 }
 
 static void ComputeSpecialMemberFunctionsEligiblity(Sema &S,
                                                     CXXRecordDecl *Record) {
   SmallVector<CXXMethodDecl *, 4> DefaultConstructors;
   SmallVector<CXXMethodDecl *, 4> CopyConstructors;
   SmallVector<CXXMethodDecl *, 4> MoveConstructors;
   SmallVector<CXXMethodDecl *, 4> CopyAssignmentOperators;
   SmallVector<CXXMethodDecl *, 4> MoveAssignmentOperators;
 
   for (auto *Decl : Record->decls()) {
     auto *MD = dyn_cast<CXXMethodDecl>(Decl);
     if (!MD) {
       auto *FTD = dyn_cast<FunctionTemplateDecl>(Decl);
       if (FTD)
         MD = dyn_cast<CXXMethodDecl>(FTD->getTemplatedDecl());
     }
     if (!MD)
       continue;
     if (auto *CD = dyn_cast<CXXConstructorDecl>(MD)) {
       if (CD->isInvalidDecl())
         continue;
       if (CD->isDefaultConstructor())
         DefaultConstructors.push_back(MD);
       else if (CD->isCopyConstructor())
         CopyConstructors.push_back(MD);
       else if (CD->isMoveConstructor())
         MoveConstructors.push_back(MD);
     } else if (MD->isCopyAssignmentOperator()) {
       CopyAssignmentOperators.push_back(MD);
     } else if (MD->isMoveAssignmentOperator()) {
       MoveAssignmentOperators.push_back(MD);
     }
   }
 
   SetEligibleMethods(S, Record, DefaultConstructors,
                      Sema::CXXDefaultConstructor);
   SetEligibleMethods(S, Record, CopyConstructors, Sema::CXXCopyConstructor);
   SetEligibleMethods(S, Record, MoveConstructors, Sema::CXXMoveConstructor);
   SetEligibleMethods(S, Record, CopyAssignmentOperators,
                      Sema::CXXCopyAssignment);
   SetEligibleMethods(S, Record, MoveAssignmentOperators,
                      Sema::CXXMoveAssignment);
 }
 
 void Sema::ActOnFields(Scope *S, SourceLocation RecLoc, Decl *EnclosingDecl,
                        ArrayRef<Decl *> Fields, SourceLocation LBrac,
                        SourceLocation RBrac,
                        const ParsedAttributesView &Attrs) {
   assert(EnclosingDecl && "missing record or interface decl");
 
   // If this is an Objective-C @implementation or category and we have
   // new fields here we should reset the layout of the interface since
   // it will now change.
   if (!Fields.empty() && isa<ObjCContainerDecl>(EnclosingDecl)) {
     ObjCContainerDecl *DC = cast<ObjCContainerDecl>(EnclosingDecl);
     switch (DC->getKind()) {
     default: break;
     case Decl::ObjCCategory:
       Context.ResetObjCLayout(cast<ObjCCategoryDecl>(DC)->getClassInterface());
       break;
     case Decl::ObjCImplementation:
       Context.
         ResetObjCLayout(cast<ObjCImplementationDecl>(DC)->getClassInterface());
       break;
     }
   }
 
   RecordDecl *Record = dyn_cast<RecordDecl>(EnclosingDecl);
   CXXRecordDecl *CXXRecord = dyn_cast<CXXRecordDecl>(EnclosingDecl);
 
   // Start counting up the number of named members; make sure to include
   // members of anonymous structs and unions in the total.
   unsigned NumNamedMembers = 0;
   if (Record) {
     for (const auto *I : Record->decls()) {
       if (const auto *IFD = dyn_cast<IndirectFieldDecl>(I))
         if (IFD->getDeclName())
           ++NumNamedMembers;
     }
   }
 
   // Verify that all the fields are okay.
   SmallVector<FieldDecl*, 32> RecFields;
 
   for (ArrayRef<Decl *>::iterator i = Fields.begin(), end = Fields.end();
        i != end; ++i) {
     FieldDecl *FD = cast<FieldDecl>(*i);
 
     // Get the type for the field.
     const Type *FDTy = FD->getType().getTypePtr();
 
     if (!FD->isAnonymousStructOrUnion()) {
       // Remember all fields written by the user.
       RecFields.push_back(FD);
     }
 
     // If the field is already invalid for some reason, don't emit more
     // diagnostics about it.
     if (FD->isInvalidDecl()) {
       EnclosingDecl->setInvalidDecl();
       continue;
     }
 
     // C99 6.7.2.1p2:
     //   A structure or union shall not contain a member with
     //   incomplete or function type (hence, a structure shall not
     //   contain an instance of itself, but may contain a pointer to
     //   an instance of itself), except that the last member of a
     //   structure with more than one named member may have incomplete
     //   array type; such a structure (and any union containing,
     //   possibly recursively, a member that is such a structure)
     //   shall not be a member of a structure or an element of an
     //   array.
     bool IsLastField = (i + 1 == Fields.end());
     if (FDTy->isFunctionType()) {
       // Field declared as a function.
       Diag(FD->getLocation(), diag::err_field_declared_as_function)
         << FD->getDeclName();
       FD->setInvalidDecl();
       EnclosingDecl->setInvalidDecl();
       continue;
     } else if (FDTy->isIncompleteArrayType() &&
                (Record || isa<ObjCContainerDecl>(EnclosingDecl))) {
       if (Record) {
         // Flexible array member.
         // Microsoft and g++ is more permissive regarding flexible array.
         // It will accept flexible array in union and also
         // as the sole element of a struct/class.
         unsigned DiagID = 0;
         if (!Record->isUnion() && !IsLastField) {
           Diag(FD->getLocation(), diag::err_flexible_array_not_at_end)
             << FD->getDeclName() << FD->getType() << Record->getTagKind();
           Diag((*(i + 1))->getLocation(), diag::note_next_field_declaration);
           FD->setInvalidDecl();
           EnclosingDecl->setInvalidDecl();
           continue;
         } else if (Record->isUnion())
           DiagID = getLangOpts().MicrosoftExt
                        ? diag::ext_flexible_array_union_ms
                        : getLangOpts().CPlusPlus
                              ? diag::ext_flexible_array_union_gnu
                              : diag::err_flexible_array_union;
         else if (NumNamedMembers < 1)
           DiagID = getLangOpts().MicrosoftExt
                        ? diag::ext_flexible_array_empty_aggregate_ms
                        : getLangOpts().CPlusPlus
                              ? diag::ext_flexible_array_empty_aggregate_gnu
                              : diag::err_flexible_array_empty_aggregate;
 
         if (DiagID)
           Diag(FD->getLocation(), DiagID) << FD->getDeclName()
                                           << Record->getTagKind();
         // While the layout of types that contain virtual bases is not specified
         // by the C++ standard, both the Itanium and Microsoft C++ ABIs place
         // virtual bases after the derived members.  This would make a flexible
         // array member declared at the end of an object not adjacent to the end
         // of the type.
         if (CXXRecord && CXXRecord->getNumVBases() != 0)
           Diag(FD->getLocation(), diag::err_flexible_array_virtual_base)
               << FD->getDeclName() << Record->getTagKind();
         if (!getLangOpts().C99)
           Diag(FD->getLocation(), diag::ext_c99_flexible_array_member)
             << FD->getDeclName() << Record->getTagKind();
 
         // If the element type has a non-trivial destructor, we would not
         // implicitly destroy the elements, so disallow it for now.
         //
         // FIXME: GCC allows this. We should probably either implicitly delete
         // the destructor of the containing class, or just allow this.
         QualType BaseElem = Context.getBaseElementType(FD->getType());
         if (!BaseElem->isDependentType() && BaseElem.isDestructedType()) {
           Diag(FD->getLocation(), diag::err_flexible_array_has_nontrivial_dtor)
             << FD->getDeclName() << FD->getType();
           FD->setInvalidDecl();
           EnclosingDecl->setInvalidDecl();
           continue;
         }
         // Okay, we have a legal flexible array member at the end of the struct.
         Record->setHasFlexibleArrayMember(true);
       } else {
         // In ObjCContainerDecl ivars with incomplete array type are accepted,
         // unless they are followed by another ivar. That check is done
         // elsewhere, after synthesized ivars are known.
       }
     } else if (!FDTy->isDependentType() &&
                RequireCompleteSizedType(
                    FD->getLocation(), FD->getType(),
                    diag::err_field_incomplete_or_sizeless)) {
       // Incomplete type
       FD->setInvalidDecl();
       EnclosingDecl->setInvalidDecl();
       continue;
     } else if (const RecordType *FDTTy = FDTy->getAs<RecordType>()) {
       if (Record && FDTTy->getDecl()->hasFlexibleArrayMember()) {
         // A type which contains a flexible array member is considered to be a
         // flexible array member.
         Record->setHasFlexibleArrayMember(true);
         if (!Record->isUnion()) {
           // If this is a struct/class and this is not the last element, reject
           // it.  Note that GCC supports variable sized arrays in the middle of
           // structures.
           if (!IsLastField)
             Diag(FD->getLocation(), diag::ext_variable_sized_type_in_struct)
               << FD->getDeclName() << FD->getType();
           else {
             // We support flexible arrays at the end of structs in
             // other structs as an extension.
             Diag(FD->getLocation(), diag::ext_flexible_array_in_struct)
               << FD->getDeclName();
           }
         }
       }
       if (isa<ObjCContainerDecl>(EnclosingDecl) &&
           RequireNonAbstractType(FD->getLocation(), FD->getType(),
                                  diag::err_abstract_type_in_decl,
                                  AbstractIvarType)) {
         // Ivars can not have abstract class types
         FD->setInvalidDecl();
       }
       if (Record && FDTTy->getDecl()->hasObjectMember())
         Record->setHasObjectMember(true);
       if (Record && FDTTy->getDecl()->hasVolatileMember())
         Record->setHasVolatileMember(true);
     } else if (FDTy->isObjCObjectType()) {
       /// A field cannot be an Objective-c object
       Diag(FD->getLocation(), diag::err_statically_allocated_object)
         << FixItHint::CreateInsertion(FD->getLocation(), "*");
       QualType T = Context.getObjCObjectPointerType(FD->getType());
       FD->setType(T);
     } else if (Record && Record->isUnion() &&
                FD->getType().hasNonTrivialObjCLifetime() &&
                getSourceManager().isInSystemHeader(FD->getLocation()) &&
                !getLangOpts().CPlusPlus && !FD->hasAttr<UnavailableAttr>() &&
                (FD->getType().getObjCLifetime() != Qualifiers::OCL_Strong ||
                 !Context.hasDirectOwnershipQualifier(FD->getType()))) {
       // For backward compatibility, fields of C unions declared in system
       // headers that have non-trivial ObjC ownership qualifications are marked
       // as unavailable unless the qualifier is explicit and __strong. This can
       // break ABI compatibility between programs compiled with ARC and MRR, but
       // is a better option than rejecting programs using those unions under
       // ARC.
       FD->addAttr(UnavailableAttr::CreateImplicit(
           Context, "", UnavailableAttr::IR_ARCFieldWithOwnership,
           FD->getLocation()));
     } else if (getLangOpts().ObjC &&
                getLangOpts().getGC() != LangOptions::NonGC && Record &&
                !Record->hasObjectMember()) {
       if (FD->getType()->isObjCObjectPointerType() ||
           FD->getType().isObjCGCStrong())
         Record->setHasObjectMember(true);
       else if (Context.getAsArrayType(FD->getType())) {
         QualType BaseType = Context.getBaseElementType(FD->getType());
         if (BaseType->isRecordType() &&
             BaseType->castAs<RecordType>()->getDecl()->hasObjectMember())
           Record->setHasObjectMember(true);
         else if (BaseType->isObjCObjectPointerType() ||
                  BaseType.isObjCGCStrong())
                Record->setHasObjectMember(true);
       }
     }
 
     if (Record && !getLangOpts().CPlusPlus &&
         !shouldIgnoreForRecordTriviality(FD)) {
       QualType FT = FD->getType();
       if (FT.isNonTrivialToPrimitiveDefaultInitialize()) {
         Record->setNonTrivialToPrimitiveDefaultInitialize(true);
         if (FT.hasNonTrivialToPrimitiveDefaultInitializeCUnion() ||
             Record->isUnion())
           Record->setHasNonTrivialToPrimitiveDefaultInitializeCUnion(true);
       }
       QualType::PrimitiveCopyKind PCK = FT.isNonTrivialToPrimitiveCopy();
       if (PCK != QualType::PCK_Trivial && PCK != QualType::PCK_VolatileTrivial) {
         Record->setNonTrivialToPrimitiveCopy(true);
         if (FT.hasNonTrivialToPrimitiveCopyCUnion() || Record->isUnion())
           Record->setHasNonTrivialToPrimitiveCopyCUnion(true);
       }
       if (FT.isDestructedType()) {
         Record->setNonTrivialToPrimitiveDestroy(true);
         Record->setParamDestroyedInCallee(true);
         if (FT.hasNonTrivialToPrimitiveDestructCUnion() || Record->isUnion())
           Record->setHasNonTrivialToPrimitiveDestructCUnion(true);
       }
 
       if (const auto *RT = FT->getAs<RecordType>()) {
         if (RT->getDecl()->getArgPassingRestrictions() ==
             RecordDecl::APK_CanNeverPassInRegs)
           Record->setArgPassingRestrictions(RecordDecl::APK_CanNeverPassInRegs);
       } else if (FT.getQualifiers().getObjCLifetime() == Qualifiers::OCL_Weak)
         Record->setArgPassingRestrictions(RecordDecl::APK_CanNeverPassInRegs);
     }
 
     if (Record && FD->getType().isVolatileQualified())
       Record->setHasVolatileMember(true);
     // Keep track of the number of named members.
     if (FD->getIdentifier())
       ++NumNamedMembers;
   }
 
   // Okay, we successfully defined 'Record'.
   if (Record) {
     bool Completed = false;
     if (CXXRecord) {
       if (!CXXRecord->isInvalidDecl()) {
         // Set access bits correctly on the directly-declared conversions.
         for (CXXRecordDecl::conversion_iterator
                I = CXXRecord->conversion_begin(),
                E = CXXRecord->conversion_end(); I != E; ++I)
           I.setAccess((*I)->getAccess());
       }
 
       // Add any implicitly-declared members to this class.
       AddImplicitlyDeclaredMembersToClass(CXXRecord);
 
       if (!CXXRecord->isDependentType()) {
         if (!CXXRecord->isInvalidDecl()) {
           // If we have virtual base classes, we may end up finding multiple
           // final overriders for a given virtual function. Check for this
           // problem now.
           if (CXXRecord->getNumVBases()) {
             CXXFinalOverriderMap FinalOverriders;
             CXXRecord->getFinalOverriders(FinalOverriders);
 
             for (CXXFinalOverriderMap::iterator M = FinalOverriders.begin(),
                                              MEnd = FinalOverriders.end();
                  M != MEnd; ++M) {
               for (OverridingMethods::iterator SO = M->second.begin(),
                                             SOEnd = M->second.end();
                    SO != SOEnd; ++SO) {
                 assert(SO->second.size() > 0 &&
                        "Virtual function without overriding functions?");
                 if (SO->second.size() == 1)
                   continue;
 
                 // C++ [class.virtual]p2:
                 //   In a derived class, if a virtual member function of a base
                 //   class subobject has more than one final overrider the
                 //   program is ill-formed.
                 Diag(Record->getLocation(), diag::err_multiple_final_overriders)
                   << (const NamedDecl *)M->first << Record;
                 Diag(M->first->getLocation(),
                      diag::note_overridden_virtual_function);
                 for (OverridingMethods::overriding_iterator
                           OM = SO->second.begin(),
                        OMEnd = SO->second.end();
                      OM != OMEnd; ++OM)
                   Diag(OM->Method->getLocation(), diag::note_final_overrider)
                     << (const NamedDecl *)M->first << OM->Method->getParent();
 
                 Record->setInvalidDecl();
               }
             }
             CXXRecord->completeDefinition(&FinalOverriders);
             Completed = true;
           }
         }
         ComputeSelectedDestructor(*this, CXXRecord);
         ComputeSpecialMemberFunctionsEligiblity(*this, CXXRecord);
       }
     }
 
     if (!Completed)
       Record->completeDefinition();
 
     // Handle attributes before checking the layout.
     ProcessDeclAttributeList(S, Record, Attrs);
 
     // Check to see if a FieldDecl is a pointer to a function.
     auto IsFunctionPointerOrForwardDecl = [&](const Decl *D) {
       const FieldDecl *FD = dyn_cast<FieldDecl>(D);
       if (!FD) {
         // Check whether this is a forward declaration that was inserted by
         // Clang. This happens when a non-forward declared / defined type is
         // used, e.g.:
         //
         //   struct foo {
         //     struct bar *(*f)();
         //     struct bar *(*g)();
         //   };
         //
         // "struct bar" shows up in the decl AST as a "RecordDecl" with an
         // incomplete definition.
         if (const auto *TD = dyn_cast<TagDecl>(D))
           return !TD->isCompleteDefinition();
         return false;
       }
       QualType FieldType = FD->getType().getDesugaredType(Context);
       if (isa<PointerType>(FieldType)) {
         QualType PointeeType = cast<PointerType>(FieldType)->getPointeeType();
         return PointeeType.getDesugaredType(Context)->isFunctionType();
       }
       return false;
     };
 
     // Maybe randomize the record's decls. We automatically randomize a record
     // of function pointers, unless it has the "no_randomize_layout" attribute.
     if (!getLangOpts().CPlusPlus &&
         (Record->hasAttr<RandomizeLayoutAttr>() ||
          (!Record->hasAttr<NoRandomizeLayoutAttr>() &&
           llvm::all_of(Record->decls(), IsFunctionPointerOrForwardDecl))) &&
         !Record->isUnion() && !getLangOpts().RandstructSeed.empty() &&
         !Record->isRandomized()) {
       SmallVector<Decl *, 32> NewDeclOrdering;
       if (randstruct::randomizeStructureLayout(Context, Record,
                                                NewDeclOrdering))
         Record->reorderDecls(NewDeclOrdering);
     }
 
     // We may have deferred checking for a deleted destructor. Check now.
     if (CXXRecord) {
       auto *Dtor = CXXRecord->getDestructor();
       if (Dtor && Dtor->isImplicit() &&
           ShouldDeleteSpecialMember(Dtor, CXXDestructor)) {
         CXXRecord->setImplicitDestructorIsDeleted();
         SetDeclDeleted(Dtor, CXXRecord->getLocation());
       }
     }
 
     if (Record->hasAttrs()) {
       CheckAlignasUnderalignment(Record);
 
       if (const MSInheritanceAttr *IA = Record->getAttr<MSInheritanceAttr>())
         checkMSInheritanceAttrOnDefinition(cast<CXXRecordDecl>(Record),
                                            IA->getRange(), IA->getBestCase(),
                                            IA->getInheritanceModel());
     }
 
     // Check if the structure/union declaration is a type that can have zero
     // size in C. For C this is a language extension, for C++ it may cause
     // compatibility problems.
     bool CheckForZeroSize;
     if (!getLangOpts().CPlusPlus) {
       CheckForZeroSize = true;
     } else {
       // For C++ filter out types that cannot be referenced in C code.
       CXXRecordDecl *CXXRecord = cast<CXXRecordDecl>(Record);
       CheckForZeroSize =
           CXXRecord->getLexicalDeclContext()->isExternCContext() &&
           !CXXRecord->isDependentType() && !inTemplateInstantiation() &&
           CXXRecord->isCLike();
     }
     if (CheckForZeroSize) {
       bool ZeroSize = true;
       bool IsEmpty = true;
       unsigned NonBitFields = 0;
       for (RecordDecl::field_iterator I = Record->field_begin(),
                                       E = Record->field_end();
            (NonBitFields == 0 || ZeroSize) && I != E; ++I) {
         IsEmpty = false;
         if (I->isUnnamedBitfield()) {
           if (!I->isZeroLengthBitField(Context))
             ZeroSize = false;
         } else {
           ++NonBitFields;
           QualType FieldType = I->getType();
           if (FieldType->isIncompleteType() ||
               !Context.getTypeSizeInChars(FieldType).isZero())
             ZeroSize = false;
         }
       }
 
       // Empty structs are an extension in C (C99 6.7.2.1p7). They are
       // allowed in C++, but warn if its declaration is inside
       // extern "C" block.
       if (ZeroSize) {
         Diag(RecLoc, getLangOpts().CPlusPlus ?
                          diag::warn_zero_size_struct_union_in_extern_c :
                          diag::warn_zero_size_struct_union_compat)
           << IsEmpty << Record->isUnion() << (NonBitFields > 1);
       }
 
       // Structs without named members are extension in C (C99 6.7.2.1p7),
       // but are accepted by GCC.
       if (NonBitFields == 0 && !getLangOpts().CPlusPlus) {
         Diag(RecLoc, IsEmpty ? diag::ext_empty_struct_union :
                                diag::ext_no_named_members_in_struct_union)
           << Record->isUnion();
       }
     }
   } else {
     ObjCIvarDecl **ClsFields =
       reinterpret_cast<ObjCIvarDecl**>(RecFields.data());
     if (ObjCInterfaceDecl *ID = dyn_cast<ObjCInterfaceDecl>(EnclosingDecl)) {
       ID->setEndOfDefinitionLoc(RBrac);
       // Add ivar's to class's DeclContext.
       for (unsigned i = 0, e = RecFields.size(); i != e; ++i) {
         ClsFields[i]->setLexicalDeclContext(ID);
         ID->addDecl(ClsFields[i]);
       }
       // Must enforce the rule that ivars in the base classes may not be
       // duplicates.
       if (ID->getSuperClass())
         DiagnoseDuplicateIvars(ID, ID->getSuperClass());
     } else if (ObjCImplementationDecl *IMPDecl =
                   dyn_cast<ObjCImplementationDecl>(EnclosingDecl)) {
       assert(IMPDecl && "ActOnFields - missing ObjCImplementationDecl");
       for (unsigned I = 0, N = RecFields.size(); I != N; ++I)
         // Ivar declared in @implementation never belongs to the implementation.
         // Only it is in implementation's lexical context.
         ClsFields[I]->setLexicalDeclContext(IMPDecl);
       CheckImplementationIvars(IMPDecl, ClsFields, RecFields.size(), RBrac);
       IMPDecl->setIvarLBraceLoc(LBrac);
       IMPDecl->setIvarRBraceLoc(RBrac);
     } else if (ObjCCategoryDecl *CDecl =
                 dyn_cast<ObjCCategoryDecl>(EnclosingDecl)) {
       // case of ivars in class extension; all other cases have been
       // reported as errors elsewhere.
       // FIXME. Class extension does not have a LocEnd field.
       // CDecl->setLocEnd(RBrac);
       // Add ivar's to class extension's DeclContext.
       // Diagnose redeclaration of private ivars.
       ObjCInterfaceDecl *IDecl = CDecl->getClassInterface();
       for (unsigned i = 0, e = RecFields.size(); i != e; ++i) {
         if (IDecl) {
           if (const ObjCIvarDecl *ClsIvar =
               IDecl->getIvarDecl(ClsFields[i]->getIdentifier())) {
             Diag(ClsFields[i]->getLocation(),
                  diag::err_duplicate_ivar_declaration);
             Diag(ClsIvar->getLocation(), diag::note_previous_definition);
             continue;
           }
           for (const auto *Ext : IDecl->known_extensions()) {
             if (const ObjCIvarDecl *ClsExtIvar
                   = Ext->getIvarDecl(ClsFields[i]->getIdentifier())) {
               Diag(ClsFields[i]->getLocation(),
                    diag::err_duplicate_ivar_declaration);
               Diag(ClsExtIvar->getLocation(), diag::note_previous_definition);
               continue;
             }
           }
         }
         ClsFields[i]->setLexicalDeclContext(CDecl);
         CDecl->addDecl(ClsFields[i]);
       }
       CDecl->setIvarLBraceLoc(LBrac);
       CDecl->setIvarRBraceLoc(RBrac);
     }
   }
 }
 
 /// Determine whether the given integral value is representable within
 /// the given type T.
 static bool isRepresentableIntegerValue(ASTContext &Context,
                                         llvm::APSInt &Value,
                                         QualType T) {
   assert((T->isIntegralType(Context) || T->isEnumeralType()) &&
          "Integral type required!");
   unsigned BitWidth = Context.getIntWidth(T);
 
   if (Value.isUnsigned() || Value.isNonNegative()) {
     if (T->isSignedIntegerOrEnumerationType())
       --BitWidth;
     return Value.getActiveBits() <= BitWidth;
   }
   return Value.getSignificantBits() <= BitWidth;
 }
 
 // Given an integral type, return the next larger integral type
 // (or a NULL type of no such type exists).
 static QualType getNextLargerIntegralType(ASTContext &Context, QualType T) {
   // FIXME: Int128/UInt128 support, which also needs to be introduced into
   // enum checking below.
   assert((T->isIntegralType(Context) ||
          T->isEnumeralType()) && "Integral type required!");
   const unsigned NumTypes = 4;
   QualType SignedIntegralTypes[NumTypes] = {
     Context.ShortTy, Context.IntTy, Context.LongTy, Context.LongLongTy
   };
   QualType UnsignedIntegralTypes[NumTypes] = {
     Context.UnsignedShortTy, Context.UnsignedIntTy, Context.UnsignedLongTy,
     Context.UnsignedLongLongTy
   };
 
   unsigned BitWidth = Context.getTypeSize(T);
   QualType *Types = T->isSignedIntegerOrEnumerationType()? SignedIntegralTypes
                                                         : UnsignedIntegralTypes;
   for (unsigned I = 0; I != NumTypes; ++I)
     if (Context.getTypeSize(Types[I]) > BitWidth)
       return Types[I];
 
   return QualType();
 }
 
 EnumConstantDecl *Sema::CheckEnumConstant(EnumDecl *Enum,
                                           EnumConstantDecl *LastEnumConst,
                                           SourceLocation IdLoc,
                                           IdentifierInfo *Id,
                                           Expr *Val) {
   unsigned IntWidth = Context.getTargetInfo().getIntWidth();
   llvm::APSInt EnumVal(IntWidth);
   QualType EltTy;
 
   if (Val && DiagnoseUnexpandedParameterPack(Val, UPPC_EnumeratorValue))
     Val = nullptr;
 
   if (Val)
     Val = DefaultLvalueConversion(Val).get();
 
   if (Val) {
     if (Enum->isDependentType() || Val->isTypeDependent() ||
         Val->containsErrors())
       EltTy = Context.DependentTy;
     else {
       // FIXME: We don't allow folding in C++11 mode for an enum with a fixed
       // underlying type, but do allow it in all other contexts.
       if (getLangOpts().CPlusPlus11 && Enum->isFixed()) {
         // C++11 [dcl.enum]p5: If the underlying type is fixed, [...] the
         // constant-expression in the enumerator-definition shall be a converted
         // constant expression of the underlying type.
         EltTy = Enum->getIntegerType();
         ExprResult Converted =
           CheckConvertedConstantExpression(Val, EltTy, EnumVal,
                                            CCEK_Enumerator);
         if (Converted.isInvalid())
           Val = nullptr;
         else
           Val = Converted.get();
       } else if (!Val->isValueDependent() &&
                  !(Val =
                        VerifyIntegerConstantExpression(Val, &EnumVal, AllowFold)
                            .get())) {
         // C99 6.7.2.2p2: Make sure we have an integer constant expression.
       } else {
         if (Enum->isComplete()) {
           EltTy = Enum->getIntegerType();
 
           // In Obj-C and Microsoft mode, require the enumeration value to be
           // representable in the underlying type of the enumeration. In C++11,
           // we perform a non-narrowing conversion as part of converted constant
           // expression checking.
           if (!isRepresentableIntegerValue(Context, EnumVal, EltTy)) {
             if (Context.getTargetInfo()
                     .getTriple()
                     .isWindowsMSVCEnvironment()) {
               Diag(IdLoc, diag::ext_enumerator_too_large) << EltTy;
             } else {
               Diag(IdLoc, diag::err_enumerator_too_large) << EltTy;
             }
           }
 
           // Cast to the underlying type.
           Val = ImpCastExprToType(Val, EltTy,
                                   EltTy->isBooleanType() ? CK_IntegralToBoolean
                                                          : CK_IntegralCast)
                     .get();
         } else if (getLangOpts().CPlusPlus) {
           // C++11 [dcl.enum]p5:
           //   If the underlying type is not fixed, the type of each enumerator
           //   is the type of its initializing value:
           //     - If an initializer is specified for an enumerator, the
           //       initializing value has the same type as the expression.
           EltTy = Val->getType();
         } else {
           // C99 6.7.2.2p2:
           //   The expression that defines the value of an enumeration constant
           //   shall be an integer constant expression that has a value
           //   representable as an int.
 
           // Complain if the value is not representable in an int.
           if (!isRepresentableIntegerValue(Context, EnumVal, Context.IntTy))
             Diag(IdLoc, diag::ext_enum_value_not_int)
               << toString(EnumVal, 10) << Val->getSourceRange()
               << (EnumVal.isUnsigned() || EnumVal.isNonNegative());
           else if (!Context.hasSameType(Val->getType(), Context.IntTy)) {
             // Force the type of the expression to 'int'.
             Val = ImpCastExprToType(Val, Context.IntTy, CK_IntegralCast).get();
           }
           EltTy = Val->getType();
         }
       }
     }
   }
 
   if (!Val) {
     if (Enum->isDependentType())
       EltTy = Context.DependentTy;
     else if (!LastEnumConst) {
       // C++0x [dcl.enum]p5:
       //   If the underlying type is not fixed, the type of each enumerator
       //   is the type of its initializing value:
       //     - If no initializer is specified for the first enumerator, the
       //       initializing value has an unspecified integral type.
       //
       // GCC uses 'int' for its unspecified integral type, as does
       // C99 6.7.2.2p3.
       if (Enum->isFixed()) {
         EltTy = Enum->getIntegerType();
       }
       else {
         EltTy = Context.IntTy;
       }
     } else {
       // Assign the last value + 1.
       EnumVal = LastEnumConst->getInitVal();
       ++EnumVal;
       EltTy = LastEnumConst->getType();
 
       // Check for overflow on increment.
       if (EnumVal < LastEnumConst->getInitVal()) {
         // C++0x [dcl.enum]p5:
         //   If the underlying type is not fixed, the type of each enumerator
         //   is the type of its initializing value:
         //
         //     - Otherwise the type of the initializing value is the same as
         //       the type of the initializing value of the preceding enumerator
         //       unless the incremented value is not representable in that type,
         //       in which case the type is an unspecified integral type
         //       sufficient to contain the incremented value. If no such type
         //       exists, the program is ill-formed.
         QualType T = getNextLargerIntegralType(Context, EltTy);
         if (T.isNull() || Enum->isFixed()) {
           // There is no integral type larger enough to represent this
           // value. Complain, then allow the value to wrap around.
           EnumVal = LastEnumConst->getInitVal();
           EnumVal = EnumVal.zext(EnumVal.getBitWidth() * 2);
           ++EnumVal;
           if (Enum->isFixed())
             // When the underlying type is fixed, this is ill-formed.
             Diag(IdLoc, diag::err_enumerator_wrapped)
               << toString(EnumVal, 10)
               << EltTy;
           else
             Diag(IdLoc, diag::ext_enumerator_increment_too_large)
               << toString(EnumVal, 10);
         } else {
           EltTy = T;
         }
 
         // Retrieve the last enumerator's value, extent that type to the
         // type that is supposed to be large enough to represent the incremented
         // value, then increment.
         EnumVal = LastEnumConst->getInitVal();
         EnumVal.setIsSigned(EltTy->isSignedIntegerOrEnumerationType());
         EnumVal = EnumVal.zextOrTrunc(Context.getIntWidth(EltTy));
         ++EnumVal;
 
         // If we're not in C++, diagnose the overflow of enumerator values,
         // which in C99 means that the enumerator value is not representable in
         // an int (C99 6.7.2.2p2). However, we support GCC's extension that
         // permits enumerator values that are representable in some larger
         // integral type.
         if (!getLangOpts().CPlusPlus && !T.isNull())
           Diag(IdLoc, diag::warn_enum_value_overflow);
       } else if (!getLangOpts().CPlusPlus &&
                  !EltTy->isDependentType() &&
                  !isRepresentableIntegerValue(Context, EnumVal, EltTy)) {
         // Enforce C99 6.7.2.2p2 even when we compute the next value.
         Diag(IdLoc, diag::ext_enum_value_not_int)
           << toString(EnumVal, 10) << 1;
       }
     }
   }
 
   if (!EltTy->isDependentType()) {
     // Make the enumerator value match the signedness and size of the
     // enumerator's type.
     EnumVal = EnumVal.extOrTrunc(Context.getIntWidth(EltTy));
     EnumVal.setIsSigned(EltTy->isSignedIntegerOrEnumerationType());
   }
 
   return EnumConstantDecl::Create(Context, Enum, IdLoc, Id, EltTy,
                                   Val, EnumVal);
 }
 
 Sema::SkipBodyInfo Sema::shouldSkipAnonEnumBody(Scope *S, IdentifierInfo *II,
                                                 SourceLocation IILoc) {
   if (!(getLangOpts().Modules || getLangOpts().ModulesLocalVisibility) ||
       !getLangOpts().CPlusPlus)
     return SkipBodyInfo();
 
   // We have an anonymous enum definition. Look up the first enumerator to
   // determine if we should merge the definition with an existing one and
   // skip the body.
   NamedDecl *PrevDecl = LookupSingleName(S, II, IILoc, LookupOrdinaryName,
                                          forRedeclarationInCurContext());
   auto *PrevECD = dyn_cast_or_null<EnumConstantDecl>(PrevDecl);
   if (!PrevECD)
     return SkipBodyInfo();
 
   EnumDecl *PrevED = cast<EnumDecl>(PrevECD->getDeclContext());
   NamedDecl *Hidden;
   if (!PrevED->getDeclName() && !hasVisibleDefinition(PrevED, &Hidden)) {
     SkipBodyInfo Skip;
     Skip.Previous = Hidden;
     return Skip;
   }
 
   return SkipBodyInfo();
 }
 
 Decl *Sema::ActOnEnumConstant(Scope *S, Decl *theEnumDecl, Decl *lastEnumConst,
                               SourceLocation IdLoc, IdentifierInfo *Id,
                               const ParsedAttributesView &Attrs,
                               SourceLocation EqualLoc, Expr *Val) {
   EnumDecl *TheEnumDecl = cast<EnumDecl>(theEnumDecl);
   EnumConstantDecl *LastEnumConst =
     cast_or_null<EnumConstantDecl>(lastEnumConst);
 
   // The scope passed in may not be a decl scope.  Zip up the scope tree until
   // we find one that is.
   S = getNonFieldDeclScope(S);
 
   // Verify that there isn't already something declared with this name in this
   // scope.
   LookupResult R(*this, Id, IdLoc, LookupOrdinaryName, ForVisibleRedeclaration);
   LookupName(R, S);
   NamedDecl *PrevDecl = R.getAsSingle<NamedDecl>();
 
   if (PrevDecl && PrevDecl->isTemplateParameter()) {
     // Maybe we will complain about the shadowed template parameter.
     DiagnoseTemplateParameterShadow(IdLoc, PrevDecl);
     // Just pretend that we didn't see the previous declaration.
     PrevDecl = nullptr;
   }
 
   // C++ [class.mem]p15:
   // If T is the name of a class, then each of the following shall have a name
   // different from T:
   // - every enumerator of every member of class T that is an unscoped
   // enumerated type
   if (getLangOpts().CPlusPlus && !TheEnumDecl->isScoped())
     DiagnoseClassNameShadow(TheEnumDecl->getDeclContext(),
                             DeclarationNameInfo(Id, IdLoc));
 
   EnumConstantDecl *New =
     CheckEnumConstant(TheEnumDecl, LastEnumConst, IdLoc, Id, Val);
   if (!New)
     return nullptr;
 
   if (PrevDecl) {
     if (!TheEnumDecl->isScoped() && isa<ValueDecl>(PrevDecl)) {
       // Check for other kinds of shadowing not already handled.
       CheckShadow(New, PrevDecl, R);
     }
 
     // When in C++, we may get a TagDecl with the same name; in this case the
     // enum constant will 'hide' the tag.
     assert((getLangOpts().CPlusPlus || !isa<TagDecl>(PrevDecl)) &&
            "Received TagDecl when not in C++!");
     if (!isa<TagDecl>(PrevDecl) && isDeclInScope(PrevDecl, CurContext, S)) {
       if (isa<EnumConstantDecl>(PrevDecl))
         Diag(IdLoc, diag::err_redefinition_of_enumerator) << Id;
       else
         Diag(IdLoc, diag::err_redefinition) << Id;
       notePreviousDefinition(PrevDecl, IdLoc);
       return nullptr;
     }
   }
 
   // Process attributes.
   ProcessDeclAttributeList(S, New, Attrs);
   AddPragmaAttributes(S, New);
 
   // Register this decl in the current scope stack.
   New->setAccess(TheEnumDecl->getAccess());
   PushOnScopeChains(New, S);
 
   ActOnDocumentableDecl(New);
 
   return New;
 }
 
 // Returns true when the enum initial expression does not trigger the
 // duplicate enum warning.  A few common cases are exempted as follows:
 // Element2 = Element1
 // Element2 = Element1 + 1
 // Element2 = Element1 - 1
 // Where Element2 and Element1 are from the same enum.
 static bool ValidDuplicateEnum(EnumConstantDecl *ECD, EnumDecl *Enum) {
   Expr *InitExpr = ECD->getInitExpr();
   if (!InitExpr)
     return true;
   InitExpr = InitExpr->IgnoreImpCasts();
 
   if (BinaryOperator *BO = dyn_cast<BinaryOperator>(InitExpr)) {
     if (!BO->isAdditiveOp())
       return true;
     IntegerLiteral *IL = dyn_cast<IntegerLiteral>(BO->getRHS());
     if (!IL)
       return true;
     if (IL->getValue() != 1)
       return true;
 
     InitExpr = BO->getLHS();
   }
 
   // This checks if the elements are from the same enum.
   DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(InitExpr);
   if (!DRE)
     return true;
 
   EnumConstantDecl *EnumConstant = dyn_cast<EnumConstantDecl>(DRE->getDecl());
   if (!EnumConstant)
     return true;
 
   if (cast<EnumDecl>(TagDecl::castFromDeclContext(ECD->getDeclContext())) !=
       Enum)
     return true;
 
   return false;
 }
 
 // Emits a warning when an element is implicitly set a value that
 // a previous element has already been set to.
 static void CheckForDuplicateEnumValues(Sema &S, ArrayRef<Decl *> Elements,
                                         EnumDecl *Enum, QualType EnumType) {
   // Avoid anonymous enums
   if (!Enum->getIdentifier())
     return;
 
   // Only check for small enums.
   if (Enum->getNumPositiveBits() > 63 || Enum->getNumNegativeBits() > 64)
     return;
 
   if (S.Diags.isIgnored(diag::warn_duplicate_enum_values, Enum->getLocation()))
     return;
 
   typedef SmallVector<EnumConstantDecl *, 3> ECDVector;
   typedef SmallVector<std::unique_ptr<ECDVector>, 3> DuplicatesVector;
 
   typedef llvm::PointerUnion<EnumConstantDecl*, ECDVector*> DeclOrVector;
 
   // DenseMaps cannot contain the all ones int64_t value, so use unordered_map.
   typedef std::unordered_map<int64_t, DeclOrVector> ValueToVectorMap;
 
   // Use int64_t as a key to avoid needing special handling for map keys.
   auto EnumConstantToKey = [](const EnumConstantDecl *D) {
     llvm::APSInt Val = D->getInitVal();
     return Val.isSigned() ? Val.getSExtValue() : Val.getZExtValue();
   };
 
   DuplicatesVector DupVector;
   ValueToVectorMap EnumMap;
 
   // Populate the EnumMap with all values represented by enum constants without
   // an initializer.
   for (auto *Element : Elements) {
     EnumConstantDecl *ECD = cast_or_null<EnumConstantDecl>(Element);
 
     // Null EnumConstantDecl means a previous diagnostic has been emitted for
     // this constant.  Skip this enum since it may be ill-formed.
     if (!ECD) {
       return;
     }
 
     // Constants with initializers are handled in the next loop.
     if (ECD->getInitExpr())
       continue;
 
     // Duplicate values are handled in the next loop.
     EnumMap.insert({EnumConstantToKey(ECD), ECD});
   }
 
   if (EnumMap.size() == 0)
     return;
 
   // Create vectors for any values that has duplicates.
   for (auto *Element : Elements) {
     // The last loop returned if any constant was null.
     EnumConstantDecl *ECD = cast<EnumConstantDecl>(Element);
     if (!ValidDuplicateEnum(ECD, Enum))
       continue;
 
     auto Iter = EnumMap.find(EnumConstantToKey(ECD));
     if (Iter == EnumMap.end())
       continue;
 
     DeclOrVector& Entry = Iter->second;
     if (EnumConstantDecl *D = Entry.dyn_cast<EnumConstantDecl*>()) {
       // Ensure constants are different.
       if (D == ECD)
         continue;
 
       // Create new vector and push values onto it.
       auto Vec = std::make_unique<ECDVector>();
       Vec->push_back(D);
       Vec->push_back(ECD);
 
       // Update entry to point to the duplicates vector.
       Entry = Vec.get();
 
       // Store the vector somewhere we can consult later for quick emission of
       // diagnostics.
       DupVector.emplace_back(std::move(Vec));
       continue;
     }
 
     ECDVector *Vec = Entry.get<ECDVector*>();
     // Make sure constants are not added more than once.
     if (*Vec->begin() == ECD)
       continue;
 
     Vec->push_back(ECD);
   }
 
   // Emit diagnostics.
   for (const auto &Vec : DupVector) {
     assert(Vec->size() > 1 && "ECDVector should have at least 2 elements.");
 
     // Emit warning for one enum constant.
     auto *FirstECD = Vec->front();
     S.Diag(FirstECD->getLocation(), diag::warn_duplicate_enum_values)
       << FirstECD << toString(FirstECD->getInitVal(), 10)
       << FirstECD->getSourceRange();
 
     // Emit one note for each of the remaining enum constants with
     // the same value.
     for (auto *ECD : llvm::drop_begin(*Vec))
       S.Diag(ECD->getLocation(), diag::note_duplicate_element)
         << ECD << toString(ECD->getInitVal(), 10)
         << ECD->getSourceRange();
   }
 }
 
 bool Sema::IsValueInFlagEnum(const EnumDecl *ED, const llvm::APInt &Val,
                              bool AllowMask) const {
   assert(ED->isClosedFlag() && "looking for value in non-flag or open enum");
   assert(ED->isCompleteDefinition() && "expected enum definition");
 
   auto R = FlagBitsCache.insert(std::make_pair(ED, llvm::APInt()));
   llvm::APInt &FlagBits = R.first->second;
 
   if (R.second) {
     for (auto *E : ED->enumerators()) {
       const auto &EVal = E->getInitVal();
       // Only single-bit enumerators introduce new flag values.
       if (EVal.isPowerOf2())
         FlagBits = FlagBits.zext(EVal.getBitWidth()) | EVal;
     }
   }
 
   // A value is in a flag enum if either its bits are a subset of the enum's
   // flag bits (the first condition) or we are allowing masks and the same is
   // true of its complement (the second condition). When masks are allowed, we
   // allow the common idiom of ~(enum1 | enum2) to be a valid enum value.
   //
   // While it's true that any value could be used as a mask, the assumption is
   // that a mask will have all of the insignificant bits set. Anything else is
   // likely a logic error.
   llvm::APInt FlagMask = ~FlagBits.zextOrTrunc(Val.getBitWidth());
   return !(FlagMask & Val) || (AllowMask && !(FlagMask & ~Val));
 }
 
 void Sema::ActOnEnumBody(SourceLocation EnumLoc, SourceRange BraceRange,
                          Decl *EnumDeclX, ArrayRef<Decl *> Elements, Scope *S,
                          const ParsedAttributesView &Attrs) {
   EnumDecl *Enum = cast<EnumDecl>(EnumDeclX);
   QualType EnumType = Context.getTypeDeclType(Enum);
 
   ProcessDeclAttributeList(S, Enum, Attrs);
 
   if (Enum->isDependentType()) {
     for (unsigned i = 0, e = Elements.size(); i != e; ++i) {
       EnumConstantDecl *ECD =
         cast_or_null<EnumConstantDecl>(Elements[i]);
       if (!ECD) continue;
 
       ECD->setType(EnumType);
     }
 
     Enum->completeDefinition(Context.DependentTy, Context.DependentTy, 0, 0);
     return;
   }
 
   // TODO: If the result value doesn't fit in an int, it must be a long or long
   // long value.  ISO C does not support this, but GCC does as an extension,
   // emit a warning.
   unsigned IntWidth = Context.getTargetInfo().getIntWidth();
   unsigned CharWidth = Context.getTargetInfo().getCharWidth();
   unsigned ShortWidth = Context.getTargetInfo().getShortWidth();
 
   // Verify that all the values are okay, compute the size of the values, and
   // reverse the list.
   unsigned NumNegativeBits = 0;
   unsigned NumPositiveBits = 0;
 
   for (unsigned i = 0, e = Elements.size(); i != e; ++i) {
     EnumConstantDecl *ECD =
       cast_or_null<EnumConstantDecl>(Elements[i]);
     if (!ECD) continue;  // Already issued a diagnostic.
 
     const llvm::APSInt &InitVal = ECD->getInitVal();
 
     // Keep track of the size of positive and negative values.
     if (InitVal.isUnsigned() || InitVal.isNonNegative()) {
       // If the enumerator is zero that should still be counted as a positive
       // bit since we need a bit to store the value zero.
       unsigned ActiveBits = InitVal.getActiveBits();
       NumPositiveBits = std::max({NumPositiveBits, ActiveBits, 1u});
     } else {
       NumNegativeBits =
           std::max(NumNegativeBits, (unsigned)InitVal.getSignificantBits());
     }
   }
 
   // If we have an empty set of enumerators we still need one bit.
   // From [dcl.enum]p8
   // If the enumerator-list is empty, the values of the enumeration are as if
   // the enumeration had a single enumerator with value 0
   if (!NumPositiveBits && !NumNegativeBits)
     NumPositiveBits = 1;
 
   // Figure out the type that should be used for this enum.
   QualType BestType;
   unsigned BestWidth;
 
   // C++0x N3000 [conv.prom]p3:
   //   An rvalue of an unscoped enumeration type whose underlying
   //   type is not fixed can be converted to an rvalue of the first
   //   of the following types that can represent all the values of
   //   the enumeration: int, unsigned int, long int, unsigned long
   //   int, long long int, or unsigned long long int.
   // C99 6.4.4.3p2:
   //   An identifier declared as an enumeration constant has type int.
   // The C99 rule is modified by a gcc extension
   QualType BestPromotionType;
 
   bool Packed = Enum->hasAttr<PackedAttr>();
   // -fshort-enums is the equivalent to specifying the packed attribute on all
   // enum definitions.
   if (LangOpts.ShortEnums)
     Packed = true;
 
   // If the enum already has a type because it is fixed or dictated by the
   // target, promote that type instead of analyzing the enumerators.
   if (Enum->isComplete()) {
     BestType = Enum->getIntegerType();
     if (Context.isPromotableIntegerType(BestType))
       BestPromotionType = Context.getPromotedIntegerType(BestType);
     else
       BestPromotionType = BestType;
 
     BestWidth = Context.getIntWidth(BestType);
   }
   else if (NumNegativeBits) {
     // If there is a negative value, figure out the smallest integer type (of
     // int/long/longlong) that fits.
     // If it's packed, check also if it fits a char or a short.
     if (Packed && NumNegativeBits <= CharWidth && NumPositiveBits < CharWidth) {
       BestType = Context.SignedCharTy;
       BestWidth = CharWidth;
     } else if (Packed && NumNegativeBits <= ShortWidth &&
                NumPositiveBits < ShortWidth) {
       BestType = Context.ShortTy;
       BestWidth = ShortWidth;
     } else if (NumNegativeBits <= IntWidth && NumPositiveBits < IntWidth) {
       BestType = Context.IntTy;
       BestWidth = IntWidth;
     } else {
       BestWidth = Context.getTargetInfo().getLongWidth();
 
       if (NumNegativeBits <= BestWidth && NumPositiveBits < BestWidth) {
         BestType = Context.LongTy;
       } else {
         BestWidth = Context.getTargetInfo().getLongLongWidth();
 
         if (NumNegativeBits > BestWidth || NumPositiveBits >= BestWidth)
           Diag(Enum->getLocation(), diag::ext_enum_too_large);
         BestType = Context.LongLongTy;
       }
     }
     BestPromotionType = (BestWidth <= IntWidth ? Context.IntTy : BestType);
   } else {
     // If there is no negative value, figure out the smallest type that fits
     // all of the enumerator values.
     // If it's packed, check also if it fits a char or a short.
     if (Packed && NumPositiveBits <= CharWidth) {
       BestType = Context.UnsignedCharTy;
       BestPromotionType = Context.IntTy;
       BestWidth = CharWidth;
     } else if (Packed && NumPositiveBits <= ShortWidth) {
       BestType = Context.UnsignedShortTy;
       BestPromotionType = Context.IntTy;
       BestWidth = ShortWidth;
     } else if (NumPositiveBits <= IntWidth) {
       BestType = Context.UnsignedIntTy;
       BestWidth = IntWidth;
       BestPromotionType
         = (NumPositiveBits == BestWidth || !getLangOpts().CPlusPlus)
                            ? Context.UnsignedIntTy : Context.IntTy;
     } else if (NumPositiveBits <=
                (BestWidth = Context.getTargetInfo().getLongWidth())) {
       BestType = Context.UnsignedLongTy;
       BestPromotionType
         = (NumPositiveBits == BestWidth || !getLangOpts().CPlusPlus)
                            ? Context.UnsignedLongTy : Context.LongTy;
     } else {
       BestWidth = Context.getTargetInfo().getLongLongWidth();
       assert(NumPositiveBits <= BestWidth &&
              "How could an initializer get larger than ULL?");
       BestType = Context.UnsignedLongLongTy;
       BestPromotionType
         = (NumPositiveBits == BestWidth || !getLangOpts().CPlusPlus)
                            ? Context.UnsignedLongLongTy : Context.LongLongTy;
     }
   }
 
   // Loop over all of the enumerator constants, changing their types to match
   // the type of the enum if needed.
   for (auto *D : Elements) {
     auto *ECD = cast_or_null<EnumConstantDecl>(D);
     if (!ECD) continue;  // Already issued a diagnostic.
 
     // Standard C says the enumerators have int type, but we allow, as an
     // extension, the enumerators to be larger than int size.  If each
     // enumerator value fits in an int, type it as an int, otherwise type it the
     // same as the enumerator decl itself.  This means that in "enum { X = 1U }"
     // that X has type 'int', not 'unsigned'.
 
     // Determine whether the value fits into an int.
     llvm::APSInt InitVal = ECD->getInitVal();
 
     // If it fits into an integer type, force it.  Otherwise force it to match
     // the enum decl type.
     QualType NewTy;
     unsigned NewWidth;
     bool NewSign;
     if (!getLangOpts().CPlusPlus &&
         !Enum->isFixed() &&
         isRepresentableIntegerValue(Context, InitVal, Context.IntTy)) {
       NewTy = Context.IntTy;
       NewWidth = IntWidth;
       NewSign = true;
     } else if (ECD->getType() == BestType) {
       // Already the right type!
       if (getLangOpts().CPlusPlus)
         // C++ [dcl.enum]p4: Following the closing brace of an
         // enum-specifier, each enumerator has the type of its
         // enumeration.
         ECD->setType(EnumType);
       continue;
     } else {
       NewTy = BestType;
       NewWidth = BestWidth;
       NewSign = BestType->isSignedIntegerOrEnumerationType();
     }
 
     // Adjust the APSInt value.
     InitVal = InitVal.extOrTrunc(NewWidth);
     InitVal.setIsSigned(NewSign);
     ECD->setInitVal(InitVal);
 
     // Adjust the Expr initializer and type.
     if (ECD->getInitExpr() &&
         !Context.hasSameType(NewTy, ECD->getInitExpr()->getType()))
       ECD->setInitExpr(ImplicitCastExpr::Create(
           Context, NewTy, CK_IntegralCast, ECD->getInitExpr(),
           /*base paths*/ nullptr, VK_PRValue, FPOptionsOverride()));
     if (getLangOpts().CPlusPlus)
       // C++ [dcl.enum]p4: Following the closing brace of an
       // enum-specifier, each enumerator has the type of its
       // enumeration.
       ECD->setType(EnumType);
     else
       ECD->setType(NewTy);
   }
 
   Enum->completeDefinition(BestType, BestPromotionType,
                            NumPositiveBits, NumNegativeBits);
 
   CheckForDuplicateEnumValues(*this, Elements, Enum, EnumType);
 
   if (Enum->isClosedFlag()) {
     for (Decl *D : Elements) {
       EnumConstantDecl *ECD = cast_or_null<EnumConstantDecl>(D);
       if (!ECD) continue;  // Already issued a diagnostic.
 
       llvm::APSInt InitVal = ECD->getInitVal();
       if (InitVal != 0 && !InitVal.isPowerOf2() &&
           !IsValueInFlagEnum(Enum, InitVal, true))
         Diag(ECD->getLocation(), diag::warn_flag_enum_constant_out_of_range)
           << ECD << Enum;
     }
   }
 
   // Now that the enum type is defined, ensure it's not been underaligned.
   if (Enum->hasAttrs())
     CheckAlignasUnderalignment(Enum);
 }
 
 Decl *Sema::ActOnFileScopeAsmDecl(Expr *expr,
                                   SourceLocation StartLoc,
                                   SourceLocation EndLoc) {
   StringLiteral *AsmString = cast<StringLiteral>(expr);
 
   FileScopeAsmDecl *New = FileScopeAsmDecl::Create(Context, CurContext,
                                                    AsmString, StartLoc,
                                                    EndLoc);
   CurContext->addDecl(New);
   return New;
 }
 
 Decl *Sema::ActOnTopLevelStmtDecl(Stmt *Statement) {
   auto *New = TopLevelStmtDecl::Create(Context, Statement);
   Context.getTranslationUnitDecl()->addDecl(New);
   return New;
 }
 
 void Sema::ActOnPragmaRedefineExtname(IdentifierInfo* Name,
                                       IdentifierInfo* AliasName,
                                       SourceLocation PragmaLoc,
                                       SourceLocation NameLoc,
                                       SourceLocation AliasNameLoc) {
   NamedDecl *PrevDecl = LookupSingleName(TUScope, Name, NameLoc,
                                          LookupOrdinaryName);
   AttributeCommonInfo Info(AliasName, SourceRange(AliasNameLoc),
                            AttributeCommonInfo::Form::Pragma());
   AsmLabelAttr *Attr = AsmLabelAttr::CreateImplicit(
       Context, AliasName->getName(), /*IsLiteralLabel=*/true, Info);
 
   // If a declaration that:
   // 1) declares a function or a variable
   // 2) has external linkage
   // already exists, add a label attribute to it.
   if (PrevDecl && (isa<FunctionDecl>(PrevDecl) || isa<VarDecl>(PrevDecl))) {
     if (isDeclExternC(PrevDecl))
       PrevDecl->addAttr(Attr);
     else
       Diag(PrevDecl->getLocation(), diag::warn_redefine_extname_not_applied)
           << /*Variable*/(isa<FunctionDecl>(PrevDecl) ? 0 : 1) << PrevDecl;
     // Otherwise, add a label attribute to ExtnameUndeclaredIdentifiers.
   } else
     (void)ExtnameUndeclaredIdentifiers.insert(std::make_pair(Name, Attr));
 }
 
 void Sema::ActOnPragmaWeakID(IdentifierInfo* Name,
                              SourceLocation PragmaLoc,
                              SourceLocation NameLoc) {
   Decl *PrevDecl = LookupSingleName(TUScope, Name, NameLoc, LookupOrdinaryName);
 
   if (PrevDecl) {
     PrevDecl->addAttr(WeakAttr::CreateImplicit(Context, PragmaLoc));
   } else {
     (void)WeakUndeclaredIdentifiers[Name].insert(WeakInfo(nullptr, NameLoc));
   }
 }
 
 void Sema::ActOnPragmaWeakAlias(IdentifierInfo* Name,
                                 IdentifierInfo* AliasName,
                                 SourceLocation PragmaLoc,
                                 SourceLocation NameLoc,
                                 SourceLocation AliasNameLoc) {
   Decl *PrevDecl = LookupSingleName(TUScope, AliasName, AliasNameLoc,
                                     LookupOrdinaryName);
   WeakInfo W = WeakInfo(Name, NameLoc);
 
   if (PrevDecl && (isa<FunctionDecl>(PrevDecl) || isa<VarDecl>(PrevDecl))) {
     if (!PrevDecl->hasAttr<AliasAttr>())
       if (NamedDecl *ND = dyn_cast<NamedDecl>(PrevDecl))
         DeclApplyPragmaWeak(TUScope, ND, W);
   } else {
     (void)WeakUndeclaredIdentifiers[AliasName].insert(W);
   }
 }
 
 ObjCContainerDecl *Sema::getObjCDeclContext() const {
   return (dyn_cast_or_null<ObjCContainerDecl>(CurContext));
 }
 
 Sema::FunctionEmissionStatus Sema::getEmissionStatus(const FunctionDecl *FD,
                                                      bool Final) {
   assert(FD && "Expected non-null FunctionDecl");
 
   // SYCL functions can be template, so we check if they have appropriate
   // attribute prior to checking if it is a template.
   if (LangOpts.SYCLIsDevice && FD->hasAttr<SYCLKernelAttr>())
     return FunctionEmissionStatus::Emitted;
 
   // Templates are emitted when they're instantiated.
   if (FD->isDependentContext())
     return FunctionEmissionStatus::TemplateDiscarded;
 
   // Check whether this function is an externally visible definition.
   auto IsEmittedForExternalSymbol = [this, FD]() {
     // We have to check the GVA linkage of the function's *definition* -- if we
     // only have a declaration, we don't know whether or not the function will
     // be emitted, because (say) the definition could include "inline".
     const FunctionDecl *Def = FD->getDefinition();
 
     return Def && !isDiscardableGVALinkage(
                       getASTContext().GetGVALinkageForFunction(Def));
   };
 
   if (LangOpts.OpenMPIsTargetDevice) {
     // In OpenMP device mode we will not emit host only functions, or functions
     // we don't need due to their linkage.
     std::optional<OMPDeclareTargetDeclAttr::DevTypeTy> DevTy =
         OMPDeclareTargetDeclAttr::getDeviceType(FD->getCanonicalDecl());
     // DevTy may be changed later by
     //  #pragma omp declare target to(*) device_type(*).
     // Therefore DevTy having no value does not imply host. The emission status
     // will be checked again at the end of compilation unit with Final = true.
     if (DevTy)
       if (*DevTy == OMPDeclareTargetDeclAttr::DT_Host)
         return FunctionEmissionStatus::OMPDiscarded;
     // If we have an explicit value for the device type, or we are in a target
     // declare context, we need to emit all extern and used symbols.
     if (isInOpenMPDeclareTargetContext() || DevTy)
       if (IsEmittedForExternalSymbol())
         return FunctionEmissionStatus::Emitted;
     // Device mode only emits what it must, if it wasn't tagged yet and needed,
     // we'll omit it.
     if (Final)
       return FunctionEmissionStatus::OMPDiscarded;
   } else if (LangOpts.OpenMP > 45) {
     // In OpenMP host compilation prior to 5.0 everything was an emitted host
     // function. In 5.0, no_host was introduced which might cause a function to
     // be ommitted.
     std::optional<OMPDeclareTargetDeclAttr::DevTypeTy> DevTy =
         OMPDeclareTargetDeclAttr::getDeviceType(FD->getCanonicalDecl());
     if (DevTy)
       if (*DevTy == OMPDeclareTargetDeclAttr::DT_NoHost)
         return FunctionEmissionStatus::OMPDiscarded;
   }
 
   if (Final && LangOpts.OpenMP && !LangOpts.CUDA)
     return FunctionEmissionStatus::Emitted;
 
   if (LangOpts.CUDA) {
     // When compiling for device, host functions are never emitted.  Similarly,
     // when compiling for host, device and global functions are never emitted.
     // (Technically, we do emit a host-side stub for global functions, but this
     // doesn't count for our purposes here.)
     Sema::CUDAFunctionTarget T = IdentifyCUDATarget(FD);
     if (LangOpts.CUDAIsDevice && T == Sema::CFT_Host)
       return FunctionEmissionStatus::CUDADiscarded;
     if (!LangOpts.CUDAIsDevice &&
         (T == Sema::CFT_Device || T == Sema::CFT_Global))
       return FunctionEmissionStatus::CUDADiscarded;
 
     if (IsEmittedForExternalSymbol())
       return FunctionEmissionStatus::Emitted;
   }
 
   // Otherwise, the function is known-emitted if it's in our set of
   // known-emitted functions.
   return FunctionEmissionStatus::Unknown;
 }
 
 bool Sema::shouldIgnoreInHostDeviceCheck(FunctionDecl *Callee) {
   // Host-side references to a __global__ function refer to the stub, so the
   // function itself is never emitted and therefore should not be marked.
   // If we have host fn calls kernel fn calls host+device, the HD function
   // does not get instantiated on the host. We model this by omitting at the
   // call to the kernel from the callgraph. This ensures that, when compiling
   // for host, only HD functions actually called from the host get marked as
   // known-emitted.
   return LangOpts.CUDA && !LangOpts.CUDAIsDevice &&
          IdentifyCUDATarget(Callee) == CFT_Global;
 }
diff --git a/contrib/llvm-project/clang/lib/Sema/SemaExpr.cpp b/contrib/llvm-project/clang/lib/Sema/SemaExpr.cpp
index 3a5e302cc03a..63b00d640a9c 100644
--- a/contrib/llvm-project/clang/lib/Sema/SemaExpr.cpp
+++ b/contrib/llvm-project/clang/lib/Sema/SemaExpr.cpp
@@ -1,21746 +1,21747 @@
 //===--- SemaExpr.cpp - Semantic Analysis for Expressions -----------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 //  This file implements semantic analysis for expressions.
 //
 //===----------------------------------------------------------------------===//
 
 #include "TreeTransform.h"
 #include "UsedDeclVisitor.h"
 #include "clang/AST/ASTConsumer.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/ASTLambda.h"
 #include "clang/AST/ASTMutationListener.h"
 #include "clang/AST/CXXInheritance.h"
 #include "clang/AST/DeclObjC.h"
 #include "clang/AST/DeclTemplate.h"
 #include "clang/AST/EvaluatedExprVisitor.h"
 #include "clang/AST/Expr.h"
 #include "clang/AST/ExprCXX.h"
 #include "clang/AST/ExprObjC.h"
 #include "clang/AST/ExprOpenMP.h"
 #include "clang/AST/OperationKinds.h"
 #include "clang/AST/ParentMapContext.h"
 #include "clang/AST/RecursiveASTVisitor.h"
 #include "clang/AST/Type.h"
 #include "clang/AST/TypeLoc.h"
 #include "clang/Basic/Builtins.h"
 #include "clang/Basic/DiagnosticSema.h"
 #include "clang/Basic/PartialDiagnostic.h"
 #include "clang/Basic/SourceManager.h"
 #include "clang/Basic/Specifiers.h"
 #include "clang/Basic/TargetInfo.h"
 #include "clang/Lex/LiteralSupport.h"
 #include "clang/Lex/Preprocessor.h"
 #include "clang/Sema/AnalysisBasedWarnings.h"
 #include "clang/Sema/DeclSpec.h"
 #include "clang/Sema/DelayedDiagnostic.h"
 #include "clang/Sema/Designator.h"
 #include "clang/Sema/EnterExpressionEvaluationContext.h"
 #include "clang/Sema/Initialization.h"
 #include "clang/Sema/Lookup.h"
 #include "clang/Sema/Overload.h"
 #include "clang/Sema/ParsedTemplate.h"
 #include "clang/Sema/Scope.h"
 #include "clang/Sema/ScopeInfo.h"
 #include "clang/Sema/SemaFixItUtils.h"
 #include "clang/Sema/SemaInternal.h"
 #include "clang/Sema/Template.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/ConvertUTF.h"
 #include "llvm/Support/SaveAndRestore.h"
 #include "llvm/Support/TypeSize.h"
 #include <optional>
 
 using namespace clang;
 using namespace sema;
 
 /// Determine whether the use of this declaration is valid, without
 /// emitting diagnostics.
 bool Sema::CanUseDecl(NamedDecl *D, bool TreatUnavailableAsInvalid) {
   // See if this is an auto-typed variable whose initializer we are parsing.
   if (ParsingInitForAutoVars.count(D))
     return false;
 
   // See if this is a deleted function.
   if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
     if (FD->isDeleted())
       return false;
 
     // If the function has a deduced return type, and we can't deduce it,
     // then we can't use it either.
     if (getLangOpts().CPlusPlus14 && FD->getReturnType()->isUndeducedType() &&
         DeduceReturnType(FD, SourceLocation(), /*Diagnose*/ false))
       return false;
 
     // See if this is an aligned allocation/deallocation function that is
     // unavailable.
     if (TreatUnavailableAsInvalid &&
         isUnavailableAlignedAllocationFunction(*FD))
       return false;
   }
 
   // See if this function is unavailable.
   if (TreatUnavailableAsInvalid && D->getAvailability() == AR_Unavailable &&
       cast<Decl>(CurContext)->getAvailability() != AR_Unavailable)
     return false;
 
   if (isa<UnresolvedUsingIfExistsDecl>(D))
     return false;
 
   return true;
 }
 
 static void DiagnoseUnusedOfDecl(Sema &S, NamedDecl *D, SourceLocation Loc) {
   // Warn if this is used but marked unused.
   if (const auto *A = D->getAttr<UnusedAttr>()) {
     // [[maybe_unused]] should not diagnose uses, but __attribute__((unused))
     // should diagnose them.
     if (A->getSemanticSpelling() != UnusedAttr::CXX11_maybe_unused &&
         A->getSemanticSpelling() != UnusedAttr::C2x_maybe_unused) {
       const Decl *DC = cast_or_null<Decl>(S.getCurObjCLexicalContext());
       if (DC && !DC->hasAttr<UnusedAttr>())
         S.Diag(Loc, diag::warn_used_but_marked_unused) << D;
     }
   }
 }
 
 /// Emit a note explaining that this function is deleted.
 void Sema::NoteDeletedFunction(FunctionDecl *Decl) {
   assert(Decl && Decl->isDeleted());
 
   if (Decl->isDefaulted()) {
     // If the method was explicitly defaulted, point at that declaration.
     if (!Decl->isImplicit())
       Diag(Decl->getLocation(), diag::note_implicitly_deleted);
 
     // Try to diagnose why this special member function was implicitly
     // deleted. This might fail, if that reason no longer applies.
     DiagnoseDeletedDefaultedFunction(Decl);
     return;
   }
 
   auto *Ctor = dyn_cast<CXXConstructorDecl>(Decl);
   if (Ctor && Ctor->isInheritingConstructor())
     return NoteDeletedInheritingConstructor(Ctor);
 
   Diag(Decl->getLocation(), diag::note_availability_specified_here)
     << Decl << 1;
 }
 
 /// Determine whether a FunctionDecl was ever declared with an
 /// explicit storage class.
 static bool hasAnyExplicitStorageClass(const FunctionDecl *D) {
   for (auto *I : D->redecls()) {
     if (I->getStorageClass() != SC_None)
       return true;
   }
   return false;
 }
 
 /// Check whether we're in an extern inline function and referring to a
 /// variable or function with internal linkage (C11 6.7.4p3).
 ///
 /// This is only a warning because we used to silently accept this code, but
 /// in many cases it will not behave correctly. This is not enabled in C++ mode
 /// because the restriction language is a bit weaker (C++11 [basic.def.odr]p6)
 /// and so while there may still be user mistakes, most of the time we can't
 /// prove that there are errors.
 static void diagnoseUseOfInternalDeclInInlineFunction(Sema &S,
                                                       const NamedDecl *D,
                                                       SourceLocation Loc) {
   // This is disabled under C++; there are too many ways for this to fire in
   // contexts where the warning is a false positive, or where it is technically
   // correct but benign.
   if (S.getLangOpts().CPlusPlus)
     return;
 
   // Check if this is an inlined function or method.
   FunctionDecl *Current = S.getCurFunctionDecl();
   if (!Current)
     return;
   if (!Current->isInlined())
     return;
   if (!Current->isExternallyVisible())
     return;
 
   // Check if the decl has internal linkage.
   if (D->getFormalLinkage() != InternalLinkage)
     return;
 
   // Downgrade from ExtWarn to Extension if
   //  (1) the supposedly external inline function is in the main file,
   //      and probably won't be included anywhere else.
   //  (2) the thing we're referencing is a pure function.
   //  (3) the thing we're referencing is another inline function.
   // This last can give us false negatives, but it's better than warning on
   // wrappers for simple C library functions.
   const FunctionDecl *UsedFn = dyn_cast<FunctionDecl>(D);
   bool DowngradeWarning = S.getSourceManager().isInMainFile(Loc);
   if (!DowngradeWarning && UsedFn)
     DowngradeWarning = UsedFn->isInlined() || UsedFn->hasAttr<ConstAttr>();
 
   S.Diag(Loc, DowngradeWarning ? diag::ext_internal_in_extern_inline_quiet
                                : diag::ext_internal_in_extern_inline)
     << /*IsVar=*/!UsedFn << D;
 
   S.MaybeSuggestAddingStaticToDecl(Current);
 
   S.Diag(D->getCanonicalDecl()->getLocation(), diag::note_entity_declared_at)
       << D;
 }
 
 void Sema::MaybeSuggestAddingStaticToDecl(const FunctionDecl *Cur) {
   const FunctionDecl *First = Cur->getFirstDecl();
 
   // Suggest "static" on the function, if possible.
   if (!hasAnyExplicitStorageClass(First)) {
     SourceLocation DeclBegin = First->getSourceRange().getBegin();
     Diag(DeclBegin, diag::note_convert_inline_to_static)
       << Cur << FixItHint::CreateInsertion(DeclBegin, "static ");
   }
 }
 
 /// Determine whether the use of this declaration is valid, and
 /// emit any corresponding diagnostics.
 ///
 /// This routine diagnoses various problems with referencing
 /// declarations that can occur when using a declaration. For example,
 /// it might warn if a deprecated or unavailable declaration is being
 /// used, or produce an error (and return true) if a C++0x deleted
 /// function is being used.
 ///
 /// \returns true if there was an error (this declaration cannot be
 /// referenced), false otherwise.
 ///
 bool Sema::DiagnoseUseOfDecl(NamedDecl *D, ArrayRef<SourceLocation> Locs,
                              const ObjCInterfaceDecl *UnknownObjCClass,
                              bool ObjCPropertyAccess,
                              bool AvoidPartialAvailabilityChecks,
                              ObjCInterfaceDecl *ClassReceiver,
                              bool SkipTrailingRequiresClause) {
   SourceLocation Loc = Locs.front();
   if (getLangOpts().CPlusPlus && isa<FunctionDecl>(D)) {
     // If there were any diagnostics suppressed by template argument deduction,
     // emit them now.
     auto Pos = SuppressedDiagnostics.find(D->getCanonicalDecl());
     if (Pos != SuppressedDiagnostics.end()) {
       for (const PartialDiagnosticAt &Suppressed : Pos->second)
         Diag(Suppressed.first, Suppressed.second);
 
       // Clear out the list of suppressed diagnostics, so that we don't emit
       // them again for this specialization. However, we don't obsolete this
       // entry from the table, because we want to avoid ever emitting these
       // diagnostics again.
       Pos->second.clear();
     }
 
     // C++ [basic.start.main]p3:
     //   The function 'main' shall not be used within a program.
     if (cast<FunctionDecl>(D)->isMain())
       Diag(Loc, diag::ext_main_used);
 
     diagnoseUnavailableAlignedAllocation(*cast<FunctionDecl>(D), Loc);
   }
 
   // See if this is an auto-typed variable whose initializer we are parsing.
   if (ParsingInitForAutoVars.count(D)) {
     if (isa<BindingDecl>(D)) {
       Diag(Loc, diag::err_binding_cannot_appear_in_own_initializer)
         << D->getDeclName();
     } else {
       Diag(Loc, diag::err_auto_variable_cannot_appear_in_own_initializer)
         << D->getDeclName() << cast<VarDecl>(D)->getType();
     }
     return true;
   }
 
   if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
     // See if this is a deleted function.
     if (FD->isDeleted()) {
       auto *Ctor = dyn_cast<CXXConstructorDecl>(FD);
       if (Ctor && Ctor->isInheritingConstructor())
         Diag(Loc, diag::err_deleted_inherited_ctor_use)
             << Ctor->getParent()
             << Ctor->getInheritedConstructor().getConstructor()->getParent();
       else
         Diag(Loc, diag::err_deleted_function_use);
       NoteDeletedFunction(FD);
       return true;
     }
 
     // [expr.prim.id]p4
     //   A program that refers explicitly or implicitly to a function with a
     //   trailing requires-clause whose constraint-expression is not satisfied,
     //   other than to declare it, is ill-formed. [...]
     //
     // See if this is a function with constraints that need to be satisfied.
     // Check this before deducing the return type, as it might instantiate the
     // definition.
     if (!SkipTrailingRequiresClause && FD->getTrailingRequiresClause()) {
       ConstraintSatisfaction Satisfaction;
       if (CheckFunctionConstraints(FD, Satisfaction, Loc,
                                    /*ForOverloadResolution*/ true))
         // A diagnostic will have already been generated (non-constant
         // constraint expression, for example)
         return true;
       if (!Satisfaction.IsSatisfied) {
         Diag(Loc,
              diag::err_reference_to_function_with_unsatisfied_constraints)
             << D;
         DiagnoseUnsatisfiedConstraint(Satisfaction);
         return true;
       }
     }
 
     // If the function has a deduced return type, and we can't deduce it,
     // then we can't use it either.
     if (getLangOpts().CPlusPlus14 && FD->getReturnType()->isUndeducedType() &&
         DeduceReturnType(FD, Loc))
       return true;
 
     if (getLangOpts().CUDA && !CheckCUDACall(Loc, FD))
       return true;
 
   }
 
   if (auto *MD = dyn_cast<CXXMethodDecl>(D)) {
     // Lambdas are only default-constructible or assignable in C++2a onwards.
     if (MD->getParent()->isLambda() &&
         ((isa<CXXConstructorDecl>(MD) &&
           cast<CXXConstructorDecl>(MD)->isDefaultConstructor()) ||
          MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator())) {
       Diag(Loc, diag::warn_cxx17_compat_lambda_def_ctor_assign)
         << !isa<CXXConstructorDecl>(MD);
     }
   }
 
   auto getReferencedObjCProp = [](const NamedDecl *D) ->
                                       const ObjCPropertyDecl * {
     if (const auto *MD = dyn_cast<ObjCMethodDecl>(D))
       return MD->findPropertyDecl();
     return nullptr;
   };
   if (const ObjCPropertyDecl *ObjCPDecl = getReferencedObjCProp(D)) {
     if (diagnoseArgIndependentDiagnoseIfAttrs(ObjCPDecl, Loc))
       return true;
   } else if (diagnoseArgIndependentDiagnoseIfAttrs(D, Loc)) {
       return true;
   }
 
   // [OpenMP 4.0], 2.15 declare reduction Directive, Restrictions
   // Only the variables omp_in and omp_out are allowed in the combiner.
   // Only the variables omp_priv and omp_orig are allowed in the
   // initializer-clause.
   auto *DRD = dyn_cast<OMPDeclareReductionDecl>(CurContext);
   if (LangOpts.OpenMP && DRD && !CurContext->containsDecl(D) &&
       isa<VarDecl>(D)) {
     Diag(Loc, diag::err_omp_wrong_var_in_declare_reduction)
         << getCurFunction()->HasOMPDeclareReductionCombiner;
     Diag(D->getLocation(), diag::note_entity_declared_at) << D;
     return true;
   }
 
   // [OpenMP 5.0], 2.19.7.3. declare mapper Directive, Restrictions
   //  List-items in map clauses on this construct may only refer to the declared
   //  variable var and entities that could be referenced by a procedure defined
   //  at the same location.
   // [OpenMP 5.2] Also allow iterator declared variables.
   if (LangOpts.OpenMP && isa<VarDecl>(D) &&
       !isOpenMPDeclareMapperVarDeclAllowed(cast<VarDecl>(D))) {
     Diag(Loc, diag::err_omp_declare_mapper_wrong_var)
         << getOpenMPDeclareMapperVarName();
     Diag(D->getLocation(), diag::note_entity_declared_at) << D;
     return true;
   }
 
   if (const auto *EmptyD = dyn_cast<UnresolvedUsingIfExistsDecl>(D)) {
     Diag(Loc, diag::err_use_of_empty_using_if_exists);
     Diag(EmptyD->getLocation(), diag::note_empty_using_if_exists_here);
     return true;
   }
 
   DiagnoseAvailabilityOfDecl(D, Locs, UnknownObjCClass, ObjCPropertyAccess,
                              AvoidPartialAvailabilityChecks, ClassReceiver);
 
   DiagnoseUnusedOfDecl(*this, D, Loc);
 
   diagnoseUseOfInternalDeclInInlineFunction(*this, D, Loc);
 
   if (D->hasAttr<AvailableOnlyInDefaultEvalMethodAttr>()) {
     if (getLangOpts().getFPEvalMethod() !=
             LangOptions::FPEvalMethodKind::FEM_UnsetOnCommandLine &&
         PP.getLastFPEvalPragmaLocation().isValid() &&
         PP.getCurrentFPEvalMethod() != getLangOpts().getFPEvalMethod())
       Diag(D->getLocation(),
            diag::err_type_available_only_in_default_eval_method)
           << D->getName();
   }
 
   if (auto *VD = dyn_cast<ValueDecl>(D))
     checkTypeSupport(VD->getType(), Loc, VD);
 
   if (LangOpts.SYCLIsDevice ||
       (LangOpts.OpenMP && LangOpts.OpenMPIsTargetDevice)) {
     if (!Context.getTargetInfo().isTLSSupported())
       if (const auto *VD = dyn_cast<VarDecl>(D))
         if (VD->getTLSKind() != VarDecl::TLS_None)
           targetDiag(*Locs.begin(), diag::err_thread_unsupported);
   }
 
   if (isa<ParmVarDecl>(D) && isa<RequiresExprBodyDecl>(D->getDeclContext()) &&
       !isUnevaluatedContext()) {
     // C++ [expr.prim.req.nested] p3
     //   A local parameter shall only appear as an unevaluated operand
     //   (Clause 8) within the constraint-expression.
     Diag(Loc, diag::err_requires_expr_parameter_referenced_in_evaluated_context)
         << D;
     Diag(D->getLocation(), diag::note_entity_declared_at) << D;
     return true;
   }
 
   return false;
 }
 
 /// DiagnoseSentinelCalls - This routine checks whether a call or
 /// message-send is to a declaration with the sentinel attribute, and
 /// if so, it checks that the requirements of the sentinel are
 /// satisfied.
 void Sema::DiagnoseSentinelCalls(NamedDecl *D, SourceLocation Loc,
                                  ArrayRef<Expr *> Args) {
   const SentinelAttr *attr = D->getAttr<SentinelAttr>();
   if (!attr)
     return;
 
   // The number of formal parameters of the declaration.
   unsigned numFormalParams;
 
   // The kind of declaration.  This is also an index into a %select in
   // the diagnostic.
   enum CalleeType { CT_Function, CT_Method, CT_Block } calleeType;
 
   if (ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D)) {
     numFormalParams = MD->param_size();
     calleeType = CT_Method;
   } else if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
     numFormalParams = FD->param_size();
     calleeType = CT_Function;
   } else if (isa<VarDecl>(D)) {
     QualType type = cast<ValueDecl>(D)->getType();
     const FunctionType *fn = nullptr;
     if (const PointerType *ptr = type->getAs<PointerType>()) {
       fn = ptr->getPointeeType()->getAs<FunctionType>();
       if (!fn) return;
       calleeType = CT_Function;
     } else if (const BlockPointerType *ptr = type->getAs<BlockPointerType>()) {
       fn = ptr->getPointeeType()->castAs<FunctionType>();
       calleeType = CT_Block;
     } else {
       return;
     }
 
     if (const FunctionProtoType *proto = dyn_cast<FunctionProtoType>(fn)) {
       numFormalParams = proto->getNumParams();
     } else {
       numFormalParams = 0;
     }
   } else {
     return;
   }
 
   // "nullPos" is the number of formal parameters at the end which
   // effectively count as part of the variadic arguments.  This is
   // useful if you would prefer to not have *any* formal parameters,
   // but the language forces you to have at least one.
   unsigned nullPos = attr->getNullPos();
   assert((nullPos == 0 || nullPos == 1) && "invalid null position on sentinel");
   numFormalParams = (nullPos > numFormalParams ? 0 : numFormalParams - nullPos);
 
   // The number of arguments which should follow the sentinel.
   unsigned numArgsAfterSentinel = attr->getSentinel();
 
   // If there aren't enough arguments for all the formal parameters,
   // the sentinel, and the args after the sentinel, complain.
   if (Args.size() < numFormalParams + numArgsAfterSentinel + 1) {
     Diag(Loc, diag::warn_not_enough_argument) << D->getDeclName();
     Diag(D->getLocation(), diag::note_sentinel_here) << int(calleeType);
     return;
   }
 
   // Otherwise, find the sentinel expression.
   Expr *sentinelExpr = Args[Args.size() - numArgsAfterSentinel - 1];
   if (!sentinelExpr) return;
   if (sentinelExpr->isValueDependent()) return;
   if (Context.isSentinelNullExpr(sentinelExpr)) return;
 
   // Pick a reasonable string to insert.  Optimistically use 'nil', 'nullptr',
   // or 'NULL' if those are actually defined in the context.  Only use
   // 'nil' for ObjC methods, where it's much more likely that the
   // variadic arguments form a list of object pointers.
   SourceLocation MissingNilLoc = getLocForEndOfToken(sentinelExpr->getEndLoc());
   std::string NullValue;
   if (calleeType == CT_Method && PP.isMacroDefined("nil"))
     NullValue = "nil";
   else if (getLangOpts().CPlusPlus11)
     NullValue = "nullptr";
   else if (PP.isMacroDefined("NULL"))
     NullValue = "NULL";
   else
     NullValue = "(void*) 0";
 
   if (MissingNilLoc.isInvalid())
     Diag(Loc, diag::warn_missing_sentinel) << int(calleeType);
   else
     Diag(MissingNilLoc, diag::warn_missing_sentinel)
       << int(calleeType)
       << FixItHint::CreateInsertion(MissingNilLoc, ", " + NullValue);
   Diag(D->getLocation(), diag::note_sentinel_here) << int(calleeType);
 }
 
 SourceRange Sema::getExprRange(Expr *E) const {
   return E ? E->getSourceRange() : SourceRange();
 }
 
 //===----------------------------------------------------------------------===//
 //  Standard Promotions and Conversions
 //===----------------------------------------------------------------------===//
 
 /// DefaultFunctionArrayConversion (C99 6.3.2.1p3, C99 6.3.2.1p4).
 ExprResult Sema::DefaultFunctionArrayConversion(Expr *E, bool Diagnose) {
   // Handle any placeholder expressions which made it here.
   if (E->hasPlaceholderType()) {
     ExprResult result = CheckPlaceholderExpr(E);
     if (result.isInvalid()) return ExprError();
     E = result.get();
   }
 
   QualType Ty = E->getType();
   assert(!Ty.isNull() && "DefaultFunctionArrayConversion - missing type");
 
   if (Ty->isFunctionType()) {
     if (auto *DRE = dyn_cast<DeclRefExpr>(E->IgnoreParenCasts()))
       if (auto *FD = dyn_cast<FunctionDecl>(DRE->getDecl()))
         if (!checkAddressOfFunctionIsAvailable(FD, Diagnose, E->getExprLoc()))
           return ExprError();
 
     E = ImpCastExprToType(E, Context.getPointerType(Ty),
                           CK_FunctionToPointerDecay).get();
   } else if (Ty->isArrayType()) {
     // In C90 mode, arrays only promote to pointers if the array expression is
     // an lvalue.  The relevant legalese is C90 6.2.2.1p3: "an lvalue that has
     // type 'array of type' is converted to an expression that has type 'pointer
     // to type'...".  In C99 this was changed to: C99 6.3.2.1p3: "an expression
     // that has type 'array of type' ...".  The relevant change is "an lvalue"
     // (C90) to "an expression" (C99).
     //
     // C++ 4.2p1:
     // An lvalue or rvalue of type "array of N T" or "array of unknown bound of
     // T" can be converted to an rvalue of type "pointer to T".
     //
     if (getLangOpts().C99 || getLangOpts().CPlusPlus || E->isLValue()) {
       ExprResult Res = ImpCastExprToType(E, Context.getArrayDecayedType(Ty),
                                          CK_ArrayToPointerDecay);
       if (Res.isInvalid())
         return ExprError();
       E = Res.get();
     }
   }
   return E;
 }
 
 static void CheckForNullPointerDereference(Sema &S, Expr *E) {
   // Check to see if we are dereferencing a null pointer.  If so,
   // and if not volatile-qualified, this is undefined behavior that the
   // optimizer will delete, so warn about it.  People sometimes try to use this
   // to get a deterministic trap and are surprised by clang's behavior.  This
   // only handles the pattern "*null", which is a very syntactic check.
   const auto *UO = dyn_cast<UnaryOperator>(E->IgnoreParenCasts());
   if (UO && UO->getOpcode() == UO_Deref &&
       UO->getSubExpr()->getType()->isPointerType()) {
     const LangAS AS =
         UO->getSubExpr()->getType()->getPointeeType().getAddressSpace();
     if ((!isTargetAddressSpace(AS) ||
          (isTargetAddressSpace(AS) && toTargetAddressSpace(AS) == 0)) &&
         UO->getSubExpr()->IgnoreParenCasts()->isNullPointerConstant(
             S.Context, Expr::NPC_ValueDependentIsNotNull) &&
         !UO->getType().isVolatileQualified()) {
       S.DiagRuntimeBehavior(UO->getOperatorLoc(), UO,
                             S.PDiag(diag::warn_indirection_through_null)
                                 << UO->getSubExpr()->getSourceRange());
       S.DiagRuntimeBehavior(UO->getOperatorLoc(), UO,
                             S.PDiag(diag::note_indirection_through_null));
     }
   }
 }
 
 static void DiagnoseDirectIsaAccess(Sema &S, const ObjCIvarRefExpr *OIRE,
                                     SourceLocation AssignLoc,
                                     const Expr* RHS) {
   const ObjCIvarDecl *IV = OIRE->getDecl();
   if (!IV)
     return;
 
   DeclarationName MemberName = IV->getDeclName();
   IdentifierInfo *Member = MemberName.getAsIdentifierInfo();
   if (!Member || !Member->isStr("isa"))
     return;
 
   const Expr *Base = OIRE->getBase();
   QualType BaseType = Base->getType();
   if (OIRE->isArrow())
     BaseType = BaseType->getPointeeType();
   if (const ObjCObjectType *OTy = BaseType->getAs<ObjCObjectType>())
     if (ObjCInterfaceDecl *IDecl = OTy->getInterface()) {
       ObjCInterfaceDecl *ClassDeclared = nullptr;
       ObjCIvarDecl *IV = IDecl->lookupInstanceVariable(Member, ClassDeclared);
       if (!ClassDeclared->getSuperClass()
           && (*ClassDeclared->ivar_begin()) == IV) {
         if (RHS) {
           NamedDecl *ObjectSetClass =
             S.LookupSingleName(S.TUScope,
                                &S.Context.Idents.get("object_setClass"),
                                SourceLocation(), S.LookupOrdinaryName);
           if (ObjectSetClass) {
             SourceLocation RHSLocEnd = S.getLocForEndOfToken(RHS->getEndLoc());
             S.Diag(OIRE->getExprLoc(), diag::warn_objc_isa_assign)
                 << FixItHint::CreateInsertion(OIRE->getBeginLoc(),
                                               "object_setClass(")
                 << FixItHint::CreateReplacement(
                        SourceRange(OIRE->getOpLoc(), AssignLoc), ",")
                 << FixItHint::CreateInsertion(RHSLocEnd, ")");
           }
           else
             S.Diag(OIRE->getLocation(), diag::warn_objc_isa_assign);
         } else {
           NamedDecl *ObjectGetClass =
             S.LookupSingleName(S.TUScope,
                                &S.Context.Idents.get("object_getClass"),
                                SourceLocation(), S.LookupOrdinaryName);
           if (ObjectGetClass)
             S.Diag(OIRE->getExprLoc(), diag::warn_objc_isa_use)
                 << FixItHint::CreateInsertion(OIRE->getBeginLoc(),
                                               "object_getClass(")
                 << FixItHint::CreateReplacement(
                        SourceRange(OIRE->getOpLoc(), OIRE->getEndLoc()), ")");
           else
             S.Diag(OIRE->getLocation(), diag::warn_objc_isa_use);
         }
         S.Diag(IV->getLocation(), diag::note_ivar_decl);
       }
     }
 }
 
 ExprResult Sema::DefaultLvalueConversion(Expr *E) {
   // Handle any placeholder expressions which made it here.
   if (E->hasPlaceholderType()) {
     ExprResult result = CheckPlaceholderExpr(E);
     if (result.isInvalid()) return ExprError();
     E = result.get();
   }
 
   // C++ [conv.lval]p1:
   //   A glvalue of a non-function, non-array type T can be
   //   converted to a prvalue.
   if (!E->isGLValue()) return E;
 
   QualType T = E->getType();
   assert(!T.isNull() && "r-value conversion on typeless expression?");
 
   // lvalue-to-rvalue conversion cannot be applied to function or array types.
   if (T->isFunctionType() || T->isArrayType())
     return E;
 
   // We don't want to throw lvalue-to-rvalue casts on top of
   // expressions of certain types in C++.
   if (getLangOpts().CPlusPlus &&
       (E->getType() == Context.OverloadTy ||
        T->isDependentType() ||
        T->isRecordType()))
     return E;
 
   // The C standard is actually really unclear on this point, and
   // DR106 tells us what the result should be but not why.  It's
   // generally best to say that void types just doesn't undergo
   // lvalue-to-rvalue at all.  Note that expressions of unqualified
   // 'void' type are never l-values, but qualified void can be.
   if (T->isVoidType())
     return E;
 
   // OpenCL usually rejects direct accesses to values of 'half' type.
   if (getLangOpts().OpenCL &&
       !getOpenCLOptions().isAvailableOption("cl_khr_fp16", getLangOpts()) &&
       T->isHalfType()) {
     Diag(E->getExprLoc(), diag::err_opencl_half_load_store)
       << 0 << T;
     return ExprError();
   }
 
   CheckForNullPointerDereference(*this, E);
   if (const ObjCIsaExpr *OISA = dyn_cast<ObjCIsaExpr>(E->IgnoreParenCasts())) {
     NamedDecl *ObjectGetClass = LookupSingleName(TUScope,
                                      &Context.Idents.get("object_getClass"),
                                      SourceLocation(), LookupOrdinaryName);
     if (ObjectGetClass)
       Diag(E->getExprLoc(), diag::warn_objc_isa_use)
           << FixItHint::CreateInsertion(OISA->getBeginLoc(), "object_getClass(")
           << FixItHint::CreateReplacement(
                  SourceRange(OISA->getOpLoc(), OISA->getIsaMemberLoc()), ")");
     else
       Diag(E->getExprLoc(), diag::warn_objc_isa_use);
   }
   else if (const ObjCIvarRefExpr *OIRE =
             dyn_cast<ObjCIvarRefExpr>(E->IgnoreParenCasts()))
     DiagnoseDirectIsaAccess(*this, OIRE, SourceLocation(), /* Expr*/nullptr);
 
   // C++ [conv.lval]p1:
   //   [...] If T is a non-class type, the type of the prvalue is the
   //   cv-unqualified version of T. Otherwise, the type of the
   //   rvalue is T.
   //
   // C99 6.3.2.1p2:
   //   If the lvalue has qualified type, the value has the unqualified
   //   version of the type of the lvalue; otherwise, the value has the
   //   type of the lvalue.
   if (T.hasQualifiers())
     T = T.getUnqualifiedType();
 
   // Under the MS ABI, lock down the inheritance model now.
   if (T->isMemberPointerType() &&
       Context.getTargetInfo().getCXXABI().isMicrosoft())
     (void)isCompleteType(E->getExprLoc(), T);
 
   ExprResult Res = CheckLValueToRValueConversionOperand(E);
   if (Res.isInvalid())
     return Res;
   E = Res.get();
 
   // Loading a __weak object implicitly retains the value, so we need a cleanup to
   // balance that.
   if (E->getType().getObjCLifetime() == Qualifiers::OCL_Weak)
     Cleanup.setExprNeedsCleanups(true);
 
   if (E->getType().isDestructedType() == QualType::DK_nontrivial_c_struct)
     Cleanup.setExprNeedsCleanups(true);
 
   // C++ [conv.lval]p3:
   //   If T is cv std::nullptr_t, the result is a null pointer constant.
   CastKind CK = T->isNullPtrType() ? CK_NullToPointer : CK_LValueToRValue;
   Res = ImplicitCastExpr::Create(Context, T, CK, E, nullptr, VK_PRValue,
                                  CurFPFeatureOverrides());
 
   // C11 6.3.2.1p2:
   //   ... if the lvalue has atomic type, the value has the non-atomic version
   //   of the type of the lvalue ...
   if (const AtomicType *Atomic = T->getAs<AtomicType>()) {
     T = Atomic->getValueType().getUnqualifiedType();
     Res = ImplicitCastExpr::Create(Context, T, CK_AtomicToNonAtomic, Res.get(),
                                    nullptr, VK_PRValue, FPOptionsOverride());
   }
 
   return Res;
 }
 
 ExprResult Sema::DefaultFunctionArrayLvalueConversion(Expr *E, bool Diagnose) {
   ExprResult Res = DefaultFunctionArrayConversion(E, Diagnose);
   if (Res.isInvalid())
     return ExprError();
   Res = DefaultLvalueConversion(Res.get());
   if (Res.isInvalid())
     return ExprError();
   return Res;
 }
 
 /// CallExprUnaryConversions - a special case of an unary conversion
 /// performed on a function designator of a call expression.
 ExprResult Sema::CallExprUnaryConversions(Expr *E) {
   QualType Ty = E->getType();
   ExprResult Res = E;
   // Only do implicit cast for a function type, but not for a pointer
   // to function type.
   if (Ty->isFunctionType()) {
     Res = ImpCastExprToType(E, Context.getPointerType(Ty),
                             CK_FunctionToPointerDecay);
     if (Res.isInvalid())
       return ExprError();
   }
   Res = DefaultLvalueConversion(Res.get());
   if (Res.isInvalid())
     return ExprError();
   return Res.get();
 }
 
 /// UsualUnaryConversions - Performs various conversions that are common to most
 /// operators (C99 6.3). The conversions of array and function types are
 /// sometimes suppressed. For example, the array->pointer conversion doesn't
 /// apply if the array is an argument to the sizeof or address (&) operators.
 /// In these instances, this routine should *not* be called.
 ExprResult Sema::UsualUnaryConversions(Expr *E) {
   // First, convert to an r-value.
   ExprResult Res = DefaultFunctionArrayLvalueConversion(E);
   if (Res.isInvalid())
     return ExprError();
   E = Res.get();
 
   QualType Ty = E->getType();
   assert(!Ty.isNull() && "UsualUnaryConversions - missing type");
 
   LangOptions::FPEvalMethodKind EvalMethod = CurFPFeatures.getFPEvalMethod();
   if (EvalMethod != LangOptions::FEM_Source && Ty->isFloatingType() &&
       (getLangOpts().getFPEvalMethod() !=
            LangOptions::FPEvalMethodKind::FEM_UnsetOnCommandLine ||
        PP.getLastFPEvalPragmaLocation().isValid())) {
     switch (EvalMethod) {
     default:
       llvm_unreachable("Unrecognized float evaluation method");
       break;
     case LangOptions::FEM_UnsetOnCommandLine:
       llvm_unreachable("Float evaluation method should be set by now");
       break;
     case LangOptions::FEM_Double:
       if (Context.getFloatingTypeOrder(Context.DoubleTy, Ty) > 0)
         // Widen the expression to double.
         return Ty->isComplexType()
                    ? ImpCastExprToType(E,
                                        Context.getComplexType(Context.DoubleTy),
                                        CK_FloatingComplexCast)
                    : ImpCastExprToType(E, Context.DoubleTy, CK_FloatingCast);
       break;
     case LangOptions::FEM_Extended:
       if (Context.getFloatingTypeOrder(Context.LongDoubleTy, Ty) > 0)
         // Widen the expression to long double.
         return Ty->isComplexType()
                    ? ImpCastExprToType(
                          E, Context.getComplexType(Context.LongDoubleTy),
                          CK_FloatingComplexCast)
                    : ImpCastExprToType(E, Context.LongDoubleTy,
                                        CK_FloatingCast);
       break;
     }
   }
 
   // Half FP have to be promoted to float unless it is natively supported
   if (Ty->isHalfType() && !getLangOpts().NativeHalfType)
     return ImpCastExprToType(Res.get(), Context.FloatTy, CK_FloatingCast);
 
   // Try to perform integral promotions if the object has a theoretically
   // promotable type.
   if (Ty->isIntegralOrUnscopedEnumerationType()) {
     // C99 6.3.1.1p2:
     //
     //   The following may be used in an expression wherever an int or
     //   unsigned int may be used:
     //     - an object or expression with an integer type whose integer
     //       conversion rank is less than or equal to the rank of int
     //       and unsigned int.
     //     - A bit-field of type _Bool, int, signed int, or unsigned int.
     //
     //   If an int can represent all values of the original type, the
     //   value is converted to an int; otherwise, it is converted to an
     //   unsigned int. These are called the integer promotions. All
     //   other types are unchanged by the integer promotions.
 
     QualType PTy = Context.isPromotableBitField(E);
     if (!PTy.isNull()) {
       E = ImpCastExprToType(E, PTy, CK_IntegralCast).get();
       return E;
     }
     if (Context.isPromotableIntegerType(Ty)) {
       QualType PT = Context.getPromotedIntegerType(Ty);
       E = ImpCastExprToType(E, PT, CK_IntegralCast).get();
       return E;
     }
   }
   return E;
 }
 
 /// DefaultArgumentPromotion (C99 6.5.2.2p6). Used for function calls that
 /// do not have a prototype. Arguments that have type float or __fp16
 /// are promoted to double. All other argument types are converted by
 /// UsualUnaryConversions().
 ExprResult Sema::DefaultArgumentPromotion(Expr *E) {
   QualType Ty = E->getType();
   assert(!Ty.isNull() && "DefaultArgumentPromotion - missing type");
 
   ExprResult Res = UsualUnaryConversions(E);
   if (Res.isInvalid())
     return ExprError();
   E = Res.get();
 
   // If this is a 'float'  or '__fp16' (CVR qualified or typedef)
   // promote to double.
   // Note that default argument promotion applies only to float (and
   // half/fp16); it does not apply to _Float16.
   const BuiltinType *BTy = Ty->getAs<BuiltinType>();
   if (BTy && (BTy->getKind() == BuiltinType::Half ||
               BTy->getKind() == BuiltinType::Float)) {
     if (getLangOpts().OpenCL &&
         !getOpenCLOptions().isAvailableOption("cl_khr_fp64", getLangOpts())) {
       if (BTy->getKind() == BuiltinType::Half) {
         E = ImpCastExprToType(E, Context.FloatTy, CK_FloatingCast).get();
       }
     } else {
       E = ImpCastExprToType(E, Context.DoubleTy, CK_FloatingCast).get();
     }
   }
   if (BTy &&
       getLangOpts().getExtendIntArgs() ==
           LangOptions::ExtendArgsKind::ExtendTo64 &&
       Context.getTargetInfo().supportsExtendIntArgs() && Ty->isIntegerType() &&
       Context.getTypeSizeInChars(BTy) <
           Context.getTypeSizeInChars(Context.LongLongTy)) {
     E = (Ty->isUnsignedIntegerType())
             ? ImpCastExprToType(E, Context.UnsignedLongLongTy, CK_IntegralCast)
                   .get()
             : ImpCastExprToType(E, Context.LongLongTy, CK_IntegralCast).get();
     assert(8 == Context.getTypeSizeInChars(Context.LongLongTy).getQuantity() &&
            "Unexpected typesize for LongLongTy");
   }
 
   // C++ performs lvalue-to-rvalue conversion as a default argument
   // promotion, even on class types, but note:
   //   C++11 [conv.lval]p2:
   //     When an lvalue-to-rvalue conversion occurs in an unevaluated
   //     operand or a subexpression thereof the value contained in the
   //     referenced object is not accessed. Otherwise, if the glvalue
   //     has a class type, the conversion copy-initializes a temporary
   //     of type T from the glvalue and the result of the conversion
   //     is a prvalue for the temporary.
   // FIXME: add some way to gate this entire thing for correctness in
   // potentially potentially evaluated contexts.
   if (getLangOpts().CPlusPlus && E->isGLValue() && !isUnevaluatedContext()) {
     ExprResult Temp = PerformCopyInitialization(
                        InitializedEntity::InitializeTemporary(E->getType()),
                                                 E->getExprLoc(), E);
     if (Temp.isInvalid())
       return ExprError();
     E = Temp.get();
   }
 
   return E;
 }
 
 /// Determine the degree of POD-ness for an expression.
 /// Incomplete types are considered POD, since this check can be performed
 /// when we're in an unevaluated context.
 Sema::VarArgKind Sema::isValidVarArgType(const QualType &Ty) {
   if (Ty->isIncompleteType()) {
     // C++11 [expr.call]p7:
     //   After these conversions, if the argument does not have arithmetic,
     //   enumeration, pointer, pointer to member, or class type, the program
     //   is ill-formed.
     //
     // Since we've already performed array-to-pointer and function-to-pointer
     // decay, the only such type in C++ is cv void. This also handles
     // initializer lists as variadic arguments.
     if (Ty->isVoidType())
       return VAK_Invalid;
 
     if (Ty->isObjCObjectType())
       return VAK_Invalid;
     return VAK_Valid;
   }
 
   if (Ty.isDestructedType() == QualType::DK_nontrivial_c_struct)
     return VAK_Invalid;
 
   if (Context.getTargetInfo().getTriple().isWasm() &&
       Ty.isWebAssemblyReferenceType()) {
     return VAK_Invalid;
   }
 
   if (Ty.isCXX98PODType(Context))
     return VAK_Valid;
 
   // C++11 [expr.call]p7:
   //   Passing a potentially-evaluated argument of class type (Clause 9)
   //   having a non-trivial copy constructor, a non-trivial move constructor,
   //   or a non-trivial destructor, with no corresponding parameter,
   //   is conditionally-supported with implementation-defined semantics.
   if (getLangOpts().CPlusPlus11 && !Ty->isDependentType())
     if (CXXRecordDecl *Record = Ty->getAsCXXRecordDecl())
       if (!Record->hasNonTrivialCopyConstructor() &&
           !Record->hasNonTrivialMoveConstructor() &&
           !Record->hasNonTrivialDestructor())
         return VAK_ValidInCXX11;
 
   if (getLangOpts().ObjCAutoRefCount && Ty->isObjCLifetimeType())
     return VAK_Valid;
 
   if (Ty->isObjCObjectType())
     return VAK_Invalid;
 
   if (getLangOpts().MSVCCompat)
     return VAK_MSVCUndefined;
 
   // FIXME: In C++11, these cases are conditionally-supported, meaning we're
   // permitted to reject them. We should consider doing so.
   return VAK_Undefined;
 }
 
 void Sema::checkVariadicArgument(const Expr *E, VariadicCallType CT) {
   // Don't allow one to pass an Objective-C interface to a vararg.
   const QualType &Ty = E->getType();
   VarArgKind VAK = isValidVarArgType(Ty);
 
   // Complain about passing non-POD types through varargs.
   switch (VAK) {
   case VAK_ValidInCXX11:
     DiagRuntimeBehavior(
         E->getBeginLoc(), nullptr,
         PDiag(diag::warn_cxx98_compat_pass_non_pod_arg_to_vararg) << Ty << CT);
     [[fallthrough]];
   case VAK_Valid:
     if (Ty->isRecordType()) {
       // This is unlikely to be what the user intended. If the class has a
       // 'c_str' member function, the user probably meant to call that.
       DiagRuntimeBehavior(E->getBeginLoc(), nullptr,
                           PDiag(diag::warn_pass_class_arg_to_vararg)
                               << Ty << CT << hasCStrMethod(E) << ".c_str()");
     }
     break;
 
   case VAK_Undefined:
   case VAK_MSVCUndefined:
     DiagRuntimeBehavior(E->getBeginLoc(), nullptr,
                         PDiag(diag::warn_cannot_pass_non_pod_arg_to_vararg)
                             << getLangOpts().CPlusPlus11 << Ty << CT);
     break;
 
   case VAK_Invalid:
     if (Ty.isDestructedType() == QualType::DK_nontrivial_c_struct)
       Diag(E->getBeginLoc(),
            diag::err_cannot_pass_non_trivial_c_struct_to_vararg)
           << Ty << CT;
     else if (Ty->isObjCObjectType())
       DiagRuntimeBehavior(E->getBeginLoc(), nullptr,
                           PDiag(diag::err_cannot_pass_objc_interface_to_vararg)
                               << Ty << CT);
     else
       Diag(E->getBeginLoc(), diag::err_cannot_pass_to_vararg)
           << isa<InitListExpr>(E) << Ty << CT;
     break;
   }
 }
 
 /// DefaultVariadicArgumentPromotion - Like DefaultArgumentPromotion, but
 /// will create a trap if the resulting type is not a POD type.
 ExprResult Sema::DefaultVariadicArgumentPromotion(Expr *E, VariadicCallType CT,
                                                   FunctionDecl *FDecl) {
   if (const BuiltinType *PlaceholderTy = E->getType()->getAsPlaceholderType()) {
     // Strip the unbridged-cast placeholder expression off, if applicable.
     if (PlaceholderTy->getKind() == BuiltinType::ARCUnbridgedCast &&
         (CT == VariadicMethod ||
          (FDecl && FDecl->hasAttr<CFAuditedTransferAttr>()))) {
       E = stripARCUnbridgedCast(E);
 
     // Otherwise, do normal placeholder checking.
     } else {
       ExprResult ExprRes = CheckPlaceholderExpr(E);
       if (ExprRes.isInvalid())
         return ExprError();
       E = ExprRes.get();
     }
   }
 
   ExprResult ExprRes = DefaultArgumentPromotion(E);
   if (ExprRes.isInvalid())
     return ExprError();
 
   // Copy blocks to the heap.
   if (ExprRes.get()->getType()->isBlockPointerType())
     maybeExtendBlockObject(ExprRes);
 
   E = ExprRes.get();
 
   // Diagnostics regarding non-POD argument types are
   // emitted along with format string checking in Sema::CheckFunctionCall().
   if (isValidVarArgType(E->getType()) == VAK_Undefined) {
     // Turn this into a trap.
     CXXScopeSpec SS;
     SourceLocation TemplateKWLoc;
     UnqualifiedId Name;
     Name.setIdentifier(PP.getIdentifierInfo("__builtin_trap"),
                        E->getBeginLoc());
     ExprResult TrapFn = ActOnIdExpression(TUScope, SS, TemplateKWLoc, Name,
                                           /*HasTrailingLParen=*/true,
                                           /*IsAddressOfOperand=*/false);
     if (TrapFn.isInvalid())
       return ExprError();
 
     ExprResult Call = BuildCallExpr(TUScope, TrapFn.get(), E->getBeginLoc(),
                                     std::nullopt, E->getEndLoc());
     if (Call.isInvalid())
       return ExprError();
 
     ExprResult Comma =
         ActOnBinOp(TUScope, E->getBeginLoc(), tok::comma, Call.get(), E);
     if (Comma.isInvalid())
       return ExprError();
     return Comma.get();
   }
 
   if (!getLangOpts().CPlusPlus &&
       RequireCompleteType(E->getExprLoc(), E->getType(),
                           diag::err_call_incomplete_argument))
     return ExprError();
 
   return E;
 }
 
 /// Converts an integer to complex float type.  Helper function of
 /// UsualArithmeticConversions()
 ///
 /// \return false if the integer expression is an integer type and is
 /// successfully converted to the complex type.
 static bool handleIntegerToComplexFloatConversion(Sema &S, ExprResult &IntExpr,
                                                   ExprResult &ComplexExpr,
                                                   QualType IntTy,
                                                   QualType ComplexTy,
                                                   bool SkipCast) {
   if (IntTy->isComplexType() || IntTy->isRealFloatingType()) return true;
   if (SkipCast) return false;
   if (IntTy->isIntegerType()) {
     QualType fpTy = ComplexTy->castAs<ComplexType>()->getElementType();
     IntExpr = S.ImpCastExprToType(IntExpr.get(), fpTy, CK_IntegralToFloating);
     IntExpr = S.ImpCastExprToType(IntExpr.get(), ComplexTy,
                                   CK_FloatingRealToComplex);
   } else {
     assert(IntTy->isComplexIntegerType());
     IntExpr = S.ImpCastExprToType(IntExpr.get(), ComplexTy,
                                   CK_IntegralComplexToFloatingComplex);
   }
   return false;
 }
 
 // This handles complex/complex, complex/float, or float/complex.
 // When both operands are complex, the shorter operand is converted to the
 // type of the longer, and that is the type of the result. This corresponds
 // to what is done when combining two real floating-point operands.
 // The fun begins when size promotion occur across type domains.
 // From H&S 6.3.4: When one operand is complex and the other is a real
 // floating-point type, the less precise type is converted, within it's
 // real or complex domain, to the precision of the other type. For example,
 // when combining a "long double" with a "double _Complex", the
 // "double _Complex" is promoted to "long double _Complex".
 static QualType handleComplexFloatConversion(Sema &S, ExprResult &Shorter,
                                              QualType ShorterType,
                                              QualType LongerType,
                                              bool PromotePrecision) {
   bool LongerIsComplex = isa<ComplexType>(LongerType.getCanonicalType());
   QualType Result =
       LongerIsComplex ? LongerType : S.Context.getComplexType(LongerType);
 
   if (PromotePrecision) {
     if (isa<ComplexType>(ShorterType.getCanonicalType())) {
       Shorter =
           S.ImpCastExprToType(Shorter.get(), Result, CK_FloatingComplexCast);
     } else {
       if (LongerIsComplex)
         LongerType = LongerType->castAs<ComplexType>()->getElementType();
       Shorter = S.ImpCastExprToType(Shorter.get(), LongerType, CK_FloatingCast);
     }
   }
   return Result;
 }
 
 /// Handle arithmetic conversion with complex types.  Helper function of
 /// UsualArithmeticConversions()
 static QualType handleComplexConversion(Sema &S, ExprResult &LHS,
                                         ExprResult &RHS, QualType LHSType,
                                         QualType RHSType, bool IsCompAssign) {
   // if we have an integer operand, the result is the complex type.
   if (!handleIntegerToComplexFloatConversion(S, RHS, LHS, RHSType, LHSType,
                                              /*SkipCast=*/false))
     return LHSType;
   if (!handleIntegerToComplexFloatConversion(S, LHS, RHS, LHSType, RHSType,
                                              /*SkipCast=*/IsCompAssign))
     return RHSType;
 
   // Compute the rank of the two types, regardless of whether they are complex.
   int Order = S.Context.getFloatingTypeOrder(LHSType, RHSType);
   if (Order < 0)
     // Promote the precision of the LHS if not an assignment.
     return handleComplexFloatConversion(S, LHS, LHSType, RHSType,
                                         /*PromotePrecision=*/!IsCompAssign);
   // Promote the precision of the RHS unless it is already the same as the LHS.
   return handleComplexFloatConversion(S, RHS, RHSType, LHSType,
                                       /*PromotePrecision=*/Order > 0);
 }
 
 /// Handle arithmetic conversion from integer to float.  Helper function
 /// of UsualArithmeticConversions()
 static QualType handleIntToFloatConversion(Sema &S, ExprResult &FloatExpr,
                                            ExprResult &IntExpr,
                                            QualType FloatTy, QualType IntTy,
                                            bool ConvertFloat, bool ConvertInt) {
   if (IntTy->isIntegerType()) {
     if (ConvertInt)
       // Convert intExpr to the lhs floating point type.
       IntExpr = S.ImpCastExprToType(IntExpr.get(), FloatTy,
                                     CK_IntegralToFloating);
     return FloatTy;
   }
 
   // Convert both sides to the appropriate complex float.
   assert(IntTy->isComplexIntegerType());
   QualType result = S.Context.getComplexType(FloatTy);
 
   // _Complex int -> _Complex float
   if (ConvertInt)
     IntExpr = S.ImpCastExprToType(IntExpr.get(), result,
                                   CK_IntegralComplexToFloatingComplex);
 
   // float -> _Complex float
   if (ConvertFloat)
     FloatExpr = S.ImpCastExprToType(FloatExpr.get(), result,
                                     CK_FloatingRealToComplex);
 
   return result;
 }
 
 /// Handle arithmethic conversion with floating point types.  Helper
 /// function of UsualArithmeticConversions()
 static QualType handleFloatConversion(Sema &S, ExprResult &LHS,
                                       ExprResult &RHS, QualType LHSType,
                                       QualType RHSType, bool IsCompAssign) {
   bool LHSFloat = LHSType->isRealFloatingType();
   bool RHSFloat = RHSType->isRealFloatingType();
 
   // N1169 4.1.4: If one of the operands has a floating type and the other
   //              operand has a fixed-point type, the fixed-point operand
   //              is converted to the floating type [...]
   if (LHSType->isFixedPointType() || RHSType->isFixedPointType()) {
     if (LHSFloat)
       RHS = S.ImpCastExprToType(RHS.get(), LHSType, CK_FixedPointToFloating);
     else if (!IsCompAssign)
       LHS = S.ImpCastExprToType(LHS.get(), RHSType, CK_FixedPointToFloating);
     return LHSFloat ? LHSType : RHSType;
   }
 
   // If we have two real floating types, convert the smaller operand
   // to the bigger result.
   if (LHSFloat && RHSFloat) {
     int order = S.Context.getFloatingTypeOrder(LHSType, RHSType);
     if (order > 0) {
       RHS = S.ImpCastExprToType(RHS.get(), LHSType, CK_FloatingCast);
       return LHSType;
     }
 
     assert(order < 0 && "illegal float comparison");
     if (!IsCompAssign)
       LHS = S.ImpCastExprToType(LHS.get(), RHSType, CK_FloatingCast);
     return RHSType;
   }
 
   if (LHSFloat) {
     // Half FP has to be promoted to float unless it is natively supported
     if (LHSType->isHalfType() && !S.getLangOpts().NativeHalfType)
       LHSType = S.Context.FloatTy;
 
     return handleIntToFloatConversion(S, LHS, RHS, LHSType, RHSType,
                                       /*ConvertFloat=*/!IsCompAssign,
                                       /*ConvertInt=*/ true);
   }
   assert(RHSFloat);
   return handleIntToFloatConversion(S, RHS, LHS, RHSType, LHSType,
                                     /*ConvertFloat=*/ true,
                                     /*ConvertInt=*/!IsCompAssign);
 }
 
 /// Diagnose attempts to convert between __float128, __ibm128 and
 /// long double if there is no support for such conversion.
 /// Helper function of UsualArithmeticConversions().
 static bool unsupportedTypeConversion(const Sema &S, QualType LHSType,
                                       QualType RHSType) {
   // No issue if either is not a floating point type.
   if (!LHSType->isFloatingType() || !RHSType->isFloatingType())
     return false;
 
   // No issue if both have the same 128-bit float semantics.
   auto *LHSComplex = LHSType->getAs<ComplexType>();
   auto *RHSComplex = RHSType->getAs<ComplexType>();
 
   QualType LHSElem = LHSComplex ? LHSComplex->getElementType() : LHSType;
   QualType RHSElem = RHSComplex ? RHSComplex->getElementType() : RHSType;
 
   const llvm::fltSemantics &LHSSem = S.Context.getFloatTypeSemantics(LHSElem);
   const llvm::fltSemantics &RHSSem = S.Context.getFloatTypeSemantics(RHSElem);
 
   if ((&LHSSem != &llvm::APFloat::PPCDoubleDouble() ||
        &RHSSem != &llvm::APFloat::IEEEquad()) &&
       (&LHSSem != &llvm::APFloat::IEEEquad() ||
        &RHSSem != &llvm::APFloat::PPCDoubleDouble()))
     return false;
 
   return true;
 }
 
 typedef ExprResult PerformCastFn(Sema &S, Expr *operand, QualType toType);
 
 namespace {
 /// These helper callbacks are placed in an anonymous namespace to
 /// permit their use as function template parameters.
 ExprResult doIntegralCast(Sema &S, Expr *op, QualType toType) {
   return S.ImpCastExprToType(op, toType, CK_IntegralCast);
 }
 
 ExprResult doComplexIntegralCast(Sema &S, Expr *op, QualType toType) {
   return S.ImpCastExprToType(op, S.Context.getComplexType(toType),
                              CK_IntegralComplexCast);
 }
 }
 
 /// Handle integer arithmetic conversions.  Helper function of
 /// UsualArithmeticConversions()
 template <PerformCastFn doLHSCast, PerformCastFn doRHSCast>
 static QualType handleIntegerConversion(Sema &S, ExprResult &LHS,
                                         ExprResult &RHS, QualType LHSType,
                                         QualType RHSType, bool IsCompAssign) {
   // The rules for this case are in C99 6.3.1.8
   int order = S.Context.getIntegerTypeOrder(LHSType, RHSType);
   bool LHSSigned = LHSType->hasSignedIntegerRepresentation();
   bool RHSSigned = RHSType->hasSignedIntegerRepresentation();
   if (LHSSigned == RHSSigned) {
     // Same signedness; use the higher-ranked type
     if (order >= 0) {
       RHS = (*doRHSCast)(S, RHS.get(), LHSType);
       return LHSType;
     } else if (!IsCompAssign)
       LHS = (*doLHSCast)(S, LHS.get(), RHSType);
     return RHSType;
   } else if (order != (LHSSigned ? 1 : -1)) {
     // The unsigned type has greater than or equal rank to the
     // signed type, so use the unsigned type
     if (RHSSigned) {
       RHS = (*doRHSCast)(S, RHS.get(), LHSType);
       return LHSType;
     } else if (!IsCompAssign)
       LHS = (*doLHSCast)(S, LHS.get(), RHSType);
     return RHSType;
   } else if (S.Context.getIntWidth(LHSType) != S.Context.getIntWidth(RHSType)) {
     // The two types are different widths; if we are here, that
     // means the signed type is larger than the unsigned type, so
     // use the signed type.
     if (LHSSigned) {
       RHS = (*doRHSCast)(S, RHS.get(), LHSType);
       return LHSType;
     } else if (!IsCompAssign)
       LHS = (*doLHSCast)(S, LHS.get(), RHSType);
     return RHSType;
   } else {
     // The signed type is higher-ranked than the unsigned type,
     // but isn't actually any bigger (like unsigned int and long
     // on most 32-bit systems).  Use the unsigned type corresponding
     // to the signed type.
     QualType result =
       S.Context.getCorrespondingUnsignedType(LHSSigned ? LHSType : RHSType);
     RHS = (*doRHSCast)(S, RHS.get(), result);
     if (!IsCompAssign)
       LHS = (*doLHSCast)(S, LHS.get(), result);
     return result;
   }
 }
 
 /// Handle conversions with GCC complex int extension.  Helper function
 /// of UsualArithmeticConversions()
 static QualType handleComplexIntConversion(Sema &S, ExprResult &LHS,
                                            ExprResult &RHS, QualType LHSType,
                                            QualType RHSType,
                                            bool IsCompAssign) {
   const ComplexType *LHSComplexInt = LHSType->getAsComplexIntegerType();
   const ComplexType *RHSComplexInt = RHSType->getAsComplexIntegerType();
 
   if (LHSComplexInt && RHSComplexInt) {
     QualType LHSEltType = LHSComplexInt->getElementType();
     QualType RHSEltType = RHSComplexInt->getElementType();
     QualType ScalarType =
       handleIntegerConversion<doComplexIntegralCast, doComplexIntegralCast>
         (S, LHS, RHS, LHSEltType, RHSEltType, IsCompAssign);
 
     return S.Context.getComplexType(ScalarType);
   }
 
   if (LHSComplexInt) {
     QualType LHSEltType = LHSComplexInt->getElementType();
     QualType ScalarType =
       handleIntegerConversion<doComplexIntegralCast, doIntegralCast>
         (S, LHS, RHS, LHSEltType, RHSType, IsCompAssign);
     QualType ComplexType = S.Context.getComplexType(ScalarType);
     RHS = S.ImpCastExprToType(RHS.get(), ComplexType,
                               CK_IntegralRealToComplex);
 
     return ComplexType;
   }
 
   assert(RHSComplexInt);
 
   QualType RHSEltType = RHSComplexInt->getElementType();
   QualType ScalarType =
     handleIntegerConversion<doIntegralCast, doComplexIntegralCast>
       (S, LHS, RHS, LHSType, RHSEltType, IsCompAssign);
   QualType ComplexType = S.Context.getComplexType(ScalarType);
 
   if (!IsCompAssign)
     LHS = S.ImpCastExprToType(LHS.get(), ComplexType,
                               CK_IntegralRealToComplex);
   return ComplexType;
 }
 
 /// Return the rank of a given fixed point or integer type. The value itself
 /// doesn't matter, but the values must be increasing with proper increasing
 /// rank as described in N1169 4.1.1.
 static unsigned GetFixedPointRank(QualType Ty) {
   const auto *BTy = Ty->getAs<BuiltinType>();
   assert(BTy && "Expected a builtin type.");
 
   switch (BTy->getKind()) {
   case BuiltinType::ShortFract:
   case BuiltinType::UShortFract:
   case BuiltinType::SatShortFract:
   case BuiltinType::SatUShortFract:
     return 1;
   case BuiltinType::Fract:
   case BuiltinType::UFract:
   case BuiltinType::SatFract:
   case BuiltinType::SatUFract:
     return 2;
   case BuiltinType::LongFract:
   case BuiltinType::ULongFract:
   case BuiltinType::SatLongFract:
   case BuiltinType::SatULongFract:
     return 3;
   case BuiltinType::ShortAccum:
   case BuiltinType::UShortAccum:
   case BuiltinType::SatShortAccum:
   case BuiltinType::SatUShortAccum:
     return 4;
   case BuiltinType::Accum:
   case BuiltinType::UAccum:
   case BuiltinType::SatAccum:
   case BuiltinType::SatUAccum:
     return 5;
   case BuiltinType::LongAccum:
   case BuiltinType::ULongAccum:
   case BuiltinType::SatLongAccum:
   case BuiltinType::SatULongAccum:
     return 6;
   default:
     if (BTy->isInteger())
       return 0;
     llvm_unreachable("Unexpected fixed point or integer type");
   }
 }
 
 /// handleFixedPointConversion - Fixed point operations between fixed
 /// point types and integers or other fixed point types do not fall under
 /// usual arithmetic conversion since these conversions could result in loss
 /// of precsision (N1169 4.1.4). These operations should be calculated with
 /// the full precision of their result type (N1169 4.1.6.2.1).
 static QualType handleFixedPointConversion(Sema &S, QualType LHSTy,
                                            QualType RHSTy) {
   assert((LHSTy->isFixedPointType() || RHSTy->isFixedPointType()) &&
          "Expected at least one of the operands to be a fixed point type");
   assert((LHSTy->isFixedPointOrIntegerType() ||
           RHSTy->isFixedPointOrIntegerType()) &&
          "Special fixed point arithmetic operation conversions are only "
          "applied to ints or other fixed point types");
 
   // If one operand has signed fixed-point type and the other operand has
   // unsigned fixed-point type, then the unsigned fixed-point operand is
   // converted to its corresponding signed fixed-point type and the resulting
   // type is the type of the converted operand.
   if (RHSTy->isSignedFixedPointType() && LHSTy->isUnsignedFixedPointType())
     LHSTy = S.Context.getCorrespondingSignedFixedPointType(LHSTy);
   else if (RHSTy->isUnsignedFixedPointType() && LHSTy->isSignedFixedPointType())
     RHSTy = S.Context.getCorrespondingSignedFixedPointType(RHSTy);
 
   // The result type is the type with the highest rank, whereby a fixed-point
   // conversion rank is always greater than an integer conversion rank; if the
   // type of either of the operands is a saturating fixedpoint type, the result
   // type shall be the saturating fixed-point type corresponding to the type
   // with the highest rank; the resulting value is converted (taking into
   // account rounding and overflow) to the precision of the resulting type.
   // Same ranks between signed and unsigned types are resolved earlier, so both
   // types are either signed or both unsigned at this point.
   unsigned LHSTyRank = GetFixedPointRank(LHSTy);
   unsigned RHSTyRank = GetFixedPointRank(RHSTy);
 
   QualType ResultTy = LHSTyRank > RHSTyRank ? LHSTy : RHSTy;
 
   if (LHSTy->isSaturatedFixedPointType() || RHSTy->isSaturatedFixedPointType())
     ResultTy = S.Context.getCorrespondingSaturatedType(ResultTy);
 
   return ResultTy;
 }
 
 /// Check that the usual arithmetic conversions can be performed on this pair of
 /// expressions that might be of enumeration type.
 static void checkEnumArithmeticConversions(Sema &S, Expr *LHS, Expr *RHS,
                                            SourceLocation Loc,
                                            Sema::ArithConvKind ACK) {
   // C++2a [expr.arith.conv]p1:
   //   If one operand is of enumeration type and the other operand is of a
   //   different enumeration type or a floating-point type, this behavior is
   //   deprecated ([depr.arith.conv.enum]).
   //
   // Warn on this in all language modes. Produce a deprecation warning in C++20.
   // Eventually we will presumably reject these cases (in C++23 onwards?).
   QualType L = LHS->getType(), R = RHS->getType();
   bool LEnum = L->isUnscopedEnumerationType(),
        REnum = R->isUnscopedEnumerationType();
   bool IsCompAssign = ACK == Sema::ACK_CompAssign;
   if ((!IsCompAssign && LEnum && R->isFloatingType()) ||
       (REnum && L->isFloatingType())) {
     S.Diag(Loc, S.getLangOpts().CPlusPlus20
                     ? diag::warn_arith_conv_enum_float_cxx20
                     : diag::warn_arith_conv_enum_float)
         << LHS->getSourceRange() << RHS->getSourceRange()
         << (int)ACK << LEnum << L << R;
   } else if (!IsCompAssign && LEnum && REnum &&
              !S.Context.hasSameUnqualifiedType(L, R)) {
     unsigned DiagID;
     if (!L->castAs<EnumType>()->getDecl()->hasNameForLinkage() ||
         !R->castAs<EnumType>()->getDecl()->hasNameForLinkage()) {
       // If either enumeration type is unnamed, it's less likely that the
       // user cares about this, but this situation is still deprecated in
       // C++2a. Use a different warning group.
       DiagID = S.getLangOpts().CPlusPlus20
                     ? diag::warn_arith_conv_mixed_anon_enum_types_cxx20
                     : diag::warn_arith_conv_mixed_anon_enum_types;
     } else if (ACK == Sema::ACK_Conditional) {
       // Conditional expressions are separated out because they have
       // historically had a different warning flag.
       DiagID = S.getLangOpts().CPlusPlus20
                    ? diag::warn_conditional_mixed_enum_types_cxx20
                    : diag::warn_conditional_mixed_enum_types;
     } else if (ACK == Sema::ACK_Comparison) {
       // Comparison expressions are separated out because they have
       // historically had a different warning flag.
       DiagID = S.getLangOpts().CPlusPlus20
                    ? diag::warn_comparison_mixed_enum_types_cxx20
                    : diag::warn_comparison_mixed_enum_types;
     } else {
       DiagID = S.getLangOpts().CPlusPlus20
                    ? diag::warn_arith_conv_mixed_enum_types_cxx20
                    : diag::warn_arith_conv_mixed_enum_types;
     }
     S.Diag(Loc, DiagID) << LHS->getSourceRange() << RHS->getSourceRange()
                         << (int)ACK << L << R;
   }
 }
 
 /// UsualArithmeticConversions - Performs various conversions that are common to
 /// binary operators (C99 6.3.1.8). If both operands aren't arithmetic, this
 /// routine returns the first non-arithmetic type found. The client is
 /// responsible for emitting appropriate error diagnostics.
 QualType Sema::UsualArithmeticConversions(ExprResult &LHS, ExprResult &RHS,
                                           SourceLocation Loc,
                                           ArithConvKind ACK) {
   checkEnumArithmeticConversions(*this, LHS.get(), RHS.get(), Loc, ACK);
 
   if (ACK != ACK_CompAssign) {
     LHS = UsualUnaryConversions(LHS.get());
     if (LHS.isInvalid())
       return QualType();
   }
 
   RHS = UsualUnaryConversions(RHS.get());
   if (RHS.isInvalid())
     return QualType();
 
   // For conversion purposes, we ignore any qualifiers.
   // For example, "const float" and "float" are equivalent.
   QualType LHSType = LHS.get()->getType().getUnqualifiedType();
   QualType RHSType = RHS.get()->getType().getUnqualifiedType();
 
   // For conversion purposes, we ignore any atomic qualifier on the LHS.
   if (const AtomicType *AtomicLHS = LHSType->getAs<AtomicType>())
     LHSType = AtomicLHS->getValueType();
 
   // If both types are identical, no conversion is needed.
   if (Context.hasSameType(LHSType, RHSType))
     return Context.getCommonSugaredType(LHSType, RHSType);
 
   // If either side is a non-arithmetic type (e.g. a pointer), we are done.
   // The caller can deal with this (e.g. pointer + int).
   if (!LHSType->isArithmeticType() || !RHSType->isArithmeticType())
     return QualType();
 
   // Apply unary and bitfield promotions to the LHS's type.
   QualType LHSUnpromotedType = LHSType;
   if (Context.isPromotableIntegerType(LHSType))
     LHSType = Context.getPromotedIntegerType(LHSType);
   QualType LHSBitfieldPromoteTy = Context.isPromotableBitField(LHS.get());
   if (!LHSBitfieldPromoteTy.isNull())
     LHSType = LHSBitfieldPromoteTy;
   if (LHSType != LHSUnpromotedType && ACK != ACK_CompAssign)
     LHS = ImpCastExprToType(LHS.get(), LHSType, CK_IntegralCast);
 
   // If both types are identical, no conversion is needed.
   if (Context.hasSameType(LHSType, RHSType))
     return Context.getCommonSugaredType(LHSType, RHSType);
 
   // At this point, we have two different arithmetic types.
 
   // Diagnose attempts to convert between __ibm128, __float128 and long double
   // where such conversions currently can't be handled.
   if (unsupportedTypeConversion(*this, LHSType, RHSType))
     return QualType();
 
   // Handle complex types first (C99 6.3.1.8p1).
   if (LHSType->isComplexType() || RHSType->isComplexType())
     return handleComplexConversion(*this, LHS, RHS, LHSType, RHSType,
                                    ACK == ACK_CompAssign);
 
   // Now handle "real" floating types (i.e. float, double, long double).
   if (LHSType->isRealFloatingType() || RHSType->isRealFloatingType())
     return handleFloatConversion(*this, LHS, RHS, LHSType, RHSType,
                                  ACK == ACK_CompAssign);
 
   // Handle GCC complex int extension.
   if (LHSType->isComplexIntegerType() || RHSType->isComplexIntegerType())
     return handleComplexIntConversion(*this, LHS, RHS, LHSType, RHSType,
                                       ACK == ACK_CompAssign);
 
   if (LHSType->isFixedPointType() || RHSType->isFixedPointType())
     return handleFixedPointConversion(*this, LHSType, RHSType);
 
   // Finally, we have two differing integer types.
   return handleIntegerConversion<doIntegralCast, doIntegralCast>
            (*this, LHS, RHS, LHSType, RHSType, ACK == ACK_CompAssign);
 }
 
 //===----------------------------------------------------------------------===//
 //  Semantic Analysis for various Expression Types
 //===----------------------------------------------------------------------===//
 
 
 ExprResult Sema::ActOnGenericSelectionExpr(
     SourceLocation KeyLoc, SourceLocation DefaultLoc, SourceLocation RParenLoc,
     bool PredicateIsExpr, void *ControllingExprOrType,
     ArrayRef<ParsedType> ArgTypes, ArrayRef<Expr *> ArgExprs) {
   unsigned NumAssocs = ArgTypes.size();
   assert(NumAssocs == ArgExprs.size());
 
   TypeSourceInfo **Types = new TypeSourceInfo*[NumAssocs];
   for (unsigned i = 0; i < NumAssocs; ++i) {
     if (ArgTypes[i])
       (void) GetTypeFromParser(ArgTypes[i], &Types[i]);
     else
       Types[i] = nullptr;
   }
 
   // If we have a controlling type, we need to convert it from a parsed type
   // into a semantic type and then pass that along.
   if (!PredicateIsExpr) {
     TypeSourceInfo *ControllingType;
     (void)GetTypeFromParser(ParsedType::getFromOpaquePtr(ControllingExprOrType),
                             &ControllingType);
     assert(ControllingType && "couldn't get the type out of the parser");
     ControllingExprOrType = ControllingType;
   }
 
   ExprResult ER = CreateGenericSelectionExpr(
       KeyLoc, DefaultLoc, RParenLoc, PredicateIsExpr, ControllingExprOrType,
       llvm::ArrayRef(Types, NumAssocs), ArgExprs);
   delete [] Types;
   return ER;
 }
 
 ExprResult Sema::CreateGenericSelectionExpr(
     SourceLocation KeyLoc, SourceLocation DefaultLoc, SourceLocation RParenLoc,
     bool PredicateIsExpr, void *ControllingExprOrType,
     ArrayRef<TypeSourceInfo *> Types, ArrayRef<Expr *> Exprs) {
   unsigned NumAssocs = Types.size();
   assert(NumAssocs == Exprs.size());
   assert(ControllingExprOrType &&
          "Must have either a controlling expression or a controlling type");
 
   Expr *ControllingExpr = nullptr;
   TypeSourceInfo *ControllingType = nullptr;
   if (PredicateIsExpr) {
     // Decay and strip qualifiers for the controlling expression type, and
     // handle placeholder type replacement. See committee discussion from WG14
     // DR423.
     EnterExpressionEvaluationContext Unevaluated(
         *this, Sema::ExpressionEvaluationContext::Unevaluated);
     ExprResult R = DefaultFunctionArrayLvalueConversion(
         reinterpret_cast<Expr *>(ControllingExprOrType));
     if (R.isInvalid())
       return ExprError();
     ControllingExpr = R.get();
   } else {
     // The extension form uses the type directly rather than converting it.
     ControllingType = reinterpret_cast<TypeSourceInfo *>(ControllingExprOrType);
     if (!ControllingType)
       return ExprError();
   }
 
   bool TypeErrorFound = false,
        IsResultDependent = ControllingExpr
                                ? ControllingExpr->isTypeDependent()
                                : ControllingType->getType()->isDependentType(),
        ContainsUnexpandedParameterPack =
            ControllingExpr
                ? ControllingExpr->containsUnexpandedParameterPack()
                : ControllingType->getType()->containsUnexpandedParameterPack();
 
   // The controlling expression is an unevaluated operand, so side effects are
   // likely unintended.
   if (!inTemplateInstantiation() && !IsResultDependent && ControllingExpr &&
       ControllingExpr->HasSideEffects(Context, false))
     Diag(ControllingExpr->getExprLoc(),
          diag::warn_side_effects_unevaluated_context);
 
   for (unsigned i = 0; i < NumAssocs; ++i) {
     if (Exprs[i]->containsUnexpandedParameterPack())
       ContainsUnexpandedParameterPack = true;
 
     if (Types[i]) {
       if (Types[i]->getType()->containsUnexpandedParameterPack())
         ContainsUnexpandedParameterPack = true;
 
       if (Types[i]->getType()->isDependentType()) {
         IsResultDependent = true;
       } else {
         // We relax the restriction on use of incomplete types and non-object
         // types with the type-based extension of _Generic. Allowing incomplete
         // objects means those can be used as "tags" for a type-safe way to map
         // to a value. Similarly, matching on function types rather than
         // function pointer types can be useful. However, the restriction on VM
         // types makes sense to retain as there are open questions about how
         // the selection can be made at compile time.
         //
         // C11 6.5.1.1p2 "The type name in a generic association shall specify a
         // complete object type other than a variably modified type."
         unsigned D = 0;
         if (ControllingExpr && Types[i]->getType()->isIncompleteType())
           D = diag::err_assoc_type_incomplete;
         else if (ControllingExpr && !Types[i]->getType()->isObjectType())
           D = diag::err_assoc_type_nonobject;
         else if (Types[i]->getType()->isVariablyModifiedType())
           D = diag::err_assoc_type_variably_modified;
         else if (ControllingExpr) {
           // Because the controlling expression undergoes lvalue conversion,
           // array conversion, and function conversion, an association which is
           // of array type, function type, or is qualified can never be
           // reached. We will warn about this so users are less surprised by
           // the unreachable association. However, we don't have to handle
           // function types; that's not an object type, so it's handled above.
           //
           // The logic is somewhat different for C++ because C++ has different
           // lvalue to rvalue conversion rules than C. [conv.lvalue]p1 says,
           // If T is a non-class type, the type of the prvalue is the cv-
           // unqualified version of T. Otherwise, the type of the prvalue is T.
           // The result of these rules is that all qualified types in an
           // association in C are unreachable, and in C++, only qualified non-
           // class types are unreachable.
           //
           // NB: this does not apply when the first operand is a type rather
           // than an expression, because the type form does not undergo
           // conversion.
           unsigned Reason = 0;
           QualType QT = Types[i]->getType();
           if (QT->isArrayType())
             Reason = 1;
           else if (QT.hasQualifiers() &&
                    (!LangOpts.CPlusPlus || !QT->isRecordType()))
             Reason = 2;
 
           if (Reason)
             Diag(Types[i]->getTypeLoc().getBeginLoc(),
                  diag::warn_unreachable_association)
                 << QT << (Reason - 1);
         }
 
         if (D != 0) {
           Diag(Types[i]->getTypeLoc().getBeginLoc(), D)
             << Types[i]->getTypeLoc().getSourceRange()
             << Types[i]->getType();
           TypeErrorFound = true;
         }
 
         // C11 6.5.1.1p2 "No two generic associations in the same generic
         // selection shall specify compatible types."
         for (unsigned j = i+1; j < NumAssocs; ++j)
           if (Types[j] && !Types[j]->getType()->isDependentType() &&
               Context.typesAreCompatible(Types[i]->getType(),
                                          Types[j]->getType())) {
             Diag(Types[j]->getTypeLoc().getBeginLoc(),
                  diag::err_assoc_compatible_types)
               << Types[j]->getTypeLoc().getSourceRange()
               << Types[j]->getType()
               << Types[i]->getType();
             Diag(Types[i]->getTypeLoc().getBeginLoc(),
                  diag::note_compat_assoc)
               << Types[i]->getTypeLoc().getSourceRange()
               << Types[i]->getType();
             TypeErrorFound = true;
           }
       }
     }
   }
   if (TypeErrorFound)
     return ExprError();
 
   // If we determined that the generic selection is result-dependent, don't
   // try to compute the result expression.
   if (IsResultDependent) {
     if (ControllingExpr)
       return GenericSelectionExpr::Create(Context, KeyLoc, ControllingExpr,
                                           Types, Exprs, DefaultLoc, RParenLoc,
                                           ContainsUnexpandedParameterPack);
     return GenericSelectionExpr::Create(Context, KeyLoc, ControllingType, Types,
                                         Exprs, DefaultLoc, RParenLoc,
                                         ContainsUnexpandedParameterPack);
   }
 
   SmallVector<unsigned, 1> CompatIndices;
   unsigned DefaultIndex = -1U;
   // Look at the canonical type of the controlling expression in case it was a
   // deduced type like __auto_type. However, when issuing diagnostics, use the
   // type the user wrote in source rather than the canonical one.
   for (unsigned i = 0; i < NumAssocs; ++i) {
     if (!Types[i])
       DefaultIndex = i;
     else if (ControllingExpr &&
              Context.typesAreCompatible(
                  ControllingExpr->getType().getCanonicalType(),
                  Types[i]->getType()))
       CompatIndices.push_back(i);
     else if (ControllingType &&
              Context.typesAreCompatible(
                  ControllingType->getType().getCanonicalType(),
                  Types[i]->getType()))
       CompatIndices.push_back(i);
   }
 
   auto GetControllingRangeAndType = [](Expr *ControllingExpr,
                                        TypeSourceInfo *ControllingType) {
     // We strip parens here because the controlling expression is typically
     // parenthesized in macro definitions.
     if (ControllingExpr)
       ControllingExpr = ControllingExpr->IgnoreParens();
 
     SourceRange SR = ControllingExpr
                          ? ControllingExpr->getSourceRange()
                          : ControllingType->getTypeLoc().getSourceRange();
     QualType QT = ControllingExpr ? ControllingExpr->getType()
                                   : ControllingType->getType();
 
     return std::make_pair(SR, QT);
   };
 
   // C11 6.5.1.1p2 "The controlling expression of a generic selection shall have
   // type compatible with at most one of the types named in its generic
   // association list."
   if (CompatIndices.size() > 1) {
     auto P = GetControllingRangeAndType(ControllingExpr, ControllingType);
     SourceRange SR = P.first;
     Diag(SR.getBegin(), diag::err_generic_sel_multi_match)
         << SR << P.second << (unsigned)CompatIndices.size();
     for (unsigned I : CompatIndices) {
       Diag(Types[I]->getTypeLoc().getBeginLoc(),
            diag::note_compat_assoc)
         << Types[I]->getTypeLoc().getSourceRange()
         << Types[I]->getType();
     }
     return ExprError();
   }
 
   // C11 6.5.1.1p2 "If a generic selection has no default generic association,
   // its controlling expression shall have type compatible with exactly one of
   // the types named in its generic association list."
   if (DefaultIndex == -1U && CompatIndices.size() == 0) {
     auto P = GetControllingRangeAndType(ControllingExpr, ControllingType);
     SourceRange SR = P.first;
     Diag(SR.getBegin(), diag::err_generic_sel_no_match) << SR << P.second;
     return ExprError();
   }
 
   // C11 6.5.1.1p3 "If a generic selection has a generic association with a
   // type name that is compatible with the type of the controlling expression,
   // then the result expression of the generic selection is the expression
   // in that generic association. Otherwise, the result expression of the
   // generic selection is the expression in the default generic association."
   unsigned ResultIndex =
     CompatIndices.size() ? CompatIndices[0] : DefaultIndex;
 
   if (ControllingExpr) {
     return GenericSelectionExpr::Create(
         Context, KeyLoc, ControllingExpr, Types, Exprs, DefaultLoc, RParenLoc,
         ContainsUnexpandedParameterPack, ResultIndex);
   }
   return GenericSelectionExpr::Create(
       Context, KeyLoc, ControllingType, Types, Exprs, DefaultLoc, RParenLoc,
       ContainsUnexpandedParameterPack, ResultIndex);
 }
 
 /// getUDSuffixLoc - Create a SourceLocation for a ud-suffix, given the
 /// location of the token and the offset of the ud-suffix within it.
 static SourceLocation getUDSuffixLoc(Sema &S, SourceLocation TokLoc,
                                      unsigned Offset) {
   return Lexer::AdvanceToTokenCharacter(TokLoc, Offset, S.getSourceManager(),
                                         S.getLangOpts());
 }
 
 /// BuildCookedLiteralOperatorCall - A user-defined literal was found. Look up
 /// the corresponding cooked (non-raw) literal operator, and build a call to it.
 static ExprResult BuildCookedLiteralOperatorCall(Sema &S, Scope *Scope,
                                                  IdentifierInfo *UDSuffix,
                                                  SourceLocation UDSuffixLoc,
                                                  ArrayRef<Expr*> Args,
                                                  SourceLocation LitEndLoc) {
   assert(Args.size() <= 2 && "too many arguments for literal operator");
 
   QualType ArgTy[2];
   for (unsigned ArgIdx = 0; ArgIdx != Args.size(); ++ArgIdx) {
     ArgTy[ArgIdx] = Args[ArgIdx]->getType();
     if (ArgTy[ArgIdx]->isArrayType())
       ArgTy[ArgIdx] = S.Context.getArrayDecayedType(ArgTy[ArgIdx]);
   }
 
   DeclarationName OpName =
     S.Context.DeclarationNames.getCXXLiteralOperatorName(UDSuffix);
   DeclarationNameInfo OpNameInfo(OpName, UDSuffixLoc);
   OpNameInfo.setCXXLiteralOperatorNameLoc(UDSuffixLoc);
 
   LookupResult R(S, OpName, UDSuffixLoc, Sema::LookupOrdinaryName);
   if (S.LookupLiteralOperator(Scope, R, llvm::ArrayRef(ArgTy, Args.size()),
                               /*AllowRaw*/ false, /*AllowTemplate*/ false,
                               /*AllowStringTemplatePack*/ false,
                               /*DiagnoseMissing*/ true) == Sema::LOLR_Error)
     return ExprError();
 
   return S.BuildLiteralOperatorCall(R, OpNameInfo, Args, LitEndLoc);
 }
 
 ExprResult Sema::ActOnUnevaluatedStringLiteral(ArrayRef<Token> StringToks) {
   StringLiteralParser Literal(StringToks, PP,
                               StringLiteralEvalMethod::Unevaluated);
   if (Literal.hadError)
     return ExprError();
 
   SmallVector<SourceLocation, 4> StringTokLocs;
   for (const Token &Tok : StringToks)
     StringTokLocs.push_back(Tok.getLocation());
 
   StringLiteral *Lit = StringLiteral::Create(
       Context, Literal.GetString(), StringLiteral::Unevaluated, false, {},
       &StringTokLocs[0], StringTokLocs.size());
 
   if (!Literal.getUDSuffix().empty()) {
     SourceLocation UDSuffixLoc =
         getUDSuffixLoc(*this, StringTokLocs[Literal.getUDSuffixToken()],
                        Literal.getUDSuffixOffset());
     return ExprError(Diag(UDSuffixLoc, diag::err_invalid_string_udl));
   }
 
   return Lit;
 }
 
 /// ActOnStringLiteral - The specified tokens were lexed as pasted string
 /// fragments (e.g. "foo" "bar" L"baz").  The result string has to handle string
 /// concatenation ([C99 5.1.1.2, translation phase #6]), so it may come from
 /// multiple tokens.  However, the common case is that StringToks points to one
 /// string.
 ///
 ExprResult
 Sema::ActOnStringLiteral(ArrayRef<Token> StringToks, Scope *UDLScope) {
   assert(!StringToks.empty() && "Must have at least one string!");
 
   StringLiteralParser Literal(StringToks, PP);
   if (Literal.hadError)
     return ExprError();
 
   SmallVector<SourceLocation, 4> StringTokLocs;
   for (const Token &Tok : StringToks)
     StringTokLocs.push_back(Tok.getLocation());
 
   QualType CharTy = Context.CharTy;
   StringLiteral::StringKind Kind = StringLiteral::Ordinary;
   if (Literal.isWide()) {
     CharTy = Context.getWideCharType();
     Kind = StringLiteral::Wide;
   } else if (Literal.isUTF8()) {
     if (getLangOpts().Char8)
       CharTy = Context.Char8Ty;
     Kind = StringLiteral::UTF8;
   } else if (Literal.isUTF16()) {
     CharTy = Context.Char16Ty;
     Kind = StringLiteral::UTF16;
   } else if (Literal.isUTF32()) {
     CharTy = Context.Char32Ty;
     Kind = StringLiteral::UTF32;
   } else if (Literal.isPascal()) {
     CharTy = Context.UnsignedCharTy;
   }
 
   // Warn on initializing an array of char from a u8 string literal; this
   // becomes ill-formed in C++2a.
   if (getLangOpts().CPlusPlus && !getLangOpts().CPlusPlus20 &&
       !getLangOpts().Char8 && Kind == StringLiteral::UTF8) {
     Diag(StringTokLocs.front(), diag::warn_cxx20_compat_utf8_string);
 
     // Create removals for all 'u8' prefixes in the string literal(s). This
     // ensures C++2a compatibility (but may change the program behavior when
     // built by non-Clang compilers for which the execution character set is
     // not always UTF-8).
     auto RemovalDiag = PDiag(diag::note_cxx20_compat_utf8_string_remove_u8);
     SourceLocation RemovalDiagLoc;
     for (const Token &Tok : StringToks) {
       if (Tok.getKind() == tok::utf8_string_literal) {
         if (RemovalDiagLoc.isInvalid())
           RemovalDiagLoc = Tok.getLocation();
         RemovalDiag << FixItHint::CreateRemoval(CharSourceRange::getCharRange(
             Tok.getLocation(),
             Lexer::AdvanceToTokenCharacter(Tok.getLocation(), 2,
                                            getSourceManager(), getLangOpts())));
       }
     }
     Diag(RemovalDiagLoc, RemovalDiag);
   }
 
   QualType StrTy =
       Context.getStringLiteralArrayType(CharTy, Literal.GetNumStringChars());
 
   // Pass &StringTokLocs[0], StringTokLocs.size() to factory!
   StringLiteral *Lit = StringLiteral::Create(Context, Literal.GetString(),
                                              Kind, Literal.Pascal, StrTy,
                                              &StringTokLocs[0],
                                              StringTokLocs.size());
   if (Literal.getUDSuffix().empty())
     return Lit;
 
   // We're building a user-defined literal.
   IdentifierInfo *UDSuffix = &Context.Idents.get(Literal.getUDSuffix());
   SourceLocation UDSuffixLoc =
     getUDSuffixLoc(*this, StringTokLocs[Literal.getUDSuffixToken()],
                    Literal.getUDSuffixOffset());
 
   // Make sure we're allowed user-defined literals here.
   if (!UDLScope)
     return ExprError(Diag(UDSuffixLoc, diag::err_invalid_string_udl));
 
   // C++11 [lex.ext]p5: The literal L is treated as a call of the form
   //   operator "" X (str, len)
   QualType SizeType = Context.getSizeType();
 
   DeclarationName OpName =
     Context.DeclarationNames.getCXXLiteralOperatorName(UDSuffix);
   DeclarationNameInfo OpNameInfo(OpName, UDSuffixLoc);
   OpNameInfo.setCXXLiteralOperatorNameLoc(UDSuffixLoc);
 
   QualType ArgTy[] = {
     Context.getArrayDecayedType(StrTy), SizeType
   };
 
   LookupResult R(*this, OpName, UDSuffixLoc, LookupOrdinaryName);
   switch (LookupLiteralOperator(UDLScope, R, ArgTy,
                                 /*AllowRaw*/ false, /*AllowTemplate*/ true,
                                 /*AllowStringTemplatePack*/ true,
                                 /*DiagnoseMissing*/ true, Lit)) {
 
   case LOLR_Cooked: {
     llvm::APInt Len(Context.getIntWidth(SizeType), Literal.GetNumStringChars());
     IntegerLiteral *LenArg = IntegerLiteral::Create(Context, Len, SizeType,
                                                     StringTokLocs[0]);
     Expr *Args[] = { Lit, LenArg };
 
     return BuildLiteralOperatorCall(R, OpNameInfo, Args, StringTokLocs.back());
   }
 
   case LOLR_Template: {
     TemplateArgumentListInfo ExplicitArgs;
     TemplateArgument Arg(Lit);
     TemplateArgumentLocInfo ArgInfo(Lit);
     ExplicitArgs.addArgument(TemplateArgumentLoc(Arg, ArgInfo));
     return BuildLiteralOperatorCall(R, OpNameInfo, std::nullopt,
                                     StringTokLocs.back(), &ExplicitArgs);
   }
 
   case LOLR_StringTemplatePack: {
     TemplateArgumentListInfo ExplicitArgs;
 
     unsigned CharBits = Context.getIntWidth(CharTy);
     bool CharIsUnsigned = CharTy->isUnsignedIntegerType();
     llvm::APSInt Value(CharBits, CharIsUnsigned);
 
     TemplateArgument TypeArg(CharTy);
     TemplateArgumentLocInfo TypeArgInfo(Context.getTrivialTypeSourceInfo(CharTy));
     ExplicitArgs.addArgument(TemplateArgumentLoc(TypeArg, TypeArgInfo));
 
     for (unsigned I = 0, N = Lit->getLength(); I != N; ++I) {
       Value = Lit->getCodeUnit(I);
       TemplateArgument Arg(Context, Value, CharTy);
       TemplateArgumentLocInfo ArgInfo;
       ExplicitArgs.addArgument(TemplateArgumentLoc(Arg, ArgInfo));
     }
     return BuildLiteralOperatorCall(R, OpNameInfo, std::nullopt,
                                     StringTokLocs.back(), &ExplicitArgs);
   }
   case LOLR_Raw:
   case LOLR_ErrorNoDiagnostic:
     llvm_unreachable("unexpected literal operator lookup result");
   case LOLR_Error:
     return ExprError();
   }
   llvm_unreachable("unexpected literal operator lookup result");
 }
 
 DeclRefExpr *
 Sema::BuildDeclRefExpr(ValueDecl *D, QualType Ty, ExprValueKind VK,
                        SourceLocation Loc,
                        const CXXScopeSpec *SS) {
   DeclarationNameInfo NameInfo(D->getDeclName(), Loc);
   return BuildDeclRefExpr(D, Ty, VK, NameInfo, SS);
 }
 
 DeclRefExpr *
 Sema::BuildDeclRefExpr(ValueDecl *D, QualType Ty, ExprValueKind VK,
                        const DeclarationNameInfo &NameInfo,
                        const CXXScopeSpec *SS, NamedDecl *FoundD,
                        SourceLocation TemplateKWLoc,
                        const TemplateArgumentListInfo *TemplateArgs) {
   NestedNameSpecifierLoc NNS =
       SS ? SS->getWithLocInContext(Context) : NestedNameSpecifierLoc();
   return BuildDeclRefExpr(D, Ty, VK, NameInfo, NNS, FoundD, TemplateKWLoc,
                           TemplateArgs);
 }
 
 // CUDA/HIP: Check whether a captured reference variable is referencing a
 // host variable in a device or host device lambda.
 static bool isCapturingReferenceToHostVarInCUDADeviceLambda(const Sema &S,
                                                             VarDecl *VD) {
   if (!S.getLangOpts().CUDA || !VD->hasInit())
     return false;
   assert(VD->getType()->isReferenceType());
 
   // Check whether the reference variable is referencing a host variable.
   auto *DRE = dyn_cast<DeclRefExpr>(VD->getInit());
   if (!DRE)
     return false;
   auto *Referee = dyn_cast<VarDecl>(DRE->getDecl());
   if (!Referee || !Referee->hasGlobalStorage() ||
       Referee->hasAttr<CUDADeviceAttr>())
     return false;
 
   // Check whether the current function is a device or host device lambda.
   // Check whether the reference variable is a capture by getDeclContext()
   // since refersToEnclosingVariableOrCapture() is not ready at this point.
   auto *MD = dyn_cast_or_null<CXXMethodDecl>(S.CurContext);
   if (MD && MD->getParent()->isLambda() &&
       MD->getOverloadedOperator() == OO_Call && MD->hasAttr<CUDADeviceAttr>() &&
       VD->getDeclContext() != MD)
     return true;
 
   return false;
 }
 
 NonOdrUseReason Sema::getNonOdrUseReasonInCurrentContext(ValueDecl *D) {
   // A declaration named in an unevaluated operand never constitutes an odr-use.
   if (isUnevaluatedContext())
     return NOUR_Unevaluated;
 
   // C++2a [basic.def.odr]p4:
   //   A variable x whose name appears as a potentially-evaluated expression e
   //   is odr-used by e unless [...] x is a reference that is usable in
   //   constant expressions.
   // CUDA/HIP:
   //   If a reference variable referencing a host variable is captured in a
   //   device or host device lambda, the value of the referee must be copied
   //   to the capture and the reference variable must be treated as odr-use
   //   since the value of the referee is not known at compile time and must
   //   be loaded from the captured.
   if (VarDecl *VD = dyn_cast<VarDecl>(D)) {
     if (VD->getType()->isReferenceType() &&
         !(getLangOpts().OpenMP && isOpenMPCapturedDecl(D)) &&
         !isCapturingReferenceToHostVarInCUDADeviceLambda(*this, VD) &&
         VD->isUsableInConstantExpressions(Context))
       return NOUR_Constant;
   }
 
   // All remaining non-variable cases constitute an odr-use. For variables, we
   // need to wait and see how the expression is used.
   return NOUR_None;
 }
 
 /// BuildDeclRefExpr - Build an expression that references a
 /// declaration that does not require a closure capture.
 DeclRefExpr *
 Sema::BuildDeclRefExpr(ValueDecl *D, QualType Ty, ExprValueKind VK,
                        const DeclarationNameInfo &NameInfo,
                        NestedNameSpecifierLoc NNS, NamedDecl *FoundD,
                        SourceLocation TemplateKWLoc,
                        const TemplateArgumentListInfo *TemplateArgs) {
   bool RefersToCapturedVariable = isa<VarDecl, BindingDecl>(D) &&
                                   NeedToCaptureVariable(D, NameInfo.getLoc());
 
   DeclRefExpr *E = DeclRefExpr::Create(
       Context, NNS, TemplateKWLoc, D, RefersToCapturedVariable, NameInfo, Ty,
       VK, FoundD, TemplateArgs, getNonOdrUseReasonInCurrentContext(D));
   MarkDeclRefReferenced(E);
 
   // C++ [except.spec]p17:
   //   An exception-specification is considered to be needed when:
   //   - in an expression, the function is the unique lookup result or
   //     the selected member of a set of overloaded functions.
   //
   // We delay doing this until after we've built the function reference and
   // marked it as used so that:
   //  a) if the function is defaulted, we get errors from defining it before /
   //     instead of errors from computing its exception specification, and
   //  b) if the function is a defaulted comparison, we can use the body we
   //     build when defining it as input to the exception specification
   //     computation rather than computing a new body.
   if (const auto *FPT = Ty->getAs<FunctionProtoType>()) {
     if (isUnresolvedExceptionSpec(FPT->getExceptionSpecType())) {
       if (const auto *NewFPT = ResolveExceptionSpec(NameInfo.getLoc(), FPT))
         E->setType(Context.getQualifiedType(NewFPT, Ty.getQualifiers()));
     }
   }
 
   if (getLangOpts().ObjCWeak && isa<VarDecl>(D) &&
       Ty.getObjCLifetime() == Qualifiers::OCL_Weak && !isUnevaluatedContext() &&
       !Diags.isIgnored(diag::warn_arc_repeated_use_of_weak, E->getBeginLoc()))
     getCurFunction()->recordUseOfWeak(E);
 
   const auto *FD = dyn_cast<FieldDecl>(D);
   if (const auto *IFD = dyn_cast<IndirectFieldDecl>(D))
     FD = IFD->getAnonField();
   if (FD) {
     UnusedPrivateFields.remove(FD);
     // Just in case we're building an illegal pointer-to-member.
     if (FD->isBitField())
       E->setObjectKind(OK_BitField);
   }
 
   // C++ [expr.prim]/8: The expression [...] is a bit-field if the identifier
   // designates a bit-field.
   if (const auto *BD = dyn_cast<BindingDecl>(D))
     if (const auto *BE = BD->getBinding())
       E->setObjectKind(BE->getObjectKind());
 
   return E;
 }
 
 /// Decomposes the given name into a DeclarationNameInfo, its location, and
 /// possibly a list of template arguments.
 ///
 /// If this produces template arguments, it is permitted to call
 /// DecomposeTemplateName.
 ///
 /// This actually loses a lot of source location information for
 /// non-standard name kinds; we should consider preserving that in
 /// some way.
 void
 Sema::DecomposeUnqualifiedId(const UnqualifiedId &Id,
                              TemplateArgumentListInfo &Buffer,
                              DeclarationNameInfo &NameInfo,
                              const TemplateArgumentListInfo *&TemplateArgs) {
   if (Id.getKind() == UnqualifiedIdKind::IK_TemplateId) {
     Buffer.setLAngleLoc(Id.TemplateId->LAngleLoc);
     Buffer.setRAngleLoc(Id.TemplateId->RAngleLoc);
 
     ASTTemplateArgsPtr TemplateArgsPtr(Id.TemplateId->getTemplateArgs(),
                                        Id.TemplateId->NumArgs);
     translateTemplateArguments(TemplateArgsPtr, Buffer);
 
     TemplateName TName = Id.TemplateId->Template.get();
     SourceLocation TNameLoc = Id.TemplateId->TemplateNameLoc;
     NameInfo = Context.getNameForTemplate(TName, TNameLoc);
     TemplateArgs = &Buffer;
   } else {
     NameInfo = GetNameFromUnqualifiedId(Id);
     TemplateArgs = nullptr;
   }
 }
 
 static void emitEmptyLookupTypoDiagnostic(
     const TypoCorrection &TC, Sema &SemaRef, const CXXScopeSpec &SS,
     DeclarationName Typo, SourceLocation TypoLoc, ArrayRef<Expr *> Args,
     unsigned DiagnosticID, unsigned DiagnosticSuggestID) {
   DeclContext *Ctx =
       SS.isEmpty() ? nullptr : SemaRef.computeDeclContext(SS, false);
   if (!TC) {
     // Emit a special diagnostic for failed member lookups.
     // FIXME: computing the declaration context might fail here (?)
     if (Ctx)
       SemaRef.Diag(TypoLoc, diag::err_no_member) << Typo << Ctx
                                                  << SS.getRange();
     else
       SemaRef.Diag(TypoLoc, DiagnosticID) << Typo;
     return;
   }
 
   std::string CorrectedStr = TC.getAsString(SemaRef.getLangOpts());
   bool DroppedSpecifier =
       TC.WillReplaceSpecifier() && Typo.getAsString() == CorrectedStr;
   unsigned NoteID = TC.getCorrectionDeclAs<ImplicitParamDecl>()
                         ? diag::note_implicit_param_decl
                         : diag::note_previous_decl;
   if (!Ctx)
     SemaRef.diagnoseTypo(TC, SemaRef.PDiag(DiagnosticSuggestID) << Typo,
                          SemaRef.PDiag(NoteID));
   else
     SemaRef.diagnoseTypo(TC, SemaRef.PDiag(diag::err_no_member_suggest)
                                  << Typo << Ctx << DroppedSpecifier
                                  << SS.getRange(),
                          SemaRef.PDiag(NoteID));
 }
 
 /// Diagnose a lookup that found results in an enclosing class during error
 /// recovery. This usually indicates that the results were found in a dependent
 /// base class that could not be searched as part of a template definition.
 /// Always issues a diagnostic (though this may be only a warning in MS
 /// compatibility mode).
 ///
 /// Return \c true if the error is unrecoverable, or \c false if the caller
 /// should attempt to recover using these lookup results.
 bool Sema::DiagnoseDependentMemberLookup(const LookupResult &R) {
   // During a default argument instantiation the CurContext points
   // to a CXXMethodDecl; but we can't apply a this-> fixit inside a
   // function parameter list, hence add an explicit check.
   bool isDefaultArgument =
       !CodeSynthesisContexts.empty() &&
       CodeSynthesisContexts.back().Kind ==
           CodeSynthesisContext::DefaultFunctionArgumentInstantiation;
   const auto *CurMethod = dyn_cast<CXXMethodDecl>(CurContext);
   bool isInstance = CurMethod && CurMethod->isInstance() &&
                     R.getNamingClass() == CurMethod->getParent() &&
                     !isDefaultArgument;
 
   // There are two ways we can find a class-scope declaration during template
   // instantiation that we did not find in the template definition: if it is a
   // member of a dependent base class, or if it is declared after the point of
   // use in the same class. Distinguish these by comparing the class in which
   // the member was found to the naming class of the lookup.
   unsigned DiagID = diag::err_found_in_dependent_base;
   unsigned NoteID = diag::note_member_declared_at;
   if (R.getRepresentativeDecl()->getDeclContext()->Equals(R.getNamingClass())) {
     DiagID = getLangOpts().MSVCCompat ? diag::ext_found_later_in_class
                                       : diag::err_found_later_in_class;
   } else if (getLangOpts().MSVCCompat) {
     DiagID = diag::ext_found_in_dependent_base;
     NoteID = diag::note_dependent_member_use;
   }
 
   if (isInstance) {
     // Give a code modification hint to insert 'this->'.
     Diag(R.getNameLoc(), DiagID)
         << R.getLookupName()
         << FixItHint::CreateInsertion(R.getNameLoc(), "this->");
     CheckCXXThisCapture(R.getNameLoc());
   } else {
     // FIXME: Add a FixItHint to insert 'Base::' or 'Derived::' (assuming
     // they're not shadowed).
     Diag(R.getNameLoc(), DiagID) << R.getLookupName();
   }
 
   for (const NamedDecl *D : R)
     Diag(D->getLocation(), NoteID);
 
   // Return true if we are inside a default argument instantiation
   // and the found name refers to an instance member function, otherwise
   // the caller will try to create an implicit member call and this is wrong
   // for default arguments.
   //
   // FIXME: Is this special case necessary? We could allow the caller to
   // diagnose this.
   if (isDefaultArgument && ((*R.begin())->isCXXInstanceMember())) {
     Diag(R.getNameLoc(), diag::err_member_call_without_object);
     return true;
   }
 
   // Tell the callee to try to recover.
   return false;
 }
 
 /// Diagnose an empty lookup.
 ///
 /// \return false if new lookup candidates were found
 bool Sema::DiagnoseEmptyLookup(Scope *S, CXXScopeSpec &SS, LookupResult &R,
                                CorrectionCandidateCallback &CCC,
                                TemplateArgumentListInfo *ExplicitTemplateArgs,
                                ArrayRef<Expr *> Args, TypoExpr **Out) {
   DeclarationName Name = R.getLookupName();
 
   unsigned diagnostic = diag::err_undeclared_var_use;
   unsigned diagnostic_suggest = diag::err_undeclared_var_use_suggest;
   if (Name.getNameKind() == DeclarationName::CXXOperatorName ||
       Name.getNameKind() == DeclarationName::CXXLiteralOperatorName ||
       Name.getNameKind() == DeclarationName::CXXConversionFunctionName) {
     diagnostic = diag::err_undeclared_use;
     diagnostic_suggest = diag::err_undeclared_use_suggest;
   }
 
   // If the original lookup was an unqualified lookup, fake an
   // unqualified lookup.  This is useful when (for example) the
   // original lookup would not have found something because it was a
   // dependent name.
   DeclContext *DC = SS.isEmpty() ? CurContext : nullptr;
   while (DC) {
     if (isa<CXXRecordDecl>(DC)) {
       LookupQualifiedName(R, DC);
 
       if (!R.empty()) {
         // Don't give errors about ambiguities in this lookup.
         R.suppressDiagnostics();
 
         // If there's a best viable function among the results, only mention
         // that one in the notes.
         OverloadCandidateSet Candidates(R.getNameLoc(),
                                         OverloadCandidateSet::CSK_Normal);
         AddOverloadedCallCandidates(R, ExplicitTemplateArgs, Args, Candidates);
         OverloadCandidateSet::iterator Best;
         if (Candidates.BestViableFunction(*this, R.getNameLoc(), Best) ==
             OR_Success) {
           R.clear();
           R.addDecl(Best->FoundDecl.getDecl(), Best->FoundDecl.getAccess());
           R.resolveKind();
         }
 
         return DiagnoseDependentMemberLookup(R);
       }
 
       R.clear();
     }
 
     DC = DC->getLookupParent();
   }
 
   // We didn't find anything, so try to correct for a typo.
   TypoCorrection Corrected;
   if (S && Out) {
     SourceLocation TypoLoc = R.getNameLoc();
     assert(!ExplicitTemplateArgs &&
            "Diagnosing an empty lookup with explicit template args!");
     *Out = CorrectTypoDelayed(
         R.getLookupNameInfo(), R.getLookupKind(), S, &SS, CCC,
         [=](const TypoCorrection &TC) {
           emitEmptyLookupTypoDiagnostic(TC, *this, SS, Name, TypoLoc, Args,
                                         diagnostic, diagnostic_suggest);
         },
         nullptr, CTK_ErrorRecovery);
     if (*Out)
       return true;
   } else if (S &&
              (Corrected = CorrectTypo(R.getLookupNameInfo(), R.getLookupKind(),
                                       S, &SS, CCC, CTK_ErrorRecovery))) {
     std::string CorrectedStr(Corrected.getAsString(getLangOpts()));
     bool DroppedSpecifier =
         Corrected.WillReplaceSpecifier() && Name.getAsString() == CorrectedStr;
     R.setLookupName(Corrected.getCorrection());
 
     bool AcceptableWithRecovery = false;
     bool AcceptableWithoutRecovery = false;
     NamedDecl *ND = Corrected.getFoundDecl();
     if (ND) {
       if (Corrected.isOverloaded()) {
         OverloadCandidateSet OCS(R.getNameLoc(),
                                  OverloadCandidateSet::CSK_Normal);
         OverloadCandidateSet::iterator Best;
         for (NamedDecl *CD : Corrected) {
           if (FunctionTemplateDecl *FTD =
                    dyn_cast<FunctionTemplateDecl>(CD))
             AddTemplateOverloadCandidate(
                 FTD, DeclAccessPair::make(FTD, AS_none), ExplicitTemplateArgs,
                 Args, OCS);
           else if (FunctionDecl *FD = dyn_cast<FunctionDecl>(CD))
             if (!ExplicitTemplateArgs || ExplicitTemplateArgs->size() == 0)
               AddOverloadCandidate(FD, DeclAccessPair::make(FD, AS_none),
                                    Args, OCS);
         }
         switch (OCS.BestViableFunction(*this, R.getNameLoc(), Best)) {
         case OR_Success:
           ND = Best->FoundDecl;
           Corrected.setCorrectionDecl(ND);
           break;
         default:
           // FIXME: Arbitrarily pick the first declaration for the note.
           Corrected.setCorrectionDecl(ND);
           break;
         }
       }
       R.addDecl(ND);
       if (getLangOpts().CPlusPlus && ND->isCXXClassMember()) {
         CXXRecordDecl *Record = nullptr;
         if (Corrected.getCorrectionSpecifier()) {
           const Type *Ty = Corrected.getCorrectionSpecifier()->getAsType();
           Record = Ty->getAsCXXRecordDecl();
         }
         if (!Record)
           Record = cast<CXXRecordDecl>(
               ND->getDeclContext()->getRedeclContext());
         R.setNamingClass(Record);
       }
 
       auto *UnderlyingND = ND->getUnderlyingDecl();
       AcceptableWithRecovery = isa<ValueDecl>(UnderlyingND) ||
                                isa<FunctionTemplateDecl>(UnderlyingND);
       // FIXME: If we ended up with a typo for a type name or
       // Objective-C class name, we're in trouble because the parser
       // is in the wrong place to recover. Suggest the typo
       // correction, but don't make it a fix-it since we're not going
       // to recover well anyway.
       AcceptableWithoutRecovery = isa<TypeDecl>(UnderlyingND) ||
                                   getAsTypeTemplateDecl(UnderlyingND) ||
                                   isa<ObjCInterfaceDecl>(UnderlyingND);
     } else {
       // FIXME: We found a keyword. Suggest it, but don't provide a fix-it
       // because we aren't able to recover.
       AcceptableWithoutRecovery = true;
     }
 
     if (AcceptableWithRecovery || AcceptableWithoutRecovery) {
       unsigned NoteID = Corrected.getCorrectionDeclAs<ImplicitParamDecl>()
                             ? diag::note_implicit_param_decl
                             : diag::note_previous_decl;
       if (SS.isEmpty())
         diagnoseTypo(Corrected, PDiag(diagnostic_suggest) << Name,
                      PDiag(NoteID), AcceptableWithRecovery);
       else
         diagnoseTypo(Corrected, PDiag(diag::err_no_member_suggest)
                                   << Name << computeDeclContext(SS, false)
                                   << DroppedSpecifier << SS.getRange(),
                      PDiag(NoteID), AcceptableWithRecovery);
 
       // Tell the callee whether to try to recover.
       return !AcceptableWithRecovery;
     }
   }
   R.clear();
 
   // Emit a special diagnostic for failed member lookups.
   // FIXME: computing the declaration context might fail here (?)
   if (!SS.isEmpty()) {
     Diag(R.getNameLoc(), diag::err_no_member)
       << Name << computeDeclContext(SS, false)
       << SS.getRange();
     return true;
   }
 
   // Give up, we can't recover.
   Diag(R.getNameLoc(), diagnostic) << Name;
   return true;
 }
 
 /// In Microsoft mode, if we are inside a template class whose parent class has
 /// dependent base classes, and we can't resolve an unqualified identifier, then
 /// assume the identifier is a member of a dependent base class.  We can only
 /// recover successfully in static methods, instance methods, and other contexts
 /// where 'this' is available.  This doesn't precisely match MSVC's
 /// instantiation model, but it's close enough.
 static Expr *
 recoverFromMSUnqualifiedLookup(Sema &S, ASTContext &Context,
                                DeclarationNameInfo &NameInfo,
                                SourceLocation TemplateKWLoc,
                                const TemplateArgumentListInfo *TemplateArgs) {
   // Only try to recover from lookup into dependent bases in static methods or
   // contexts where 'this' is available.
   QualType ThisType = S.getCurrentThisType();
   const CXXRecordDecl *RD = nullptr;
   if (!ThisType.isNull())
     RD = ThisType->getPointeeType()->getAsCXXRecordDecl();
   else if (auto *MD = dyn_cast<CXXMethodDecl>(S.CurContext))
     RD = MD->getParent();
   if (!RD || !RD->hasAnyDependentBases())
     return nullptr;
 
   // Diagnose this as unqualified lookup into a dependent base class.  If 'this'
   // is available, suggest inserting 'this->' as a fixit.
   SourceLocation Loc = NameInfo.getLoc();
   auto DB = S.Diag(Loc, diag::ext_undeclared_unqual_id_with_dependent_base);
   DB << NameInfo.getName() << RD;
 
   if (!ThisType.isNull()) {
     DB << FixItHint::CreateInsertion(Loc, "this->");
     return CXXDependentScopeMemberExpr::Create(
         Context, /*This=*/nullptr, ThisType, /*IsArrow=*/true,
         /*Op=*/SourceLocation(), NestedNameSpecifierLoc(), TemplateKWLoc,
         /*FirstQualifierFoundInScope=*/nullptr, NameInfo, TemplateArgs);
   }
 
   // Synthesize a fake NNS that points to the derived class.  This will
   // perform name lookup during template instantiation.
   CXXScopeSpec SS;
   auto *NNS =
       NestedNameSpecifier::Create(Context, nullptr, true, RD->getTypeForDecl());
   SS.MakeTrivial(Context, NNS, SourceRange(Loc, Loc));
   return DependentScopeDeclRefExpr::Create(
       Context, SS.getWithLocInContext(Context), TemplateKWLoc, NameInfo,
       TemplateArgs);
 }
 
 ExprResult
 Sema::ActOnIdExpression(Scope *S, CXXScopeSpec &SS,
                         SourceLocation TemplateKWLoc, UnqualifiedId &Id,
                         bool HasTrailingLParen, bool IsAddressOfOperand,
                         CorrectionCandidateCallback *CCC,
                         bool IsInlineAsmIdentifier, Token *KeywordReplacement) {
   assert(!(IsAddressOfOperand && HasTrailingLParen) &&
          "cannot be direct & operand and have a trailing lparen");
   if (SS.isInvalid())
     return ExprError();
 
   TemplateArgumentListInfo TemplateArgsBuffer;
 
   // Decompose the UnqualifiedId into the following data.
   DeclarationNameInfo NameInfo;
   const TemplateArgumentListInfo *TemplateArgs;
   DecomposeUnqualifiedId(Id, TemplateArgsBuffer, NameInfo, TemplateArgs);
 
   DeclarationName Name = NameInfo.getName();
   IdentifierInfo *II = Name.getAsIdentifierInfo();
   SourceLocation NameLoc = NameInfo.getLoc();
 
   if (II && II->isEditorPlaceholder()) {
     // FIXME: When typed placeholders are supported we can create a typed
     // placeholder expression node.
     return ExprError();
   }
 
   // C++ [temp.dep.expr]p3:
   //   An id-expression is type-dependent if it contains:
   //     -- an identifier that was declared with a dependent type,
   //        (note: handled after lookup)
   //     -- a template-id that is dependent,
   //        (note: handled in BuildTemplateIdExpr)
   //     -- a conversion-function-id that specifies a dependent type,
   //     -- a nested-name-specifier that contains a class-name that
   //        names a dependent type.
   // Determine whether this is a member of an unknown specialization;
   // we need to handle these differently.
   bool DependentID = false;
   if (Name.getNameKind() == DeclarationName::CXXConversionFunctionName &&
       Name.getCXXNameType()->isDependentType()) {
     DependentID = true;
   } else if (SS.isSet()) {
     if (DeclContext *DC = computeDeclContext(SS, false)) {
       if (RequireCompleteDeclContext(SS, DC))
         return ExprError();
     } else {
       DependentID = true;
     }
   }
 
   if (DependentID)
     return ActOnDependentIdExpression(SS, TemplateKWLoc, NameInfo,
                                       IsAddressOfOperand, TemplateArgs);
 
   // Perform the required lookup.
   LookupResult R(*this, NameInfo,
                  (Id.getKind() == UnqualifiedIdKind::IK_ImplicitSelfParam)
                      ? LookupObjCImplicitSelfParam
                      : LookupOrdinaryName);
   if (TemplateKWLoc.isValid() || TemplateArgs) {
     // Lookup the template name again to correctly establish the context in
     // which it was found. This is really unfortunate as we already did the
     // lookup to determine that it was a template name in the first place. If
     // this becomes a performance hit, we can work harder to preserve those
     // results until we get here but it's likely not worth it.
     bool MemberOfUnknownSpecialization;
     AssumedTemplateKind AssumedTemplate;
     if (LookupTemplateName(R, S, SS, QualType(), /*EnteringContext=*/false,
                            MemberOfUnknownSpecialization, TemplateKWLoc,
                            &AssumedTemplate))
       return ExprError();
 
     if (MemberOfUnknownSpecialization ||
         (R.getResultKind() == LookupResult::NotFoundInCurrentInstantiation))
       return ActOnDependentIdExpression(SS, TemplateKWLoc, NameInfo,
                                         IsAddressOfOperand, TemplateArgs);
   } else {
     bool IvarLookupFollowUp = II && !SS.isSet() && getCurMethodDecl();
     LookupParsedName(R, S, &SS, !IvarLookupFollowUp);
 
     // If the result might be in a dependent base class, this is a dependent
     // id-expression.
     if (R.getResultKind() == LookupResult::NotFoundInCurrentInstantiation)
       return ActOnDependentIdExpression(SS, TemplateKWLoc, NameInfo,
                                         IsAddressOfOperand, TemplateArgs);
 
     // If this reference is in an Objective-C method, then we need to do
     // some special Objective-C lookup, too.
     if (IvarLookupFollowUp) {
       ExprResult E(LookupInObjCMethod(R, S, II, true));
       if (E.isInvalid())
         return ExprError();
 
       if (Expr *Ex = E.getAs<Expr>())
         return Ex;
     }
   }
 
   if (R.isAmbiguous())
     return ExprError();
 
   // This could be an implicitly declared function reference if the language
   // mode allows it as a feature.
   if (R.empty() && HasTrailingLParen && II &&
       getLangOpts().implicitFunctionsAllowed()) {
     NamedDecl *D = ImplicitlyDefineFunction(NameLoc, *II, S);
     if (D) R.addDecl(D);
   }
 
   // Determine whether this name might be a candidate for
   // argument-dependent lookup.
   bool ADL = UseArgumentDependentLookup(SS, R, HasTrailingLParen);
 
   if (R.empty() && !ADL) {
     if (SS.isEmpty() && getLangOpts().MSVCCompat) {
       if (Expr *E = recoverFromMSUnqualifiedLookup(*this, Context, NameInfo,
                                                    TemplateKWLoc, TemplateArgs))
         return E;
     }
 
     // Don't diagnose an empty lookup for inline assembly.
     if (IsInlineAsmIdentifier)
       return ExprError();
 
     // If this name wasn't predeclared and if this is not a function
     // call, diagnose the problem.
     TypoExpr *TE = nullptr;
     DefaultFilterCCC DefaultValidator(II, SS.isValid() ? SS.getScopeRep()
                                                        : nullptr);
     DefaultValidator.IsAddressOfOperand = IsAddressOfOperand;
     assert((!CCC || CCC->IsAddressOfOperand == IsAddressOfOperand) &&
            "Typo correction callback misconfigured");
     if (CCC) {
       // Make sure the callback knows what the typo being diagnosed is.
       CCC->setTypoName(II);
       if (SS.isValid())
         CCC->setTypoNNS(SS.getScopeRep());
     }
     // FIXME: DiagnoseEmptyLookup produces bad diagnostics if we're looking for
     // a template name, but we happen to have always already looked up the name
     // before we get here if it must be a template name.
     if (DiagnoseEmptyLookup(S, SS, R, CCC ? *CCC : DefaultValidator, nullptr,
                             std::nullopt, &TE)) {
       if (TE && KeywordReplacement) {
         auto &State = getTypoExprState(TE);
         auto BestTC = State.Consumer->getNextCorrection();
         if (BestTC.isKeyword()) {
           auto *II = BestTC.getCorrectionAsIdentifierInfo();
           if (State.DiagHandler)
             State.DiagHandler(BestTC);
           KeywordReplacement->startToken();
           KeywordReplacement->setKind(II->getTokenID());
           KeywordReplacement->setIdentifierInfo(II);
           KeywordReplacement->setLocation(BestTC.getCorrectionRange().getBegin());
           // Clean up the state associated with the TypoExpr, since it has
           // now been diagnosed (without a call to CorrectDelayedTyposInExpr).
           clearDelayedTypo(TE);
           // Signal that a correction to a keyword was performed by returning a
           // valid-but-null ExprResult.
           return (Expr*)nullptr;
         }
         State.Consumer->resetCorrectionStream();
       }
       return TE ? TE : ExprError();
     }
 
     assert(!R.empty() &&
            "DiagnoseEmptyLookup returned false but added no results");
 
     // If we found an Objective-C instance variable, let
     // LookupInObjCMethod build the appropriate expression to
     // reference the ivar.
     if (ObjCIvarDecl *Ivar = R.getAsSingle<ObjCIvarDecl>()) {
       R.clear();
       ExprResult E(LookupInObjCMethod(R, S, Ivar->getIdentifier()));
       // In a hopelessly buggy code, Objective-C instance variable
       // lookup fails and no expression will be built to reference it.
       if (!E.isInvalid() && !E.get())
         return ExprError();
       return E;
     }
   }
 
   // This is guaranteed from this point on.
   assert(!R.empty() || ADL);
 
   // Check whether this might be a C++ implicit instance member access.
   // C++ [class.mfct.non-static]p3:
   //   When an id-expression that is not part of a class member access
   //   syntax and not used to form a pointer to member is used in the
   //   body of a non-static member function of class X, if name lookup
   //   resolves the name in the id-expression to a non-static non-type
   //   member of some class C, the id-expression is transformed into a
   //   class member access expression using (*this) as the
   //   postfix-expression to the left of the . operator.
   //
   // But we don't actually need to do this for '&' operands if R
   // resolved to a function or overloaded function set, because the
   // expression is ill-formed if it actually works out to be a
   // non-static member function:
   //
   // C++ [expr.ref]p4:
   //   Otherwise, if E1.E2 refers to a non-static member function. . .
   //   [t]he expression can be used only as the left-hand operand of a
   //   member function call.
   //
   // There are other safeguards against such uses, but it's important
   // to get this right here so that we don't end up making a
   // spuriously dependent expression if we're inside a dependent
   // instance method.
   if (!R.empty() && (*R.begin())->isCXXClassMember()) {
     bool MightBeImplicitMember;
     if (!IsAddressOfOperand)
       MightBeImplicitMember = true;
     else if (!SS.isEmpty())
       MightBeImplicitMember = false;
     else if (R.isOverloadedResult())
       MightBeImplicitMember = false;
     else if (R.isUnresolvableResult())
       MightBeImplicitMember = true;
     else
       MightBeImplicitMember = isa<FieldDecl>(R.getFoundDecl()) ||
                               isa<IndirectFieldDecl>(R.getFoundDecl()) ||
                               isa<MSPropertyDecl>(R.getFoundDecl());
 
     if (MightBeImplicitMember)
       return BuildPossibleImplicitMemberExpr(SS, TemplateKWLoc,
                                              R, TemplateArgs, S);
   }
 
   if (TemplateArgs || TemplateKWLoc.isValid()) {
 
     // In C++1y, if this is a variable template id, then check it
     // in BuildTemplateIdExpr().
     // The single lookup result must be a variable template declaration.
     if (Id.getKind() == UnqualifiedIdKind::IK_TemplateId && Id.TemplateId &&
         Id.TemplateId->Kind == TNK_Var_template) {
       assert(R.getAsSingle<VarTemplateDecl>() &&
              "There should only be one declaration found.");
     }
 
     return BuildTemplateIdExpr(SS, TemplateKWLoc, R, ADL, TemplateArgs);
   }
 
   return BuildDeclarationNameExpr(SS, R, ADL);
 }
 
 /// BuildQualifiedDeclarationNameExpr - Build a C++ qualified
 /// declaration name, generally during template instantiation.
 /// There's a large number of things which don't need to be done along
 /// this path.
 ExprResult Sema::BuildQualifiedDeclarationNameExpr(
     CXXScopeSpec &SS, const DeclarationNameInfo &NameInfo,
     bool IsAddressOfOperand, const Scope *S, TypeSourceInfo **RecoveryTSI) {
   if (NameInfo.getName().isDependentName())
     return BuildDependentDeclRefExpr(SS, /*TemplateKWLoc=*/SourceLocation(),
                                      NameInfo, /*TemplateArgs=*/nullptr);
 
   DeclContext *DC = computeDeclContext(SS, false);
   if (!DC)
     return BuildDependentDeclRefExpr(SS, /*TemplateKWLoc=*/SourceLocation(),
                                      NameInfo, /*TemplateArgs=*/nullptr);
 
   if (RequireCompleteDeclContext(SS, DC))
     return ExprError();
 
   LookupResult R(*this, NameInfo, LookupOrdinaryName);
   LookupQualifiedName(R, DC);
 
   if (R.isAmbiguous())
     return ExprError();
 
   if (R.getResultKind() == LookupResult::NotFoundInCurrentInstantiation)
     return BuildDependentDeclRefExpr(SS, /*TemplateKWLoc=*/SourceLocation(),
                                      NameInfo, /*TemplateArgs=*/nullptr);
 
   if (R.empty()) {
     // Don't diagnose problems with invalid record decl, the secondary no_member
     // diagnostic during template instantiation is likely bogus, e.g. if a class
     // is invalid because it's derived from an invalid base class, then missing
     // members were likely supposed to be inherited.
     if (const auto *CD = dyn_cast<CXXRecordDecl>(DC))
       if (CD->isInvalidDecl())
         return ExprError();
     Diag(NameInfo.getLoc(), diag::err_no_member)
       << NameInfo.getName() << DC << SS.getRange();
     return ExprError();
   }
 
   if (const TypeDecl *TD = R.getAsSingle<TypeDecl>()) {
     // Diagnose a missing typename if this resolved unambiguously to a type in
     // a dependent context.  If we can recover with a type, downgrade this to
     // a warning in Microsoft compatibility mode.
     unsigned DiagID = diag::err_typename_missing;
     if (RecoveryTSI && getLangOpts().MSVCCompat)
       DiagID = diag::ext_typename_missing;
     SourceLocation Loc = SS.getBeginLoc();
     auto D = Diag(Loc, DiagID);
     D << SS.getScopeRep() << NameInfo.getName().getAsString()
       << SourceRange(Loc, NameInfo.getEndLoc());
 
     // Don't recover if the caller isn't expecting us to or if we're in a SFINAE
     // context.
     if (!RecoveryTSI)
       return ExprError();
 
     // Only issue the fixit if we're prepared to recover.
     D << FixItHint::CreateInsertion(Loc, "typename ");
 
     // Recover by pretending this was an elaborated type.
     QualType Ty = Context.getTypeDeclType(TD);
     TypeLocBuilder TLB;
     TLB.pushTypeSpec(Ty).setNameLoc(NameInfo.getLoc());
 
     QualType ET = getElaboratedType(ETK_None, SS, Ty);
     ElaboratedTypeLoc QTL = TLB.push<ElaboratedTypeLoc>(ET);
     QTL.setElaboratedKeywordLoc(SourceLocation());
     QTL.setQualifierLoc(SS.getWithLocInContext(Context));
 
     *RecoveryTSI = TLB.getTypeSourceInfo(Context, ET);
 
     return ExprEmpty();
   }
 
   // Defend against this resolving to an implicit member access. We usually
   // won't get here if this might be a legitimate a class member (we end up in
   // BuildMemberReferenceExpr instead), but this can be valid if we're forming
   // a pointer-to-member or in an unevaluated context in C++11.
   if (!R.empty() && (*R.begin())->isCXXClassMember() && !IsAddressOfOperand)
     return BuildPossibleImplicitMemberExpr(SS,
                                            /*TemplateKWLoc=*/SourceLocation(),
                                            R, /*TemplateArgs=*/nullptr, S);
 
   return BuildDeclarationNameExpr(SS, R, /* ADL */ false);
 }
 
 /// The parser has read a name in, and Sema has detected that we're currently
 /// inside an ObjC method. Perform some additional checks and determine if we
 /// should form a reference to an ivar.
 ///
 /// Ideally, most of this would be done by lookup, but there's
 /// actually quite a lot of extra work involved.
 DeclResult Sema::LookupIvarInObjCMethod(LookupResult &Lookup, Scope *S,
                                         IdentifierInfo *II) {
   SourceLocation Loc = Lookup.getNameLoc();
   ObjCMethodDecl *CurMethod = getCurMethodDecl();
 
   // Check for error condition which is already reported.
   if (!CurMethod)
     return DeclResult(true);
 
   // There are two cases to handle here.  1) scoped lookup could have failed,
   // in which case we should look for an ivar.  2) scoped lookup could have
   // found a decl, but that decl is outside the current instance method (i.e.
   // a global variable).  In these two cases, we do a lookup for an ivar with
   // this name, if the lookup sucedes, we replace it our current decl.
 
   // If we're in a class method, we don't normally want to look for
   // ivars.  But if we don't find anything else, and there's an
   // ivar, that's an error.
   bool IsClassMethod = CurMethod->isClassMethod();
 
   bool LookForIvars;
   if (Lookup.empty())
     LookForIvars = true;
   else if (IsClassMethod)
     LookForIvars = false;
   else
     LookForIvars = (Lookup.isSingleResult() &&
                     Lookup.getFoundDecl()->isDefinedOutsideFunctionOrMethod());
   ObjCInterfaceDecl *IFace = nullptr;
   if (LookForIvars) {
     IFace = CurMethod->getClassInterface();
     ObjCInterfaceDecl *ClassDeclared;
     ObjCIvarDecl *IV = nullptr;
     if (IFace && (IV = IFace->lookupInstanceVariable(II, ClassDeclared))) {
       // Diagnose using an ivar in a class method.
       if (IsClassMethod) {
         Diag(Loc, diag::err_ivar_use_in_class_method) << IV->getDeclName();
         return DeclResult(true);
       }
 
       // Diagnose the use of an ivar outside of the declaring class.
       if (IV->getAccessControl() == ObjCIvarDecl::Private &&
           !declaresSameEntity(ClassDeclared, IFace) &&
           !getLangOpts().DebuggerSupport)
         Diag(Loc, diag::err_private_ivar_access) << IV->getDeclName();
 
       // Success.
       return IV;
     }
   } else if (CurMethod->isInstanceMethod()) {
     // We should warn if a local variable hides an ivar.
     if (ObjCInterfaceDecl *IFace = CurMethod->getClassInterface()) {
       ObjCInterfaceDecl *ClassDeclared;
       if (ObjCIvarDecl *IV = IFace->lookupInstanceVariable(II, ClassDeclared)) {
         if (IV->getAccessControl() != ObjCIvarDecl::Private ||
             declaresSameEntity(IFace, ClassDeclared))
           Diag(Loc, diag::warn_ivar_use_hidden) << IV->getDeclName();
       }
     }
   } else if (Lookup.isSingleResult() &&
              Lookup.getFoundDecl()->isDefinedOutsideFunctionOrMethod()) {
     // If accessing a stand-alone ivar in a class method, this is an error.
     if (const ObjCIvarDecl *IV =
             dyn_cast<ObjCIvarDecl>(Lookup.getFoundDecl())) {
       Diag(Loc, diag::err_ivar_use_in_class_method) << IV->getDeclName();
       return DeclResult(true);
     }
   }
 
   // Didn't encounter an error, didn't find an ivar.
   return DeclResult(false);
 }
 
 ExprResult Sema::BuildIvarRefExpr(Scope *S, SourceLocation Loc,
                                   ObjCIvarDecl *IV) {
   ObjCMethodDecl *CurMethod = getCurMethodDecl();
   assert(CurMethod && CurMethod->isInstanceMethod() &&
          "should not reference ivar from this context");
 
   ObjCInterfaceDecl *IFace = CurMethod->getClassInterface();
   assert(IFace && "should not reference ivar from this context");
 
   // If we're referencing an invalid decl, just return this as a silent
   // error node.  The error diagnostic was already emitted on the decl.
   if (IV->isInvalidDecl())
     return ExprError();
 
   // Check if referencing a field with __attribute__((deprecated)).
   if (DiagnoseUseOfDecl(IV, Loc))
     return ExprError();
 
   // FIXME: This should use a new expr for a direct reference, don't
   // turn this into Self->ivar, just return a BareIVarExpr or something.
   IdentifierInfo &II = Context.Idents.get("self");
   UnqualifiedId SelfName;
   SelfName.setImplicitSelfParam(&II);
   CXXScopeSpec SelfScopeSpec;
   SourceLocation TemplateKWLoc;
   ExprResult SelfExpr =
       ActOnIdExpression(S, SelfScopeSpec, TemplateKWLoc, SelfName,
                         /*HasTrailingLParen=*/false,
                         /*IsAddressOfOperand=*/false);
   if (SelfExpr.isInvalid())
     return ExprError();
 
   SelfExpr = DefaultLvalueConversion(SelfExpr.get());
   if (SelfExpr.isInvalid())
     return ExprError();
 
   MarkAnyDeclReferenced(Loc, IV, true);
 
   ObjCMethodFamily MF = CurMethod->getMethodFamily();
   if (MF != OMF_init && MF != OMF_dealloc && MF != OMF_finalize &&
       !IvarBacksCurrentMethodAccessor(IFace, CurMethod, IV))
     Diag(Loc, diag::warn_direct_ivar_access) << IV->getDeclName();
 
   ObjCIvarRefExpr *Result = new (Context)
       ObjCIvarRefExpr(IV, IV->getUsageType(SelfExpr.get()->getType()), Loc,
                       IV->getLocation(), SelfExpr.get(), true, true);
 
   if (IV->getType().getObjCLifetime() == Qualifiers::OCL_Weak) {
     if (!isUnevaluatedContext() &&
         !Diags.isIgnored(diag::warn_arc_repeated_use_of_weak, Loc))
       getCurFunction()->recordUseOfWeak(Result);
   }
   if (getLangOpts().ObjCAutoRefCount && !isUnevaluatedContext())
     if (const BlockDecl *BD = CurContext->getInnermostBlockDecl())
       ImplicitlyRetainedSelfLocs.push_back({Loc, BD});
 
   return Result;
 }
 
 /// The parser has read a name in, and Sema has detected that we're currently
 /// inside an ObjC method. Perform some additional checks and determine if we
 /// should form a reference to an ivar. If so, build an expression referencing
 /// that ivar.
 ExprResult
 Sema::LookupInObjCMethod(LookupResult &Lookup, Scope *S,
                          IdentifierInfo *II, bool AllowBuiltinCreation) {
   // FIXME: Integrate this lookup step into LookupParsedName.
   DeclResult Ivar = LookupIvarInObjCMethod(Lookup, S, II);
   if (Ivar.isInvalid())
     return ExprError();
   if (Ivar.isUsable())
     return BuildIvarRefExpr(S, Lookup.getNameLoc(),
                             cast<ObjCIvarDecl>(Ivar.get()));
 
   if (Lookup.empty() && II && AllowBuiltinCreation)
     LookupBuiltin(Lookup);
 
   // Sentinel value saying that we didn't do anything special.
   return ExprResult(false);
 }
 
 /// Cast a base object to a member's actual type.
 ///
 /// There are two relevant checks:
 ///
 /// C++ [class.access.base]p7:
 ///
 ///   If a class member access operator [...] is used to access a non-static
 ///   data member or non-static member function, the reference is ill-formed if
 ///   the left operand [...] cannot be implicitly converted to a pointer to the
 ///   naming class of the right operand.
 ///
 /// C++ [expr.ref]p7:
 ///
 ///   If E2 is a non-static data member or a non-static member function, the
 ///   program is ill-formed if the class of which E2 is directly a member is an
 ///   ambiguous base (11.8) of the naming class (11.9.3) of E2.
 ///
 /// Note that the latter check does not consider access; the access of the
 /// "real" base class is checked as appropriate when checking the access of the
 /// member name.
 ExprResult
 Sema::PerformObjectMemberConversion(Expr *From,
                                     NestedNameSpecifier *Qualifier,
                                     NamedDecl *FoundDecl,
                                     NamedDecl *Member) {
   const auto *RD = dyn_cast<CXXRecordDecl>(Member->getDeclContext());
   if (!RD)
     return From;
 
   QualType DestRecordType;
   QualType DestType;
   QualType FromRecordType;
   QualType FromType = From->getType();
   bool PointerConversions = false;
   if (isa<FieldDecl>(Member)) {
     DestRecordType = Context.getCanonicalType(Context.getTypeDeclType(RD));
     auto FromPtrType = FromType->getAs<PointerType>();
     DestRecordType = Context.getAddrSpaceQualType(
         DestRecordType, FromPtrType
                             ? FromType->getPointeeType().getAddressSpace()
                             : FromType.getAddressSpace());
 
     if (FromPtrType) {
       DestType = Context.getPointerType(DestRecordType);
       FromRecordType = FromPtrType->getPointeeType();
       PointerConversions = true;
     } else {
       DestType = DestRecordType;
       FromRecordType = FromType;
     }
   } else if (const auto *Method = dyn_cast<CXXMethodDecl>(Member)) {
     if (Method->isStatic())
       return From;
 
     DestType = Method->getThisType();
     DestRecordType = DestType->getPointeeType();
 
     if (FromType->getAs<PointerType>()) {
       FromRecordType = FromType->getPointeeType();
       PointerConversions = true;
     } else {
       FromRecordType = FromType;
       DestType = DestRecordType;
     }
 
     LangAS FromAS = FromRecordType.getAddressSpace();
     LangAS DestAS = DestRecordType.getAddressSpace();
     if (FromAS != DestAS) {
       QualType FromRecordTypeWithoutAS =
           Context.removeAddrSpaceQualType(FromRecordType);
       QualType FromTypeWithDestAS =
           Context.getAddrSpaceQualType(FromRecordTypeWithoutAS, DestAS);
       if (PointerConversions)
         FromTypeWithDestAS = Context.getPointerType(FromTypeWithDestAS);
       From = ImpCastExprToType(From, FromTypeWithDestAS,
                                CK_AddressSpaceConversion, From->getValueKind())
                  .get();
     }
   } else {
     // No conversion necessary.
     return From;
   }
 
   if (DestType->isDependentType() || FromType->isDependentType())
     return From;
 
   // If the unqualified types are the same, no conversion is necessary.
   if (Context.hasSameUnqualifiedType(FromRecordType, DestRecordType))
     return From;
 
   SourceRange FromRange = From->getSourceRange();
   SourceLocation FromLoc = FromRange.getBegin();
 
   ExprValueKind VK = From->getValueKind();
 
   // C++ [class.member.lookup]p8:
   //   [...] Ambiguities can often be resolved by qualifying a name with its
   //   class name.
   //
   // If the member was a qualified name and the qualified referred to a
   // specific base subobject type, we'll cast to that intermediate type
   // first and then to the object in which the member is declared. That allows
   // one to resolve ambiguities in, e.g., a diamond-shaped hierarchy such as:
   //
   //   class Base { public: int x; };
   //   class Derived1 : public Base { };
   //   class Derived2 : public Base { };
   //   class VeryDerived : public Derived1, public Derived2 { void f(); };
   //
   //   void VeryDerived::f() {
   //     x = 17; // error: ambiguous base subobjects
   //     Derived1::x = 17; // okay, pick the Base subobject of Derived1
   //   }
   if (Qualifier && Qualifier->getAsType()) {
     QualType QType = QualType(Qualifier->getAsType(), 0);
     assert(QType->isRecordType() && "lookup done with non-record type");
 
     QualType QRecordType = QualType(QType->castAs<RecordType>(), 0);
 
     // In C++98, the qualifier type doesn't actually have to be a base
     // type of the object type, in which case we just ignore it.
     // Otherwise build the appropriate casts.
     if (IsDerivedFrom(FromLoc, FromRecordType, QRecordType)) {
       CXXCastPath BasePath;
       if (CheckDerivedToBaseConversion(FromRecordType, QRecordType,
                                        FromLoc, FromRange, &BasePath))
         return ExprError();
 
       if (PointerConversions)
         QType = Context.getPointerType(QType);
       From = ImpCastExprToType(From, QType, CK_UncheckedDerivedToBase,
                                VK, &BasePath).get();
 
       FromType = QType;
       FromRecordType = QRecordType;
 
       // If the qualifier type was the same as the destination type,
       // we're done.
       if (Context.hasSameUnqualifiedType(FromRecordType, DestRecordType))
         return From;
     }
   }
 
   CXXCastPath BasePath;
   if (CheckDerivedToBaseConversion(FromRecordType, DestRecordType,
                                    FromLoc, FromRange, &BasePath,
                                    /*IgnoreAccess=*/true))
     return ExprError();
 
   return ImpCastExprToType(From, DestType, CK_UncheckedDerivedToBase,
                            VK, &BasePath);
 }
 
 bool Sema::UseArgumentDependentLookup(const CXXScopeSpec &SS,
                                       const LookupResult &R,
                                       bool HasTrailingLParen) {
   // Only when used directly as the postfix-expression of a call.
   if (!HasTrailingLParen)
     return false;
 
   // Never if a scope specifier was provided.
   if (SS.isSet())
     return false;
 
   // Only in C++ or ObjC++.
   if (!getLangOpts().CPlusPlus)
     return false;
 
   // Turn off ADL when we find certain kinds of declarations during
   // normal lookup:
   for (const NamedDecl *D : R) {
     // C++0x [basic.lookup.argdep]p3:
     //     -- a declaration of a class member
     // Since using decls preserve this property, we check this on the
     // original decl.
     if (D->isCXXClassMember())
       return false;
 
     // C++0x [basic.lookup.argdep]p3:
     //     -- a block-scope function declaration that is not a
     //        using-declaration
     // NOTE: we also trigger this for function templates (in fact, we
     // don't check the decl type at all, since all other decl types
     // turn off ADL anyway).
     if (isa<UsingShadowDecl>(D))
       D = cast<UsingShadowDecl>(D)->getTargetDecl();
     else if (D->getLexicalDeclContext()->isFunctionOrMethod())
       return false;
 
     // C++0x [basic.lookup.argdep]p3:
     //     -- a declaration that is neither a function or a function
     //        template
     // And also for builtin functions.
     if (const auto *FDecl = dyn_cast<FunctionDecl>(D)) {
       // But also builtin functions.
       if (FDecl->getBuiltinID() && FDecl->isImplicit())
         return false;
     } else if (!isa<FunctionTemplateDecl>(D))
       return false;
   }
 
   return true;
 }
 
 
 /// Diagnoses obvious problems with the use of the given declaration
 /// as an expression.  This is only actually called for lookups that
 /// were not overloaded, and it doesn't promise that the declaration
 /// will in fact be used.
 static bool CheckDeclInExpr(Sema &S, SourceLocation Loc, NamedDecl *D,
                             bool AcceptInvalid) {
   if (D->isInvalidDecl() && !AcceptInvalid)
     return true;
 
   if (isa<TypedefNameDecl>(D)) {
     S.Diag(Loc, diag::err_unexpected_typedef) << D->getDeclName();
     return true;
   }
 
   if (isa<ObjCInterfaceDecl>(D)) {
     S.Diag(Loc, diag::err_unexpected_interface) << D->getDeclName();
     return true;
   }
 
   if (isa<NamespaceDecl>(D)) {
     S.Diag(Loc, diag::err_unexpected_namespace) << D->getDeclName();
     return true;
   }
 
   return false;
 }
 
 // Certain multiversion types should be treated as overloaded even when there is
 // only one result.
 static bool ShouldLookupResultBeMultiVersionOverload(const LookupResult &R) {
   assert(R.isSingleResult() && "Expected only a single result");
   const auto *FD = dyn_cast<FunctionDecl>(R.getFoundDecl());
   return FD &&
          (FD->isCPUDispatchMultiVersion() || FD->isCPUSpecificMultiVersion());
 }
 
 ExprResult Sema::BuildDeclarationNameExpr(const CXXScopeSpec &SS,
                                           LookupResult &R, bool NeedsADL,
                                           bool AcceptInvalidDecl) {
   // If this is a single, fully-resolved result and we don't need ADL,
   // just build an ordinary singleton decl ref.
   if (!NeedsADL && R.isSingleResult() &&
       !R.getAsSingle<FunctionTemplateDecl>() &&
       !ShouldLookupResultBeMultiVersionOverload(R))
     return BuildDeclarationNameExpr(SS, R.getLookupNameInfo(), R.getFoundDecl(),
                                     R.getRepresentativeDecl(), nullptr,
                                     AcceptInvalidDecl);
 
   // We only need to check the declaration if there's exactly one
   // result, because in the overloaded case the results can only be
   // functions and function templates.
   if (R.isSingleResult() && !ShouldLookupResultBeMultiVersionOverload(R) &&
       CheckDeclInExpr(*this, R.getNameLoc(), R.getFoundDecl(),
                       AcceptInvalidDecl))
     return ExprError();
 
   // Otherwise, just build an unresolved lookup expression.  Suppress
   // any lookup-related diagnostics; we'll hash these out later, when
   // we've picked a target.
   R.suppressDiagnostics();
 
   UnresolvedLookupExpr *ULE
     = UnresolvedLookupExpr::Create(Context, R.getNamingClass(),
                                    SS.getWithLocInContext(Context),
                                    R.getLookupNameInfo(),
                                    NeedsADL, R.isOverloadedResult(),
                                    R.begin(), R.end());
 
   return ULE;
 }
 
 static void diagnoseUncapturableValueReferenceOrBinding(Sema &S,
                                                         SourceLocation loc,
                                                         ValueDecl *var);
 
 /// Complete semantic analysis for a reference to the given declaration.
 ExprResult Sema::BuildDeclarationNameExpr(
     const CXXScopeSpec &SS, const DeclarationNameInfo &NameInfo, NamedDecl *D,
     NamedDecl *FoundD, const TemplateArgumentListInfo *TemplateArgs,
     bool AcceptInvalidDecl) {
   assert(D && "Cannot refer to a NULL declaration");
   assert(!isa<FunctionTemplateDecl>(D) &&
          "Cannot refer unambiguously to a function template");
 
   SourceLocation Loc = NameInfo.getLoc();
   if (CheckDeclInExpr(*this, Loc, D, AcceptInvalidDecl)) {
     // Recovery from invalid cases (e.g. D is an invalid Decl).
     // We use the dependent type for the RecoveryExpr to prevent bogus follow-up
     // diagnostics, as invalid decls use int as a fallback type.
     return CreateRecoveryExpr(NameInfo.getBeginLoc(), NameInfo.getEndLoc(), {});
   }
 
   if (TemplateDecl *Template = dyn_cast<TemplateDecl>(D)) {
     // Specifically diagnose references to class templates that are missing
     // a template argument list.
     diagnoseMissingTemplateArguments(TemplateName(Template), Loc);
     return ExprError();
   }
 
   // Make sure that we're referring to a value.
   if (!isa<ValueDecl, UnresolvedUsingIfExistsDecl>(D)) {
     Diag(Loc, diag::err_ref_non_value) << D << SS.getRange();
     Diag(D->getLocation(), diag::note_declared_at);
     return ExprError();
   }
 
   // Check whether this declaration can be used. Note that we suppress
   // this check when we're going to perform argument-dependent lookup
   // on this function name, because this might not be the function
   // that overload resolution actually selects.
   if (DiagnoseUseOfDecl(D, Loc))
     return ExprError();
 
   auto *VD = cast<ValueDecl>(D);
 
   // Only create DeclRefExpr's for valid Decl's.
   if (VD->isInvalidDecl() && !AcceptInvalidDecl)
     return ExprError();
 
   // Handle members of anonymous structs and unions.  If we got here,
   // and the reference is to a class member indirect field, then this
   // must be the subject of a pointer-to-member expression.
   if (auto *IndirectField = dyn_cast<IndirectFieldDecl>(VD);
       IndirectField && !IndirectField->isCXXClassMember())
     return BuildAnonymousStructUnionMemberReference(SS, NameInfo.getLoc(),
                                                     IndirectField);
 
   QualType type = VD->getType();
   if (type.isNull())
     return ExprError();
   ExprValueKind valueKind = VK_PRValue;
 
   // In 'T ...V;', the type of the declaration 'V' is 'T...', but the type of
   // a reference to 'V' is simply (unexpanded) 'T'. The type, like the value,
   // is expanded by some outer '...' in the context of the use.
   type = type.getNonPackExpansionType();
 
   switch (D->getKind()) {
     // Ignore all the non-ValueDecl kinds.
 #define ABSTRACT_DECL(kind)
 #define VALUE(type, base)
 #define DECL(type, base) case Decl::type:
 #include "clang/AST/DeclNodes.inc"
     llvm_unreachable("invalid value decl kind");
 
   // These shouldn't make it here.
   case Decl::ObjCAtDefsField:
     llvm_unreachable("forming non-member reference to ivar?");
 
   // Enum constants are always r-values and never references.
   // Unresolved using declarations are dependent.
   case Decl::EnumConstant:
   case Decl::UnresolvedUsingValue:
   case Decl::OMPDeclareReduction:
   case Decl::OMPDeclareMapper:
     valueKind = VK_PRValue;
     break;
 
   // Fields and indirect fields that got here must be for
   // pointer-to-member expressions; we just call them l-values for
   // internal consistency, because this subexpression doesn't really
   // exist in the high-level semantics.
   case Decl::Field:
   case Decl::IndirectField:
   case Decl::ObjCIvar:
     assert(getLangOpts().CPlusPlus && "building reference to field in C?");
 
     // These can't have reference type in well-formed programs, but
     // for internal consistency we do this anyway.
     type = type.getNonReferenceType();
     valueKind = VK_LValue;
     break;
 
   // Non-type template parameters are either l-values or r-values
   // depending on the type.
   case Decl::NonTypeTemplateParm: {
     if (const ReferenceType *reftype = type->getAs<ReferenceType>()) {
       type = reftype->getPointeeType();
       valueKind = VK_LValue; // even if the parameter is an r-value reference
       break;
     }
 
     // [expr.prim.id.unqual]p2:
     //   If the entity is a template parameter object for a template
     //   parameter of type T, the type of the expression is const T.
     //   [...] The expression is an lvalue if the entity is a [...] template
     //   parameter object.
     if (type->isRecordType()) {
       type = type.getUnqualifiedType().withConst();
       valueKind = VK_LValue;
       break;
     }
 
     // For non-references, we need to strip qualifiers just in case
     // the template parameter was declared as 'const int' or whatever.
     valueKind = VK_PRValue;
     type = type.getUnqualifiedType();
     break;
   }
 
   case Decl::Var:
   case Decl::VarTemplateSpecialization:
   case Decl::VarTemplatePartialSpecialization:
   case Decl::Decomposition:
   case Decl::OMPCapturedExpr:
     // In C, "extern void blah;" is valid and is an r-value.
     if (!getLangOpts().CPlusPlus && !type.hasQualifiers() &&
         type->isVoidType()) {
       valueKind = VK_PRValue;
       break;
     }
     [[fallthrough]];
 
   case Decl::ImplicitParam:
   case Decl::ParmVar: {
     // These are always l-values.
     valueKind = VK_LValue;
     type = type.getNonReferenceType();
 
     // FIXME: Does the addition of const really only apply in
     // potentially-evaluated contexts? Since the variable isn't actually
     // captured in an unevaluated context, it seems that the answer is no.
     if (!isUnevaluatedContext()) {
       QualType CapturedType = getCapturedDeclRefType(cast<VarDecl>(VD), Loc);
       if (!CapturedType.isNull())
         type = CapturedType;
     }
 
     break;
   }
 
   case Decl::Binding:
     // These are always lvalues.
     valueKind = VK_LValue;
     type = type.getNonReferenceType();
     break;
 
   case Decl::Function: {
     if (unsigned BID = cast<FunctionDecl>(VD)->getBuiltinID()) {
       if (!Context.BuiltinInfo.isDirectlyAddressable(BID)) {
         type = Context.BuiltinFnTy;
         valueKind = VK_PRValue;
         break;
       }
     }
 
     const FunctionType *fty = type->castAs<FunctionType>();
 
     // If we're referring to a function with an __unknown_anytype
     // result type, make the entire expression __unknown_anytype.
     if (fty->getReturnType() == Context.UnknownAnyTy) {
       type = Context.UnknownAnyTy;
       valueKind = VK_PRValue;
       break;
     }
 
     // Functions are l-values in C++.
     if (getLangOpts().CPlusPlus) {
       valueKind = VK_LValue;
       break;
     }
 
     // C99 DR 316 says that, if a function type comes from a
     // function definition (without a prototype), that type is only
     // used for checking compatibility. Therefore, when referencing
     // the function, we pretend that we don't have the full function
     // type.
     if (!cast<FunctionDecl>(VD)->hasPrototype() && isa<FunctionProtoType>(fty))
       type = Context.getFunctionNoProtoType(fty->getReturnType(),
                                             fty->getExtInfo());
 
     // Functions are r-values in C.
     valueKind = VK_PRValue;
     break;
   }
 
   case Decl::CXXDeductionGuide:
     llvm_unreachable("building reference to deduction guide");
 
   case Decl::MSProperty:
   case Decl::MSGuid:
   case Decl::TemplateParamObject:
     // FIXME: Should MSGuidDecl and template parameter objects be subject to
     // capture in OpenMP, or duplicated between host and device?
     valueKind = VK_LValue;
     break;
 
   case Decl::UnnamedGlobalConstant:
     valueKind = VK_LValue;
     break;
 
   case Decl::CXXMethod:
     // If we're referring to a method with an __unknown_anytype
     // result type, make the entire expression __unknown_anytype.
     // This should only be possible with a type written directly.
     if (const FunctionProtoType *proto =
             dyn_cast<FunctionProtoType>(VD->getType()))
       if (proto->getReturnType() == Context.UnknownAnyTy) {
         type = Context.UnknownAnyTy;
         valueKind = VK_PRValue;
         break;
       }
 
     // C++ methods are l-values if static, r-values if non-static.
     if (cast<CXXMethodDecl>(VD)->isStatic()) {
       valueKind = VK_LValue;
       break;
     }
     [[fallthrough]];
 
   case Decl::CXXConversion:
   case Decl::CXXDestructor:
   case Decl::CXXConstructor:
     valueKind = VK_PRValue;
     break;
   }
 
   auto *E =
       BuildDeclRefExpr(VD, type, valueKind, NameInfo, &SS, FoundD,
                        /*FIXME: TemplateKWLoc*/ SourceLocation(), TemplateArgs);
   // Clang AST consumers assume a DeclRefExpr refers to a valid decl. We
   // wrap a DeclRefExpr referring to an invalid decl with a dependent-type
   // RecoveryExpr to avoid follow-up semantic analysis (thus prevent bogus
   // diagnostics).
   if (VD->isInvalidDecl() && E)
     return CreateRecoveryExpr(E->getBeginLoc(), E->getEndLoc(), {E});
   return E;
 }
 
 static void ConvertUTF8ToWideString(unsigned CharByteWidth, StringRef Source,
                                     SmallString<32> &Target) {
   Target.resize(CharByteWidth * (Source.size() + 1));
   char *ResultPtr = &Target[0];
   const llvm::UTF8 *ErrorPtr;
   bool success =
       llvm::ConvertUTF8toWide(CharByteWidth, Source, ResultPtr, ErrorPtr);
   (void)success;
   assert(success);
   Target.resize(ResultPtr - &Target[0]);
 }
 
 ExprResult Sema::BuildPredefinedExpr(SourceLocation Loc,
                                      PredefinedExpr::IdentKind IK) {
   // Pick the current block, lambda, captured statement or function.
   Decl *currentDecl = nullptr;
   if (const BlockScopeInfo *BSI = getCurBlock())
     currentDecl = BSI->TheDecl;
   else if (const LambdaScopeInfo *LSI = getCurLambda())
     currentDecl = LSI->CallOperator;
   else if (const CapturedRegionScopeInfo *CSI = getCurCapturedRegion())
     currentDecl = CSI->TheCapturedDecl;
   else
     currentDecl = getCurFunctionOrMethodDecl();
 
   if (!currentDecl) {
     Diag(Loc, diag::ext_predef_outside_function);
     currentDecl = Context.getTranslationUnitDecl();
   }
 
   QualType ResTy;
   StringLiteral *SL = nullptr;
   if (cast<DeclContext>(currentDecl)->isDependentContext())
     ResTy = Context.DependentTy;
   else {
     // Pre-defined identifiers are of type char[x], where x is the length of
     // the string.
     auto Str = PredefinedExpr::ComputeName(IK, currentDecl);
     unsigned Length = Str.length();
 
     llvm::APInt LengthI(32, Length + 1);
     if (IK == PredefinedExpr::LFunction || IK == PredefinedExpr::LFuncSig) {
       ResTy =
           Context.adjustStringLiteralBaseType(Context.WideCharTy.withConst());
       SmallString<32> RawChars;
       ConvertUTF8ToWideString(Context.getTypeSizeInChars(ResTy).getQuantity(),
                               Str, RawChars);
       ResTy = Context.getConstantArrayType(ResTy, LengthI, nullptr,
                                            ArrayType::Normal,
                                            /*IndexTypeQuals*/ 0);
       SL = StringLiteral::Create(Context, RawChars, StringLiteral::Wide,
                                  /*Pascal*/ false, ResTy, Loc);
     } else {
       ResTy = Context.adjustStringLiteralBaseType(Context.CharTy.withConst());
       ResTy = Context.getConstantArrayType(ResTy, LengthI, nullptr,
                                            ArrayType::Normal,
                                            /*IndexTypeQuals*/ 0);
       SL = StringLiteral::Create(Context, Str, StringLiteral::Ordinary,
                                  /*Pascal*/ false, ResTy, Loc);
     }
   }
 
   return PredefinedExpr::Create(Context, Loc, ResTy, IK, LangOpts.MicrosoftExt,
                                 SL);
 }
 
 ExprResult Sema::BuildSYCLUniqueStableNameExpr(SourceLocation OpLoc,
                                                SourceLocation LParen,
                                                SourceLocation RParen,
                                                TypeSourceInfo *TSI) {
   return SYCLUniqueStableNameExpr::Create(Context, OpLoc, LParen, RParen, TSI);
 }
 
 ExprResult Sema::ActOnSYCLUniqueStableNameExpr(SourceLocation OpLoc,
                                                SourceLocation LParen,
                                                SourceLocation RParen,
                                                ParsedType ParsedTy) {
   TypeSourceInfo *TSI = nullptr;
   QualType Ty = GetTypeFromParser(ParsedTy, &TSI);
 
   if (Ty.isNull())
     return ExprError();
   if (!TSI)
     TSI = Context.getTrivialTypeSourceInfo(Ty, LParen);
 
   return BuildSYCLUniqueStableNameExpr(OpLoc, LParen, RParen, TSI);
 }
 
 ExprResult Sema::ActOnPredefinedExpr(SourceLocation Loc, tok::TokenKind Kind) {
   PredefinedExpr::IdentKind IK;
 
   switch (Kind) {
   default: llvm_unreachable("Unknown simple primary expr!");
   case tok::kw___func__: IK = PredefinedExpr::Func; break; // [C99 6.4.2.2]
   case tok::kw___FUNCTION__: IK = PredefinedExpr::Function; break;
   case tok::kw___FUNCDNAME__: IK = PredefinedExpr::FuncDName; break; // [MS]
   case tok::kw___FUNCSIG__: IK = PredefinedExpr::FuncSig; break; // [MS]
   case tok::kw_L__FUNCTION__: IK = PredefinedExpr::LFunction; break; // [MS]
   case tok::kw_L__FUNCSIG__: IK = PredefinedExpr::LFuncSig; break; // [MS]
   case tok::kw___PRETTY_FUNCTION__: IK = PredefinedExpr::PrettyFunction; break;
   }
 
   return BuildPredefinedExpr(Loc, IK);
 }
 
 ExprResult Sema::ActOnCharacterConstant(const Token &Tok, Scope *UDLScope) {
   SmallString<16> CharBuffer;
   bool Invalid = false;
   StringRef ThisTok = PP.getSpelling(Tok, CharBuffer, &Invalid);
   if (Invalid)
     return ExprError();
 
   CharLiteralParser Literal(ThisTok.begin(), ThisTok.end(), Tok.getLocation(),
                             PP, Tok.getKind());
   if (Literal.hadError())
     return ExprError();
 
   QualType Ty;
   if (Literal.isWide())
     Ty = Context.WideCharTy; // L'x' -> wchar_t in C and C++.
   else if (Literal.isUTF8() && getLangOpts().C2x)
     Ty = Context.UnsignedCharTy; // u8'x' -> unsigned char in C2x
   else if (Literal.isUTF8() && getLangOpts().Char8)
     Ty = Context.Char8Ty; // u8'x' -> char8_t when it exists.
   else if (Literal.isUTF16())
     Ty = Context.Char16Ty; // u'x' -> char16_t in C11 and C++11.
   else if (Literal.isUTF32())
     Ty = Context.Char32Ty; // U'x' -> char32_t in C11 and C++11.
   else if (!getLangOpts().CPlusPlus || Literal.isMultiChar())
     Ty = Context.IntTy;   // 'x' -> int in C, 'wxyz' -> int in C++.
   else
     Ty = Context.CharTy; // 'x' -> char in C++;
                          // u8'x' -> char in C11-C17 and in C++ without char8_t.
 
   CharacterLiteral::CharacterKind Kind = CharacterLiteral::Ascii;
   if (Literal.isWide())
     Kind = CharacterLiteral::Wide;
   else if (Literal.isUTF16())
     Kind = CharacterLiteral::UTF16;
   else if (Literal.isUTF32())
     Kind = CharacterLiteral::UTF32;
   else if (Literal.isUTF8())
     Kind = CharacterLiteral::UTF8;
 
   Expr *Lit = new (Context) CharacterLiteral(Literal.getValue(), Kind, Ty,
                                              Tok.getLocation());
 
   if (Literal.getUDSuffix().empty())
     return Lit;
 
   // We're building a user-defined literal.
   IdentifierInfo *UDSuffix = &Context.Idents.get(Literal.getUDSuffix());
   SourceLocation UDSuffixLoc =
     getUDSuffixLoc(*this, Tok.getLocation(), Literal.getUDSuffixOffset());
 
   // Make sure we're allowed user-defined literals here.
   if (!UDLScope)
     return ExprError(Diag(UDSuffixLoc, diag::err_invalid_character_udl));
 
   // C++11 [lex.ext]p6: The literal L is treated as a call of the form
   //   operator "" X (ch)
   return BuildCookedLiteralOperatorCall(*this, UDLScope, UDSuffix, UDSuffixLoc,
                                         Lit, Tok.getLocation());
 }
 
 ExprResult Sema::ActOnIntegerConstant(SourceLocation Loc, uint64_t Val) {
   unsigned IntSize = Context.getTargetInfo().getIntWidth();
   return IntegerLiteral::Create(Context, llvm::APInt(IntSize, Val),
                                 Context.IntTy, Loc);
 }
 
 static Expr *BuildFloatingLiteral(Sema &S, NumericLiteralParser &Literal,
                                   QualType Ty, SourceLocation Loc) {
   const llvm::fltSemantics &Format = S.Context.getFloatTypeSemantics(Ty);
 
   using llvm::APFloat;
   APFloat Val(Format);
 
   APFloat::opStatus result = Literal.GetFloatValue(Val);
 
   // Overflow is always an error, but underflow is only an error if
   // we underflowed to zero (APFloat reports denormals as underflow).
   if ((result & APFloat::opOverflow) ||
       ((result & APFloat::opUnderflow) && Val.isZero())) {
     unsigned diagnostic;
     SmallString<20> buffer;
     if (result & APFloat::opOverflow) {
       diagnostic = diag::warn_float_overflow;
       APFloat::getLargest(Format).toString(buffer);
     } else {
       diagnostic = diag::warn_float_underflow;
       APFloat::getSmallest(Format).toString(buffer);
     }
 
     S.Diag(Loc, diagnostic)
       << Ty
       << StringRef(buffer.data(), buffer.size());
   }
 
   bool isExact = (result == APFloat::opOK);
   return FloatingLiteral::Create(S.Context, Val, isExact, Ty, Loc);
 }
 
 bool Sema::CheckLoopHintExpr(Expr *E, SourceLocation Loc) {
   assert(E && "Invalid expression");
 
   if (E->isValueDependent())
     return false;
 
   QualType QT = E->getType();
   if (!QT->isIntegerType() || QT->isBooleanType() || QT->isCharType()) {
     Diag(E->getExprLoc(), diag::err_pragma_loop_invalid_argument_type) << QT;
     return true;
   }
 
   llvm::APSInt ValueAPS;
   ExprResult R = VerifyIntegerConstantExpression(E, &ValueAPS);
 
   if (R.isInvalid())
     return true;
 
   bool ValueIsPositive = ValueAPS.isStrictlyPositive();
   if (!ValueIsPositive || ValueAPS.getActiveBits() > 31) {
     Diag(E->getExprLoc(), diag::err_pragma_loop_invalid_argument_value)
         << toString(ValueAPS, 10) << ValueIsPositive;
     return true;
   }
 
   return false;
 }
 
 ExprResult Sema::ActOnNumericConstant(const Token &Tok, Scope *UDLScope) {
   // Fast path for a single digit (which is quite common).  A single digit
   // cannot have a trigraph, escaped newline, radix prefix, or suffix.
   if (Tok.getLength() == 1) {
     const char Val = PP.getSpellingOfSingleCharacterNumericConstant(Tok);
     return ActOnIntegerConstant(Tok.getLocation(), Val-'0');
   }
 
   SmallString<128> SpellingBuffer;
   // NumericLiteralParser wants to overread by one character.  Add padding to
   // the buffer in case the token is copied to the buffer.  If getSpelling()
   // returns a StringRef to the memory buffer, it should have a null char at
   // the EOF, so it is also safe.
   SpellingBuffer.resize(Tok.getLength() + 1);
 
   // Get the spelling of the token, which eliminates trigraphs, etc.
   bool Invalid = false;
   StringRef TokSpelling = PP.getSpelling(Tok, SpellingBuffer, &Invalid);
   if (Invalid)
     return ExprError();
 
   NumericLiteralParser Literal(TokSpelling, Tok.getLocation(),
                                PP.getSourceManager(), PP.getLangOpts(),
                                PP.getTargetInfo(), PP.getDiagnostics());
   if (Literal.hadError)
     return ExprError();
 
   if (Literal.hasUDSuffix()) {
     // We're building a user-defined literal.
     const IdentifierInfo *UDSuffix = &Context.Idents.get(Literal.getUDSuffix());
     SourceLocation UDSuffixLoc =
       getUDSuffixLoc(*this, Tok.getLocation(), Literal.getUDSuffixOffset());
 
     // Make sure we're allowed user-defined literals here.
     if (!UDLScope)
       return ExprError(Diag(UDSuffixLoc, diag::err_invalid_numeric_udl));
 
     QualType CookedTy;
     if (Literal.isFloatingLiteral()) {
       // C++11 [lex.ext]p4: If S contains a literal operator with parameter type
       // long double, the literal is treated as a call of the form
       //   operator "" X (f L)
       CookedTy = Context.LongDoubleTy;
     } else {
       // C++11 [lex.ext]p3: If S contains a literal operator with parameter type
       // unsigned long long, the literal is treated as a call of the form
       //   operator "" X (n ULL)
       CookedTy = Context.UnsignedLongLongTy;
     }
 
     DeclarationName OpName =
       Context.DeclarationNames.getCXXLiteralOperatorName(UDSuffix);
     DeclarationNameInfo OpNameInfo(OpName, UDSuffixLoc);
     OpNameInfo.setCXXLiteralOperatorNameLoc(UDSuffixLoc);
 
     SourceLocation TokLoc = Tok.getLocation();
 
     // Perform literal operator lookup to determine if we're building a raw
     // literal or a cooked one.
     LookupResult R(*this, OpName, UDSuffixLoc, LookupOrdinaryName);
     switch (LookupLiteralOperator(UDLScope, R, CookedTy,
                                   /*AllowRaw*/ true, /*AllowTemplate*/ true,
                                   /*AllowStringTemplatePack*/ false,
                                   /*DiagnoseMissing*/ !Literal.isImaginary)) {
     case LOLR_ErrorNoDiagnostic:
       // Lookup failure for imaginary constants isn't fatal, there's still the
       // GNU extension producing _Complex types.
       break;
     case LOLR_Error:
       return ExprError();
     case LOLR_Cooked: {
       Expr *Lit;
       if (Literal.isFloatingLiteral()) {
         Lit = BuildFloatingLiteral(*this, Literal, CookedTy, Tok.getLocation());
       } else {
         llvm::APInt ResultVal(Context.getTargetInfo().getLongLongWidth(), 0);
         if (Literal.GetIntegerValue(ResultVal))
           Diag(Tok.getLocation(), diag::err_integer_literal_too_large)
               << /* Unsigned */ 1;
         Lit = IntegerLiteral::Create(Context, ResultVal, CookedTy,
                                      Tok.getLocation());
       }
       return BuildLiteralOperatorCall(R, OpNameInfo, Lit, TokLoc);
     }
 
     case LOLR_Raw: {
       // C++11 [lit.ext]p3, p4: If S contains a raw literal operator, the
       // literal is treated as a call of the form
       //   operator "" X ("n")
       unsigned Length = Literal.getUDSuffixOffset();
       QualType StrTy = Context.getConstantArrayType(
           Context.adjustStringLiteralBaseType(Context.CharTy.withConst()),
           llvm::APInt(32, Length + 1), nullptr, ArrayType::Normal, 0);
       Expr *Lit =
           StringLiteral::Create(Context, StringRef(TokSpelling.data(), Length),
                                 StringLiteral::Ordinary,
                                 /*Pascal*/ false, StrTy, &TokLoc, 1);
       return BuildLiteralOperatorCall(R, OpNameInfo, Lit, TokLoc);
     }
 
     case LOLR_Template: {
       // C++11 [lit.ext]p3, p4: Otherwise (S contains a literal operator
       // template), L is treated as a call fo the form
       //   operator "" X <'c1', 'c2', ... 'ck'>()
       // where n is the source character sequence c1 c2 ... ck.
       TemplateArgumentListInfo ExplicitArgs;
       unsigned CharBits = Context.getIntWidth(Context.CharTy);
       bool CharIsUnsigned = Context.CharTy->isUnsignedIntegerType();
       llvm::APSInt Value(CharBits, CharIsUnsigned);
       for (unsigned I = 0, N = Literal.getUDSuffixOffset(); I != N; ++I) {
         Value = TokSpelling[I];
         TemplateArgument Arg(Context, Value, Context.CharTy);
         TemplateArgumentLocInfo ArgInfo;
         ExplicitArgs.addArgument(TemplateArgumentLoc(Arg, ArgInfo));
       }
       return BuildLiteralOperatorCall(R, OpNameInfo, std::nullopt, TokLoc,
                                       &ExplicitArgs);
     }
     case LOLR_StringTemplatePack:
       llvm_unreachable("unexpected literal operator lookup result");
     }
   }
 
   Expr *Res;
 
   if (Literal.isFixedPointLiteral()) {
     QualType Ty;
 
     if (Literal.isAccum) {
       if (Literal.isHalf) {
         Ty = Context.ShortAccumTy;
       } else if (Literal.isLong) {
         Ty = Context.LongAccumTy;
       } else {
         Ty = Context.AccumTy;
       }
     } else if (Literal.isFract) {
       if (Literal.isHalf) {
         Ty = Context.ShortFractTy;
       } else if (Literal.isLong) {
         Ty = Context.LongFractTy;
       } else {
         Ty = Context.FractTy;
       }
     }
 
     if (Literal.isUnsigned) Ty = Context.getCorrespondingUnsignedType(Ty);
 
     bool isSigned = !Literal.isUnsigned;
     unsigned scale = Context.getFixedPointScale(Ty);
     unsigned bit_width = Context.getTypeInfo(Ty).Width;
 
     llvm::APInt Val(bit_width, 0, isSigned);
     bool Overflowed = Literal.GetFixedPointValue(Val, scale);
     bool ValIsZero = Val.isZero() && !Overflowed;
 
     auto MaxVal = Context.getFixedPointMax(Ty).getValue();
     if (Literal.isFract && Val == MaxVal + 1 && !ValIsZero)
       // Clause 6.4.4 - The value of a constant shall be in the range of
       // representable values for its type, with exception for constants of a
       // fract type with a value of exactly 1; such a constant shall denote
       // the maximal value for the type.
       --Val;
     else if (Val.ugt(MaxVal) || Overflowed)
       Diag(Tok.getLocation(), diag::err_too_large_for_fixed_point);
 
     Res = FixedPointLiteral::CreateFromRawInt(Context, Val, Ty,
                                               Tok.getLocation(), scale);
   } else if (Literal.isFloatingLiteral()) {
     QualType Ty;
     if (Literal.isHalf){
       if (getOpenCLOptions().isAvailableOption("cl_khr_fp16", getLangOpts()))
         Ty = Context.HalfTy;
       else {
         Diag(Tok.getLocation(), diag::err_half_const_requires_fp16);
         return ExprError();
       }
     } else if (Literal.isFloat)
       Ty = Context.FloatTy;
     else if (Literal.isLong)
       Ty = Context.LongDoubleTy;
     else if (Literal.isFloat16)
       Ty = Context.Float16Ty;
     else if (Literal.isFloat128)
       Ty = Context.Float128Ty;
     else
       Ty = Context.DoubleTy;
 
     Res = BuildFloatingLiteral(*this, Literal, Ty, Tok.getLocation());
 
     if (Ty == Context.DoubleTy) {
       if (getLangOpts().SinglePrecisionConstants) {
         if (Ty->castAs<BuiltinType>()->getKind() != BuiltinType::Float) {
           Res = ImpCastExprToType(Res, Context.FloatTy, CK_FloatingCast).get();
         }
       } else if (getLangOpts().OpenCL && !getOpenCLOptions().isAvailableOption(
                                              "cl_khr_fp64", getLangOpts())) {
         // Impose single-precision float type when cl_khr_fp64 is not enabled.
         Diag(Tok.getLocation(), diag::warn_double_const_requires_fp64)
             << (getLangOpts().getOpenCLCompatibleVersion() >= 300);
         Res = ImpCastExprToType(Res, Context.FloatTy, CK_FloatingCast).get();
       }
     }
   } else if (!Literal.isIntegerLiteral()) {
     return ExprError();
   } else {
     QualType Ty;
 
     // 'z/uz' literals are a C++23 feature.
     if (Literal.isSizeT)
       Diag(Tok.getLocation(), getLangOpts().CPlusPlus
                                   ? getLangOpts().CPlusPlus23
                                         ? diag::warn_cxx20_compat_size_t_suffix
                                         : diag::ext_cxx23_size_t_suffix
                                   : diag::err_cxx23_size_t_suffix);
 
     // 'wb/uwb' literals are a C2x feature. We support _BitInt as a type in C++,
     // but we do not currently support the suffix in C++ mode because it's not
     // entirely clear whether WG21 will prefer this suffix to return a library
     // type such as std::bit_int instead of returning a _BitInt.
     if (Literal.isBitInt && !getLangOpts().CPlusPlus)
       PP.Diag(Tok.getLocation(), getLangOpts().C2x
                                      ? diag::warn_c2x_compat_bitint_suffix
                                      : diag::ext_c2x_bitint_suffix);
 
     // Get the value in the widest-possible width. What is "widest" depends on
     // whether the literal is a bit-precise integer or not. For a bit-precise
     // integer type, try to scan the source to determine how many bits are
     // needed to represent the value. This may seem a bit expensive, but trying
     // to get the integer value from an overly-wide APInt is *extremely*
     // expensive, so the naive approach of assuming
     // llvm::IntegerType::MAX_INT_BITS is a big performance hit.
     unsigned BitsNeeded =
         Literal.isBitInt ? llvm::APInt::getSufficientBitsNeeded(
                                Literal.getLiteralDigits(), Literal.getRadix())
                          : Context.getTargetInfo().getIntMaxTWidth();
     llvm::APInt ResultVal(BitsNeeded, 0);
 
     if (Literal.GetIntegerValue(ResultVal)) {
       // If this value didn't fit into uintmax_t, error and force to ull.
       Diag(Tok.getLocation(), diag::err_integer_literal_too_large)
           << /* Unsigned */ 1;
       Ty = Context.UnsignedLongLongTy;
       assert(Context.getTypeSize(Ty) == ResultVal.getBitWidth() &&
              "long long is not intmax_t?");
     } else {
       // If this value fits into a ULL, try to figure out what else it fits into
       // according to the rules of C99 6.4.4.1p5.
 
       // Octal, Hexadecimal, and integers with a U suffix are allowed to
       // be an unsigned int.
       bool AllowUnsigned = Literal.isUnsigned || Literal.getRadix() != 10;
 
       // Check from smallest to largest, picking the smallest type we can.
       unsigned Width = 0;
 
       // Microsoft specific integer suffixes are explicitly sized.
       if (Literal.MicrosoftInteger) {
         if (Literal.MicrosoftInteger == 8 && !Literal.isUnsigned) {
           Width = 8;
           Ty = Context.CharTy;
         } else {
           Width = Literal.MicrosoftInteger;
           Ty = Context.getIntTypeForBitwidth(Width,
                                              /*Signed=*/!Literal.isUnsigned);
         }
       }
 
       // Bit-precise integer literals are automagically-sized based on the
       // width required by the literal.
       if (Literal.isBitInt) {
         // The signed version has one more bit for the sign value. There are no
         // zero-width bit-precise integers, even if the literal value is 0.
         Width = std::max(ResultVal.getActiveBits(), 1u) +
                 (Literal.isUnsigned ? 0u : 1u);
 
         // Diagnose if the width of the constant is larger than BITINT_MAXWIDTH,
         // and reset the type to the largest supported width.
         unsigned int MaxBitIntWidth =
             Context.getTargetInfo().getMaxBitIntWidth();
         if (Width > MaxBitIntWidth) {
           Diag(Tok.getLocation(), diag::err_integer_literal_too_large)
               << Literal.isUnsigned;
           Width = MaxBitIntWidth;
         }
 
         // Reset the result value to the smaller APInt and select the correct
         // type to be used. Note, we zext even for signed values because the
         // literal itself is always an unsigned value (a preceeding - is a
         // unary operator, not part of the literal).
         ResultVal = ResultVal.zextOrTrunc(Width);
         Ty = Context.getBitIntType(Literal.isUnsigned, Width);
       }
 
       // Check C++23 size_t literals.
       if (Literal.isSizeT) {
         assert(!Literal.MicrosoftInteger &&
                "size_t literals can't be Microsoft literals");
         unsigned SizeTSize = Context.getTargetInfo().getTypeWidth(
             Context.getTargetInfo().getSizeType());
 
         // Does it fit in size_t?
         if (ResultVal.isIntN(SizeTSize)) {
           // Does it fit in ssize_t?
           if (!Literal.isUnsigned && ResultVal[SizeTSize - 1] == 0)
             Ty = Context.getSignedSizeType();
           else if (AllowUnsigned)
             Ty = Context.getSizeType();
           Width = SizeTSize;
         }
       }
 
       if (Ty.isNull() && !Literal.isLong && !Literal.isLongLong &&
           !Literal.isSizeT) {
         // Are int/unsigned possibilities?
         unsigned IntSize = Context.getTargetInfo().getIntWidth();
 
         // Does it fit in a unsigned int?
         if (ResultVal.isIntN(IntSize)) {
           // Does it fit in a signed int?
           if (!Literal.isUnsigned && ResultVal[IntSize-1] == 0)
             Ty = Context.IntTy;
           else if (AllowUnsigned)
             Ty = Context.UnsignedIntTy;
           Width = IntSize;
         }
       }
 
       // Are long/unsigned long possibilities?
       if (Ty.isNull() && !Literal.isLongLong && !Literal.isSizeT) {
         unsigned LongSize = Context.getTargetInfo().getLongWidth();
 
         // Does it fit in a unsigned long?
         if (ResultVal.isIntN(LongSize)) {
           // Does it fit in a signed long?
           if (!Literal.isUnsigned && ResultVal[LongSize-1] == 0)
             Ty = Context.LongTy;
           else if (AllowUnsigned)
             Ty = Context.UnsignedLongTy;
           // Check according to the rules of C90 6.1.3.2p5. C++03 [lex.icon]p2
           // is compatible.
           else if (!getLangOpts().C99 && !getLangOpts().CPlusPlus11) {
             const unsigned LongLongSize =
                 Context.getTargetInfo().getLongLongWidth();
             Diag(Tok.getLocation(),
                  getLangOpts().CPlusPlus
                      ? Literal.isLong
                            ? diag::warn_old_implicitly_unsigned_long_cxx
                            : /*C++98 UB*/ diag::
                                  ext_old_implicitly_unsigned_long_cxx
                      : diag::warn_old_implicitly_unsigned_long)
                 << (LongLongSize > LongSize ? /*will have type 'long long'*/ 0
                                             : /*will be ill-formed*/ 1);
             Ty = Context.UnsignedLongTy;
           }
           Width = LongSize;
         }
       }
 
       // Check long long if needed.
       if (Ty.isNull() && !Literal.isSizeT) {
         unsigned LongLongSize = Context.getTargetInfo().getLongLongWidth();
 
         // Does it fit in a unsigned long long?
         if (ResultVal.isIntN(LongLongSize)) {
           // Does it fit in a signed long long?
           // To be compatible with MSVC, hex integer literals ending with the
           // LL or i64 suffix are always signed in Microsoft mode.
           if (!Literal.isUnsigned && (ResultVal[LongLongSize-1] == 0 ||
               (getLangOpts().MSVCCompat && Literal.isLongLong)))
             Ty = Context.LongLongTy;
           else if (AllowUnsigned)
             Ty = Context.UnsignedLongLongTy;
           Width = LongLongSize;
 
           // 'long long' is a C99 or C++11 feature, whether the literal
           // explicitly specified 'long long' or we needed the extra width.
           if (getLangOpts().CPlusPlus)
             Diag(Tok.getLocation(), getLangOpts().CPlusPlus11
                                         ? diag::warn_cxx98_compat_longlong
                                         : diag::ext_cxx11_longlong);
           else if (!getLangOpts().C99)
             Diag(Tok.getLocation(), diag::ext_c99_longlong);
         }
       }
 
       // If we still couldn't decide a type, we either have 'size_t' literal
       // that is out of range, or a decimal literal that does not fit in a
       // signed long long and has no U suffix.
       if (Ty.isNull()) {
         if (Literal.isSizeT)
           Diag(Tok.getLocation(), diag::err_size_t_literal_too_large)
               << Literal.isUnsigned;
         else
           Diag(Tok.getLocation(),
                diag::ext_integer_literal_too_large_for_signed);
         Ty = Context.UnsignedLongLongTy;
         Width = Context.getTargetInfo().getLongLongWidth();
       }
 
       if (ResultVal.getBitWidth() != Width)
         ResultVal = ResultVal.trunc(Width);
     }
     Res = IntegerLiteral::Create(Context, ResultVal, Ty, Tok.getLocation());
   }
 
   // If this is an imaginary literal, create the ImaginaryLiteral wrapper.
   if (Literal.isImaginary) {
     Res = new (Context) ImaginaryLiteral(Res,
                                         Context.getComplexType(Res->getType()));
 
     Diag(Tok.getLocation(), diag::ext_imaginary_constant);
   }
   return Res;
 }
 
 ExprResult Sema::ActOnParenExpr(SourceLocation L, SourceLocation R, Expr *E) {
   assert(E && "ActOnParenExpr() missing expr");
   QualType ExprTy = E->getType();
   if (getLangOpts().ProtectParens && CurFPFeatures.getAllowFPReassociate() &&
       !E->isLValue() && ExprTy->hasFloatingRepresentation())
     return BuildBuiltinCallExpr(R, Builtin::BI__arithmetic_fence, E);
   return new (Context) ParenExpr(L, R, E);
 }
 
 static bool CheckVecStepTraitOperandType(Sema &S, QualType T,
                                          SourceLocation Loc,
                                          SourceRange ArgRange) {
   // [OpenCL 1.1 6.11.12] "The vec_step built-in function takes a built-in
   // scalar or vector data type argument..."
   // Every built-in scalar type (OpenCL 1.1 6.1.1) is either an arithmetic
   // type (C99 6.2.5p18) or void.
   if (!(T->isArithmeticType() || T->isVoidType() || T->isVectorType())) {
     S.Diag(Loc, diag::err_vecstep_non_scalar_vector_type)
       << T << ArgRange;
     return true;
   }
 
   assert((T->isVoidType() || !T->isIncompleteType()) &&
          "Scalar types should always be complete");
   return false;
 }
 
 static bool CheckExtensionTraitOperandType(Sema &S, QualType T,
                                            SourceLocation Loc,
                                            SourceRange ArgRange,
                                            UnaryExprOrTypeTrait TraitKind) {
   // Invalid types must be hard errors for SFINAE in C++.
   if (S.LangOpts.CPlusPlus)
     return true;
 
   // C99 6.5.3.4p1:
   if (T->isFunctionType() &&
       (TraitKind == UETT_SizeOf || TraitKind == UETT_AlignOf ||
        TraitKind == UETT_PreferredAlignOf)) {
     // sizeof(function)/alignof(function) is allowed as an extension.
     S.Diag(Loc, diag::ext_sizeof_alignof_function_type)
         << getTraitSpelling(TraitKind) << ArgRange;
     return false;
   }
 
   // Allow sizeof(void)/alignof(void) as an extension, unless in OpenCL where
   // this is an error (OpenCL v1.1 s6.3.k)
   if (T->isVoidType()) {
     unsigned DiagID = S.LangOpts.OpenCL ? diag::err_opencl_sizeof_alignof_type
                                         : diag::ext_sizeof_alignof_void_type;
     S.Diag(Loc, DiagID) << getTraitSpelling(TraitKind) << ArgRange;
     return false;
   }
 
   return true;
 }
 
 static bool CheckObjCTraitOperandConstraints(Sema &S, QualType T,
                                              SourceLocation Loc,
                                              SourceRange ArgRange,
                                              UnaryExprOrTypeTrait TraitKind) {
   // Reject sizeof(interface) and sizeof(interface<proto>) if the
   // runtime doesn't allow it.
   if (!S.LangOpts.ObjCRuntime.allowsSizeofAlignof() && T->isObjCObjectType()) {
     S.Diag(Loc, diag::err_sizeof_nonfragile_interface)
       << T << (TraitKind == UETT_SizeOf)
       << ArgRange;
     return true;
   }
 
   return false;
 }
 
 /// Check whether E is a pointer from a decayed array type (the decayed
 /// pointer type is equal to T) and emit a warning if it is.
 static void warnOnSizeofOnArrayDecay(Sema &S, SourceLocation Loc, QualType T,
                                      const Expr *E) {
   // Don't warn if the operation changed the type.
   if (T != E->getType())
     return;
 
   // Now look for array decays.
   const auto *ICE = dyn_cast<ImplicitCastExpr>(E);
   if (!ICE || ICE->getCastKind() != CK_ArrayToPointerDecay)
     return;
 
   S.Diag(Loc, diag::warn_sizeof_array_decay) << ICE->getSourceRange()
                                              << ICE->getType()
                                              << ICE->getSubExpr()->getType();
 }
 
 /// Check the constraints on expression operands to unary type expression
 /// and type traits.
 ///
 /// Completes any types necessary and validates the constraints on the operand
 /// expression. The logic mostly mirrors the type-based overload, but may modify
 /// the expression as it completes the type for that expression through template
 /// instantiation, etc.
 bool Sema::CheckUnaryExprOrTypeTraitOperand(Expr *E,
                                             UnaryExprOrTypeTrait ExprKind) {
   QualType ExprTy = E->getType();
   assert(!ExprTy->isReferenceType());
 
   bool IsUnevaluatedOperand =
       (ExprKind == UETT_SizeOf || ExprKind == UETT_AlignOf ||
        ExprKind == UETT_PreferredAlignOf || ExprKind == UETT_VecStep);
   if (IsUnevaluatedOperand) {
     ExprResult Result = CheckUnevaluatedOperand(E);
     if (Result.isInvalid())
       return true;
     E = Result.get();
   }
 
   // The operand for sizeof and alignof is in an unevaluated expression context,
   // so side effects could result in unintended consequences.
   // Exclude instantiation-dependent expressions, because 'sizeof' is sometimes
   // used to build SFINAE gadgets.
   // FIXME: Should we consider instantiation-dependent operands to 'alignof'?
   if (IsUnevaluatedOperand && !inTemplateInstantiation() &&
       !E->isInstantiationDependent() &&
       !E->getType()->isVariableArrayType() &&
       E->HasSideEffects(Context, false))
     Diag(E->getExprLoc(), diag::warn_side_effects_unevaluated_context);
 
   if (ExprKind == UETT_VecStep)
     return CheckVecStepTraitOperandType(*this, ExprTy, E->getExprLoc(),
                                         E->getSourceRange());
 
   // Explicitly list some types as extensions.
   if (!CheckExtensionTraitOperandType(*this, ExprTy, E->getExprLoc(),
                                       E->getSourceRange(), ExprKind))
     return false;
 
   // WebAssembly tables are always illegal operands to unary expressions and
   // type traits.
   if (Context.getTargetInfo().getTriple().isWasm() &&
       E->getType()->isWebAssemblyTableType()) {
     Diag(E->getExprLoc(), diag::err_wasm_table_invalid_uett_operand)
         << getTraitSpelling(ExprKind);
     return true;
   }
 
   // 'alignof' applied to an expression only requires the base element type of
   // the expression to be complete. 'sizeof' requires the expression's type to
   // be complete (and will attempt to complete it if it's an array of unknown
   // bound).
   if (ExprKind == UETT_AlignOf || ExprKind == UETT_PreferredAlignOf) {
     if (RequireCompleteSizedType(
             E->getExprLoc(), Context.getBaseElementType(E->getType()),
             diag::err_sizeof_alignof_incomplete_or_sizeless_type,
             getTraitSpelling(ExprKind), E->getSourceRange()))
       return true;
   } else {
     if (RequireCompleteSizedExprType(
             E, diag::err_sizeof_alignof_incomplete_or_sizeless_type,
             getTraitSpelling(ExprKind), E->getSourceRange()))
       return true;
   }
 
   // Completing the expression's type may have changed it.
   ExprTy = E->getType();
   assert(!ExprTy->isReferenceType());
 
   if (ExprTy->isFunctionType()) {
     Diag(E->getExprLoc(), diag::err_sizeof_alignof_function_type)
         << getTraitSpelling(ExprKind) << E->getSourceRange();
     return true;
   }
 
   if (CheckObjCTraitOperandConstraints(*this, ExprTy, E->getExprLoc(),
                                        E->getSourceRange(), ExprKind))
     return true;
 
   if (ExprKind == UETT_SizeOf) {
     if (const auto *DeclRef = dyn_cast<DeclRefExpr>(E->IgnoreParens())) {
       if (const auto *PVD = dyn_cast<ParmVarDecl>(DeclRef->getFoundDecl())) {
         QualType OType = PVD->getOriginalType();
         QualType Type = PVD->getType();
         if (Type->isPointerType() && OType->isArrayType()) {
           Diag(E->getExprLoc(), diag::warn_sizeof_array_param)
             << Type << OType;
           Diag(PVD->getLocation(), diag::note_declared_at);
         }
       }
     }
 
     // Warn on "sizeof(array op x)" and "sizeof(x op array)", where the array
     // decays into a pointer and returns an unintended result. This is most
     // likely a typo for "sizeof(array) op x".
     if (const auto *BO = dyn_cast<BinaryOperator>(E->IgnoreParens())) {
       warnOnSizeofOnArrayDecay(*this, BO->getOperatorLoc(), BO->getType(),
                                BO->getLHS());
       warnOnSizeofOnArrayDecay(*this, BO->getOperatorLoc(), BO->getType(),
                                BO->getRHS());
     }
   }
 
   return false;
 }
 
 static bool CheckAlignOfExpr(Sema &S, Expr *E, UnaryExprOrTypeTrait ExprKind) {
   // Cannot know anything else if the expression is dependent.
   if (E->isTypeDependent())
     return false;
 
   if (E->getObjectKind() == OK_BitField) {
     S.Diag(E->getExprLoc(), diag::err_sizeof_alignof_typeof_bitfield)
        << 1 << E->getSourceRange();
     return true;
   }
 
   ValueDecl *D = nullptr;
   Expr *Inner = E->IgnoreParens();
   if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Inner)) {
     D = DRE->getDecl();
   } else if (MemberExpr *ME = dyn_cast<MemberExpr>(Inner)) {
     D = ME->getMemberDecl();
   }
 
   // If it's a field, require the containing struct to have a
   // complete definition so that we can compute the layout.
   //
   // This can happen in C++11 onwards, either by naming the member
   // in a way that is not transformed into a member access expression
   // (in an unevaluated operand, for instance), or by naming the member
   // in a trailing-return-type.
   //
   // For the record, since __alignof__ on expressions is a GCC
   // extension, GCC seems to permit this but always gives the
   // nonsensical answer 0.
   //
   // We don't really need the layout here --- we could instead just
   // directly check for all the appropriate alignment-lowing
   // attributes --- but that would require duplicating a lot of
   // logic that just isn't worth duplicating for such a marginal
   // use-case.
   if (FieldDecl *FD = dyn_cast_or_null<FieldDecl>(D)) {
     // Fast path this check, since we at least know the record has a
     // definition if we can find a member of it.
     if (!FD->getParent()->isCompleteDefinition()) {
       S.Diag(E->getExprLoc(), diag::err_alignof_member_of_incomplete_type)
         << E->getSourceRange();
       return true;
     }
 
     // Otherwise, if it's a field, and the field doesn't have
     // reference type, then it must have a complete type (or be a
     // flexible array member, which we explicitly want to
     // white-list anyway), which makes the following checks trivial.
     if (!FD->getType()->isReferenceType())
       return false;
   }
 
   return S.CheckUnaryExprOrTypeTraitOperand(E, ExprKind);
 }
 
 bool Sema::CheckVecStepExpr(Expr *E) {
   E = E->IgnoreParens();
 
   // Cannot know anything else if the expression is dependent.
   if (E->isTypeDependent())
     return false;
 
   return CheckUnaryExprOrTypeTraitOperand(E, UETT_VecStep);
 }
 
 static void captureVariablyModifiedType(ASTContext &Context, QualType T,
                                         CapturingScopeInfo *CSI) {
   assert(T->isVariablyModifiedType());
   assert(CSI != nullptr);
 
   // We're going to walk down into the type and look for VLA expressions.
   do {
     const Type *Ty = T.getTypePtr();
     switch (Ty->getTypeClass()) {
 #define TYPE(Class, Base)
 #define ABSTRACT_TYPE(Class, Base)
 #define NON_CANONICAL_TYPE(Class, Base)
 #define DEPENDENT_TYPE(Class, Base) case Type::Class:
 #define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(Class, Base)
 #include "clang/AST/TypeNodes.inc"
       T = QualType();
       break;
     // These types are never variably-modified.
     case Type::Builtin:
     case Type::Complex:
     case Type::Vector:
     case Type::ExtVector:
     case Type::ConstantMatrix:
     case Type::Record:
     case Type::Enum:
     case Type::TemplateSpecialization:
     case Type::ObjCObject:
     case Type::ObjCInterface:
     case Type::ObjCObjectPointer:
     case Type::ObjCTypeParam:
     case Type::Pipe:
     case Type::BitInt:
       llvm_unreachable("type class is never variably-modified!");
     case Type::Elaborated:
       T = cast<ElaboratedType>(Ty)->getNamedType();
       break;
     case Type::Adjusted:
       T = cast<AdjustedType>(Ty)->getOriginalType();
       break;
     case Type::Decayed:
       T = cast<DecayedType>(Ty)->getPointeeType();
       break;
     case Type::Pointer:
       T = cast<PointerType>(Ty)->getPointeeType();
       break;
     case Type::BlockPointer:
       T = cast<BlockPointerType>(Ty)->getPointeeType();
       break;
     case Type::LValueReference:
     case Type::RValueReference:
       T = cast<ReferenceType>(Ty)->getPointeeType();
       break;
     case Type::MemberPointer:
       T = cast<MemberPointerType>(Ty)->getPointeeType();
       break;
     case Type::ConstantArray:
     case Type::IncompleteArray:
       // Losing element qualification here is fine.
       T = cast<ArrayType>(Ty)->getElementType();
       break;
     case Type::VariableArray: {
       // Losing element qualification here is fine.
       const VariableArrayType *VAT = cast<VariableArrayType>(Ty);
 
       // Unknown size indication requires no size computation.
       // Otherwise, evaluate and record it.
       auto Size = VAT->getSizeExpr();
       if (Size && !CSI->isVLATypeCaptured(VAT) &&
           (isa<CapturedRegionScopeInfo>(CSI) || isa<LambdaScopeInfo>(CSI)))
         CSI->addVLATypeCapture(Size->getExprLoc(), VAT, Context.getSizeType());
 
       T = VAT->getElementType();
       break;
     }
     case Type::FunctionProto:
     case Type::FunctionNoProto:
       T = cast<FunctionType>(Ty)->getReturnType();
       break;
     case Type::Paren:
     case Type::TypeOf:
     case Type::UnaryTransform:
     case Type::Attributed:
     case Type::BTFTagAttributed:
     case Type::SubstTemplateTypeParm:
     case Type::MacroQualified:
       // Keep walking after single level desugaring.
       T = T.getSingleStepDesugaredType(Context);
       break;
     case Type::Typedef:
       T = cast<TypedefType>(Ty)->desugar();
       break;
     case Type::Decltype:
       T = cast<DecltypeType>(Ty)->desugar();
       break;
     case Type::Using:
       T = cast<UsingType>(Ty)->desugar();
       break;
     case Type::Auto:
     case Type::DeducedTemplateSpecialization:
       T = cast<DeducedType>(Ty)->getDeducedType();
       break;
     case Type::TypeOfExpr:
       T = cast<TypeOfExprType>(Ty)->getUnderlyingExpr()->getType();
       break;
     case Type::Atomic:
       T = cast<AtomicType>(Ty)->getValueType();
       break;
     }
   } while (!T.isNull() && T->isVariablyModifiedType());
 }
 
 /// Check the constraints on operands to unary expression and type
 /// traits.
 ///
 /// This will complete any types necessary, and validate the various constraints
 /// on those operands.
 ///
 /// The UsualUnaryConversions() function is *not* called by this routine.
 /// C99 6.3.2.1p[2-4] all state:
 ///   Except when it is the operand of the sizeof operator ...
 ///
 /// C++ [expr.sizeof]p4
 ///   The lvalue-to-rvalue, array-to-pointer, and function-to-pointer
 ///   standard conversions are not applied to the operand of sizeof.
 ///
 /// This policy is followed for all of the unary trait expressions.
 bool Sema::CheckUnaryExprOrTypeTraitOperand(QualType ExprType,
                                             SourceLocation OpLoc,
                                             SourceRange ExprRange,
                                             UnaryExprOrTypeTrait ExprKind,
                                             StringRef KWName) {
   if (ExprType->isDependentType())
     return false;
 
   // C++ [expr.sizeof]p2:
   //     When applied to a reference or a reference type, the result
   //     is the size of the referenced type.
   // C++11 [expr.alignof]p3:
   //     When alignof is applied to a reference type, the result
   //     shall be the alignment of the referenced type.
   if (const ReferenceType *Ref = ExprType->getAs<ReferenceType>())
     ExprType = Ref->getPointeeType();
 
   // C11 6.5.3.4/3, C++11 [expr.alignof]p3:
   //   When alignof or _Alignof is applied to an array type, the result
   //   is the alignment of the element type.
   if (ExprKind == UETT_AlignOf || ExprKind == UETT_PreferredAlignOf ||
       ExprKind == UETT_OpenMPRequiredSimdAlign)
     ExprType = Context.getBaseElementType(ExprType);
 
   if (ExprKind == UETT_VecStep)
     return CheckVecStepTraitOperandType(*this, ExprType, OpLoc, ExprRange);
 
   // Explicitly list some types as extensions.
   if (!CheckExtensionTraitOperandType(*this, ExprType, OpLoc, ExprRange,
                                       ExprKind))
     return false;
 
   if (RequireCompleteSizedType(
           OpLoc, ExprType, diag::err_sizeof_alignof_incomplete_or_sizeless_type,
           KWName, ExprRange))
     return true;
 
   if (ExprType->isFunctionType()) {
     Diag(OpLoc, diag::err_sizeof_alignof_function_type) << KWName << ExprRange;
     return true;
   }
 
   // WebAssembly tables are always illegal operands to unary expressions and
   // type traits.
   if (Context.getTargetInfo().getTriple().isWasm() &&
       ExprType->isWebAssemblyTableType()) {
     Diag(OpLoc, diag::err_wasm_table_invalid_uett_operand)
         << getTraitSpelling(ExprKind);
     return true;
   }
 
   if (CheckObjCTraitOperandConstraints(*this, ExprType, OpLoc, ExprRange,
                                        ExprKind))
     return true;
 
   if (ExprType->isVariablyModifiedType() && FunctionScopes.size() > 1) {
     if (auto *TT = ExprType->getAs<TypedefType>()) {
       for (auto I = FunctionScopes.rbegin(),
                 E = std::prev(FunctionScopes.rend());
            I != E; ++I) {
         auto *CSI = dyn_cast<CapturingScopeInfo>(*I);
         if (CSI == nullptr)
           break;
         DeclContext *DC = nullptr;
         if (auto *LSI = dyn_cast<LambdaScopeInfo>(CSI))
           DC = LSI->CallOperator;
         else if (auto *CRSI = dyn_cast<CapturedRegionScopeInfo>(CSI))
           DC = CRSI->TheCapturedDecl;
         else if (auto *BSI = dyn_cast<BlockScopeInfo>(CSI))
           DC = BSI->TheDecl;
         if (DC) {
           if (DC->containsDecl(TT->getDecl()))
             break;
           captureVariablyModifiedType(Context, ExprType, CSI);
         }
       }
     }
   }
 
   return false;
 }
 
 /// Build a sizeof or alignof expression given a type operand.
 ExprResult Sema::CreateUnaryExprOrTypeTraitExpr(TypeSourceInfo *TInfo,
                                                 SourceLocation OpLoc,
                                                 UnaryExprOrTypeTrait ExprKind,
                                                 SourceRange R) {
   if (!TInfo)
     return ExprError();
 
   QualType T = TInfo->getType();
 
   if (!T->isDependentType() &&
       CheckUnaryExprOrTypeTraitOperand(T, OpLoc, R, ExprKind,
                                        getTraitSpelling(ExprKind)))
     return ExprError();
 
   // Adds overload of TransformToPotentiallyEvaluated for TypeSourceInfo to
   // properly deal with VLAs in nested calls of sizeof and typeof.
   if (isUnevaluatedContext() && ExprKind == UETT_SizeOf &&
       TInfo->getType()->isVariablyModifiedType())
     TInfo = TransformToPotentiallyEvaluated(TInfo);
 
   // C99 6.5.3.4p4: the type (an unsigned integer type) is size_t.
   return new (Context) UnaryExprOrTypeTraitExpr(
       ExprKind, TInfo, Context.getSizeType(), OpLoc, R.getEnd());
 }
 
 /// Build a sizeof or alignof expression given an expression
 /// operand.
 ExprResult
 Sema::CreateUnaryExprOrTypeTraitExpr(Expr *E, SourceLocation OpLoc,
                                      UnaryExprOrTypeTrait ExprKind) {
   ExprResult PE = CheckPlaceholderExpr(E);
   if (PE.isInvalid())
     return ExprError();
 
   E = PE.get();
 
   // Verify that the operand is valid.
   bool isInvalid = false;
   if (E->isTypeDependent()) {
     // Delay type-checking for type-dependent expressions.
   } else if (ExprKind == UETT_AlignOf || ExprKind == UETT_PreferredAlignOf) {
     isInvalid = CheckAlignOfExpr(*this, E, ExprKind);
   } else if (ExprKind == UETT_VecStep) {
     isInvalid = CheckVecStepExpr(E);
   } else if (ExprKind == UETT_OpenMPRequiredSimdAlign) {
       Diag(E->getExprLoc(), diag::err_openmp_default_simd_align_expr);
       isInvalid = true;
   } else if (E->refersToBitField()) {  // C99 6.5.3.4p1.
     Diag(E->getExprLoc(), diag::err_sizeof_alignof_typeof_bitfield) << 0;
     isInvalid = true;
   } else {
     isInvalid = CheckUnaryExprOrTypeTraitOperand(E, UETT_SizeOf);
   }
 
   if (isInvalid)
     return ExprError();
 
   if (ExprKind == UETT_SizeOf && E->getType()->isVariableArrayType()) {
     PE = TransformToPotentiallyEvaluated(E);
     if (PE.isInvalid()) return ExprError();
     E = PE.get();
   }
 
   // C99 6.5.3.4p4: the type (an unsigned integer type) is size_t.
   return new (Context) UnaryExprOrTypeTraitExpr(
       ExprKind, E, Context.getSizeType(), OpLoc, E->getSourceRange().getEnd());
 }
 
 /// ActOnUnaryExprOrTypeTraitExpr - Handle @c sizeof(type) and @c sizeof @c
 /// expr and the same for @c alignof and @c __alignof
 /// Note that the ArgRange is invalid if isType is false.
 ExprResult
 Sema::ActOnUnaryExprOrTypeTraitExpr(SourceLocation OpLoc,
                                     UnaryExprOrTypeTrait ExprKind, bool IsType,
                                     void *TyOrEx, SourceRange ArgRange) {
   // If error parsing type, ignore.
   if (!TyOrEx) return ExprError();
 
   if (IsType) {
     TypeSourceInfo *TInfo;
     (void) GetTypeFromParser(ParsedType::getFromOpaquePtr(TyOrEx), &TInfo);
     return CreateUnaryExprOrTypeTraitExpr(TInfo, OpLoc, ExprKind, ArgRange);
   }
 
   Expr *ArgEx = (Expr *)TyOrEx;
   ExprResult Result = CreateUnaryExprOrTypeTraitExpr(ArgEx, OpLoc, ExprKind);
   return Result;
 }
 
 bool Sema::CheckAlignasTypeArgument(StringRef KWName, TypeSourceInfo *TInfo,
                                     SourceLocation OpLoc, SourceRange R) {
   if (!TInfo)
     return true;
   return CheckUnaryExprOrTypeTraitOperand(TInfo->getType(), OpLoc, R,
                                           UETT_AlignOf, KWName);
 }
 
 /// ActOnAlignasTypeArgument - Handle @c alignas(type-id) and @c
 /// _Alignas(type-name) .
 /// [dcl.align] An alignment-specifier of the form
 /// alignas(type-id) has the same effect as alignas(alignof(type-id)).
 ///
 /// [N1570 6.7.5] _Alignas(type-name) is equivalent to
 /// _Alignas(_Alignof(type-name)).
 bool Sema::ActOnAlignasTypeArgument(StringRef KWName, ParsedType Ty,
                                     SourceLocation OpLoc, SourceRange R) {
   TypeSourceInfo *TInfo;
   (void)GetTypeFromParser(ParsedType::getFromOpaquePtr(Ty.getAsOpaquePtr()),
                           &TInfo);
   return CheckAlignasTypeArgument(KWName, TInfo, OpLoc, R);
 }
 
 static QualType CheckRealImagOperand(Sema &S, ExprResult &V, SourceLocation Loc,
                                      bool IsReal) {
   if (V.get()->isTypeDependent())
     return S.Context.DependentTy;
 
   // _Real and _Imag are only l-values for normal l-values.
   if (V.get()->getObjectKind() != OK_Ordinary) {
     V = S.DefaultLvalueConversion(V.get());
     if (V.isInvalid())
       return QualType();
   }
 
   // These operators return the element type of a complex type.
   if (const ComplexType *CT = V.get()->getType()->getAs<ComplexType>())
     return CT->getElementType();
 
   // Otherwise they pass through real integer and floating point types here.
   if (V.get()->getType()->isArithmeticType())
     return V.get()->getType();
 
   // Test for placeholders.
   ExprResult PR = S.CheckPlaceholderExpr(V.get());
   if (PR.isInvalid()) return QualType();
   if (PR.get() != V.get()) {
     V = PR;
     return CheckRealImagOperand(S, V, Loc, IsReal);
   }
 
   // Reject anything else.
   S.Diag(Loc, diag::err_realimag_invalid_type) << V.get()->getType()
     << (IsReal ? "__real" : "__imag");
   return QualType();
 }
 
 
 
 ExprResult
 Sema::ActOnPostfixUnaryOp(Scope *S, SourceLocation OpLoc,
                           tok::TokenKind Kind, Expr *Input) {
   UnaryOperatorKind Opc;
   switch (Kind) {
   default: llvm_unreachable("Unknown unary op!");
   case tok::plusplus:   Opc = UO_PostInc; break;
   case tok::minusminus: Opc = UO_PostDec; break;
   }
 
   // Since this might is a postfix expression, get rid of ParenListExprs.
   ExprResult Result = MaybeConvertParenListExprToParenExpr(S, Input);
   if (Result.isInvalid()) return ExprError();
   Input = Result.get();
 
   return BuildUnaryOp(S, OpLoc, Opc, Input);
 }
 
 /// Diagnose if arithmetic on the given ObjC pointer is illegal.
 ///
 /// \return true on error
 static bool checkArithmeticOnObjCPointer(Sema &S,
                                          SourceLocation opLoc,
                                          Expr *op) {
   assert(op->getType()->isObjCObjectPointerType());
   if (S.LangOpts.ObjCRuntime.allowsPointerArithmetic() &&
       !S.LangOpts.ObjCSubscriptingLegacyRuntime)
     return false;
 
   S.Diag(opLoc, diag::err_arithmetic_nonfragile_interface)
     << op->getType()->castAs<ObjCObjectPointerType>()->getPointeeType()
     << op->getSourceRange();
   return true;
 }
 
 static bool isMSPropertySubscriptExpr(Sema &S, Expr *Base) {
   auto *BaseNoParens = Base->IgnoreParens();
   if (auto *MSProp = dyn_cast<MSPropertyRefExpr>(BaseNoParens))
     return MSProp->getPropertyDecl()->getType()->isArrayType();
   return isa<MSPropertySubscriptExpr>(BaseNoParens);
 }
 
 // Returns the type used for LHS[RHS], given one of LHS, RHS is type-dependent.
 // Typically this is DependentTy, but can sometimes be more precise.
 //
 // There are cases when we could determine a non-dependent type:
 //  - LHS and RHS may have non-dependent types despite being type-dependent
 //    (e.g. unbounded array static members of the current instantiation)
 //  - one may be a dependent-sized array with known element type
 //  - one may be a dependent-typed valid index (enum in current instantiation)
 //
 // We *always* return a dependent type, in such cases it is DependentTy.
 // This avoids creating type-dependent expressions with non-dependent types.
 // FIXME: is this important to avoid? See https://reviews.llvm.org/D107275
 static QualType getDependentArraySubscriptType(Expr *LHS, Expr *RHS,
                                                const ASTContext &Ctx) {
   assert(LHS->isTypeDependent() || RHS->isTypeDependent());
   QualType LTy = LHS->getType(), RTy = RHS->getType();
   QualType Result = Ctx.DependentTy;
   if (RTy->isIntegralOrUnscopedEnumerationType()) {
     if (const PointerType *PT = LTy->getAs<PointerType>())
       Result = PT->getPointeeType();
     else if (const ArrayType *AT = LTy->getAsArrayTypeUnsafe())
       Result = AT->getElementType();
   } else if (LTy->isIntegralOrUnscopedEnumerationType()) {
     if (const PointerType *PT = RTy->getAs<PointerType>())
       Result = PT->getPointeeType();
     else if (const ArrayType *AT = RTy->getAsArrayTypeUnsafe())
       Result = AT->getElementType();
   }
   // Ensure we return a dependent type.
   return Result->isDependentType() ? Result : Ctx.DependentTy;
 }
 
 static bool checkArgsForPlaceholders(Sema &S, MultiExprArg args);
 
 ExprResult Sema::ActOnArraySubscriptExpr(Scope *S, Expr *base,
                                          SourceLocation lbLoc,
                                          MultiExprArg ArgExprs,
                                          SourceLocation rbLoc) {
 
   if (base && !base->getType().isNull() &&
       base->hasPlaceholderType(BuiltinType::OMPArraySection))
     return ActOnOMPArraySectionExpr(base, lbLoc, ArgExprs.front(), SourceLocation(),
                                     SourceLocation(), /*Length*/ nullptr,
                                     /*Stride=*/nullptr, rbLoc);
 
   // Since this might be a postfix expression, get rid of ParenListExprs.
   if (isa<ParenListExpr>(base)) {
     ExprResult result = MaybeConvertParenListExprToParenExpr(S, base);
     if (result.isInvalid())
       return ExprError();
     base = result.get();
   }
 
   // Check if base and idx form a MatrixSubscriptExpr.
   //
   // Helper to check for comma expressions, which are not allowed as indices for
   // matrix subscript expressions.
   auto CheckAndReportCommaError = [this, base, rbLoc](Expr *E) {
     if (isa<BinaryOperator>(E) && cast<BinaryOperator>(E)->isCommaOp()) {
       Diag(E->getExprLoc(), diag::err_matrix_subscript_comma)
           << SourceRange(base->getBeginLoc(), rbLoc);
       return true;
     }
     return false;
   };
   // The matrix subscript operator ([][])is considered a single operator.
   // Separating the index expressions by parenthesis is not allowed.
   if (base && !base->getType().isNull() &&
       base->hasPlaceholderType(BuiltinType::IncompleteMatrixIdx) &&
       !isa<MatrixSubscriptExpr>(base)) {
     Diag(base->getExprLoc(), diag::err_matrix_separate_incomplete_index)
         << SourceRange(base->getBeginLoc(), rbLoc);
     return ExprError();
   }
   // If the base is a MatrixSubscriptExpr, try to create a new
   // MatrixSubscriptExpr.
   auto *matSubscriptE = dyn_cast<MatrixSubscriptExpr>(base);
   if (matSubscriptE) {
     assert(ArgExprs.size() == 1);
     if (CheckAndReportCommaError(ArgExprs.front()))
       return ExprError();
 
     assert(matSubscriptE->isIncomplete() &&
            "base has to be an incomplete matrix subscript");
     return CreateBuiltinMatrixSubscriptExpr(matSubscriptE->getBase(),
                                             matSubscriptE->getRowIdx(),
                                             ArgExprs.front(), rbLoc);
   }
   if (base->getType()->isWebAssemblyTableType()) {
     Diag(base->getExprLoc(), diag::err_wasm_table_art)
         << SourceRange(base->getBeginLoc(), rbLoc) << 3;
     return ExprError();
   }
 
   // Handle any non-overload placeholder types in the base and index
   // expressions.  We can't handle overloads here because the other
   // operand might be an overloadable type, in which case the overload
   // resolution for the operator overload should get the first crack
   // at the overload.
   bool IsMSPropertySubscript = false;
   if (base->getType()->isNonOverloadPlaceholderType()) {
     IsMSPropertySubscript = isMSPropertySubscriptExpr(*this, base);
     if (!IsMSPropertySubscript) {
       ExprResult result = CheckPlaceholderExpr(base);
       if (result.isInvalid())
         return ExprError();
       base = result.get();
     }
   }
 
   // If the base is a matrix type, try to create a new MatrixSubscriptExpr.
   if (base->getType()->isMatrixType()) {
     assert(ArgExprs.size() == 1);
     if (CheckAndReportCommaError(ArgExprs.front()))
       return ExprError();
 
     return CreateBuiltinMatrixSubscriptExpr(base, ArgExprs.front(), nullptr,
                                             rbLoc);
   }
 
   if (ArgExprs.size() == 1 && getLangOpts().CPlusPlus20) {
     Expr *idx = ArgExprs[0];
     if ((isa<BinaryOperator>(idx) && cast<BinaryOperator>(idx)->isCommaOp()) ||
         (isa<CXXOperatorCallExpr>(idx) &&
          cast<CXXOperatorCallExpr>(idx)->getOperator() == OO_Comma)) {
       Diag(idx->getExprLoc(), diag::warn_deprecated_comma_subscript)
           << SourceRange(base->getBeginLoc(), rbLoc);
     }
   }
 
   if (ArgExprs.size() == 1 &&
       ArgExprs[0]->getType()->isNonOverloadPlaceholderType()) {
     ExprResult result = CheckPlaceholderExpr(ArgExprs[0]);
     if (result.isInvalid())
       return ExprError();
     ArgExprs[0] = result.get();
   } else {
     if (checkArgsForPlaceholders(*this, ArgExprs))
       return ExprError();
   }
 
   // Build an unanalyzed expression if either operand is type-dependent.
   if (getLangOpts().CPlusPlus && ArgExprs.size() == 1 &&
       (base->isTypeDependent() ||
        Expr::hasAnyTypeDependentArguments(ArgExprs)) &&
       !isa<PackExpansionExpr>(ArgExprs[0])) {
     return new (Context) ArraySubscriptExpr(
         base, ArgExprs.front(),
         getDependentArraySubscriptType(base, ArgExprs.front(), getASTContext()),
         VK_LValue, OK_Ordinary, rbLoc);
   }
 
   // MSDN, property (C++)
   // https://msdn.microsoft.com/en-us/library/yhfk0thd(v=vs.120).aspx
   // This attribute can also be used in the declaration of an empty array in a
   // class or structure definition. For example:
   // __declspec(property(get=GetX, put=PutX)) int x[];
   // The above statement indicates that x[] can be used with one or more array
   // indices. In this case, i=p->x[a][b] will be turned into i=p->GetX(a, b),
   // and p->x[a][b] = i will be turned into p->PutX(a, b, i);
   if (IsMSPropertySubscript) {
     assert(ArgExprs.size() == 1);
     // Build MS property subscript expression if base is MS property reference
     // or MS property subscript.
     return new (Context)
         MSPropertySubscriptExpr(base, ArgExprs.front(), Context.PseudoObjectTy,
                                 VK_LValue, OK_Ordinary, rbLoc);
   }
 
   // Use C++ overloaded-operator rules if either operand has record
   // type.  The spec says to do this if either type is *overloadable*,
   // but enum types can't declare subscript operators or conversion
   // operators, so there's nothing interesting for overload resolution
   // to do if there aren't any record types involved.
   //
   // ObjC pointers have their own subscripting logic that is not tied
   // to overload resolution and so should not take this path.
   if (getLangOpts().CPlusPlus && !base->getType()->isObjCObjectPointerType() &&
       ((base->getType()->isRecordType() ||
         (ArgExprs.size() != 1 || isa<PackExpansionExpr>(ArgExprs[0]) ||
          ArgExprs[0]->getType()->isRecordType())))) {
     return CreateOverloadedArraySubscriptExpr(lbLoc, rbLoc, base, ArgExprs);
   }
 
   ExprResult Res =
       CreateBuiltinArraySubscriptExpr(base, lbLoc, ArgExprs.front(), rbLoc);
 
   if (!Res.isInvalid() && isa<ArraySubscriptExpr>(Res.get()))
     CheckSubscriptAccessOfNoDeref(cast<ArraySubscriptExpr>(Res.get()));
 
   return Res;
 }
 
 ExprResult Sema::tryConvertExprToType(Expr *E, QualType Ty) {
   InitializedEntity Entity = InitializedEntity::InitializeTemporary(Ty);
   InitializationKind Kind =
       InitializationKind::CreateCopy(E->getBeginLoc(), SourceLocation());
   InitializationSequence InitSeq(*this, Entity, Kind, E);
   return InitSeq.Perform(*this, Entity, Kind, E);
 }
 
 ExprResult Sema::CreateBuiltinMatrixSubscriptExpr(Expr *Base, Expr *RowIdx,
                                                   Expr *ColumnIdx,
                                                   SourceLocation RBLoc) {
   ExprResult BaseR = CheckPlaceholderExpr(Base);
   if (BaseR.isInvalid())
     return BaseR;
   Base = BaseR.get();
 
   ExprResult RowR = CheckPlaceholderExpr(RowIdx);
   if (RowR.isInvalid())
     return RowR;
   RowIdx = RowR.get();
 
   if (!ColumnIdx)
     return new (Context) MatrixSubscriptExpr(
         Base, RowIdx, ColumnIdx, Context.IncompleteMatrixIdxTy, RBLoc);
 
   // Build an unanalyzed expression if any of the operands is type-dependent.
   if (Base->isTypeDependent() || RowIdx->isTypeDependent() ||
       ColumnIdx->isTypeDependent())
     return new (Context) MatrixSubscriptExpr(Base, RowIdx, ColumnIdx,
                                              Context.DependentTy, RBLoc);
 
   ExprResult ColumnR = CheckPlaceholderExpr(ColumnIdx);
   if (ColumnR.isInvalid())
     return ColumnR;
   ColumnIdx = ColumnR.get();
 
   // Check that IndexExpr is an integer expression. If it is a constant
   // expression, check that it is less than Dim (= the number of elements in the
   // corresponding dimension).
   auto IsIndexValid = [&](Expr *IndexExpr, unsigned Dim,
                           bool IsColumnIdx) -> Expr * {
     if (!IndexExpr->getType()->isIntegerType() &&
         !IndexExpr->isTypeDependent()) {
       Diag(IndexExpr->getBeginLoc(), diag::err_matrix_index_not_integer)
           << IsColumnIdx;
       return nullptr;
     }
 
     if (std::optional<llvm::APSInt> Idx =
             IndexExpr->getIntegerConstantExpr(Context)) {
       if ((*Idx < 0 || *Idx >= Dim)) {
         Diag(IndexExpr->getBeginLoc(), diag::err_matrix_index_outside_range)
             << IsColumnIdx << Dim;
         return nullptr;
       }
     }
 
     ExprResult ConvExpr =
         tryConvertExprToType(IndexExpr, Context.getSizeType());
     assert(!ConvExpr.isInvalid() &&
            "should be able to convert any integer type to size type");
     return ConvExpr.get();
   };
 
   auto *MTy = Base->getType()->getAs<ConstantMatrixType>();
   RowIdx = IsIndexValid(RowIdx, MTy->getNumRows(), false);
   ColumnIdx = IsIndexValid(ColumnIdx, MTy->getNumColumns(), true);
   if (!RowIdx || !ColumnIdx)
     return ExprError();
 
   return new (Context) MatrixSubscriptExpr(Base, RowIdx, ColumnIdx,
                                            MTy->getElementType(), RBLoc);
 }
 
 void Sema::CheckAddressOfNoDeref(const Expr *E) {
   ExpressionEvaluationContextRecord &LastRecord = ExprEvalContexts.back();
   const Expr *StrippedExpr = E->IgnoreParenImpCasts();
 
   // For expressions like `&(*s).b`, the base is recorded and what should be
   // checked.
   const MemberExpr *Member = nullptr;
   while ((Member = dyn_cast<MemberExpr>(StrippedExpr)) && !Member->isArrow())
     StrippedExpr = Member->getBase()->IgnoreParenImpCasts();
 
   LastRecord.PossibleDerefs.erase(StrippedExpr);
 }
 
 void Sema::CheckSubscriptAccessOfNoDeref(const ArraySubscriptExpr *E) {
   if (isUnevaluatedContext())
     return;
 
   QualType ResultTy = E->getType();
   ExpressionEvaluationContextRecord &LastRecord = ExprEvalContexts.back();
 
   // Bail if the element is an array since it is not memory access.
   if (isa<ArrayType>(ResultTy))
     return;
 
   if (ResultTy->hasAttr(attr::NoDeref)) {
     LastRecord.PossibleDerefs.insert(E);
     return;
   }
 
   // Check if the base type is a pointer to a member access of a struct
   // marked with noderef.
   const Expr *Base = E->getBase();
   QualType BaseTy = Base->getType();
   if (!(isa<ArrayType>(BaseTy) || isa<PointerType>(BaseTy)))
     // Not a pointer access
     return;
 
   const MemberExpr *Member = nullptr;
   while ((Member = dyn_cast<MemberExpr>(Base->IgnoreParenCasts())) &&
          Member->isArrow())
     Base = Member->getBase();
 
   if (const auto *Ptr = dyn_cast<PointerType>(Base->getType())) {
     if (Ptr->getPointeeType()->hasAttr(attr::NoDeref))
       LastRecord.PossibleDerefs.insert(E);
   }
 }
 
 ExprResult Sema::ActOnOMPArraySectionExpr(Expr *Base, SourceLocation LBLoc,
                                           Expr *LowerBound,
                                           SourceLocation ColonLocFirst,
                                           SourceLocation ColonLocSecond,
                                           Expr *Length, Expr *Stride,
                                           SourceLocation RBLoc) {
   if (Base->hasPlaceholderType() &&
       !Base->hasPlaceholderType(BuiltinType::OMPArraySection)) {
     ExprResult Result = CheckPlaceholderExpr(Base);
     if (Result.isInvalid())
       return ExprError();
     Base = Result.get();
   }
   if (LowerBound && LowerBound->getType()->isNonOverloadPlaceholderType()) {
     ExprResult Result = CheckPlaceholderExpr(LowerBound);
     if (Result.isInvalid())
       return ExprError();
     Result = DefaultLvalueConversion(Result.get());
     if (Result.isInvalid())
       return ExprError();
     LowerBound = Result.get();
   }
   if (Length && Length->getType()->isNonOverloadPlaceholderType()) {
     ExprResult Result = CheckPlaceholderExpr(Length);
     if (Result.isInvalid())
       return ExprError();
     Result = DefaultLvalueConversion(Result.get());
     if (Result.isInvalid())
       return ExprError();
     Length = Result.get();
   }
   if (Stride && Stride->getType()->isNonOverloadPlaceholderType()) {
     ExprResult Result = CheckPlaceholderExpr(Stride);
     if (Result.isInvalid())
       return ExprError();
     Result = DefaultLvalueConversion(Result.get());
     if (Result.isInvalid())
       return ExprError();
     Stride = Result.get();
   }
 
   // Build an unanalyzed expression if either operand is type-dependent.
   if (Base->isTypeDependent() ||
       (LowerBound &&
        (LowerBound->isTypeDependent() || LowerBound->isValueDependent())) ||
       (Length && (Length->isTypeDependent() || Length->isValueDependent())) ||
       (Stride && (Stride->isTypeDependent() || Stride->isValueDependent()))) {
     return new (Context) OMPArraySectionExpr(
         Base, LowerBound, Length, Stride, Context.DependentTy, VK_LValue,
         OK_Ordinary, ColonLocFirst, ColonLocSecond, RBLoc);
   }
 
   // Perform default conversions.
   QualType OriginalTy = OMPArraySectionExpr::getBaseOriginalType(Base);
   QualType ResultTy;
   if (OriginalTy->isAnyPointerType()) {
     ResultTy = OriginalTy->getPointeeType();
   } else if (OriginalTy->isArrayType()) {
     ResultTy = OriginalTy->getAsArrayTypeUnsafe()->getElementType();
   } else {
     return ExprError(
         Diag(Base->getExprLoc(), diag::err_omp_typecheck_section_value)
         << Base->getSourceRange());
   }
   // C99 6.5.2.1p1
   if (LowerBound) {
     auto Res = PerformOpenMPImplicitIntegerConversion(LowerBound->getExprLoc(),
                                                       LowerBound);
     if (Res.isInvalid())
       return ExprError(Diag(LowerBound->getExprLoc(),
                             diag::err_omp_typecheck_section_not_integer)
                        << 0 << LowerBound->getSourceRange());
     LowerBound = Res.get();
 
     if (LowerBound->getType()->isSpecificBuiltinType(BuiltinType::Char_S) ||
         LowerBound->getType()->isSpecificBuiltinType(BuiltinType::Char_U))
       Diag(LowerBound->getExprLoc(), diag::warn_omp_section_is_char)
           << 0 << LowerBound->getSourceRange();
   }
   if (Length) {
     auto Res =
         PerformOpenMPImplicitIntegerConversion(Length->getExprLoc(), Length);
     if (Res.isInvalid())
       return ExprError(Diag(Length->getExprLoc(),
                             diag::err_omp_typecheck_section_not_integer)
                        << 1 << Length->getSourceRange());
     Length = Res.get();
 
     if (Length->getType()->isSpecificBuiltinType(BuiltinType::Char_S) ||
         Length->getType()->isSpecificBuiltinType(BuiltinType::Char_U))
       Diag(Length->getExprLoc(), diag::warn_omp_section_is_char)
           << 1 << Length->getSourceRange();
   }
   if (Stride) {
     ExprResult Res =
         PerformOpenMPImplicitIntegerConversion(Stride->getExprLoc(), Stride);
     if (Res.isInvalid())
       return ExprError(Diag(Stride->getExprLoc(),
                             diag::err_omp_typecheck_section_not_integer)
                        << 1 << Stride->getSourceRange());
     Stride = Res.get();
 
     if (Stride->getType()->isSpecificBuiltinType(BuiltinType::Char_S) ||
         Stride->getType()->isSpecificBuiltinType(BuiltinType::Char_U))
       Diag(Stride->getExprLoc(), diag::warn_omp_section_is_char)
           << 1 << Stride->getSourceRange();
   }
 
   // C99 6.5.2.1p1: "shall have type "pointer to *object* type". Similarly,
   // C++ [expr.sub]p1: The type "T" shall be a completely-defined object
   // type. Note that functions are not objects, and that (in C99 parlance)
   // incomplete types are not object types.
   if (ResultTy->isFunctionType()) {
     Diag(Base->getExprLoc(), diag::err_omp_section_function_type)
         << ResultTy << Base->getSourceRange();
     return ExprError();
   }
 
   if (RequireCompleteType(Base->getExprLoc(), ResultTy,
                           diag::err_omp_section_incomplete_type, Base))
     return ExprError();
 
   if (LowerBound && !OriginalTy->isAnyPointerType()) {
     Expr::EvalResult Result;
     if (LowerBound->EvaluateAsInt(Result, Context)) {
       // OpenMP 5.0, [2.1.5 Array Sections]
       // The array section must be a subset of the original array.
       llvm::APSInt LowerBoundValue = Result.Val.getInt();
       if (LowerBoundValue.isNegative()) {
         Diag(LowerBound->getExprLoc(), diag::err_omp_section_not_subset_of_array)
             << LowerBound->getSourceRange();
         return ExprError();
       }
     }
   }
 
   if (Length) {
     Expr::EvalResult Result;
     if (Length->EvaluateAsInt(Result, Context)) {
       // OpenMP 5.0, [2.1.5 Array Sections]
       // The length must evaluate to non-negative integers.
       llvm::APSInt LengthValue = Result.Val.getInt();
       if (LengthValue.isNegative()) {
         Diag(Length->getExprLoc(), diag::err_omp_section_length_negative)
             << toString(LengthValue, /*Radix=*/10, /*Signed=*/true)
             << Length->getSourceRange();
         return ExprError();
       }
     }
   } else if (ColonLocFirst.isValid() &&
              (OriginalTy.isNull() || (!OriginalTy->isConstantArrayType() &&
                                       !OriginalTy->isVariableArrayType()))) {
     // OpenMP 5.0, [2.1.5 Array Sections]
     // When the size of the array dimension is not known, the length must be
     // specified explicitly.
     Diag(ColonLocFirst, diag::err_omp_section_length_undefined)
         << (!OriginalTy.isNull() && OriginalTy->isArrayType());
     return ExprError();
   }
 
   if (Stride) {
     Expr::EvalResult Result;
     if (Stride->EvaluateAsInt(Result, Context)) {
       // OpenMP 5.0, [2.1.5 Array Sections]
       // The stride must evaluate to a positive integer.
       llvm::APSInt StrideValue = Result.Val.getInt();
       if (!StrideValue.isStrictlyPositive()) {
         Diag(Stride->getExprLoc(), diag::err_omp_section_stride_non_positive)
             << toString(StrideValue, /*Radix=*/10, /*Signed=*/true)
             << Stride->getSourceRange();
         return ExprError();
       }
     }
   }
 
   if (!Base->hasPlaceholderType(BuiltinType::OMPArraySection)) {
     ExprResult Result = DefaultFunctionArrayLvalueConversion(Base);
     if (Result.isInvalid())
       return ExprError();
     Base = Result.get();
   }
   return new (Context) OMPArraySectionExpr(
       Base, LowerBound, Length, Stride, Context.OMPArraySectionTy, VK_LValue,
       OK_Ordinary, ColonLocFirst, ColonLocSecond, RBLoc);
 }
 
 ExprResult Sema::ActOnOMPArrayShapingExpr(Expr *Base, SourceLocation LParenLoc,
                                           SourceLocation RParenLoc,
                                           ArrayRef<Expr *> Dims,
                                           ArrayRef<SourceRange> Brackets) {
   if (Base->hasPlaceholderType()) {
     ExprResult Result = CheckPlaceholderExpr(Base);
     if (Result.isInvalid())
       return ExprError();
     Result = DefaultLvalueConversion(Result.get());
     if (Result.isInvalid())
       return ExprError();
     Base = Result.get();
   }
   QualType BaseTy = Base->getType();
   // Delay analysis of the types/expressions if instantiation/specialization is
   // required.
   if (!BaseTy->isPointerType() && Base->isTypeDependent())
     return OMPArrayShapingExpr::Create(Context, Context.DependentTy, Base,
                                        LParenLoc, RParenLoc, Dims, Brackets);
   if (!BaseTy->isPointerType() ||
       (!Base->isTypeDependent() &&
        BaseTy->getPointeeType()->isIncompleteType()))
     return ExprError(Diag(Base->getExprLoc(),
                           diag::err_omp_non_pointer_type_array_shaping_base)
                      << Base->getSourceRange());
 
   SmallVector<Expr *, 4> NewDims;
   bool ErrorFound = false;
   for (Expr *Dim : Dims) {
     if (Dim->hasPlaceholderType()) {
       ExprResult Result = CheckPlaceholderExpr(Dim);
       if (Result.isInvalid()) {
         ErrorFound = true;
         continue;
       }
       Result = DefaultLvalueConversion(Result.get());
       if (Result.isInvalid()) {
         ErrorFound = true;
         continue;
       }
       Dim = Result.get();
     }
     if (!Dim->isTypeDependent()) {
       ExprResult Result =
           PerformOpenMPImplicitIntegerConversion(Dim->getExprLoc(), Dim);
       if (Result.isInvalid()) {
         ErrorFound = true;
         Diag(Dim->getExprLoc(), diag::err_omp_typecheck_shaping_not_integer)
             << Dim->getSourceRange();
         continue;
       }
       Dim = Result.get();
       Expr::EvalResult EvResult;
       if (!Dim->isValueDependent() && Dim->EvaluateAsInt(EvResult, Context)) {
         // OpenMP 5.0, [2.1.4 Array Shaping]
         // Each si is an integral type expression that must evaluate to a
         // positive integer.
         llvm::APSInt Value = EvResult.Val.getInt();
         if (!Value.isStrictlyPositive()) {
           Diag(Dim->getExprLoc(), diag::err_omp_shaping_dimension_not_positive)
               << toString(Value, /*Radix=*/10, /*Signed=*/true)
               << Dim->getSourceRange();
           ErrorFound = true;
           continue;
         }
       }
     }
     NewDims.push_back(Dim);
   }
   if (ErrorFound)
     return ExprError();
   return OMPArrayShapingExpr::Create(Context, Context.OMPArrayShapingTy, Base,
                                      LParenLoc, RParenLoc, NewDims, Brackets);
 }
 
 ExprResult Sema::ActOnOMPIteratorExpr(Scope *S, SourceLocation IteratorKwLoc,
                                       SourceLocation LLoc, SourceLocation RLoc,
                                       ArrayRef<OMPIteratorData> Data) {
   SmallVector<OMPIteratorExpr::IteratorDefinition, 4> ID;
   bool IsCorrect = true;
   for (const OMPIteratorData &D : Data) {
     TypeSourceInfo *TInfo = nullptr;
     SourceLocation StartLoc;
     QualType DeclTy;
     if (!D.Type.getAsOpaquePtr()) {
       // OpenMP 5.0, 2.1.6 Iterators
       // In an iterator-specifier, if the iterator-type is not specified then
       // the type of that iterator is of int type.
       DeclTy = Context.IntTy;
       StartLoc = D.DeclIdentLoc;
     } else {
       DeclTy = GetTypeFromParser(D.Type, &TInfo);
       StartLoc = TInfo->getTypeLoc().getBeginLoc();
     }
 
     bool IsDeclTyDependent = DeclTy->isDependentType() ||
                              DeclTy->containsUnexpandedParameterPack() ||
                              DeclTy->isInstantiationDependentType();
     if (!IsDeclTyDependent) {
       if (!DeclTy->isIntegralType(Context) && !DeclTy->isAnyPointerType()) {
         // OpenMP 5.0, 2.1.6 Iterators, Restrictions, C/C++
         // The iterator-type must be an integral or pointer type.
         Diag(StartLoc, diag::err_omp_iterator_not_integral_or_pointer)
             << DeclTy;
         IsCorrect = false;
         continue;
       }
       if (DeclTy.isConstant(Context)) {
         // OpenMP 5.0, 2.1.6 Iterators, Restrictions, C/C++
         // The iterator-type must not be const qualified.
         Diag(StartLoc, diag::err_omp_iterator_not_integral_or_pointer)
             << DeclTy;
         IsCorrect = false;
         continue;
       }
     }
 
     // Iterator declaration.
     assert(D.DeclIdent && "Identifier expected.");
     // Always try to create iterator declarator to avoid extra error messages
     // about unknown declarations use.
     auto *VD = VarDecl::Create(Context, CurContext, StartLoc, D.DeclIdentLoc,
                                D.DeclIdent, DeclTy, TInfo, SC_None);
     VD->setImplicit();
     if (S) {
       // Check for conflicting previous declaration.
       DeclarationNameInfo NameInfo(VD->getDeclName(), D.DeclIdentLoc);
       LookupResult Previous(*this, NameInfo, LookupOrdinaryName,
                             ForVisibleRedeclaration);
       Previous.suppressDiagnostics();
       LookupName(Previous, S);
 
       FilterLookupForScope(Previous, CurContext, S, /*ConsiderLinkage=*/false,
                            /*AllowInlineNamespace=*/false);
       if (!Previous.empty()) {
         NamedDecl *Old = Previous.getRepresentativeDecl();
         Diag(D.DeclIdentLoc, diag::err_redefinition) << VD->getDeclName();
         Diag(Old->getLocation(), diag::note_previous_definition);
       } else {
         PushOnScopeChains(VD, S);
       }
     } else {
       CurContext->addDecl(VD);
     }
 
     /// Act on the iterator variable declaration.
     ActOnOpenMPIteratorVarDecl(VD);
 
     Expr *Begin = D.Range.Begin;
     if (!IsDeclTyDependent && Begin && !Begin->isTypeDependent()) {
       ExprResult BeginRes =
           PerformImplicitConversion(Begin, DeclTy, AA_Converting);
       Begin = BeginRes.get();
     }
     Expr *End = D.Range.End;
     if (!IsDeclTyDependent && End && !End->isTypeDependent()) {
       ExprResult EndRes = PerformImplicitConversion(End, DeclTy, AA_Converting);
       End = EndRes.get();
     }
     Expr *Step = D.Range.Step;
     if (!IsDeclTyDependent && Step && !Step->isTypeDependent()) {
       if (!Step->getType()->isIntegralType(Context)) {
         Diag(Step->getExprLoc(), diag::err_omp_iterator_step_not_integral)
             << Step << Step->getSourceRange();
         IsCorrect = false;
         continue;
       }
       std::optional<llvm::APSInt> Result =
           Step->getIntegerConstantExpr(Context);
       // OpenMP 5.0, 2.1.6 Iterators, Restrictions
       // If the step expression of a range-specification equals zero, the
       // behavior is unspecified.
       if (Result && Result->isZero()) {
         Diag(Step->getExprLoc(), diag::err_omp_iterator_step_constant_zero)
             << Step << Step->getSourceRange();
         IsCorrect = false;
         continue;
       }
     }
     if (!Begin || !End || !IsCorrect) {
       IsCorrect = false;
       continue;
     }
     OMPIteratorExpr::IteratorDefinition &IDElem = ID.emplace_back();
     IDElem.IteratorDecl = VD;
     IDElem.AssignmentLoc = D.AssignLoc;
     IDElem.Range.Begin = Begin;
     IDElem.Range.End = End;
     IDElem.Range.Step = Step;
     IDElem.ColonLoc = D.ColonLoc;
     IDElem.SecondColonLoc = D.SecColonLoc;
   }
   if (!IsCorrect) {
     // Invalidate all created iterator declarations if error is found.
     for (const OMPIteratorExpr::IteratorDefinition &D : ID) {
       if (Decl *ID = D.IteratorDecl)
         ID->setInvalidDecl();
     }
     return ExprError();
   }
   SmallVector<OMPIteratorHelperData, 4> Helpers;
   if (!CurContext->isDependentContext()) {
     // Build number of ityeration for each iteration range.
     // Ni = ((Stepi > 0) ? ((Endi + Stepi -1 - Begini)/Stepi) :
     // ((Begini-Stepi-1-Endi) / -Stepi);
     for (OMPIteratorExpr::IteratorDefinition &D : ID) {
       // (Endi - Begini)
       ExprResult Res = CreateBuiltinBinOp(D.AssignmentLoc, BO_Sub, D.Range.End,
                                           D.Range.Begin);
       if(!Res.isUsable()) {
         IsCorrect = false;
         continue;
       }
       ExprResult St, St1;
       if (D.Range.Step) {
         St = D.Range.Step;
         // (Endi - Begini) + Stepi
         Res = CreateBuiltinBinOp(D.AssignmentLoc, BO_Add, Res.get(), St.get());
         if (!Res.isUsable()) {
           IsCorrect = false;
           continue;
         }
         // (Endi - Begini) + Stepi - 1
         Res =
             CreateBuiltinBinOp(D.AssignmentLoc, BO_Sub, Res.get(),
                                ActOnIntegerConstant(D.AssignmentLoc, 1).get());
         if (!Res.isUsable()) {
           IsCorrect = false;
           continue;
         }
         // ((Endi - Begini) + Stepi - 1) / Stepi
         Res = CreateBuiltinBinOp(D.AssignmentLoc, BO_Div, Res.get(), St.get());
         if (!Res.isUsable()) {
           IsCorrect = false;
           continue;
         }
         St1 = CreateBuiltinUnaryOp(D.AssignmentLoc, UO_Minus, D.Range.Step);
         // (Begini - Endi)
         ExprResult Res1 = CreateBuiltinBinOp(D.AssignmentLoc, BO_Sub,
                                              D.Range.Begin, D.Range.End);
         if (!Res1.isUsable()) {
           IsCorrect = false;
           continue;
         }
         // (Begini - Endi) - Stepi
         Res1 =
             CreateBuiltinBinOp(D.AssignmentLoc, BO_Add, Res1.get(), St1.get());
         if (!Res1.isUsable()) {
           IsCorrect = false;
           continue;
         }
         // (Begini - Endi) - Stepi - 1
         Res1 =
             CreateBuiltinBinOp(D.AssignmentLoc, BO_Sub, Res1.get(),
                                ActOnIntegerConstant(D.AssignmentLoc, 1).get());
         if (!Res1.isUsable()) {
           IsCorrect = false;
           continue;
         }
         // ((Begini - Endi) - Stepi - 1) / (-Stepi)
         Res1 =
             CreateBuiltinBinOp(D.AssignmentLoc, BO_Div, Res1.get(), St1.get());
         if (!Res1.isUsable()) {
           IsCorrect = false;
           continue;
         }
         // Stepi > 0.
         ExprResult CmpRes =
             CreateBuiltinBinOp(D.AssignmentLoc, BO_GT, D.Range.Step,
                                ActOnIntegerConstant(D.AssignmentLoc, 0).get());
         if (!CmpRes.isUsable()) {
           IsCorrect = false;
           continue;
         }
         Res = ActOnConditionalOp(D.AssignmentLoc, D.AssignmentLoc, CmpRes.get(),
                                  Res.get(), Res1.get());
         if (!Res.isUsable()) {
           IsCorrect = false;
           continue;
         }
       }
       Res = ActOnFinishFullExpr(Res.get(), /*DiscardedValue=*/false);
       if (!Res.isUsable()) {
         IsCorrect = false;
         continue;
       }
 
       // Build counter update.
       // Build counter.
       auto *CounterVD =
           VarDecl::Create(Context, CurContext, D.IteratorDecl->getBeginLoc(),
                           D.IteratorDecl->getBeginLoc(), nullptr,
                           Res.get()->getType(), nullptr, SC_None);
       CounterVD->setImplicit();
       ExprResult RefRes =
           BuildDeclRefExpr(CounterVD, CounterVD->getType(), VK_LValue,
                            D.IteratorDecl->getBeginLoc());
       // Build counter update.
       // I = Begini + counter * Stepi;
       ExprResult UpdateRes;
       if (D.Range.Step) {
         UpdateRes = CreateBuiltinBinOp(
             D.AssignmentLoc, BO_Mul,
             DefaultLvalueConversion(RefRes.get()).get(), St.get());
       } else {
         UpdateRes = DefaultLvalueConversion(RefRes.get());
       }
       if (!UpdateRes.isUsable()) {
         IsCorrect = false;
         continue;
       }
       UpdateRes = CreateBuiltinBinOp(D.AssignmentLoc, BO_Add, D.Range.Begin,
                                      UpdateRes.get());
       if (!UpdateRes.isUsable()) {
         IsCorrect = false;
         continue;
       }
       ExprResult VDRes =
           BuildDeclRefExpr(cast<VarDecl>(D.IteratorDecl),
                            cast<VarDecl>(D.IteratorDecl)->getType(), VK_LValue,
                            D.IteratorDecl->getBeginLoc());
       UpdateRes = CreateBuiltinBinOp(D.AssignmentLoc, BO_Assign, VDRes.get(),
                                      UpdateRes.get());
       if (!UpdateRes.isUsable()) {
         IsCorrect = false;
         continue;
       }
       UpdateRes =
           ActOnFinishFullExpr(UpdateRes.get(), /*DiscardedValue=*/true);
       if (!UpdateRes.isUsable()) {
         IsCorrect = false;
         continue;
       }
       ExprResult CounterUpdateRes =
           CreateBuiltinUnaryOp(D.AssignmentLoc, UO_PreInc, RefRes.get());
       if (!CounterUpdateRes.isUsable()) {
         IsCorrect = false;
         continue;
       }
       CounterUpdateRes =
           ActOnFinishFullExpr(CounterUpdateRes.get(), /*DiscardedValue=*/true);
       if (!CounterUpdateRes.isUsable()) {
         IsCorrect = false;
         continue;
       }
       OMPIteratorHelperData &HD = Helpers.emplace_back();
       HD.CounterVD = CounterVD;
       HD.Upper = Res.get();
       HD.Update = UpdateRes.get();
       HD.CounterUpdate = CounterUpdateRes.get();
     }
   } else {
     Helpers.assign(ID.size(), {});
   }
   if (!IsCorrect) {
     // Invalidate all created iterator declarations if error is found.
     for (const OMPIteratorExpr::IteratorDefinition &D : ID) {
       if (Decl *ID = D.IteratorDecl)
         ID->setInvalidDecl();
     }
     return ExprError();
   }
   return OMPIteratorExpr::Create(Context, Context.OMPIteratorTy, IteratorKwLoc,
                                  LLoc, RLoc, ID, Helpers);
 }
 
 ExprResult
 Sema::CreateBuiltinArraySubscriptExpr(Expr *Base, SourceLocation LLoc,
                                       Expr *Idx, SourceLocation RLoc) {
   Expr *LHSExp = Base;
   Expr *RHSExp = Idx;
 
   ExprValueKind VK = VK_LValue;
   ExprObjectKind OK = OK_Ordinary;
 
   // Per C++ core issue 1213, the result is an xvalue if either operand is
   // a non-lvalue array, and an lvalue otherwise.
   if (getLangOpts().CPlusPlus11) {
     for (auto *Op : {LHSExp, RHSExp}) {
       Op = Op->IgnoreImplicit();
       if (Op->getType()->isArrayType() && !Op->isLValue())
         VK = VK_XValue;
     }
   }
 
   // Perform default conversions.
   if (!LHSExp->getType()->getAs<VectorType>()) {
     ExprResult Result = DefaultFunctionArrayLvalueConversion(LHSExp);
     if (Result.isInvalid())
       return ExprError();
     LHSExp = Result.get();
   }
   ExprResult Result = DefaultFunctionArrayLvalueConversion(RHSExp);
   if (Result.isInvalid())
     return ExprError();
   RHSExp = Result.get();
 
   QualType LHSTy = LHSExp->getType(), RHSTy = RHSExp->getType();
 
   // C99 6.5.2.1p2: the expression e1[e2] is by definition precisely equivalent
   // to the expression *((e1)+(e2)). This means the array "Base" may actually be
   // in the subscript position. As a result, we need to derive the array base
   // and index from the expression types.
   Expr *BaseExpr, *IndexExpr;
   QualType ResultType;
   if (LHSTy->isDependentType() || RHSTy->isDependentType()) {
     BaseExpr = LHSExp;
     IndexExpr = RHSExp;
     ResultType =
         getDependentArraySubscriptType(LHSExp, RHSExp, getASTContext());
   } else if (const PointerType *PTy = LHSTy->getAs<PointerType>()) {
     BaseExpr = LHSExp;
     IndexExpr = RHSExp;
     ResultType = PTy->getPointeeType();
   } else if (const ObjCObjectPointerType *PTy =
                LHSTy->getAs<ObjCObjectPointerType>()) {
     BaseExpr = LHSExp;
     IndexExpr = RHSExp;
 
     // Use custom logic if this should be the pseudo-object subscript
     // expression.
     if (!LangOpts.isSubscriptPointerArithmetic())
       return BuildObjCSubscriptExpression(RLoc, BaseExpr, IndexExpr, nullptr,
                                           nullptr);
 
     ResultType = PTy->getPointeeType();
   } else if (const PointerType *PTy = RHSTy->getAs<PointerType>()) {
      // Handle the uncommon case of "123[Ptr]".
     BaseExpr = RHSExp;
     IndexExpr = LHSExp;
     ResultType = PTy->getPointeeType();
   } else if (const ObjCObjectPointerType *PTy =
                RHSTy->getAs<ObjCObjectPointerType>()) {
      // Handle the uncommon case of "123[Ptr]".
     BaseExpr = RHSExp;
     IndexExpr = LHSExp;
     ResultType = PTy->getPointeeType();
     if (!LangOpts.isSubscriptPointerArithmetic()) {
       Diag(LLoc, diag::err_subscript_nonfragile_interface)
         << ResultType << BaseExpr->getSourceRange();
       return ExprError();
     }
   } else if (const VectorType *VTy = LHSTy->getAs<VectorType>()) {
     BaseExpr = LHSExp;    // vectors: V[123]
     IndexExpr = RHSExp;
     // We apply C++ DR1213 to vector subscripting too.
     if (getLangOpts().CPlusPlus11 && LHSExp->isPRValue()) {
       ExprResult Materialized = TemporaryMaterializationConversion(LHSExp);
       if (Materialized.isInvalid())
         return ExprError();
       LHSExp = Materialized.get();
     }
     VK = LHSExp->getValueKind();
     if (VK != VK_PRValue)
       OK = OK_VectorComponent;
 
     ResultType = VTy->getElementType();
     QualType BaseType = BaseExpr->getType();
     Qualifiers BaseQuals = BaseType.getQualifiers();
     Qualifiers MemberQuals = ResultType.getQualifiers();
     Qualifiers Combined = BaseQuals + MemberQuals;
     if (Combined != MemberQuals)
       ResultType = Context.getQualifiedType(ResultType, Combined);
   } else if (LHSTy->isBuiltinType() &&
              LHSTy->getAs<BuiltinType>()->isVLSTBuiltinType()) {
     const BuiltinType *BTy = LHSTy->getAs<BuiltinType>();
     if (BTy->isSVEBool())
       return ExprError(Diag(LLoc, diag::err_subscript_svbool_t)
                        << LHSExp->getSourceRange() << RHSExp->getSourceRange());
 
     BaseExpr = LHSExp;
     IndexExpr = RHSExp;
     if (getLangOpts().CPlusPlus11 && LHSExp->isPRValue()) {
       ExprResult Materialized = TemporaryMaterializationConversion(LHSExp);
       if (Materialized.isInvalid())
         return ExprError();
       LHSExp = Materialized.get();
     }
     VK = LHSExp->getValueKind();
     if (VK != VK_PRValue)
       OK = OK_VectorComponent;
 
     ResultType = BTy->getSveEltType(Context);
 
     QualType BaseType = BaseExpr->getType();
     Qualifiers BaseQuals = BaseType.getQualifiers();
     Qualifiers MemberQuals = ResultType.getQualifiers();
     Qualifiers Combined = BaseQuals + MemberQuals;
     if (Combined != MemberQuals)
       ResultType = Context.getQualifiedType(ResultType, Combined);
   } else if (LHSTy->isArrayType()) {
     // If we see an array that wasn't promoted by
     // DefaultFunctionArrayLvalueConversion, it must be an array that
     // wasn't promoted because of the C90 rule that doesn't
     // allow promoting non-lvalue arrays.  Warn, then
     // force the promotion here.
     Diag(LHSExp->getBeginLoc(), diag::ext_subscript_non_lvalue)
         << LHSExp->getSourceRange();
     LHSExp = ImpCastExprToType(LHSExp, Context.getArrayDecayedType(LHSTy),
                                CK_ArrayToPointerDecay).get();
     LHSTy = LHSExp->getType();
 
     BaseExpr = LHSExp;
     IndexExpr = RHSExp;
     ResultType = LHSTy->castAs<PointerType>()->getPointeeType();
   } else if (RHSTy->isArrayType()) {
     // Same as previous, except for 123[f().a] case
     Diag(RHSExp->getBeginLoc(), diag::ext_subscript_non_lvalue)
         << RHSExp->getSourceRange();
     RHSExp = ImpCastExprToType(RHSExp, Context.getArrayDecayedType(RHSTy),
                                CK_ArrayToPointerDecay).get();
     RHSTy = RHSExp->getType();
 
     BaseExpr = RHSExp;
     IndexExpr = LHSExp;
     ResultType = RHSTy->castAs<PointerType>()->getPointeeType();
   } else {
     return ExprError(Diag(LLoc, diag::err_typecheck_subscript_value)
        << LHSExp->getSourceRange() << RHSExp->getSourceRange());
   }
   // C99 6.5.2.1p1
   if (!IndexExpr->getType()->isIntegerType() && !IndexExpr->isTypeDependent())
     return ExprError(Diag(LLoc, diag::err_typecheck_subscript_not_integer)
                      << IndexExpr->getSourceRange());
 
   if ((IndexExpr->getType()->isSpecificBuiltinType(BuiltinType::Char_S) ||
        IndexExpr->getType()->isSpecificBuiltinType(BuiltinType::Char_U))
          && !IndexExpr->isTypeDependent())
     Diag(LLoc, diag::warn_subscript_is_char) << IndexExpr->getSourceRange();
 
   // C99 6.5.2.1p1: "shall have type "pointer to *object* type". Similarly,
   // C++ [expr.sub]p1: The type "T" shall be a completely-defined object
   // type. Note that Functions are not objects, and that (in C99 parlance)
   // incomplete types are not object types.
   if (ResultType->isFunctionType()) {
     Diag(BaseExpr->getBeginLoc(), diag::err_subscript_function_type)
         << ResultType << BaseExpr->getSourceRange();
     return ExprError();
   }
 
   if (ResultType->isVoidType() && !getLangOpts().CPlusPlus) {
     // GNU extension: subscripting on pointer to void
     Diag(LLoc, diag::ext_gnu_subscript_void_type)
       << BaseExpr->getSourceRange();
 
     // C forbids expressions of unqualified void type from being l-values.
     // See IsCForbiddenLValueType.
     if (!ResultType.hasQualifiers())
       VK = VK_PRValue;
   } else if (!ResultType->isDependentType() &&
              !ResultType.isWebAssemblyReferenceType() &&
              RequireCompleteSizedType(
                  LLoc, ResultType,
                  diag::err_subscript_incomplete_or_sizeless_type, BaseExpr))
     return ExprError();
 
   assert(VK == VK_PRValue || LangOpts.CPlusPlus ||
          !ResultType.isCForbiddenLValueType());
 
   if (LHSExp->IgnoreParenImpCasts()->getType()->isVariablyModifiedType() &&
       FunctionScopes.size() > 1) {
     if (auto *TT =
             LHSExp->IgnoreParenImpCasts()->getType()->getAs<TypedefType>()) {
       for (auto I = FunctionScopes.rbegin(),
                 E = std::prev(FunctionScopes.rend());
            I != E; ++I) {
         auto *CSI = dyn_cast<CapturingScopeInfo>(*I);
         if (CSI == nullptr)
           break;
         DeclContext *DC = nullptr;
         if (auto *LSI = dyn_cast<LambdaScopeInfo>(CSI))
           DC = LSI->CallOperator;
         else if (auto *CRSI = dyn_cast<CapturedRegionScopeInfo>(CSI))
           DC = CRSI->TheCapturedDecl;
         else if (auto *BSI = dyn_cast<BlockScopeInfo>(CSI))
           DC = BSI->TheDecl;
         if (DC) {
           if (DC->containsDecl(TT->getDecl()))
             break;
           captureVariablyModifiedType(
               Context, LHSExp->IgnoreParenImpCasts()->getType(), CSI);
         }
       }
     }
   }
 
   return new (Context)
       ArraySubscriptExpr(LHSExp, RHSExp, ResultType, VK, OK, RLoc);
 }
 
 bool Sema::CheckCXXDefaultArgExpr(SourceLocation CallLoc, FunctionDecl *FD,
                                   ParmVarDecl *Param, Expr *RewrittenInit,
                                   bool SkipImmediateInvocations) {
   if (Param->hasUnparsedDefaultArg()) {
     assert(!RewrittenInit && "Should not have a rewritten init expression yet");
     // If we've already cleared out the location for the default argument,
     // that means we're parsing it right now.
     if (!UnparsedDefaultArgLocs.count(Param)) {
       Diag(Param->getBeginLoc(), diag::err_recursive_default_argument) << FD;
       Diag(CallLoc, diag::note_recursive_default_argument_used_here);
       Param->setInvalidDecl();
       return true;
     }
 
     Diag(CallLoc, diag::err_use_of_default_argument_to_function_declared_later)
         << FD << cast<CXXRecordDecl>(FD->getDeclContext());
     Diag(UnparsedDefaultArgLocs[Param],
          diag::note_default_argument_declared_here);
     return true;
   }
 
   if (Param->hasUninstantiatedDefaultArg()) {
     assert(!RewrittenInit && "Should not have a rewitten init expression yet");
     if (InstantiateDefaultArgument(CallLoc, FD, Param))
       return true;
   }
 
   Expr *Init = RewrittenInit ? RewrittenInit : Param->getInit();
   assert(Init && "default argument but no initializer?");
 
   // If the default expression creates temporaries, we need to
   // push them to the current stack of expression temporaries so they'll
   // be properly destroyed.
   // FIXME: We should really be rebuilding the default argument with new
   // bound temporaries; see the comment in PR5810.
   // We don't need to do that with block decls, though, because
   // blocks in default argument expression can never capture anything.
   if (auto *InitWithCleanup = dyn_cast<ExprWithCleanups>(Init)) {
     // Set the "needs cleanups" bit regardless of whether there are
     // any explicit objects.
     Cleanup.setExprNeedsCleanups(InitWithCleanup->cleanupsHaveSideEffects());
     // Append all the objects to the cleanup list.  Right now, this
     // should always be a no-op, because blocks in default argument
     // expressions should never be able to capture anything.
     assert(!InitWithCleanup->getNumObjects() &&
            "default argument expression has capturing blocks?");
   }
   // C++ [expr.const]p15.1:
   //   An expression or conversion is in an immediate function context if it is
   //   potentially evaluated and [...] its innermost enclosing non-block scope
   //   is a function parameter scope of an immediate function.
   EnterExpressionEvaluationContext EvalContext(
       *this,
       FD->isImmediateFunction()
           ? ExpressionEvaluationContext::ImmediateFunctionContext
           : ExpressionEvaluationContext::PotentiallyEvaluated,
       Param);
   ExprEvalContexts.back().IsCurrentlyCheckingDefaultArgumentOrInitializer =
       SkipImmediateInvocations;
   runWithSufficientStackSpace(CallLoc, [&] {
     MarkDeclarationsReferencedInExpr(Init, /*SkipLocalVariables=*/true);
   });
   return false;
 }
 
 struct ImmediateCallVisitor : public RecursiveASTVisitor<ImmediateCallVisitor> {
   const ASTContext &Context;
   ImmediateCallVisitor(const ASTContext &Ctx) : Context(Ctx) {}
 
   bool HasImmediateCalls = false;
   bool shouldVisitImplicitCode() const { return true; }
 
   bool VisitCallExpr(CallExpr *E) {
     if (const FunctionDecl *FD = E->getDirectCallee())
       HasImmediateCalls |= FD->isImmediateFunction();
     return RecursiveASTVisitor<ImmediateCallVisitor>::VisitStmt(E);
   }
 
   // SourceLocExpr are not immediate invocations
   // but CXXDefaultInitExpr/CXXDefaultArgExpr containing a SourceLocExpr
   // need to be rebuilt so that they refer to the correct SourceLocation and
   // DeclContext.
   bool VisitSourceLocExpr(SourceLocExpr *E) {
     HasImmediateCalls = true;
     return RecursiveASTVisitor<ImmediateCallVisitor>::VisitStmt(E);
   }
 
   // A nested lambda might have parameters with immediate invocations
   // in their default arguments.
   // The compound statement is not visited (as it does not constitute a
   // subexpression).
   // FIXME: We should consider visiting and transforming captures
   // with init expressions.
   bool VisitLambdaExpr(LambdaExpr *E) {
     return VisitCXXMethodDecl(E->getCallOperator());
   }
 
   // Blocks don't support default parameters, and, as for lambdas,
   // we don't consider their body a subexpression.
   bool VisitBlockDecl(BlockDecl *B) { return false; }
 
   bool VisitCompoundStmt(CompoundStmt *B) { return false; }
 
   bool VisitCXXDefaultArgExpr(CXXDefaultArgExpr *E) {
     return TraverseStmt(E->getExpr());
   }
 
   bool VisitCXXDefaultInitExpr(CXXDefaultInitExpr *E) {
     return TraverseStmt(E->getExpr());
   }
 };
 
 struct EnsureImmediateInvocationInDefaultArgs
     : TreeTransform<EnsureImmediateInvocationInDefaultArgs> {
   EnsureImmediateInvocationInDefaultArgs(Sema &SemaRef)
       : TreeTransform(SemaRef) {}
 
   // Lambda can only have immediate invocations in the default
   // args of their parameters, which is transformed upon calling the closure.
   // The body is not a subexpression, so we have nothing to do.
   // FIXME: Immediate calls in capture initializers should be transformed.
   ExprResult TransformLambdaExpr(LambdaExpr *E) { return E; }
   ExprResult TransformBlockExpr(BlockExpr *E) { return E; }
 
   // Make sure we don't rebuild the this pointer as it would
   // cause it to incorrectly point it to the outermost class
   // in the case of nested struct initialization.
   ExprResult TransformCXXThisExpr(CXXThisExpr *E) { return E; }
 };
 
 ExprResult Sema::BuildCXXDefaultArgExpr(SourceLocation CallLoc,
                                         FunctionDecl *FD, ParmVarDecl *Param,
                                         Expr *Init) {
   assert(Param->hasDefaultArg() && "can't build nonexistent default arg");
 
   bool NestedDefaultChecking = isCheckingDefaultArgumentOrInitializer();
 
   std::optional<ExpressionEvaluationContextRecord::InitializationContext>
       InitializationContext =
           OutermostDeclarationWithDelayedImmediateInvocations();
   if (!InitializationContext.has_value())
     InitializationContext.emplace(CallLoc, Param, CurContext);
 
   if (!Init && !Param->hasUnparsedDefaultArg()) {
     // Mark that we are replacing a default argument first.
     // If we are instantiating a template we won't have to
     // retransform immediate calls.
     // C++ [expr.const]p15.1:
     //   An expression or conversion is in an immediate function context if it
     //   is potentially evaluated and [...] its innermost enclosing non-block
     //   scope is a function parameter scope of an immediate function.
     EnterExpressionEvaluationContext EvalContext(
         *this,
         FD->isImmediateFunction()
             ? ExpressionEvaluationContext::ImmediateFunctionContext
             : ExpressionEvaluationContext::PotentiallyEvaluated,
         Param);
 
     if (Param->hasUninstantiatedDefaultArg()) {
       if (InstantiateDefaultArgument(CallLoc, FD, Param))
         return ExprError();
     }
     // CWG2631
     // An immediate invocation that is not evaluated where it appears is
     // evaluated and checked for whether it is a constant expression at the
     // point where the enclosing initializer is used in a function call.
     ImmediateCallVisitor V(getASTContext());
     if (!NestedDefaultChecking)
       V.TraverseDecl(Param);
     if (V.HasImmediateCalls) {
       ExprEvalContexts.back().DelayedDefaultInitializationContext = {
           CallLoc, Param, CurContext};
       EnsureImmediateInvocationInDefaultArgs Immediate(*this);
       ExprResult Res;
       runWithSufficientStackSpace(CallLoc, [&] {
         Res = Immediate.TransformInitializer(Param->getInit(),
                                              /*NotCopy=*/false);
       });
       if (Res.isInvalid())
         return ExprError();
       Res = ConvertParamDefaultArgument(Param, Res.get(),
                                         Res.get()->getBeginLoc());
       if (Res.isInvalid())
         return ExprError();
       Init = Res.get();
     }
   }
 
   if (CheckCXXDefaultArgExpr(
           CallLoc, FD, Param, Init,
           /*SkipImmediateInvocations=*/NestedDefaultChecking))
     return ExprError();
 
   return CXXDefaultArgExpr::Create(Context, InitializationContext->Loc, Param,
                                    Init, InitializationContext->Context);
 }
 
 ExprResult Sema::BuildCXXDefaultInitExpr(SourceLocation Loc, FieldDecl *Field) {
   assert(Field->hasInClassInitializer());
 
   // If we might have already tried and failed to instantiate, don't try again.
   if (Field->isInvalidDecl())
     return ExprError();
 
   CXXThisScopeRAII This(*this, Field->getParent(), Qualifiers());
 
   auto *ParentRD = cast<CXXRecordDecl>(Field->getParent());
 
   std::optional<ExpressionEvaluationContextRecord::InitializationContext>
       InitializationContext =
           OutermostDeclarationWithDelayedImmediateInvocations();
   if (!InitializationContext.has_value())
     InitializationContext.emplace(Loc, Field, CurContext);
 
   Expr *Init = nullptr;
 
   bool NestedDefaultChecking = isCheckingDefaultArgumentOrInitializer();
 
   EnterExpressionEvaluationContext EvalContext(
       *this, ExpressionEvaluationContext::PotentiallyEvaluated, Field);
 
   if (!Field->getInClassInitializer()) {
     // Maybe we haven't instantiated the in-class initializer. Go check the
     // pattern FieldDecl to see if it has one.
     if (isTemplateInstantiation(ParentRD->getTemplateSpecializationKind())) {
       CXXRecordDecl *ClassPattern = ParentRD->getTemplateInstantiationPattern();
       DeclContext::lookup_result Lookup =
           ClassPattern->lookup(Field->getDeclName());
 
       FieldDecl *Pattern = nullptr;
       for (auto *L : Lookup) {
         if ((Pattern = dyn_cast<FieldDecl>(L)))
           break;
       }
       assert(Pattern && "We must have set the Pattern!");
       if (!Pattern->hasInClassInitializer() ||
           InstantiateInClassInitializer(Loc, Field, Pattern,
                                         getTemplateInstantiationArgs(Field))) {
         Field->setInvalidDecl();
         return ExprError();
       }
     }
   }
 
   // CWG2631
   // An immediate invocation that is not evaluated where it appears is
   // evaluated and checked for whether it is a constant expression at the
   // point where the enclosing initializer is used in a [...] a constructor
   // definition, or an aggregate initialization.
   ImmediateCallVisitor V(getASTContext());
   if (!NestedDefaultChecking)
     V.TraverseDecl(Field);
   if (V.HasImmediateCalls) {
     ExprEvalContexts.back().DelayedDefaultInitializationContext = {Loc, Field,
                                                                    CurContext};
     ExprEvalContexts.back().IsCurrentlyCheckingDefaultArgumentOrInitializer =
         NestedDefaultChecking;
 
     EnsureImmediateInvocationInDefaultArgs Immediate(*this);
     ExprResult Res;
     runWithSufficientStackSpace(Loc, [&] {
       Res = Immediate.TransformInitializer(Field->getInClassInitializer(),
                                            /*CXXDirectInit=*/false);
     });
     if (!Res.isInvalid())
       Res = ConvertMemberDefaultInitExpression(Field, Res.get(), Loc);
     if (Res.isInvalid()) {
       Field->setInvalidDecl();
       return ExprError();
     }
     Init = Res.get();
   }
 
   if (Field->getInClassInitializer()) {
     Expr *E = Init ? Init : Field->getInClassInitializer();
     if (!NestedDefaultChecking)
       runWithSufficientStackSpace(Loc, [&] {
         MarkDeclarationsReferencedInExpr(E, /*SkipLocalVariables=*/false);
       });
     // C++11 [class.base.init]p7:
     //   The initialization of each base and member constitutes a
     //   full-expression.
     ExprResult Res = ActOnFinishFullExpr(E, /*DiscardedValue=*/false);
     if (Res.isInvalid()) {
       Field->setInvalidDecl();
       return ExprError();
     }
     Init = Res.get();
 
     return CXXDefaultInitExpr::Create(Context, InitializationContext->Loc,
                                       Field, InitializationContext->Context,
                                       Init);
   }
 
   // DR1351:
   //   If the brace-or-equal-initializer of a non-static data member
   //   invokes a defaulted default constructor of its class or of an
   //   enclosing class in a potentially evaluated subexpression, the
   //   program is ill-formed.
   //
   // This resolution is unworkable: the exception specification of the
   // default constructor can be needed in an unevaluated context, in
   // particular, in the operand of a noexcept-expression, and we can be
   // unable to compute an exception specification for an enclosed class.
   //
   // Any attempt to resolve the exception specification of a defaulted default
   // constructor before the initializer is lexically complete will ultimately
   // come here at which point we can diagnose it.
   RecordDecl *OutermostClass = ParentRD->getOuterLexicalRecordContext();
   Diag(Loc, diag::err_default_member_initializer_not_yet_parsed)
       << OutermostClass << Field;
   Diag(Field->getEndLoc(),
        diag::note_default_member_initializer_not_yet_parsed);
   // Recover by marking the field invalid, unless we're in a SFINAE context.
   if (!isSFINAEContext())
     Field->setInvalidDecl();
   return ExprError();
 }
 
 Sema::VariadicCallType
 Sema::getVariadicCallType(FunctionDecl *FDecl, const FunctionProtoType *Proto,
                           Expr *Fn) {
   if (Proto && Proto->isVariadic()) {
     if (isa_and_nonnull<CXXConstructorDecl>(FDecl))
       return VariadicConstructor;
     else if (Fn && Fn->getType()->isBlockPointerType())
       return VariadicBlock;
     else if (FDecl) {
       if (CXXMethodDecl *Method = dyn_cast_or_null<CXXMethodDecl>(FDecl))
         if (Method->isInstance())
           return VariadicMethod;
     } else if (Fn && Fn->getType() == Context.BoundMemberTy)
       return VariadicMethod;
     return VariadicFunction;
   }
   return VariadicDoesNotApply;
 }
 
 namespace {
 class FunctionCallCCC final : public FunctionCallFilterCCC {
 public:
   FunctionCallCCC(Sema &SemaRef, const IdentifierInfo *FuncName,
                   unsigned NumArgs, MemberExpr *ME)
       : FunctionCallFilterCCC(SemaRef, NumArgs, false, ME),
         FunctionName(FuncName) {}
 
   bool ValidateCandidate(const TypoCorrection &candidate) override {
     if (!candidate.getCorrectionSpecifier() ||
         candidate.getCorrectionAsIdentifierInfo() != FunctionName) {
       return false;
     }
 
     return FunctionCallFilterCCC::ValidateCandidate(candidate);
   }
 
   std::unique_ptr<CorrectionCandidateCallback> clone() override {
     return std::make_unique<FunctionCallCCC>(*this);
   }
 
 private:
   const IdentifierInfo *const FunctionName;
 };
 }
 
 static TypoCorrection TryTypoCorrectionForCall(Sema &S, Expr *Fn,
                                                FunctionDecl *FDecl,
                                                ArrayRef<Expr *> Args) {
   MemberExpr *ME = dyn_cast<MemberExpr>(Fn);
   DeclarationName FuncName = FDecl->getDeclName();
   SourceLocation NameLoc = ME ? ME->getMemberLoc() : Fn->getBeginLoc();
 
   FunctionCallCCC CCC(S, FuncName.getAsIdentifierInfo(), Args.size(), ME);
   if (TypoCorrection Corrected = S.CorrectTypo(
           DeclarationNameInfo(FuncName, NameLoc), Sema::LookupOrdinaryName,
           S.getScopeForContext(S.CurContext), nullptr, CCC,
           Sema::CTK_ErrorRecovery)) {
     if (NamedDecl *ND = Corrected.getFoundDecl()) {
       if (Corrected.isOverloaded()) {
         OverloadCandidateSet OCS(NameLoc, OverloadCandidateSet::CSK_Normal);
         OverloadCandidateSet::iterator Best;
         for (NamedDecl *CD : Corrected) {
           if (FunctionDecl *FD = dyn_cast<FunctionDecl>(CD))
             S.AddOverloadCandidate(FD, DeclAccessPair::make(FD, AS_none), Args,
                                    OCS);
         }
         switch (OCS.BestViableFunction(S, NameLoc, Best)) {
         case OR_Success:
           ND = Best->FoundDecl;
           Corrected.setCorrectionDecl(ND);
           break;
         default:
           break;
         }
       }
       ND = ND->getUnderlyingDecl();
       if (isa<ValueDecl>(ND) || isa<FunctionTemplateDecl>(ND))
         return Corrected;
     }
   }
   return TypoCorrection();
 }
 
 /// ConvertArgumentsForCall - Converts the arguments specified in
 /// Args/NumArgs to the parameter types of the function FDecl with
 /// function prototype Proto. Call is the call expression itself, and
 /// Fn is the function expression. For a C++ member function, this
 /// routine does not attempt to convert the object argument. Returns
 /// true if the call is ill-formed.
 bool
 Sema::ConvertArgumentsForCall(CallExpr *Call, Expr *Fn,
                               FunctionDecl *FDecl,
                               const FunctionProtoType *Proto,
                               ArrayRef<Expr *> Args,
                               SourceLocation RParenLoc,
                               bool IsExecConfig) {
   // Bail out early if calling a builtin with custom typechecking.
   if (FDecl)
     if (unsigned ID = FDecl->getBuiltinID())
       if (Context.BuiltinInfo.hasCustomTypechecking(ID))
         return false;
 
   // C99 6.5.2.2p7 - the arguments are implicitly converted, as if by
   // assignment, to the types of the corresponding parameter, ...
   unsigned NumParams = Proto->getNumParams();
   bool Invalid = false;
   unsigned MinArgs = FDecl ? FDecl->getMinRequiredArguments() : NumParams;
   unsigned FnKind = Fn->getType()->isBlockPointerType()
                        ? 1 /* block */
                        : (IsExecConfig ? 3 /* kernel function (exec config) */
                                        : 0 /* function */);
 
   // If too few arguments are available (and we don't have default
   // arguments for the remaining parameters), don't make the call.
   if (Args.size() < NumParams) {
     if (Args.size() < MinArgs) {
       TypoCorrection TC;
       if (FDecl && (TC = TryTypoCorrectionForCall(*this, Fn, FDecl, Args))) {
         unsigned diag_id =
             MinArgs == NumParams && !Proto->isVariadic()
                 ? diag::err_typecheck_call_too_few_args_suggest
                 : diag::err_typecheck_call_too_few_args_at_least_suggest;
         diagnoseTypo(TC, PDiag(diag_id) << FnKind << MinArgs
                                         << static_cast<unsigned>(Args.size())
                                         << TC.getCorrectionRange());
       } else if (MinArgs == 1 && FDecl && FDecl->getParamDecl(0)->getDeclName())
         Diag(RParenLoc,
              MinArgs == NumParams && !Proto->isVariadic()
                  ? diag::err_typecheck_call_too_few_args_one
                  : diag::err_typecheck_call_too_few_args_at_least_one)
             << FnKind << FDecl->getParamDecl(0) << Fn->getSourceRange();
       else
         Diag(RParenLoc, MinArgs == NumParams && !Proto->isVariadic()
                             ? diag::err_typecheck_call_too_few_args
                             : diag::err_typecheck_call_too_few_args_at_least)
             << FnKind << MinArgs << static_cast<unsigned>(Args.size())
             << Fn->getSourceRange();
 
       // Emit the location of the prototype.
       if (!TC && FDecl && !FDecl->getBuiltinID() && !IsExecConfig)
         Diag(FDecl->getLocation(), diag::note_callee_decl)
             << FDecl << FDecl->getParametersSourceRange();
 
       return true;
     }
     // We reserve space for the default arguments when we create
     // the call expression, before calling ConvertArgumentsForCall.
     assert((Call->getNumArgs() == NumParams) &&
            "We should have reserved space for the default arguments before!");
   }
 
   // If too many are passed and not variadic, error on the extras and drop
   // them.
   if (Args.size() > NumParams) {
     if (!Proto->isVariadic()) {
       TypoCorrection TC;
       if (FDecl && (TC = TryTypoCorrectionForCall(*this, Fn, FDecl, Args))) {
         unsigned diag_id =
             MinArgs == NumParams && !Proto->isVariadic()
                 ? diag::err_typecheck_call_too_many_args_suggest
                 : diag::err_typecheck_call_too_many_args_at_most_suggest;
         diagnoseTypo(TC, PDiag(diag_id) << FnKind << NumParams
                                         << static_cast<unsigned>(Args.size())
                                         << TC.getCorrectionRange());
       } else if (NumParams == 1 && FDecl &&
                  FDecl->getParamDecl(0)->getDeclName())
         Diag(Args[NumParams]->getBeginLoc(),
              MinArgs == NumParams
                  ? diag::err_typecheck_call_too_many_args_one
                  : diag::err_typecheck_call_too_many_args_at_most_one)
             << FnKind << FDecl->getParamDecl(0)
             << static_cast<unsigned>(Args.size()) << Fn->getSourceRange()
             << SourceRange(Args[NumParams]->getBeginLoc(),
                            Args.back()->getEndLoc());
       else
         Diag(Args[NumParams]->getBeginLoc(),
              MinArgs == NumParams
                  ? diag::err_typecheck_call_too_many_args
                  : diag::err_typecheck_call_too_many_args_at_most)
             << FnKind << NumParams << static_cast<unsigned>(Args.size())
             << Fn->getSourceRange()
             << SourceRange(Args[NumParams]->getBeginLoc(),
                            Args.back()->getEndLoc());
 
       // Emit the location of the prototype.
       if (!TC && FDecl && !FDecl->getBuiltinID() && !IsExecConfig)
         Diag(FDecl->getLocation(), diag::note_callee_decl)
             << FDecl << FDecl->getParametersSourceRange();
 
       // This deletes the extra arguments.
       Call->shrinkNumArgs(NumParams);
       return true;
     }
   }
   SmallVector<Expr *, 8> AllArgs;
   VariadicCallType CallType = getVariadicCallType(FDecl, Proto, Fn);
 
   Invalid = GatherArgumentsForCall(Call->getBeginLoc(), FDecl, Proto, 0, Args,
                                    AllArgs, CallType);
   if (Invalid)
     return true;
   unsigned TotalNumArgs = AllArgs.size();
   for (unsigned i = 0; i < TotalNumArgs; ++i)
     Call->setArg(i, AllArgs[i]);
 
   Call->computeDependence();
   return false;
 }
 
 bool Sema::GatherArgumentsForCall(SourceLocation CallLoc, FunctionDecl *FDecl,
                                   const FunctionProtoType *Proto,
                                   unsigned FirstParam, ArrayRef<Expr *> Args,
                                   SmallVectorImpl<Expr *> &AllArgs,
                                   VariadicCallType CallType, bool AllowExplicit,
                                   bool IsListInitialization) {
   unsigned NumParams = Proto->getNumParams();
   bool Invalid = false;
   size_t ArgIx = 0;
   // Continue to check argument types (even if we have too few/many args).
   for (unsigned i = FirstParam; i < NumParams; i++) {
     QualType ProtoArgType = Proto->getParamType(i);
 
     Expr *Arg;
     ParmVarDecl *Param = FDecl ? FDecl->getParamDecl(i) : nullptr;
     if (ArgIx < Args.size()) {
       Arg = Args[ArgIx++];
 
       if (RequireCompleteType(Arg->getBeginLoc(), ProtoArgType,
                               diag::err_call_incomplete_argument, Arg))
         return true;
 
       // Strip the unbridged-cast placeholder expression off, if applicable.
       bool CFAudited = false;
       if (Arg->getType() == Context.ARCUnbridgedCastTy &&
           FDecl && FDecl->hasAttr<CFAuditedTransferAttr>() &&
           (!Param || !Param->hasAttr<CFConsumedAttr>()))
         Arg = stripARCUnbridgedCast(Arg);
       else if (getLangOpts().ObjCAutoRefCount &&
                FDecl && FDecl->hasAttr<CFAuditedTransferAttr>() &&
                (!Param || !Param->hasAttr<CFConsumedAttr>()))
         CFAudited = true;
 
       if (Proto->getExtParameterInfo(i).isNoEscape() &&
           ProtoArgType->isBlockPointerType())
         if (auto *BE = dyn_cast<BlockExpr>(Arg->IgnoreParenNoopCasts(Context)))
           BE->getBlockDecl()->setDoesNotEscape();
 
       InitializedEntity Entity =
           Param ? InitializedEntity::InitializeParameter(Context, Param,
                                                          ProtoArgType)
                 : InitializedEntity::InitializeParameter(
                       Context, ProtoArgType, Proto->isParamConsumed(i));
 
       // Remember that parameter belongs to a CF audited API.
       if (CFAudited)
         Entity.setParameterCFAudited();
 
       ExprResult ArgE = PerformCopyInitialization(
           Entity, SourceLocation(), Arg, IsListInitialization, AllowExplicit);
       if (ArgE.isInvalid())
         return true;
 
       Arg = ArgE.getAs<Expr>();
     } else {
       assert(Param && "can't use default arguments without a known callee");
 
       ExprResult ArgExpr = BuildCXXDefaultArgExpr(CallLoc, FDecl, Param);
       if (ArgExpr.isInvalid())
         return true;
 
       Arg = ArgExpr.getAs<Expr>();
     }
 
     // Check for array bounds violations for each argument to the call. This
     // check only triggers warnings when the argument isn't a more complex Expr
     // with its own checking, such as a BinaryOperator.
     CheckArrayAccess(Arg);
 
     // Check for violations of C99 static array rules (C99 6.7.5.3p7).
     CheckStaticArrayArgument(CallLoc, Param, Arg);
 
     AllArgs.push_back(Arg);
   }
 
   // If this is a variadic call, handle args passed through "...".
   if (CallType != VariadicDoesNotApply) {
     // Assume that extern "C" functions with variadic arguments that
     // return __unknown_anytype aren't *really* variadic.
     if (Proto->getReturnType() == Context.UnknownAnyTy && FDecl &&
         FDecl->isExternC()) {
       for (Expr *A : Args.slice(ArgIx)) {
         QualType paramType; // ignored
         ExprResult arg = checkUnknownAnyArg(CallLoc, A, paramType);
         Invalid |= arg.isInvalid();
         AllArgs.push_back(arg.get());
       }
 
     // Otherwise do argument promotion, (C99 6.5.2.2p7).
     } else {
       for (Expr *A : Args.slice(ArgIx)) {
         ExprResult Arg = DefaultVariadicArgumentPromotion(A, CallType, FDecl);
         Invalid |= Arg.isInvalid();
         AllArgs.push_back(Arg.get());
       }
     }
 
     // Check for array bounds violations.
     for (Expr *A : Args.slice(ArgIx))
       CheckArrayAccess(A);
   }
   return Invalid;
 }
 
 static void DiagnoseCalleeStaticArrayParam(Sema &S, ParmVarDecl *PVD) {
   TypeLoc TL = PVD->getTypeSourceInfo()->getTypeLoc();
   if (DecayedTypeLoc DTL = TL.getAs<DecayedTypeLoc>())
     TL = DTL.getOriginalLoc();
   if (ArrayTypeLoc ATL = TL.getAs<ArrayTypeLoc>())
     S.Diag(PVD->getLocation(), diag::note_callee_static_array)
       << ATL.getLocalSourceRange();
 }
 
 /// CheckStaticArrayArgument - If the given argument corresponds to a static
 /// array parameter, check that it is non-null, and that if it is formed by
 /// array-to-pointer decay, the underlying array is sufficiently large.
 ///
 /// C99 6.7.5.3p7: If the keyword static also appears within the [ and ] of the
 /// array type derivation, then for each call to the function, the value of the
 /// corresponding actual argument shall provide access to the first element of
 /// an array with at least as many elements as specified by the size expression.
 void
 Sema::CheckStaticArrayArgument(SourceLocation CallLoc,
                                ParmVarDecl *Param,
                                const Expr *ArgExpr) {
   // Static array parameters are not supported in C++.
   if (!Param || getLangOpts().CPlusPlus)
     return;
 
   QualType OrigTy = Param->getOriginalType();
 
   const ArrayType *AT = Context.getAsArrayType(OrigTy);
   if (!AT || AT->getSizeModifier() != ArrayType::Static)
     return;
 
   if (ArgExpr->isNullPointerConstant(Context,
                                      Expr::NPC_NeverValueDependent)) {
     Diag(CallLoc, diag::warn_null_arg) << ArgExpr->getSourceRange();
     DiagnoseCalleeStaticArrayParam(*this, Param);
     return;
   }
 
   const ConstantArrayType *CAT = dyn_cast<ConstantArrayType>(AT);
   if (!CAT)
     return;
 
   const ConstantArrayType *ArgCAT =
     Context.getAsConstantArrayType(ArgExpr->IgnoreParenCasts()->getType());
   if (!ArgCAT)
     return;
 
   if (getASTContext().hasSameUnqualifiedType(CAT->getElementType(),
                                              ArgCAT->getElementType())) {
     if (ArgCAT->getSize().ult(CAT->getSize())) {
       Diag(CallLoc, diag::warn_static_array_too_small)
           << ArgExpr->getSourceRange()
           << (unsigned)ArgCAT->getSize().getZExtValue()
           << (unsigned)CAT->getSize().getZExtValue() << 0;
       DiagnoseCalleeStaticArrayParam(*this, Param);
     }
     return;
   }
 
   std::optional<CharUnits> ArgSize =
       getASTContext().getTypeSizeInCharsIfKnown(ArgCAT);
   std::optional<CharUnits> ParmSize =
       getASTContext().getTypeSizeInCharsIfKnown(CAT);
   if (ArgSize && ParmSize && *ArgSize < *ParmSize) {
     Diag(CallLoc, diag::warn_static_array_too_small)
         << ArgExpr->getSourceRange() << (unsigned)ArgSize->getQuantity()
         << (unsigned)ParmSize->getQuantity() << 1;
     DiagnoseCalleeStaticArrayParam(*this, Param);
   }
 }
 
 /// Given a function expression of unknown-any type, try to rebuild it
 /// to have a function type.
 static ExprResult rebuildUnknownAnyFunction(Sema &S, Expr *fn);
 
 /// Is the given type a placeholder that we need to lower out
 /// immediately during argument processing?
 static bool isPlaceholderToRemoveAsArg(QualType type) {
   // Placeholders are never sugared.
   const BuiltinType *placeholder = dyn_cast<BuiltinType>(type);
   if (!placeholder) return false;
 
   switch (placeholder->getKind()) {
   // Ignore all the non-placeholder types.
 #define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \
   case BuiltinType::Id:
 #include "clang/Basic/OpenCLImageTypes.def"
 #define EXT_OPAQUE_TYPE(ExtType, Id, Ext) \
   case BuiltinType::Id:
 #include "clang/Basic/OpenCLExtensionTypes.def"
   // In practice we'll never use this, since all SVE types are sugared
   // via TypedefTypes rather than exposed directly as BuiltinTypes.
 #define SVE_TYPE(Name, Id, SingletonId) \
   case BuiltinType::Id:
 #include "clang/Basic/AArch64SVEACLETypes.def"
 #define PPC_VECTOR_TYPE(Name, Id, Size) \
   case BuiltinType::Id:
 #include "clang/Basic/PPCTypes.def"
 #define RVV_TYPE(Name, Id, SingletonId) case BuiltinType::Id:
 #include "clang/Basic/RISCVVTypes.def"
 #define WASM_TYPE(Name, Id, SingletonId) case BuiltinType::Id:
 #include "clang/Basic/WebAssemblyReferenceTypes.def"
 #define PLACEHOLDER_TYPE(ID, SINGLETON_ID)
 #define BUILTIN_TYPE(ID, SINGLETON_ID) case BuiltinType::ID:
 #include "clang/AST/BuiltinTypes.def"
     return false;
 
   // We cannot lower out overload sets; they might validly be resolved
   // by the call machinery.
   case BuiltinType::Overload:
     return false;
 
   // Unbridged casts in ARC can be handled in some call positions and
   // should be left in place.
   case BuiltinType::ARCUnbridgedCast:
     return false;
 
   // Pseudo-objects should be converted as soon as possible.
   case BuiltinType::PseudoObject:
     return true;
 
   // The debugger mode could theoretically but currently does not try
   // to resolve unknown-typed arguments based on known parameter types.
   case BuiltinType::UnknownAny:
     return true;
 
   // These are always invalid as call arguments and should be reported.
   case BuiltinType::BoundMember:
   case BuiltinType::BuiltinFn:
   case BuiltinType::IncompleteMatrixIdx:
   case BuiltinType::OMPArraySection:
   case BuiltinType::OMPArrayShaping:
   case BuiltinType::OMPIterator:
     return true;
 
   }
   llvm_unreachable("bad builtin type kind");
 }
 
 /// Check an argument list for placeholders that we won't try to
 /// handle later.
 static bool checkArgsForPlaceholders(Sema &S, MultiExprArg args) {
   // Apply this processing to all the arguments at once instead of
   // dying at the first failure.
   bool hasInvalid = false;
   for (size_t i = 0, e = args.size(); i != e; i++) {
     if (isPlaceholderToRemoveAsArg(args[i]->getType())) {
       ExprResult result = S.CheckPlaceholderExpr(args[i]);
       if (result.isInvalid()) hasInvalid = true;
       else args[i] = result.get();
     }
   }
   return hasInvalid;
 }
 
 /// If a builtin function has a pointer argument with no explicit address
 /// space, then it should be able to accept a pointer to any address
 /// space as input.  In order to do this, we need to replace the
 /// standard builtin declaration with one that uses the same address space
 /// as the call.
 ///
 /// \returns nullptr If this builtin is not a candidate for a rewrite i.e.
 ///                  it does not contain any pointer arguments without
 ///                  an address space qualifer.  Otherwise the rewritten
 ///                  FunctionDecl is returned.
 /// TODO: Handle pointer return types.
 static FunctionDecl *rewriteBuiltinFunctionDecl(Sema *Sema, ASTContext &Context,
                                                 FunctionDecl *FDecl,
                                                 MultiExprArg ArgExprs) {
 
   QualType DeclType = FDecl->getType();
   const FunctionProtoType *FT = dyn_cast<FunctionProtoType>(DeclType);
 
   if (!Context.BuiltinInfo.hasPtrArgsOrResult(FDecl->getBuiltinID()) || !FT ||
       ArgExprs.size() < FT->getNumParams())
     return nullptr;
 
   bool NeedsNewDecl = false;
   unsigned i = 0;
   SmallVector<QualType, 8> OverloadParams;
 
   for (QualType ParamType : FT->param_types()) {
 
     // Convert array arguments to pointer to simplify type lookup.
     ExprResult ArgRes =
         Sema->DefaultFunctionArrayLvalueConversion(ArgExprs[i++]);
     if (ArgRes.isInvalid())
       return nullptr;
     Expr *Arg = ArgRes.get();
     QualType ArgType = Arg->getType();
     if (!ParamType->isPointerType() || ParamType.hasAddressSpace() ||
         !ArgType->isPointerType() ||
         !ArgType->getPointeeType().hasAddressSpace() ||
         isPtrSizeAddressSpace(ArgType->getPointeeType().getAddressSpace())) {
       OverloadParams.push_back(ParamType);
       continue;
     }
 
     QualType PointeeType = ParamType->getPointeeType();
     if (PointeeType.hasAddressSpace())
       continue;
 
     NeedsNewDecl = true;
     LangAS AS = ArgType->getPointeeType().getAddressSpace();
 
     PointeeType = Context.getAddrSpaceQualType(PointeeType, AS);
     OverloadParams.push_back(Context.getPointerType(PointeeType));
   }
 
   if (!NeedsNewDecl)
     return nullptr;
 
   FunctionProtoType::ExtProtoInfo EPI;
   EPI.Variadic = FT->isVariadic();
   QualType OverloadTy = Context.getFunctionType(FT->getReturnType(),
                                                 OverloadParams, EPI);
   DeclContext *Parent = FDecl->getParent();
   FunctionDecl *OverloadDecl = FunctionDecl::Create(
       Context, Parent, FDecl->getLocation(), FDecl->getLocation(),
       FDecl->getIdentifier(), OverloadTy,
       /*TInfo=*/nullptr, SC_Extern, Sema->getCurFPFeatures().isFPConstrained(),
       false,
       /*hasPrototype=*/true);
   SmallVector<ParmVarDecl*, 16> Params;
   FT = cast<FunctionProtoType>(OverloadTy);
   for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i) {
     QualType ParamType = FT->getParamType(i);
     ParmVarDecl *Parm =
         ParmVarDecl::Create(Context, OverloadDecl, SourceLocation(),
                                 SourceLocation(), nullptr, ParamType,
                                 /*TInfo=*/nullptr, SC_None, nullptr);
     Parm->setScopeInfo(0, i);
     Params.push_back(Parm);
   }
   OverloadDecl->setParams(Params);
   Sema->mergeDeclAttributes(OverloadDecl, FDecl);
   return OverloadDecl;
 }
 
 static void checkDirectCallValidity(Sema &S, const Expr *Fn,
                                     FunctionDecl *Callee,
                                     MultiExprArg ArgExprs) {
   // `Callee` (when called with ArgExprs) may be ill-formed. enable_if (and
   // similar attributes) really don't like it when functions are called with an
   // invalid number of args.
   if (S.TooManyArguments(Callee->getNumParams(), ArgExprs.size(),
                          /*PartialOverloading=*/false) &&
       !Callee->isVariadic())
     return;
   if (Callee->getMinRequiredArguments() > ArgExprs.size())
     return;
 
   if (const EnableIfAttr *Attr =
           S.CheckEnableIf(Callee, Fn->getBeginLoc(), ArgExprs, true)) {
     S.Diag(Fn->getBeginLoc(),
            isa<CXXMethodDecl>(Callee)
                ? diag::err_ovl_no_viable_member_function_in_call
                : diag::err_ovl_no_viable_function_in_call)
         << Callee << Callee->getSourceRange();
     S.Diag(Callee->getLocation(),
            diag::note_ovl_candidate_disabled_by_function_cond_attr)
         << Attr->getCond()->getSourceRange() << Attr->getMessage();
     return;
   }
 }
 
 static bool enclosingClassIsRelatedToClassInWhichMembersWereFound(
     const UnresolvedMemberExpr *const UME, Sema &S) {
 
   const auto GetFunctionLevelDCIfCXXClass =
       [](Sema &S) -> const CXXRecordDecl * {
     const DeclContext *const DC = S.getFunctionLevelDeclContext();
     if (!DC || !DC->getParent())
       return nullptr;
 
     // If the call to some member function was made from within a member
     // function body 'M' return return 'M's parent.
     if (const auto *MD = dyn_cast<CXXMethodDecl>(DC))
       return MD->getParent()->getCanonicalDecl();
     // else the call was made from within a default member initializer of a
     // class, so return the class.
     if (const auto *RD = dyn_cast<CXXRecordDecl>(DC))
       return RD->getCanonicalDecl();
     return nullptr;
   };
   // If our DeclContext is neither a member function nor a class (in the
   // case of a lambda in a default member initializer), we can't have an
   // enclosing 'this'.
 
   const CXXRecordDecl *const CurParentClass = GetFunctionLevelDCIfCXXClass(S);
   if (!CurParentClass)
     return false;
 
   // The naming class for implicit member functions call is the class in which
   // name lookup starts.
   const CXXRecordDecl *const NamingClass =
       UME->getNamingClass()->getCanonicalDecl();
   assert(NamingClass && "Must have naming class even for implicit access");
 
   // If the unresolved member functions were found in a 'naming class' that is
   // related (either the same or derived from) to the class that contains the
   // member function that itself contained the implicit member access.
 
   return CurParentClass == NamingClass ||
          CurParentClass->isDerivedFrom(NamingClass);
 }
 
 static void
 tryImplicitlyCaptureThisIfImplicitMemberFunctionAccessWithDependentArgs(
     Sema &S, const UnresolvedMemberExpr *const UME, SourceLocation CallLoc) {
 
   if (!UME)
     return;
 
   LambdaScopeInfo *const CurLSI = S.getCurLambda();
   // Only try and implicitly capture 'this' within a C++ Lambda if it hasn't
   // already been captured, or if this is an implicit member function call (if
   // it isn't, an attempt to capture 'this' should already have been made).
   if (!CurLSI || CurLSI->ImpCaptureStyle == CurLSI->ImpCap_None ||
       !UME->isImplicitAccess() || CurLSI->isCXXThisCaptured())
     return;
 
   // Check if the naming class in which the unresolved members were found is
   // related (same as or is a base of) to the enclosing class.
 
   if (!enclosingClassIsRelatedToClassInWhichMembersWereFound(UME, S))
     return;
 
 
   DeclContext *EnclosingFunctionCtx = S.CurContext->getParent()->getParent();
   // If the enclosing function is not dependent, then this lambda is
   // capture ready, so if we can capture this, do so.
   if (!EnclosingFunctionCtx->isDependentContext()) {
     // If the current lambda and all enclosing lambdas can capture 'this' -
     // then go ahead and capture 'this' (since our unresolved overload set
     // contains at least one non-static member function).
     if (!S.CheckCXXThisCapture(CallLoc, /*Explcit*/ false, /*Diagnose*/ false))
       S.CheckCXXThisCapture(CallLoc);
   } else if (S.CurContext->isDependentContext()) {
     // ... since this is an implicit member reference, that might potentially
     // involve a 'this' capture, mark 'this' for potential capture in
     // enclosing lambdas.
     if (CurLSI->ImpCaptureStyle != CurLSI->ImpCap_None)
       CurLSI->addPotentialThisCapture(CallLoc);
   }
 }
 
 // Once a call is fully resolved, warn for unqualified calls to specific
 // C++ standard functions, like move and forward.
 static void DiagnosedUnqualifiedCallsToStdFunctions(Sema &S, CallExpr *Call) {
   // We are only checking unary move and forward so exit early here.
   if (Call->getNumArgs() != 1)
     return;
 
   Expr *E = Call->getCallee()->IgnoreParenImpCasts();
   if (!E || isa<UnresolvedLookupExpr>(E))
     return;
   DeclRefExpr *DRE = dyn_cast_or_null<DeclRefExpr>(E);
   if (!DRE || !DRE->getLocation().isValid())
     return;
 
   if (DRE->getQualifier())
     return;
 
   const FunctionDecl *FD = Call->getDirectCallee();
   if (!FD)
     return;
 
   // Only warn for some functions deemed more frequent or problematic.
   unsigned BuiltinID = FD->getBuiltinID();
   if (BuiltinID != Builtin::BImove && BuiltinID != Builtin::BIforward)
     return;
 
   S.Diag(DRE->getLocation(), diag::warn_unqualified_call_to_std_cast_function)
       << FD->getQualifiedNameAsString()
       << FixItHint::CreateInsertion(DRE->getLocation(), "std::");
 }
 
 ExprResult Sema::ActOnCallExpr(Scope *Scope, Expr *Fn, SourceLocation LParenLoc,
                                MultiExprArg ArgExprs, SourceLocation RParenLoc,
                                Expr *ExecConfig) {
   ExprResult Call =
       BuildCallExpr(Scope, Fn, LParenLoc, ArgExprs, RParenLoc, ExecConfig,
                     /*IsExecConfig=*/false, /*AllowRecovery=*/true);
   if (Call.isInvalid())
     return Call;
 
   // Diagnose uses of the C++20 "ADL-only template-id call" feature in earlier
   // language modes.
   if (auto *ULE = dyn_cast<UnresolvedLookupExpr>(Fn)) {
     if (ULE->hasExplicitTemplateArgs() &&
         ULE->decls_begin() == ULE->decls_end()) {
       Diag(Fn->getExprLoc(), getLangOpts().CPlusPlus20
                                  ? diag::warn_cxx17_compat_adl_only_template_id
                                  : diag::ext_adl_only_template_id)
           << ULE->getName();
     }
   }
 
   if (LangOpts.OpenMP)
     Call = ActOnOpenMPCall(Call, Scope, LParenLoc, ArgExprs, RParenLoc,
                            ExecConfig);
   if (LangOpts.CPlusPlus) {
     CallExpr *CE = dyn_cast<CallExpr>(Call.get());
     if (CE)
       DiagnosedUnqualifiedCallsToStdFunctions(*this, CE);
   }
   return Call;
 }
 
 /// BuildCallExpr - Handle a call to Fn with the specified array of arguments.
 /// This provides the location of the left/right parens and a list of comma
 /// locations.
 ExprResult Sema::BuildCallExpr(Scope *Scope, Expr *Fn, SourceLocation LParenLoc,
                                MultiExprArg ArgExprs, SourceLocation RParenLoc,
                                Expr *ExecConfig, bool IsExecConfig,
                                bool AllowRecovery) {
   // Since this might be a postfix expression, get rid of ParenListExprs.
   ExprResult Result = MaybeConvertParenListExprToParenExpr(Scope, Fn);
   if (Result.isInvalid()) return ExprError();
   Fn = Result.get();
 
   if (checkArgsForPlaceholders(*this, ArgExprs))
     return ExprError();
 
   if (getLangOpts().CPlusPlus) {
     // If this is a pseudo-destructor expression, build the call immediately.
     if (isa<CXXPseudoDestructorExpr>(Fn)) {
       if (!ArgExprs.empty()) {
         // Pseudo-destructor calls should not have any arguments.
         Diag(Fn->getBeginLoc(), diag::err_pseudo_dtor_call_with_args)
             << FixItHint::CreateRemoval(
                    SourceRange(ArgExprs.front()->getBeginLoc(),
                                ArgExprs.back()->getEndLoc()));
       }
 
       return CallExpr::Create(Context, Fn, /*Args=*/{}, Context.VoidTy,
                               VK_PRValue, RParenLoc, CurFPFeatureOverrides());
     }
     if (Fn->getType() == Context.PseudoObjectTy) {
       ExprResult result = CheckPlaceholderExpr(Fn);
       if (result.isInvalid()) return ExprError();
       Fn = result.get();
     }
 
     // Determine whether this is a dependent call inside a C++ template,
     // in which case we won't do any semantic analysis now.
     if (Fn->isTypeDependent() || Expr::hasAnyTypeDependentArguments(ArgExprs)) {
       if (ExecConfig) {
         return CUDAKernelCallExpr::Create(Context, Fn,
                                           cast<CallExpr>(ExecConfig), ArgExprs,
                                           Context.DependentTy, VK_PRValue,
                                           RParenLoc, CurFPFeatureOverrides());
       } else {
 
         tryImplicitlyCaptureThisIfImplicitMemberFunctionAccessWithDependentArgs(
             *this, dyn_cast<UnresolvedMemberExpr>(Fn->IgnoreParens()),
             Fn->getBeginLoc());
 
         return CallExpr::Create(Context, Fn, ArgExprs, Context.DependentTy,
                                 VK_PRValue, RParenLoc, CurFPFeatureOverrides());
       }
     }
 
     // Determine whether this is a call to an object (C++ [over.call.object]).
     if (Fn->getType()->isRecordType())
       return BuildCallToObjectOfClassType(Scope, Fn, LParenLoc, ArgExprs,
                                           RParenLoc);
 
     if (Fn->getType() == Context.UnknownAnyTy) {
       ExprResult result = rebuildUnknownAnyFunction(*this, Fn);
       if (result.isInvalid()) return ExprError();
       Fn = result.get();
     }
 
     if (Fn->getType() == Context.BoundMemberTy) {
       return BuildCallToMemberFunction(Scope, Fn, LParenLoc, ArgExprs,
                                        RParenLoc, ExecConfig, IsExecConfig,
                                        AllowRecovery);
     }
   }
 
   // Check for overloaded calls.  This can happen even in C due to extensions.
   if (Fn->getType() == Context.OverloadTy) {
     OverloadExpr::FindResult find = OverloadExpr::find(Fn);
 
     // We aren't supposed to apply this logic if there's an '&' involved.
     if (!find.HasFormOfMemberPointer) {
       if (Expr::hasAnyTypeDependentArguments(ArgExprs))
         return CallExpr::Create(Context, Fn, ArgExprs, Context.DependentTy,
                                 VK_PRValue, RParenLoc, CurFPFeatureOverrides());
       OverloadExpr *ovl = find.Expression;
       if (UnresolvedLookupExpr *ULE = dyn_cast<UnresolvedLookupExpr>(ovl))
         return BuildOverloadedCallExpr(
             Scope, Fn, ULE, LParenLoc, ArgExprs, RParenLoc, ExecConfig,
             /*AllowTypoCorrection=*/true, find.IsAddressOfOperand);
       return BuildCallToMemberFunction(Scope, Fn, LParenLoc, ArgExprs,
                                        RParenLoc, ExecConfig, IsExecConfig,
                                        AllowRecovery);
     }
   }
 
   // If we're directly calling a function, get the appropriate declaration.
   if (Fn->getType() == Context.UnknownAnyTy) {
     ExprResult result = rebuildUnknownAnyFunction(*this, Fn);
     if (result.isInvalid()) return ExprError();
     Fn = result.get();
   }
 
   Expr *NakedFn = Fn->IgnoreParens();
 
   bool CallingNDeclIndirectly = false;
   NamedDecl *NDecl = nullptr;
   if (UnaryOperator *UnOp = dyn_cast<UnaryOperator>(NakedFn)) {
     if (UnOp->getOpcode() == UO_AddrOf) {
       CallingNDeclIndirectly = true;
       NakedFn = UnOp->getSubExpr()->IgnoreParens();
     }
   }
 
   if (auto *DRE = dyn_cast<DeclRefExpr>(NakedFn)) {
     NDecl = DRE->getDecl();
 
     FunctionDecl *FDecl = dyn_cast<FunctionDecl>(NDecl);
     if (FDecl && FDecl->getBuiltinID()) {
       // Rewrite the function decl for this builtin by replacing parameters
       // with no explicit address space with the address space of the arguments
       // in ArgExprs.
       if ((FDecl =
                rewriteBuiltinFunctionDecl(this, Context, FDecl, ArgExprs))) {
         NDecl = FDecl;
         Fn = DeclRefExpr::Create(
             Context, FDecl->getQualifierLoc(), SourceLocation(), FDecl, false,
             SourceLocation(), FDecl->getType(), Fn->getValueKind(), FDecl,
             nullptr, DRE->isNonOdrUse());
       }
     }
   } else if (auto *ME = dyn_cast<MemberExpr>(NakedFn))
     NDecl = ME->getMemberDecl();
 
   if (FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(NDecl)) {
     if (CallingNDeclIndirectly && !checkAddressOfFunctionIsAvailable(
                                       FD, /*Complain=*/true, Fn->getBeginLoc()))
       return ExprError();
 
     checkDirectCallValidity(*this, Fn, FD, ArgExprs);
 
     // If this expression is a call to a builtin function in HIP device
     // compilation, allow a pointer-type argument to default address space to be
     // passed as a pointer-type parameter to a non-default address space.
     // If Arg is declared in the default address space and Param is declared
     // in a non-default address space, perform an implicit address space cast to
     // the parameter type.
     if (getLangOpts().HIP && getLangOpts().CUDAIsDevice && FD &&
         FD->getBuiltinID()) {
       for (unsigned Idx = 0; Idx < FD->param_size(); ++Idx) {
         ParmVarDecl *Param = FD->getParamDecl(Idx);
         if (!ArgExprs[Idx] || !Param || !Param->getType()->isPointerType() ||
             !ArgExprs[Idx]->getType()->isPointerType())
           continue;
 
         auto ParamAS = Param->getType()->getPointeeType().getAddressSpace();
         auto ArgTy = ArgExprs[Idx]->getType();
         auto ArgPtTy = ArgTy->getPointeeType();
         auto ArgAS = ArgPtTy.getAddressSpace();
 
         // Add address space cast if target address spaces are different
         bool NeedImplicitASC =
           ParamAS != LangAS::Default &&       // Pointer params in generic AS don't need special handling.
           ( ArgAS == LangAS::Default  ||      // We do allow implicit conversion from generic AS
                                               // or from specific AS which has target AS matching that of Param.
           getASTContext().getTargetAddressSpace(ArgAS) == getASTContext().getTargetAddressSpace(ParamAS));
         if (!NeedImplicitASC)
           continue;
 
         // First, ensure that the Arg is an RValue.
         if (ArgExprs[Idx]->isGLValue()) {
           ArgExprs[Idx] = ImplicitCastExpr::Create(
               Context, ArgExprs[Idx]->getType(), CK_NoOp, ArgExprs[Idx],
               nullptr, VK_PRValue, FPOptionsOverride());
         }
 
         // Construct a new arg type with address space of Param
         Qualifiers ArgPtQuals = ArgPtTy.getQualifiers();
         ArgPtQuals.setAddressSpace(ParamAS);
         auto NewArgPtTy =
             Context.getQualifiedType(ArgPtTy.getUnqualifiedType(), ArgPtQuals);
         auto NewArgTy =
             Context.getQualifiedType(Context.getPointerType(NewArgPtTy),
                                      ArgTy.getQualifiers());
 
         // Finally perform an implicit address space cast
         ArgExprs[Idx] = ImpCastExprToType(ArgExprs[Idx], NewArgTy,
                                           CK_AddressSpaceConversion)
                             .get();
       }
     }
   }
 
   if (Context.isDependenceAllowed() &&
       (Fn->isTypeDependent() || Expr::hasAnyTypeDependentArguments(ArgExprs))) {
     assert(!getLangOpts().CPlusPlus);
     assert((Fn->containsErrors() ||
             llvm::any_of(ArgExprs,
                          [](clang::Expr *E) { return E->containsErrors(); })) &&
            "should only occur in error-recovery path.");
     return CallExpr::Create(Context, Fn, ArgExprs, Context.DependentTy,
                             VK_PRValue, RParenLoc, CurFPFeatureOverrides());
   }
   return BuildResolvedCallExpr(Fn, NDecl, LParenLoc, ArgExprs, RParenLoc,
                                ExecConfig, IsExecConfig);
 }
 
 /// BuildBuiltinCallExpr - Create a call to a builtin function specified by Id
 //  with the specified CallArgs
 Expr *Sema::BuildBuiltinCallExpr(SourceLocation Loc, Builtin::ID Id,
                                  MultiExprArg CallArgs) {
   StringRef Name = Context.BuiltinInfo.getName(Id);
   LookupResult R(*this, &Context.Idents.get(Name), Loc,
                  Sema::LookupOrdinaryName);
   LookupName(R, TUScope, /*AllowBuiltinCreation=*/true);
 
   auto *BuiltInDecl = R.getAsSingle<FunctionDecl>();
   assert(BuiltInDecl && "failed to find builtin declaration");
 
   ExprResult DeclRef =
       BuildDeclRefExpr(BuiltInDecl, BuiltInDecl->getType(), VK_LValue, Loc);
   assert(DeclRef.isUsable() && "Builtin reference cannot fail");
 
   ExprResult Call =
       BuildCallExpr(/*Scope=*/nullptr, DeclRef.get(), Loc, CallArgs, Loc);
 
   assert(!Call.isInvalid() && "Call to builtin cannot fail!");
   return Call.get();
 }
 
 /// Parse a __builtin_astype expression.
 ///
 /// __builtin_astype( value, dst type )
 ///
 ExprResult Sema::ActOnAsTypeExpr(Expr *E, ParsedType ParsedDestTy,
                                  SourceLocation BuiltinLoc,
                                  SourceLocation RParenLoc) {
   QualType DstTy = GetTypeFromParser(ParsedDestTy);
   return BuildAsTypeExpr(E, DstTy, BuiltinLoc, RParenLoc);
 }
 
 /// Create a new AsTypeExpr node (bitcast) from the arguments.
 ExprResult Sema::BuildAsTypeExpr(Expr *E, QualType DestTy,
                                  SourceLocation BuiltinLoc,
                                  SourceLocation RParenLoc) {
   ExprValueKind VK = VK_PRValue;
   ExprObjectKind OK = OK_Ordinary;
   QualType SrcTy = E->getType();
   if (!SrcTy->isDependentType() &&
       Context.getTypeSize(DestTy) != Context.getTypeSize(SrcTy))
     return ExprError(
         Diag(BuiltinLoc, diag::err_invalid_astype_of_different_size)
         << DestTy << SrcTy << E->getSourceRange());
   return new (Context) AsTypeExpr(E, DestTy, VK, OK, BuiltinLoc, RParenLoc);
 }
 
 /// ActOnConvertVectorExpr - create a new convert-vector expression from the
 /// provided arguments.
 ///
 /// __builtin_convertvector( value, dst type )
 ///
 ExprResult Sema::ActOnConvertVectorExpr(Expr *E, ParsedType ParsedDestTy,
                                         SourceLocation BuiltinLoc,
                                         SourceLocation RParenLoc) {
   TypeSourceInfo *TInfo;
   GetTypeFromParser(ParsedDestTy, &TInfo);
   return SemaConvertVectorExpr(E, TInfo, BuiltinLoc, RParenLoc);
 }
 
 /// BuildResolvedCallExpr - Build a call to a resolved expression,
 /// i.e. an expression not of \p OverloadTy.  The expression should
 /// unary-convert to an expression of function-pointer or
 /// block-pointer type.
 ///
 /// \param NDecl the declaration being called, if available
 ExprResult Sema::BuildResolvedCallExpr(Expr *Fn, NamedDecl *NDecl,
                                        SourceLocation LParenLoc,
                                        ArrayRef<Expr *> Args,
                                        SourceLocation RParenLoc, Expr *Config,
                                        bool IsExecConfig, ADLCallKind UsesADL) {
   FunctionDecl *FDecl = dyn_cast_or_null<FunctionDecl>(NDecl);
   unsigned BuiltinID = (FDecl ? FDecl->getBuiltinID() : 0);
 
   // Functions with 'interrupt' attribute cannot be called directly.
   if (FDecl && FDecl->hasAttr<AnyX86InterruptAttr>()) {
     Diag(Fn->getExprLoc(), diag::err_anyx86_interrupt_called);
     return ExprError();
   }
 
   // Interrupt handlers don't save off the VFP regs automatically on ARM,
   // so there's some risk when calling out to non-interrupt handler functions
   // that the callee might not preserve them. This is easy to diagnose here,
   // but can be very challenging to debug.
   // Likewise, X86 interrupt handlers may only call routines with attribute
   // no_caller_saved_registers since there is no efficient way to
   // save and restore the non-GPR state.
   if (auto *Caller = getCurFunctionDecl()) {
     if (Caller->hasAttr<ARMInterruptAttr>()) {
       bool VFP = Context.getTargetInfo().hasFeature("vfp");
       if (VFP && (!FDecl || !FDecl->hasAttr<ARMInterruptAttr>())) {
         Diag(Fn->getExprLoc(), diag::warn_arm_interrupt_calling_convention);
         if (FDecl)
           Diag(FDecl->getLocation(), diag::note_callee_decl) << FDecl;
       }
     }
     if (Caller->hasAttr<AnyX86InterruptAttr>() &&
         ((!FDecl || !FDecl->hasAttr<AnyX86NoCallerSavedRegistersAttr>()))) {
       Diag(Fn->getExprLoc(), diag::warn_anyx86_interrupt_regsave);
       if (FDecl)
         Diag(FDecl->getLocation(), diag::note_callee_decl) << FDecl;
     }
   }
 
   // Promote the function operand.
   // We special-case function promotion here because we only allow promoting
   // builtin functions to function pointers in the callee of a call.
   ExprResult Result;
   QualType ResultTy;
   if (BuiltinID &&
       Fn->getType()->isSpecificBuiltinType(BuiltinType::BuiltinFn)) {
     // Extract the return type from the (builtin) function pointer type.
     // FIXME Several builtins still have setType in
     // Sema::CheckBuiltinFunctionCall. One should review their definitions in
     // Builtins.def to ensure they are correct before removing setType calls.
     QualType FnPtrTy = Context.getPointerType(FDecl->getType());
     Result = ImpCastExprToType(Fn, FnPtrTy, CK_BuiltinFnToFnPtr).get();
     ResultTy = FDecl->getCallResultType();
   } else {
     Result = CallExprUnaryConversions(Fn);
     ResultTy = Context.BoolTy;
   }
   if (Result.isInvalid())
     return ExprError();
   Fn = Result.get();
 
   // Check for a valid function type, but only if it is not a builtin which
   // requires custom type checking. These will be handled by
   // CheckBuiltinFunctionCall below just after creation of the call expression.
   const FunctionType *FuncT = nullptr;
   if (!BuiltinID || !Context.BuiltinInfo.hasCustomTypechecking(BuiltinID)) {
   retry:
     if (const PointerType *PT = Fn->getType()->getAs<PointerType>()) {
       // C99 6.5.2.2p1 - "The expression that denotes the called function shall
       // have type pointer to function".
       FuncT = PT->getPointeeType()->getAs<FunctionType>();
       if (!FuncT)
         return ExprError(Diag(LParenLoc, diag::err_typecheck_call_not_function)
                          << Fn->getType() << Fn->getSourceRange());
     } else if (const BlockPointerType *BPT =
                    Fn->getType()->getAs<BlockPointerType>()) {
       FuncT = BPT->getPointeeType()->castAs<FunctionType>();
     } else {
       // Handle calls to expressions of unknown-any type.
       if (Fn->getType() == Context.UnknownAnyTy) {
         ExprResult rewrite = rebuildUnknownAnyFunction(*this, Fn);
         if (rewrite.isInvalid())
           return ExprError();
         Fn = rewrite.get();
         goto retry;
       }
 
       return ExprError(Diag(LParenLoc, diag::err_typecheck_call_not_function)
                        << Fn->getType() << Fn->getSourceRange());
     }
   }
 
   // Get the number of parameters in the function prototype, if any.
   // We will allocate space for max(Args.size(), NumParams) arguments
   // in the call expression.
   const auto *Proto = dyn_cast_or_null<FunctionProtoType>(FuncT);
   unsigned NumParams = Proto ? Proto->getNumParams() : 0;
 
   CallExpr *TheCall;
   if (Config) {
     assert(UsesADL == ADLCallKind::NotADL &&
            "CUDAKernelCallExpr should not use ADL");
     TheCall = CUDAKernelCallExpr::Create(Context, Fn, cast<CallExpr>(Config),
                                          Args, ResultTy, VK_PRValue, RParenLoc,
                                          CurFPFeatureOverrides(), NumParams);
   } else {
     TheCall =
         CallExpr::Create(Context, Fn, Args, ResultTy, VK_PRValue, RParenLoc,
                          CurFPFeatureOverrides(), NumParams, UsesADL);
   }
 
   if (!Context.isDependenceAllowed()) {
     // Forget about the nulled arguments since typo correction
     // do not handle them well.
     TheCall->shrinkNumArgs(Args.size());
     // C cannot always handle TypoExpr nodes in builtin calls and direct
     // function calls as their argument checking don't necessarily handle
     // dependent types properly, so make sure any TypoExprs have been
     // dealt with.
     ExprResult Result = CorrectDelayedTyposInExpr(TheCall);
     if (!Result.isUsable()) return ExprError();
     CallExpr *TheOldCall = TheCall;
     TheCall = dyn_cast<CallExpr>(Result.get());
     bool CorrectedTypos = TheCall != TheOldCall;
     if (!TheCall) return Result;
     Args = llvm::ArrayRef(TheCall->getArgs(), TheCall->getNumArgs());
 
     // A new call expression node was created if some typos were corrected.
     // However it may not have been constructed with enough storage. In this
     // case, rebuild the node with enough storage. The waste of space is
     // immaterial since this only happens when some typos were corrected.
     if (CorrectedTypos && Args.size() < NumParams) {
       if (Config)
         TheCall = CUDAKernelCallExpr::Create(
             Context, Fn, cast<CallExpr>(Config), Args, ResultTy, VK_PRValue,
             RParenLoc, CurFPFeatureOverrides(), NumParams);
       else
         TheCall =
             CallExpr::Create(Context, Fn, Args, ResultTy, VK_PRValue, RParenLoc,
                              CurFPFeatureOverrides(), NumParams, UsesADL);
     }
     // We can now handle the nulled arguments for the default arguments.
     TheCall->setNumArgsUnsafe(std::max<unsigned>(Args.size(), NumParams));
   }
 
   // Bail out early if calling a builtin with custom type checking.
   if (BuiltinID && Context.BuiltinInfo.hasCustomTypechecking(BuiltinID))
     return CheckBuiltinFunctionCall(FDecl, BuiltinID, TheCall);
 
   if (getLangOpts().CUDA) {
     if (Config) {
       // CUDA: Kernel calls must be to global functions
       if (FDecl && !FDecl->hasAttr<CUDAGlobalAttr>())
         return ExprError(Diag(LParenLoc,diag::err_kern_call_not_global_function)
             << FDecl << Fn->getSourceRange());
 
       // CUDA: Kernel function must have 'void' return type
       if (!FuncT->getReturnType()->isVoidType() &&
           !FuncT->getReturnType()->getAs<AutoType>() &&
           !FuncT->getReturnType()->isInstantiationDependentType())
         return ExprError(Diag(LParenLoc, diag::err_kern_type_not_void_return)
             << Fn->getType() << Fn->getSourceRange());
     } else {
       // CUDA: Calls to global functions must be configured
       if (FDecl && FDecl->hasAttr<CUDAGlobalAttr>())
         return ExprError(Diag(LParenLoc, diag::err_global_call_not_config)
             << FDecl << Fn->getSourceRange());
     }
   }
 
   // Check for a valid return type
   if (CheckCallReturnType(FuncT->getReturnType(), Fn->getBeginLoc(), TheCall,
                           FDecl))
     return ExprError();
 
   // We know the result type of the call, set it.
   TheCall->setType(FuncT->getCallResultType(Context));
   TheCall->setValueKind(Expr::getValueKindForType(FuncT->getReturnType()));
 
   // WebAssembly tables can't be used as arguments.
   if (Context.getTargetInfo().getTriple().isWasm()) {
     for (const Expr *Arg : Args) {
       if (Arg && Arg->getType()->isWebAssemblyTableType()) {
         return ExprError(Diag(Arg->getExprLoc(),
                               diag::err_wasm_table_as_function_parameter));
       }
     }
   }
 
   if (Proto) {
     if (ConvertArgumentsForCall(TheCall, Fn, FDecl, Proto, Args, RParenLoc,
                                 IsExecConfig))
       return ExprError();
   } else {
     assert(isa<FunctionNoProtoType>(FuncT) && "Unknown FunctionType!");
 
     if (FDecl) {
       // Check if we have too few/too many template arguments, based
       // on our knowledge of the function definition.
       const FunctionDecl *Def = nullptr;
       if (FDecl->hasBody(Def) && Args.size() != Def->param_size()) {
         Proto = Def->getType()->getAs<FunctionProtoType>();
        if (!Proto || !(Proto->isVariadic() && Args.size() >= Def->param_size()))
           Diag(RParenLoc, diag::warn_call_wrong_number_of_arguments)
           << (Args.size() > Def->param_size()) << FDecl << Fn->getSourceRange();
       }
 
       // If the function we're calling isn't a function prototype, but we have
       // a function prototype from a prior declaratiom, use that prototype.
       if (!FDecl->hasPrototype())
         Proto = FDecl->getType()->getAs<FunctionProtoType>();
     }
 
     // If we still haven't found a prototype to use but there are arguments to
     // the call, diagnose this as calling a function without a prototype.
     // However, if we found a function declaration, check to see if
     // -Wdeprecated-non-prototype was disabled where the function was declared.
     // If so, we will silence the diagnostic here on the assumption that this
     // interface is intentional and the user knows what they're doing. We will
     // also silence the diagnostic if there is a function declaration but it
     // was implicitly defined (the user already gets diagnostics about the
     // creation of the implicit function declaration, so the additional warning
     // is not helpful).
     if (!Proto && !Args.empty() &&
         (!FDecl || (!FDecl->isImplicit() &&
                     !Diags.isIgnored(diag::warn_strict_uses_without_prototype,
                                      FDecl->getLocation()))))
       Diag(LParenLoc, diag::warn_strict_uses_without_prototype)
           << (FDecl != nullptr) << FDecl;
 
     // Promote the arguments (C99 6.5.2.2p6).
     for (unsigned i = 0, e = Args.size(); i != e; i++) {
       Expr *Arg = Args[i];
 
       if (Proto && i < Proto->getNumParams()) {
         InitializedEntity Entity = InitializedEntity::InitializeParameter(
             Context, Proto->getParamType(i), Proto->isParamConsumed(i));
         ExprResult ArgE =
             PerformCopyInitialization(Entity, SourceLocation(), Arg);
         if (ArgE.isInvalid())
           return true;
 
         Arg = ArgE.getAs<Expr>();
 
       } else {
         ExprResult ArgE = DefaultArgumentPromotion(Arg);
 
         if (ArgE.isInvalid())
           return true;
 
         Arg = ArgE.getAs<Expr>();
       }
 
       if (RequireCompleteType(Arg->getBeginLoc(), Arg->getType(),
                               diag::err_call_incomplete_argument, Arg))
         return ExprError();
 
       TheCall->setArg(i, Arg);
     }
     TheCall->computeDependence();
   }
 
   if (CXXMethodDecl *Method = dyn_cast_or_null<CXXMethodDecl>(FDecl))
     if (!Method->isStatic())
       return ExprError(Diag(LParenLoc, diag::err_member_call_without_object)
         << Fn->getSourceRange());
 
   // Check for sentinels
   if (NDecl)
     DiagnoseSentinelCalls(NDecl, LParenLoc, Args);
 
   // Warn for unions passing across security boundary (CMSE).
   if (FuncT != nullptr && FuncT->getCmseNSCallAttr()) {
     for (unsigned i = 0, e = Args.size(); i != e; i++) {
       if (const auto *RT =
               dyn_cast<RecordType>(Args[i]->getType().getCanonicalType())) {
         if (RT->getDecl()->isOrContainsUnion())
           Diag(Args[i]->getBeginLoc(), diag::warn_cmse_nonsecure_union)
               << 0 << i;
       }
     }
   }
 
   // Do special checking on direct calls to functions.
   if (FDecl) {
     if (CheckFunctionCall(FDecl, TheCall, Proto))
       return ExprError();
 
     checkFortifiedBuiltinMemoryFunction(FDecl, TheCall);
 
     if (BuiltinID)
       return CheckBuiltinFunctionCall(FDecl, BuiltinID, TheCall);
   } else if (NDecl) {
     if (CheckPointerCall(NDecl, TheCall, Proto))
       return ExprError();
   } else {
     if (CheckOtherCall(TheCall, Proto))
       return ExprError();
   }
 
   return CheckForImmediateInvocation(MaybeBindToTemporary(TheCall), FDecl);
 }
 
 ExprResult
 Sema::ActOnCompoundLiteral(SourceLocation LParenLoc, ParsedType Ty,
                            SourceLocation RParenLoc, Expr *InitExpr) {
   assert(Ty && "ActOnCompoundLiteral(): missing type");
   assert(InitExpr && "ActOnCompoundLiteral(): missing expression");
 
   TypeSourceInfo *TInfo;
   QualType literalType = GetTypeFromParser(Ty, &TInfo);
   if (!TInfo)
     TInfo = Context.getTrivialTypeSourceInfo(literalType);
 
   return BuildCompoundLiteralExpr(LParenLoc, TInfo, RParenLoc, InitExpr);
 }
 
 ExprResult
 Sema::BuildCompoundLiteralExpr(SourceLocation LParenLoc, TypeSourceInfo *TInfo,
                                SourceLocation RParenLoc, Expr *LiteralExpr) {
   QualType literalType = TInfo->getType();
 
   if (literalType->isArrayType()) {
     if (RequireCompleteSizedType(
             LParenLoc, Context.getBaseElementType(literalType),
             diag::err_array_incomplete_or_sizeless_type,
             SourceRange(LParenLoc, LiteralExpr->getSourceRange().getEnd())))
       return ExprError();
     if (literalType->isVariableArrayType()) {
       // C2x 6.7.9p4: An entity of variable length array type shall not be
       // initialized except by an empty initializer.
       //
       // The C extension warnings are issued from ParseBraceInitializer() and
       // do not need to be issued here. However, we continue to issue an error
       // in the case there are initializers or we are compiling C++. We allow
       // use of VLAs in C++, but it's not clear we want to allow {} to zero
       // init a VLA in C++ in all cases (such as with non-trivial constructors).
       // FIXME: should we allow this construct in C++ when it makes sense to do
       // so?
       std::optional<unsigned> NumInits;
       if (const auto *ILE = dyn_cast<InitListExpr>(LiteralExpr))
         NumInits = ILE->getNumInits();
       if ((LangOpts.CPlusPlus || NumInits.value_or(0)) &&
           !tryToFixVariablyModifiedVarType(TInfo, literalType, LParenLoc,
                                            diag::err_variable_object_no_init))
         return ExprError();
     }
   } else if (!literalType->isDependentType() &&
              RequireCompleteType(LParenLoc, literalType,
                diag::err_typecheck_decl_incomplete_type,
                SourceRange(LParenLoc, LiteralExpr->getSourceRange().getEnd())))
     return ExprError();
 
   InitializedEntity Entity
     = InitializedEntity::InitializeCompoundLiteralInit(TInfo);
   InitializationKind Kind
     = InitializationKind::CreateCStyleCast(LParenLoc,
                                            SourceRange(LParenLoc, RParenLoc),
                                            /*InitList=*/true);
   InitializationSequence InitSeq(*this, Entity, Kind, LiteralExpr);
   ExprResult Result = InitSeq.Perform(*this, Entity, Kind, LiteralExpr,
                                       &literalType);
   if (Result.isInvalid())
     return ExprError();
   LiteralExpr = Result.get();
 
   bool isFileScope = !CurContext->isFunctionOrMethod();
 
   // In C, compound literals are l-values for some reason.
   // For GCC compatibility, in C++, file-scope array compound literals with
   // constant initializers are also l-values, and compound literals are
   // otherwise prvalues.
   //
   // (GCC also treats C++ list-initialized file-scope array prvalues with
   // constant initializers as l-values, but that's non-conforming, so we don't
   // follow it there.)
   //
   // FIXME: It would be better to handle the lvalue cases as materializing and
   // lifetime-extending a temporary object, but our materialized temporaries
   // representation only supports lifetime extension from a variable, not "out
   // of thin air".
   // FIXME: For C++, we might want to instead lifetime-extend only if a pointer
   // is bound to the result of applying array-to-pointer decay to the compound
   // literal.
   // FIXME: GCC supports compound literals of reference type, which should
   // obviously have a value kind derived from the kind of reference involved.
   ExprValueKind VK =
       (getLangOpts().CPlusPlus && !(isFileScope && literalType->isArrayType()))
           ? VK_PRValue
           : VK_LValue;
 
   if (isFileScope)
     if (auto ILE = dyn_cast<InitListExpr>(LiteralExpr))
       for (unsigned i = 0, j = ILE->getNumInits(); i != j; i++) {
         Expr *Init = ILE->getInit(i);
         ILE->setInit(i, ConstantExpr::Create(Context, Init));
       }
 
   auto *E = new (Context) CompoundLiteralExpr(LParenLoc, TInfo, literalType,
                                               VK, LiteralExpr, isFileScope);
   if (isFileScope) {
     if (!LiteralExpr->isTypeDependent() &&
         !LiteralExpr->isValueDependent() &&
         !literalType->isDependentType()) // C99 6.5.2.5p3
       if (CheckForConstantInitializer(LiteralExpr, literalType))
         return ExprError();
   } else if (literalType.getAddressSpace() != LangAS::opencl_private &&
              literalType.getAddressSpace() != LangAS::Default) {
     // Embedded-C extensions to C99 6.5.2.5:
     //   "If the compound literal occurs inside the body of a function, the
     //   type name shall not be qualified by an address-space qualifier."
     Diag(LParenLoc, diag::err_compound_literal_with_address_space)
       << SourceRange(LParenLoc, LiteralExpr->getSourceRange().getEnd());
     return ExprError();
   }
 
   if (!isFileScope && !getLangOpts().CPlusPlus) {
     // Compound literals that have automatic storage duration are destroyed at
     // the end of the scope in C; in C++, they're just temporaries.
 
     // Emit diagnostics if it is or contains a C union type that is non-trivial
     // to destruct.
     if (E->getType().hasNonTrivialToPrimitiveDestructCUnion())
       checkNonTrivialCUnion(E->getType(), E->getExprLoc(),
                             NTCUC_CompoundLiteral, NTCUK_Destruct);
 
     // Diagnose jumps that enter or exit the lifetime of the compound literal.
     if (literalType.isDestructedType()) {
       Cleanup.setExprNeedsCleanups(true);
       ExprCleanupObjects.push_back(E);
       getCurFunction()->setHasBranchProtectedScope();
     }
   }
 
   if (E->getType().hasNonTrivialToPrimitiveDefaultInitializeCUnion() ||
       E->getType().hasNonTrivialToPrimitiveCopyCUnion())
     checkNonTrivialCUnionInInitializer(E->getInitializer(),
                                        E->getInitializer()->getExprLoc());
 
   return MaybeBindToTemporary(E);
 }
 
 ExprResult
 Sema::ActOnInitList(SourceLocation LBraceLoc, MultiExprArg InitArgList,
                     SourceLocation RBraceLoc) {
   // Only produce each kind of designated initialization diagnostic once.
   SourceLocation FirstDesignator;
   bool DiagnosedArrayDesignator = false;
   bool DiagnosedNestedDesignator = false;
   bool DiagnosedMixedDesignator = false;
 
   // Check that any designated initializers are syntactically valid in the
   // current language mode.
   for (unsigned I = 0, E = InitArgList.size(); I != E; ++I) {
     if (auto *DIE = dyn_cast<DesignatedInitExpr>(InitArgList[I])) {
       if (FirstDesignator.isInvalid())
         FirstDesignator = DIE->getBeginLoc();
 
       if (!getLangOpts().CPlusPlus)
         break;
 
       if (!DiagnosedNestedDesignator && DIE->size() > 1) {
         DiagnosedNestedDesignator = true;
         Diag(DIE->getBeginLoc(), diag::ext_designated_init_nested)
           << DIE->getDesignatorsSourceRange();
       }
 
       for (auto &Desig : DIE->designators()) {
         if (!Desig.isFieldDesignator() && !DiagnosedArrayDesignator) {
           DiagnosedArrayDesignator = true;
           Diag(Desig.getBeginLoc(), diag::ext_designated_init_array)
             << Desig.getSourceRange();
         }
       }
 
       if (!DiagnosedMixedDesignator &&
           !isa<DesignatedInitExpr>(InitArgList[0])) {
         DiagnosedMixedDesignator = true;
         Diag(DIE->getBeginLoc(), diag::ext_designated_init_mixed)
           << DIE->getSourceRange();
         Diag(InitArgList[0]->getBeginLoc(), diag::note_designated_init_mixed)
           << InitArgList[0]->getSourceRange();
       }
     } else if (getLangOpts().CPlusPlus && !DiagnosedMixedDesignator &&
                isa<DesignatedInitExpr>(InitArgList[0])) {
       DiagnosedMixedDesignator = true;
       auto *DIE = cast<DesignatedInitExpr>(InitArgList[0]);
       Diag(DIE->getBeginLoc(), diag::ext_designated_init_mixed)
         << DIE->getSourceRange();
       Diag(InitArgList[I]->getBeginLoc(), diag::note_designated_init_mixed)
         << InitArgList[I]->getSourceRange();
     }
   }
 
   if (FirstDesignator.isValid()) {
     // Only diagnose designated initiaization as a C++20 extension if we didn't
     // already diagnose use of (non-C++20) C99 designator syntax.
     if (getLangOpts().CPlusPlus && !DiagnosedArrayDesignator &&
         !DiagnosedNestedDesignator && !DiagnosedMixedDesignator) {
       Diag(FirstDesignator, getLangOpts().CPlusPlus20
                                 ? diag::warn_cxx17_compat_designated_init
                                 : diag::ext_cxx_designated_init);
     } else if (!getLangOpts().CPlusPlus && !getLangOpts().C99) {
       Diag(FirstDesignator, diag::ext_designated_init);
     }
   }
 
   return BuildInitList(LBraceLoc, InitArgList, RBraceLoc);
 }
 
 ExprResult
 Sema::BuildInitList(SourceLocation LBraceLoc, MultiExprArg InitArgList,
                     SourceLocation RBraceLoc) {
   // Semantic analysis for initializers is done by ActOnDeclarator() and
   // CheckInitializer() - it requires knowledge of the object being initialized.
 
   // Immediately handle non-overload placeholders.  Overloads can be
   // resolved contextually, but everything else here can't.
   for (unsigned I = 0, E = InitArgList.size(); I != E; ++I) {
     if (InitArgList[I]->getType()->isNonOverloadPlaceholderType()) {
       ExprResult result = CheckPlaceholderExpr(InitArgList[I]);
 
       // Ignore failures; dropping the entire initializer list because
       // of one failure would be terrible for indexing/etc.
       if (result.isInvalid()) continue;
 
       InitArgList[I] = result.get();
     }
   }
 
   InitListExpr *E = new (Context) InitListExpr(Context, LBraceLoc, InitArgList,
                                                RBraceLoc);
   E->setType(Context.VoidTy); // FIXME: just a place holder for now.
   return E;
 }
 
 /// Do an explicit extend of the given block pointer if we're in ARC.
 void Sema::maybeExtendBlockObject(ExprResult &E) {
   assert(E.get()->getType()->isBlockPointerType());
   assert(E.get()->isPRValue());
 
   // Only do this in an r-value context.
   if (!getLangOpts().ObjCAutoRefCount) return;
 
   E = ImplicitCastExpr::Create(
       Context, E.get()->getType(), CK_ARCExtendBlockObject, E.get(),
       /*base path*/ nullptr, VK_PRValue, FPOptionsOverride());
   Cleanup.setExprNeedsCleanups(true);
 }
 
 /// Prepare a conversion of the given expression to an ObjC object
 /// pointer type.
 CastKind Sema::PrepareCastToObjCObjectPointer(ExprResult &E) {
   QualType type = E.get()->getType();
   if (type->isObjCObjectPointerType()) {
     return CK_BitCast;
   } else if (type->isBlockPointerType()) {
     maybeExtendBlockObject(E);
     return CK_BlockPointerToObjCPointerCast;
   } else {
     assert(type->isPointerType());
     return CK_CPointerToObjCPointerCast;
   }
 }
 
 /// Prepares for a scalar cast, performing all the necessary stages
 /// except the final cast and returning the kind required.
 CastKind Sema::PrepareScalarCast(ExprResult &Src, QualType DestTy) {
   // Both Src and Dest are scalar types, i.e. arithmetic or pointer.
   // Also, callers should have filtered out the invalid cases with
   // pointers.  Everything else should be possible.
 
   QualType SrcTy = Src.get()->getType();
   if (Context.hasSameUnqualifiedType(SrcTy, DestTy))
     return CK_NoOp;
 
   switch (Type::ScalarTypeKind SrcKind = SrcTy->getScalarTypeKind()) {
   case Type::STK_MemberPointer:
     llvm_unreachable("member pointer type in C");
 
   case Type::STK_CPointer:
   case Type::STK_BlockPointer:
   case Type::STK_ObjCObjectPointer:
     switch (DestTy->getScalarTypeKind()) {
     case Type::STK_CPointer: {
       LangAS SrcAS = SrcTy->getPointeeType().getAddressSpace();
       LangAS DestAS = DestTy->getPointeeType().getAddressSpace();
       if (SrcAS != DestAS)
         return CK_AddressSpaceConversion;
       if (Context.hasCvrSimilarType(SrcTy, DestTy))
         return CK_NoOp;
       return CK_BitCast;
     }
     case Type::STK_BlockPointer:
       return (SrcKind == Type::STK_BlockPointer
                 ? CK_BitCast : CK_AnyPointerToBlockPointerCast);
     case Type::STK_ObjCObjectPointer:
       if (SrcKind == Type::STK_ObjCObjectPointer)
         return CK_BitCast;
       if (SrcKind == Type::STK_CPointer)
         return CK_CPointerToObjCPointerCast;
       maybeExtendBlockObject(Src);
       return CK_BlockPointerToObjCPointerCast;
     case Type::STK_Bool:
       return CK_PointerToBoolean;
     case Type::STK_Integral:
       return CK_PointerToIntegral;
     case Type::STK_Floating:
     case Type::STK_FloatingComplex:
     case Type::STK_IntegralComplex:
     case Type::STK_MemberPointer:
     case Type::STK_FixedPoint:
       llvm_unreachable("illegal cast from pointer");
     }
     llvm_unreachable("Should have returned before this");
 
   case Type::STK_FixedPoint:
     switch (DestTy->getScalarTypeKind()) {
     case Type::STK_FixedPoint:
       return CK_FixedPointCast;
     case Type::STK_Bool:
       return CK_FixedPointToBoolean;
     case Type::STK_Integral:
       return CK_FixedPointToIntegral;
     case Type::STK_Floating:
       return CK_FixedPointToFloating;
     case Type::STK_IntegralComplex:
     case Type::STK_FloatingComplex:
       Diag(Src.get()->getExprLoc(),
            diag::err_unimplemented_conversion_with_fixed_point_type)
           << DestTy;
       return CK_IntegralCast;
     case Type::STK_CPointer:
     case Type::STK_ObjCObjectPointer:
     case Type::STK_BlockPointer:
     case Type::STK_MemberPointer:
       llvm_unreachable("illegal cast to pointer type");
     }
     llvm_unreachable("Should have returned before this");
 
   case Type::STK_Bool: // casting from bool is like casting from an integer
   case Type::STK_Integral:
     switch (DestTy->getScalarTypeKind()) {
     case Type::STK_CPointer:
     case Type::STK_ObjCObjectPointer:
     case Type::STK_BlockPointer:
       if (Src.get()->isNullPointerConstant(Context,
                                            Expr::NPC_ValueDependentIsNull))
         return CK_NullToPointer;
       return CK_IntegralToPointer;
     case Type::STK_Bool:
       return CK_IntegralToBoolean;
     case Type::STK_Integral:
       return CK_IntegralCast;
     case Type::STK_Floating:
       return CK_IntegralToFloating;
     case Type::STK_IntegralComplex:
       Src = ImpCastExprToType(Src.get(),
                       DestTy->castAs<ComplexType>()->getElementType(),
                       CK_IntegralCast);
       return CK_IntegralRealToComplex;
     case Type::STK_FloatingComplex:
       Src = ImpCastExprToType(Src.get(),
                       DestTy->castAs<ComplexType>()->getElementType(),
                       CK_IntegralToFloating);
       return CK_FloatingRealToComplex;
     case Type::STK_MemberPointer:
       llvm_unreachable("member pointer type in C");
     case Type::STK_FixedPoint:
       return CK_IntegralToFixedPoint;
     }
     llvm_unreachable("Should have returned before this");
 
   case Type::STK_Floating:
     switch (DestTy->getScalarTypeKind()) {
     case Type::STK_Floating:
       return CK_FloatingCast;
     case Type::STK_Bool:
       return CK_FloatingToBoolean;
     case Type::STK_Integral:
       return CK_FloatingToIntegral;
     case Type::STK_FloatingComplex:
       Src = ImpCastExprToType(Src.get(),
                               DestTy->castAs<ComplexType>()->getElementType(),
                               CK_FloatingCast);
       return CK_FloatingRealToComplex;
     case Type::STK_IntegralComplex:
       Src = ImpCastExprToType(Src.get(),
                               DestTy->castAs<ComplexType>()->getElementType(),
                               CK_FloatingToIntegral);
       return CK_IntegralRealToComplex;
     case Type::STK_CPointer:
     case Type::STK_ObjCObjectPointer:
     case Type::STK_BlockPointer:
       llvm_unreachable("valid float->pointer cast?");
     case Type::STK_MemberPointer:
       llvm_unreachable("member pointer type in C");
     case Type::STK_FixedPoint:
       return CK_FloatingToFixedPoint;
     }
     llvm_unreachable("Should have returned before this");
 
   case Type::STK_FloatingComplex:
     switch (DestTy->getScalarTypeKind()) {
     case Type::STK_FloatingComplex:
       return CK_FloatingComplexCast;
     case Type::STK_IntegralComplex:
       return CK_FloatingComplexToIntegralComplex;
     case Type::STK_Floating: {
       QualType ET = SrcTy->castAs<ComplexType>()->getElementType();
       if (Context.hasSameType(ET, DestTy))
         return CK_FloatingComplexToReal;
       Src = ImpCastExprToType(Src.get(), ET, CK_FloatingComplexToReal);
       return CK_FloatingCast;
     }
     case Type::STK_Bool:
       return CK_FloatingComplexToBoolean;
     case Type::STK_Integral:
       Src = ImpCastExprToType(Src.get(),
                               SrcTy->castAs<ComplexType>()->getElementType(),
                               CK_FloatingComplexToReal);
       return CK_FloatingToIntegral;
     case Type::STK_CPointer:
     case Type::STK_ObjCObjectPointer:
     case Type::STK_BlockPointer:
       llvm_unreachable("valid complex float->pointer cast?");
     case Type::STK_MemberPointer:
       llvm_unreachable("member pointer type in C");
     case Type::STK_FixedPoint:
       Diag(Src.get()->getExprLoc(),
            diag::err_unimplemented_conversion_with_fixed_point_type)
           << SrcTy;
       return CK_IntegralCast;
     }
     llvm_unreachable("Should have returned before this");
 
   case Type::STK_IntegralComplex:
     switch (DestTy->getScalarTypeKind()) {
     case Type::STK_FloatingComplex:
       return CK_IntegralComplexToFloatingComplex;
     case Type::STK_IntegralComplex:
       return CK_IntegralComplexCast;
     case Type::STK_Integral: {
       QualType ET = SrcTy->castAs<ComplexType>()->getElementType();
       if (Context.hasSameType(ET, DestTy))
         return CK_IntegralComplexToReal;
       Src = ImpCastExprToType(Src.get(), ET, CK_IntegralComplexToReal);
       return CK_IntegralCast;
     }
     case Type::STK_Bool:
       return CK_IntegralComplexToBoolean;
     case Type::STK_Floating:
       Src = ImpCastExprToType(Src.get(),
                               SrcTy->castAs<ComplexType>()->getElementType(),
                               CK_IntegralComplexToReal);
       return CK_IntegralToFloating;
     case Type::STK_CPointer:
     case Type::STK_ObjCObjectPointer:
     case Type::STK_BlockPointer:
       llvm_unreachable("valid complex int->pointer cast?");
     case Type::STK_MemberPointer:
       llvm_unreachable("member pointer type in C");
     case Type::STK_FixedPoint:
       Diag(Src.get()->getExprLoc(),
            diag::err_unimplemented_conversion_with_fixed_point_type)
           << SrcTy;
       return CK_IntegralCast;
     }
     llvm_unreachable("Should have returned before this");
   }
 
   llvm_unreachable("Unhandled scalar cast");
 }
 
 static bool breakDownVectorType(QualType type, uint64_t &len,
                                 QualType &eltType) {
   // Vectors are simple.
   if (const VectorType *vecType = type->getAs<VectorType>()) {
     len = vecType->getNumElements();
     eltType = vecType->getElementType();
     assert(eltType->isScalarType());
     return true;
   }
 
   // We allow lax conversion to and from non-vector types, but only if
   // they're real types (i.e. non-complex, non-pointer scalar types).
   if (!type->isRealType()) return false;
 
   len = 1;
   eltType = type;
   return true;
 }
 
 /// Are the two types SVE-bitcast-compatible types? I.e. is bitcasting from the
 /// first SVE type (e.g. an SVE VLAT) to the second type (e.g. an SVE VLST)
 /// allowed?
 ///
 /// This will also return false if the two given types do not make sense from
 /// the perspective of SVE bitcasts.
 bool Sema::isValidSveBitcast(QualType srcTy, QualType destTy) {
   assert(srcTy->isVectorType() || destTy->isVectorType());
 
   auto ValidScalableConversion = [](QualType FirstType, QualType SecondType) {
     if (!FirstType->isSVESizelessBuiltinType())
       return false;
 
     const auto *VecTy = SecondType->getAs<VectorType>();
     return VecTy &&
            VecTy->getVectorKind() == VectorType::SveFixedLengthDataVector;
   };
 
   return ValidScalableConversion(srcTy, destTy) ||
          ValidScalableConversion(destTy, srcTy);
 }
 
 /// Are the two types RVV-bitcast-compatible types? I.e. is bitcasting from the
 /// first RVV type (e.g. an RVV scalable type) to the second type (e.g. an RVV
 /// VLS type) allowed?
 ///
 /// This will also return false if the two given types do not make sense from
 /// the perspective of RVV bitcasts.
 bool Sema::isValidRVVBitcast(QualType srcTy, QualType destTy) {
   assert(srcTy->isVectorType() || destTy->isVectorType());
 
   auto ValidScalableConversion = [](QualType FirstType, QualType SecondType) {
     if (!FirstType->isRVVSizelessBuiltinType())
       return false;
 
     const auto *VecTy = SecondType->getAs<VectorType>();
     return VecTy &&
            VecTy->getVectorKind() == VectorType::RVVFixedLengthDataVector;
   };
 
   return ValidScalableConversion(srcTy, destTy) ||
          ValidScalableConversion(destTy, srcTy);
 }
 
 /// Are the two types matrix types and do they have the same dimensions i.e.
 /// do they have the same number of rows and the same number of columns?
 bool Sema::areMatrixTypesOfTheSameDimension(QualType srcTy, QualType destTy) {
   if (!destTy->isMatrixType() || !srcTy->isMatrixType())
     return false;
 
   const ConstantMatrixType *matSrcType = srcTy->getAs<ConstantMatrixType>();
   const ConstantMatrixType *matDestType = destTy->getAs<ConstantMatrixType>();
 
   return matSrcType->getNumRows() == matDestType->getNumRows() &&
          matSrcType->getNumColumns() == matDestType->getNumColumns();
 }
 
 bool Sema::areVectorTypesSameSize(QualType SrcTy, QualType DestTy) {
   assert(DestTy->isVectorType() || SrcTy->isVectorType());
 
   uint64_t SrcLen, DestLen;
   QualType SrcEltTy, DestEltTy;
   if (!breakDownVectorType(SrcTy, SrcLen, SrcEltTy))
     return false;
   if (!breakDownVectorType(DestTy, DestLen, DestEltTy))
     return false;
 
   // ASTContext::getTypeSize will return the size rounded up to a
   // power of 2, so instead of using that, we need to use the raw
   // element size multiplied by the element count.
   uint64_t SrcEltSize = Context.getTypeSize(SrcEltTy);
   uint64_t DestEltSize = Context.getTypeSize(DestEltTy);
 
   return (SrcLen * SrcEltSize == DestLen * DestEltSize);
 }
 
 // This returns true if at least one of the types is an altivec vector.
 bool Sema::anyAltivecTypes(QualType SrcTy, QualType DestTy) {
   assert((DestTy->isVectorType() || SrcTy->isVectorType()) &&
          "expected at least one type to be a vector here");
 
   bool IsSrcTyAltivec =
       SrcTy->isVectorType() && ((SrcTy->castAs<VectorType>()->getVectorKind() ==
                                  VectorType::AltiVecVector) ||
                                 (SrcTy->castAs<VectorType>()->getVectorKind() ==
                                  VectorType::AltiVecBool) ||
                                 (SrcTy->castAs<VectorType>()->getVectorKind() ==
                                  VectorType::AltiVecPixel));
 
   bool IsDestTyAltivec = DestTy->isVectorType() &&
                          ((DestTy->castAs<VectorType>()->getVectorKind() ==
                            VectorType::AltiVecVector) ||
                           (DestTy->castAs<VectorType>()->getVectorKind() ==
                            VectorType::AltiVecBool) ||
                           (DestTy->castAs<VectorType>()->getVectorKind() ==
                            VectorType::AltiVecPixel));
 
   return (IsSrcTyAltivec || IsDestTyAltivec);
 }
 
 /// Are the two types lax-compatible vector types?  That is, given
 /// that one of them is a vector, do they have equal storage sizes,
 /// where the storage size is the number of elements times the element
 /// size?
 ///
 /// This will also return false if either of the types is neither a
 /// vector nor a real type.
 bool Sema::areLaxCompatibleVectorTypes(QualType srcTy, QualType destTy) {
   assert(destTy->isVectorType() || srcTy->isVectorType());
 
   // Disallow lax conversions between scalars and ExtVectors (these
   // conversions are allowed for other vector types because common headers
   // depend on them).  Most scalar OP ExtVector cases are handled by the
   // splat path anyway, which does what we want (convert, not bitcast).
   // What this rules out for ExtVectors is crazy things like char4*float.
   if (srcTy->isScalarType() && destTy->isExtVectorType()) return false;
   if (destTy->isScalarType() && srcTy->isExtVectorType()) return false;
 
   return areVectorTypesSameSize(srcTy, destTy);
 }
 
 /// Is this a legal conversion between two types, one of which is
 /// known to be a vector type?
 bool Sema::isLaxVectorConversion(QualType srcTy, QualType destTy) {
   assert(destTy->isVectorType() || srcTy->isVectorType());
 
   switch (Context.getLangOpts().getLaxVectorConversions()) {
   case LangOptions::LaxVectorConversionKind::None:
     return false;
 
   case LangOptions::LaxVectorConversionKind::Integer:
     if (!srcTy->isIntegralOrEnumerationType()) {
       auto *Vec = srcTy->getAs<VectorType>();
       if (!Vec || !Vec->getElementType()->isIntegralOrEnumerationType())
         return false;
     }
     if (!destTy->isIntegralOrEnumerationType()) {
       auto *Vec = destTy->getAs<VectorType>();
       if (!Vec || !Vec->getElementType()->isIntegralOrEnumerationType())
         return false;
     }
     // OK, integer (vector) -> integer (vector) bitcast.
     break;
 
     case LangOptions::LaxVectorConversionKind::All:
     break;
   }
 
   return areLaxCompatibleVectorTypes(srcTy, destTy);
 }
 
 bool Sema::CheckMatrixCast(SourceRange R, QualType DestTy, QualType SrcTy,
                            CastKind &Kind) {
   if (SrcTy->isMatrixType() && DestTy->isMatrixType()) {
     if (!areMatrixTypesOfTheSameDimension(SrcTy, DestTy)) {
       return Diag(R.getBegin(), diag::err_invalid_conversion_between_matrixes)
              << DestTy << SrcTy << R;
     }
   } else if (SrcTy->isMatrixType()) {
     return Diag(R.getBegin(),
                 diag::err_invalid_conversion_between_matrix_and_type)
            << SrcTy << DestTy << R;
   } else if (DestTy->isMatrixType()) {
     return Diag(R.getBegin(),
                 diag::err_invalid_conversion_between_matrix_and_type)
            << DestTy << SrcTy << R;
   }
 
   Kind = CK_MatrixCast;
   return false;
 }
 
 bool Sema::CheckVectorCast(SourceRange R, QualType VectorTy, QualType Ty,
                            CastKind &Kind) {
   assert(VectorTy->isVectorType() && "Not a vector type!");
 
   if (Ty->isVectorType() || Ty->isIntegralType(Context)) {
     if (!areLaxCompatibleVectorTypes(Ty, VectorTy))
       return Diag(R.getBegin(),
                   Ty->isVectorType() ?
                   diag::err_invalid_conversion_between_vectors :
                   diag::err_invalid_conversion_between_vector_and_integer)
         << VectorTy << Ty << R;
   } else
     return Diag(R.getBegin(),
                 diag::err_invalid_conversion_between_vector_and_scalar)
       << VectorTy << Ty << R;
 
   Kind = CK_BitCast;
   return false;
 }
 
 ExprResult Sema::prepareVectorSplat(QualType VectorTy, Expr *SplattedExpr) {
   QualType DestElemTy = VectorTy->castAs<VectorType>()->getElementType();
 
   if (DestElemTy == SplattedExpr->getType())
     return SplattedExpr;
 
   assert(DestElemTy->isFloatingType() ||
          DestElemTy->isIntegralOrEnumerationType());
 
   CastKind CK;
   if (VectorTy->isExtVectorType() && SplattedExpr->getType()->isBooleanType()) {
     // OpenCL requires that we convert `true` boolean expressions to -1, but
     // only when splatting vectors.
     if (DestElemTy->isFloatingType()) {
       // To avoid having to have a CK_BooleanToSignedFloating cast kind, we cast
       // in two steps: boolean to signed integral, then to floating.
       ExprResult CastExprRes = ImpCastExprToType(SplattedExpr, Context.IntTy,
                                                  CK_BooleanToSignedIntegral);
       SplattedExpr = CastExprRes.get();
       CK = CK_IntegralToFloating;
     } else {
       CK = CK_BooleanToSignedIntegral;
     }
   } else {
     ExprResult CastExprRes = SplattedExpr;
     CK = PrepareScalarCast(CastExprRes, DestElemTy);
     if (CastExprRes.isInvalid())
       return ExprError();
     SplattedExpr = CastExprRes.get();
   }
   return ImpCastExprToType(SplattedExpr, DestElemTy, CK);
 }
 
 ExprResult Sema::CheckExtVectorCast(SourceRange R, QualType DestTy,
                                     Expr *CastExpr, CastKind &Kind) {
   assert(DestTy->isExtVectorType() && "Not an extended vector type!");
 
   QualType SrcTy = CastExpr->getType();
 
   // If SrcTy is a VectorType, the total size must match to explicitly cast to
   // an ExtVectorType.
   // In OpenCL, casts between vectors of different types are not allowed.
   // (See OpenCL 6.2).
   if (SrcTy->isVectorType()) {
     if (!areLaxCompatibleVectorTypes(SrcTy, DestTy) ||
         (getLangOpts().OpenCL &&
          !Context.hasSameUnqualifiedType(DestTy, SrcTy))) {
       Diag(R.getBegin(),diag::err_invalid_conversion_between_ext_vectors)
         << DestTy << SrcTy << R;
       return ExprError();
     }
     Kind = CK_BitCast;
     return CastExpr;
   }
 
   // All non-pointer scalars can be cast to ExtVector type.  The appropriate
   // conversion will take place first from scalar to elt type, and then
   // splat from elt type to vector.
   if (SrcTy->isPointerType())
     return Diag(R.getBegin(),
                 diag::err_invalid_conversion_between_vector_and_scalar)
       << DestTy << SrcTy << R;
 
   Kind = CK_VectorSplat;
   return prepareVectorSplat(DestTy, CastExpr);
 }
 
 ExprResult
 Sema::ActOnCastExpr(Scope *S, SourceLocation LParenLoc,
                     Declarator &D, ParsedType &Ty,
                     SourceLocation RParenLoc, Expr *CastExpr) {
   assert(!D.isInvalidType() && (CastExpr != nullptr) &&
          "ActOnCastExpr(): missing type or expr");
 
   TypeSourceInfo *castTInfo = GetTypeForDeclaratorCast(D, CastExpr->getType());
   if (D.isInvalidType())
     return ExprError();
 
   if (getLangOpts().CPlusPlus) {
     // Check that there are no default arguments (C++ only).
     CheckExtraCXXDefaultArguments(D);
   } else {
     // Make sure any TypoExprs have been dealt with.
     ExprResult Res = CorrectDelayedTyposInExpr(CastExpr);
     if (!Res.isUsable())
       return ExprError();
     CastExpr = Res.get();
   }
 
   checkUnusedDeclAttributes(D);
 
   QualType castType = castTInfo->getType();
   Ty = CreateParsedType(castType, castTInfo);
 
   bool isVectorLiteral = false;
 
   // Check for an altivec or OpenCL literal,
   // i.e. all the elements are integer constants.
   ParenExpr *PE = dyn_cast<ParenExpr>(CastExpr);
   ParenListExpr *PLE = dyn_cast<ParenListExpr>(CastExpr);
   if ((getLangOpts().AltiVec || getLangOpts().ZVector || getLangOpts().OpenCL)
        && castType->isVectorType() && (PE || PLE)) {
     if (PLE && PLE->getNumExprs() == 0) {
       Diag(PLE->getExprLoc(), diag::err_altivec_empty_initializer);
       return ExprError();
     }
     if (PE || PLE->getNumExprs() == 1) {
       Expr *E = (PE ? PE->getSubExpr() : PLE->getExpr(0));
       if (!E->isTypeDependent() && !E->getType()->isVectorType())
         isVectorLiteral = true;
     }
     else
       isVectorLiteral = true;
   }
 
   // If this is a vector initializer, '(' type ')' '(' init, ..., init ')'
   // then handle it as such.
   if (isVectorLiteral)
     return BuildVectorLiteral(LParenLoc, RParenLoc, CastExpr, castTInfo);
 
   // If the Expr being casted is a ParenListExpr, handle it specially.
   // This is not an AltiVec-style cast, so turn the ParenListExpr into a
   // sequence of BinOp comma operators.
   if (isa<ParenListExpr>(CastExpr)) {
     ExprResult Result = MaybeConvertParenListExprToParenExpr(S, CastExpr);
     if (Result.isInvalid()) return ExprError();
     CastExpr = Result.get();
   }
 
   if (getLangOpts().CPlusPlus && !castType->isVoidType())
     Diag(LParenLoc, diag::warn_old_style_cast) << CastExpr->getSourceRange();
 
   CheckTollFreeBridgeCast(castType, CastExpr);
 
   CheckObjCBridgeRelatedCast(castType, CastExpr);
 
   DiscardMisalignedMemberAddress(castType.getTypePtr(), CastExpr);
 
   return BuildCStyleCastExpr(LParenLoc, castTInfo, RParenLoc, CastExpr);
 }
 
 ExprResult Sema::BuildVectorLiteral(SourceLocation LParenLoc,
                                     SourceLocation RParenLoc, Expr *E,
                                     TypeSourceInfo *TInfo) {
   assert((isa<ParenListExpr>(E) || isa<ParenExpr>(E)) &&
          "Expected paren or paren list expression");
 
   Expr **exprs;
   unsigned numExprs;
   Expr *subExpr;
   SourceLocation LiteralLParenLoc, LiteralRParenLoc;
   if (ParenListExpr *PE = dyn_cast<ParenListExpr>(E)) {
     LiteralLParenLoc = PE->getLParenLoc();
     LiteralRParenLoc = PE->getRParenLoc();
     exprs = PE->getExprs();
     numExprs = PE->getNumExprs();
   } else { // isa<ParenExpr> by assertion at function entrance
     LiteralLParenLoc = cast<ParenExpr>(E)->getLParen();
     LiteralRParenLoc = cast<ParenExpr>(E)->getRParen();
     subExpr = cast<ParenExpr>(E)->getSubExpr();
     exprs = &subExpr;
     numExprs = 1;
   }
 
   QualType Ty = TInfo->getType();
   assert(Ty->isVectorType() && "Expected vector type");
 
   SmallVector<Expr *, 8> initExprs;
   const VectorType *VTy = Ty->castAs<VectorType>();
   unsigned numElems = VTy->getNumElements();
 
   // '(...)' form of vector initialization in AltiVec: the number of
   // initializers must be one or must match the size of the vector.
   // If a single value is specified in the initializer then it will be
   // replicated to all the components of the vector
   if (CheckAltivecInitFromScalar(E->getSourceRange(), Ty,
                                  VTy->getElementType()))
     return ExprError();
   if (ShouldSplatAltivecScalarInCast(VTy)) {
     // The number of initializers must be one or must match the size of the
     // vector. If a single value is specified in the initializer then it will
     // be replicated to all the components of the vector
     if (numExprs == 1) {
       QualType ElemTy = VTy->getElementType();
       ExprResult Literal = DefaultLvalueConversion(exprs[0]);
       if (Literal.isInvalid())
         return ExprError();
       Literal = ImpCastExprToType(Literal.get(), ElemTy,
                                   PrepareScalarCast(Literal, ElemTy));
       return BuildCStyleCastExpr(LParenLoc, TInfo, RParenLoc, Literal.get());
     }
     else if (numExprs < numElems) {
       Diag(E->getExprLoc(),
            diag::err_incorrect_number_of_vector_initializers);
       return ExprError();
     }
     else
       initExprs.append(exprs, exprs + numExprs);
   }
   else {
     // For OpenCL, when the number of initializers is a single value,
     // it will be replicated to all components of the vector.
     if (getLangOpts().OpenCL &&
         VTy->getVectorKind() == VectorType::GenericVector &&
         numExprs == 1) {
         QualType ElemTy = VTy->getElementType();
         ExprResult Literal = DefaultLvalueConversion(exprs[0]);
         if (Literal.isInvalid())
           return ExprError();
         Literal = ImpCastExprToType(Literal.get(), ElemTy,
                                     PrepareScalarCast(Literal, ElemTy));
         return BuildCStyleCastExpr(LParenLoc, TInfo, RParenLoc, Literal.get());
     }
 
     initExprs.append(exprs, exprs + numExprs);
   }
   // FIXME: This means that pretty-printing the final AST will produce curly
   // braces instead of the original commas.
   InitListExpr *initE = new (Context) InitListExpr(Context, LiteralLParenLoc,
                                                    initExprs, LiteralRParenLoc);
   initE->setType(Ty);
   return BuildCompoundLiteralExpr(LParenLoc, TInfo, RParenLoc, initE);
 }
 
 /// This is not an AltiVec-style cast or or C++ direct-initialization, so turn
 /// the ParenListExpr into a sequence of comma binary operators.
 ExprResult
 Sema::MaybeConvertParenListExprToParenExpr(Scope *S, Expr *OrigExpr) {
   ParenListExpr *E = dyn_cast<ParenListExpr>(OrigExpr);
   if (!E)
     return OrigExpr;
 
   ExprResult Result(E->getExpr(0));
 
   for (unsigned i = 1, e = E->getNumExprs(); i != e && !Result.isInvalid(); ++i)
     Result = ActOnBinOp(S, E->getExprLoc(), tok::comma, Result.get(),
                         E->getExpr(i));
 
   if (Result.isInvalid()) return ExprError();
 
   return ActOnParenExpr(E->getLParenLoc(), E->getRParenLoc(), Result.get());
 }
 
 ExprResult Sema::ActOnParenListExpr(SourceLocation L,
                                     SourceLocation R,
                                     MultiExprArg Val) {
   return ParenListExpr::Create(Context, L, Val, R);
 }
 
 /// Emit a specialized diagnostic when one expression is a null pointer
 /// constant and the other is not a pointer.  Returns true if a diagnostic is
 /// emitted.
 bool Sema::DiagnoseConditionalForNull(Expr *LHSExpr, Expr *RHSExpr,
                                       SourceLocation QuestionLoc) {
   Expr *NullExpr = LHSExpr;
   Expr *NonPointerExpr = RHSExpr;
   Expr::NullPointerConstantKind NullKind =
       NullExpr->isNullPointerConstant(Context,
                                       Expr::NPC_ValueDependentIsNotNull);
 
   if (NullKind == Expr::NPCK_NotNull) {
     NullExpr = RHSExpr;
     NonPointerExpr = LHSExpr;
     NullKind =
         NullExpr->isNullPointerConstant(Context,
                                         Expr::NPC_ValueDependentIsNotNull);
   }
 
   if (NullKind == Expr::NPCK_NotNull)
     return false;
 
   if (NullKind == Expr::NPCK_ZeroExpression)
     return false;
 
   if (NullKind == Expr::NPCK_ZeroLiteral) {
     // In this case, check to make sure that we got here from a "NULL"
     // string in the source code.
     NullExpr = NullExpr->IgnoreParenImpCasts();
     SourceLocation loc = NullExpr->getExprLoc();
     if (!findMacroSpelling(loc, "NULL"))
       return false;
   }
 
   int DiagType = (NullKind == Expr::NPCK_CXX11_nullptr);
   Diag(QuestionLoc, diag::err_typecheck_cond_incompatible_operands_null)
       << NonPointerExpr->getType() << DiagType
       << NonPointerExpr->getSourceRange();
   return true;
 }
 
 /// Return false if the condition expression is valid, true otherwise.
 static bool checkCondition(Sema &S, Expr *Cond, SourceLocation QuestionLoc) {
   QualType CondTy = Cond->getType();
 
   // OpenCL v1.1 s6.3.i says the condition cannot be a floating point type.
   if (S.getLangOpts().OpenCL && CondTy->isFloatingType()) {
     S.Diag(QuestionLoc, diag::err_typecheck_cond_expect_nonfloat)
       << CondTy << Cond->getSourceRange();
     return true;
   }
 
   // C99 6.5.15p2
   if (CondTy->isScalarType()) return false;
 
   S.Diag(QuestionLoc, diag::err_typecheck_cond_expect_scalar)
     << CondTy << Cond->getSourceRange();
   return true;
 }
 
 /// Return false if the NullExpr can be promoted to PointerTy,
 /// true otherwise.
 static bool checkConditionalNullPointer(Sema &S, ExprResult &NullExpr,
                                         QualType PointerTy) {
   if ((!PointerTy->isAnyPointerType() && !PointerTy->isBlockPointerType()) ||
       !NullExpr.get()->isNullPointerConstant(S.Context,
                                             Expr::NPC_ValueDependentIsNull))
     return true;
 
   NullExpr = S.ImpCastExprToType(NullExpr.get(), PointerTy, CK_NullToPointer);
   return false;
 }
 
 /// Checks compatibility between two pointers and return the resulting
 /// type.
 static QualType checkConditionalPointerCompatibility(Sema &S, ExprResult &LHS,
                                                      ExprResult &RHS,
                                                      SourceLocation Loc) {
   QualType LHSTy = LHS.get()->getType();
   QualType RHSTy = RHS.get()->getType();
 
   if (S.Context.hasSameType(LHSTy, RHSTy)) {
     // Two identical pointers types are always compatible.
     return S.Context.getCommonSugaredType(LHSTy, RHSTy);
   }
 
   QualType lhptee, rhptee;
 
   // Get the pointee types.
   bool IsBlockPointer = false;
   if (const BlockPointerType *LHSBTy = LHSTy->getAs<BlockPointerType>()) {
     lhptee = LHSBTy->getPointeeType();
     rhptee = RHSTy->castAs<BlockPointerType>()->getPointeeType();
     IsBlockPointer = true;
   } else {
     lhptee = LHSTy->castAs<PointerType>()->getPointeeType();
     rhptee = RHSTy->castAs<PointerType>()->getPointeeType();
   }
 
   // C99 6.5.15p6: If both operands are pointers to compatible types or to
   // differently qualified versions of compatible types, the result type is
   // a pointer to an appropriately qualified version of the composite
   // type.
 
   // Only CVR-qualifiers exist in the standard, and the differently-qualified
   // clause doesn't make sense for our extensions. E.g. address space 2 should
   // be incompatible with address space 3: they may live on different devices or
   // anything.
   Qualifiers lhQual = lhptee.getQualifiers();
   Qualifiers rhQual = rhptee.getQualifiers();
 
   LangAS ResultAddrSpace = LangAS::Default;
   LangAS LAddrSpace = lhQual.getAddressSpace();
   LangAS RAddrSpace = rhQual.getAddressSpace();
 
   // OpenCL v1.1 s6.5 - Conversion between pointers to distinct address
   // spaces is disallowed.
   if (lhQual.isAddressSpaceSupersetOf(rhQual))
     ResultAddrSpace = LAddrSpace;
   else if (rhQual.isAddressSpaceSupersetOf(lhQual))
     ResultAddrSpace = RAddrSpace;
   else {
     S.Diag(Loc, diag::err_typecheck_op_on_nonoverlapping_address_space_pointers)
         << LHSTy << RHSTy << 2 << LHS.get()->getSourceRange()
         << RHS.get()->getSourceRange();
     return QualType();
   }
 
   unsigned MergedCVRQual = lhQual.getCVRQualifiers() | rhQual.getCVRQualifiers();
   auto LHSCastKind = CK_BitCast, RHSCastKind = CK_BitCast;
   lhQual.removeCVRQualifiers();
   rhQual.removeCVRQualifiers();
 
   // OpenCL v2.0 specification doesn't extend compatibility of type qualifiers
   // (C99 6.7.3) for address spaces. We assume that the check should behave in
   // the same manner as it's defined for CVR qualifiers, so for OpenCL two
   // qual types are compatible iff
   //  * corresponded types are compatible
   //  * CVR qualifiers are equal
   //  * address spaces are equal
   // Thus for conditional operator we merge CVR and address space unqualified
   // pointees and if there is a composite type we return a pointer to it with
   // merged qualifiers.
   LHSCastKind =
       LAddrSpace == ResultAddrSpace ? CK_BitCast : CK_AddressSpaceConversion;
   RHSCastKind =
       RAddrSpace == ResultAddrSpace ? CK_BitCast : CK_AddressSpaceConversion;
   lhQual.removeAddressSpace();
   rhQual.removeAddressSpace();
 
   lhptee = S.Context.getQualifiedType(lhptee.getUnqualifiedType(), lhQual);
   rhptee = S.Context.getQualifiedType(rhptee.getUnqualifiedType(), rhQual);
 
   QualType CompositeTy = S.Context.mergeTypes(
       lhptee, rhptee, /*OfBlockPointer=*/false, /*Unqualified=*/false,
       /*BlockReturnType=*/false, /*IsConditionalOperator=*/true);
 
   if (CompositeTy.isNull()) {
     // In this situation, we assume void* type. No especially good
     // reason, but this is what gcc does, and we do have to pick
     // to get a consistent AST.
     QualType incompatTy;
     incompatTy = S.Context.getPointerType(
         S.Context.getAddrSpaceQualType(S.Context.VoidTy, ResultAddrSpace));
     LHS = S.ImpCastExprToType(LHS.get(), incompatTy, LHSCastKind);
     RHS = S.ImpCastExprToType(RHS.get(), incompatTy, RHSCastKind);
 
     // FIXME: For OpenCL the warning emission and cast to void* leaves a room
     // for casts between types with incompatible address space qualifiers.
     // For the following code the compiler produces casts between global and
     // local address spaces of the corresponded innermost pointees:
     // local int *global *a;
     // global int *global *b;
     // a = (0 ? a : b); // see C99 6.5.16.1.p1.
     S.Diag(Loc, diag::ext_typecheck_cond_incompatible_pointers)
         << LHSTy << RHSTy << LHS.get()->getSourceRange()
         << RHS.get()->getSourceRange();
 
     return incompatTy;
   }
 
   // The pointer types are compatible.
   // In case of OpenCL ResultTy should have the address space qualifier
   // which is a superset of address spaces of both the 2nd and the 3rd
   // operands of the conditional operator.
   QualType ResultTy = [&, ResultAddrSpace]() {
     if (S.getLangOpts().OpenCL) {
       Qualifiers CompositeQuals = CompositeTy.getQualifiers();
       CompositeQuals.setAddressSpace(ResultAddrSpace);
       return S.Context
           .getQualifiedType(CompositeTy.getUnqualifiedType(), CompositeQuals)
           .withCVRQualifiers(MergedCVRQual);
     }
     return CompositeTy.withCVRQualifiers(MergedCVRQual);
   }();
   if (IsBlockPointer)
     ResultTy = S.Context.getBlockPointerType(ResultTy);
   else
     ResultTy = S.Context.getPointerType(ResultTy);
 
   LHS = S.ImpCastExprToType(LHS.get(), ResultTy, LHSCastKind);
   RHS = S.ImpCastExprToType(RHS.get(), ResultTy, RHSCastKind);
   return ResultTy;
 }
 
 /// Return the resulting type when the operands are both block pointers.
 static QualType checkConditionalBlockPointerCompatibility(Sema &S,
                                                           ExprResult &LHS,
                                                           ExprResult &RHS,
                                                           SourceLocation Loc) {
   QualType LHSTy = LHS.get()->getType();
   QualType RHSTy = RHS.get()->getType();
 
   if (!LHSTy->isBlockPointerType() || !RHSTy->isBlockPointerType()) {
     if (LHSTy->isVoidPointerType() || RHSTy->isVoidPointerType()) {
       QualType destType = S.Context.getPointerType(S.Context.VoidTy);
       LHS = S.ImpCastExprToType(LHS.get(), destType, CK_BitCast);
       RHS = S.ImpCastExprToType(RHS.get(), destType, CK_BitCast);
       return destType;
     }
     S.Diag(Loc, diag::err_typecheck_cond_incompatible_operands)
       << LHSTy << RHSTy << LHS.get()->getSourceRange()
       << RHS.get()->getSourceRange();
     return QualType();
   }
 
   // We have 2 block pointer types.
   return checkConditionalPointerCompatibility(S, LHS, RHS, Loc);
 }
 
 /// Return the resulting type when the operands are both pointers.
 static QualType
 checkConditionalObjectPointersCompatibility(Sema &S, ExprResult &LHS,
                                             ExprResult &RHS,
                                             SourceLocation Loc) {
   // get the pointer types
   QualType LHSTy = LHS.get()->getType();
   QualType RHSTy = RHS.get()->getType();
 
   // get the "pointed to" types
   QualType lhptee = LHSTy->castAs<PointerType>()->getPointeeType();
   QualType rhptee = RHSTy->castAs<PointerType>()->getPointeeType();
 
   // ignore qualifiers on void (C99 6.5.15p3, clause 6)
   if (lhptee->isVoidType() && rhptee->isIncompleteOrObjectType()) {
     // Figure out necessary qualifiers (C99 6.5.15p6)
     QualType destPointee
       = S.Context.getQualifiedType(lhptee, rhptee.getQualifiers());
     QualType destType = S.Context.getPointerType(destPointee);
     // Add qualifiers if necessary.
     LHS = S.ImpCastExprToType(LHS.get(), destType, CK_NoOp);
     // Promote to void*.
     RHS = S.ImpCastExprToType(RHS.get(), destType, CK_BitCast);
     return destType;
   }
   if (rhptee->isVoidType() && lhptee->isIncompleteOrObjectType()) {
     QualType destPointee
       = S.Context.getQualifiedType(rhptee, lhptee.getQualifiers());
     QualType destType = S.Context.getPointerType(destPointee);
     // Add qualifiers if necessary.
     RHS = S.ImpCastExprToType(RHS.get(), destType, CK_NoOp);
     // Promote to void*.
     LHS = S.ImpCastExprToType(LHS.get(), destType, CK_BitCast);
     return destType;
   }
 
   return checkConditionalPointerCompatibility(S, LHS, RHS, Loc);
 }
 
 /// Return false if the first expression is not an integer and the second
 /// expression is not a pointer, true otherwise.
 static bool checkPointerIntegerMismatch(Sema &S, ExprResult &Int,
                                         Expr* PointerExpr, SourceLocation Loc,
                                         bool IsIntFirstExpr) {
   if (!PointerExpr->getType()->isPointerType() ||
       !Int.get()->getType()->isIntegerType())
     return false;
 
   Expr *Expr1 = IsIntFirstExpr ? Int.get() : PointerExpr;
   Expr *Expr2 = IsIntFirstExpr ? PointerExpr : Int.get();
 
   S.Diag(Loc, diag::ext_typecheck_cond_pointer_integer_mismatch)
     << Expr1->getType() << Expr2->getType()
     << Expr1->getSourceRange() << Expr2->getSourceRange();
   Int = S.ImpCastExprToType(Int.get(), PointerExpr->getType(),
                             CK_IntegralToPointer);
   return true;
 }
 
 /// Simple conversion between integer and floating point types.
 ///
 /// Used when handling the OpenCL conditional operator where the
 /// condition is a vector while the other operands are scalar.
 ///
 /// OpenCL v1.1 s6.3.i and s6.11.6 together require that the scalar
 /// types are either integer or floating type. Between the two
 /// operands, the type with the higher rank is defined as the "result
 /// type". The other operand needs to be promoted to the same type. No
 /// other type promotion is allowed. We cannot use
 /// UsualArithmeticConversions() for this purpose, since it always
 /// promotes promotable types.
 static QualType OpenCLArithmeticConversions(Sema &S, ExprResult &LHS,
                                             ExprResult &RHS,
                                             SourceLocation QuestionLoc) {
   LHS = S.DefaultFunctionArrayLvalueConversion(LHS.get());
   if (LHS.isInvalid())
     return QualType();
   RHS = S.DefaultFunctionArrayLvalueConversion(RHS.get());
   if (RHS.isInvalid())
     return QualType();
 
   // For conversion purposes, we ignore any qualifiers.
   // For example, "const float" and "float" are equivalent.
   QualType LHSType =
     S.Context.getCanonicalType(LHS.get()->getType()).getUnqualifiedType();
   QualType RHSType =
     S.Context.getCanonicalType(RHS.get()->getType()).getUnqualifiedType();
 
   if (!LHSType->isIntegerType() && !LHSType->isRealFloatingType()) {
     S.Diag(QuestionLoc, diag::err_typecheck_cond_expect_int_float)
       << LHSType << LHS.get()->getSourceRange();
     return QualType();
   }
 
   if (!RHSType->isIntegerType() && !RHSType->isRealFloatingType()) {
     S.Diag(QuestionLoc, diag::err_typecheck_cond_expect_int_float)
       << RHSType << RHS.get()->getSourceRange();
     return QualType();
   }
 
   // If both types are identical, no conversion is needed.
   if (LHSType == RHSType)
     return LHSType;
 
   // Now handle "real" floating types (i.e. float, double, long double).
   if (LHSType->isRealFloatingType() || RHSType->isRealFloatingType())
     return handleFloatConversion(S, LHS, RHS, LHSType, RHSType,
                                  /*IsCompAssign = */ false);
 
   // Finally, we have two differing integer types.
   return handleIntegerConversion<doIntegralCast, doIntegralCast>
   (S, LHS, RHS, LHSType, RHSType, /*IsCompAssign = */ false);
 }
 
 /// Convert scalar operands to a vector that matches the
 ///        condition in length.
 ///
 /// Used when handling the OpenCL conditional operator where the
 /// condition is a vector while the other operands are scalar.
 ///
 /// We first compute the "result type" for the scalar operands
 /// according to OpenCL v1.1 s6.3.i. Both operands are then converted
 /// into a vector of that type where the length matches the condition
 /// vector type. s6.11.6 requires that the element types of the result
 /// and the condition must have the same number of bits.
 static QualType
 OpenCLConvertScalarsToVectors(Sema &S, ExprResult &LHS, ExprResult &RHS,
                               QualType CondTy, SourceLocation QuestionLoc) {
   QualType ResTy = OpenCLArithmeticConversions(S, LHS, RHS, QuestionLoc);
   if (ResTy.isNull()) return QualType();
 
   const VectorType *CV = CondTy->getAs<VectorType>();
   assert(CV);
 
   // Determine the vector result type
   unsigned NumElements = CV->getNumElements();
   QualType VectorTy = S.Context.getExtVectorType(ResTy, NumElements);
 
   // Ensure that all types have the same number of bits
   if (S.Context.getTypeSize(CV->getElementType())
       != S.Context.getTypeSize(ResTy)) {
     // Since VectorTy is created internally, it does not pretty print
     // with an OpenCL name. Instead, we just print a description.
     std::string EleTyName = ResTy.getUnqualifiedType().getAsString();
     SmallString<64> Str;
     llvm::raw_svector_ostream OS(Str);
     OS << "(vector of " << NumElements << " '" << EleTyName << "' values)";
     S.Diag(QuestionLoc, diag::err_conditional_vector_element_size)
       << CondTy << OS.str();
     return QualType();
   }
 
   // Convert operands to the vector result type
   LHS = S.ImpCastExprToType(LHS.get(), VectorTy, CK_VectorSplat);
   RHS = S.ImpCastExprToType(RHS.get(), VectorTy, CK_VectorSplat);
 
   return VectorTy;
 }
 
 /// Return false if this is a valid OpenCL condition vector
 static bool checkOpenCLConditionVector(Sema &S, Expr *Cond,
                                        SourceLocation QuestionLoc) {
   // OpenCL v1.1 s6.11.6 says the elements of the vector must be of
   // integral type.
   const VectorType *CondTy = Cond->getType()->getAs<VectorType>();
   assert(CondTy);
   QualType EleTy = CondTy->getElementType();
   if (EleTy->isIntegerType()) return false;
 
   S.Diag(QuestionLoc, diag::err_typecheck_cond_expect_nonfloat)
     << Cond->getType() << Cond->getSourceRange();
   return true;
 }
 
 /// Return false if the vector condition type and the vector
 ///        result type are compatible.
 ///
 /// OpenCL v1.1 s6.11.6 requires that both vector types have the same
 /// number of elements, and their element types have the same number
 /// of bits.
 static bool checkVectorResult(Sema &S, QualType CondTy, QualType VecResTy,
                               SourceLocation QuestionLoc) {
   const VectorType *CV = CondTy->getAs<VectorType>();
   const VectorType *RV = VecResTy->getAs<VectorType>();
   assert(CV && RV);
 
   if (CV->getNumElements() != RV->getNumElements()) {
     S.Diag(QuestionLoc, diag::err_conditional_vector_size)
       << CondTy << VecResTy;
     return true;
   }
 
   QualType CVE = CV->getElementType();
   QualType RVE = RV->getElementType();
 
   if (S.Context.getTypeSize(CVE) != S.Context.getTypeSize(RVE)) {
     S.Diag(QuestionLoc, diag::err_conditional_vector_element_size)
       << CondTy << VecResTy;
     return true;
   }
 
   return false;
 }
 
 /// Return the resulting type for the conditional operator in
 ///        OpenCL (aka "ternary selection operator", OpenCL v1.1
 ///        s6.3.i) when the condition is a vector type.
 static QualType
 OpenCLCheckVectorConditional(Sema &S, ExprResult &Cond,
                              ExprResult &LHS, ExprResult &RHS,
                              SourceLocation QuestionLoc) {
   Cond = S.DefaultFunctionArrayLvalueConversion(Cond.get());
   if (Cond.isInvalid())
     return QualType();
   QualType CondTy = Cond.get()->getType();
 
   if (checkOpenCLConditionVector(S, Cond.get(), QuestionLoc))
     return QualType();
 
   // If either operand is a vector then find the vector type of the
   // result as specified in OpenCL v1.1 s6.3.i.
   if (LHS.get()->getType()->isVectorType() ||
       RHS.get()->getType()->isVectorType()) {
     bool IsBoolVecLang =
         !S.getLangOpts().OpenCL && !S.getLangOpts().OpenCLCPlusPlus;
     QualType VecResTy =
         S.CheckVectorOperands(LHS, RHS, QuestionLoc,
                               /*isCompAssign*/ false,
                               /*AllowBothBool*/ true,
                               /*AllowBoolConversions*/ false,
                               /*AllowBooleanOperation*/ IsBoolVecLang,
                               /*ReportInvalid*/ true);
     if (VecResTy.isNull())
       return QualType();
     // The result type must match the condition type as specified in
     // OpenCL v1.1 s6.11.6.
     if (checkVectorResult(S, CondTy, VecResTy, QuestionLoc))
       return QualType();
     return VecResTy;
   }
 
   // Both operands are scalar.
   return OpenCLConvertScalarsToVectors(S, LHS, RHS, CondTy, QuestionLoc);
 }
 
 /// Return true if the Expr is block type
 static bool checkBlockType(Sema &S, const Expr *E) {
   if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
     QualType Ty = CE->getCallee()->getType();
     if (Ty->isBlockPointerType()) {
       S.Diag(E->getExprLoc(), diag::err_opencl_ternary_with_block);
       return true;
     }
   }
   return false;
 }
 
 /// Note that LHS is not null here, even if this is the gnu "x ?: y" extension.
 /// In that case, LHS = cond.
 /// C99 6.5.15
 QualType Sema::CheckConditionalOperands(ExprResult &Cond, ExprResult &LHS,
                                         ExprResult &RHS, ExprValueKind &VK,
                                         ExprObjectKind &OK,
                                         SourceLocation QuestionLoc) {
 
   ExprResult LHSResult = CheckPlaceholderExpr(LHS.get());
   if (!LHSResult.isUsable()) return QualType();
   LHS = LHSResult;
 
   ExprResult RHSResult = CheckPlaceholderExpr(RHS.get());
   if (!RHSResult.isUsable()) return QualType();
   RHS = RHSResult;
 
   // C++ is sufficiently different to merit its own checker.
   if (getLangOpts().CPlusPlus)
     return CXXCheckConditionalOperands(Cond, LHS, RHS, VK, OK, QuestionLoc);
 
   VK = VK_PRValue;
   OK = OK_Ordinary;
 
   if (Context.isDependenceAllowed() &&
       (Cond.get()->isTypeDependent() || LHS.get()->isTypeDependent() ||
        RHS.get()->isTypeDependent())) {
     assert(!getLangOpts().CPlusPlus);
     assert((Cond.get()->containsErrors() || LHS.get()->containsErrors() ||
             RHS.get()->containsErrors()) &&
            "should only occur in error-recovery path.");
     return Context.DependentTy;
   }
 
   // The OpenCL operator with a vector condition is sufficiently
   // different to merit its own checker.
   if ((getLangOpts().OpenCL && Cond.get()->getType()->isVectorType()) ||
       Cond.get()->getType()->isExtVectorType())
     return OpenCLCheckVectorConditional(*this, Cond, LHS, RHS, QuestionLoc);
 
   // First, check the condition.
   Cond = UsualUnaryConversions(Cond.get());
   if (Cond.isInvalid())
     return QualType();
   if (checkCondition(*this, Cond.get(), QuestionLoc))
     return QualType();
 
   // Now check the two expressions.
   if (LHS.get()->getType()->isVectorType() ||
       RHS.get()->getType()->isVectorType())
     return CheckVectorOperands(LHS, RHS, QuestionLoc, /*isCompAssign*/ false,
                                /*AllowBothBool*/ true,
                                /*AllowBoolConversions*/ false,
                                /*AllowBooleanOperation*/ false,
                                /*ReportInvalid*/ true);
 
   QualType ResTy =
       UsualArithmeticConversions(LHS, RHS, QuestionLoc, ACK_Conditional);
   if (LHS.isInvalid() || RHS.isInvalid())
     return QualType();
 
   // WebAssembly tables are not allowed as conditional LHS or RHS.
   QualType LHSTy = LHS.get()->getType();
   QualType RHSTy = RHS.get()->getType();
   if (LHSTy->isWebAssemblyTableType() || RHSTy->isWebAssemblyTableType()) {
     Diag(QuestionLoc, diag::err_wasm_table_conditional_expression)
         << LHS.get()->getSourceRange() << RHS.get()->getSourceRange();
     return QualType();
   }
 
   // Diagnose attempts to convert between __ibm128, __float128 and long double
   // where such conversions currently can't be handled.
   if (unsupportedTypeConversion(*this, LHSTy, RHSTy)) {
     Diag(QuestionLoc,
          diag::err_typecheck_cond_incompatible_operands) << LHSTy << RHSTy
       << LHS.get()->getSourceRange() << RHS.get()->getSourceRange();
     return QualType();
   }
 
   // OpenCL v2.0 s6.12.5 - Blocks cannot be used as expressions of the ternary
   // selection operator (?:).
   if (getLangOpts().OpenCL &&
       ((int)checkBlockType(*this, LHS.get()) | (int)checkBlockType(*this, RHS.get()))) {
     return QualType();
   }
 
   // If both operands have arithmetic type, do the usual arithmetic conversions
   // to find a common type: C99 6.5.15p3,5.
   if (LHSTy->isArithmeticType() && RHSTy->isArithmeticType()) {
     // Disallow invalid arithmetic conversions, such as those between bit-
     // precise integers types of different sizes, or between a bit-precise
     // integer and another type.
     if (ResTy.isNull() && (LHSTy->isBitIntType() || RHSTy->isBitIntType())) {
       Diag(QuestionLoc, diag::err_typecheck_cond_incompatible_operands)
           << LHSTy << RHSTy << LHS.get()->getSourceRange()
           << RHS.get()->getSourceRange();
       return QualType();
     }
 
     LHS = ImpCastExprToType(LHS.get(), ResTy, PrepareScalarCast(LHS, ResTy));
     RHS = ImpCastExprToType(RHS.get(), ResTy, PrepareScalarCast(RHS, ResTy));
 
     return ResTy;
   }
 
   // And if they're both bfloat (which isn't arithmetic), that's fine too.
   if (LHSTy->isBFloat16Type() && RHSTy->isBFloat16Type()) {
     return Context.getCommonSugaredType(LHSTy, RHSTy);
   }
 
   // If both operands are the same structure or union type, the result is that
   // type.
   if (const RecordType *LHSRT = LHSTy->getAs<RecordType>()) {    // C99 6.5.15p3
     if (const RecordType *RHSRT = RHSTy->getAs<RecordType>())
       if (LHSRT->getDecl() == RHSRT->getDecl())
         // "If both the operands have structure or union type, the result has
         // that type."  This implies that CV qualifiers are dropped.
         return Context.getCommonSugaredType(LHSTy.getUnqualifiedType(),
                                             RHSTy.getUnqualifiedType());
     // FIXME: Type of conditional expression must be complete in C mode.
   }
 
   // C99 6.5.15p5: "If both operands have void type, the result has void type."
   // The following || allows only one side to be void (a GCC-ism).
   if (LHSTy->isVoidType() || RHSTy->isVoidType()) {
     QualType ResTy;
     if (LHSTy->isVoidType() && RHSTy->isVoidType()) {
       ResTy = Context.getCommonSugaredType(LHSTy, RHSTy);
     } else if (RHSTy->isVoidType()) {
       ResTy = RHSTy;
       Diag(RHS.get()->getBeginLoc(), diag::ext_typecheck_cond_one_void)
           << RHS.get()->getSourceRange();
     } else {
       ResTy = LHSTy;
       Diag(LHS.get()->getBeginLoc(), diag::ext_typecheck_cond_one_void)
           << LHS.get()->getSourceRange();
     }
     LHS = ImpCastExprToType(LHS.get(), ResTy, CK_ToVoid);
     RHS = ImpCastExprToType(RHS.get(), ResTy, CK_ToVoid);
     return ResTy;
   }
 
   // C2x 6.5.15p7:
   //   ... if both the second and third operands have nullptr_t type, the
   //   result also has that type.
   if (LHSTy->isNullPtrType() && Context.hasSameType(LHSTy, RHSTy))
     return ResTy;
 
   // C99 6.5.15p6 - "if one operand is a null pointer constant, the result has
   // the type of the other operand."
   if (!checkConditionalNullPointer(*this, RHS, LHSTy)) return LHSTy;
   if (!checkConditionalNullPointer(*this, LHS, RHSTy)) return RHSTy;
 
   // All objective-c pointer type analysis is done here.
   QualType compositeType = FindCompositeObjCPointerType(LHS, RHS,
                                                         QuestionLoc);
   if (LHS.isInvalid() || RHS.isInvalid())
     return QualType();
   if (!compositeType.isNull())
     return compositeType;
 
 
   // Handle block pointer types.
   if (LHSTy->isBlockPointerType() || RHSTy->isBlockPointerType())
     return checkConditionalBlockPointerCompatibility(*this, LHS, RHS,
                                                      QuestionLoc);
 
   // Check constraints for C object pointers types (C99 6.5.15p3,6).
   if (LHSTy->isPointerType() && RHSTy->isPointerType())
     return checkConditionalObjectPointersCompatibility(*this, LHS, RHS,
                                                        QuestionLoc);
 
   // GCC compatibility: soften pointer/integer mismatch.  Note that
   // null pointers have been filtered out by this point.
   if (checkPointerIntegerMismatch(*this, LHS, RHS.get(), QuestionLoc,
       /*IsIntFirstExpr=*/true))
     return RHSTy;
   if (checkPointerIntegerMismatch(*this, RHS, LHS.get(), QuestionLoc,
       /*IsIntFirstExpr=*/false))
     return LHSTy;
 
   // Allow ?: operations in which both operands have the same
   // built-in sizeless type.
   if (LHSTy->isSizelessBuiltinType() && Context.hasSameType(LHSTy, RHSTy))
     return Context.getCommonSugaredType(LHSTy, RHSTy);
 
   // Emit a better diagnostic if one of the expressions is a null pointer
   // constant and the other is not a pointer type. In this case, the user most
   // likely forgot to take the address of the other expression.
   if (DiagnoseConditionalForNull(LHS.get(), RHS.get(), QuestionLoc))
     return QualType();
 
   // Otherwise, the operands are not compatible.
   Diag(QuestionLoc, diag::err_typecheck_cond_incompatible_operands)
     << LHSTy << RHSTy << LHS.get()->getSourceRange()
     << RHS.get()->getSourceRange();
   return QualType();
 }
 
 /// FindCompositeObjCPointerType - Helper method to find composite type of
 /// two objective-c pointer types of the two input expressions.
 QualType Sema::FindCompositeObjCPointerType(ExprResult &LHS, ExprResult &RHS,
                                             SourceLocation QuestionLoc) {
   QualType LHSTy = LHS.get()->getType();
   QualType RHSTy = RHS.get()->getType();
 
   // Handle things like Class and struct objc_class*.  Here we case the result
   // to the pseudo-builtin, because that will be implicitly cast back to the
   // redefinition type if an attempt is made to access its fields.
   if (LHSTy->isObjCClassType() &&
       (Context.hasSameType(RHSTy, Context.getObjCClassRedefinitionType()))) {
     RHS = ImpCastExprToType(RHS.get(), LHSTy, CK_CPointerToObjCPointerCast);
     return LHSTy;
   }
   if (RHSTy->isObjCClassType() &&
       (Context.hasSameType(LHSTy, Context.getObjCClassRedefinitionType()))) {
     LHS = ImpCastExprToType(LHS.get(), RHSTy, CK_CPointerToObjCPointerCast);
     return RHSTy;
   }
   // And the same for struct objc_object* / id
   if (LHSTy->isObjCIdType() &&
       (Context.hasSameType(RHSTy, Context.getObjCIdRedefinitionType()))) {
     RHS = ImpCastExprToType(RHS.get(), LHSTy, CK_CPointerToObjCPointerCast);
     return LHSTy;
   }
   if (RHSTy->isObjCIdType() &&
       (Context.hasSameType(LHSTy, Context.getObjCIdRedefinitionType()))) {
     LHS = ImpCastExprToType(LHS.get(), RHSTy, CK_CPointerToObjCPointerCast);
     return RHSTy;
   }
   // And the same for struct objc_selector* / SEL
   if (Context.isObjCSelType(LHSTy) &&
       (Context.hasSameType(RHSTy, Context.getObjCSelRedefinitionType()))) {
     RHS = ImpCastExprToType(RHS.get(), LHSTy, CK_BitCast);
     return LHSTy;
   }
   if (Context.isObjCSelType(RHSTy) &&
       (Context.hasSameType(LHSTy, Context.getObjCSelRedefinitionType()))) {
     LHS = ImpCastExprToType(LHS.get(), RHSTy, CK_BitCast);
     return RHSTy;
   }
   // Check constraints for Objective-C object pointers types.
   if (LHSTy->isObjCObjectPointerType() && RHSTy->isObjCObjectPointerType()) {
 
     if (Context.getCanonicalType(LHSTy) == Context.getCanonicalType(RHSTy)) {
       // Two identical object pointer types are always compatible.
       return LHSTy;
     }
     const ObjCObjectPointerType *LHSOPT = LHSTy->castAs<ObjCObjectPointerType>();
     const ObjCObjectPointerType *RHSOPT = RHSTy->castAs<ObjCObjectPointerType>();
     QualType compositeType = LHSTy;
 
     // If both operands are interfaces and either operand can be
     // assigned to the other, use that type as the composite
     // type. This allows
     //   xxx ? (A*) a : (B*) b
     // where B is a subclass of A.
     //
     // Additionally, as for assignment, if either type is 'id'
     // allow silent coercion. Finally, if the types are
     // incompatible then make sure to use 'id' as the composite
     // type so the result is acceptable for sending messages to.
 
     // FIXME: Consider unifying with 'areComparableObjCPointerTypes'.
     // It could return the composite type.
     if (!(compositeType =
           Context.areCommonBaseCompatible(LHSOPT, RHSOPT)).isNull()) {
       // Nothing more to do.
     } else if (Context.canAssignObjCInterfaces(LHSOPT, RHSOPT)) {
       compositeType = RHSOPT->isObjCBuiltinType() ? RHSTy : LHSTy;
     } else if (Context.canAssignObjCInterfaces(RHSOPT, LHSOPT)) {
       compositeType = LHSOPT->isObjCBuiltinType() ? LHSTy : RHSTy;
     } else if ((LHSOPT->isObjCQualifiedIdType() ||
                 RHSOPT->isObjCQualifiedIdType()) &&
                Context.ObjCQualifiedIdTypesAreCompatible(LHSOPT, RHSOPT,
                                                          true)) {
       // Need to handle "id<xx>" explicitly.
       // GCC allows qualified id and any Objective-C type to devolve to
       // id. Currently localizing to here until clear this should be
       // part of ObjCQualifiedIdTypesAreCompatible.
       compositeType = Context.getObjCIdType();
     } else if (LHSTy->isObjCIdType() || RHSTy->isObjCIdType()) {
       compositeType = Context.getObjCIdType();
     } else {
       Diag(QuestionLoc, diag::ext_typecheck_cond_incompatible_operands)
       << LHSTy << RHSTy
       << LHS.get()->getSourceRange() << RHS.get()->getSourceRange();
       QualType incompatTy = Context.getObjCIdType();
       LHS = ImpCastExprToType(LHS.get(), incompatTy, CK_BitCast);
       RHS = ImpCastExprToType(RHS.get(), incompatTy, CK_BitCast);
       return incompatTy;
     }
     // The object pointer types are compatible.
     LHS = ImpCastExprToType(LHS.get(), compositeType, CK_BitCast);
     RHS = ImpCastExprToType(RHS.get(), compositeType, CK_BitCast);
     return compositeType;
   }
   // Check Objective-C object pointer types and 'void *'
   if (LHSTy->isVoidPointerType() && RHSTy->isObjCObjectPointerType()) {
     if (getLangOpts().ObjCAutoRefCount) {
       // ARC forbids the implicit conversion of object pointers to 'void *',
       // so these types are not compatible.
       Diag(QuestionLoc, diag::err_cond_voidptr_arc) << LHSTy << RHSTy
           << LHS.get()->getSourceRange() << RHS.get()->getSourceRange();
       LHS = RHS = true;
       return QualType();
     }
     QualType lhptee = LHSTy->castAs<PointerType>()->getPointeeType();
     QualType rhptee = RHSTy->castAs<ObjCObjectPointerType>()->getPointeeType();
     QualType destPointee
     = Context.getQualifiedType(lhptee, rhptee.getQualifiers());
     QualType destType = Context.getPointerType(destPointee);
     // Add qualifiers if necessary.
     LHS = ImpCastExprToType(LHS.get(), destType, CK_NoOp);
     // Promote to void*.
     RHS = ImpCastExprToType(RHS.get(), destType, CK_BitCast);
     return destType;
   }
   if (LHSTy->isObjCObjectPointerType() && RHSTy->isVoidPointerType()) {
     if (getLangOpts().ObjCAutoRefCount) {
       // ARC forbids the implicit conversion of object pointers to 'void *',
       // so these types are not compatible.
       Diag(QuestionLoc, diag::err_cond_voidptr_arc) << LHSTy << RHSTy
           << LHS.get()->getSourceRange() << RHS.get()->getSourceRange();
       LHS = RHS = true;
       return QualType();
     }
     QualType lhptee = LHSTy->castAs<ObjCObjectPointerType>()->getPointeeType();
     QualType rhptee = RHSTy->castAs<PointerType>()->getPointeeType();
     QualType destPointee
     = Context.getQualifiedType(rhptee, lhptee.getQualifiers());
     QualType destType = Context.getPointerType(destPointee);
     // Add qualifiers if necessary.
     RHS = ImpCastExprToType(RHS.get(), destType, CK_NoOp);
     // Promote to void*.
     LHS = ImpCastExprToType(LHS.get(), destType, CK_BitCast);
     return destType;
   }
   return QualType();
 }
 
 /// SuggestParentheses - Emit a note with a fixit hint that wraps
 /// ParenRange in parentheses.
 static void SuggestParentheses(Sema &Self, SourceLocation Loc,
                                const PartialDiagnostic &Note,
                                SourceRange ParenRange) {
   SourceLocation EndLoc = Self.getLocForEndOfToken(ParenRange.getEnd());
   if (ParenRange.getBegin().isFileID() && ParenRange.getEnd().isFileID() &&
       EndLoc.isValid()) {
     Self.Diag(Loc, Note)
       << FixItHint::CreateInsertion(ParenRange.getBegin(), "(")
       << FixItHint::CreateInsertion(EndLoc, ")");
   } else {
     // We can't display the parentheses, so just show the bare note.
     Self.Diag(Loc, Note) << ParenRange;
   }
 }
 
 static bool IsArithmeticOp(BinaryOperatorKind Opc) {
   return BinaryOperator::isAdditiveOp(Opc) ||
          BinaryOperator::isMultiplicativeOp(Opc) ||
          BinaryOperator::isShiftOp(Opc) || Opc == BO_And || Opc == BO_Or;
   // This only checks for bitwise-or and bitwise-and, but not bitwise-xor and
   // not any of the logical operators.  Bitwise-xor is commonly used as a
   // logical-xor because there is no logical-xor operator.  The logical
   // operators, including uses of xor, have a high false positive rate for
   // precedence warnings.
 }
 
 /// IsArithmeticBinaryExpr - Returns true if E is an arithmetic binary
 /// expression, either using a built-in or overloaded operator,
 /// and sets *OpCode to the opcode and *RHSExprs to the right-hand side
 /// expression.
 static bool IsArithmeticBinaryExpr(Expr *E, BinaryOperatorKind *Opcode,
                                    Expr **RHSExprs) {
   // Don't strip parenthesis: we should not warn if E is in parenthesis.
   E = E->IgnoreImpCasts();
   E = E->IgnoreConversionOperatorSingleStep();
   E = E->IgnoreImpCasts();
   if (auto *MTE = dyn_cast<MaterializeTemporaryExpr>(E)) {
     E = MTE->getSubExpr();
     E = E->IgnoreImpCasts();
   }
 
   // Built-in binary operator.
   if (BinaryOperator *OP = dyn_cast<BinaryOperator>(E)) {
     if (IsArithmeticOp(OP->getOpcode())) {
       *Opcode = OP->getOpcode();
       *RHSExprs = OP->getRHS();
       return true;
     }
   }
 
   // Overloaded operator.
   if (CXXOperatorCallExpr *Call = dyn_cast<CXXOperatorCallExpr>(E)) {
     if (Call->getNumArgs() != 2)
       return false;
 
     // Make sure this is really a binary operator that is safe to pass into
     // BinaryOperator::getOverloadedOpcode(), e.g. it's not a subscript op.
     OverloadedOperatorKind OO = Call->getOperator();
     if (OO < OO_Plus || OO > OO_Arrow ||
         OO == OO_PlusPlus || OO == OO_MinusMinus)
       return false;
 
     BinaryOperatorKind OpKind = BinaryOperator::getOverloadedOpcode(OO);
     if (IsArithmeticOp(OpKind)) {
       *Opcode = OpKind;
       *RHSExprs = Call->getArg(1);
       return true;
     }
   }
 
   return false;
 }
 
 /// ExprLooksBoolean - Returns true if E looks boolean, i.e. it has boolean type
 /// or is a logical expression such as (x==y) which has int type, but is
 /// commonly interpreted as boolean.
 static bool ExprLooksBoolean(Expr *E) {
   E = E->IgnoreParenImpCasts();
 
   if (E->getType()->isBooleanType())
     return true;
   if (BinaryOperator *OP = dyn_cast<BinaryOperator>(E))
     return OP->isComparisonOp() || OP->isLogicalOp();
   if (UnaryOperator *OP = dyn_cast<UnaryOperator>(E))
     return OP->getOpcode() == UO_LNot;
   if (E->getType()->isPointerType())
     return true;
   // FIXME: What about overloaded operator calls returning "unspecified boolean
   // type"s (commonly pointer-to-members)?
 
   return false;
 }
 
 /// DiagnoseConditionalPrecedence - Emit a warning when a conditional operator
 /// and binary operator are mixed in a way that suggests the programmer assumed
 /// the conditional operator has higher precedence, for example:
 /// "int x = a + someBinaryCondition ? 1 : 2".
 static void DiagnoseConditionalPrecedence(Sema &Self,
                                           SourceLocation OpLoc,
                                           Expr *Condition,
                                           Expr *LHSExpr,
                                           Expr *RHSExpr) {
   BinaryOperatorKind CondOpcode;
   Expr *CondRHS;
 
   if (!IsArithmeticBinaryExpr(Condition, &CondOpcode, &CondRHS))
     return;
   if (!ExprLooksBoolean(CondRHS))
     return;
 
   // The condition is an arithmetic binary expression, with a right-
   // hand side that looks boolean, so warn.
 
   unsigned DiagID = BinaryOperator::isBitwiseOp(CondOpcode)
                         ? diag::warn_precedence_bitwise_conditional
                         : diag::warn_precedence_conditional;
 
   Self.Diag(OpLoc, DiagID)
       << Condition->getSourceRange()
       << BinaryOperator::getOpcodeStr(CondOpcode);
 
   SuggestParentheses(
       Self, OpLoc,
       Self.PDiag(diag::note_precedence_silence)
           << BinaryOperator::getOpcodeStr(CondOpcode),
       SourceRange(Condition->getBeginLoc(), Condition->getEndLoc()));
 
   SuggestParentheses(Self, OpLoc,
                      Self.PDiag(diag::note_precedence_conditional_first),
                      SourceRange(CondRHS->getBeginLoc(), RHSExpr->getEndLoc()));
 }
 
 /// Compute the nullability of a conditional expression.
 static QualType computeConditionalNullability(QualType ResTy, bool IsBin,
                                               QualType LHSTy, QualType RHSTy,
                                               ASTContext &Ctx) {
   if (!ResTy->isAnyPointerType())
     return ResTy;
 
   auto GetNullability = [](QualType Ty) {
     std::optional<NullabilityKind> Kind = Ty->getNullability();
     if (Kind) {
       // For our purposes, treat _Nullable_result as _Nullable.
       if (*Kind == NullabilityKind::NullableResult)
         return NullabilityKind::Nullable;
       return *Kind;
     }
     return NullabilityKind::Unspecified;
   };
 
   auto LHSKind = GetNullability(LHSTy), RHSKind = GetNullability(RHSTy);
   NullabilityKind MergedKind;
 
   // Compute nullability of a binary conditional expression.
   if (IsBin) {
     if (LHSKind == NullabilityKind::NonNull)
       MergedKind = NullabilityKind::NonNull;
     else
       MergedKind = RHSKind;
   // Compute nullability of a normal conditional expression.
   } else {
     if (LHSKind == NullabilityKind::Nullable ||
         RHSKind == NullabilityKind::Nullable)
       MergedKind = NullabilityKind::Nullable;
     else if (LHSKind == NullabilityKind::NonNull)
       MergedKind = RHSKind;
     else if (RHSKind == NullabilityKind::NonNull)
       MergedKind = LHSKind;
     else
       MergedKind = NullabilityKind::Unspecified;
   }
 
   // Return if ResTy already has the correct nullability.
   if (GetNullability(ResTy) == MergedKind)
     return ResTy;
 
   // Strip all nullability from ResTy.
   while (ResTy->getNullability())
     ResTy = ResTy.getSingleStepDesugaredType(Ctx);
 
   // Create a new AttributedType with the new nullability kind.
   auto NewAttr = AttributedType::getNullabilityAttrKind(MergedKind);
   return Ctx.getAttributedType(NewAttr, ResTy, ResTy);
 }
 
 /// ActOnConditionalOp - Parse a ?: operation.  Note that 'LHS' may be null
 /// in the case of a the GNU conditional expr extension.
 ExprResult Sema::ActOnConditionalOp(SourceLocation QuestionLoc,
                                     SourceLocation ColonLoc,
                                     Expr *CondExpr, Expr *LHSExpr,
                                     Expr *RHSExpr) {
   if (!Context.isDependenceAllowed()) {
     // C cannot handle TypoExpr nodes in the condition because it
     // doesn't handle dependent types properly, so make sure any TypoExprs have
     // been dealt with before checking the operands.
     ExprResult CondResult = CorrectDelayedTyposInExpr(CondExpr);
     ExprResult LHSResult = CorrectDelayedTyposInExpr(LHSExpr);
     ExprResult RHSResult = CorrectDelayedTyposInExpr(RHSExpr);
 
     if (!CondResult.isUsable())
       return ExprError();
 
     if (LHSExpr) {
       if (!LHSResult.isUsable())
         return ExprError();
     }
 
     if (!RHSResult.isUsable())
       return ExprError();
 
     CondExpr = CondResult.get();
     LHSExpr = LHSResult.get();
     RHSExpr = RHSResult.get();
   }
 
   // If this is the gnu "x ?: y" extension, analyze the types as though the LHS
   // was the condition.
   OpaqueValueExpr *opaqueValue = nullptr;
   Expr *commonExpr = nullptr;
   if (!LHSExpr) {
     commonExpr = CondExpr;
     // Lower out placeholder types first.  This is important so that we don't
     // try to capture a placeholder. This happens in few cases in C++; such
     // as Objective-C++'s dictionary subscripting syntax.
     if (commonExpr->hasPlaceholderType()) {
       ExprResult result = CheckPlaceholderExpr(commonExpr);
       if (!result.isUsable()) return ExprError();
       commonExpr = result.get();
     }
     // We usually want to apply unary conversions *before* saving, except
     // in the special case of a C++ l-value conditional.
     if (!(getLangOpts().CPlusPlus
           && !commonExpr->isTypeDependent()
           && commonExpr->getValueKind() == RHSExpr->getValueKind()
           && commonExpr->isGLValue()
           && commonExpr->isOrdinaryOrBitFieldObject()
           && RHSExpr->isOrdinaryOrBitFieldObject()
           && Context.hasSameType(commonExpr->getType(), RHSExpr->getType()))) {
       ExprResult commonRes = UsualUnaryConversions(commonExpr);
       if (commonRes.isInvalid())
         return ExprError();
       commonExpr = commonRes.get();
     }
 
     // If the common expression is a class or array prvalue, materialize it
     // so that we can safely refer to it multiple times.
     if (commonExpr->isPRValue() && (commonExpr->getType()->isRecordType() ||
                                     commonExpr->getType()->isArrayType())) {
       ExprResult MatExpr = TemporaryMaterializationConversion(commonExpr);
       if (MatExpr.isInvalid())
         return ExprError();
       commonExpr = MatExpr.get();
     }
 
     opaqueValue = new (Context) OpaqueValueExpr(commonExpr->getExprLoc(),
                                                 commonExpr->getType(),
                                                 commonExpr->getValueKind(),
                                                 commonExpr->getObjectKind(),
                                                 commonExpr);
     LHSExpr = CondExpr = opaqueValue;
   }
 
   QualType LHSTy = LHSExpr->getType(), RHSTy = RHSExpr->getType();
   ExprValueKind VK = VK_PRValue;
   ExprObjectKind OK = OK_Ordinary;
   ExprResult Cond = CondExpr, LHS = LHSExpr, RHS = RHSExpr;
   QualType result = CheckConditionalOperands(Cond, LHS, RHS,
                                              VK, OK, QuestionLoc);
   if (result.isNull() || Cond.isInvalid() || LHS.isInvalid() ||
       RHS.isInvalid())
     return ExprError();
 
   DiagnoseConditionalPrecedence(*this, QuestionLoc, Cond.get(), LHS.get(),
                                 RHS.get());
 
   CheckBoolLikeConversion(Cond.get(), QuestionLoc);
 
   result = computeConditionalNullability(result, commonExpr, LHSTy, RHSTy,
                                          Context);
 
   if (!commonExpr)
     return new (Context)
         ConditionalOperator(Cond.get(), QuestionLoc, LHS.get(), ColonLoc,
                             RHS.get(), result, VK, OK);
 
   return new (Context) BinaryConditionalOperator(
       commonExpr, opaqueValue, Cond.get(), LHS.get(), RHS.get(), QuestionLoc,
       ColonLoc, result, VK, OK);
 }
 
 // Check if we have a conversion between incompatible cmse function pointer
 // types, that is, a conversion between a function pointer with the
 // cmse_nonsecure_call attribute and one without.
 static bool IsInvalidCmseNSCallConversion(Sema &S, QualType FromType,
                                           QualType ToType) {
   if (const auto *ToFn =
           dyn_cast<FunctionType>(S.Context.getCanonicalType(ToType))) {
     if (const auto *FromFn =
             dyn_cast<FunctionType>(S.Context.getCanonicalType(FromType))) {
       FunctionType::ExtInfo ToEInfo = ToFn->getExtInfo();
       FunctionType::ExtInfo FromEInfo = FromFn->getExtInfo();
 
       return ToEInfo.getCmseNSCall() != FromEInfo.getCmseNSCall();
     }
   }
   return false;
 }
 
 // checkPointerTypesForAssignment - This is a very tricky routine (despite
 // being closely modeled after the C99 spec:-). The odd characteristic of this
 // routine is it effectively iqnores the qualifiers on the top level pointee.
 // This circumvents the usual type rules specified in 6.2.7p1 & 6.7.5.[1-3].
 // FIXME: add a couple examples in this comment.
 static Sema::AssignConvertType
 checkPointerTypesForAssignment(Sema &S, QualType LHSType, QualType RHSType,
                                SourceLocation Loc) {
   assert(LHSType.isCanonical() && "LHS not canonicalized!");
   assert(RHSType.isCanonical() && "RHS not canonicalized!");
 
   // get the "pointed to" type (ignoring qualifiers at the top level)
   const Type *lhptee, *rhptee;
   Qualifiers lhq, rhq;
   std::tie(lhptee, lhq) =
       cast<PointerType>(LHSType)->getPointeeType().split().asPair();
   std::tie(rhptee, rhq) =
       cast<PointerType>(RHSType)->getPointeeType().split().asPair();
 
   Sema::AssignConvertType ConvTy = Sema::Compatible;
 
   // C99 6.5.16.1p1: This following citation is common to constraints
   // 3 & 4 (below). ...and the type *pointed to* by the left has all the
   // qualifiers of the type *pointed to* by the right;
 
   // As a special case, 'non-__weak A *' -> 'non-__weak const *' is okay.
   if (lhq.getObjCLifetime() != rhq.getObjCLifetime() &&
       lhq.compatiblyIncludesObjCLifetime(rhq)) {
     // Ignore lifetime for further calculation.
     lhq.removeObjCLifetime();
     rhq.removeObjCLifetime();
   }
 
   if (!lhq.compatiblyIncludes(rhq)) {
     // Treat address-space mismatches as fatal.
     if (!lhq.isAddressSpaceSupersetOf(rhq))
       return Sema::IncompatiblePointerDiscardsQualifiers;
 
     // It's okay to add or remove GC or lifetime qualifiers when converting to
     // and from void*.
     else if (lhq.withoutObjCGCAttr().withoutObjCLifetime()
                         .compatiblyIncludes(
                                 rhq.withoutObjCGCAttr().withoutObjCLifetime())
              && (lhptee->isVoidType() || rhptee->isVoidType()))
       ; // keep old
 
     // Treat lifetime mismatches as fatal.
     else if (lhq.getObjCLifetime() != rhq.getObjCLifetime())
       ConvTy = Sema::IncompatiblePointerDiscardsQualifiers;
 
     // For GCC/MS compatibility, other qualifier mismatches are treated
     // as still compatible in C.
     else ConvTy = Sema::CompatiblePointerDiscardsQualifiers;
   }
 
   // C99 6.5.16.1p1 (constraint 4): If one operand is a pointer to an object or
   // incomplete type and the other is a pointer to a qualified or unqualified
   // version of void...
   if (lhptee->isVoidType()) {
     if (rhptee->isIncompleteOrObjectType())
       return ConvTy;
 
     // As an extension, we allow cast to/from void* to function pointer.
     assert(rhptee->isFunctionType());
     return Sema::FunctionVoidPointer;
   }
 
   if (rhptee->isVoidType()) {
     if (lhptee->isIncompleteOrObjectType())
       return ConvTy;
 
     // As an extension, we allow cast to/from void* to function pointer.
     assert(lhptee->isFunctionType());
     return Sema::FunctionVoidPointer;
   }
 
   if (!S.Diags.isIgnored(
           diag::warn_typecheck_convert_incompatible_function_pointer_strict,
           Loc) &&
       RHSType->isFunctionPointerType() && LHSType->isFunctionPointerType() &&
       !S.IsFunctionConversion(RHSType, LHSType, RHSType))
     return Sema::IncompatibleFunctionPointerStrict;
 
   // C99 6.5.16.1p1 (constraint 3): both operands are pointers to qualified or
   // unqualified versions of compatible types, ...
   QualType ltrans = QualType(lhptee, 0), rtrans = QualType(rhptee, 0);
   if (!S.Context.typesAreCompatible(ltrans, rtrans)) {
     // Check if the pointee types are compatible ignoring the sign.
     // We explicitly check for char so that we catch "char" vs
     // "unsigned char" on systems where "char" is unsigned.
     if (lhptee->isCharType())
       ltrans = S.Context.UnsignedCharTy;
     else if (lhptee->hasSignedIntegerRepresentation())
       ltrans = S.Context.getCorrespondingUnsignedType(ltrans);
 
     if (rhptee->isCharType())
       rtrans = S.Context.UnsignedCharTy;
     else if (rhptee->hasSignedIntegerRepresentation())
       rtrans = S.Context.getCorrespondingUnsignedType(rtrans);
 
     if (ltrans == rtrans) {
       // Types are compatible ignoring the sign. Qualifier incompatibility
       // takes priority over sign incompatibility because the sign
       // warning can be disabled.
       if (ConvTy != Sema::Compatible)
         return ConvTy;
 
       return Sema::IncompatiblePointerSign;
     }
 
     // If we are a multi-level pointer, it's possible that our issue is simply
     // one of qualification - e.g. char ** -> const char ** is not allowed. If
     // the eventual target type is the same and the pointers have the same
     // level of indirection, this must be the issue.
     if (isa<PointerType>(lhptee) && isa<PointerType>(rhptee)) {
       do {
         std::tie(lhptee, lhq) =
           cast<PointerType>(lhptee)->getPointeeType().split().asPair();
         std::tie(rhptee, rhq) =
           cast<PointerType>(rhptee)->getPointeeType().split().asPair();
 
         // Inconsistent address spaces at this point is invalid, even if the
         // address spaces would be compatible.
         // FIXME: This doesn't catch address space mismatches for pointers of
         // different nesting levels, like:
         //   __local int *** a;
         //   int ** b = a;
         // It's not clear how to actually determine when such pointers are
         // invalidly incompatible.
         if (lhq.getAddressSpace() != rhq.getAddressSpace())
           return Sema::IncompatibleNestedPointerAddressSpaceMismatch;
 
       } while (isa<PointerType>(lhptee) && isa<PointerType>(rhptee));
 
       if (lhptee == rhptee)
         return Sema::IncompatibleNestedPointerQualifiers;
     }
 
     // General pointer incompatibility takes priority over qualifiers.
     if (RHSType->isFunctionPointerType() && LHSType->isFunctionPointerType())
       return Sema::IncompatibleFunctionPointer;
     return Sema::IncompatiblePointer;
   }
   if (!S.getLangOpts().CPlusPlus &&
       S.IsFunctionConversion(ltrans, rtrans, ltrans))
     return Sema::IncompatibleFunctionPointer;
   if (IsInvalidCmseNSCallConversion(S, ltrans, rtrans))
     return Sema::IncompatibleFunctionPointer;
   return ConvTy;
 }
 
 /// checkBlockPointerTypesForAssignment - This routine determines whether two
 /// block pointer types are compatible or whether a block and normal pointer
 /// are compatible. It is more restrict than comparing two function pointer
 // types.
 static Sema::AssignConvertType
 checkBlockPointerTypesForAssignment(Sema &S, QualType LHSType,
                                     QualType RHSType) {
   assert(LHSType.isCanonical() && "LHS not canonicalized!");
   assert(RHSType.isCanonical() && "RHS not canonicalized!");
 
   QualType lhptee, rhptee;
 
   // get the "pointed to" type (ignoring qualifiers at the top level)
   lhptee = cast<BlockPointerType>(LHSType)->getPointeeType();
   rhptee = cast<BlockPointerType>(RHSType)->getPointeeType();
 
   // In C++, the types have to match exactly.
   if (S.getLangOpts().CPlusPlus)
     return Sema::IncompatibleBlockPointer;
 
   Sema::AssignConvertType ConvTy = Sema::Compatible;
 
   // For blocks we enforce that qualifiers are identical.
   Qualifiers LQuals = lhptee.getLocalQualifiers();
   Qualifiers RQuals = rhptee.getLocalQualifiers();
   if (S.getLangOpts().OpenCL) {
     LQuals.removeAddressSpace();
     RQuals.removeAddressSpace();
   }
   if (LQuals != RQuals)
     ConvTy = Sema::CompatiblePointerDiscardsQualifiers;
 
   // FIXME: OpenCL doesn't define the exact compile time semantics for a block
   // assignment.
   // The current behavior is similar to C++ lambdas. A block might be
   // assigned to a variable iff its return type and parameters are compatible
   // (C99 6.2.7) with the corresponding return type and parameters of the LHS of
   // an assignment. Presumably it should behave in way that a function pointer
   // assignment does in C, so for each parameter and return type:
   //  * CVR and address space of LHS should be a superset of CVR and address
   //  space of RHS.
   //  * unqualified types should be compatible.
   if (S.getLangOpts().OpenCL) {
     if (!S.Context.typesAreBlockPointerCompatible(
             S.Context.getQualifiedType(LHSType.getUnqualifiedType(), LQuals),
             S.Context.getQualifiedType(RHSType.getUnqualifiedType(), RQuals)))
       return Sema::IncompatibleBlockPointer;
   } else if (!S.Context.typesAreBlockPointerCompatible(LHSType, RHSType))
     return Sema::IncompatibleBlockPointer;
 
   return ConvTy;
 }
 
 /// checkObjCPointerTypesForAssignment - Compares two objective-c pointer types
 /// for assignment compatibility.
 static Sema::AssignConvertType
 checkObjCPointerTypesForAssignment(Sema &S, QualType LHSType,
                                    QualType RHSType) {
   assert(LHSType.isCanonical() && "LHS was not canonicalized!");
   assert(RHSType.isCanonical() && "RHS was not canonicalized!");
 
   if (LHSType->isObjCBuiltinType()) {
     // Class is not compatible with ObjC object pointers.
     if (LHSType->isObjCClassType() && !RHSType->isObjCBuiltinType() &&
         !RHSType->isObjCQualifiedClassType())
       return Sema::IncompatiblePointer;
     return Sema::Compatible;
   }
   if (RHSType->isObjCBuiltinType()) {
     if (RHSType->isObjCClassType() && !LHSType->isObjCBuiltinType() &&
         !LHSType->isObjCQualifiedClassType())
       return Sema::IncompatiblePointer;
     return Sema::Compatible;
   }
   QualType lhptee = LHSType->castAs<ObjCObjectPointerType>()->getPointeeType();
   QualType rhptee = RHSType->castAs<ObjCObjectPointerType>()->getPointeeType();
 
   if (!lhptee.isAtLeastAsQualifiedAs(rhptee) &&
       // make an exception for id<P>
       !LHSType->isObjCQualifiedIdType())
     return Sema::CompatiblePointerDiscardsQualifiers;
 
   if (S.Context.typesAreCompatible(LHSType, RHSType))
     return Sema::Compatible;
   if (LHSType->isObjCQualifiedIdType() || RHSType->isObjCQualifiedIdType())
     return Sema::IncompatibleObjCQualifiedId;
   return Sema::IncompatiblePointer;
 }
 
 Sema::AssignConvertType
 Sema::CheckAssignmentConstraints(SourceLocation Loc,
                                  QualType LHSType, QualType RHSType) {
   // Fake up an opaque expression.  We don't actually care about what
   // cast operations are required, so if CheckAssignmentConstraints
   // adds casts to this they'll be wasted, but fortunately that doesn't
   // usually happen on valid code.
   OpaqueValueExpr RHSExpr(Loc, RHSType, VK_PRValue);
   ExprResult RHSPtr = &RHSExpr;
   CastKind K;
 
   return CheckAssignmentConstraints(LHSType, RHSPtr, K, /*ConvertRHS=*/false);
 }
 
 /// This helper function returns true if QT is a vector type that has element
 /// type ElementType.
 static bool isVector(QualType QT, QualType ElementType) {
   if (const VectorType *VT = QT->getAs<VectorType>())
     return VT->getElementType().getCanonicalType() == ElementType;
   return false;
 }
 
 /// CheckAssignmentConstraints (C99 6.5.16) - This routine currently
 /// has code to accommodate several GCC extensions when type checking
 /// pointers. Here are some objectionable examples that GCC considers warnings:
 ///
 ///  int a, *pint;
 ///  short *pshort;
 ///  struct foo *pfoo;
 ///
 ///  pint = pshort; // warning: assignment from incompatible pointer type
 ///  a = pint; // warning: assignment makes integer from pointer without a cast
 ///  pint = a; // warning: assignment makes pointer from integer without a cast
 ///  pint = pfoo; // warning: assignment from incompatible pointer type
 ///
 /// As a result, the code for dealing with pointers is more complex than the
 /// C99 spec dictates.
 ///
 /// Sets 'Kind' for any result kind except Incompatible.
 Sema::AssignConvertType
 Sema::CheckAssignmentConstraints(QualType LHSType, ExprResult &RHS,
                                  CastKind &Kind, bool ConvertRHS) {
   QualType RHSType = RHS.get()->getType();
   QualType OrigLHSType = LHSType;
 
   // Get canonical types.  We're not formatting these types, just comparing
   // them.
   LHSType = Context.getCanonicalType(LHSType).getUnqualifiedType();
   RHSType = Context.getCanonicalType(RHSType).getUnqualifiedType();
 
   // Common case: no conversion required.
   if (LHSType == RHSType) {
     Kind = CK_NoOp;
     return Compatible;
   }
 
   // If the LHS has an __auto_type, there are no additional type constraints
   // to be worried about.
   if (const auto *AT = dyn_cast<AutoType>(LHSType)) {
     if (AT->isGNUAutoType()) {
       Kind = CK_NoOp;
       return Compatible;
     }
   }
 
   // If we have an atomic type, try a non-atomic assignment, then just add an
   // atomic qualification step.
   if (const AtomicType *AtomicTy = dyn_cast<AtomicType>(LHSType)) {
     Sema::AssignConvertType result =
       CheckAssignmentConstraints(AtomicTy->getValueType(), RHS, Kind);
     if (result != Compatible)
       return result;
     if (Kind != CK_NoOp && ConvertRHS)
       RHS = ImpCastExprToType(RHS.get(), AtomicTy->getValueType(), Kind);
     Kind = CK_NonAtomicToAtomic;
     return Compatible;
   }
 
   // If the left-hand side is a reference type, then we are in a
   // (rare!) case where we've allowed the use of references in C,
   // e.g., as a parameter type in a built-in function. In this case,
   // just make sure that the type referenced is compatible with the
   // right-hand side type. The caller is responsible for adjusting
   // LHSType so that the resulting expression does not have reference
   // type.
   if (const ReferenceType *LHSTypeRef = LHSType->getAs<ReferenceType>()) {
     if (Context.typesAreCompatible(LHSTypeRef->getPointeeType(), RHSType)) {
       Kind = CK_LValueBitCast;
       return Compatible;
     }
     return Incompatible;
   }
 
   // Allow scalar to ExtVector assignments, and assignments of an ExtVector type
   // to the same ExtVector type.
   if (LHSType->isExtVectorType()) {
     if (RHSType->isExtVectorType())
       return Incompatible;
     if (RHSType->isArithmeticType()) {
       // CK_VectorSplat does T -> vector T, so first cast to the element type.
       if (ConvertRHS)
         RHS = prepareVectorSplat(LHSType, RHS.get());
       Kind = CK_VectorSplat;
       return Compatible;
     }
   }
 
   // Conversions to or from vector type.
   if (LHSType->isVectorType() || RHSType->isVectorType()) {
     if (LHSType->isVectorType() && RHSType->isVectorType()) {
       // Allow assignments of an AltiVec vector type to an equivalent GCC
       // vector type and vice versa
       if (Context.areCompatibleVectorTypes(LHSType, RHSType)) {
         Kind = CK_BitCast;
         return Compatible;
       }
 
       // If we are allowing lax vector conversions, and LHS and RHS are both
       // vectors, the total size only needs to be the same. This is a bitcast;
       // no bits are changed but the result type is different.
       if (isLaxVectorConversion(RHSType, LHSType)) {
         // The default for lax vector conversions with Altivec vectors will
         // change, so if we are converting between vector types where
         // at least one is an Altivec vector, emit a warning.
         if (Context.getTargetInfo().getTriple().isPPC() &&
             anyAltivecTypes(RHSType, LHSType) &&
             !Context.areCompatibleVectorTypes(RHSType, LHSType))
           Diag(RHS.get()->getExprLoc(), diag::warn_deprecated_lax_vec_conv_all)
               << RHSType << LHSType;
         Kind = CK_BitCast;
         return IncompatibleVectors;
       }
     }
 
     // When the RHS comes from another lax conversion (e.g. binops between
     // scalars and vectors) the result is canonicalized as a vector. When the
     // LHS is also a vector, the lax is allowed by the condition above. Handle
     // the case where LHS is a scalar.
     if (LHSType->isScalarType()) {
       const VectorType *VecType = RHSType->getAs<VectorType>();
       if (VecType && VecType->getNumElements() == 1 &&
           isLaxVectorConversion(RHSType, LHSType)) {
         if (Context.getTargetInfo().getTriple().isPPC() &&
             (VecType->getVectorKind() == VectorType::AltiVecVector ||
              VecType->getVectorKind() == VectorType::AltiVecBool ||
              VecType->getVectorKind() == VectorType::AltiVecPixel))
           Diag(RHS.get()->getExprLoc(), diag::warn_deprecated_lax_vec_conv_all)
               << RHSType << LHSType;
         ExprResult *VecExpr = &RHS;
         *VecExpr = ImpCastExprToType(VecExpr->get(), LHSType, CK_BitCast);
         Kind = CK_BitCast;
         return Compatible;
       }
     }
 
     // Allow assignments between fixed-length and sizeless SVE vectors.
     if ((LHSType->isSVESizelessBuiltinType() && RHSType->isVectorType()) ||
         (LHSType->isVectorType() && RHSType->isSVESizelessBuiltinType()))
       if (Context.areCompatibleSveTypes(LHSType, RHSType) ||
           Context.areLaxCompatibleSveTypes(LHSType, RHSType)) {
         Kind = CK_BitCast;
         return Compatible;
       }
 
     // Allow assignments between fixed-length and sizeless RVV vectors.
     if ((LHSType->isRVVSizelessBuiltinType() && RHSType->isVectorType()) ||
         (LHSType->isVectorType() && RHSType->isRVVSizelessBuiltinType())) {
       if (Context.areCompatibleRVVTypes(LHSType, RHSType) ||
           Context.areLaxCompatibleRVVTypes(LHSType, RHSType)) {
         Kind = CK_BitCast;
         return Compatible;
       }
     }
 
     return Incompatible;
   }
 
   // Diagnose attempts to convert between __ibm128, __float128 and long double
   // where such conversions currently can't be handled.
   if (unsupportedTypeConversion(*this, LHSType, RHSType))
     return Incompatible;
 
   // Disallow assigning a _Complex to a real type in C++ mode since it simply
   // discards the imaginary part.
   if (getLangOpts().CPlusPlus && RHSType->getAs<ComplexType>() &&
       !LHSType->getAs<ComplexType>())
     return Incompatible;
 
   // Arithmetic conversions.
   if (LHSType->isArithmeticType() && RHSType->isArithmeticType() &&
       !(getLangOpts().CPlusPlus && LHSType->isEnumeralType())) {
     if (ConvertRHS)
       Kind = PrepareScalarCast(RHS, LHSType);
     return Compatible;
   }
 
   // Conversions to normal pointers.
   if (const PointerType *LHSPointer = dyn_cast<PointerType>(LHSType)) {
     // U* -> T*
     if (isa<PointerType>(RHSType)) {
       LangAS AddrSpaceL = LHSPointer->getPointeeType().getAddressSpace();
       LangAS AddrSpaceR = RHSType->getPointeeType().getAddressSpace();
       if (AddrSpaceL != AddrSpaceR)
         Kind = CK_AddressSpaceConversion;
       else if (Context.hasCvrSimilarType(RHSType, LHSType))
         Kind = CK_NoOp;
       else
         Kind = CK_BitCast;
       return checkPointerTypesForAssignment(*this, LHSType, RHSType,
                                             RHS.get()->getBeginLoc());
     }
 
     // int -> T*
     if (RHSType->isIntegerType()) {
       Kind = CK_IntegralToPointer; // FIXME: null?
       return IntToPointer;
     }
 
     // C pointers are not compatible with ObjC object pointers,
     // with two exceptions:
     if (isa<ObjCObjectPointerType>(RHSType)) {
       //  - conversions to void*
       if (LHSPointer->getPointeeType()->isVoidType()) {
         Kind = CK_BitCast;
         return Compatible;
       }
 
       //  - conversions from 'Class' to the redefinition type
       if (RHSType->isObjCClassType() &&
           Context.hasSameType(LHSType,
                               Context.getObjCClassRedefinitionType())) {
         Kind = CK_BitCast;
         return Compatible;
       }
 
       Kind = CK_BitCast;
       return IncompatiblePointer;
     }
 
     // U^ -> void*
     if (RHSType->getAs<BlockPointerType>()) {
       if (LHSPointer->getPointeeType()->isVoidType()) {
         LangAS AddrSpaceL = LHSPointer->getPointeeType().getAddressSpace();
         LangAS AddrSpaceR = RHSType->getAs<BlockPointerType>()
                                 ->getPointeeType()
                                 .getAddressSpace();
         Kind =
             AddrSpaceL != AddrSpaceR ? CK_AddressSpaceConversion : CK_BitCast;
         return Compatible;
       }
     }
 
     return Incompatible;
   }
 
   // Conversions to block pointers.
   if (isa<BlockPointerType>(LHSType)) {
     // U^ -> T^
     if (RHSType->isBlockPointerType()) {
       LangAS AddrSpaceL = LHSType->getAs<BlockPointerType>()
                               ->getPointeeType()
                               .getAddressSpace();
       LangAS AddrSpaceR = RHSType->getAs<BlockPointerType>()
                               ->getPointeeType()
                               .getAddressSpace();
       Kind = AddrSpaceL != AddrSpaceR ? CK_AddressSpaceConversion : CK_BitCast;
       return checkBlockPointerTypesForAssignment(*this, LHSType, RHSType);
     }
 
     // int or null -> T^
     if (RHSType->isIntegerType()) {
       Kind = CK_IntegralToPointer; // FIXME: null
       return IntToBlockPointer;
     }
 
     // id -> T^
     if (getLangOpts().ObjC && RHSType->isObjCIdType()) {
       Kind = CK_AnyPointerToBlockPointerCast;
       return Compatible;
     }
 
     // void* -> T^
     if (const PointerType *RHSPT = RHSType->getAs<PointerType>())
       if (RHSPT->getPointeeType()->isVoidType()) {
         Kind = CK_AnyPointerToBlockPointerCast;
         return Compatible;
       }
 
     return Incompatible;
   }
 
   // Conversions to Objective-C pointers.
   if (isa<ObjCObjectPointerType>(LHSType)) {
     // A* -> B*
     if (RHSType->isObjCObjectPointerType()) {
       Kind = CK_BitCast;
       Sema::AssignConvertType result =
         checkObjCPointerTypesForAssignment(*this, LHSType, RHSType);
       if (getLangOpts().allowsNonTrivialObjCLifetimeQualifiers() &&
           result == Compatible &&
           !CheckObjCARCUnavailableWeakConversion(OrigLHSType, RHSType))
         result = IncompatibleObjCWeakRef;
       return result;
     }
 
     // int or null -> A*
     if (RHSType->isIntegerType()) {
       Kind = CK_IntegralToPointer; // FIXME: null
       return IntToPointer;
     }
 
     // In general, C pointers are not compatible with ObjC object pointers,
     // with two exceptions:
     if (isa<PointerType>(RHSType)) {
       Kind = CK_CPointerToObjCPointerCast;
 
       //  - conversions from 'void*'
       if (RHSType->isVoidPointerType()) {
         return Compatible;
       }
 
       //  - conversions to 'Class' from its redefinition type
       if (LHSType->isObjCClassType() &&
           Context.hasSameType(RHSType,
                               Context.getObjCClassRedefinitionType())) {
         return Compatible;
       }
 
       return IncompatiblePointer;
     }
 
     // Only under strict condition T^ is compatible with an Objective-C pointer.
     if (RHSType->isBlockPointerType() &&
         LHSType->isBlockCompatibleObjCPointerType(Context)) {
       if (ConvertRHS)
         maybeExtendBlockObject(RHS);
       Kind = CK_BlockPointerToObjCPointerCast;
       return Compatible;
     }
 
     return Incompatible;
   }
 
   // Conversion to nullptr_t (C2x only)
   if (getLangOpts().C2x && LHSType->isNullPtrType() &&
       RHS.get()->isNullPointerConstant(Context,
                                        Expr::NPC_ValueDependentIsNull)) {
     // null -> nullptr_t
     Kind = CK_NullToPointer;
     return Compatible;
   }
 
   // Conversions from pointers that are not covered by the above.
   if (isa<PointerType>(RHSType)) {
     // T* -> _Bool
     if (LHSType == Context.BoolTy) {
       Kind = CK_PointerToBoolean;
       return Compatible;
     }
 
     // T* -> int
     if (LHSType->isIntegerType()) {
       Kind = CK_PointerToIntegral;
       return PointerToInt;
     }
 
     return Incompatible;
   }
 
   // Conversions from Objective-C pointers that are not covered by the above.
   if (isa<ObjCObjectPointerType>(RHSType)) {
     // T* -> _Bool
     if (LHSType == Context.BoolTy) {
       Kind = CK_PointerToBoolean;
       return Compatible;
     }
 
     // T* -> int
     if (LHSType->isIntegerType()) {
       Kind = CK_PointerToIntegral;
       return PointerToInt;
     }
 
     return Incompatible;
   }
 
   // struct A -> struct B
   if (isa<TagType>(LHSType) && isa<TagType>(RHSType)) {
     if (Context.typesAreCompatible(LHSType, RHSType)) {
       Kind = CK_NoOp;
       return Compatible;
     }
   }
 
   if (LHSType->isSamplerT() && RHSType->isIntegerType()) {
     Kind = CK_IntToOCLSampler;
     return Compatible;
   }
 
   return Incompatible;
 }
 
 /// Constructs a transparent union from an expression that is
 /// used to initialize the transparent union.
 static void ConstructTransparentUnion(Sema &S, ASTContext &C,
                                       ExprResult &EResult, QualType UnionType,
                                       FieldDecl *Field) {
   // Build an initializer list that designates the appropriate member
   // of the transparent union.
   Expr *E = EResult.get();
   InitListExpr *Initializer = new (C) InitListExpr(C, SourceLocation(),
                                                    E, SourceLocation());
   Initializer->setType(UnionType);
   Initializer->setInitializedFieldInUnion(Field);
 
   // Build a compound literal constructing a value of the transparent
   // union type from this initializer list.
   TypeSourceInfo *unionTInfo = C.getTrivialTypeSourceInfo(UnionType);
   EResult = new (C) CompoundLiteralExpr(SourceLocation(), unionTInfo, UnionType,
                                         VK_PRValue, Initializer, false);
 }
 
 Sema::AssignConvertType
 Sema::CheckTransparentUnionArgumentConstraints(QualType ArgType,
                                                ExprResult &RHS) {
   QualType RHSType = RHS.get()->getType();
 
   // If the ArgType is a Union type, we want to handle a potential
   // transparent_union GCC extension.
   const RecordType *UT = ArgType->getAsUnionType();
   if (!UT || !UT->getDecl()->hasAttr<TransparentUnionAttr>())
     return Incompatible;
 
   // The field to initialize within the transparent union.
   RecordDecl *UD = UT->getDecl();
   FieldDecl *InitField = nullptr;
   // It's compatible if the expression matches any of the fields.
   for (auto *it : UD->fields()) {
     if (it->getType()->isPointerType()) {
       // If the transparent union contains a pointer type, we allow:
       // 1) void pointer
       // 2) null pointer constant
       if (RHSType->isPointerType())
         if (RHSType->castAs<PointerType>()->getPointeeType()->isVoidType()) {
           RHS = ImpCastExprToType(RHS.get(), it->getType(), CK_BitCast);
           InitField = it;
           break;
         }
 
       if (RHS.get()->isNullPointerConstant(Context,
                                            Expr::NPC_ValueDependentIsNull)) {
         RHS = ImpCastExprToType(RHS.get(), it->getType(),
                                 CK_NullToPointer);
         InitField = it;
         break;
       }
     }
 
     CastKind Kind;
     if (CheckAssignmentConstraints(it->getType(), RHS, Kind)
           == Compatible) {
       RHS = ImpCastExprToType(RHS.get(), it->getType(), Kind);
       InitField = it;
       break;
     }
   }
 
   if (!InitField)
     return Incompatible;
 
   ConstructTransparentUnion(*this, Context, RHS, ArgType, InitField);
   return Compatible;
 }
 
 Sema::AssignConvertType
 Sema::CheckSingleAssignmentConstraints(QualType LHSType, ExprResult &CallerRHS,
                                        bool Diagnose,
                                        bool DiagnoseCFAudited,
                                        bool ConvertRHS) {
   // We need to be able to tell the caller whether we diagnosed a problem, if
   // they ask us to issue diagnostics.
   assert((ConvertRHS || !Diagnose) && "can't indicate whether we diagnosed");
 
   // If ConvertRHS is false, we want to leave the caller's RHS untouched. Sadly,
   // we can't avoid *all* modifications at the moment, so we need some somewhere
   // to put the updated value.
   ExprResult LocalRHS = CallerRHS;
   ExprResult &RHS = ConvertRHS ? CallerRHS : LocalRHS;
 
   if (const auto *LHSPtrType = LHSType->getAs<PointerType>()) {
     if (const auto *RHSPtrType = RHS.get()->getType()->getAs<PointerType>()) {
       if (RHSPtrType->getPointeeType()->hasAttr(attr::NoDeref) &&
           !LHSPtrType->getPointeeType()->hasAttr(attr::NoDeref)) {
         Diag(RHS.get()->getExprLoc(),
              diag::warn_noderef_to_dereferenceable_pointer)
             << RHS.get()->getSourceRange();
       }
     }
   }
 
   if (getLangOpts().CPlusPlus) {
     if (!LHSType->isRecordType() && !LHSType->isAtomicType()) {
       // C++ 5.17p3: If the left operand is not of class type, the
       // expression is implicitly converted (C++ 4) to the
       // cv-unqualified type of the left operand.
       QualType RHSType = RHS.get()->getType();
       if (Diagnose) {
         RHS = PerformImplicitConversion(RHS.get(), LHSType.getUnqualifiedType(),
                                         AA_Assigning);
       } else {
         ImplicitConversionSequence ICS =
             TryImplicitConversion(RHS.get(), LHSType.getUnqualifiedType(),
                                   /*SuppressUserConversions=*/false,
                                   AllowedExplicit::None,
                                   /*InOverloadResolution=*/false,
                                   /*CStyle=*/false,
                                   /*AllowObjCWritebackConversion=*/false);
         if (ICS.isFailure())
           return Incompatible;
         RHS = PerformImplicitConversion(RHS.get(), LHSType.getUnqualifiedType(),
                                         ICS, AA_Assigning);
       }
       if (RHS.isInvalid())
         return Incompatible;
       Sema::AssignConvertType result = Compatible;
       if (getLangOpts().allowsNonTrivialObjCLifetimeQualifiers() &&
           !CheckObjCARCUnavailableWeakConversion(LHSType, RHSType))
         result = IncompatibleObjCWeakRef;
       return result;
     }
 
     // FIXME: Currently, we fall through and treat C++ classes like C
     // structures.
     // FIXME: We also fall through for atomics; not sure what should
     // happen there, though.
   } else if (RHS.get()->getType() == Context.OverloadTy) {
     // As a set of extensions to C, we support overloading on functions. These
     // functions need to be resolved here.
     DeclAccessPair DAP;
     if (FunctionDecl *FD = ResolveAddressOfOverloadedFunction(
             RHS.get(), LHSType, /*Complain=*/false, DAP))
       RHS = FixOverloadedFunctionReference(RHS.get(), DAP, FD);
     else
       return Incompatible;
   }
 
   // This check seems unnatural, however it is necessary to ensure the proper
   // conversion of functions/arrays. If the conversion were done for all
   // DeclExpr's (created by ActOnIdExpression), it would mess up the unary
   // expressions that suppress this implicit conversion (&, sizeof). This needs
   // to happen before we check for null pointer conversions because C does not
   // undergo the same implicit conversions as C++ does above (by the calls to
   // TryImplicitConversion() and PerformImplicitConversion()) which insert the
   // lvalue to rvalue cast before checking for null pointer constraints. This
   // addresses code like: nullptr_t val; int *ptr; ptr = val;
   //
   // Suppress this for references: C++ 8.5.3p5.
   if (!LHSType->isReferenceType()) {
     // FIXME: We potentially allocate here even if ConvertRHS is false.
     RHS = DefaultFunctionArrayLvalueConversion(RHS.get(), Diagnose);
     if (RHS.isInvalid())
       return Incompatible;
   }
 
   // The constraints are expressed in terms of the atomic, qualified, or
   // unqualified type of the LHS.
   QualType LHSTypeAfterConversion = LHSType.getAtomicUnqualifiedType();
 
   // C99 6.5.16.1p1: the left operand is a pointer and the right is
   // a null pointer constant <C2x>or its type is nullptr_t;</C2x>.
   if ((LHSTypeAfterConversion->isPointerType() ||
        LHSTypeAfterConversion->isObjCObjectPointerType() ||
        LHSTypeAfterConversion->isBlockPointerType()) &&
       ((getLangOpts().C2x && RHS.get()->getType()->isNullPtrType()) ||
        RHS.get()->isNullPointerConstant(Context,
                                         Expr::NPC_ValueDependentIsNull))) {
     if (Diagnose || ConvertRHS) {
       CastKind Kind;
       CXXCastPath Path;
       CheckPointerConversion(RHS.get(), LHSType, Kind, Path,
                              /*IgnoreBaseAccess=*/false, Diagnose);
       if (ConvertRHS)
         RHS = ImpCastExprToType(RHS.get(), LHSType, Kind, VK_PRValue, &Path);
     }
     return Compatible;
   }
   // C2x 6.5.16.1p1: the left operand has type atomic, qualified, or
   // unqualified bool, and the right operand is a pointer or its type is
   // nullptr_t.
   if (getLangOpts().C2x && LHSType->isBooleanType() &&
       RHS.get()->getType()->isNullPtrType()) {
     // NB: T* -> _Bool is handled in CheckAssignmentConstraints, this only
     // only handles nullptr -> _Bool due to needing an extra conversion
     // step.
     // We model this by converting from nullptr -> void * and then let the
     // conversion from void * -> _Bool happen naturally.
     if (Diagnose || ConvertRHS) {
       CastKind Kind;
       CXXCastPath Path;
       CheckPointerConversion(RHS.get(), Context.VoidPtrTy, Kind, Path,
                              /*IgnoreBaseAccess=*/false, Diagnose);
       if (ConvertRHS)
         RHS = ImpCastExprToType(RHS.get(), Context.VoidPtrTy, Kind, VK_PRValue,
                                 &Path);
     }
   }
 
   // OpenCL queue_t type assignment.
   if (LHSType->isQueueT() && RHS.get()->isNullPointerConstant(
                                  Context, Expr::NPC_ValueDependentIsNull)) {
     RHS = ImpCastExprToType(RHS.get(), LHSType, CK_NullToPointer);
     return Compatible;
   }
 
   CastKind Kind;
   Sema::AssignConvertType result =
     CheckAssignmentConstraints(LHSType, RHS, Kind, ConvertRHS);
 
   // C99 6.5.16.1p2: The value of the right operand is converted to the
   // type of the assignment expression.
   // CheckAssignmentConstraints allows the left-hand side to be a reference,
   // so that we can use references in built-in functions even in C.
   // The getNonReferenceType() call makes sure that the resulting expression
   // does not have reference type.
   if (result != Incompatible && RHS.get()->getType() != LHSType) {
     QualType Ty = LHSType.getNonLValueExprType(Context);
     Expr *E = RHS.get();
 
     // Check for various Objective-C errors. If we are not reporting
     // diagnostics and just checking for errors, e.g., during overload
     // resolution, return Incompatible to indicate the failure.
     if (getLangOpts().allowsNonTrivialObjCLifetimeQualifiers() &&
         CheckObjCConversion(SourceRange(), Ty, E, CCK_ImplicitConversion,
                             Diagnose, DiagnoseCFAudited) != ACR_okay) {
       if (!Diagnose)
         return Incompatible;
     }
     if (getLangOpts().ObjC &&
         (CheckObjCBridgeRelatedConversions(E->getBeginLoc(), LHSType,
                                            E->getType(), E, Diagnose) ||
          CheckConversionToObjCLiteral(LHSType, E, Diagnose))) {
       if (!Diagnose)
         return Incompatible;
       // Replace the expression with a corrected version and continue so we
       // can find further errors.
       RHS = E;
       return Compatible;
     }
 
     if (ConvertRHS)
       RHS = ImpCastExprToType(E, Ty, Kind);
   }
 
   return result;
 }
 
 namespace {
 /// The original operand to an operator, prior to the application of the usual
 /// arithmetic conversions and converting the arguments of a builtin operator
 /// candidate.
 struct OriginalOperand {
   explicit OriginalOperand(Expr *Op) : Orig(Op), Conversion(nullptr) {
     if (auto *MTE = dyn_cast<MaterializeTemporaryExpr>(Op))
       Op = MTE->getSubExpr();
     if (auto *BTE = dyn_cast<CXXBindTemporaryExpr>(Op))
       Op = BTE->getSubExpr();
     if (auto *ICE = dyn_cast<ImplicitCastExpr>(Op)) {
       Orig = ICE->getSubExprAsWritten();
       Conversion = ICE->getConversionFunction();
     }
   }
 
   QualType getType() const { return Orig->getType(); }
 
   Expr *Orig;
   NamedDecl *Conversion;
 };
 }
 
 QualType Sema::InvalidOperands(SourceLocation Loc, ExprResult &LHS,
                                ExprResult &RHS) {
   OriginalOperand OrigLHS(LHS.get()), OrigRHS(RHS.get());
 
   Diag(Loc, diag::err_typecheck_invalid_operands)
     << OrigLHS.getType() << OrigRHS.getType()
     << LHS.get()->getSourceRange() << RHS.get()->getSourceRange();
 
   // If a user-defined conversion was applied to either of the operands prior
   // to applying the built-in operator rules, tell the user about it.
   if (OrigLHS.Conversion) {
     Diag(OrigLHS.Conversion->getLocation(),
          diag::note_typecheck_invalid_operands_converted)
       << 0 << LHS.get()->getType();
   }
   if (OrigRHS.Conversion) {
     Diag(OrigRHS.Conversion->getLocation(),
          diag::note_typecheck_invalid_operands_converted)
       << 1 << RHS.get()->getType();
   }
 
   return QualType();
 }
 
 // Diagnose cases where a scalar was implicitly converted to a vector and
 // diagnose the underlying types. Otherwise, diagnose the error
 // as invalid vector logical operands for non-C++ cases.
 QualType Sema::InvalidLogicalVectorOperands(SourceLocation Loc, ExprResult &LHS,
                                             ExprResult &RHS) {
   QualType LHSType = LHS.get()->IgnoreImpCasts()->getType();
   QualType RHSType = RHS.get()->IgnoreImpCasts()->getType();
 
   bool LHSNatVec = LHSType->isVectorType();
   bool RHSNatVec = RHSType->isVectorType();
 
   if (!(LHSNatVec && RHSNatVec)) {
     Expr *Vector = LHSNatVec ? LHS.get() : RHS.get();
     Expr *NonVector = !LHSNatVec ? LHS.get() : RHS.get();
     Diag(Loc, diag::err_typecheck_logical_vector_expr_gnu_cpp_restrict)
         << 0 << Vector->getType() << NonVector->IgnoreImpCasts()->getType()
         << Vector->getSourceRange();
     return QualType();
   }
 
   Diag(Loc, diag::err_typecheck_logical_vector_expr_gnu_cpp_restrict)
       << 1 << LHSType << RHSType << LHS.get()->getSourceRange()
       << RHS.get()->getSourceRange();
 
   return QualType();
 }
 
 /// Try to convert a value of non-vector type to a vector type by converting
 /// the type to the element type of the vector and then performing a splat.
 /// If the language is OpenCL, we only use conversions that promote scalar
 /// rank; for C, Obj-C, and C++ we allow any real scalar conversion except
 /// for float->int.
 ///
 /// OpenCL V2.0 6.2.6.p2:
 /// An error shall occur if any scalar operand type has greater rank
 /// than the type of the vector element.
 ///
 /// \param scalar - if non-null, actually perform the conversions
 /// \return true if the operation fails (but without diagnosing the failure)
 static bool tryVectorConvertAndSplat(Sema &S, ExprResult *scalar,
                                      QualType scalarTy,
                                      QualType vectorEltTy,
                                      QualType vectorTy,
                                      unsigned &DiagID) {
   // The conversion to apply to the scalar before splatting it,
   // if necessary.
   CastKind scalarCast = CK_NoOp;
 
   if (vectorEltTy->isIntegralType(S.Context)) {
     if (S.getLangOpts().OpenCL && (scalarTy->isRealFloatingType() ||
         (scalarTy->isIntegerType() &&
          S.Context.getIntegerTypeOrder(vectorEltTy, scalarTy) < 0))) {
       DiagID = diag::err_opencl_scalar_type_rank_greater_than_vector_type;
       return true;
     }
     if (!scalarTy->isIntegralType(S.Context))
       return true;
     scalarCast = CK_IntegralCast;
   } else if (vectorEltTy->isRealFloatingType()) {
     if (scalarTy->isRealFloatingType()) {
       if (S.getLangOpts().OpenCL &&
           S.Context.getFloatingTypeOrder(vectorEltTy, scalarTy) < 0) {
         DiagID = diag::err_opencl_scalar_type_rank_greater_than_vector_type;
         return true;
       }
       scalarCast = CK_FloatingCast;
     }
     else if (scalarTy->isIntegralType(S.Context))
       scalarCast = CK_IntegralToFloating;
     else
       return true;
   } else {
     return true;
   }
 
   // Adjust scalar if desired.
   if (scalar) {
     if (scalarCast != CK_NoOp)
       *scalar = S.ImpCastExprToType(scalar->get(), vectorEltTy, scalarCast);
     *scalar = S.ImpCastExprToType(scalar->get(), vectorTy, CK_VectorSplat);
   }
   return false;
 }
 
 /// Convert vector E to a vector with the same number of elements but different
 /// element type.
 static ExprResult convertVector(Expr *E, QualType ElementType, Sema &S) {
   const auto *VecTy = E->getType()->getAs<VectorType>();
   assert(VecTy && "Expression E must be a vector");
   QualType NewVecTy =
       VecTy->isExtVectorType()
           ? S.Context.getExtVectorType(ElementType, VecTy->getNumElements())
           : S.Context.getVectorType(ElementType, VecTy->getNumElements(),
                                     VecTy->getVectorKind());
 
   // Look through the implicit cast. Return the subexpression if its type is
   // NewVecTy.
   if (auto *ICE = dyn_cast<ImplicitCastExpr>(E))
     if (ICE->getSubExpr()->getType() == NewVecTy)
       return ICE->getSubExpr();
 
   auto Cast = ElementType->isIntegerType() ? CK_IntegralCast : CK_FloatingCast;
   return S.ImpCastExprToType(E, NewVecTy, Cast);
 }
 
 /// Test if a (constant) integer Int can be casted to another integer type
 /// IntTy without losing precision.
 static bool canConvertIntToOtherIntTy(Sema &S, ExprResult *Int,
                                       QualType OtherIntTy) {
   QualType IntTy = Int->get()->getType().getUnqualifiedType();
 
   // Reject cases where the value of the Int is unknown as that would
   // possibly cause truncation, but accept cases where the scalar can be
   // demoted without loss of precision.
   Expr::EvalResult EVResult;
   bool CstInt = Int->get()->EvaluateAsInt(EVResult, S.Context);
   int Order = S.Context.getIntegerTypeOrder(OtherIntTy, IntTy);
   bool IntSigned = IntTy->hasSignedIntegerRepresentation();
   bool OtherIntSigned = OtherIntTy->hasSignedIntegerRepresentation();
 
   if (CstInt) {
     // If the scalar is constant and is of a higher order and has more active
     // bits that the vector element type, reject it.
     llvm::APSInt Result = EVResult.Val.getInt();
     unsigned NumBits = IntSigned
                            ? (Result.isNegative() ? Result.getSignificantBits()
                                                   : Result.getActiveBits())
                            : Result.getActiveBits();
     if (Order < 0 && S.Context.getIntWidth(OtherIntTy) < NumBits)
       return true;
 
     // If the signedness of the scalar type and the vector element type
     // differs and the number of bits is greater than that of the vector
     // element reject it.
     return (IntSigned != OtherIntSigned &&
             NumBits > S.Context.getIntWidth(OtherIntTy));
   }
 
   // Reject cases where the value of the scalar is not constant and it's
   // order is greater than that of the vector element type.
   return (Order < 0);
 }
 
 /// Test if a (constant) integer Int can be casted to floating point type
 /// FloatTy without losing precision.
 static bool canConvertIntTyToFloatTy(Sema &S, ExprResult *Int,
                                      QualType FloatTy) {
   QualType IntTy = Int->get()->getType().getUnqualifiedType();
 
   // Determine if the integer constant can be expressed as a floating point
   // number of the appropriate type.
   Expr::EvalResult EVResult;
   bool CstInt = Int->get()->EvaluateAsInt(EVResult, S.Context);
 
   uint64_t Bits = 0;
   if (CstInt) {
     // Reject constants that would be truncated if they were converted to
     // the floating point type. Test by simple to/from conversion.
     // FIXME: Ideally the conversion to an APFloat and from an APFloat
     //        could be avoided if there was a convertFromAPInt method
     //        which could signal back if implicit truncation occurred.
     llvm::APSInt Result = EVResult.Val.getInt();
     llvm::APFloat Float(S.Context.getFloatTypeSemantics(FloatTy));
     Float.convertFromAPInt(Result, IntTy->hasSignedIntegerRepresentation(),
                            llvm::APFloat::rmTowardZero);
     llvm::APSInt ConvertBack(S.Context.getIntWidth(IntTy),
                              !IntTy->hasSignedIntegerRepresentation());
     bool Ignored = false;
     Float.convertToInteger(ConvertBack, llvm::APFloat::rmNearestTiesToEven,
                            &Ignored);
     if (Result != ConvertBack)
       return true;
   } else {
     // Reject types that cannot be fully encoded into the mantissa of
     // the float.
     Bits = S.Context.getTypeSize(IntTy);
     unsigned FloatPrec = llvm::APFloat::semanticsPrecision(
         S.Context.getFloatTypeSemantics(FloatTy));
     if (Bits > FloatPrec)
       return true;
   }
 
   return false;
 }
 
 /// Attempt to convert and splat Scalar into a vector whose types matches
 /// Vector following GCC conversion rules. The rule is that implicit
 /// conversion can occur when Scalar can be casted to match Vector's element
 /// type without causing truncation of Scalar.
 static bool tryGCCVectorConvertAndSplat(Sema &S, ExprResult *Scalar,
                                         ExprResult *Vector) {
   QualType ScalarTy = Scalar->get()->getType().getUnqualifiedType();
   QualType VectorTy = Vector->get()->getType().getUnqualifiedType();
   QualType VectorEltTy;
 
   if (const auto *VT = VectorTy->getAs<VectorType>()) {
     assert(!isa<ExtVectorType>(VT) &&
            "ExtVectorTypes should not be handled here!");
     VectorEltTy = VT->getElementType();
   } else if (VectorTy->isVLSTBuiltinType()) {
     VectorEltTy =
         VectorTy->castAs<BuiltinType>()->getSveEltType(S.getASTContext());
   } else {
     llvm_unreachable("Only Fixed-Length and SVE Vector types are handled here");
   }
 
   // Reject cases where the vector element type or the scalar element type are
   // not integral or floating point types.
   if (!VectorEltTy->isArithmeticType() || !ScalarTy->isArithmeticType())
     return true;
 
   // The conversion to apply to the scalar before splatting it,
   // if necessary.
   CastKind ScalarCast = CK_NoOp;
 
   // Accept cases where the vector elements are integers and the scalar is
   // an integer.
   // FIXME: Notionally if the scalar was a floating point value with a precise
   //        integral representation, we could cast it to an appropriate integer
   //        type and then perform the rest of the checks here. GCC will perform
   //        this conversion in some cases as determined by the input language.
   //        We should accept it on a language independent basis.
   if (VectorEltTy->isIntegralType(S.Context) &&
       ScalarTy->isIntegralType(S.Context) &&
       S.Context.getIntegerTypeOrder(VectorEltTy, ScalarTy)) {
 
     if (canConvertIntToOtherIntTy(S, Scalar, VectorEltTy))
       return true;
 
     ScalarCast = CK_IntegralCast;
   } else if (VectorEltTy->isIntegralType(S.Context) &&
              ScalarTy->isRealFloatingType()) {
     if (S.Context.getTypeSize(VectorEltTy) == S.Context.getTypeSize(ScalarTy))
       ScalarCast = CK_FloatingToIntegral;
     else
       return true;
   } else if (VectorEltTy->isRealFloatingType()) {
     if (ScalarTy->isRealFloatingType()) {
 
       // Reject cases where the scalar type is not a constant and has a higher
       // Order than the vector element type.
       llvm::APFloat Result(0.0);
 
       // Determine whether this is a constant scalar. In the event that the
       // value is dependent (and thus cannot be evaluated by the constant
       // evaluator), skip the evaluation. This will then diagnose once the
       // expression is instantiated.
       bool CstScalar = Scalar->get()->isValueDependent() ||
                        Scalar->get()->EvaluateAsFloat(Result, S.Context);
       int Order = S.Context.getFloatingTypeOrder(VectorEltTy, ScalarTy);
       if (!CstScalar && Order < 0)
         return true;
 
       // If the scalar cannot be safely casted to the vector element type,
       // reject it.
       if (CstScalar) {
         bool Truncated = false;
         Result.convert(S.Context.getFloatTypeSemantics(VectorEltTy),
                        llvm::APFloat::rmNearestTiesToEven, &Truncated);
         if (Truncated)
           return true;
       }
 
       ScalarCast = CK_FloatingCast;
     } else if (ScalarTy->isIntegralType(S.Context)) {
       if (canConvertIntTyToFloatTy(S, Scalar, VectorEltTy))
         return true;
 
       ScalarCast = CK_IntegralToFloating;
     } else
       return true;
   } else if (ScalarTy->isEnumeralType())
     return true;
 
   // Adjust scalar if desired.
   if (ScalarCast != CK_NoOp)
     *Scalar = S.ImpCastExprToType(Scalar->get(), VectorEltTy, ScalarCast);
   *Scalar = S.ImpCastExprToType(Scalar->get(), VectorTy, CK_VectorSplat);
   return false;
 }
 
 QualType Sema::CheckVectorOperands(ExprResult &LHS, ExprResult &RHS,
                                    SourceLocation Loc, bool IsCompAssign,
                                    bool AllowBothBool,
                                    bool AllowBoolConversions,
                                    bool AllowBoolOperation,
                                    bool ReportInvalid) {
   if (!IsCompAssign) {
     LHS = DefaultFunctionArrayLvalueConversion(LHS.get());
     if (LHS.isInvalid())
       return QualType();
   }
   RHS = DefaultFunctionArrayLvalueConversion(RHS.get());
   if (RHS.isInvalid())
     return QualType();
 
   // For conversion purposes, we ignore any qualifiers.
   // For example, "const float" and "float" are equivalent.
   QualType LHSType = LHS.get()->getType().getUnqualifiedType();
   QualType RHSType = RHS.get()->getType().getUnqualifiedType();
 
   const VectorType *LHSVecType = LHSType->getAs<VectorType>();
   const VectorType *RHSVecType = RHSType->getAs<VectorType>();
   assert(LHSVecType || RHSVecType);
 
   // AltiVec-style "vector bool op vector bool" combinations are allowed
   // for some operators but not others.
   if (!AllowBothBool &&
       LHSVecType && LHSVecType->getVectorKind() == VectorType::AltiVecBool &&
       RHSVecType && RHSVecType->getVectorKind() == VectorType::AltiVecBool)
     return ReportInvalid ? InvalidOperands(Loc, LHS, RHS) : QualType();
 
   // This operation may not be performed on boolean vectors.
   if (!AllowBoolOperation &&
       (LHSType->isExtVectorBoolType() || RHSType->isExtVectorBoolType()))
     return ReportInvalid ? InvalidOperands(Loc, LHS, RHS) : QualType();
 
   // If the vector types are identical, return.
   if (Context.hasSameType(LHSType, RHSType))
     return Context.getCommonSugaredType(LHSType, RHSType);
 
   // If we have compatible AltiVec and GCC vector types, use the AltiVec type.
   if (LHSVecType && RHSVecType &&
       Context.areCompatibleVectorTypes(LHSType, RHSType)) {
     if (isa<ExtVectorType>(LHSVecType)) {
       RHS = ImpCastExprToType(RHS.get(), LHSType, CK_BitCast);
       return LHSType;
     }
 
     if (!IsCompAssign)
       LHS = ImpCastExprToType(LHS.get(), RHSType, CK_BitCast);
     return RHSType;
   }
 
   // AllowBoolConversions says that bool and non-bool AltiVec vectors
   // can be mixed, with the result being the non-bool type.  The non-bool
   // operand must have integer element type.
   if (AllowBoolConversions && LHSVecType && RHSVecType &&
       LHSVecType->getNumElements() == RHSVecType->getNumElements() &&
       (Context.getTypeSize(LHSVecType->getElementType()) ==
        Context.getTypeSize(RHSVecType->getElementType()))) {
     if (LHSVecType->getVectorKind() == VectorType::AltiVecVector &&
         LHSVecType->getElementType()->isIntegerType() &&
         RHSVecType->getVectorKind() == VectorType::AltiVecBool) {
       RHS = ImpCastExprToType(RHS.get(), LHSType, CK_BitCast);
       return LHSType;
     }
     if (!IsCompAssign &&
         LHSVecType->getVectorKind() == VectorType::AltiVecBool &&
         RHSVecType->getVectorKind() == VectorType::AltiVecVector &&
         RHSVecType->getElementType()->isIntegerType()) {
       LHS = ImpCastExprToType(LHS.get(), RHSType, CK_BitCast);
       return RHSType;
     }
   }
 
   // Expressions containing fixed-length and sizeless SVE/RVV vectors are
   // invalid since the ambiguity can affect the ABI.
   auto IsSveRVVConversion = [](QualType FirstType, QualType SecondType,
                                unsigned &SVEorRVV) {
     const VectorType *VecType = SecondType->getAs<VectorType>();
     SVEorRVV = 0;
     if (FirstType->isSizelessBuiltinType() && VecType) {
       if (VecType->getVectorKind() == VectorType::SveFixedLengthDataVector ||
           VecType->getVectorKind() == VectorType::SveFixedLengthPredicateVector)
         return true;
       if (VecType->getVectorKind() == VectorType::RVVFixedLengthDataVector) {
         SVEorRVV = 1;
         return true;
       }
     }
 
     return false;
   };
 
   unsigned SVEorRVV;
   if (IsSveRVVConversion(LHSType, RHSType, SVEorRVV) ||
       IsSveRVVConversion(RHSType, LHSType, SVEorRVV)) {
     Diag(Loc, diag::err_typecheck_sve_rvv_ambiguous)
         << SVEorRVV << LHSType << RHSType;
     return QualType();
   }
 
   // Expressions containing GNU and SVE or RVV (fixed or sizeless) vectors are
   // invalid since the ambiguity can affect the ABI.
   auto IsSveRVVGnuConversion = [](QualType FirstType, QualType SecondType,
                                   unsigned &SVEorRVV) {
     const VectorType *FirstVecType = FirstType->getAs<VectorType>();
     const VectorType *SecondVecType = SecondType->getAs<VectorType>();
 
     SVEorRVV = 0;
     if (FirstVecType && SecondVecType) {
       if (FirstVecType->getVectorKind() == VectorType::GenericVector) {
         if (SecondVecType->getVectorKind() ==
                 VectorType::SveFixedLengthDataVector ||
             SecondVecType->getVectorKind() ==
                 VectorType::SveFixedLengthPredicateVector)
           return true;
         if (SecondVecType->getVectorKind() ==
             VectorType::RVVFixedLengthDataVector) {
           SVEorRVV = 1;
           return true;
         }
       }
       return false;
     }
 
     if (SecondVecType &&
         SecondVecType->getVectorKind() == VectorType::GenericVector) {
       if (FirstType->isSVESizelessBuiltinType())
         return true;
       if (FirstType->isRVVSizelessBuiltinType()) {
         SVEorRVV = 1;
         return true;
       }
     }
 
     return false;
   };
 
   if (IsSveRVVGnuConversion(LHSType, RHSType, SVEorRVV) ||
       IsSveRVVGnuConversion(RHSType, LHSType, SVEorRVV)) {
     Diag(Loc, diag::err_typecheck_sve_rvv_gnu_ambiguous)
         << SVEorRVV << LHSType << RHSType;
     return QualType();
   }
 
   // If there's a vector type and a scalar, try to convert the scalar to
   // the vector element type and splat.
   unsigned DiagID = diag::err_typecheck_vector_not_convertable;
   if (!RHSVecType) {
     if (isa<ExtVectorType>(LHSVecType)) {
       if (!tryVectorConvertAndSplat(*this, &RHS, RHSType,
                                     LHSVecType->getElementType(), LHSType,
                                     DiagID))
         return LHSType;
     } else {
       if (!tryGCCVectorConvertAndSplat(*this, &RHS, &LHS))
         return LHSType;
     }
   }
   if (!LHSVecType) {
     if (isa<ExtVectorType>(RHSVecType)) {
       if (!tryVectorConvertAndSplat(*this, (IsCompAssign ? nullptr : &LHS),
                                     LHSType, RHSVecType->getElementType(),
                                     RHSType, DiagID))
         return RHSType;
     } else {
       if (LHS.get()->isLValue() ||
           !tryGCCVectorConvertAndSplat(*this, &LHS, &RHS))
         return RHSType;
     }
   }
 
   // FIXME: The code below also handles conversion between vectors and
   // non-scalars, we should break this down into fine grained specific checks
   // and emit proper diagnostics.
   QualType VecType = LHSVecType ? LHSType : RHSType;
   const VectorType *VT = LHSVecType ? LHSVecType : RHSVecType;
   QualType OtherType = LHSVecType ? RHSType : LHSType;
   ExprResult *OtherExpr = LHSVecType ? &RHS : &LHS;
   if (isLaxVectorConversion(OtherType, VecType)) {
     if (Context.getTargetInfo().getTriple().isPPC() &&
         anyAltivecTypes(RHSType, LHSType) &&
         !Context.areCompatibleVectorTypes(RHSType, LHSType))
       Diag(Loc, diag::warn_deprecated_lax_vec_conv_all) << RHSType << LHSType;
     // If we're allowing lax vector conversions, only the total (data) size
     // needs to be the same. For non compound assignment, if one of the types is
     // scalar, the result is always the vector type.
     if (!IsCompAssign) {
       *OtherExpr = ImpCastExprToType(OtherExpr->get(), VecType, CK_BitCast);
       return VecType;
     // In a compound assignment, lhs += rhs, 'lhs' is a lvalue src, forbidding
     // any implicit cast. Here, the 'rhs' should be implicit casted to 'lhs'
     // type. Note that this is already done by non-compound assignments in
     // CheckAssignmentConstraints. If it's a scalar type, only bitcast for
     // <1 x T> -> T. The result is also a vector type.
     } else if (OtherType->isExtVectorType() || OtherType->isVectorType() ||
                (OtherType->isScalarType() && VT->getNumElements() == 1)) {
       ExprResult *RHSExpr = &RHS;
       *RHSExpr = ImpCastExprToType(RHSExpr->get(), LHSType, CK_BitCast);
       return VecType;
     }
   }
 
   // Okay, the expression is invalid.
 
   // If there's a non-vector, non-real operand, diagnose that.
   if ((!RHSVecType && !RHSType->isRealType()) ||
       (!LHSVecType && !LHSType->isRealType())) {
     Diag(Loc, diag::err_typecheck_vector_not_convertable_non_scalar)
       << LHSType << RHSType
       << LHS.get()->getSourceRange() << RHS.get()->getSourceRange();
     return QualType();
   }
 
   // OpenCL V1.1 6.2.6.p1:
   // If the operands are of more than one vector type, then an error shall
   // occur. Implicit conversions between vector types are not permitted, per
   // section 6.2.1.
   if (getLangOpts().OpenCL &&
       RHSVecType && isa<ExtVectorType>(RHSVecType) &&
       LHSVecType && isa<ExtVectorType>(LHSVecType)) {
     Diag(Loc, diag::err_opencl_implicit_vector_conversion) << LHSType
                                                            << RHSType;
     return QualType();
   }
 
 
   // If there is a vector type that is not a ExtVector and a scalar, we reach
   // this point if scalar could not be converted to the vector's element type
   // without truncation.
   if ((RHSVecType && !isa<ExtVectorType>(RHSVecType)) ||
       (LHSVecType && !isa<ExtVectorType>(LHSVecType))) {
     QualType Scalar = LHSVecType ? RHSType : LHSType;
     QualType Vector = LHSVecType ? LHSType : RHSType;
     unsigned ScalarOrVector = LHSVecType && RHSVecType ? 1 : 0;
     Diag(Loc,
          diag::err_typecheck_vector_not_convertable_implict_truncation)
         << ScalarOrVector << Scalar << Vector;
 
     return QualType();
   }
 
   // Otherwise, use the generic diagnostic.
   Diag(Loc, DiagID)
     << LHSType << RHSType
     << LHS.get()->getSourceRange() << RHS.get()->getSourceRange();
   return QualType();
 }
 
 QualType Sema::CheckSizelessVectorOperands(ExprResult &LHS, ExprResult &RHS,
                                            SourceLocation Loc,
                                            bool IsCompAssign,
                                            ArithConvKind OperationKind) {
   if (!IsCompAssign) {
     LHS = DefaultFunctionArrayLvalueConversion(LHS.get());
     if (LHS.isInvalid())
       return QualType();
   }
   RHS = DefaultFunctionArrayLvalueConversion(RHS.get());
   if (RHS.isInvalid())
     return QualType();
 
   QualType LHSType = LHS.get()->getType().getUnqualifiedType();
   QualType RHSType = RHS.get()->getType().getUnqualifiedType();
 
   const BuiltinType *LHSBuiltinTy = LHSType->getAs<BuiltinType>();
   const BuiltinType *RHSBuiltinTy = RHSType->getAs<BuiltinType>();
 
   unsigned DiagID = diag::err_typecheck_invalid_operands;
   if ((OperationKind == ACK_Arithmetic) &&
       ((LHSBuiltinTy && LHSBuiltinTy->isSVEBool()) ||
        (RHSBuiltinTy && RHSBuiltinTy->isSVEBool()))) {
     Diag(Loc, DiagID) << LHSType << RHSType << LHS.get()->getSourceRange()
                       << RHS.get()->getSourceRange();
     return QualType();
   }
 
   if (Context.hasSameType(LHSType, RHSType))
     return LHSType;
 
   if (LHSType->isVLSTBuiltinType() && !RHSType->isVLSTBuiltinType()) {
     if (!tryGCCVectorConvertAndSplat(*this, &RHS, &LHS))
       return LHSType;
   }
   if (RHSType->isVLSTBuiltinType() && !LHSType->isVLSTBuiltinType()) {
     if (LHS.get()->isLValue() ||
         !tryGCCVectorConvertAndSplat(*this, &LHS, &RHS))
       return RHSType;
   }
 
   if ((!LHSType->isVLSTBuiltinType() && !LHSType->isRealType()) ||
       (!RHSType->isVLSTBuiltinType() && !RHSType->isRealType())) {
     Diag(Loc, diag::err_typecheck_vector_not_convertable_non_scalar)
         << LHSType << RHSType << LHS.get()->getSourceRange()
         << RHS.get()->getSourceRange();
     return QualType();
   }
 
   if (LHSType->isVLSTBuiltinType() && RHSType->isVLSTBuiltinType() &&
       Context.getBuiltinVectorTypeInfo(LHSBuiltinTy).EC !=
           Context.getBuiltinVectorTypeInfo(RHSBuiltinTy).EC) {
     Diag(Loc, diag::err_typecheck_vector_lengths_not_equal)
         << LHSType << RHSType << LHS.get()->getSourceRange()
         << RHS.get()->getSourceRange();
     return QualType();
   }
 
   if (LHSType->isVLSTBuiltinType() || RHSType->isVLSTBuiltinType()) {
     QualType Scalar = LHSType->isVLSTBuiltinType() ? RHSType : LHSType;
     QualType Vector = LHSType->isVLSTBuiltinType() ? LHSType : RHSType;
     bool ScalarOrVector =
         LHSType->isVLSTBuiltinType() && RHSType->isVLSTBuiltinType();
 
     Diag(Loc, diag::err_typecheck_vector_not_convertable_implict_truncation)
         << ScalarOrVector << Scalar << Vector;
 
     return QualType();
   }
 
   Diag(Loc, DiagID) << LHSType << RHSType << LHS.get()->getSourceRange()
                     << RHS.get()->getSourceRange();
   return QualType();
 }
 
 // checkArithmeticNull - Detect when a NULL constant is used improperly in an
 // expression.  These are mainly cases where the null pointer is used as an
 // integer instead of a pointer.
 static void checkArithmeticNull(Sema &S, ExprResult &LHS, ExprResult &RHS,
                                 SourceLocation Loc, bool IsCompare) {
   // The canonical way to check for a GNU null is with isNullPointerConstant,
   // but we use a bit of a hack here for speed; this is a relatively
   // hot path, and isNullPointerConstant is slow.
   bool LHSNull = isa<GNUNullExpr>(LHS.get()->IgnoreParenImpCasts());
   bool RHSNull = isa<GNUNullExpr>(RHS.get()->IgnoreParenImpCasts());
 
   QualType NonNullType = LHSNull ? RHS.get()->getType() : LHS.get()->getType();
 
   // Avoid analyzing cases where the result will either be invalid (and
   // diagnosed as such) or entirely valid and not something to warn about.
   if ((!LHSNull && !RHSNull) || NonNullType->isBlockPointerType() ||
       NonNullType->isMemberPointerType() || NonNullType->isFunctionType())
     return;
 
   // Comparison operations would not make sense with a null pointer no matter
   // what the other expression is.
   if (!IsCompare) {
     S.Diag(Loc, diag::warn_null_in_arithmetic_operation)
         << (LHSNull ? LHS.get()->getSourceRange() : SourceRange())
         << (RHSNull ? RHS.get()->getSourceRange() : SourceRange());
     return;
   }
 
   // The rest of the operations only make sense with a null pointer
   // if the other expression is a pointer.
   if (LHSNull == RHSNull || NonNullType->isAnyPointerType() ||
       NonNullType->canDecayToPointerType())
     return;
 
   S.Diag(Loc, diag::warn_null_in_comparison_operation)
       << LHSNull /* LHS is NULL */ << NonNullType
       << LHS.get()->getSourceRange() << RHS.get()->getSourceRange();
 }
 
 static void DiagnoseDivisionSizeofPointerOrArray(Sema &S, Expr *LHS, Expr *RHS,
                                           SourceLocation Loc) {
   const auto *LUE = dyn_cast<UnaryExprOrTypeTraitExpr>(LHS);
   const auto *RUE = dyn_cast<UnaryExprOrTypeTraitExpr>(RHS);
   if (!LUE || !RUE)
     return;
   if (LUE->getKind() != UETT_SizeOf || LUE->isArgumentType() ||
       RUE->getKind() != UETT_SizeOf)
     return;
 
   const Expr *LHSArg = LUE->getArgumentExpr()->IgnoreParens();
   QualType LHSTy = LHSArg->getType();
   QualType RHSTy;
 
   if (RUE->isArgumentType())
     RHSTy = RUE->getArgumentType().getNonReferenceType();
   else
     RHSTy = RUE->getArgumentExpr()->IgnoreParens()->getType();
 
   if (LHSTy->isPointerType() && !RHSTy->isPointerType()) {
     if (!S.Context.hasSameUnqualifiedType(LHSTy->getPointeeType(), RHSTy))
       return;
 
     S.Diag(Loc, diag::warn_division_sizeof_ptr) << LHS << LHS->getSourceRange();
     if (const auto *DRE = dyn_cast<DeclRefExpr>(LHSArg)) {
       if (const ValueDecl *LHSArgDecl = DRE->getDecl())
         S.Diag(LHSArgDecl->getLocation(), diag::note_pointer_declared_here)
             << LHSArgDecl;
     }
   } else if (const auto *ArrayTy = S.Context.getAsArrayType(LHSTy)) {
     QualType ArrayElemTy = ArrayTy->getElementType();
     if (ArrayElemTy != S.Context.getBaseElementType(ArrayTy) ||
         ArrayElemTy->isDependentType() || RHSTy->isDependentType() ||
         RHSTy->isReferenceType() || ArrayElemTy->isCharType() ||
         S.Context.getTypeSize(ArrayElemTy) == S.Context.getTypeSize(RHSTy))
       return;
     S.Diag(Loc, diag::warn_division_sizeof_array)
         << LHSArg->getSourceRange() << ArrayElemTy << RHSTy;
     if (const auto *DRE = dyn_cast<DeclRefExpr>(LHSArg)) {
       if (const ValueDecl *LHSArgDecl = DRE->getDecl())
         S.Diag(LHSArgDecl->getLocation(), diag::note_array_declared_here)
             << LHSArgDecl;
     }
 
     S.Diag(Loc, diag::note_precedence_silence) << RHS;
   }
 }
 
 static void DiagnoseBadDivideOrRemainderValues(Sema& S, ExprResult &LHS,
                                                ExprResult &RHS,
                                                SourceLocation Loc, bool IsDiv) {
   // Check for division/remainder by zero.
   Expr::EvalResult RHSValue;
   if (!RHS.get()->isValueDependent() &&
       RHS.get()->EvaluateAsInt(RHSValue, S.Context) &&
       RHSValue.Val.getInt() == 0)
     S.DiagRuntimeBehavior(Loc, RHS.get(),
                           S.PDiag(diag::warn_remainder_division_by_zero)
                             << IsDiv << RHS.get()->getSourceRange());
 }
 
 QualType Sema::CheckMultiplyDivideOperands(ExprResult &LHS, ExprResult &RHS,
                                            SourceLocation Loc,
                                            bool IsCompAssign, bool IsDiv) {
   checkArithmeticNull(*this, LHS, RHS, Loc, /*IsCompare=*/false);
 
   QualType LHSTy = LHS.get()->getType();
   QualType RHSTy = RHS.get()->getType();
   if (LHSTy->isVectorType() || RHSTy->isVectorType())
     return CheckVectorOperands(LHS, RHS, Loc, IsCompAssign,
                                /*AllowBothBool*/ getLangOpts().AltiVec,
                                /*AllowBoolConversions*/ false,
                                /*AllowBooleanOperation*/ false,
                                /*ReportInvalid*/ true);
   if (LHSTy->isVLSTBuiltinType() || RHSTy->isVLSTBuiltinType())
     return CheckSizelessVectorOperands(LHS, RHS, Loc, IsCompAssign,
                                        ACK_Arithmetic);
   if (!IsDiv &&
       (LHSTy->isConstantMatrixType() || RHSTy->isConstantMatrixType()))
     return CheckMatrixMultiplyOperands(LHS, RHS, Loc, IsCompAssign);
   // For division, only matrix-by-scalar is supported. Other combinations with
   // matrix types are invalid.
   if (IsDiv && LHSTy->isConstantMatrixType() && RHSTy->isArithmeticType())
     return CheckMatrixElementwiseOperands(LHS, RHS, Loc, IsCompAssign);
 
   QualType compType = UsualArithmeticConversions(
       LHS, RHS, Loc, IsCompAssign ? ACK_CompAssign : ACK_Arithmetic);
   if (LHS.isInvalid() || RHS.isInvalid())
     return QualType();
 
 
   if (compType.isNull() || !compType->isArithmeticType())
     return InvalidOperands(Loc, LHS, RHS);
   if (IsDiv) {
     DiagnoseBadDivideOrRemainderValues(*this, LHS, RHS, Loc, IsDiv);
     DiagnoseDivisionSizeofPointerOrArray(*this, LHS.get(), RHS.get(), Loc);
   }
   return compType;
 }
 
 QualType Sema::CheckRemainderOperands(
   ExprResult &LHS, ExprResult &RHS, SourceLocation Loc, bool IsCompAssign) {
   checkArithmeticNull(*this, LHS, RHS, Loc, /*IsCompare=*/false);
 
   if (LHS.get()->getType()->isVectorType() ||
       RHS.get()->getType()->isVectorType()) {
     if (LHS.get()->getType()->hasIntegerRepresentation() &&
         RHS.get()->getType()->hasIntegerRepresentation())
       return CheckVectorOperands(LHS, RHS, Loc, IsCompAssign,
                                  /*AllowBothBool*/ getLangOpts().AltiVec,
                                  /*AllowBoolConversions*/ false,
                                  /*AllowBooleanOperation*/ false,
                                  /*ReportInvalid*/ true);
     return InvalidOperands(Loc, LHS, RHS);
   }
 
   if (LHS.get()->getType()->isVLSTBuiltinType() ||
       RHS.get()->getType()->isVLSTBuiltinType()) {
     if (LHS.get()->getType()->hasIntegerRepresentation() &&
         RHS.get()->getType()->hasIntegerRepresentation())
       return CheckSizelessVectorOperands(LHS, RHS, Loc, IsCompAssign,
                                          ACK_Arithmetic);
 
     return InvalidOperands(Loc, LHS, RHS);
   }
 
   QualType compType = UsualArithmeticConversions(
       LHS, RHS, Loc, IsCompAssign ? ACK_CompAssign : ACK_Arithmetic);
   if (LHS.isInvalid() || RHS.isInvalid())
     return QualType();
 
   if (compType.isNull() || !compType->isIntegerType())
     return InvalidOperands(Loc, LHS, RHS);
   DiagnoseBadDivideOrRemainderValues(*this, LHS, RHS, Loc, false /* IsDiv */);
   return compType;
 }
 
 /// Diagnose invalid arithmetic on two void pointers.
 static void diagnoseArithmeticOnTwoVoidPointers(Sema &S, SourceLocation Loc,
                                                 Expr *LHSExpr, Expr *RHSExpr) {
   S.Diag(Loc, S.getLangOpts().CPlusPlus
                 ? diag::err_typecheck_pointer_arith_void_type
                 : diag::ext_gnu_void_ptr)
     << 1 /* two pointers */ << LHSExpr->getSourceRange()
                             << RHSExpr->getSourceRange();
 }
 
 /// Diagnose invalid arithmetic on a void pointer.
 static void diagnoseArithmeticOnVoidPointer(Sema &S, SourceLocation Loc,
                                             Expr *Pointer) {
   S.Diag(Loc, S.getLangOpts().CPlusPlus
                 ? diag::err_typecheck_pointer_arith_void_type
                 : diag::ext_gnu_void_ptr)
     << 0 /* one pointer */ << Pointer->getSourceRange();
 }
 
 /// Diagnose invalid arithmetic on a null pointer.
 ///
 /// If \p IsGNUIdiom is true, the operation is using the 'p = (i8*)nullptr + n'
 /// idiom, which we recognize as a GNU extension.
 ///
 static void diagnoseArithmeticOnNullPointer(Sema &S, SourceLocation Loc,
                                             Expr *Pointer, bool IsGNUIdiom) {
   if (IsGNUIdiom)
     S.Diag(Loc, diag::warn_gnu_null_ptr_arith)
       << Pointer->getSourceRange();
   else
     S.Diag(Loc, diag::warn_pointer_arith_null_ptr)
       << S.getLangOpts().CPlusPlus << Pointer->getSourceRange();
 }
 
 /// Diagnose invalid subraction on a null pointer.
 ///
 static void diagnoseSubtractionOnNullPointer(Sema &S, SourceLocation Loc,
                                              Expr *Pointer, bool BothNull) {
   // Null - null is valid in C++ [expr.add]p7
   if (BothNull && S.getLangOpts().CPlusPlus)
     return;
 
   // Is this s a macro from a system header?
   if (S.Diags.getSuppressSystemWarnings() && S.SourceMgr.isInSystemMacro(Loc))
     return;
 
   S.DiagRuntimeBehavior(Loc, Pointer,
                         S.PDiag(diag::warn_pointer_sub_null_ptr)
                             << S.getLangOpts().CPlusPlus
                             << Pointer->getSourceRange());
 }
 
 /// Diagnose invalid arithmetic on two function pointers.
 static void diagnoseArithmeticOnTwoFunctionPointers(Sema &S, SourceLocation Loc,
                                                     Expr *LHS, Expr *RHS) {
   assert(LHS->getType()->isAnyPointerType());
   assert(RHS->getType()->isAnyPointerType());
   S.Diag(Loc, S.getLangOpts().CPlusPlus
                 ? diag::err_typecheck_pointer_arith_function_type
                 : diag::ext_gnu_ptr_func_arith)
     << 1 /* two pointers */ << LHS->getType()->getPointeeType()
     // We only show the second type if it differs from the first.
     << (unsigned)!S.Context.hasSameUnqualifiedType(LHS->getType(),
                                                    RHS->getType())
     << RHS->getType()->getPointeeType()
     << LHS->getSourceRange() << RHS->getSourceRange();
 }
 
 /// Diagnose invalid arithmetic on a function pointer.
 static void diagnoseArithmeticOnFunctionPointer(Sema &S, SourceLocation Loc,
                                                 Expr *Pointer) {
   assert(Pointer->getType()->isAnyPointerType());
   S.Diag(Loc, S.getLangOpts().CPlusPlus
                 ? diag::err_typecheck_pointer_arith_function_type
                 : diag::ext_gnu_ptr_func_arith)
     << 0 /* one pointer */ << Pointer->getType()->getPointeeType()
     << 0 /* one pointer, so only one type */
     << Pointer->getSourceRange();
 }
 
 /// Emit error if Operand is incomplete pointer type
 ///
 /// \returns True if pointer has incomplete type
 static bool checkArithmeticIncompletePointerType(Sema &S, SourceLocation Loc,
                                                  Expr *Operand) {
   QualType ResType = Operand->getType();
   if (const AtomicType *ResAtomicType = ResType->getAs<AtomicType>())
     ResType = ResAtomicType->getValueType();
 
   assert(ResType->isAnyPointerType() && !ResType->isDependentType());
   QualType PointeeTy = ResType->getPointeeType();
   return S.RequireCompleteSizedType(
       Loc, PointeeTy,
       diag::err_typecheck_arithmetic_incomplete_or_sizeless_type,
       Operand->getSourceRange());
 }
 
 /// Check the validity of an arithmetic pointer operand.
 ///
 /// If the operand has pointer type, this code will check for pointer types
 /// which are invalid in arithmetic operations. These will be diagnosed
 /// appropriately, including whether or not the use is supported as an
 /// extension.
 ///
 /// \returns True when the operand is valid to use (even if as an extension).
 static bool checkArithmeticOpPointerOperand(Sema &S, SourceLocation Loc,
                                             Expr *Operand) {
   QualType ResType = Operand->getType();
   if (const AtomicType *ResAtomicType = ResType->getAs<AtomicType>())
     ResType = ResAtomicType->getValueType();
 
   if (!ResType->isAnyPointerType()) return true;
 
   QualType PointeeTy = ResType->getPointeeType();
   if (PointeeTy->isVoidType()) {
     diagnoseArithmeticOnVoidPointer(S, Loc, Operand);
     return !S.getLangOpts().CPlusPlus;
   }
   if (PointeeTy->isFunctionType()) {
     diagnoseArithmeticOnFunctionPointer(S, Loc, Operand);
     return !S.getLangOpts().CPlusPlus;
   }
 
   if (checkArithmeticIncompletePointerType(S, Loc, Operand)) return false;
 
   return true;
 }
 
 /// Check the validity of a binary arithmetic operation w.r.t. pointer
 /// operands.
 ///
 /// This routine will diagnose any invalid arithmetic on pointer operands much
 /// like \see checkArithmeticOpPointerOperand. However, it has special logic
 /// for emitting a single diagnostic even for operations where both LHS and RHS
 /// are (potentially problematic) pointers.
 ///
 /// \returns True when the operand is valid to use (even if as an extension).
 static bool checkArithmeticBinOpPointerOperands(Sema &S, SourceLocation Loc,
                                                 Expr *LHSExpr, Expr *RHSExpr) {
   bool isLHSPointer = LHSExpr->getType()->isAnyPointerType();
   bool isRHSPointer = RHSExpr->getType()->isAnyPointerType();
   if (!isLHSPointer && !isRHSPointer) return true;
 
   QualType LHSPointeeTy, RHSPointeeTy;
   if (isLHSPointer) LHSPointeeTy = LHSExpr->getType()->getPointeeType();
   if (isRHSPointer) RHSPointeeTy = RHSExpr->getType()->getPointeeType();
 
   // if both are pointers check if operation is valid wrt address spaces
   if (isLHSPointer && isRHSPointer) {
     if (!LHSPointeeTy.isAddressSpaceOverlapping(RHSPointeeTy)) {
       S.Diag(Loc,
              diag::err_typecheck_op_on_nonoverlapping_address_space_pointers)
           << LHSExpr->getType() << RHSExpr->getType() << 1 /*arithmetic op*/
           << LHSExpr->getSourceRange() << RHSExpr->getSourceRange();
       return false;
     }
   }
 
   // Check for arithmetic on pointers to incomplete types.
   bool isLHSVoidPtr = isLHSPointer && LHSPointeeTy->isVoidType();
   bool isRHSVoidPtr = isRHSPointer && RHSPointeeTy->isVoidType();
   if (isLHSVoidPtr || isRHSVoidPtr) {
     if (!isRHSVoidPtr) diagnoseArithmeticOnVoidPointer(S, Loc, LHSExpr);
     else if (!isLHSVoidPtr) diagnoseArithmeticOnVoidPointer(S, Loc, RHSExpr);
     else diagnoseArithmeticOnTwoVoidPointers(S, Loc, LHSExpr, RHSExpr);
 
     return !S.getLangOpts().CPlusPlus;
   }
 
   bool isLHSFuncPtr = isLHSPointer && LHSPointeeTy->isFunctionType();
   bool isRHSFuncPtr = isRHSPointer && RHSPointeeTy->isFunctionType();
   if (isLHSFuncPtr || isRHSFuncPtr) {
     if (!isRHSFuncPtr) diagnoseArithmeticOnFunctionPointer(S, Loc, LHSExpr);
     else if (!isLHSFuncPtr) diagnoseArithmeticOnFunctionPointer(S, Loc,
                                                                 RHSExpr);
     else diagnoseArithmeticOnTwoFunctionPointers(S, Loc, LHSExpr, RHSExpr);
 
     return !S.getLangOpts().CPlusPlus;
   }
 
   if (isLHSPointer && checkArithmeticIncompletePointerType(S, Loc, LHSExpr))
     return false;
   if (isRHSPointer && checkArithmeticIncompletePointerType(S, Loc, RHSExpr))
     return false;
 
   return true;
 }
 
 /// diagnoseStringPlusInt - Emit a warning when adding an integer to a string
 /// literal.
 static void diagnoseStringPlusInt(Sema &Self, SourceLocation OpLoc,
                                   Expr *LHSExpr, Expr *RHSExpr) {
   StringLiteral* StrExpr = dyn_cast<StringLiteral>(LHSExpr->IgnoreImpCasts());
   Expr* IndexExpr = RHSExpr;
   if (!StrExpr) {
     StrExpr = dyn_cast<StringLiteral>(RHSExpr->IgnoreImpCasts());
     IndexExpr = LHSExpr;
   }
 
   bool IsStringPlusInt = StrExpr &&
       IndexExpr->getType()->isIntegralOrUnscopedEnumerationType();
   if (!IsStringPlusInt || IndexExpr->isValueDependent())
     return;
 
   SourceRange DiagRange(LHSExpr->getBeginLoc(), RHSExpr->getEndLoc());
   Self.Diag(OpLoc, diag::warn_string_plus_int)
       << DiagRange << IndexExpr->IgnoreImpCasts()->getType();
 
   // Only print a fixit for "str" + int, not for int + "str".
   if (IndexExpr == RHSExpr) {
     SourceLocation EndLoc = Self.getLocForEndOfToken(RHSExpr->getEndLoc());
     Self.Diag(OpLoc, diag::note_string_plus_scalar_silence)
         << FixItHint::CreateInsertion(LHSExpr->getBeginLoc(), "&")
         << FixItHint::CreateReplacement(SourceRange(OpLoc), "[")
         << FixItHint::CreateInsertion(EndLoc, "]");
   } else
     Self.Diag(OpLoc, diag::note_string_plus_scalar_silence);
 }
 
 /// Emit a warning when adding a char literal to a string.
 static void diagnoseStringPlusChar(Sema &Self, SourceLocation OpLoc,
                                    Expr *LHSExpr, Expr *RHSExpr) {
   const Expr *StringRefExpr = LHSExpr;
   const CharacterLiteral *CharExpr =
       dyn_cast<CharacterLiteral>(RHSExpr->IgnoreImpCasts());
 
   if (!CharExpr) {
     CharExpr = dyn_cast<CharacterLiteral>(LHSExpr->IgnoreImpCasts());
     StringRefExpr = RHSExpr;
   }
 
   if (!CharExpr || !StringRefExpr)
     return;
 
   const QualType StringType = StringRefExpr->getType();
 
   // Return if not a PointerType.
   if (!StringType->isAnyPointerType())
     return;
 
   // Return if not a CharacterType.
   if (!StringType->getPointeeType()->isAnyCharacterType())
     return;
 
   ASTContext &Ctx = Self.getASTContext();
   SourceRange DiagRange(LHSExpr->getBeginLoc(), RHSExpr->getEndLoc());
 
   const QualType CharType = CharExpr->getType();
   if (!CharType->isAnyCharacterType() &&
       CharType->isIntegerType() &&
       llvm::isUIntN(Ctx.getCharWidth(), CharExpr->getValue())) {
     Self.Diag(OpLoc, diag::warn_string_plus_char)
         << DiagRange << Ctx.CharTy;
   } else {
     Self.Diag(OpLoc, diag::warn_string_plus_char)
         << DiagRange << CharExpr->getType();
   }
 
   // Only print a fixit for str + char, not for char + str.
   if (isa<CharacterLiteral>(RHSExpr->IgnoreImpCasts())) {
     SourceLocation EndLoc = Self.getLocForEndOfToken(RHSExpr->getEndLoc());
     Self.Diag(OpLoc, diag::note_string_plus_scalar_silence)
         << FixItHint::CreateInsertion(LHSExpr->getBeginLoc(), "&")
         << FixItHint::CreateReplacement(SourceRange(OpLoc), "[")
         << FixItHint::CreateInsertion(EndLoc, "]");
   } else {
     Self.Diag(OpLoc, diag::note_string_plus_scalar_silence);
   }
 }
 
 /// Emit error when two pointers are incompatible.
 static void diagnosePointerIncompatibility(Sema &S, SourceLocation Loc,
                                            Expr *LHSExpr, Expr *RHSExpr) {
   assert(LHSExpr->getType()->isAnyPointerType());
   assert(RHSExpr->getType()->isAnyPointerType());
   S.Diag(Loc, diag::err_typecheck_sub_ptr_compatible)
     << LHSExpr->getType() << RHSExpr->getType() << LHSExpr->getSourceRange()
     << RHSExpr->getSourceRange();
 }
 
 // C99 6.5.6
 QualType Sema::CheckAdditionOperands(ExprResult &LHS, ExprResult &RHS,
                                      SourceLocation Loc, BinaryOperatorKind Opc,
                                      QualType* CompLHSTy) {
   checkArithmeticNull(*this, LHS, RHS, Loc, /*IsCompare=*/false);
 
   if (LHS.get()->getType()->isVectorType() ||
       RHS.get()->getType()->isVectorType()) {
     QualType compType =
         CheckVectorOperands(LHS, RHS, Loc, CompLHSTy,
                             /*AllowBothBool*/ getLangOpts().AltiVec,
                             /*AllowBoolConversions*/ getLangOpts().ZVector,
                             /*AllowBooleanOperation*/ false,
                             /*ReportInvalid*/ true);
     if (CompLHSTy) *CompLHSTy = compType;
     return compType;
   }
 
   if (LHS.get()->getType()->isVLSTBuiltinType() ||
       RHS.get()->getType()->isVLSTBuiltinType()) {
     QualType compType =
         CheckSizelessVectorOperands(LHS, RHS, Loc, CompLHSTy, ACK_Arithmetic);
     if (CompLHSTy)
       *CompLHSTy = compType;
     return compType;
   }
 
   if (LHS.get()->getType()->isConstantMatrixType() ||
       RHS.get()->getType()->isConstantMatrixType()) {
     QualType compType =
         CheckMatrixElementwiseOperands(LHS, RHS, Loc, CompLHSTy);
     if (CompLHSTy)
       *CompLHSTy = compType;
     return compType;
   }
 
   QualType compType = UsualArithmeticConversions(
       LHS, RHS, Loc, CompLHSTy ? ACK_CompAssign : ACK_Arithmetic);
   if (LHS.isInvalid() || RHS.isInvalid())
     return QualType();
 
   // Diagnose "string literal" '+' int and string '+' "char literal".
   if (Opc == BO_Add) {
     diagnoseStringPlusInt(*this, Loc, LHS.get(), RHS.get());
     diagnoseStringPlusChar(*this, Loc, LHS.get(), RHS.get());
   }
 
   // handle the common case first (both operands are arithmetic).
   if (!compType.isNull() && compType->isArithmeticType()) {
     if (CompLHSTy) *CompLHSTy = compType;
     return compType;
   }
 
   // Type-checking.  Ultimately the pointer's going to be in PExp;
   // note that we bias towards the LHS being the pointer.
   Expr *PExp = LHS.get(), *IExp = RHS.get();
 
   bool isObjCPointer;
   if (PExp->getType()->isPointerType()) {
     isObjCPointer = false;
   } else if (PExp->getType()->isObjCObjectPointerType()) {
     isObjCPointer = true;
   } else {
     std::swap(PExp, IExp);
     if (PExp->getType()->isPointerType()) {
       isObjCPointer = false;
     } else if (PExp->getType()->isObjCObjectPointerType()) {
       isObjCPointer = true;
     } else {
       return InvalidOperands(Loc, LHS, RHS);
     }
   }
   assert(PExp->getType()->isAnyPointerType());
 
   if (!IExp->getType()->isIntegerType())
     return InvalidOperands(Loc, LHS, RHS);
 
   // Adding to a null pointer results in undefined behavior.
   if (PExp->IgnoreParenCasts()->isNullPointerConstant(
           Context, Expr::NPC_ValueDependentIsNotNull)) {
     // In C++ adding zero to a null pointer is defined.
     Expr::EvalResult KnownVal;
     if (!getLangOpts().CPlusPlus ||
         (!IExp->isValueDependent() &&
          (!IExp->EvaluateAsInt(KnownVal, Context) ||
           KnownVal.Val.getInt() != 0))) {
       // Check the conditions to see if this is the 'p = nullptr + n' idiom.
       bool IsGNUIdiom = BinaryOperator::isNullPointerArithmeticExtension(
           Context, BO_Add, PExp, IExp);
       diagnoseArithmeticOnNullPointer(*this, Loc, PExp, IsGNUIdiom);
     }
   }
 
   if (!checkArithmeticOpPointerOperand(*this, Loc, PExp))
     return QualType();
 
   if (isObjCPointer && checkArithmeticOnObjCPointer(*this, Loc, PExp))
     return QualType();
 
   // Check array bounds for pointer arithemtic
   CheckArrayAccess(PExp, IExp);
 
   if (CompLHSTy) {
     QualType LHSTy = Context.isPromotableBitField(LHS.get());
     if (LHSTy.isNull()) {
       LHSTy = LHS.get()->getType();
       if (Context.isPromotableIntegerType(LHSTy))
         LHSTy = Context.getPromotedIntegerType(LHSTy);
     }
     *CompLHSTy = LHSTy;
   }
 
   return PExp->getType();
 }
 
 // C99 6.5.6
 QualType Sema::CheckSubtractionOperands(ExprResult &LHS, ExprResult &RHS,
                                         SourceLocation Loc,
                                         QualType* CompLHSTy) {
   checkArithmeticNull(*this, LHS, RHS, Loc, /*IsCompare=*/false);
 
   if (LHS.get()->getType()->isVectorType() ||
       RHS.get()->getType()->isVectorType()) {
     QualType compType =
         CheckVectorOperands(LHS, RHS, Loc, CompLHSTy,
                             /*AllowBothBool*/ getLangOpts().AltiVec,
                             /*AllowBoolConversions*/ getLangOpts().ZVector,
                             /*AllowBooleanOperation*/ false,
                             /*ReportInvalid*/ true);
     if (CompLHSTy) *CompLHSTy = compType;
     return compType;
   }
 
   if (LHS.get()->getType()->isVLSTBuiltinType() ||
       RHS.get()->getType()->isVLSTBuiltinType()) {
     QualType compType =
         CheckSizelessVectorOperands(LHS, RHS, Loc, CompLHSTy, ACK_Arithmetic);
     if (CompLHSTy)
       *CompLHSTy = compType;
     return compType;
   }
 
   if (LHS.get()->getType()->isConstantMatrixType() ||
       RHS.get()->getType()->isConstantMatrixType()) {
     QualType compType =
         CheckMatrixElementwiseOperands(LHS, RHS, Loc, CompLHSTy);
     if (CompLHSTy)
       *CompLHSTy = compType;
     return compType;
   }
 
   QualType compType = UsualArithmeticConversions(
       LHS, RHS, Loc, CompLHSTy ? ACK_CompAssign : ACK_Arithmetic);
   if (LHS.isInvalid() || RHS.isInvalid())
     return QualType();
 
   // Enforce type constraints: C99 6.5.6p3.
 
   // Handle the common case first (both operands are arithmetic).
   if (!compType.isNull() && compType->isArithmeticType()) {
     if (CompLHSTy) *CompLHSTy = compType;
     return compType;
   }
 
   // Either ptr - int   or   ptr - ptr.
   if (LHS.get()->getType()->isAnyPointerType()) {
     QualType lpointee = LHS.get()->getType()->getPointeeType();
 
     // Diagnose bad cases where we step over interface counts.
     if (LHS.get()->getType()->isObjCObjectPointerType() &&
         checkArithmeticOnObjCPointer(*this, Loc, LHS.get()))
       return QualType();
 
     // The result type of a pointer-int computation is the pointer type.
     if (RHS.get()->getType()->isIntegerType()) {
       // Subtracting from a null pointer should produce a warning.
       // The last argument to the diagnose call says this doesn't match the
       // GNU int-to-pointer idiom.
       if (LHS.get()->IgnoreParenCasts()->isNullPointerConstant(Context,
                                            Expr::NPC_ValueDependentIsNotNull)) {
         // In C++ adding zero to a null pointer is defined.
         Expr::EvalResult KnownVal;
         if (!getLangOpts().CPlusPlus ||
             (!RHS.get()->isValueDependent() &&
              (!RHS.get()->EvaluateAsInt(KnownVal, Context) ||
               KnownVal.Val.getInt() != 0))) {
           diagnoseArithmeticOnNullPointer(*this, Loc, LHS.get(), false);
         }
       }
 
       if (!checkArithmeticOpPointerOperand(*this, Loc, LHS.get()))
         return QualType();
 
       // Check array bounds for pointer arithemtic
       CheckArrayAccess(LHS.get(), RHS.get(), /*ArraySubscriptExpr*/nullptr,
                        /*AllowOnePastEnd*/true, /*IndexNegated*/true);
 
       if (CompLHSTy) *CompLHSTy = LHS.get()->getType();
       return LHS.get()->getType();
     }
 
     // Handle pointer-pointer subtractions.
     if (const PointerType *RHSPTy
           = RHS.get()->getType()->getAs<PointerType>()) {
       QualType rpointee = RHSPTy->getPointeeType();
 
       if (getLangOpts().CPlusPlus) {
         // Pointee types must be the same: C++ [expr.add]
         if (!Context.hasSameUnqualifiedType(lpointee, rpointee)) {
           diagnosePointerIncompatibility(*this, Loc, LHS.get(), RHS.get());
         }
       } else {
         // Pointee types must be compatible C99 6.5.6p3
         if (!Context.typesAreCompatible(
                 Context.getCanonicalType(lpointee).getUnqualifiedType(),
                 Context.getCanonicalType(rpointee).getUnqualifiedType())) {
           diagnosePointerIncompatibility(*this, Loc, LHS.get(), RHS.get());
           return QualType();
         }
       }
 
       if (!checkArithmeticBinOpPointerOperands(*this, Loc,
                                                LHS.get(), RHS.get()))
         return QualType();
 
       bool LHSIsNullPtr = LHS.get()->IgnoreParenCasts()->isNullPointerConstant(
           Context, Expr::NPC_ValueDependentIsNotNull);
       bool RHSIsNullPtr = RHS.get()->IgnoreParenCasts()->isNullPointerConstant(
           Context, Expr::NPC_ValueDependentIsNotNull);
 
       // Subtracting nullptr or from nullptr is suspect
       if (LHSIsNullPtr)
         diagnoseSubtractionOnNullPointer(*this, Loc, LHS.get(), RHSIsNullPtr);
       if (RHSIsNullPtr)
         diagnoseSubtractionOnNullPointer(*this, Loc, RHS.get(), LHSIsNullPtr);
 
       // The pointee type may have zero size.  As an extension, a structure or
       // union may have zero size or an array may have zero length.  In this
       // case subtraction does not make sense.
       if (!rpointee->isVoidType() && !rpointee->isFunctionType()) {
         CharUnits ElementSize = Context.getTypeSizeInChars(rpointee);
         if (ElementSize.isZero()) {
           Diag(Loc,diag::warn_sub_ptr_zero_size_types)
             << rpointee.getUnqualifiedType()
             << LHS.get()->getSourceRange() << RHS.get()->getSourceRange();
         }
       }
 
       if (CompLHSTy) *CompLHSTy = LHS.get()->getType();
       return Context.getPointerDiffType();
     }
   }
 
   return InvalidOperands(Loc, LHS, RHS);
 }
 
 static bool isScopedEnumerationType(QualType T) {
   if (const EnumType *ET = T->getAs<EnumType>())
     return ET->getDecl()->isScoped();
   return false;
 }
 
 static void DiagnoseBadShiftValues(Sema& S, ExprResult &LHS, ExprResult &RHS,
                                    SourceLocation Loc, BinaryOperatorKind Opc,
                                    QualType LHSType) {
   // OpenCL 6.3j: shift values are effectively % word size of LHS (more defined),
   // so skip remaining warnings as we don't want to modify values within Sema.
   if (S.getLangOpts().OpenCL)
     return;
 
   // Check right/shifter operand
   Expr::EvalResult RHSResult;
   if (RHS.get()->isValueDependent() ||
       !RHS.get()->EvaluateAsInt(RHSResult, S.Context))
     return;
   llvm::APSInt Right = RHSResult.Val.getInt();
 
   if (Right.isNegative()) {
     S.DiagRuntimeBehavior(Loc, RHS.get(),
                           S.PDiag(diag::warn_shift_negative)
                             << RHS.get()->getSourceRange());
     return;
   }
 
   QualType LHSExprType = LHS.get()->getType();
   uint64_t LeftSize = S.Context.getTypeSize(LHSExprType);
   if (LHSExprType->isBitIntType())
     LeftSize = S.Context.getIntWidth(LHSExprType);
   else if (LHSExprType->isFixedPointType()) {
     auto FXSema = S.Context.getFixedPointSemantics(LHSExprType);
     LeftSize = FXSema.getWidth() - (unsigned)FXSema.hasUnsignedPadding();
   }
   llvm::APInt LeftBits(Right.getBitWidth(), LeftSize);
   if (Right.uge(LeftBits)) {
     S.DiagRuntimeBehavior(Loc, RHS.get(),
                           S.PDiag(diag::warn_shift_gt_typewidth)
                             << RHS.get()->getSourceRange());
     return;
   }
 
   // FIXME: We probably need to handle fixed point types specially here.
   if (Opc != BO_Shl || LHSExprType->isFixedPointType())
     return;
 
   // When left shifting an ICE which is signed, we can check for overflow which
   // according to C++ standards prior to C++2a has undefined behavior
   // ([expr.shift] 5.8/2). Unsigned integers have defined behavior modulo one
   // more than the maximum value representable in the result type, so never
   // warn for those. (FIXME: Unsigned left-shift overflow in a constant
   // expression is still probably a bug.)
   Expr::EvalResult LHSResult;
   if (LHS.get()->isValueDependent() ||
       LHSType->hasUnsignedIntegerRepresentation() ||
       !LHS.get()->EvaluateAsInt(LHSResult, S.Context))
     return;
   llvm::APSInt Left = LHSResult.Val.getInt();
 
   // Don't warn if signed overflow is defined, then all the rest of the
   // diagnostics will not be triggered because the behavior is defined.
   // Also don't warn in C++20 mode (and newer), as signed left shifts
   // always wrap and never overflow.
   if (S.getLangOpts().isSignedOverflowDefined() || S.getLangOpts().CPlusPlus20)
     return;
 
   // If LHS does not have a non-negative value then, the
   // behavior is undefined before C++2a. Warn about it.
   if (Left.isNegative()) {
     S.DiagRuntimeBehavior(Loc, LHS.get(),
                           S.PDiag(diag::warn_shift_lhs_negative)
                             << LHS.get()->getSourceRange());
     return;
   }
 
   llvm::APInt ResultBits =
       static_cast<llvm::APInt &>(Right) + Left.getSignificantBits();
   if (LeftBits.uge(ResultBits))
     return;
   llvm::APSInt Result = Left.extend(ResultBits.getLimitedValue());
   Result = Result.shl(Right);
 
   // Print the bit representation of the signed integer as an unsigned
   // hexadecimal number.
   SmallString<40> HexResult;
   Result.toString(HexResult, 16, /*Signed =*/false, /*Literal =*/true);
 
   // If we are only missing a sign bit, this is less likely to result in actual
   // bugs -- if the result is cast back to an unsigned type, it will have the
   // expected value. Thus we place this behind a different warning that can be
   // turned off separately if needed.
   if (LeftBits == ResultBits - 1) {
     S.Diag(Loc, diag::warn_shift_result_sets_sign_bit)
         << HexResult << LHSType
         << LHS.get()->getSourceRange() << RHS.get()->getSourceRange();
     return;
   }
 
   S.Diag(Loc, diag::warn_shift_result_gt_typewidth)
       << HexResult.str() << Result.getSignificantBits() << LHSType
       << Left.getBitWidth() << LHS.get()->getSourceRange()
       << RHS.get()->getSourceRange();
 }
 
 /// Return the resulting type when a vector is shifted
 ///        by a scalar or vector shift amount.
 static QualType checkVectorShift(Sema &S, ExprResult &LHS, ExprResult &RHS,
                                  SourceLocation Loc, bool IsCompAssign) {
   // OpenCL v1.1 s6.3.j says RHS can be a vector only if LHS is a vector.
   if ((S.LangOpts.OpenCL || S.LangOpts.ZVector) &&
       !LHS.get()->getType()->isVectorType()) {
     S.Diag(Loc, diag::err_shift_rhs_only_vector)
       << RHS.get()->getType() << LHS.get()->getType()
       << LHS.get()->getSourceRange() << RHS.get()->getSourceRange();
     return QualType();
   }
 
   if (!IsCompAssign) {
     LHS = S.UsualUnaryConversions(LHS.get());
     if (LHS.isInvalid()) return QualType();
   }
 
   RHS = S.UsualUnaryConversions(RHS.get());
   if (RHS.isInvalid()) return QualType();
 
   QualType LHSType = LHS.get()->getType();
   // Note that LHS might be a scalar because the routine calls not only in
   // OpenCL case.
   const VectorType *LHSVecTy = LHSType->getAs<VectorType>();
   QualType LHSEleType = LHSVecTy ? LHSVecTy->getElementType() : LHSType;
 
   // Note that RHS might not be a vector.
   QualType RHSType = RHS.get()->getType();
   const VectorType *RHSVecTy = RHSType->getAs<VectorType>();
   QualType RHSEleType = RHSVecTy ? RHSVecTy->getElementType() : RHSType;
 
   // Do not allow shifts for boolean vectors.
   if ((LHSVecTy && LHSVecTy->isExtVectorBoolType()) ||
       (RHSVecTy && RHSVecTy->isExtVectorBoolType())) {
     S.Diag(Loc, diag::err_typecheck_invalid_operands)
         << LHS.get()->getType() << RHS.get()->getType()
         << LHS.get()->getSourceRange();
     return QualType();
   }
 
   // The operands need to be integers.
   if (!LHSEleType->isIntegerType()) {
     S.Diag(Loc, diag::err_typecheck_expect_int)
       << LHS.get()->getType() << LHS.get()->getSourceRange();
     return QualType();
   }
 
   if (!RHSEleType->isIntegerType()) {
     S.Diag(Loc, diag::err_typecheck_expect_int)
       << RHS.get()->getType() << RHS.get()->getSourceRange();
     return QualType();
   }
 
   if (!LHSVecTy) {
     assert(RHSVecTy);
     if (IsCompAssign)
       return RHSType;
     if (LHSEleType != RHSEleType) {
       LHS = S.ImpCastExprToType(LHS.get(),RHSEleType, CK_IntegralCast);
       LHSEleType = RHSEleType;
     }
     QualType VecTy =
         S.Context.getExtVectorType(LHSEleType, RHSVecTy->getNumElements());
     LHS = S.ImpCastExprToType(LHS.get(), VecTy, CK_VectorSplat);
     LHSType = VecTy;
   } else if (RHSVecTy) {
     // OpenCL v1.1 s6.3.j says that for vector types, the operators
     // are applied component-wise. So if RHS is a vector, then ensure
     // that the number of elements is the same as LHS...
     if (RHSVecTy->getNumElements() != LHSVecTy->getNumElements()) {
       S.Diag(Loc, diag::err_typecheck_vector_lengths_not_equal)
         << LHS.get()->getType() << RHS.get()->getType()
         << LHS.get()->getSourceRange() << RHS.get()->getSourceRange();
       return QualType();
     }
     if (!S.LangOpts.OpenCL && !S.LangOpts.ZVector) {
       const BuiltinType *LHSBT = LHSEleType->getAs<clang::BuiltinType>();
       const BuiltinType *RHSBT = RHSEleType->getAs<clang::BuiltinType>();
       if (LHSBT != RHSBT &&
           S.Context.getTypeSize(LHSBT) != S.Context.getTypeSize(RHSBT)) {
         S.Diag(Loc, diag::warn_typecheck_vector_element_sizes_not_equal)
             << LHS.get()->getType() << RHS.get()->getType()
             << LHS.get()->getSourceRange() << RHS.get()->getSourceRange();
       }
     }
   } else {
     // ...else expand RHS to match the number of elements in LHS.
     QualType VecTy =
       S.Context.getExtVectorType(RHSEleType, LHSVecTy->getNumElements());
     RHS = S.ImpCastExprToType(RHS.get(), VecTy, CK_VectorSplat);
   }
 
   return LHSType;
 }
 
 static QualType checkSizelessVectorShift(Sema &S, ExprResult &LHS,
                                          ExprResult &RHS, SourceLocation Loc,
                                          bool IsCompAssign) {
   if (!IsCompAssign) {
     LHS = S.UsualUnaryConversions(LHS.get());
     if (LHS.isInvalid())
       return QualType();
   }
 
   RHS = S.UsualUnaryConversions(RHS.get());
   if (RHS.isInvalid())
     return QualType();
 
   QualType LHSType = LHS.get()->getType();
   const BuiltinType *LHSBuiltinTy = LHSType->castAs<BuiltinType>();
   QualType LHSEleType = LHSType->isVLSTBuiltinType()
                             ? LHSBuiltinTy->getSveEltType(S.getASTContext())
                             : LHSType;
 
   // Note that RHS might not be a vector
   QualType RHSType = RHS.get()->getType();
   const BuiltinType *RHSBuiltinTy = RHSType->castAs<BuiltinType>();
   QualType RHSEleType = RHSType->isVLSTBuiltinType()
                             ? RHSBuiltinTy->getSveEltType(S.getASTContext())
                             : RHSType;
 
   if ((LHSBuiltinTy && LHSBuiltinTy->isSVEBool()) ||
       (RHSBuiltinTy && RHSBuiltinTy->isSVEBool())) {
     S.Diag(Loc, diag::err_typecheck_invalid_operands)
         << LHSType << RHSType << LHS.get()->getSourceRange();
     return QualType();
   }
 
   if (!LHSEleType->isIntegerType()) {
     S.Diag(Loc, diag::err_typecheck_expect_int)
         << LHS.get()->getType() << LHS.get()->getSourceRange();
     return QualType();
   }
 
   if (!RHSEleType->isIntegerType()) {
     S.Diag(Loc, diag::err_typecheck_expect_int)
         << RHS.get()->getType() << RHS.get()->getSourceRange();
     return QualType();
   }
 
   if (LHSType->isVLSTBuiltinType() && RHSType->isVLSTBuiltinType() &&
       (S.Context.getBuiltinVectorTypeInfo(LHSBuiltinTy).EC !=
        S.Context.getBuiltinVectorTypeInfo(RHSBuiltinTy).EC)) {
     S.Diag(Loc, diag::err_typecheck_invalid_operands)
         << LHSType << RHSType << LHS.get()->getSourceRange()
         << RHS.get()->getSourceRange();
     return QualType();
   }
 
   if (!LHSType->isVLSTBuiltinType()) {
     assert(RHSType->isVLSTBuiltinType());
     if (IsCompAssign)
       return RHSType;
     if (LHSEleType != RHSEleType) {
       LHS = S.ImpCastExprToType(LHS.get(), RHSEleType, clang::CK_IntegralCast);
       LHSEleType = RHSEleType;
     }
     const llvm::ElementCount VecSize =
         S.Context.getBuiltinVectorTypeInfo(RHSBuiltinTy).EC;
     QualType VecTy =
         S.Context.getScalableVectorType(LHSEleType, VecSize.getKnownMinValue());
     LHS = S.ImpCastExprToType(LHS.get(), VecTy, clang::CK_VectorSplat);
     LHSType = VecTy;
   } else if (RHSBuiltinTy && RHSBuiltinTy->isVLSTBuiltinType()) {
     if (S.Context.getTypeSize(RHSBuiltinTy) !=
         S.Context.getTypeSize(LHSBuiltinTy)) {
       S.Diag(Loc, diag::err_typecheck_vector_lengths_not_equal)
           << LHSType << RHSType << LHS.get()->getSourceRange()
           << RHS.get()->getSourceRange();
       return QualType();
     }
   } else {
     const llvm::ElementCount VecSize =
         S.Context.getBuiltinVectorTypeInfo(LHSBuiltinTy).EC;
     if (LHSEleType != RHSEleType) {
       RHS = S.ImpCastExprToType(RHS.get(), LHSEleType, clang::CK_IntegralCast);
       RHSEleType = LHSEleType;
     }
     QualType VecTy =
         S.Context.getScalableVectorType(RHSEleType, VecSize.getKnownMinValue());
     RHS = S.ImpCastExprToType(RHS.get(), VecTy, CK_VectorSplat);
   }
 
   return LHSType;
 }
 
 // C99 6.5.7
 QualType Sema::CheckShiftOperands(ExprResult &LHS, ExprResult &RHS,
                                   SourceLocation Loc, BinaryOperatorKind Opc,
                                   bool IsCompAssign) {
   checkArithmeticNull(*this, LHS, RHS, Loc, /*IsCompare=*/false);
 
   // Vector shifts promote their scalar inputs to vector type.
   if (LHS.get()->getType()->isVectorType() ||
       RHS.get()->getType()->isVectorType()) {
     if (LangOpts.ZVector) {
       // The shift operators for the z vector extensions work basically
       // like general shifts, except that neither the LHS nor the RHS is
       // allowed to be a "vector bool".
       if (auto LHSVecType = LHS.get()->getType()->getAs<VectorType>())
         if (LHSVecType->getVectorKind() == VectorType::AltiVecBool)
           return InvalidOperands(Loc, LHS, RHS);
       if (auto RHSVecType = RHS.get()->getType()->getAs<VectorType>())
         if (RHSVecType->getVectorKind() == VectorType::AltiVecBool)
           return InvalidOperands(Loc, LHS, RHS);
     }
     return checkVectorShift(*this, LHS, RHS, Loc, IsCompAssign);
   }
 
   if (LHS.get()->getType()->isVLSTBuiltinType() ||
       RHS.get()->getType()->isVLSTBuiltinType())
     return checkSizelessVectorShift(*this, LHS, RHS, Loc, IsCompAssign);
 
   // Shifts don't perform usual arithmetic conversions, they just do integer
   // promotions on each operand. C99 6.5.7p3
 
   // For the LHS, do usual unary conversions, but then reset them away
   // if this is a compound assignment.
   ExprResult OldLHS = LHS;
   LHS = UsualUnaryConversions(LHS.get());
   if (LHS.isInvalid())
     return QualType();
   QualType LHSType = LHS.get()->getType();
   if (IsCompAssign) LHS = OldLHS;
 
   // The RHS is simpler.
   RHS = UsualUnaryConversions(RHS.get());
   if (RHS.isInvalid())
     return QualType();
   QualType RHSType = RHS.get()->getType();
 
   // C99 6.5.7p2: Each of the operands shall have integer type.
   // Embedded-C 4.1.6.2.2: The LHS may also be fixed-point.
   if ((!LHSType->isFixedPointOrIntegerType() &&
        !LHSType->hasIntegerRepresentation()) ||
       !RHSType->hasIntegerRepresentation())
     return InvalidOperands(Loc, LHS, RHS);
 
   // C++0x: Don't allow scoped enums. FIXME: Use something better than
   // hasIntegerRepresentation() above instead of this.
   if (isScopedEnumerationType(LHSType) ||
       isScopedEnumerationType(RHSType)) {
     return InvalidOperands(Loc, LHS, RHS);
   }
   DiagnoseBadShiftValues(*this, LHS, RHS, Loc, Opc, LHSType);
 
   // "The type of the result is that of the promoted left operand."
   return LHSType;
 }
 
 /// Diagnose bad pointer comparisons.
 static void diagnoseDistinctPointerComparison(Sema &S, SourceLocation Loc,
                                               ExprResult &LHS, ExprResult &RHS,
                                               bool IsError) {
   S.Diag(Loc, IsError ? diag::err_typecheck_comparison_of_distinct_pointers
                       : diag::ext_typecheck_comparison_of_distinct_pointers)
     << LHS.get()->getType() << RHS.get()->getType()
     << LHS.get()->getSourceRange() << RHS.get()->getSourceRange();
 }
 
 /// Returns false if the pointers are converted to a composite type,
 /// true otherwise.
 static bool convertPointersToCompositeType(Sema &S, SourceLocation Loc,
                                            ExprResult &LHS, ExprResult &RHS) {
   // C++ [expr.rel]p2:
   //   [...] Pointer conversions (4.10) and qualification
   //   conversions (4.4) are performed on pointer operands (or on
   //   a pointer operand and a null pointer constant) to bring
   //   them to their composite pointer type. [...]
   //
   // C++ [expr.eq]p1 uses the same notion for (in)equality
   // comparisons of pointers.
 
   QualType LHSType = LHS.get()->getType();
   QualType RHSType = RHS.get()->getType();
   assert(LHSType->isPointerType() || RHSType->isPointerType() ||
          LHSType->isMemberPointerType() || RHSType->isMemberPointerType());
 
   QualType T = S.FindCompositePointerType(Loc, LHS, RHS);
   if (T.isNull()) {
     if ((LHSType->isAnyPointerType() || LHSType->isMemberPointerType()) &&
         (RHSType->isAnyPointerType() || RHSType->isMemberPointerType()))
       diagnoseDistinctPointerComparison(S, Loc, LHS, RHS, /*isError*/true);
     else
       S.InvalidOperands(Loc, LHS, RHS);
     return true;
   }
 
   return false;
 }
 
 static void diagnoseFunctionPointerToVoidComparison(Sema &S, SourceLocation Loc,
                                                     ExprResult &LHS,
                                                     ExprResult &RHS,
                                                     bool IsError) {
   S.Diag(Loc, IsError ? diag::err_typecheck_comparison_of_fptr_to_void
                       : diag::ext_typecheck_comparison_of_fptr_to_void)
     << LHS.get()->getType() << RHS.get()->getType()
     << LHS.get()->getSourceRange() << RHS.get()->getSourceRange();
 }
 
 static bool isObjCObjectLiteral(ExprResult &E) {
   switch (E.get()->IgnoreParenImpCasts()->getStmtClass()) {
   case Stmt::ObjCArrayLiteralClass:
   case Stmt::ObjCDictionaryLiteralClass:
   case Stmt::ObjCStringLiteralClass:
   case Stmt::ObjCBoxedExprClass:
     return true;
   default:
     // Note that ObjCBoolLiteral is NOT an object literal!
     return false;
   }
 }
 
 static bool hasIsEqualMethod(Sema &S, const Expr *LHS, const Expr *RHS) {
   const ObjCObjectPointerType *Type =
     LHS->getType()->getAs<ObjCObjectPointerType>();
 
   // If this is not actually an Objective-C object, bail out.
   if (!Type)
     return false;
 
   // Get the LHS object's interface type.
   QualType InterfaceType = Type->getPointeeType();
 
   // If the RHS isn't an Objective-C object, bail out.
   if (!RHS->getType()->isObjCObjectPointerType())
     return false;
 
   // Try to find the -isEqual: method.
   Selector IsEqualSel = S.NSAPIObj->getIsEqualSelector();
   ObjCMethodDecl *Method = S.LookupMethodInObjectType(IsEqualSel,
                                                       InterfaceType,
                                                       /*IsInstance=*/true);
   if (!Method) {
     if (Type->isObjCIdType()) {
       // For 'id', just check the global pool.
       Method = S.LookupInstanceMethodInGlobalPool(IsEqualSel, SourceRange(),
                                                   /*receiverId=*/true);
     } else {
       // Check protocols.
       Method = S.LookupMethodInQualifiedType(IsEqualSel, Type,
                                              /*IsInstance=*/true);
     }
   }
 
   if (!Method)
     return false;
 
   QualType T = Method->parameters()[0]->getType();
   if (!T->isObjCObjectPointerType())
     return false;
 
   QualType R = Method->getReturnType();
   if (!R->isScalarType())
     return false;
 
   return true;
 }
 
 Sema::ObjCLiteralKind Sema::CheckLiteralKind(Expr *FromE) {
   FromE = FromE->IgnoreParenImpCasts();
   switch (FromE->getStmtClass()) {
     default:
       break;
     case Stmt::ObjCStringLiteralClass:
       // "string literal"
       return LK_String;
     case Stmt::ObjCArrayLiteralClass:
       // "array literal"
       return LK_Array;
     case Stmt::ObjCDictionaryLiteralClass:
       // "dictionary literal"
       return LK_Dictionary;
     case Stmt::BlockExprClass:
       return LK_Block;
     case Stmt::ObjCBoxedExprClass: {
       Expr *Inner = cast<ObjCBoxedExpr>(FromE)->getSubExpr()->IgnoreParens();
       switch (Inner->getStmtClass()) {
         case Stmt::IntegerLiteralClass:
         case Stmt::FloatingLiteralClass:
         case Stmt::CharacterLiteralClass:
         case Stmt::ObjCBoolLiteralExprClass:
         case Stmt::CXXBoolLiteralExprClass:
           // "numeric literal"
           return LK_Numeric;
         case Stmt::ImplicitCastExprClass: {
           CastKind CK = cast<CastExpr>(Inner)->getCastKind();
           // Boolean literals can be represented by implicit casts.
           if (CK == CK_IntegralToBoolean || CK == CK_IntegralCast)
             return LK_Numeric;
           break;
         }
         default:
           break;
       }
       return LK_Boxed;
     }
   }
   return LK_None;
 }
 
 static void diagnoseObjCLiteralComparison(Sema &S, SourceLocation Loc,
                                           ExprResult &LHS, ExprResult &RHS,
                                           BinaryOperator::Opcode Opc){
   Expr *Literal;
   Expr *Other;
   if (isObjCObjectLiteral(LHS)) {
     Literal = LHS.get();
     Other = RHS.get();
   } else {
     Literal = RHS.get();
     Other = LHS.get();
   }
 
   // Don't warn on comparisons against nil.
   Other = Other->IgnoreParenCasts();
   if (Other->isNullPointerConstant(S.getASTContext(),
                                    Expr::NPC_ValueDependentIsNotNull))
     return;
 
   // This should be kept in sync with warn_objc_literal_comparison.
   // LK_String should always be after the other literals, since it has its own
   // warning flag.
   Sema::ObjCLiteralKind LiteralKind = S.CheckLiteralKind(Literal);
   assert(LiteralKind != Sema::LK_Block);
   if (LiteralKind == Sema::LK_None) {
     llvm_unreachable("Unknown Objective-C object literal kind");
   }
 
   if (LiteralKind == Sema::LK_String)
     S.Diag(Loc, diag::warn_objc_string_literal_comparison)
       << Literal->getSourceRange();
   else
     S.Diag(Loc, diag::warn_objc_literal_comparison)
       << LiteralKind << Literal->getSourceRange();
 
   if (BinaryOperator::isEqualityOp(Opc) &&
       hasIsEqualMethod(S, LHS.get(), RHS.get())) {
     SourceLocation Start = LHS.get()->getBeginLoc();
     SourceLocation End = S.getLocForEndOfToken(RHS.get()->getEndLoc());
     CharSourceRange OpRange =
       CharSourceRange::getCharRange(Loc, S.getLocForEndOfToken(Loc));
 
     S.Diag(Loc, diag::note_objc_literal_comparison_isequal)
       << FixItHint::CreateInsertion(Start, Opc == BO_EQ ? "[" : "![")
       << FixItHint::CreateReplacement(OpRange, " isEqual:")
       << FixItHint::CreateInsertion(End, "]");
   }
 }
 
 /// Warns on !x < y, !x & y where !(x < y), !(x & y) was probably intended.
 static void diagnoseLogicalNotOnLHSofCheck(Sema &S, ExprResult &LHS,
                                            ExprResult &RHS, SourceLocation Loc,
                                            BinaryOperatorKind Opc) {
   // Check that left hand side is !something.
   UnaryOperator *UO = dyn_cast<UnaryOperator>(LHS.get()->IgnoreImpCasts());
   if (!UO || UO->getOpcode() != UO_LNot) return;
 
   // Only check if the right hand side is non-bool arithmetic type.
   if (RHS.get()->isKnownToHaveBooleanValue()) return;
 
   // Make sure that the something in !something is not bool.
   Expr *SubExpr = UO->getSubExpr()->IgnoreImpCasts();
   if (SubExpr->isKnownToHaveBooleanValue()) return;
 
   // Emit warning.
   bool IsBitwiseOp = Opc == BO_And || Opc == BO_Or || Opc == BO_Xor;
   S.Diag(UO->getOperatorLoc(), diag::warn_logical_not_on_lhs_of_check)
       << Loc << IsBitwiseOp;
 
   // First note suggest !(x < y)
   SourceLocation FirstOpen = SubExpr->getBeginLoc();
   SourceLocation FirstClose = RHS.get()->getEndLoc();
   FirstClose = S.getLocForEndOfToken(FirstClose);
   if (FirstClose.isInvalid())
     FirstOpen = SourceLocation();
   S.Diag(UO->getOperatorLoc(), diag::note_logical_not_fix)
       << IsBitwiseOp
       << FixItHint::CreateInsertion(FirstOpen, "(")
       << FixItHint::CreateInsertion(FirstClose, ")");
 
   // Second note suggests (!x) < y
   SourceLocation SecondOpen = LHS.get()->getBeginLoc();
   SourceLocation SecondClose = LHS.get()->getEndLoc();
   SecondClose = S.getLocForEndOfToken(SecondClose);
   if (SecondClose.isInvalid())
     SecondOpen = SourceLocation();
   S.Diag(UO->getOperatorLoc(), diag::note_logical_not_silence_with_parens)
       << FixItHint::CreateInsertion(SecondOpen, "(")
       << FixItHint::CreateInsertion(SecondClose, ")");
 }
 
 // Returns true if E refers to a non-weak array.
 static bool checkForArray(const Expr *E) {
   const ValueDecl *D = nullptr;
   if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(E)) {
     D = DR->getDecl();
   } else if (const MemberExpr *Mem = dyn_cast<MemberExpr>(E)) {
     if (Mem->isImplicitAccess())
       D = Mem->getMemberDecl();
   }
   if (!D)
     return false;
   return D->getType()->isArrayType() && !D->isWeak();
 }
 
 /// Diagnose some forms of syntactically-obvious tautological comparison.
 static void diagnoseTautologicalComparison(Sema &S, SourceLocation Loc,
                                            Expr *LHS, Expr *RHS,
                                            BinaryOperatorKind Opc) {
   Expr *LHSStripped = LHS->IgnoreParenImpCasts();
   Expr *RHSStripped = RHS->IgnoreParenImpCasts();
 
   QualType LHSType = LHS->getType();
   QualType RHSType = RHS->getType();
   if (LHSType->hasFloatingRepresentation() ||
       (LHSType->isBlockPointerType() && !BinaryOperator::isEqualityOp(Opc)) ||
       S.inTemplateInstantiation())
     return;
 
   // WebAssembly Tables cannot be compared, therefore shouldn't emit
   // Tautological diagnostics.
   if (LHSType->isWebAssemblyTableType() || RHSType->isWebAssemblyTableType())
     return;
 
   // Comparisons between two array types are ill-formed for operator<=>, so
   // we shouldn't emit any additional warnings about it.
   if (Opc == BO_Cmp && LHSType->isArrayType() && RHSType->isArrayType())
     return;
 
   // For non-floating point types, check for self-comparisons of the form
   // x == x, x != x, x < x, etc.  These always evaluate to a constant, and
   // often indicate logic errors in the program.
   //
   // NOTE: Don't warn about comparison expressions resulting from macro
   // expansion. Also don't warn about comparisons which are only self
   // comparisons within a template instantiation. The warnings should catch
   // obvious cases in the definition of the template anyways. The idea is to
   // warn when the typed comparison operator will always evaluate to the same
   // result.
 
   // Used for indexing into %select in warn_comparison_always
   enum {
     AlwaysConstant,
     AlwaysTrue,
     AlwaysFalse,
     AlwaysEqual, // std::strong_ordering::equal from operator<=>
   };
 
   // C++2a [depr.array.comp]:
   //   Equality and relational comparisons ([expr.eq], [expr.rel]) between two
   //   operands of array type are deprecated.
   if (S.getLangOpts().CPlusPlus20 && LHSStripped->getType()->isArrayType() &&
       RHSStripped->getType()->isArrayType()) {
     S.Diag(Loc, diag::warn_depr_array_comparison)
         << LHS->getSourceRange() << RHS->getSourceRange()
         << LHSStripped->getType() << RHSStripped->getType();
     // Carry on to produce the tautological comparison warning, if this
     // expression is potentially-evaluated, we can resolve the array to a
     // non-weak declaration, and so on.
   }
 
   if (!LHS->getBeginLoc().isMacroID() && !RHS->getBeginLoc().isMacroID()) {
     if (Expr::isSameComparisonOperand(LHS, RHS)) {
       unsigned Result;
       switch (Opc) {
       case BO_EQ:
       case BO_LE:
       case BO_GE:
         Result = AlwaysTrue;
         break;
       case BO_NE:
       case BO_LT:
       case BO_GT:
         Result = AlwaysFalse;
         break;
       case BO_Cmp:
         Result = AlwaysEqual;
         break;
       default:
         Result = AlwaysConstant;
         break;
       }
       S.DiagRuntimeBehavior(Loc, nullptr,
                             S.PDiag(diag::warn_comparison_always)
                                 << 0 /*self-comparison*/
                                 << Result);
     } else if (checkForArray(LHSStripped) && checkForArray(RHSStripped)) {
       // What is it always going to evaluate to?
       unsigned Result;
       switch (Opc) {
       case BO_EQ: // e.g. array1 == array2
         Result = AlwaysFalse;
         break;
       case BO_NE: // e.g. array1 != array2
         Result = AlwaysTrue;
         break;
       default: // e.g. array1 <= array2
         // The best we can say is 'a constant'
         Result = AlwaysConstant;
         break;
       }
       S.DiagRuntimeBehavior(Loc, nullptr,
                             S.PDiag(diag::warn_comparison_always)
                                 << 1 /*array comparison*/
                                 << Result);
     }
   }
 
   if (isa<CastExpr>(LHSStripped))
     LHSStripped = LHSStripped->IgnoreParenCasts();
   if (isa<CastExpr>(RHSStripped))
     RHSStripped = RHSStripped->IgnoreParenCasts();
 
   // Warn about comparisons against a string constant (unless the other
   // operand is null); the user probably wants string comparison function.
   Expr *LiteralString = nullptr;
   Expr *LiteralStringStripped = nullptr;
   if ((isa<StringLiteral>(LHSStripped) || isa<ObjCEncodeExpr>(LHSStripped)) &&
       !RHSStripped->isNullPointerConstant(S.Context,
                                           Expr::NPC_ValueDependentIsNull)) {
     LiteralString = LHS;
     LiteralStringStripped = LHSStripped;
   } else if ((isa<StringLiteral>(RHSStripped) ||
               isa<ObjCEncodeExpr>(RHSStripped)) &&
              !LHSStripped->isNullPointerConstant(S.Context,
                                           Expr::NPC_ValueDependentIsNull)) {
     LiteralString = RHS;
     LiteralStringStripped = RHSStripped;
   }
 
   if (LiteralString) {
     S.DiagRuntimeBehavior(Loc, nullptr,
                           S.PDiag(diag::warn_stringcompare)
                               << isa<ObjCEncodeExpr>(LiteralStringStripped)
                               << LiteralString->getSourceRange());
   }
 }
 
 static ImplicitConversionKind castKindToImplicitConversionKind(CastKind CK) {
   switch (CK) {
   default: {
 #ifndef NDEBUG
     llvm::errs() << "unhandled cast kind: " << CastExpr::getCastKindName(CK)
                  << "\n";
 #endif
     llvm_unreachable("unhandled cast kind");
   }
   case CK_UserDefinedConversion:
     return ICK_Identity;
   case CK_LValueToRValue:
     return ICK_Lvalue_To_Rvalue;
   case CK_ArrayToPointerDecay:
     return ICK_Array_To_Pointer;
   case CK_FunctionToPointerDecay:
     return ICK_Function_To_Pointer;
   case CK_IntegralCast:
     return ICK_Integral_Conversion;
   case CK_FloatingCast:
     return ICK_Floating_Conversion;
   case CK_IntegralToFloating:
   case CK_FloatingToIntegral:
     return ICK_Floating_Integral;
   case CK_IntegralComplexCast:
   case CK_FloatingComplexCast:
   case CK_FloatingComplexToIntegralComplex:
   case CK_IntegralComplexToFloatingComplex:
     return ICK_Complex_Conversion;
   case CK_FloatingComplexToReal:
   case CK_FloatingRealToComplex:
   case CK_IntegralComplexToReal:
   case CK_IntegralRealToComplex:
     return ICK_Complex_Real;
   }
 }
 
 static bool checkThreeWayNarrowingConversion(Sema &S, QualType ToType, Expr *E,
                                              QualType FromType,
                                              SourceLocation Loc) {
   // Check for a narrowing implicit conversion.
   StandardConversionSequence SCS;
   SCS.setAsIdentityConversion();
   SCS.setToType(0, FromType);
   SCS.setToType(1, ToType);
   if (const auto *ICE = dyn_cast<ImplicitCastExpr>(E))
     SCS.Second = castKindToImplicitConversionKind(ICE->getCastKind());
 
   APValue PreNarrowingValue;
   QualType PreNarrowingType;
   switch (SCS.getNarrowingKind(S.Context, E, PreNarrowingValue,
                                PreNarrowingType,
                                /*IgnoreFloatToIntegralConversion*/ true)) {
   case NK_Dependent_Narrowing:
     // Implicit conversion to a narrower type, but the expression is
     // value-dependent so we can't tell whether it's actually narrowing.
   case NK_Not_Narrowing:
     return false;
 
   case NK_Constant_Narrowing:
     // Implicit conversion to a narrower type, and the value is not a constant
     // expression.
     S.Diag(E->getBeginLoc(), diag::err_spaceship_argument_narrowing)
         << /*Constant*/ 1
         << PreNarrowingValue.getAsString(S.Context, PreNarrowingType) << ToType;
     return true;
 
   case NK_Variable_Narrowing:
     // Implicit conversion to a narrower type, and the value is not a constant
     // expression.
   case NK_Type_Narrowing:
     S.Diag(E->getBeginLoc(), diag::err_spaceship_argument_narrowing)
         << /*Constant*/ 0 << FromType << ToType;
     // TODO: It's not a constant expression, but what if the user intended it
     // to be? Can we produce notes to help them figure out why it isn't?
     return true;
   }
   llvm_unreachable("unhandled case in switch");
 }
 
 static QualType checkArithmeticOrEnumeralThreeWayCompare(Sema &S,
                                                          ExprResult &LHS,
                                                          ExprResult &RHS,
                                                          SourceLocation Loc) {
   QualType LHSType = LHS.get()->getType();
   QualType RHSType = RHS.get()->getType();
   // Dig out the original argument type and expression before implicit casts
   // were applied. These are the types/expressions we need to check the
   // [expr.spaceship] requirements against.
   ExprResult LHSStripped = LHS.get()->IgnoreParenImpCasts();
   ExprResult RHSStripped = RHS.get()->IgnoreParenImpCasts();
   QualType LHSStrippedType = LHSStripped.get()->getType();
   QualType RHSStrippedType = RHSStripped.get()->getType();
 
   // C++2a [expr.spaceship]p3: If one of the operands is of type bool and the
   // other is not, the program is ill-formed.
   if (LHSStrippedType->isBooleanType() != RHSStrippedType->isBooleanType()) {
     S.InvalidOperands(Loc, LHSStripped, RHSStripped);
     return QualType();
   }
 
   // FIXME: Consider combining this with checkEnumArithmeticConversions.
   int NumEnumArgs = (int)LHSStrippedType->isEnumeralType() +
                     RHSStrippedType->isEnumeralType();
   if (NumEnumArgs == 1) {
     bool LHSIsEnum = LHSStrippedType->isEnumeralType();
     QualType OtherTy = LHSIsEnum ? RHSStrippedType : LHSStrippedType;
     if (OtherTy->hasFloatingRepresentation()) {
       S.InvalidOperands(Loc, LHSStripped, RHSStripped);
       return QualType();
     }
   }
   if (NumEnumArgs == 2) {
     // C++2a [expr.spaceship]p5: If both operands have the same enumeration
     // type E, the operator yields the result of converting the operands
     // to the underlying type of E and applying <=> to the converted operands.
     if (!S.Context.hasSameUnqualifiedType(LHSStrippedType, RHSStrippedType)) {
       S.InvalidOperands(Loc, LHS, RHS);
       return QualType();
     }
     QualType IntType =
         LHSStrippedType->castAs<EnumType>()->getDecl()->getIntegerType();
     assert(IntType->isArithmeticType());
 
     // We can't use `CK_IntegralCast` when the underlying type is 'bool', so we
     // promote the boolean type, and all other promotable integer types, to
     // avoid this.
     if (S.Context.isPromotableIntegerType(IntType))
       IntType = S.Context.getPromotedIntegerType(IntType);
 
     LHS = S.ImpCastExprToType(LHS.get(), IntType, CK_IntegralCast);
     RHS = S.ImpCastExprToType(RHS.get(), IntType, CK_IntegralCast);
     LHSType = RHSType = IntType;
   }
 
   // C++2a [expr.spaceship]p4: If both operands have arithmetic types, the
   // usual arithmetic conversions are applied to the operands.
   QualType Type =
       S.UsualArithmeticConversions(LHS, RHS, Loc, Sema::ACK_Comparison);
   if (LHS.isInvalid() || RHS.isInvalid())
     return QualType();
   if (Type.isNull())
     return S.InvalidOperands(Loc, LHS, RHS);
 
   std::optional<ComparisonCategoryType> CCT =
       getComparisonCategoryForBuiltinCmp(Type);
   if (!CCT)
     return S.InvalidOperands(Loc, LHS, RHS);
 
   bool HasNarrowing = checkThreeWayNarrowingConversion(
       S, Type, LHS.get(), LHSType, LHS.get()->getBeginLoc());
   HasNarrowing |= checkThreeWayNarrowingConversion(S, Type, RHS.get(), RHSType,
                                                    RHS.get()->getBeginLoc());
   if (HasNarrowing)
     return QualType();
 
   assert(!Type.isNull() && "composite type for <=> has not been set");
 
   return S.CheckComparisonCategoryType(
       *CCT, Loc, Sema::ComparisonCategoryUsage::OperatorInExpression);
 }
 
 static QualType checkArithmeticOrEnumeralCompare(Sema &S, ExprResult &LHS,
                                                  ExprResult &RHS,
                                                  SourceLocation Loc,
                                                  BinaryOperatorKind Opc) {
   if (Opc == BO_Cmp)
     return checkArithmeticOrEnumeralThreeWayCompare(S, LHS, RHS, Loc);
 
   // C99 6.5.8p3 / C99 6.5.9p4
   QualType Type =
       S.UsualArithmeticConversions(LHS, RHS, Loc, Sema::ACK_Comparison);
   if (LHS.isInvalid() || RHS.isInvalid())
     return QualType();
   if (Type.isNull())
     return S.InvalidOperands(Loc, LHS, RHS);
   assert(Type->isArithmeticType() || Type->isEnumeralType());
 
   if (Type->isAnyComplexType() && BinaryOperator::isRelationalOp(Opc))
     return S.InvalidOperands(Loc, LHS, RHS);
 
   // Check for comparisons of floating point operands using != and ==.
   if (Type->hasFloatingRepresentation())
     S.CheckFloatComparison(Loc, LHS.get(), RHS.get(), Opc);
 
   // The result of comparisons is 'bool' in C++, 'int' in C.
   return S.Context.getLogicalOperationType();
 }
 
 void Sema::CheckPtrComparisonWithNullChar(ExprResult &E, ExprResult &NullE) {
   if (!NullE.get()->getType()->isAnyPointerType())
     return;
   int NullValue = PP.isMacroDefined("NULL") ? 0 : 1;
   if (!E.get()->getType()->isAnyPointerType() &&
       E.get()->isNullPointerConstant(Context,
                                      Expr::NPC_ValueDependentIsNotNull) ==
         Expr::NPCK_ZeroExpression) {
     if (const auto *CL = dyn_cast<CharacterLiteral>(E.get())) {
       if (CL->getValue() == 0)
         Diag(E.get()->getExprLoc(), diag::warn_pointer_compare)
             << NullValue
             << FixItHint::CreateReplacement(E.get()->getExprLoc(),
                                             NullValue ? "NULL" : "(void *)0");
     } else if (const auto *CE = dyn_cast<CStyleCastExpr>(E.get())) {
         TypeSourceInfo *TI = CE->getTypeInfoAsWritten();
         QualType T = Context.getCanonicalType(TI->getType()).getUnqualifiedType();
         if (T == Context.CharTy)
           Diag(E.get()->getExprLoc(), diag::warn_pointer_compare)
               << NullValue
               << FixItHint::CreateReplacement(E.get()->getExprLoc(),
                                               NullValue ? "NULL" : "(void *)0");
       }
   }
 }
 
 // C99 6.5.8, C++ [expr.rel]
 QualType Sema::CheckCompareOperands(ExprResult &LHS, ExprResult &RHS,
                                     SourceLocation Loc,
                                     BinaryOperatorKind Opc) {
   bool IsRelational = BinaryOperator::isRelationalOp(Opc);
   bool IsThreeWay = Opc == BO_Cmp;
   bool IsOrdered = IsRelational || IsThreeWay;
   auto IsAnyPointerType = [](ExprResult E) {
     QualType Ty = E.get()->getType();
     return Ty->isPointerType() || Ty->isMemberPointerType();
   };
 
   // C++2a [expr.spaceship]p6: If at least one of the operands is of pointer
   // type, array-to-pointer, ..., conversions are performed on both operands to
   // bring them to their composite type.
   // Otherwise, all comparisons expect an rvalue, so convert to rvalue before
   // any type-related checks.
   if (!IsThreeWay || IsAnyPointerType(LHS) || IsAnyPointerType(RHS)) {
     LHS = DefaultFunctionArrayLvalueConversion(LHS.get());
     if (LHS.isInvalid())
       return QualType();
     RHS = DefaultFunctionArrayLvalueConversion(RHS.get());
     if (RHS.isInvalid())
       return QualType();
   } else {
     LHS = DefaultLvalueConversion(LHS.get());
     if (LHS.isInvalid())
       return QualType();
     RHS = DefaultLvalueConversion(RHS.get());
     if (RHS.isInvalid())
       return QualType();
   }
 
   checkArithmeticNull(*this, LHS, RHS, Loc, /*IsCompare=*/true);
   if (!getLangOpts().CPlusPlus && BinaryOperator::isEqualityOp(Opc)) {
     CheckPtrComparisonWithNullChar(LHS, RHS);
     CheckPtrComparisonWithNullChar(RHS, LHS);
   }
 
   // Handle vector comparisons separately.
   if (LHS.get()->getType()->isVectorType() ||
       RHS.get()->getType()->isVectorType())
     return CheckVectorCompareOperands(LHS, RHS, Loc, Opc);
 
   if (LHS.get()->getType()->isVLSTBuiltinType() ||
       RHS.get()->getType()->isVLSTBuiltinType())
     return CheckSizelessVectorCompareOperands(LHS, RHS, Loc, Opc);
 
   diagnoseLogicalNotOnLHSofCheck(*this, LHS, RHS, Loc, Opc);
   diagnoseTautologicalComparison(*this, Loc, LHS.get(), RHS.get(), Opc);
 
   QualType LHSType = LHS.get()->getType();
   QualType RHSType = RHS.get()->getType();
   if ((LHSType->isArithmeticType() || LHSType->isEnumeralType()) &&
       (RHSType->isArithmeticType() || RHSType->isEnumeralType()))
     return checkArithmeticOrEnumeralCompare(*this, LHS, RHS, Loc, Opc);
 
   if ((LHSType->isPointerType() &&
        LHSType->getPointeeType().isWebAssemblyReferenceType()) ||
       (RHSType->isPointerType() &&
        RHSType->getPointeeType().isWebAssemblyReferenceType()))
     return InvalidOperands(Loc, LHS, RHS);
 
   const Expr::NullPointerConstantKind LHSNullKind =
       LHS.get()->isNullPointerConstant(Context, Expr::NPC_ValueDependentIsNull);
   const Expr::NullPointerConstantKind RHSNullKind =
       RHS.get()->isNullPointerConstant(Context, Expr::NPC_ValueDependentIsNull);
   bool LHSIsNull = LHSNullKind != Expr::NPCK_NotNull;
   bool RHSIsNull = RHSNullKind != Expr::NPCK_NotNull;
 
   auto computeResultTy = [&]() {
     if (Opc != BO_Cmp)
       return Context.getLogicalOperationType();
     assert(getLangOpts().CPlusPlus);
     assert(Context.hasSameType(LHS.get()->getType(), RHS.get()->getType()));
 
     QualType CompositeTy = LHS.get()->getType();
     assert(!CompositeTy->isReferenceType());
 
     std::optional<ComparisonCategoryType> CCT =
         getComparisonCategoryForBuiltinCmp(CompositeTy);
     if (!CCT)
       return InvalidOperands(Loc, LHS, RHS);
 
     if (CompositeTy->isPointerType() && LHSIsNull != RHSIsNull) {
       // P0946R0: Comparisons between a null pointer constant and an object
       // pointer result in std::strong_equality, which is ill-formed under
       // P1959R0.
       Diag(Loc, diag::err_typecheck_three_way_comparison_of_pointer_and_zero)
           << (LHSIsNull ? LHS.get()->getSourceRange()
                         : RHS.get()->getSourceRange());
       return QualType();
     }
 
     return CheckComparisonCategoryType(
         *CCT, Loc, ComparisonCategoryUsage::OperatorInExpression);
   };
 
   if (!IsOrdered && LHSIsNull != RHSIsNull) {
     bool IsEquality = Opc == BO_EQ;
     if (RHSIsNull)
       DiagnoseAlwaysNonNullPointer(LHS.get(), RHSNullKind, IsEquality,
                                    RHS.get()->getSourceRange());
     else
       DiagnoseAlwaysNonNullPointer(RHS.get(), LHSNullKind, IsEquality,
                                    LHS.get()->getSourceRange());
   }
 
   if (IsOrdered && LHSType->isFunctionPointerType() &&
       RHSType->isFunctionPointerType()) {
     // Valid unless a relational comparison of function pointers
     bool IsError = Opc == BO_Cmp;
     auto DiagID =
         IsError ? diag::err_typecheck_ordered_comparison_of_function_pointers
         : getLangOpts().CPlusPlus
             ? diag::warn_typecheck_ordered_comparison_of_function_pointers
             : diag::ext_typecheck_ordered_comparison_of_function_pointers;
     Diag(Loc, DiagID) << LHSType << RHSType << LHS.get()->getSourceRange()
                       << RHS.get()->getSourceRange();
     if (IsError)
       return QualType();
   }
 
   if ((LHSType->isIntegerType() && !LHSIsNull) ||
       (RHSType->isIntegerType() && !RHSIsNull)) {
     // Skip normal pointer conversion checks in this case; we have better
     // diagnostics for this below.
   } else if (getLangOpts().CPlusPlus) {
     // Equality comparison of a function pointer to a void pointer is invalid,
     // but we allow it as an extension.
     // FIXME: If we really want to allow this, should it be part of composite
     // pointer type computation so it works in conditionals too?
     if (!IsOrdered &&
         ((LHSType->isFunctionPointerType() && RHSType->isVoidPointerType()) ||
          (RHSType->isFunctionPointerType() && LHSType->isVoidPointerType()))) {
       // This is a gcc extension compatibility comparison.
       // In a SFINAE context, we treat this as a hard error to maintain
       // conformance with the C++ standard.
       diagnoseFunctionPointerToVoidComparison(
           *this, Loc, LHS, RHS, /*isError*/ (bool)isSFINAEContext());
 
       if (isSFINAEContext())
         return QualType();
 
       RHS = ImpCastExprToType(RHS.get(), LHSType, CK_BitCast);
       return computeResultTy();
     }
 
     // C++ [expr.eq]p2:
     //   If at least one operand is a pointer [...] bring them to their
     //   composite pointer type.
     // C++ [expr.spaceship]p6
     //  If at least one of the operands is of pointer type, [...] bring them
     //  to their composite pointer type.
     // C++ [expr.rel]p2:
     //   If both operands are pointers, [...] bring them to their composite
     //   pointer type.
     // For <=>, the only valid non-pointer types are arrays and functions, and
     // we already decayed those, so this is really the same as the relational
     // comparison rule.
     if ((int)LHSType->isPointerType() + (int)RHSType->isPointerType() >=
             (IsOrdered ? 2 : 1) &&
         (!LangOpts.ObjCAutoRefCount || !(LHSType->isObjCObjectPointerType() ||
                                          RHSType->isObjCObjectPointerType()))) {
       if (convertPointersToCompositeType(*this, Loc, LHS, RHS))
         return QualType();
       return computeResultTy();
     }
   } else if (LHSType->isPointerType() &&
              RHSType->isPointerType()) { // C99 6.5.8p2
     // All of the following pointer-related warnings are GCC extensions, except
     // when handling null pointer constants.
     QualType LCanPointeeTy =
       LHSType->castAs<PointerType>()->getPointeeType().getCanonicalType();
     QualType RCanPointeeTy =
       RHSType->castAs<PointerType>()->getPointeeType().getCanonicalType();
 
     // C99 6.5.9p2 and C99 6.5.8p2
     if (Context.typesAreCompatible(LCanPointeeTy.getUnqualifiedType(),
                                    RCanPointeeTy.getUnqualifiedType())) {
       if (IsRelational) {
         // Pointers both need to point to complete or incomplete types
         if ((LCanPointeeTy->isIncompleteType() !=
              RCanPointeeTy->isIncompleteType()) &&
             !getLangOpts().C11) {
           Diag(Loc, diag::ext_typecheck_compare_complete_incomplete_pointers)
               << LHS.get()->getSourceRange() << RHS.get()->getSourceRange()
               << LHSType << RHSType << LCanPointeeTy->isIncompleteType()
               << RCanPointeeTy->isIncompleteType();
         }
       }
     } else if (!IsRelational &&
                (LCanPointeeTy->isVoidType() || RCanPointeeTy->isVoidType())) {
       // Valid unless comparison between non-null pointer and function pointer
       if ((LCanPointeeTy->isFunctionType() || RCanPointeeTy->isFunctionType())
           && !LHSIsNull && !RHSIsNull)
         diagnoseFunctionPointerToVoidComparison(*this, Loc, LHS, RHS,
                                                 /*isError*/false);
     } else {
       // Invalid
       diagnoseDistinctPointerComparison(*this, Loc, LHS, RHS, /*isError*/false);
     }
     if (LCanPointeeTy != RCanPointeeTy) {
       // Treat NULL constant as a special case in OpenCL.
       if (getLangOpts().OpenCL && !LHSIsNull && !RHSIsNull) {
         if (!LCanPointeeTy.isAddressSpaceOverlapping(RCanPointeeTy)) {
           Diag(Loc,
                diag::err_typecheck_op_on_nonoverlapping_address_space_pointers)
               << LHSType << RHSType << 0 /* comparison */
               << LHS.get()->getSourceRange() << RHS.get()->getSourceRange();
         }
       }
       LangAS AddrSpaceL = LCanPointeeTy.getAddressSpace();
       LangAS AddrSpaceR = RCanPointeeTy.getAddressSpace();
       CastKind Kind = AddrSpaceL != AddrSpaceR ? CK_AddressSpaceConversion
                                                : CK_BitCast;
       if (LHSIsNull && !RHSIsNull)
         LHS = ImpCastExprToType(LHS.get(), RHSType, Kind);
       else
         RHS = ImpCastExprToType(RHS.get(), LHSType, Kind);
     }
     return computeResultTy();
   }
 
 
   // C++ [expr.eq]p4:
   //   Two operands of type std::nullptr_t or one operand of type
   //   std::nullptr_t and the other a null pointer constant compare
   //   equal.
   // C2x 6.5.9p5:
   //   If both operands have type nullptr_t or one operand has type nullptr_t
   //   and the other is a null pointer constant, they compare equal.
   if (!IsOrdered && LHSIsNull && RHSIsNull) {
     if (LHSType->isNullPtrType()) {
       RHS = ImpCastExprToType(RHS.get(), LHSType, CK_NullToPointer);
       return computeResultTy();
     }
     if (RHSType->isNullPtrType()) {
       LHS = ImpCastExprToType(LHS.get(), RHSType, CK_NullToPointer);
       return computeResultTy();
     }
   }
 
   if (!getLangOpts().CPlusPlus && !IsOrdered && (LHSIsNull || RHSIsNull)) {
     // C2x 6.5.9p6:
     //   Otherwise, at least one operand is a pointer. If one is a pointer and
     //   the other is a null pointer constant, the null pointer constant is
     //   converted to the type of the pointer.
     if (LHSIsNull && RHSType->isPointerType()) {
       LHS = ImpCastExprToType(LHS.get(), RHSType, CK_NullToPointer);
       return computeResultTy();
     }
     if (RHSIsNull && LHSType->isPointerType()) {
       RHS = ImpCastExprToType(RHS.get(), LHSType, CK_NullToPointer);
       return computeResultTy();
     }
   }
 
   // Comparison of Objective-C pointers and block pointers against nullptr_t.
   // These aren't covered by the composite pointer type rules.
   if (!IsOrdered && RHSType->isNullPtrType() &&
       (LHSType->isObjCObjectPointerType() || LHSType->isBlockPointerType())) {
     RHS = ImpCastExprToType(RHS.get(), LHSType, CK_NullToPointer);
     return computeResultTy();
   }
   if (!IsOrdered && LHSType->isNullPtrType() &&
       (RHSType->isObjCObjectPointerType() || RHSType->isBlockPointerType())) {
     LHS = ImpCastExprToType(LHS.get(), RHSType, CK_NullToPointer);
     return computeResultTy();
   }
 
   if (getLangOpts().CPlusPlus) {
     if (IsRelational &&
         ((LHSType->isNullPtrType() && RHSType->isPointerType()) ||
          (RHSType->isNullPtrType() && LHSType->isPointerType()))) {
       // HACK: Relational comparison of nullptr_t against a pointer type is
       // invalid per DR583, but we allow it within std::less<> and friends,
       // since otherwise common uses of it break.
       // FIXME: Consider removing this hack once LWG fixes std::less<> and
       // friends to have std::nullptr_t overload candidates.
       DeclContext *DC = CurContext;
       if (isa<FunctionDecl>(DC))
         DC = DC->getParent();
       if (auto *CTSD = dyn_cast<ClassTemplateSpecializationDecl>(DC)) {
         if (CTSD->isInStdNamespace() &&
             llvm::StringSwitch<bool>(CTSD->getName())
                 .Cases("less", "less_equal", "greater", "greater_equal", true)
                 .Default(false)) {
           if (RHSType->isNullPtrType())
             RHS = ImpCastExprToType(RHS.get(), LHSType, CK_NullToPointer);
           else
             LHS = ImpCastExprToType(LHS.get(), RHSType, CK_NullToPointer);
           return computeResultTy();
         }
       }
     }
 
     // C++ [expr.eq]p2:
     //   If at least one operand is a pointer to member, [...] bring them to
     //   their composite pointer type.
     if (!IsOrdered &&
         (LHSType->isMemberPointerType() || RHSType->isMemberPointerType())) {
       if (convertPointersToCompositeType(*this, Loc, LHS, RHS))
         return QualType();
       else
         return computeResultTy();
     }
   }
 
   // Handle block pointer types.
   if (!IsOrdered && LHSType->isBlockPointerType() &&
       RHSType->isBlockPointerType()) {
     QualType lpointee = LHSType->castAs<BlockPointerType>()->getPointeeType();
     QualType rpointee = RHSType->castAs<BlockPointerType>()->getPointeeType();
 
     if (!LHSIsNull && !RHSIsNull &&
         !Context.typesAreCompatible(lpointee, rpointee)) {
       Diag(Loc, diag::err_typecheck_comparison_of_distinct_blocks)
         << LHSType << RHSType << LHS.get()->getSourceRange()
         << RHS.get()->getSourceRange();
     }
     RHS = ImpCastExprToType(RHS.get(), LHSType, CK_BitCast);
     return computeResultTy();
   }
 
   // Allow block pointers to be compared with null pointer constants.
   if (!IsOrdered
       && ((LHSType->isBlockPointerType() && RHSType->isPointerType())
           || (LHSType->isPointerType() && RHSType->isBlockPointerType()))) {
     if (!LHSIsNull && !RHSIsNull) {
       if (!((RHSType->isPointerType() && RHSType->castAs<PointerType>()
              ->getPointeeType()->isVoidType())
             || (LHSType->isPointerType() && LHSType->castAs<PointerType>()
                 ->getPointeeType()->isVoidType())))
         Diag(Loc, diag::err_typecheck_comparison_of_distinct_blocks)
           << LHSType << RHSType << LHS.get()->getSourceRange()
           << RHS.get()->getSourceRange();
     }
     if (LHSIsNull && !RHSIsNull)
       LHS = ImpCastExprToType(LHS.get(), RHSType,
                               RHSType->isPointerType() ? CK_BitCast
                                 : CK_AnyPointerToBlockPointerCast);
     else
       RHS = ImpCastExprToType(RHS.get(), LHSType,
                               LHSType->isPointerType() ? CK_BitCast
                                 : CK_AnyPointerToBlockPointerCast);
     return computeResultTy();
   }
 
   if (LHSType->isObjCObjectPointerType() ||
       RHSType->isObjCObjectPointerType()) {
     const PointerType *LPT = LHSType->getAs<PointerType>();
     const PointerType *RPT = RHSType->getAs<PointerType>();
     if (LPT || RPT) {
       bool LPtrToVoid = LPT ? LPT->getPointeeType()->isVoidType() : false;
       bool RPtrToVoid = RPT ? RPT->getPointeeType()->isVoidType() : false;
 
       if (!LPtrToVoid && !RPtrToVoid &&
           !Context.typesAreCompatible(LHSType, RHSType)) {
         diagnoseDistinctPointerComparison(*this, Loc, LHS, RHS,
                                           /*isError*/false);
       }
       // FIXME: If LPtrToVoid, we should presumably convert the LHS rather than
       // the RHS, but we have test coverage for this behavior.
       // FIXME: Consider using convertPointersToCompositeType in C++.
       if (LHSIsNull && !RHSIsNull) {
         Expr *E = LHS.get();
         if (getLangOpts().ObjCAutoRefCount)
           CheckObjCConversion(SourceRange(), RHSType, E,
                               CCK_ImplicitConversion);
         LHS = ImpCastExprToType(E, RHSType,
                                 RPT ? CK_BitCast :CK_CPointerToObjCPointerCast);
       }
       else {
         Expr *E = RHS.get();
         if (getLangOpts().ObjCAutoRefCount)
           CheckObjCConversion(SourceRange(), LHSType, E, CCK_ImplicitConversion,
                               /*Diagnose=*/true,
                               /*DiagnoseCFAudited=*/false, Opc);
         RHS = ImpCastExprToType(E, LHSType,
                                 LPT ? CK_BitCast :CK_CPointerToObjCPointerCast);
       }
       return computeResultTy();
     }
     if (LHSType->isObjCObjectPointerType() &&
         RHSType->isObjCObjectPointerType()) {
       if (!Context.areComparableObjCPointerTypes(LHSType, RHSType))
         diagnoseDistinctPointerComparison(*this, Loc, LHS, RHS,
                                           /*isError*/false);
       if (isObjCObjectLiteral(LHS) || isObjCObjectLiteral(RHS))
         diagnoseObjCLiteralComparison(*this, Loc, LHS, RHS, Opc);
 
       if (LHSIsNull && !RHSIsNull)
         LHS = ImpCastExprToType(LHS.get(), RHSType, CK_BitCast);
       else
         RHS = ImpCastExprToType(RHS.get(), LHSType, CK_BitCast);
       return computeResultTy();
     }
 
     if (!IsOrdered && LHSType->isBlockPointerType() &&
         RHSType->isBlockCompatibleObjCPointerType(Context)) {
       LHS = ImpCastExprToType(LHS.get(), RHSType,
                               CK_BlockPointerToObjCPointerCast);
       return computeResultTy();
     } else if (!IsOrdered &&
                LHSType->isBlockCompatibleObjCPointerType(Context) &&
                RHSType->isBlockPointerType()) {
       RHS = ImpCastExprToType(RHS.get(), LHSType,
                               CK_BlockPointerToObjCPointerCast);
       return computeResultTy();
     }
   }
   if ((LHSType->isAnyPointerType() && RHSType->isIntegerType()) ||
       (LHSType->isIntegerType() && RHSType->isAnyPointerType())) {
     unsigned DiagID = 0;
     bool isError = false;
     if (LangOpts.DebuggerSupport) {
       // Under a debugger, allow the comparison of pointers to integers,
       // since users tend to want to compare addresses.
     } else if ((LHSIsNull && LHSType->isIntegerType()) ||
                (RHSIsNull && RHSType->isIntegerType())) {
       if (IsOrdered) {
         isError = getLangOpts().CPlusPlus;
         DiagID =
           isError ? diag::err_typecheck_ordered_comparison_of_pointer_and_zero
                   : diag::ext_typecheck_ordered_comparison_of_pointer_and_zero;
       }
     } else if (getLangOpts().CPlusPlus) {
       DiagID = diag::err_typecheck_comparison_of_pointer_integer;
       isError = true;
     } else if (IsOrdered)
       DiagID = diag::ext_typecheck_ordered_comparison_of_pointer_integer;
     else
       DiagID = diag::ext_typecheck_comparison_of_pointer_integer;
 
     if (DiagID) {
       Diag(Loc, DiagID)
         << LHSType << RHSType << LHS.get()->getSourceRange()
         << RHS.get()->getSourceRange();
       if (isError)
         return QualType();
     }
 
     if (LHSType->isIntegerType())
       LHS = ImpCastExprToType(LHS.get(), RHSType,
                         LHSIsNull ? CK_NullToPointer : CK_IntegralToPointer);
     else
       RHS = ImpCastExprToType(RHS.get(), LHSType,
                         RHSIsNull ? CK_NullToPointer : CK_IntegralToPointer);
     return computeResultTy();
   }
 
   // Handle block pointers.
   if (!IsOrdered && RHSIsNull
       && LHSType->isBlockPointerType() && RHSType->isIntegerType()) {
     RHS = ImpCastExprToType(RHS.get(), LHSType, CK_NullToPointer);
     return computeResultTy();
   }
   if (!IsOrdered && LHSIsNull
       && LHSType->isIntegerType() && RHSType->isBlockPointerType()) {
     LHS = ImpCastExprToType(LHS.get(), RHSType, CK_NullToPointer);
     return computeResultTy();
   }
 
   if (getLangOpts().getOpenCLCompatibleVersion() >= 200) {
     if (LHSType->isClkEventT() && RHSType->isClkEventT()) {
       return computeResultTy();
     }
 
     if (LHSType->isQueueT() && RHSType->isQueueT()) {
       return computeResultTy();
     }
 
     if (LHSIsNull && RHSType->isQueueT()) {
       LHS = ImpCastExprToType(LHS.get(), RHSType, CK_NullToPointer);
       return computeResultTy();
     }
 
     if (LHSType->isQueueT() && RHSIsNull) {
       RHS = ImpCastExprToType(RHS.get(), LHSType, CK_NullToPointer);
       return computeResultTy();
     }
   }
 
   return InvalidOperands(Loc, LHS, RHS);
 }
 
 // Return a signed ext_vector_type that is of identical size and number of
 // elements. For floating point vectors, return an integer type of identical
 // size and number of elements. In the non ext_vector_type case, search from
 // the largest type to the smallest type to avoid cases where long long == long,
 // where long gets picked over long long.
 QualType Sema::GetSignedVectorType(QualType V) {
   const VectorType *VTy = V->castAs<VectorType>();
   unsigned TypeSize = Context.getTypeSize(VTy->getElementType());
 
   if (isa<ExtVectorType>(VTy)) {
     if (VTy->isExtVectorBoolType())
       return Context.getExtVectorType(Context.BoolTy, VTy->getNumElements());
     if (TypeSize == Context.getTypeSize(Context.CharTy))
       return Context.getExtVectorType(Context.CharTy, VTy->getNumElements());
     if (TypeSize == Context.getTypeSize(Context.ShortTy))
       return Context.getExtVectorType(Context.ShortTy, VTy->getNumElements());
     if (TypeSize == Context.getTypeSize(Context.IntTy))
       return Context.getExtVectorType(Context.IntTy, VTy->getNumElements());
     if (TypeSize == Context.getTypeSize(Context.Int128Ty))
       return Context.getExtVectorType(Context.Int128Ty, VTy->getNumElements());
     if (TypeSize == Context.getTypeSize(Context.LongTy))
       return Context.getExtVectorType(Context.LongTy, VTy->getNumElements());
     assert(TypeSize == Context.getTypeSize(Context.LongLongTy) &&
            "Unhandled vector element size in vector compare");
     return Context.getExtVectorType(Context.LongLongTy, VTy->getNumElements());
   }
 
   if (TypeSize == Context.getTypeSize(Context.Int128Ty))
     return Context.getVectorType(Context.Int128Ty, VTy->getNumElements(),
                                  VectorType::GenericVector);
   if (TypeSize == Context.getTypeSize(Context.LongLongTy))
     return Context.getVectorType(Context.LongLongTy, VTy->getNumElements(),
                                  VectorType::GenericVector);
   if (TypeSize == Context.getTypeSize(Context.LongTy))
     return Context.getVectorType(Context.LongTy, VTy->getNumElements(),
                                  VectorType::GenericVector);
   if (TypeSize == Context.getTypeSize(Context.IntTy))
     return Context.getVectorType(Context.IntTy, VTy->getNumElements(),
                                  VectorType::GenericVector);
   if (TypeSize == Context.getTypeSize(Context.ShortTy))
     return Context.getVectorType(Context.ShortTy, VTy->getNumElements(),
                                  VectorType::GenericVector);
   assert(TypeSize == Context.getTypeSize(Context.CharTy) &&
          "Unhandled vector element size in vector compare");
   return Context.getVectorType(Context.CharTy, VTy->getNumElements(),
                                VectorType::GenericVector);
 }
 
 QualType Sema::GetSignedSizelessVectorType(QualType V) {
   const BuiltinType *VTy = V->castAs<BuiltinType>();
   assert(VTy->isSizelessBuiltinType() && "expected sizeless type");
 
   const QualType ETy = V->getSveEltType(Context);
   const auto TypeSize = Context.getTypeSize(ETy);
 
   const QualType IntTy = Context.getIntTypeForBitwidth(TypeSize, true);
   const llvm::ElementCount VecSize = Context.getBuiltinVectorTypeInfo(VTy).EC;
   return Context.getScalableVectorType(IntTy, VecSize.getKnownMinValue());
 }
 
 /// CheckVectorCompareOperands - vector comparisons are a clang extension that
 /// operates on extended vector types.  Instead of producing an IntTy result,
 /// like a scalar comparison, a vector comparison produces a vector of integer
 /// types.
 QualType Sema::CheckVectorCompareOperands(ExprResult &LHS, ExprResult &RHS,
                                           SourceLocation Loc,
                                           BinaryOperatorKind Opc) {
   if (Opc == BO_Cmp) {
     Diag(Loc, diag::err_three_way_vector_comparison);
     return QualType();
   }
 
   // Check to make sure we're operating on vectors of the same type and width,
   // Allowing one side to be a scalar of element type.
   QualType vType =
       CheckVectorOperands(LHS, RHS, Loc, /*isCompAssign*/ false,
                           /*AllowBothBool*/ true,
                           /*AllowBoolConversions*/ getLangOpts().ZVector,
                           /*AllowBooleanOperation*/ true,
                           /*ReportInvalid*/ true);
   if (vType.isNull())
     return vType;
 
   QualType LHSType = LHS.get()->getType();
 
   // Determine the return type of a vector compare. By default clang will return
   // a scalar for all vector compares except vector bool and vector pixel.
   // With the gcc compiler we will always return a vector type and with the xl
   // compiler we will always return a scalar type. This switch allows choosing
   // which behavior is prefered.
   if (getLangOpts().AltiVec) {
     switch (getLangOpts().getAltivecSrcCompat()) {
     case LangOptions::AltivecSrcCompatKind::Mixed:
       // If AltiVec, the comparison results in a numeric type, i.e.
       // bool for C++, int for C
       if (vType->castAs<VectorType>()->getVectorKind() ==
           VectorType::AltiVecVector)
         return Context.getLogicalOperationType();
       else
         Diag(Loc, diag::warn_deprecated_altivec_src_compat);
       break;
     case LangOptions::AltivecSrcCompatKind::GCC:
       // For GCC we always return the vector type.
       break;
     case LangOptions::AltivecSrcCompatKind::XL:
       return Context.getLogicalOperationType();
       break;
     }
   }
 
   // For non-floating point types, check for self-comparisons of the form
   // x == x, x != x, x < x, etc.  These always evaluate to a constant, and
   // often indicate logic errors in the program.
   diagnoseTautologicalComparison(*this, Loc, LHS.get(), RHS.get(), Opc);
 
   // Check for comparisons of floating point operands using != and ==.
   if (LHSType->hasFloatingRepresentation()) {
     assert(RHS.get()->getType()->hasFloatingRepresentation());
     CheckFloatComparison(Loc, LHS.get(), RHS.get(), Opc);
   }
 
   // Return a signed type for the vector.
   return GetSignedVectorType(vType);
 }
 
 QualType Sema::CheckSizelessVectorCompareOperands(ExprResult &LHS,
                                                   ExprResult &RHS,
                                                   SourceLocation Loc,
                                                   BinaryOperatorKind Opc) {
   if (Opc == BO_Cmp) {
     Diag(Loc, diag::err_three_way_vector_comparison);
     return QualType();
   }
 
   // Check to make sure we're operating on vectors of the same type and width,
   // Allowing one side to be a scalar of element type.
   QualType vType = CheckSizelessVectorOperands(
       LHS, RHS, Loc, /*isCompAssign*/ false, ACK_Comparison);
 
   if (vType.isNull())
     return vType;
 
   QualType LHSType = LHS.get()->getType();
 
   // For non-floating point types, check for self-comparisons of the form
   // x == x, x != x, x < x, etc.  These always evaluate to a constant, and
   // often indicate logic errors in the program.
   diagnoseTautologicalComparison(*this, Loc, LHS.get(), RHS.get(), Opc);
 
   // Check for comparisons of floating point operands using != and ==.
   if (LHSType->hasFloatingRepresentation()) {
     assert(RHS.get()->getType()->hasFloatingRepresentation());
     CheckFloatComparison(Loc, LHS.get(), RHS.get(), Opc);
   }
 
   const BuiltinType *LHSBuiltinTy = LHSType->getAs<BuiltinType>();
   const BuiltinType *RHSBuiltinTy = RHS.get()->getType()->getAs<BuiltinType>();
 
   if (LHSBuiltinTy && RHSBuiltinTy && LHSBuiltinTy->isSVEBool() &&
       RHSBuiltinTy->isSVEBool())
     return LHSType;
 
   // Return a signed type for the vector.
   return GetSignedSizelessVectorType(vType);
 }
 
 static void diagnoseXorMisusedAsPow(Sema &S, const ExprResult &XorLHS,
                                     const ExprResult &XorRHS,
                                     const SourceLocation Loc) {
   // Do not diagnose macros.
   if (Loc.isMacroID())
     return;
 
   // Do not diagnose if both LHS and RHS are macros.
   if (XorLHS.get()->getExprLoc().isMacroID() &&
       XorRHS.get()->getExprLoc().isMacroID())
     return;
 
   bool Negative = false;
   bool ExplicitPlus = false;
   const auto *LHSInt = dyn_cast<IntegerLiteral>(XorLHS.get());
   const auto *RHSInt = dyn_cast<IntegerLiteral>(XorRHS.get());
 
   if (!LHSInt)
     return;
   if (!RHSInt) {
     // Check negative literals.
     if (const auto *UO = dyn_cast<UnaryOperator>(XorRHS.get())) {
       UnaryOperatorKind Opc = UO->getOpcode();
       if (Opc != UO_Minus && Opc != UO_Plus)
         return;
       RHSInt = dyn_cast<IntegerLiteral>(UO->getSubExpr());
       if (!RHSInt)
         return;
       Negative = (Opc == UO_Minus);
       ExplicitPlus = !Negative;
     } else {
       return;
     }
   }
 
   const llvm::APInt &LeftSideValue = LHSInt->getValue();
   llvm::APInt RightSideValue = RHSInt->getValue();
   if (LeftSideValue != 2 && LeftSideValue != 10)
     return;
 
   if (LeftSideValue.getBitWidth() != RightSideValue.getBitWidth())
     return;
 
   CharSourceRange ExprRange = CharSourceRange::getCharRange(
       LHSInt->getBeginLoc(), S.getLocForEndOfToken(RHSInt->getLocation()));
   llvm::StringRef ExprStr =
       Lexer::getSourceText(ExprRange, S.getSourceManager(), S.getLangOpts());
 
   CharSourceRange XorRange =
       CharSourceRange::getCharRange(Loc, S.getLocForEndOfToken(Loc));
   llvm::StringRef XorStr =
       Lexer::getSourceText(XorRange, S.getSourceManager(), S.getLangOpts());
   // Do not diagnose if xor keyword/macro is used.
   if (XorStr == "xor")
     return;
 
   std::string LHSStr = std::string(Lexer::getSourceText(
       CharSourceRange::getTokenRange(LHSInt->getSourceRange()),
       S.getSourceManager(), S.getLangOpts()));
   std::string RHSStr = std::string(Lexer::getSourceText(
       CharSourceRange::getTokenRange(RHSInt->getSourceRange()),
       S.getSourceManager(), S.getLangOpts()));
 
   if (Negative) {
     RightSideValue = -RightSideValue;
     RHSStr = "-" + RHSStr;
   } else if (ExplicitPlus) {
     RHSStr = "+" + RHSStr;
   }
 
   StringRef LHSStrRef = LHSStr;
   StringRef RHSStrRef = RHSStr;
   // Do not diagnose literals with digit separators, binary, hexadecimal, octal
   // literals.
   if (LHSStrRef.startswith("0b") || LHSStrRef.startswith("0B") ||
       RHSStrRef.startswith("0b") || RHSStrRef.startswith("0B") ||
       LHSStrRef.startswith("0x") || LHSStrRef.startswith("0X") ||
       RHSStrRef.startswith("0x") || RHSStrRef.startswith("0X") ||
       (LHSStrRef.size() > 1 && LHSStrRef.startswith("0")) ||
       (RHSStrRef.size() > 1 && RHSStrRef.startswith("0")) ||
       LHSStrRef.contains('\'') || RHSStrRef.contains('\''))
     return;
 
   bool SuggestXor =
       S.getLangOpts().CPlusPlus || S.getPreprocessor().isMacroDefined("xor");
   const llvm::APInt XorValue = LeftSideValue ^ RightSideValue;
   int64_t RightSideIntValue = RightSideValue.getSExtValue();
   if (LeftSideValue == 2 && RightSideIntValue >= 0) {
     std::string SuggestedExpr = "1 << " + RHSStr;
     bool Overflow = false;
     llvm::APInt One = (LeftSideValue - 1);
     llvm::APInt PowValue = One.sshl_ov(RightSideValue, Overflow);
     if (Overflow) {
       if (RightSideIntValue < 64)
         S.Diag(Loc, diag::warn_xor_used_as_pow_base)
             << ExprStr << toString(XorValue, 10, true) << ("1LL << " + RHSStr)
             << FixItHint::CreateReplacement(ExprRange, "1LL << " + RHSStr);
       else if (RightSideIntValue == 64)
         S.Diag(Loc, diag::warn_xor_used_as_pow)
             << ExprStr << toString(XorValue, 10, true);
       else
         return;
     } else {
       S.Diag(Loc, diag::warn_xor_used_as_pow_base_extra)
           << ExprStr << toString(XorValue, 10, true) << SuggestedExpr
           << toString(PowValue, 10, true)
           << FixItHint::CreateReplacement(
                  ExprRange, (RightSideIntValue == 0) ? "1" : SuggestedExpr);
     }
 
     S.Diag(Loc, diag::note_xor_used_as_pow_silence)
         << ("0x2 ^ " + RHSStr) << SuggestXor;
   } else if (LeftSideValue == 10) {
     std::string SuggestedValue = "1e" + std::to_string(RightSideIntValue);
     S.Diag(Loc, diag::warn_xor_used_as_pow_base)
         << ExprStr << toString(XorValue, 10, true) << SuggestedValue
         << FixItHint::CreateReplacement(ExprRange, SuggestedValue);
     S.Diag(Loc, diag::note_xor_used_as_pow_silence)
         << ("0xA ^ " + RHSStr) << SuggestXor;
   }
 }
 
 QualType Sema::CheckVectorLogicalOperands(ExprResult &LHS, ExprResult &RHS,
                                           SourceLocation Loc) {
   // Ensure that either both operands are of the same vector type, or
   // one operand is of a vector type and the other is of its element type.
   QualType vType = CheckVectorOperands(LHS, RHS, Loc, false,
                                        /*AllowBothBool*/ true,
                                        /*AllowBoolConversions*/ false,
                                        /*AllowBooleanOperation*/ false,
                                        /*ReportInvalid*/ false);
   if (vType.isNull())
     return InvalidOperands(Loc, LHS, RHS);
   if (getLangOpts().OpenCL &&
       getLangOpts().getOpenCLCompatibleVersion() < 120 &&
       vType->hasFloatingRepresentation())
     return InvalidOperands(Loc, LHS, RHS);
   // FIXME: The check for C++ here is for GCC compatibility. GCC rejects the
   //        usage of the logical operators && and || with vectors in C. This
   //        check could be notionally dropped.
   if (!getLangOpts().CPlusPlus &&
       !(isa<ExtVectorType>(vType->getAs<VectorType>())))
     return InvalidLogicalVectorOperands(Loc, LHS, RHS);
 
   return GetSignedVectorType(LHS.get()->getType());
 }
 
 QualType Sema::CheckMatrixElementwiseOperands(ExprResult &LHS, ExprResult &RHS,
                                               SourceLocation Loc,
                                               bool IsCompAssign) {
   if (!IsCompAssign) {
     LHS = DefaultFunctionArrayLvalueConversion(LHS.get());
     if (LHS.isInvalid())
       return QualType();
   }
   RHS = DefaultFunctionArrayLvalueConversion(RHS.get());
   if (RHS.isInvalid())
     return QualType();
 
   // For conversion purposes, we ignore any qualifiers.
   // For example, "const float" and "float" are equivalent.
   QualType LHSType = LHS.get()->getType().getUnqualifiedType();
   QualType RHSType = RHS.get()->getType().getUnqualifiedType();
 
   const MatrixType *LHSMatType = LHSType->getAs<MatrixType>();
   const MatrixType *RHSMatType = RHSType->getAs<MatrixType>();
   assert((LHSMatType || RHSMatType) && "At least one operand must be a matrix");
 
   if (Context.hasSameType(LHSType, RHSType))
     return Context.getCommonSugaredType(LHSType, RHSType);
 
   // Type conversion may change LHS/RHS. Keep copies to the original results, in
   // case we have to return InvalidOperands.
   ExprResult OriginalLHS = LHS;
   ExprResult OriginalRHS = RHS;
   if (LHSMatType && !RHSMatType) {
     RHS = tryConvertExprToType(RHS.get(), LHSMatType->getElementType());
     if (!RHS.isInvalid())
       return LHSType;
 
     return InvalidOperands(Loc, OriginalLHS, OriginalRHS);
   }
 
   if (!LHSMatType && RHSMatType) {
     LHS = tryConvertExprToType(LHS.get(), RHSMatType->getElementType());
     if (!LHS.isInvalid())
       return RHSType;
     return InvalidOperands(Loc, OriginalLHS, OriginalRHS);
   }
 
   return InvalidOperands(Loc, LHS, RHS);
 }
 
 QualType Sema::CheckMatrixMultiplyOperands(ExprResult &LHS, ExprResult &RHS,
                                            SourceLocation Loc,
                                            bool IsCompAssign) {
   if (!IsCompAssign) {
     LHS = DefaultFunctionArrayLvalueConversion(LHS.get());
     if (LHS.isInvalid())
       return QualType();
   }
   RHS = DefaultFunctionArrayLvalueConversion(RHS.get());
   if (RHS.isInvalid())
     return QualType();
 
   auto *LHSMatType = LHS.get()->getType()->getAs<ConstantMatrixType>();
   auto *RHSMatType = RHS.get()->getType()->getAs<ConstantMatrixType>();
   assert((LHSMatType || RHSMatType) && "At least one operand must be a matrix");
 
   if (LHSMatType && RHSMatType) {
     if (LHSMatType->getNumColumns() != RHSMatType->getNumRows())
       return InvalidOperands(Loc, LHS, RHS);
 
     if (Context.hasSameType(LHSMatType, RHSMatType))
       return Context.getCommonSugaredType(
           LHS.get()->getType().getUnqualifiedType(),
           RHS.get()->getType().getUnqualifiedType());
 
     QualType LHSELTy = LHSMatType->getElementType(),
              RHSELTy = RHSMatType->getElementType();
     if (!Context.hasSameType(LHSELTy, RHSELTy))
       return InvalidOperands(Loc, LHS, RHS);
 
     return Context.getConstantMatrixType(
         Context.getCommonSugaredType(LHSELTy, RHSELTy),
         LHSMatType->getNumRows(), RHSMatType->getNumColumns());
   }
   return CheckMatrixElementwiseOperands(LHS, RHS, Loc, IsCompAssign);
 }
 
 static bool isLegalBoolVectorBinaryOp(BinaryOperatorKind Opc) {
   switch (Opc) {
   default:
     return false;
   case BO_And:
   case BO_AndAssign:
   case BO_Or:
   case BO_OrAssign:
   case BO_Xor:
   case BO_XorAssign:
     return true;
   }
 }
 
 inline QualType Sema::CheckBitwiseOperands(ExprResult &LHS, ExprResult &RHS,
                                            SourceLocation Loc,
                                            BinaryOperatorKind Opc) {
   checkArithmeticNull(*this, LHS, RHS, Loc, /*IsCompare=*/false);
 
   bool IsCompAssign =
       Opc == BO_AndAssign || Opc == BO_OrAssign || Opc == BO_XorAssign;
 
   bool LegalBoolVecOperator = isLegalBoolVectorBinaryOp(Opc);
 
   if (LHS.get()->getType()->isVectorType() ||
       RHS.get()->getType()->isVectorType()) {
     if (LHS.get()->getType()->hasIntegerRepresentation() &&
         RHS.get()->getType()->hasIntegerRepresentation())
       return CheckVectorOperands(LHS, RHS, Loc, IsCompAssign,
                                  /*AllowBothBool*/ true,
                                  /*AllowBoolConversions*/ getLangOpts().ZVector,
                                  /*AllowBooleanOperation*/ LegalBoolVecOperator,
                                  /*ReportInvalid*/ true);
     return InvalidOperands(Loc, LHS, RHS);
   }
 
   if (LHS.get()->getType()->isVLSTBuiltinType() ||
       RHS.get()->getType()->isVLSTBuiltinType()) {
     if (LHS.get()->getType()->hasIntegerRepresentation() &&
         RHS.get()->getType()->hasIntegerRepresentation())
       return CheckSizelessVectorOperands(LHS, RHS, Loc, IsCompAssign,
                                          ACK_BitwiseOp);
     return InvalidOperands(Loc, LHS, RHS);
   }
 
   if (LHS.get()->getType()->isVLSTBuiltinType() ||
       RHS.get()->getType()->isVLSTBuiltinType()) {
     if (LHS.get()->getType()->hasIntegerRepresentation() &&
         RHS.get()->getType()->hasIntegerRepresentation())
       return CheckSizelessVectorOperands(LHS, RHS, Loc, IsCompAssign,
                                          ACK_BitwiseOp);
     return InvalidOperands(Loc, LHS, RHS);
   }
 
   if (Opc == BO_And)
     diagnoseLogicalNotOnLHSofCheck(*this, LHS, RHS, Loc, Opc);
 
   if (LHS.get()->getType()->hasFloatingRepresentation() ||
       RHS.get()->getType()->hasFloatingRepresentation())
     return InvalidOperands(Loc, LHS, RHS);
 
   ExprResult LHSResult = LHS, RHSResult = RHS;
   QualType compType = UsualArithmeticConversions(
       LHSResult, RHSResult, Loc, IsCompAssign ? ACK_CompAssign : ACK_BitwiseOp);
   if (LHSResult.isInvalid() || RHSResult.isInvalid())
     return QualType();
   LHS = LHSResult.get();
   RHS = RHSResult.get();
 
   if (Opc == BO_Xor)
     diagnoseXorMisusedAsPow(*this, LHS, RHS, Loc);
 
   if (!compType.isNull() && compType->isIntegralOrUnscopedEnumerationType())
     return compType;
   return InvalidOperands(Loc, LHS, RHS);
 }
 
 // C99 6.5.[13,14]
 inline QualType Sema::CheckLogicalOperands(ExprResult &LHS, ExprResult &RHS,
                                            SourceLocation Loc,
                                            BinaryOperatorKind Opc) {
   // Check vector operands differently.
   if (LHS.get()->getType()->isVectorType() ||
       RHS.get()->getType()->isVectorType())
     return CheckVectorLogicalOperands(LHS, RHS, Loc);
 
   bool EnumConstantInBoolContext = false;
   for (const ExprResult &HS : {LHS, RHS}) {
     if (const auto *DREHS = dyn_cast<DeclRefExpr>(HS.get())) {
       const auto *ECDHS = dyn_cast<EnumConstantDecl>(DREHS->getDecl());
       if (ECDHS && ECDHS->getInitVal() != 0 && ECDHS->getInitVal() != 1)
         EnumConstantInBoolContext = true;
     }
   }
 
   if (EnumConstantInBoolContext)
     Diag(Loc, diag::warn_enum_constant_in_bool_context);
 
   // WebAssembly tables can't be used with logical operators.
   QualType LHSTy = LHS.get()->getType();
   QualType RHSTy = RHS.get()->getType();
   const auto *LHSATy = dyn_cast<ArrayType>(LHSTy);
   const auto *RHSATy = dyn_cast<ArrayType>(RHSTy);
   if ((LHSATy && LHSATy->getElementType().isWebAssemblyReferenceType()) ||
       (RHSATy && RHSATy->getElementType().isWebAssemblyReferenceType())) {
     return InvalidOperands(Loc, LHS, RHS);
   }
 
   // Diagnose cases where the user write a logical and/or but probably meant a
   // bitwise one.  We do this when the LHS is a non-bool integer and the RHS
   // is a constant.
   if (!EnumConstantInBoolContext && LHS.get()->getType()->isIntegerType() &&
       !LHS.get()->getType()->isBooleanType() &&
       RHS.get()->getType()->isIntegerType() && !RHS.get()->isValueDependent() &&
       // Don't warn in macros or template instantiations.
       !Loc.isMacroID() && !inTemplateInstantiation()) {
     // If the RHS can be constant folded, and if it constant folds to something
     // that isn't 0 or 1 (which indicate a potential logical operation that
     // happened to fold to true/false) then warn.
     // Parens on the RHS are ignored.
     Expr::EvalResult EVResult;
     if (RHS.get()->EvaluateAsInt(EVResult, Context)) {
       llvm::APSInt Result = EVResult.Val.getInt();
       if ((getLangOpts().Bool && !RHS.get()->getType()->isBooleanType() &&
            !RHS.get()->getExprLoc().isMacroID()) ||
           (Result != 0 && Result != 1)) {
         Diag(Loc, diag::warn_logical_instead_of_bitwise)
             << RHS.get()->getSourceRange() << (Opc == BO_LAnd ? "&&" : "||");
         // Suggest replacing the logical operator with the bitwise version
         Diag(Loc, diag::note_logical_instead_of_bitwise_change_operator)
             << (Opc == BO_LAnd ? "&" : "|")
             << FixItHint::CreateReplacement(
                    SourceRange(Loc, getLocForEndOfToken(Loc)),
                    Opc == BO_LAnd ? "&" : "|");
         if (Opc == BO_LAnd)
           // Suggest replacing "Foo() && kNonZero" with "Foo()"
           Diag(Loc, diag::note_logical_instead_of_bitwise_remove_constant)
               << FixItHint::CreateRemoval(
                      SourceRange(getLocForEndOfToken(LHS.get()->getEndLoc()),
                                  RHS.get()->getEndLoc()));
       }
     }
   }
 
   if (!Context.getLangOpts().CPlusPlus) {
     // OpenCL v1.1 s6.3.g: The logical operators and (&&), or (||) do
     // not operate on the built-in scalar and vector float types.
     if (Context.getLangOpts().OpenCL &&
         Context.getLangOpts().OpenCLVersion < 120) {
       if (LHS.get()->getType()->isFloatingType() ||
           RHS.get()->getType()->isFloatingType())
         return InvalidOperands(Loc, LHS, RHS);
     }
 
     LHS = UsualUnaryConversions(LHS.get());
     if (LHS.isInvalid())
       return QualType();
 
     RHS = UsualUnaryConversions(RHS.get());
     if (RHS.isInvalid())
       return QualType();
 
     if (!LHS.get()->getType()->isScalarType() ||
         !RHS.get()->getType()->isScalarType())
       return InvalidOperands(Loc, LHS, RHS);
 
     return Context.IntTy;
   }
 
   // The following is safe because we only use this method for
   // non-overloadable operands.
 
   // C++ [expr.log.and]p1
   // C++ [expr.log.or]p1
   // The operands are both contextually converted to type bool.
   ExprResult LHSRes = PerformContextuallyConvertToBool(LHS.get());
   if (LHSRes.isInvalid())
     return InvalidOperands(Loc, LHS, RHS);
   LHS = LHSRes;
 
   ExprResult RHSRes = PerformContextuallyConvertToBool(RHS.get());
   if (RHSRes.isInvalid())
     return InvalidOperands(Loc, LHS, RHS);
   RHS = RHSRes;
 
   // C++ [expr.log.and]p2
   // C++ [expr.log.or]p2
   // The result is a bool.
   return Context.BoolTy;
 }
 
 static bool IsReadonlyMessage(Expr *E, Sema &S) {
   const MemberExpr *ME = dyn_cast<MemberExpr>(E);
   if (!ME) return false;
   if (!isa<FieldDecl>(ME->getMemberDecl())) return false;
   ObjCMessageExpr *Base = dyn_cast<ObjCMessageExpr>(
       ME->getBase()->IgnoreImplicit()->IgnoreParenImpCasts());
   if (!Base) return false;
   return Base->getMethodDecl() != nullptr;
 }
 
 /// Is the given expression (which must be 'const') a reference to a
 /// variable which was originally non-const, but which has become
 /// 'const' due to being captured within a block?
 enum NonConstCaptureKind { NCCK_None, NCCK_Block, NCCK_Lambda };
 static NonConstCaptureKind isReferenceToNonConstCapture(Sema &S, Expr *E) {
   assert(E->isLValue() && E->getType().isConstQualified());
   E = E->IgnoreParens();
 
   // Must be a reference to a declaration from an enclosing scope.
   DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E);
   if (!DRE) return NCCK_None;
   if (!DRE->refersToEnclosingVariableOrCapture()) return NCCK_None;
 
   // The declaration must be a variable which is not declared 'const'.
   VarDecl *var = dyn_cast<VarDecl>(DRE->getDecl());
   if (!var) return NCCK_None;
   if (var->getType().isConstQualified()) return NCCK_None;
   assert(var->hasLocalStorage() && "capture added 'const' to non-local?");
 
   // Decide whether the first capture was for a block or a lambda.
   DeclContext *DC = S.CurContext, *Prev = nullptr;
   // Decide whether the first capture was for a block or a lambda.
   while (DC) {
     // For init-capture, it is possible that the variable belongs to the
     // template pattern of the current context.
     if (auto *FD = dyn_cast<FunctionDecl>(DC))
       if (var->isInitCapture() &&
           FD->getTemplateInstantiationPattern() == var->getDeclContext())
         break;
     if (DC == var->getDeclContext())
       break;
     Prev = DC;
     DC = DC->getParent();
   }
   // Unless we have an init-capture, we've gone one step too far.
   if (!var->isInitCapture())
     DC = Prev;
   return (isa<BlockDecl>(DC) ? NCCK_Block : NCCK_Lambda);
 }
 
 static bool IsTypeModifiable(QualType Ty, bool IsDereference) {
   Ty = Ty.getNonReferenceType();
   if (IsDereference && Ty->isPointerType())
     Ty = Ty->getPointeeType();
   return !Ty.isConstQualified();
 }
 
 // Update err_typecheck_assign_const and note_typecheck_assign_const
 // when this enum is changed.
 enum {
   ConstFunction,
   ConstVariable,
   ConstMember,
   ConstMethod,
   NestedConstMember,
   ConstUnknown,  // Keep as last element
 };
 
 /// Emit the "read-only variable not assignable" error and print notes to give
 /// more information about why the variable is not assignable, such as pointing
 /// to the declaration of a const variable, showing that a method is const, or
 /// that the function is returning a const reference.
 static void DiagnoseConstAssignment(Sema &S, const Expr *E,
                                     SourceLocation Loc) {
   SourceRange ExprRange = E->getSourceRange();
 
   // Only emit one error on the first const found.  All other consts will emit
   // a note to the error.
   bool DiagnosticEmitted = false;
 
   // Track if the current expression is the result of a dereference, and if the
   // next checked expression is the result of a dereference.
   bool IsDereference = false;
   bool NextIsDereference = false;
 
   // Loop to process MemberExpr chains.
   while (true) {
     IsDereference = NextIsDereference;
 
     E = E->IgnoreImplicit()->IgnoreParenImpCasts();
     if (const MemberExpr *ME = dyn_cast<MemberExpr>(E)) {
       NextIsDereference = ME->isArrow();
       const ValueDecl *VD = ME->getMemberDecl();
       if (const FieldDecl *Field = dyn_cast<FieldDecl>(VD)) {
         // Mutable fields can be modified even if the class is const.
         if (Field->isMutable()) {
           assert(DiagnosticEmitted && "Expected diagnostic not emitted.");
           break;
         }
 
         if (!IsTypeModifiable(Field->getType(), IsDereference)) {
           if (!DiagnosticEmitted) {
             S.Diag(Loc, diag::err_typecheck_assign_const)
                 << ExprRange << ConstMember << false /*static*/ << Field
                 << Field->getType();
             DiagnosticEmitted = true;
           }
           S.Diag(VD->getLocation(), diag::note_typecheck_assign_const)
               << ConstMember << false /*static*/ << Field << Field->getType()
               << Field->getSourceRange();
         }
         E = ME->getBase();
         continue;
       } else if (const VarDecl *VDecl = dyn_cast<VarDecl>(VD)) {
         if (VDecl->getType().isConstQualified()) {
           if (!DiagnosticEmitted) {
             S.Diag(Loc, diag::err_typecheck_assign_const)
                 << ExprRange << ConstMember << true /*static*/ << VDecl
                 << VDecl->getType();
             DiagnosticEmitted = true;
           }
           S.Diag(VD->getLocation(), diag::note_typecheck_assign_const)
               << ConstMember << true /*static*/ << VDecl << VDecl->getType()
               << VDecl->getSourceRange();
         }
         // Static fields do not inherit constness from parents.
         break;
       }
       break; // End MemberExpr
     } else if (const ArraySubscriptExpr *ASE =
                    dyn_cast<ArraySubscriptExpr>(E)) {
       E = ASE->getBase()->IgnoreParenImpCasts();
       continue;
     } else if (const ExtVectorElementExpr *EVE =
                    dyn_cast<ExtVectorElementExpr>(E)) {
       E = EVE->getBase()->IgnoreParenImpCasts();
       continue;
     }
     break;
   }
 
   if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
     // Function calls
     const FunctionDecl *FD = CE->getDirectCallee();
     if (FD && !IsTypeModifiable(FD->getReturnType(), IsDereference)) {
       if (!DiagnosticEmitted) {
         S.Diag(Loc, diag::err_typecheck_assign_const) << ExprRange
                                                       << ConstFunction << FD;
         DiagnosticEmitted = true;
       }
       S.Diag(FD->getReturnTypeSourceRange().getBegin(),
              diag::note_typecheck_assign_const)
           << ConstFunction << FD << FD->getReturnType()
           << FD->getReturnTypeSourceRange();
     }
   } else if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
     // Point to variable declaration.
     if (const ValueDecl *VD = DRE->getDecl()) {
       if (!IsTypeModifiable(VD->getType(), IsDereference)) {
         if (!DiagnosticEmitted) {
           S.Diag(Loc, diag::err_typecheck_assign_const)
               << ExprRange << ConstVariable << VD << VD->getType();
           DiagnosticEmitted = true;
         }
         S.Diag(VD->getLocation(), diag::note_typecheck_assign_const)
             << ConstVariable << VD << VD->getType() << VD->getSourceRange();
       }
     }
   } else if (isa<CXXThisExpr>(E)) {
     if (const DeclContext *DC = S.getFunctionLevelDeclContext()) {
       if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(DC)) {
         if (MD->isConst()) {
           if (!DiagnosticEmitted) {
             S.Diag(Loc, diag::err_typecheck_assign_const) << ExprRange
                                                           << ConstMethod << MD;
             DiagnosticEmitted = true;
           }
           S.Diag(MD->getLocation(), diag::note_typecheck_assign_const)
               << ConstMethod << MD << MD->getSourceRange();
         }
       }
     }
   }
 
   if (DiagnosticEmitted)
     return;
 
   // Can't determine a more specific message, so display the generic error.
   S.Diag(Loc, diag::err_typecheck_assign_const) << ExprRange << ConstUnknown;
 }
 
 enum OriginalExprKind {
   OEK_Variable,
   OEK_Member,
   OEK_LValue
 };
 
 static void DiagnoseRecursiveConstFields(Sema &S, const ValueDecl *VD,
                                          const RecordType *Ty,
                                          SourceLocation Loc, SourceRange Range,
                                          OriginalExprKind OEK,
                                          bool &DiagnosticEmitted) {
   std::vector<const RecordType *> RecordTypeList;
   RecordTypeList.push_back(Ty);
   unsigned NextToCheckIndex = 0;
   // We walk the record hierarchy breadth-first to ensure that we print
   // diagnostics in field nesting order.
   while (RecordTypeList.size() > NextToCheckIndex) {
     bool IsNested = NextToCheckIndex > 0;
     for (const FieldDecl *Field :
          RecordTypeList[NextToCheckIndex]->getDecl()->fields()) {
       // First, check every field for constness.
       QualType FieldTy = Field->getType();
       if (FieldTy.isConstQualified()) {
         if (!DiagnosticEmitted) {
           S.Diag(Loc, diag::err_typecheck_assign_const)
               << Range << NestedConstMember << OEK << VD
               << IsNested << Field;
           DiagnosticEmitted = true;
         }
         S.Diag(Field->getLocation(), diag::note_typecheck_assign_const)
             << NestedConstMember << IsNested << Field
             << FieldTy << Field->getSourceRange();
       }
 
       // Then we append it to the list to check next in order.
       FieldTy = FieldTy.getCanonicalType();
       if (const auto *FieldRecTy = FieldTy->getAs<RecordType>()) {
         if (!llvm::is_contained(RecordTypeList, FieldRecTy))
           RecordTypeList.push_back(FieldRecTy);
       }
     }
     ++NextToCheckIndex;
   }
 }
 
 /// Emit an error for the case where a record we are trying to assign to has a
 /// const-qualified field somewhere in its hierarchy.
 static void DiagnoseRecursiveConstFields(Sema &S, const Expr *E,
                                          SourceLocation Loc) {
   QualType Ty = E->getType();
   assert(Ty->isRecordType() && "lvalue was not record?");
   SourceRange Range = E->getSourceRange();
   const RecordType *RTy = Ty.getCanonicalType()->getAs<RecordType>();
   bool DiagEmitted = false;
 
   if (const MemberExpr *ME = dyn_cast<MemberExpr>(E))
     DiagnoseRecursiveConstFields(S, ME->getMemberDecl(), RTy, Loc,
             Range, OEK_Member, DiagEmitted);
   else if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
     DiagnoseRecursiveConstFields(S, DRE->getDecl(), RTy, Loc,
             Range, OEK_Variable, DiagEmitted);
   else
     DiagnoseRecursiveConstFields(S, nullptr, RTy, Loc,
             Range, OEK_LValue, DiagEmitted);
   if (!DiagEmitted)
     DiagnoseConstAssignment(S, E, Loc);
 }
 
 /// CheckForModifiableLvalue - Verify that E is a modifiable lvalue.  If not,
 /// emit an error and return true.  If so, return false.
 static bool CheckForModifiableLvalue(Expr *E, SourceLocation Loc, Sema &S) {
   assert(!E->hasPlaceholderType(BuiltinType::PseudoObject));
 
   S.CheckShadowingDeclModification(E, Loc);
 
   SourceLocation OrigLoc = Loc;
   Expr::isModifiableLvalueResult IsLV = E->isModifiableLvalue(S.Context,
                                                               &Loc);
   if (IsLV == Expr::MLV_ClassTemporary && IsReadonlyMessage(E, S))
     IsLV = Expr::MLV_InvalidMessageExpression;
   if (IsLV == Expr::MLV_Valid)
     return false;
 
   unsigned DiagID = 0;
   bool NeedType = false;
   switch (IsLV) { // C99 6.5.16p2
   case Expr::MLV_ConstQualified:
     // Use a specialized diagnostic when we're assigning to an object
     // from an enclosing function or block.
     if (NonConstCaptureKind NCCK = isReferenceToNonConstCapture(S, E)) {
       if (NCCK == NCCK_Block)
         DiagID = diag::err_block_decl_ref_not_modifiable_lvalue;
       else
         DiagID = diag::err_lambda_decl_ref_not_modifiable_lvalue;
       break;
     }
 
     // In ARC, use some specialized diagnostics for occasions where we
     // infer 'const'.  These are always pseudo-strong variables.
     if (S.getLangOpts().ObjCAutoRefCount) {
       DeclRefExpr *declRef = dyn_cast<DeclRefExpr>(E->IgnoreParenCasts());
       if (declRef && isa<VarDecl>(declRef->getDecl())) {
         VarDecl *var = cast<VarDecl>(declRef->getDecl());
 
         // Use the normal diagnostic if it's pseudo-__strong but the
         // user actually wrote 'const'.
         if (var->isARCPseudoStrong() &&
             (!var->getTypeSourceInfo() ||
              !var->getTypeSourceInfo()->getType().isConstQualified())) {
           // There are three pseudo-strong cases:
           //  - self
           ObjCMethodDecl *method = S.getCurMethodDecl();
           if (method && var == method->getSelfDecl()) {
             DiagID = method->isClassMethod()
               ? diag::err_typecheck_arc_assign_self_class_method
               : diag::err_typecheck_arc_assign_self;
 
           //  - Objective-C externally_retained attribute.
           } else if (var->hasAttr<ObjCExternallyRetainedAttr>() ||
                      isa<ParmVarDecl>(var)) {
             DiagID = diag::err_typecheck_arc_assign_externally_retained;
 
           //  - fast enumeration variables
           } else {
             DiagID = diag::err_typecheck_arr_assign_enumeration;
           }
 
           SourceRange Assign;
           if (Loc != OrigLoc)
             Assign = SourceRange(OrigLoc, OrigLoc);
           S.Diag(Loc, DiagID) << E->getSourceRange() << Assign;
           // We need to preserve the AST regardless, so migration tool
           // can do its job.
           return false;
         }
       }
     }
 
     // If none of the special cases above are triggered, then this is a
     // simple const assignment.
     if (DiagID == 0) {
       DiagnoseConstAssignment(S, E, Loc);
       return true;
     }
 
     break;
   case Expr::MLV_ConstAddrSpace:
     DiagnoseConstAssignment(S, E, Loc);
     return true;
   case Expr::MLV_ConstQualifiedField:
     DiagnoseRecursiveConstFields(S, E, Loc);
     return true;
   case Expr::MLV_ArrayType:
   case Expr::MLV_ArrayTemporary:
     DiagID = diag::err_typecheck_array_not_modifiable_lvalue;
     NeedType = true;
     break;
   case Expr::MLV_NotObjectType:
     DiagID = diag::err_typecheck_non_object_not_modifiable_lvalue;
     NeedType = true;
     break;
   case Expr::MLV_LValueCast:
     DiagID = diag::err_typecheck_lvalue_casts_not_supported;
     break;
   case Expr::MLV_Valid:
     llvm_unreachable("did not take early return for MLV_Valid");
   case Expr::MLV_InvalidExpression:
   case Expr::MLV_MemberFunction:
   case Expr::MLV_ClassTemporary:
     DiagID = diag::err_typecheck_expression_not_modifiable_lvalue;
     break;
   case Expr::MLV_IncompleteType:
   case Expr::MLV_IncompleteVoidType:
     return S.RequireCompleteType(Loc, E->getType(),
              diag::err_typecheck_incomplete_type_not_modifiable_lvalue, E);
   case Expr::MLV_DuplicateVectorComponents:
     DiagID = diag::err_typecheck_duplicate_vector_components_not_mlvalue;
     break;
   case Expr::MLV_NoSetterProperty:
     llvm_unreachable("readonly properties should be processed differently");
   case Expr::MLV_InvalidMessageExpression:
     DiagID = diag::err_readonly_message_assignment;
     break;
   case Expr::MLV_SubObjCPropertySetting:
     DiagID = diag::err_no_subobject_property_setting;
     break;
   }
 
   SourceRange Assign;
   if (Loc != OrigLoc)
     Assign = SourceRange(OrigLoc, OrigLoc);
   if (NeedType)
     S.Diag(Loc, DiagID) << E->getType() << E->getSourceRange() << Assign;
   else
     S.Diag(Loc, DiagID) << E->getSourceRange() << Assign;
   return true;
 }
 
 static void CheckIdentityFieldAssignment(Expr *LHSExpr, Expr *RHSExpr,
                                          SourceLocation Loc,
                                          Sema &Sema) {
   if (Sema.inTemplateInstantiation())
     return;
   if (Sema.isUnevaluatedContext())
     return;
   if (Loc.isInvalid() || Loc.isMacroID())
     return;
   if (LHSExpr->getExprLoc().isMacroID() || RHSExpr->getExprLoc().isMacroID())
     return;
 
   // C / C++ fields
   MemberExpr *ML = dyn_cast<MemberExpr>(LHSExpr);
   MemberExpr *MR = dyn_cast<MemberExpr>(RHSExpr);
   if (ML && MR) {
     if (!(isa<CXXThisExpr>(ML->getBase()) && isa<CXXThisExpr>(MR->getBase())))
       return;
     const ValueDecl *LHSDecl =
         cast<ValueDecl>(ML->getMemberDecl()->getCanonicalDecl());
     const ValueDecl *RHSDecl =
         cast<ValueDecl>(MR->getMemberDecl()->getCanonicalDecl());
     if (LHSDecl != RHSDecl)
       return;
     if (LHSDecl->getType().isVolatileQualified())
       return;
     if (const ReferenceType *RefTy = LHSDecl->getType()->getAs<ReferenceType>())
       if (RefTy->getPointeeType().isVolatileQualified())
         return;
 
     Sema.Diag(Loc, diag::warn_identity_field_assign) << 0;
   }
 
   // Objective-C instance variables
   ObjCIvarRefExpr *OL = dyn_cast<ObjCIvarRefExpr>(LHSExpr);
   ObjCIvarRefExpr *OR = dyn_cast<ObjCIvarRefExpr>(RHSExpr);
   if (OL && OR && OL->getDecl() == OR->getDecl()) {
     DeclRefExpr *RL = dyn_cast<DeclRefExpr>(OL->getBase()->IgnoreImpCasts());
     DeclRefExpr *RR = dyn_cast<DeclRefExpr>(OR->getBase()->IgnoreImpCasts());
     if (RL && RR && RL->getDecl() == RR->getDecl())
       Sema.Diag(Loc, diag::warn_identity_field_assign) << 1;
   }
 }
 
 // C99 6.5.16.1
 QualType Sema::CheckAssignmentOperands(Expr *LHSExpr, ExprResult &RHS,
                                        SourceLocation Loc,
                                        QualType CompoundType,
                                        BinaryOperatorKind Opc) {
   assert(!LHSExpr->hasPlaceholderType(BuiltinType::PseudoObject));
 
   // Verify that LHS is a modifiable lvalue, and emit error if not.
   if (CheckForModifiableLvalue(LHSExpr, Loc, *this))
     return QualType();
 
   QualType LHSType = LHSExpr->getType();
   QualType RHSType = CompoundType.isNull() ? RHS.get()->getType() :
                                              CompoundType;
   // OpenCL v1.2 s6.1.1.1 p2:
   // The half data type can only be used to declare a pointer to a buffer that
   // contains half values
   if (getLangOpts().OpenCL &&
       !getOpenCLOptions().isAvailableOption("cl_khr_fp16", getLangOpts()) &&
       LHSType->isHalfType()) {
     Diag(Loc, diag::err_opencl_half_load_store) << 1
         << LHSType.getUnqualifiedType();
     return QualType();
   }
 
   // WebAssembly tables can't be used on RHS of an assignment expression.
   if (RHSType->isWebAssemblyTableType()) {
     Diag(Loc, diag::err_wasm_table_art) << 0;
     return QualType();
   }
 
   AssignConvertType ConvTy;
   if (CompoundType.isNull()) {
     Expr *RHSCheck = RHS.get();
 
     CheckIdentityFieldAssignment(LHSExpr, RHSCheck, Loc, *this);
 
     QualType LHSTy(LHSType);
     ConvTy = CheckSingleAssignmentConstraints(LHSTy, RHS);
     if (RHS.isInvalid())
       return QualType();
     // Special case of NSObject attributes on c-style pointer types.
     if (ConvTy == IncompatiblePointer &&
         ((Context.isObjCNSObjectType(LHSType) &&
           RHSType->isObjCObjectPointerType()) ||
          (Context.isObjCNSObjectType(RHSType) &&
           LHSType->isObjCObjectPointerType())))
       ConvTy = Compatible;
 
     if (ConvTy == Compatible &&
         LHSType->isObjCObjectType())
         Diag(Loc, diag::err_objc_object_assignment)
           << LHSType;
 
     // If the RHS is a unary plus or minus, check to see if they = and + are
     // right next to each other.  If so, the user may have typo'd "x =+ 4"
     // instead of "x += 4".
     if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(RHSCheck))
       RHSCheck = ICE->getSubExpr();
     if (UnaryOperator *UO = dyn_cast<UnaryOperator>(RHSCheck)) {
       if ((UO->getOpcode() == UO_Plus || UO->getOpcode() == UO_Minus) &&
           Loc.isFileID() && UO->getOperatorLoc().isFileID() &&
           // Only if the two operators are exactly adjacent.
           Loc.getLocWithOffset(1) == UO->getOperatorLoc() &&
           // And there is a space or other character before the subexpr of the
           // unary +/-.  We don't want to warn on "x=-1".
           Loc.getLocWithOffset(2) != UO->getSubExpr()->getBeginLoc() &&
           UO->getSubExpr()->getBeginLoc().isFileID()) {
         Diag(Loc, diag::warn_not_compound_assign)
           << (UO->getOpcode() == UO_Plus ? "+" : "-")
           << SourceRange(UO->getOperatorLoc(), UO->getOperatorLoc());
       }
     }
 
     if (ConvTy == Compatible) {
       if (LHSType.getObjCLifetime() == Qualifiers::OCL_Strong) {
         // Warn about retain cycles where a block captures the LHS, but
         // not if the LHS is a simple variable into which the block is
         // being stored...unless that variable can be captured by reference!
         const Expr *InnerLHS = LHSExpr->IgnoreParenCasts();
         const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(InnerLHS);
         if (!DRE || DRE->getDecl()->hasAttr<BlocksAttr>())
           checkRetainCycles(LHSExpr, RHS.get());
       }
 
       if (LHSType.getObjCLifetime() == Qualifiers::OCL_Strong ||
           LHSType.isNonWeakInMRRWithObjCWeak(Context)) {
         // It is safe to assign a weak reference into a strong variable.
         // Although this code can still have problems:
         //   id x = self.weakProp;
         //   id y = self.weakProp;
         // we do not warn to warn spuriously when 'x' and 'y' are on separate
         // paths through the function. This should be revisited if
         // -Wrepeated-use-of-weak is made flow-sensitive.
         // For ObjCWeak only, we do not warn if the assign is to a non-weak
         // variable, which will be valid for the current autorelease scope.
         if (!Diags.isIgnored(diag::warn_arc_repeated_use_of_weak,
                              RHS.get()->getBeginLoc()))
           getCurFunction()->markSafeWeakUse(RHS.get());
 
       } else if (getLangOpts().ObjCAutoRefCount || getLangOpts().ObjCWeak) {
         checkUnsafeExprAssigns(Loc, LHSExpr, RHS.get());
       }
     }
   } else {
     // Compound assignment "x += y"
     ConvTy = CheckAssignmentConstraints(Loc, LHSType, RHSType);
   }
 
   if (DiagnoseAssignmentResult(ConvTy, Loc, LHSType, RHSType,
                                RHS.get(), AA_Assigning))
     return QualType();
 
   CheckForNullPointerDereference(*this, LHSExpr);
 
   if (getLangOpts().CPlusPlus20 && LHSType.isVolatileQualified()) {
     if (CompoundType.isNull()) {
       // C++2a [expr.ass]p5:
       //   A simple-assignment whose left operand is of a volatile-qualified
       //   type is deprecated unless the assignment is either a discarded-value
       //   expression or an unevaluated operand
       ExprEvalContexts.back().VolatileAssignmentLHSs.push_back(LHSExpr);
     }
   }
 
   // C11 6.5.16p3: The type of an assignment expression is the type of the
   // left operand would have after lvalue conversion.
   // C11 6.3.2.1p2: ...this is called lvalue conversion. If the lvalue has
   // qualified type, the value has the unqualified version of the type of the
   // lvalue; additionally, if the lvalue has atomic type, the value has the
   // non-atomic version of the type of the lvalue.
   // C++ 5.17p1: the type of the assignment expression is that of its left
   // operand.
   return getLangOpts().CPlusPlus ? LHSType : LHSType.getAtomicUnqualifiedType();
 }
 
 // Scenarios to ignore if expression E is:
 // 1. an explicit cast expression into void
 // 2. a function call expression that returns void
 static bool IgnoreCommaOperand(const Expr *E, const ASTContext &Context) {
   E = E->IgnoreParens();
 
   if (const CastExpr *CE = dyn_cast<CastExpr>(E)) {
     if (CE->getCastKind() == CK_ToVoid) {
       return true;
     }
 
     // static_cast<void> on a dependent type will not show up as CK_ToVoid.
     if (CE->getCastKind() == CK_Dependent && E->getType()->isVoidType() &&
         CE->getSubExpr()->getType()->isDependentType()) {
       return true;
     }
   }
 
   if (const auto *CE = dyn_cast<CallExpr>(E))
     return CE->getCallReturnType(Context)->isVoidType();
   return false;
 }
 
 // Look for instances where it is likely the comma operator is confused with
 // another operator.  There is an explicit list of acceptable expressions for
 // the left hand side of the comma operator, otherwise emit a warning.
 void Sema::DiagnoseCommaOperator(const Expr *LHS, SourceLocation Loc) {
   // No warnings in macros
   if (Loc.isMacroID())
     return;
 
   // Don't warn in template instantiations.
   if (inTemplateInstantiation())
     return;
 
   // Scope isn't fine-grained enough to explicitly list the specific cases, so
   // instead, skip more than needed, then call back into here with the
   // CommaVisitor in SemaStmt.cpp.
   // The listed locations are the initialization and increment portions
   // of a for loop.  The additional checks are on the condition of
   // if statements, do/while loops, and for loops.
   // Differences in scope flags for C89 mode requires the extra logic.
   const unsigned ForIncrementFlags =
       getLangOpts().C99 || getLangOpts().CPlusPlus
           ? Scope::ControlScope | Scope::ContinueScope | Scope::BreakScope
           : Scope::ContinueScope | Scope::BreakScope;
   const unsigned ForInitFlags = Scope::ControlScope | Scope::DeclScope;
   const unsigned ScopeFlags = getCurScope()->getFlags();
   if ((ScopeFlags & ForIncrementFlags) == ForIncrementFlags ||
       (ScopeFlags & ForInitFlags) == ForInitFlags)
     return;
 
   // If there are multiple comma operators used together, get the RHS of the
   // of the comma operator as the LHS.
   while (const BinaryOperator *BO = dyn_cast<BinaryOperator>(LHS)) {
     if (BO->getOpcode() != BO_Comma)
       break;
     LHS = BO->getRHS();
   }
 
   // Only allow some expressions on LHS to not warn.
   if (IgnoreCommaOperand(LHS, Context))
     return;
 
   Diag(Loc, diag::warn_comma_operator);
   Diag(LHS->getBeginLoc(), diag::note_cast_to_void)
       << LHS->getSourceRange()
       << FixItHint::CreateInsertion(LHS->getBeginLoc(),
                                     LangOpts.CPlusPlus ? "static_cast<void>("
                                                        : "(void)(")
       << FixItHint::CreateInsertion(PP.getLocForEndOfToken(LHS->getEndLoc()),
                                     ")");
 }
 
 // C99 6.5.17
 static QualType CheckCommaOperands(Sema &S, ExprResult &LHS, ExprResult &RHS,
                                    SourceLocation Loc) {
   LHS = S.CheckPlaceholderExpr(LHS.get());
   RHS = S.CheckPlaceholderExpr(RHS.get());
   if (LHS.isInvalid() || RHS.isInvalid())
     return QualType();
 
   // C's comma performs lvalue conversion (C99 6.3.2.1) on both its
   // operands, but not unary promotions.
   // C++'s comma does not do any conversions at all (C++ [expr.comma]p1).
 
   // So we treat the LHS as a ignored value, and in C++ we allow the
   // containing site to determine what should be done with the RHS.
   LHS = S.IgnoredValueConversions(LHS.get());
   if (LHS.isInvalid())
     return QualType();
 
   S.DiagnoseUnusedExprResult(LHS.get(), diag::warn_unused_comma_left_operand);
 
   if (!S.getLangOpts().CPlusPlus) {
     RHS = S.DefaultFunctionArrayLvalueConversion(RHS.get());
     if (RHS.isInvalid())
       return QualType();
     if (!RHS.get()->getType()->isVoidType())
       S.RequireCompleteType(Loc, RHS.get()->getType(),
                             diag::err_incomplete_type);
   }
 
   if (!S.getDiagnostics().isIgnored(diag::warn_comma_operator, Loc))
     S.DiagnoseCommaOperator(LHS.get(), Loc);
 
   return RHS.get()->getType();
 }
 
 /// CheckIncrementDecrementOperand - unlike most "Check" methods, this routine
 /// doesn't need to call UsualUnaryConversions or UsualArithmeticConversions.
 static QualType CheckIncrementDecrementOperand(Sema &S, Expr *Op,
                                                ExprValueKind &VK,
                                                ExprObjectKind &OK,
                                                SourceLocation OpLoc,
                                                bool IsInc, bool IsPrefix) {
   if (Op->isTypeDependent())
     return S.Context.DependentTy;
 
   QualType ResType = Op->getType();
   // Atomic types can be used for increment / decrement where the non-atomic
   // versions can, so ignore the _Atomic() specifier for the purpose of
   // checking.
   if (const AtomicType *ResAtomicType = ResType->getAs<AtomicType>())
     ResType = ResAtomicType->getValueType();
 
   assert(!ResType.isNull() && "no type for increment/decrement expression");
 
   if (S.getLangOpts().CPlusPlus && ResType->isBooleanType()) {
     // Decrement of bool is not allowed.
     if (!IsInc) {
       S.Diag(OpLoc, diag::err_decrement_bool) << Op->getSourceRange();
       return QualType();
     }
     // Increment of bool sets it to true, but is deprecated.
     S.Diag(OpLoc, S.getLangOpts().CPlusPlus17 ? diag::ext_increment_bool
                                               : diag::warn_increment_bool)
       << Op->getSourceRange();
   } else if (S.getLangOpts().CPlusPlus && ResType->isEnumeralType()) {
     // Error on enum increments and decrements in C++ mode
     S.Diag(OpLoc, diag::err_increment_decrement_enum) << IsInc << ResType;
     return QualType();
   } else if (ResType->isRealType()) {
     // OK!
   } else if (ResType->isPointerType()) {
     // C99 6.5.2.4p2, 6.5.6p2
     if (!checkArithmeticOpPointerOperand(S, OpLoc, Op))
       return QualType();
   } else if (ResType->isObjCObjectPointerType()) {
     // On modern runtimes, ObjC pointer arithmetic is forbidden.
     // Otherwise, we just need a complete type.
     if (checkArithmeticIncompletePointerType(S, OpLoc, Op) ||
         checkArithmeticOnObjCPointer(S, OpLoc, Op))
       return QualType();
   } else if (ResType->isAnyComplexType()) {
     // C99 does not support ++/-- on complex types, we allow as an extension.
     S.Diag(OpLoc, diag::ext_integer_increment_complex)
       << ResType << Op->getSourceRange();
   } else if (ResType->isPlaceholderType()) {
     ExprResult PR = S.CheckPlaceholderExpr(Op);
     if (PR.isInvalid()) return QualType();
     return CheckIncrementDecrementOperand(S, PR.get(), VK, OK, OpLoc,
                                           IsInc, IsPrefix);
   } else if (S.getLangOpts().AltiVec && ResType->isVectorType()) {
     // OK! ( C/C++ Language Extensions for CBEA(Version 2.6) 10.3 )
   } else if (S.getLangOpts().ZVector && ResType->isVectorType() &&
              (ResType->castAs<VectorType>()->getVectorKind() !=
               VectorType::AltiVecBool)) {
     // The z vector extensions allow ++ and -- for non-bool vectors.
   } else if(S.getLangOpts().OpenCL && ResType->isVectorType() &&
             ResType->castAs<VectorType>()->getElementType()->isIntegerType()) {
     // OpenCL V1.2 6.3 says dec/inc ops operate on integer vector types.
   } else {
     S.Diag(OpLoc, diag::err_typecheck_illegal_increment_decrement)
       << ResType << int(IsInc) << Op->getSourceRange();
     return QualType();
   }
   // At this point, we know we have a real, complex or pointer type.
   // Now make sure the operand is a modifiable lvalue.
   if (CheckForModifiableLvalue(Op, OpLoc, S))
     return QualType();
   if (S.getLangOpts().CPlusPlus20 && ResType.isVolatileQualified()) {
     // C++2a [expr.pre.inc]p1, [expr.post.inc]p1:
     //   An operand with volatile-qualified type is deprecated
     S.Diag(OpLoc, diag::warn_deprecated_increment_decrement_volatile)
         << IsInc << ResType;
   }
   // In C++, a prefix increment is the same type as the operand. Otherwise
   // (in C or with postfix), the increment is the unqualified type of the
   // operand.
   if (IsPrefix && S.getLangOpts().CPlusPlus) {
     VK = VK_LValue;
     OK = Op->getObjectKind();
     return ResType;
   } else {
     VK = VK_PRValue;
     return ResType.getUnqualifiedType();
   }
 }
 
 
 /// getPrimaryDecl - Helper function for CheckAddressOfOperand().
 /// This routine allows us to typecheck complex/recursive expressions
 /// where the declaration is needed for type checking. We only need to
 /// handle cases when the expression references a function designator
 /// or is an lvalue. Here are some examples:
 ///  - &(x) => x
 ///  - &*****f => f for f a function designator.
 ///  - &s.xx => s
 ///  - &s.zz[1].yy -> s, if zz is an array
 ///  - *(x + 1) -> x, if x is an array
 ///  - &"123"[2] -> 0
 ///  - & __real__ x -> x
 ///
 /// FIXME: We don't recurse to the RHS of a comma, nor handle pointers to
 /// members.
 static ValueDecl *getPrimaryDecl(Expr *E) {
   switch (E->getStmtClass()) {
   case Stmt::DeclRefExprClass:
     return cast<DeclRefExpr>(E)->getDecl();
   case Stmt::MemberExprClass:
     // If this is an arrow operator, the address is an offset from
     // the base's value, so the object the base refers to is
     // irrelevant.
     if (cast<MemberExpr>(E)->isArrow())
       return nullptr;
     // Otherwise, the expression refers to a part of the base
     return getPrimaryDecl(cast<MemberExpr>(E)->getBase());
   case Stmt::ArraySubscriptExprClass: {
     // FIXME: This code shouldn't be necessary!  We should catch the implicit
     // promotion of register arrays earlier.
     Expr* Base = cast<ArraySubscriptExpr>(E)->getBase();
     if (ImplicitCastExpr* ICE = dyn_cast<ImplicitCastExpr>(Base)) {
       if (ICE->getSubExpr()->getType()->isArrayType())
         return getPrimaryDecl(ICE->getSubExpr());
     }
     return nullptr;
   }
   case Stmt::UnaryOperatorClass: {
     UnaryOperator *UO = cast<UnaryOperator>(E);
 
     switch(UO->getOpcode()) {
     case UO_Real:
     case UO_Imag:
     case UO_Extension:
       return getPrimaryDecl(UO->getSubExpr());
     default:
       return nullptr;
     }
   }
   case Stmt::ParenExprClass:
     return getPrimaryDecl(cast<ParenExpr>(E)->getSubExpr());
   case Stmt::ImplicitCastExprClass:
     // If the result of an implicit cast is an l-value, we care about
     // the sub-expression; otherwise, the result here doesn't matter.
     return getPrimaryDecl(cast<ImplicitCastExpr>(E)->getSubExpr());
   case Stmt::CXXUuidofExprClass:
     return cast<CXXUuidofExpr>(E)->getGuidDecl();
   default:
     return nullptr;
   }
 }
 
 namespace {
 enum {
   AO_Bit_Field = 0,
   AO_Vector_Element = 1,
   AO_Property_Expansion = 2,
   AO_Register_Variable = 3,
   AO_Matrix_Element = 4,
   AO_No_Error = 5
 };
 }
 /// Diagnose invalid operand for address of operations.
 ///
 /// \param Type The type of operand which cannot have its address taken.
 static void diagnoseAddressOfInvalidType(Sema &S, SourceLocation Loc,
                                          Expr *E, unsigned Type) {
   S.Diag(Loc, diag::err_typecheck_address_of) << Type << E->getSourceRange();
 }
 
 /// CheckAddressOfOperand - The operand of & must be either a function
 /// designator or an lvalue designating an object. If it is an lvalue, the
 /// object cannot be declared with storage class register or be a bit field.
 /// Note: The usual conversions are *not* applied to the operand of the &
 /// operator (C99 6.3.2.1p[2-4]), and its result is never an lvalue.
 /// In C++, the operand might be an overloaded function name, in which case
 /// we allow the '&' but retain the overloaded-function type.
 QualType Sema::CheckAddressOfOperand(ExprResult &OrigOp, SourceLocation OpLoc) {
   if (const BuiltinType *PTy = OrigOp.get()->getType()->getAsPlaceholderType()){
     if (PTy->getKind() == BuiltinType::Overload) {
       Expr *E = OrigOp.get()->IgnoreParens();
       if (!isa<OverloadExpr>(E)) {
         assert(cast<UnaryOperator>(E)->getOpcode() == UO_AddrOf);
         Diag(OpLoc, diag::err_typecheck_invalid_lvalue_addrof_addrof_function)
           << OrigOp.get()->getSourceRange();
         return QualType();
       }
 
       OverloadExpr *Ovl = cast<OverloadExpr>(E);
       if (isa<UnresolvedMemberExpr>(Ovl))
         if (!ResolveSingleFunctionTemplateSpecialization(Ovl)) {
           Diag(OpLoc, diag::err_invalid_form_pointer_member_function)
             << OrigOp.get()->getSourceRange();
           return QualType();
         }
 
       return Context.OverloadTy;
     }
 
     if (PTy->getKind() == BuiltinType::UnknownAny)
       return Context.UnknownAnyTy;
 
     if (PTy->getKind() == BuiltinType::BoundMember) {
       Diag(OpLoc, diag::err_invalid_form_pointer_member_function)
         << OrigOp.get()->getSourceRange();
       return QualType();
     }
 
     OrigOp = CheckPlaceholderExpr(OrigOp.get());
     if (OrigOp.isInvalid()) return QualType();
   }
 
   if (OrigOp.get()->isTypeDependent())
     return Context.DependentTy;
 
   assert(!OrigOp.get()->hasPlaceholderType());
 
   // Make sure to ignore parentheses in subsequent checks
   Expr *op = OrigOp.get()->IgnoreParens();
 
   // In OpenCL captures for blocks called as lambda functions
   // are located in the private address space. Blocks used in
   // enqueue_kernel can be located in a different address space
   // depending on a vendor implementation. Thus preventing
   // taking an address of the capture to avoid invalid AS casts.
   if (LangOpts.OpenCL) {
     auto* VarRef = dyn_cast<DeclRefExpr>(op);
     if (VarRef && VarRef->refersToEnclosingVariableOrCapture()) {
       Diag(op->getExprLoc(), diag::err_opencl_taking_address_capture);
       return QualType();
     }
   }
 
   if (getLangOpts().C99) {
     // Implement C99-only parts of addressof rules.
     if (UnaryOperator* uOp = dyn_cast<UnaryOperator>(op)) {
       if (uOp->getOpcode() == UO_Deref)
         // Per C99 6.5.3.2, the address of a deref always returns a valid result
         // (assuming the deref expression is valid).
         return uOp->getSubExpr()->getType();
     }
     // Technically, there should be a check for array subscript
     // expressions here, but the result of one is always an lvalue anyway.
   }
   ValueDecl *dcl = getPrimaryDecl(op);
 
   if (auto *FD = dyn_cast_or_null<FunctionDecl>(dcl))
     if (!checkAddressOfFunctionIsAvailable(FD, /*Complain=*/true,
                                            op->getBeginLoc()))
       return QualType();
 
   Expr::LValueClassification lval = op->ClassifyLValue(Context);
   unsigned AddressOfError = AO_No_Error;
 
   if (lval == Expr::LV_ClassTemporary || lval == Expr::LV_ArrayTemporary) {
     bool sfinae = (bool)isSFINAEContext();
     Diag(OpLoc, isSFINAEContext() ? diag::err_typecheck_addrof_temporary
                                   : diag::ext_typecheck_addrof_temporary)
       << op->getType() << op->getSourceRange();
     if (sfinae)
       return QualType();
     // Materialize the temporary as an lvalue so that we can take its address.
     OrigOp = op =
         CreateMaterializeTemporaryExpr(op->getType(), OrigOp.get(), true);
   } else if (isa<ObjCSelectorExpr>(op)) {
     return Context.getPointerType(op->getType());
   } else if (lval == Expr::LV_MemberFunction) {
     // If it's an instance method, make a member pointer.
     // The expression must have exactly the form &A::foo.
 
     // If the underlying expression isn't a decl ref, give up.
     if (!isa<DeclRefExpr>(op)) {
       Diag(OpLoc, diag::err_invalid_form_pointer_member_function)
         << OrigOp.get()->getSourceRange();
       return QualType();
     }
     DeclRefExpr *DRE = cast<DeclRefExpr>(op);
     CXXMethodDecl *MD = cast<CXXMethodDecl>(DRE->getDecl());
 
     // The id-expression was parenthesized.
     if (OrigOp.get() != DRE) {
       Diag(OpLoc, diag::err_parens_pointer_member_function)
         << OrigOp.get()->getSourceRange();
 
     // The method was named without a qualifier.
     } else if (!DRE->getQualifier()) {
       if (MD->getParent()->getName().empty())
         Diag(OpLoc, diag::err_unqualified_pointer_member_function)
           << op->getSourceRange();
       else {
         SmallString<32> Str;
         StringRef Qual = (MD->getParent()->getName() + "::").toStringRef(Str);
         Diag(OpLoc, diag::err_unqualified_pointer_member_function)
           << op->getSourceRange()
           << FixItHint::CreateInsertion(op->getSourceRange().getBegin(), Qual);
       }
     }
 
     // Taking the address of a dtor is illegal per C++ [class.dtor]p2.
     if (isa<CXXDestructorDecl>(MD))
       Diag(OpLoc, diag::err_typecheck_addrof_dtor) << op->getSourceRange();
 
     QualType MPTy = Context.getMemberPointerType(
         op->getType(), Context.getTypeDeclType(MD->getParent()).getTypePtr());
     // Under the MS ABI, lock down the inheritance model now.
     if (Context.getTargetInfo().getCXXABI().isMicrosoft())
       (void)isCompleteType(OpLoc, MPTy);
     return MPTy;
   } else if (lval != Expr::LV_Valid && lval != Expr::LV_IncompleteVoidType) {
     // C99 6.5.3.2p1
     // The operand must be either an l-value or a function designator
     if (!op->getType()->isFunctionType()) {
       // Use a special diagnostic for loads from property references.
       if (isa<PseudoObjectExpr>(op)) {
         AddressOfError = AO_Property_Expansion;
       } else {
         Diag(OpLoc, diag::err_typecheck_invalid_lvalue_addrof)
           << op->getType() << op->getSourceRange();
         return QualType();
       }
     }
   } else if (op->getObjectKind() == OK_BitField) { // C99 6.5.3.2p1
     // The operand cannot be a bit-field
     AddressOfError = AO_Bit_Field;
   } else if (op->getObjectKind() == OK_VectorComponent) {
     // The operand cannot be an element of a vector
     AddressOfError = AO_Vector_Element;
   } else if (op->getObjectKind() == OK_MatrixComponent) {
     // The operand cannot be an element of a matrix.
     AddressOfError = AO_Matrix_Element;
   } else if (dcl) { // C99 6.5.3.2p1
     // We have an lvalue with a decl. Make sure the decl is not declared
     // with the register storage-class specifier.
     if (const VarDecl *vd = dyn_cast<VarDecl>(dcl)) {
       // in C++ it is not error to take address of a register
       // variable (c++03 7.1.1P3)
       if (vd->getStorageClass() == SC_Register &&
           !getLangOpts().CPlusPlus) {
         AddressOfError = AO_Register_Variable;
       }
     } else if (isa<MSPropertyDecl>(dcl)) {
       AddressOfError = AO_Property_Expansion;
     } else if (isa<FunctionTemplateDecl>(dcl)) {
       return Context.OverloadTy;
     } else if (isa<FieldDecl>(dcl) || isa<IndirectFieldDecl>(dcl)) {
       // Okay: we can take the address of a field.
       // Could be a pointer to member, though, if there is an explicit
       // scope qualifier for the class.
       if (isa<DeclRefExpr>(op) && cast<DeclRefExpr>(op)->getQualifier()) {
         DeclContext *Ctx = dcl->getDeclContext();
         if (Ctx && Ctx->isRecord()) {
           if (dcl->getType()->isReferenceType()) {
             Diag(OpLoc,
                  diag::err_cannot_form_pointer_to_member_of_reference_type)
               << dcl->getDeclName() << dcl->getType();
             return QualType();
           }
 
           while (cast<RecordDecl>(Ctx)->isAnonymousStructOrUnion())
             Ctx = Ctx->getParent();
 
           QualType MPTy = Context.getMemberPointerType(
               op->getType(),
               Context.getTypeDeclType(cast<RecordDecl>(Ctx)).getTypePtr());
           // Under the MS ABI, lock down the inheritance model now.
           if (Context.getTargetInfo().getCXXABI().isMicrosoft())
             (void)isCompleteType(OpLoc, MPTy);
           return MPTy;
         }
       }
     } else if (!isa<FunctionDecl, NonTypeTemplateParmDecl, BindingDecl,
                     MSGuidDecl, UnnamedGlobalConstantDecl>(dcl))
       llvm_unreachable("Unknown/unexpected decl type");
   }
 
   if (AddressOfError != AO_No_Error) {
     diagnoseAddressOfInvalidType(*this, OpLoc, op, AddressOfError);
     return QualType();
   }
 
   if (lval == Expr::LV_IncompleteVoidType) {
     // Taking the address of a void variable is technically illegal, but we
     // allow it in cases which are otherwise valid.
     // Example: "extern void x; void* y = &x;".
     Diag(OpLoc, diag::ext_typecheck_addrof_void) << op->getSourceRange();
   }
 
   // If the operand has type "type", the result has type "pointer to type".
   if (op->getType()->isObjCObjectType())
     return Context.getObjCObjectPointerType(op->getType());
 
   // Cannot take the address of WebAssembly references or tables.
   if (Context.getTargetInfo().getTriple().isWasm()) {
     QualType OpTy = op->getType();
     if (OpTy.isWebAssemblyReferenceType()) {
       Diag(OpLoc, diag::err_wasm_ca_reference)
           << 1 << OrigOp.get()->getSourceRange();
       return QualType();
     }
     if (OpTy->isWebAssemblyTableType()) {
       Diag(OpLoc, diag::err_wasm_table_pr)
           << 1 << OrigOp.get()->getSourceRange();
       return QualType();
     }
   }
 
   CheckAddressOfPackedMember(op);
 
   return Context.getPointerType(op->getType());
 }
 
 static void RecordModifiableNonNullParam(Sema &S, const Expr *Exp) {
   const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Exp);
   if (!DRE)
     return;
   const Decl *D = DRE->getDecl();
   if (!D)
     return;
   const ParmVarDecl *Param = dyn_cast<ParmVarDecl>(D);
   if (!Param)
     return;
   if (const FunctionDecl* FD = dyn_cast<FunctionDecl>(Param->getDeclContext()))
     if (!FD->hasAttr<NonNullAttr>() && !Param->hasAttr<NonNullAttr>())
       return;
   if (FunctionScopeInfo *FD = S.getCurFunction())
     FD->ModifiedNonNullParams.insert(Param);
 }
 
 /// CheckIndirectionOperand - Type check unary indirection (prefix '*').
 static QualType CheckIndirectionOperand(Sema &S, Expr *Op, ExprValueKind &VK,
                                         SourceLocation OpLoc,
                                         bool IsAfterAmp = false) {
   if (Op->isTypeDependent())
     return S.Context.DependentTy;
 
   ExprResult ConvResult = S.UsualUnaryConversions(Op);
   if (ConvResult.isInvalid())
     return QualType();
   Op = ConvResult.get();
   QualType OpTy = Op->getType();
   QualType Result;
 
   if (isa<CXXReinterpretCastExpr>(Op)) {
     QualType OpOrigType = Op->IgnoreParenCasts()->getType();
     S.CheckCompatibleReinterpretCast(OpOrigType, OpTy, /*IsDereference*/true,
                                      Op->getSourceRange());
   }
 
   if (const PointerType *PT = OpTy->getAs<PointerType>())
   {
     Result = PT->getPointeeType();
   }
   else if (const ObjCObjectPointerType *OPT =
              OpTy->getAs<ObjCObjectPointerType>())
     Result = OPT->getPointeeType();
   else {
     ExprResult PR = S.CheckPlaceholderExpr(Op);
     if (PR.isInvalid()) return QualType();
     if (PR.get() != Op)
       return CheckIndirectionOperand(S, PR.get(), VK, OpLoc);
   }
 
   if (Result.isNull()) {
     S.Diag(OpLoc, diag::err_typecheck_indirection_requires_pointer)
       << OpTy << Op->getSourceRange();
     return QualType();
   }
 
   if (Result->isVoidType()) {
     // C++ [expr.unary.op]p1:
     //   [...] the expression to which [the unary * operator] is applied shall
     //   be a pointer to an object type, or a pointer to a function type
     LangOptions LO = S.getLangOpts();
     if (LO.CPlusPlus)
       S.Diag(OpLoc, diag::err_typecheck_indirection_through_void_pointer_cpp)
           << OpTy << Op->getSourceRange();
     else if (!(LO.C99 && IsAfterAmp) && !S.isUnevaluatedContext())
       S.Diag(OpLoc, diag::ext_typecheck_indirection_through_void_pointer)
           << OpTy << Op->getSourceRange();
   }
 
   // Dereferences are usually l-values...
   VK = VK_LValue;
 
   // ...except that certain expressions are never l-values in C.
   if (!S.getLangOpts().CPlusPlus && Result.isCForbiddenLValueType())
     VK = VK_PRValue;
 
   return Result;
 }
 
 BinaryOperatorKind Sema::ConvertTokenKindToBinaryOpcode(tok::TokenKind Kind) {
   BinaryOperatorKind Opc;
   switch (Kind) {
   default: llvm_unreachable("Unknown binop!");
   case tok::periodstar:           Opc = BO_PtrMemD; break;
   case tok::arrowstar:            Opc = BO_PtrMemI; break;
   case tok::star:                 Opc = BO_Mul; break;
   case tok::slash:                Opc = BO_Div; break;
   case tok::percent:              Opc = BO_Rem; break;
   case tok::plus:                 Opc = BO_Add; break;
   case tok::minus:                Opc = BO_Sub; break;
   case tok::lessless:             Opc = BO_Shl; break;
   case tok::greatergreater:       Opc = BO_Shr; break;
   case tok::lessequal:            Opc = BO_LE; break;
   case tok::less:                 Opc = BO_LT; break;
   case tok::greaterequal:         Opc = BO_GE; break;
   case tok::greater:              Opc = BO_GT; break;
   case tok::exclaimequal:         Opc = BO_NE; break;
   case tok::equalequal:           Opc = BO_EQ; break;
   case tok::spaceship:            Opc = BO_Cmp; break;
   case tok::amp:                  Opc = BO_And; break;
   case tok::caret:                Opc = BO_Xor; break;
   case tok::pipe:                 Opc = BO_Or; break;
   case tok::ampamp:               Opc = BO_LAnd; break;
   case tok::pipepipe:             Opc = BO_LOr; break;
   case tok::equal:                Opc = BO_Assign; break;
   case tok::starequal:            Opc = BO_MulAssign; break;
   case tok::slashequal:           Opc = BO_DivAssign; break;
   case tok::percentequal:         Opc = BO_RemAssign; break;
   case tok::plusequal:            Opc = BO_AddAssign; break;
   case tok::minusequal:           Opc = BO_SubAssign; break;
   case tok::lesslessequal:        Opc = BO_ShlAssign; break;
   case tok::greatergreaterequal:  Opc = BO_ShrAssign; break;
   case tok::ampequal:             Opc = BO_AndAssign; break;
   case tok::caretequal:           Opc = BO_XorAssign; break;
   case tok::pipeequal:            Opc = BO_OrAssign; break;
   case tok::comma:                Opc = BO_Comma; break;
   }
   return Opc;
 }
 
 static inline UnaryOperatorKind ConvertTokenKindToUnaryOpcode(
   tok::TokenKind Kind) {
   UnaryOperatorKind Opc;
   switch (Kind) {
   default: llvm_unreachable("Unknown unary op!");
   case tok::plusplus:     Opc = UO_PreInc; break;
   case tok::minusminus:   Opc = UO_PreDec; break;
   case tok::amp:          Opc = UO_AddrOf; break;
   case tok::star:         Opc = UO_Deref; break;
   case tok::plus:         Opc = UO_Plus; break;
   case tok::minus:        Opc = UO_Minus; break;
   case tok::tilde:        Opc = UO_Not; break;
   case tok::exclaim:      Opc = UO_LNot; break;
   case tok::kw___real:    Opc = UO_Real; break;
   case tok::kw___imag:    Opc = UO_Imag; break;
   case tok::kw___extension__: Opc = UO_Extension; break;
   }
   return Opc;
 }
 
 const FieldDecl *
 Sema::getSelfAssignmentClassMemberCandidate(const ValueDecl *SelfAssigned) {
   // Explore the case for adding 'this->' to the LHS of a self assignment, very
   // common for setters.
   // struct A {
   // int X;
   // -void setX(int X) { X = X; }
   // +void setX(int X) { this->X = X; }
   // };
 
   // Only consider parameters for self assignment fixes.
   if (!isa<ParmVarDecl>(SelfAssigned))
     return nullptr;
   const auto *Method =
       dyn_cast_or_null<CXXMethodDecl>(getCurFunctionDecl(true));
   if (!Method)
     return nullptr;
 
   const CXXRecordDecl *Parent = Method->getParent();
   // In theory this is fixable if the lambda explicitly captures this, but
   // that's added complexity that's rarely going to be used.
   if (Parent->isLambda())
     return nullptr;
 
   // FIXME: Use an actual Lookup operation instead of just traversing fields
   // in order to get base class fields.
   auto Field =
       llvm::find_if(Parent->fields(),
                     [Name(SelfAssigned->getDeclName())](const FieldDecl *F) {
                       return F->getDeclName() == Name;
                     });
   return (Field != Parent->field_end()) ? *Field : nullptr;
 }
 
 /// DiagnoseSelfAssignment - Emits a warning if a value is assigned to itself.
 /// This warning suppressed in the event of macro expansions.
 static void DiagnoseSelfAssignment(Sema &S, Expr *LHSExpr, Expr *RHSExpr,
                                    SourceLocation OpLoc, bool IsBuiltin) {
   if (S.inTemplateInstantiation())
     return;
   if (S.isUnevaluatedContext())
     return;
   if (OpLoc.isInvalid() || OpLoc.isMacroID())
     return;
   LHSExpr = LHSExpr->IgnoreParenImpCasts();
   RHSExpr = RHSExpr->IgnoreParenImpCasts();
   const DeclRefExpr *LHSDeclRef = dyn_cast<DeclRefExpr>(LHSExpr);
   const DeclRefExpr *RHSDeclRef = dyn_cast<DeclRefExpr>(RHSExpr);
   if (!LHSDeclRef || !RHSDeclRef ||
       LHSDeclRef->getLocation().isMacroID() ||
       RHSDeclRef->getLocation().isMacroID())
     return;
   const ValueDecl *LHSDecl =
     cast<ValueDecl>(LHSDeclRef->getDecl()->getCanonicalDecl());
   const ValueDecl *RHSDecl =
     cast<ValueDecl>(RHSDeclRef->getDecl()->getCanonicalDecl());
   if (LHSDecl != RHSDecl)
     return;
   if (LHSDecl->getType().isVolatileQualified())
     return;
   if (const ReferenceType *RefTy = LHSDecl->getType()->getAs<ReferenceType>())
     if (RefTy->getPointeeType().isVolatileQualified())
       return;
 
   auto Diag = S.Diag(OpLoc, IsBuiltin ? diag::warn_self_assignment_builtin
                                       : diag::warn_self_assignment_overloaded)
               << LHSDeclRef->getType() << LHSExpr->getSourceRange()
               << RHSExpr->getSourceRange();
   if (const FieldDecl *SelfAssignField =
           S.getSelfAssignmentClassMemberCandidate(RHSDecl))
     Diag << 1 << SelfAssignField
          << FixItHint::CreateInsertion(LHSDeclRef->getBeginLoc(), "this->");
   else
     Diag << 0;
 }
 
 /// Check if a bitwise-& is performed on an Objective-C pointer.  This
 /// is usually indicative of introspection within the Objective-C pointer.
 static void checkObjCPointerIntrospection(Sema &S, ExprResult &L, ExprResult &R,
                                           SourceLocation OpLoc) {
   if (!S.getLangOpts().ObjC)
     return;
 
   const Expr *ObjCPointerExpr = nullptr, *OtherExpr = nullptr;
   const Expr *LHS = L.get();
   const Expr *RHS = R.get();
 
   if (LHS->IgnoreParenCasts()->getType()->isObjCObjectPointerType()) {
     ObjCPointerExpr = LHS;
     OtherExpr = RHS;
   }
   else if (RHS->IgnoreParenCasts()->getType()->isObjCObjectPointerType()) {
     ObjCPointerExpr = RHS;
     OtherExpr = LHS;
   }
 
   // This warning is deliberately made very specific to reduce false
   // positives with logic that uses '&' for hashing.  This logic mainly
   // looks for code trying to introspect into tagged pointers, which
   // code should generally never do.
   if (ObjCPointerExpr && isa<IntegerLiteral>(OtherExpr->IgnoreParenCasts())) {
     unsigned Diag = diag::warn_objc_pointer_masking;
     // Determine if we are introspecting the result of performSelectorXXX.
     const Expr *Ex = ObjCPointerExpr->IgnoreParenCasts();
     // Special case messages to -performSelector and friends, which
     // can return non-pointer values boxed in a pointer value.
     // Some clients may wish to silence warnings in this subcase.
     if (const ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(Ex)) {
       Selector S = ME->getSelector();
       StringRef SelArg0 = S.getNameForSlot(0);
       if (SelArg0.startswith("performSelector"))
         Diag = diag::warn_objc_pointer_masking_performSelector;
     }
 
     S.Diag(OpLoc, Diag)
       << ObjCPointerExpr->getSourceRange();
   }
 }
 
 static NamedDecl *getDeclFromExpr(Expr *E) {
   if (!E)
     return nullptr;
   if (auto *DRE = dyn_cast<DeclRefExpr>(E))
     return DRE->getDecl();
   if (auto *ME = dyn_cast<MemberExpr>(E))
     return ME->getMemberDecl();
   if (auto *IRE = dyn_cast<ObjCIvarRefExpr>(E))
     return IRE->getDecl();
   return nullptr;
 }
 
 // This helper function promotes a binary operator's operands (which are of a
 // half vector type) to a vector of floats and then truncates the result to
 // a vector of either half or short.
 static ExprResult convertHalfVecBinOp(Sema &S, ExprResult LHS, ExprResult RHS,
                                       BinaryOperatorKind Opc, QualType ResultTy,
                                       ExprValueKind VK, ExprObjectKind OK,
                                       bool IsCompAssign, SourceLocation OpLoc,
                                       FPOptionsOverride FPFeatures) {
   auto &Context = S.getASTContext();
   assert((isVector(ResultTy, Context.HalfTy) ||
           isVector(ResultTy, Context.ShortTy)) &&
          "Result must be a vector of half or short");
   assert(isVector(LHS.get()->getType(), Context.HalfTy) &&
          isVector(RHS.get()->getType(), Context.HalfTy) &&
          "both operands expected to be a half vector");
 
   RHS = convertVector(RHS.get(), Context.FloatTy, S);
   QualType BinOpResTy = RHS.get()->getType();
 
   // If Opc is a comparison, ResultType is a vector of shorts. In that case,
   // change BinOpResTy to a vector of ints.
   if (isVector(ResultTy, Context.ShortTy))
     BinOpResTy = S.GetSignedVectorType(BinOpResTy);
 
   if (IsCompAssign)
     return CompoundAssignOperator::Create(Context, LHS.get(), RHS.get(), Opc,
                                           ResultTy, VK, OK, OpLoc, FPFeatures,
                                           BinOpResTy, BinOpResTy);
 
   LHS = convertVector(LHS.get(), Context.FloatTy, S);
   auto *BO = BinaryOperator::Create(Context, LHS.get(), RHS.get(), Opc,
                                     BinOpResTy, VK, OK, OpLoc, FPFeatures);
   return convertVector(BO, ResultTy->castAs<VectorType>()->getElementType(), S);
 }
 
 static std::pair<ExprResult, ExprResult>
 CorrectDelayedTyposInBinOp(Sema &S, BinaryOperatorKind Opc, Expr *LHSExpr,
                            Expr *RHSExpr) {
   ExprResult LHS = LHSExpr, RHS = RHSExpr;
   if (!S.Context.isDependenceAllowed()) {
     // C cannot handle TypoExpr nodes on either side of a binop because it
     // doesn't handle dependent types properly, so make sure any TypoExprs have
     // been dealt with before checking the operands.
     LHS = S.CorrectDelayedTyposInExpr(LHS);
     RHS = S.CorrectDelayedTyposInExpr(
         RHS, /*InitDecl=*/nullptr, /*RecoverUncorrectedTypos=*/false,
         [Opc, LHS](Expr *E) {
           if (Opc != BO_Assign)
             return ExprResult(E);
           // Avoid correcting the RHS to the same Expr as the LHS.
           Decl *D = getDeclFromExpr(E);
           return (D && D == getDeclFromExpr(LHS.get())) ? ExprError() : E;
         });
   }
   return std::make_pair(LHS, RHS);
 }
 
 /// Returns true if conversion between vectors of halfs and vectors of floats
 /// is needed.
 static bool needsConversionOfHalfVec(bool OpRequiresConversion, ASTContext &Ctx,
                                      Expr *E0, Expr *E1 = nullptr) {
   if (!OpRequiresConversion || Ctx.getLangOpts().NativeHalfType ||
       Ctx.getTargetInfo().useFP16ConversionIntrinsics())
     return false;
 
   auto HasVectorOfHalfType = [&Ctx](Expr *E) {
     QualType Ty = E->IgnoreImplicit()->getType();
 
     // Don't promote half precision neon vectors like float16x4_t in arm_neon.h
     // to vectors of floats. Although the element type of the vectors is __fp16,
     // the vectors shouldn't be treated as storage-only types. See the
     // discussion here: https://reviews.llvm.org/rG825235c140e7
     if (const VectorType *VT = Ty->getAs<VectorType>()) {
       if (VT->getVectorKind() == VectorType::NeonVector)
         return false;
       return VT->getElementType().getCanonicalType() == Ctx.HalfTy;
     }
     return false;
   };
 
   return HasVectorOfHalfType(E0) && (!E1 || HasVectorOfHalfType(E1));
 }
 
 /// CreateBuiltinBinOp - Creates a new built-in binary operation with
 /// operator @p Opc at location @c TokLoc. This routine only supports
 /// built-in operations; ActOnBinOp handles overloaded operators.
 ExprResult Sema::CreateBuiltinBinOp(SourceLocation OpLoc,
                                     BinaryOperatorKind Opc,
                                     Expr *LHSExpr, Expr *RHSExpr) {
   if (getLangOpts().CPlusPlus11 && isa<InitListExpr>(RHSExpr)) {
     // The syntax only allows initializer lists on the RHS of assignment,
     // so we don't need to worry about accepting invalid code for
     // non-assignment operators.
     // C++11 5.17p9:
     //   The meaning of x = {v} [...] is that of x = T(v) [...]. The meaning
     //   of x = {} is x = T().
     InitializationKind Kind = InitializationKind::CreateDirectList(
         RHSExpr->getBeginLoc(), RHSExpr->getBeginLoc(), RHSExpr->getEndLoc());
     InitializedEntity Entity =
         InitializedEntity::InitializeTemporary(LHSExpr->getType());
     InitializationSequence InitSeq(*this, Entity, Kind, RHSExpr);
     ExprResult Init = InitSeq.Perform(*this, Entity, Kind, RHSExpr);
     if (Init.isInvalid())
       return Init;
     RHSExpr = Init.get();
   }
 
   ExprResult LHS = LHSExpr, RHS = RHSExpr;
   QualType ResultTy;     // Result type of the binary operator.
   // The following two variables are used for compound assignment operators
   QualType CompLHSTy;    // Type of LHS after promotions for computation
   QualType CompResultTy; // Type of computation result
   ExprValueKind VK = VK_PRValue;
   ExprObjectKind OK = OK_Ordinary;
   bool ConvertHalfVec = false;
 
   std::tie(LHS, RHS) = CorrectDelayedTyposInBinOp(*this, Opc, LHSExpr, RHSExpr);
   if (!LHS.isUsable() || !RHS.isUsable())
     return ExprError();
 
   if (getLangOpts().OpenCL) {
     QualType LHSTy = LHSExpr->getType();
     QualType RHSTy = RHSExpr->getType();
     // OpenCLC v2.0 s6.13.11.1 allows atomic variables to be initialized by
     // the ATOMIC_VAR_INIT macro.
     if (LHSTy->isAtomicType() || RHSTy->isAtomicType()) {
       SourceRange SR(LHSExpr->getBeginLoc(), RHSExpr->getEndLoc());
       if (BO_Assign == Opc)
         Diag(OpLoc, diag::err_opencl_atomic_init) << 0 << SR;
       else
         ResultTy = InvalidOperands(OpLoc, LHS, RHS);
       return ExprError();
     }
 
     // OpenCL special types - image, sampler, pipe, and blocks are to be used
     // only with a builtin functions and therefore should be disallowed here.
     if (LHSTy->isImageType() || RHSTy->isImageType() ||
         LHSTy->isSamplerT() || RHSTy->isSamplerT() ||
         LHSTy->isPipeType() || RHSTy->isPipeType() ||
         LHSTy->isBlockPointerType() || RHSTy->isBlockPointerType()) {
       ResultTy = InvalidOperands(OpLoc, LHS, RHS);
       return ExprError();
     }
   }
 
   checkTypeSupport(LHSExpr->getType(), OpLoc, /*ValueDecl*/ nullptr);
   checkTypeSupport(RHSExpr->getType(), OpLoc, /*ValueDecl*/ nullptr);
 
   switch (Opc) {
   case BO_Assign:
     ResultTy = CheckAssignmentOperands(LHS.get(), RHS, OpLoc, QualType(), Opc);
     if (getLangOpts().CPlusPlus &&
         LHS.get()->getObjectKind() != OK_ObjCProperty) {
       VK = LHS.get()->getValueKind();
       OK = LHS.get()->getObjectKind();
     }
     if (!ResultTy.isNull()) {
       DiagnoseSelfAssignment(*this, LHS.get(), RHS.get(), OpLoc, true);
       DiagnoseSelfMove(LHS.get(), RHS.get(), OpLoc);
 
       // Avoid copying a block to the heap if the block is assigned to a local
       // auto variable that is declared in the same scope as the block. This
       // optimization is unsafe if the local variable is declared in an outer
       // scope. For example:
       //
       // BlockTy b;
       // {
       //   b = ^{...};
       // }
       // // It is unsafe to invoke the block here if it wasn't copied to the
       // // heap.
       // b();
 
       if (auto *BE = dyn_cast<BlockExpr>(RHS.get()->IgnoreParens()))
         if (auto *DRE = dyn_cast<DeclRefExpr>(LHS.get()->IgnoreParens()))
           if (auto *VD = dyn_cast<VarDecl>(DRE->getDecl()))
             if (VD->hasLocalStorage() && getCurScope()->isDeclScope(VD))
               BE->getBlockDecl()->setCanAvoidCopyToHeap();
 
       if (LHS.get()->getType().hasNonTrivialToPrimitiveCopyCUnion())
         checkNonTrivialCUnion(LHS.get()->getType(), LHS.get()->getExprLoc(),
                               NTCUC_Assignment, NTCUK_Copy);
     }
     RecordModifiableNonNullParam(*this, LHS.get());
     break;
   case BO_PtrMemD:
   case BO_PtrMemI:
     ResultTy = CheckPointerToMemberOperands(LHS, RHS, VK, OpLoc,
                                             Opc == BO_PtrMemI);
     break;
   case BO_Mul:
   case BO_Div:
     ConvertHalfVec = true;
     ResultTy = CheckMultiplyDivideOperands(LHS, RHS, OpLoc, false,
                                            Opc == BO_Div);
     break;
   case BO_Rem:
     ResultTy = CheckRemainderOperands(LHS, RHS, OpLoc);
     break;
   case BO_Add:
     ConvertHalfVec = true;
     ResultTy = CheckAdditionOperands(LHS, RHS, OpLoc, Opc);
     break;
   case BO_Sub:
     ConvertHalfVec = true;
     ResultTy = CheckSubtractionOperands(LHS, RHS, OpLoc);
     break;
   case BO_Shl:
   case BO_Shr:
     ResultTy = CheckShiftOperands(LHS, RHS, OpLoc, Opc);
     break;
   case BO_LE:
   case BO_LT:
   case BO_GE:
   case BO_GT:
     ConvertHalfVec = true;
     ResultTy = CheckCompareOperands(LHS, RHS, OpLoc, Opc);
     break;
   case BO_EQ:
   case BO_NE:
     ConvertHalfVec = true;
     ResultTy = CheckCompareOperands(LHS, RHS, OpLoc, Opc);
     break;
   case BO_Cmp:
     ConvertHalfVec = true;
     ResultTy = CheckCompareOperands(LHS, RHS, OpLoc, Opc);
     assert(ResultTy.isNull() || ResultTy->getAsCXXRecordDecl());
     break;
   case BO_And:
     checkObjCPointerIntrospection(*this, LHS, RHS, OpLoc);
     [[fallthrough]];
   case BO_Xor:
   case BO_Or:
     ResultTy = CheckBitwiseOperands(LHS, RHS, OpLoc, Opc);
     break;
   case BO_LAnd:
   case BO_LOr:
     ConvertHalfVec = true;
     ResultTy = CheckLogicalOperands(LHS, RHS, OpLoc, Opc);
     break;
   case BO_MulAssign:
   case BO_DivAssign:
     ConvertHalfVec = true;
     CompResultTy = CheckMultiplyDivideOperands(LHS, RHS, OpLoc, true,
                                                Opc == BO_DivAssign);
     CompLHSTy = CompResultTy;
     if (!CompResultTy.isNull() && !LHS.isInvalid() && !RHS.isInvalid())
       ResultTy =
           CheckAssignmentOperands(LHS.get(), RHS, OpLoc, CompResultTy, Opc);
     break;
   case BO_RemAssign:
     CompResultTy = CheckRemainderOperands(LHS, RHS, OpLoc, true);
     CompLHSTy = CompResultTy;
     if (!CompResultTy.isNull() && !LHS.isInvalid() && !RHS.isInvalid())
       ResultTy =
           CheckAssignmentOperands(LHS.get(), RHS, OpLoc, CompResultTy, Opc);
     break;
   case BO_AddAssign:
     ConvertHalfVec = true;
     CompResultTy = CheckAdditionOperands(LHS, RHS, OpLoc, Opc, &CompLHSTy);
     if (!CompResultTy.isNull() && !LHS.isInvalid() && !RHS.isInvalid())
       ResultTy =
           CheckAssignmentOperands(LHS.get(), RHS, OpLoc, CompResultTy, Opc);
     break;
   case BO_SubAssign:
     ConvertHalfVec = true;
     CompResultTy = CheckSubtractionOperands(LHS, RHS, OpLoc, &CompLHSTy);
     if (!CompResultTy.isNull() && !LHS.isInvalid() && !RHS.isInvalid())
       ResultTy =
           CheckAssignmentOperands(LHS.get(), RHS, OpLoc, CompResultTy, Opc);
     break;
   case BO_ShlAssign:
   case BO_ShrAssign:
     CompResultTy = CheckShiftOperands(LHS, RHS, OpLoc, Opc, true);
     CompLHSTy = CompResultTy;
     if (!CompResultTy.isNull() && !LHS.isInvalid() && !RHS.isInvalid())
       ResultTy =
           CheckAssignmentOperands(LHS.get(), RHS, OpLoc, CompResultTy, Opc);
     break;
   case BO_AndAssign:
   case BO_OrAssign: // fallthrough
     DiagnoseSelfAssignment(*this, LHS.get(), RHS.get(), OpLoc, true);
     [[fallthrough]];
   case BO_XorAssign:
     CompResultTy = CheckBitwiseOperands(LHS, RHS, OpLoc, Opc);
     CompLHSTy = CompResultTy;
     if (!CompResultTy.isNull() && !LHS.isInvalid() && !RHS.isInvalid())
       ResultTy =
           CheckAssignmentOperands(LHS.get(), RHS, OpLoc, CompResultTy, Opc);
     break;
   case BO_Comma:
     ResultTy = CheckCommaOperands(*this, LHS, RHS, OpLoc);
     if (getLangOpts().CPlusPlus && !RHS.isInvalid()) {
       VK = RHS.get()->getValueKind();
       OK = RHS.get()->getObjectKind();
     }
     break;
   }
   if (ResultTy.isNull() || LHS.isInvalid() || RHS.isInvalid())
     return ExprError();
 
   // Some of the binary operations require promoting operands of half vector to
   // float vectors and truncating the result back to half vector. For now, we do
   // this only when HalfArgsAndReturn is set (that is, when the target is arm or
   // arm64).
   assert(
       (Opc == BO_Comma || isVector(RHS.get()->getType(), Context.HalfTy) ==
                               isVector(LHS.get()->getType(), Context.HalfTy)) &&
       "both sides are half vectors or neither sides are");
   ConvertHalfVec =
       needsConversionOfHalfVec(ConvertHalfVec, Context, LHS.get(), RHS.get());
 
   // Check for array bounds violations for both sides of the BinaryOperator
   CheckArrayAccess(LHS.get());
   CheckArrayAccess(RHS.get());
 
   if (const ObjCIsaExpr *OISA = dyn_cast<ObjCIsaExpr>(LHS.get()->IgnoreParenCasts())) {
     NamedDecl *ObjectSetClass = LookupSingleName(TUScope,
                                                  &Context.Idents.get("object_setClass"),
                                                  SourceLocation(), LookupOrdinaryName);
     if (ObjectSetClass && isa<ObjCIsaExpr>(LHS.get())) {
       SourceLocation RHSLocEnd = getLocForEndOfToken(RHS.get()->getEndLoc());
       Diag(LHS.get()->getExprLoc(), diag::warn_objc_isa_assign)
           << FixItHint::CreateInsertion(LHS.get()->getBeginLoc(),
                                         "object_setClass(")
           << FixItHint::CreateReplacement(SourceRange(OISA->getOpLoc(), OpLoc),
                                           ",")
           << FixItHint::CreateInsertion(RHSLocEnd, ")");
     }
     else
       Diag(LHS.get()->getExprLoc(), diag::warn_objc_isa_assign);
   }
   else if (const ObjCIvarRefExpr *OIRE =
            dyn_cast<ObjCIvarRefExpr>(LHS.get()->IgnoreParenCasts()))
     DiagnoseDirectIsaAccess(*this, OIRE, OpLoc, RHS.get());
 
   // Opc is not a compound assignment if CompResultTy is null.
   if (CompResultTy.isNull()) {
     if (ConvertHalfVec)
       return convertHalfVecBinOp(*this, LHS, RHS, Opc, ResultTy, VK, OK, false,
                                  OpLoc, CurFPFeatureOverrides());
     return BinaryOperator::Create(Context, LHS.get(), RHS.get(), Opc, ResultTy,
                                   VK, OK, OpLoc, CurFPFeatureOverrides());
   }
 
   // Handle compound assignments.
   if (getLangOpts().CPlusPlus && LHS.get()->getObjectKind() !=
       OK_ObjCProperty) {
     VK = VK_LValue;
     OK = LHS.get()->getObjectKind();
   }
 
   // The LHS is not converted to the result type for fixed-point compound
   // assignment as the common type is computed on demand. Reset the CompLHSTy
   // to the LHS type we would have gotten after unary conversions.
   if (CompResultTy->isFixedPointType())
     CompLHSTy = UsualUnaryConversions(LHS.get()).get()->getType();
 
   if (ConvertHalfVec)
     return convertHalfVecBinOp(*this, LHS, RHS, Opc, ResultTy, VK, OK, true,
                                OpLoc, CurFPFeatureOverrides());
 
   return CompoundAssignOperator::Create(
       Context, LHS.get(), RHS.get(), Opc, ResultTy, VK, OK, OpLoc,
       CurFPFeatureOverrides(), CompLHSTy, CompResultTy);
 }
 
 /// DiagnoseBitwisePrecedence - Emit a warning when bitwise and comparison
 /// operators are mixed in a way that suggests that the programmer forgot that
 /// comparison operators have higher precedence. The most typical example of
 /// such code is "flags & 0x0020 != 0", which is equivalent to "flags & 1".
 static void DiagnoseBitwisePrecedence(Sema &Self, BinaryOperatorKind Opc,
                                       SourceLocation OpLoc, Expr *LHSExpr,
                                       Expr *RHSExpr) {
   BinaryOperator *LHSBO = dyn_cast<BinaryOperator>(LHSExpr);
   BinaryOperator *RHSBO = dyn_cast<BinaryOperator>(RHSExpr);
 
   // Check that one of the sides is a comparison operator and the other isn't.
   bool isLeftComp = LHSBO && LHSBO->isComparisonOp();
   bool isRightComp = RHSBO && RHSBO->isComparisonOp();
   if (isLeftComp == isRightComp)
     return;
 
   // Bitwise operations are sometimes used as eager logical ops.
   // Don't diagnose this.
   bool isLeftBitwise = LHSBO && LHSBO->isBitwiseOp();
   bool isRightBitwise = RHSBO && RHSBO->isBitwiseOp();
   if (isLeftBitwise || isRightBitwise)
     return;
 
   SourceRange DiagRange = isLeftComp
                               ? SourceRange(LHSExpr->getBeginLoc(), OpLoc)
                               : SourceRange(OpLoc, RHSExpr->getEndLoc());
   StringRef OpStr = isLeftComp ? LHSBO->getOpcodeStr() : RHSBO->getOpcodeStr();
   SourceRange ParensRange =
       isLeftComp
           ? SourceRange(LHSBO->getRHS()->getBeginLoc(), RHSExpr->getEndLoc())
           : SourceRange(LHSExpr->getBeginLoc(), RHSBO->getLHS()->getEndLoc());
 
   Self.Diag(OpLoc, diag::warn_precedence_bitwise_rel)
     << DiagRange << BinaryOperator::getOpcodeStr(Opc) << OpStr;
   SuggestParentheses(Self, OpLoc,
     Self.PDiag(diag::note_precedence_silence) << OpStr,
     (isLeftComp ? LHSExpr : RHSExpr)->getSourceRange());
   SuggestParentheses(Self, OpLoc,
     Self.PDiag(diag::note_precedence_bitwise_first)
       << BinaryOperator::getOpcodeStr(Opc),
     ParensRange);
 }
 
 /// It accepts a '&&' expr that is inside a '||' one.
 /// Emit a diagnostic together with a fixit hint that wraps the '&&' expression
 /// in parentheses.
 static void
 EmitDiagnosticForLogicalAndInLogicalOr(Sema &Self, SourceLocation OpLoc,
                                        BinaryOperator *Bop) {
   assert(Bop->getOpcode() == BO_LAnd);
   Self.Diag(Bop->getOperatorLoc(), diag::warn_logical_and_in_logical_or)
       << Bop->getSourceRange() << OpLoc;
   SuggestParentheses(Self, Bop->getOperatorLoc(),
     Self.PDiag(diag::note_precedence_silence)
       << Bop->getOpcodeStr(),
     Bop->getSourceRange());
 }
 
 /// Look for '&&' in the left hand of a '||' expr.
 static void DiagnoseLogicalAndInLogicalOrLHS(Sema &S, SourceLocation OpLoc,
                                              Expr *LHSExpr, Expr *RHSExpr) {
   if (BinaryOperator *Bop = dyn_cast<BinaryOperator>(LHSExpr)) {
     if (Bop->getOpcode() == BO_LAnd) {
       // If it's "string_literal && a || b" don't warn since the precedence
       // doesn't matter.
       if (!isa<StringLiteral>(Bop->getLHS()->IgnoreParenImpCasts()))
         return EmitDiagnosticForLogicalAndInLogicalOr(S, OpLoc, Bop);
     } else if (Bop->getOpcode() == BO_LOr) {
       if (BinaryOperator *RBop = dyn_cast<BinaryOperator>(Bop->getRHS())) {
         // If it's "a || b && string_literal || c" we didn't warn earlier for
         // "a || b && string_literal", but warn now.
         if (RBop->getOpcode() == BO_LAnd &&
             isa<StringLiteral>(RBop->getRHS()->IgnoreParenImpCasts()))
           return EmitDiagnosticForLogicalAndInLogicalOr(S, OpLoc, RBop);
       }
     }
   }
 }
 
 /// Look for '&&' in the right hand of a '||' expr.
 static void DiagnoseLogicalAndInLogicalOrRHS(Sema &S, SourceLocation OpLoc,
                                              Expr *LHSExpr, Expr *RHSExpr) {
   if (BinaryOperator *Bop = dyn_cast<BinaryOperator>(RHSExpr)) {
     if (Bop->getOpcode() == BO_LAnd) {
       // If it's "a || b && string_literal" don't warn since the precedence
       // doesn't matter.
       if (!isa<StringLiteral>(Bop->getRHS()->IgnoreParenImpCasts()))
         return EmitDiagnosticForLogicalAndInLogicalOr(S, OpLoc, Bop);
     }
   }
 }
 
 /// Look for bitwise op in the left or right hand of a bitwise op with
 /// lower precedence and emit a diagnostic together with a fixit hint that wraps
 /// the '&' expression in parentheses.
 static void DiagnoseBitwiseOpInBitwiseOp(Sema &S, BinaryOperatorKind Opc,
                                          SourceLocation OpLoc, Expr *SubExpr) {
   if (BinaryOperator *Bop = dyn_cast<BinaryOperator>(SubExpr)) {
     if (Bop->isBitwiseOp() && Bop->getOpcode() < Opc) {
       S.Diag(Bop->getOperatorLoc(), diag::warn_bitwise_op_in_bitwise_op)
         << Bop->getOpcodeStr() << BinaryOperator::getOpcodeStr(Opc)
         << Bop->getSourceRange() << OpLoc;
       SuggestParentheses(S, Bop->getOperatorLoc(),
         S.PDiag(diag::note_precedence_silence)
           << Bop->getOpcodeStr(),
         Bop->getSourceRange());
     }
   }
 }
 
 static void DiagnoseAdditionInShift(Sema &S, SourceLocation OpLoc,
                                     Expr *SubExpr, StringRef Shift) {
   if (BinaryOperator *Bop = dyn_cast<BinaryOperator>(SubExpr)) {
     if (Bop->getOpcode() == BO_Add || Bop->getOpcode() == BO_Sub) {
       StringRef Op = Bop->getOpcodeStr();
       S.Diag(Bop->getOperatorLoc(), diag::warn_addition_in_bitshift)
           << Bop->getSourceRange() << OpLoc << Shift << Op;
       SuggestParentheses(S, Bop->getOperatorLoc(),
           S.PDiag(diag::note_precedence_silence) << Op,
           Bop->getSourceRange());
     }
   }
 }
 
 static void DiagnoseShiftCompare(Sema &S, SourceLocation OpLoc,
                                  Expr *LHSExpr, Expr *RHSExpr) {
   CXXOperatorCallExpr *OCE = dyn_cast<CXXOperatorCallExpr>(LHSExpr);
   if (!OCE)
     return;
 
   FunctionDecl *FD = OCE->getDirectCallee();
   if (!FD || !FD->isOverloadedOperator())
     return;
 
   OverloadedOperatorKind Kind = FD->getOverloadedOperator();
   if (Kind != OO_LessLess && Kind != OO_GreaterGreater)
     return;
 
   S.Diag(OpLoc, diag::warn_overloaded_shift_in_comparison)
       << LHSExpr->getSourceRange() << RHSExpr->getSourceRange()
       << (Kind == OO_LessLess);
   SuggestParentheses(S, OCE->getOperatorLoc(),
                      S.PDiag(diag::note_precedence_silence)
                          << (Kind == OO_LessLess ? "<<" : ">>"),
                      OCE->getSourceRange());
   SuggestParentheses(
       S, OpLoc, S.PDiag(diag::note_evaluate_comparison_first),
       SourceRange(OCE->getArg(1)->getBeginLoc(), RHSExpr->getEndLoc()));
 }
 
 /// DiagnoseBinOpPrecedence - Emit warnings for expressions with tricky
 /// precedence.
 static void DiagnoseBinOpPrecedence(Sema &Self, BinaryOperatorKind Opc,
                                     SourceLocation OpLoc, Expr *LHSExpr,
                                     Expr *RHSExpr){
   // Diagnose "arg1 'bitwise' arg2 'eq' arg3".
   if (BinaryOperator::isBitwiseOp(Opc))
     DiagnoseBitwisePrecedence(Self, Opc, OpLoc, LHSExpr, RHSExpr);
 
   // Diagnose "arg1 & arg2 | arg3"
   if ((Opc == BO_Or || Opc == BO_Xor) &&
       !OpLoc.isMacroID()/* Don't warn in macros. */) {
     DiagnoseBitwiseOpInBitwiseOp(Self, Opc, OpLoc, LHSExpr);
     DiagnoseBitwiseOpInBitwiseOp(Self, Opc, OpLoc, RHSExpr);
   }
 
   // Warn about arg1 || arg2 && arg3, as GCC 4.3+ does.
   // We don't warn for 'assert(a || b && "bad")' since this is safe.
   if (Opc == BO_LOr && !OpLoc.isMacroID()/* Don't warn in macros. */) {
     DiagnoseLogicalAndInLogicalOrLHS(Self, OpLoc, LHSExpr, RHSExpr);
     DiagnoseLogicalAndInLogicalOrRHS(Self, OpLoc, LHSExpr, RHSExpr);
   }
 
   if ((Opc == BO_Shl && LHSExpr->getType()->isIntegralType(Self.getASTContext()))
       || Opc == BO_Shr) {
     StringRef Shift = BinaryOperator::getOpcodeStr(Opc);
     DiagnoseAdditionInShift(Self, OpLoc, LHSExpr, Shift);
     DiagnoseAdditionInShift(Self, OpLoc, RHSExpr, Shift);
   }
 
   // Warn on overloaded shift operators and comparisons, such as:
   // cout << 5 == 4;
   if (BinaryOperator::isComparisonOp(Opc))
     DiagnoseShiftCompare(Self, OpLoc, LHSExpr, RHSExpr);
 }
 
 // Binary Operators.  'Tok' is the token for the operator.
 ExprResult Sema::ActOnBinOp(Scope *S, SourceLocation TokLoc,
                             tok::TokenKind Kind,
                             Expr *LHSExpr, Expr *RHSExpr) {
   BinaryOperatorKind Opc = ConvertTokenKindToBinaryOpcode(Kind);
   assert(LHSExpr && "ActOnBinOp(): missing left expression");
   assert(RHSExpr && "ActOnBinOp(): missing right expression");
 
   // Emit warnings for tricky precedence issues, e.g. "bitfield & 0x4 == 0"
   DiagnoseBinOpPrecedence(*this, Opc, TokLoc, LHSExpr, RHSExpr);
 
   return BuildBinOp(S, TokLoc, Opc, LHSExpr, RHSExpr);
 }
 
 void Sema::LookupBinOp(Scope *S, SourceLocation OpLoc, BinaryOperatorKind Opc,
                        UnresolvedSetImpl &Functions) {
   OverloadedOperatorKind OverOp = BinaryOperator::getOverloadedOperator(Opc);
   if (OverOp != OO_None && OverOp != OO_Equal)
     LookupOverloadedOperatorName(OverOp, S, Functions);
 
   // In C++20 onwards, we may have a second operator to look up.
   if (getLangOpts().CPlusPlus20) {
     if (OverloadedOperatorKind ExtraOp = getRewrittenOverloadedOperator(OverOp))
       LookupOverloadedOperatorName(ExtraOp, S, Functions);
   }
 }
 
 /// Build an overloaded binary operator expression in the given scope.
 static ExprResult BuildOverloadedBinOp(Sema &S, Scope *Sc, SourceLocation OpLoc,
                                        BinaryOperatorKind Opc,
                                        Expr *LHS, Expr *RHS) {
   switch (Opc) {
   case BO_Assign:
     // In the non-overloaded case, we warn about self-assignment (x = x) for
     // both simple assignment and certain compound assignments where algebra
     // tells us the operation yields a constant result.  When the operator is
     // overloaded, we can't do the latter because we don't want to assume that
     // those algebraic identities still apply; for example, a path-building
     // library might use operator/= to append paths.  But it's still reasonable
     // to assume that simple assignment is just moving/copying values around
     // and so self-assignment is likely a bug.
     DiagnoseSelfAssignment(S, LHS, RHS, OpLoc, false);
     [[fallthrough]];
   case BO_DivAssign:
   case BO_RemAssign:
   case BO_SubAssign:
   case BO_AndAssign:
   case BO_OrAssign:
   case BO_XorAssign:
     CheckIdentityFieldAssignment(LHS, RHS, OpLoc, S);
     break;
   default:
     break;
   }
 
   // Find all of the overloaded operators visible from this point.
   UnresolvedSet<16> Functions;
   S.LookupBinOp(Sc, OpLoc, Opc, Functions);
 
   // Build the (potentially-overloaded, potentially-dependent)
   // binary operation.
   return S.CreateOverloadedBinOp(OpLoc, Opc, Functions, LHS, RHS);
 }
 
 ExprResult Sema::BuildBinOp(Scope *S, SourceLocation OpLoc,
                             BinaryOperatorKind Opc,
                             Expr *LHSExpr, Expr *RHSExpr) {
   ExprResult LHS, RHS;
   std::tie(LHS, RHS) = CorrectDelayedTyposInBinOp(*this, Opc, LHSExpr, RHSExpr);
   if (!LHS.isUsable() || !RHS.isUsable())
     return ExprError();
   LHSExpr = LHS.get();
   RHSExpr = RHS.get();
 
   // We want to end up calling one of checkPseudoObjectAssignment
   // (if the LHS is a pseudo-object), BuildOverloadedBinOp (if
   // both expressions are overloadable or either is type-dependent),
   // or CreateBuiltinBinOp (in any other case).  We also want to get
   // any placeholder types out of the way.
 
   // Handle pseudo-objects in the LHS.
   if (const BuiltinType *pty = LHSExpr->getType()->getAsPlaceholderType()) {
     // Assignments with a pseudo-object l-value need special analysis.
     if (pty->getKind() == BuiltinType::PseudoObject &&
         BinaryOperator::isAssignmentOp(Opc))
       return checkPseudoObjectAssignment(S, OpLoc, Opc, LHSExpr, RHSExpr);
 
     // Don't resolve overloads if the other type is overloadable.
     if (getLangOpts().CPlusPlus && pty->getKind() == BuiltinType::Overload) {
       // We can't actually test that if we still have a placeholder,
       // though.  Fortunately, none of the exceptions we see in that
       // code below are valid when the LHS is an overload set.  Note
       // that an overload set can be dependently-typed, but it never
       // instantiates to having an overloadable type.
       ExprResult resolvedRHS = CheckPlaceholderExpr(RHSExpr);
       if (resolvedRHS.isInvalid()) return ExprError();
       RHSExpr = resolvedRHS.get();
 
       if (RHSExpr->isTypeDependent() ||
           RHSExpr->getType()->isOverloadableType())
         return BuildOverloadedBinOp(*this, S, OpLoc, Opc, LHSExpr, RHSExpr);
     }
 
     // If we're instantiating "a.x < b" or "A::x < b" and 'x' names a function
     // template, diagnose the missing 'template' keyword instead of diagnosing
     // an invalid use of a bound member function.
     //
     // Note that "A::x < b" might be valid if 'b' has an overloadable type due
     // to C++1z [over.over]/1.4, but we already checked for that case above.
     if (Opc == BO_LT && inTemplateInstantiation() &&
         (pty->getKind() == BuiltinType::BoundMember ||
          pty->getKind() == BuiltinType::Overload)) {
       auto *OE = dyn_cast<OverloadExpr>(LHSExpr);
       if (OE && !OE->hasTemplateKeyword() && !OE->hasExplicitTemplateArgs() &&
           llvm::any_of(OE->decls(), [](NamedDecl *ND) {
             return isa<FunctionTemplateDecl>(ND);
           })) {
         Diag(OE->getQualifier() ? OE->getQualifierLoc().getBeginLoc()
                                 : OE->getNameLoc(),
              diag::err_template_kw_missing)
           << OE->getName().getAsString() << "";
         return ExprError();
       }
     }
 
     ExprResult LHS = CheckPlaceholderExpr(LHSExpr);
     if (LHS.isInvalid()) return ExprError();
     LHSExpr = LHS.get();
   }
 
   // Handle pseudo-objects in the RHS.
   if (const BuiltinType *pty = RHSExpr->getType()->getAsPlaceholderType()) {
     // An overload in the RHS can potentially be resolved by the type
     // being assigned to.
     if (Opc == BO_Assign && pty->getKind() == BuiltinType::Overload) {
       if (getLangOpts().CPlusPlus &&
           (LHSExpr->isTypeDependent() || RHSExpr->isTypeDependent() ||
            LHSExpr->getType()->isOverloadableType()))
         return BuildOverloadedBinOp(*this, S, OpLoc, Opc, LHSExpr, RHSExpr);
 
       return CreateBuiltinBinOp(OpLoc, Opc, LHSExpr, RHSExpr);
     }
 
     // Don't resolve overloads if the other type is overloadable.
     if (getLangOpts().CPlusPlus && pty->getKind() == BuiltinType::Overload &&
         LHSExpr->getType()->isOverloadableType())
       return BuildOverloadedBinOp(*this, S, OpLoc, Opc, LHSExpr, RHSExpr);
 
     ExprResult resolvedRHS = CheckPlaceholderExpr(RHSExpr);
     if (!resolvedRHS.isUsable()) return ExprError();
     RHSExpr = resolvedRHS.get();
   }
 
   if (getLangOpts().CPlusPlus) {
     // If either expression is type-dependent, always build an
     // overloaded op.
     if (LHSExpr->isTypeDependent() || RHSExpr->isTypeDependent())
       return BuildOverloadedBinOp(*this, S, OpLoc, Opc, LHSExpr, RHSExpr);
 
     // Otherwise, build an overloaded op if either expression has an
     // overloadable type.
     if (LHSExpr->getType()->isOverloadableType() ||
         RHSExpr->getType()->isOverloadableType())
       return BuildOverloadedBinOp(*this, S, OpLoc, Opc, LHSExpr, RHSExpr);
   }
 
   if (getLangOpts().RecoveryAST &&
       (LHSExpr->isTypeDependent() || RHSExpr->isTypeDependent())) {
     assert(!getLangOpts().CPlusPlus);
     assert((LHSExpr->containsErrors() || RHSExpr->containsErrors()) &&
            "Should only occur in error-recovery path.");
     if (BinaryOperator::isCompoundAssignmentOp(Opc))
       // C [6.15.16] p3:
       // An assignment expression has the value of the left operand after the
       // assignment, but is not an lvalue.
       return CompoundAssignOperator::Create(
           Context, LHSExpr, RHSExpr, Opc,
           LHSExpr->getType().getUnqualifiedType(), VK_PRValue, OK_Ordinary,
           OpLoc, CurFPFeatureOverrides());
     QualType ResultType;
     switch (Opc) {
     case BO_Assign:
       ResultType = LHSExpr->getType().getUnqualifiedType();
       break;
     case BO_LT:
     case BO_GT:
     case BO_LE:
     case BO_GE:
     case BO_EQ:
     case BO_NE:
     case BO_LAnd:
     case BO_LOr:
       // These operators have a fixed result type regardless of operands.
       ResultType = Context.IntTy;
       break;
     case BO_Comma:
       ResultType = RHSExpr->getType();
       break;
     default:
       ResultType = Context.DependentTy;
       break;
     }
     return BinaryOperator::Create(Context, LHSExpr, RHSExpr, Opc, ResultType,
                                   VK_PRValue, OK_Ordinary, OpLoc,
                                   CurFPFeatureOverrides());
   }
 
   // Build a built-in binary operation.
   return CreateBuiltinBinOp(OpLoc, Opc, LHSExpr, RHSExpr);
 }
 
 static bool isOverflowingIntegerType(ASTContext &Ctx, QualType T) {
   if (T.isNull() || T->isDependentType())
     return false;
 
   if (!Ctx.isPromotableIntegerType(T))
     return true;
 
   return Ctx.getIntWidth(T) >= Ctx.getIntWidth(Ctx.IntTy);
 }
 
 ExprResult Sema::CreateBuiltinUnaryOp(SourceLocation OpLoc,
                                       UnaryOperatorKind Opc, Expr *InputExpr,
                                       bool IsAfterAmp) {
   ExprResult Input = InputExpr;
   ExprValueKind VK = VK_PRValue;
   ExprObjectKind OK = OK_Ordinary;
   QualType resultType;
   bool CanOverflow = false;
 
   bool ConvertHalfVec = false;
   if (getLangOpts().OpenCL) {
     QualType Ty = InputExpr->getType();
     // The only legal unary operation for atomics is '&'.
     if ((Opc != UO_AddrOf && Ty->isAtomicType()) ||
     // OpenCL special types - image, sampler, pipe, and blocks are to be used
     // only with a builtin functions and therefore should be disallowed here.
         (Ty->isImageType() || Ty->isSamplerT() || Ty->isPipeType()
         || Ty->isBlockPointerType())) {
       return ExprError(Diag(OpLoc, diag::err_typecheck_unary_expr)
                        << InputExpr->getType()
                        << Input.get()->getSourceRange());
     }
   }
 
   if (getLangOpts().HLSL && OpLoc.isValid()) {
     if (Opc == UO_AddrOf)
       return ExprError(Diag(OpLoc, diag::err_hlsl_operator_unsupported) << 0);
     if (Opc == UO_Deref)
       return ExprError(Diag(OpLoc, diag::err_hlsl_operator_unsupported) << 1);
   }
 
   switch (Opc) {
   case UO_PreInc:
   case UO_PreDec:
   case UO_PostInc:
   case UO_PostDec:
     resultType = CheckIncrementDecrementOperand(*this, Input.get(), VK, OK,
                                                 OpLoc,
                                                 Opc == UO_PreInc ||
                                                 Opc == UO_PostInc,
                                                 Opc == UO_PreInc ||
                                                 Opc == UO_PreDec);
     CanOverflow = isOverflowingIntegerType(Context, resultType);
     break;
   case UO_AddrOf:
     resultType = CheckAddressOfOperand(Input, OpLoc);
     CheckAddressOfNoDeref(InputExpr);
     RecordModifiableNonNullParam(*this, InputExpr);
     break;
   case UO_Deref: {
     Input = DefaultFunctionArrayLvalueConversion(Input.get());
     if (Input.isInvalid()) return ExprError();
     resultType =
         CheckIndirectionOperand(*this, Input.get(), VK, OpLoc, IsAfterAmp);
     break;
   }
   case UO_Plus:
   case UO_Minus:
     CanOverflow = Opc == UO_Minus &&
                   isOverflowingIntegerType(Context, Input.get()->getType());
     Input = UsualUnaryConversions(Input.get());
     if (Input.isInvalid()) return ExprError();
     // Unary plus and minus require promoting an operand of half vector to a
     // float vector and truncating the result back to a half vector. For now, we
     // do this only when HalfArgsAndReturns is set (that is, when the target is
     // arm or arm64).
     ConvertHalfVec = needsConversionOfHalfVec(true, Context, Input.get());
 
     // If the operand is a half vector, promote it to a float vector.
     if (ConvertHalfVec)
       Input = convertVector(Input.get(), Context.FloatTy, *this);
     resultType = Input.get()->getType();
     if (resultType->isDependentType())
       break;
     if (resultType->isArithmeticType()) // C99 6.5.3.3p1
       break;
     else if (resultType->isVectorType() &&
              // The z vector extensions don't allow + or - with bool vectors.
              (!Context.getLangOpts().ZVector ||
               resultType->castAs<VectorType>()->getVectorKind() !=
               VectorType::AltiVecBool))
       break;
     else if (resultType->isVLSTBuiltinType()) // SVE vectors allow + and -
       break;
     else if (getLangOpts().CPlusPlus && // C++ [expr.unary.op]p6
              Opc == UO_Plus &&
              resultType->isPointerType())
       break;
 
     return ExprError(Diag(OpLoc, diag::err_typecheck_unary_expr)
       << resultType << Input.get()->getSourceRange());
 
   case UO_Not: // bitwise complement
     Input = UsualUnaryConversions(Input.get());
     if (Input.isInvalid())
       return ExprError();
     resultType = Input.get()->getType();
     if (resultType->isDependentType())
       break;
     // C99 6.5.3.3p1. We allow complex int and float as a GCC extension.
     if (resultType->isComplexType() || resultType->isComplexIntegerType())
       // C99 does not support '~' for complex conjugation.
       Diag(OpLoc, diag::ext_integer_complement_complex)
           << resultType << Input.get()->getSourceRange();
     else if (resultType->hasIntegerRepresentation())
       break;
     else if (resultType->isExtVectorType() && Context.getLangOpts().OpenCL) {
       // OpenCL v1.1 s6.3.f: The bitwise operator not (~) does not operate
       // on vector float types.
       QualType T = resultType->castAs<ExtVectorType>()->getElementType();
       if (!T->isIntegerType())
         return ExprError(Diag(OpLoc, diag::err_typecheck_unary_expr)
                           << resultType << Input.get()->getSourceRange());
     } else {
       return ExprError(Diag(OpLoc, diag::err_typecheck_unary_expr)
                        << resultType << Input.get()->getSourceRange());
     }
     break;
 
   case UO_LNot: // logical negation
     // Unlike +/-/~, integer promotions aren't done here (C99 6.5.3.3p5).
     Input = DefaultFunctionArrayLvalueConversion(Input.get());
     if (Input.isInvalid()) return ExprError();
     resultType = Input.get()->getType();
 
     // Though we still have to promote half FP to float...
     if (resultType->isHalfType() && !Context.getLangOpts().NativeHalfType) {
       Input = ImpCastExprToType(Input.get(), Context.FloatTy, CK_FloatingCast).get();
       resultType = Context.FloatTy;
     }
 
     // WebAsembly tables can't be used in unary expressions.
     if (resultType->isPointerType() &&
         resultType->getPointeeType().isWebAssemblyReferenceType()) {
       return ExprError(Diag(OpLoc, diag::err_typecheck_unary_expr)
                        << resultType << Input.get()->getSourceRange());
     }
 
     if (resultType->isDependentType())
       break;
     if (resultType->isScalarType() && !isScopedEnumerationType(resultType)) {
       // C99 6.5.3.3p1: ok, fallthrough;
       if (Context.getLangOpts().CPlusPlus) {
         // C++03 [expr.unary.op]p8, C++0x [expr.unary.op]p9:
         // operand contextually converted to bool.
         Input = ImpCastExprToType(Input.get(), Context.BoolTy,
                                   ScalarTypeToBooleanCastKind(resultType));
       } else if (Context.getLangOpts().OpenCL &&
                  Context.getLangOpts().OpenCLVersion < 120) {
         // OpenCL v1.1 6.3.h: The logical operator not (!) does not
         // operate on scalar float types.
         if (!resultType->isIntegerType() && !resultType->isPointerType())
           return ExprError(Diag(OpLoc, diag::err_typecheck_unary_expr)
                            << resultType << Input.get()->getSourceRange());
       }
     } else if (resultType->isExtVectorType()) {
       if (Context.getLangOpts().OpenCL &&
           Context.getLangOpts().getOpenCLCompatibleVersion() < 120) {
         // OpenCL v1.1 6.3.h: The logical operator not (!) does not
         // operate on vector float types.
         QualType T = resultType->castAs<ExtVectorType>()->getElementType();
         if (!T->isIntegerType())
           return ExprError(Diag(OpLoc, diag::err_typecheck_unary_expr)
                            << resultType << Input.get()->getSourceRange());
       }
       // Vector logical not returns the signed variant of the operand type.
       resultType = GetSignedVectorType(resultType);
       break;
     } else if (Context.getLangOpts().CPlusPlus && resultType->isVectorType()) {
       const VectorType *VTy = resultType->castAs<VectorType>();
       if (VTy->getVectorKind() != VectorType::GenericVector)
         return ExprError(Diag(OpLoc, diag::err_typecheck_unary_expr)
                          << resultType << Input.get()->getSourceRange());
 
       // Vector logical not returns the signed variant of the operand type.
       resultType = GetSignedVectorType(resultType);
       break;
     } else {
       return ExprError(Diag(OpLoc, diag::err_typecheck_unary_expr)
         << resultType << Input.get()->getSourceRange());
     }
 
     // LNot always has type int. C99 6.5.3.3p5.
     // In C++, it's bool. C++ 5.3.1p8
     resultType = Context.getLogicalOperationType();
     break;
   case UO_Real:
   case UO_Imag:
     resultType = CheckRealImagOperand(*this, Input, OpLoc, Opc == UO_Real);
     // _Real maps ordinary l-values into ordinary l-values. _Imag maps ordinary
     // complex l-values to ordinary l-values and all other values to r-values.
     if (Input.isInvalid()) return ExprError();
     if (Opc == UO_Real || Input.get()->getType()->isAnyComplexType()) {
       if (Input.get()->isGLValue() &&
           Input.get()->getObjectKind() == OK_Ordinary)
         VK = Input.get()->getValueKind();
     } else if (!getLangOpts().CPlusPlus) {
       // In C, a volatile scalar is read by __imag. In C++, it is not.
       Input = DefaultLvalueConversion(Input.get());
     }
     break;
   case UO_Extension:
     resultType = Input.get()->getType();
     VK = Input.get()->getValueKind();
     OK = Input.get()->getObjectKind();
     break;
   case UO_Coawait:
     // It's unnecessary to represent the pass-through operator co_await in the
     // AST; just return the input expression instead.
     assert(!Input.get()->getType()->isDependentType() &&
                    "the co_await expression must be non-dependant before "
                    "building operator co_await");
     return Input;
   }
   if (resultType.isNull() || Input.isInvalid())
     return ExprError();
 
   // Check for array bounds violations in the operand of the UnaryOperator,
   // except for the '*' and '&' operators that have to be handled specially
   // by CheckArrayAccess (as there are special cases like &array[arraysize]
   // that are explicitly defined as valid by the standard).
   if (Opc != UO_AddrOf && Opc != UO_Deref)
     CheckArrayAccess(Input.get());
 
   auto *UO =
       UnaryOperator::Create(Context, Input.get(), Opc, resultType, VK, OK,
                             OpLoc, CanOverflow, CurFPFeatureOverrides());
 
   if (Opc == UO_Deref && UO->getType()->hasAttr(attr::NoDeref) &&
       !isa<ArrayType>(UO->getType().getDesugaredType(Context)) &&
       !isUnevaluatedContext())
     ExprEvalContexts.back().PossibleDerefs.insert(UO);
 
   // Convert the result back to a half vector.
   if (ConvertHalfVec)
     return convertVector(UO, Context.HalfTy, *this);
   return UO;
 }
 
 /// Determine whether the given expression is a qualified member
 /// access expression, of a form that could be turned into a pointer to member
 /// with the address-of operator.
 bool Sema::isQualifiedMemberAccess(Expr *E) {
   if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
     if (!DRE->getQualifier())
       return false;
 
     ValueDecl *VD = DRE->getDecl();
     if (!VD->isCXXClassMember())
       return false;
 
     if (isa<FieldDecl>(VD) || isa<IndirectFieldDecl>(VD))
       return true;
     if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(VD))
       return Method->isInstance();
 
     return false;
   }
 
   if (UnresolvedLookupExpr *ULE = dyn_cast<UnresolvedLookupExpr>(E)) {
     if (!ULE->getQualifier())
       return false;
 
     for (NamedDecl *D : ULE->decls()) {
       if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(D)) {
         if (Method->isInstance())
           return true;
       } else {
         // Overload set does not contain methods.
         break;
       }
     }
 
     return false;
   }
 
   return false;
 }
 
 ExprResult Sema::BuildUnaryOp(Scope *S, SourceLocation OpLoc,
                               UnaryOperatorKind Opc, Expr *Input,
                               bool IsAfterAmp) {
   // First things first: handle placeholders so that the
   // overloaded-operator check considers the right type.
   if (const BuiltinType *pty = Input->getType()->getAsPlaceholderType()) {
     // Increment and decrement of pseudo-object references.
     if (pty->getKind() == BuiltinType::PseudoObject &&
         UnaryOperator::isIncrementDecrementOp(Opc))
       return checkPseudoObjectIncDec(S, OpLoc, Opc, Input);
 
     // extension is always a builtin operator.
     if (Opc == UO_Extension)
       return CreateBuiltinUnaryOp(OpLoc, Opc, Input);
 
     // & gets special logic for several kinds of placeholder.
     // The builtin code knows what to do.
     if (Opc == UO_AddrOf &&
         (pty->getKind() == BuiltinType::Overload ||
          pty->getKind() == BuiltinType::UnknownAny ||
          pty->getKind() == BuiltinType::BoundMember))
       return CreateBuiltinUnaryOp(OpLoc, Opc, Input);
 
     // Anything else needs to be handled now.
     ExprResult Result = CheckPlaceholderExpr(Input);
     if (Result.isInvalid()) return ExprError();
     Input = Result.get();
   }
 
   if (getLangOpts().CPlusPlus && Input->getType()->isOverloadableType() &&
       UnaryOperator::getOverloadedOperator(Opc) != OO_None &&
       !(Opc == UO_AddrOf && isQualifiedMemberAccess(Input))) {
     // Find all of the overloaded operators visible from this point.
     UnresolvedSet<16> Functions;
     OverloadedOperatorKind OverOp = UnaryOperator::getOverloadedOperator(Opc);
     if (S && OverOp != OO_None)
       LookupOverloadedOperatorName(OverOp, S, Functions);
 
     return CreateOverloadedUnaryOp(OpLoc, Opc, Functions, Input);
   }
 
   return CreateBuiltinUnaryOp(OpLoc, Opc, Input, IsAfterAmp);
 }
 
 // Unary Operators.  'Tok' is the token for the operator.
 ExprResult Sema::ActOnUnaryOp(Scope *S, SourceLocation OpLoc, tok::TokenKind Op,
                               Expr *Input, bool IsAfterAmp) {
   return BuildUnaryOp(S, OpLoc, ConvertTokenKindToUnaryOpcode(Op), Input,
                       IsAfterAmp);
 }
 
 /// ActOnAddrLabel - Parse the GNU address of label extension: "&&foo".
 ExprResult Sema::ActOnAddrLabel(SourceLocation OpLoc, SourceLocation LabLoc,
                                 LabelDecl *TheDecl) {
   TheDecl->markUsed(Context);
   // Create the AST node.  The address of a label always has type 'void*'.
   auto *Res = new (Context) AddrLabelExpr(
       OpLoc, LabLoc, TheDecl, Context.getPointerType(Context.VoidTy));
 
   if (getCurFunction())
     getCurFunction()->AddrLabels.push_back(Res);
 
   return Res;
 }
 
 void Sema::ActOnStartStmtExpr() {
   PushExpressionEvaluationContext(ExprEvalContexts.back().Context);
   // Make sure we diagnose jumping into a statement expression.
   setFunctionHasBranchProtectedScope();
 }
 
 void Sema::ActOnStmtExprError() {
   // Note that function is also called by TreeTransform when leaving a
   // StmtExpr scope without rebuilding anything.
 
   DiscardCleanupsInEvaluationContext();
   PopExpressionEvaluationContext();
 }
 
 ExprResult Sema::ActOnStmtExpr(Scope *S, SourceLocation LPLoc, Stmt *SubStmt,
                                SourceLocation RPLoc) {
   return BuildStmtExpr(LPLoc, SubStmt, RPLoc, getTemplateDepth(S));
 }
 
 ExprResult Sema::BuildStmtExpr(SourceLocation LPLoc, Stmt *SubStmt,
                                SourceLocation RPLoc, unsigned TemplateDepth) {
   assert(SubStmt && isa<CompoundStmt>(SubStmt) && "Invalid action invocation!");
   CompoundStmt *Compound = cast<CompoundStmt>(SubStmt);
 
   if (hasAnyUnrecoverableErrorsInThisFunction())
     DiscardCleanupsInEvaluationContext();
   assert(!Cleanup.exprNeedsCleanups() &&
          "cleanups within StmtExpr not correctly bound!");
   PopExpressionEvaluationContext();
 
   // FIXME: there are a variety of strange constraints to enforce here, for
   // example, it is not possible to goto into a stmt expression apparently.
   // More semantic analysis is needed.
 
   // If there are sub-stmts in the compound stmt, take the type of the last one
   // as the type of the stmtexpr.
   QualType Ty = Context.VoidTy;
   bool StmtExprMayBindToTemp = false;
   if (!Compound->body_empty()) {
     // For GCC compatibility we get the last Stmt excluding trailing NullStmts.
     if (const auto *LastStmt =
             dyn_cast<ValueStmt>(Compound->getStmtExprResult())) {
       if (const Expr *Value = LastStmt->getExprStmt()) {
         StmtExprMayBindToTemp = true;
         Ty = Value->getType();
       }
     }
   }
 
   // FIXME: Check that expression type is complete/non-abstract; statement
   // expressions are not lvalues.
   Expr *ResStmtExpr =
       new (Context) StmtExpr(Compound, Ty, LPLoc, RPLoc, TemplateDepth);
   if (StmtExprMayBindToTemp)
     return MaybeBindToTemporary(ResStmtExpr);
   return ResStmtExpr;
 }
 
 ExprResult Sema::ActOnStmtExprResult(ExprResult ER) {
   if (ER.isInvalid())
     return ExprError();
 
   // Do function/array conversion on the last expression, but not
   // lvalue-to-rvalue.  However, initialize an unqualified type.
   ER = DefaultFunctionArrayConversion(ER.get());
   if (ER.isInvalid())
     return ExprError();
   Expr *E = ER.get();
 
   if (E->isTypeDependent())
     return E;
 
   // In ARC, if the final expression ends in a consume, splice
   // the consume out and bind it later.  In the alternate case
   // (when dealing with a retainable type), the result
   // initialization will create a produce.  In both cases the
   // result will be +1, and we'll need to balance that out with
   // a bind.
   auto *Cast = dyn_cast<ImplicitCastExpr>(E);
   if (Cast && Cast->getCastKind() == CK_ARCConsumeObject)
     return Cast->getSubExpr();
 
   // FIXME: Provide a better location for the initialization.
   return PerformCopyInitialization(
       InitializedEntity::InitializeStmtExprResult(
           E->getBeginLoc(), E->getType().getUnqualifiedType()),
       SourceLocation(), E);
 }
 
 ExprResult Sema::BuildBuiltinOffsetOf(SourceLocation BuiltinLoc,
                                       TypeSourceInfo *TInfo,
                                       ArrayRef<OffsetOfComponent> Components,
                                       SourceLocation RParenLoc) {
   QualType ArgTy = TInfo->getType();
   bool Dependent = ArgTy->isDependentType();
   SourceRange TypeRange = TInfo->getTypeLoc().getLocalSourceRange();
 
   // We must have at least one component that refers to the type, and the first
   // one is known to be a field designator.  Verify that the ArgTy represents
   // a struct/union/class.
   if (!Dependent && !ArgTy->isRecordType())
     return ExprError(Diag(BuiltinLoc, diag::err_offsetof_record_type)
                        << ArgTy << TypeRange);
 
   // Type must be complete per C99 7.17p3 because a declaring a variable
   // with an incomplete type would be ill-formed.
   if (!Dependent
       && RequireCompleteType(BuiltinLoc, ArgTy,
                              diag::err_offsetof_incomplete_type, TypeRange))
     return ExprError();
 
   bool DidWarnAboutNonPOD = false;
   QualType CurrentType = ArgTy;
   SmallVector<OffsetOfNode, 4> Comps;
   SmallVector<Expr*, 4> Exprs;
   for (const OffsetOfComponent &OC : Components) {
     if (OC.isBrackets) {
       // Offset of an array sub-field.  TODO: Should we allow vector elements?
       if (!CurrentType->isDependentType()) {
         const ArrayType *AT = Context.getAsArrayType(CurrentType);
         if(!AT)
           return ExprError(Diag(OC.LocEnd, diag::err_offsetof_array_type)
                            << CurrentType);
         CurrentType = AT->getElementType();
       } else
         CurrentType = Context.DependentTy;
 
       ExprResult IdxRval = DefaultLvalueConversion(static_cast<Expr*>(OC.U.E));
       if (IdxRval.isInvalid())
         return ExprError();
       Expr *Idx = IdxRval.get();
 
       // The expression must be an integral expression.
       // FIXME: An integral constant expression?
       if (!Idx->isTypeDependent() && !Idx->isValueDependent() &&
           !Idx->getType()->isIntegerType())
         return ExprError(
             Diag(Idx->getBeginLoc(), diag::err_typecheck_subscript_not_integer)
             << Idx->getSourceRange());
 
       // Record this array index.
       Comps.push_back(OffsetOfNode(OC.LocStart, Exprs.size(), OC.LocEnd));
       Exprs.push_back(Idx);
       continue;
     }
 
     // Offset of a field.
     if (CurrentType->isDependentType()) {
       // We have the offset of a field, but we can't look into the dependent
       // type. Just record the identifier of the field.
       Comps.push_back(OffsetOfNode(OC.LocStart, OC.U.IdentInfo, OC.LocEnd));
       CurrentType = Context.DependentTy;
       continue;
     }
 
     // We need to have a complete type to look into.
     if (RequireCompleteType(OC.LocStart, CurrentType,
                             diag::err_offsetof_incomplete_type))
       return ExprError();
 
     // Look for the designated field.
     const RecordType *RC = CurrentType->getAs<RecordType>();
     if (!RC)
       return ExprError(Diag(OC.LocEnd, diag::err_offsetof_record_type)
                        << CurrentType);
     RecordDecl *RD = RC->getDecl();
 
     // C++ [lib.support.types]p5:
     //   The macro offsetof accepts a restricted set of type arguments in this
     //   International Standard. type shall be a POD structure or a POD union
     //   (clause 9).
     // C++11 [support.types]p4:
     //   If type is not a standard-layout class (Clause 9), the results are
     //   undefined.
     if (CXXRecordDecl *CRD = dyn_cast<CXXRecordDecl>(RD)) {
       bool IsSafe = LangOpts.CPlusPlus11? CRD->isStandardLayout() : CRD->isPOD();
       unsigned DiagID =
         LangOpts.CPlusPlus11? diag::ext_offsetof_non_standardlayout_type
                             : diag::ext_offsetof_non_pod_type;
 
       if (!IsSafe && !DidWarnAboutNonPOD &&
           DiagRuntimeBehavior(BuiltinLoc, nullptr,
                               PDiag(DiagID)
                               << SourceRange(Components[0].LocStart, OC.LocEnd)
                               << CurrentType))
         DidWarnAboutNonPOD = true;
     }
 
     // Look for the field.
     LookupResult R(*this, OC.U.IdentInfo, OC.LocStart, LookupMemberName);
     LookupQualifiedName(R, RD);
     FieldDecl *MemberDecl = R.getAsSingle<FieldDecl>();
     IndirectFieldDecl *IndirectMemberDecl = nullptr;
     if (!MemberDecl) {
       if ((IndirectMemberDecl = R.getAsSingle<IndirectFieldDecl>()))
         MemberDecl = IndirectMemberDecl->getAnonField();
     }
 
     if (!MemberDecl)
       return ExprError(Diag(BuiltinLoc, diag::err_no_member)
                        << OC.U.IdentInfo << RD << SourceRange(OC.LocStart,
                                                               OC.LocEnd));
 
     // C99 7.17p3:
     //   (If the specified member is a bit-field, the behavior is undefined.)
     //
     // We diagnose this as an error.
     if (MemberDecl->isBitField()) {
       Diag(OC.LocEnd, diag::err_offsetof_bitfield)
         << MemberDecl->getDeclName()
         << SourceRange(BuiltinLoc, RParenLoc);
       Diag(MemberDecl->getLocation(), diag::note_bitfield_decl);
       return ExprError();
     }
 
     RecordDecl *Parent = MemberDecl->getParent();
     if (IndirectMemberDecl)
       Parent = cast<RecordDecl>(IndirectMemberDecl->getDeclContext());
 
     // If the member was found in a base class, introduce OffsetOfNodes for
     // the base class indirections.
     CXXBasePaths Paths;
     if (IsDerivedFrom(OC.LocStart, CurrentType, Context.getTypeDeclType(Parent),
                       Paths)) {
       if (Paths.getDetectedVirtual()) {
         Diag(OC.LocEnd, diag::err_offsetof_field_of_virtual_base)
           << MemberDecl->getDeclName()
           << SourceRange(BuiltinLoc, RParenLoc);
         return ExprError();
       }
 
       CXXBasePath &Path = Paths.front();
       for (const CXXBasePathElement &B : Path)
         Comps.push_back(OffsetOfNode(B.Base));
     }
 
     if (IndirectMemberDecl) {
       for (auto *FI : IndirectMemberDecl->chain()) {
         assert(isa<FieldDecl>(FI));
         Comps.push_back(OffsetOfNode(OC.LocStart,
                                      cast<FieldDecl>(FI), OC.LocEnd));
       }
     } else
       Comps.push_back(OffsetOfNode(OC.LocStart, MemberDecl, OC.LocEnd));
 
     CurrentType = MemberDecl->getType().getNonReferenceType();
   }
 
   return OffsetOfExpr::Create(Context, Context.getSizeType(), BuiltinLoc, TInfo,
                               Comps, Exprs, RParenLoc);
 }
 
 ExprResult Sema::ActOnBuiltinOffsetOf(Scope *S,
                                       SourceLocation BuiltinLoc,
                                       SourceLocation TypeLoc,
                                       ParsedType ParsedArgTy,
                                       ArrayRef<OffsetOfComponent> Components,
                                       SourceLocation RParenLoc) {
 
   TypeSourceInfo *ArgTInfo;
   QualType ArgTy = GetTypeFromParser(ParsedArgTy, &ArgTInfo);
   if (ArgTy.isNull())
     return ExprError();
 
   if (!ArgTInfo)
     ArgTInfo = Context.getTrivialTypeSourceInfo(ArgTy, TypeLoc);
 
   return BuildBuiltinOffsetOf(BuiltinLoc, ArgTInfo, Components, RParenLoc);
 }
 
 
 ExprResult Sema::ActOnChooseExpr(SourceLocation BuiltinLoc,
                                  Expr *CondExpr,
                                  Expr *LHSExpr, Expr *RHSExpr,
                                  SourceLocation RPLoc) {
   assert((CondExpr && LHSExpr && RHSExpr) && "Missing type argument(s)");
 
   ExprValueKind VK = VK_PRValue;
   ExprObjectKind OK = OK_Ordinary;
   QualType resType;
   bool CondIsTrue = false;
   if (CondExpr->isTypeDependent() || CondExpr->isValueDependent()) {
     resType = Context.DependentTy;
   } else {
     // The conditional expression is required to be a constant expression.
     llvm::APSInt condEval(32);
     ExprResult CondICE = VerifyIntegerConstantExpression(
         CondExpr, &condEval, diag::err_typecheck_choose_expr_requires_constant);
     if (CondICE.isInvalid())
       return ExprError();
     CondExpr = CondICE.get();
     CondIsTrue = condEval.getZExtValue();
 
     // If the condition is > zero, then the AST type is the same as the LHSExpr.
     Expr *ActiveExpr = CondIsTrue ? LHSExpr : RHSExpr;
 
     resType = ActiveExpr->getType();
     VK = ActiveExpr->getValueKind();
     OK = ActiveExpr->getObjectKind();
   }
 
   return new (Context) ChooseExpr(BuiltinLoc, CondExpr, LHSExpr, RHSExpr,
                                   resType, VK, OK, RPLoc, CondIsTrue);
 }
 
 //===----------------------------------------------------------------------===//
 // Clang Extensions.
 //===----------------------------------------------------------------------===//
 
 /// ActOnBlockStart - This callback is invoked when a block literal is started.
 void Sema::ActOnBlockStart(SourceLocation CaretLoc, Scope *CurScope) {
   BlockDecl *Block = BlockDecl::Create(Context, CurContext, CaretLoc);
 
   if (LangOpts.CPlusPlus) {
     MangleNumberingContext *MCtx;
     Decl *ManglingContextDecl;
     std::tie(MCtx, ManglingContextDecl) =
         getCurrentMangleNumberContext(Block->getDeclContext());
     if (MCtx) {
       unsigned ManglingNumber = MCtx->getManglingNumber(Block);
       Block->setBlockMangling(ManglingNumber, ManglingContextDecl);
     }
   }
 
   PushBlockScope(CurScope, Block);
   CurContext->addDecl(Block);
   if (CurScope)
     PushDeclContext(CurScope, Block);
   else
     CurContext = Block;
 
   getCurBlock()->HasImplicitReturnType = true;
 
   // Enter a new evaluation context to insulate the block from any
   // cleanups from the enclosing full-expression.
   PushExpressionEvaluationContext(
       ExpressionEvaluationContext::PotentiallyEvaluated);
 }
 
 void Sema::ActOnBlockArguments(SourceLocation CaretLoc, Declarator &ParamInfo,
                                Scope *CurScope) {
   assert(ParamInfo.getIdentifier() == nullptr &&
          "block-id should have no identifier!");
   assert(ParamInfo.getContext() == DeclaratorContext::BlockLiteral);
   BlockScopeInfo *CurBlock = getCurBlock();
 
   TypeSourceInfo *Sig = GetTypeForDeclarator(ParamInfo, CurScope);
   QualType T = Sig->getType();
 
   // FIXME: We should allow unexpanded parameter packs here, but that would,
   // in turn, make the block expression contain unexpanded parameter packs.
   if (DiagnoseUnexpandedParameterPack(CaretLoc, Sig, UPPC_Block)) {
     // Drop the parameters.
     FunctionProtoType::ExtProtoInfo EPI;
     EPI.HasTrailingReturn = false;
     EPI.TypeQuals.addConst();
     T = Context.getFunctionType(Context.DependentTy, std::nullopt, EPI);
     Sig = Context.getTrivialTypeSourceInfo(T);
   }
 
   // GetTypeForDeclarator always produces a function type for a block
   // literal signature.  Furthermore, it is always a FunctionProtoType
   // unless the function was written with a typedef.
   assert(T->isFunctionType() &&
          "GetTypeForDeclarator made a non-function block signature");
 
   // Look for an explicit signature in that function type.
   FunctionProtoTypeLoc ExplicitSignature;
 
   if ((ExplicitSignature = Sig->getTypeLoc()
                                .getAsAdjusted<FunctionProtoTypeLoc>())) {
 
     // Check whether that explicit signature was synthesized by
     // GetTypeForDeclarator.  If so, don't save that as part of the
     // written signature.
     if (ExplicitSignature.getLocalRangeBegin() ==
         ExplicitSignature.getLocalRangeEnd()) {
       // This would be much cheaper if we stored TypeLocs instead of
       // TypeSourceInfos.
       TypeLoc Result = ExplicitSignature.getReturnLoc();
       unsigned Size = Result.getFullDataSize();
       Sig = Context.CreateTypeSourceInfo(Result.getType(), Size);
       Sig->getTypeLoc().initializeFullCopy(Result, Size);
 
       ExplicitSignature = FunctionProtoTypeLoc();
     }
   }
 
   CurBlock->TheDecl->setSignatureAsWritten(Sig);
   CurBlock->FunctionType = T;
 
   const auto *Fn = T->castAs<FunctionType>();
   QualType RetTy = Fn->getReturnType();
   bool isVariadic =
       (isa<FunctionProtoType>(Fn) && cast<FunctionProtoType>(Fn)->isVariadic());
 
   CurBlock->TheDecl->setIsVariadic(isVariadic);
 
   // Context.DependentTy is used as a placeholder for a missing block
   // return type.  TODO:  what should we do with declarators like:
   //   ^ * { ... }
   // If the answer is "apply template argument deduction"....
   if (RetTy != Context.DependentTy) {
     CurBlock->ReturnType = RetTy;
     CurBlock->TheDecl->setBlockMissingReturnType(false);
     CurBlock->HasImplicitReturnType = false;
   }
 
   // Push block parameters from the declarator if we had them.
   SmallVector<ParmVarDecl*, 8> Params;
   if (ExplicitSignature) {
     for (unsigned I = 0, E = ExplicitSignature.getNumParams(); I != E; ++I) {
       ParmVarDecl *Param = ExplicitSignature.getParam(I);
       if (Param->getIdentifier() == nullptr && !Param->isImplicit() &&
           !Param->isInvalidDecl() && !getLangOpts().CPlusPlus) {
         // Diagnose this as an extension in C17 and earlier.
         if (!getLangOpts().C2x)
           Diag(Param->getLocation(), diag::ext_parameter_name_omitted_c2x);
       }
       Params.push_back(Param);
     }
 
   // Fake up parameter variables if we have a typedef, like
   //   ^ fntype { ... }
   } else if (const FunctionProtoType *Fn = T->getAs<FunctionProtoType>()) {
     for (const auto &I : Fn->param_types()) {
       ParmVarDecl *Param = BuildParmVarDeclForTypedef(
           CurBlock->TheDecl, ParamInfo.getBeginLoc(), I);
       Params.push_back(Param);
     }
   }
 
   // Set the parameters on the block decl.
   if (!Params.empty()) {
     CurBlock->TheDecl->setParams(Params);
     CheckParmsForFunctionDef(CurBlock->TheDecl->parameters(),
                              /*CheckParameterNames=*/false);
   }
 
   // Finally we can process decl attributes.
   ProcessDeclAttributes(CurScope, CurBlock->TheDecl, ParamInfo);
 
   // Put the parameter variables in scope.
   for (auto *AI : CurBlock->TheDecl->parameters()) {
     AI->setOwningFunction(CurBlock->TheDecl);
 
     // If this has an identifier, add it to the scope stack.
     if (AI->getIdentifier()) {
       CheckShadow(CurBlock->TheScope, AI);
 
       PushOnScopeChains(AI, CurBlock->TheScope);
     }
 
     if (AI->isInvalidDecl())
       CurBlock->TheDecl->setInvalidDecl();
   }
 }
 
 /// ActOnBlockError - If there is an error parsing a block, this callback
 /// is invoked to pop the information about the block from the action impl.
 void Sema::ActOnBlockError(SourceLocation CaretLoc, Scope *CurScope) {
   // Leave the expression-evaluation context.
   DiscardCleanupsInEvaluationContext();
   PopExpressionEvaluationContext();
 
   // Pop off CurBlock, handle nested blocks.
   PopDeclContext();
   PopFunctionScopeInfo();
 }
 
 /// ActOnBlockStmtExpr - This is called when the body of a block statement
 /// literal was successfully completed.  ^(int x){...}
 ExprResult Sema::ActOnBlockStmtExpr(SourceLocation CaretLoc,
                                     Stmt *Body, Scope *CurScope) {
   // If blocks are disabled, emit an error.
   if (!LangOpts.Blocks)
     Diag(CaretLoc, diag::err_blocks_disable) << LangOpts.OpenCL;
 
   // Leave the expression-evaluation context.
   if (hasAnyUnrecoverableErrorsInThisFunction())
     DiscardCleanupsInEvaluationContext();
   assert(!Cleanup.exprNeedsCleanups() &&
          "cleanups within block not correctly bound!");
   PopExpressionEvaluationContext();
 
   BlockScopeInfo *BSI = cast<BlockScopeInfo>(FunctionScopes.back());
   BlockDecl *BD = BSI->TheDecl;
 
   if (BSI->HasImplicitReturnType)
     deduceClosureReturnType(*BSI);
 
   QualType RetTy = Context.VoidTy;
   if (!BSI->ReturnType.isNull())
     RetTy = BSI->ReturnType;
 
   bool NoReturn = BD->hasAttr<NoReturnAttr>();
   QualType BlockTy;
 
   // If the user wrote a function type in some form, try to use that.
   if (!BSI->FunctionType.isNull()) {
     const FunctionType *FTy = BSI->FunctionType->castAs<FunctionType>();
 
     FunctionType::ExtInfo Ext = FTy->getExtInfo();
     if (NoReturn && !Ext.getNoReturn()) Ext = Ext.withNoReturn(true);
 
     // Turn protoless block types into nullary block types.
     if (isa<FunctionNoProtoType>(FTy)) {
       FunctionProtoType::ExtProtoInfo EPI;
       EPI.ExtInfo = Ext;
       BlockTy = Context.getFunctionType(RetTy, std::nullopt, EPI);
 
       // Otherwise, if we don't need to change anything about the function type,
       // preserve its sugar structure.
     } else if (FTy->getReturnType() == RetTy &&
                (!NoReturn || FTy->getNoReturnAttr())) {
       BlockTy = BSI->FunctionType;
 
     // Otherwise, make the minimal modifications to the function type.
     } else {
       const FunctionProtoType *FPT = cast<FunctionProtoType>(FTy);
       FunctionProtoType::ExtProtoInfo EPI = FPT->getExtProtoInfo();
       EPI.TypeQuals = Qualifiers();
       EPI.ExtInfo = Ext;
       BlockTy = Context.getFunctionType(RetTy, FPT->getParamTypes(), EPI);
     }
 
   // If we don't have a function type, just build one from nothing.
   } else {
     FunctionProtoType::ExtProtoInfo EPI;
     EPI.ExtInfo = FunctionType::ExtInfo().withNoReturn(NoReturn);
     BlockTy = Context.getFunctionType(RetTy, std::nullopt, EPI);
   }
 
   DiagnoseUnusedParameters(BD->parameters());
   BlockTy = Context.getBlockPointerType(BlockTy);
 
   // If needed, diagnose invalid gotos and switches in the block.
   if (getCurFunction()->NeedsScopeChecking() &&
       !PP.isCodeCompletionEnabled())
     DiagnoseInvalidJumps(cast<CompoundStmt>(Body));
 
   BD->setBody(cast<CompoundStmt>(Body));
 
   if (Body && getCurFunction()->HasPotentialAvailabilityViolations)
     DiagnoseUnguardedAvailabilityViolations(BD);
 
   // Try to apply the named return value optimization. We have to check again
   // if we can do this, though, because blocks keep return statements around
   // to deduce an implicit return type.
   if (getLangOpts().CPlusPlus && RetTy->isRecordType() &&
       !BD->isDependentContext())
     computeNRVO(Body, BSI);
 
   if (RetTy.hasNonTrivialToPrimitiveDestructCUnion() ||
       RetTy.hasNonTrivialToPrimitiveCopyCUnion())
     checkNonTrivialCUnion(RetTy, BD->getCaretLocation(), NTCUC_FunctionReturn,
                           NTCUK_Destruct|NTCUK_Copy);
 
   PopDeclContext();
 
   // Set the captured variables on the block.
   SmallVector<BlockDecl::Capture, 4> Captures;
   for (Capture &Cap : BSI->Captures) {
     if (Cap.isInvalid() || Cap.isThisCapture())
       continue;
     // Cap.getVariable() is always a VarDecl because
     // blocks cannot capture structured bindings or other ValueDecl kinds.
     auto *Var = cast<VarDecl>(Cap.getVariable());
     Expr *CopyExpr = nullptr;
     if (getLangOpts().CPlusPlus && Cap.isCopyCapture()) {
       if (const RecordType *Record =
               Cap.getCaptureType()->getAs<RecordType>()) {
         // The capture logic needs the destructor, so make sure we mark it.
         // Usually this is unnecessary because most local variables have
         // their destructors marked at declaration time, but parameters are
         // an exception because it's technically only the call site that
         // actually requires the destructor.
         if (isa<ParmVarDecl>(Var))
           FinalizeVarWithDestructor(Var, Record);
 
         // Enter a separate potentially-evaluated context while building block
         // initializers to isolate their cleanups from those of the block
         // itself.
         // FIXME: Is this appropriate even when the block itself occurs in an
         // unevaluated operand?
         EnterExpressionEvaluationContext EvalContext(
             *this, ExpressionEvaluationContext::PotentiallyEvaluated);
 
         SourceLocation Loc = Cap.getLocation();
 
         ExprResult Result = BuildDeclarationNameExpr(
             CXXScopeSpec(), DeclarationNameInfo(Var->getDeclName(), Loc), Var);
 
         // According to the blocks spec, the capture of a variable from
         // the stack requires a const copy constructor.  This is not true
         // of the copy/move done to move a __block variable to the heap.
         if (!Result.isInvalid() &&
             !Result.get()->getType().isConstQualified()) {
           Result = ImpCastExprToType(Result.get(),
                                      Result.get()->getType().withConst(),
                                      CK_NoOp, VK_LValue);
         }
 
         if (!Result.isInvalid()) {
           Result = PerformCopyInitialization(
               InitializedEntity::InitializeBlock(Var->getLocation(),
                                                  Cap.getCaptureType()),
               Loc, Result.get());
         }
 
         // Build a full-expression copy expression if initialization
         // succeeded and used a non-trivial constructor.  Recover from
         // errors by pretending that the copy isn't necessary.
         if (!Result.isInvalid() &&
             !cast<CXXConstructExpr>(Result.get())->getConstructor()
                 ->isTrivial()) {
           Result = MaybeCreateExprWithCleanups(Result);
           CopyExpr = Result.get();
         }
       }
     }
 
     BlockDecl::Capture NewCap(Var, Cap.isBlockCapture(), Cap.isNested(),
                               CopyExpr);
     Captures.push_back(NewCap);
   }
   BD->setCaptures(Context, Captures, BSI->CXXThisCaptureIndex != 0);
 
   // Pop the block scope now but keep it alive to the end of this function.
   AnalysisBasedWarnings::Policy WP = AnalysisWarnings.getDefaultPolicy();
   PoppedFunctionScopePtr ScopeRAII = PopFunctionScopeInfo(&WP, BD, BlockTy);
 
   BlockExpr *Result = new (Context) BlockExpr(BD, BlockTy);
 
   // If the block isn't obviously global, i.e. it captures anything at
   // all, then we need to do a few things in the surrounding context:
   if (Result->getBlockDecl()->hasCaptures()) {
     // First, this expression has a new cleanup object.
     ExprCleanupObjects.push_back(Result->getBlockDecl());
     Cleanup.setExprNeedsCleanups(true);
 
     // It also gets a branch-protected scope if any of the captured
     // variables needs destruction.
     for (const auto &CI : Result->getBlockDecl()->captures()) {
       const VarDecl *var = CI.getVariable();
       if (var->getType().isDestructedType() != QualType::DK_none) {
         setFunctionHasBranchProtectedScope();
         break;
       }
     }
   }
 
   if (getCurFunction())
     getCurFunction()->addBlock(BD);
 
   if (BD->isInvalidDecl())
     return CreateRecoveryExpr(Result->getBeginLoc(), Result->getEndLoc(),
                               {Result}, Result->getType());
   return Result;
 }
 
 ExprResult Sema::ActOnVAArg(SourceLocation BuiltinLoc, Expr *E, ParsedType Ty,
                             SourceLocation RPLoc) {
   TypeSourceInfo *TInfo;
   GetTypeFromParser(Ty, &TInfo);
   return BuildVAArgExpr(BuiltinLoc, E, TInfo, RPLoc);
 }
 
 ExprResult Sema::BuildVAArgExpr(SourceLocation BuiltinLoc,
                                 Expr *E, TypeSourceInfo *TInfo,
                                 SourceLocation RPLoc) {
   Expr *OrigExpr = E;
   bool IsMS = false;
 
   // CUDA device code does not support varargs.
   if (getLangOpts().CUDA && getLangOpts().CUDAIsDevice) {
     if (const FunctionDecl *F = dyn_cast<FunctionDecl>(CurContext)) {
       CUDAFunctionTarget T = IdentifyCUDATarget(F);
       if (T == CFT_Global || T == CFT_Device || T == CFT_HostDevice)
         return ExprError(Diag(E->getBeginLoc(), diag::err_va_arg_in_device));
     }
   }
 
   // NVPTX does not support va_arg expression.
   if (getLangOpts().OpenMP && getLangOpts().OpenMPIsTargetDevice &&
       Context.getTargetInfo().getTriple().isNVPTX())
     targetDiag(E->getBeginLoc(), diag::err_va_arg_in_device);
 
   // It might be a __builtin_ms_va_list. (But don't ever mark a va_arg()
   // as Microsoft ABI on an actual Microsoft platform, where
   // __builtin_ms_va_list and __builtin_va_list are the same.)
   if (!E->isTypeDependent() && Context.getTargetInfo().hasBuiltinMSVaList() &&
       Context.getTargetInfo().getBuiltinVaListKind() != TargetInfo::CharPtrBuiltinVaList) {
     QualType MSVaListType = Context.getBuiltinMSVaListType();
     if (Context.hasSameType(MSVaListType, E->getType())) {
       if (CheckForModifiableLvalue(E, BuiltinLoc, *this))
         return ExprError();
       IsMS = true;
     }
   }
 
   // Get the va_list type
   QualType VaListType = Context.getBuiltinVaListType();
   if (!IsMS) {
     if (VaListType->isArrayType()) {
       // Deal with implicit array decay; for example, on x86-64,
       // va_list is an array, but it's supposed to decay to
       // a pointer for va_arg.
       VaListType = Context.getArrayDecayedType(VaListType);
       // Make sure the input expression also decays appropriately.
       ExprResult Result = UsualUnaryConversions(E);
       if (Result.isInvalid())
         return ExprError();
       E = Result.get();
     } else if (VaListType->isRecordType() && getLangOpts().CPlusPlus) {
       // If va_list is a record type and we are compiling in C++ mode,
       // check the argument using reference binding.
       InitializedEntity Entity = InitializedEntity::InitializeParameter(
           Context, Context.getLValueReferenceType(VaListType), false);
       ExprResult Init = PerformCopyInitialization(Entity, SourceLocation(), E);
       if (Init.isInvalid())
         return ExprError();
       E = Init.getAs<Expr>();
     } else {
       // Otherwise, the va_list argument must be an l-value because
       // it is modified by va_arg.
       if (!E->isTypeDependent() &&
           CheckForModifiableLvalue(E, BuiltinLoc, *this))
         return ExprError();
     }
   }
 
   if (!IsMS && !E->isTypeDependent() &&
       !Context.hasSameType(VaListType, E->getType()))
     return ExprError(
         Diag(E->getBeginLoc(),
              diag::err_first_argument_to_va_arg_not_of_type_va_list)
         << OrigExpr->getType() << E->getSourceRange());
 
   if (!TInfo->getType()->isDependentType()) {
     if (RequireCompleteType(TInfo->getTypeLoc().getBeginLoc(), TInfo->getType(),
                             diag::err_second_parameter_to_va_arg_incomplete,
                             TInfo->getTypeLoc()))
       return ExprError();
 
     if (RequireNonAbstractType(TInfo->getTypeLoc().getBeginLoc(),
                                TInfo->getType(),
                                diag::err_second_parameter_to_va_arg_abstract,
                                TInfo->getTypeLoc()))
       return ExprError();
 
     if (!TInfo->getType().isPODType(Context)) {
       Diag(TInfo->getTypeLoc().getBeginLoc(),
            TInfo->getType()->isObjCLifetimeType()
              ? diag::warn_second_parameter_to_va_arg_ownership_qualified
              : diag::warn_second_parameter_to_va_arg_not_pod)
         << TInfo->getType()
         << TInfo->getTypeLoc().getSourceRange();
     }
 
     // Check for va_arg where arguments of the given type will be promoted
     // (i.e. this va_arg is guaranteed to have undefined behavior).
     QualType PromoteType;
     if (Context.isPromotableIntegerType(TInfo->getType())) {
       PromoteType = Context.getPromotedIntegerType(TInfo->getType());
       // [cstdarg.syn]p1 defers the C++ behavior to what the C standard says,
       // and C2x 7.16.1.1p2 says, in part:
       //   If type is not compatible with the type of the actual next argument
       //   (as promoted according to the default argument promotions), the
       //   behavior is undefined, except for the following cases:
       //     - both types are pointers to qualified or unqualified versions of
       //       compatible types;
       //     - one type is a signed integer type, the other type is the
       //       corresponding unsigned integer type, and the value is
       //       representable in both types;
       //     - one type is pointer to qualified or unqualified void and the
       //       other is a pointer to a qualified or unqualified character type.
       // Given that type compatibility is the primary requirement (ignoring
       // qualifications), you would think we could call typesAreCompatible()
       // directly to test this. However, in C++, that checks for *same type*,
       // which causes false positives when passing an enumeration type to
       // va_arg. Instead, get the underlying type of the enumeration and pass
       // that.
       QualType UnderlyingType = TInfo->getType();
       if (const auto *ET = UnderlyingType->getAs<EnumType>())
         UnderlyingType = ET->getDecl()->getIntegerType();
       if (Context.typesAreCompatible(PromoteType, UnderlyingType,
                                      /*CompareUnqualified*/ true))
         PromoteType = QualType();
 
       // If the types are still not compatible, we need to test whether the
       // promoted type and the underlying type are the same except for
       // signedness. Ask the AST for the correctly corresponding type and see
       // if that's compatible.
       if (!PromoteType.isNull() && !UnderlyingType->isBooleanType() &&
           PromoteType->isUnsignedIntegerType() !=
               UnderlyingType->isUnsignedIntegerType()) {
         UnderlyingType =
             UnderlyingType->isUnsignedIntegerType()
                 ? Context.getCorrespondingSignedType(UnderlyingType)
                 : Context.getCorrespondingUnsignedType(UnderlyingType);
         if (Context.typesAreCompatible(PromoteType, UnderlyingType,
                                        /*CompareUnqualified*/ true))
           PromoteType = QualType();
       }
     }
     if (TInfo->getType()->isSpecificBuiltinType(BuiltinType::Float))
       PromoteType = Context.DoubleTy;
     if (!PromoteType.isNull())
       DiagRuntimeBehavior(TInfo->getTypeLoc().getBeginLoc(), E,
                   PDiag(diag::warn_second_parameter_to_va_arg_never_compatible)
                           << TInfo->getType()
                           << PromoteType
                           << TInfo->getTypeLoc().getSourceRange());
   }
 
   QualType T = TInfo->getType().getNonLValueExprType(Context);
   return new (Context) VAArgExpr(BuiltinLoc, E, TInfo, RPLoc, T, IsMS);
 }
 
 ExprResult Sema::ActOnGNUNullExpr(SourceLocation TokenLoc) {
   // The type of __null will be int or long, depending on the size of
   // pointers on the target.
   QualType Ty;
   unsigned pw = Context.getTargetInfo().getPointerWidth(LangAS::Default);
   if (pw == Context.getTargetInfo().getIntWidth())
     Ty = Context.IntTy;
   else if (pw == Context.getTargetInfo().getLongWidth())
     Ty = Context.LongTy;
   else if (pw == Context.getTargetInfo().getLongLongWidth())
     Ty = Context.LongLongTy;
   else {
     llvm_unreachable("I don't know size of pointer!");
   }
 
   return new (Context) GNUNullExpr(Ty, TokenLoc);
 }
 
 static CXXRecordDecl *LookupStdSourceLocationImpl(Sema &S, SourceLocation Loc) {
   CXXRecordDecl *ImplDecl = nullptr;
 
   // Fetch the std::source_location::__impl decl.
   if (NamespaceDecl *Std = S.getStdNamespace()) {
     LookupResult ResultSL(S, &S.PP.getIdentifierTable().get("source_location"),
                           Loc, Sema::LookupOrdinaryName);
     if (S.LookupQualifiedName(ResultSL, Std)) {
       if (auto *SLDecl = ResultSL.getAsSingle<RecordDecl>()) {
         LookupResult ResultImpl(S, &S.PP.getIdentifierTable().get("__impl"),
                                 Loc, Sema::LookupOrdinaryName);
         if ((SLDecl->isCompleteDefinition() || SLDecl->isBeingDefined()) &&
             S.LookupQualifiedName(ResultImpl, SLDecl)) {
           ImplDecl = ResultImpl.getAsSingle<CXXRecordDecl>();
         }
       }
     }
   }
 
   if (!ImplDecl || !ImplDecl->isCompleteDefinition()) {
     S.Diag(Loc, diag::err_std_source_location_impl_not_found);
     return nullptr;
   }
 
   // Verify that __impl is a trivial struct type, with no base classes, and with
   // only the four expected fields.
   if (ImplDecl->isUnion() || !ImplDecl->isStandardLayout() ||
       ImplDecl->getNumBases() != 0) {
     S.Diag(Loc, diag::err_std_source_location_impl_malformed);
     return nullptr;
   }
 
   unsigned Count = 0;
   for (FieldDecl *F : ImplDecl->fields()) {
     StringRef Name = F->getName();
 
     if (Name == "_M_file_name") {
       if (F->getType() !=
           S.Context.getPointerType(S.Context.CharTy.withConst()))
         break;
       Count++;
     } else if (Name == "_M_function_name") {
       if (F->getType() !=
           S.Context.getPointerType(S.Context.CharTy.withConst()))
         break;
       Count++;
     } else if (Name == "_M_line") {
       if (!F->getType()->isIntegerType())
         break;
       Count++;
     } else if (Name == "_M_column") {
       if (!F->getType()->isIntegerType())
         break;
       Count++;
     } else {
       Count = 100; // invalid
       break;
     }
   }
   if (Count != 4) {
     S.Diag(Loc, diag::err_std_source_location_impl_malformed);
     return nullptr;
   }
 
   return ImplDecl;
 }
 
 ExprResult Sema::ActOnSourceLocExpr(SourceLocExpr::IdentKind Kind,
                                     SourceLocation BuiltinLoc,
                                     SourceLocation RPLoc) {
   QualType ResultTy;
   switch (Kind) {
   case SourceLocExpr::File:
   case SourceLocExpr::FileName:
   case SourceLocExpr::Function:
   case SourceLocExpr::FuncSig: {
     QualType ArrTy = Context.getStringLiteralArrayType(Context.CharTy, 0);
     ResultTy =
         Context.getPointerType(ArrTy->getAsArrayTypeUnsafe()->getElementType());
     break;
   }
   case SourceLocExpr::Line:
   case SourceLocExpr::Column:
     ResultTy = Context.UnsignedIntTy;
     break;
   case SourceLocExpr::SourceLocStruct:
     if (!StdSourceLocationImplDecl) {
       StdSourceLocationImplDecl =
           LookupStdSourceLocationImpl(*this, BuiltinLoc);
       if (!StdSourceLocationImplDecl)
         return ExprError();
     }
     ResultTy = Context.getPointerType(
         Context.getRecordType(StdSourceLocationImplDecl).withConst());
     break;
   }
 
   return BuildSourceLocExpr(Kind, ResultTy, BuiltinLoc, RPLoc, CurContext);
 }
 
 ExprResult Sema::BuildSourceLocExpr(SourceLocExpr::IdentKind Kind,
                                     QualType ResultTy,
                                     SourceLocation BuiltinLoc,
                                     SourceLocation RPLoc,
                                     DeclContext *ParentContext) {
   return new (Context)
       SourceLocExpr(Context, Kind, ResultTy, BuiltinLoc, RPLoc, ParentContext);
 }
 
 bool Sema::CheckConversionToObjCLiteral(QualType DstType, Expr *&Exp,
                                         bool Diagnose) {
   if (!getLangOpts().ObjC)
     return false;
 
   const ObjCObjectPointerType *PT = DstType->getAs<ObjCObjectPointerType>();
   if (!PT)
     return false;
   const ObjCInterfaceDecl *ID = PT->getInterfaceDecl();
 
   // Ignore any parens, implicit casts (should only be
   // array-to-pointer decays), and not-so-opaque values.  The last is
   // important for making this trigger for property assignments.
   Expr *SrcExpr = Exp->IgnoreParenImpCasts();
   if (OpaqueValueExpr *OV = dyn_cast<OpaqueValueExpr>(SrcExpr))
     if (OV->getSourceExpr())
       SrcExpr = OV->getSourceExpr()->IgnoreParenImpCasts();
 
   if (auto *SL = dyn_cast<StringLiteral>(SrcExpr)) {
     if (!PT->isObjCIdType() &&
         !(ID && ID->getIdentifier()->isStr("NSString")))
       return false;
     if (!SL->isOrdinary())
       return false;
 
     if (Diagnose) {
       Diag(SL->getBeginLoc(), diag::err_missing_atsign_prefix)
           << /*string*/0 << FixItHint::CreateInsertion(SL->getBeginLoc(), "@");
       Exp = BuildObjCStringLiteral(SL->getBeginLoc(), SL).get();
     }
     return true;
   }
 
   if ((isa<IntegerLiteral>(SrcExpr) || isa<CharacterLiteral>(SrcExpr) ||
       isa<FloatingLiteral>(SrcExpr) || isa<ObjCBoolLiteralExpr>(SrcExpr) ||
       isa<CXXBoolLiteralExpr>(SrcExpr)) &&
       !SrcExpr->isNullPointerConstant(
           getASTContext(), Expr::NPC_NeverValueDependent)) {
     if (!ID || !ID->getIdentifier()->isStr("NSNumber"))
       return false;
     if (Diagnose) {
       Diag(SrcExpr->getBeginLoc(), diag::err_missing_atsign_prefix)
           << /*number*/1
           << FixItHint::CreateInsertion(SrcExpr->getBeginLoc(), "@");
       Expr *NumLit =
           BuildObjCNumericLiteral(SrcExpr->getBeginLoc(), SrcExpr).get();
       if (NumLit)
         Exp = NumLit;
     }
     return true;
   }
 
   return false;
 }
 
 static bool maybeDiagnoseAssignmentToFunction(Sema &S, QualType DstType,
                                               const Expr *SrcExpr) {
   if (!DstType->isFunctionPointerType() ||
       !SrcExpr->getType()->isFunctionType())
     return false;
 
   auto *DRE = dyn_cast<DeclRefExpr>(SrcExpr->IgnoreParenImpCasts());
   if (!DRE)
     return false;
 
   auto *FD = dyn_cast<FunctionDecl>(DRE->getDecl());
   if (!FD)
     return false;
 
   return !S.checkAddressOfFunctionIsAvailable(FD,
                                               /*Complain=*/true,
                                               SrcExpr->getBeginLoc());
 }
 
 bool Sema::DiagnoseAssignmentResult(AssignConvertType ConvTy,
                                     SourceLocation Loc,
                                     QualType DstType, QualType SrcType,
                                     Expr *SrcExpr, AssignmentAction Action,
                                     bool *Complained) {
   if (Complained)
     *Complained = false;
 
   // Decode the result (notice that AST's are still created for extensions).
   bool CheckInferredResultType = false;
   bool isInvalid = false;
   unsigned DiagKind = 0;
   ConversionFixItGenerator ConvHints;
   bool MayHaveConvFixit = false;
   bool MayHaveFunctionDiff = false;
   const ObjCInterfaceDecl *IFace = nullptr;
   const ObjCProtocolDecl *PDecl = nullptr;
 
   switch (ConvTy) {
   case Compatible:
       DiagnoseAssignmentEnum(DstType, SrcType, SrcExpr);
       return false;
 
   case PointerToInt:
     if (getLangOpts().CPlusPlus) {
       DiagKind = diag::err_typecheck_convert_pointer_int;
       isInvalid = true;
     } else {
       DiagKind = diag::ext_typecheck_convert_pointer_int;
     }
     ConvHints.tryToFixConversion(SrcExpr, SrcType, DstType, *this);
     MayHaveConvFixit = true;
     break;
   case IntToPointer:
     if (getLangOpts().CPlusPlus) {
       DiagKind = diag::err_typecheck_convert_int_pointer;
       isInvalid = true;
     } else {
       DiagKind = diag::ext_typecheck_convert_int_pointer;
     }
     ConvHints.tryToFixConversion(SrcExpr, SrcType, DstType, *this);
     MayHaveConvFixit = true;
     break;
   case IncompatibleFunctionPointerStrict:
     DiagKind =
         diag::warn_typecheck_convert_incompatible_function_pointer_strict;
     ConvHints.tryToFixConversion(SrcExpr, SrcType, DstType, *this);
     MayHaveConvFixit = true;
     break;
   case IncompatibleFunctionPointer:
     if (getLangOpts().CPlusPlus) {
       DiagKind = diag::err_typecheck_convert_incompatible_function_pointer;
       isInvalid = true;
     } else {
       DiagKind = diag::ext_typecheck_convert_incompatible_function_pointer;
     }
     ConvHints.tryToFixConversion(SrcExpr, SrcType, DstType, *this);
     MayHaveConvFixit = true;
     break;
   case IncompatiblePointer:
     if (Action == AA_Passing_CFAudited) {
       DiagKind = diag::err_arc_typecheck_convert_incompatible_pointer;
     } else if (getLangOpts().CPlusPlus) {
       DiagKind = diag::err_typecheck_convert_incompatible_pointer;
       isInvalid = true;
     } else {
       DiagKind = diag::ext_typecheck_convert_incompatible_pointer;
     }
     CheckInferredResultType = DstType->isObjCObjectPointerType() &&
       SrcType->isObjCObjectPointerType();
     if (!CheckInferredResultType) {
       ConvHints.tryToFixConversion(SrcExpr, SrcType, DstType, *this);
     } else if (CheckInferredResultType) {
       SrcType = SrcType.getUnqualifiedType();
       DstType = DstType.getUnqualifiedType();
     }
     MayHaveConvFixit = true;
     break;
   case IncompatiblePointerSign:
     if (getLangOpts().CPlusPlus) {
       DiagKind = diag::err_typecheck_convert_incompatible_pointer_sign;
       isInvalid = true;
     } else {
       DiagKind = diag::ext_typecheck_convert_incompatible_pointer_sign;
     }
     break;
   case FunctionVoidPointer:
     if (getLangOpts().CPlusPlus) {
       DiagKind = diag::err_typecheck_convert_pointer_void_func;
       isInvalid = true;
     } else {
       DiagKind = diag::ext_typecheck_convert_pointer_void_func;
     }
     break;
   case IncompatiblePointerDiscardsQualifiers: {
     // Perform array-to-pointer decay if necessary.
     if (SrcType->isArrayType()) SrcType = Context.getArrayDecayedType(SrcType);
 
     isInvalid = true;
 
     Qualifiers lhq = SrcType->getPointeeType().getQualifiers();
     Qualifiers rhq = DstType->getPointeeType().getQualifiers();
     if (lhq.getAddressSpace() != rhq.getAddressSpace()) {
       DiagKind = diag::err_typecheck_incompatible_address_space;
       break;
 
     } else if (lhq.getObjCLifetime() != rhq.getObjCLifetime()) {
       DiagKind = diag::err_typecheck_incompatible_ownership;
       break;
     }
 
     llvm_unreachable("unknown error case for discarding qualifiers!");
     // fallthrough
   }
   case CompatiblePointerDiscardsQualifiers:
     // If the qualifiers lost were because we were applying the
     // (deprecated) C++ conversion from a string literal to a char*
     // (or wchar_t*), then there was no error (C++ 4.2p2).  FIXME:
     // Ideally, this check would be performed in
     // checkPointerTypesForAssignment. However, that would require a
     // bit of refactoring (so that the second argument is an
     // expression, rather than a type), which should be done as part
     // of a larger effort to fix checkPointerTypesForAssignment for
     // C++ semantics.
     if (getLangOpts().CPlusPlus &&
         IsStringLiteralToNonConstPointerConversion(SrcExpr, DstType))
       return false;
     if (getLangOpts().CPlusPlus) {
       DiagKind =  diag::err_typecheck_convert_discards_qualifiers;
       isInvalid = true;
     } else {
       DiagKind =  diag::ext_typecheck_convert_discards_qualifiers;
     }
 
     break;
   case IncompatibleNestedPointerQualifiers:
     if (getLangOpts().CPlusPlus) {
       isInvalid = true;
       DiagKind = diag::err_nested_pointer_qualifier_mismatch;
     } else {
       DiagKind = diag::ext_nested_pointer_qualifier_mismatch;
     }
     break;
   case IncompatibleNestedPointerAddressSpaceMismatch:
     DiagKind = diag::err_typecheck_incompatible_nested_address_space;
     isInvalid = true;
     break;
   case IntToBlockPointer:
     DiagKind = diag::err_int_to_block_pointer;
     isInvalid = true;
     break;
   case IncompatibleBlockPointer:
     DiagKind = diag::err_typecheck_convert_incompatible_block_pointer;
     isInvalid = true;
     break;
   case IncompatibleObjCQualifiedId: {
     if (SrcType->isObjCQualifiedIdType()) {
       const ObjCObjectPointerType *srcOPT =
                 SrcType->castAs<ObjCObjectPointerType>();
       for (auto *srcProto : srcOPT->quals()) {
         PDecl = srcProto;
         break;
       }
       if (const ObjCInterfaceType *IFaceT =
             DstType->castAs<ObjCObjectPointerType>()->getInterfaceType())
         IFace = IFaceT->getDecl();
     }
     else if (DstType->isObjCQualifiedIdType()) {
       const ObjCObjectPointerType *dstOPT =
         DstType->castAs<ObjCObjectPointerType>();
       for (auto *dstProto : dstOPT->quals()) {
         PDecl = dstProto;
         break;
       }
       if (const ObjCInterfaceType *IFaceT =
             SrcType->castAs<ObjCObjectPointerType>()->getInterfaceType())
         IFace = IFaceT->getDecl();
     }
     if (getLangOpts().CPlusPlus) {
       DiagKind = diag::err_incompatible_qualified_id;
       isInvalid = true;
     } else {
       DiagKind = diag::warn_incompatible_qualified_id;
     }
     break;
   }
   case IncompatibleVectors:
     if (getLangOpts().CPlusPlus) {
       DiagKind = diag::err_incompatible_vectors;
       isInvalid = true;
     } else {
       DiagKind = diag::warn_incompatible_vectors;
     }
     break;
   case IncompatibleObjCWeakRef:
     DiagKind = diag::err_arc_weak_unavailable_assign;
     isInvalid = true;
     break;
   case Incompatible:
     if (maybeDiagnoseAssignmentToFunction(*this, DstType, SrcExpr)) {
       if (Complained)
         *Complained = true;
       return true;
     }
 
     DiagKind = diag::err_typecheck_convert_incompatible;
     ConvHints.tryToFixConversion(SrcExpr, SrcType, DstType, *this);
     MayHaveConvFixit = true;
     isInvalid = true;
     MayHaveFunctionDiff = true;
     break;
   }
 
   QualType FirstType, SecondType;
   switch (Action) {
   case AA_Assigning:
   case AA_Initializing:
     // The destination type comes first.
     FirstType = DstType;
     SecondType = SrcType;
     break;
 
   case AA_Returning:
   case AA_Passing:
   case AA_Passing_CFAudited:
   case AA_Converting:
   case AA_Sending:
   case AA_Casting:
     // The source type comes first.
     FirstType = SrcType;
     SecondType = DstType;
     break;
   }
 
   PartialDiagnostic FDiag = PDiag(DiagKind);
   AssignmentAction ActionForDiag = Action;
   if (Action == AA_Passing_CFAudited)
     ActionForDiag = AA_Passing;
 
   FDiag << FirstType << SecondType << ActionForDiag
         << SrcExpr->getSourceRange();
 
   if (DiagKind == diag::ext_typecheck_convert_incompatible_pointer_sign ||
       DiagKind == diag::err_typecheck_convert_incompatible_pointer_sign) {
     auto isPlainChar = [](const clang::Type *Type) {
       return Type->isSpecificBuiltinType(BuiltinType::Char_S) ||
              Type->isSpecificBuiltinType(BuiltinType::Char_U);
     };
     FDiag << (isPlainChar(FirstType->getPointeeOrArrayElementType()) ||
               isPlainChar(SecondType->getPointeeOrArrayElementType()));
   }
 
   // If we can fix the conversion, suggest the FixIts.
   if (!ConvHints.isNull()) {
     for (FixItHint &H : ConvHints.Hints)
       FDiag << H;
   }
 
   if (MayHaveConvFixit) { FDiag << (unsigned) (ConvHints.Kind); }
 
   if (MayHaveFunctionDiff)
     HandleFunctionTypeMismatch(FDiag, SecondType, FirstType);
 
   Diag(Loc, FDiag);
   if ((DiagKind == diag::warn_incompatible_qualified_id ||
        DiagKind == diag::err_incompatible_qualified_id) &&
       PDecl && IFace && !IFace->hasDefinition())
     Diag(IFace->getLocation(), diag::note_incomplete_class_and_qualified_id)
         << IFace << PDecl;
 
   if (SecondType == Context.OverloadTy)
     NoteAllOverloadCandidates(OverloadExpr::find(SrcExpr).Expression,
                               FirstType, /*TakingAddress=*/true);
 
   if (CheckInferredResultType)
     EmitRelatedResultTypeNote(SrcExpr);
 
   if (Action == AA_Returning && ConvTy == IncompatiblePointer)
     EmitRelatedResultTypeNoteForReturn(DstType);
 
   if (Complained)
     *Complained = true;
   return isInvalid;
 }
 
 ExprResult Sema::VerifyIntegerConstantExpression(Expr *E,
                                                  llvm::APSInt *Result,
                                                  AllowFoldKind CanFold) {
   class SimpleICEDiagnoser : public VerifyICEDiagnoser {
   public:
     SemaDiagnosticBuilder diagnoseNotICEType(Sema &S, SourceLocation Loc,
                                              QualType T) override {
       return S.Diag(Loc, diag::err_ice_not_integral)
              << T << S.LangOpts.CPlusPlus;
     }
     SemaDiagnosticBuilder diagnoseNotICE(Sema &S, SourceLocation Loc) override {
       return S.Diag(Loc, diag::err_expr_not_ice) << S.LangOpts.CPlusPlus;
     }
   } Diagnoser;
 
   return VerifyIntegerConstantExpression(E, Result, Diagnoser, CanFold);
 }
 
 ExprResult Sema::VerifyIntegerConstantExpression(Expr *E,
                                                  llvm::APSInt *Result,
                                                  unsigned DiagID,
                                                  AllowFoldKind CanFold) {
   class IDDiagnoser : public VerifyICEDiagnoser {
     unsigned DiagID;
 
   public:
     IDDiagnoser(unsigned DiagID)
       : VerifyICEDiagnoser(DiagID == 0), DiagID(DiagID) { }
 
     SemaDiagnosticBuilder diagnoseNotICE(Sema &S, SourceLocation Loc) override {
       return S.Diag(Loc, DiagID);
     }
   } Diagnoser(DiagID);
 
   return VerifyIntegerConstantExpression(E, Result, Diagnoser, CanFold);
 }
 
 Sema::SemaDiagnosticBuilder
 Sema::VerifyICEDiagnoser::diagnoseNotICEType(Sema &S, SourceLocation Loc,
                                              QualType T) {
   return diagnoseNotICE(S, Loc);
 }
 
 Sema::SemaDiagnosticBuilder
 Sema::VerifyICEDiagnoser::diagnoseFold(Sema &S, SourceLocation Loc) {
   return S.Diag(Loc, diag::ext_expr_not_ice) << S.LangOpts.CPlusPlus;
 }
 
 ExprResult
 Sema::VerifyIntegerConstantExpression(Expr *E, llvm::APSInt *Result,
                                       VerifyICEDiagnoser &Diagnoser,
                                       AllowFoldKind CanFold) {
   SourceLocation DiagLoc = E->getBeginLoc();
 
   if (getLangOpts().CPlusPlus11) {
     // C++11 [expr.const]p5:
     //   If an expression of literal class type is used in a context where an
     //   integral constant expression is required, then that class type shall
     //   have a single non-explicit conversion function to an integral or
     //   unscoped enumeration type
     ExprResult Converted;
     class CXX11ConvertDiagnoser : public ICEConvertDiagnoser {
       VerifyICEDiagnoser &BaseDiagnoser;
     public:
       CXX11ConvertDiagnoser(VerifyICEDiagnoser &BaseDiagnoser)
           : ICEConvertDiagnoser(/*AllowScopedEnumerations*/ false,
                                 BaseDiagnoser.Suppress, true),
             BaseDiagnoser(BaseDiagnoser) {}
 
       SemaDiagnosticBuilder diagnoseNotInt(Sema &S, SourceLocation Loc,
                                            QualType T) override {
         return BaseDiagnoser.diagnoseNotICEType(S, Loc, T);
       }
 
       SemaDiagnosticBuilder diagnoseIncomplete(
           Sema &S, SourceLocation Loc, QualType T) override {
         return S.Diag(Loc, diag::err_ice_incomplete_type) << T;
       }
 
       SemaDiagnosticBuilder diagnoseExplicitConv(
           Sema &S, SourceLocation Loc, QualType T, QualType ConvTy) override {
         return S.Diag(Loc, diag::err_ice_explicit_conversion) << T << ConvTy;
       }
 
       SemaDiagnosticBuilder noteExplicitConv(
           Sema &S, CXXConversionDecl *Conv, QualType ConvTy) override {
         return S.Diag(Conv->getLocation(), diag::note_ice_conversion_here)
                  << ConvTy->isEnumeralType() << ConvTy;
       }
 
       SemaDiagnosticBuilder diagnoseAmbiguous(
           Sema &S, SourceLocation Loc, QualType T) override {
         return S.Diag(Loc, diag::err_ice_ambiguous_conversion) << T;
       }
 
       SemaDiagnosticBuilder noteAmbiguous(
           Sema &S, CXXConversionDecl *Conv, QualType ConvTy) override {
         return S.Diag(Conv->getLocation(), diag::note_ice_conversion_here)
                  << ConvTy->isEnumeralType() << ConvTy;
       }
 
       SemaDiagnosticBuilder diagnoseConversion(
           Sema &S, SourceLocation Loc, QualType T, QualType ConvTy) override {
         llvm_unreachable("conversion functions are permitted");
       }
     } ConvertDiagnoser(Diagnoser);
 
     Converted = PerformContextualImplicitConversion(DiagLoc, E,
                                                     ConvertDiagnoser);
     if (Converted.isInvalid())
       return Converted;
     E = Converted.get();
     if (!E->getType()->isIntegralOrUnscopedEnumerationType())
       return ExprError();
   } else if (!E->getType()->isIntegralOrUnscopedEnumerationType()) {
     // An ICE must be of integral or unscoped enumeration type.
     if (!Diagnoser.Suppress)
       Diagnoser.diagnoseNotICEType(*this, DiagLoc, E->getType())
           << E->getSourceRange();
     return ExprError();
   }
 
   ExprResult RValueExpr = DefaultLvalueConversion(E);
   if (RValueExpr.isInvalid())
     return ExprError();
 
   E = RValueExpr.get();
 
   // Circumvent ICE checking in C++11 to avoid evaluating the expression twice
   // in the non-ICE case.
   if (!getLangOpts().CPlusPlus11 && E->isIntegerConstantExpr(Context)) {
     if (Result)
       *Result = E->EvaluateKnownConstIntCheckOverflow(Context);
     if (!isa<ConstantExpr>(E))
       E = Result ? ConstantExpr::Create(Context, E, APValue(*Result))
                  : ConstantExpr::Create(Context, E);
     return E;
   }
 
   Expr::EvalResult EvalResult;
   SmallVector<PartialDiagnosticAt, 8> Notes;
   EvalResult.Diag = &Notes;
 
   // Try to evaluate the expression, and produce diagnostics explaining why it's
   // not a constant expression as a side-effect.
   bool Folded =
       E->EvaluateAsRValue(EvalResult, Context, /*isConstantContext*/ true) &&
       EvalResult.Val.isInt() && !EvalResult.HasSideEffects;
 
   if (!isa<ConstantExpr>(E))
     E = ConstantExpr::Create(Context, E, EvalResult.Val);
 
   // In C++11, we can rely on diagnostics being produced for any expression
   // which is not a constant expression. If no diagnostics were produced, then
   // this is a constant expression.
   if (Folded && getLangOpts().CPlusPlus11 && Notes.empty()) {
     if (Result)
       *Result = EvalResult.Val.getInt();
     return E;
   }
 
   // If our only note is the usual "invalid subexpression" note, just point
   // the caret at its location rather than producing an essentially
   // redundant note.
   if (Notes.size() == 1 && Notes[0].second.getDiagID() ==
         diag::note_invalid_subexpr_in_const_expr) {
     DiagLoc = Notes[0].first;
     Notes.clear();
   }
 
   if (!Folded || !CanFold) {
     if (!Diagnoser.Suppress) {
       Diagnoser.diagnoseNotICE(*this, DiagLoc) << E->getSourceRange();
       for (const PartialDiagnosticAt &Note : Notes)
         Diag(Note.first, Note.second);
     }
 
     return ExprError();
   }
 
   Diagnoser.diagnoseFold(*this, DiagLoc) << E->getSourceRange();
   for (const PartialDiagnosticAt &Note : Notes)
     Diag(Note.first, Note.second);
 
   if (Result)
     *Result = EvalResult.Val.getInt();
   return E;
 }
 
 namespace {
   // Handle the case where we conclude a expression which we speculatively
   // considered to be unevaluated is actually evaluated.
   class TransformToPE : public TreeTransform<TransformToPE> {
     typedef TreeTransform<TransformToPE> BaseTransform;
 
   public:
     TransformToPE(Sema &SemaRef) : BaseTransform(SemaRef) { }
 
     // Make sure we redo semantic analysis
     bool AlwaysRebuild() { return true; }
     bool ReplacingOriginal() { return true; }
 
     // We need to special-case DeclRefExprs referring to FieldDecls which
     // are not part of a member pointer formation; normal TreeTransforming
     // doesn't catch this case because of the way we represent them in the AST.
     // FIXME: This is a bit ugly; is it really the best way to handle this
     // case?
     //
     // Error on DeclRefExprs referring to FieldDecls.
     ExprResult TransformDeclRefExpr(DeclRefExpr *E) {
       if (isa<FieldDecl>(E->getDecl()) &&
           !SemaRef.isUnevaluatedContext())
         return SemaRef.Diag(E->getLocation(),
                             diag::err_invalid_non_static_member_use)
             << E->getDecl() << E->getSourceRange();
 
       return BaseTransform::TransformDeclRefExpr(E);
     }
 
     // Exception: filter out member pointer formation
     ExprResult TransformUnaryOperator(UnaryOperator *E) {
       if (E->getOpcode() == UO_AddrOf && E->getType()->isMemberPointerType())
         return E;
 
       return BaseTransform::TransformUnaryOperator(E);
     }
 
     // The body of a lambda-expression is in a separate expression evaluation
     // context so never needs to be transformed.
     // FIXME: Ideally we wouldn't transform the closure type either, and would
     // just recreate the capture expressions and lambda expression.
     StmtResult TransformLambdaBody(LambdaExpr *E, Stmt *Body) {
       return SkipLambdaBody(E, Body);
     }
   };
 }
 
 ExprResult Sema::TransformToPotentiallyEvaluated(Expr *E) {
   assert(isUnevaluatedContext() &&
          "Should only transform unevaluated expressions");
   ExprEvalContexts.back().Context =
       ExprEvalContexts[ExprEvalContexts.size()-2].Context;
   if (isUnevaluatedContext())
     return E;
   return TransformToPE(*this).TransformExpr(E);
 }
 
 TypeSourceInfo *Sema::TransformToPotentiallyEvaluated(TypeSourceInfo *TInfo) {
   assert(isUnevaluatedContext() &&
          "Should only transform unevaluated expressions");
   ExprEvalContexts.back().Context =
       ExprEvalContexts[ExprEvalContexts.size() - 2].Context;
   if (isUnevaluatedContext())
     return TInfo;
   return TransformToPE(*this).TransformType(TInfo);
 }
 
 void
 Sema::PushExpressionEvaluationContext(
     ExpressionEvaluationContext NewContext, Decl *LambdaContextDecl,
     ExpressionEvaluationContextRecord::ExpressionKind ExprContext) {
   ExprEvalContexts.emplace_back(NewContext, ExprCleanupObjects.size(), Cleanup,
                                 LambdaContextDecl, ExprContext);
 
   // Discarded statements and immediate contexts nested in other
   // discarded statements or immediate context are themselves
   // a discarded statement or an immediate context, respectively.
   ExprEvalContexts.back().InDiscardedStatement =
       ExprEvalContexts[ExprEvalContexts.size() - 2]
           .isDiscardedStatementContext();
 
   // C++23 [expr.const]/p15
   // An expression or conversion is in an immediate function context if [...]
   // it is a subexpression of a manifestly constant-evaluated expression or
   // conversion.
   const auto &Prev = ExprEvalContexts[ExprEvalContexts.size() - 2];
   ExprEvalContexts.back().InImmediateFunctionContext =
       Prev.isImmediateFunctionContext() || Prev.isConstantEvaluated();
 
   ExprEvalContexts.back().InImmediateEscalatingFunctionContext =
       Prev.InImmediateEscalatingFunctionContext;
 
   Cleanup.reset();
   if (!MaybeODRUseExprs.empty())
     std::swap(MaybeODRUseExprs, ExprEvalContexts.back().SavedMaybeODRUseExprs);
 }
 
 void
 Sema::PushExpressionEvaluationContext(
     ExpressionEvaluationContext NewContext, ReuseLambdaContextDecl_t,
     ExpressionEvaluationContextRecord::ExpressionKind ExprContext) {
   Decl *ClosureContextDecl = ExprEvalContexts.back().ManglingContextDecl;
   PushExpressionEvaluationContext(NewContext, ClosureContextDecl, ExprContext);
 }
 
 namespace {
 
 const DeclRefExpr *CheckPossibleDeref(Sema &S, const Expr *PossibleDeref) {
   PossibleDeref = PossibleDeref->IgnoreParenImpCasts();
   if (const auto *E = dyn_cast<UnaryOperator>(PossibleDeref)) {
     if (E->getOpcode() == UO_Deref)
       return CheckPossibleDeref(S, E->getSubExpr());
   } else if (const auto *E = dyn_cast<ArraySubscriptExpr>(PossibleDeref)) {
     return CheckPossibleDeref(S, E->getBase());
   } else if (const auto *E = dyn_cast<MemberExpr>(PossibleDeref)) {
     return CheckPossibleDeref(S, E->getBase());
   } else if (const auto E = dyn_cast<DeclRefExpr>(PossibleDeref)) {
     QualType Inner;
     QualType Ty = E->getType();
     if (const auto *Ptr = Ty->getAs<PointerType>())
       Inner = Ptr->getPointeeType();
     else if (const auto *Arr = S.Context.getAsArrayType(Ty))
       Inner = Arr->getElementType();
     else
       return nullptr;
 
     if (Inner->hasAttr(attr::NoDeref))
       return E;
   }
   return nullptr;
 }
 
 } // namespace
 
 void Sema::WarnOnPendingNoDerefs(ExpressionEvaluationContextRecord &Rec) {
   for (const Expr *E : Rec.PossibleDerefs) {
     const DeclRefExpr *DeclRef = CheckPossibleDeref(*this, E);
     if (DeclRef) {
       const ValueDecl *Decl = DeclRef->getDecl();
       Diag(E->getExprLoc(), diag::warn_dereference_of_noderef_type)
           << Decl->getName() << E->getSourceRange();
       Diag(Decl->getLocation(), diag::note_previous_decl) << Decl->getName();
     } else {
       Diag(E->getExprLoc(), diag::warn_dereference_of_noderef_type_no_decl)
           << E->getSourceRange();
     }
   }
   Rec.PossibleDerefs.clear();
 }
 
 /// Check whether E, which is either a discarded-value expression or an
 /// unevaluated operand, is a simple-assignment to a volatlie-qualified lvalue,
 /// and if so, remove it from the list of volatile-qualified assignments that
 /// we are going to warn are deprecated.
 void Sema::CheckUnusedVolatileAssignment(Expr *E) {
   if (!E->getType().isVolatileQualified() || !getLangOpts().CPlusPlus20)
     return;
 
   // Note: ignoring parens here is not justified by the standard rules, but
   // ignoring parentheses seems like a more reasonable approach, and this only
   // drives a deprecation warning so doesn't affect conformance.
   if (auto *BO = dyn_cast<BinaryOperator>(E->IgnoreParenImpCasts())) {
     if (BO->getOpcode() == BO_Assign) {
       auto &LHSs = ExprEvalContexts.back().VolatileAssignmentLHSs;
       llvm::erase_value(LHSs, BO->getLHS());
     }
   }
 }
 
 void Sema::MarkExpressionAsImmediateEscalating(Expr *E) {
   assert(!FunctionScopes.empty() && "Expected a function scope");
   assert(getLangOpts().CPlusPlus20 &&
          ExprEvalContexts.back().InImmediateEscalatingFunctionContext &&
          "Cannot mark an immediate escalating expression outside of an "
          "immediate escalating context");
   if (auto *Call = dyn_cast<CallExpr>(E->IgnoreImplicit());
       Call && Call->getCallee()) {
     if (auto *DeclRef =
             dyn_cast<DeclRefExpr>(Call->getCallee()->IgnoreImplicit()))
       DeclRef->setIsImmediateEscalating(true);
   } else if (auto *Ctr = dyn_cast<CXXConstructExpr>(E->IgnoreImplicit())) {
     Ctr->setIsImmediateEscalating(true);
   } else if (auto *DeclRef = dyn_cast<DeclRefExpr>(E->IgnoreImplicit())) {
     DeclRef->setIsImmediateEscalating(true);
   } else {
     assert(false && "expected an immediately escalating expression");
   }
   getCurFunction()->FoundImmediateEscalatingExpression = true;
 }
 
 ExprResult Sema::CheckForImmediateInvocation(ExprResult E, FunctionDecl *Decl) {
   if (isUnevaluatedContext() || !E.isUsable() || !Decl ||
       !Decl->isImmediateFunction() || isConstantEvaluated() ||
       isCheckingDefaultArgumentOrInitializer() ||
       RebuildingImmediateInvocation || isImmediateFunctionContext())
     return E;
 
   /// Opportunistically remove the callee from ReferencesToConsteval if we can.
   /// It's OK if this fails; we'll also remove this in
   /// HandleImmediateInvocations, but catching it here allows us to avoid
   /// walking the AST looking for it in simple cases.
   if (auto *Call = dyn_cast<CallExpr>(E.get()->IgnoreImplicit()))
     if (auto *DeclRef =
             dyn_cast<DeclRefExpr>(Call->getCallee()->IgnoreImplicit()))
       ExprEvalContexts.back().ReferenceToConsteval.erase(DeclRef);
 
   // C++23 [expr.const]/p16
   // An expression or conversion is immediate-escalating if it is not initially
   // in an immediate function context and it is [...] an immediate invocation
   // that is not a constant expression and is not a subexpression of an
   // immediate invocation.
   APValue Cached;
   auto CheckConstantExpressionAndKeepResult = [&]() {
     llvm::SmallVector<PartialDiagnosticAt, 8> Notes;
     Expr::EvalResult Eval;
     Eval.Diag = &Notes;
     bool Res = E.get()->EvaluateAsConstantExpr(
         Eval, getASTContext(), ConstantExprKind::ImmediateInvocation);
     if (Res && Notes.empty()) {
       Cached = std::move(Eval.Val);
       return true;
     }
     return false;
   };
 
   if (!E.get()->isValueDependent() &&
       ExprEvalContexts.back().InImmediateEscalatingFunctionContext &&
       !CheckConstantExpressionAndKeepResult()) {
     MarkExpressionAsImmediateEscalating(E.get());
     return E;
   }
 
   if (Cleanup.exprNeedsCleanups()) {
     // Since an immediate invocation is a full expression itself - it requires
     // an additional ExprWithCleanups node, but it can participate to a bigger
     // full expression which actually requires cleanups to be run after so
     // create ExprWithCleanups without using MaybeCreateExprWithCleanups as it
     // may discard cleanups for outer expression too early.
 
     // Note that ExprWithCleanups created here must always have empty cleanup
     // objects:
     // - compound literals do not create cleanup objects in C++ and immediate
     // invocations are C++-only.
     // - blocks are not allowed inside constant expressions and compiler will
     // issue an error if they appear there.
     //
     // Hence, in correct code any cleanup objects created inside current
     // evaluation context must be outside the immediate invocation.
     E = ExprWithCleanups::Create(getASTContext(), E.get(),
                                  Cleanup.cleanupsHaveSideEffects(), {});
   }
 
   ConstantExpr *Res = ConstantExpr::Create(
       getASTContext(), E.get(),
       ConstantExpr::getStorageKind(Decl->getReturnType().getTypePtr(),
                                    getASTContext()),
       /*IsImmediateInvocation*/ true);
   if (Cached.hasValue())
     Res->MoveIntoResult(Cached, getASTContext());
   /// Value-dependent constant expressions should not be immediately
   /// evaluated until they are instantiated.
   if (!Res->isValueDependent())
     ExprEvalContexts.back().ImmediateInvocationCandidates.emplace_back(Res, 0);
   return Res;
 }
 
 static void EvaluateAndDiagnoseImmediateInvocation(
     Sema &SemaRef, Sema::ImmediateInvocationCandidate Candidate) {
   llvm::SmallVector<PartialDiagnosticAt, 8> Notes;
   Expr::EvalResult Eval;
   Eval.Diag = &Notes;
   ConstantExpr *CE = Candidate.getPointer();
   bool Result = CE->EvaluateAsConstantExpr(
       Eval, SemaRef.getASTContext(), ConstantExprKind::ImmediateInvocation);
   if (!Result || !Notes.empty()) {
     SemaRef.FailedImmediateInvocations.insert(CE);
     Expr *InnerExpr = CE->getSubExpr()->IgnoreImplicit();
     if (auto *FunctionalCast = dyn_cast<CXXFunctionalCastExpr>(InnerExpr))
       InnerExpr = FunctionalCast->getSubExpr();
     FunctionDecl *FD = nullptr;
     if (auto *Call = dyn_cast<CallExpr>(InnerExpr))
       FD = cast<FunctionDecl>(Call->getCalleeDecl());
     else if (auto *Call = dyn_cast<CXXConstructExpr>(InnerExpr))
       FD = Call->getConstructor();
     else
       llvm_unreachable("unhandled decl kind");
     assert(FD && FD->isImmediateFunction());
     SemaRef.Diag(CE->getBeginLoc(), diag::err_invalid_consteval_call)
         << FD << FD->isConsteval();
     if (auto Context =
             SemaRef.InnermostDeclarationWithDelayedImmediateInvocations()) {
       SemaRef.Diag(Context->Loc, diag::note_invalid_consteval_initializer)
           << Context->Decl;
       SemaRef.Diag(Context->Decl->getBeginLoc(), diag::note_declared_at);
     }
     if (!FD->isConsteval())
       SemaRef.DiagnoseImmediateEscalatingReason(FD);
     for (auto &Note : Notes)
       SemaRef.Diag(Note.first, Note.second);
     return;
   }
   CE->MoveIntoResult(Eval.Val, SemaRef.getASTContext());
 }
 
 static void RemoveNestedImmediateInvocation(
     Sema &SemaRef, Sema::ExpressionEvaluationContextRecord &Rec,
     SmallVector<Sema::ImmediateInvocationCandidate, 4>::reverse_iterator It) {
   struct ComplexRemove : TreeTransform<ComplexRemove> {
     using Base = TreeTransform<ComplexRemove>;
     llvm::SmallPtrSetImpl<DeclRefExpr *> &DRSet;
     SmallVector<Sema::ImmediateInvocationCandidate, 4> &IISet;
     SmallVector<Sema::ImmediateInvocationCandidate, 4>::reverse_iterator
         CurrentII;
     ComplexRemove(Sema &SemaRef, llvm::SmallPtrSetImpl<DeclRefExpr *> &DR,
                   SmallVector<Sema::ImmediateInvocationCandidate, 4> &II,
                   SmallVector<Sema::ImmediateInvocationCandidate,
                               4>::reverse_iterator Current)
         : Base(SemaRef), DRSet(DR), IISet(II), CurrentII(Current) {}
     void RemoveImmediateInvocation(ConstantExpr* E) {
       auto It = std::find_if(CurrentII, IISet.rend(),
                              [E](Sema::ImmediateInvocationCandidate Elem) {
                                return Elem.getPointer() == E;
                              });
       // It is possible that some subexpression of the current immediate
       // invocation was handled from another expression evaluation context. Do
       // not handle the current immediate invocation if some of its
       // subexpressions failed before.
       if (It == IISet.rend()) {
         if (SemaRef.FailedImmediateInvocations.contains(E))
           CurrentII->setInt(1);
       } else {
         It->setInt(1); // Mark as deleted
       }
     }
     ExprResult TransformConstantExpr(ConstantExpr *E) {
       if (!E->isImmediateInvocation())
         return Base::TransformConstantExpr(E);
       RemoveImmediateInvocation(E);
       return Base::TransformExpr(E->getSubExpr());
     }
     /// Base::TransfromCXXOperatorCallExpr doesn't traverse the callee so
     /// we need to remove its DeclRefExpr from the DRSet.
     ExprResult TransformCXXOperatorCallExpr(CXXOperatorCallExpr *E) {
       DRSet.erase(cast<DeclRefExpr>(E->getCallee()->IgnoreImplicit()));
       return Base::TransformCXXOperatorCallExpr(E);
     }
     /// Base::TransformInitializer skip ConstantExpr so we need to visit them
     /// here.
     ExprResult TransformInitializer(Expr *Init, bool NotCopyInit) {
       if (!Init)
         return Init;
       /// ConstantExpr are the first layer of implicit node to be removed so if
       /// Init isn't a ConstantExpr, no ConstantExpr will be skipped.
       if (auto *CE = dyn_cast<ConstantExpr>(Init))
         if (CE->isImmediateInvocation())
           RemoveImmediateInvocation(CE);
       return Base::TransformInitializer(Init, NotCopyInit);
     }
     ExprResult TransformDeclRefExpr(DeclRefExpr *E) {
       DRSet.erase(E);
       return E;
     }
     ExprResult TransformLambdaExpr(LambdaExpr *E) {
       // Do not rebuild lambdas to avoid creating a new type.
       // Lambdas have already been processed inside their eval context.
       return E;
     }
     bool AlwaysRebuild() { return false; }
     bool ReplacingOriginal() { return true; }
     bool AllowSkippingCXXConstructExpr() {
       bool Res = AllowSkippingFirstCXXConstructExpr;
       AllowSkippingFirstCXXConstructExpr = true;
       return Res;
     }
     bool AllowSkippingFirstCXXConstructExpr = true;
   } Transformer(SemaRef, Rec.ReferenceToConsteval,
                 Rec.ImmediateInvocationCandidates, It);
 
   /// CXXConstructExpr with a single argument are getting skipped by
   /// TreeTransform in some situtation because they could be implicit. This
   /// can only occur for the top-level CXXConstructExpr because it is used
   /// nowhere in the expression being transformed therefore will not be rebuilt.
   /// Setting AllowSkippingFirstCXXConstructExpr to false will prevent from
   /// skipping the first CXXConstructExpr.
   if (isa<CXXConstructExpr>(It->getPointer()->IgnoreImplicit()))
     Transformer.AllowSkippingFirstCXXConstructExpr = false;
 
   ExprResult Res = Transformer.TransformExpr(It->getPointer()->getSubExpr());
   // The result may not be usable in case of previous compilation errors.
   // In this case evaluation of the expression may result in crash so just
   // don't do anything further with the result.
   if (Res.isUsable()) {
     Res = SemaRef.MaybeCreateExprWithCleanups(Res);
     It->getPointer()->setSubExpr(Res.get());
   }
 }
 
 static void
 HandleImmediateInvocations(Sema &SemaRef,
                            Sema::ExpressionEvaluationContextRecord &Rec) {
   if ((Rec.ImmediateInvocationCandidates.size() == 0 &&
        Rec.ReferenceToConsteval.size() == 0) ||
       SemaRef.RebuildingImmediateInvocation)
     return;
 
   /// When we have more than 1 ImmediateInvocationCandidates or previously
   /// failed immediate invocations, we need to check for nested
   /// ImmediateInvocationCandidates in order to avoid duplicate diagnostics.
   /// Otherwise we only need to remove ReferenceToConsteval in the immediate
   /// invocation.
   if (Rec.ImmediateInvocationCandidates.size() > 1 ||
       !SemaRef.FailedImmediateInvocations.empty()) {
 
     /// Prevent sema calls during the tree transform from adding pointers that
     /// are already in the sets.
     llvm::SaveAndRestore DisableIITracking(
         SemaRef.RebuildingImmediateInvocation, true);
 
     /// Prevent diagnostic during tree transfrom as they are duplicates
     Sema::TentativeAnalysisScope DisableDiag(SemaRef);
 
     for (auto It = Rec.ImmediateInvocationCandidates.rbegin();
          It != Rec.ImmediateInvocationCandidates.rend(); It++)
       if (!It->getInt())
         RemoveNestedImmediateInvocation(SemaRef, Rec, It);
   } else if (Rec.ImmediateInvocationCandidates.size() == 1 &&
              Rec.ReferenceToConsteval.size()) {
     struct SimpleRemove : RecursiveASTVisitor<SimpleRemove> {
       llvm::SmallPtrSetImpl<DeclRefExpr *> &DRSet;
       SimpleRemove(llvm::SmallPtrSetImpl<DeclRefExpr *> &S) : DRSet(S) {}
       bool VisitDeclRefExpr(DeclRefExpr *E) {
         DRSet.erase(E);
         return DRSet.size();
       }
     } Visitor(Rec.ReferenceToConsteval);
     Visitor.TraverseStmt(
         Rec.ImmediateInvocationCandidates.front().getPointer()->getSubExpr());
   }
   for (auto CE : Rec.ImmediateInvocationCandidates)
     if (!CE.getInt())
       EvaluateAndDiagnoseImmediateInvocation(SemaRef, CE);
   for (auto *DR : Rec.ReferenceToConsteval) {
     // If the expression is immediate escalating, it is not an error;
     // The outer context itself becomes immediate and further errors,
     // if any, will be handled by DiagnoseImmediateEscalatingReason.
     if (DR->isImmediateEscalating())
       continue;
     auto *FD = cast<FunctionDecl>(DR->getDecl());
     const NamedDecl *ND = FD;
     if (const auto *MD = dyn_cast<CXXMethodDecl>(ND);
         MD && (MD->isLambdaStaticInvoker() || isLambdaCallOperator(MD)))
       ND = MD->getParent();
 
     // C++23 [expr.const]/p16
     // An expression or conversion is immediate-escalating if it is not
     // initially in an immediate function context and it is [...] a
     // potentially-evaluated id-expression that denotes an immediate function
     // that is not a subexpression of an immediate invocation.
     bool ImmediateEscalating = false;
     bool IsPotentiallyEvaluated =
         Rec.Context ==
             Sema::ExpressionEvaluationContext::PotentiallyEvaluated ||
         Rec.Context ==
             Sema::ExpressionEvaluationContext::PotentiallyEvaluatedIfUsed;
     if (SemaRef.inTemplateInstantiation() && IsPotentiallyEvaluated)
       ImmediateEscalating = Rec.InImmediateEscalatingFunctionContext;
 
     if (!Rec.InImmediateEscalatingFunctionContext ||
         (SemaRef.inTemplateInstantiation() && !ImmediateEscalating)) {
       SemaRef.Diag(DR->getBeginLoc(), diag::err_invalid_consteval_take_address)
           << ND << isa<CXXRecordDecl>(ND) << FD->isConsteval();
       SemaRef.Diag(ND->getLocation(), diag::note_declared_at);
       if (auto Context =
               SemaRef.InnermostDeclarationWithDelayedImmediateInvocations()) {
         SemaRef.Diag(Context->Loc, diag::note_invalid_consteval_initializer)
             << Context->Decl;
         SemaRef.Diag(Context->Decl->getBeginLoc(), diag::note_declared_at);
       }
       if (FD->isImmediateEscalating() && !FD->isConsteval())
         SemaRef.DiagnoseImmediateEscalatingReason(FD);
 
     } else {
       SemaRef.MarkExpressionAsImmediateEscalating(DR);
     }
   }
 }
 
 void Sema::PopExpressionEvaluationContext() {
   ExpressionEvaluationContextRecord& Rec = ExprEvalContexts.back();
   unsigned NumTypos = Rec.NumTypos;
 
   if (!Rec.Lambdas.empty()) {
     using ExpressionKind = ExpressionEvaluationContextRecord::ExpressionKind;
     if (!getLangOpts().CPlusPlus20 &&
         (Rec.ExprContext == ExpressionKind::EK_TemplateArgument ||
          Rec.isUnevaluated() ||
          (Rec.isConstantEvaluated() && !getLangOpts().CPlusPlus17))) {
       unsigned D;
       if (Rec.isUnevaluated()) {
         // C++11 [expr.prim.lambda]p2:
         //   A lambda-expression shall not appear in an unevaluated operand
         //   (Clause 5).
         D = diag::err_lambda_unevaluated_operand;
       } else if (Rec.isConstantEvaluated() && !getLangOpts().CPlusPlus17) {
         // C++1y [expr.const]p2:
         //   A conditional-expression e is a core constant expression unless the
         //   evaluation of e, following the rules of the abstract machine, would
         //   evaluate [...] a lambda-expression.
         D = diag::err_lambda_in_constant_expression;
       } else if (Rec.ExprContext == ExpressionKind::EK_TemplateArgument) {
         // C++17 [expr.prim.lamda]p2:
         // A lambda-expression shall not appear [...] in a template-argument.
         D = diag::err_lambda_in_invalid_context;
       } else
         llvm_unreachable("Couldn't infer lambda error message.");
 
       for (const auto *L : Rec.Lambdas)
         Diag(L->getBeginLoc(), D);
     }
   }
 
   WarnOnPendingNoDerefs(Rec);
   HandleImmediateInvocations(*this, Rec);
 
   // Warn on any volatile-qualified simple-assignments that are not discarded-
   // value expressions nor unevaluated operands (those cases get removed from
   // this list by CheckUnusedVolatileAssignment).
   for (auto *BO : Rec.VolatileAssignmentLHSs)
     Diag(BO->getBeginLoc(), diag::warn_deprecated_simple_assign_volatile)
         << BO->getType();
 
   // When are coming out of an unevaluated context, clear out any
   // temporaries that we may have created as part of the evaluation of
   // the expression in that context: they aren't relevant because they
   // will never be constructed.
   if (Rec.isUnevaluated() || Rec.isConstantEvaluated()) {
     ExprCleanupObjects.erase(ExprCleanupObjects.begin() + Rec.NumCleanupObjects,
                              ExprCleanupObjects.end());
     Cleanup = Rec.ParentCleanup;
     CleanupVarDeclMarking();
     std::swap(MaybeODRUseExprs, Rec.SavedMaybeODRUseExprs);
   // Otherwise, merge the contexts together.
   } else {
     Cleanup.mergeFrom(Rec.ParentCleanup);
     MaybeODRUseExprs.insert(Rec.SavedMaybeODRUseExprs.begin(),
                             Rec.SavedMaybeODRUseExprs.end());
   }
 
   // Pop the current expression evaluation context off the stack.
   ExprEvalContexts.pop_back();
 
   // The global expression evaluation context record is never popped.
   ExprEvalContexts.back().NumTypos += NumTypos;
 }
 
 void Sema::DiscardCleanupsInEvaluationContext() {
   ExprCleanupObjects.erase(
          ExprCleanupObjects.begin() + ExprEvalContexts.back().NumCleanupObjects,
          ExprCleanupObjects.end());
   Cleanup.reset();
   MaybeODRUseExprs.clear();
 }
 
 ExprResult Sema::HandleExprEvaluationContextForTypeof(Expr *E) {
   ExprResult Result = CheckPlaceholderExpr(E);
   if (Result.isInvalid())
     return ExprError();
   E = Result.get();
   if (!E->getType()->isVariablyModifiedType())
     return E;
   return TransformToPotentiallyEvaluated(E);
 }
 
 /// Are we in a context that is potentially constant evaluated per C++20
 /// [expr.const]p12?
 static bool isPotentiallyConstantEvaluatedContext(Sema &SemaRef) {
   /// C++2a [expr.const]p12:
   //   An expression or conversion is potentially constant evaluated if it is
   switch (SemaRef.ExprEvalContexts.back().Context) {
     case Sema::ExpressionEvaluationContext::ConstantEvaluated:
     case Sema::ExpressionEvaluationContext::ImmediateFunctionContext:
 
       // -- a manifestly constant-evaluated expression,
     case Sema::ExpressionEvaluationContext::PotentiallyEvaluated:
     case Sema::ExpressionEvaluationContext::PotentiallyEvaluatedIfUsed:
     case Sema::ExpressionEvaluationContext::DiscardedStatement:
       // -- a potentially-evaluated expression,
     case Sema::ExpressionEvaluationContext::UnevaluatedList:
       // -- an immediate subexpression of a braced-init-list,
 
       // -- [FIXME] an expression of the form & cast-expression that occurs
       //    within a templated entity
       // -- a subexpression of one of the above that is not a subexpression of
       // a nested unevaluated operand.
       return true;
 
     case Sema::ExpressionEvaluationContext::Unevaluated:
     case Sema::ExpressionEvaluationContext::UnevaluatedAbstract:
       // Expressions in this context are never evaluated.
       return false;
   }
   llvm_unreachable("Invalid context");
 }
 
 /// Return true if this function has a calling convention that requires mangling
 /// in the size of the parameter pack.
 static bool funcHasParameterSizeMangling(Sema &S, FunctionDecl *FD) {
   // These manglings don't do anything on non-Windows or non-x86 platforms, so
   // we don't need parameter type sizes.
   const llvm::Triple &TT = S.Context.getTargetInfo().getTriple();
   if (!TT.isOSWindows() || !TT.isX86())
     return false;
 
   // If this is C++ and this isn't an extern "C" function, parameters do not
   // need to be complete. In this case, C++ mangling will apply, which doesn't
   // use the size of the parameters.
   if (S.getLangOpts().CPlusPlus && !FD->isExternC())
     return false;
 
   // Stdcall, fastcall, and vectorcall need this special treatment.
   CallingConv CC = FD->getType()->castAs<FunctionType>()->getCallConv();
   switch (CC) {
   case CC_X86StdCall:
   case CC_X86FastCall:
   case CC_X86VectorCall:
     return true;
   default:
     break;
   }
   return false;
 }
 
 /// Require that all of the parameter types of function be complete. Normally,
 /// parameter types are only required to be complete when a function is called
 /// or defined, but to mangle functions with certain calling conventions, the
 /// mangler needs to know the size of the parameter list. In this situation,
 /// MSVC doesn't emit an error or instantiate templates. Instead, MSVC mangles
 /// the function as _foo@0, i.e. zero bytes of parameters, which will usually
 /// result in a linker error. Clang doesn't implement this behavior, and instead
 /// attempts to error at compile time.
 static void CheckCompleteParameterTypesForMangler(Sema &S, FunctionDecl *FD,
                                                   SourceLocation Loc) {
   class ParamIncompleteTypeDiagnoser : public Sema::TypeDiagnoser {
     FunctionDecl *FD;
     ParmVarDecl *Param;
 
   public:
     ParamIncompleteTypeDiagnoser(FunctionDecl *FD, ParmVarDecl *Param)
         : FD(FD), Param(Param) {}
 
     void diagnose(Sema &S, SourceLocation Loc, QualType T) override {
       CallingConv CC = FD->getType()->castAs<FunctionType>()->getCallConv();
       StringRef CCName;
       switch (CC) {
       case CC_X86StdCall:
         CCName = "stdcall";
         break;
       case CC_X86FastCall:
         CCName = "fastcall";
         break;
       case CC_X86VectorCall:
         CCName = "vectorcall";
         break;
       default:
         llvm_unreachable("CC does not need mangling");
       }
 
       S.Diag(Loc, diag::err_cconv_incomplete_param_type)
           << Param->getDeclName() << FD->getDeclName() << CCName;
     }
   };
 
   for (ParmVarDecl *Param : FD->parameters()) {
     ParamIncompleteTypeDiagnoser Diagnoser(FD, Param);
     S.RequireCompleteType(Loc, Param->getType(), Diagnoser);
   }
 }
 
 namespace {
 enum class OdrUseContext {
   /// Declarations in this context are not odr-used.
   None,
   /// Declarations in this context are formally odr-used, but this is a
   /// dependent context.
   Dependent,
   /// Declarations in this context are odr-used but not actually used (yet).
   FormallyOdrUsed,
   /// Declarations in this context are used.
   Used
 };
 }
 
 /// Are we within a context in which references to resolved functions or to
 /// variables result in odr-use?
 static OdrUseContext isOdrUseContext(Sema &SemaRef) {
   OdrUseContext Result;
 
   switch (SemaRef.ExprEvalContexts.back().Context) {
     case Sema::ExpressionEvaluationContext::Unevaluated:
     case Sema::ExpressionEvaluationContext::UnevaluatedList:
     case Sema::ExpressionEvaluationContext::UnevaluatedAbstract:
       return OdrUseContext::None;
 
     case Sema::ExpressionEvaluationContext::ConstantEvaluated:
     case Sema::ExpressionEvaluationContext::ImmediateFunctionContext:
     case Sema::ExpressionEvaluationContext::PotentiallyEvaluated:
       Result = OdrUseContext::Used;
       break;
 
     case Sema::ExpressionEvaluationContext::DiscardedStatement:
       Result = OdrUseContext::FormallyOdrUsed;
       break;
 
     case Sema::ExpressionEvaluationContext::PotentiallyEvaluatedIfUsed:
       // A default argument formally results in odr-use, but doesn't actually
       // result in a use in any real sense until it itself is used.
       Result = OdrUseContext::FormallyOdrUsed;
       break;
   }
 
   if (SemaRef.CurContext->isDependentContext())
     return OdrUseContext::Dependent;
 
   return Result;
 }
 
 static bool isImplicitlyDefinableConstexprFunction(FunctionDecl *Func) {
   if (!Func->isConstexpr())
     return false;
 
   if (Func->isImplicitlyInstantiable() || !Func->isUserProvided())
     return true;
   auto *CCD = dyn_cast<CXXConstructorDecl>(Func);
   return CCD && CCD->getInheritedConstructor();
 }
 
 /// Mark a function referenced, and check whether it is odr-used
 /// (C++ [basic.def.odr]p2, C99 6.9p3)
 void Sema::MarkFunctionReferenced(SourceLocation Loc, FunctionDecl *Func,
                                   bool MightBeOdrUse) {
   assert(Func && "No function?");
 
   Func->setReferenced();
 
   // Recursive functions aren't really used until they're used from some other
   // context.
   bool IsRecursiveCall = CurContext == Func;
 
   // C++11 [basic.def.odr]p3:
   //   A function whose name appears as a potentially-evaluated expression is
   //   odr-used if it is the unique lookup result or the selected member of a
   //   set of overloaded functions [...].
   //
   // We (incorrectly) mark overload resolution as an unevaluated context, so we
   // can just check that here.
   OdrUseContext OdrUse =
       MightBeOdrUse ? isOdrUseContext(*this) : OdrUseContext::None;
   if (IsRecursiveCall && OdrUse == OdrUseContext::Used)
     OdrUse = OdrUseContext::FormallyOdrUsed;
 
   // Trivial default constructors and destructors are never actually used.
   // FIXME: What about other special members?
   if (Func->isTrivial() && !Func->hasAttr<DLLExportAttr>() &&
       OdrUse == OdrUseContext::Used) {
     if (auto *Constructor = dyn_cast<CXXConstructorDecl>(Func))
       if (Constructor->isDefaultConstructor())
         OdrUse = OdrUseContext::FormallyOdrUsed;
     if (isa<CXXDestructorDecl>(Func))
       OdrUse = OdrUseContext::FormallyOdrUsed;
   }
 
   // C++20 [expr.const]p12:
   //   A function [...] is needed for constant evaluation if it is [...] a
   //   constexpr function that is named by an expression that is potentially
   //   constant evaluated
   bool NeededForConstantEvaluation =
       isPotentiallyConstantEvaluatedContext(*this) &&
       isImplicitlyDefinableConstexprFunction(Func);
 
   // Determine whether we require a function definition to exist, per
   // C++11 [temp.inst]p3:
   //   Unless a function template specialization has been explicitly
   //   instantiated or explicitly specialized, the function template
   //   specialization is implicitly instantiated when the specialization is
   //   referenced in a context that requires a function definition to exist.
   // C++20 [temp.inst]p7:
   //   The existence of a definition of a [...] function is considered to
   //   affect the semantics of the program if the [...] function is needed for
   //   constant evaluation by an expression
   // C++20 [basic.def.odr]p10:
   //   Every program shall contain exactly one definition of every non-inline
   //   function or variable that is odr-used in that program outside of a
   //   discarded statement
   // C++20 [special]p1:
   //   The implementation will implicitly define [defaulted special members]
   //   if they are odr-used or needed for constant evaluation.
   //
   // Note that we skip the implicit instantiation of templates that are only
   // used in unused default arguments or by recursive calls to themselves.
   // This is formally non-conforming, but seems reasonable in practice.
   bool NeedDefinition = !IsRecursiveCall && (OdrUse == OdrUseContext::Used ||
                                              NeededForConstantEvaluation);
 
   // C++14 [temp.expl.spec]p6:
   //   If a template [...] is explicitly specialized then that specialization
   //   shall be declared before the first use of that specialization that would
   //   cause an implicit instantiation to take place, in every translation unit
   //   in which such a use occurs
   if (NeedDefinition &&
       (Func->getTemplateSpecializationKind() != TSK_Undeclared ||
        Func->getMemberSpecializationInfo()))
     checkSpecializationReachability(Loc, Func);
 
   if (getLangOpts().CUDA)
     CheckCUDACall(Loc, Func);
 
   // If we need a definition, try to create one.
   if (NeedDefinition && !Func->getBody()) {
     runWithSufficientStackSpace(Loc, [&] {
       if (CXXConstructorDecl *Constructor =
               dyn_cast<CXXConstructorDecl>(Func)) {
         Constructor = cast<CXXConstructorDecl>(Constructor->getFirstDecl());
         if (Constructor->isDefaulted() && !Constructor->isDeleted()) {
           if (Constructor->isDefaultConstructor()) {
             if (Constructor->isTrivial() &&
                 !Constructor->hasAttr<DLLExportAttr>())
               return;
             DefineImplicitDefaultConstructor(Loc, Constructor);
           } else if (Constructor->isCopyConstructor()) {
             DefineImplicitCopyConstructor(Loc, Constructor);
           } else if (Constructor->isMoveConstructor()) {
             DefineImplicitMoveConstructor(Loc, Constructor);
           }
         } else if (Constructor->getInheritedConstructor()) {
           DefineInheritingConstructor(Loc, Constructor);
         }
       } else if (CXXDestructorDecl *Destructor =
                      dyn_cast<CXXDestructorDecl>(Func)) {
         Destructor = cast<CXXDestructorDecl>(Destructor->getFirstDecl());
         if (Destructor->isDefaulted() && !Destructor->isDeleted()) {
           if (Destructor->isTrivial() && !Destructor->hasAttr<DLLExportAttr>())
             return;
           DefineImplicitDestructor(Loc, Destructor);
         }
         if (Destructor->isVirtual() && getLangOpts().AppleKext)
           MarkVTableUsed(Loc, Destructor->getParent());
       } else if (CXXMethodDecl *MethodDecl = dyn_cast<CXXMethodDecl>(Func)) {
         if (MethodDecl->isOverloadedOperator() &&
             MethodDecl->getOverloadedOperator() == OO_Equal) {
           MethodDecl = cast<CXXMethodDecl>(MethodDecl->getFirstDecl());
           if (MethodDecl->isDefaulted() && !MethodDecl->isDeleted()) {
             if (MethodDecl->isCopyAssignmentOperator())
               DefineImplicitCopyAssignment(Loc, MethodDecl);
             else if (MethodDecl->isMoveAssignmentOperator())
               DefineImplicitMoveAssignment(Loc, MethodDecl);
           }
         } else if (isa<CXXConversionDecl>(MethodDecl) &&
                    MethodDecl->getParent()->isLambda()) {
           CXXConversionDecl *Conversion =
               cast<CXXConversionDecl>(MethodDecl->getFirstDecl());
           if (Conversion->isLambdaToBlockPointerConversion())
             DefineImplicitLambdaToBlockPointerConversion(Loc, Conversion);
           else
             DefineImplicitLambdaToFunctionPointerConversion(Loc, Conversion);
         } else if (MethodDecl->isVirtual() && getLangOpts().AppleKext)
           MarkVTableUsed(Loc, MethodDecl->getParent());
       }
 
       if (Func->isDefaulted() && !Func->isDeleted()) {
         DefaultedComparisonKind DCK = getDefaultedComparisonKind(Func);
         if (DCK != DefaultedComparisonKind::None)
           DefineDefaultedComparison(Loc, Func, DCK);
       }
 
       // Implicit instantiation of function templates and member functions of
       // class templates.
       if (Func->isImplicitlyInstantiable()) {
         TemplateSpecializationKind TSK =
             Func->getTemplateSpecializationKindForInstantiation();
         SourceLocation PointOfInstantiation = Func->getPointOfInstantiation();
         bool FirstInstantiation = PointOfInstantiation.isInvalid();
         if (FirstInstantiation) {
           PointOfInstantiation = Loc;
           if (auto *MSI = Func->getMemberSpecializationInfo())
             MSI->setPointOfInstantiation(Loc);
             // FIXME: Notify listener.
           else
             Func->setTemplateSpecializationKind(TSK, PointOfInstantiation);
         } else if (TSK != TSK_ImplicitInstantiation) {
           // Use the point of use as the point of instantiation, instead of the
           // point of explicit instantiation (which we track as the actual point
           // of instantiation). This gives better backtraces in diagnostics.
           PointOfInstantiation = Loc;
         }
 
         if (FirstInstantiation || TSK != TSK_ImplicitInstantiation ||
             Func->isConstexpr()) {
           if (isa<CXXRecordDecl>(Func->getDeclContext()) &&
               cast<CXXRecordDecl>(Func->getDeclContext())->isLocalClass() &&
               CodeSynthesisContexts.size())
             PendingLocalImplicitInstantiations.push_back(
                 std::make_pair(Func, PointOfInstantiation));
           else if (Func->isConstexpr())
             // Do not defer instantiations of constexpr functions, to avoid the
             // expression evaluator needing to call back into Sema if it sees a
             // call to such a function.
             InstantiateFunctionDefinition(PointOfInstantiation, Func);
           else {
             Func->setInstantiationIsPending(true);
             PendingInstantiations.push_back(
                 std::make_pair(Func, PointOfInstantiation));
             // Notify the consumer that a function was implicitly instantiated.
             Consumer.HandleCXXImplicitFunctionInstantiation(Func);
           }
         }
       } else {
         // Walk redefinitions, as some of them may be instantiable.
         for (auto *i : Func->redecls()) {
           if (!i->isUsed(false) && i->isImplicitlyInstantiable())
             MarkFunctionReferenced(Loc, i, MightBeOdrUse);
         }
       }
     });
   }
 
   // If a constructor was defined in the context of a default parameter
   // or of another default member initializer (ie a PotentiallyEvaluatedIfUsed
   // context), its initializers may not be referenced yet.
   if (CXXConstructorDecl *Constructor = dyn_cast<CXXConstructorDecl>(Func)) {
     EnterExpressionEvaluationContext EvalContext(
         *this,
         Constructor->isImmediateFunction()
             ? ExpressionEvaluationContext::ImmediateFunctionContext
             : ExpressionEvaluationContext::PotentiallyEvaluated,
         Constructor);
     for (CXXCtorInitializer *Init : Constructor->inits()) {
       if (Init->isInClassMemberInitializer())
         runWithSufficientStackSpace(Init->getSourceLocation(), [&]() {
           MarkDeclarationsReferencedInExpr(Init->getInit());
         });
     }
   }
 
   // C++14 [except.spec]p17:
   //   An exception-specification is considered to be needed when:
   //   - the function is odr-used or, if it appears in an unevaluated operand,
   //     would be odr-used if the expression were potentially-evaluated;
   //
   // Note, we do this even if MightBeOdrUse is false. That indicates that the
   // function is a pure virtual function we're calling, and in that case the
   // function was selected by overload resolution and we need to resolve its
   // exception specification for a different reason.
   const FunctionProtoType *FPT = Func->getType()->getAs<FunctionProtoType>();
   if (FPT && isUnresolvedExceptionSpec(FPT->getExceptionSpecType()))
     ResolveExceptionSpec(Loc, FPT);
 
   // If this is the first "real" use, act on that.
   if (OdrUse == OdrUseContext::Used && !Func->isUsed(/*CheckUsedAttr=*/false)) {
     // Keep track of used but undefined functions.
     if (!Func->isDefined()) {
       if (mightHaveNonExternalLinkage(Func))
         UndefinedButUsed.insert(std::make_pair(Func->getCanonicalDecl(), Loc));
       else if (Func->getMostRecentDecl()->isInlined() &&
                !LangOpts.GNUInline &&
                !Func->getMostRecentDecl()->hasAttr<GNUInlineAttr>())
         UndefinedButUsed.insert(std::make_pair(Func->getCanonicalDecl(), Loc));
       else if (isExternalWithNoLinkageType(Func))
         UndefinedButUsed.insert(std::make_pair(Func->getCanonicalDecl(), Loc));
     }
 
     // Some x86 Windows calling conventions mangle the size of the parameter
     // pack into the name. Computing the size of the parameters requires the
     // parameter types to be complete. Check that now.
     if (funcHasParameterSizeMangling(*this, Func))
       CheckCompleteParameterTypesForMangler(*this, Func, Loc);
 
     // In the MS C++ ABI, the compiler emits destructor variants where they are
     // used. If the destructor is used here but defined elsewhere, mark the
     // virtual base destructors referenced. If those virtual base destructors
     // are inline, this will ensure they are defined when emitting the complete
     // destructor variant. This checking may be redundant if the destructor is
     // provided later in this TU.
     if (Context.getTargetInfo().getCXXABI().isMicrosoft()) {
       if (auto *Dtor = dyn_cast<CXXDestructorDecl>(Func)) {
         CXXRecordDecl *Parent = Dtor->getParent();
         if (Parent->getNumVBases() > 0 && !Dtor->getBody())
           CheckCompleteDestructorVariant(Loc, Dtor);
       }
     }
 
     Func->markUsed(Context);
   }
 }
 
 /// Directly mark a variable odr-used. Given a choice, prefer to use
 /// MarkVariableReferenced since it does additional checks and then
 /// calls MarkVarDeclODRUsed.
 /// If the variable must be captured:
 ///  - if FunctionScopeIndexToStopAt is null, capture it in the CurContext
 ///  - else capture it in the DeclContext that maps to the
 ///    *FunctionScopeIndexToStopAt on the FunctionScopeInfo stack.
 static void
 MarkVarDeclODRUsed(ValueDecl *V, SourceLocation Loc, Sema &SemaRef,
                    const unsigned *const FunctionScopeIndexToStopAt = nullptr) {
   // Keep track of used but undefined variables.
   // FIXME: We shouldn't suppress this warning for static data members.
   VarDecl *Var = V->getPotentiallyDecomposedVarDecl();
   assert(Var && "expected a capturable variable");
 
   if (Var->hasDefinition(SemaRef.Context) == VarDecl::DeclarationOnly &&
       (!Var->isExternallyVisible() || Var->isInline() ||
        SemaRef.isExternalWithNoLinkageType(Var)) &&
       !(Var->isStaticDataMember() && Var->hasInit())) {
     SourceLocation &old = SemaRef.UndefinedButUsed[Var->getCanonicalDecl()];
     if (old.isInvalid())
       old = Loc;
   }
   QualType CaptureType, DeclRefType;
   if (SemaRef.LangOpts.OpenMP)
     SemaRef.tryCaptureOpenMPLambdas(V);
   SemaRef.tryCaptureVariable(V, Loc, Sema::TryCapture_Implicit,
                              /*EllipsisLoc*/ SourceLocation(),
                              /*BuildAndDiagnose*/ true, CaptureType,
                              DeclRefType, FunctionScopeIndexToStopAt);
 
   if (SemaRef.LangOpts.CUDA && Var->hasGlobalStorage()) {
     auto *FD = dyn_cast_or_null<FunctionDecl>(SemaRef.CurContext);
     auto VarTarget = SemaRef.IdentifyCUDATarget(Var);
     auto UserTarget = SemaRef.IdentifyCUDATarget(FD);
     if (VarTarget == Sema::CVT_Host &&
         (UserTarget == Sema::CFT_Device || UserTarget == Sema::CFT_HostDevice ||
          UserTarget == Sema::CFT_Global)) {
       // Diagnose ODR-use of host global variables in device functions.
       // Reference of device global variables in host functions is allowed
       // through shadow variables therefore it is not diagnosed.
       if (SemaRef.LangOpts.CUDAIsDevice) {
         SemaRef.targetDiag(Loc, diag::err_ref_bad_target)
             << /*host*/ 2 << /*variable*/ 1 << Var << UserTarget;
         SemaRef.targetDiag(Var->getLocation(),
                            Var->getType().isConstQualified()
                                ? diag::note_cuda_const_var_unpromoted
                                : diag::note_cuda_host_var);
       }
     } else if (VarTarget == Sema::CVT_Device &&
                (UserTarget == Sema::CFT_Host ||
                 UserTarget == Sema::CFT_HostDevice)) {
       // Record a CUDA/HIP device side variable if it is ODR-used
       // by host code. This is done conservatively, when the variable is
       // referenced in any of the following contexts:
       //   - a non-function context
       //   - a host function
       //   - a host device function
       // This makes the ODR-use of the device side variable by host code to
       // be visible in the device compilation for the compiler to be able to
       // emit template variables instantiated by host code only and to
       // externalize the static device side variable ODR-used by host code.
       if (!Var->hasExternalStorage())
         SemaRef.getASTContext().CUDADeviceVarODRUsedByHost.insert(Var);
       else if (SemaRef.LangOpts.GPURelocatableDeviceCode)
         SemaRef.getASTContext().CUDAExternalDeviceDeclODRUsedByHost.insert(Var);
     }
   }
 
   V->markUsed(SemaRef.Context);
 }
 
 void Sema::MarkCaptureUsedInEnclosingContext(ValueDecl *Capture,
                                              SourceLocation Loc,
                                              unsigned CapturingScopeIndex) {
   MarkVarDeclODRUsed(Capture, Loc, *this, &CapturingScopeIndex);
 }
 
 void diagnoseUncapturableValueReferenceOrBinding(Sema &S, SourceLocation loc,
                                                  ValueDecl *var) {
   DeclContext *VarDC = var->getDeclContext();
 
   //  If the parameter still belongs to the translation unit, then
   //  we're actually just using one parameter in the declaration of
   //  the next.
   if (isa<ParmVarDecl>(var) &&
       isa<TranslationUnitDecl>(VarDC))
     return;
 
   // For C code, don't diagnose about capture if we're not actually in code
   // right now; it's impossible to write a non-constant expression outside of
   // function context, so we'll get other (more useful) diagnostics later.
   //
   // For C++, things get a bit more nasty... it would be nice to suppress this
   // diagnostic for certain cases like using a local variable in an array bound
   // for a member of a local class, but the correct predicate is not obvious.
   if (!S.getLangOpts().CPlusPlus && !S.CurContext->isFunctionOrMethod())
     return;
 
   unsigned ValueKind = isa<BindingDecl>(var) ? 1 : 0;
   unsigned ContextKind = 3; // unknown
   if (isa<CXXMethodDecl>(VarDC) &&
       cast<CXXRecordDecl>(VarDC->getParent())->isLambda()) {
     ContextKind = 2;
   } else if (isa<FunctionDecl>(VarDC)) {
     ContextKind = 0;
   } else if (isa<BlockDecl>(VarDC)) {
     ContextKind = 1;
   }
 
   S.Diag(loc, diag::err_reference_to_local_in_enclosing_context)
     << var << ValueKind << ContextKind << VarDC;
   S.Diag(var->getLocation(), diag::note_entity_declared_at)
       << var;
 
   // FIXME: Add additional diagnostic info about class etc. which prevents
   // capture.
 }
 
 static bool isVariableAlreadyCapturedInScopeInfo(CapturingScopeInfo *CSI,
                                                  ValueDecl *Var,
                                                  bool &SubCapturesAreNested,
                                                  QualType &CaptureType,
                                                  QualType &DeclRefType) {
   // Check whether we've already captured it.
   if (CSI->CaptureMap.count(Var)) {
     // If we found a capture, any subcaptures are nested.
     SubCapturesAreNested = true;
 
     // Retrieve the capture type for this variable.
     CaptureType = CSI->getCapture(Var).getCaptureType();
 
     // Compute the type of an expression that refers to this variable.
     DeclRefType = CaptureType.getNonReferenceType();
 
     // Similarly to mutable captures in lambda, all the OpenMP captures by copy
     // are mutable in the sense that user can change their value - they are
     // private instances of the captured declarations.
     const Capture &Cap = CSI->getCapture(Var);
     if (Cap.isCopyCapture() &&
         !(isa<LambdaScopeInfo>(CSI) && cast<LambdaScopeInfo>(CSI)->Mutable) &&
         !(isa<CapturedRegionScopeInfo>(CSI) &&
           cast<CapturedRegionScopeInfo>(CSI)->CapRegionKind == CR_OpenMP))
       DeclRefType.addConst();
     return true;
   }
   return false;
 }
 
 // Only block literals, captured statements, and lambda expressions can
 // capture; other scopes don't work.
 static DeclContext *getParentOfCapturingContextOrNull(DeclContext *DC,
                                                       ValueDecl *Var,
                                                       SourceLocation Loc,
                                                       const bool Diagnose,
                                                       Sema &S) {
   if (isa<BlockDecl>(DC) || isa<CapturedDecl>(DC) || isLambdaCallOperator(DC))
     return getLambdaAwareParentOfDeclContext(DC);
 
   VarDecl *Underlying = Var->getPotentiallyDecomposedVarDecl();
   if (Underlying) {
     if (Underlying->hasLocalStorage() && Diagnose)
       diagnoseUncapturableValueReferenceOrBinding(S, Loc, Var);
   }
   return nullptr;
 }
 
 // Certain capturing entities (lambdas, blocks etc.) are not allowed to capture
 // certain types of variables (unnamed, variably modified types etc.)
 // so check for eligibility.
 static bool isVariableCapturable(CapturingScopeInfo *CSI, ValueDecl *Var,
                                  SourceLocation Loc, const bool Diagnose,
                                  Sema &S) {
 
   assert((isa<VarDecl, BindingDecl>(Var)) &&
          "Only variables and structured bindings can be captured");
 
   bool IsBlock = isa<BlockScopeInfo>(CSI);
   bool IsLambda = isa<LambdaScopeInfo>(CSI);
 
   // Lambdas are not allowed to capture unnamed variables
   // (e.g. anonymous unions).
   // FIXME: The C++11 rule don't actually state this explicitly, but I'm
   // assuming that's the intent.
   if (IsLambda && !Var->getDeclName()) {
     if (Diagnose) {
       S.Diag(Loc, diag::err_lambda_capture_anonymous_var);
       S.Diag(Var->getLocation(), diag::note_declared_at);
     }
     return false;
   }
 
   // Prohibit variably-modified types in blocks; they're difficult to deal with.
   if (Var->getType()->isVariablyModifiedType() && IsBlock) {
     if (Diagnose) {
       S.Diag(Loc, diag::err_ref_vm_type);
       S.Diag(Var->getLocation(), diag::note_previous_decl) << Var;
     }
     return false;
   }
   // Prohibit structs with flexible array members too.
   // We cannot capture what is in the tail end of the struct.
   if (const RecordType *VTTy = Var->getType()->getAs<RecordType>()) {
     if (VTTy->getDecl()->hasFlexibleArrayMember()) {
       if (Diagnose) {
         if (IsBlock)
           S.Diag(Loc, diag::err_ref_flexarray_type);
         else
           S.Diag(Loc, diag::err_lambda_capture_flexarray_type) << Var;
         S.Diag(Var->getLocation(), diag::note_previous_decl) << Var;
       }
       return false;
     }
   }
   const bool HasBlocksAttr = Var->hasAttr<BlocksAttr>();
   // Lambdas and captured statements are not allowed to capture __block
   // variables; they don't support the expected semantics.
   if (HasBlocksAttr && (IsLambda || isa<CapturedRegionScopeInfo>(CSI))) {
     if (Diagnose) {
       S.Diag(Loc, diag::err_capture_block_variable) << Var << !IsLambda;
       S.Diag(Var->getLocation(), diag::note_previous_decl) << Var;
     }
     return false;
   }
   // OpenCL v2.0 s6.12.5: Blocks cannot reference/capture other blocks
   if (S.getLangOpts().OpenCL && IsBlock &&
       Var->getType()->isBlockPointerType()) {
     if (Diagnose)
       S.Diag(Loc, diag::err_opencl_block_ref_block);
     return false;
   }
 
   if (isa<BindingDecl>(Var)) {
     if (!IsLambda || !S.getLangOpts().CPlusPlus) {
       if (Diagnose)
         diagnoseUncapturableValueReferenceOrBinding(S, Loc, Var);
       return false;
     } else if (Diagnose && S.getLangOpts().CPlusPlus) {
       S.Diag(Loc, S.LangOpts.CPlusPlus20
                       ? diag::warn_cxx17_compat_capture_binding
                       : diag::ext_capture_binding)
           << Var;
       S.Diag(Var->getLocation(), diag::note_entity_declared_at) << Var;
     }
   }
 
   return true;
 }
 
 // Returns true if the capture by block was successful.
 static bool captureInBlock(BlockScopeInfo *BSI, ValueDecl *Var,
                            SourceLocation Loc, const bool BuildAndDiagnose,
                            QualType &CaptureType, QualType &DeclRefType,
                            const bool Nested, Sema &S, bool Invalid) {
   bool ByRef = false;
 
   // Blocks are not allowed to capture arrays, excepting OpenCL.
   // OpenCL v2.0 s1.12.5 (revision 40): arrays are captured by reference
   // (decayed to pointers).
   if (!Invalid && !S.getLangOpts().OpenCL && CaptureType->isArrayType()) {
     if (BuildAndDiagnose) {
       S.Diag(Loc, diag::err_ref_array_type);
       S.Diag(Var->getLocation(), diag::note_previous_decl) << Var;
       Invalid = true;
     } else {
       return false;
     }
   }
 
   // Forbid the block-capture of autoreleasing variables.
   if (!Invalid &&
       CaptureType.getObjCLifetime() == Qualifiers::OCL_Autoreleasing) {
     if (BuildAndDiagnose) {
       S.Diag(Loc, diag::err_arc_autoreleasing_capture)
         << /*block*/ 0;
       S.Diag(Var->getLocation(), diag::note_previous_decl) << Var;
       Invalid = true;
     } else {
       return false;
     }
   }
 
   // Warn about implicitly autoreleasing indirect parameters captured by blocks.
   if (const auto *PT = CaptureType->getAs<PointerType>()) {
     QualType PointeeTy = PT->getPointeeType();
 
     if (!Invalid && PointeeTy->getAs<ObjCObjectPointerType>() &&
         PointeeTy.getObjCLifetime() == Qualifiers::OCL_Autoreleasing &&
         !S.Context.hasDirectOwnershipQualifier(PointeeTy)) {
       if (BuildAndDiagnose) {
         SourceLocation VarLoc = Var->getLocation();
         S.Diag(Loc, diag::warn_block_capture_autoreleasing);
         S.Diag(VarLoc, diag::note_declare_parameter_strong);
       }
     }
   }
 
   const bool HasBlocksAttr = Var->hasAttr<BlocksAttr>();
   if (HasBlocksAttr || CaptureType->isReferenceType() ||
       (S.getLangOpts().OpenMP && S.isOpenMPCapturedDecl(Var))) {
     // Block capture by reference does not change the capture or
     // declaration reference types.
     ByRef = true;
   } else {
     // Block capture by copy introduces 'const'.
     CaptureType = CaptureType.getNonReferenceType().withConst();
     DeclRefType = CaptureType;
   }
 
   // Actually capture the variable.
   if (BuildAndDiagnose)
     BSI->addCapture(Var, HasBlocksAttr, ByRef, Nested, Loc, SourceLocation(),
                     CaptureType, Invalid);
 
   return !Invalid;
 }
 
 /// Capture the given variable in the captured region.
 static bool captureInCapturedRegion(
     CapturedRegionScopeInfo *RSI, ValueDecl *Var, SourceLocation Loc,
     const bool BuildAndDiagnose, QualType &CaptureType, QualType &DeclRefType,
     const bool RefersToCapturedVariable, Sema::TryCaptureKind Kind,
     bool IsTopScope, Sema &S, bool Invalid) {
   // By default, capture variables by reference.
   bool ByRef = true;
   if (IsTopScope && Kind != Sema::TryCapture_Implicit) {
     ByRef = (Kind == Sema::TryCapture_ExplicitByRef);
   } else if (S.getLangOpts().OpenMP && RSI->CapRegionKind == CR_OpenMP) {
     // Using an LValue reference type is consistent with Lambdas (see below).
     if (S.isOpenMPCapturedDecl(Var)) {
       bool HasConst = DeclRefType.isConstQualified();
       DeclRefType = DeclRefType.getUnqualifiedType();
       // Don't lose diagnostics about assignments to const.
       if (HasConst)
         DeclRefType.addConst();
     }
     // Do not capture firstprivates in tasks.
     if (S.isOpenMPPrivateDecl(Var, RSI->OpenMPLevel, RSI->OpenMPCaptureLevel) !=
         OMPC_unknown)
       return true;
     ByRef = S.isOpenMPCapturedByRef(Var, RSI->OpenMPLevel,
                                     RSI->OpenMPCaptureLevel);
   }
 
   if (ByRef)
     CaptureType = S.Context.getLValueReferenceType(DeclRefType);
   else
     CaptureType = DeclRefType;
 
   // Actually capture the variable.
   if (BuildAndDiagnose)
     RSI->addCapture(Var, /*isBlock*/ false, ByRef, RefersToCapturedVariable,
                     Loc, SourceLocation(), CaptureType, Invalid);
 
   return !Invalid;
 }
 
 /// Capture the given variable in the lambda.
 static bool captureInLambda(LambdaScopeInfo *LSI, ValueDecl *Var,
                             SourceLocation Loc, const bool BuildAndDiagnose,
                             QualType &CaptureType, QualType &DeclRefType,
                             const bool RefersToCapturedVariable,
                             const Sema::TryCaptureKind Kind,
                             SourceLocation EllipsisLoc, const bool IsTopScope,
                             Sema &S, bool Invalid) {
   // Determine whether we are capturing by reference or by value.
   bool ByRef = false;
   if (IsTopScope && Kind != Sema::TryCapture_Implicit) {
     ByRef = (Kind == Sema::TryCapture_ExplicitByRef);
   } else {
     ByRef = (LSI->ImpCaptureStyle == LambdaScopeInfo::ImpCap_LambdaByref);
   }
 
   BindingDecl *BD = dyn_cast<BindingDecl>(Var);
   // FIXME: We should support capturing structured bindings in OpenMP.
   if (!Invalid && BD && S.LangOpts.OpenMP) {
     if (BuildAndDiagnose) {
       S.Diag(Loc, diag::err_capture_binding_openmp) << Var;
       S.Diag(Var->getLocation(), diag::note_entity_declared_at) << Var;
     }
     Invalid = true;
   }
 
   if (BuildAndDiagnose && S.Context.getTargetInfo().getTriple().isWasm() &&
       CaptureType.getNonReferenceType().isWebAssemblyReferenceType()) {
     S.Diag(Loc, diag::err_wasm_ca_reference) << 0;
     Invalid = true;
   }
 
   // Compute the type of the field that will capture this variable.
   if (ByRef) {
     // C++11 [expr.prim.lambda]p15:
     //   An entity is captured by reference if it is implicitly or
     //   explicitly captured but not captured by copy. It is
     //   unspecified whether additional unnamed non-static data
     //   members are declared in the closure type for entities
     //   captured by reference.
     //
     // FIXME: It is not clear whether we want to build an lvalue reference
     // to the DeclRefType or to CaptureType.getNonReferenceType(). GCC appears
     // to do the former, while EDG does the latter. Core issue 1249 will
     // clarify, but for now we follow GCC because it's a more permissive and
     // easily defensible position.
     CaptureType = S.Context.getLValueReferenceType(DeclRefType);
   } else {
     // C++11 [expr.prim.lambda]p14:
     //   For each entity captured by copy, an unnamed non-static
     //   data member is declared in the closure type. The
     //   declaration order of these members is unspecified. The type
     //   of such a data member is the type of the corresponding
     //   captured entity if the entity is not a reference to an
     //   object, or the referenced type otherwise. [Note: If the
     //   captured entity is a reference to a function, the
     //   corresponding data member is also a reference to a
     //   function. - end note ]
     if (const ReferenceType *RefType = CaptureType->getAs<ReferenceType>()){
       if (!RefType->getPointeeType()->isFunctionType())
         CaptureType = RefType->getPointeeType();
     }
 
     // Forbid the lambda copy-capture of autoreleasing variables.
     if (!Invalid &&
         CaptureType.getObjCLifetime() == Qualifiers::OCL_Autoreleasing) {
       if (BuildAndDiagnose) {
         S.Diag(Loc, diag::err_arc_autoreleasing_capture) << /*lambda*/ 1;
         S.Diag(Var->getLocation(), diag::note_previous_decl)
           << Var->getDeclName();
         Invalid = true;
       } else {
         return false;
       }
     }
 
     // Make sure that by-copy captures are of a complete and non-abstract type.
     if (!Invalid && BuildAndDiagnose) {
       if (!CaptureType->isDependentType() &&
           S.RequireCompleteSizedType(
               Loc, CaptureType,
               diag::err_capture_of_incomplete_or_sizeless_type,
               Var->getDeclName()))
         Invalid = true;
       else if (S.RequireNonAbstractType(Loc, CaptureType,
                                         diag::err_capture_of_abstract_type))
         Invalid = true;
     }
   }
 
   // Compute the type of a reference to this captured variable.
   if (ByRef)
     DeclRefType = CaptureType.getNonReferenceType();
   else {
     // C++ [expr.prim.lambda]p5:
     //   The closure type for a lambda-expression has a public inline
     //   function call operator [...]. This function call operator is
     //   declared const (9.3.1) if and only if the lambda-expression's
     //   parameter-declaration-clause is not followed by mutable.
     DeclRefType = CaptureType.getNonReferenceType();
     if (!LSI->Mutable && !CaptureType->isReferenceType())
       DeclRefType.addConst();
   }
 
   // Add the capture.
   if (BuildAndDiagnose)
     LSI->addCapture(Var, /*isBlock=*/false, ByRef, RefersToCapturedVariable,
                     Loc, EllipsisLoc, CaptureType, Invalid);
 
   return !Invalid;
 }
 
 static bool canCaptureVariableByCopy(ValueDecl *Var,
                                      const ASTContext &Context) {
   // Offer a Copy fix even if the type is dependent.
   if (Var->getType()->isDependentType())
     return true;
   QualType T = Var->getType().getNonReferenceType();
   if (T.isTriviallyCopyableType(Context))
     return true;
   if (CXXRecordDecl *RD = T->getAsCXXRecordDecl()) {
 
     if (!(RD = RD->getDefinition()))
       return false;
     if (RD->hasSimpleCopyConstructor())
       return true;
     if (RD->hasUserDeclaredCopyConstructor())
       for (CXXConstructorDecl *Ctor : RD->ctors())
         if (Ctor->isCopyConstructor())
           return !Ctor->isDeleted();
   }
   return false;
 }
 
 /// Create up to 4 fix-its for explicit reference and value capture of \p Var or
 /// default capture. Fixes may be omitted if they aren't allowed by the
 /// standard, for example we can't emit a default copy capture fix-it if we
 /// already explicitly copy capture capture another variable.
 static void buildLambdaCaptureFixit(Sema &Sema, LambdaScopeInfo *LSI,
                                     ValueDecl *Var) {
   assert(LSI->ImpCaptureStyle == CapturingScopeInfo::ImpCap_None);
   // Don't offer Capture by copy of default capture by copy fixes if Var is
   // known not to be copy constructible.
   bool ShouldOfferCopyFix = canCaptureVariableByCopy(Var, Sema.getASTContext());
 
   SmallString<32> FixBuffer;
   StringRef Separator = LSI->NumExplicitCaptures > 0 ? ", " : "";
   if (Var->getDeclName().isIdentifier() && !Var->getName().empty()) {
     SourceLocation VarInsertLoc = LSI->IntroducerRange.getEnd();
     if (ShouldOfferCopyFix) {
       // Offer fixes to insert an explicit capture for the variable.
       // [] -> [VarName]
       // [OtherCapture] -> [OtherCapture, VarName]
       FixBuffer.assign({Separator, Var->getName()});
       Sema.Diag(VarInsertLoc, diag::note_lambda_variable_capture_fixit)
           << Var << /*value*/ 0
           << FixItHint::CreateInsertion(VarInsertLoc, FixBuffer);
     }
     // As above but capture by reference.
     FixBuffer.assign({Separator, "&", Var->getName()});
     Sema.Diag(VarInsertLoc, diag::note_lambda_variable_capture_fixit)
         << Var << /*reference*/ 1
         << FixItHint::CreateInsertion(VarInsertLoc, FixBuffer);
   }
 
   // Only try to offer default capture if there are no captures excluding this
   // and init captures.
   // [this]: OK.
   // [X = Y]: OK.
   // [&A, &B]: Don't offer.
   // [A, B]: Don't offer.
   if (llvm::any_of(LSI->Captures, [](Capture &C) {
         return !C.isThisCapture() && !C.isInitCapture();
       }))
     return;
 
   // The default capture specifiers, '=' or '&', must appear first in the
   // capture body.
   SourceLocation DefaultInsertLoc =
       LSI->IntroducerRange.getBegin().getLocWithOffset(1);
 
   if (ShouldOfferCopyFix) {
     bool CanDefaultCopyCapture = true;
     // [=, *this] OK since c++17
     // [=, this] OK since c++20
     if (LSI->isCXXThisCaptured() && !Sema.getLangOpts().CPlusPlus20)
       CanDefaultCopyCapture = Sema.getLangOpts().CPlusPlus17
                                   ? LSI->getCXXThisCapture().isCopyCapture()
                                   : false;
     // We can't use default capture by copy if any captures already specified
     // capture by copy.
     if (CanDefaultCopyCapture && llvm::none_of(LSI->Captures, [](Capture &C) {
           return !C.isThisCapture() && !C.isInitCapture() && C.isCopyCapture();
         })) {
       FixBuffer.assign({"=", Separator});
       Sema.Diag(DefaultInsertLoc, diag::note_lambda_default_capture_fixit)
           << /*value*/ 0
           << FixItHint::CreateInsertion(DefaultInsertLoc, FixBuffer);
     }
   }
 
   // We can't use default capture by reference if any captures already specified
   // capture by reference.
   if (llvm::none_of(LSI->Captures, [](Capture &C) {
         return !C.isInitCapture() && C.isReferenceCapture() &&
                !C.isThisCapture();
       })) {
     FixBuffer.assign({"&", Separator});
     Sema.Diag(DefaultInsertLoc, diag::note_lambda_default_capture_fixit)
         << /*reference*/ 1
         << FixItHint::CreateInsertion(DefaultInsertLoc, FixBuffer);
   }
 }
 
 bool Sema::tryCaptureVariable(
     ValueDecl *Var, SourceLocation ExprLoc, TryCaptureKind Kind,
     SourceLocation EllipsisLoc, bool BuildAndDiagnose, QualType &CaptureType,
     QualType &DeclRefType, const unsigned *const FunctionScopeIndexToStopAt) {
   // An init-capture is notionally from the context surrounding its
   // declaration, but its parent DC is the lambda class.
   DeclContext *VarDC = Var->getDeclContext();
   DeclContext *DC = CurContext;
 
   // tryCaptureVariable is called every time a DeclRef is formed,
   // it can therefore have non-negigible impact on performances.
   // For local variables and when there is no capturing scope,
   // we can bailout early.
   if (CapturingFunctionScopes == 0 && (!BuildAndDiagnose || VarDC == DC))
     return true;
 
   const auto *VD = dyn_cast<VarDecl>(Var);
   if (VD) {
     if (VD->isInitCapture())
       VarDC = VarDC->getParent();
   } else {
     VD = Var->getPotentiallyDecomposedVarDecl();
   }
   assert(VD && "Cannot capture a null variable");
 
   const unsigned MaxFunctionScopesIndex = FunctionScopeIndexToStopAt
       ? *FunctionScopeIndexToStopAt : FunctionScopes.size() - 1;
   // We need to sync up the Declaration Context with the
   // FunctionScopeIndexToStopAt
   if (FunctionScopeIndexToStopAt) {
     unsigned FSIndex = FunctionScopes.size() - 1;
     while (FSIndex != MaxFunctionScopesIndex) {
       DC = getLambdaAwareParentOfDeclContext(DC);
       --FSIndex;
     }
   }
 
   // Capture global variables if it is required to use private copy of this
   // variable.
   bool IsGlobal = !VD->hasLocalStorage();
   if (IsGlobal &&
       !(LangOpts.OpenMP && isOpenMPCapturedDecl(Var, /*CheckScopeInfo=*/true,
                                                 MaxFunctionScopesIndex)))
     return true;
 
   if (isa<VarDecl>(Var))
     Var = cast<VarDecl>(Var->getCanonicalDecl());
 
   // Walk up the stack to determine whether we can capture the variable,
   // performing the "simple" checks that don't depend on type. We stop when
   // we've either hit the declared scope of the variable or find an existing
   // capture of that variable.  We start from the innermost capturing-entity
   // (the DC) and ensure that all intervening capturing-entities
   // (blocks/lambdas etc.) between the innermost capturer and the variable`s
   // declcontext can either capture the variable or have already captured
   // the variable.
   CaptureType = Var->getType();
   DeclRefType = CaptureType.getNonReferenceType();
   bool Nested = false;
   bool Explicit = (Kind != TryCapture_Implicit);
   unsigned FunctionScopesIndex = MaxFunctionScopesIndex;
   do {
 
     LambdaScopeInfo *LSI = nullptr;
     if (!FunctionScopes.empty())
       LSI = dyn_cast_or_null<LambdaScopeInfo>(
           FunctionScopes[FunctionScopesIndex]);
 
     bool IsInScopeDeclarationContext =
         !LSI || LSI->AfterParameterList || CurContext == LSI->CallOperator;
 
     if (LSI && !LSI->AfterParameterList) {
       // This allows capturing parameters from a default value which does not
       // seems correct
       if (isa<ParmVarDecl>(Var) && !Var->getDeclContext()->isFunctionOrMethod())
         return true;
     }
     // If the variable is declared in the current context, there is no need to
     // capture it.
     if (IsInScopeDeclarationContext &&
         FunctionScopesIndex == MaxFunctionScopesIndex && VarDC == DC)
       return true;
 
-    // When evaluating some attributes (like enable_if) we might refer to a
-    // function parameter appertaining to the same declaration as that
-    // attribute.
-    if (const auto *Parm = dyn_cast<ParmVarDecl>(Var);
-        Parm && Parm->getDeclContext() == DC)
-      return true;
-
     // Only block literals, captured statements, and lambda expressions can
     // capture; other scopes don't work.
     DeclContext *ParentDC =
         !IsInScopeDeclarationContext
             ? DC->getParent()
             : getParentOfCapturingContextOrNull(DC, Var, ExprLoc,
                                                 BuildAndDiagnose, *this);
     // We need to check for the parent *first* because, if we *have*
     // private-captured a global variable, we need to recursively capture it in
     // intermediate blocks, lambdas, etc.
     if (!ParentDC) {
       if (IsGlobal) {
         FunctionScopesIndex = MaxFunctionScopesIndex - 1;
         break;
       }
       return true;
     }
 
     FunctionScopeInfo  *FSI = FunctionScopes[FunctionScopesIndex];
     CapturingScopeInfo *CSI = cast<CapturingScopeInfo>(FSI);
 
     // Check whether we've already captured it.
     if (isVariableAlreadyCapturedInScopeInfo(CSI, Var, Nested, CaptureType,
                                              DeclRefType)) {
       CSI->getCapture(Var).markUsed(BuildAndDiagnose);
       break;
     }
+
+    // When evaluating some attributes (like enable_if) we might refer to a
+    // function parameter appertaining to the same declaration as that
+    // attribute.
+    if (const auto *Parm = dyn_cast<ParmVarDecl>(Var);
+        Parm && Parm->getDeclContext() == DC)
+      return true;
+
     // If we are instantiating a generic lambda call operator body,
     // we do not want to capture new variables.  What was captured
     // during either a lambdas transformation or initial parsing
     // should be used.
     if (isGenericLambdaCallOperatorSpecialization(DC)) {
       if (BuildAndDiagnose) {
         LambdaScopeInfo *LSI = cast<LambdaScopeInfo>(CSI);
         if (LSI->ImpCaptureStyle == CapturingScopeInfo::ImpCap_None) {
           Diag(ExprLoc, diag::err_lambda_impcap) << Var;
           Diag(Var->getLocation(), diag::note_previous_decl) << Var;
           Diag(LSI->Lambda->getBeginLoc(), diag::note_lambda_decl);
           buildLambdaCaptureFixit(*this, LSI, Var);
         } else
           diagnoseUncapturableValueReferenceOrBinding(*this, ExprLoc, Var);
       }
       return true;
     }
 
     // Try to capture variable-length arrays types.
     if (Var->getType()->isVariablyModifiedType()) {
       // We're going to walk down into the type and look for VLA
       // expressions.
       QualType QTy = Var->getType();
       if (ParmVarDecl *PVD = dyn_cast_or_null<ParmVarDecl>(Var))
         QTy = PVD->getOriginalType();
       captureVariablyModifiedType(Context, QTy, CSI);
     }
 
     if (getLangOpts().OpenMP) {
       if (auto *RSI = dyn_cast<CapturedRegionScopeInfo>(CSI)) {
         // OpenMP private variables should not be captured in outer scope, so
         // just break here. Similarly, global variables that are captured in a
         // target region should not be captured outside the scope of the region.
         if (RSI->CapRegionKind == CR_OpenMP) {
           OpenMPClauseKind IsOpenMPPrivateDecl = isOpenMPPrivateDecl(
               Var, RSI->OpenMPLevel, RSI->OpenMPCaptureLevel);
           // If the variable is private (i.e. not captured) and has variably
           // modified type, we still need to capture the type for correct
           // codegen in all regions, associated with the construct. Currently,
           // it is captured in the innermost captured region only.
           if (IsOpenMPPrivateDecl != OMPC_unknown &&
               Var->getType()->isVariablyModifiedType()) {
             QualType QTy = Var->getType();
             if (ParmVarDecl *PVD = dyn_cast_or_null<ParmVarDecl>(Var))
               QTy = PVD->getOriginalType();
             for (int I = 1, E = getNumberOfConstructScopes(RSI->OpenMPLevel);
                  I < E; ++I) {
               auto *OuterRSI = cast<CapturedRegionScopeInfo>(
                   FunctionScopes[FunctionScopesIndex - I]);
               assert(RSI->OpenMPLevel == OuterRSI->OpenMPLevel &&
                      "Wrong number of captured regions associated with the "
                      "OpenMP construct.");
               captureVariablyModifiedType(Context, QTy, OuterRSI);
             }
           }
           bool IsTargetCap =
               IsOpenMPPrivateDecl != OMPC_private &&
               isOpenMPTargetCapturedDecl(Var, RSI->OpenMPLevel,
                                          RSI->OpenMPCaptureLevel);
           // Do not capture global if it is not privatized in outer regions.
           bool IsGlobalCap =
               IsGlobal && isOpenMPGlobalCapturedDecl(Var, RSI->OpenMPLevel,
                                                      RSI->OpenMPCaptureLevel);
 
           // When we detect target captures we are looking from inside the
           // target region, therefore we need to propagate the capture from the
           // enclosing region. Therefore, the capture is not initially nested.
           if (IsTargetCap)
             adjustOpenMPTargetScopeIndex(FunctionScopesIndex, RSI->OpenMPLevel);
 
           if (IsTargetCap || IsOpenMPPrivateDecl == OMPC_private ||
               (IsGlobal && !IsGlobalCap)) {
             Nested = !IsTargetCap;
             bool HasConst = DeclRefType.isConstQualified();
             DeclRefType = DeclRefType.getUnqualifiedType();
             // Don't lose diagnostics about assignments to const.
             if (HasConst)
               DeclRefType.addConst();
             CaptureType = Context.getLValueReferenceType(DeclRefType);
             break;
           }
         }
       }
     }
     if (CSI->ImpCaptureStyle == CapturingScopeInfo::ImpCap_None && !Explicit) {
       // No capture-default, and this is not an explicit capture
       // so cannot capture this variable.
       if (BuildAndDiagnose) {
         Diag(ExprLoc, diag::err_lambda_impcap) << Var;
         Diag(Var->getLocation(), diag::note_previous_decl) << Var;
         auto *LSI = cast<LambdaScopeInfo>(CSI);
         if (LSI->Lambda) {
           Diag(LSI->Lambda->getBeginLoc(), diag::note_lambda_decl);
           buildLambdaCaptureFixit(*this, LSI, Var);
         }
         // FIXME: If we error out because an outer lambda can not implicitly
         // capture a variable that an inner lambda explicitly captures, we
         // should have the inner lambda do the explicit capture - because
         // it makes for cleaner diagnostics later.  This would purely be done
         // so that the diagnostic does not misleadingly claim that a variable
         // can not be captured by a lambda implicitly even though it is captured
         // explicitly.  Suggestion:
         //  - create const bool VariableCaptureWasInitiallyExplicit = Explicit
         //    at the function head
         //  - cache the StartingDeclContext - this must be a lambda
         //  - captureInLambda in the innermost lambda the variable.
       }
       return true;
     }
     Explicit = false;
     FunctionScopesIndex--;
     if (IsInScopeDeclarationContext)
       DC = ParentDC;
   } while (!VarDC->Equals(DC));
 
   // Walk back down the scope stack, (e.g. from outer lambda to inner lambda)
   // computing the type of the capture at each step, checking type-specific
   // requirements, and adding captures if requested.
   // If the variable had already been captured previously, we start capturing
   // at the lambda nested within that one.
   bool Invalid = false;
   for (unsigned I = ++FunctionScopesIndex, N = MaxFunctionScopesIndex + 1; I != N;
        ++I) {
     CapturingScopeInfo *CSI = cast<CapturingScopeInfo>(FunctionScopes[I]);
 
     // Certain capturing entities (lambdas, blocks etc.) are not allowed to capture
     // certain types of variables (unnamed, variably modified types etc.)
     // so check for eligibility.
     if (!Invalid)
       Invalid =
           !isVariableCapturable(CSI, Var, ExprLoc, BuildAndDiagnose, *this);
 
     // After encountering an error, if we're actually supposed to capture, keep
     // capturing in nested contexts to suppress any follow-on diagnostics.
     if (Invalid && !BuildAndDiagnose)
       return true;
 
     if (BlockScopeInfo *BSI = dyn_cast<BlockScopeInfo>(CSI)) {
       Invalid = !captureInBlock(BSI, Var, ExprLoc, BuildAndDiagnose, CaptureType,
                                DeclRefType, Nested, *this, Invalid);
       Nested = true;
     } else if (CapturedRegionScopeInfo *RSI = dyn_cast<CapturedRegionScopeInfo>(CSI)) {
       Invalid = !captureInCapturedRegion(
           RSI, Var, ExprLoc, BuildAndDiagnose, CaptureType, DeclRefType, Nested,
           Kind, /*IsTopScope*/ I == N - 1, *this, Invalid);
       Nested = true;
     } else {
       LambdaScopeInfo *LSI = cast<LambdaScopeInfo>(CSI);
       Invalid =
           !captureInLambda(LSI, Var, ExprLoc, BuildAndDiagnose, CaptureType,
                            DeclRefType, Nested, Kind, EllipsisLoc,
                            /*IsTopScope*/ I == N - 1, *this, Invalid);
       Nested = true;
     }
 
     if (Invalid && !BuildAndDiagnose)
       return true;
   }
   return Invalid;
 }
 
 bool Sema::tryCaptureVariable(ValueDecl *Var, SourceLocation Loc,
                               TryCaptureKind Kind, SourceLocation EllipsisLoc) {
   QualType CaptureType;
   QualType DeclRefType;
   return tryCaptureVariable(Var, Loc, Kind, EllipsisLoc,
                             /*BuildAndDiagnose=*/true, CaptureType,
                             DeclRefType, nullptr);
 }
 
 bool Sema::NeedToCaptureVariable(ValueDecl *Var, SourceLocation Loc) {
   QualType CaptureType;
   QualType DeclRefType;
   return !tryCaptureVariable(Var, Loc, TryCapture_Implicit, SourceLocation(),
                              /*BuildAndDiagnose=*/false, CaptureType,
                              DeclRefType, nullptr);
 }
 
 QualType Sema::getCapturedDeclRefType(ValueDecl *Var, SourceLocation Loc) {
   QualType CaptureType;
   QualType DeclRefType;
 
   // Determine whether we can capture this variable.
   if (tryCaptureVariable(Var, Loc, TryCapture_Implicit, SourceLocation(),
                          /*BuildAndDiagnose=*/false, CaptureType,
                          DeclRefType, nullptr))
     return QualType();
 
   return DeclRefType;
 }
 
 namespace {
 // Helper to copy the template arguments from a DeclRefExpr or MemberExpr.
 // The produced TemplateArgumentListInfo* points to data stored within this
 // object, so should only be used in contexts where the pointer will not be
 // used after the CopiedTemplateArgs object is destroyed.
 class CopiedTemplateArgs {
   bool HasArgs;
   TemplateArgumentListInfo TemplateArgStorage;
 public:
   template<typename RefExpr>
   CopiedTemplateArgs(RefExpr *E) : HasArgs(E->hasExplicitTemplateArgs()) {
     if (HasArgs)
       E->copyTemplateArgumentsInto(TemplateArgStorage);
   }
   operator TemplateArgumentListInfo*()
 #ifdef __has_cpp_attribute
 #if __has_cpp_attribute(clang::lifetimebound)
   [[clang::lifetimebound]]
 #endif
 #endif
   {
     return HasArgs ? &TemplateArgStorage : nullptr;
   }
 };
 }
 
 /// Walk the set of potential results of an expression and mark them all as
 /// non-odr-uses if they satisfy the side-conditions of the NonOdrUseReason.
 ///
 /// \return A new expression if we found any potential results, ExprEmpty() if
 ///         not, and ExprError() if we diagnosed an error.
 static ExprResult rebuildPotentialResultsAsNonOdrUsed(Sema &S, Expr *E,
                                                       NonOdrUseReason NOUR) {
   // Per C++11 [basic.def.odr], a variable is odr-used "unless it is
   // an object that satisfies the requirements for appearing in a
   // constant expression (5.19) and the lvalue-to-rvalue conversion (4.1)
   // is immediately applied."  This function handles the lvalue-to-rvalue
   // conversion part.
   //
   // If we encounter a node that claims to be an odr-use but shouldn't be, we
   // transform it into the relevant kind of non-odr-use node and rebuild the
   // tree of nodes leading to it.
   //
   // This is a mini-TreeTransform that only transforms a restricted subset of
   // nodes (and only certain operands of them).
 
   // Rebuild a subexpression.
   auto Rebuild = [&](Expr *Sub) {
     return rebuildPotentialResultsAsNonOdrUsed(S, Sub, NOUR);
   };
 
   // Check whether a potential result satisfies the requirements of NOUR.
   auto IsPotentialResultOdrUsed = [&](NamedDecl *D) {
     // Any entity other than a VarDecl is always odr-used whenever it's named
     // in a potentially-evaluated expression.
     auto *VD = dyn_cast<VarDecl>(D);
     if (!VD)
       return true;
 
     // C++2a [basic.def.odr]p4:
     //   A variable x whose name appears as a potentially-evalauted expression
     //   e is odr-used by e unless
     //   -- x is a reference that is usable in constant expressions, or
     //   -- x is a variable of non-reference type that is usable in constant
     //      expressions and has no mutable subobjects, and e is an element of
     //      the set of potential results of an expression of
     //      non-volatile-qualified non-class type to which the lvalue-to-rvalue
     //      conversion is applied, or
     //   -- x is a variable of non-reference type, and e is an element of the
     //      set of potential results of a discarded-value expression to which
     //      the lvalue-to-rvalue conversion is not applied
     //
     // We check the first bullet and the "potentially-evaluated" condition in
     // BuildDeclRefExpr. We check the type requirements in the second bullet
     // in CheckLValueToRValueConversionOperand below.
     switch (NOUR) {
     case NOUR_None:
     case NOUR_Unevaluated:
       llvm_unreachable("unexpected non-odr-use-reason");
 
     case NOUR_Constant:
       // Constant references were handled when they were built.
       if (VD->getType()->isReferenceType())
         return true;
       if (auto *RD = VD->getType()->getAsCXXRecordDecl())
         if (RD->hasMutableFields())
           return true;
       if (!VD->isUsableInConstantExpressions(S.Context))
         return true;
       break;
 
     case NOUR_Discarded:
       if (VD->getType()->isReferenceType())
         return true;
       break;
     }
     return false;
   };
 
   // Mark that this expression does not constitute an odr-use.
   auto MarkNotOdrUsed = [&] {
     S.MaybeODRUseExprs.remove(E);
     if (LambdaScopeInfo *LSI = S.getCurLambda())
       LSI->markVariableExprAsNonODRUsed(E);
   };
 
   // C++2a [basic.def.odr]p2:
   //   The set of potential results of an expression e is defined as follows:
   switch (E->getStmtClass()) {
   //   -- If e is an id-expression, ...
   case Expr::DeclRefExprClass: {
     auto *DRE = cast<DeclRefExpr>(E);
     if (DRE->isNonOdrUse() || IsPotentialResultOdrUsed(DRE->getDecl()))
       break;
 
     // Rebuild as a non-odr-use DeclRefExpr.
     MarkNotOdrUsed();
     return DeclRefExpr::Create(
         S.Context, DRE->getQualifierLoc(), DRE->getTemplateKeywordLoc(),
         DRE->getDecl(), DRE->refersToEnclosingVariableOrCapture(),
         DRE->getNameInfo(), DRE->getType(), DRE->getValueKind(),
         DRE->getFoundDecl(), CopiedTemplateArgs(DRE), NOUR);
   }
 
   case Expr::FunctionParmPackExprClass: {
     auto *FPPE = cast<FunctionParmPackExpr>(E);
     // If any of the declarations in the pack is odr-used, then the expression
     // as a whole constitutes an odr-use.
     for (VarDecl *D : *FPPE)
       if (IsPotentialResultOdrUsed(D))
         return ExprEmpty();
 
     // FIXME: Rebuild as a non-odr-use FunctionParmPackExpr? In practice,
     // nothing cares about whether we marked this as an odr-use, but it might
     // be useful for non-compiler tools.
     MarkNotOdrUsed();
     break;
   }
 
   //   -- If e is a subscripting operation with an array operand...
   case Expr::ArraySubscriptExprClass: {
     auto *ASE = cast<ArraySubscriptExpr>(E);
     Expr *OldBase = ASE->getBase()->IgnoreImplicit();
     if (!OldBase->getType()->isArrayType())
       break;
     ExprResult Base = Rebuild(OldBase);
     if (!Base.isUsable())
       return Base;
     Expr *LHS = ASE->getBase() == ASE->getLHS() ? Base.get() : ASE->getLHS();
     Expr *RHS = ASE->getBase() == ASE->getRHS() ? Base.get() : ASE->getRHS();
     SourceLocation LBracketLoc = ASE->getBeginLoc(); // FIXME: Not stored.
     return S.ActOnArraySubscriptExpr(nullptr, LHS, LBracketLoc, RHS,
                                      ASE->getRBracketLoc());
   }
 
   case Expr::MemberExprClass: {
     auto *ME = cast<MemberExpr>(E);
     // -- If e is a class member access expression [...] naming a non-static
     //    data member...
     if (isa<FieldDecl>(ME->getMemberDecl())) {
       ExprResult Base = Rebuild(ME->getBase());
       if (!Base.isUsable())
         return Base;
       return MemberExpr::Create(
           S.Context, Base.get(), ME->isArrow(), ME->getOperatorLoc(),
           ME->getQualifierLoc(), ME->getTemplateKeywordLoc(),
           ME->getMemberDecl(), ME->getFoundDecl(), ME->getMemberNameInfo(),
           CopiedTemplateArgs(ME), ME->getType(), ME->getValueKind(),
           ME->getObjectKind(), ME->isNonOdrUse());
     }
 
     if (ME->getMemberDecl()->isCXXInstanceMember())
       break;
 
     // -- If e is a class member access expression naming a static data member,
     //    ...
     if (ME->isNonOdrUse() || IsPotentialResultOdrUsed(ME->getMemberDecl()))
       break;
 
     // Rebuild as a non-odr-use MemberExpr.
     MarkNotOdrUsed();
     return MemberExpr::Create(
         S.Context, ME->getBase(), ME->isArrow(), ME->getOperatorLoc(),
         ME->getQualifierLoc(), ME->getTemplateKeywordLoc(), ME->getMemberDecl(),
         ME->getFoundDecl(), ME->getMemberNameInfo(), CopiedTemplateArgs(ME),
         ME->getType(), ME->getValueKind(), ME->getObjectKind(), NOUR);
   }
 
   case Expr::BinaryOperatorClass: {
     auto *BO = cast<BinaryOperator>(E);
     Expr *LHS = BO->getLHS();
     Expr *RHS = BO->getRHS();
     // -- If e is a pointer-to-member expression of the form e1 .* e2 ...
     if (BO->getOpcode() == BO_PtrMemD) {
       ExprResult Sub = Rebuild(LHS);
       if (!Sub.isUsable())
         return Sub;
       LHS = Sub.get();
     //   -- If e is a comma expression, ...
     } else if (BO->getOpcode() == BO_Comma) {
       ExprResult Sub = Rebuild(RHS);
       if (!Sub.isUsable())
         return Sub;
       RHS = Sub.get();
     } else {
       break;
     }
     return S.BuildBinOp(nullptr, BO->getOperatorLoc(), BO->getOpcode(),
                         LHS, RHS);
   }
 
   //   -- If e has the form (e1)...
   case Expr::ParenExprClass: {
     auto *PE = cast<ParenExpr>(E);
     ExprResult Sub = Rebuild(PE->getSubExpr());
     if (!Sub.isUsable())
       return Sub;
     return S.ActOnParenExpr(PE->getLParen(), PE->getRParen(), Sub.get());
   }
 
   //   -- If e is a glvalue conditional expression, ...
   // We don't apply this to a binary conditional operator. FIXME: Should we?
   case Expr::ConditionalOperatorClass: {
     auto *CO = cast<ConditionalOperator>(E);
     ExprResult LHS = Rebuild(CO->getLHS());
     if (LHS.isInvalid())
       return ExprError();
     ExprResult RHS = Rebuild(CO->getRHS());
     if (RHS.isInvalid())
       return ExprError();
     if (!LHS.isUsable() && !RHS.isUsable())
       return ExprEmpty();
     if (!LHS.isUsable())
       LHS = CO->getLHS();
     if (!RHS.isUsable())
       RHS = CO->getRHS();
     return S.ActOnConditionalOp(CO->getQuestionLoc(), CO->getColonLoc(),
                                 CO->getCond(), LHS.get(), RHS.get());
   }
 
   // [Clang extension]
   //   -- If e has the form __extension__ e1...
   case Expr::UnaryOperatorClass: {
     auto *UO = cast<UnaryOperator>(E);
     if (UO->getOpcode() != UO_Extension)
       break;
     ExprResult Sub = Rebuild(UO->getSubExpr());
     if (!Sub.isUsable())
       return Sub;
     return S.BuildUnaryOp(nullptr, UO->getOperatorLoc(), UO_Extension,
                           Sub.get());
   }
 
   // [Clang extension]
   //   -- If e has the form _Generic(...), the set of potential results is the
   //      union of the sets of potential results of the associated expressions.
   case Expr::GenericSelectionExprClass: {
     auto *GSE = cast<GenericSelectionExpr>(E);
 
     SmallVector<Expr *, 4> AssocExprs;
     bool AnyChanged = false;
     for (Expr *OrigAssocExpr : GSE->getAssocExprs()) {
       ExprResult AssocExpr = Rebuild(OrigAssocExpr);
       if (AssocExpr.isInvalid())
         return ExprError();
       if (AssocExpr.isUsable()) {
         AssocExprs.push_back(AssocExpr.get());
         AnyChanged = true;
       } else {
         AssocExprs.push_back(OrigAssocExpr);
       }
     }
 
     void *ExOrTy = nullptr;
     bool IsExpr = GSE->isExprPredicate();
     if (IsExpr)
       ExOrTy = GSE->getControllingExpr();
     else
       ExOrTy = GSE->getControllingType();
     return AnyChanged ? S.CreateGenericSelectionExpr(
                             GSE->getGenericLoc(), GSE->getDefaultLoc(),
                             GSE->getRParenLoc(), IsExpr, ExOrTy,
                             GSE->getAssocTypeSourceInfos(), AssocExprs)
                       : ExprEmpty();
   }
 
   // [Clang extension]
   //   -- If e has the form __builtin_choose_expr(...), the set of potential
   //      results is the union of the sets of potential results of the
   //      second and third subexpressions.
   case Expr::ChooseExprClass: {
     auto *CE = cast<ChooseExpr>(E);
 
     ExprResult LHS = Rebuild(CE->getLHS());
     if (LHS.isInvalid())
       return ExprError();
 
     ExprResult RHS = Rebuild(CE->getLHS());
     if (RHS.isInvalid())
       return ExprError();
 
     if (!LHS.get() && !RHS.get())
       return ExprEmpty();
     if (!LHS.isUsable())
       LHS = CE->getLHS();
     if (!RHS.isUsable())
       RHS = CE->getRHS();
 
     return S.ActOnChooseExpr(CE->getBuiltinLoc(), CE->getCond(), LHS.get(),
                              RHS.get(), CE->getRParenLoc());
   }
 
   // Step through non-syntactic nodes.
   case Expr::ConstantExprClass: {
     auto *CE = cast<ConstantExpr>(E);
     ExprResult Sub = Rebuild(CE->getSubExpr());
     if (!Sub.isUsable())
       return Sub;
     return ConstantExpr::Create(S.Context, Sub.get());
   }
 
   // We could mostly rely on the recursive rebuilding to rebuild implicit
   // casts, but not at the top level, so rebuild them here.
   case Expr::ImplicitCastExprClass: {
     auto *ICE = cast<ImplicitCastExpr>(E);
     // Only step through the narrow set of cast kinds we expect to encounter.
     // Anything else suggests we've left the region in which potential results
     // can be found.
     switch (ICE->getCastKind()) {
     case CK_NoOp:
     case CK_DerivedToBase:
     case CK_UncheckedDerivedToBase: {
       ExprResult Sub = Rebuild(ICE->getSubExpr());
       if (!Sub.isUsable())
         return Sub;
       CXXCastPath Path(ICE->path());
       return S.ImpCastExprToType(Sub.get(), ICE->getType(), ICE->getCastKind(),
                                  ICE->getValueKind(), &Path);
     }
 
     default:
       break;
     }
     break;
   }
 
   default:
     break;
   }
 
   // Can't traverse through this node. Nothing to do.
   return ExprEmpty();
 }
 
 ExprResult Sema::CheckLValueToRValueConversionOperand(Expr *E) {
   // Check whether the operand is or contains an object of non-trivial C union
   // type.
   if (E->getType().isVolatileQualified() &&
       (E->getType().hasNonTrivialToPrimitiveDestructCUnion() ||
        E->getType().hasNonTrivialToPrimitiveCopyCUnion()))
     checkNonTrivialCUnion(E->getType(), E->getExprLoc(),
                           Sema::NTCUC_LValueToRValueVolatile,
                           NTCUK_Destruct|NTCUK_Copy);
 
   // C++2a [basic.def.odr]p4:
   //   [...] an expression of non-volatile-qualified non-class type to which
   //   the lvalue-to-rvalue conversion is applied [...]
   if (E->getType().isVolatileQualified() || E->getType()->getAs<RecordType>())
     return E;
 
   ExprResult Result =
       rebuildPotentialResultsAsNonOdrUsed(*this, E, NOUR_Constant);
   if (Result.isInvalid())
     return ExprError();
   return Result.get() ? Result : E;
 }
 
 ExprResult Sema::ActOnConstantExpression(ExprResult Res) {
   Res = CorrectDelayedTyposInExpr(Res);
 
   if (!Res.isUsable())
     return Res;
 
   // If a constant-expression is a reference to a variable where we delay
   // deciding whether it is an odr-use, just assume we will apply the
   // lvalue-to-rvalue conversion.  In the one case where this doesn't happen
   // (a non-type template argument), we have special handling anyway.
   return CheckLValueToRValueConversionOperand(Res.get());
 }
 
 void Sema::CleanupVarDeclMarking() {
   // Iterate through a local copy in case MarkVarDeclODRUsed makes a recursive
   // call.
   MaybeODRUseExprSet LocalMaybeODRUseExprs;
   std::swap(LocalMaybeODRUseExprs, MaybeODRUseExprs);
 
   for (Expr *E : LocalMaybeODRUseExprs) {
     if (auto *DRE = dyn_cast<DeclRefExpr>(E)) {
       MarkVarDeclODRUsed(cast<VarDecl>(DRE->getDecl()),
                          DRE->getLocation(), *this);
     } else if (auto *ME = dyn_cast<MemberExpr>(E)) {
       MarkVarDeclODRUsed(cast<VarDecl>(ME->getMemberDecl()), ME->getMemberLoc(),
                          *this);
     } else if (auto *FP = dyn_cast<FunctionParmPackExpr>(E)) {
       for (VarDecl *VD : *FP)
         MarkVarDeclODRUsed(VD, FP->getParameterPackLocation(), *this);
     } else {
       llvm_unreachable("Unexpected expression");
     }
   }
 
   assert(MaybeODRUseExprs.empty() &&
          "MarkVarDeclODRUsed failed to cleanup MaybeODRUseExprs?");
 }
 
 static void DoMarkPotentialCapture(Sema &SemaRef, SourceLocation Loc,
                                    ValueDecl *Var, Expr *E) {
   VarDecl *VD = Var->getPotentiallyDecomposedVarDecl();
   if (!VD)
     return;
 
   const bool RefersToEnclosingScope =
       (SemaRef.CurContext != VD->getDeclContext() &&
        VD->getDeclContext()->isFunctionOrMethod() && VD->hasLocalStorage());
   if (RefersToEnclosingScope) {
     LambdaScopeInfo *const LSI =
         SemaRef.getCurLambda(/*IgnoreNonLambdaCapturingScope=*/true);
     if (LSI && (!LSI->CallOperator ||
                 !LSI->CallOperator->Encloses(Var->getDeclContext()))) {
       // If a variable could potentially be odr-used, defer marking it so
       // until we finish analyzing the full expression for any
       // lvalue-to-rvalue
       // or discarded value conversions that would obviate odr-use.
       // Add it to the list of potential captures that will be analyzed
       // later (ActOnFinishFullExpr) for eventual capture and odr-use marking
       // unless the variable is a reference that was initialized by a constant
       // expression (this will never need to be captured or odr-used).
       //
       // FIXME: We can simplify this a lot after implementing P0588R1.
       assert(E && "Capture variable should be used in an expression.");
       if (!Var->getType()->isReferenceType() ||
           !VD->isUsableInConstantExpressions(SemaRef.Context))
         LSI->addPotentialCapture(E->IgnoreParens());
     }
   }
 }
 
 static void DoMarkVarDeclReferenced(
     Sema &SemaRef, SourceLocation Loc, VarDecl *Var, Expr *E,
     llvm::DenseMap<const VarDecl *, int> &RefsMinusAssignments) {
   assert((!E || isa<DeclRefExpr>(E) || isa<MemberExpr>(E) ||
           isa<FunctionParmPackExpr>(E)) &&
          "Invalid Expr argument to DoMarkVarDeclReferenced");
   Var->setReferenced();
 
   if (Var->isInvalidDecl())
     return;
 
   auto *MSI = Var->getMemberSpecializationInfo();
   TemplateSpecializationKind TSK = MSI ? MSI->getTemplateSpecializationKind()
                                        : Var->getTemplateSpecializationKind();
 
   OdrUseContext OdrUse = isOdrUseContext(SemaRef);
   bool UsableInConstantExpr =
       Var->mightBeUsableInConstantExpressions(SemaRef.Context);
 
   if (Var->isLocalVarDeclOrParm() && !Var->hasExternalStorage()) {
     RefsMinusAssignments.insert({Var, 0}).first->getSecond()++;
   }
 
   // C++20 [expr.const]p12:
   //   A variable [...] is needed for constant evaluation if it is [...] a
   //   variable whose name appears as a potentially constant evaluated
   //   expression that is either a contexpr variable or is of non-volatile
   //   const-qualified integral type or of reference type
   bool NeededForConstantEvaluation =
       isPotentiallyConstantEvaluatedContext(SemaRef) && UsableInConstantExpr;
 
   bool NeedDefinition =
       OdrUse == OdrUseContext::Used || NeededForConstantEvaluation;
 
   assert(!isa<VarTemplatePartialSpecializationDecl>(Var) &&
          "Can't instantiate a partial template specialization.");
 
   // If this might be a member specialization of a static data member, check
   // the specialization is visible. We already did the checks for variable
   // template specializations when we created them.
   if (NeedDefinition && TSK != TSK_Undeclared &&
       !isa<VarTemplateSpecializationDecl>(Var))
     SemaRef.checkSpecializationVisibility(Loc, Var);
 
   // Perform implicit instantiation of static data members, static data member
   // templates of class templates, and variable template specializations. Delay
   // instantiations of variable templates, except for those that could be used
   // in a constant expression.
   if (NeedDefinition && isTemplateInstantiation(TSK)) {
     // Per C++17 [temp.explicit]p10, we may instantiate despite an explicit
     // instantiation declaration if a variable is usable in a constant
     // expression (among other cases).
     bool TryInstantiating =
         TSK == TSK_ImplicitInstantiation ||
         (TSK == TSK_ExplicitInstantiationDeclaration && UsableInConstantExpr);
 
     if (TryInstantiating) {
       SourceLocation PointOfInstantiation =
           MSI ? MSI->getPointOfInstantiation() : Var->getPointOfInstantiation();
       bool FirstInstantiation = PointOfInstantiation.isInvalid();
       if (FirstInstantiation) {
         PointOfInstantiation = Loc;
         if (MSI)
           MSI->setPointOfInstantiation(PointOfInstantiation);
           // FIXME: Notify listener.
         else
           Var->setTemplateSpecializationKind(TSK, PointOfInstantiation);
       }
 
       if (UsableInConstantExpr) {
         // Do not defer instantiations of variables that could be used in a
         // constant expression.
         SemaRef.runWithSufficientStackSpace(PointOfInstantiation, [&] {
           SemaRef.InstantiateVariableDefinition(PointOfInstantiation, Var);
         });
 
         // Re-set the member to trigger a recomputation of the dependence bits
         // for the expression.
         if (auto *DRE = dyn_cast_or_null<DeclRefExpr>(E))
           DRE->setDecl(DRE->getDecl());
         else if (auto *ME = dyn_cast_or_null<MemberExpr>(E))
           ME->setMemberDecl(ME->getMemberDecl());
       } else if (FirstInstantiation) {
         SemaRef.PendingInstantiations
             .push_back(std::make_pair(Var, PointOfInstantiation));
       } else {
         bool Inserted = false;
         for (auto &I : SemaRef.SavedPendingInstantiations) {
           auto Iter = llvm::find_if(
               I, [Var](const Sema::PendingImplicitInstantiation &P) {
                 return P.first == Var;
               });
           if (Iter != I.end()) {
             SemaRef.PendingInstantiations.push_back(*Iter);
             I.erase(Iter);
             Inserted = true;
             break;
           }
         }
 
         // FIXME: For a specialization of a variable template, we don't
         // distinguish between "declaration and type implicitly instantiated"
         // and "implicit instantiation of definition requested", so we have
         // no direct way to avoid enqueueing the pending instantiation
         // multiple times.
         if (isa<VarTemplateSpecializationDecl>(Var) && !Inserted)
           SemaRef.PendingInstantiations
             .push_back(std::make_pair(Var, PointOfInstantiation));
       }
     }
   }
 
   // C++2a [basic.def.odr]p4:
   //   A variable x whose name appears as a potentially-evaluated expression e
   //   is odr-used by e unless
   //   -- x is a reference that is usable in constant expressions
   //   -- x is a variable of non-reference type that is usable in constant
   //      expressions and has no mutable subobjects [FIXME], and e is an
   //      element of the set of potential results of an expression of
   //      non-volatile-qualified non-class type to which the lvalue-to-rvalue
   //      conversion is applied
   //   -- x is a variable of non-reference type, and e is an element of the set
   //      of potential results of a discarded-value expression to which the
   //      lvalue-to-rvalue conversion is not applied [FIXME]
   //
   // We check the first part of the second bullet here, and
   // Sema::CheckLValueToRValueConversionOperand deals with the second part.
   // FIXME: To get the third bullet right, we need to delay this even for
   // variables that are not usable in constant expressions.
 
   // If we already know this isn't an odr-use, there's nothing more to do.
   if (DeclRefExpr *DRE = dyn_cast_or_null<DeclRefExpr>(E))
     if (DRE->isNonOdrUse())
       return;
   if (MemberExpr *ME = dyn_cast_or_null<MemberExpr>(E))
     if (ME->isNonOdrUse())
       return;
 
   switch (OdrUse) {
   case OdrUseContext::None:
     // In some cases, a variable may not have been marked unevaluated, if it
     // appears in a defaukt initializer.
     assert((!E || isa<FunctionParmPackExpr>(E) ||
             SemaRef.isUnevaluatedContext()) &&
            "missing non-odr-use marking for unevaluated decl ref");
     break;
 
   case OdrUseContext::FormallyOdrUsed:
     // FIXME: Ignoring formal odr-uses results in incorrect lambda capture
     // behavior.
     break;
 
   case OdrUseContext::Used:
     // If we might later find that this expression isn't actually an odr-use,
     // delay the marking.
     if (E && Var->isUsableInConstantExpressions(SemaRef.Context))
       SemaRef.MaybeODRUseExprs.insert(E);
     else
       MarkVarDeclODRUsed(Var, Loc, SemaRef);
     break;
 
   case OdrUseContext::Dependent:
     // If this is a dependent context, we don't need to mark variables as
     // odr-used, but we may still need to track them for lambda capture.
     // FIXME: Do we also need to do this inside dependent typeid expressions
     // (which are modeled as unevaluated at this point)?
     DoMarkPotentialCapture(SemaRef, Loc, Var, E);
     break;
   }
 }
 
 static void DoMarkBindingDeclReferenced(Sema &SemaRef, SourceLocation Loc,
                                         BindingDecl *BD, Expr *E) {
   BD->setReferenced();
 
   if (BD->isInvalidDecl())
     return;
 
   OdrUseContext OdrUse = isOdrUseContext(SemaRef);
   if (OdrUse == OdrUseContext::Used) {
     QualType CaptureType, DeclRefType;
     SemaRef.tryCaptureVariable(BD, Loc, Sema::TryCapture_Implicit,
                                /*EllipsisLoc*/ SourceLocation(),
                                /*BuildAndDiagnose*/ true, CaptureType,
                                DeclRefType,
                                /*FunctionScopeIndexToStopAt*/ nullptr);
   } else if (OdrUse == OdrUseContext::Dependent) {
     DoMarkPotentialCapture(SemaRef, Loc, BD, E);
   }
 }
 
 /// Mark a variable referenced, and check whether it is odr-used
 /// (C++ [basic.def.odr]p2, C99 6.9p3).  Note that this should not be
 /// used directly for normal expressions referring to VarDecl.
 void Sema::MarkVariableReferenced(SourceLocation Loc, VarDecl *Var) {
   DoMarkVarDeclReferenced(*this, Loc, Var, nullptr, RefsMinusAssignments);
 }
 
 static void
 MarkExprReferenced(Sema &SemaRef, SourceLocation Loc, Decl *D, Expr *E,
                    bool MightBeOdrUse,
                    llvm::DenseMap<const VarDecl *, int> &RefsMinusAssignments) {
   if (SemaRef.isInOpenMPDeclareTargetContext())
     SemaRef.checkDeclIsAllowedInOpenMPTarget(E, D);
 
   if (VarDecl *Var = dyn_cast<VarDecl>(D)) {
     DoMarkVarDeclReferenced(SemaRef, Loc, Var, E, RefsMinusAssignments);
     return;
   }
 
   if (BindingDecl *Decl = dyn_cast<BindingDecl>(D)) {
     DoMarkBindingDeclReferenced(SemaRef, Loc, Decl, E);
     return;
   }
 
   SemaRef.MarkAnyDeclReferenced(Loc, D, MightBeOdrUse);
 
   // If this is a call to a method via a cast, also mark the method in the
   // derived class used in case codegen can devirtualize the call.
   const MemberExpr *ME = dyn_cast<MemberExpr>(E);
   if (!ME)
     return;
   CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(ME->getMemberDecl());
   if (!MD)
     return;
   // Only attempt to devirtualize if this is truly a virtual call.
   bool IsVirtualCall = MD->isVirtual() &&
                           ME->performsVirtualDispatch(SemaRef.getLangOpts());
   if (!IsVirtualCall)
     return;
 
   // If it's possible to devirtualize the call, mark the called function
   // referenced.
   CXXMethodDecl *DM = MD->getDevirtualizedMethod(
       ME->getBase(), SemaRef.getLangOpts().AppleKext);
   if (DM)
     SemaRef.MarkAnyDeclReferenced(Loc, DM, MightBeOdrUse);
 }
 
 /// Perform reference-marking and odr-use handling for a DeclRefExpr.
 ///
 /// Note, this may change the dependence of the DeclRefExpr, and so needs to be
 /// handled with care if the DeclRefExpr is not newly-created.
 void Sema::MarkDeclRefReferenced(DeclRefExpr *E, const Expr *Base) {
   // TODO: update this with DR# once a defect report is filed.
   // C++11 defect. The address of a pure member should not be an ODR use, even
   // if it's a qualified reference.
   bool OdrUse = true;
   if (const CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(E->getDecl()))
     if (Method->isVirtual() &&
         !Method->getDevirtualizedMethod(Base, getLangOpts().AppleKext))
       OdrUse = false;
 
   if (auto *FD = dyn_cast<FunctionDecl>(E->getDecl())) {
     if (!isUnevaluatedContext() && !isConstantEvaluated() &&
         !isImmediateFunctionContext() &&
         !isCheckingDefaultArgumentOrInitializer() &&
         FD->isImmediateFunction() && !RebuildingImmediateInvocation &&
         !FD->isDependentContext())
       ExprEvalContexts.back().ReferenceToConsteval.insert(E);
   }
   MarkExprReferenced(*this, E->getLocation(), E->getDecl(), E, OdrUse,
                      RefsMinusAssignments);
 }
 
 /// Perform reference-marking and odr-use handling for a MemberExpr.
 void Sema::MarkMemberReferenced(MemberExpr *E) {
   // C++11 [basic.def.odr]p2:
   //   A non-overloaded function whose name appears as a potentially-evaluated
   //   expression or a member of a set of candidate functions, if selected by
   //   overload resolution when referred to from a potentially-evaluated
   //   expression, is odr-used, unless it is a pure virtual function and its
   //   name is not explicitly qualified.
   bool MightBeOdrUse = true;
   if (E->performsVirtualDispatch(getLangOpts())) {
     if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(E->getMemberDecl()))
       if (Method->isPure())
         MightBeOdrUse = false;
   }
   SourceLocation Loc =
       E->getMemberLoc().isValid() ? E->getMemberLoc() : E->getBeginLoc();
   MarkExprReferenced(*this, Loc, E->getMemberDecl(), E, MightBeOdrUse,
                      RefsMinusAssignments);
 }
 
 /// Perform reference-marking and odr-use handling for a FunctionParmPackExpr.
 void Sema::MarkFunctionParmPackReferenced(FunctionParmPackExpr *E) {
   for (VarDecl *VD : *E)
     MarkExprReferenced(*this, E->getParameterPackLocation(), VD, E, true,
                        RefsMinusAssignments);
 }
 
 /// Perform marking for a reference to an arbitrary declaration.  It
 /// marks the declaration referenced, and performs odr-use checking for
 /// functions and variables. This method should not be used when building a
 /// normal expression which refers to a variable.
 void Sema::MarkAnyDeclReferenced(SourceLocation Loc, Decl *D,
                                  bool MightBeOdrUse) {
   if (MightBeOdrUse) {
     if (auto *VD = dyn_cast<VarDecl>(D)) {
       MarkVariableReferenced(Loc, VD);
       return;
     }
   }
   if (auto *FD = dyn_cast<FunctionDecl>(D)) {
     MarkFunctionReferenced(Loc, FD, MightBeOdrUse);
     return;
   }
   D->setReferenced();
 }
 
 namespace {
   // Mark all of the declarations used by a type as referenced.
   // FIXME: Not fully implemented yet! We need to have a better understanding
   // of when we're entering a context we should not recurse into.
   // FIXME: This is and EvaluatedExprMarker are more-or-less equivalent to
   // TreeTransforms rebuilding the type in a new context. Rather than
   // duplicating the TreeTransform logic, we should consider reusing it here.
   // Currently that causes problems when rebuilding LambdaExprs.
   class MarkReferencedDecls : public RecursiveASTVisitor<MarkReferencedDecls> {
     Sema &S;
     SourceLocation Loc;
 
   public:
     typedef RecursiveASTVisitor<MarkReferencedDecls> Inherited;
 
     MarkReferencedDecls(Sema &S, SourceLocation Loc) : S(S), Loc(Loc) { }
 
     bool TraverseTemplateArgument(const TemplateArgument &Arg);
   };
 }
 
 bool MarkReferencedDecls::TraverseTemplateArgument(
     const TemplateArgument &Arg) {
   {
     // A non-type template argument is a constant-evaluated context.
     EnterExpressionEvaluationContext Evaluated(
         S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
     if (Arg.getKind() == TemplateArgument::Declaration) {
       if (Decl *D = Arg.getAsDecl())
         S.MarkAnyDeclReferenced(Loc, D, true);
     } else if (Arg.getKind() == TemplateArgument::Expression) {
       S.MarkDeclarationsReferencedInExpr(Arg.getAsExpr(), false);
     }
   }
 
   return Inherited::TraverseTemplateArgument(Arg);
 }
 
 void Sema::MarkDeclarationsReferencedInType(SourceLocation Loc, QualType T) {
   MarkReferencedDecls Marker(*this, Loc);
   Marker.TraverseType(T);
 }
 
 namespace {
 /// Helper class that marks all of the declarations referenced by
 /// potentially-evaluated subexpressions as "referenced".
 class EvaluatedExprMarker : public UsedDeclVisitor<EvaluatedExprMarker> {
 public:
   typedef UsedDeclVisitor<EvaluatedExprMarker> Inherited;
   bool SkipLocalVariables;
   ArrayRef<const Expr *> StopAt;
 
   EvaluatedExprMarker(Sema &S, bool SkipLocalVariables,
                       ArrayRef<const Expr *> StopAt)
       : Inherited(S), SkipLocalVariables(SkipLocalVariables), StopAt(StopAt) {}
 
   void visitUsedDecl(SourceLocation Loc, Decl *D) {
     S.MarkFunctionReferenced(Loc, cast<FunctionDecl>(D));
   }
 
   void Visit(Expr *E) {
     if (llvm::is_contained(StopAt, E))
       return;
     Inherited::Visit(E);
   }
 
   void VisitConstantExpr(ConstantExpr *E) {
     // Don't mark declarations within a ConstantExpression, as this expression
     // will be evaluated and folded to a value.
   }
 
   void VisitDeclRefExpr(DeclRefExpr *E) {
     // If we were asked not to visit local variables, don't.
     if (SkipLocalVariables) {
       if (VarDecl *VD = dyn_cast<VarDecl>(E->getDecl()))
         if (VD->hasLocalStorage())
           return;
     }
 
     // FIXME: This can trigger the instantiation of the initializer of a
     // variable, which can cause the expression to become value-dependent
     // or error-dependent. Do we need to propagate the new dependence bits?
     S.MarkDeclRefReferenced(E);
   }
 
   void VisitMemberExpr(MemberExpr *E) {
     S.MarkMemberReferenced(E);
     Visit(E->getBase());
   }
 };
 } // namespace
 
 /// Mark any declarations that appear within this expression or any
 /// potentially-evaluated subexpressions as "referenced".
 ///
 /// \param SkipLocalVariables If true, don't mark local variables as
 /// 'referenced'.
 /// \param StopAt Subexpressions that we shouldn't recurse into.
 void Sema::MarkDeclarationsReferencedInExpr(Expr *E,
                                             bool SkipLocalVariables,
                                             ArrayRef<const Expr*> StopAt) {
   EvaluatedExprMarker(*this, SkipLocalVariables, StopAt).Visit(E);
 }
 
 /// Emit a diagnostic when statements are reachable.
 /// FIXME: check for reachability even in expressions for which we don't build a
 ///        CFG (eg, in the initializer of a global or in a constant expression).
 ///        For example,
 ///        namespace { auto *p = new double[3][false ? (1, 2) : 3]; }
 bool Sema::DiagIfReachable(SourceLocation Loc, ArrayRef<const Stmt *> Stmts,
                            const PartialDiagnostic &PD) {
   if (!Stmts.empty() && getCurFunctionOrMethodDecl()) {
     if (!FunctionScopes.empty())
       FunctionScopes.back()->PossiblyUnreachableDiags.push_back(
           sema::PossiblyUnreachableDiag(PD, Loc, Stmts));
     return true;
   }
 
   // The initializer of a constexpr variable or of the first declaration of a
   // static data member is not syntactically a constant evaluated constant,
   // but nonetheless is always required to be a constant expression, so we
   // can skip diagnosing.
   // FIXME: Using the mangling context here is a hack.
   if (auto *VD = dyn_cast_or_null<VarDecl>(
           ExprEvalContexts.back().ManglingContextDecl)) {
     if (VD->isConstexpr() ||
         (VD->isStaticDataMember() && VD->isFirstDecl() && !VD->isInline()))
       return false;
     // FIXME: For any other kind of variable, we should build a CFG for its
     // initializer and check whether the context in question is reachable.
   }
 
   Diag(Loc, PD);
   return true;
 }
 
 /// Emit a diagnostic that describes an effect on the run-time behavior
 /// of the program being compiled.
 ///
 /// This routine emits the given diagnostic when the code currently being
 /// type-checked is "potentially evaluated", meaning that there is a
 /// possibility that the code will actually be executable. Code in sizeof()
 /// expressions, code used only during overload resolution, etc., are not
 /// potentially evaluated. This routine will suppress such diagnostics or,
 /// in the absolutely nutty case of potentially potentially evaluated
 /// expressions (C++ typeid), queue the diagnostic to potentially emit it
 /// later.
 ///
 /// This routine should be used for all diagnostics that describe the run-time
 /// behavior of a program, such as passing a non-POD value through an ellipsis.
 /// Failure to do so will likely result in spurious diagnostics or failures
 /// during overload resolution or within sizeof/alignof/typeof/typeid.
 bool Sema::DiagRuntimeBehavior(SourceLocation Loc, ArrayRef<const Stmt*> Stmts,
                                const PartialDiagnostic &PD) {
 
   if (ExprEvalContexts.back().isDiscardedStatementContext())
     return false;
 
   switch (ExprEvalContexts.back().Context) {
   case ExpressionEvaluationContext::Unevaluated:
   case ExpressionEvaluationContext::UnevaluatedList:
   case ExpressionEvaluationContext::UnevaluatedAbstract:
   case ExpressionEvaluationContext::DiscardedStatement:
     // The argument will never be evaluated, so don't complain.
     break;
 
   case ExpressionEvaluationContext::ConstantEvaluated:
   case ExpressionEvaluationContext::ImmediateFunctionContext:
     // Relevant diagnostics should be produced by constant evaluation.
     break;
 
   case ExpressionEvaluationContext::PotentiallyEvaluated:
   case ExpressionEvaluationContext::PotentiallyEvaluatedIfUsed:
     return DiagIfReachable(Loc, Stmts, PD);
   }
 
   return false;
 }
 
 bool Sema::DiagRuntimeBehavior(SourceLocation Loc, const Stmt *Statement,
                                const PartialDiagnostic &PD) {
   return DiagRuntimeBehavior(
       Loc, Statement ? llvm::ArrayRef(Statement) : std::nullopt, PD);
 }
 
 bool Sema::CheckCallReturnType(QualType ReturnType, SourceLocation Loc,
                                CallExpr *CE, FunctionDecl *FD) {
   if (ReturnType->isVoidType() || !ReturnType->isIncompleteType())
     return false;
 
   // If we're inside a decltype's expression, don't check for a valid return
   // type or construct temporaries until we know whether this is the last call.
   if (ExprEvalContexts.back().ExprContext ==
       ExpressionEvaluationContextRecord::EK_Decltype) {
     ExprEvalContexts.back().DelayedDecltypeCalls.push_back(CE);
     return false;
   }
 
   class CallReturnIncompleteDiagnoser : public TypeDiagnoser {
     FunctionDecl *FD;
     CallExpr *CE;
 
   public:
     CallReturnIncompleteDiagnoser(FunctionDecl *FD, CallExpr *CE)
       : FD(FD), CE(CE) { }
 
     void diagnose(Sema &S, SourceLocation Loc, QualType T) override {
       if (!FD) {
         S.Diag(Loc, diag::err_call_incomplete_return)
           << T << CE->getSourceRange();
         return;
       }
 
       S.Diag(Loc, diag::err_call_function_incomplete_return)
           << CE->getSourceRange() << FD << T;
       S.Diag(FD->getLocation(), diag::note_entity_declared_at)
           << FD->getDeclName();
     }
   } Diagnoser(FD, CE);
 
   if (RequireCompleteType(Loc, ReturnType, Diagnoser))
     return true;
 
   return false;
 }
 
 // Diagnose the s/=/==/ and s/\|=/!=/ typos. Note that adding parentheses
 // will prevent this condition from triggering, which is what we want.
 void Sema::DiagnoseAssignmentAsCondition(Expr *E) {
   SourceLocation Loc;
 
   unsigned diagnostic = diag::warn_condition_is_assignment;
   bool IsOrAssign = false;
 
   if (BinaryOperator *Op = dyn_cast<BinaryOperator>(E)) {
     if (Op->getOpcode() != BO_Assign && Op->getOpcode() != BO_OrAssign)
       return;
 
     IsOrAssign = Op->getOpcode() == BO_OrAssign;
 
     // Greylist some idioms by putting them into a warning subcategory.
     if (ObjCMessageExpr *ME
           = dyn_cast<ObjCMessageExpr>(Op->getRHS()->IgnoreParenCasts())) {
       Selector Sel = ME->getSelector();
 
       // self = [<foo> init...]
       if (isSelfExpr(Op->getLHS()) && ME->getMethodFamily() == OMF_init)
         diagnostic = diag::warn_condition_is_idiomatic_assignment;
 
       // <foo> = [<bar> nextObject]
       else if (Sel.isUnarySelector() && Sel.getNameForSlot(0) == "nextObject")
         diagnostic = diag::warn_condition_is_idiomatic_assignment;
     }
 
     Loc = Op->getOperatorLoc();
   } else if (CXXOperatorCallExpr *Op = dyn_cast<CXXOperatorCallExpr>(E)) {
     if (Op->getOperator() != OO_Equal && Op->getOperator() != OO_PipeEqual)
       return;
 
     IsOrAssign = Op->getOperator() == OO_PipeEqual;
     Loc = Op->getOperatorLoc();
   } else if (PseudoObjectExpr *POE = dyn_cast<PseudoObjectExpr>(E))
     return DiagnoseAssignmentAsCondition(POE->getSyntacticForm());
   else {
     // Not an assignment.
     return;
   }
 
   Diag(Loc, diagnostic) << E->getSourceRange();
 
   SourceLocation Open = E->getBeginLoc();
   SourceLocation Close = getLocForEndOfToken(E->getSourceRange().getEnd());
   Diag(Loc, diag::note_condition_assign_silence)
         << FixItHint::CreateInsertion(Open, "(")
         << FixItHint::CreateInsertion(Close, ")");
 
   if (IsOrAssign)
     Diag(Loc, diag::note_condition_or_assign_to_comparison)
       << FixItHint::CreateReplacement(Loc, "!=");
   else
     Diag(Loc, diag::note_condition_assign_to_comparison)
       << FixItHint::CreateReplacement(Loc, "==");
 }
 
 /// Redundant parentheses over an equality comparison can indicate
 /// that the user intended an assignment used as condition.
 void Sema::DiagnoseEqualityWithExtraParens(ParenExpr *ParenE) {
   // Don't warn if the parens came from a macro.
   SourceLocation parenLoc = ParenE->getBeginLoc();
   if (parenLoc.isInvalid() || parenLoc.isMacroID())
     return;
   // Don't warn for dependent expressions.
   if (ParenE->isTypeDependent())
     return;
 
   Expr *E = ParenE->IgnoreParens();
 
   if (BinaryOperator *opE = dyn_cast<BinaryOperator>(E))
     if (opE->getOpcode() == BO_EQ &&
         opE->getLHS()->IgnoreParenImpCasts()->isModifiableLvalue(Context)
                                                            == Expr::MLV_Valid) {
       SourceLocation Loc = opE->getOperatorLoc();
 
       Diag(Loc, diag::warn_equality_with_extra_parens) << E->getSourceRange();
       SourceRange ParenERange = ParenE->getSourceRange();
       Diag(Loc, diag::note_equality_comparison_silence)
         << FixItHint::CreateRemoval(ParenERange.getBegin())
         << FixItHint::CreateRemoval(ParenERange.getEnd());
       Diag(Loc, diag::note_equality_comparison_to_assign)
         << FixItHint::CreateReplacement(Loc, "=");
     }
 }
 
 ExprResult Sema::CheckBooleanCondition(SourceLocation Loc, Expr *E,
                                        bool IsConstexpr) {
   DiagnoseAssignmentAsCondition(E);
   if (ParenExpr *parenE = dyn_cast<ParenExpr>(E))
     DiagnoseEqualityWithExtraParens(parenE);
 
   ExprResult result = CheckPlaceholderExpr(E);
   if (result.isInvalid()) return ExprError();
   E = result.get();
 
   if (!E->isTypeDependent()) {
     if (getLangOpts().CPlusPlus)
       return CheckCXXBooleanCondition(E, IsConstexpr); // C++ 6.4p4
 
     ExprResult ERes = DefaultFunctionArrayLvalueConversion(E);
     if (ERes.isInvalid())
       return ExprError();
     E = ERes.get();
 
     QualType T = E->getType();
     if (!T->isScalarType()) { // C99 6.8.4.1p1
       Diag(Loc, diag::err_typecheck_statement_requires_scalar)
         << T << E->getSourceRange();
       return ExprError();
     }
     CheckBoolLikeConversion(E, Loc);
   }
 
   return E;
 }
 
 Sema::ConditionResult Sema::ActOnCondition(Scope *S, SourceLocation Loc,
                                            Expr *SubExpr, ConditionKind CK,
                                            bool MissingOK) {
   // MissingOK indicates whether having no condition expression is valid
   // (for loop) or invalid (e.g. while loop).
   if (!SubExpr)
     return MissingOK ? ConditionResult() : ConditionError();
 
   ExprResult Cond;
   switch (CK) {
   case ConditionKind::Boolean:
     Cond = CheckBooleanCondition(Loc, SubExpr);
     break;
 
   case ConditionKind::ConstexprIf:
     Cond = CheckBooleanCondition(Loc, SubExpr, true);
     break;
 
   case ConditionKind::Switch:
     Cond = CheckSwitchCondition(Loc, SubExpr);
     break;
   }
   if (Cond.isInvalid()) {
     Cond = CreateRecoveryExpr(SubExpr->getBeginLoc(), SubExpr->getEndLoc(),
                               {SubExpr}, PreferredConditionType(CK));
     if (!Cond.get())
       return ConditionError();
   }
   // FIXME: FullExprArg doesn't have an invalid bit, so check nullness instead.
   FullExprArg FullExpr = MakeFullExpr(Cond.get(), Loc);
   if (!FullExpr.get())
     return ConditionError();
 
   return ConditionResult(*this, nullptr, FullExpr,
                          CK == ConditionKind::ConstexprIf);
 }
 
 namespace {
   /// A visitor for rebuilding a call to an __unknown_any expression
   /// to have an appropriate type.
   struct RebuildUnknownAnyFunction
     : StmtVisitor<RebuildUnknownAnyFunction, ExprResult> {
 
     Sema &S;
 
     RebuildUnknownAnyFunction(Sema &S) : S(S) {}
 
     ExprResult VisitStmt(Stmt *S) {
       llvm_unreachable("unexpected statement!");
     }
 
     ExprResult VisitExpr(Expr *E) {
       S.Diag(E->getExprLoc(), diag::err_unsupported_unknown_any_call)
         << E->getSourceRange();
       return ExprError();
     }
 
     /// Rebuild an expression which simply semantically wraps another
     /// expression which it shares the type and value kind of.
     template <class T> ExprResult rebuildSugarExpr(T *E) {
       ExprResult SubResult = Visit(E->getSubExpr());
       if (SubResult.isInvalid()) return ExprError();
 
       Expr *SubExpr = SubResult.get();
       E->setSubExpr(SubExpr);
       E->setType(SubExpr->getType());
       E->setValueKind(SubExpr->getValueKind());
       assert(E->getObjectKind() == OK_Ordinary);
       return E;
     }
 
     ExprResult VisitParenExpr(ParenExpr *E) {
       return rebuildSugarExpr(E);
     }
 
     ExprResult VisitUnaryExtension(UnaryOperator *E) {
       return rebuildSugarExpr(E);
     }
 
     ExprResult VisitUnaryAddrOf(UnaryOperator *E) {
       ExprResult SubResult = Visit(E->getSubExpr());
       if (SubResult.isInvalid()) return ExprError();
 
       Expr *SubExpr = SubResult.get();
       E->setSubExpr(SubExpr);
       E->setType(S.Context.getPointerType(SubExpr->getType()));
       assert(E->isPRValue());
       assert(E->getObjectKind() == OK_Ordinary);
       return E;
     }
 
     ExprResult resolveDecl(Expr *E, ValueDecl *VD) {
       if (!isa<FunctionDecl>(VD)) return VisitExpr(E);
 
       E->setType(VD->getType());
 
       assert(E->isPRValue());
       if (S.getLangOpts().CPlusPlus &&
           !(isa<CXXMethodDecl>(VD) &&
             cast<CXXMethodDecl>(VD)->isInstance()))
         E->setValueKind(VK_LValue);
 
       return E;
     }
 
     ExprResult VisitMemberExpr(MemberExpr *E) {
       return resolveDecl(E, E->getMemberDecl());
     }
 
     ExprResult VisitDeclRefExpr(DeclRefExpr *E) {
       return resolveDecl(E, E->getDecl());
     }
   };
 }
 
 /// Given a function expression of unknown-any type, try to rebuild it
 /// to have a function type.
 static ExprResult rebuildUnknownAnyFunction(Sema &S, Expr *FunctionExpr) {
   ExprResult Result = RebuildUnknownAnyFunction(S).Visit(FunctionExpr);
   if (Result.isInvalid()) return ExprError();
   return S.DefaultFunctionArrayConversion(Result.get());
 }
 
 namespace {
   /// A visitor for rebuilding an expression of type __unknown_anytype
   /// into one which resolves the type directly on the referring
   /// expression.  Strict preservation of the original source
   /// structure is not a goal.
   struct RebuildUnknownAnyExpr
     : StmtVisitor<RebuildUnknownAnyExpr, ExprResult> {
 
     Sema &S;
 
     /// The current destination type.
     QualType DestType;
 
     RebuildUnknownAnyExpr(Sema &S, QualType CastType)
       : S(S), DestType(CastType) {}
 
     ExprResult VisitStmt(Stmt *S) {
       llvm_unreachable("unexpected statement!");
     }
 
     ExprResult VisitExpr(Expr *E) {
       S.Diag(E->getExprLoc(), diag::err_unsupported_unknown_any_expr)
         << E->getSourceRange();
       return ExprError();
     }
 
     ExprResult VisitCallExpr(CallExpr *E);
     ExprResult VisitObjCMessageExpr(ObjCMessageExpr *E);
 
     /// Rebuild an expression which simply semantically wraps another
     /// expression which it shares the type and value kind of.
     template <class T> ExprResult rebuildSugarExpr(T *E) {
       ExprResult SubResult = Visit(E->getSubExpr());
       if (SubResult.isInvalid()) return ExprError();
       Expr *SubExpr = SubResult.get();
       E->setSubExpr(SubExpr);
       E->setType(SubExpr->getType());
       E->setValueKind(SubExpr->getValueKind());
       assert(E->getObjectKind() == OK_Ordinary);
       return E;
     }
 
     ExprResult VisitParenExpr(ParenExpr *E) {
       return rebuildSugarExpr(E);
     }
 
     ExprResult VisitUnaryExtension(UnaryOperator *E) {
       return rebuildSugarExpr(E);
     }
 
     ExprResult VisitUnaryAddrOf(UnaryOperator *E) {
       const PointerType *Ptr = DestType->getAs<PointerType>();
       if (!Ptr) {
         S.Diag(E->getOperatorLoc(), diag::err_unknown_any_addrof)
           << E->getSourceRange();
         return ExprError();
       }
 
       if (isa<CallExpr>(E->getSubExpr())) {
         S.Diag(E->getOperatorLoc(), diag::err_unknown_any_addrof_call)
           << E->getSourceRange();
         return ExprError();
       }
 
       assert(E->isPRValue());
       assert(E->getObjectKind() == OK_Ordinary);
       E->setType(DestType);
 
       // Build the sub-expression as if it were an object of the pointee type.
       DestType = Ptr->getPointeeType();
       ExprResult SubResult = Visit(E->getSubExpr());
       if (SubResult.isInvalid()) return ExprError();
       E->setSubExpr(SubResult.get());
       return E;
     }
 
     ExprResult VisitImplicitCastExpr(ImplicitCastExpr *E);
 
     ExprResult resolveDecl(Expr *E, ValueDecl *VD);
 
     ExprResult VisitMemberExpr(MemberExpr *E) {
       return resolveDecl(E, E->getMemberDecl());
     }
 
     ExprResult VisitDeclRefExpr(DeclRefExpr *E) {
       return resolveDecl(E, E->getDecl());
     }
   };
 }
 
 /// Rebuilds a call expression which yielded __unknown_anytype.
 ExprResult RebuildUnknownAnyExpr::VisitCallExpr(CallExpr *E) {
   Expr *CalleeExpr = E->getCallee();
 
   enum FnKind {
     FK_MemberFunction,
     FK_FunctionPointer,
     FK_BlockPointer
   };
 
   FnKind Kind;
   QualType CalleeType = CalleeExpr->getType();
   if (CalleeType == S.Context.BoundMemberTy) {
     assert(isa<CXXMemberCallExpr>(E) || isa<CXXOperatorCallExpr>(E));
     Kind = FK_MemberFunction;
     CalleeType = Expr::findBoundMemberType(CalleeExpr);
   } else if (const PointerType *Ptr = CalleeType->getAs<PointerType>()) {
     CalleeType = Ptr->getPointeeType();
     Kind = FK_FunctionPointer;
   } else {
     CalleeType = CalleeType->castAs<BlockPointerType>()->getPointeeType();
     Kind = FK_BlockPointer;
   }
   const FunctionType *FnType = CalleeType->castAs<FunctionType>();
 
   // Verify that this is a legal result type of a function.
   if (DestType->isArrayType() || DestType->isFunctionType()) {
     unsigned diagID = diag::err_func_returning_array_function;
     if (Kind == FK_BlockPointer)
       diagID = diag::err_block_returning_array_function;
 
     S.Diag(E->getExprLoc(), diagID)
       << DestType->isFunctionType() << DestType;
     return ExprError();
   }
 
   // Otherwise, go ahead and set DestType as the call's result.
   E->setType(DestType.getNonLValueExprType(S.Context));
   E->setValueKind(Expr::getValueKindForType(DestType));
   assert(E->getObjectKind() == OK_Ordinary);
 
   // Rebuild the function type, replacing the result type with DestType.
   const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FnType);
   if (Proto) {
     // __unknown_anytype(...) is a special case used by the debugger when
     // it has no idea what a function's signature is.
     //
     // We want to build this call essentially under the K&R
     // unprototyped rules, but making a FunctionNoProtoType in C++
     // would foul up all sorts of assumptions.  However, we cannot
     // simply pass all arguments as variadic arguments, nor can we
     // portably just call the function under a non-variadic type; see
     // the comment on IR-gen's TargetInfo::isNoProtoCallVariadic.
     // However, it turns out that in practice it is generally safe to
     // call a function declared as "A foo(B,C,D);" under the prototype
     // "A foo(B,C,D,...);".  The only known exception is with the
     // Windows ABI, where any variadic function is implicitly cdecl
     // regardless of its normal CC.  Therefore we change the parameter
     // types to match the types of the arguments.
     //
     // This is a hack, but it is far superior to moving the
     // corresponding target-specific code from IR-gen to Sema/AST.
 
     ArrayRef<QualType> ParamTypes = Proto->getParamTypes();
     SmallVector<QualType, 8> ArgTypes;
     if (ParamTypes.empty() && Proto->isVariadic()) { // the special case
       ArgTypes.reserve(E->getNumArgs());
       for (unsigned i = 0, e = E->getNumArgs(); i != e; ++i) {
         ArgTypes.push_back(S.Context.getReferenceQualifiedType(E->getArg(i)));
       }
       ParamTypes = ArgTypes;
     }
     DestType = S.Context.getFunctionType(DestType, ParamTypes,
                                          Proto->getExtProtoInfo());
   } else {
     DestType = S.Context.getFunctionNoProtoType(DestType,
                                                 FnType->getExtInfo());
   }
 
   // Rebuild the appropriate pointer-to-function type.
   switch (Kind) {
   case FK_MemberFunction:
     // Nothing to do.
     break;
 
   case FK_FunctionPointer:
     DestType = S.Context.getPointerType(DestType);
     break;
 
   case FK_BlockPointer:
     DestType = S.Context.getBlockPointerType(DestType);
     break;
   }
 
   // Finally, we can recurse.
   ExprResult CalleeResult = Visit(CalleeExpr);
   if (!CalleeResult.isUsable()) return ExprError();
   E->setCallee(CalleeResult.get());
 
   // Bind a temporary if necessary.
   return S.MaybeBindToTemporary(E);
 }
 
 ExprResult RebuildUnknownAnyExpr::VisitObjCMessageExpr(ObjCMessageExpr *E) {
   // Verify that this is a legal result type of a call.
   if (DestType->isArrayType() || DestType->isFunctionType()) {
     S.Diag(E->getExprLoc(), diag::err_func_returning_array_function)
       << DestType->isFunctionType() << DestType;
     return ExprError();
   }
 
   // Rewrite the method result type if available.
   if (ObjCMethodDecl *Method = E->getMethodDecl()) {
     assert(Method->getReturnType() == S.Context.UnknownAnyTy);
     Method->setReturnType(DestType);
   }
 
   // Change the type of the message.
   E->setType(DestType.getNonReferenceType());
   E->setValueKind(Expr::getValueKindForType(DestType));
 
   return S.MaybeBindToTemporary(E);
 }
 
 ExprResult RebuildUnknownAnyExpr::VisitImplicitCastExpr(ImplicitCastExpr *E) {
   // The only case we should ever see here is a function-to-pointer decay.
   if (E->getCastKind() == CK_FunctionToPointerDecay) {
     assert(E->isPRValue());
     assert(E->getObjectKind() == OK_Ordinary);
 
     E->setType(DestType);
 
     // Rebuild the sub-expression as the pointee (function) type.
     DestType = DestType->castAs<PointerType>()->getPointeeType();
 
     ExprResult Result = Visit(E->getSubExpr());
     if (!Result.isUsable()) return ExprError();
 
     E->setSubExpr(Result.get());
     return E;
   } else if (E->getCastKind() == CK_LValueToRValue) {
     assert(E->isPRValue());
     assert(E->getObjectKind() == OK_Ordinary);
 
     assert(isa<BlockPointerType>(E->getType()));
 
     E->setType(DestType);
 
     // The sub-expression has to be a lvalue reference, so rebuild it as such.
     DestType = S.Context.getLValueReferenceType(DestType);
 
     ExprResult Result = Visit(E->getSubExpr());
     if (!Result.isUsable()) return ExprError();
 
     E->setSubExpr(Result.get());
     return E;
   } else {
     llvm_unreachable("Unhandled cast type!");
   }
 }
 
 ExprResult RebuildUnknownAnyExpr::resolveDecl(Expr *E, ValueDecl *VD) {
   ExprValueKind ValueKind = VK_LValue;
   QualType Type = DestType;
 
   // We know how to make this work for certain kinds of decls:
 
   //  - functions
   if (FunctionDecl *FD = dyn_cast<FunctionDecl>(VD)) {
     if (const PointerType *Ptr = Type->getAs<PointerType>()) {
       DestType = Ptr->getPointeeType();
       ExprResult Result = resolveDecl(E, VD);
       if (Result.isInvalid()) return ExprError();
       return S.ImpCastExprToType(Result.get(), Type, CK_FunctionToPointerDecay,
                                  VK_PRValue);
     }
 
     if (!Type->isFunctionType()) {
       S.Diag(E->getExprLoc(), diag::err_unknown_any_function)
         << VD << E->getSourceRange();
       return ExprError();
     }
     if (const FunctionProtoType *FT = Type->getAs<FunctionProtoType>()) {
       // We must match the FunctionDecl's type to the hack introduced in
       // RebuildUnknownAnyExpr::VisitCallExpr to vararg functions of unknown
       // type. See the lengthy commentary in that routine.
       QualType FDT = FD->getType();
       const FunctionType *FnType = FDT->castAs<FunctionType>();
       const FunctionProtoType *Proto = dyn_cast_or_null<FunctionProtoType>(FnType);
       DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E);
       if (DRE && Proto && Proto->getParamTypes().empty() && Proto->isVariadic()) {
         SourceLocation Loc = FD->getLocation();
         FunctionDecl *NewFD = FunctionDecl::Create(
             S.Context, FD->getDeclContext(), Loc, Loc,
             FD->getNameInfo().getName(), DestType, FD->getTypeSourceInfo(),
             SC_None, S.getCurFPFeatures().isFPConstrained(),
             false /*isInlineSpecified*/, FD->hasPrototype(),
             /*ConstexprKind*/ ConstexprSpecKind::Unspecified);
 
         if (FD->getQualifier())
           NewFD->setQualifierInfo(FD->getQualifierLoc());
 
         SmallVector<ParmVarDecl*, 16> Params;
         for (const auto &AI : FT->param_types()) {
           ParmVarDecl *Param =
             S.BuildParmVarDeclForTypedef(FD, Loc, AI);
           Param->setScopeInfo(0, Params.size());
           Params.push_back(Param);
         }
         NewFD->setParams(Params);
         DRE->setDecl(NewFD);
         VD = DRE->getDecl();
       }
     }
 
     if (CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD))
       if (MD->isInstance()) {
         ValueKind = VK_PRValue;
         Type = S.Context.BoundMemberTy;
       }
 
     // Function references aren't l-values in C.
     if (!S.getLangOpts().CPlusPlus)
       ValueKind = VK_PRValue;
 
   //  - variables
   } else if (isa<VarDecl>(VD)) {
     if (const ReferenceType *RefTy = Type->getAs<ReferenceType>()) {
       Type = RefTy->getPointeeType();
     } else if (Type->isFunctionType()) {
       S.Diag(E->getExprLoc(), diag::err_unknown_any_var_function_type)
         << VD << E->getSourceRange();
       return ExprError();
     }
 
   //  - nothing else
   } else {
     S.Diag(E->getExprLoc(), diag::err_unsupported_unknown_any_decl)
       << VD << E->getSourceRange();
     return ExprError();
   }
 
   // Modifying the declaration like this is friendly to IR-gen but
   // also really dangerous.
   VD->setType(DestType);
   E->setType(Type);
   E->setValueKind(ValueKind);
   return E;
 }
 
 /// Check a cast of an unknown-any type.  We intentionally only
 /// trigger this for C-style casts.
 ExprResult Sema::checkUnknownAnyCast(SourceRange TypeRange, QualType CastType,
                                      Expr *CastExpr, CastKind &CastKind,
                                      ExprValueKind &VK, CXXCastPath &Path) {
   // The type we're casting to must be either void or complete.
   if (!CastType->isVoidType() &&
       RequireCompleteType(TypeRange.getBegin(), CastType,
                           diag::err_typecheck_cast_to_incomplete))
     return ExprError();
 
   // Rewrite the casted expression from scratch.
   ExprResult result = RebuildUnknownAnyExpr(*this, CastType).Visit(CastExpr);
   if (!result.isUsable()) return ExprError();
 
   CastExpr = result.get();
   VK = CastExpr->getValueKind();
   CastKind = CK_NoOp;
 
   return CastExpr;
 }
 
 ExprResult Sema::forceUnknownAnyToType(Expr *E, QualType ToType) {
   return RebuildUnknownAnyExpr(*this, ToType).Visit(E);
 }
 
 ExprResult Sema::checkUnknownAnyArg(SourceLocation callLoc,
                                     Expr *arg, QualType &paramType) {
   // If the syntactic form of the argument is not an explicit cast of
   // any sort, just do default argument promotion.
   ExplicitCastExpr *castArg = dyn_cast<ExplicitCastExpr>(arg->IgnoreParens());
   if (!castArg) {
     ExprResult result = DefaultArgumentPromotion(arg);
     if (result.isInvalid()) return ExprError();
     paramType = result.get()->getType();
     return result;
   }
 
   // Otherwise, use the type that was written in the explicit cast.
   assert(!arg->hasPlaceholderType());
   paramType = castArg->getTypeAsWritten();
 
   // Copy-initialize a parameter of that type.
   InitializedEntity entity =
     InitializedEntity::InitializeParameter(Context, paramType,
                                            /*consumed*/ false);
   return PerformCopyInitialization(entity, callLoc, arg);
 }
 
 static ExprResult diagnoseUnknownAnyExpr(Sema &S, Expr *E) {
   Expr *orig = E;
   unsigned diagID = diag::err_uncasted_use_of_unknown_any;
   while (true) {
     E = E->IgnoreParenImpCasts();
     if (CallExpr *call = dyn_cast<CallExpr>(E)) {
       E = call->getCallee();
       diagID = diag::err_uncasted_call_of_unknown_any;
     } else {
       break;
     }
   }
 
   SourceLocation loc;
   NamedDecl *d;
   if (DeclRefExpr *ref = dyn_cast<DeclRefExpr>(E)) {
     loc = ref->getLocation();
     d = ref->getDecl();
   } else if (MemberExpr *mem = dyn_cast<MemberExpr>(E)) {
     loc = mem->getMemberLoc();
     d = mem->getMemberDecl();
   } else if (ObjCMessageExpr *msg = dyn_cast<ObjCMessageExpr>(E)) {
     diagID = diag::err_uncasted_call_of_unknown_any;
     loc = msg->getSelectorStartLoc();
     d = msg->getMethodDecl();
     if (!d) {
       S.Diag(loc, diag::err_uncasted_send_to_unknown_any_method)
         << static_cast<unsigned>(msg->isClassMessage()) << msg->getSelector()
         << orig->getSourceRange();
       return ExprError();
     }
   } else {
     S.Diag(E->getExprLoc(), diag::err_unsupported_unknown_any_expr)
       << E->getSourceRange();
     return ExprError();
   }
 
   S.Diag(loc, diagID) << d << orig->getSourceRange();
 
   // Never recoverable.
   return ExprError();
 }
 
 /// Check for operands with placeholder types and complain if found.
 /// Returns ExprError() if there was an error and no recovery was possible.
 ExprResult Sema::CheckPlaceholderExpr(Expr *E) {
   if (!Context.isDependenceAllowed()) {
     // C cannot handle TypoExpr nodes on either side of a binop because it
     // doesn't handle dependent types properly, so make sure any TypoExprs have
     // been dealt with before checking the operands.
     ExprResult Result = CorrectDelayedTyposInExpr(E);
     if (!Result.isUsable()) return ExprError();
     E = Result.get();
   }
 
   const BuiltinType *placeholderType = E->getType()->getAsPlaceholderType();
   if (!placeholderType) return E;
 
   switch (placeholderType->getKind()) {
 
   // Overloaded expressions.
   case BuiltinType::Overload: {
     // Try to resolve a single function template specialization.
     // This is obligatory.
     ExprResult Result = E;
     if (ResolveAndFixSingleFunctionTemplateSpecialization(Result, false))
       return Result;
 
     // No guarantees that ResolveAndFixSingleFunctionTemplateSpecialization
     // leaves Result unchanged on failure.
     Result = E;
     if (resolveAndFixAddressOfSingleOverloadCandidate(Result))
       return Result;
 
     // If that failed, try to recover with a call.
     tryToRecoverWithCall(Result, PDiag(diag::err_ovl_unresolvable),
                          /*complain*/ true);
     return Result;
   }
 
   // Bound member functions.
   case BuiltinType::BoundMember: {
     ExprResult result = E;
     const Expr *BME = E->IgnoreParens();
     PartialDiagnostic PD = PDiag(diag::err_bound_member_function);
     // Try to give a nicer diagnostic if it is a bound member that we recognize.
     if (isa<CXXPseudoDestructorExpr>(BME)) {
       PD = PDiag(diag::err_dtor_expr_without_call) << /*pseudo-destructor*/ 1;
     } else if (const auto *ME = dyn_cast<MemberExpr>(BME)) {
       if (ME->getMemberNameInfo().getName().getNameKind() ==
           DeclarationName::CXXDestructorName)
         PD = PDiag(diag::err_dtor_expr_without_call) << /*destructor*/ 0;
     }
     tryToRecoverWithCall(result, PD,
                          /*complain*/ true);
     return result;
   }
 
   // ARC unbridged casts.
   case BuiltinType::ARCUnbridgedCast: {
     Expr *realCast = stripARCUnbridgedCast(E);
     diagnoseARCUnbridgedCast(realCast);
     return realCast;
   }
 
   // Expressions of unknown type.
   case BuiltinType::UnknownAny:
     return diagnoseUnknownAnyExpr(*this, E);
 
   // Pseudo-objects.
   case BuiltinType::PseudoObject:
     return checkPseudoObjectRValue(E);
 
   case BuiltinType::BuiltinFn: {
     // Accept __noop without parens by implicitly converting it to a call expr.
     auto *DRE = dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts());
     if (DRE) {
       auto *FD = cast<FunctionDecl>(DRE->getDecl());
       unsigned BuiltinID = FD->getBuiltinID();
       if (BuiltinID == Builtin::BI__noop) {
         E = ImpCastExprToType(E, Context.getPointerType(FD->getType()),
                               CK_BuiltinFnToFnPtr)
                 .get();
         return CallExpr::Create(Context, E, /*Args=*/{}, Context.IntTy,
                                 VK_PRValue, SourceLocation(),
                                 FPOptionsOverride());
       }
 
       if (Context.BuiltinInfo.isInStdNamespace(BuiltinID)) {
         // Any use of these other than a direct call is ill-formed as of C++20,
         // because they are not addressable functions. In earlier language
         // modes, warn and force an instantiation of the real body.
         Diag(E->getBeginLoc(),
              getLangOpts().CPlusPlus20
                  ? diag::err_use_of_unaddressable_function
                  : diag::warn_cxx20_compat_use_of_unaddressable_function);
         if (FD->isImplicitlyInstantiable()) {
           // Require a definition here because a normal attempt at
           // instantiation for a builtin will be ignored, and we won't try
           // again later. We assume that the definition of the template
           // precedes this use.
           InstantiateFunctionDefinition(E->getBeginLoc(), FD,
                                         /*Recursive=*/false,
                                         /*DefinitionRequired=*/true,
                                         /*AtEndOfTU=*/false);
         }
         // Produce a properly-typed reference to the function.
         CXXScopeSpec SS;
         SS.Adopt(DRE->getQualifierLoc());
         TemplateArgumentListInfo TemplateArgs;
         DRE->copyTemplateArgumentsInto(TemplateArgs);
         return BuildDeclRefExpr(
             FD, FD->getType(), VK_LValue, DRE->getNameInfo(),
             DRE->hasQualifier() ? &SS : nullptr, DRE->getFoundDecl(),
             DRE->getTemplateKeywordLoc(),
             DRE->hasExplicitTemplateArgs() ? &TemplateArgs : nullptr);
       }
     }
 
     Diag(E->getBeginLoc(), diag::err_builtin_fn_use);
     return ExprError();
   }
 
   case BuiltinType::IncompleteMatrixIdx:
     Diag(cast<MatrixSubscriptExpr>(E->IgnoreParens())
              ->getRowIdx()
              ->getBeginLoc(),
          diag::err_matrix_incomplete_index);
     return ExprError();
 
   // Expressions of unknown type.
   case BuiltinType::OMPArraySection:
     Diag(E->getBeginLoc(), diag::err_omp_array_section_use);
     return ExprError();
 
   // Expressions of unknown type.
   case BuiltinType::OMPArrayShaping:
     return ExprError(Diag(E->getBeginLoc(), diag::err_omp_array_shaping_use));
 
   case BuiltinType::OMPIterator:
     return ExprError(Diag(E->getBeginLoc(), diag::err_omp_iterator_use));
 
   // Everything else should be impossible.
 #define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \
   case BuiltinType::Id:
 #include "clang/Basic/OpenCLImageTypes.def"
 #define EXT_OPAQUE_TYPE(ExtType, Id, Ext) \
   case BuiltinType::Id:
 #include "clang/Basic/OpenCLExtensionTypes.def"
 #define SVE_TYPE(Name, Id, SingletonId) \
   case BuiltinType::Id:
 #include "clang/Basic/AArch64SVEACLETypes.def"
 #define PPC_VECTOR_TYPE(Name, Id, Size) \
   case BuiltinType::Id:
 #include "clang/Basic/PPCTypes.def"
 #define RVV_TYPE(Name, Id, SingletonId) case BuiltinType::Id:
 #include "clang/Basic/RISCVVTypes.def"
 #define WASM_TYPE(Name, Id, SingletonId) case BuiltinType::Id:
 #include "clang/Basic/WebAssemblyReferenceTypes.def"
 #define BUILTIN_TYPE(Id, SingletonId) case BuiltinType::Id:
 #define PLACEHOLDER_TYPE(Id, SingletonId)
 #include "clang/AST/BuiltinTypes.def"
     break;
   }
 
   llvm_unreachable("invalid placeholder type!");
 }
 
 bool Sema::CheckCaseExpression(Expr *E) {
   if (E->isTypeDependent())
     return true;
   if (E->isValueDependent() || E->isIntegerConstantExpr(Context))
     return E->getType()->isIntegralOrEnumerationType();
   return false;
 }
 
 /// ActOnObjCBoolLiteral - Parse {__objc_yes,__objc_no} literals.
 ExprResult
 Sema::ActOnObjCBoolLiteral(SourceLocation OpLoc, tok::TokenKind Kind) {
   assert((Kind == tok::kw___objc_yes || Kind == tok::kw___objc_no) &&
          "Unknown Objective-C Boolean value!");
   QualType BoolT = Context.ObjCBuiltinBoolTy;
   if (!Context.getBOOLDecl()) {
     LookupResult Result(*this, &Context.Idents.get("BOOL"), OpLoc,
                         Sema::LookupOrdinaryName);
     if (LookupName(Result, getCurScope()) && Result.isSingleResult()) {
       NamedDecl *ND = Result.getFoundDecl();
       if (TypedefDecl *TD = dyn_cast<TypedefDecl>(ND))
         Context.setBOOLDecl(TD);
     }
   }
   if (Context.getBOOLDecl())
     BoolT = Context.getBOOLType();
   return new (Context)
       ObjCBoolLiteralExpr(Kind == tok::kw___objc_yes, BoolT, OpLoc);
 }
 
 ExprResult Sema::ActOnObjCAvailabilityCheckExpr(
     llvm::ArrayRef<AvailabilitySpec> AvailSpecs, SourceLocation AtLoc,
     SourceLocation RParen) {
   auto FindSpecVersion =
       [&](StringRef Platform) -> std::optional<VersionTuple> {
     auto Spec = llvm::find_if(AvailSpecs, [&](const AvailabilitySpec &Spec) {
       return Spec.getPlatform() == Platform;
     });
     // Transcribe the "ios" availability check to "maccatalyst" when compiling
     // for "maccatalyst" if "maccatalyst" is not specified.
     if (Spec == AvailSpecs.end() && Platform == "maccatalyst") {
       Spec = llvm::find_if(AvailSpecs, [&](const AvailabilitySpec &Spec) {
         return Spec.getPlatform() == "ios";
       });
     }
     if (Spec == AvailSpecs.end())
       return std::nullopt;
     return Spec->getVersion();
   };
 
   VersionTuple Version;
   if (auto MaybeVersion =
           FindSpecVersion(Context.getTargetInfo().getPlatformName()))
     Version = *MaybeVersion;
 
   // The use of `@available` in the enclosing context should be analyzed to
   // warn when it's used inappropriately (i.e. not if(@available)).
   if (FunctionScopeInfo *Context = getCurFunctionAvailabilityContext())
     Context->HasPotentialAvailabilityViolations = true;
 
   return new (Context)
       ObjCAvailabilityCheckExpr(Version, AtLoc, RParen, Context.BoolTy);
 }
 
 ExprResult Sema::CreateRecoveryExpr(SourceLocation Begin, SourceLocation End,
                                     ArrayRef<Expr *> SubExprs, QualType T) {
   if (!Context.getLangOpts().RecoveryAST)
     return ExprError();
 
   if (isSFINAEContext())
     return ExprError();
 
   if (T.isNull() || T->isUndeducedType() ||
       !Context.getLangOpts().RecoveryASTType)
     // We don't know the concrete type, fallback to dependent type.
     T = Context.DependentTy;
 
   return RecoveryExpr::Create(Context, T, Begin, End, SubExprs);
 }
diff --git a/contrib/llvm-project/clang/lib/Sema/SemaLambda.cpp b/contrib/llvm-project/clang/lib/Sema/SemaLambda.cpp
index 06fc53591a76..ccc5111d1e31 100644
--- a/contrib/llvm-project/clang/lib/Sema/SemaLambda.cpp
+++ b/contrib/llvm-project/clang/lib/Sema/SemaLambda.cpp
@@ -1,2224 +1,2256 @@
 //===--- SemaLambda.cpp - Semantic Analysis for C++11 Lambdas -------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 //  This file implements semantic analysis for C++ lambda expressions.
 //
 //===----------------------------------------------------------------------===//
 #include "clang/Sema/DeclSpec.h"
 #include "TypeLocBuilder.h"
 #include "clang/AST/ASTLambda.h"
 #include "clang/AST/ExprCXX.h"
 #include "clang/Basic/TargetInfo.h"
 #include "clang/Sema/Initialization.h"
 #include "clang/Sema/Lookup.h"
 #include "clang/Sema/Scope.h"
 #include "clang/Sema/ScopeInfo.h"
 #include "clang/Sema/SemaInternal.h"
 #include "clang/Sema/SemaLambda.h"
+#include "clang/Sema/Template.h"
 #include "llvm/ADT/STLExtras.h"
 #include <optional>
 using namespace clang;
 using namespace sema;
 
 /// Examines the FunctionScopeInfo stack to determine the nearest
 /// enclosing lambda (to the current lambda) that is 'capture-ready' for
 /// the variable referenced in the current lambda (i.e. \p VarToCapture).
 /// If successful, returns the index into Sema's FunctionScopeInfo stack
 /// of the capture-ready lambda's LambdaScopeInfo.
 ///
 /// Climbs down the stack of lambdas (deepest nested lambda - i.e. current
 /// lambda - is on top) to determine the index of the nearest enclosing/outer
 /// lambda that is ready to capture the \p VarToCapture being referenced in
 /// the current lambda.
 /// As we climb down the stack, we want the index of the first such lambda -
 /// that is the lambda with the highest index that is 'capture-ready'.
 ///
 /// A lambda 'L' is capture-ready for 'V' (var or this) if:
 ///  - its enclosing context is non-dependent
 ///  - and if the chain of lambdas between L and the lambda in which
 ///    V is potentially used (i.e. the lambda at the top of the scope info
 ///    stack), can all capture or have already captured V.
 /// If \p VarToCapture is 'null' then we are trying to capture 'this'.
 ///
 /// Note that a lambda that is deemed 'capture-ready' still needs to be checked
 /// for whether it is 'capture-capable' (see
 /// getStackIndexOfNearestEnclosingCaptureCapableLambda), before it can truly
 /// capture.
 ///
 /// \param FunctionScopes - Sema's stack of nested FunctionScopeInfo's (which a
 ///  LambdaScopeInfo inherits from).  The current/deepest/innermost lambda
 ///  is at the top of the stack and has the highest index.
 /// \param VarToCapture - the variable to capture.  If NULL, capture 'this'.
 ///
 /// \returns An std::optional<unsigned> Index that if evaluates to 'true'
 /// contains the index (into Sema's FunctionScopeInfo stack) of the innermost
 /// lambda which is capture-ready.  If the return value evaluates to 'false'
 /// then no lambda is capture-ready for \p VarToCapture.
 
 static inline std::optional<unsigned>
 getStackIndexOfNearestEnclosingCaptureReadyLambda(
     ArrayRef<const clang::sema::FunctionScopeInfo *> FunctionScopes,
     ValueDecl *VarToCapture) {
   // Label failure to capture.
   const std::optional<unsigned> NoLambdaIsCaptureReady;
 
   // Ignore all inner captured regions.
   unsigned CurScopeIndex = FunctionScopes.size() - 1;
   while (CurScopeIndex > 0 && isa<clang::sema::CapturedRegionScopeInfo>(
                                   FunctionScopes[CurScopeIndex]))
     --CurScopeIndex;
   assert(
       isa<clang::sema::LambdaScopeInfo>(FunctionScopes[CurScopeIndex]) &&
       "The function on the top of sema's function-info stack must be a lambda");
 
   // If VarToCapture is null, we are attempting to capture 'this'.
   const bool IsCapturingThis = !VarToCapture;
   const bool IsCapturingVariable = !IsCapturingThis;
 
   // Start with the current lambda at the top of the stack (highest index).
   DeclContext *EnclosingDC =
       cast<sema::LambdaScopeInfo>(FunctionScopes[CurScopeIndex])->CallOperator;
 
   do {
     const clang::sema::LambdaScopeInfo *LSI =
         cast<sema::LambdaScopeInfo>(FunctionScopes[CurScopeIndex]);
     // IF we have climbed down to an intervening enclosing lambda that contains
     // the variable declaration - it obviously can/must not capture the
     // variable.
     // Since its enclosing DC is dependent, all the lambdas between it and the
     // innermost nested lambda are dependent (otherwise we wouldn't have
     // arrived here) - so we don't yet have a lambda that can capture the
     // variable.
     if (IsCapturingVariable &&
         VarToCapture->getDeclContext()->Equals(EnclosingDC))
       return NoLambdaIsCaptureReady;
 
     // For an enclosing lambda to be capture ready for an entity, all
     // intervening lambda's have to be able to capture that entity. If even
     // one of the intervening lambda's is not capable of capturing the entity
     // then no enclosing lambda can ever capture that entity.
     // For e.g.
     // const int x = 10;
     // [=](auto a) {    #1
     //   [](auto b) {   #2 <-- an intervening lambda that can never capture 'x'
     //    [=](auto c) { #3
     //       f(x, c);  <-- can not lead to x's speculative capture by #1 or #2
     //    }; }; };
     // If they do not have a default implicit capture, check to see
     // if the entity has already been explicitly captured.
     // If even a single dependent enclosing lambda lacks the capability
     // to ever capture this variable, there is no further enclosing
     // non-dependent lambda that can capture this variable.
     if (LSI->ImpCaptureStyle == sema::LambdaScopeInfo::ImpCap_None) {
       if (IsCapturingVariable && !LSI->isCaptured(VarToCapture))
         return NoLambdaIsCaptureReady;
       if (IsCapturingThis && !LSI->isCXXThisCaptured())
         return NoLambdaIsCaptureReady;
     }
     EnclosingDC = getLambdaAwareParentOfDeclContext(EnclosingDC);
 
     assert(CurScopeIndex);
     --CurScopeIndex;
   } while (!EnclosingDC->isTranslationUnit() &&
            EnclosingDC->isDependentContext() &&
            isLambdaCallOperator(EnclosingDC));
 
   assert(CurScopeIndex < (FunctionScopes.size() - 1));
   // If the enclosingDC is not dependent, then the immediately nested lambda
   // (one index above) is capture-ready.
   if (!EnclosingDC->isDependentContext())
     return CurScopeIndex + 1;
   return NoLambdaIsCaptureReady;
 }
 
 /// Examines the FunctionScopeInfo stack to determine the nearest
 /// enclosing lambda (to the current lambda) that is 'capture-capable' for
 /// the variable referenced in the current lambda (i.e. \p VarToCapture).
 /// If successful, returns the index into Sema's FunctionScopeInfo stack
 /// of the capture-capable lambda's LambdaScopeInfo.
 ///
 /// Given the current stack of lambdas being processed by Sema and
 /// the variable of interest, to identify the nearest enclosing lambda (to the
 /// current lambda at the top of the stack) that can truly capture
 /// a variable, it has to have the following two properties:
 ///  a) 'capture-ready' - be the innermost lambda that is 'capture-ready':
 ///     - climb down the stack (i.e. starting from the innermost and examining
 ///       each outer lambda step by step) checking if each enclosing
 ///       lambda can either implicitly or explicitly capture the variable.
 ///       Record the first such lambda that is enclosed in a non-dependent
 ///       context. If no such lambda currently exists return failure.
 ///  b) 'capture-capable' - make sure the 'capture-ready' lambda can truly
 ///  capture the variable by checking all its enclosing lambdas:
 ///     - check if all outer lambdas enclosing the 'capture-ready' lambda
 ///       identified above in 'a' can also capture the variable (this is done
 ///       via tryCaptureVariable for variables and CheckCXXThisCapture for
 ///       'this' by passing in the index of the Lambda identified in step 'a')
 ///
 /// \param FunctionScopes - Sema's stack of nested FunctionScopeInfo's (which a
 /// LambdaScopeInfo inherits from).  The current/deepest/innermost lambda
 /// is at the top of the stack.
 ///
 /// \param VarToCapture - the variable to capture.  If NULL, capture 'this'.
 ///
 ///
 /// \returns An std::optional<unsigned> Index that if evaluates to 'true'
 /// contains the index (into Sema's FunctionScopeInfo stack) of the innermost
 /// lambda which is capture-capable.  If the return value evaluates to 'false'
 /// then no lambda is capture-capable for \p VarToCapture.
 
 std::optional<unsigned>
 clang::getStackIndexOfNearestEnclosingCaptureCapableLambda(
     ArrayRef<const sema::FunctionScopeInfo *> FunctionScopes,
     ValueDecl *VarToCapture, Sema &S) {
 
   const std::optional<unsigned> NoLambdaIsCaptureCapable;
 
   const std::optional<unsigned> OptionalStackIndex =
       getStackIndexOfNearestEnclosingCaptureReadyLambda(FunctionScopes,
                                                         VarToCapture);
   if (!OptionalStackIndex)
     return NoLambdaIsCaptureCapable;
 
   const unsigned IndexOfCaptureReadyLambda = *OptionalStackIndex;
   assert(((IndexOfCaptureReadyLambda != (FunctionScopes.size() - 1)) ||
           S.getCurGenericLambda()) &&
          "The capture ready lambda for a potential capture can only be the "
          "current lambda if it is a generic lambda");
 
   const sema::LambdaScopeInfo *const CaptureReadyLambdaLSI =
       cast<sema::LambdaScopeInfo>(FunctionScopes[IndexOfCaptureReadyLambda]);
 
   // If VarToCapture is null, we are attempting to capture 'this'
   const bool IsCapturingThis = !VarToCapture;
   const bool IsCapturingVariable = !IsCapturingThis;
 
   if (IsCapturingVariable) {
     // Check if the capture-ready lambda can truly capture the variable, by
     // checking whether all enclosing lambdas of the capture-ready lambda allow
     // the capture - i.e. make sure it is capture-capable.
     QualType CaptureType, DeclRefType;
     const bool CanCaptureVariable =
         !S.tryCaptureVariable(VarToCapture,
                               /*ExprVarIsUsedInLoc*/ SourceLocation(),
                               clang::Sema::TryCapture_Implicit,
                               /*EllipsisLoc*/ SourceLocation(),
                               /*BuildAndDiagnose*/ false, CaptureType,
                               DeclRefType, &IndexOfCaptureReadyLambda);
     if (!CanCaptureVariable)
       return NoLambdaIsCaptureCapable;
   } else {
     // Check if the capture-ready lambda can truly capture 'this' by checking
     // whether all enclosing lambdas of the capture-ready lambda can capture
     // 'this'.
     const bool CanCaptureThis =
         !S.CheckCXXThisCapture(
              CaptureReadyLambdaLSI->PotentialThisCaptureLocation,
              /*Explicit*/ false, /*BuildAndDiagnose*/ false,
              &IndexOfCaptureReadyLambda);
     if (!CanCaptureThis)
       return NoLambdaIsCaptureCapable;
   }
   return IndexOfCaptureReadyLambda;
 }
 
 static inline TemplateParameterList *
 getGenericLambdaTemplateParameterList(LambdaScopeInfo *LSI, Sema &SemaRef) {
   if (!LSI->GLTemplateParameterList && !LSI->TemplateParams.empty()) {
     LSI->GLTemplateParameterList = TemplateParameterList::Create(
         SemaRef.Context,
         /*Template kw loc*/ SourceLocation(),
         /*L angle loc*/ LSI->ExplicitTemplateParamsRange.getBegin(),
         LSI->TemplateParams,
         /*R angle loc*/LSI->ExplicitTemplateParamsRange.getEnd(),
         LSI->RequiresClause.get());
   }
   return LSI->GLTemplateParameterList;
 }
 
 CXXRecordDecl *
 Sema::createLambdaClosureType(SourceRange IntroducerRange, TypeSourceInfo *Info,
                               unsigned LambdaDependencyKind,
                               LambdaCaptureDefault CaptureDefault) {
   DeclContext *DC = CurContext;
   while (!(DC->isFunctionOrMethod() || DC->isRecord() || DC->isFileContext()))
     DC = DC->getParent();
 
   bool IsGenericLambda =
       Info && getGenericLambdaTemplateParameterList(getCurLambda(), *this);
   // Start constructing the lambda class.
   CXXRecordDecl *Class = CXXRecordDecl::CreateLambda(
       Context, DC, Info, IntroducerRange.getBegin(), LambdaDependencyKind,
       IsGenericLambda, CaptureDefault);
   DC->addDecl(Class);
 
   return Class;
 }
 
 /// Determine whether the given context is or is enclosed in an inline
 /// function.
 static bool isInInlineFunction(const DeclContext *DC) {
   while (!DC->isFileContext()) {
     if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(DC))
       if (FD->isInlined())
         return true;
 
     DC = DC->getLexicalParent();
   }
 
   return false;
 }
 
 std::tuple<MangleNumberingContext *, Decl *>
 Sema::getCurrentMangleNumberContext(const DeclContext *DC) {
   // Compute the context for allocating mangling numbers in the current
   // expression, if the ABI requires them.
   Decl *ManglingContextDecl = ExprEvalContexts.back().ManglingContextDecl;
 
   enum ContextKind {
     Normal,
     DefaultArgument,
     DataMember,
     InlineVariable,
     TemplatedVariable,
     Concept
   } Kind = Normal;
 
   bool IsInNonspecializedTemplate =
       inTemplateInstantiation() || CurContext->isDependentContext();
 
   // Default arguments of member function parameters that appear in a class
   // definition, as well as the initializers of data members, receive special
   // treatment. Identify them.
   if (ManglingContextDecl) {
     if (ParmVarDecl *Param = dyn_cast<ParmVarDecl>(ManglingContextDecl)) {
       if (const DeclContext *LexicalDC
           = Param->getDeclContext()->getLexicalParent())
         if (LexicalDC->isRecord())
           Kind = DefaultArgument;
     } else if (VarDecl *Var = dyn_cast<VarDecl>(ManglingContextDecl)) {
       if (Var->getMostRecentDecl()->isInline())
         Kind = InlineVariable;
       else if (Var->getDeclContext()->isRecord() && IsInNonspecializedTemplate)
         Kind = TemplatedVariable;
       else if (Var->getDescribedVarTemplate())
         Kind = TemplatedVariable;
       else if (auto *VTS = dyn_cast<VarTemplateSpecializationDecl>(Var)) {
         if (!VTS->isExplicitSpecialization())
           Kind = TemplatedVariable;
       }
     } else if (isa<FieldDecl>(ManglingContextDecl)) {
       Kind = DataMember;
     } else if (isa<ImplicitConceptSpecializationDecl>(ManglingContextDecl)) {
       Kind = Concept;
     }
   }
 
   // Itanium ABI [5.1.7]:
   //   In the following contexts [...] the one-definition rule requires closure
   //   types in different translation units to "correspond":
   switch (Kind) {
   case Normal: {
     //  -- the bodies of inline or templated functions
     if ((IsInNonspecializedTemplate &&
          !(ManglingContextDecl && isa<ParmVarDecl>(ManglingContextDecl))) ||
         isInInlineFunction(CurContext)) {
       while (auto *CD = dyn_cast<CapturedDecl>(DC))
         DC = CD->getParent();
       return std::make_tuple(&Context.getManglingNumberContext(DC), nullptr);
     }
 
     return std::make_tuple(nullptr, nullptr);
   }
 
   case Concept:
     // Concept definitions aren't code generated and thus aren't mangled,
     // however the ManglingContextDecl is important for the purposes of
     // re-forming the template argument list of the lambda for constraint
     // evaluation.
   case DataMember:
     //  -- default member initializers
   case DefaultArgument:
     //  -- default arguments appearing in class definitions
   case InlineVariable:
   case TemplatedVariable:
     //  -- the initializers of inline or templated variables
     return std::make_tuple(
         &Context.getManglingNumberContext(ASTContext::NeedExtraManglingDecl,
                                           ManglingContextDecl),
         ManglingContextDecl);
   }
 
   llvm_unreachable("unexpected context");
 }
 
 static QualType
 buildTypeForLambdaCallOperator(Sema &S, clang::CXXRecordDecl *Class,
                                TemplateParameterList *TemplateParams,
                                TypeSourceInfo *MethodTypeInfo) {
   assert(MethodTypeInfo && "expected a non null type");
 
   QualType MethodType = MethodTypeInfo->getType();
   // If a lambda appears in a dependent context or is a generic lambda (has
   // template parameters) and has an 'auto' return type, deduce it to a
   // dependent type.
   if (Class->isDependentContext() || TemplateParams) {
     const FunctionProtoType *FPT = MethodType->castAs<FunctionProtoType>();
     QualType Result = FPT->getReturnType();
     if (Result->isUndeducedType()) {
       Result = S.SubstAutoTypeDependent(Result);
       MethodType = S.Context.getFunctionType(Result, FPT->getParamTypes(),
                                              FPT->getExtProtoInfo());
     }
   }
   return MethodType;
 }
 
 void Sema::handleLambdaNumbering(
     CXXRecordDecl *Class, CXXMethodDecl *Method,
     std::optional<CXXRecordDecl::LambdaNumbering> NumberingOverride) {
   if (NumberingOverride) {
     Class->setLambdaNumbering(*NumberingOverride);
     return;
   }
 
   ContextRAII ManglingContext(*this, Class->getDeclContext());
 
   auto getMangleNumberingContext =
       [this](CXXRecordDecl *Class,
              Decl *ManglingContextDecl) -> MangleNumberingContext * {
     // Get mangle numbering context if there's any extra decl context.
     if (ManglingContextDecl)
       return &Context.getManglingNumberContext(
           ASTContext::NeedExtraManglingDecl, ManglingContextDecl);
     // Otherwise, from that lambda's decl context.
     auto DC = Class->getDeclContext();
     while (auto *CD = dyn_cast<CapturedDecl>(DC))
       DC = CD->getParent();
     return &Context.getManglingNumberContext(DC);
   };
 
   CXXRecordDecl::LambdaNumbering Numbering;
   MangleNumberingContext *MCtx;
   std::tie(MCtx, Numbering.ContextDecl) =
       getCurrentMangleNumberContext(Class->getDeclContext());
   if (!MCtx && (getLangOpts().CUDA || getLangOpts().SYCLIsDevice ||
                 getLangOpts().SYCLIsHost)) {
     // Force lambda numbering in CUDA/HIP as we need to name lambdas following
     // ODR. Both device- and host-compilation need to have a consistent naming
     // on kernel functions. As lambdas are potential part of these `__global__`
     // function names, they needs numbering following ODR.
     // Also force for SYCL, since we need this for the
     // __builtin_sycl_unique_stable_name implementation, which depends on lambda
     // mangling.
     MCtx = getMangleNumberingContext(Class, Numbering.ContextDecl);
     assert(MCtx && "Retrieving mangle numbering context failed!");
     Numbering.HasKnownInternalLinkage = true;
   }
   if (MCtx) {
     Numbering.IndexInContext = MCtx->getNextLambdaIndex();
     Numbering.ManglingNumber = MCtx->getManglingNumber(Method);
     Numbering.DeviceManglingNumber = MCtx->getDeviceManglingNumber(Method);
     Class->setLambdaNumbering(Numbering);
 
     if (auto *Source =
             dyn_cast_or_null<ExternalSemaSource>(Context.getExternalSource()))
       Source->AssignedLambdaNumbering(Class);
   }
 }
 
 static void buildLambdaScopeReturnType(Sema &S, LambdaScopeInfo *LSI,
                                        CXXMethodDecl *CallOperator,
                                        bool ExplicitResultType) {
   if (ExplicitResultType) {
     LSI->HasImplicitReturnType = false;
     LSI->ReturnType = CallOperator->getReturnType();
     if (!LSI->ReturnType->isDependentType() && !LSI->ReturnType->isVoidType())
       S.RequireCompleteType(CallOperator->getBeginLoc(), LSI->ReturnType,
                             diag::err_lambda_incomplete_result);
   } else {
     LSI->HasImplicitReturnType = true;
   }
 }
 
 void Sema::buildLambdaScope(LambdaScopeInfo *LSI, CXXMethodDecl *CallOperator,
                             SourceRange IntroducerRange,
                             LambdaCaptureDefault CaptureDefault,
                             SourceLocation CaptureDefaultLoc,
                             bool ExplicitParams, bool Mutable) {
   LSI->CallOperator = CallOperator;
   CXXRecordDecl *LambdaClass = CallOperator->getParent();
   LSI->Lambda = LambdaClass;
   if (CaptureDefault == LCD_ByCopy)
     LSI->ImpCaptureStyle = LambdaScopeInfo::ImpCap_LambdaByval;
   else if (CaptureDefault == LCD_ByRef)
     LSI->ImpCaptureStyle = LambdaScopeInfo::ImpCap_LambdaByref;
   LSI->CaptureDefaultLoc = CaptureDefaultLoc;
   LSI->IntroducerRange = IntroducerRange;
   LSI->ExplicitParams = ExplicitParams;
   LSI->Mutable = Mutable;
 }
 
 void Sema::finishLambdaExplicitCaptures(LambdaScopeInfo *LSI) {
   LSI->finishedExplicitCaptures();
 }
 
 void Sema::ActOnLambdaExplicitTemplateParameterList(
     LambdaIntroducer &Intro, SourceLocation LAngleLoc,
     ArrayRef<NamedDecl *> TParams, SourceLocation RAngleLoc,
     ExprResult RequiresClause) {
   LambdaScopeInfo *LSI = getCurLambda();
   assert(LSI && "Expected a lambda scope");
   assert(LSI->NumExplicitTemplateParams == 0 &&
          "Already acted on explicit template parameters");
   assert(LSI->TemplateParams.empty() &&
          "Explicit template parameters should come "
          "before invented (auto) ones");
   assert(!TParams.empty() &&
          "No template parameters to act on");
   LSI->TemplateParams.append(TParams.begin(), TParams.end());
   LSI->NumExplicitTemplateParams = TParams.size();
   LSI->ExplicitTemplateParamsRange = {LAngleLoc, RAngleLoc};
   LSI->RequiresClause = RequiresClause;
 }
 
 /// If this expression is an enumerator-like expression of some type
 /// T, return the type T; otherwise, return null.
 ///
 /// Pointer comparisons on the result here should always work because
 /// it's derived from either the parent of an EnumConstantDecl
 /// (i.e. the definition) or the declaration returned by
 /// EnumType::getDecl() (i.e. the definition).
 static EnumDecl *findEnumForBlockReturn(Expr *E) {
   // An expression is an enumerator-like expression of type T if,
   // ignoring parens and parens-like expressions:
   E = E->IgnoreParens();
 
   //  - it is an enumerator whose enum type is T or
   if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
     if (EnumConstantDecl *D
           = dyn_cast<EnumConstantDecl>(DRE->getDecl())) {
       return cast<EnumDecl>(D->getDeclContext());
     }
     return nullptr;
   }
 
   //  - it is a comma expression whose RHS is an enumerator-like
   //    expression of type T or
   if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
     if (BO->getOpcode() == BO_Comma)
       return findEnumForBlockReturn(BO->getRHS());
     return nullptr;
   }
 
   //  - it is a statement-expression whose value expression is an
   //    enumerator-like expression of type T or
   if (StmtExpr *SE = dyn_cast<StmtExpr>(E)) {
     if (Expr *last = dyn_cast_or_null<Expr>(SE->getSubStmt()->body_back()))
       return findEnumForBlockReturn(last);
     return nullptr;
   }
 
   //   - it is a ternary conditional operator (not the GNU ?:
   //     extension) whose second and third operands are
   //     enumerator-like expressions of type T or
   if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
     if (EnumDecl *ED = findEnumForBlockReturn(CO->getTrueExpr()))
       if (ED == findEnumForBlockReturn(CO->getFalseExpr()))
         return ED;
     return nullptr;
   }
 
   // (implicitly:)
   //   - it is an implicit integral conversion applied to an
   //     enumerator-like expression of type T or
   if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
     // We can sometimes see integral conversions in valid
     // enumerator-like expressions.
     if (ICE->getCastKind() == CK_IntegralCast)
       return findEnumForBlockReturn(ICE->getSubExpr());
 
     // Otherwise, just rely on the type.
   }
 
   //   - it is an expression of that formal enum type.
   if (const EnumType *ET = E->getType()->getAs<EnumType>()) {
     return ET->getDecl();
   }
 
   // Otherwise, nope.
   return nullptr;
 }
 
 /// Attempt to find a type T for which the returned expression of the
 /// given statement is an enumerator-like expression of that type.
 static EnumDecl *findEnumForBlockReturn(ReturnStmt *ret) {
   if (Expr *retValue = ret->getRetValue())
     return findEnumForBlockReturn(retValue);
   return nullptr;
 }
 
 /// Attempt to find a common type T for which all of the returned
 /// expressions in a block are enumerator-like expressions of that
 /// type.
 static EnumDecl *findCommonEnumForBlockReturns(ArrayRef<ReturnStmt*> returns) {
   ArrayRef<ReturnStmt*>::iterator i = returns.begin(), e = returns.end();
 
   // Try to find one for the first return.
   EnumDecl *ED = findEnumForBlockReturn(*i);
   if (!ED) return nullptr;
 
   // Check that the rest of the returns have the same enum.
   for (++i; i != e; ++i) {
     if (findEnumForBlockReturn(*i) != ED)
       return nullptr;
   }
 
   // Never infer an anonymous enum type.
   if (!ED->hasNameForLinkage()) return nullptr;
 
   return ED;
 }
 
 /// Adjust the given return statements so that they formally return
 /// the given type.  It should require, at most, an IntegralCast.
 static void adjustBlockReturnsToEnum(Sema &S, ArrayRef<ReturnStmt*> returns,
                                      QualType returnType) {
   for (ArrayRef<ReturnStmt*>::iterator
          i = returns.begin(), e = returns.end(); i != e; ++i) {
     ReturnStmt *ret = *i;
     Expr *retValue = ret->getRetValue();
     if (S.Context.hasSameType(retValue->getType(), returnType))
       continue;
 
     // Right now we only support integral fixup casts.
     assert(returnType->isIntegralOrUnscopedEnumerationType());
     assert(retValue->getType()->isIntegralOrUnscopedEnumerationType());
 
     ExprWithCleanups *cleanups = dyn_cast<ExprWithCleanups>(retValue);
 
     Expr *E = (cleanups ? cleanups->getSubExpr() : retValue);
     E = ImplicitCastExpr::Create(S.Context, returnType, CK_IntegralCast, E,
                                  /*base path*/ nullptr, VK_PRValue,
                                  FPOptionsOverride());
     if (cleanups) {
       cleanups->setSubExpr(E);
     } else {
       ret->setRetValue(E);
     }
   }
 }
 
 void Sema::deduceClosureReturnType(CapturingScopeInfo &CSI) {
   assert(CSI.HasImplicitReturnType);
   // If it was ever a placeholder, it had to been deduced to DependentTy.
   assert(CSI.ReturnType.isNull() || !CSI.ReturnType->isUndeducedType());
   assert((!isa<LambdaScopeInfo>(CSI) || !getLangOpts().CPlusPlus14) &&
          "lambda expressions use auto deduction in C++14 onwards");
 
   // C++ core issue 975:
   //   If a lambda-expression does not include a trailing-return-type,
   //   it is as if the trailing-return-type denotes the following type:
   //     - if there are no return statements in the compound-statement,
   //       or all return statements return either an expression of type
   //       void or no expression or braced-init-list, the type void;
   //     - otherwise, if all return statements return an expression
   //       and the types of the returned expressions after
   //       lvalue-to-rvalue conversion (4.1 [conv.lval]),
   //       array-to-pointer conversion (4.2 [conv.array]), and
   //       function-to-pointer conversion (4.3 [conv.func]) are the
   //       same, that common type;
   //     - otherwise, the program is ill-formed.
   //
   // C++ core issue 1048 additionally removes top-level cv-qualifiers
   // from the types of returned expressions to match the C++14 auto
   // deduction rules.
   //
   // In addition, in blocks in non-C++ modes, if all of the return
   // statements are enumerator-like expressions of some type T, where
   // T has a name for linkage, then we infer the return type of the
   // block to be that type.
 
   // First case: no return statements, implicit void return type.
   ASTContext &Ctx = getASTContext();
   if (CSI.Returns.empty()) {
     // It's possible there were simply no /valid/ return statements.
     // In this case, the first one we found may have at least given us a type.
     if (CSI.ReturnType.isNull())
       CSI.ReturnType = Ctx.VoidTy;
     return;
   }
 
   // Second case: at least one return statement has dependent type.
   // Delay type checking until instantiation.
   assert(!CSI.ReturnType.isNull() && "We should have a tentative return type.");
   if (CSI.ReturnType->isDependentType())
     return;
 
   // Try to apply the enum-fuzz rule.
   if (!getLangOpts().CPlusPlus) {
     assert(isa<BlockScopeInfo>(CSI));
     const EnumDecl *ED = findCommonEnumForBlockReturns(CSI.Returns);
     if (ED) {
       CSI.ReturnType = Context.getTypeDeclType(ED);
       adjustBlockReturnsToEnum(*this, CSI.Returns, CSI.ReturnType);
       return;
     }
   }
 
   // Third case: only one return statement. Don't bother doing extra work!
   if (CSI.Returns.size() == 1)
     return;
 
   // General case: many return statements.
   // Check that they all have compatible return types.
 
   // We require the return types to strictly match here.
   // Note that we've already done the required promotions as part of
   // processing the return statement.
   for (const ReturnStmt *RS : CSI.Returns) {
     const Expr *RetE = RS->getRetValue();
 
     QualType ReturnType =
         (RetE ? RetE->getType() : Context.VoidTy).getUnqualifiedType();
     if (Context.getCanonicalFunctionResultType(ReturnType) ==
           Context.getCanonicalFunctionResultType(CSI.ReturnType)) {
       // Use the return type with the strictest possible nullability annotation.
       auto RetTyNullability = ReturnType->getNullability();
       auto BlockNullability = CSI.ReturnType->getNullability();
       if (BlockNullability &&
           (!RetTyNullability ||
            hasWeakerNullability(*RetTyNullability, *BlockNullability)))
         CSI.ReturnType = ReturnType;
       continue;
     }
 
     // FIXME: This is a poor diagnostic for ReturnStmts without expressions.
     // TODO: It's possible that the *first* return is the divergent one.
     Diag(RS->getBeginLoc(),
          diag::err_typecheck_missing_return_type_incompatible)
         << ReturnType << CSI.ReturnType << isa<LambdaScopeInfo>(CSI);
     // Continue iterating so that we keep emitting diagnostics.
   }
 }
 
 QualType Sema::buildLambdaInitCaptureInitialization(
     SourceLocation Loc, bool ByRef, SourceLocation EllipsisLoc,
     std::optional<unsigned> NumExpansions, IdentifierInfo *Id,
     bool IsDirectInit, Expr *&Init) {
   // Create an 'auto' or 'auto&' TypeSourceInfo that we can use to
   // deduce against.
   QualType DeductType = Context.getAutoDeductType();
   TypeLocBuilder TLB;
   AutoTypeLoc TL = TLB.push<AutoTypeLoc>(DeductType);
   TL.setNameLoc(Loc);
   if (ByRef) {
     DeductType = BuildReferenceType(DeductType, true, Loc, Id);
     assert(!DeductType.isNull() && "can't build reference to auto");
     TLB.push<ReferenceTypeLoc>(DeductType).setSigilLoc(Loc);
   }
   if (EllipsisLoc.isValid()) {
     if (Init->containsUnexpandedParameterPack()) {
       Diag(EllipsisLoc, getLangOpts().CPlusPlus20
                             ? diag::warn_cxx17_compat_init_capture_pack
                             : diag::ext_init_capture_pack);
       DeductType = Context.getPackExpansionType(DeductType, NumExpansions,
                                                 /*ExpectPackInType=*/false);
       TLB.push<PackExpansionTypeLoc>(DeductType).setEllipsisLoc(EllipsisLoc);
     } else {
       // Just ignore the ellipsis for now and form a non-pack variable. We'll
       // diagnose this later when we try to capture it.
     }
   }
   TypeSourceInfo *TSI = TLB.getTypeSourceInfo(Context, DeductType);
 
   // Deduce the type of the init capture.
   QualType DeducedType = deduceVarTypeFromInitializer(
       /*VarDecl*/nullptr, DeclarationName(Id), DeductType, TSI,
       SourceRange(Loc, Loc), IsDirectInit, Init);
   if (DeducedType.isNull())
     return QualType();
 
   // Are we a non-list direct initialization?
   ParenListExpr *CXXDirectInit = dyn_cast<ParenListExpr>(Init);
 
   // Perform initialization analysis and ensure any implicit conversions
   // (such as lvalue-to-rvalue) are enforced.
   InitializedEntity Entity =
       InitializedEntity::InitializeLambdaCapture(Id, DeducedType, Loc);
   InitializationKind Kind =
       IsDirectInit
           ? (CXXDirectInit ? InitializationKind::CreateDirect(
                                  Loc, Init->getBeginLoc(), Init->getEndLoc())
                            : InitializationKind::CreateDirectList(Loc))
           : InitializationKind::CreateCopy(Loc, Init->getBeginLoc());
 
   MultiExprArg Args = Init;
   if (CXXDirectInit)
     Args =
         MultiExprArg(CXXDirectInit->getExprs(), CXXDirectInit->getNumExprs());
   QualType DclT;
   InitializationSequence InitSeq(*this, Entity, Kind, Args);
   ExprResult Result = InitSeq.Perform(*this, Entity, Kind, Args, &DclT);
 
   if (Result.isInvalid())
     return QualType();
 
   Init = Result.getAs<Expr>();
   return DeducedType;
 }
 
 VarDecl *Sema::createLambdaInitCaptureVarDecl(
     SourceLocation Loc, QualType InitCaptureType, SourceLocation EllipsisLoc,
     IdentifierInfo *Id, unsigned InitStyle, Expr *Init, DeclContext *DeclCtx) {
   // FIXME: Retain the TypeSourceInfo from buildLambdaInitCaptureInitialization
   // rather than reconstructing it here.
   TypeSourceInfo *TSI = Context.getTrivialTypeSourceInfo(InitCaptureType, Loc);
   if (auto PETL = TSI->getTypeLoc().getAs<PackExpansionTypeLoc>())
     PETL.setEllipsisLoc(EllipsisLoc);
 
   // Create a dummy variable representing the init-capture. This is not actually
   // used as a variable, and only exists as a way to name and refer to the
   // init-capture.
   // FIXME: Pass in separate source locations for '&' and identifier.
   VarDecl *NewVD = VarDecl::Create(Context, DeclCtx, Loc, Loc, Id,
                                    InitCaptureType, TSI, SC_Auto);
   NewVD->setInitCapture(true);
   NewVD->setReferenced(true);
   // FIXME: Pass in a VarDecl::InitializationStyle.
   NewVD->setInitStyle(static_cast<VarDecl::InitializationStyle>(InitStyle));
   NewVD->markUsed(Context);
   NewVD->setInit(Init);
   if (NewVD->isParameterPack())
     getCurLambda()->LocalPacks.push_back(NewVD);
   return NewVD;
 }
 
 void Sema::addInitCapture(LambdaScopeInfo *LSI, VarDecl *Var, bool ByRef) {
   assert(Var->isInitCapture() && "init capture flag should be set");
   LSI->addCapture(Var, /*isBlock=*/false, ByRef,
                   /*isNested=*/false, Var->getLocation(), SourceLocation(),
                   Var->getType(), /*Invalid=*/false);
 }
 
 // Unlike getCurLambda, getCurrentLambdaScopeUnsafe doesn't
 // check that the current lambda is in a consistent or fully constructed state.
 static LambdaScopeInfo *getCurrentLambdaScopeUnsafe(Sema &S) {
   assert(!S.FunctionScopes.empty());
   return cast<LambdaScopeInfo>(S.FunctionScopes[S.FunctionScopes.size() - 1]);
 }
 
 static TypeSourceInfo *
 getDummyLambdaType(Sema &S, SourceLocation Loc = SourceLocation()) {
   // C++11 [expr.prim.lambda]p4:
   //   If a lambda-expression does not include a lambda-declarator, it is as
   //   if the lambda-declarator were ().
   FunctionProtoType::ExtProtoInfo EPI(S.Context.getDefaultCallingConvention(
       /*IsVariadic=*/false, /*IsCXXMethod=*/true));
   EPI.HasTrailingReturn = true;
   EPI.TypeQuals.addConst();
   LangAS AS = S.getDefaultCXXMethodAddrSpace();
   if (AS != LangAS::Default)
     EPI.TypeQuals.addAddressSpace(AS);
 
   // C++1y [expr.prim.lambda]:
   //   The lambda return type is 'auto', which is replaced by the
   //   trailing-return type if provided and/or deduced from 'return'
   //   statements
   // We don't do this before C++1y, because we don't support deduced return
   // types there.
   QualType DefaultTypeForNoTrailingReturn = S.getLangOpts().CPlusPlus14
                                                 ? S.Context.getAutoDeductType()
                                                 : S.Context.DependentTy;
   QualType MethodTy = S.Context.getFunctionType(DefaultTypeForNoTrailingReturn,
                                                 std::nullopt, EPI);
   return S.Context.getTrivialTypeSourceInfo(MethodTy, Loc);
 }
 
 static TypeSourceInfo *getLambdaType(Sema &S, LambdaIntroducer &Intro,
                                      Declarator &ParamInfo, Scope *CurScope,
                                      SourceLocation Loc,
                                      bool &ExplicitResultType) {
 
   ExplicitResultType = false;
 
   assert(
       (ParamInfo.getDeclSpec().getStorageClassSpec() ==
            DeclSpec::SCS_unspecified ||
        ParamInfo.getDeclSpec().getStorageClassSpec() == DeclSpec::SCS_static) &&
       "Unexpected storage specifier");
   bool IsLambdaStatic =
       ParamInfo.getDeclSpec().getStorageClassSpec() == DeclSpec::SCS_static;
 
   TypeSourceInfo *MethodTyInfo;
 
   if (ParamInfo.getNumTypeObjects() == 0) {
     MethodTyInfo = getDummyLambdaType(S, Loc);
   } else {
     DeclaratorChunk::FunctionTypeInfo &FTI = ParamInfo.getFunctionTypeInfo();
     ExplicitResultType = FTI.hasTrailingReturnType();
     if (!FTI.hasMutableQualifier() && !IsLambdaStatic)
       FTI.getOrCreateMethodQualifiers().SetTypeQual(DeclSpec::TQ_const, Loc);
 
     if (ExplicitResultType && S.getLangOpts().HLSL) {
       QualType RetTy = FTI.getTrailingReturnType().get();
       if (!RetTy.isNull()) {
         // HLSL does not support specifying an address space on a lambda return
         // type.
         LangAS AddressSpace = RetTy.getAddressSpace();
         if (AddressSpace != LangAS::Default)
           S.Diag(FTI.getTrailingReturnTypeLoc(),
                  diag::err_return_value_with_address_space);
       }
     }
 
     MethodTyInfo = S.GetTypeForDeclarator(ParamInfo, CurScope);
     assert(MethodTyInfo && "no type from lambda-declarator");
 
     // Check for unexpanded parameter packs in the method type.
     if (MethodTyInfo->getType()->containsUnexpandedParameterPack())
       S.DiagnoseUnexpandedParameterPack(Intro.Range.getBegin(), MethodTyInfo,
                                         S.UPPC_DeclarationType);
   }
   return MethodTyInfo;
 }
 
 CXXMethodDecl *Sema::CreateLambdaCallOperator(SourceRange IntroducerRange,
                                               CXXRecordDecl *Class) {
 
   // C++20 [expr.prim.lambda.closure]p3:
   // The closure type for a lambda-expression has a public inline function
   // call operator (for a non-generic lambda) or function call operator
   // template (for a generic lambda) whose parameters and return type are
   // described by the lambda-expression's parameter-declaration-clause
   // and trailing-return-type respectively.
   DeclarationName MethodName =
       Context.DeclarationNames.getCXXOperatorName(OO_Call);
   DeclarationNameLoc MethodNameLoc =
       DeclarationNameLoc::makeCXXOperatorNameLoc(IntroducerRange.getBegin());
   CXXMethodDecl *Method = CXXMethodDecl::Create(
       Context, Class, SourceLocation(),
       DeclarationNameInfo(MethodName, IntroducerRange.getBegin(),
                           MethodNameLoc),
       QualType(), /*Tinfo=*/nullptr, SC_None,
       getCurFPFeatures().isFPConstrained(),
       /*isInline=*/true, ConstexprSpecKind::Unspecified, SourceLocation(),
       /*TrailingRequiresClause=*/nullptr);
   Method->setAccess(AS_public);
   return Method;
 }
 
 void Sema::CompleteLambdaCallOperator(
     CXXMethodDecl *Method, SourceLocation LambdaLoc,
     SourceLocation CallOperatorLoc, Expr *TrailingRequiresClause,
     TypeSourceInfo *MethodTyInfo, ConstexprSpecKind ConstexprKind,
     StorageClass SC, ArrayRef<ParmVarDecl *> Params,
     bool HasExplicitResultType) {
 
   LambdaScopeInfo *LSI = getCurrentLambdaScopeUnsafe(*this);
 
   if (TrailingRequiresClause)
     Method->setTrailingRequiresClause(TrailingRequiresClause);
 
   TemplateParameterList *TemplateParams =
       getGenericLambdaTemplateParameterList(LSI, *this);
 
   DeclContext *DC = Method->getLexicalDeclContext();
   Method->setLexicalDeclContext(LSI->Lambda);
   if (TemplateParams) {
     FunctionTemplateDecl *TemplateMethod = FunctionTemplateDecl::Create(
         Context, LSI->Lambda, Method->getLocation(), Method->getDeclName(),
         TemplateParams, Method);
     TemplateMethod->setAccess(AS_public);
     Method->setDescribedFunctionTemplate(TemplateMethod);
     LSI->Lambda->addDecl(TemplateMethod);
     TemplateMethod->setLexicalDeclContext(DC);
   } else {
     LSI->Lambda->addDecl(Method);
   }
   LSI->Lambda->setLambdaIsGeneric(TemplateParams);
   LSI->Lambda->setLambdaTypeInfo(MethodTyInfo);
 
   Method->setLexicalDeclContext(DC);
   Method->setLocation(LambdaLoc);
   Method->setInnerLocStart(CallOperatorLoc);
   Method->setTypeSourceInfo(MethodTyInfo);
   Method->setType(buildTypeForLambdaCallOperator(*this, LSI->Lambda,
                                                  TemplateParams, MethodTyInfo));
   Method->setConstexprKind(ConstexprKind);
   Method->setStorageClass(SC);
   if (!Params.empty()) {
     CheckParmsForFunctionDef(Params, /*CheckParameterNames=*/false);
     Method->setParams(Params);
     for (auto P : Method->parameters()) {
       assert(P && "null in a parameter list");
       P->setOwningFunction(Method);
     }
   }
 
   buildLambdaScopeReturnType(*this, LSI, Method, HasExplicitResultType);
 }
 
 void Sema::ActOnLambdaExpressionAfterIntroducer(LambdaIntroducer &Intro,
                                                 Scope *CurrentScope) {
 
   LambdaScopeInfo *LSI = getCurLambda();
   assert(LSI && "LambdaScopeInfo should be on stack!");
 
   if (Intro.Default == LCD_ByCopy)
     LSI->ImpCaptureStyle = LambdaScopeInfo::ImpCap_LambdaByval;
   else if (Intro.Default == LCD_ByRef)
     LSI->ImpCaptureStyle = LambdaScopeInfo::ImpCap_LambdaByref;
   LSI->CaptureDefaultLoc = Intro.DefaultLoc;
   LSI->IntroducerRange = Intro.Range;
   LSI->AfterParameterList = false;
 
   assert(LSI->NumExplicitTemplateParams == 0);
 
   // Determine if we're within a context where we know that the lambda will
   // be dependent, because there are template parameters in scope.
   CXXRecordDecl::LambdaDependencyKind LambdaDependencyKind =
       CXXRecordDecl::LDK_Unknown;
   if (LSI->NumExplicitTemplateParams > 0) {
     Scope *TemplateParamScope = CurScope->getTemplateParamParent();
     assert(TemplateParamScope &&
            "Lambda with explicit template param list should establish a "
            "template param scope");
     assert(TemplateParamScope->getParent());
     if (TemplateParamScope->getParent()->getTemplateParamParent() != nullptr)
       LambdaDependencyKind = CXXRecordDecl::LDK_AlwaysDependent;
   } else if (CurScope->getTemplateParamParent() != nullptr) {
     LambdaDependencyKind = CXXRecordDecl::LDK_AlwaysDependent;
   }
 
   CXXRecordDecl *Class = createLambdaClosureType(
       Intro.Range, /*Info=*/nullptr, LambdaDependencyKind, Intro.Default);
   LSI->Lambda = Class;
 
   CXXMethodDecl *Method = CreateLambdaCallOperator(Intro.Range, Class);
   LSI->CallOperator = Method;
   Method->setLexicalDeclContext(CurContext);
 
   PushDeclContext(CurScope, Method);
 
   bool ContainsUnexpandedParameterPack = false;
 
   // Distinct capture names, for diagnostics.
   llvm::DenseMap<IdentifierInfo *, ValueDecl *> CaptureNames;
 
   // Handle explicit captures.
   SourceLocation PrevCaptureLoc =
       Intro.Default == LCD_None ? Intro.Range.getBegin() : Intro.DefaultLoc;
   for (auto C = Intro.Captures.begin(), E = Intro.Captures.end(); C != E;
        PrevCaptureLoc = C->Loc, ++C) {
     if (C->Kind == LCK_This || C->Kind == LCK_StarThis) {
       if (C->Kind == LCK_StarThis)
         Diag(C->Loc, !getLangOpts().CPlusPlus17
                          ? diag::ext_star_this_lambda_capture_cxx17
                          : diag::warn_cxx14_compat_star_this_lambda_capture);
 
       // C++11 [expr.prim.lambda]p8:
       //   An identifier or this shall not appear more than once in a
       //   lambda-capture.
       if (LSI->isCXXThisCaptured()) {
         Diag(C->Loc, diag::err_capture_more_than_once)
             << "'this'" << SourceRange(LSI->getCXXThisCapture().getLocation())
             << FixItHint::CreateRemoval(
                    SourceRange(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
         continue;
       }
 
       // C++20 [expr.prim.lambda]p8:
       //  If a lambda-capture includes a capture-default that is =,
       //  each simple-capture of that lambda-capture shall be of the form
       //  "&identifier", "this", or "* this". [ Note: The form [&,this] is
       //  redundant but accepted for compatibility with ISO C++14. --end note ]
       if (Intro.Default == LCD_ByCopy && C->Kind != LCK_StarThis)
         Diag(C->Loc, !getLangOpts().CPlusPlus20
                          ? diag::ext_equals_this_lambda_capture_cxx20
                          : diag::warn_cxx17_compat_equals_this_lambda_capture);
 
       // C++11 [expr.prim.lambda]p12:
       //   If this is captured by a local lambda expression, its nearest
       //   enclosing function shall be a non-static member function.
       QualType ThisCaptureType = getCurrentThisType();
       if (ThisCaptureType.isNull()) {
         Diag(C->Loc, diag::err_this_capture) << true;
         continue;
       }
 
       CheckCXXThisCapture(C->Loc, /*Explicit=*/true, /*BuildAndDiagnose*/ true,
                           /*FunctionScopeIndexToStopAtPtr*/ nullptr,
                           C->Kind == LCK_StarThis);
       if (!LSI->Captures.empty())
         LSI->ExplicitCaptureRanges[LSI->Captures.size() - 1] = C->ExplicitRange;
       continue;
     }
 
     assert(C->Id && "missing identifier for capture");
 
     if (C->Init.isInvalid())
       continue;
 
     ValueDecl *Var = nullptr;
     if (C->Init.isUsable()) {
       Diag(C->Loc, getLangOpts().CPlusPlus14
                        ? diag::warn_cxx11_compat_init_capture
                        : diag::ext_init_capture);
 
       // If the initializer expression is usable, but the InitCaptureType
       // is not, then an error has occurred - so ignore the capture for now.
       // for e.g., [n{0}] { }; <-- if no <initializer_list> is included.
       // FIXME: we should create the init capture variable and mark it invalid
       // in this case.
       if (C->InitCaptureType.get().isNull())
         continue;
 
       if (C->Init.get()->containsUnexpandedParameterPack() &&
           !C->InitCaptureType.get()->getAs<PackExpansionType>())
         DiagnoseUnexpandedParameterPack(C->Init.get(), UPPC_Initializer);
 
       unsigned InitStyle;
       switch (C->InitKind) {
       case LambdaCaptureInitKind::NoInit:
         llvm_unreachable("not an init-capture?");
       case LambdaCaptureInitKind::CopyInit:
         InitStyle = VarDecl::CInit;
         break;
       case LambdaCaptureInitKind::DirectInit:
         InitStyle = VarDecl::CallInit;
         break;
       case LambdaCaptureInitKind::ListInit:
         InitStyle = VarDecl::ListInit;
         break;
       }
       Var = createLambdaInitCaptureVarDecl(C->Loc, C->InitCaptureType.get(),
                                            C->EllipsisLoc, C->Id, InitStyle,
                                            C->Init.get(), Method);
       assert(Var && "createLambdaInitCaptureVarDecl returned a null VarDecl?");
       if (auto *V = dyn_cast<VarDecl>(Var))
         CheckShadow(CurrentScope, V);
       PushOnScopeChains(Var, CurrentScope, false);
     } else {
       assert(C->InitKind == LambdaCaptureInitKind::NoInit &&
              "init capture has valid but null init?");
 
       // C++11 [expr.prim.lambda]p8:
       //   If a lambda-capture includes a capture-default that is &, the
       //   identifiers in the lambda-capture shall not be preceded by &.
       //   If a lambda-capture includes a capture-default that is =, [...]
       //   each identifier it contains shall be preceded by &.
       if (C->Kind == LCK_ByRef && Intro.Default == LCD_ByRef) {
         Diag(C->Loc, diag::err_reference_capture_with_reference_default)
             << FixItHint::CreateRemoval(
                 SourceRange(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
         continue;
       } else if (C->Kind == LCK_ByCopy && Intro.Default == LCD_ByCopy) {
         Diag(C->Loc, diag::err_copy_capture_with_copy_default)
             << FixItHint::CreateRemoval(
                 SourceRange(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
         continue;
       }
 
       // C++11 [expr.prim.lambda]p10:
       //   The identifiers in a capture-list are looked up using the usual
       //   rules for unqualified name lookup (3.4.1)
       DeclarationNameInfo Name(C->Id, C->Loc);
       LookupResult R(*this, Name, LookupOrdinaryName);
       LookupName(R, CurScope);
       if (R.isAmbiguous())
         continue;
       if (R.empty()) {
         // FIXME: Disable corrections that would add qualification?
         CXXScopeSpec ScopeSpec;
         DeclFilterCCC<VarDecl> Validator{};
         if (DiagnoseEmptyLookup(CurScope, ScopeSpec, R, Validator))
           continue;
       }
 
       if (auto *BD = R.getAsSingle<BindingDecl>())
         Var = BD;
       else
         Var = R.getAsSingle<VarDecl>();
       if (Var && DiagnoseUseOfDecl(Var, C->Loc))
         continue;
     }
 
     // C++11 [expr.prim.lambda]p10:
     //   [...] each such lookup shall find a variable with automatic storage
     //   duration declared in the reaching scope of the local lambda expression.
     // Note that the 'reaching scope' check happens in tryCaptureVariable().
     if (!Var) {
       Diag(C->Loc, diag::err_capture_does_not_name_variable) << C->Id;
       continue;
     }
 
     // C++11 [expr.prim.lambda]p8:
     //   An identifier or this shall not appear more than once in a
     //   lambda-capture.
     if (auto [It, Inserted] = CaptureNames.insert(std::pair{C->Id, Var});
         !Inserted) {
       if (C->InitKind == LambdaCaptureInitKind::NoInit &&
           !Var->isInitCapture()) {
         Diag(C->Loc, diag::err_capture_more_than_once)
             << C->Id << It->second->getBeginLoc()
             << FixItHint::CreateRemoval(
                    SourceRange(getLocForEndOfToken(PrevCaptureLoc), C->Loc));
       } else
         // Previous capture captured something different (one or both was
         // an init-capture): no fixit.
         Diag(C->Loc, diag::err_capture_more_than_once) << C->Id;
       continue;
     }
 
     // Ignore invalid decls; they'll just confuse the code later.
     if (Var->isInvalidDecl())
       continue;
 
     VarDecl *Underlying = Var->getPotentiallyDecomposedVarDecl();
 
     if (!Underlying->hasLocalStorage()) {
       Diag(C->Loc, diag::err_capture_non_automatic_variable) << C->Id;
       Diag(Var->getLocation(), diag::note_previous_decl) << C->Id;
       continue;
     }
 
     // C++11 [expr.prim.lambda]p23:
     //   A capture followed by an ellipsis is a pack expansion (14.5.3).
     SourceLocation EllipsisLoc;
     if (C->EllipsisLoc.isValid()) {
       if (Var->isParameterPack()) {
         EllipsisLoc = C->EllipsisLoc;
       } else {
         Diag(C->EllipsisLoc, diag::err_pack_expansion_without_parameter_packs)
             << (C->Init.isUsable() ? C->Init.get()->getSourceRange()
                                    : SourceRange(C->Loc));
 
         // Just ignore the ellipsis.
       }
     } else if (Var->isParameterPack()) {
       ContainsUnexpandedParameterPack = true;
     }
 
     if (C->Init.isUsable()) {
       addInitCapture(LSI, cast<VarDecl>(Var), C->Kind == LCK_ByRef);
       PushOnScopeChains(Var, CurScope, false);
     } else {
       TryCaptureKind Kind = C->Kind == LCK_ByRef ? TryCapture_ExplicitByRef
                                                  : TryCapture_ExplicitByVal;
       tryCaptureVariable(Var, C->Loc, Kind, EllipsisLoc);
     }
     if (!LSI->Captures.empty())
       LSI->ExplicitCaptureRanges[LSI->Captures.size() - 1] = C->ExplicitRange;
   }
   finishLambdaExplicitCaptures(LSI);
   LSI->ContainsUnexpandedParameterPack |= ContainsUnexpandedParameterPack;
   PopDeclContext();
 }
 
 void Sema::ActOnLambdaClosureQualifiers(LambdaIntroducer &Intro,
                                         SourceLocation MutableLoc) {
 
   LambdaScopeInfo *LSI = getCurrentLambdaScopeUnsafe(*this);
   LSI->Mutable = MutableLoc.isValid();
   ContextRAII Context(*this, LSI->CallOperator, /*NewThisContext*/ false);
 
   // C++11 [expr.prim.lambda]p9:
   //   A lambda-expression whose smallest enclosing scope is a block scope is a
   //   local lambda expression; any other lambda expression shall not have a
   //   capture-default or simple-capture in its lambda-introducer.
   //
   // For simple-captures, this is covered by the check below that any named
   // entity is a variable that can be captured.
   //
   // For DR1632, we also allow a capture-default in any context where we can
   // odr-use 'this' (in particular, in a default initializer for a non-static
   // data member).
   if (Intro.Default != LCD_None &&
       !LSI->Lambda->getParent()->isFunctionOrMethod() &&
       (getCurrentThisType().isNull() ||
        CheckCXXThisCapture(SourceLocation(), /*Explicit=*/true,
                            /*BuildAndDiagnose=*/false)))
     Diag(Intro.DefaultLoc, diag::err_capture_default_non_local);
 }
 
 void Sema::ActOnLambdaClosureParameters(
     Scope *LambdaScope, MutableArrayRef<DeclaratorChunk::ParamInfo> Params) {
   LambdaScopeInfo *LSI = getCurrentLambdaScopeUnsafe(*this);
   PushDeclContext(LambdaScope, LSI->CallOperator);
 
   for (const DeclaratorChunk::ParamInfo &P : Params) {
     auto *Param = cast<ParmVarDecl>(P.Param);
     Param->setOwningFunction(LSI->CallOperator);
     if (Param->getIdentifier())
       PushOnScopeChains(Param, LambdaScope, false);
   }
 
   LSI->AfterParameterList = true;
 }
 
 void Sema::ActOnStartOfLambdaDefinition(LambdaIntroducer &Intro,
                                         Declarator &ParamInfo,
                                         const DeclSpec &DS) {
 
   LambdaScopeInfo *LSI = getCurrentLambdaScopeUnsafe(*this);
   LSI->CallOperator->setConstexprKind(DS.getConstexprSpecifier());
 
   SmallVector<ParmVarDecl *, 8> Params;
   bool ExplicitResultType;
 
   SourceLocation TypeLoc, CallOperatorLoc;
   if (ParamInfo.getNumTypeObjects() == 0) {
     CallOperatorLoc = TypeLoc = Intro.Range.getEnd();
   } else {
     unsigned Index;
     ParamInfo.isFunctionDeclarator(Index);
     const auto &Object = ParamInfo.getTypeObject(Index);
     TypeLoc =
         Object.Loc.isValid() ? Object.Loc : ParamInfo.getSourceRange().getEnd();
     CallOperatorLoc = ParamInfo.getSourceRange().getEnd();
   }
 
   CXXRecordDecl *Class = LSI->Lambda;
   CXXMethodDecl *Method = LSI->CallOperator;
 
   TypeSourceInfo *MethodTyInfo = getLambdaType(
       *this, Intro, ParamInfo, getCurScope(), TypeLoc, ExplicitResultType);
 
   LSI->ExplicitParams = ParamInfo.getNumTypeObjects() != 0;
 
   if (ParamInfo.isFunctionDeclarator() != 0 &&
       !FTIHasSingleVoidParameter(ParamInfo.getFunctionTypeInfo())) {
     const auto &FTI = ParamInfo.getFunctionTypeInfo();
     Params.reserve(Params.size());
     for (unsigned I = 0; I < FTI.NumParams; ++I) {
       auto *Param = cast<ParmVarDecl>(FTI.Params[I].Param);
       Param->setScopeInfo(0, Params.size());
       Params.push_back(Param);
     }
   }
 
   bool IsLambdaStatic =
       ParamInfo.getDeclSpec().getStorageClassSpec() == DeclSpec::SCS_static;
 
   CompleteLambdaCallOperator(
       Method, Intro.Range.getBegin(), CallOperatorLoc,
       ParamInfo.getTrailingRequiresClause(), MethodTyInfo,
       ParamInfo.getDeclSpec().getConstexprSpecifier(),
       IsLambdaStatic ? SC_Static : SC_None, Params, ExplicitResultType);
 
   CheckCXXDefaultArguments(Method);
 
   // This represents the function body for the lambda function, check if we
   // have to apply optnone due to a pragma.
   AddRangeBasedOptnone(Method);
 
   // code_seg attribute on lambda apply to the method.
   if (Attr *A = getImplicitCodeSegOrSectionAttrForFunction(
           Method, /*IsDefinition=*/true))
     Method->addAttr(A);
 
   // Attributes on the lambda apply to the method.
   ProcessDeclAttributes(CurScope, Method, ParamInfo);
 
   // CUDA lambdas get implicit host and device attributes.
   if (getLangOpts().CUDA)
     CUDASetLambdaAttrs(Method);
 
   // OpenMP lambdas might get assumumption attributes.
   if (LangOpts.OpenMP)
     ActOnFinishedFunctionDefinitionInOpenMPAssumeScope(Method);
 
   handleLambdaNumbering(Class, Method);
 
   for (auto &&C : LSI->Captures) {
     if (!C.isVariableCapture())
       continue;
     ValueDecl *Var = C.getVariable();
     if (Var && Var->isInitCapture()) {
       PushOnScopeChains(Var, CurScope, false);
     }
   }
 
   auto CheckRedefinition = [&](ParmVarDecl *Param) {
     for (const auto &Capture : Intro.Captures) {
       if (Capture.Id == Param->getIdentifier()) {
         Diag(Param->getLocation(), diag::err_parameter_shadow_capture);
         Diag(Capture.Loc, diag::note_var_explicitly_captured_here)
             << Capture.Id << true;
         return false;
       }
     }
     return true;
   };
 
   for (ParmVarDecl *P : Params) {
     if (!P->getIdentifier())
       continue;
     if (CheckRedefinition(P))
       CheckShadow(CurScope, P);
     PushOnScopeChains(P, CurScope);
   }
 
   // C++23 [expr.prim.lambda.capture]p5:
   // If an identifier in a capture appears as the declarator-id of a parameter
   // of the lambda-declarator's parameter-declaration-clause or as the name of a
   // template parameter of the lambda-expression's template-parameter-list, the
   // program is ill-formed.
   TemplateParameterList *TemplateParams =
       getGenericLambdaTemplateParameterList(LSI, *this);
   if (TemplateParams) {
     for (const auto *TP : TemplateParams->asArray()) {
       if (!TP->getIdentifier())
         continue;
       for (const auto &Capture : Intro.Captures) {
         if (Capture.Id == TP->getIdentifier()) {
           Diag(Capture.Loc, diag::err_template_param_shadow) << Capture.Id;
           Diag(TP->getLocation(), diag::note_template_param_here);
         }
       }
     }
   }
 
   // C++20: dcl.decl.general p4:
   // The optional requires-clause ([temp.pre]) in an init-declarator or
   // member-declarator shall be present only if the declarator declares a
   // templated function ([dcl.fct]).
   if (Expr *TRC = Method->getTrailingRequiresClause()) {
     // [temp.pre]/8:
     // An entity is templated if it is
     // - a template,
     // - an entity defined ([basic.def]) or created ([class.temporary]) in a
     // templated entity,
     // - a member of a templated entity,
     // - an enumerator for an enumeration that is a templated entity, or
     // - the closure type of a lambda-expression ([expr.prim.lambda.closure])
     // appearing in the declaration of a templated entity. [Note 6: A local
     // class, a local or block variable, or a friend function defined in a
     // templated entity is a templated entity.  — end note]
     //
     // A templated function is a function template or a function that is
     // templated. A templated class is a class template or a class that is
     // templated. A templated variable is a variable template or a variable
     // that is templated.
 
     // Note: we only have to check if this is defined in a template entity, OR
     // if we are a template, since the rest don't apply. The requires clause
     // applies to the call operator, which we already know is a member function,
     // AND defined.
     if (!Method->getDescribedFunctionTemplate() && !Method->isTemplated()) {
       Diag(TRC->getBeginLoc(), diag::err_constrained_non_templated_function);
     }
   }
 
   // Enter a new evaluation context to insulate the lambda from any
   // cleanups from the enclosing full-expression.
   PushExpressionEvaluationContext(
       LSI->CallOperator->isConsteval()
           ? ExpressionEvaluationContext::ImmediateFunctionContext
           : ExpressionEvaluationContext::PotentiallyEvaluated);
   ExprEvalContexts.back().InImmediateFunctionContext =
       LSI->CallOperator->isConsteval();
   ExprEvalContexts.back().InImmediateEscalatingFunctionContext =
       getLangOpts().CPlusPlus20 && LSI->CallOperator->isImmediateEscalating();
 }
 
 void Sema::ActOnLambdaError(SourceLocation StartLoc, Scope *CurScope,
                             bool IsInstantiation) {
   LambdaScopeInfo *LSI = cast<LambdaScopeInfo>(FunctionScopes.back());
 
   // Leave the expression-evaluation context.
   DiscardCleanupsInEvaluationContext();
   PopExpressionEvaluationContext();
 
   // Leave the context of the lambda.
   if (!IsInstantiation)
     PopDeclContext();
 
   // Finalize the lambda.
   CXXRecordDecl *Class = LSI->Lambda;
   Class->setInvalidDecl();
   SmallVector<Decl*, 4> Fields(Class->fields());
   ActOnFields(nullptr, Class->getLocation(), Class, Fields, SourceLocation(),
               SourceLocation(), ParsedAttributesView());
   CheckCompletedCXXClass(nullptr, Class);
 
   PopFunctionScopeInfo();
 }
 
 template <typename Func>
 static void repeatForLambdaConversionFunctionCallingConvs(
     Sema &S, const FunctionProtoType &CallOpProto, Func F) {
   CallingConv DefaultFree = S.Context.getDefaultCallingConvention(
       CallOpProto.isVariadic(), /*IsCXXMethod=*/false);
   CallingConv DefaultMember = S.Context.getDefaultCallingConvention(
       CallOpProto.isVariadic(), /*IsCXXMethod=*/true);
   CallingConv CallOpCC = CallOpProto.getCallConv();
 
   /// Implement emitting a version of the operator for many of the calling
   /// conventions for MSVC, as described here:
   /// https://devblogs.microsoft.com/oldnewthing/20150220-00/?p=44623.
   /// Experimentally, we determined that cdecl, stdcall, fastcall, and
   /// vectorcall are generated by MSVC when it is supported by the target.
   /// Additionally, we are ensuring that the default-free/default-member and
   /// call-operator calling convention are generated as well.
   /// NOTE: We intentionally generate a 'thiscall' on Win32 implicitly from the
   /// 'member default', despite MSVC not doing so. We do this in order to ensure
   /// that someone who intentionally places 'thiscall' on the lambda call
   /// operator will still get that overload, since we don't have the a way of
   /// detecting the attribute by the time we get here.
   if (S.getLangOpts().MSVCCompat) {
     CallingConv Convs[] = {
         CC_C,        CC_X86StdCall, CC_X86FastCall, CC_X86VectorCall,
         DefaultFree, DefaultMember, CallOpCC};
     llvm::sort(Convs);
     llvm::iterator_range<CallingConv *> Range(
         std::begin(Convs), std::unique(std::begin(Convs), std::end(Convs)));
     const TargetInfo &TI = S.getASTContext().getTargetInfo();
 
     for (CallingConv C : Range) {
       if (TI.checkCallingConvention(C) == TargetInfo::CCCR_OK)
         F(C);
     }
     return;
   }
 
   if (CallOpCC == DefaultMember && DefaultMember != DefaultFree) {
     F(DefaultFree);
     F(DefaultMember);
   } else {
     F(CallOpCC);
   }
 }
 
 // Returns the 'standard' calling convention to be used for the lambda
 // conversion function, that is, the 'free' function calling convention unless
 // it is overridden by a non-default calling convention attribute.
 static CallingConv
 getLambdaConversionFunctionCallConv(Sema &S,
                                     const FunctionProtoType *CallOpProto) {
   CallingConv DefaultFree = S.Context.getDefaultCallingConvention(
       CallOpProto->isVariadic(), /*IsCXXMethod=*/false);
   CallingConv DefaultMember = S.Context.getDefaultCallingConvention(
       CallOpProto->isVariadic(), /*IsCXXMethod=*/true);
   CallingConv CallOpCC = CallOpProto->getCallConv();
 
   // If the call-operator hasn't been changed, return both the 'free' and
   // 'member' function calling convention.
   if (CallOpCC == DefaultMember && DefaultMember != DefaultFree)
     return DefaultFree;
   return CallOpCC;
 }
 
 QualType Sema::getLambdaConversionFunctionResultType(
     const FunctionProtoType *CallOpProto, CallingConv CC) {
   const FunctionProtoType::ExtProtoInfo CallOpExtInfo =
       CallOpProto->getExtProtoInfo();
   FunctionProtoType::ExtProtoInfo InvokerExtInfo = CallOpExtInfo;
   InvokerExtInfo.ExtInfo = InvokerExtInfo.ExtInfo.withCallingConv(CC);
   InvokerExtInfo.TypeQuals = Qualifiers();
   assert(InvokerExtInfo.RefQualifier == RQ_None &&
          "Lambda's call operator should not have a reference qualifier");
   return Context.getFunctionType(CallOpProto->getReturnType(),
                                  CallOpProto->getParamTypes(), InvokerExtInfo);
 }
 
 /// Add a lambda's conversion to function pointer, as described in
 /// C++11 [expr.prim.lambda]p6.
 static void addFunctionPointerConversion(Sema &S, SourceRange IntroducerRange,
                                          CXXRecordDecl *Class,
                                          CXXMethodDecl *CallOperator,
                                          QualType InvokerFunctionTy) {
   // This conversion is explicitly disabled if the lambda's function has
   // pass_object_size attributes on any of its parameters.
   auto HasPassObjectSizeAttr = [](const ParmVarDecl *P) {
     return P->hasAttr<PassObjectSizeAttr>();
   };
   if (llvm::any_of(CallOperator->parameters(), HasPassObjectSizeAttr))
     return;
 
   // Add the conversion to function pointer.
   QualType PtrToFunctionTy = S.Context.getPointerType(InvokerFunctionTy);
 
   // Create the type of the conversion function.
   FunctionProtoType::ExtProtoInfo ConvExtInfo(
       S.Context.getDefaultCallingConvention(
       /*IsVariadic=*/false, /*IsCXXMethod=*/true));
   // The conversion function is always const and noexcept.
   ConvExtInfo.TypeQuals = Qualifiers();
   ConvExtInfo.TypeQuals.addConst();
   ConvExtInfo.ExceptionSpec.Type = EST_BasicNoexcept;
   QualType ConvTy =
       S.Context.getFunctionType(PtrToFunctionTy, std::nullopt, ConvExtInfo);
 
   SourceLocation Loc = IntroducerRange.getBegin();
   DeclarationName ConversionName
     = S.Context.DeclarationNames.getCXXConversionFunctionName(
         S.Context.getCanonicalType(PtrToFunctionTy));
   // Construct a TypeSourceInfo for the conversion function, and wire
   // all the parameters appropriately for the FunctionProtoTypeLoc
   // so that everything works during transformation/instantiation of
   // generic lambdas.
   // The main reason for wiring up the parameters of the conversion
   // function with that of the call operator is so that constructs
   // like the following work:
   // auto L = [](auto b) {                <-- 1
   //   return [](auto a) -> decltype(a) { <-- 2
   //      return a;
   //   };
   // };
   // int (*fp)(int) = L(5);
   // Because the trailing return type can contain DeclRefExprs that refer
   // to the original call operator's variables, we hijack the call
   // operators ParmVarDecls below.
   TypeSourceInfo *ConvNamePtrToFunctionTSI =
       S.Context.getTrivialTypeSourceInfo(PtrToFunctionTy, Loc);
   DeclarationNameLoc ConvNameLoc =
       DeclarationNameLoc::makeNamedTypeLoc(ConvNamePtrToFunctionTSI);
 
   // The conversion function is a conversion to a pointer-to-function.
   TypeSourceInfo *ConvTSI = S.Context.getTrivialTypeSourceInfo(ConvTy, Loc);
   FunctionProtoTypeLoc ConvTL =
       ConvTSI->getTypeLoc().getAs<FunctionProtoTypeLoc>();
   // Get the result of the conversion function which is a pointer-to-function.
   PointerTypeLoc PtrToFunctionTL =
       ConvTL.getReturnLoc().getAs<PointerTypeLoc>();
   // Do the same for the TypeSourceInfo that is used to name the conversion
   // operator.
   PointerTypeLoc ConvNamePtrToFunctionTL =
       ConvNamePtrToFunctionTSI->getTypeLoc().getAs<PointerTypeLoc>();
 
   // Get the underlying function types that the conversion function will
   // be converting to (should match the type of the call operator).
   FunctionProtoTypeLoc CallOpConvTL =
       PtrToFunctionTL.getPointeeLoc().getAs<FunctionProtoTypeLoc>();
   FunctionProtoTypeLoc CallOpConvNameTL =
     ConvNamePtrToFunctionTL.getPointeeLoc().getAs<FunctionProtoTypeLoc>();
 
   // Wire up the FunctionProtoTypeLocs with the call operator's parameters.
   // These parameter's are essentially used to transform the name and
   // the type of the conversion operator.  By using the same parameters
   // as the call operator's we don't have to fix any back references that
   // the trailing return type of the call operator's uses (such as
   // decltype(some_type<decltype(a)>::type{} + decltype(a){}) etc.)
   // - we can simply use the return type of the call operator, and
   // everything should work.
   SmallVector<ParmVarDecl *, 4> InvokerParams;
   for (unsigned I = 0, N = CallOperator->getNumParams(); I != N; ++I) {
     ParmVarDecl *From = CallOperator->getParamDecl(I);
 
     InvokerParams.push_back(ParmVarDecl::Create(
         S.Context,
         // Temporarily add to the TU. This is set to the invoker below.
         S.Context.getTranslationUnitDecl(), From->getBeginLoc(),
         From->getLocation(), From->getIdentifier(), From->getType(),
         From->getTypeSourceInfo(), From->getStorageClass(),
         /*DefArg=*/nullptr));
     CallOpConvTL.setParam(I, From);
     CallOpConvNameTL.setParam(I, From);
   }
 
   CXXConversionDecl *Conversion = CXXConversionDecl::Create(
       S.Context, Class, Loc,
       DeclarationNameInfo(ConversionName, Loc, ConvNameLoc), ConvTy, ConvTSI,
       S.getCurFPFeatures().isFPConstrained(),
       /*isInline=*/true, ExplicitSpecifier(),
       S.getLangOpts().CPlusPlus17 ? ConstexprSpecKind::Constexpr
                                   : ConstexprSpecKind::Unspecified,
       CallOperator->getBody()->getEndLoc());
   Conversion->setAccess(AS_public);
   Conversion->setImplicit(true);
 
   // A non-generic lambda may still be a templated entity. We need to preserve
   // constraints when converting the lambda to a function pointer. See GH63181.
   if (Expr *Requires = CallOperator->getTrailingRequiresClause())
     Conversion->setTrailingRequiresClause(Requires);
 
   if (Class->isGenericLambda()) {
     // Create a template version of the conversion operator, using the template
     // parameter list of the function call operator.
     FunctionTemplateDecl *TemplateCallOperator =
             CallOperator->getDescribedFunctionTemplate();
     FunctionTemplateDecl *ConversionTemplate =
                   FunctionTemplateDecl::Create(S.Context, Class,
                                       Loc, ConversionName,
                                       TemplateCallOperator->getTemplateParameters(),
                                       Conversion);
     ConversionTemplate->setAccess(AS_public);
     ConversionTemplate->setImplicit(true);
     Conversion->setDescribedFunctionTemplate(ConversionTemplate);
     Class->addDecl(ConversionTemplate);
   } else
     Class->addDecl(Conversion);
 
   // If the lambda is not static, we need to add a static member
   // function that will be the result of the conversion with a
   // certain unique ID.
   // When it is static we just return the static call operator instead.
   if (CallOperator->isInstance()) {
     DeclarationName InvokerName =
         &S.Context.Idents.get(getLambdaStaticInvokerName());
     // FIXME: Instead of passing in the CallOperator->getTypeSourceInfo()
     // we should get a prebuilt TrivialTypeSourceInfo from Context
     // using FunctionTy & Loc and get its TypeLoc as a FunctionProtoTypeLoc
     // then rewire the parameters accordingly, by hoisting up the InvokeParams
     // loop below and then use its Params to set Invoke->setParams(...) below.
     // This would avoid the 'const' qualifier of the calloperator from
     // contaminating the type of the invoker, which is currently adjusted
     // in SemaTemplateDeduction.cpp:DeduceTemplateArguments.  Fixing the
     // trailing return type of the invoker would require a visitor to rebuild
     // the trailing return type and adjusting all back DeclRefExpr's to refer
     // to the new static invoker parameters - not the call operator's.
     CXXMethodDecl *Invoke = CXXMethodDecl::Create(
         S.Context, Class, Loc, DeclarationNameInfo(InvokerName, Loc),
         InvokerFunctionTy, CallOperator->getTypeSourceInfo(), SC_Static,
         S.getCurFPFeatures().isFPConstrained(),
         /*isInline=*/true, CallOperator->getConstexprKind(),
         CallOperator->getBody()->getEndLoc());
     for (unsigned I = 0, N = CallOperator->getNumParams(); I != N; ++I)
       InvokerParams[I]->setOwningFunction(Invoke);
     Invoke->setParams(InvokerParams);
     Invoke->setAccess(AS_private);
     Invoke->setImplicit(true);
     if (Class->isGenericLambda()) {
       FunctionTemplateDecl *TemplateCallOperator =
           CallOperator->getDescribedFunctionTemplate();
       FunctionTemplateDecl *StaticInvokerTemplate =
           FunctionTemplateDecl::Create(
               S.Context, Class, Loc, InvokerName,
               TemplateCallOperator->getTemplateParameters(), Invoke);
       StaticInvokerTemplate->setAccess(AS_private);
       StaticInvokerTemplate->setImplicit(true);
       Invoke->setDescribedFunctionTemplate(StaticInvokerTemplate);
       Class->addDecl(StaticInvokerTemplate);
     } else
       Class->addDecl(Invoke);
   }
 }
 
 /// Add a lambda's conversion to function pointers, as described in
 /// C++11 [expr.prim.lambda]p6. Note that in most cases, this should emit only a
 /// single pointer conversion. In the event that the default calling convention
 /// for free and member functions is different, it will emit both conventions.
 static void addFunctionPointerConversions(Sema &S, SourceRange IntroducerRange,
                                           CXXRecordDecl *Class,
                                           CXXMethodDecl *CallOperator) {
   const FunctionProtoType *CallOpProto =
       CallOperator->getType()->castAs<FunctionProtoType>();
 
   repeatForLambdaConversionFunctionCallingConvs(
       S, *CallOpProto, [&](CallingConv CC) {
         QualType InvokerFunctionTy =
             S.getLambdaConversionFunctionResultType(CallOpProto, CC);
         addFunctionPointerConversion(S, IntroducerRange, Class, CallOperator,
                                      InvokerFunctionTy);
       });
 }
 
 /// Add a lambda's conversion to block pointer.
 static void addBlockPointerConversion(Sema &S,
                                       SourceRange IntroducerRange,
                                       CXXRecordDecl *Class,
                                       CXXMethodDecl *CallOperator) {
   const FunctionProtoType *CallOpProto =
       CallOperator->getType()->castAs<FunctionProtoType>();
   QualType FunctionTy = S.getLambdaConversionFunctionResultType(
       CallOpProto, getLambdaConversionFunctionCallConv(S, CallOpProto));
   QualType BlockPtrTy = S.Context.getBlockPointerType(FunctionTy);
 
   FunctionProtoType::ExtProtoInfo ConversionEPI(
       S.Context.getDefaultCallingConvention(
           /*IsVariadic=*/false, /*IsCXXMethod=*/true));
   ConversionEPI.TypeQuals = Qualifiers();
   ConversionEPI.TypeQuals.addConst();
   QualType ConvTy =
       S.Context.getFunctionType(BlockPtrTy, std::nullopt, ConversionEPI);
 
   SourceLocation Loc = IntroducerRange.getBegin();
   DeclarationName Name
     = S.Context.DeclarationNames.getCXXConversionFunctionName(
         S.Context.getCanonicalType(BlockPtrTy));
   DeclarationNameLoc NameLoc = DeclarationNameLoc::makeNamedTypeLoc(
       S.Context.getTrivialTypeSourceInfo(BlockPtrTy, Loc));
   CXXConversionDecl *Conversion = CXXConversionDecl::Create(
       S.Context, Class, Loc, DeclarationNameInfo(Name, Loc, NameLoc), ConvTy,
       S.Context.getTrivialTypeSourceInfo(ConvTy, Loc),
       S.getCurFPFeatures().isFPConstrained(),
       /*isInline=*/true, ExplicitSpecifier(), ConstexprSpecKind::Unspecified,
       CallOperator->getBody()->getEndLoc());
   Conversion->setAccess(AS_public);
   Conversion->setImplicit(true);
   Class->addDecl(Conversion);
 }
 
 ExprResult Sema::BuildCaptureInit(const Capture &Cap,
                                   SourceLocation ImplicitCaptureLoc,
                                   bool IsOpenMPMapping) {
   // VLA captures don't have a stored initialization expression.
   if (Cap.isVLATypeCapture())
     return ExprResult();
 
   // An init-capture is initialized directly from its stored initializer.
   if (Cap.isInitCapture())
     return cast<VarDecl>(Cap.getVariable())->getInit();
 
   // For anything else, build an initialization expression. For an implicit
   // capture, the capture notionally happens at the capture-default, so use
   // that location here.
   SourceLocation Loc =
       ImplicitCaptureLoc.isValid() ? ImplicitCaptureLoc : Cap.getLocation();
 
   // C++11 [expr.prim.lambda]p21:
   //   When the lambda-expression is evaluated, the entities that
   //   are captured by copy are used to direct-initialize each
   //   corresponding non-static data member of the resulting closure
   //   object. (For array members, the array elements are
   //   direct-initialized in increasing subscript order.) These
   //   initializations are performed in the (unspecified) order in
   //   which the non-static data members are declared.
 
   // C++ [expr.prim.lambda]p12:
   //   An entity captured by a lambda-expression is odr-used (3.2) in
   //   the scope containing the lambda-expression.
   ExprResult Init;
   IdentifierInfo *Name = nullptr;
   if (Cap.isThisCapture()) {
     QualType ThisTy = getCurrentThisType();
     Expr *This = BuildCXXThisExpr(Loc, ThisTy, ImplicitCaptureLoc.isValid());
     if (Cap.isCopyCapture())
       Init = CreateBuiltinUnaryOp(Loc, UO_Deref, This);
     else
       Init = This;
   } else {
     assert(Cap.isVariableCapture() && "unknown kind of capture");
     ValueDecl *Var = Cap.getVariable();
     Name = Var->getIdentifier();
     Init = BuildDeclarationNameExpr(
       CXXScopeSpec(), DeclarationNameInfo(Var->getDeclName(), Loc), Var);
   }
 
   // In OpenMP, the capture kind doesn't actually describe how to capture:
   // variables are "mapped" onto the device in a process that does not formally
   // make a copy, even for a "copy capture".
   if (IsOpenMPMapping)
     return Init;
 
   if (Init.isInvalid())
     return ExprError();
 
   Expr *InitExpr = Init.get();
   InitializedEntity Entity = InitializedEntity::InitializeLambdaCapture(
       Name, Cap.getCaptureType(), Loc);
   InitializationKind InitKind =
       InitializationKind::CreateDirect(Loc, Loc, Loc);
   InitializationSequence InitSeq(*this, Entity, InitKind, InitExpr);
   return InitSeq.Perform(*this, Entity, InitKind, InitExpr);
 }
 
 ExprResult Sema::ActOnLambdaExpr(SourceLocation StartLoc, Stmt *Body,
                                  Scope *CurScope) {
   LambdaScopeInfo LSI = *cast<LambdaScopeInfo>(FunctionScopes.back());
   ActOnFinishFunctionBody(LSI.CallOperator, Body);
   return BuildLambdaExpr(StartLoc, Body->getEndLoc(), &LSI);
 }
 
 static LambdaCaptureDefault
 mapImplicitCaptureStyle(CapturingScopeInfo::ImplicitCaptureStyle ICS) {
   switch (ICS) {
   case CapturingScopeInfo::ImpCap_None:
     return LCD_None;
   case CapturingScopeInfo::ImpCap_LambdaByval:
     return LCD_ByCopy;
   case CapturingScopeInfo::ImpCap_CapturedRegion:
   case CapturingScopeInfo::ImpCap_LambdaByref:
     return LCD_ByRef;
   case CapturingScopeInfo::ImpCap_Block:
     llvm_unreachable("block capture in lambda");
   }
   llvm_unreachable("Unknown implicit capture style");
 }
 
 bool Sema::CaptureHasSideEffects(const Capture &From) {
   if (From.isInitCapture()) {
     Expr *Init = cast<VarDecl>(From.getVariable())->getInit();
     if (Init && Init->HasSideEffects(Context))
       return true;
   }
 
   if (!From.isCopyCapture())
     return false;
 
   const QualType T = From.isThisCapture()
                          ? getCurrentThisType()->getPointeeType()
                          : From.getCaptureType();
 
   if (T.isVolatileQualified())
     return true;
 
   const Type *BaseT = T->getBaseElementTypeUnsafe();
   if (const CXXRecordDecl *RD = BaseT->getAsCXXRecordDecl())
     return !RD->isCompleteDefinition() || !RD->hasTrivialCopyConstructor() ||
            !RD->hasTrivialDestructor();
 
   return false;
 }
 
 bool Sema::DiagnoseUnusedLambdaCapture(SourceRange CaptureRange,
                                        const Capture &From) {
   if (CaptureHasSideEffects(From))
     return false;
 
   if (From.isVLATypeCapture())
     return false;
 
   auto diag = Diag(From.getLocation(), diag::warn_unused_lambda_capture);
   if (From.isThisCapture())
     diag << "'this'";
   else
     diag << From.getVariable();
   diag << From.isNonODRUsed();
   diag << FixItHint::CreateRemoval(CaptureRange);
   return true;
 }
 
 /// Create a field within the lambda class or captured statement record for the
 /// given capture.
 FieldDecl *Sema::BuildCaptureField(RecordDecl *RD,
                                    const sema::Capture &Capture) {
   SourceLocation Loc = Capture.getLocation();
   QualType FieldType = Capture.getCaptureType();
 
   TypeSourceInfo *TSI = nullptr;
   if (Capture.isVariableCapture()) {
     const auto *Var = dyn_cast_or_null<VarDecl>(Capture.getVariable());
     if (Var && Var->isInitCapture())
       TSI = Var->getTypeSourceInfo();
   }
 
   // FIXME: Should we really be doing this? A null TypeSourceInfo seems more
   // appropriate, at least for an implicit capture.
   if (!TSI)
     TSI = Context.getTrivialTypeSourceInfo(FieldType, Loc);
 
   // Build the non-static data member.
   FieldDecl *Field =
       FieldDecl::Create(Context, RD, /*StartLoc=*/Loc, /*IdLoc=*/Loc,
                         /*Id=*/nullptr, FieldType, TSI, /*BW=*/nullptr,
                         /*Mutable=*/false, ICIS_NoInit);
   // If the variable being captured has an invalid type, mark the class as
   // invalid as well.
   if (!FieldType->isDependentType()) {
     if (RequireCompleteSizedType(Loc, FieldType,
                                  diag::err_field_incomplete_or_sizeless)) {
       RD->setInvalidDecl();
       Field->setInvalidDecl();
     } else {
       NamedDecl *Def;
       FieldType->isIncompleteType(&Def);
       if (Def && Def->isInvalidDecl()) {
         RD->setInvalidDecl();
         Field->setInvalidDecl();
       }
     }
   }
   Field->setImplicit(true);
   Field->setAccess(AS_private);
   RD->addDecl(Field);
 
   if (Capture.isVLATypeCapture())
     Field->setCapturedVLAType(Capture.getCapturedVLAType());
 
   return Field;
 }
 
 ExprResult Sema::BuildLambdaExpr(SourceLocation StartLoc, SourceLocation EndLoc,
                                  LambdaScopeInfo *LSI) {
   // Collect information from the lambda scope.
   SmallVector<LambdaCapture, 4> Captures;
   SmallVector<Expr *, 4> CaptureInits;
   SourceLocation CaptureDefaultLoc = LSI->CaptureDefaultLoc;
   LambdaCaptureDefault CaptureDefault =
       mapImplicitCaptureStyle(LSI->ImpCaptureStyle);
   CXXRecordDecl *Class;
   CXXMethodDecl *CallOperator;
   SourceRange IntroducerRange;
   bool ExplicitParams;
   bool ExplicitResultType;
   CleanupInfo LambdaCleanup;
   bool ContainsUnexpandedParameterPack;
   bool IsGenericLambda;
   {
     CallOperator = LSI->CallOperator;
     Class = LSI->Lambda;
     IntroducerRange = LSI->IntroducerRange;
     ExplicitParams = LSI->ExplicitParams;
     ExplicitResultType = !LSI->HasImplicitReturnType;
     LambdaCleanup = LSI->Cleanup;
     ContainsUnexpandedParameterPack = LSI->ContainsUnexpandedParameterPack;
     IsGenericLambda = Class->isGenericLambda();
 
     CallOperator->setLexicalDeclContext(Class);
     Decl *TemplateOrNonTemplateCallOperatorDecl =
         CallOperator->getDescribedFunctionTemplate()
         ? CallOperator->getDescribedFunctionTemplate()
         : cast<Decl>(CallOperator);
 
     // FIXME: Is this really the best choice? Keeping the lexical decl context
     // set as CurContext seems more faithful to the source.
     TemplateOrNonTemplateCallOperatorDecl->setLexicalDeclContext(Class);
 
     PopExpressionEvaluationContext();
 
     // True if the current capture has a used capture or default before it.
     bool CurHasPreviousCapture = CaptureDefault != LCD_None;
     SourceLocation PrevCaptureLoc = CurHasPreviousCapture ?
         CaptureDefaultLoc : IntroducerRange.getBegin();
 
     for (unsigned I = 0, N = LSI->Captures.size(); I != N; ++I) {
       const Capture &From = LSI->Captures[I];
 
       if (From.isInvalid())
         return ExprError();
 
       assert(!From.isBlockCapture() && "Cannot capture __block variables");
       bool IsImplicit = I >= LSI->NumExplicitCaptures;
       SourceLocation ImplicitCaptureLoc =
           IsImplicit ? CaptureDefaultLoc : SourceLocation();
 
       // Use source ranges of explicit captures for fixits where available.
       SourceRange CaptureRange = LSI->ExplicitCaptureRanges[I];
 
       // Warn about unused explicit captures.
       bool IsCaptureUsed = true;
       if (!CurContext->isDependentContext() && !IsImplicit &&
           !From.isODRUsed()) {
         // Initialized captures that are non-ODR used may not be eliminated.
         // FIXME: Where did the IsGenericLambda here come from?
         bool NonODRUsedInitCapture =
             IsGenericLambda && From.isNonODRUsed() && From.isInitCapture();
         if (!NonODRUsedInitCapture) {
           bool IsLast = (I + 1) == LSI->NumExplicitCaptures;
           SourceRange FixItRange;
           if (CaptureRange.isValid()) {
             if (!CurHasPreviousCapture && !IsLast) {
               // If there are no captures preceding this capture, remove the
               // following comma.
               FixItRange = SourceRange(CaptureRange.getBegin(),
                                        getLocForEndOfToken(CaptureRange.getEnd()));
             } else {
               // Otherwise, remove the comma since the last used capture.
               FixItRange = SourceRange(getLocForEndOfToken(PrevCaptureLoc),
                                        CaptureRange.getEnd());
             }
           }
 
           IsCaptureUsed = !DiagnoseUnusedLambdaCapture(FixItRange, From);
         }
       }
 
       if (CaptureRange.isValid()) {
         CurHasPreviousCapture |= IsCaptureUsed;
         PrevCaptureLoc = CaptureRange.getEnd();
       }
 
       // Map the capture to our AST representation.
       LambdaCapture Capture = [&] {
         if (From.isThisCapture()) {
           // Capturing 'this' implicitly with a default of '[=]' is deprecated,
           // because it results in a reference capture. Don't warn prior to
           // C++2a; there's nothing that can be done about it before then.
           if (getLangOpts().CPlusPlus20 && IsImplicit &&
               CaptureDefault == LCD_ByCopy) {
             Diag(From.getLocation(), diag::warn_deprecated_this_capture);
             Diag(CaptureDefaultLoc, diag::note_deprecated_this_capture)
                 << FixItHint::CreateInsertion(
                        getLocForEndOfToken(CaptureDefaultLoc), ", this");
           }
           return LambdaCapture(From.getLocation(), IsImplicit,
                                From.isCopyCapture() ? LCK_StarThis : LCK_This);
         } else if (From.isVLATypeCapture()) {
           return LambdaCapture(From.getLocation(), IsImplicit, LCK_VLAType);
         } else {
           assert(From.isVariableCapture() && "unknown kind of capture");
           ValueDecl *Var = From.getVariable();
           LambdaCaptureKind Kind =
               From.isCopyCapture() ? LCK_ByCopy : LCK_ByRef;
           return LambdaCapture(From.getLocation(), IsImplicit, Kind, Var,
                                From.getEllipsisLoc());
         }
       }();
 
       // Form the initializer for the capture field.
       ExprResult Init = BuildCaptureInit(From, ImplicitCaptureLoc);
 
       // FIXME: Skip this capture if the capture is not used, the initializer
       // has no side-effects, the type of the capture is trivial, and the
       // lambda is not externally visible.
 
       // Add a FieldDecl for the capture and form its initializer.
       BuildCaptureField(Class, From);
       Captures.push_back(Capture);
       CaptureInits.push_back(Init.get());
 
       if (LangOpts.CUDA)
         CUDACheckLambdaCapture(CallOperator, From);
     }
 
     Class->setCaptures(Context, Captures);
 
     // C++11 [expr.prim.lambda]p6:
     //   The closure type for a lambda-expression with no lambda-capture
     //   has a public non-virtual non-explicit const conversion function
     //   to pointer to function having the same parameter and return
     //   types as the closure type's function call operator.
     if (Captures.empty() && CaptureDefault == LCD_None)
       addFunctionPointerConversions(*this, IntroducerRange, Class,
                                     CallOperator);
 
     // Objective-C++:
     //   The closure type for a lambda-expression has a public non-virtual
     //   non-explicit const conversion function to a block pointer having the
     //   same parameter and return types as the closure type's function call
     //   operator.
     // FIXME: Fix generic lambda to block conversions.
     if (getLangOpts().Blocks && getLangOpts().ObjC && !IsGenericLambda)
       addBlockPointerConversion(*this, IntroducerRange, Class, CallOperator);
 
     // Finalize the lambda class.
     SmallVector<Decl*, 4> Fields(Class->fields());
     ActOnFields(nullptr, Class->getLocation(), Class, Fields, SourceLocation(),
                 SourceLocation(), ParsedAttributesView());
     CheckCompletedCXXClass(nullptr, Class);
   }
 
   Cleanup.mergeFrom(LambdaCleanup);
 
   LambdaExpr *Lambda = LambdaExpr::Create(Context, Class, IntroducerRange,
                                           CaptureDefault, CaptureDefaultLoc,
                                           ExplicitParams, ExplicitResultType,
                                           CaptureInits, EndLoc,
                                           ContainsUnexpandedParameterPack);
   // If the lambda expression's call operator is not explicitly marked constexpr
   // and we are not in a dependent context, analyze the call operator to infer
   // its constexpr-ness, suppressing diagnostics while doing so.
   if (getLangOpts().CPlusPlus17 && !CallOperator->isInvalidDecl() &&
       !CallOperator->isConstexpr() &&
       !isa<CoroutineBodyStmt>(CallOperator->getBody()) &&
       !Class->getDeclContext()->isDependentContext()) {
     CallOperator->setConstexprKind(
         CheckConstexprFunctionDefinition(CallOperator,
                                          CheckConstexprKind::CheckValid)
             ? ConstexprSpecKind::Constexpr
             : ConstexprSpecKind::Unspecified);
   }
 
   // Emit delayed shadowing warnings now that the full capture list is known.
   DiagnoseShadowingLambdaDecls(LSI);
 
   if (!CurContext->isDependentContext()) {
     switch (ExprEvalContexts.back().Context) {
     // C++11 [expr.prim.lambda]p2:
     //   A lambda-expression shall not appear in an unevaluated operand
     //   (Clause 5).
     case ExpressionEvaluationContext::Unevaluated:
     case ExpressionEvaluationContext::UnevaluatedList:
     case ExpressionEvaluationContext::UnevaluatedAbstract:
     // C++1y [expr.const]p2:
     //   A conditional-expression e is a core constant expression unless the
     //   evaluation of e, following the rules of the abstract machine, would
     //   evaluate [...] a lambda-expression.
     //
     // This is technically incorrect, there are some constant evaluated contexts
     // where this should be allowed.  We should probably fix this when DR1607 is
     // ratified, it lays out the exact set of conditions where we shouldn't
     // allow a lambda-expression.
     case ExpressionEvaluationContext::ConstantEvaluated:
     case ExpressionEvaluationContext::ImmediateFunctionContext:
       // We don't actually diagnose this case immediately, because we
       // could be within a context where we might find out later that
       // the expression is potentially evaluated (e.g., for typeid).
       ExprEvalContexts.back().Lambdas.push_back(Lambda);
       break;
 
     case ExpressionEvaluationContext::DiscardedStatement:
     case ExpressionEvaluationContext::PotentiallyEvaluated:
     case ExpressionEvaluationContext::PotentiallyEvaluatedIfUsed:
       break;
     }
   }
 
   return MaybeBindToTemporary(Lambda);
 }
 
 ExprResult Sema::BuildBlockForLambdaConversion(SourceLocation CurrentLocation,
                                                SourceLocation ConvLocation,
                                                CXXConversionDecl *Conv,
                                                Expr *Src) {
   // Make sure that the lambda call operator is marked used.
   CXXRecordDecl *Lambda = Conv->getParent();
   CXXMethodDecl *CallOperator
     = cast<CXXMethodDecl>(
         Lambda->lookup(
           Context.DeclarationNames.getCXXOperatorName(OO_Call)).front());
   CallOperator->setReferenced();
   CallOperator->markUsed(Context);
 
   ExprResult Init = PerformCopyInitialization(
       InitializedEntity::InitializeLambdaToBlock(ConvLocation, Src->getType()),
       CurrentLocation, Src);
   if (!Init.isInvalid())
     Init = ActOnFinishFullExpr(Init.get(), /*DiscardedValue*/ false);
 
   if (Init.isInvalid())
     return ExprError();
 
   // Create the new block to be returned.
   BlockDecl *Block = BlockDecl::Create(Context, CurContext, ConvLocation);
 
   // Set the type information.
   Block->setSignatureAsWritten(CallOperator->getTypeSourceInfo());
   Block->setIsVariadic(CallOperator->isVariadic());
   Block->setBlockMissingReturnType(false);
 
   // Add parameters.
   SmallVector<ParmVarDecl *, 4> BlockParams;
   for (unsigned I = 0, N = CallOperator->getNumParams(); I != N; ++I) {
     ParmVarDecl *From = CallOperator->getParamDecl(I);
     BlockParams.push_back(ParmVarDecl::Create(
         Context, Block, From->getBeginLoc(), From->getLocation(),
         From->getIdentifier(), From->getType(), From->getTypeSourceInfo(),
         From->getStorageClass(),
         /*DefArg=*/nullptr));
   }
   Block->setParams(BlockParams);
 
   Block->setIsConversionFromLambda(true);
 
   // Add capture. The capture uses a fake variable, which doesn't correspond
   // to any actual memory location. However, the initializer copy-initializes
   // the lambda object.
   TypeSourceInfo *CapVarTSI =
       Context.getTrivialTypeSourceInfo(Src->getType());
   VarDecl *CapVar = VarDecl::Create(Context, Block, ConvLocation,
                                     ConvLocation, nullptr,
                                     Src->getType(), CapVarTSI,
                                     SC_None);
   BlockDecl::Capture Capture(/*variable=*/CapVar, /*byRef=*/false,
                              /*nested=*/false, /*copy=*/Init.get());
   Block->setCaptures(Context, Capture, /*CapturesCXXThis=*/false);
 
   // Add a fake function body to the block. IR generation is responsible
   // for filling in the actual body, which cannot be expressed as an AST.
   Block->setBody(new (Context) CompoundStmt(ConvLocation));
 
   // Create the block literal expression.
   Expr *BuildBlock = new (Context) BlockExpr(Block, Conv->getConversionType());
   ExprCleanupObjects.push_back(Block);
   Cleanup.setExprNeedsCleanups(true);
 
   return BuildBlock;
 }
+
+Sema::LambdaScopeForCallOperatorInstantiationRAII::
+    LambdaScopeForCallOperatorInstantiationRAII(
+        Sema &SemasRef, FunctionDecl *FD, MultiLevelTemplateArgumentList MLTAL,
+        LocalInstantiationScope &Scope)
+    : FunctionScopeRAII(SemasRef) {
+  if (!isLambdaCallOperator(FD)) {
+    FunctionScopeRAII::disable();
+    return;
+  }
+
+  if (FD->isTemplateInstantiation() && FD->getPrimaryTemplate()) {
+    FunctionTemplateDecl *PrimaryTemplate = FD->getPrimaryTemplate();
+    if (const auto *FromMemTempl =
+            PrimaryTemplate->getInstantiatedFromMemberTemplate()) {
+      SemasRef.addInstantiatedCapturesToScope(
+          FD, FromMemTempl->getTemplatedDecl(), Scope, MLTAL);
+    }
+  }
+
+  else if (FD->getTemplatedKind() == FunctionDecl::TK_MemberSpecialization ||
+           FD->getTemplatedKind() == FunctionDecl::TK_DependentNonTemplate) {
+    FunctionDecl *InstantiatedFrom =
+        FD->getTemplatedKind() == FunctionDecl::TK_MemberSpecialization
+            ? FD->getInstantiatedFromMemberFunction()
+            : FD->getInstantiatedFromDecl();
+    SemasRef.addInstantiatedCapturesToScope(FD, InstantiatedFrom, Scope, MLTAL);
+  }
+
+  SemasRef.RebuildLambdaScopeInfo(cast<CXXMethodDecl>(FD));
+}
diff --git a/contrib/llvm-project/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/contrib/llvm-project/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index f78d46f59503..332004055b58 100644
--- a/contrib/llvm-project/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/contrib/llvm-project/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -1,6447 +1,6450 @@
 //===--- SemaTemplateInstantiateDecl.cpp - C++ Template Decl Instantiation ===/
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //===----------------------------------------------------------------------===/
 //
 //  This file implements C++ template instantiation for declarations.
 //
 //===----------------------------------------------------------------------===/
 
 #include "TreeTransform.h"
 #include "clang/AST/ASTConsumer.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/ASTMutationListener.h"
 #include "clang/AST/DeclTemplate.h"
 #include "clang/AST/DeclVisitor.h"
 #include "clang/AST/DependentDiagnostic.h"
 #include "clang/AST/Expr.h"
 #include "clang/AST/ExprCXX.h"
 #include "clang/AST/PrettyDeclStackTrace.h"
 #include "clang/AST/TypeLoc.h"
 #include "clang/Basic/SourceManager.h"
 #include "clang/Basic/TargetInfo.h"
 #include "clang/Sema/EnterExpressionEvaluationContext.h"
 #include "clang/Sema/Initialization.h"
 #include "clang/Sema/Lookup.h"
 #include "clang/Sema/ScopeInfo.h"
 #include "clang/Sema/SemaInternal.h"
 #include "clang/Sema/Template.h"
 #include "clang/Sema/TemplateInstCallback.h"
 #include "llvm/Support/TimeProfiler.h"
 #include <optional>
 
 using namespace clang;
 
 static bool isDeclWithinFunction(const Decl *D) {
   const DeclContext *DC = D->getDeclContext();
   if (DC->isFunctionOrMethod())
     return true;
 
   if (DC->isRecord())
     return cast<CXXRecordDecl>(DC)->isLocalClass();
 
   return false;
 }
 
 template<typename DeclT>
 static bool SubstQualifier(Sema &SemaRef, const DeclT *OldDecl, DeclT *NewDecl,
                            const MultiLevelTemplateArgumentList &TemplateArgs) {
   if (!OldDecl->getQualifierLoc())
     return false;
 
   assert((NewDecl->getFriendObjectKind() ||
           !OldDecl->getLexicalDeclContext()->isDependentContext()) &&
          "non-friend with qualified name defined in dependent context");
   Sema::ContextRAII SavedContext(
       SemaRef,
       const_cast<DeclContext *>(NewDecl->getFriendObjectKind()
                                     ? NewDecl->getLexicalDeclContext()
                                     : OldDecl->getLexicalDeclContext()));
 
   NestedNameSpecifierLoc NewQualifierLoc
       = SemaRef.SubstNestedNameSpecifierLoc(OldDecl->getQualifierLoc(),
                                             TemplateArgs);
 
   if (!NewQualifierLoc)
     return true;
 
   NewDecl->setQualifierInfo(NewQualifierLoc);
   return false;
 }
 
 bool TemplateDeclInstantiator::SubstQualifier(const DeclaratorDecl *OldDecl,
                                               DeclaratorDecl *NewDecl) {
   return ::SubstQualifier(SemaRef, OldDecl, NewDecl, TemplateArgs);
 }
 
 bool TemplateDeclInstantiator::SubstQualifier(const TagDecl *OldDecl,
                                               TagDecl *NewDecl) {
   return ::SubstQualifier(SemaRef, OldDecl, NewDecl, TemplateArgs);
 }
 
 // Include attribute instantiation code.
 #include "clang/Sema/AttrTemplateInstantiate.inc"
 
 static void instantiateDependentAlignedAttr(
     Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
     const AlignedAttr *Aligned, Decl *New, bool IsPackExpansion) {
   if (Aligned->isAlignmentExpr()) {
     // The alignment expression is a constant expression.
     EnterExpressionEvaluationContext Unevaluated(
         S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
     ExprResult Result = S.SubstExpr(Aligned->getAlignmentExpr(), TemplateArgs);
     if (!Result.isInvalid())
       S.AddAlignedAttr(New, *Aligned, Result.getAs<Expr>(), IsPackExpansion);
   } else {
     if (TypeSourceInfo *Result =
             S.SubstType(Aligned->getAlignmentType(), TemplateArgs,
                         Aligned->getLocation(), DeclarationName())) {
       if (!S.CheckAlignasTypeArgument(Aligned->getSpelling(), Result,
                                       Aligned->getLocation(),
                                       Result->getTypeLoc().getSourceRange()))
         S.AddAlignedAttr(New, *Aligned, Result, IsPackExpansion);
     }
   }
 }
 
 static void instantiateDependentAlignedAttr(
     Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
     const AlignedAttr *Aligned, Decl *New) {
   if (!Aligned->isPackExpansion()) {
     instantiateDependentAlignedAttr(S, TemplateArgs, Aligned, New, false);
     return;
   }
 
   SmallVector<UnexpandedParameterPack, 2> Unexpanded;
   if (Aligned->isAlignmentExpr())
     S.collectUnexpandedParameterPacks(Aligned->getAlignmentExpr(),
                                       Unexpanded);
   else
     S.collectUnexpandedParameterPacks(Aligned->getAlignmentType()->getTypeLoc(),
                                       Unexpanded);
   assert(!Unexpanded.empty() && "Pack expansion without parameter packs?");
 
   // Determine whether we can expand this attribute pack yet.
   bool Expand = true, RetainExpansion = false;
   std::optional<unsigned> NumExpansions;
   // FIXME: Use the actual location of the ellipsis.
   SourceLocation EllipsisLoc = Aligned->getLocation();
   if (S.CheckParameterPacksForExpansion(EllipsisLoc, Aligned->getRange(),
                                         Unexpanded, TemplateArgs, Expand,
                                         RetainExpansion, NumExpansions))
     return;
 
   if (!Expand) {
     Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(S, -1);
     instantiateDependentAlignedAttr(S, TemplateArgs, Aligned, New, true);
   } else {
     for (unsigned I = 0; I != *NumExpansions; ++I) {
       Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(S, I);
       instantiateDependentAlignedAttr(S, TemplateArgs, Aligned, New, false);
     }
   }
 }
 
 static void instantiateDependentAssumeAlignedAttr(
     Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
     const AssumeAlignedAttr *Aligned, Decl *New) {
   // The alignment expression is a constant expression.
   EnterExpressionEvaluationContext Unevaluated(
       S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
 
   Expr *E, *OE = nullptr;
   ExprResult Result = S.SubstExpr(Aligned->getAlignment(), TemplateArgs);
   if (Result.isInvalid())
     return;
   E = Result.getAs<Expr>();
 
   if (Aligned->getOffset()) {
     Result = S.SubstExpr(Aligned->getOffset(), TemplateArgs);
     if (Result.isInvalid())
       return;
     OE = Result.getAs<Expr>();
   }
 
   S.AddAssumeAlignedAttr(New, *Aligned, E, OE);
 }
 
 static void instantiateDependentAlignValueAttr(
     Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
     const AlignValueAttr *Aligned, Decl *New) {
   // The alignment expression is a constant expression.
   EnterExpressionEvaluationContext Unevaluated(
       S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
   ExprResult Result = S.SubstExpr(Aligned->getAlignment(), TemplateArgs);
   if (!Result.isInvalid())
     S.AddAlignValueAttr(New, *Aligned, Result.getAs<Expr>());
 }
 
 static void instantiateDependentAllocAlignAttr(
     Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
     const AllocAlignAttr *Align, Decl *New) {
   Expr *Param = IntegerLiteral::Create(
       S.getASTContext(),
       llvm::APInt(64, Align->getParamIndex().getSourceIndex()),
       S.getASTContext().UnsignedLongLongTy, Align->getLocation());
   S.AddAllocAlignAttr(New, *Align, Param);
 }
 
 static void instantiateDependentAnnotationAttr(
     Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
     const AnnotateAttr *Attr, Decl *New) {
   EnterExpressionEvaluationContext Unevaluated(
       S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
 
   // If the attribute has delayed arguments it will have to instantiate those
   // and handle them as new arguments for the attribute.
   bool HasDelayedArgs = Attr->delayedArgs_size();
 
   ArrayRef<Expr *> ArgsToInstantiate =
       HasDelayedArgs
           ? ArrayRef<Expr *>{Attr->delayedArgs_begin(), Attr->delayedArgs_end()}
           : ArrayRef<Expr *>{Attr->args_begin(), Attr->args_end()};
 
   SmallVector<Expr *, 4> Args;
   if (S.SubstExprs(ArgsToInstantiate,
                    /*IsCall=*/false, TemplateArgs, Args))
     return;
 
   StringRef Str = Attr->getAnnotation();
   if (HasDelayedArgs) {
     if (Args.size() < 1) {
       S.Diag(Attr->getLoc(), diag::err_attribute_too_few_arguments)
           << Attr << 1;
       return;
     }
 
     if (!S.checkStringLiteralArgumentAttr(*Attr, Args[0], Str))
       return;
 
     llvm::SmallVector<Expr *, 4> ActualArgs;
     ActualArgs.insert(ActualArgs.begin(), Args.begin() + 1, Args.end());
     std::swap(Args, ActualArgs);
   }
   S.AddAnnotationAttr(New, *Attr, Str, Args);
 }
 
 static Expr *instantiateDependentFunctionAttrCondition(
     Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
     const Attr *A, Expr *OldCond, const Decl *Tmpl, FunctionDecl *New) {
   Expr *Cond = nullptr;
   {
     Sema::ContextRAII SwitchContext(S, New);
     EnterExpressionEvaluationContext Unevaluated(
         S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
     ExprResult Result = S.SubstExpr(OldCond, TemplateArgs);
     if (Result.isInvalid())
       return nullptr;
     Cond = Result.getAs<Expr>();
   }
   if (!Cond->isTypeDependent()) {
     ExprResult Converted = S.PerformContextuallyConvertToBool(Cond);
     if (Converted.isInvalid())
       return nullptr;
     Cond = Converted.get();
   }
 
   SmallVector<PartialDiagnosticAt, 8> Diags;
   if (OldCond->isValueDependent() && !Cond->isValueDependent() &&
       !Expr::isPotentialConstantExprUnevaluated(Cond, New, Diags)) {
     S.Diag(A->getLocation(), diag::err_attr_cond_never_constant_expr) << A;
     for (const auto &P : Diags)
       S.Diag(P.first, P.second);
     return nullptr;
   }
   return Cond;
 }
 
 static void instantiateDependentEnableIfAttr(
     Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
     const EnableIfAttr *EIA, const Decl *Tmpl, FunctionDecl *New) {
   Expr *Cond = instantiateDependentFunctionAttrCondition(
       S, TemplateArgs, EIA, EIA->getCond(), Tmpl, New);
 
   if (Cond)
     New->addAttr(new (S.getASTContext()) EnableIfAttr(S.getASTContext(), *EIA,
                                                       Cond, EIA->getMessage()));
 }
 
 static void instantiateDependentDiagnoseIfAttr(
     Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
     const DiagnoseIfAttr *DIA, const Decl *Tmpl, FunctionDecl *New) {
   Expr *Cond = instantiateDependentFunctionAttrCondition(
       S, TemplateArgs, DIA, DIA->getCond(), Tmpl, New);
 
   if (Cond)
     New->addAttr(new (S.getASTContext()) DiagnoseIfAttr(
         S.getASTContext(), *DIA, Cond, DIA->getMessage(),
         DIA->getDiagnosticType(), DIA->getArgDependent(), New));
 }
 
 // Constructs and adds to New a new instance of CUDALaunchBoundsAttr using
 // template A as the base and arguments from TemplateArgs.
 static void instantiateDependentCUDALaunchBoundsAttr(
     Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
     const CUDALaunchBoundsAttr &Attr, Decl *New) {
   // The alignment expression is a constant expression.
   EnterExpressionEvaluationContext Unevaluated(
       S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
 
   ExprResult Result = S.SubstExpr(Attr.getMaxThreads(), TemplateArgs);
   if (Result.isInvalid())
     return;
   Expr *MaxThreads = Result.getAs<Expr>();
 
   Expr *MinBlocks = nullptr;
   if (Attr.getMinBlocks()) {
     Result = S.SubstExpr(Attr.getMinBlocks(), TemplateArgs);
     if (Result.isInvalid())
       return;
     MinBlocks = Result.getAs<Expr>();
   }
 
   S.AddLaunchBoundsAttr(New, Attr, MaxThreads, MinBlocks);
 }
 
 static void
 instantiateDependentModeAttr(Sema &S,
                              const MultiLevelTemplateArgumentList &TemplateArgs,
                              const ModeAttr &Attr, Decl *New) {
   S.AddModeAttr(New, Attr, Attr.getMode(),
                 /*InInstantiation=*/true);
 }
 
 /// Instantiation of 'declare simd' attribute and its arguments.
 static void instantiateOMPDeclareSimdDeclAttr(
     Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
     const OMPDeclareSimdDeclAttr &Attr, Decl *New) {
   // Allow 'this' in clauses with varlists.
   if (auto *FTD = dyn_cast<FunctionTemplateDecl>(New))
     New = FTD->getTemplatedDecl();
   auto *FD = cast<FunctionDecl>(New);
   auto *ThisContext = dyn_cast_or_null<CXXRecordDecl>(FD->getDeclContext());
   SmallVector<Expr *, 4> Uniforms, Aligneds, Alignments, Linears, Steps;
   SmallVector<unsigned, 4> LinModifiers;
 
   auto SubstExpr = [&](Expr *E) -> ExprResult {
     if (auto *DRE = dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts()))
       if (auto *PVD = dyn_cast<ParmVarDecl>(DRE->getDecl())) {
         Sema::ContextRAII SavedContext(S, FD);
         LocalInstantiationScope Local(S);
         if (FD->getNumParams() > PVD->getFunctionScopeIndex())
           Local.InstantiatedLocal(
               PVD, FD->getParamDecl(PVD->getFunctionScopeIndex()));
         return S.SubstExpr(E, TemplateArgs);
       }
     Sema::CXXThisScopeRAII ThisScope(S, ThisContext, Qualifiers(),
                                      FD->isCXXInstanceMember());
     return S.SubstExpr(E, TemplateArgs);
   };
 
   // Substitute a single OpenMP clause, which is a potentially-evaluated
   // full-expression.
   auto Subst = [&](Expr *E) -> ExprResult {
     EnterExpressionEvaluationContext Evaluated(
         S, Sema::ExpressionEvaluationContext::PotentiallyEvaluated);
     ExprResult Res = SubstExpr(E);
     if (Res.isInvalid())
       return Res;
     return S.ActOnFinishFullExpr(Res.get(), false);
   };
 
   ExprResult Simdlen;
   if (auto *E = Attr.getSimdlen())
     Simdlen = Subst(E);
 
   if (Attr.uniforms_size() > 0) {
     for(auto *E : Attr.uniforms()) {
       ExprResult Inst = Subst(E);
       if (Inst.isInvalid())
         continue;
       Uniforms.push_back(Inst.get());
     }
   }
 
   auto AI = Attr.alignments_begin();
   for (auto *E : Attr.aligneds()) {
     ExprResult Inst = Subst(E);
     if (Inst.isInvalid())
       continue;
     Aligneds.push_back(Inst.get());
     Inst = ExprEmpty();
     if (*AI)
       Inst = S.SubstExpr(*AI, TemplateArgs);
     Alignments.push_back(Inst.get());
     ++AI;
   }
 
   auto SI = Attr.steps_begin();
   for (auto *E : Attr.linears()) {
     ExprResult Inst = Subst(E);
     if (Inst.isInvalid())
       continue;
     Linears.push_back(Inst.get());
     Inst = ExprEmpty();
     if (*SI)
       Inst = S.SubstExpr(*SI, TemplateArgs);
     Steps.push_back(Inst.get());
     ++SI;
   }
   LinModifiers.append(Attr.modifiers_begin(), Attr.modifiers_end());
   (void)S.ActOnOpenMPDeclareSimdDirective(
       S.ConvertDeclToDeclGroup(New), Attr.getBranchState(), Simdlen.get(),
       Uniforms, Aligneds, Alignments, Linears, LinModifiers, Steps,
       Attr.getRange());
 }
 
 /// Instantiation of 'declare variant' attribute and its arguments.
 static void instantiateOMPDeclareVariantAttr(
     Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
     const OMPDeclareVariantAttr &Attr, Decl *New) {
   // Allow 'this' in clauses with varlists.
   if (auto *FTD = dyn_cast<FunctionTemplateDecl>(New))
     New = FTD->getTemplatedDecl();
   auto *FD = cast<FunctionDecl>(New);
   auto *ThisContext = dyn_cast_or_null<CXXRecordDecl>(FD->getDeclContext());
 
   auto &&SubstExpr = [FD, ThisContext, &S, &TemplateArgs](Expr *E) {
     if (auto *DRE = dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts()))
       if (auto *PVD = dyn_cast<ParmVarDecl>(DRE->getDecl())) {
         Sema::ContextRAII SavedContext(S, FD);
         LocalInstantiationScope Local(S);
         if (FD->getNumParams() > PVD->getFunctionScopeIndex())
           Local.InstantiatedLocal(
               PVD, FD->getParamDecl(PVD->getFunctionScopeIndex()));
         return S.SubstExpr(E, TemplateArgs);
       }
     Sema::CXXThisScopeRAII ThisScope(S, ThisContext, Qualifiers(),
                                      FD->isCXXInstanceMember());
     return S.SubstExpr(E, TemplateArgs);
   };
 
   // Substitute a single OpenMP clause, which is a potentially-evaluated
   // full-expression.
   auto &&Subst = [&SubstExpr, &S](Expr *E) {
     EnterExpressionEvaluationContext Evaluated(
         S, Sema::ExpressionEvaluationContext::PotentiallyEvaluated);
     ExprResult Res = SubstExpr(E);
     if (Res.isInvalid())
       return Res;
     return S.ActOnFinishFullExpr(Res.get(), false);
   };
 
   ExprResult VariantFuncRef;
   if (Expr *E = Attr.getVariantFuncRef()) {
     // Do not mark function as is used to prevent its emission if this is the
     // only place where it is used.
     EnterExpressionEvaluationContext Unevaluated(
         S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
     VariantFuncRef = Subst(E);
   }
 
   // Copy the template version of the OMPTraitInfo and run substitute on all
   // score and condition expressiosn.
   OMPTraitInfo &TI = S.getASTContext().getNewOMPTraitInfo();
   TI = *Attr.getTraitInfos();
 
   // Try to substitute template parameters in score and condition expressions.
   auto SubstScoreOrConditionExpr = [&S, Subst](Expr *&E, bool) {
     if (E) {
       EnterExpressionEvaluationContext Unevaluated(
           S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
       ExprResult ER = Subst(E);
       if (ER.isUsable())
         E = ER.get();
       else
         return true;
     }
     return false;
   };
   if (TI.anyScoreOrCondition(SubstScoreOrConditionExpr))
     return;
 
   Expr *E = VariantFuncRef.get();
 
   // Check function/variant ref for `omp declare variant` but not for `omp
   // begin declare variant` (which use implicit attributes).
   std::optional<std::pair<FunctionDecl *, Expr *>> DeclVarData =
       S.checkOpenMPDeclareVariantFunction(S.ConvertDeclToDeclGroup(New), E, TI,
                                           Attr.appendArgs_size(),
                                           Attr.getRange());
 
   if (!DeclVarData)
     return;
 
   E = DeclVarData->second;
   FD = DeclVarData->first;
 
   if (auto *VariantDRE = dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts())) {
     if (auto *VariantFD = dyn_cast<FunctionDecl>(VariantDRE->getDecl())) {
       if (auto *VariantFTD = VariantFD->getDescribedFunctionTemplate()) {
         if (!VariantFTD->isThisDeclarationADefinition())
           return;
         Sema::TentativeAnalysisScope Trap(S);
         const TemplateArgumentList *TAL = TemplateArgumentList::CreateCopy(
             S.Context, TemplateArgs.getInnermost());
 
         auto *SubstFD = S.InstantiateFunctionDeclaration(VariantFTD, TAL,
                                                          New->getLocation());
         if (!SubstFD)
           return;
         QualType NewType = S.Context.mergeFunctionTypes(
             SubstFD->getType(), FD->getType(),
             /* OfBlockPointer */ false,
             /* Unqualified */ false, /* AllowCXX */ true);
         if (NewType.isNull())
           return;
         S.InstantiateFunctionDefinition(
             New->getLocation(), SubstFD, /* Recursive */ true,
             /* DefinitionRequired */ false, /* AtEndOfTU */ false);
         SubstFD->setInstantiationIsPending(!SubstFD->isDefined());
         E = DeclRefExpr::Create(S.Context, NestedNameSpecifierLoc(),
                                 SourceLocation(), SubstFD,
                                 /* RefersToEnclosingVariableOrCapture */ false,
                                 /* NameLoc */ SubstFD->getLocation(),
                                 SubstFD->getType(), ExprValueKind::VK_PRValue);
       }
     }
   }
 
   SmallVector<Expr *, 8> NothingExprs;
   SmallVector<Expr *, 8> NeedDevicePtrExprs;
   SmallVector<OMPInteropInfo, 4> AppendArgs;
 
   for (Expr *E : Attr.adjustArgsNothing()) {
     ExprResult ER = Subst(E);
     if (ER.isInvalid())
       continue;
     NothingExprs.push_back(ER.get());
   }
   for (Expr *E : Attr.adjustArgsNeedDevicePtr()) {
     ExprResult ER = Subst(E);
     if (ER.isInvalid())
       continue;
     NeedDevicePtrExprs.push_back(ER.get());
   }
   for (OMPInteropInfo &II : Attr.appendArgs()) {
     // When prefer_type is implemented for append_args handle them here too.
     AppendArgs.emplace_back(II.IsTarget, II.IsTargetSync);
   }
 
   S.ActOnOpenMPDeclareVariantDirective(
       FD, E, TI, NothingExprs, NeedDevicePtrExprs, AppendArgs, SourceLocation(),
       SourceLocation(), Attr.getRange());
 }
 
 static void instantiateDependentAMDGPUFlatWorkGroupSizeAttr(
     Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
     const AMDGPUFlatWorkGroupSizeAttr &Attr, Decl *New) {
   // Both min and max expression are constant expressions.
   EnterExpressionEvaluationContext Unevaluated(
       S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
 
   ExprResult Result = S.SubstExpr(Attr.getMin(), TemplateArgs);
   if (Result.isInvalid())
     return;
   Expr *MinExpr = Result.getAs<Expr>();
 
   Result = S.SubstExpr(Attr.getMax(), TemplateArgs);
   if (Result.isInvalid())
     return;
   Expr *MaxExpr = Result.getAs<Expr>();
 
   S.addAMDGPUFlatWorkGroupSizeAttr(New, Attr, MinExpr, MaxExpr);
 }
 
 static ExplicitSpecifier
 instantiateExplicitSpecifier(Sema &S,
                              const MultiLevelTemplateArgumentList &TemplateArgs,
                              ExplicitSpecifier ES, FunctionDecl *New) {
   if (!ES.getExpr())
     return ES;
   Expr *OldCond = ES.getExpr();
   Expr *Cond = nullptr;
   {
     EnterExpressionEvaluationContext Unevaluated(
         S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
     ExprResult SubstResult = S.SubstExpr(OldCond, TemplateArgs);
     if (SubstResult.isInvalid()) {
       return ExplicitSpecifier::Invalid();
     }
     Cond = SubstResult.get();
   }
   ExplicitSpecifier Result(Cond, ES.getKind());
   if (!Cond->isTypeDependent())
     S.tryResolveExplicitSpecifier(Result);
   return Result;
 }
 
 static void instantiateDependentAMDGPUWavesPerEUAttr(
     Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
     const AMDGPUWavesPerEUAttr &Attr, Decl *New) {
   // Both min and max expression are constant expressions.
   EnterExpressionEvaluationContext Unevaluated(
       S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
 
   ExprResult Result = S.SubstExpr(Attr.getMin(), TemplateArgs);
   if (Result.isInvalid())
     return;
   Expr *MinExpr = Result.getAs<Expr>();
 
   Expr *MaxExpr = nullptr;
   if (auto Max = Attr.getMax()) {
     Result = S.SubstExpr(Max, TemplateArgs);
     if (Result.isInvalid())
       return;
     MaxExpr = Result.getAs<Expr>();
   }
 
   S.addAMDGPUWavesPerEUAttr(New, Attr, MinExpr, MaxExpr);
 }
 
 // This doesn't take any template parameters, but we have a custom action that
 // needs to happen when the kernel itself is instantiated. We need to run the
 // ItaniumMangler to mark the names required to name this kernel.
 static void instantiateDependentSYCLKernelAttr(
     Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
     const SYCLKernelAttr &Attr, Decl *New) {
   New->addAttr(Attr.clone(S.getASTContext()));
 }
 
 /// Determine whether the attribute A might be relevant to the declaration D.
 /// If not, we can skip instantiating it. The attribute may or may not have
 /// been instantiated yet.
 static bool isRelevantAttr(Sema &S, const Decl *D, const Attr *A) {
   // 'preferred_name' is only relevant to the matching specialization of the
   // template.
   if (const auto *PNA = dyn_cast<PreferredNameAttr>(A)) {
     QualType T = PNA->getTypedefType();
     const auto *RD = cast<CXXRecordDecl>(D);
     if (!T->isDependentType() && !RD->isDependentContext() &&
         !declaresSameEntity(T->getAsCXXRecordDecl(), RD))
       return false;
     for (const auto *ExistingPNA : D->specific_attrs<PreferredNameAttr>())
       if (S.Context.hasSameType(ExistingPNA->getTypedefType(),
                                 PNA->getTypedefType()))
         return false;
     return true;
   }
 
   if (const auto *BA = dyn_cast<BuiltinAttr>(A)) {
     const FunctionDecl *FD = dyn_cast<FunctionDecl>(D);
     switch (BA->getID()) {
     case Builtin::BIforward:
       // Do not treat 'std::forward' as a builtin if it takes an rvalue reference
       // type and returns an lvalue reference type. The library implementation
       // will produce an error in this case; don't get in its way.
       if (FD && FD->getNumParams() >= 1 &&
           FD->getParamDecl(0)->getType()->isRValueReferenceType() &&
           FD->getReturnType()->isLValueReferenceType()) {
         return false;
       }
       [[fallthrough]];
     case Builtin::BImove:
     case Builtin::BImove_if_noexcept:
       // HACK: Super-old versions of libc++ (3.1 and earlier) provide
       // std::forward and std::move overloads that sometimes return by value
       // instead of by reference when building in C++98 mode. Don't treat such
       // cases as builtins.
       if (FD && !FD->getReturnType()->isReferenceType())
         return false;
       break;
     }
   }
 
   return true;
 }
 
 void Sema::InstantiateAttrsForDecl(
     const MultiLevelTemplateArgumentList &TemplateArgs, const Decl *Tmpl,
     Decl *New, LateInstantiatedAttrVec *LateAttrs,
     LocalInstantiationScope *OuterMostScope) {
   if (NamedDecl *ND = dyn_cast<NamedDecl>(New)) {
     // FIXME: This function is called multiple times for the same template
     // specialization. We should only instantiate attributes that were added
     // since the previous instantiation.
     for (const auto *TmplAttr : Tmpl->attrs()) {
       if (!isRelevantAttr(*this, New, TmplAttr))
         continue;
 
       // FIXME: If any of the special case versions from InstantiateAttrs become
       // applicable to template declaration, we'll need to add them here.
       CXXThisScopeRAII ThisScope(
           *this, dyn_cast_or_null<CXXRecordDecl>(ND->getDeclContext()),
           Qualifiers(), ND->isCXXInstanceMember());
 
       Attr *NewAttr = sema::instantiateTemplateAttributeForDecl(
           TmplAttr, Context, *this, TemplateArgs);
       if (NewAttr && isRelevantAttr(*this, New, NewAttr))
         New->addAttr(NewAttr);
     }
   }
 }
 
 static Sema::RetainOwnershipKind
 attrToRetainOwnershipKind(const Attr *A) {
   switch (A->getKind()) {
   case clang::attr::CFConsumed:
     return Sema::RetainOwnershipKind::CF;
   case clang::attr::OSConsumed:
     return Sema::RetainOwnershipKind::OS;
   case clang::attr::NSConsumed:
     return Sema::RetainOwnershipKind::NS;
   default:
     llvm_unreachable("Wrong argument supplied");
   }
 }
 
 void Sema::InstantiateAttrs(const MultiLevelTemplateArgumentList &TemplateArgs,
                             const Decl *Tmpl, Decl *New,
                             LateInstantiatedAttrVec *LateAttrs,
                             LocalInstantiationScope *OuterMostScope) {
   for (const auto *TmplAttr : Tmpl->attrs()) {
     if (!isRelevantAttr(*this, New, TmplAttr))
       continue;
 
     // FIXME: This should be generalized to more than just the AlignedAttr.
     const AlignedAttr *Aligned = dyn_cast<AlignedAttr>(TmplAttr);
     if (Aligned && Aligned->isAlignmentDependent()) {
       instantiateDependentAlignedAttr(*this, TemplateArgs, Aligned, New);
       continue;
     }
 
     if (const auto *AssumeAligned = dyn_cast<AssumeAlignedAttr>(TmplAttr)) {
       instantiateDependentAssumeAlignedAttr(*this, TemplateArgs, AssumeAligned, New);
       continue;
     }
 
     if (const auto *AlignValue = dyn_cast<AlignValueAttr>(TmplAttr)) {
       instantiateDependentAlignValueAttr(*this, TemplateArgs, AlignValue, New);
       continue;
     }
 
     if (const auto *AllocAlign = dyn_cast<AllocAlignAttr>(TmplAttr)) {
       instantiateDependentAllocAlignAttr(*this, TemplateArgs, AllocAlign, New);
       continue;
     }
 
     if (const auto *Annotate = dyn_cast<AnnotateAttr>(TmplAttr)) {
       instantiateDependentAnnotationAttr(*this, TemplateArgs, Annotate, New);
       continue;
     }
 
     if (const auto *EnableIf = dyn_cast<EnableIfAttr>(TmplAttr)) {
       instantiateDependentEnableIfAttr(*this, TemplateArgs, EnableIf, Tmpl,
                                        cast<FunctionDecl>(New));
       continue;
     }
 
     if (const auto *DiagnoseIf = dyn_cast<DiagnoseIfAttr>(TmplAttr)) {
       instantiateDependentDiagnoseIfAttr(*this, TemplateArgs, DiagnoseIf, Tmpl,
                                          cast<FunctionDecl>(New));
       continue;
     }
 
     if (const auto *CUDALaunchBounds =
             dyn_cast<CUDALaunchBoundsAttr>(TmplAttr)) {
       instantiateDependentCUDALaunchBoundsAttr(*this, TemplateArgs,
                                                *CUDALaunchBounds, New);
       continue;
     }
 
     if (const auto *Mode = dyn_cast<ModeAttr>(TmplAttr)) {
       instantiateDependentModeAttr(*this, TemplateArgs, *Mode, New);
       continue;
     }
 
     if (const auto *OMPAttr = dyn_cast<OMPDeclareSimdDeclAttr>(TmplAttr)) {
       instantiateOMPDeclareSimdDeclAttr(*this, TemplateArgs, *OMPAttr, New);
       continue;
     }
 
     if (const auto *OMPAttr = dyn_cast<OMPDeclareVariantAttr>(TmplAttr)) {
       instantiateOMPDeclareVariantAttr(*this, TemplateArgs, *OMPAttr, New);
       continue;
     }
 
     if (const auto *AMDGPUFlatWorkGroupSize =
             dyn_cast<AMDGPUFlatWorkGroupSizeAttr>(TmplAttr)) {
       instantiateDependentAMDGPUFlatWorkGroupSizeAttr(
           *this, TemplateArgs, *AMDGPUFlatWorkGroupSize, New);
     }
 
     if (const auto *AMDGPUFlatWorkGroupSize =
             dyn_cast<AMDGPUWavesPerEUAttr>(TmplAttr)) {
       instantiateDependentAMDGPUWavesPerEUAttr(*this, TemplateArgs,
                                                *AMDGPUFlatWorkGroupSize, New);
     }
 
     // Existing DLL attribute on the instantiation takes precedence.
     if (TmplAttr->getKind() == attr::DLLExport ||
         TmplAttr->getKind() == attr::DLLImport) {
       if (New->hasAttr<DLLExportAttr>() || New->hasAttr<DLLImportAttr>()) {
         continue;
       }
     }
 
     if (const auto *ABIAttr = dyn_cast<ParameterABIAttr>(TmplAttr)) {
       AddParameterABIAttr(New, *ABIAttr, ABIAttr->getABI());
       continue;
     }
 
     if (isa<NSConsumedAttr>(TmplAttr) || isa<OSConsumedAttr>(TmplAttr) ||
         isa<CFConsumedAttr>(TmplAttr)) {
       AddXConsumedAttr(New, *TmplAttr, attrToRetainOwnershipKind(TmplAttr),
                        /*template instantiation=*/true);
       continue;
     }
 
     if (auto *A = dyn_cast<PointerAttr>(TmplAttr)) {
       if (!New->hasAttr<PointerAttr>())
         New->addAttr(A->clone(Context));
       continue;
     }
 
     if (auto *A = dyn_cast<OwnerAttr>(TmplAttr)) {
       if (!New->hasAttr<OwnerAttr>())
         New->addAttr(A->clone(Context));
       continue;
     }
 
     if (auto *A = dyn_cast<SYCLKernelAttr>(TmplAttr)) {
       instantiateDependentSYCLKernelAttr(*this, TemplateArgs, *A, New);
       continue;
     }
 
     assert(!TmplAttr->isPackExpansion());
     if (TmplAttr->isLateParsed() && LateAttrs) {
       // Late parsed attributes must be instantiated and attached after the
       // enclosing class has been instantiated.  See Sema::InstantiateClass.
       LocalInstantiationScope *Saved = nullptr;
       if (CurrentInstantiationScope)
         Saved = CurrentInstantiationScope->cloneScopes(OuterMostScope);
       LateAttrs->push_back(LateInstantiatedAttribute(TmplAttr, Saved, New));
     } else {
       // Allow 'this' within late-parsed attributes.
       auto *ND = cast<NamedDecl>(New);
       auto *ThisContext = dyn_cast_or_null<CXXRecordDecl>(ND->getDeclContext());
       CXXThisScopeRAII ThisScope(*this, ThisContext, Qualifiers(),
                                  ND->isCXXInstanceMember());
 
       Attr *NewAttr = sema::instantiateTemplateAttribute(TmplAttr, Context,
                                                          *this, TemplateArgs);
       if (NewAttr && isRelevantAttr(*this, New, TmplAttr))
         New->addAttr(NewAttr);
     }
   }
 }
 
 /// Update instantiation attributes after template was late parsed.
 ///
 /// Some attributes are evaluated based on the body of template. If it is
 /// late parsed, such attributes cannot be evaluated when declaration is
 /// instantiated. This function is used to update instantiation attributes when
 /// template definition is ready.
 void Sema::updateAttrsForLateParsedTemplate(const Decl *Pattern, Decl *Inst) {
   for (const auto *Attr : Pattern->attrs()) {
     if (auto *A = dyn_cast<StrictFPAttr>(Attr)) {
       if (!Inst->hasAttr<StrictFPAttr>())
         Inst->addAttr(A->clone(getASTContext()));
       continue;
     }
   }
 }
 
 /// In the MS ABI, we need to instantiate default arguments of dllexported
 /// default constructors along with the constructor definition. This allows IR
 /// gen to emit a constructor closure which calls the default constructor with
 /// its default arguments.
 void Sema::InstantiateDefaultCtorDefaultArgs(CXXConstructorDecl *Ctor) {
   assert(Context.getTargetInfo().getCXXABI().isMicrosoft() &&
          Ctor->isDefaultConstructor());
   unsigned NumParams = Ctor->getNumParams();
   if (NumParams == 0)
     return;
   DLLExportAttr *Attr = Ctor->getAttr<DLLExportAttr>();
   if (!Attr)
     return;
   for (unsigned I = 0; I != NumParams; ++I) {
     (void)CheckCXXDefaultArgExpr(Attr->getLocation(), Ctor,
                                    Ctor->getParamDecl(I));
     CleanupVarDeclMarking();
   }
 }
 
 /// Get the previous declaration of a declaration for the purposes of template
 /// instantiation. If this finds a previous declaration, then the previous
 /// declaration of the instantiation of D should be an instantiation of the
 /// result of this function.
 template<typename DeclT>
 static DeclT *getPreviousDeclForInstantiation(DeclT *D) {
   DeclT *Result = D->getPreviousDecl();
 
   // If the declaration is within a class, and the previous declaration was
   // merged from a different definition of that class, then we don't have a
   // previous declaration for the purpose of template instantiation.
   if (Result && isa<CXXRecordDecl>(D->getDeclContext()) &&
       D->getLexicalDeclContext() != Result->getLexicalDeclContext())
     return nullptr;
 
   return Result;
 }
 
 Decl *
 TemplateDeclInstantiator::VisitTranslationUnitDecl(TranslationUnitDecl *D) {
   llvm_unreachable("Translation units cannot be instantiated");
 }
 
 Decl *TemplateDeclInstantiator::VisitHLSLBufferDecl(HLSLBufferDecl *Decl) {
   llvm_unreachable("HLSL buffer declarations cannot be instantiated");
 }
 
 Decl *
 TemplateDeclInstantiator::VisitPragmaCommentDecl(PragmaCommentDecl *D) {
   llvm_unreachable("pragma comment cannot be instantiated");
 }
 
 Decl *TemplateDeclInstantiator::VisitPragmaDetectMismatchDecl(
     PragmaDetectMismatchDecl *D) {
   llvm_unreachable("pragma comment cannot be instantiated");
 }
 
 Decl *
 TemplateDeclInstantiator::VisitExternCContextDecl(ExternCContextDecl *D) {
   llvm_unreachable("extern \"C\" context cannot be instantiated");
 }
 
 Decl *TemplateDeclInstantiator::VisitMSGuidDecl(MSGuidDecl *D) {
   llvm_unreachable("GUID declaration cannot be instantiated");
 }
 
 Decl *TemplateDeclInstantiator::VisitUnnamedGlobalConstantDecl(
     UnnamedGlobalConstantDecl *D) {
   llvm_unreachable("UnnamedGlobalConstantDecl cannot be instantiated");
 }
 
 Decl *TemplateDeclInstantiator::VisitTemplateParamObjectDecl(
     TemplateParamObjectDecl *D) {
   llvm_unreachable("template parameter objects cannot be instantiated");
 }
 
 Decl *
 TemplateDeclInstantiator::VisitLabelDecl(LabelDecl *D) {
   LabelDecl *Inst = LabelDecl::Create(SemaRef.Context, Owner, D->getLocation(),
                                       D->getIdentifier());
   Owner->addDecl(Inst);
   return Inst;
 }
 
 Decl *
 TemplateDeclInstantiator::VisitNamespaceDecl(NamespaceDecl *D) {
   llvm_unreachable("Namespaces cannot be instantiated");
 }
 
 Decl *
 TemplateDeclInstantiator::VisitNamespaceAliasDecl(NamespaceAliasDecl *D) {
   NamespaceAliasDecl *Inst
     = NamespaceAliasDecl::Create(SemaRef.Context, Owner,
                                  D->getNamespaceLoc(),
                                  D->getAliasLoc(),
                                  D->getIdentifier(),
                                  D->getQualifierLoc(),
                                  D->getTargetNameLoc(),
                                  D->getNamespace());
   Owner->addDecl(Inst);
   return Inst;
 }
 
 Decl *TemplateDeclInstantiator::InstantiateTypedefNameDecl(TypedefNameDecl *D,
                                                            bool IsTypeAlias) {
   bool Invalid = false;
   TypeSourceInfo *DI = D->getTypeSourceInfo();
   if (DI->getType()->isInstantiationDependentType() ||
       DI->getType()->isVariablyModifiedType()) {
     DI = SemaRef.SubstType(DI, TemplateArgs,
                            D->getLocation(), D->getDeclName());
     if (!DI) {
       Invalid = true;
       DI = SemaRef.Context.getTrivialTypeSourceInfo(SemaRef.Context.IntTy);
     }
   } else {
     SemaRef.MarkDeclarationsReferencedInType(D->getLocation(), DI->getType());
   }
 
   // HACK: 2012-10-23 g++ has a bug where it gets the value kind of ?: wrong.
   // libstdc++ relies upon this bug in its implementation of common_type.  If we
   // happen to be processing that implementation, fake up the g++ ?:
   // semantics. See LWG issue 2141 for more information on the bug.  The bugs
   // are fixed in g++ and libstdc++ 4.9.0 (2014-04-22).
   const DecltypeType *DT = DI->getType()->getAs<DecltypeType>();
   CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D->getDeclContext());
   if (DT && RD && isa<ConditionalOperator>(DT->getUnderlyingExpr()) &&
       DT->isReferenceType() &&
       RD->getEnclosingNamespaceContext() == SemaRef.getStdNamespace() &&
       RD->getIdentifier() && RD->getIdentifier()->isStr("common_type") &&
       D->getIdentifier() && D->getIdentifier()->isStr("type") &&
       SemaRef.getSourceManager().isInSystemHeader(D->getBeginLoc()))
     // Fold it to the (non-reference) type which g++ would have produced.
     DI = SemaRef.Context.getTrivialTypeSourceInfo(
       DI->getType().getNonReferenceType());
 
   // Create the new typedef
   TypedefNameDecl *Typedef;
   if (IsTypeAlias)
     Typedef = TypeAliasDecl::Create(SemaRef.Context, Owner, D->getBeginLoc(),
                                     D->getLocation(), D->getIdentifier(), DI);
   else
     Typedef = TypedefDecl::Create(SemaRef.Context, Owner, D->getBeginLoc(),
                                   D->getLocation(), D->getIdentifier(), DI);
   if (Invalid)
     Typedef->setInvalidDecl();
 
   // If the old typedef was the name for linkage purposes of an anonymous
   // tag decl, re-establish that relationship for the new typedef.
   if (const TagType *oldTagType = D->getUnderlyingType()->getAs<TagType>()) {
     TagDecl *oldTag = oldTagType->getDecl();
     if (oldTag->getTypedefNameForAnonDecl() == D && !Invalid) {
       TagDecl *newTag = DI->getType()->castAs<TagType>()->getDecl();
       assert(!newTag->hasNameForLinkage());
       newTag->setTypedefNameForAnonDecl(Typedef);
     }
   }
 
   if (TypedefNameDecl *Prev = getPreviousDeclForInstantiation(D)) {
     NamedDecl *InstPrev = SemaRef.FindInstantiatedDecl(D->getLocation(), Prev,
                                                        TemplateArgs);
     if (!InstPrev)
       return nullptr;
 
     TypedefNameDecl *InstPrevTypedef = cast<TypedefNameDecl>(InstPrev);
 
     // If the typedef types are not identical, reject them.
     SemaRef.isIncompatibleTypedef(InstPrevTypedef, Typedef);
 
     Typedef->setPreviousDecl(InstPrevTypedef);
   }
 
   SemaRef.InstantiateAttrs(TemplateArgs, D, Typedef);
 
   if (D->getUnderlyingType()->getAs<DependentNameType>())
     SemaRef.inferGslPointerAttribute(Typedef);
 
   Typedef->setAccess(D->getAccess());
   Typedef->setReferenced(D->isReferenced());
 
   return Typedef;
 }
 
 Decl *TemplateDeclInstantiator::VisitTypedefDecl(TypedefDecl *D) {
   Decl *Typedef = InstantiateTypedefNameDecl(D, /*IsTypeAlias=*/false);
   if (Typedef)
     Owner->addDecl(Typedef);
   return Typedef;
 }
 
 Decl *TemplateDeclInstantiator::VisitTypeAliasDecl(TypeAliasDecl *D) {
   Decl *Typedef = InstantiateTypedefNameDecl(D, /*IsTypeAlias=*/true);
   if (Typedef)
     Owner->addDecl(Typedef);
   return Typedef;
 }
 
 Decl *
 TemplateDeclInstantiator::VisitTypeAliasTemplateDecl(TypeAliasTemplateDecl *D) {
   // Create a local instantiation scope for this type alias template, which
   // will contain the instantiations of the template parameters.
   LocalInstantiationScope Scope(SemaRef);
 
   TemplateParameterList *TempParams = D->getTemplateParameters();
   TemplateParameterList *InstParams = SubstTemplateParams(TempParams);
   if (!InstParams)
     return nullptr;
 
   TypeAliasDecl *Pattern = D->getTemplatedDecl();
 
   TypeAliasTemplateDecl *PrevAliasTemplate = nullptr;
   if (getPreviousDeclForInstantiation<TypedefNameDecl>(Pattern)) {
     DeclContext::lookup_result Found = Owner->lookup(Pattern->getDeclName());
     if (!Found.empty()) {
       PrevAliasTemplate = dyn_cast<TypeAliasTemplateDecl>(Found.front());
     }
   }
 
   TypeAliasDecl *AliasInst = cast_or_null<TypeAliasDecl>(
     InstantiateTypedefNameDecl(Pattern, /*IsTypeAlias=*/true));
   if (!AliasInst)
     return nullptr;
 
   TypeAliasTemplateDecl *Inst
     = TypeAliasTemplateDecl::Create(SemaRef.Context, Owner, D->getLocation(),
                                     D->getDeclName(), InstParams, AliasInst);
   AliasInst->setDescribedAliasTemplate(Inst);
   if (PrevAliasTemplate)
     Inst->setPreviousDecl(PrevAliasTemplate);
 
   Inst->setAccess(D->getAccess());
 
   if (!PrevAliasTemplate)
     Inst->setInstantiatedFromMemberTemplate(D);
 
   Owner->addDecl(Inst);
 
   return Inst;
 }
 
 Decl *TemplateDeclInstantiator::VisitBindingDecl(BindingDecl *D) {
   auto *NewBD = BindingDecl::Create(SemaRef.Context, Owner, D->getLocation(),
                                     D->getIdentifier());
   NewBD->setReferenced(D->isReferenced());
   SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, NewBD);
   return NewBD;
 }
 
 Decl *TemplateDeclInstantiator::VisitDecompositionDecl(DecompositionDecl *D) {
   // Transform the bindings first.
   SmallVector<BindingDecl*, 16> NewBindings;
   for (auto *OldBD : D->bindings())
     NewBindings.push_back(cast<BindingDecl>(VisitBindingDecl(OldBD)));
   ArrayRef<BindingDecl*> NewBindingArray = NewBindings;
 
   auto *NewDD = cast_or_null<DecompositionDecl>(
       VisitVarDecl(D, /*InstantiatingVarTemplate=*/false, &NewBindingArray));
 
   if (!NewDD || NewDD->isInvalidDecl())
     for (auto *NewBD : NewBindings)
       NewBD->setInvalidDecl();
 
   return NewDD;
 }
 
 Decl *TemplateDeclInstantiator::VisitVarDecl(VarDecl *D) {
   return VisitVarDecl(D, /*InstantiatingVarTemplate=*/false);
 }
 
 Decl *TemplateDeclInstantiator::VisitVarDecl(VarDecl *D,
                                              bool InstantiatingVarTemplate,
                                              ArrayRef<BindingDecl*> *Bindings) {
 
   // Do substitution on the type of the declaration
   TypeSourceInfo *DI = SemaRef.SubstType(
       D->getTypeSourceInfo(), TemplateArgs, D->getTypeSpecStartLoc(),
       D->getDeclName(), /*AllowDeducedTST*/true);
   if (!DI)
     return nullptr;
 
   if (DI->getType()->isFunctionType()) {
     SemaRef.Diag(D->getLocation(), diag::err_variable_instantiates_to_function)
       << D->isStaticDataMember() << DI->getType();
     return nullptr;
   }
 
   DeclContext *DC = Owner;
   if (D->isLocalExternDecl())
     SemaRef.adjustContextForLocalExternDecl(DC);
 
   // Build the instantiated declaration.
   VarDecl *Var;
   if (Bindings)
     Var = DecompositionDecl::Create(SemaRef.Context, DC, D->getInnerLocStart(),
                                     D->getLocation(), DI->getType(), DI,
                                     D->getStorageClass(), *Bindings);
   else
     Var = VarDecl::Create(SemaRef.Context, DC, D->getInnerLocStart(),
                           D->getLocation(), D->getIdentifier(), DI->getType(),
                           DI, D->getStorageClass());
 
   // In ARC, infer 'retaining' for variables of retainable type.
   if (SemaRef.getLangOpts().ObjCAutoRefCount &&
       SemaRef.inferObjCARCLifetime(Var))
     Var->setInvalidDecl();
 
   if (SemaRef.getLangOpts().OpenCL)
     SemaRef.deduceOpenCLAddressSpace(Var);
 
   // Substitute the nested name specifier, if any.
   if (SubstQualifier(D, Var))
     return nullptr;
 
   SemaRef.BuildVariableInstantiation(Var, D, TemplateArgs, LateAttrs, Owner,
                                      StartingScope, InstantiatingVarTemplate);
   if (D->isNRVOVariable() && !Var->isInvalidDecl()) {
     QualType RT;
     if (auto *F = dyn_cast<FunctionDecl>(DC))
       RT = F->getReturnType();
     else if (isa<BlockDecl>(DC))
       RT = cast<FunctionType>(SemaRef.getCurBlock()->FunctionType)
                ->getReturnType();
     else
       llvm_unreachable("Unknown context type");
 
     // This is the last chance we have of checking copy elision eligibility
     // for functions in dependent contexts. The sema actions for building
     // the return statement during template instantiation will have no effect
     // regarding copy elision, since NRVO propagation runs on the scope exit
     // actions, and these are not run on instantiation.
     // This might run through some VarDecls which were returned from non-taken
     // 'if constexpr' branches, and these will end up being constructed on the
     // return slot even if they will never be returned, as a sort of accidental
     // 'optimization'. Notably, functions with 'auto' return types won't have it
     // deduced by this point. Coupled with the limitation described
     // previously, this makes it very hard to support copy elision for these.
     Sema::NamedReturnInfo Info = SemaRef.getNamedReturnInfo(Var);
     bool NRVO = SemaRef.getCopyElisionCandidate(Info, RT) != nullptr;
     Var->setNRVOVariable(NRVO);
   }
 
   Var->setImplicit(D->isImplicit());
 
   if (Var->isStaticLocal())
     SemaRef.CheckStaticLocalForDllExport(Var);
 
   if (Var->getTLSKind())
     SemaRef.CheckThreadLocalForLargeAlignment(Var);
 
   return Var;
 }
 
 Decl *TemplateDeclInstantiator::VisitAccessSpecDecl(AccessSpecDecl *D) {
   AccessSpecDecl* AD
     = AccessSpecDecl::Create(SemaRef.Context, D->getAccess(), Owner,
                              D->getAccessSpecifierLoc(), D->getColonLoc());
   Owner->addHiddenDecl(AD);
   return AD;
 }
 
 Decl *TemplateDeclInstantiator::VisitFieldDecl(FieldDecl *D) {
   bool Invalid = false;
   TypeSourceInfo *DI = D->getTypeSourceInfo();
   if (DI->getType()->isInstantiationDependentType() ||
       DI->getType()->isVariablyModifiedType())  {
     DI = SemaRef.SubstType(DI, TemplateArgs,
                            D->getLocation(), D->getDeclName());
     if (!DI) {
       DI = D->getTypeSourceInfo();
       Invalid = true;
     } else if (DI->getType()->isFunctionType()) {
       // C++ [temp.arg.type]p3:
       //   If a declaration acquires a function type through a type
       //   dependent on a template-parameter and this causes a
       //   declaration that does not use the syntactic form of a
       //   function declarator to have function type, the program is
       //   ill-formed.
       SemaRef.Diag(D->getLocation(), diag::err_field_instantiates_to_function)
         << DI->getType();
       Invalid = true;
     }
   } else {
     SemaRef.MarkDeclarationsReferencedInType(D->getLocation(), DI->getType());
   }
 
   Expr *BitWidth = D->getBitWidth();
   if (Invalid)
     BitWidth = nullptr;
   else if (BitWidth) {
     // The bit-width expression is a constant expression.
     EnterExpressionEvaluationContext Unevaluated(
         SemaRef, Sema::ExpressionEvaluationContext::ConstantEvaluated);
 
     ExprResult InstantiatedBitWidth
       = SemaRef.SubstExpr(BitWidth, TemplateArgs);
     if (InstantiatedBitWidth.isInvalid()) {
       Invalid = true;
       BitWidth = nullptr;
     } else
       BitWidth = InstantiatedBitWidth.getAs<Expr>();
   }
 
   FieldDecl *Field = SemaRef.CheckFieldDecl(D->getDeclName(),
                                             DI->getType(), DI,
                                             cast<RecordDecl>(Owner),
                                             D->getLocation(),
                                             D->isMutable(),
                                             BitWidth,
                                             D->getInClassInitStyle(),
                                             D->getInnerLocStart(),
                                             D->getAccess(),
                                             nullptr);
   if (!Field) {
     cast<Decl>(Owner)->setInvalidDecl();
     return nullptr;
   }
 
   SemaRef.InstantiateAttrs(TemplateArgs, D, Field, LateAttrs, StartingScope);
 
   if (Field->hasAttrs())
     SemaRef.CheckAlignasUnderalignment(Field);
 
   if (Invalid)
     Field->setInvalidDecl();
 
   if (!Field->getDeclName()) {
     // Keep track of where this decl came from.
     SemaRef.Context.setInstantiatedFromUnnamedFieldDecl(Field, D);
   }
   if (CXXRecordDecl *Parent= dyn_cast<CXXRecordDecl>(Field->getDeclContext())) {
     if (Parent->isAnonymousStructOrUnion() &&
         Parent->getRedeclContext()->isFunctionOrMethod())
       SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, Field);
   }
 
   Field->setImplicit(D->isImplicit());
   Field->setAccess(D->getAccess());
   Owner->addDecl(Field);
 
   return Field;
 }
 
 Decl *TemplateDeclInstantiator::VisitMSPropertyDecl(MSPropertyDecl *D) {
   bool Invalid = false;
   TypeSourceInfo *DI = D->getTypeSourceInfo();
 
   if (DI->getType()->isVariablyModifiedType()) {
     SemaRef.Diag(D->getLocation(), diag::err_property_is_variably_modified)
       << D;
     Invalid = true;
   } else if (DI->getType()->isInstantiationDependentType())  {
     DI = SemaRef.SubstType(DI, TemplateArgs,
                            D->getLocation(), D->getDeclName());
     if (!DI) {
       DI = D->getTypeSourceInfo();
       Invalid = true;
     } else if (DI->getType()->isFunctionType()) {
       // C++ [temp.arg.type]p3:
       //   If a declaration acquires a function type through a type
       //   dependent on a template-parameter and this causes a
       //   declaration that does not use the syntactic form of a
       //   function declarator to have function type, the program is
       //   ill-formed.
       SemaRef.Diag(D->getLocation(), diag::err_field_instantiates_to_function)
       << DI->getType();
       Invalid = true;
     }
   } else {
     SemaRef.MarkDeclarationsReferencedInType(D->getLocation(), DI->getType());
   }
 
   MSPropertyDecl *Property = MSPropertyDecl::Create(
       SemaRef.Context, Owner, D->getLocation(), D->getDeclName(), DI->getType(),
       DI, D->getBeginLoc(), D->getGetterId(), D->getSetterId());
 
   SemaRef.InstantiateAttrs(TemplateArgs, D, Property, LateAttrs,
                            StartingScope);
 
   if (Invalid)
     Property->setInvalidDecl();
 
   Property->setAccess(D->getAccess());
   Owner->addDecl(Property);
 
   return Property;
 }
 
 Decl *TemplateDeclInstantiator::VisitIndirectFieldDecl(IndirectFieldDecl *D) {
   NamedDecl **NamedChain =
     new (SemaRef.Context)NamedDecl*[D->getChainingSize()];
 
   int i = 0;
   for (auto *PI : D->chain()) {
     NamedDecl *Next = SemaRef.FindInstantiatedDecl(D->getLocation(), PI,
                                               TemplateArgs);
     if (!Next)
       return nullptr;
 
     NamedChain[i++] = Next;
   }
 
   QualType T = cast<FieldDecl>(NamedChain[i-1])->getType();
   IndirectFieldDecl *IndirectField = IndirectFieldDecl::Create(
       SemaRef.Context, Owner, D->getLocation(), D->getIdentifier(), T,
       {NamedChain, D->getChainingSize()});
 
   for (const auto *Attr : D->attrs())
     IndirectField->addAttr(Attr->clone(SemaRef.Context));
 
   IndirectField->setImplicit(D->isImplicit());
   IndirectField->setAccess(D->getAccess());
   Owner->addDecl(IndirectField);
   return IndirectField;
 }
 
 Decl *TemplateDeclInstantiator::VisitFriendDecl(FriendDecl *D) {
   // Handle friend type expressions by simply substituting template
   // parameters into the pattern type and checking the result.
   if (TypeSourceInfo *Ty = D->getFriendType()) {
     TypeSourceInfo *InstTy;
     // If this is an unsupported friend, don't bother substituting template
     // arguments into it. The actual type referred to won't be used by any
     // parts of Clang, and may not be valid for instantiating. Just use the
     // same info for the instantiated friend.
     if (D->isUnsupportedFriend()) {
       InstTy = Ty;
     } else {
       InstTy = SemaRef.SubstType(Ty, TemplateArgs,
                                  D->getLocation(), DeclarationName());
     }
     if (!InstTy)
       return nullptr;
 
     FriendDecl *FD = SemaRef.CheckFriendTypeDecl(D->getBeginLoc(),
                                                  D->getFriendLoc(), InstTy);
     if (!FD)
       return nullptr;
 
     FD->setAccess(AS_public);
     FD->setUnsupportedFriend(D->isUnsupportedFriend());
     Owner->addDecl(FD);
     return FD;
   }
 
   NamedDecl *ND = D->getFriendDecl();
   assert(ND && "friend decl must be a decl or a type!");
 
   // All of the Visit implementations for the various potential friend
   // declarations have to be carefully written to work for friend
   // objects, with the most important detail being that the target
   // decl should almost certainly not be placed in Owner.
   Decl *NewND = Visit(ND);
   if (!NewND) return nullptr;
 
   FriendDecl *FD =
     FriendDecl::Create(SemaRef.Context, Owner, D->getLocation(),
                        cast<NamedDecl>(NewND), D->getFriendLoc());
   FD->setAccess(AS_public);
   FD->setUnsupportedFriend(D->isUnsupportedFriend());
   Owner->addDecl(FD);
   return FD;
 }
 
 Decl *TemplateDeclInstantiator::VisitStaticAssertDecl(StaticAssertDecl *D) {
   Expr *AssertExpr = D->getAssertExpr();
 
   // The expression in a static assertion is a constant expression.
   EnterExpressionEvaluationContext Unevaluated(
       SemaRef, Sema::ExpressionEvaluationContext::ConstantEvaluated);
 
   ExprResult InstantiatedAssertExpr
     = SemaRef.SubstExpr(AssertExpr, TemplateArgs);
   if (InstantiatedAssertExpr.isInvalid())
     return nullptr;
 
   ExprResult InstantiatedMessageExpr =
       SemaRef.SubstExpr(D->getMessage(), TemplateArgs);
   if (InstantiatedMessageExpr.isInvalid())
     return nullptr;
 
   return SemaRef.BuildStaticAssertDeclaration(
       D->getLocation(), InstantiatedAssertExpr.get(),
       InstantiatedMessageExpr.get(), D->getRParenLoc(), D->isFailed());
 }
 
 Decl *TemplateDeclInstantiator::VisitEnumDecl(EnumDecl *D) {
   EnumDecl *PrevDecl = nullptr;
   if (EnumDecl *PatternPrev = getPreviousDeclForInstantiation(D)) {
     NamedDecl *Prev = SemaRef.FindInstantiatedDecl(D->getLocation(),
                                                    PatternPrev,
                                                    TemplateArgs);
     if (!Prev) return nullptr;
     PrevDecl = cast<EnumDecl>(Prev);
   }
 
   EnumDecl *Enum =
       EnumDecl::Create(SemaRef.Context, Owner, D->getBeginLoc(),
                        D->getLocation(), D->getIdentifier(), PrevDecl,
                        D->isScoped(), D->isScopedUsingClassTag(), D->isFixed());
   if (D->isFixed()) {
     if (TypeSourceInfo *TI = D->getIntegerTypeSourceInfo()) {
       // If we have type source information for the underlying type, it means it
       // has been explicitly set by the user. Perform substitution on it before
       // moving on.
       SourceLocation UnderlyingLoc = TI->getTypeLoc().getBeginLoc();
       TypeSourceInfo *NewTI = SemaRef.SubstType(TI, TemplateArgs, UnderlyingLoc,
                                                 DeclarationName());
       if (!NewTI || SemaRef.CheckEnumUnderlyingType(NewTI))
         Enum->setIntegerType(SemaRef.Context.IntTy);
       else
         Enum->setIntegerTypeSourceInfo(NewTI);
     } else {
       assert(!D->getIntegerType()->isDependentType()
              && "Dependent type without type source info");
       Enum->setIntegerType(D->getIntegerType());
     }
   }
 
   SemaRef.InstantiateAttrs(TemplateArgs, D, Enum);
 
   Enum->setInstantiationOfMemberEnum(D, TSK_ImplicitInstantiation);
   Enum->setAccess(D->getAccess());
   // Forward the mangling number from the template to the instantiated decl.
   SemaRef.Context.setManglingNumber(Enum, SemaRef.Context.getManglingNumber(D));
   // See if the old tag was defined along with a declarator.
   // If it did, mark the new tag as being associated with that declarator.
   if (DeclaratorDecl *DD = SemaRef.Context.getDeclaratorForUnnamedTagDecl(D))
     SemaRef.Context.addDeclaratorForUnnamedTagDecl(Enum, DD);
   // See if the old tag was defined along with a typedef.
   // If it did, mark the new tag as being associated with that typedef.
   if (TypedefNameDecl *TND = SemaRef.Context.getTypedefNameForUnnamedTagDecl(D))
     SemaRef.Context.addTypedefNameForUnnamedTagDecl(Enum, TND);
   if (SubstQualifier(D, Enum)) return nullptr;
   Owner->addDecl(Enum);
 
   EnumDecl *Def = D->getDefinition();
   if (Def && Def != D) {
     // If this is an out-of-line definition of an enum member template, check
     // that the underlying types match in the instantiation of both
     // declarations.
     if (TypeSourceInfo *TI = Def->getIntegerTypeSourceInfo()) {
       SourceLocation UnderlyingLoc = TI->getTypeLoc().getBeginLoc();
       QualType DefnUnderlying =
         SemaRef.SubstType(TI->getType(), TemplateArgs,
                           UnderlyingLoc, DeclarationName());
       SemaRef.CheckEnumRedeclaration(Def->getLocation(), Def->isScoped(),
                                      DefnUnderlying, /*IsFixed=*/true, Enum);
     }
   }
 
   // C++11 [temp.inst]p1: The implicit instantiation of a class template
   // specialization causes the implicit instantiation of the declarations, but
   // not the definitions of scoped member enumerations.
   //
   // DR1484 clarifies that enumeration definitions inside of a template
   // declaration aren't considered entities that can be separately instantiated
   // from the rest of the entity they are declared inside of.
   if (isDeclWithinFunction(D) ? D == Def : Def && !Enum->isScoped()) {
     SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, Enum);
     InstantiateEnumDefinition(Enum, Def);
   }
 
   return Enum;
 }
 
 void TemplateDeclInstantiator::InstantiateEnumDefinition(
     EnumDecl *Enum, EnumDecl *Pattern) {
   Enum->startDefinition();
 
   // Update the location to refer to the definition.
   Enum->setLocation(Pattern->getLocation());
 
   SmallVector<Decl*, 4> Enumerators;
 
   EnumConstantDecl *LastEnumConst = nullptr;
   for (auto *EC : Pattern->enumerators()) {
     // The specified value for the enumerator.
     ExprResult Value((Expr *)nullptr);
     if (Expr *UninstValue = EC->getInitExpr()) {
       // The enumerator's value expression is a constant expression.
       EnterExpressionEvaluationContext Unevaluated(
           SemaRef, Sema::ExpressionEvaluationContext::ConstantEvaluated);
 
       Value = SemaRef.SubstExpr(UninstValue, TemplateArgs);
     }
 
     // Drop the initial value and continue.
     bool isInvalid = false;
     if (Value.isInvalid()) {
       Value = nullptr;
       isInvalid = true;
     }
 
     EnumConstantDecl *EnumConst
       = SemaRef.CheckEnumConstant(Enum, LastEnumConst,
                                   EC->getLocation(), EC->getIdentifier(),
                                   Value.get());
 
     if (isInvalid) {
       if (EnumConst)
         EnumConst->setInvalidDecl();
       Enum->setInvalidDecl();
     }
 
     if (EnumConst) {
       SemaRef.InstantiateAttrs(TemplateArgs, EC, EnumConst);
 
       EnumConst->setAccess(Enum->getAccess());
       Enum->addDecl(EnumConst);
       Enumerators.push_back(EnumConst);
       LastEnumConst = EnumConst;
 
       if (Pattern->getDeclContext()->isFunctionOrMethod() &&
           !Enum->isScoped()) {
         // If the enumeration is within a function or method, record the enum
         // constant as a local.
         SemaRef.CurrentInstantiationScope->InstantiatedLocal(EC, EnumConst);
       }
     }
   }
 
   SemaRef.ActOnEnumBody(Enum->getLocation(), Enum->getBraceRange(), Enum,
                         Enumerators, nullptr, ParsedAttributesView());
 }
 
 Decl *TemplateDeclInstantiator::VisitEnumConstantDecl(EnumConstantDecl *D) {
   llvm_unreachable("EnumConstantDecls can only occur within EnumDecls.");
 }
 
 Decl *
 TemplateDeclInstantiator::VisitBuiltinTemplateDecl(BuiltinTemplateDecl *D) {
   llvm_unreachable("BuiltinTemplateDecls cannot be instantiated.");
 }
 
 Decl *TemplateDeclInstantiator::VisitClassTemplateDecl(ClassTemplateDecl *D) {
   bool isFriend = (D->getFriendObjectKind() != Decl::FOK_None);
 
   // Create a local instantiation scope for this class template, which
   // will contain the instantiations of the template parameters.
   LocalInstantiationScope Scope(SemaRef);
   TemplateParameterList *TempParams = D->getTemplateParameters();
   TemplateParameterList *InstParams = SubstTemplateParams(TempParams);
   if (!InstParams)
     return nullptr;
 
   CXXRecordDecl *Pattern = D->getTemplatedDecl();
 
   // Instantiate the qualifier.  We have to do this first in case
   // we're a friend declaration, because if we are then we need to put
   // the new declaration in the appropriate context.
   NestedNameSpecifierLoc QualifierLoc = Pattern->getQualifierLoc();
   if (QualifierLoc) {
     QualifierLoc = SemaRef.SubstNestedNameSpecifierLoc(QualifierLoc,
                                                        TemplateArgs);
     if (!QualifierLoc)
       return nullptr;
   }
 
   CXXRecordDecl *PrevDecl = nullptr;
   ClassTemplateDecl *PrevClassTemplate = nullptr;
 
   if (!isFriend && getPreviousDeclForInstantiation(Pattern)) {
     DeclContext::lookup_result Found = Owner->lookup(Pattern->getDeclName());
     if (!Found.empty()) {
       PrevClassTemplate = dyn_cast<ClassTemplateDecl>(Found.front());
       if (PrevClassTemplate)
         PrevDecl = PrevClassTemplate->getTemplatedDecl();
     }
   }
 
   // If this isn't a friend, then it's a member template, in which
   // case we just want to build the instantiation in the
   // specialization.  If it is a friend, we want to build it in
   // the appropriate context.
   DeclContext *DC = Owner;
   if (isFriend) {
     if (QualifierLoc) {
       CXXScopeSpec SS;
       SS.Adopt(QualifierLoc);
       DC = SemaRef.computeDeclContext(SS);
       if (!DC) return nullptr;
     } else {
       DC = SemaRef.FindInstantiatedContext(Pattern->getLocation(),
                                            Pattern->getDeclContext(),
                                            TemplateArgs);
     }
 
     // Look for a previous declaration of the template in the owning
     // context.
     LookupResult R(SemaRef, Pattern->getDeclName(), Pattern->getLocation(),
                    Sema::LookupOrdinaryName,
                    SemaRef.forRedeclarationInCurContext());
     SemaRef.LookupQualifiedName(R, DC);
 
     if (R.isSingleResult()) {
       PrevClassTemplate = R.getAsSingle<ClassTemplateDecl>();
       if (PrevClassTemplate)
         PrevDecl = PrevClassTemplate->getTemplatedDecl();
     }
 
     if (!PrevClassTemplate && QualifierLoc) {
       SemaRef.Diag(Pattern->getLocation(), diag::err_not_tag_in_scope)
         << D->getTemplatedDecl()->getTagKind() << Pattern->getDeclName() << DC
         << QualifierLoc.getSourceRange();
       return nullptr;
     }
   }
 
   CXXRecordDecl *RecordInst = CXXRecordDecl::Create(
       SemaRef.Context, Pattern->getTagKind(), DC, Pattern->getBeginLoc(),
       Pattern->getLocation(), Pattern->getIdentifier(), PrevDecl,
       /*DelayTypeCreation=*/true);
   if (QualifierLoc)
     RecordInst->setQualifierInfo(QualifierLoc);
 
   SemaRef.InstantiateAttrsForDecl(TemplateArgs, Pattern, RecordInst, LateAttrs,
                                                               StartingScope);
 
   ClassTemplateDecl *Inst
     = ClassTemplateDecl::Create(SemaRef.Context, DC, D->getLocation(),
                                 D->getIdentifier(), InstParams, RecordInst);
   RecordInst->setDescribedClassTemplate(Inst);
 
   if (isFriend) {
     assert(!Owner->isDependentContext());
     Inst->setLexicalDeclContext(Owner);
     RecordInst->setLexicalDeclContext(Owner);
 
     if (PrevClassTemplate) {
       Inst->setCommonPtr(PrevClassTemplate->getCommonPtr());
       RecordInst->setTypeForDecl(
           PrevClassTemplate->getTemplatedDecl()->getTypeForDecl());
       const ClassTemplateDecl *MostRecentPrevCT =
           PrevClassTemplate->getMostRecentDecl();
       TemplateParameterList *PrevParams =
           MostRecentPrevCT->getTemplateParameters();
 
       // Make sure the parameter lists match.
       if (!SemaRef.TemplateParameterListsAreEqual(
               RecordInst, InstParams, MostRecentPrevCT->getTemplatedDecl(),
               PrevParams, true, Sema::TPL_TemplateMatch))
         return nullptr;
 
       // Do some additional validation, then merge default arguments
       // from the existing declarations.
       if (SemaRef.CheckTemplateParameterList(InstParams, PrevParams,
                                              Sema::TPC_ClassTemplate))
         return nullptr;
 
       Inst->setAccess(PrevClassTemplate->getAccess());
     } else {
       Inst->setAccess(D->getAccess());
     }
 
     Inst->setObjectOfFriendDecl();
     // TODO: do we want to track the instantiation progeny of this
     // friend target decl?
   } else {
     Inst->setAccess(D->getAccess());
     if (!PrevClassTemplate)
       Inst->setInstantiatedFromMemberTemplate(D);
   }
 
   Inst->setPreviousDecl(PrevClassTemplate);
 
   // Trigger creation of the type for the instantiation.
   SemaRef.Context.getInjectedClassNameType(
       RecordInst, Inst->getInjectedClassNameSpecialization());
 
   // Finish handling of friends.
   if (isFriend) {
     DC->makeDeclVisibleInContext(Inst);
     return Inst;
   }
 
   if (D->isOutOfLine()) {
     Inst->setLexicalDeclContext(D->getLexicalDeclContext());
     RecordInst->setLexicalDeclContext(D->getLexicalDeclContext());
   }
 
   Owner->addDecl(Inst);
 
   if (!PrevClassTemplate) {
     // Queue up any out-of-line partial specializations of this member
     // class template; the client will force their instantiation once
     // the enclosing class has been instantiated.
     SmallVector<ClassTemplatePartialSpecializationDecl *, 4> PartialSpecs;
     D->getPartialSpecializations(PartialSpecs);
     for (unsigned I = 0, N = PartialSpecs.size(); I != N; ++I)
       if (PartialSpecs[I]->getFirstDecl()->isOutOfLine())
         OutOfLinePartialSpecs.push_back(std::make_pair(Inst, PartialSpecs[I]));
   }
 
   return Inst;
 }
 
 Decl *
 TemplateDeclInstantiator::VisitClassTemplatePartialSpecializationDecl(
                                    ClassTemplatePartialSpecializationDecl *D) {
   ClassTemplateDecl *ClassTemplate = D->getSpecializedTemplate();
 
   // Lookup the already-instantiated declaration in the instantiation
   // of the class template and return that.
   DeclContext::lookup_result Found
     = Owner->lookup(ClassTemplate->getDeclName());
   if (Found.empty())
     return nullptr;
 
   ClassTemplateDecl *InstClassTemplate
     = dyn_cast<ClassTemplateDecl>(Found.front());
   if (!InstClassTemplate)
     return nullptr;
 
   if (ClassTemplatePartialSpecializationDecl *Result
         = InstClassTemplate->findPartialSpecInstantiatedFromMember(D))
     return Result;
 
   return InstantiateClassTemplatePartialSpecialization(InstClassTemplate, D);
 }
 
 Decl *TemplateDeclInstantiator::VisitVarTemplateDecl(VarTemplateDecl *D) {
   assert(D->getTemplatedDecl()->isStaticDataMember() &&
          "Only static data member templates are allowed.");
 
   // Create a local instantiation scope for this variable template, which
   // will contain the instantiations of the template parameters.
   LocalInstantiationScope Scope(SemaRef);
   TemplateParameterList *TempParams = D->getTemplateParameters();
   TemplateParameterList *InstParams = SubstTemplateParams(TempParams);
   if (!InstParams)
     return nullptr;
 
   VarDecl *Pattern = D->getTemplatedDecl();
   VarTemplateDecl *PrevVarTemplate = nullptr;
 
   if (getPreviousDeclForInstantiation(Pattern)) {
     DeclContext::lookup_result Found = Owner->lookup(Pattern->getDeclName());
     if (!Found.empty())
       PrevVarTemplate = dyn_cast<VarTemplateDecl>(Found.front());
   }
 
   VarDecl *VarInst =
       cast_or_null<VarDecl>(VisitVarDecl(Pattern,
                                          /*InstantiatingVarTemplate=*/true));
   if (!VarInst) return nullptr;
 
   DeclContext *DC = Owner;
 
   VarTemplateDecl *Inst = VarTemplateDecl::Create(
       SemaRef.Context, DC, D->getLocation(), D->getIdentifier(), InstParams,
       VarInst);
   VarInst->setDescribedVarTemplate(Inst);
   Inst->setPreviousDecl(PrevVarTemplate);
 
   Inst->setAccess(D->getAccess());
   if (!PrevVarTemplate)
     Inst->setInstantiatedFromMemberTemplate(D);
 
   if (D->isOutOfLine()) {
     Inst->setLexicalDeclContext(D->getLexicalDeclContext());
     VarInst->setLexicalDeclContext(D->getLexicalDeclContext());
   }
 
   Owner->addDecl(Inst);
 
   if (!PrevVarTemplate) {
     // Queue up any out-of-line partial specializations of this member
     // variable template; the client will force their instantiation once
     // the enclosing class has been instantiated.
     SmallVector<VarTemplatePartialSpecializationDecl *, 4> PartialSpecs;
     D->getPartialSpecializations(PartialSpecs);
     for (unsigned I = 0, N = PartialSpecs.size(); I != N; ++I)
       if (PartialSpecs[I]->getFirstDecl()->isOutOfLine())
         OutOfLineVarPartialSpecs.push_back(
             std::make_pair(Inst, PartialSpecs[I]));
   }
 
   return Inst;
 }
 
 Decl *TemplateDeclInstantiator::VisitVarTemplatePartialSpecializationDecl(
     VarTemplatePartialSpecializationDecl *D) {
   assert(D->isStaticDataMember() &&
          "Only static data member templates are allowed.");
 
   VarTemplateDecl *VarTemplate = D->getSpecializedTemplate();
 
   // Lookup the already-instantiated declaration and return that.
   DeclContext::lookup_result Found = Owner->lookup(VarTemplate->getDeclName());
   assert(!Found.empty() && "Instantiation found nothing?");
 
   VarTemplateDecl *InstVarTemplate = dyn_cast<VarTemplateDecl>(Found.front());
   assert(InstVarTemplate && "Instantiation did not find a variable template?");
 
   if (VarTemplatePartialSpecializationDecl *Result =
           InstVarTemplate->findPartialSpecInstantiatedFromMember(D))
     return Result;
 
   return InstantiateVarTemplatePartialSpecialization(InstVarTemplate, D);
 }
 
 Decl *
 TemplateDeclInstantiator::VisitFunctionTemplateDecl(FunctionTemplateDecl *D) {
   // Create a local instantiation scope for this function template, which
   // will contain the instantiations of the template parameters and then get
   // merged with the local instantiation scope for the function template
   // itself.
   LocalInstantiationScope Scope(SemaRef);
   Sema::ConstraintEvalRAII<TemplateDeclInstantiator> RAII(*this);
 
   TemplateParameterList *TempParams = D->getTemplateParameters();
   TemplateParameterList *InstParams = SubstTemplateParams(TempParams);
   if (!InstParams)
     return nullptr;
 
   FunctionDecl *Instantiated = nullptr;
   if (CXXMethodDecl *DMethod = dyn_cast<CXXMethodDecl>(D->getTemplatedDecl()))
     Instantiated = cast_or_null<FunctionDecl>(VisitCXXMethodDecl(DMethod,
                                                                  InstParams));
   else
     Instantiated = cast_or_null<FunctionDecl>(VisitFunctionDecl(
                                                           D->getTemplatedDecl(),
                                                                 InstParams));
 
   if (!Instantiated)
     return nullptr;
 
   // Link the instantiated function template declaration to the function
   // template from which it was instantiated.
   FunctionTemplateDecl *InstTemplate
     = Instantiated->getDescribedFunctionTemplate();
   InstTemplate->setAccess(D->getAccess());
   assert(InstTemplate &&
          "VisitFunctionDecl/CXXMethodDecl didn't create a template!");
 
   bool isFriend = (InstTemplate->getFriendObjectKind() != Decl::FOK_None);
 
   // Link the instantiation back to the pattern *unless* this is a
   // non-definition friend declaration.
   if (!InstTemplate->getInstantiatedFromMemberTemplate() &&
       !(isFriend && !D->getTemplatedDecl()->isThisDeclarationADefinition()))
     InstTemplate->setInstantiatedFromMemberTemplate(D);
 
   // Make declarations visible in the appropriate context.
   if (!isFriend) {
     Owner->addDecl(InstTemplate);
   } else if (InstTemplate->getDeclContext()->isRecord() &&
              !getPreviousDeclForInstantiation(D)) {
     SemaRef.CheckFriendAccess(InstTemplate);
   }
 
   return InstTemplate;
 }
 
 Decl *TemplateDeclInstantiator::VisitCXXRecordDecl(CXXRecordDecl *D) {
   CXXRecordDecl *PrevDecl = nullptr;
   if (CXXRecordDecl *PatternPrev = getPreviousDeclForInstantiation(D)) {
     NamedDecl *Prev = SemaRef.FindInstantiatedDecl(D->getLocation(),
                                                    PatternPrev,
                                                    TemplateArgs);
     if (!Prev) return nullptr;
     PrevDecl = cast<CXXRecordDecl>(Prev);
   }
 
   CXXRecordDecl *Record = nullptr;
   bool IsInjectedClassName = D->isInjectedClassName();
   if (D->isLambda())
     Record = CXXRecordDecl::CreateLambda(
         SemaRef.Context, Owner, D->getLambdaTypeInfo(), D->getLocation(),
         D->getLambdaDependencyKind(), D->isGenericLambda(),
         D->getLambdaCaptureDefault());
   else
     Record = CXXRecordDecl::Create(SemaRef.Context, D->getTagKind(), Owner,
                                    D->getBeginLoc(), D->getLocation(),
                                    D->getIdentifier(), PrevDecl,
                                    /*DelayTypeCreation=*/IsInjectedClassName);
   // Link the type of the injected-class-name to that of the outer class.
   if (IsInjectedClassName)
     (void)SemaRef.Context.getTypeDeclType(Record, cast<CXXRecordDecl>(Owner));
 
   // Substitute the nested name specifier, if any.
   if (SubstQualifier(D, Record))
     return nullptr;
 
   SemaRef.InstantiateAttrsForDecl(TemplateArgs, D, Record, LateAttrs,
                                                               StartingScope);
 
   Record->setImplicit(D->isImplicit());
   // FIXME: Check against AS_none is an ugly hack to work around the issue that
   // the tag decls introduced by friend class declarations don't have an access
   // specifier. Remove once this area of the code gets sorted out.
   if (D->getAccess() != AS_none)
     Record->setAccess(D->getAccess());
   if (!IsInjectedClassName)
     Record->setInstantiationOfMemberClass(D, TSK_ImplicitInstantiation);
 
   // If the original function was part of a friend declaration,
   // inherit its namespace state.
   if (D->getFriendObjectKind())
     Record->setObjectOfFriendDecl();
 
   // Make sure that anonymous structs and unions are recorded.
   if (D->isAnonymousStructOrUnion())
     Record->setAnonymousStructOrUnion(true);
 
   if (D->isLocalClass())
     SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, Record);
 
   // Forward the mangling number from the template to the instantiated decl.
   SemaRef.Context.setManglingNumber(Record,
                                     SemaRef.Context.getManglingNumber(D));
 
   // See if the old tag was defined along with a declarator.
   // If it did, mark the new tag as being associated with that declarator.
   if (DeclaratorDecl *DD = SemaRef.Context.getDeclaratorForUnnamedTagDecl(D))
     SemaRef.Context.addDeclaratorForUnnamedTagDecl(Record, DD);
 
   // See if the old tag was defined along with a typedef.
   // If it did, mark the new tag as being associated with that typedef.
   if (TypedefNameDecl *TND = SemaRef.Context.getTypedefNameForUnnamedTagDecl(D))
     SemaRef.Context.addTypedefNameForUnnamedTagDecl(Record, TND);
 
   Owner->addDecl(Record);
 
   // DR1484 clarifies that the members of a local class are instantiated as part
   // of the instantiation of their enclosing entity.
   if (D->isCompleteDefinition() && D->isLocalClass()) {
     Sema::LocalEagerInstantiationScope LocalInstantiations(SemaRef);
 
     SemaRef.InstantiateClass(D->getLocation(), Record, D, TemplateArgs,
                              TSK_ImplicitInstantiation,
                              /*Complain=*/true);
 
     // For nested local classes, we will instantiate the members when we
     // reach the end of the outermost (non-nested) local class.
     if (!D->isCXXClassMember())
       SemaRef.InstantiateClassMembers(D->getLocation(), Record, TemplateArgs,
                                       TSK_ImplicitInstantiation);
 
     // This class may have local implicit instantiations that need to be
     // performed within this scope.
     LocalInstantiations.perform();
   }
 
   SemaRef.DiagnoseUnusedNestedTypedefs(Record);
 
   if (IsInjectedClassName)
     assert(Record->isInjectedClassName() && "Broken injected-class-name");
 
   return Record;
 }
 
 /// Adjust the given function type for an instantiation of the
 /// given declaration, to cope with modifications to the function's type that
 /// aren't reflected in the type-source information.
 ///
 /// \param D The declaration we're instantiating.
 /// \param TInfo The already-instantiated type.
 static QualType adjustFunctionTypeForInstantiation(ASTContext &Context,
                                                    FunctionDecl *D,
                                                    TypeSourceInfo *TInfo) {
   const FunctionProtoType *OrigFunc
     = D->getType()->castAs<FunctionProtoType>();
   const FunctionProtoType *NewFunc
     = TInfo->getType()->castAs<FunctionProtoType>();
   if (OrigFunc->getExtInfo() == NewFunc->getExtInfo())
     return TInfo->getType();
 
   FunctionProtoType::ExtProtoInfo NewEPI = NewFunc->getExtProtoInfo();
   NewEPI.ExtInfo = OrigFunc->getExtInfo();
   return Context.getFunctionType(NewFunc->getReturnType(),
                                  NewFunc->getParamTypes(), NewEPI);
 }
 
 /// Normal class members are of more specific types and therefore
 /// don't make it here.  This function serves three purposes:
 ///   1) instantiating function templates
 ///   2) substituting friend and local function declarations
 ///   3) substituting deduction guide declarations for nested class templates
 Decl *TemplateDeclInstantiator::VisitFunctionDecl(
     FunctionDecl *D, TemplateParameterList *TemplateParams,
     RewriteKind FunctionRewriteKind) {
   // Check whether there is already a function template specialization for
   // this declaration.
   FunctionTemplateDecl *FunctionTemplate = D->getDescribedFunctionTemplate();
   if (FunctionTemplate && !TemplateParams) {
     ArrayRef<TemplateArgument> Innermost = TemplateArgs.getInnermost();
 
     void *InsertPos = nullptr;
     FunctionDecl *SpecFunc
       = FunctionTemplate->findSpecialization(Innermost, InsertPos);
 
     // If we already have a function template specialization, return it.
     if (SpecFunc)
       return SpecFunc;
   }
 
   bool isFriend;
   if (FunctionTemplate)
     isFriend = (FunctionTemplate->getFriendObjectKind() != Decl::FOK_None);
   else
     isFriend = (D->getFriendObjectKind() != Decl::FOK_None);
 
   bool MergeWithParentScope = (TemplateParams != nullptr) ||
     Owner->isFunctionOrMethod() ||
     !(isa<Decl>(Owner) &&
       cast<Decl>(Owner)->isDefinedOutsideFunctionOrMethod());
   LocalInstantiationScope Scope(SemaRef, MergeWithParentScope);
 
   ExplicitSpecifier InstantiatedExplicitSpecifier;
   if (auto *DGuide = dyn_cast<CXXDeductionGuideDecl>(D)) {
     InstantiatedExplicitSpecifier = instantiateExplicitSpecifier(
         SemaRef, TemplateArgs, DGuide->getExplicitSpecifier(), DGuide);
     if (InstantiatedExplicitSpecifier.isInvalid())
       return nullptr;
   }
 
   SmallVector<ParmVarDecl *, 4> Params;
   TypeSourceInfo *TInfo = SubstFunctionType(D, Params);
   if (!TInfo)
     return nullptr;
   QualType T = adjustFunctionTypeForInstantiation(SemaRef.Context, D, TInfo);
 
   if (TemplateParams && TemplateParams->size()) {
     auto *LastParam =
         dyn_cast<TemplateTypeParmDecl>(TemplateParams->asArray().back());
     if (LastParam && LastParam->isImplicit() &&
         LastParam->hasTypeConstraint()) {
       // In abbreviated templates, the type-constraints of invented template
       // type parameters are instantiated with the function type, invalidating
       // the TemplateParameterList which relied on the template type parameter
       // not having a type constraint. Recreate the TemplateParameterList with
       // the updated parameter list.
       TemplateParams = TemplateParameterList::Create(
           SemaRef.Context, TemplateParams->getTemplateLoc(),
           TemplateParams->getLAngleLoc(), TemplateParams->asArray(),
           TemplateParams->getRAngleLoc(), TemplateParams->getRequiresClause());
     }
   }
 
   NestedNameSpecifierLoc QualifierLoc = D->getQualifierLoc();
   if (QualifierLoc) {
     QualifierLoc = SemaRef.SubstNestedNameSpecifierLoc(QualifierLoc,
                                                        TemplateArgs);
     if (!QualifierLoc)
       return nullptr;
   }
 
   Expr *TrailingRequiresClause = D->getTrailingRequiresClause();
 
   // If we're instantiating a local function declaration, put the result
   // in the enclosing namespace; otherwise we need to find the instantiated
   // context.
   DeclContext *DC;
   if (D->isLocalExternDecl()) {
     DC = Owner;
     SemaRef.adjustContextForLocalExternDecl(DC);
   } else if (isFriend && QualifierLoc) {
     CXXScopeSpec SS;
     SS.Adopt(QualifierLoc);
     DC = SemaRef.computeDeclContext(SS);
     if (!DC) return nullptr;
   } else {
     DC = SemaRef.FindInstantiatedContext(D->getLocation(), D->getDeclContext(),
                                          TemplateArgs);
   }
 
   DeclarationNameInfo NameInfo
     = SemaRef.SubstDeclarationNameInfo(D->getNameInfo(), TemplateArgs);
 
   if (FunctionRewriteKind != RewriteKind::None)
     adjustForRewrite(FunctionRewriteKind, D, T, TInfo, NameInfo);
 
   FunctionDecl *Function;
   if (auto *DGuide = dyn_cast<CXXDeductionGuideDecl>(D)) {
     Function = CXXDeductionGuideDecl::Create(
         SemaRef.Context, DC, D->getInnerLocStart(),
         InstantiatedExplicitSpecifier, NameInfo, T, TInfo,
         D->getSourceRange().getEnd(), /*Ctor=*/nullptr,
         DGuide->getDeductionCandidateKind());
     Function->setAccess(D->getAccess());
   } else {
     Function = FunctionDecl::Create(
         SemaRef.Context, DC, D->getInnerLocStart(), NameInfo, T, TInfo,
         D->getCanonicalDecl()->getStorageClass(), D->UsesFPIntrin(),
         D->isInlineSpecified(), D->hasWrittenPrototype(), D->getConstexprKind(),
         TrailingRequiresClause);
     Function->setFriendConstraintRefersToEnclosingTemplate(
         D->FriendConstraintRefersToEnclosingTemplate());
     Function->setRangeEnd(D->getSourceRange().getEnd());
   }
 
   if (D->isInlined())
     Function->setImplicitlyInline();
 
   if (QualifierLoc)
     Function->setQualifierInfo(QualifierLoc);
 
   if (D->isLocalExternDecl())
     Function->setLocalExternDecl();
 
   DeclContext *LexicalDC = Owner;
   if (!isFriend && D->isOutOfLine() && !D->isLocalExternDecl()) {
     assert(D->getDeclContext()->isFileContext());
     LexicalDC = D->getDeclContext();
   }
   else if (D->isLocalExternDecl()) {
     LexicalDC = SemaRef.CurContext;
   }
 
   Function->setLexicalDeclContext(LexicalDC);
 
   // Attach the parameters
   for (unsigned P = 0; P < Params.size(); ++P)
     if (Params[P])
       Params[P]->setOwningFunction(Function);
   Function->setParams(Params);
 
   if (TrailingRequiresClause)
     Function->setTrailingRequiresClause(TrailingRequiresClause);
 
   if (TemplateParams) {
     // Our resulting instantiation is actually a function template, since we
     // are substituting only the outer template parameters. For example, given
     //
     //   template<typename T>
     //   struct X {
     //     template<typename U> friend void f(T, U);
     //   };
     //
     //   X<int> x;
     //
     // We are instantiating the friend function template "f" within X<int>,
     // which means substituting int for T, but leaving "f" as a friend function
     // template.
     // Build the function template itself.
     FunctionTemplate = FunctionTemplateDecl::Create(SemaRef.Context, DC,
                                                     Function->getLocation(),
                                                     Function->getDeclName(),
                                                     TemplateParams, Function);
     Function->setDescribedFunctionTemplate(FunctionTemplate);
 
     FunctionTemplate->setLexicalDeclContext(LexicalDC);
 
     if (isFriend && D->isThisDeclarationADefinition()) {
       FunctionTemplate->setInstantiatedFromMemberTemplate(
                                            D->getDescribedFunctionTemplate());
     }
   } else if (FunctionTemplate) {
     // Record this function template specialization.
     ArrayRef<TemplateArgument> Innermost = TemplateArgs.getInnermost();
     Function->setFunctionTemplateSpecialization(FunctionTemplate,
                             TemplateArgumentList::CreateCopy(SemaRef.Context,
                                                              Innermost),
                                                 /*InsertPos=*/nullptr);
   } else if (isFriend && D->isThisDeclarationADefinition()) {
     // Do not connect the friend to the template unless it's actually a
     // definition. We don't want non-template functions to be marked as being
     // template instantiations.
     Function->setInstantiationOfMemberFunction(D, TSK_ImplicitInstantiation);
   } else if (!isFriend) {
     // If this is not a function template, and this is not a friend (that is,
     // this is a locally declared function), save the instantiation relationship
     // for the purposes of constraint instantiation.
     Function->setInstantiatedFromDecl(D);
   }
 
   if (isFriend) {
     Function->setObjectOfFriendDecl();
     if (FunctionTemplateDecl *FT = Function->getDescribedFunctionTemplate())
       FT->setObjectOfFriendDecl();
   }
 
   if (InitFunctionInstantiation(Function, D))
     Function->setInvalidDecl();
 
   bool IsExplicitSpecialization = false;
 
   LookupResult Previous(
       SemaRef, Function->getDeclName(), SourceLocation(),
       D->isLocalExternDecl() ? Sema::LookupRedeclarationWithLinkage
                              : Sema::LookupOrdinaryName,
       D->isLocalExternDecl() ? Sema::ForExternalRedeclaration
                              : SemaRef.forRedeclarationInCurContext());
 
   if (DependentFunctionTemplateSpecializationInfo *Info
         = D->getDependentSpecializationInfo()) {
     assert(isFriend && "non-friend has dependent specialization info?");
 
     // Instantiate the explicit template arguments.
     TemplateArgumentListInfo ExplicitArgs(Info->getLAngleLoc(),
                                           Info->getRAngleLoc());
     if (SemaRef.SubstTemplateArguments(Info->arguments(), TemplateArgs,
                                        ExplicitArgs))
       return nullptr;
 
     // Map the candidate templates to their instantiations.
     for (unsigned I = 0, E = Info->getNumTemplates(); I != E; ++I) {
       Decl *Temp = SemaRef.FindInstantiatedDecl(D->getLocation(),
                                                 Info->getTemplate(I),
                                                 TemplateArgs);
       if (!Temp) return nullptr;
 
       Previous.addDecl(cast<FunctionTemplateDecl>(Temp));
     }
 
     if (SemaRef.CheckFunctionTemplateSpecialization(Function,
                                                     &ExplicitArgs,
                                                     Previous))
       Function->setInvalidDecl();
 
     IsExplicitSpecialization = true;
   } else if (const ASTTemplateArgumentListInfo *Info =
                  D->getTemplateSpecializationArgsAsWritten()) {
     // The name of this function was written as a template-id.
     SemaRef.LookupQualifiedName(Previous, DC);
 
     // Instantiate the explicit template arguments.
     TemplateArgumentListInfo ExplicitArgs(Info->getLAngleLoc(),
                                           Info->getRAngleLoc());
     if (SemaRef.SubstTemplateArguments(Info->arguments(), TemplateArgs,
                                        ExplicitArgs))
       return nullptr;
 
     if (SemaRef.CheckFunctionTemplateSpecialization(Function,
                                                     &ExplicitArgs,
                                                     Previous))
       Function->setInvalidDecl();
 
     IsExplicitSpecialization = true;
   } else if (TemplateParams || !FunctionTemplate) {
     // Look only into the namespace where the friend would be declared to
     // find a previous declaration. This is the innermost enclosing namespace,
     // as described in ActOnFriendFunctionDecl.
     SemaRef.LookupQualifiedName(Previous, DC->getRedeclContext());
 
     // In C++, the previous declaration we find might be a tag type
     // (class or enum). In this case, the new declaration will hide the
     // tag type. Note that this does not apply if we're declaring a
     // typedef (C++ [dcl.typedef]p4).
     if (Previous.isSingleTagDecl())
       Previous.clear();
 
     // Filter out previous declarations that don't match the scope. The only
     // effect this has is to remove declarations found in inline namespaces
     // for friend declarations with unqualified names.
     if (isFriend && !QualifierLoc) {
       SemaRef.FilterLookupForScope(Previous, DC, /*Scope=*/ nullptr,
                                    /*ConsiderLinkage=*/ true,
                                    QualifierLoc.hasQualifier());
     }
   }
 
   // Per [temp.inst], default arguments in function declarations at local scope
   // are instantiated along with the enclosing declaration. For example:
   //
   //   template<typename T>
   //   void ft() {
   //     void f(int = []{ return T::value; }());
   //   }
   //   template void ft<int>(); // error: type 'int' cannot be used prior
   //                                      to '::' because it has no members
   //
   // The error is issued during instantiation of ft<int>() because substitution
   // into the default argument fails; the default argument is instantiated even
   // though it is never used.
   if (Function->isLocalExternDecl()) {
     for (ParmVarDecl *PVD : Function->parameters()) {
       if (!PVD->hasDefaultArg())
         continue;
       if (SemaRef.SubstDefaultArgument(D->getInnerLocStart(), PVD, TemplateArgs)) {
         // If substitution fails, the default argument is set to a
         // RecoveryExpr that wraps the uninstantiated default argument so
         // that downstream diagnostics are omitted.
         Expr *UninstExpr = PVD->getUninstantiatedDefaultArg();
         ExprResult ErrorResult = SemaRef.CreateRecoveryExpr(
             UninstExpr->getBeginLoc(), UninstExpr->getEndLoc(),
             { UninstExpr }, UninstExpr->getType());
         if (ErrorResult.isUsable())
           PVD->setDefaultArg(ErrorResult.get());
       }
     }
   }
 
   SemaRef.CheckFunctionDeclaration(/*Scope*/ nullptr, Function, Previous,
                                    IsExplicitSpecialization,
                                    Function->isThisDeclarationADefinition());
 
   // Check the template parameter list against the previous declaration. The
   // goal here is to pick up default arguments added since the friend was
   // declared; we know the template parameter lists match, since otherwise
   // we would not have picked this template as the previous declaration.
   if (isFriend && TemplateParams && FunctionTemplate->getPreviousDecl()) {
     SemaRef.CheckTemplateParameterList(
         TemplateParams,
         FunctionTemplate->getPreviousDecl()->getTemplateParameters(),
         Function->isThisDeclarationADefinition()
             ? Sema::TPC_FriendFunctionTemplateDefinition
             : Sema::TPC_FriendFunctionTemplate);
   }
 
   // If we're introducing a friend definition after the first use, trigger
   // instantiation.
   // FIXME: If this is a friend function template definition, we should check
   // to see if any specializations have been used.
   if (isFriend && D->isThisDeclarationADefinition() && Function->isUsed(false)) {
     if (MemberSpecializationInfo *MSInfo =
             Function->getMemberSpecializationInfo()) {
       if (MSInfo->getPointOfInstantiation().isInvalid()) {
         SourceLocation Loc = D->getLocation(); // FIXME
         MSInfo->setPointOfInstantiation(Loc);
         SemaRef.PendingLocalImplicitInstantiations.push_back(
             std::make_pair(Function, Loc));
       }
     }
   }
 
   if (D->isExplicitlyDefaulted()) {
     if (SubstDefaultedFunction(Function, D))
       return nullptr;
   }
   if (D->isDeleted())
     SemaRef.SetDeclDeleted(Function, D->getLocation());
 
   NamedDecl *PrincipalDecl =
       (TemplateParams ? cast<NamedDecl>(FunctionTemplate) : Function);
 
   // If this declaration lives in a different context from its lexical context,
   // add it to the corresponding lookup table.
   if (isFriend ||
       (Function->isLocalExternDecl() && !Function->getPreviousDecl()))
     DC->makeDeclVisibleInContext(PrincipalDecl);
 
   if (Function->isOverloadedOperator() && !DC->isRecord() &&
       PrincipalDecl->isInIdentifierNamespace(Decl::IDNS_Ordinary))
     PrincipalDecl->setNonMemberOperator();
 
   return Function;
 }
 
 Decl *TemplateDeclInstantiator::VisitCXXMethodDecl(
     CXXMethodDecl *D, TemplateParameterList *TemplateParams,
     std::optional<const ASTTemplateArgumentListInfo *>
         ClassScopeSpecializationArgs,
     RewriteKind FunctionRewriteKind) {
   FunctionTemplateDecl *FunctionTemplate = D->getDescribedFunctionTemplate();
   if (FunctionTemplate && !TemplateParams) {
     // We are creating a function template specialization from a function
     // template. Check whether there is already a function template
     // specialization for this particular set of template arguments.
     ArrayRef<TemplateArgument> Innermost = TemplateArgs.getInnermost();
 
     void *InsertPos = nullptr;
     FunctionDecl *SpecFunc
       = FunctionTemplate->findSpecialization(Innermost, InsertPos);
 
     // If we already have a function template specialization, return it.
     if (SpecFunc)
       return SpecFunc;
   }
 
   bool isFriend;
   if (FunctionTemplate)
     isFriend = (FunctionTemplate->getFriendObjectKind() != Decl::FOK_None);
   else
     isFriend = (D->getFriendObjectKind() != Decl::FOK_None);
 
   bool MergeWithParentScope = (TemplateParams != nullptr) ||
     !(isa<Decl>(Owner) &&
       cast<Decl>(Owner)->isDefinedOutsideFunctionOrMethod());
   LocalInstantiationScope Scope(SemaRef, MergeWithParentScope);
 
+  Sema::LambdaScopeForCallOperatorInstantiationRAII LambdaScope(
+      SemaRef, const_cast<CXXMethodDecl *>(D), TemplateArgs, Scope);
+
   // Instantiate enclosing template arguments for friends.
   SmallVector<TemplateParameterList *, 4> TempParamLists;
   unsigned NumTempParamLists = 0;
   if (isFriend && (NumTempParamLists = D->getNumTemplateParameterLists())) {
     TempParamLists.resize(NumTempParamLists);
     for (unsigned I = 0; I != NumTempParamLists; ++I) {
       TemplateParameterList *TempParams = D->getTemplateParameterList(I);
       TemplateParameterList *InstParams = SubstTemplateParams(TempParams);
       if (!InstParams)
         return nullptr;
       TempParamLists[I] = InstParams;
     }
   }
 
   ExplicitSpecifier InstantiatedExplicitSpecifier =
       instantiateExplicitSpecifier(SemaRef, TemplateArgs,
                                    ExplicitSpecifier::getFromDecl(D), D);
   if (InstantiatedExplicitSpecifier.isInvalid())
     return nullptr;
 
   // Implicit destructors/constructors created for local classes in
   // DeclareImplicit* (see SemaDeclCXX.cpp) might not have an associated TSI.
   // Unfortunately there isn't enough context in those functions to
   // conditionally populate the TSI without breaking non-template related use
   // cases. Populate TSIs prior to calling SubstFunctionType to make sure we get
   // a proper transformation.
   if (cast<CXXRecordDecl>(D->getParent())->isLambda() &&
       !D->getTypeSourceInfo() &&
       isa<CXXConstructorDecl, CXXDestructorDecl>(D)) {
     TypeSourceInfo *TSI =
         SemaRef.Context.getTrivialTypeSourceInfo(D->getType());
     D->setTypeSourceInfo(TSI);
   }
 
   SmallVector<ParmVarDecl *, 4> Params;
   TypeSourceInfo *TInfo = SubstFunctionType(D, Params);
   if (!TInfo)
     return nullptr;
   QualType T = adjustFunctionTypeForInstantiation(SemaRef.Context, D, TInfo);
 
   if (TemplateParams && TemplateParams->size()) {
     auto *LastParam =
         dyn_cast<TemplateTypeParmDecl>(TemplateParams->asArray().back());
     if (LastParam && LastParam->isImplicit() &&
         LastParam->hasTypeConstraint()) {
       // In abbreviated templates, the type-constraints of invented template
       // type parameters are instantiated with the function type, invalidating
       // the TemplateParameterList which relied on the template type parameter
       // not having a type constraint. Recreate the TemplateParameterList with
       // the updated parameter list.
       TemplateParams = TemplateParameterList::Create(
           SemaRef.Context, TemplateParams->getTemplateLoc(),
           TemplateParams->getLAngleLoc(), TemplateParams->asArray(),
           TemplateParams->getRAngleLoc(), TemplateParams->getRequiresClause());
     }
   }
 
   NestedNameSpecifierLoc QualifierLoc = D->getQualifierLoc();
   if (QualifierLoc) {
     QualifierLoc = SemaRef.SubstNestedNameSpecifierLoc(QualifierLoc,
                                                  TemplateArgs);
     if (!QualifierLoc)
       return nullptr;
   }
 
   DeclContext *DC = Owner;
   if (isFriend) {
     if (QualifierLoc) {
       CXXScopeSpec SS;
       SS.Adopt(QualifierLoc);
       DC = SemaRef.computeDeclContext(SS);
 
       if (DC && SemaRef.RequireCompleteDeclContext(SS, DC))
         return nullptr;
     } else {
       DC = SemaRef.FindInstantiatedContext(D->getLocation(),
                                            D->getDeclContext(),
                                            TemplateArgs);
     }
     if (!DC) return nullptr;
   }
 
   CXXRecordDecl *Record = cast<CXXRecordDecl>(DC);
   Expr *TrailingRequiresClause = D->getTrailingRequiresClause();
 
   DeclarationNameInfo NameInfo
     = SemaRef.SubstDeclarationNameInfo(D->getNameInfo(), TemplateArgs);
 
   if (FunctionRewriteKind != RewriteKind::None)
     adjustForRewrite(FunctionRewriteKind, D, T, TInfo, NameInfo);
 
   // Build the instantiated method declaration.
   CXXMethodDecl *Method = nullptr;
 
   SourceLocation StartLoc = D->getInnerLocStart();
   if (CXXConstructorDecl *Constructor = dyn_cast<CXXConstructorDecl>(D)) {
     Method = CXXConstructorDecl::Create(
         SemaRef.Context, Record, StartLoc, NameInfo, T, TInfo,
         InstantiatedExplicitSpecifier, Constructor->UsesFPIntrin(),
         Constructor->isInlineSpecified(), false,
         Constructor->getConstexprKind(), InheritedConstructor(),
         TrailingRequiresClause);
     Method->setRangeEnd(Constructor->getEndLoc());
   } else if (CXXDestructorDecl *Destructor = dyn_cast<CXXDestructorDecl>(D)) {
     Method = CXXDestructorDecl::Create(
         SemaRef.Context, Record, StartLoc, NameInfo, T, TInfo,
         Destructor->UsesFPIntrin(), Destructor->isInlineSpecified(), false,
         Destructor->getConstexprKind(), TrailingRequiresClause);
     Method->setIneligibleOrNotSelected(true);
     Method->setRangeEnd(Destructor->getEndLoc());
     Method->setDeclName(SemaRef.Context.DeclarationNames.getCXXDestructorName(
         SemaRef.Context.getCanonicalType(
             SemaRef.Context.getTypeDeclType(Record))));
   } else if (CXXConversionDecl *Conversion = dyn_cast<CXXConversionDecl>(D)) {
     Method = CXXConversionDecl::Create(
         SemaRef.Context, Record, StartLoc, NameInfo, T, TInfo,
         Conversion->UsesFPIntrin(), Conversion->isInlineSpecified(),
         InstantiatedExplicitSpecifier, Conversion->getConstexprKind(),
         Conversion->getEndLoc(), TrailingRequiresClause);
   } else {
     StorageClass SC = D->isStatic() ? SC_Static : SC_None;
     Method = CXXMethodDecl::Create(
         SemaRef.Context, Record, StartLoc, NameInfo, T, TInfo, SC,
         D->UsesFPIntrin(), D->isInlineSpecified(), D->getConstexprKind(),
         D->getEndLoc(), TrailingRequiresClause);
   }
 
   if (D->isInlined())
     Method->setImplicitlyInline();
 
   if (QualifierLoc)
     Method->setQualifierInfo(QualifierLoc);
 
   if (TemplateParams) {
     // Our resulting instantiation is actually a function template, since we
     // are substituting only the outer template parameters. For example, given
     //
     //   template<typename T>
     //   struct X {
     //     template<typename U> void f(T, U);
     //   };
     //
     //   X<int> x;
     //
     // We are instantiating the member template "f" within X<int>, which means
     // substituting int for T, but leaving "f" as a member function template.
     // Build the function template itself.
     FunctionTemplate = FunctionTemplateDecl::Create(SemaRef.Context, Record,
                                                     Method->getLocation(),
                                                     Method->getDeclName(),
                                                     TemplateParams, Method);
     if (isFriend) {
       FunctionTemplate->setLexicalDeclContext(Owner);
       FunctionTemplate->setObjectOfFriendDecl();
     } else if (D->isOutOfLine())
       FunctionTemplate->setLexicalDeclContext(D->getLexicalDeclContext());
     Method->setDescribedFunctionTemplate(FunctionTemplate);
   } else if (FunctionTemplate) {
     // Record this function template specialization.
     ArrayRef<TemplateArgument> Innermost = TemplateArgs.getInnermost();
     Method->setFunctionTemplateSpecialization(FunctionTemplate,
                          TemplateArgumentList::CreateCopy(SemaRef.Context,
                                                           Innermost),
                                               /*InsertPos=*/nullptr);
   } else if (!isFriend) {
     // Record that this is an instantiation of a member function.
     Method->setInstantiationOfMemberFunction(D, TSK_ImplicitInstantiation);
   }
 
   // If we are instantiating a member function defined
   // out-of-line, the instantiation will have the same lexical
   // context (which will be a namespace scope) as the template.
   if (isFriend) {
     if (NumTempParamLists)
       Method->setTemplateParameterListsInfo(
           SemaRef.Context,
           llvm::ArrayRef(TempParamLists.data(), NumTempParamLists));
 
     Method->setLexicalDeclContext(Owner);
     Method->setObjectOfFriendDecl();
   } else if (D->isOutOfLine())
     Method->setLexicalDeclContext(D->getLexicalDeclContext());
 
   // Attach the parameters
   for (unsigned P = 0; P < Params.size(); ++P)
     Params[P]->setOwningFunction(Method);
   Method->setParams(Params);
 
   if (InitMethodInstantiation(Method, D))
     Method->setInvalidDecl();
 
   LookupResult Previous(SemaRef, NameInfo, Sema::LookupOrdinaryName,
                         Sema::ForExternalRedeclaration);
 
   bool IsExplicitSpecialization = false;
 
   // If the name of this function was written as a template-id, instantiate
   // the explicit template arguments.
   if (DependentFunctionTemplateSpecializationInfo *Info
         = D->getDependentSpecializationInfo()) {
     assert(isFriend && "non-friend has dependent specialization info?");
 
     // Instantiate the explicit template arguments.
     TemplateArgumentListInfo ExplicitArgs(Info->getLAngleLoc(),
                                           Info->getRAngleLoc());
     if (SemaRef.SubstTemplateArguments(Info->arguments(), TemplateArgs,
                                        ExplicitArgs))
       return nullptr;
 
     // Map the candidate templates to their instantiations.
     for (unsigned I = 0, E = Info->getNumTemplates(); I != E; ++I) {
       Decl *Temp = SemaRef.FindInstantiatedDecl(D->getLocation(),
                                                 Info->getTemplate(I),
                                                 TemplateArgs);
       if (!Temp) return nullptr;
 
       Previous.addDecl(cast<FunctionTemplateDecl>(Temp));
     }
 
     if (SemaRef.CheckFunctionTemplateSpecialization(Method,
                                                     &ExplicitArgs,
                                                     Previous))
       Method->setInvalidDecl();
 
     IsExplicitSpecialization = true;
   } else if (const ASTTemplateArgumentListInfo *Info =
                  ClassScopeSpecializationArgs.value_or(
                      D->getTemplateSpecializationArgsAsWritten())) {
     SemaRef.LookupQualifiedName(Previous, DC);
 
     TemplateArgumentListInfo ExplicitArgs(Info->getLAngleLoc(),
                                           Info->getRAngleLoc());
     if (SemaRef.SubstTemplateArguments(Info->arguments(), TemplateArgs,
                                        ExplicitArgs))
       return nullptr;
 
     if (SemaRef.CheckFunctionTemplateSpecialization(Method,
                                                     &ExplicitArgs,
                                                     Previous))
       Method->setInvalidDecl();
 
     IsExplicitSpecialization = true;
   } else if (ClassScopeSpecializationArgs) {
     // Class-scope explicit specialization written without explicit template
     // arguments.
     SemaRef.LookupQualifiedName(Previous, DC);
     if (SemaRef.CheckFunctionTemplateSpecialization(Method, nullptr, Previous))
       Method->setInvalidDecl();
 
     IsExplicitSpecialization = true;
   } else if (!FunctionTemplate || TemplateParams || isFriend) {
     SemaRef.LookupQualifiedName(Previous, Record);
 
     // In C++, the previous declaration we find might be a tag type
     // (class or enum). In this case, the new declaration will hide the
     // tag type. Note that this does not apply if we're declaring a
     // typedef (C++ [dcl.typedef]p4).
     if (Previous.isSingleTagDecl())
       Previous.clear();
   }
 
   // Per [temp.inst], default arguments in member functions of local classes
   // are instantiated along with the member function declaration. For example:
   //
   //   template<typename T>
   //   void ft() {
   //     struct lc {
   //       int operator()(int p = []{ return T::value; }());
   //     };
   //   }
   //   template void ft<int>(); // error: type 'int' cannot be used prior
   //                                      to '::'because it has no members
   //
   // The error is issued during instantiation of ft<int>()::lc::operator()
   // because substitution into the default argument fails; the default argument
   // is instantiated even though it is never used.
   if (D->isInLocalScopeForInstantiation()) {
     for (unsigned P = 0; P < Params.size(); ++P) {
       if (!Params[P]->hasDefaultArg())
         continue;
       if (SemaRef.SubstDefaultArgument(StartLoc, Params[P], TemplateArgs)) {
         // If substitution fails, the default argument is set to a
         // RecoveryExpr that wraps the uninstantiated default argument so
         // that downstream diagnostics are omitted.
         Expr *UninstExpr = Params[P]->getUninstantiatedDefaultArg();
         ExprResult ErrorResult = SemaRef.CreateRecoveryExpr(
             UninstExpr->getBeginLoc(), UninstExpr->getEndLoc(),
             { UninstExpr }, UninstExpr->getType());
         if (ErrorResult.isUsable())
           Params[P]->setDefaultArg(ErrorResult.get());
       }
     }
   }
 
   SemaRef.CheckFunctionDeclaration(nullptr, Method, Previous,
                                    IsExplicitSpecialization,
                                    Method->isThisDeclarationADefinition());
 
   if (D->isPure())
     SemaRef.CheckPureMethod(Method, SourceRange());
 
   // Propagate access.  For a non-friend declaration, the access is
   // whatever we're propagating from.  For a friend, it should be the
   // previous declaration we just found.
   if (isFriend && Method->getPreviousDecl())
     Method->setAccess(Method->getPreviousDecl()->getAccess());
   else
     Method->setAccess(D->getAccess());
   if (FunctionTemplate)
     FunctionTemplate->setAccess(Method->getAccess());
 
   SemaRef.CheckOverrideControl(Method);
 
   // If a function is defined as defaulted or deleted, mark it as such now.
   if (D->isExplicitlyDefaulted()) {
     if (SubstDefaultedFunction(Method, D))
       return nullptr;
   }
   if (D->isDeletedAsWritten())
     SemaRef.SetDeclDeleted(Method, Method->getLocation());
 
   // If this is an explicit specialization, mark the implicitly-instantiated
   // template specialization as being an explicit specialization too.
   // FIXME: Is this necessary?
   if (IsExplicitSpecialization && !isFriend)
     SemaRef.CompleteMemberSpecialization(Method, Previous);
 
   // If the method is a special member function, we need to mark it as
   // ineligible so that Owner->addDecl() won't mark the class as non trivial.
   // At the end of the class instantiation, we calculate eligibility again and
   // then we adjust trivility if needed.
   // We need this check to happen only after the method parameters are set,
   // because being e.g. a copy constructor depends on the instantiated
   // arguments.
   if (auto *Constructor = dyn_cast<CXXConstructorDecl>(Method)) {
     if (Constructor->isDefaultConstructor() ||
         Constructor->isCopyOrMoveConstructor())
       Method->setIneligibleOrNotSelected(true);
   } else if (Method->isCopyAssignmentOperator() ||
              Method->isMoveAssignmentOperator()) {
     Method->setIneligibleOrNotSelected(true);
   }
 
   // If there's a function template, let our caller handle it.
   if (FunctionTemplate) {
     // do nothing
 
   // Don't hide a (potentially) valid declaration with an invalid one.
   } else if (Method->isInvalidDecl() && !Previous.empty()) {
     // do nothing
 
   // Otherwise, check access to friends and make them visible.
   } else if (isFriend) {
     // We only need to re-check access for methods which we didn't
     // manage to match during parsing.
     if (!D->getPreviousDecl())
       SemaRef.CheckFriendAccess(Method);
 
     Record->makeDeclVisibleInContext(Method);
 
   // Otherwise, add the declaration.  We don't need to do this for
   // class-scope specializations because we'll have matched them with
   // the appropriate template.
   } else {
     Owner->addDecl(Method);
   }
 
   // PR17480: Honor the used attribute to instantiate member function
   // definitions
   if (Method->hasAttr<UsedAttr>()) {
     if (const auto *A = dyn_cast<CXXRecordDecl>(Owner)) {
       SourceLocation Loc;
       if (const MemberSpecializationInfo *MSInfo =
               A->getMemberSpecializationInfo())
         Loc = MSInfo->getPointOfInstantiation();
       else if (const auto *Spec = dyn_cast<ClassTemplateSpecializationDecl>(A))
         Loc = Spec->getPointOfInstantiation();
       SemaRef.MarkFunctionReferenced(Loc, Method);
     }
   }
 
   return Method;
 }
 
 Decl *TemplateDeclInstantiator::VisitCXXConstructorDecl(CXXConstructorDecl *D) {
   return VisitCXXMethodDecl(D);
 }
 
 Decl *TemplateDeclInstantiator::VisitCXXDestructorDecl(CXXDestructorDecl *D) {
   return VisitCXXMethodDecl(D);
 }
 
 Decl *TemplateDeclInstantiator::VisitCXXConversionDecl(CXXConversionDecl *D) {
   return VisitCXXMethodDecl(D);
 }
 
 Decl *TemplateDeclInstantiator::VisitParmVarDecl(ParmVarDecl *D) {
   return SemaRef.SubstParmVarDecl(D, TemplateArgs, /*indexAdjustment*/ 0,
                                   std::nullopt,
                                   /*ExpectParameterPack=*/false);
 }
 
 Decl *TemplateDeclInstantiator::VisitTemplateTypeParmDecl(
                                                     TemplateTypeParmDecl *D) {
   assert(D->getTypeForDecl()->isTemplateTypeParmType());
 
   std::optional<unsigned> NumExpanded;
 
   if (const TypeConstraint *TC = D->getTypeConstraint()) {
     if (D->isPackExpansion() && !D->isExpandedParameterPack()) {
       assert(TC->getTemplateArgsAsWritten() &&
              "type parameter can only be an expansion when explicit arguments "
              "are specified");
       // The template type parameter pack's type is a pack expansion of types.
       // Determine whether we need to expand this parameter pack into separate
       // types.
       SmallVector<UnexpandedParameterPack, 2> Unexpanded;
       for (auto &ArgLoc : TC->getTemplateArgsAsWritten()->arguments())
         SemaRef.collectUnexpandedParameterPacks(ArgLoc, Unexpanded);
 
       // Determine whether the set of unexpanded parameter packs can and should
       // be expanded.
       bool Expand = true;
       bool RetainExpansion = false;
       if (SemaRef.CheckParameterPacksForExpansion(
               cast<CXXFoldExpr>(TC->getImmediatelyDeclaredConstraint())
                   ->getEllipsisLoc(),
               SourceRange(TC->getConceptNameLoc(),
                           TC->hasExplicitTemplateArgs() ?
                           TC->getTemplateArgsAsWritten()->getRAngleLoc() :
                           TC->getConceptNameInfo().getEndLoc()),
               Unexpanded, TemplateArgs, Expand, RetainExpansion, NumExpanded))
         return nullptr;
     }
   }
 
   TemplateTypeParmDecl *Inst = TemplateTypeParmDecl::Create(
       SemaRef.Context, Owner, D->getBeginLoc(), D->getLocation(),
       D->getDepth() - TemplateArgs.getNumSubstitutedLevels(), D->getIndex(),
       D->getIdentifier(), D->wasDeclaredWithTypename(), D->isParameterPack(),
       D->hasTypeConstraint(), NumExpanded);
 
   Inst->setAccess(AS_public);
   Inst->setImplicit(D->isImplicit());
   if (auto *TC = D->getTypeConstraint()) {
     if (!D->isImplicit()) {
       // Invented template parameter type constraints will be instantiated
       // with the corresponding auto-typed parameter as it might reference
       // other parameters.
       if (SemaRef.SubstTypeConstraint(Inst, TC, TemplateArgs,
                                       EvaluateConstraints))
         return nullptr;
     }
   }
   if (D->hasDefaultArgument() && !D->defaultArgumentWasInherited()) {
     TypeSourceInfo *InstantiatedDefaultArg =
         SemaRef.SubstType(D->getDefaultArgumentInfo(), TemplateArgs,
                           D->getDefaultArgumentLoc(), D->getDeclName());
     if (InstantiatedDefaultArg)
       Inst->setDefaultArgument(InstantiatedDefaultArg);
   }
 
   // Introduce this template parameter's instantiation into the instantiation
   // scope.
   SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, Inst);
 
   return Inst;
 }
 
 Decl *TemplateDeclInstantiator::VisitNonTypeTemplateParmDecl(
                                                  NonTypeTemplateParmDecl *D) {
   // Substitute into the type of the non-type template parameter.
   TypeLoc TL = D->getTypeSourceInfo()->getTypeLoc();
   SmallVector<TypeSourceInfo *, 4> ExpandedParameterPackTypesAsWritten;
   SmallVector<QualType, 4> ExpandedParameterPackTypes;
   bool IsExpandedParameterPack = false;
   TypeSourceInfo *DI;
   QualType T;
   bool Invalid = false;
 
   if (D->isExpandedParameterPack()) {
     // The non-type template parameter pack is an already-expanded pack
     // expansion of types. Substitute into each of the expanded types.
     ExpandedParameterPackTypes.reserve(D->getNumExpansionTypes());
     ExpandedParameterPackTypesAsWritten.reserve(D->getNumExpansionTypes());
     for (unsigned I = 0, N = D->getNumExpansionTypes(); I != N; ++I) {
       TypeSourceInfo *NewDI =
           SemaRef.SubstType(D->getExpansionTypeSourceInfo(I), TemplateArgs,
                             D->getLocation(), D->getDeclName());
       if (!NewDI)
         return nullptr;
 
       QualType NewT =
           SemaRef.CheckNonTypeTemplateParameterType(NewDI, D->getLocation());
       if (NewT.isNull())
         return nullptr;
 
       ExpandedParameterPackTypesAsWritten.push_back(NewDI);
       ExpandedParameterPackTypes.push_back(NewT);
     }
 
     IsExpandedParameterPack = true;
     DI = D->getTypeSourceInfo();
     T = DI->getType();
   } else if (D->isPackExpansion()) {
     // The non-type template parameter pack's type is a pack expansion of types.
     // Determine whether we need to expand this parameter pack into separate
     // types.
     PackExpansionTypeLoc Expansion = TL.castAs<PackExpansionTypeLoc>();
     TypeLoc Pattern = Expansion.getPatternLoc();
     SmallVector<UnexpandedParameterPack, 2> Unexpanded;
     SemaRef.collectUnexpandedParameterPacks(Pattern, Unexpanded);
 
     // Determine whether the set of unexpanded parameter packs can and should
     // be expanded.
     bool Expand = true;
     bool RetainExpansion = false;
     std::optional<unsigned> OrigNumExpansions =
         Expansion.getTypePtr()->getNumExpansions();
     std::optional<unsigned> NumExpansions = OrigNumExpansions;
     if (SemaRef.CheckParameterPacksForExpansion(Expansion.getEllipsisLoc(),
                                                 Pattern.getSourceRange(),
                                                 Unexpanded,
                                                 TemplateArgs,
                                                 Expand, RetainExpansion,
                                                 NumExpansions))
       return nullptr;
 
     if (Expand) {
       for (unsigned I = 0; I != *NumExpansions; ++I) {
         Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(SemaRef, I);
         TypeSourceInfo *NewDI = SemaRef.SubstType(Pattern, TemplateArgs,
                                                   D->getLocation(),
                                                   D->getDeclName());
         if (!NewDI)
           return nullptr;
 
         QualType NewT =
             SemaRef.CheckNonTypeTemplateParameterType(NewDI, D->getLocation());
         if (NewT.isNull())
           return nullptr;
 
         ExpandedParameterPackTypesAsWritten.push_back(NewDI);
         ExpandedParameterPackTypes.push_back(NewT);
       }
 
       // Note that we have an expanded parameter pack. The "type" of this
       // expanded parameter pack is the original expansion type, but callers
       // will end up using the expanded parameter pack types for type-checking.
       IsExpandedParameterPack = true;
       DI = D->getTypeSourceInfo();
       T = DI->getType();
     } else {
       // We cannot fully expand the pack expansion now, so substitute into the
       // pattern and create a new pack expansion type.
       Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(SemaRef, -1);
       TypeSourceInfo *NewPattern = SemaRef.SubstType(Pattern, TemplateArgs,
                                                      D->getLocation(),
                                                      D->getDeclName());
       if (!NewPattern)
         return nullptr;
 
       SemaRef.CheckNonTypeTemplateParameterType(NewPattern, D->getLocation());
       DI = SemaRef.CheckPackExpansion(NewPattern, Expansion.getEllipsisLoc(),
                                       NumExpansions);
       if (!DI)
         return nullptr;
 
       T = DI->getType();
     }
   } else {
     // Simple case: substitution into a parameter that is not a parameter pack.
     DI = SemaRef.SubstType(D->getTypeSourceInfo(), TemplateArgs,
                            D->getLocation(), D->getDeclName());
     if (!DI)
       return nullptr;
 
     // Check that this type is acceptable for a non-type template parameter.
     T = SemaRef.CheckNonTypeTemplateParameterType(DI, D->getLocation());
     if (T.isNull()) {
       T = SemaRef.Context.IntTy;
       Invalid = true;
     }
   }
 
   NonTypeTemplateParmDecl *Param;
   if (IsExpandedParameterPack)
     Param = NonTypeTemplateParmDecl::Create(
         SemaRef.Context, Owner, D->getInnerLocStart(), D->getLocation(),
         D->getDepth() - TemplateArgs.getNumSubstitutedLevels(),
         D->getPosition(), D->getIdentifier(), T, DI, ExpandedParameterPackTypes,
         ExpandedParameterPackTypesAsWritten);
   else
     Param = NonTypeTemplateParmDecl::Create(
         SemaRef.Context, Owner, D->getInnerLocStart(), D->getLocation(),
         D->getDepth() - TemplateArgs.getNumSubstitutedLevels(),
         D->getPosition(), D->getIdentifier(), T, D->isParameterPack(), DI);
 
   if (AutoTypeLoc AutoLoc = DI->getTypeLoc().getContainedAutoTypeLoc())
     if (AutoLoc.isConstrained())
       // Note: We attach the uninstantiated constriant here, so that it can be
       // instantiated relative to the top level, like all our other constraints.
       if (SemaRef.AttachTypeConstraint(
               AutoLoc, Param, D,
               IsExpandedParameterPack
                 ? DI->getTypeLoc().getAs<PackExpansionTypeLoc>()
                     .getEllipsisLoc()
                 : SourceLocation()))
         Invalid = true;
 
   Param->setAccess(AS_public);
   Param->setImplicit(D->isImplicit());
   if (Invalid)
     Param->setInvalidDecl();
 
   if (D->hasDefaultArgument() && !D->defaultArgumentWasInherited()) {
     EnterExpressionEvaluationContext ConstantEvaluated(
         SemaRef, Sema::ExpressionEvaluationContext::ConstantEvaluated);
     ExprResult Value = SemaRef.SubstExpr(D->getDefaultArgument(), TemplateArgs);
     if (!Value.isInvalid())
       Param->setDefaultArgument(Value.get());
   }
 
   // Introduce this template parameter's instantiation into the instantiation
   // scope.
   SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, Param);
   return Param;
 }
 
 static void collectUnexpandedParameterPacks(
     Sema &S,
     TemplateParameterList *Params,
     SmallVectorImpl<UnexpandedParameterPack> &Unexpanded) {
   for (const auto &P : *Params) {
     if (P->isTemplateParameterPack())
       continue;
     if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(P))
       S.collectUnexpandedParameterPacks(NTTP->getTypeSourceInfo()->getTypeLoc(),
                                         Unexpanded);
     if (TemplateTemplateParmDecl *TTP = dyn_cast<TemplateTemplateParmDecl>(P))
       collectUnexpandedParameterPacks(S, TTP->getTemplateParameters(),
                                       Unexpanded);
   }
 }
 
 Decl *
 TemplateDeclInstantiator::VisitTemplateTemplateParmDecl(
                                                   TemplateTemplateParmDecl *D) {
   // Instantiate the template parameter list of the template template parameter.
   TemplateParameterList *TempParams = D->getTemplateParameters();
   TemplateParameterList *InstParams;
   SmallVector<TemplateParameterList*, 8> ExpandedParams;
 
   bool IsExpandedParameterPack = false;
 
   if (D->isExpandedParameterPack()) {
     // The template template parameter pack is an already-expanded pack
     // expansion of template parameters. Substitute into each of the expanded
     // parameters.
     ExpandedParams.reserve(D->getNumExpansionTemplateParameters());
     for (unsigned I = 0, N = D->getNumExpansionTemplateParameters();
          I != N; ++I) {
       LocalInstantiationScope Scope(SemaRef);
       TemplateParameterList *Expansion =
         SubstTemplateParams(D->getExpansionTemplateParameters(I));
       if (!Expansion)
         return nullptr;
       ExpandedParams.push_back(Expansion);
     }
 
     IsExpandedParameterPack = true;
     InstParams = TempParams;
   } else if (D->isPackExpansion()) {
     // The template template parameter pack expands to a pack of template
     // template parameters. Determine whether we need to expand this parameter
     // pack into separate parameters.
     SmallVector<UnexpandedParameterPack, 2> Unexpanded;
     collectUnexpandedParameterPacks(SemaRef, D->getTemplateParameters(),
                                     Unexpanded);
 
     // Determine whether the set of unexpanded parameter packs can and should
     // be expanded.
     bool Expand = true;
     bool RetainExpansion = false;
     std::optional<unsigned> NumExpansions;
     if (SemaRef.CheckParameterPacksForExpansion(D->getLocation(),
                                                 TempParams->getSourceRange(),
                                                 Unexpanded,
                                                 TemplateArgs,
                                                 Expand, RetainExpansion,
                                                 NumExpansions))
       return nullptr;
 
     if (Expand) {
       for (unsigned I = 0; I != *NumExpansions; ++I) {
         Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(SemaRef, I);
         LocalInstantiationScope Scope(SemaRef);
         TemplateParameterList *Expansion = SubstTemplateParams(TempParams);
         if (!Expansion)
           return nullptr;
         ExpandedParams.push_back(Expansion);
       }
 
       // Note that we have an expanded parameter pack. The "type" of this
       // expanded parameter pack is the original expansion type, but callers
       // will end up using the expanded parameter pack types for type-checking.
       IsExpandedParameterPack = true;
       InstParams = TempParams;
     } else {
       // We cannot fully expand the pack expansion now, so just substitute
       // into the pattern.
       Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(SemaRef, -1);
 
       LocalInstantiationScope Scope(SemaRef);
       InstParams = SubstTemplateParams(TempParams);
       if (!InstParams)
         return nullptr;
     }
   } else {
     // Perform the actual substitution of template parameters within a new,
     // local instantiation scope.
     LocalInstantiationScope Scope(SemaRef);
     InstParams = SubstTemplateParams(TempParams);
     if (!InstParams)
       return nullptr;
   }
 
   // Build the template template parameter.
   TemplateTemplateParmDecl *Param;
   if (IsExpandedParameterPack)
     Param = TemplateTemplateParmDecl::Create(
         SemaRef.Context, Owner, D->getLocation(),
         D->getDepth() - TemplateArgs.getNumSubstitutedLevels(),
         D->getPosition(), D->getIdentifier(), InstParams, ExpandedParams);
   else
     Param = TemplateTemplateParmDecl::Create(
         SemaRef.Context, Owner, D->getLocation(),
         D->getDepth() - TemplateArgs.getNumSubstitutedLevels(),
         D->getPosition(), D->isParameterPack(), D->getIdentifier(), InstParams);
   if (D->hasDefaultArgument() && !D->defaultArgumentWasInherited()) {
     NestedNameSpecifierLoc QualifierLoc =
         D->getDefaultArgument().getTemplateQualifierLoc();
     QualifierLoc =
         SemaRef.SubstNestedNameSpecifierLoc(QualifierLoc, TemplateArgs);
     TemplateName TName = SemaRef.SubstTemplateName(
         QualifierLoc, D->getDefaultArgument().getArgument().getAsTemplate(),
         D->getDefaultArgument().getTemplateNameLoc(), TemplateArgs);
     if (!TName.isNull())
       Param->setDefaultArgument(
           SemaRef.Context,
           TemplateArgumentLoc(SemaRef.Context, TemplateArgument(TName),
                               D->getDefaultArgument().getTemplateQualifierLoc(),
                               D->getDefaultArgument().getTemplateNameLoc()));
   }
   Param->setAccess(AS_public);
   Param->setImplicit(D->isImplicit());
 
   // Introduce this template parameter's instantiation into the instantiation
   // scope.
   SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, Param);
 
   return Param;
 }
 
 Decl *TemplateDeclInstantiator::VisitUsingDirectiveDecl(UsingDirectiveDecl *D) {
   // Using directives are never dependent (and never contain any types or
   // expressions), so they require no explicit instantiation work.
 
   UsingDirectiveDecl *Inst
     = UsingDirectiveDecl::Create(SemaRef.Context, Owner, D->getLocation(),
                                  D->getNamespaceKeyLocation(),
                                  D->getQualifierLoc(),
                                  D->getIdentLocation(),
                                  D->getNominatedNamespace(),
                                  D->getCommonAncestor());
 
   // Add the using directive to its declaration context
   // only if this is not a function or method.
   if (!Owner->isFunctionOrMethod())
     Owner->addDecl(Inst);
 
   return Inst;
 }
 
 Decl *TemplateDeclInstantiator::VisitBaseUsingDecls(BaseUsingDecl *D,
                                                     BaseUsingDecl *Inst,
                                                     LookupResult *Lookup) {
 
   bool isFunctionScope = Owner->isFunctionOrMethod();
 
   for (auto *Shadow : D->shadows()) {
     // FIXME: UsingShadowDecl doesn't preserve its immediate target, so
     // reconstruct it in the case where it matters. Hm, can we extract it from
     // the DeclSpec when parsing and save it in the UsingDecl itself?
     NamedDecl *OldTarget = Shadow->getTargetDecl();
     if (auto *CUSD = dyn_cast<ConstructorUsingShadowDecl>(Shadow))
       if (auto *BaseShadow = CUSD->getNominatedBaseClassShadowDecl())
         OldTarget = BaseShadow;
 
     NamedDecl *InstTarget = nullptr;
     if (auto *EmptyD =
             dyn_cast<UnresolvedUsingIfExistsDecl>(Shadow->getTargetDecl())) {
       InstTarget = UnresolvedUsingIfExistsDecl::Create(
           SemaRef.Context, Owner, EmptyD->getLocation(), EmptyD->getDeclName());
     } else {
       InstTarget = cast_or_null<NamedDecl>(SemaRef.FindInstantiatedDecl(
           Shadow->getLocation(), OldTarget, TemplateArgs));
     }
     if (!InstTarget)
       return nullptr;
 
     UsingShadowDecl *PrevDecl = nullptr;
     if (Lookup &&
         SemaRef.CheckUsingShadowDecl(Inst, InstTarget, *Lookup, PrevDecl))
       continue;
 
     if (UsingShadowDecl *OldPrev = getPreviousDeclForInstantiation(Shadow))
       PrevDecl = cast_or_null<UsingShadowDecl>(SemaRef.FindInstantiatedDecl(
           Shadow->getLocation(), OldPrev, TemplateArgs));
 
     UsingShadowDecl *InstShadow = SemaRef.BuildUsingShadowDecl(
         /*Scope*/ nullptr, Inst, InstTarget, PrevDecl);
     SemaRef.Context.setInstantiatedFromUsingShadowDecl(InstShadow, Shadow);
 
     if (isFunctionScope)
       SemaRef.CurrentInstantiationScope->InstantiatedLocal(Shadow, InstShadow);
   }
 
   return Inst;
 }
 
 Decl *TemplateDeclInstantiator::VisitUsingDecl(UsingDecl *D) {
 
   // The nested name specifier may be dependent, for example
   //     template <typename T> struct t {
   //       struct s1 { T f1(); };
   //       struct s2 : s1 { using s1::f1; };
   //     };
   //     template struct t<int>;
   // Here, in using s1::f1, s1 refers to t<T>::s1;
   // we need to substitute for t<int>::s1.
   NestedNameSpecifierLoc QualifierLoc
     = SemaRef.SubstNestedNameSpecifierLoc(D->getQualifierLoc(),
                                           TemplateArgs);
   if (!QualifierLoc)
     return nullptr;
 
   // For an inheriting constructor declaration, the name of the using
   // declaration is the name of a constructor in this class, not in the
   // base class.
   DeclarationNameInfo NameInfo = D->getNameInfo();
   if (NameInfo.getName().getNameKind() == DeclarationName::CXXConstructorName)
     if (auto *RD = dyn_cast<CXXRecordDecl>(SemaRef.CurContext))
       NameInfo.setName(SemaRef.Context.DeclarationNames.getCXXConstructorName(
           SemaRef.Context.getCanonicalType(SemaRef.Context.getRecordType(RD))));
 
   // We only need to do redeclaration lookups if we're in a class scope (in
   // fact, it's not really even possible in non-class scopes).
   bool CheckRedeclaration = Owner->isRecord();
   LookupResult Prev(SemaRef, NameInfo, Sema::LookupUsingDeclName,
                     Sema::ForVisibleRedeclaration);
 
   UsingDecl *NewUD = UsingDecl::Create(SemaRef.Context, Owner,
                                        D->getUsingLoc(),
                                        QualifierLoc,
                                        NameInfo,
                                        D->hasTypename());
 
   CXXScopeSpec SS;
   SS.Adopt(QualifierLoc);
   if (CheckRedeclaration) {
     Prev.setHideTags(false);
     SemaRef.LookupQualifiedName(Prev, Owner);
 
     // Check for invalid redeclarations.
     if (SemaRef.CheckUsingDeclRedeclaration(D->getUsingLoc(),
                                             D->hasTypename(), SS,
                                             D->getLocation(), Prev))
       NewUD->setInvalidDecl();
   }
 
   if (!NewUD->isInvalidDecl() &&
       SemaRef.CheckUsingDeclQualifier(D->getUsingLoc(), D->hasTypename(), SS,
                                       NameInfo, D->getLocation(), nullptr, D))
     NewUD->setInvalidDecl();
 
   SemaRef.Context.setInstantiatedFromUsingDecl(NewUD, D);
   NewUD->setAccess(D->getAccess());
   Owner->addDecl(NewUD);
 
   // Don't process the shadow decls for an invalid decl.
   if (NewUD->isInvalidDecl())
     return NewUD;
 
   // If the using scope was dependent, or we had dependent bases, we need to
   // recheck the inheritance
   if (NameInfo.getName().getNameKind() == DeclarationName::CXXConstructorName)
     SemaRef.CheckInheritingConstructorUsingDecl(NewUD);
 
   return VisitBaseUsingDecls(D, NewUD, CheckRedeclaration ? &Prev : nullptr);
 }
 
 Decl *TemplateDeclInstantiator::VisitUsingEnumDecl(UsingEnumDecl *D) {
   // Cannot be a dependent type, but still could be an instantiation
   EnumDecl *EnumD = cast_or_null<EnumDecl>(SemaRef.FindInstantiatedDecl(
       D->getLocation(), D->getEnumDecl(), TemplateArgs));
 
   if (SemaRef.RequireCompleteEnumDecl(EnumD, EnumD->getLocation()))
     return nullptr;
 
   TypeSourceInfo *TSI = SemaRef.SubstType(D->getEnumType(), TemplateArgs,
                                           D->getLocation(), D->getDeclName());
   UsingEnumDecl *NewUD =
       UsingEnumDecl::Create(SemaRef.Context, Owner, D->getUsingLoc(),
                             D->getEnumLoc(), D->getLocation(), TSI);
 
   SemaRef.Context.setInstantiatedFromUsingEnumDecl(NewUD, D);
   NewUD->setAccess(D->getAccess());
   Owner->addDecl(NewUD);
 
   // Don't process the shadow decls for an invalid decl.
   if (NewUD->isInvalidDecl())
     return NewUD;
 
   // We don't have to recheck for duplication of the UsingEnumDecl itself, as it
   // cannot be dependent, and will therefore have been checked during template
   // definition.
 
   return VisitBaseUsingDecls(D, NewUD, nullptr);
 }
 
 Decl *TemplateDeclInstantiator::VisitUsingShadowDecl(UsingShadowDecl *D) {
   // Ignore these;  we handle them in bulk when processing the UsingDecl.
   return nullptr;
 }
 
 Decl *TemplateDeclInstantiator::VisitConstructorUsingShadowDecl(
     ConstructorUsingShadowDecl *D) {
   // Ignore these;  we handle them in bulk when processing the UsingDecl.
   return nullptr;
 }
 
 template <typename T>
 Decl *TemplateDeclInstantiator::instantiateUnresolvedUsingDecl(
     T *D, bool InstantiatingPackElement) {
   // If this is a pack expansion, expand it now.
   if (D->isPackExpansion() && !InstantiatingPackElement) {
     SmallVector<UnexpandedParameterPack, 2> Unexpanded;
     SemaRef.collectUnexpandedParameterPacks(D->getQualifierLoc(), Unexpanded);
     SemaRef.collectUnexpandedParameterPacks(D->getNameInfo(), Unexpanded);
 
     // Determine whether the set of unexpanded parameter packs can and should
     // be expanded.
     bool Expand = true;
     bool RetainExpansion = false;
     std::optional<unsigned> NumExpansions;
     if (SemaRef.CheckParameterPacksForExpansion(
           D->getEllipsisLoc(), D->getSourceRange(), Unexpanded, TemplateArgs,
             Expand, RetainExpansion, NumExpansions))
       return nullptr;
 
     // This declaration cannot appear within a function template signature,
     // so we can't have a partial argument list for a parameter pack.
     assert(!RetainExpansion &&
            "should never need to retain an expansion for UsingPackDecl");
 
     if (!Expand) {
       // We cannot fully expand the pack expansion now, so substitute into the
       // pattern and create a new pack expansion.
       Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(SemaRef, -1);
       return instantiateUnresolvedUsingDecl(D, true);
     }
 
     // Within a function, we don't have any normal way to check for conflicts
     // between shadow declarations from different using declarations in the
     // same pack expansion, but this is always ill-formed because all expansions
     // must produce (conflicting) enumerators.
     //
     // Sadly we can't just reject this in the template definition because it
     // could be valid if the pack is empty or has exactly one expansion.
     if (D->getDeclContext()->isFunctionOrMethod() && *NumExpansions > 1) {
       SemaRef.Diag(D->getEllipsisLoc(),
                    diag::err_using_decl_redeclaration_expansion);
       return nullptr;
     }
 
     // Instantiate the slices of this pack and build a UsingPackDecl.
     SmallVector<NamedDecl*, 8> Expansions;
     for (unsigned I = 0; I != *NumExpansions; ++I) {
       Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(SemaRef, I);
       Decl *Slice = instantiateUnresolvedUsingDecl(D, true);
       if (!Slice)
         return nullptr;
       // Note that we can still get unresolved using declarations here, if we
       // had arguments for all packs but the pattern also contained other
       // template arguments (this only happens during partial substitution, eg
       // into the body of a generic lambda in a function template).
       Expansions.push_back(cast<NamedDecl>(Slice));
     }
 
     auto *NewD = SemaRef.BuildUsingPackDecl(D, Expansions);
     if (isDeclWithinFunction(D))
       SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, NewD);
     return NewD;
   }
 
   UnresolvedUsingTypenameDecl *TD = dyn_cast<UnresolvedUsingTypenameDecl>(D);
   SourceLocation TypenameLoc = TD ? TD->getTypenameLoc() : SourceLocation();
 
   NestedNameSpecifierLoc QualifierLoc
     = SemaRef.SubstNestedNameSpecifierLoc(D->getQualifierLoc(),
                                           TemplateArgs);
   if (!QualifierLoc)
     return nullptr;
 
   CXXScopeSpec SS;
   SS.Adopt(QualifierLoc);
 
   DeclarationNameInfo NameInfo
     = SemaRef.SubstDeclarationNameInfo(D->getNameInfo(), TemplateArgs);
 
   // Produce a pack expansion only if we're not instantiating a particular
   // slice of a pack expansion.
   bool InstantiatingSlice = D->getEllipsisLoc().isValid() &&
                             SemaRef.ArgumentPackSubstitutionIndex != -1;
   SourceLocation EllipsisLoc =
       InstantiatingSlice ? SourceLocation() : D->getEllipsisLoc();
 
   bool IsUsingIfExists = D->template hasAttr<UsingIfExistsAttr>();
   NamedDecl *UD = SemaRef.BuildUsingDeclaration(
       /*Scope*/ nullptr, D->getAccess(), D->getUsingLoc(),
       /*HasTypename*/ TD, TypenameLoc, SS, NameInfo, EllipsisLoc,
       ParsedAttributesView(),
       /*IsInstantiation*/ true, IsUsingIfExists);
   if (UD) {
     SemaRef.InstantiateAttrs(TemplateArgs, D, UD);
     SemaRef.Context.setInstantiatedFromUsingDecl(UD, D);
   }
 
   return UD;
 }
 
 Decl *TemplateDeclInstantiator::VisitUnresolvedUsingTypenameDecl(
     UnresolvedUsingTypenameDecl *D) {
   return instantiateUnresolvedUsingDecl(D);
 }
 
 Decl *TemplateDeclInstantiator::VisitUnresolvedUsingValueDecl(
     UnresolvedUsingValueDecl *D) {
   return instantiateUnresolvedUsingDecl(D);
 }
 
 Decl *TemplateDeclInstantiator::VisitUnresolvedUsingIfExistsDecl(
     UnresolvedUsingIfExistsDecl *D) {
   llvm_unreachable("referring to unresolved decl out of UsingShadowDecl");
 }
 
 Decl *TemplateDeclInstantiator::VisitUsingPackDecl(UsingPackDecl *D) {
   SmallVector<NamedDecl*, 8> Expansions;
   for (auto *UD : D->expansions()) {
     if (NamedDecl *NewUD =
             SemaRef.FindInstantiatedDecl(D->getLocation(), UD, TemplateArgs))
       Expansions.push_back(NewUD);
     else
       return nullptr;
   }
 
   auto *NewD = SemaRef.BuildUsingPackDecl(D, Expansions);
   if (isDeclWithinFunction(D))
     SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, NewD);
   return NewD;
 }
 
 Decl *TemplateDeclInstantiator::VisitClassScopeFunctionSpecializationDecl(
     ClassScopeFunctionSpecializationDecl *Decl) {
   CXXMethodDecl *OldFD = Decl->getSpecialization();
   return cast_or_null<CXXMethodDecl>(
       VisitCXXMethodDecl(OldFD, nullptr, Decl->getTemplateArgsAsWritten()));
 }
 
 Decl *TemplateDeclInstantiator::VisitOMPThreadPrivateDecl(
                                      OMPThreadPrivateDecl *D) {
   SmallVector<Expr *, 5> Vars;
   for (auto *I : D->varlists()) {
     Expr *Var = SemaRef.SubstExpr(I, TemplateArgs).get();
     assert(isa<DeclRefExpr>(Var) && "threadprivate arg is not a DeclRefExpr");
     Vars.push_back(Var);
   }
 
   OMPThreadPrivateDecl *TD =
     SemaRef.CheckOMPThreadPrivateDecl(D->getLocation(), Vars);
 
   TD->setAccess(AS_public);
   Owner->addDecl(TD);
 
   return TD;
 }
 
 Decl *TemplateDeclInstantiator::VisitOMPAllocateDecl(OMPAllocateDecl *D) {
   SmallVector<Expr *, 5> Vars;
   for (auto *I : D->varlists()) {
     Expr *Var = SemaRef.SubstExpr(I, TemplateArgs).get();
     assert(isa<DeclRefExpr>(Var) && "allocate arg is not a DeclRefExpr");
     Vars.push_back(Var);
   }
   SmallVector<OMPClause *, 4> Clauses;
   // Copy map clauses from the original mapper.
   for (OMPClause *C : D->clauselists()) {
     OMPClause *IC = nullptr;
     if (auto *AC = dyn_cast<OMPAllocatorClause>(C)) {
       ExprResult NewE = SemaRef.SubstExpr(AC->getAllocator(), TemplateArgs);
       if (!NewE.isUsable())
         continue;
       IC = SemaRef.ActOnOpenMPAllocatorClause(
           NewE.get(), AC->getBeginLoc(), AC->getLParenLoc(), AC->getEndLoc());
     } else if (auto *AC = dyn_cast<OMPAlignClause>(C)) {
       ExprResult NewE = SemaRef.SubstExpr(AC->getAlignment(), TemplateArgs);
       if (!NewE.isUsable())
         continue;
       IC = SemaRef.ActOnOpenMPAlignClause(NewE.get(), AC->getBeginLoc(),
                                           AC->getLParenLoc(), AC->getEndLoc());
       // If align clause value ends up being invalid, this can end up null.
       if (!IC)
         continue;
     }
     Clauses.push_back(IC);
   }
 
   Sema::DeclGroupPtrTy Res = SemaRef.ActOnOpenMPAllocateDirective(
       D->getLocation(), Vars, Clauses, Owner);
   if (Res.get().isNull())
     return nullptr;
   return Res.get().getSingleDecl();
 }
 
 Decl *TemplateDeclInstantiator::VisitOMPRequiresDecl(OMPRequiresDecl *D) {
   llvm_unreachable(
       "Requires directive cannot be instantiated within a dependent context");
 }
 
 Decl *TemplateDeclInstantiator::VisitOMPDeclareReductionDecl(
     OMPDeclareReductionDecl *D) {
   // Instantiate type and check if it is allowed.
   const bool RequiresInstantiation =
       D->getType()->isDependentType() ||
       D->getType()->isInstantiationDependentType() ||
       D->getType()->containsUnexpandedParameterPack();
   QualType SubstReductionType;
   if (RequiresInstantiation) {
     SubstReductionType = SemaRef.ActOnOpenMPDeclareReductionType(
         D->getLocation(),
         ParsedType::make(SemaRef.SubstType(
             D->getType(), TemplateArgs, D->getLocation(), DeclarationName())));
   } else {
     SubstReductionType = D->getType();
   }
   if (SubstReductionType.isNull())
     return nullptr;
   Expr *Combiner = D->getCombiner();
   Expr *Init = D->getInitializer();
   bool IsCorrect = true;
   // Create instantiated copy.
   std::pair<QualType, SourceLocation> ReductionTypes[] = {
       std::make_pair(SubstReductionType, D->getLocation())};
   auto *PrevDeclInScope = D->getPrevDeclInScope();
   if (PrevDeclInScope && !PrevDeclInScope->isInvalidDecl()) {
     PrevDeclInScope = cast<OMPDeclareReductionDecl>(
         SemaRef.CurrentInstantiationScope->findInstantiationOf(PrevDeclInScope)
             ->get<Decl *>());
   }
   auto DRD = SemaRef.ActOnOpenMPDeclareReductionDirectiveStart(
       /*S=*/nullptr, Owner, D->getDeclName(), ReductionTypes, D->getAccess(),
       PrevDeclInScope);
   auto *NewDRD = cast<OMPDeclareReductionDecl>(DRD.get().getSingleDecl());
   SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, NewDRD);
   Expr *SubstCombiner = nullptr;
   Expr *SubstInitializer = nullptr;
   // Combiners instantiation sequence.
   if (Combiner) {
     SemaRef.ActOnOpenMPDeclareReductionCombinerStart(
         /*S=*/nullptr, NewDRD);
     SemaRef.CurrentInstantiationScope->InstantiatedLocal(
         cast<DeclRefExpr>(D->getCombinerIn())->getDecl(),
         cast<DeclRefExpr>(NewDRD->getCombinerIn())->getDecl());
     SemaRef.CurrentInstantiationScope->InstantiatedLocal(
         cast<DeclRefExpr>(D->getCombinerOut())->getDecl(),
         cast<DeclRefExpr>(NewDRD->getCombinerOut())->getDecl());
     auto *ThisContext = dyn_cast_or_null<CXXRecordDecl>(Owner);
     Sema::CXXThisScopeRAII ThisScope(SemaRef, ThisContext, Qualifiers(),
                                      ThisContext);
     SubstCombiner = SemaRef.SubstExpr(Combiner, TemplateArgs).get();
     SemaRef.ActOnOpenMPDeclareReductionCombinerEnd(NewDRD, SubstCombiner);
   }
   // Initializers instantiation sequence.
   if (Init) {
     VarDecl *OmpPrivParm = SemaRef.ActOnOpenMPDeclareReductionInitializerStart(
         /*S=*/nullptr, NewDRD);
     SemaRef.CurrentInstantiationScope->InstantiatedLocal(
         cast<DeclRefExpr>(D->getInitOrig())->getDecl(),
         cast<DeclRefExpr>(NewDRD->getInitOrig())->getDecl());
     SemaRef.CurrentInstantiationScope->InstantiatedLocal(
         cast<DeclRefExpr>(D->getInitPriv())->getDecl(),
         cast<DeclRefExpr>(NewDRD->getInitPriv())->getDecl());
     if (D->getInitializerKind() == OMPDeclareReductionDecl::CallInit) {
       SubstInitializer = SemaRef.SubstExpr(Init, TemplateArgs).get();
     } else {
       auto *OldPrivParm =
           cast<VarDecl>(cast<DeclRefExpr>(D->getInitPriv())->getDecl());
       IsCorrect = IsCorrect && OldPrivParm->hasInit();
       if (IsCorrect)
         SemaRef.InstantiateVariableInitializer(OmpPrivParm, OldPrivParm,
                                                TemplateArgs);
     }
     SemaRef.ActOnOpenMPDeclareReductionInitializerEnd(NewDRD, SubstInitializer,
                                                       OmpPrivParm);
   }
   IsCorrect = IsCorrect && SubstCombiner &&
               (!Init ||
                (D->getInitializerKind() == OMPDeclareReductionDecl::CallInit &&
                 SubstInitializer) ||
                (D->getInitializerKind() != OMPDeclareReductionDecl::CallInit &&
                 !SubstInitializer));
 
   (void)SemaRef.ActOnOpenMPDeclareReductionDirectiveEnd(
       /*S=*/nullptr, DRD, IsCorrect && !D->isInvalidDecl());
 
   return NewDRD;
 }
 
 Decl *
 TemplateDeclInstantiator::VisitOMPDeclareMapperDecl(OMPDeclareMapperDecl *D) {
   // Instantiate type and check if it is allowed.
   const bool RequiresInstantiation =
       D->getType()->isDependentType() ||
       D->getType()->isInstantiationDependentType() ||
       D->getType()->containsUnexpandedParameterPack();
   QualType SubstMapperTy;
   DeclarationName VN = D->getVarName();
   if (RequiresInstantiation) {
     SubstMapperTy = SemaRef.ActOnOpenMPDeclareMapperType(
         D->getLocation(),
         ParsedType::make(SemaRef.SubstType(D->getType(), TemplateArgs,
                                            D->getLocation(), VN)));
   } else {
     SubstMapperTy = D->getType();
   }
   if (SubstMapperTy.isNull())
     return nullptr;
   // Create an instantiated copy of mapper.
   auto *PrevDeclInScope = D->getPrevDeclInScope();
   if (PrevDeclInScope && !PrevDeclInScope->isInvalidDecl()) {
     PrevDeclInScope = cast<OMPDeclareMapperDecl>(
         SemaRef.CurrentInstantiationScope->findInstantiationOf(PrevDeclInScope)
             ->get<Decl *>());
   }
   bool IsCorrect = true;
   SmallVector<OMPClause *, 6> Clauses;
   // Instantiate the mapper variable.
   DeclarationNameInfo DirName;
   SemaRef.StartOpenMPDSABlock(llvm::omp::OMPD_declare_mapper, DirName,
                               /*S=*/nullptr,
                               (*D->clauselist_begin())->getBeginLoc());
   ExprResult MapperVarRef = SemaRef.ActOnOpenMPDeclareMapperDirectiveVarDecl(
       /*S=*/nullptr, SubstMapperTy, D->getLocation(), VN);
   SemaRef.CurrentInstantiationScope->InstantiatedLocal(
       cast<DeclRefExpr>(D->getMapperVarRef())->getDecl(),
       cast<DeclRefExpr>(MapperVarRef.get())->getDecl());
   auto *ThisContext = dyn_cast_or_null<CXXRecordDecl>(Owner);
   Sema::CXXThisScopeRAII ThisScope(SemaRef, ThisContext, Qualifiers(),
                                    ThisContext);
   // Instantiate map clauses.
   for (OMPClause *C : D->clauselists()) {
     auto *OldC = cast<OMPMapClause>(C);
     SmallVector<Expr *, 4> NewVars;
     for (Expr *OE : OldC->varlists()) {
       Expr *NE = SemaRef.SubstExpr(OE, TemplateArgs).get();
       if (!NE) {
         IsCorrect = false;
         break;
       }
       NewVars.push_back(NE);
     }
     if (!IsCorrect)
       break;
     NestedNameSpecifierLoc NewQualifierLoc =
         SemaRef.SubstNestedNameSpecifierLoc(OldC->getMapperQualifierLoc(),
                                             TemplateArgs);
     CXXScopeSpec SS;
     SS.Adopt(NewQualifierLoc);
     DeclarationNameInfo NewNameInfo =
         SemaRef.SubstDeclarationNameInfo(OldC->getMapperIdInfo(), TemplateArgs);
     OMPVarListLocTy Locs(OldC->getBeginLoc(), OldC->getLParenLoc(),
                          OldC->getEndLoc());
     OMPClause *NewC = SemaRef.ActOnOpenMPMapClause(
         OldC->getIteratorModifier(), OldC->getMapTypeModifiers(),
         OldC->getMapTypeModifiersLoc(), SS, NewNameInfo, OldC->getMapType(),
         OldC->isImplicitMapType(), OldC->getMapLoc(), OldC->getColonLoc(),
         NewVars, Locs);
     Clauses.push_back(NewC);
   }
   SemaRef.EndOpenMPDSABlock(nullptr);
   if (!IsCorrect)
     return nullptr;
   Sema::DeclGroupPtrTy DG = SemaRef.ActOnOpenMPDeclareMapperDirective(
       /*S=*/nullptr, Owner, D->getDeclName(), SubstMapperTy, D->getLocation(),
       VN, D->getAccess(), MapperVarRef.get(), Clauses, PrevDeclInScope);
   Decl *NewDMD = DG.get().getSingleDecl();
   SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, NewDMD);
   return NewDMD;
 }
 
 Decl *TemplateDeclInstantiator::VisitOMPCapturedExprDecl(
     OMPCapturedExprDecl * /*D*/) {
   llvm_unreachable("Should not be met in templates");
 }
 
 Decl *TemplateDeclInstantiator::VisitFunctionDecl(FunctionDecl *D) {
   return VisitFunctionDecl(D, nullptr);
 }
 
 Decl *
 TemplateDeclInstantiator::VisitCXXDeductionGuideDecl(CXXDeductionGuideDecl *D) {
   Decl *Inst = VisitFunctionDecl(D, nullptr);
   if (Inst && !D->getDescribedFunctionTemplate())
     Owner->addDecl(Inst);
   return Inst;
 }
 
 Decl *TemplateDeclInstantiator::VisitCXXMethodDecl(CXXMethodDecl *D) {
   return VisitCXXMethodDecl(D, nullptr);
 }
 
 Decl *TemplateDeclInstantiator::VisitRecordDecl(RecordDecl *D) {
   llvm_unreachable("There are only CXXRecordDecls in C++");
 }
 
 Decl *
 TemplateDeclInstantiator::VisitClassTemplateSpecializationDecl(
     ClassTemplateSpecializationDecl *D) {
   // As a MS extension, we permit class-scope explicit specialization
   // of member class templates.
   ClassTemplateDecl *ClassTemplate = D->getSpecializedTemplate();
   assert(ClassTemplate->getDeclContext()->isRecord() &&
          D->getTemplateSpecializationKind() == TSK_ExplicitSpecialization &&
          "can only instantiate an explicit specialization "
          "for a member class template");
 
   // Lookup the already-instantiated declaration in the instantiation
   // of the class template.
   ClassTemplateDecl *InstClassTemplate =
       cast_or_null<ClassTemplateDecl>(SemaRef.FindInstantiatedDecl(
           D->getLocation(), ClassTemplate, TemplateArgs));
   if (!InstClassTemplate)
     return nullptr;
 
   // Substitute into the template arguments of the class template explicit
   // specialization.
   TemplateSpecializationTypeLoc Loc = D->getTypeAsWritten()->getTypeLoc().
                                         castAs<TemplateSpecializationTypeLoc>();
   TemplateArgumentListInfo InstTemplateArgs(Loc.getLAngleLoc(),
                                             Loc.getRAngleLoc());
   SmallVector<TemplateArgumentLoc, 4> ArgLocs;
   for (unsigned I = 0; I != Loc.getNumArgs(); ++I)
     ArgLocs.push_back(Loc.getArgLoc(I));
   if (SemaRef.SubstTemplateArguments(ArgLocs, TemplateArgs, InstTemplateArgs))
     return nullptr;
 
   // Check that the template argument list is well-formed for this
   // class template.
   SmallVector<TemplateArgument, 4> SugaredConverted, CanonicalConverted;
   if (SemaRef.CheckTemplateArgumentList(InstClassTemplate, D->getLocation(),
                                         InstTemplateArgs, false,
                                         SugaredConverted, CanonicalConverted,
                                         /*UpdateArgsWithConversions=*/true))
     return nullptr;
 
   // Figure out where to insert this class template explicit specialization
   // in the member template's set of class template explicit specializations.
   void *InsertPos = nullptr;
   ClassTemplateSpecializationDecl *PrevDecl =
       InstClassTemplate->findSpecialization(CanonicalConverted, InsertPos);
 
   // Check whether we've already seen a conflicting instantiation of this
   // declaration (for instance, if there was a prior implicit instantiation).
   bool Ignored;
   if (PrevDecl &&
       SemaRef.CheckSpecializationInstantiationRedecl(D->getLocation(),
                                                      D->getSpecializationKind(),
                                                      PrevDecl,
                                                      PrevDecl->getSpecializationKind(),
                                                      PrevDecl->getPointOfInstantiation(),
                                                      Ignored))
     return nullptr;
 
   // If PrevDecl was a definition and D is also a definition, diagnose.
   // This happens in cases like:
   //
   //   template<typename T, typename U>
   //   struct Outer {
   //     template<typename X> struct Inner;
   //     template<> struct Inner<T> {};
   //     template<> struct Inner<U> {};
   //   };
   //
   //   Outer<int, int> outer; // error: the explicit specializations of Inner
   //                          // have the same signature.
   if (PrevDecl && PrevDecl->getDefinition() &&
       D->isThisDeclarationADefinition()) {
     SemaRef.Diag(D->getLocation(), diag::err_redefinition) << PrevDecl;
     SemaRef.Diag(PrevDecl->getDefinition()->getLocation(),
                  diag::note_previous_definition);
     return nullptr;
   }
 
   // Create the class template partial specialization declaration.
   ClassTemplateSpecializationDecl *InstD =
       ClassTemplateSpecializationDecl::Create(
           SemaRef.Context, D->getTagKind(), Owner, D->getBeginLoc(),
           D->getLocation(), InstClassTemplate, CanonicalConverted, PrevDecl);
 
   // Add this partial specialization to the set of class template partial
   // specializations.
   if (!PrevDecl)
     InstClassTemplate->AddSpecialization(InstD, InsertPos);
 
   // Substitute the nested name specifier, if any.
   if (SubstQualifier(D, InstD))
     return nullptr;
 
   // Build the canonical type that describes the converted template
   // arguments of the class template explicit specialization.
   QualType CanonType = SemaRef.Context.getTemplateSpecializationType(
       TemplateName(InstClassTemplate), CanonicalConverted,
       SemaRef.Context.getRecordType(InstD));
 
   // Build the fully-sugared type for this class template
   // specialization as the user wrote in the specialization
   // itself. This means that we'll pretty-print the type retrieved
   // from the specialization's declaration the way that the user
   // actually wrote the specialization, rather than formatting the
   // name based on the "canonical" representation used to store the
   // template arguments in the specialization.
   TypeSourceInfo *WrittenTy = SemaRef.Context.getTemplateSpecializationTypeInfo(
       TemplateName(InstClassTemplate), D->getLocation(), InstTemplateArgs,
       CanonType);
 
   InstD->setAccess(D->getAccess());
   InstD->setInstantiationOfMemberClass(D, TSK_ImplicitInstantiation);
   InstD->setSpecializationKind(D->getSpecializationKind());
   InstD->setTypeAsWritten(WrittenTy);
   InstD->setExternLoc(D->getExternLoc());
   InstD->setTemplateKeywordLoc(D->getTemplateKeywordLoc());
 
   Owner->addDecl(InstD);
 
   // Instantiate the members of the class-scope explicit specialization eagerly.
   // We don't have support for lazy instantiation of an explicit specialization
   // yet, and MSVC eagerly instantiates in this case.
   // FIXME: This is wrong in standard C++.
   if (D->isThisDeclarationADefinition() &&
       SemaRef.InstantiateClass(D->getLocation(), InstD, D, TemplateArgs,
                                TSK_ImplicitInstantiation,
                                /*Complain=*/true))
     return nullptr;
 
   return InstD;
 }
 
 Decl *TemplateDeclInstantiator::VisitVarTemplateSpecializationDecl(
     VarTemplateSpecializationDecl *D) {
 
   TemplateArgumentListInfo VarTemplateArgsInfo;
   VarTemplateDecl *VarTemplate = D->getSpecializedTemplate();
   assert(VarTemplate &&
          "A template specialization without specialized template?");
 
   VarTemplateDecl *InstVarTemplate =
       cast_or_null<VarTemplateDecl>(SemaRef.FindInstantiatedDecl(
           D->getLocation(), VarTemplate, TemplateArgs));
   if (!InstVarTemplate)
     return nullptr;
 
   // Substitute the current template arguments.
   if (const ASTTemplateArgumentListInfo *TemplateArgsInfo =
           D->getTemplateArgsInfo()) {
     VarTemplateArgsInfo.setLAngleLoc(TemplateArgsInfo->getLAngleLoc());
     VarTemplateArgsInfo.setRAngleLoc(TemplateArgsInfo->getRAngleLoc());
 
     if (SemaRef.SubstTemplateArguments(TemplateArgsInfo->arguments(),
                                        TemplateArgs, VarTemplateArgsInfo))
       return nullptr;
   }
 
   // Check that the template argument list is well-formed for this template.
   SmallVector<TemplateArgument, 4> SugaredConverted, CanonicalConverted;
   if (SemaRef.CheckTemplateArgumentList(InstVarTemplate, D->getLocation(),
                                         VarTemplateArgsInfo, false,
                                         SugaredConverted, CanonicalConverted,
                                         /*UpdateArgsWithConversions=*/true))
     return nullptr;
 
   // Check whether we've already seen a declaration of this specialization.
   void *InsertPos = nullptr;
   VarTemplateSpecializationDecl *PrevDecl =
       InstVarTemplate->findSpecialization(CanonicalConverted, InsertPos);
 
   // Check whether we've already seen a conflicting instantiation of this
   // declaration (for instance, if there was a prior implicit instantiation).
   bool Ignored;
   if (PrevDecl && SemaRef.CheckSpecializationInstantiationRedecl(
                       D->getLocation(), D->getSpecializationKind(), PrevDecl,
                       PrevDecl->getSpecializationKind(),
                       PrevDecl->getPointOfInstantiation(), Ignored))
     return nullptr;
 
   return VisitVarTemplateSpecializationDecl(
       InstVarTemplate, D, VarTemplateArgsInfo, CanonicalConverted, PrevDecl);
 }
 
 Decl *TemplateDeclInstantiator::VisitVarTemplateSpecializationDecl(
     VarTemplateDecl *VarTemplate, VarDecl *D,
     const TemplateArgumentListInfo &TemplateArgsInfo,
     ArrayRef<TemplateArgument> Converted,
     VarTemplateSpecializationDecl *PrevDecl) {
 
   // Do substitution on the type of the declaration
   TypeSourceInfo *DI =
       SemaRef.SubstType(D->getTypeSourceInfo(), TemplateArgs,
                         D->getTypeSpecStartLoc(), D->getDeclName());
   if (!DI)
     return nullptr;
 
   if (DI->getType()->isFunctionType()) {
     SemaRef.Diag(D->getLocation(), diag::err_variable_instantiates_to_function)
         << D->isStaticDataMember() << DI->getType();
     return nullptr;
   }
 
   // Build the instantiated declaration
   VarTemplateSpecializationDecl *Var = VarTemplateSpecializationDecl::Create(
       SemaRef.Context, Owner, D->getInnerLocStart(), D->getLocation(),
       VarTemplate, DI->getType(), DI, D->getStorageClass(), Converted);
   Var->setTemplateArgsInfo(TemplateArgsInfo);
   if (!PrevDecl) {
     void *InsertPos = nullptr;
     VarTemplate->findSpecialization(Converted, InsertPos);
     VarTemplate->AddSpecialization(Var, InsertPos);
   }
 
   if (SemaRef.getLangOpts().OpenCL)
     SemaRef.deduceOpenCLAddressSpace(Var);
 
   // Substitute the nested name specifier, if any.
   if (SubstQualifier(D, Var))
     return nullptr;
 
   SemaRef.BuildVariableInstantiation(Var, D, TemplateArgs, LateAttrs, Owner,
                                      StartingScope, false, PrevDecl);
 
   return Var;
 }
 
 Decl *TemplateDeclInstantiator::VisitObjCAtDefsFieldDecl(ObjCAtDefsFieldDecl *D) {
   llvm_unreachable("@defs is not supported in Objective-C++");
 }
 
 Decl *TemplateDeclInstantiator::VisitFriendTemplateDecl(FriendTemplateDecl *D) {
   // FIXME: We need to be able to instantiate FriendTemplateDecls.
   unsigned DiagID = SemaRef.getDiagnostics().getCustomDiagID(
                                                DiagnosticsEngine::Error,
                                                "cannot instantiate %0 yet");
   SemaRef.Diag(D->getLocation(), DiagID)
     << D->getDeclKindName();
 
   return nullptr;
 }
 
 Decl *TemplateDeclInstantiator::VisitConceptDecl(ConceptDecl *D) {
   llvm_unreachable("Concept definitions cannot reside inside a template");
 }
 
 Decl *TemplateDeclInstantiator::VisitImplicitConceptSpecializationDecl(
     ImplicitConceptSpecializationDecl *D) {
   llvm_unreachable("Concept specializations cannot reside inside a template");
 }
 
 Decl *
 TemplateDeclInstantiator::VisitRequiresExprBodyDecl(RequiresExprBodyDecl *D) {
   return RequiresExprBodyDecl::Create(SemaRef.Context, D->getDeclContext(),
                                       D->getBeginLoc());
 }
 
 Decl *TemplateDeclInstantiator::VisitDecl(Decl *D) {
   llvm_unreachable("Unexpected decl");
 }
 
 Decl *Sema::SubstDecl(Decl *D, DeclContext *Owner,
                       const MultiLevelTemplateArgumentList &TemplateArgs) {
   TemplateDeclInstantiator Instantiator(*this, Owner, TemplateArgs);
   if (D->isInvalidDecl())
     return nullptr;
 
   Decl *SubstD;
   runWithSufficientStackSpace(D->getLocation(), [&] {
     SubstD = Instantiator.Visit(D);
   });
   return SubstD;
 }
 
 void TemplateDeclInstantiator::adjustForRewrite(RewriteKind RK,
                                                 FunctionDecl *Orig, QualType &T,
                                                 TypeSourceInfo *&TInfo,
                                                 DeclarationNameInfo &NameInfo) {
   assert(RK == RewriteKind::RewriteSpaceshipAsEqualEqual);
 
   // C++2a [class.compare.default]p3:
   //   the return type is replaced with bool
   auto *FPT = T->castAs<FunctionProtoType>();
   T = SemaRef.Context.getFunctionType(
       SemaRef.Context.BoolTy, FPT->getParamTypes(), FPT->getExtProtoInfo());
 
   // Update the return type in the source info too. The most straightforward
   // way is to create new TypeSourceInfo for the new type. Use the location of
   // the '= default' as the location of the new type.
   //
   // FIXME: Set the correct return type when we initially transform the type,
   // rather than delaying it to now.
   TypeSourceInfo *NewTInfo =
       SemaRef.Context.getTrivialTypeSourceInfo(T, Orig->getEndLoc());
   auto OldLoc = TInfo->getTypeLoc().getAsAdjusted<FunctionProtoTypeLoc>();
   assert(OldLoc && "type of function is not a function type?");
   auto NewLoc = NewTInfo->getTypeLoc().castAs<FunctionProtoTypeLoc>();
   for (unsigned I = 0, N = OldLoc.getNumParams(); I != N; ++I)
     NewLoc.setParam(I, OldLoc.getParam(I));
   TInfo = NewTInfo;
 
   //   and the declarator-id is replaced with operator==
   NameInfo.setName(
       SemaRef.Context.DeclarationNames.getCXXOperatorName(OO_EqualEqual));
 }
 
 FunctionDecl *Sema::SubstSpaceshipAsEqualEqual(CXXRecordDecl *RD,
                                                FunctionDecl *Spaceship) {
   if (Spaceship->isInvalidDecl())
     return nullptr;
 
   // C++2a [class.compare.default]p3:
   //   an == operator function is declared implicitly [...] with the same
   //   access and function-definition and in the same class scope as the
   //   three-way comparison operator function
   MultiLevelTemplateArgumentList NoTemplateArgs;
   NoTemplateArgs.setKind(TemplateSubstitutionKind::Rewrite);
   NoTemplateArgs.addOuterRetainedLevels(RD->getTemplateDepth());
   TemplateDeclInstantiator Instantiator(*this, RD, NoTemplateArgs);
   Decl *R;
   if (auto *MD = dyn_cast<CXXMethodDecl>(Spaceship)) {
     R = Instantiator.VisitCXXMethodDecl(
         MD, nullptr, std::nullopt,
         TemplateDeclInstantiator::RewriteKind::RewriteSpaceshipAsEqualEqual);
   } else {
     assert(Spaceship->getFriendObjectKind() &&
            "defaulted spaceship is neither a member nor a friend");
 
     R = Instantiator.VisitFunctionDecl(
         Spaceship, nullptr,
         TemplateDeclInstantiator::RewriteKind::RewriteSpaceshipAsEqualEqual);
     if (!R)
       return nullptr;
 
     FriendDecl *FD =
         FriendDecl::Create(Context, RD, Spaceship->getLocation(),
                            cast<NamedDecl>(R), Spaceship->getBeginLoc());
     FD->setAccess(AS_public);
     RD->addDecl(FD);
   }
   return cast_or_null<FunctionDecl>(R);
 }
 
 /// Instantiates a nested template parameter list in the current
 /// instantiation context.
 ///
 /// \param L The parameter list to instantiate
 ///
 /// \returns NULL if there was an error
 TemplateParameterList *
 TemplateDeclInstantiator::SubstTemplateParams(TemplateParameterList *L) {
   // Get errors for all the parameters before bailing out.
   bool Invalid = false;
 
   unsigned N = L->size();
   typedef SmallVector<NamedDecl *, 8> ParamVector;
   ParamVector Params;
   Params.reserve(N);
   for (auto &P : *L) {
     NamedDecl *D = cast_or_null<NamedDecl>(Visit(P));
     Params.push_back(D);
     Invalid = Invalid || !D || D->isInvalidDecl();
   }
 
   // Clean up if we had an error.
   if (Invalid)
     return nullptr;
 
   Expr *InstRequiresClause = L->getRequiresClause();
 
   TemplateParameterList *InstL
     = TemplateParameterList::Create(SemaRef.Context, L->getTemplateLoc(),
                                     L->getLAngleLoc(), Params,
                                     L->getRAngleLoc(), InstRequiresClause);
   return InstL;
 }
 
 TemplateParameterList *
 Sema::SubstTemplateParams(TemplateParameterList *Params, DeclContext *Owner,
                           const MultiLevelTemplateArgumentList &TemplateArgs,
                           bool EvaluateConstraints) {
   TemplateDeclInstantiator Instantiator(*this, Owner, TemplateArgs);
   Instantiator.setEvaluateConstraints(EvaluateConstraints);
   return Instantiator.SubstTemplateParams(Params);
 }
 
 /// Instantiate the declaration of a class template partial
 /// specialization.
 ///
 /// \param ClassTemplate the (instantiated) class template that is partially
 // specialized by the instantiation of \p PartialSpec.
 ///
 /// \param PartialSpec the (uninstantiated) class template partial
 /// specialization that we are instantiating.
 ///
 /// \returns The instantiated partial specialization, if successful; otherwise,
 /// NULL to indicate an error.
 ClassTemplatePartialSpecializationDecl *
 TemplateDeclInstantiator::InstantiateClassTemplatePartialSpecialization(
                                             ClassTemplateDecl *ClassTemplate,
                           ClassTemplatePartialSpecializationDecl *PartialSpec) {
   // Create a local instantiation scope for this class template partial
   // specialization, which will contain the instantiations of the template
   // parameters.
   LocalInstantiationScope Scope(SemaRef);
 
   // Substitute into the template parameters of the class template partial
   // specialization.
   TemplateParameterList *TempParams = PartialSpec->getTemplateParameters();
   TemplateParameterList *InstParams = SubstTemplateParams(TempParams);
   if (!InstParams)
     return nullptr;
 
   // Substitute into the template arguments of the class template partial
   // specialization.
   const ASTTemplateArgumentListInfo *TemplArgInfo
     = PartialSpec->getTemplateArgsAsWritten();
   TemplateArgumentListInfo InstTemplateArgs(TemplArgInfo->LAngleLoc,
                                             TemplArgInfo->RAngleLoc);
   if (SemaRef.SubstTemplateArguments(TemplArgInfo->arguments(), TemplateArgs,
                                      InstTemplateArgs))
     return nullptr;
 
   // Check that the template argument list is well-formed for this
   // class template.
   SmallVector<TemplateArgument, 4> SugaredConverted, CanonicalConverted;
   if (SemaRef.CheckTemplateArgumentList(
           ClassTemplate, PartialSpec->getLocation(), InstTemplateArgs,
           /*PartialTemplateArgs=*/false, SugaredConverted, CanonicalConverted))
     return nullptr;
 
   // Check these arguments are valid for a template partial specialization.
   if (SemaRef.CheckTemplatePartialSpecializationArgs(
           PartialSpec->getLocation(), ClassTemplate, InstTemplateArgs.size(),
           CanonicalConverted))
     return nullptr;
 
   // Figure out where to insert this class template partial specialization
   // in the member template's set of class template partial specializations.
   void *InsertPos = nullptr;
   ClassTemplateSpecializationDecl *PrevDecl =
       ClassTemplate->findPartialSpecialization(CanonicalConverted, InstParams,
                                                InsertPos);
 
   // Build the canonical type that describes the converted template
   // arguments of the class template partial specialization.
   QualType CanonType = SemaRef.Context.getTemplateSpecializationType(
       TemplateName(ClassTemplate), CanonicalConverted);
 
   // Build the fully-sugared type for this class template
   // specialization as the user wrote in the specialization
   // itself. This means that we'll pretty-print the type retrieved
   // from the specialization's declaration the way that the user
   // actually wrote the specialization, rather than formatting the
   // name based on the "canonical" representation used to store the
   // template arguments in the specialization.
   TypeSourceInfo *WrittenTy
     = SemaRef.Context.getTemplateSpecializationTypeInfo(
                                                     TemplateName(ClassTemplate),
                                                     PartialSpec->getLocation(),
                                                     InstTemplateArgs,
                                                     CanonType);
 
   if (PrevDecl) {
     // We've already seen a partial specialization with the same template
     // parameters and template arguments. This can happen, for example, when
     // substituting the outer template arguments ends up causing two
     // class template partial specializations of a member class template
     // to have identical forms, e.g.,
     //
     //   template<typename T, typename U>
     //   struct Outer {
     //     template<typename X, typename Y> struct Inner;
     //     template<typename Y> struct Inner<T, Y>;
     //     template<typename Y> struct Inner<U, Y>;
     //   };
     //
     //   Outer<int, int> outer; // error: the partial specializations of Inner
     //                          // have the same signature.
     SemaRef.Diag(PartialSpec->getLocation(), diag::err_partial_spec_redeclared)
       << WrittenTy->getType();
     SemaRef.Diag(PrevDecl->getLocation(), diag::note_prev_partial_spec_here)
       << SemaRef.Context.getTypeDeclType(PrevDecl);
     return nullptr;
   }
 
 
   // Create the class template partial specialization declaration.
   ClassTemplatePartialSpecializationDecl *InstPartialSpec =
       ClassTemplatePartialSpecializationDecl::Create(
           SemaRef.Context, PartialSpec->getTagKind(), Owner,
           PartialSpec->getBeginLoc(), PartialSpec->getLocation(), InstParams,
           ClassTemplate, CanonicalConverted, InstTemplateArgs, CanonType,
           nullptr);
   // Substitute the nested name specifier, if any.
   if (SubstQualifier(PartialSpec, InstPartialSpec))
     return nullptr;
 
   InstPartialSpec->setInstantiatedFromMember(PartialSpec);
   InstPartialSpec->setTypeAsWritten(WrittenTy);
 
   // Check the completed partial specialization.
   SemaRef.CheckTemplatePartialSpecialization(InstPartialSpec);
 
   // Add this partial specialization to the set of class template partial
   // specializations.
   ClassTemplate->AddPartialSpecialization(InstPartialSpec,
                                           /*InsertPos=*/nullptr);
   return InstPartialSpec;
 }
 
 /// Instantiate the declaration of a variable template partial
 /// specialization.
 ///
 /// \param VarTemplate the (instantiated) variable template that is partially
 /// specialized by the instantiation of \p PartialSpec.
 ///
 /// \param PartialSpec the (uninstantiated) variable template partial
 /// specialization that we are instantiating.
 ///
 /// \returns The instantiated partial specialization, if successful; otherwise,
 /// NULL to indicate an error.
 VarTemplatePartialSpecializationDecl *
 TemplateDeclInstantiator::InstantiateVarTemplatePartialSpecialization(
     VarTemplateDecl *VarTemplate,
     VarTemplatePartialSpecializationDecl *PartialSpec) {
   // Create a local instantiation scope for this variable template partial
   // specialization, which will contain the instantiations of the template
   // parameters.
   LocalInstantiationScope Scope(SemaRef);
 
   // Substitute into the template parameters of the variable template partial
   // specialization.
   TemplateParameterList *TempParams = PartialSpec->getTemplateParameters();
   TemplateParameterList *InstParams = SubstTemplateParams(TempParams);
   if (!InstParams)
     return nullptr;
 
   // Substitute into the template arguments of the variable template partial
   // specialization.
   const ASTTemplateArgumentListInfo *TemplArgInfo
     = PartialSpec->getTemplateArgsAsWritten();
   TemplateArgumentListInfo InstTemplateArgs(TemplArgInfo->LAngleLoc,
                                             TemplArgInfo->RAngleLoc);
   if (SemaRef.SubstTemplateArguments(TemplArgInfo->arguments(), TemplateArgs,
                                      InstTemplateArgs))
     return nullptr;
 
   // Check that the template argument list is well-formed for this
   // class template.
   SmallVector<TemplateArgument, 4> SugaredConverted, CanonicalConverted;
   if (SemaRef.CheckTemplateArgumentList(
           VarTemplate, PartialSpec->getLocation(), InstTemplateArgs,
           /*PartialTemplateArgs=*/false, SugaredConverted, CanonicalConverted))
     return nullptr;
 
   // Check these arguments are valid for a template partial specialization.
   if (SemaRef.CheckTemplatePartialSpecializationArgs(
           PartialSpec->getLocation(), VarTemplate, InstTemplateArgs.size(),
           CanonicalConverted))
     return nullptr;
 
   // Figure out where to insert this variable template partial specialization
   // in the member template's set of variable template partial specializations.
   void *InsertPos = nullptr;
   VarTemplateSpecializationDecl *PrevDecl =
       VarTemplate->findPartialSpecialization(CanonicalConverted, InstParams,
                                              InsertPos);
 
   // Build the canonical type that describes the converted template
   // arguments of the variable template partial specialization.
   QualType CanonType = SemaRef.Context.getTemplateSpecializationType(
       TemplateName(VarTemplate), CanonicalConverted);
 
   // Build the fully-sugared type for this variable template
   // specialization as the user wrote in the specialization
   // itself. This means that we'll pretty-print the type retrieved
   // from the specialization's declaration the way that the user
   // actually wrote the specialization, rather than formatting the
   // name based on the "canonical" representation used to store the
   // template arguments in the specialization.
   TypeSourceInfo *WrittenTy = SemaRef.Context.getTemplateSpecializationTypeInfo(
       TemplateName(VarTemplate), PartialSpec->getLocation(), InstTemplateArgs,
       CanonType);
 
   if (PrevDecl) {
     // We've already seen a partial specialization with the same template
     // parameters and template arguments. This can happen, for example, when
     // substituting the outer template arguments ends up causing two
     // variable template partial specializations of a member variable template
     // to have identical forms, e.g.,
     //
     //   template<typename T, typename U>
     //   struct Outer {
     //     template<typename X, typename Y> pair<X,Y> p;
     //     template<typename Y> pair<T, Y> p;
     //     template<typename Y> pair<U, Y> p;
     //   };
     //
     //   Outer<int, int> outer; // error: the partial specializations of Inner
     //                          // have the same signature.
     SemaRef.Diag(PartialSpec->getLocation(),
                  diag::err_var_partial_spec_redeclared)
         << WrittenTy->getType();
     SemaRef.Diag(PrevDecl->getLocation(),
                  diag::note_var_prev_partial_spec_here);
     return nullptr;
   }
 
   // Do substitution on the type of the declaration
   TypeSourceInfo *DI = SemaRef.SubstType(
       PartialSpec->getTypeSourceInfo(), TemplateArgs,
       PartialSpec->getTypeSpecStartLoc(), PartialSpec->getDeclName());
   if (!DI)
     return nullptr;
 
   if (DI->getType()->isFunctionType()) {
     SemaRef.Diag(PartialSpec->getLocation(),
                  diag::err_variable_instantiates_to_function)
         << PartialSpec->isStaticDataMember() << DI->getType();
     return nullptr;
   }
 
   // Create the variable template partial specialization declaration.
   VarTemplatePartialSpecializationDecl *InstPartialSpec =
       VarTemplatePartialSpecializationDecl::Create(
           SemaRef.Context, Owner, PartialSpec->getInnerLocStart(),
           PartialSpec->getLocation(), InstParams, VarTemplate, DI->getType(),
           DI, PartialSpec->getStorageClass(), CanonicalConverted,
           InstTemplateArgs);
 
   // Substitute the nested name specifier, if any.
   if (SubstQualifier(PartialSpec, InstPartialSpec))
     return nullptr;
 
   InstPartialSpec->setInstantiatedFromMember(PartialSpec);
   InstPartialSpec->setTypeAsWritten(WrittenTy);
 
   // Check the completed partial specialization.
   SemaRef.CheckTemplatePartialSpecialization(InstPartialSpec);
 
   // Add this partial specialization to the set of variable template partial
   // specializations. The instantiation of the initializer is not necessary.
   VarTemplate->AddPartialSpecialization(InstPartialSpec, /*InsertPos=*/nullptr);
 
   SemaRef.BuildVariableInstantiation(InstPartialSpec, PartialSpec, TemplateArgs,
                                      LateAttrs, Owner, StartingScope);
 
   return InstPartialSpec;
 }
 
 TypeSourceInfo*
 TemplateDeclInstantiator::SubstFunctionType(FunctionDecl *D,
                               SmallVectorImpl<ParmVarDecl *> &Params) {
   TypeSourceInfo *OldTInfo = D->getTypeSourceInfo();
   assert(OldTInfo && "substituting function without type source info");
   assert(Params.empty() && "parameter vector is non-empty at start");
 
   CXXRecordDecl *ThisContext = nullptr;
   Qualifiers ThisTypeQuals;
   if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(D)) {
     ThisContext = cast<CXXRecordDecl>(Owner);
     ThisTypeQuals = Method->getMethodQualifiers();
   }
 
   TypeSourceInfo *NewTInfo = SemaRef.SubstFunctionDeclType(
       OldTInfo, TemplateArgs, D->getTypeSpecStartLoc(), D->getDeclName(),
       ThisContext, ThisTypeQuals, EvaluateConstraints);
   if (!NewTInfo)
     return nullptr;
 
   TypeLoc OldTL = OldTInfo->getTypeLoc().IgnoreParens();
   if (FunctionProtoTypeLoc OldProtoLoc = OldTL.getAs<FunctionProtoTypeLoc>()) {
     if (NewTInfo != OldTInfo) {
       // Get parameters from the new type info.
       TypeLoc NewTL = NewTInfo->getTypeLoc().IgnoreParens();
       FunctionProtoTypeLoc NewProtoLoc = NewTL.castAs<FunctionProtoTypeLoc>();
       unsigned NewIdx = 0;
       for (unsigned OldIdx = 0, NumOldParams = OldProtoLoc.getNumParams();
            OldIdx != NumOldParams; ++OldIdx) {
         ParmVarDecl *OldParam = OldProtoLoc.getParam(OldIdx);
         if (!OldParam)
           return nullptr;
 
         LocalInstantiationScope *Scope = SemaRef.CurrentInstantiationScope;
 
         std::optional<unsigned> NumArgumentsInExpansion;
         if (OldParam->isParameterPack())
           NumArgumentsInExpansion =
               SemaRef.getNumArgumentsInExpansion(OldParam->getType(),
                                                  TemplateArgs);
         if (!NumArgumentsInExpansion) {
           // Simple case: normal parameter, or a parameter pack that's
           // instantiated to a (still-dependent) parameter pack.
           ParmVarDecl *NewParam = NewProtoLoc.getParam(NewIdx++);
           Params.push_back(NewParam);
           Scope->InstantiatedLocal(OldParam, NewParam);
         } else {
           // Parameter pack expansion: make the instantiation an argument pack.
           Scope->MakeInstantiatedLocalArgPack(OldParam);
           for (unsigned I = 0; I != *NumArgumentsInExpansion; ++I) {
             ParmVarDecl *NewParam = NewProtoLoc.getParam(NewIdx++);
             Params.push_back(NewParam);
             Scope->InstantiatedLocalPackArg(OldParam, NewParam);
           }
         }
       }
     } else {
       // The function type itself was not dependent and therefore no
       // substitution occurred. However, we still need to instantiate
       // the function parameters themselves.
       const FunctionProtoType *OldProto =
           cast<FunctionProtoType>(OldProtoLoc.getType());
       for (unsigned i = 0, i_end = OldProtoLoc.getNumParams(); i != i_end;
            ++i) {
         ParmVarDecl *OldParam = OldProtoLoc.getParam(i);
         if (!OldParam) {
           Params.push_back(SemaRef.BuildParmVarDeclForTypedef(
               D, D->getLocation(), OldProto->getParamType(i)));
           continue;
         }
 
         ParmVarDecl *Parm =
             cast_or_null<ParmVarDecl>(VisitParmVarDecl(OldParam));
         if (!Parm)
           return nullptr;
         Params.push_back(Parm);
       }
     }
   } else {
     // If the type of this function, after ignoring parentheses, is not
     // *directly* a function type, then we're instantiating a function that
     // was declared via a typedef or with attributes, e.g.,
     //
     //   typedef int functype(int, int);
     //   functype func;
     //   int __cdecl meth(int, int);
     //
     // In this case, we'll just go instantiate the ParmVarDecls that we
     // synthesized in the method declaration.
     SmallVector<QualType, 4> ParamTypes;
     Sema::ExtParameterInfoBuilder ExtParamInfos;
     if (SemaRef.SubstParmTypes(D->getLocation(), D->parameters(), nullptr,
                                TemplateArgs, ParamTypes, &Params,
                                ExtParamInfos))
       return nullptr;
   }
 
   return NewTInfo;
 }
 
 /// Introduce the instantiated function parameters into the local
 /// instantiation scope, and set the parameter names to those used
 /// in the template.
 bool Sema::addInstantiatedParametersToScope(
     FunctionDecl *Function, const FunctionDecl *PatternDecl,
     LocalInstantiationScope &Scope,
     const MultiLevelTemplateArgumentList &TemplateArgs) {
   unsigned FParamIdx = 0;
   for (unsigned I = 0, N = PatternDecl->getNumParams(); I != N; ++I) {
     const ParmVarDecl *PatternParam = PatternDecl->getParamDecl(I);
     if (!PatternParam->isParameterPack()) {
       // Simple case: not a parameter pack.
       assert(FParamIdx < Function->getNumParams());
       ParmVarDecl *FunctionParam = Function->getParamDecl(FParamIdx);
       FunctionParam->setDeclName(PatternParam->getDeclName());
       // If the parameter's type is not dependent, update it to match the type
       // in the pattern. They can differ in top-level cv-qualifiers, and we want
       // the pattern's type here. If the type is dependent, they can't differ,
       // per core issue 1668. Substitute into the type from the pattern, in case
       // it's instantiation-dependent.
       // FIXME: Updating the type to work around this is at best fragile.
       if (!PatternDecl->getType()->isDependentType()) {
         QualType T = SubstType(PatternParam->getType(), TemplateArgs,
                                FunctionParam->getLocation(),
                                FunctionParam->getDeclName());
         if (T.isNull())
           return true;
         FunctionParam->setType(T);
       }
 
       Scope.InstantiatedLocal(PatternParam, FunctionParam);
       ++FParamIdx;
       continue;
     }
 
     // Expand the parameter pack.
     Scope.MakeInstantiatedLocalArgPack(PatternParam);
     std::optional<unsigned> NumArgumentsInExpansion =
         getNumArgumentsInExpansion(PatternParam->getType(), TemplateArgs);
     if (NumArgumentsInExpansion) {
       QualType PatternType =
           PatternParam->getType()->castAs<PackExpansionType>()->getPattern();
       for (unsigned Arg = 0; Arg < *NumArgumentsInExpansion; ++Arg) {
         ParmVarDecl *FunctionParam = Function->getParamDecl(FParamIdx);
         FunctionParam->setDeclName(PatternParam->getDeclName());
         if (!PatternDecl->getType()->isDependentType()) {
           Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(*this, Arg);
           QualType T =
               SubstType(PatternType, TemplateArgs, FunctionParam->getLocation(),
                         FunctionParam->getDeclName());
           if (T.isNull())
             return true;
           FunctionParam->setType(T);
         }
 
         Scope.InstantiatedLocalPackArg(PatternParam, FunctionParam);
         ++FParamIdx;
       }
     }
   }
 
   return false;
 }
 
 bool Sema::InstantiateDefaultArgument(SourceLocation CallLoc, FunctionDecl *FD,
                                       ParmVarDecl *Param) {
   assert(Param->hasUninstantiatedDefaultArg());
 
   // Instantiate the expression.
   //
   // FIXME: Pass in a correct Pattern argument, otherwise
   // getTemplateInstantiationArgs uses the lexical context of FD, e.g.
   //
   // template<typename T>
   // struct A {
   //   static int FooImpl();
   //
   //   template<typename Tp>
   //   // bug: default argument A<T>::FooImpl() is evaluated with 2-level
   //   // template argument list [[T], [Tp]], should be [[Tp]].
   //   friend A<Tp> Foo(int a);
   // };
   //
   // template<typename T>
   // A<T> Foo(int a = A<T>::FooImpl());
   MultiLevelTemplateArgumentList TemplateArgs = getTemplateInstantiationArgs(
       FD, /*Final=*/false, nullptr, /*RelativeToPrimary=*/true);
 
   if (SubstDefaultArgument(CallLoc, Param, TemplateArgs, /*ForCallExpr*/ true))
     return true;
 
   if (ASTMutationListener *L = getASTMutationListener())
     L->DefaultArgumentInstantiated(Param);
 
   return false;
 }
 
 void Sema::InstantiateExceptionSpec(SourceLocation PointOfInstantiation,
                                     FunctionDecl *Decl) {
   const FunctionProtoType *Proto = Decl->getType()->castAs<FunctionProtoType>();
   if (Proto->getExceptionSpecType() != EST_Uninstantiated)
     return;
 
   InstantiatingTemplate Inst(*this, PointOfInstantiation, Decl,
                              InstantiatingTemplate::ExceptionSpecification());
   if (Inst.isInvalid()) {
     // We hit the instantiation depth limit. Clear the exception specification
     // so that our callers don't have to cope with EST_Uninstantiated.
     UpdateExceptionSpec(Decl, EST_None);
     return;
   }
   if (Inst.isAlreadyInstantiating()) {
     // This exception specification indirectly depends on itself. Reject.
     // FIXME: Corresponding rule in the standard?
     Diag(PointOfInstantiation, diag::err_exception_spec_cycle) << Decl;
     UpdateExceptionSpec(Decl, EST_None);
     return;
   }
 
   // Enter the scope of this instantiation. We don't use
   // PushDeclContext because we don't have a scope.
   Sema::ContextRAII savedContext(*this, Decl);
   LocalInstantiationScope Scope(*this);
 
   MultiLevelTemplateArgumentList TemplateArgs = getTemplateInstantiationArgs(
       Decl, /*Final=*/false, nullptr, /*RelativeToPrimary*/ true);
 
   // FIXME: We can't use getTemplateInstantiationPattern(false) in general
   // here, because for a non-defining friend declaration in a class template,
   // we don't store enough information to map back to the friend declaration in
   // the template.
   FunctionDecl *Template = Proto->getExceptionSpecTemplate();
   if (addInstantiatedParametersToScope(Decl, Template, Scope, TemplateArgs)) {
     UpdateExceptionSpec(Decl, EST_None);
     return;
   }
 
   SubstExceptionSpec(Decl, Template->getType()->castAs<FunctionProtoType>(),
                      TemplateArgs);
 }
 
 /// Initializes the common fields of an instantiation function
 /// declaration (New) from the corresponding fields of its template (Tmpl).
 ///
 /// \returns true if there was an error
 bool
 TemplateDeclInstantiator::InitFunctionInstantiation(FunctionDecl *New,
                                                     FunctionDecl *Tmpl) {
   New->setImplicit(Tmpl->isImplicit());
 
   // Forward the mangling number from the template to the instantiated decl.
   SemaRef.Context.setManglingNumber(New,
                                     SemaRef.Context.getManglingNumber(Tmpl));
 
   // If we are performing substituting explicitly-specified template arguments
   // or deduced template arguments into a function template and we reach this
   // point, we are now past the point where SFINAE applies and have committed
   // to keeping the new function template specialization. We therefore
   // convert the active template instantiation for the function template
   // into a template instantiation for this specific function template
   // specialization, which is not a SFINAE context, so that we diagnose any
   // further errors in the declaration itself.
   //
   // FIXME: This is a hack.
   typedef Sema::CodeSynthesisContext ActiveInstType;
   ActiveInstType &ActiveInst = SemaRef.CodeSynthesisContexts.back();
   if (ActiveInst.Kind == ActiveInstType::ExplicitTemplateArgumentSubstitution ||
       ActiveInst.Kind == ActiveInstType::DeducedTemplateArgumentSubstitution) {
     if (isa<FunctionTemplateDecl>(ActiveInst.Entity)) {
       SemaRef.InstantiatingSpecializations.erase(
           {ActiveInst.Entity->getCanonicalDecl(), ActiveInst.Kind});
       atTemplateEnd(SemaRef.TemplateInstCallbacks, SemaRef, ActiveInst);
       ActiveInst.Kind = ActiveInstType::TemplateInstantiation;
       ActiveInst.Entity = New;
       atTemplateBegin(SemaRef.TemplateInstCallbacks, SemaRef, ActiveInst);
     }
   }
 
   const FunctionProtoType *Proto = Tmpl->getType()->getAs<FunctionProtoType>();
   assert(Proto && "Function template without prototype?");
 
   if (Proto->hasExceptionSpec() || Proto->getNoReturnAttr()) {
     FunctionProtoType::ExtProtoInfo EPI = Proto->getExtProtoInfo();
 
     // DR1330: In C++11, defer instantiation of a non-trivial
     // exception specification.
     // DR1484: Local classes and their members are instantiated along with the
     // containing function.
     if (SemaRef.getLangOpts().CPlusPlus11 &&
         EPI.ExceptionSpec.Type != EST_None &&
         EPI.ExceptionSpec.Type != EST_DynamicNone &&
         EPI.ExceptionSpec.Type != EST_BasicNoexcept &&
         !Tmpl->isInLocalScopeForInstantiation()) {
       FunctionDecl *ExceptionSpecTemplate = Tmpl;
       if (EPI.ExceptionSpec.Type == EST_Uninstantiated)
         ExceptionSpecTemplate = EPI.ExceptionSpec.SourceTemplate;
       ExceptionSpecificationType NewEST = EST_Uninstantiated;
       if (EPI.ExceptionSpec.Type == EST_Unevaluated)
         NewEST = EST_Unevaluated;
 
       // Mark the function has having an uninstantiated exception specification.
       const FunctionProtoType *NewProto
         = New->getType()->getAs<FunctionProtoType>();
       assert(NewProto && "Template instantiation without function prototype?");
       EPI = NewProto->getExtProtoInfo();
       EPI.ExceptionSpec.Type = NewEST;
       EPI.ExceptionSpec.SourceDecl = New;
       EPI.ExceptionSpec.SourceTemplate = ExceptionSpecTemplate;
       New->setType(SemaRef.Context.getFunctionType(
           NewProto->getReturnType(), NewProto->getParamTypes(), EPI));
     } else {
       Sema::ContextRAII SwitchContext(SemaRef, New);
       SemaRef.SubstExceptionSpec(New, Proto, TemplateArgs);
     }
   }
 
   // Get the definition. Leaves the variable unchanged if undefined.
   const FunctionDecl *Definition = Tmpl;
   Tmpl->isDefined(Definition);
 
   SemaRef.InstantiateAttrs(TemplateArgs, Definition, New,
                            LateAttrs, StartingScope);
 
   return false;
 }
 
 /// Initializes common fields of an instantiated method
 /// declaration (New) from the corresponding fields of its template
 /// (Tmpl).
 ///
 /// \returns true if there was an error
 bool
 TemplateDeclInstantiator::InitMethodInstantiation(CXXMethodDecl *New,
                                                   CXXMethodDecl *Tmpl) {
   if (InitFunctionInstantiation(New, Tmpl))
     return true;
 
   if (isa<CXXDestructorDecl>(New) && SemaRef.getLangOpts().CPlusPlus11)
     SemaRef.AdjustDestructorExceptionSpec(cast<CXXDestructorDecl>(New));
 
   New->setAccess(Tmpl->getAccess());
   if (Tmpl->isVirtualAsWritten())
     New->setVirtualAsWritten(true);
 
   // FIXME: New needs a pointer to Tmpl
   return false;
 }
 
 bool TemplateDeclInstantiator::SubstDefaultedFunction(FunctionDecl *New,
                                                       FunctionDecl *Tmpl) {
   // Transfer across any unqualified lookups.
   if (auto *DFI = Tmpl->getDefaultedFunctionInfo()) {
     SmallVector<DeclAccessPair, 32> Lookups;
     Lookups.reserve(DFI->getUnqualifiedLookups().size());
     bool AnyChanged = false;
     for (DeclAccessPair DA : DFI->getUnqualifiedLookups()) {
       NamedDecl *D = SemaRef.FindInstantiatedDecl(New->getLocation(),
                                                   DA.getDecl(), TemplateArgs);
       if (!D)
         return true;
       AnyChanged |= (D != DA.getDecl());
       Lookups.push_back(DeclAccessPair::make(D, DA.getAccess()));
     }
 
     // It's unlikely that substitution will change any declarations. Don't
     // store an unnecessary copy in that case.
     New->setDefaultedFunctionInfo(
         AnyChanged ? FunctionDecl::DefaultedFunctionInfo::Create(
                          SemaRef.Context, Lookups)
                    : DFI);
   }
 
   SemaRef.SetDeclDefaulted(New, Tmpl->getLocation());
   return false;
 }
 
 /// Instantiate (or find existing instantiation of) a function template with a
 /// given set of template arguments.
 ///
 /// Usually this should not be used, and template argument deduction should be
 /// used in its place.
 FunctionDecl *
 Sema::InstantiateFunctionDeclaration(FunctionTemplateDecl *FTD,
                                      const TemplateArgumentList *Args,
                                      SourceLocation Loc) {
   FunctionDecl *FD = FTD->getTemplatedDecl();
 
   sema::TemplateDeductionInfo Info(Loc);
   InstantiatingTemplate Inst(
       *this, Loc, FTD, Args->asArray(),
       CodeSynthesisContext::ExplicitTemplateArgumentSubstitution, Info);
   if (Inst.isInvalid())
     return nullptr;
 
   ContextRAII SavedContext(*this, FD);
   MultiLevelTemplateArgumentList MArgs(FTD, Args->asArray(),
                                        /*Final=*/false);
 
   return cast_or_null<FunctionDecl>(SubstDecl(FD, FD->getParent(), MArgs));
 }
 
 /// Instantiate the definition of the given function from its
 /// template.
 ///
 /// \param PointOfInstantiation the point at which the instantiation was
 /// required. Note that this is not precisely a "point of instantiation"
 /// for the function, but it's close.
 ///
 /// \param Function the already-instantiated declaration of a
 /// function template specialization or member function of a class template
 /// specialization.
 ///
 /// \param Recursive if true, recursively instantiates any functions that
 /// are required by this instantiation.
 ///
 /// \param DefinitionRequired if true, then we are performing an explicit
 /// instantiation where the body of the function is required. Complain if
 /// there is no such body.
 void Sema::InstantiateFunctionDefinition(SourceLocation PointOfInstantiation,
                                          FunctionDecl *Function,
                                          bool Recursive,
                                          bool DefinitionRequired,
                                          bool AtEndOfTU) {
   if (Function->isInvalidDecl() || isa<CXXDeductionGuideDecl>(Function))
     return;
 
   // Never instantiate an explicit specialization except if it is a class scope
   // explicit specialization.
   TemplateSpecializationKind TSK =
       Function->getTemplateSpecializationKindForInstantiation();
   if (TSK == TSK_ExplicitSpecialization)
     return;
 
   // Never implicitly instantiate a builtin; we don't actually need a function
   // body.
   if (Function->getBuiltinID() && TSK == TSK_ImplicitInstantiation &&
       !DefinitionRequired)
     return;
 
   // Don't instantiate a definition if we already have one.
   const FunctionDecl *ExistingDefn = nullptr;
   if (Function->isDefined(ExistingDefn,
                           /*CheckForPendingFriendDefinition=*/true)) {
     if (ExistingDefn->isThisDeclarationADefinition())
       return;
 
     // If we're asked to instantiate a function whose body comes from an
     // instantiated friend declaration, attach the instantiated body to the
     // corresponding declaration of the function.
     assert(ExistingDefn->isThisDeclarationInstantiatedFromAFriendDefinition());
     Function = const_cast<FunctionDecl*>(ExistingDefn);
   }
 
   // Find the function body that we'll be substituting.
   const FunctionDecl *PatternDecl = Function->getTemplateInstantiationPattern();
   assert(PatternDecl && "instantiating a non-template");
 
   const FunctionDecl *PatternDef = PatternDecl->getDefinition();
   Stmt *Pattern = nullptr;
   if (PatternDef) {
     Pattern = PatternDef->getBody(PatternDef);
     PatternDecl = PatternDef;
     if (PatternDef->willHaveBody())
       PatternDef = nullptr;
   }
 
   // FIXME: We need to track the instantiation stack in order to know which
   // definitions should be visible within this instantiation.
   if (DiagnoseUninstantiableTemplate(PointOfInstantiation, Function,
                                 Function->getInstantiatedFromMemberFunction(),
                                      PatternDecl, PatternDef, TSK,
                                      /*Complain*/DefinitionRequired)) {
     if (DefinitionRequired)
       Function->setInvalidDecl();
     else if (TSK == TSK_ExplicitInstantiationDefinition ||
              (Function->isConstexpr() && !Recursive)) {
       // Try again at the end of the translation unit (at which point a
       // definition will be required).
       assert(!Recursive);
       Function->setInstantiationIsPending(true);
       PendingInstantiations.push_back(
         std::make_pair(Function, PointOfInstantiation));
     } else if (TSK == TSK_ImplicitInstantiation) {
       if (AtEndOfTU && !getDiagnostics().hasErrorOccurred() &&
           !getSourceManager().isInSystemHeader(PatternDecl->getBeginLoc())) {
         Diag(PointOfInstantiation, diag::warn_func_template_missing)
           << Function;
         Diag(PatternDecl->getLocation(), diag::note_forward_template_decl);
         if (getLangOpts().CPlusPlus11)
           Diag(PointOfInstantiation, diag::note_inst_declaration_hint)
               << Function;
       }
     }
 
     return;
   }
 
   // Postpone late parsed template instantiations.
   if (PatternDecl->isLateTemplateParsed() &&
       !LateTemplateParser) {
     Function->setInstantiationIsPending(true);
     LateParsedInstantiations.push_back(
         std::make_pair(Function, PointOfInstantiation));
     return;
   }
 
   llvm::TimeTraceScope TimeScope("InstantiateFunction", [&]() {
     std::string Name;
     llvm::raw_string_ostream OS(Name);
     Function->getNameForDiagnostic(OS, getPrintingPolicy(),
                                    /*Qualified=*/true);
     return Name;
   });
 
   // If we're performing recursive template instantiation, create our own
   // queue of pending implicit instantiations that we will instantiate later,
   // while we're still within our own instantiation context.
   // This has to happen before LateTemplateParser below is called, so that
   // it marks vtables used in late parsed templates as used.
   GlobalEagerInstantiationScope GlobalInstantiations(*this,
                                                      /*Enabled=*/Recursive);
   LocalEagerInstantiationScope LocalInstantiations(*this);
 
   // Call the LateTemplateParser callback if there is a need to late parse
   // a templated function definition.
   if (!Pattern && PatternDecl->isLateTemplateParsed() &&
       LateTemplateParser) {
     // FIXME: Optimize to allow individual templates to be deserialized.
     if (PatternDecl->isFromASTFile())
       ExternalSource->ReadLateParsedTemplates(LateParsedTemplateMap);
 
     auto LPTIter = LateParsedTemplateMap.find(PatternDecl);
     assert(LPTIter != LateParsedTemplateMap.end() &&
            "missing LateParsedTemplate");
     LateTemplateParser(OpaqueParser, *LPTIter->second);
     Pattern = PatternDecl->getBody(PatternDecl);
     updateAttrsForLateParsedTemplate(PatternDecl, Function);
   }
 
   // Note, we should never try to instantiate a deleted function template.
   assert((Pattern || PatternDecl->isDefaulted() ||
           PatternDecl->hasSkippedBody()) &&
          "unexpected kind of function template definition");
 
   // C++1y [temp.explicit]p10:
   //   Except for inline functions, declarations with types deduced from their
   //   initializer or return value, and class template specializations, other
   //   explicit instantiation declarations have the effect of suppressing the
   //   implicit instantiation of the entity to which they refer.
   if (TSK == TSK_ExplicitInstantiationDeclaration &&
       !PatternDecl->isInlined() &&
       !PatternDecl->getReturnType()->getContainedAutoType())
     return;
 
   if (PatternDecl->isInlined()) {
     // Function, and all later redeclarations of it (from imported modules,
     // for instance), are now implicitly inline.
     for (auto *D = Function->getMostRecentDecl(); /**/;
          D = D->getPreviousDecl()) {
       D->setImplicitlyInline();
       if (D == Function)
         break;
     }
   }
 
   InstantiatingTemplate Inst(*this, PointOfInstantiation, Function);
   if (Inst.isInvalid() || Inst.isAlreadyInstantiating())
     return;
   PrettyDeclStackTraceEntry CrashInfo(Context, Function, SourceLocation(),
                                       "instantiating function definition");
 
   // The instantiation is visible here, even if it was first declared in an
   // unimported module.
   Function->setVisibleDespiteOwningModule();
 
   // Copy the inner loc start from the pattern.
   Function->setInnerLocStart(PatternDecl->getInnerLocStart());
 
   EnterExpressionEvaluationContext EvalContext(
       *this, Sema::ExpressionEvaluationContext::PotentiallyEvaluated);
 
   // Introduce a new scope where local variable instantiations will be
   // recorded, unless we're actually a member function within a local
   // class, in which case we need to merge our results with the parent
   // scope (of the enclosing function). The exception is instantiating
   // a function template specialization, since the template to be
   // instantiated already has references to locals properly substituted.
   bool MergeWithParentScope = false;
   if (CXXRecordDecl *Rec = dyn_cast<CXXRecordDecl>(Function->getDeclContext()))
     MergeWithParentScope =
         Rec->isLocalClass() && !Function->isFunctionTemplateSpecialization();
 
   LocalInstantiationScope Scope(*this, MergeWithParentScope);
   auto RebuildTypeSourceInfoForDefaultSpecialMembers = [&]() {
     // Special members might get their TypeSourceInfo set up w.r.t the
     // PatternDecl context, in which case parameters could still be pointing
     // back to the original class, make sure arguments are bound to the
     // instantiated record instead.
     assert(PatternDecl->isDefaulted() &&
            "Special member needs to be defaulted");
     auto PatternSM = getDefaultedFunctionKind(PatternDecl).asSpecialMember();
     if (!(PatternSM == Sema::CXXCopyConstructor ||
           PatternSM == Sema::CXXCopyAssignment ||
           PatternSM == Sema::CXXMoveConstructor ||
           PatternSM == Sema::CXXMoveAssignment))
       return;
 
     auto *NewRec = dyn_cast<CXXRecordDecl>(Function->getDeclContext());
     const auto *PatternRec =
         dyn_cast<CXXRecordDecl>(PatternDecl->getDeclContext());
     if (!NewRec || !PatternRec)
       return;
     if (!PatternRec->isLambda())
       return;
 
     struct SpecialMemberTypeInfoRebuilder
         : TreeTransform<SpecialMemberTypeInfoRebuilder> {
       using Base = TreeTransform<SpecialMemberTypeInfoRebuilder>;
       const CXXRecordDecl *OldDecl;
       CXXRecordDecl *NewDecl;
 
       SpecialMemberTypeInfoRebuilder(Sema &SemaRef, const CXXRecordDecl *O,
                                      CXXRecordDecl *N)
           : TreeTransform(SemaRef), OldDecl(O), NewDecl(N) {}
 
       bool TransformExceptionSpec(SourceLocation Loc,
                                   FunctionProtoType::ExceptionSpecInfo &ESI,
                                   SmallVectorImpl<QualType> &Exceptions,
                                   bool &Changed) {
         return false;
       }
 
       QualType TransformRecordType(TypeLocBuilder &TLB, RecordTypeLoc TL) {
         const RecordType *T = TL.getTypePtr();
         RecordDecl *Record = cast_or_null<RecordDecl>(
             getDerived().TransformDecl(TL.getNameLoc(), T->getDecl()));
         if (Record != OldDecl)
           return Base::TransformRecordType(TLB, TL);
 
         QualType Result = getDerived().RebuildRecordType(NewDecl);
         if (Result.isNull())
           return QualType();
 
         RecordTypeLoc NewTL = TLB.push<RecordTypeLoc>(Result);
         NewTL.setNameLoc(TL.getNameLoc());
         return Result;
       }
     } IR{*this, PatternRec, NewRec};
 
     TypeSourceInfo *NewSI = IR.TransformType(Function->getTypeSourceInfo());
     Function->setType(NewSI->getType());
     Function->setTypeSourceInfo(NewSI);
 
     ParmVarDecl *Parm = Function->getParamDecl(0);
     TypeSourceInfo *NewParmSI = IR.TransformType(Parm->getTypeSourceInfo());
     Parm->setType(NewParmSI->getType());
     Parm->setTypeSourceInfo(NewParmSI);
   };
 
   if (PatternDecl->isDefaulted()) {
     RebuildTypeSourceInfoForDefaultSpecialMembers();
     SetDeclDefaulted(Function, PatternDecl->getLocation());
   } else {
     MultiLevelTemplateArgumentList TemplateArgs = getTemplateInstantiationArgs(
         Function, /*Final=*/false, nullptr, false, PatternDecl);
 
     // Substitute into the qualifier; we can get a substitution failure here
     // through evil use of alias templates.
     // FIXME: Is CurContext correct for this? Should we go to the (instantiation
     // of the) lexical context of the pattern?
     SubstQualifier(*this, PatternDecl, Function, TemplateArgs);
 
     ActOnStartOfFunctionDef(nullptr, Function);
 
     // Enter the scope of this instantiation. We don't use
     // PushDeclContext because we don't have a scope.
     Sema::ContextRAII savedContext(*this, Function);
 
     FPFeaturesStateRAII SavedFPFeatures(*this);
     CurFPFeatures = FPOptions(getLangOpts());
     FpPragmaStack.CurrentValue = FPOptionsOverride();
 
     if (addInstantiatedParametersToScope(Function, PatternDecl, Scope,
                                          TemplateArgs))
       return;
 
     StmtResult Body;
     if (PatternDecl->hasSkippedBody()) {
       ActOnSkippedFunctionBody(Function);
       Body = nullptr;
     } else {
       if (CXXConstructorDecl *Ctor = dyn_cast<CXXConstructorDecl>(Function)) {
         // If this is a constructor, instantiate the member initializers.
         InstantiateMemInitializers(Ctor, cast<CXXConstructorDecl>(PatternDecl),
                                    TemplateArgs);
 
         // If this is an MS ABI dllexport default constructor, instantiate any
         // default arguments.
         if (Context.getTargetInfo().getCXXABI().isMicrosoft() &&
             Ctor->isDefaultConstructor()) {
           InstantiateDefaultCtorDefaultArgs(Ctor);
         }
       }
 
       // Instantiate the function body.
       Body = SubstStmt(Pattern, TemplateArgs);
 
       if (Body.isInvalid())
         Function->setInvalidDecl();
     }
     // FIXME: finishing the function body while in an expression evaluation
     // context seems wrong. Investigate more.
     ActOnFinishFunctionBody(Function, Body.get(), /*IsInstantiation=*/true);
 
     PerformDependentDiagnostics(PatternDecl, TemplateArgs);
 
     if (auto *Listener = getASTMutationListener())
       Listener->FunctionDefinitionInstantiated(Function);
 
     savedContext.pop();
   }
 
   DeclGroupRef DG(Function);
   Consumer.HandleTopLevelDecl(DG);
 
   // This class may have local implicit instantiations that need to be
   // instantiation within this scope.
   LocalInstantiations.perform();
   Scope.Exit();
   GlobalInstantiations.perform();
 }
 
 VarTemplateSpecializationDecl *Sema::BuildVarTemplateInstantiation(
     VarTemplateDecl *VarTemplate, VarDecl *FromVar,
     const TemplateArgumentList &TemplateArgList,
     const TemplateArgumentListInfo &TemplateArgsInfo,
     SmallVectorImpl<TemplateArgument> &Converted,
     SourceLocation PointOfInstantiation, LateInstantiatedAttrVec *LateAttrs,
     LocalInstantiationScope *StartingScope) {
   if (FromVar->isInvalidDecl())
     return nullptr;
 
   InstantiatingTemplate Inst(*this, PointOfInstantiation, FromVar);
   if (Inst.isInvalid())
     return nullptr;
 
   // Instantiate the first declaration of the variable template: for a partial
   // specialization of a static data member template, the first declaration may
   // or may not be the declaration in the class; if it's in the class, we want
   // to instantiate a member in the class (a declaration), and if it's outside,
   // we want to instantiate a definition.
   //
   // If we're instantiating an explicitly-specialized member template or member
   // partial specialization, don't do this. The member specialization completely
   // replaces the original declaration in this case.
   bool IsMemberSpec = false;
   MultiLevelTemplateArgumentList MultiLevelList;
   if (auto *PartialSpec =
           dyn_cast<VarTemplatePartialSpecializationDecl>(FromVar)) {
     IsMemberSpec = PartialSpec->isMemberSpecialization();
     MultiLevelList.addOuterTemplateArguments(
         PartialSpec, TemplateArgList.asArray(), /*Final=*/false);
   } else {
     assert(VarTemplate == FromVar->getDescribedVarTemplate());
     IsMemberSpec = VarTemplate->isMemberSpecialization();
     MultiLevelList.addOuterTemplateArguments(
         VarTemplate, TemplateArgList.asArray(), /*Final=*/false);
   }
   if (!IsMemberSpec)
     FromVar = FromVar->getFirstDecl();
 
   TemplateDeclInstantiator Instantiator(*this, FromVar->getDeclContext(),
                                         MultiLevelList);
 
   // TODO: Set LateAttrs and StartingScope ...
 
   return cast_or_null<VarTemplateSpecializationDecl>(
       Instantiator.VisitVarTemplateSpecializationDecl(
           VarTemplate, FromVar, TemplateArgsInfo, Converted));
 }
 
 /// Instantiates a variable template specialization by completing it
 /// with appropriate type information and initializer.
 VarTemplateSpecializationDecl *Sema::CompleteVarTemplateSpecializationDecl(
     VarTemplateSpecializationDecl *VarSpec, VarDecl *PatternDecl,
     const MultiLevelTemplateArgumentList &TemplateArgs) {
   assert(PatternDecl->isThisDeclarationADefinition() &&
          "don't have a definition to instantiate from");
 
   // Do substitution on the type of the declaration
   TypeSourceInfo *DI =
       SubstType(PatternDecl->getTypeSourceInfo(), TemplateArgs,
                 PatternDecl->getTypeSpecStartLoc(), PatternDecl->getDeclName());
   if (!DI)
     return nullptr;
 
   // Update the type of this variable template specialization.
   VarSpec->setType(DI->getType());
 
   // Convert the declaration into a definition now.
   VarSpec->setCompleteDefinition();
 
   // Instantiate the initializer.
   InstantiateVariableInitializer(VarSpec, PatternDecl, TemplateArgs);
 
   if (getLangOpts().OpenCL)
     deduceOpenCLAddressSpace(VarSpec);
 
   return VarSpec;
 }
 
 /// BuildVariableInstantiation - Used after a new variable has been created.
 /// Sets basic variable data and decides whether to postpone the
 /// variable instantiation.
 void Sema::BuildVariableInstantiation(
     VarDecl *NewVar, VarDecl *OldVar,
     const MultiLevelTemplateArgumentList &TemplateArgs,
     LateInstantiatedAttrVec *LateAttrs, DeclContext *Owner,
     LocalInstantiationScope *StartingScope,
     bool InstantiatingVarTemplate,
     VarTemplateSpecializationDecl *PrevDeclForVarTemplateSpecialization) {
   // Instantiating a partial specialization to produce a partial
   // specialization.
   bool InstantiatingVarTemplatePartialSpec =
       isa<VarTemplatePartialSpecializationDecl>(OldVar) &&
       isa<VarTemplatePartialSpecializationDecl>(NewVar);
   // Instantiating from a variable template (or partial specialization) to
   // produce a variable template specialization.
   bool InstantiatingSpecFromTemplate =
       isa<VarTemplateSpecializationDecl>(NewVar) &&
       (OldVar->getDescribedVarTemplate() ||
        isa<VarTemplatePartialSpecializationDecl>(OldVar));
 
   // If we are instantiating a local extern declaration, the
   // instantiation belongs lexically to the containing function.
   // If we are instantiating a static data member defined
   // out-of-line, the instantiation will have the same lexical
   // context (which will be a namespace scope) as the template.
   if (OldVar->isLocalExternDecl()) {
     NewVar->setLocalExternDecl();
     NewVar->setLexicalDeclContext(Owner);
   } else if (OldVar->isOutOfLine())
     NewVar->setLexicalDeclContext(OldVar->getLexicalDeclContext());
   NewVar->setTSCSpec(OldVar->getTSCSpec());
   NewVar->setInitStyle(OldVar->getInitStyle());
   NewVar->setCXXForRangeDecl(OldVar->isCXXForRangeDecl());
   NewVar->setObjCForDecl(OldVar->isObjCForDecl());
   NewVar->setConstexpr(OldVar->isConstexpr());
   NewVar->setInitCapture(OldVar->isInitCapture());
   NewVar->setPreviousDeclInSameBlockScope(
       OldVar->isPreviousDeclInSameBlockScope());
   NewVar->setAccess(OldVar->getAccess());
 
   if (!OldVar->isStaticDataMember()) {
     if (OldVar->isUsed(false))
       NewVar->setIsUsed();
     NewVar->setReferenced(OldVar->isReferenced());
   }
 
   InstantiateAttrs(TemplateArgs, OldVar, NewVar, LateAttrs, StartingScope);
 
   LookupResult Previous(
       *this, NewVar->getDeclName(), NewVar->getLocation(),
       NewVar->isLocalExternDecl() ? Sema::LookupRedeclarationWithLinkage
                                   : Sema::LookupOrdinaryName,
       NewVar->isLocalExternDecl() ? Sema::ForExternalRedeclaration
                                   : forRedeclarationInCurContext());
 
   if (NewVar->isLocalExternDecl() && OldVar->getPreviousDecl() &&
       (!OldVar->getPreviousDecl()->getDeclContext()->isDependentContext() ||
        OldVar->getPreviousDecl()->getDeclContext()==OldVar->getDeclContext())) {
     // We have a previous declaration. Use that one, so we merge with the
     // right type.
     if (NamedDecl *NewPrev = FindInstantiatedDecl(
             NewVar->getLocation(), OldVar->getPreviousDecl(), TemplateArgs))
       Previous.addDecl(NewPrev);
   } else if (!isa<VarTemplateSpecializationDecl>(NewVar) &&
              OldVar->hasLinkage()) {
     LookupQualifiedName(Previous, NewVar->getDeclContext(), false);
   } else if (PrevDeclForVarTemplateSpecialization) {
     Previous.addDecl(PrevDeclForVarTemplateSpecialization);
   }
   CheckVariableDeclaration(NewVar, Previous);
 
   if (!InstantiatingVarTemplate) {
     NewVar->getLexicalDeclContext()->addHiddenDecl(NewVar);
     if (!NewVar->isLocalExternDecl() || !NewVar->getPreviousDecl())
       NewVar->getDeclContext()->makeDeclVisibleInContext(NewVar);
   }
 
   if (!OldVar->isOutOfLine()) {
     if (NewVar->getDeclContext()->isFunctionOrMethod())
       CurrentInstantiationScope->InstantiatedLocal(OldVar, NewVar);
   }
 
   // Link instantiations of static data members back to the template from
   // which they were instantiated.
   //
   // Don't do this when instantiating a template (we link the template itself
   // back in that case) nor when instantiating a static data member template
   // (that's not a member specialization).
   if (NewVar->isStaticDataMember() && !InstantiatingVarTemplate &&
       !InstantiatingSpecFromTemplate)
     NewVar->setInstantiationOfStaticDataMember(OldVar,
                                                TSK_ImplicitInstantiation);
 
   // If the pattern is an (in-class) explicit specialization, then the result
   // is also an explicit specialization.
   if (VarTemplateSpecializationDecl *OldVTSD =
           dyn_cast<VarTemplateSpecializationDecl>(OldVar)) {
     if (OldVTSD->getSpecializationKind() == TSK_ExplicitSpecialization &&
         !isa<VarTemplatePartialSpecializationDecl>(OldVTSD))
       cast<VarTemplateSpecializationDecl>(NewVar)->setSpecializationKind(
           TSK_ExplicitSpecialization);
   }
 
   // Forward the mangling number from the template to the instantiated decl.
   Context.setManglingNumber(NewVar, Context.getManglingNumber(OldVar));
   Context.setStaticLocalNumber(NewVar, Context.getStaticLocalNumber(OldVar));
 
   // Figure out whether to eagerly instantiate the initializer.
   if (InstantiatingVarTemplate || InstantiatingVarTemplatePartialSpec) {
     // We're producing a template. Don't instantiate the initializer yet.
   } else if (NewVar->getType()->isUndeducedType()) {
     // We need the type to complete the declaration of the variable.
     InstantiateVariableInitializer(NewVar, OldVar, TemplateArgs);
   } else if (InstantiatingSpecFromTemplate ||
              (OldVar->isInline() && OldVar->isThisDeclarationADefinition() &&
               !NewVar->isThisDeclarationADefinition())) {
     // Delay instantiation of the initializer for variable template
     // specializations or inline static data members until a definition of the
     // variable is needed.
   } else {
     InstantiateVariableInitializer(NewVar, OldVar, TemplateArgs);
   }
 
   // Diagnose unused local variables with dependent types, where the diagnostic
   // will have been deferred.
   if (!NewVar->isInvalidDecl() &&
       NewVar->getDeclContext()->isFunctionOrMethod() &&
       OldVar->getType()->isDependentType())
     DiagnoseUnusedDecl(NewVar);
 }
 
 /// Instantiate the initializer of a variable.
 void Sema::InstantiateVariableInitializer(
     VarDecl *Var, VarDecl *OldVar,
     const MultiLevelTemplateArgumentList &TemplateArgs) {
   if (ASTMutationListener *L = getASTContext().getASTMutationListener())
     L->VariableDefinitionInstantiated(Var);
 
   // We propagate the 'inline' flag with the initializer, because it
   // would otherwise imply that the variable is a definition for a
   // non-static data member.
   if (OldVar->isInlineSpecified())
     Var->setInlineSpecified();
   else if (OldVar->isInline())
     Var->setImplicitlyInline();
 
   if (OldVar->getInit()) {
     EnterExpressionEvaluationContext Evaluated(
         *this, Sema::ExpressionEvaluationContext::PotentiallyEvaluated, Var);
 
     // Instantiate the initializer.
     ExprResult Init;
 
     {
       ContextRAII SwitchContext(*this, Var->getDeclContext());
       Init = SubstInitializer(OldVar->getInit(), TemplateArgs,
                               OldVar->getInitStyle() == VarDecl::CallInit);
     }
 
     if (!Init.isInvalid()) {
       Expr *InitExpr = Init.get();
 
       if (Var->hasAttr<DLLImportAttr>() &&
           (!InitExpr ||
            !InitExpr->isConstantInitializer(getASTContext(), false))) {
         // Do not dynamically initialize dllimport variables.
       } else if (InitExpr) {
         bool DirectInit = OldVar->isDirectInit();
         AddInitializerToDecl(Var, InitExpr, DirectInit);
       } else
         ActOnUninitializedDecl(Var);
     } else {
       // FIXME: Not too happy about invalidating the declaration
       // because of a bogus initializer.
       Var->setInvalidDecl();
     }
   } else {
     // `inline` variables are a definition and declaration all in one; we won't
     // pick up an initializer from anywhere else.
     if (Var->isStaticDataMember() && !Var->isInline()) {
       if (!Var->isOutOfLine())
         return;
 
       // If the declaration inside the class had an initializer, don't add
       // another one to the out-of-line definition.
       if (OldVar->getFirstDecl()->hasInit())
         return;
     }
 
     // We'll add an initializer to a for-range declaration later.
     if (Var->isCXXForRangeDecl() || Var->isObjCForDecl())
       return;
 
     ActOnUninitializedDecl(Var);
   }
 
   if (getLangOpts().CUDA)
     checkAllowedCUDAInitializer(Var);
 }
 
 /// Instantiate the definition of the given variable from its
 /// template.
 ///
 /// \param PointOfInstantiation the point at which the instantiation was
 /// required. Note that this is not precisely a "point of instantiation"
 /// for the variable, but it's close.
 ///
 /// \param Var the already-instantiated declaration of a templated variable.
 ///
 /// \param Recursive if true, recursively instantiates any functions that
 /// are required by this instantiation.
 ///
 /// \param DefinitionRequired if true, then we are performing an explicit
 /// instantiation where a definition of the variable is required. Complain
 /// if there is no such definition.
 void Sema::InstantiateVariableDefinition(SourceLocation PointOfInstantiation,
                                          VarDecl *Var, bool Recursive,
                                       bool DefinitionRequired, bool AtEndOfTU) {
   if (Var->isInvalidDecl())
     return;
 
   // Never instantiate an explicitly-specialized entity.
   TemplateSpecializationKind TSK =
       Var->getTemplateSpecializationKindForInstantiation();
   if (TSK == TSK_ExplicitSpecialization)
     return;
 
   // Find the pattern and the arguments to substitute into it.
   VarDecl *PatternDecl = Var->getTemplateInstantiationPattern();
   assert(PatternDecl && "no pattern for templated variable");
   MultiLevelTemplateArgumentList TemplateArgs =
       getTemplateInstantiationArgs(Var);
 
   VarTemplateSpecializationDecl *VarSpec =
       dyn_cast<VarTemplateSpecializationDecl>(Var);
   if (VarSpec) {
     // If this is a static data member template, there might be an
     // uninstantiated initializer on the declaration. If so, instantiate
     // it now.
     //
     // FIXME: This largely duplicates what we would do below. The difference
     // is that along this path we may instantiate an initializer from an
     // in-class declaration of the template and instantiate the definition
     // from a separate out-of-class definition.
     if (PatternDecl->isStaticDataMember() &&
         (PatternDecl = PatternDecl->getFirstDecl())->hasInit() &&
         !Var->hasInit()) {
       // FIXME: Factor out the duplicated instantiation context setup/tear down
       // code here.
       InstantiatingTemplate Inst(*this, PointOfInstantiation, Var);
       if (Inst.isInvalid() || Inst.isAlreadyInstantiating())
         return;
       PrettyDeclStackTraceEntry CrashInfo(Context, Var, SourceLocation(),
                                           "instantiating variable initializer");
 
       // The instantiation is visible here, even if it was first declared in an
       // unimported module.
       Var->setVisibleDespiteOwningModule();
 
       // If we're performing recursive template instantiation, create our own
       // queue of pending implicit instantiations that we will instantiate
       // later, while we're still within our own instantiation context.
       GlobalEagerInstantiationScope GlobalInstantiations(*this,
                                                          /*Enabled=*/Recursive);
       LocalInstantiationScope Local(*this);
       LocalEagerInstantiationScope LocalInstantiations(*this);
 
       // Enter the scope of this instantiation. We don't use
       // PushDeclContext because we don't have a scope.
       ContextRAII PreviousContext(*this, Var->getDeclContext());
       InstantiateVariableInitializer(Var, PatternDecl, TemplateArgs);
       PreviousContext.pop();
 
       // This variable may have local implicit instantiations that need to be
       // instantiated within this scope.
       LocalInstantiations.perform();
       Local.Exit();
       GlobalInstantiations.perform();
     }
   } else {
     assert(Var->isStaticDataMember() && PatternDecl->isStaticDataMember() &&
            "not a static data member?");
   }
 
   VarDecl *Def = PatternDecl->getDefinition(getASTContext());
 
   // If we don't have a definition of the variable template, we won't perform
   // any instantiation. Rather, we rely on the user to instantiate this
   // definition (or provide a specialization for it) in another translation
   // unit.
   if (!Def && !DefinitionRequired) {
     if (TSK == TSK_ExplicitInstantiationDefinition) {
       PendingInstantiations.push_back(
         std::make_pair(Var, PointOfInstantiation));
     } else if (TSK == TSK_ImplicitInstantiation) {
       // Warn about missing definition at the end of translation unit.
       if (AtEndOfTU && !getDiagnostics().hasErrorOccurred() &&
           !getSourceManager().isInSystemHeader(PatternDecl->getBeginLoc())) {
         Diag(PointOfInstantiation, diag::warn_var_template_missing)
           << Var;
         Diag(PatternDecl->getLocation(), diag::note_forward_template_decl);
         if (getLangOpts().CPlusPlus11)
           Diag(PointOfInstantiation, diag::note_inst_declaration_hint) << Var;
       }
       return;
     }
   }
 
   // FIXME: We need to track the instantiation stack in order to know which
   // definitions should be visible within this instantiation.
   // FIXME: Produce diagnostics when Var->getInstantiatedFromStaticDataMember().
   if (DiagnoseUninstantiableTemplate(PointOfInstantiation, Var,
                                      /*InstantiatedFromMember*/false,
                                      PatternDecl, Def, TSK,
                                      /*Complain*/DefinitionRequired))
     return;
 
   // C++11 [temp.explicit]p10:
   //   Except for inline functions, const variables of literal types, variables
   //   of reference types, [...] explicit instantiation declarations
   //   have the effect of suppressing the implicit instantiation of the entity
   //   to which they refer.
   //
   // FIXME: That's not exactly the same as "might be usable in constant
   // expressions", which only allows constexpr variables and const integral
   // types, not arbitrary const literal types.
   if (TSK == TSK_ExplicitInstantiationDeclaration &&
       !Var->mightBeUsableInConstantExpressions(getASTContext()))
     return;
 
   // Make sure to pass the instantiated variable to the consumer at the end.
   struct PassToConsumerRAII {
     ASTConsumer &Consumer;
     VarDecl *Var;
 
     PassToConsumerRAII(ASTConsumer &Consumer, VarDecl *Var)
       : Consumer(Consumer), Var(Var) { }
 
     ~PassToConsumerRAII() {
       Consumer.HandleCXXStaticMemberVarInstantiation(Var);
     }
   } PassToConsumerRAII(Consumer, Var);
 
   // If we already have a definition, we're done.
   if (VarDecl *Def = Var->getDefinition()) {
     // We may be explicitly instantiating something we've already implicitly
     // instantiated.
     Def->setTemplateSpecializationKind(Var->getTemplateSpecializationKind(),
                                        PointOfInstantiation);
     return;
   }
 
   InstantiatingTemplate Inst(*this, PointOfInstantiation, Var);
   if (Inst.isInvalid() || Inst.isAlreadyInstantiating())
     return;
   PrettyDeclStackTraceEntry CrashInfo(Context, Var, SourceLocation(),
                                       "instantiating variable definition");
 
   // If we're performing recursive template instantiation, create our own
   // queue of pending implicit instantiations that we will instantiate later,
   // while we're still within our own instantiation context.
   GlobalEagerInstantiationScope GlobalInstantiations(*this,
                                                      /*Enabled=*/Recursive);
 
   // Enter the scope of this instantiation. We don't use
   // PushDeclContext because we don't have a scope.
   ContextRAII PreviousContext(*this, Var->getDeclContext());
   LocalInstantiationScope Local(*this);
 
   LocalEagerInstantiationScope LocalInstantiations(*this);
 
   VarDecl *OldVar = Var;
   if (Def->isStaticDataMember() && !Def->isOutOfLine()) {
     // We're instantiating an inline static data member whose definition was
     // provided inside the class.
     InstantiateVariableInitializer(Var, Def, TemplateArgs);
   } else if (!VarSpec) {
     Var = cast_or_null<VarDecl>(SubstDecl(Def, Var->getDeclContext(),
                                           TemplateArgs));
   } else if (Var->isStaticDataMember() &&
              Var->getLexicalDeclContext()->isRecord()) {
     // We need to instantiate the definition of a static data member template,
     // and all we have is the in-class declaration of it. Instantiate a separate
     // declaration of the definition.
     TemplateDeclInstantiator Instantiator(*this, Var->getDeclContext(),
                                           TemplateArgs);
 
     TemplateArgumentListInfo TemplateArgInfo;
     if (const ASTTemplateArgumentListInfo *ArgInfo =
             VarSpec->getTemplateArgsInfo()) {
       TemplateArgInfo.setLAngleLoc(ArgInfo->getLAngleLoc());
       TemplateArgInfo.setRAngleLoc(ArgInfo->getRAngleLoc());
       for (const TemplateArgumentLoc &Arg : ArgInfo->arguments())
         TemplateArgInfo.addArgument(Arg);
     }
 
     Var = cast_or_null<VarDecl>(Instantiator.VisitVarTemplateSpecializationDecl(
         VarSpec->getSpecializedTemplate(), Def, TemplateArgInfo,
         VarSpec->getTemplateArgs().asArray(), VarSpec));
     if (Var) {
       llvm::PointerUnion<VarTemplateDecl *,
                          VarTemplatePartialSpecializationDecl *> PatternPtr =
           VarSpec->getSpecializedTemplateOrPartial();
       if (VarTemplatePartialSpecializationDecl *Partial =
           PatternPtr.dyn_cast<VarTemplatePartialSpecializationDecl *>())
         cast<VarTemplateSpecializationDecl>(Var)->setInstantiationOf(
             Partial, &VarSpec->getTemplateInstantiationArgs());
 
       // Attach the initializer.
       InstantiateVariableInitializer(Var, Def, TemplateArgs);
     }
   } else
     // Complete the existing variable's definition with an appropriately
     // substituted type and initializer.
     Var = CompleteVarTemplateSpecializationDecl(VarSpec, Def, TemplateArgs);
 
   PreviousContext.pop();
 
   if (Var) {
     PassToConsumerRAII.Var = Var;
     Var->setTemplateSpecializationKind(OldVar->getTemplateSpecializationKind(),
                                        OldVar->getPointOfInstantiation());
   }
 
   // This variable may have local implicit instantiations that need to be
   // instantiated within this scope.
   LocalInstantiations.perform();
   Local.Exit();
   GlobalInstantiations.perform();
 }
 
 void
 Sema::InstantiateMemInitializers(CXXConstructorDecl *New,
                                  const CXXConstructorDecl *Tmpl,
                            const MultiLevelTemplateArgumentList &TemplateArgs) {
 
   SmallVector<CXXCtorInitializer*, 4> NewInits;
   bool AnyErrors = Tmpl->isInvalidDecl();
 
   // Instantiate all the initializers.
   for (const auto *Init : Tmpl->inits()) {
     // Only instantiate written initializers, let Sema re-construct implicit
     // ones.
     if (!Init->isWritten())
       continue;
 
     SourceLocation EllipsisLoc;
 
     if (Init->isPackExpansion()) {
       // This is a pack expansion. We should expand it now.
       TypeLoc BaseTL = Init->getTypeSourceInfo()->getTypeLoc();
       SmallVector<UnexpandedParameterPack, 4> Unexpanded;
       collectUnexpandedParameterPacks(BaseTL, Unexpanded);
       collectUnexpandedParameterPacks(Init->getInit(), Unexpanded);
       bool ShouldExpand = false;
       bool RetainExpansion = false;
       std::optional<unsigned> NumExpansions;
       if (CheckParameterPacksForExpansion(Init->getEllipsisLoc(),
                                           BaseTL.getSourceRange(),
                                           Unexpanded,
                                           TemplateArgs, ShouldExpand,
                                           RetainExpansion,
                                           NumExpansions)) {
         AnyErrors = true;
         New->setInvalidDecl();
         continue;
       }
       assert(ShouldExpand && "Partial instantiation of base initializer?");
 
       // Loop over all of the arguments in the argument pack(s),
       for (unsigned I = 0; I != *NumExpansions; ++I) {
         Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(*this, I);
 
         // Instantiate the initializer.
         ExprResult TempInit = SubstInitializer(Init->getInit(), TemplateArgs,
                                                /*CXXDirectInit=*/true);
         if (TempInit.isInvalid()) {
           AnyErrors = true;
           break;
         }
 
         // Instantiate the base type.
         TypeSourceInfo *BaseTInfo = SubstType(Init->getTypeSourceInfo(),
                                               TemplateArgs,
                                               Init->getSourceLocation(),
                                               New->getDeclName());
         if (!BaseTInfo) {
           AnyErrors = true;
           break;
         }
 
         // Build the initializer.
         MemInitResult NewInit = BuildBaseInitializer(BaseTInfo->getType(),
                                                      BaseTInfo, TempInit.get(),
                                                      New->getParent(),
                                                      SourceLocation());
         if (NewInit.isInvalid()) {
           AnyErrors = true;
           break;
         }
 
         NewInits.push_back(NewInit.get());
       }
 
       continue;
     }
 
     // Instantiate the initializer.
     ExprResult TempInit = SubstInitializer(Init->getInit(), TemplateArgs,
                                            /*CXXDirectInit=*/true);
     if (TempInit.isInvalid()) {
       AnyErrors = true;
       continue;
     }
 
     MemInitResult NewInit;
     if (Init->isDelegatingInitializer() || Init->isBaseInitializer()) {
       TypeSourceInfo *TInfo = SubstType(Init->getTypeSourceInfo(),
                                         TemplateArgs,
                                         Init->getSourceLocation(),
                                         New->getDeclName());
       if (!TInfo) {
         AnyErrors = true;
         New->setInvalidDecl();
         continue;
       }
 
       if (Init->isBaseInitializer())
         NewInit = BuildBaseInitializer(TInfo->getType(), TInfo, TempInit.get(),
                                        New->getParent(), EllipsisLoc);
       else
         NewInit = BuildDelegatingInitializer(TInfo, TempInit.get(),
                                   cast<CXXRecordDecl>(CurContext->getParent()));
     } else if (Init->isMemberInitializer()) {
       FieldDecl *Member = cast_or_null<FieldDecl>(FindInstantiatedDecl(
                                                      Init->getMemberLocation(),
                                                      Init->getMember(),
                                                      TemplateArgs));
       if (!Member) {
         AnyErrors = true;
         New->setInvalidDecl();
         continue;
       }
 
       NewInit = BuildMemberInitializer(Member, TempInit.get(),
                                        Init->getSourceLocation());
     } else if (Init->isIndirectMemberInitializer()) {
       IndirectFieldDecl *IndirectMember =
          cast_or_null<IndirectFieldDecl>(FindInstantiatedDecl(
                                  Init->getMemberLocation(),
                                  Init->getIndirectMember(), TemplateArgs));
 
       if (!IndirectMember) {
         AnyErrors = true;
         New->setInvalidDecl();
         continue;
       }
 
       NewInit = BuildMemberInitializer(IndirectMember, TempInit.get(),
                                        Init->getSourceLocation());
     }
 
     if (NewInit.isInvalid()) {
       AnyErrors = true;
       New->setInvalidDecl();
     } else {
       NewInits.push_back(NewInit.get());
     }
   }
 
   // Assign all the initializers to the new constructor.
   ActOnMemInitializers(New,
                        /*FIXME: ColonLoc */
                        SourceLocation(),
                        NewInits,
                        AnyErrors);
 }
 
 // TODO: this could be templated if the various decl types used the
 // same method name.
 static bool isInstantiationOf(ClassTemplateDecl *Pattern,
                               ClassTemplateDecl *Instance) {
   Pattern = Pattern->getCanonicalDecl();
 
   do {
     Instance = Instance->getCanonicalDecl();
     if (Pattern == Instance) return true;
     Instance = Instance->getInstantiatedFromMemberTemplate();
   } while (Instance);
 
   return false;
 }
 
 static bool isInstantiationOf(FunctionTemplateDecl *Pattern,
                               FunctionTemplateDecl *Instance) {
   Pattern = Pattern->getCanonicalDecl();
 
   do {
     Instance = Instance->getCanonicalDecl();
     if (Pattern == Instance) return true;
     Instance = Instance->getInstantiatedFromMemberTemplate();
   } while (Instance);
 
   return false;
 }
 
 static bool
 isInstantiationOf(ClassTemplatePartialSpecializationDecl *Pattern,
                   ClassTemplatePartialSpecializationDecl *Instance) {
   Pattern
     = cast<ClassTemplatePartialSpecializationDecl>(Pattern->getCanonicalDecl());
   do {
     Instance = cast<ClassTemplatePartialSpecializationDecl>(
                                                 Instance->getCanonicalDecl());
     if (Pattern == Instance)
       return true;
     Instance = Instance->getInstantiatedFromMember();
   } while (Instance);
 
   return false;
 }
 
 static bool isInstantiationOf(CXXRecordDecl *Pattern,
                               CXXRecordDecl *Instance) {
   Pattern = Pattern->getCanonicalDecl();
 
   do {
     Instance = Instance->getCanonicalDecl();
     if (Pattern == Instance) return true;
     Instance = Instance->getInstantiatedFromMemberClass();
   } while (Instance);
 
   return false;
 }
 
 static bool isInstantiationOf(FunctionDecl *Pattern,
                               FunctionDecl *Instance) {
   Pattern = Pattern->getCanonicalDecl();
 
   do {
     Instance = Instance->getCanonicalDecl();
     if (Pattern == Instance) return true;
     Instance = Instance->getInstantiatedFromMemberFunction();
   } while (Instance);
 
   return false;
 }
 
 static bool isInstantiationOf(EnumDecl *Pattern,
                               EnumDecl *Instance) {
   Pattern = Pattern->getCanonicalDecl();
 
   do {
     Instance = Instance->getCanonicalDecl();
     if (Pattern == Instance) return true;
     Instance = Instance->getInstantiatedFromMemberEnum();
   } while (Instance);
 
   return false;
 }
 
 static bool isInstantiationOf(UsingShadowDecl *Pattern,
                               UsingShadowDecl *Instance,
                               ASTContext &C) {
   return declaresSameEntity(C.getInstantiatedFromUsingShadowDecl(Instance),
                             Pattern);
 }
 
 static bool isInstantiationOf(UsingDecl *Pattern, UsingDecl *Instance,
                               ASTContext &C) {
   return declaresSameEntity(C.getInstantiatedFromUsingDecl(Instance), Pattern);
 }
 
 template<typename T>
 static bool isInstantiationOfUnresolvedUsingDecl(T *Pattern, Decl *Other,
                                                  ASTContext &Ctx) {
   // An unresolved using declaration can instantiate to an unresolved using
   // declaration, or to a using declaration or a using declaration pack.
   //
   // Multiple declarations can claim to be instantiated from an unresolved
   // using declaration if it's a pack expansion. We want the UsingPackDecl
   // in that case, not the individual UsingDecls within the pack.
   bool OtherIsPackExpansion;
   NamedDecl *OtherFrom;
   if (auto *OtherUUD = dyn_cast<T>(Other)) {
     OtherIsPackExpansion = OtherUUD->isPackExpansion();
     OtherFrom = Ctx.getInstantiatedFromUsingDecl(OtherUUD);
   } else if (auto *OtherUPD = dyn_cast<UsingPackDecl>(Other)) {
     OtherIsPackExpansion = true;
     OtherFrom = OtherUPD->getInstantiatedFromUsingDecl();
   } else if (auto *OtherUD = dyn_cast<UsingDecl>(Other)) {
     OtherIsPackExpansion = false;
     OtherFrom = Ctx.getInstantiatedFromUsingDecl(OtherUD);
   } else {
     return false;
   }
   return Pattern->isPackExpansion() == OtherIsPackExpansion &&
          declaresSameEntity(OtherFrom, Pattern);
 }
 
 static bool isInstantiationOfStaticDataMember(VarDecl *Pattern,
                                               VarDecl *Instance) {
   assert(Instance->isStaticDataMember());
 
   Pattern = Pattern->getCanonicalDecl();
 
   do {
     Instance = Instance->getCanonicalDecl();
     if (Pattern == Instance) return true;
     Instance = Instance->getInstantiatedFromStaticDataMember();
   } while (Instance);
 
   return false;
 }
 
 // Other is the prospective instantiation
 // D is the prospective pattern
 static bool isInstantiationOf(ASTContext &Ctx, NamedDecl *D, Decl *Other) {
   if (auto *UUD = dyn_cast<UnresolvedUsingTypenameDecl>(D))
     return isInstantiationOfUnresolvedUsingDecl(UUD, Other, Ctx);
 
   if (auto *UUD = dyn_cast<UnresolvedUsingValueDecl>(D))
     return isInstantiationOfUnresolvedUsingDecl(UUD, Other, Ctx);
 
   if (D->getKind() != Other->getKind())
     return false;
 
   if (auto *Record = dyn_cast<CXXRecordDecl>(Other))
     return isInstantiationOf(cast<CXXRecordDecl>(D), Record);
 
   if (auto *Function = dyn_cast<FunctionDecl>(Other))
     return isInstantiationOf(cast<FunctionDecl>(D), Function);
 
   if (auto *Enum = dyn_cast<EnumDecl>(Other))
     return isInstantiationOf(cast<EnumDecl>(D), Enum);
 
   if (auto *Var = dyn_cast<VarDecl>(Other))
     if (Var->isStaticDataMember())
       return isInstantiationOfStaticDataMember(cast<VarDecl>(D), Var);
 
   if (auto *Temp = dyn_cast<ClassTemplateDecl>(Other))
     return isInstantiationOf(cast<ClassTemplateDecl>(D), Temp);
 
   if (auto *Temp = dyn_cast<FunctionTemplateDecl>(Other))
     return isInstantiationOf(cast<FunctionTemplateDecl>(D), Temp);
 
   if (auto *PartialSpec =
           dyn_cast<ClassTemplatePartialSpecializationDecl>(Other))
     return isInstantiationOf(cast<ClassTemplatePartialSpecializationDecl>(D),
                              PartialSpec);
 
   if (auto *Field = dyn_cast<FieldDecl>(Other)) {
     if (!Field->getDeclName()) {
       // This is an unnamed field.
       return declaresSameEntity(Ctx.getInstantiatedFromUnnamedFieldDecl(Field),
                                 cast<FieldDecl>(D));
     }
   }
 
   if (auto *Using = dyn_cast<UsingDecl>(Other))
     return isInstantiationOf(cast<UsingDecl>(D), Using, Ctx);
 
   if (auto *Shadow = dyn_cast<UsingShadowDecl>(Other))
     return isInstantiationOf(cast<UsingShadowDecl>(D), Shadow, Ctx);
 
   return D->getDeclName() &&
          D->getDeclName() == cast<NamedDecl>(Other)->getDeclName();
 }
 
 template<typename ForwardIterator>
 static NamedDecl *findInstantiationOf(ASTContext &Ctx,
                                       NamedDecl *D,
                                       ForwardIterator first,
                                       ForwardIterator last) {
   for (; first != last; ++first)
     if (isInstantiationOf(Ctx, D, *first))
       return cast<NamedDecl>(*first);
 
   return nullptr;
 }
 
 /// Finds the instantiation of the given declaration context
 /// within the current instantiation.
 ///
 /// \returns NULL if there was an error
 DeclContext *Sema::FindInstantiatedContext(SourceLocation Loc, DeclContext* DC,
                           const MultiLevelTemplateArgumentList &TemplateArgs) {
   if (NamedDecl *D = dyn_cast<NamedDecl>(DC)) {
     Decl* ID = FindInstantiatedDecl(Loc, D, TemplateArgs, true);
     return cast_or_null<DeclContext>(ID);
   } else return DC;
 }
 
 /// Determine whether the given context is dependent on template parameters at
 /// level \p Level or below.
 ///
 /// Sometimes we only substitute an inner set of template arguments and leave
 /// the outer templates alone. In such cases, contexts dependent only on the
 /// outer levels are not effectively dependent.
 static bool isDependentContextAtLevel(DeclContext *DC, unsigned Level) {
   if (!DC->isDependentContext())
     return false;
   if (!Level)
     return true;
   return cast<Decl>(DC)->getTemplateDepth() > Level;
 }
 
 /// Find the instantiation of the given declaration within the
 /// current instantiation.
 ///
 /// This routine is intended to be used when \p D is a declaration
 /// referenced from within a template, that needs to mapped into the
 /// corresponding declaration within an instantiation. For example,
 /// given:
 ///
 /// \code
 /// template<typename T>
 /// struct X {
 ///   enum Kind {
 ///     KnownValue = sizeof(T)
 ///   };
 ///
 ///   bool getKind() const { return KnownValue; }
 /// };
 ///
 /// template struct X<int>;
 /// \endcode
 ///
 /// In the instantiation of X<int>::getKind(), we need to map the \p
 /// EnumConstantDecl for \p KnownValue (which refers to
 /// X<T>::<Kind>::KnownValue) to its instantiation (X<int>::<Kind>::KnownValue).
 /// \p FindInstantiatedDecl performs this mapping from within the instantiation
 /// of X<int>.
 NamedDecl *Sema::FindInstantiatedDecl(SourceLocation Loc, NamedDecl *D,
                           const MultiLevelTemplateArgumentList &TemplateArgs,
                           bool FindingInstantiatedContext) {
   DeclContext *ParentDC = D->getDeclContext();
   // Determine whether our parent context depends on any of the template
   // arguments we're currently substituting.
   bool ParentDependsOnArgs = isDependentContextAtLevel(
       ParentDC, TemplateArgs.getNumRetainedOuterLevels());
   // FIXME: Parameters of pointer to functions (y below) that are themselves
   // parameters (p below) can have their ParentDC set to the translation-unit
   // - thus we can not consistently check if the ParentDC of such a parameter
   // is Dependent or/and a FunctionOrMethod.
   // For e.g. this code, during Template argument deduction tries to
   // find an instantiated decl for (T y) when the ParentDC for y is
   // the translation unit.
   //   e.g. template <class T> void Foo(auto (*p)(T y) -> decltype(y())) {}
   //   float baz(float(*)()) { return 0.0; }
   //   Foo(baz);
   // The better fix here is perhaps to ensure that a ParmVarDecl, by the time
   // it gets here, always has a FunctionOrMethod as its ParentDC??
   // For now:
   //  - as long as we have a ParmVarDecl whose parent is non-dependent and
   //    whose type is not instantiation dependent, do nothing to the decl
   //  - otherwise find its instantiated decl.
   if (isa<ParmVarDecl>(D) && !ParentDependsOnArgs &&
       !cast<ParmVarDecl>(D)->getType()->isInstantiationDependentType())
     return D;
   if (isa<ParmVarDecl>(D) || isa<NonTypeTemplateParmDecl>(D) ||
       isa<TemplateTypeParmDecl>(D) || isa<TemplateTemplateParmDecl>(D) ||
       (ParentDependsOnArgs && (ParentDC->isFunctionOrMethod() ||
                                isa<OMPDeclareReductionDecl>(ParentDC) ||
                                isa<OMPDeclareMapperDecl>(ParentDC))) ||
       (isa<CXXRecordDecl>(D) && cast<CXXRecordDecl>(D)->isLambda() &&
        cast<CXXRecordDecl>(D)->getTemplateDepth() >
            TemplateArgs.getNumRetainedOuterLevels())) {
     // D is a local of some kind. Look into the map of local
     // declarations to their instantiations.
     if (CurrentInstantiationScope) {
       if (auto Found = CurrentInstantiationScope->findInstantiationOf(D)) {
         if (Decl *FD = Found->dyn_cast<Decl *>())
           return cast<NamedDecl>(FD);
 
         int PackIdx = ArgumentPackSubstitutionIndex;
         assert(PackIdx != -1 &&
                "found declaration pack but not pack expanding");
         typedef LocalInstantiationScope::DeclArgumentPack DeclArgumentPack;
         return cast<NamedDecl>((*Found->get<DeclArgumentPack *>())[PackIdx]);
       }
     }
 
     // If we're performing a partial substitution during template argument
     // deduction, we may not have values for template parameters yet. They
     // just map to themselves.
     if (isa<NonTypeTemplateParmDecl>(D) || isa<TemplateTypeParmDecl>(D) ||
         isa<TemplateTemplateParmDecl>(D))
       return D;
 
     if (D->isInvalidDecl())
       return nullptr;
 
     // Normally this function only searches for already instantiated declaration
     // however we have to make an exclusion for local types used before
     // definition as in the code:
     //
     //   template<typename T> void f1() {
     //     void g1(struct x1);
     //     struct x1 {};
     //   }
     //
     // In this case instantiation of the type of 'g1' requires definition of
     // 'x1', which is defined later. Error recovery may produce an enum used
     // before definition. In these cases we need to instantiate relevant
     // declarations here.
     bool NeedInstantiate = false;
     if (CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D))
       NeedInstantiate = RD->isLocalClass();
     else if (isa<TypedefNameDecl>(D) &&
              isa<CXXDeductionGuideDecl>(D->getDeclContext()))
       NeedInstantiate = true;
     else
       NeedInstantiate = isa<EnumDecl>(D);
     if (NeedInstantiate) {
       Decl *Inst = SubstDecl(D, CurContext, TemplateArgs);
       CurrentInstantiationScope->InstantiatedLocal(D, Inst);
       return cast<TypeDecl>(Inst);
     }
 
     // If we didn't find the decl, then we must have a label decl that hasn't
     // been found yet.  Lazily instantiate it and return it now.
     assert(isa<LabelDecl>(D));
 
     Decl *Inst = SubstDecl(D, CurContext, TemplateArgs);
     assert(Inst && "Failed to instantiate label??");
 
     CurrentInstantiationScope->InstantiatedLocal(D, Inst);
     return cast<LabelDecl>(Inst);
   }
 
   if (CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(D)) {
     if (!Record->isDependentContext())
       return D;
 
     // Determine whether this record is the "templated" declaration describing
     // a class template or class template partial specialization.
     ClassTemplateDecl *ClassTemplate = Record->getDescribedClassTemplate();
     if (ClassTemplate)
       ClassTemplate = ClassTemplate->getCanonicalDecl();
     else if (ClassTemplatePartialSpecializationDecl *PartialSpec
                = dyn_cast<ClassTemplatePartialSpecializationDecl>(Record))
       ClassTemplate = PartialSpec->getSpecializedTemplate()->getCanonicalDecl();
 
     // Walk the current context to find either the record or an instantiation of
     // it.
     DeclContext *DC = CurContext;
     while (!DC->isFileContext()) {
       // If we're performing substitution while we're inside the template
       // definition, we'll find our own context. We're done.
       if (DC->Equals(Record))
         return Record;
 
       if (CXXRecordDecl *InstRecord = dyn_cast<CXXRecordDecl>(DC)) {
         // Check whether we're in the process of instantiating a class template
         // specialization of the template we're mapping.
         if (ClassTemplateSpecializationDecl *InstSpec
                       = dyn_cast<ClassTemplateSpecializationDecl>(InstRecord)){
           ClassTemplateDecl *SpecTemplate = InstSpec->getSpecializedTemplate();
           if (ClassTemplate && isInstantiationOf(ClassTemplate, SpecTemplate))
             return InstRecord;
         }
 
         // Check whether we're in the process of instantiating a member class.
         if (isInstantiationOf(Record, InstRecord))
           return InstRecord;
       }
 
       // Move to the outer template scope.
       if (FunctionDecl *FD = dyn_cast<FunctionDecl>(DC)) {
         if (FD->getFriendObjectKind() &&
             FD->getNonTransparentDeclContext()->isFileContext()) {
           DC = FD->getLexicalDeclContext();
           continue;
         }
         // An implicit deduction guide acts as if it's within the class template
         // specialization described by its name and first N template params.
         auto *Guide = dyn_cast<CXXDeductionGuideDecl>(FD);
         if (Guide && Guide->isImplicit()) {
           TemplateDecl *TD = Guide->getDeducedTemplate();
           // Convert the arguments to an "as-written" list.
           TemplateArgumentListInfo Args(Loc, Loc);
           for (TemplateArgument Arg : TemplateArgs.getInnermost().take_front(
                                         TD->getTemplateParameters()->size())) {
             ArrayRef<TemplateArgument> Unpacked(Arg);
             if (Arg.getKind() == TemplateArgument::Pack)
               Unpacked = Arg.pack_elements();
             for (TemplateArgument UnpackedArg : Unpacked)
               Args.addArgument(
                   getTrivialTemplateArgumentLoc(UnpackedArg, QualType(), Loc));
           }
           QualType T = CheckTemplateIdType(TemplateName(TD), Loc, Args);
           if (T.isNull())
             return nullptr;
           auto *SubstRecord = T->getAsCXXRecordDecl();
           assert(SubstRecord && "class template id not a class type?");
           // Check that this template-id names the primary template and not a
           // partial or explicit specialization. (In the latter cases, it's
           // meaningless to attempt to find an instantiation of D within the
           // specialization.)
           // FIXME: The standard doesn't say what should happen here.
           if (FindingInstantiatedContext &&
               usesPartialOrExplicitSpecialization(
                   Loc, cast<ClassTemplateSpecializationDecl>(SubstRecord))) {
             Diag(Loc, diag::err_specialization_not_primary_template)
               << T << (SubstRecord->getTemplateSpecializationKind() ==
                            TSK_ExplicitSpecialization);
             return nullptr;
           }
           DC = SubstRecord;
           continue;
         }
       }
 
       DC = DC->getParent();
     }
 
     // Fall through to deal with other dependent record types (e.g.,
     // anonymous unions in class templates).
   }
 
   if (!ParentDependsOnArgs)
     return D;
 
   ParentDC = FindInstantiatedContext(Loc, ParentDC, TemplateArgs);
   if (!ParentDC)
     return nullptr;
 
   if (ParentDC != D->getDeclContext()) {
     // We performed some kind of instantiation in the parent context,
     // so now we need to look into the instantiated parent context to
     // find the instantiation of the declaration D.
 
     // If our context used to be dependent, we may need to instantiate
     // it before performing lookup into that context.
     bool IsBeingInstantiated = false;
     if (CXXRecordDecl *Spec = dyn_cast<CXXRecordDecl>(ParentDC)) {
       if (!Spec->isDependentContext()) {
         QualType T = Context.getTypeDeclType(Spec);
         const RecordType *Tag = T->getAs<RecordType>();
         assert(Tag && "type of non-dependent record is not a RecordType");
         if (Tag->isBeingDefined())
           IsBeingInstantiated = true;
         if (!Tag->isBeingDefined() &&
             RequireCompleteType(Loc, T, diag::err_incomplete_type))
           return nullptr;
 
         ParentDC = Tag->getDecl();
       }
     }
 
     NamedDecl *Result = nullptr;
     // FIXME: If the name is a dependent name, this lookup won't necessarily
     // find it. Does that ever matter?
     if (auto Name = D->getDeclName()) {
       DeclarationNameInfo NameInfo(Name, D->getLocation());
       DeclarationNameInfo NewNameInfo =
           SubstDeclarationNameInfo(NameInfo, TemplateArgs);
       Name = NewNameInfo.getName();
       if (!Name)
         return nullptr;
       DeclContext::lookup_result Found = ParentDC->lookup(Name);
 
       Result = findInstantiationOf(Context, D, Found.begin(), Found.end());
     } else {
       // Since we don't have a name for the entity we're looking for,
       // our only option is to walk through all of the declarations to
       // find that name. This will occur in a few cases:
       //
       //   - anonymous struct/union within a template
       //   - unnamed class/struct/union/enum within a template
       //
       // FIXME: Find a better way to find these instantiations!
       Result = findInstantiationOf(Context, D,
                                    ParentDC->decls_begin(),
                                    ParentDC->decls_end());
     }
 
     if (!Result) {
       if (isa<UsingShadowDecl>(D)) {
         // UsingShadowDecls can instantiate to nothing because of using hiding.
       } else if (hasUncompilableErrorOccurred()) {
         // We've already complained about some ill-formed code, so most likely
         // this declaration failed to instantiate. There's no point in
         // complaining further, since this is normal in invalid code.
         // FIXME: Use more fine-grained 'invalid' tracking for this.
       } else if (IsBeingInstantiated) {
         // The class in which this member exists is currently being
         // instantiated, and we haven't gotten around to instantiating this
         // member yet. This can happen when the code uses forward declarations
         // of member classes, and introduces ordering dependencies via
         // template instantiation.
         Diag(Loc, diag::err_member_not_yet_instantiated)
           << D->getDeclName()
           << Context.getTypeDeclType(cast<CXXRecordDecl>(ParentDC));
         Diag(D->getLocation(), diag::note_non_instantiated_member_here);
       } else if (EnumConstantDecl *ED = dyn_cast<EnumConstantDecl>(D)) {
         // This enumeration constant was found when the template was defined,
         // but can't be found in the instantiation. This can happen if an
         // unscoped enumeration member is explicitly specialized.
         EnumDecl *Enum = cast<EnumDecl>(ED->getLexicalDeclContext());
         EnumDecl *Spec = cast<EnumDecl>(FindInstantiatedDecl(Loc, Enum,
                                                              TemplateArgs));
         assert(Spec->getTemplateSpecializationKind() ==
                  TSK_ExplicitSpecialization);
         Diag(Loc, diag::err_enumerator_does_not_exist)
           << D->getDeclName()
           << Context.getTypeDeclType(cast<TypeDecl>(Spec->getDeclContext()));
         Diag(Spec->getLocation(), diag::note_enum_specialized_here)
           << Context.getTypeDeclType(Spec);
       } else {
         // We should have found something, but didn't.
         llvm_unreachable("Unable to find instantiation of declaration!");
       }
     }
 
     D = Result;
   }
 
   return D;
 }
 
 /// Performs template instantiation for all implicit template
 /// instantiations we have seen until this point.
 void Sema::PerformPendingInstantiations(bool LocalOnly) {
   std::deque<PendingImplicitInstantiation> delayedPCHInstantiations;
   while (!PendingLocalImplicitInstantiations.empty() ||
          (!LocalOnly && !PendingInstantiations.empty())) {
     PendingImplicitInstantiation Inst;
 
     if (PendingLocalImplicitInstantiations.empty()) {
       Inst = PendingInstantiations.front();
       PendingInstantiations.pop_front();
     } else {
       Inst = PendingLocalImplicitInstantiations.front();
       PendingLocalImplicitInstantiations.pop_front();
     }
 
     // Instantiate function definitions
     if (FunctionDecl *Function = dyn_cast<FunctionDecl>(Inst.first)) {
       bool DefinitionRequired = Function->getTemplateSpecializationKind() ==
                                 TSK_ExplicitInstantiationDefinition;
       if (Function->isMultiVersion()) {
         getASTContext().forEachMultiversionedFunctionVersion(
             Function, [this, Inst, DefinitionRequired](FunctionDecl *CurFD) {
               InstantiateFunctionDefinition(/*FIXME:*/ Inst.second, CurFD, true,
                                             DefinitionRequired, true);
               if (CurFD->isDefined())
                 CurFD->setInstantiationIsPending(false);
             });
       } else {
         InstantiateFunctionDefinition(/*FIXME:*/ Inst.second, Function, true,
                                       DefinitionRequired, true);
         if (Function->isDefined())
           Function->setInstantiationIsPending(false);
       }
       // Definition of a PCH-ed template declaration may be available only in the TU.
       if (!LocalOnly && LangOpts.PCHInstantiateTemplates &&
           TUKind == TU_Prefix && Function->instantiationIsPending())
         delayedPCHInstantiations.push_back(Inst);
       continue;
     }
 
     // Instantiate variable definitions
     VarDecl *Var = cast<VarDecl>(Inst.first);
 
     assert((Var->isStaticDataMember() ||
             isa<VarTemplateSpecializationDecl>(Var)) &&
            "Not a static data member, nor a variable template"
            " specialization?");
 
     // Don't try to instantiate declarations if the most recent redeclaration
     // is invalid.
     if (Var->getMostRecentDecl()->isInvalidDecl())
       continue;
 
     // Check if the most recent declaration has changed the specialization kind
     // and removed the need for implicit instantiation.
     switch (Var->getMostRecentDecl()
                 ->getTemplateSpecializationKindForInstantiation()) {
     case TSK_Undeclared:
       llvm_unreachable("Cannot instantitiate an undeclared specialization.");
     case TSK_ExplicitInstantiationDeclaration:
     case TSK_ExplicitSpecialization:
       continue;  // No longer need to instantiate this type.
     case TSK_ExplicitInstantiationDefinition:
       // We only need an instantiation if the pending instantiation *is* the
       // explicit instantiation.
       if (Var != Var->getMostRecentDecl())
         continue;
       break;
     case TSK_ImplicitInstantiation:
       break;
     }
 
     PrettyDeclStackTraceEntry CrashInfo(Context, Var, SourceLocation(),
                                         "instantiating variable definition");
     bool DefinitionRequired = Var->getTemplateSpecializationKind() ==
                               TSK_ExplicitInstantiationDefinition;
 
     // Instantiate static data member definitions or variable template
     // specializations.
     InstantiateVariableDefinition(/*FIXME:*/ Inst.second, Var, true,
                                   DefinitionRequired, true);
   }
 
   if (!LocalOnly && LangOpts.PCHInstantiateTemplates)
     PendingInstantiations.swap(delayedPCHInstantiations);
 }
 
 void Sema::PerformDependentDiagnostics(const DeclContext *Pattern,
                        const MultiLevelTemplateArgumentList &TemplateArgs) {
   for (auto *DD : Pattern->ddiags()) {
     switch (DD->getKind()) {
     case DependentDiagnostic::Access:
       HandleDependentAccessCheck(*DD, TemplateArgs);
       break;
     }
   }
 }
diff --git a/contrib/llvm-project/clang/lib/Sema/TreeTransform.h b/contrib/llvm-project/clang/lib/Sema/TreeTransform.h
index 097e81ea7d45..b51741d5e8b2 100644
--- a/contrib/llvm-project/clang/lib/Sema/TreeTransform.h
+++ b/contrib/llvm-project/clang/lib/Sema/TreeTransform.h
@@ -1,15344 +1,15353 @@
 //===------- TreeTransform.h - Semantic Tree Transformation -----*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //===----------------------------------------------------------------------===//
 //
 //  This file implements a semantic tree transformation that takes a given
 //  AST and rebuilds it, possibly transforming some nodes in the process.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CLANG_LIB_SEMA_TREETRANSFORM_H
 #define LLVM_CLANG_LIB_SEMA_TREETRANSFORM_H
 
 #include "CoroutineStmtBuilder.h"
 #include "TypeLocBuilder.h"
 #include "clang/AST/Decl.h"
 #include "clang/AST/DeclObjC.h"
 #include "clang/AST/DeclTemplate.h"
 #include "clang/AST/Expr.h"
 #include "clang/AST/ExprCXX.h"
 #include "clang/AST/ExprConcepts.h"
 #include "clang/AST/ExprObjC.h"
 #include "clang/AST/ExprOpenMP.h"
 #include "clang/AST/OpenMPClause.h"
 #include "clang/AST/Stmt.h"
 #include "clang/AST/StmtCXX.h"
 #include "clang/AST/StmtObjC.h"
 #include "clang/AST/StmtOpenMP.h"
 #include "clang/Basic/DiagnosticParse.h"
 #include "clang/Basic/OpenMPKinds.h"
 #include "clang/Sema/Designator.h"
 #include "clang/Sema/EnterExpressionEvaluationContext.h"
 #include "clang/Sema/Lookup.h"
 #include "clang/Sema/Ownership.h"
 #include "clang/Sema/ParsedTemplate.h"
 #include "clang/Sema/ScopeInfo.h"
 #include "clang/Sema/SemaDiagnostic.h"
 #include "clang/Sema/SemaInternal.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/Support/ErrorHandling.h"
 #include <algorithm>
 #include <optional>
 
 using namespace llvm::omp;
 
 namespace clang {
 using namespace sema;
 
 /// A semantic tree transformation that allows one to transform one
 /// abstract syntax tree into another.
 ///
 /// A new tree transformation is defined by creating a new subclass \c X of
 /// \c TreeTransform<X> and then overriding certain operations to provide
 /// behavior specific to that transformation. For example, template
 /// instantiation is implemented as a tree transformation where the
 /// transformation of TemplateTypeParmType nodes involves substituting the
 /// template arguments for their corresponding template parameters; a similar
 /// transformation is performed for non-type template parameters and
 /// template template parameters.
 ///
 /// This tree-transformation template uses static polymorphism to allow
 /// subclasses to customize any of its operations. Thus, a subclass can
 /// override any of the transformation or rebuild operators by providing an
 /// operation with the same signature as the default implementation. The
 /// overriding function should not be virtual.
 ///
 /// Semantic tree transformations are split into two stages, either of which
 /// can be replaced by a subclass. The "transform" step transforms an AST node
 /// or the parts of an AST node using the various transformation functions,
 /// then passes the pieces on to the "rebuild" step, which constructs a new AST
 /// node of the appropriate kind from the pieces. The default transformation
 /// routines recursively transform the operands to composite AST nodes (e.g.,
 /// the pointee type of a PointerType node) and, if any of those operand nodes
 /// were changed by the transformation, invokes the rebuild operation to create
 /// a new AST node.
 ///
 /// Subclasses can customize the transformation at various levels. The
 /// most coarse-grained transformations involve replacing TransformType(),
 /// TransformExpr(), TransformDecl(), TransformNestedNameSpecifierLoc(),
 /// TransformTemplateName(), or TransformTemplateArgument() with entirely
 /// new implementations.
 ///
 /// For more fine-grained transformations, subclasses can replace any of the
 /// \c TransformXXX functions (where XXX is the name of an AST node, e.g.,
 /// PointerType, StmtExpr) to alter the transformation. As mentioned previously,
 /// replacing TransformTemplateTypeParmType() allows template instantiation
 /// to substitute template arguments for their corresponding template
 /// parameters. Additionally, subclasses can override the \c RebuildXXX
 /// functions to control how AST nodes are rebuilt when their operands change.
 /// By default, \c TreeTransform will invoke semantic analysis to rebuild
 /// AST nodes. However, certain other tree transformations (e.g, cloning) may
 /// be able to use more efficient rebuild steps.
 ///
 /// There are a handful of other functions that can be overridden, allowing one
 /// to avoid traversing nodes that don't need any transformation
 /// (\c AlreadyTransformed()), force rebuilding AST nodes even when their
 /// operands have not changed (\c AlwaysRebuild()), and customize the
 /// default locations and entity names used for type-checking
 /// (\c getBaseLocation(), \c getBaseEntity()).
 template<typename Derived>
 class TreeTransform {
   /// Private RAII object that helps us forget and then re-remember
   /// the template argument corresponding to a partially-substituted parameter
   /// pack.
   class ForgetPartiallySubstitutedPackRAII {
     Derived &Self;
     TemplateArgument Old;
 
   public:
     ForgetPartiallySubstitutedPackRAII(Derived &Self) : Self(Self) {
       Old = Self.ForgetPartiallySubstitutedPack();
     }
 
     ~ForgetPartiallySubstitutedPackRAII() {
       Self.RememberPartiallySubstitutedPack(Old);
     }
   };
 
 protected:
   Sema &SemaRef;
 
   /// The set of local declarations that have been transformed, for
   /// cases where we are forced to build new declarations within the transformer
   /// rather than in the subclass (e.g., lambda closure types).
   llvm::DenseMap<Decl *, Decl *> TransformedLocalDecls;
 
 public:
   /// Initializes a new tree transformer.
   TreeTransform(Sema &SemaRef) : SemaRef(SemaRef) { }
 
   /// Retrieves a reference to the derived class.
   Derived &getDerived() { return static_cast<Derived&>(*this); }
 
   /// Retrieves a reference to the derived class.
   const Derived &getDerived() const {
     return static_cast<const Derived&>(*this);
   }
 
   static inline ExprResult Owned(Expr *E) { return E; }
   static inline StmtResult Owned(Stmt *S) { return S; }
 
   /// Retrieves a reference to the semantic analysis object used for
   /// this tree transform.
   Sema &getSema() const { return SemaRef; }
 
   /// Whether the transformation should always rebuild AST nodes, even
   /// if none of the children have changed.
   ///
   /// Subclasses may override this function to specify when the transformation
   /// should rebuild all AST nodes.
   ///
   /// We must always rebuild all AST nodes when performing variadic template
   /// pack expansion, in order to avoid violating the AST invariant that each
   /// statement node appears at most once in its containing declaration.
   bool AlwaysRebuild() { return SemaRef.ArgumentPackSubstitutionIndex != -1; }
 
   /// Whether the transformation is forming an expression or statement that
   /// replaces the original. In this case, we'll reuse mangling numbers from
   /// existing lambdas.
   bool ReplacingOriginal() { return false; }
 
   /// Wether CXXConstructExpr can be skipped when they are implicit.
   /// They will be reconstructed when used if needed.
   /// This is useful when the user that cause rebuilding of the
   /// CXXConstructExpr is outside of the expression at which the TreeTransform
   /// started.
   bool AllowSkippingCXXConstructExpr() { return true; }
 
   /// Returns the location of the entity being transformed, if that
   /// information was not available elsewhere in the AST.
   ///
   /// By default, returns no source-location information. Subclasses can
   /// provide an alternative implementation that provides better location
   /// information.
   SourceLocation getBaseLocation() { return SourceLocation(); }
 
   /// Returns the name of the entity being transformed, if that
   /// information was not available elsewhere in the AST.
   ///
   /// By default, returns an empty name. Subclasses can provide an alternative
   /// implementation with a more precise name.
   DeclarationName getBaseEntity() { return DeclarationName(); }
 
   /// Sets the "base" location and entity when that
   /// information is known based on another transformation.
   ///
   /// By default, the source location and entity are ignored. Subclasses can
   /// override this function to provide a customized implementation.
   void setBase(SourceLocation Loc, DeclarationName Entity) { }
 
   /// RAII object that temporarily sets the base location and entity
   /// used for reporting diagnostics in types.
   class TemporaryBase {
     TreeTransform &Self;
     SourceLocation OldLocation;
     DeclarationName OldEntity;
 
   public:
     TemporaryBase(TreeTransform &Self, SourceLocation Location,
                   DeclarationName Entity) : Self(Self) {
       OldLocation = Self.getDerived().getBaseLocation();
       OldEntity = Self.getDerived().getBaseEntity();
 
       if (Location.isValid())
         Self.getDerived().setBase(Location, Entity);
     }
 
     ~TemporaryBase() {
       Self.getDerived().setBase(OldLocation, OldEntity);
     }
   };
 
   /// Determine whether the given type \p T has already been
   /// transformed.
   ///
   /// Subclasses can provide an alternative implementation of this routine
   /// to short-circuit evaluation when it is known that a given type will
   /// not change. For example, template instantiation need not traverse
   /// non-dependent types.
   bool AlreadyTransformed(QualType T) {
     return T.isNull();
   }
 
   /// Transform a template parameter depth level.
   ///
   /// During a transformation that transforms template parameters, this maps
   /// an old template parameter depth to a new depth.
   unsigned TransformTemplateDepth(unsigned Depth) {
     return Depth;
   }
 
   /// Determine whether the given call argument should be dropped, e.g.,
   /// because it is a default argument.
   ///
   /// Subclasses can provide an alternative implementation of this routine to
   /// determine which kinds of call arguments get dropped. By default,
   /// CXXDefaultArgument nodes are dropped (prior to transformation).
   bool DropCallArgument(Expr *E) {
     return E->isDefaultArgument();
   }
 
   /// Determine whether we should expand a pack expansion with the
   /// given set of parameter packs into separate arguments by repeatedly
   /// transforming the pattern.
   ///
   /// By default, the transformer never tries to expand pack expansions.
   /// Subclasses can override this routine to provide different behavior.
   ///
   /// \param EllipsisLoc The location of the ellipsis that identifies the
   /// pack expansion.
   ///
   /// \param PatternRange The source range that covers the entire pattern of
   /// the pack expansion.
   ///
   /// \param Unexpanded The set of unexpanded parameter packs within the
   /// pattern.
   ///
   /// \param ShouldExpand Will be set to \c true if the transformer should
   /// expand the corresponding pack expansions into separate arguments. When
   /// set, \c NumExpansions must also be set.
   ///
   /// \param RetainExpansion Whether the caller should add an unexpanded
   /// pack expansion after all of the expanded arguments. This is used
   /// when extending explicitly-specified template argument packs per
   /// C++0x [temp.arg.explicit]p9.
   ///
   /// \param NumExpansions The number of separate arguments that will be in
   /// the expanded form of the corresponding pack expansion. This is both an
   /// input and an output parameter, which can be set by the caller if the
   /// number of expansions is known a priori (e.g., due to a prior substitution)
   /// and will be set by the callee when the number of expansions is known.
   /// The callee must set this value when \c ShouldExpand is \c true; it may
   /// set this value in other cases.
   ///
   /// \returns true if an error occurred (e.g., because the parameter packs
   /// are to be instantiated with arguments of different lengths), false
   /// otherwise. If false, \c ShouldExpand (and possibly \c NumExpansions)
   /// must be set.
   bool TryExpandParameterPacks(SourceLocation EllipsisLoc,
                                SourceRange PatternRange,
                                ArrayRef<UnexpandedParameterPack> Unexpanded,
                                bool &ShouldExpand, bool &RetainExpansion,
                                std::optional<unsigned> &NumExpansions) {
     ShouldExpand = false;
     return false;
   }
 
   /// "Forget" about the partially-substituted pack template argument,
   /// when performing an instantiation that must preserve the parameter pack
   /// use.
   ///
   /// This routine is meant to be overridden by the template instantiator.
   TemplateArgument ForgetPartiallySubstitutedPack() {
     return TemplateArgument();
   }
 
   /// "Remember" the partially-substituted pack template argument
   /// after performing an instantiation that must preserve the parameter pack
   /// use.
   ///
   /// This routine is meant to be overridden by the template instantiator.
   void RememberPartiallySubstitutedPack(TemplateArgument Arg) { }
 
   /// Note to the derived class when a function parameter pack is
   /// being expanded.
   void ExpandingFunctionParameterPack(ParmVarDecl *Pack) { }
 
   /// Transforms the given type into another type.
   ///
   /// By default, this routine transforms a type by creating a
   /// TypeSourceInfo for it and delegating to the appropriate
   /// function.  This is expensive, but we don't mind, because
   /// this method is deprecated anyway;  all users should be
   /// switched to storing TypeSourceInfos.
   ///
   /// \returns the transformed type.
   QualType TransformType(QualType T);
 
   /// Transforms the given type-with-location into a new
   /// type-with-location.
   ///
   /// By default, this routine transforms a type by delegating to the
   /// appropriate TransformXXXType to build a new type.  Subclasses
   /// may override this function (to take over all type
   /// transformations) or some set of the TransformXXXType functions
   /// to alter the transformation.
   TypeSourceInfo *TransformType(TypeSourceInfo *DI);
 
   /// Transform the given type-with-location into a new
   /// type, collecting location information in the given builder
   /// as necessary.
   ///
   QualType TransformType(TypeLocBuilder &TLB, TypeLoc TL);
 
   /// Transform a type that is permitted to produce a
   /// DeducedTemplateSpecializationType.
   ///
   /// This is used in the (relatively rare) contexts where it is acceptable
   /// for transformation to produce a class template type with deduced
   /// template arguments.
   /// @{
   QualType TransformTypeWithDeducedTST(QualType T);
   TypeSourceInfo *TransformTypeWithDeducedTST(TypeSourceInfo *DI);
   /// @}
 
   /// The reason why the value of a statement is not discarded, if any.
   enum StmtDiscardKind {
     SDK_Discarded,
     SDK_NotDiscarded,
     SDK_StmtExprResult,
   };
 
   /// Transform the given statement.
   ///
   /// By default, this routine transforms a statement by delegating to the
   /// appropriate TransformXXXStmt function to transform a specific kind of
   /// statement or the TransformExpr() function to transform an expression.
   /// Subclasses may override this function to transform statements using some
   /// other mechanism.
   ///
   /// \returns the transformed statement.
   StmtResult TransformStmt(Stmt *S, StmtDiscardKind SDK = SDK_Discarded);
 
   /// Transform the given statement.
   ///
   /// By default, this routine transforms a statement by delegating to the
   /// appropriate TransformOMPXXXClause function to transform a specific kind
   /// of clause. Subclasses may override this function to transform statements
   /// using some other mechanism.
   ///
   /// \returns the transformed OpenMP clause.
   OMPClause *TransformOMPClause(OMPClause *S);
 
   /// Transform the given attribute.
   ///
   /// By default, this routine transforms a statement by delegating to the
   /// appropriate TransformXXXAttr function to transform a specific kind
   /// of attribute. Subclasses may override this function to transform
   /// attributed statements/types using some other mechanism.
   ///
   /// \returns the transformed attribute
   const Attr *TransformAttr(const Attr *S);
 
   // Transform the given statement attribute.
   //
   // Delegates to the appropriate TransformXXXAttr function to transform a
   // specific kind of statement attribute. Unlike the non-statement taking
   // version of this, this implements all attributes, not just pragmas.
   const Attr *TransformStmtAttr(const Stmt *OrigS, const Stmt *InstS,
                                 const Attr *A);
 
   // Transform the specified attribute.
   //
   // Subclasses should override the transformation of attributes with a pragma
   // spelling to transform expressions stored within the attribute.
   //
   // \returns the transformed attribute.
 #define ATTR(X)                                                                \
   const X##Attr *Transform##X##Attr(const X##Attr *R) { return R; }
 #include "clang/Basic/AttrList.inc"
 
   // Transform the specified attribute.
   //
   // Subclasses should override the transformation of attributes to do
   // transformation and checking of statement attributes. By default, this
   // delegates to the non-statement taking version.
   //
   // \returns the transformed attribute.
 #define ATTR(X)                                                                \
   const X##Attr *TransformStmt##X##Attr(const Stmt *, const Stmt *,            \
                                         const X##Attr *A) {                    \
     return getDerived().Transform##X##Attr(A);                                 \
   }
 #include "clang/Basic/AttrList.inc"
 
   /// Transform the given expression.
   ///
   /// By default, this routine transforms an expression by delegating to the
   /// appropriate TransformXXXExpr function to build a new expression.
   /// Subclasses may override this function to transform expressions using some
   /// other mechanism.
   ///
   /// \returns the transformed expression.
   ExprResult TransformExpr(Expr *E);
 
   /// Transform the given initializer.
   ///
   /// By default, this routine transforms an initializer by stripping off the
   /// semantic nodes added by initialization, then passing the result to
   /// TransformExpr or TransformExprs.
   ///
   /// \returns the transformed initializer.
   ExprResult TransformInitializer(Expr *Init, bool NotCopyInit);
 
   /// Transform the given list of expressions.
   ///
   /// This routine transforms a list of expressions by invoking
   /// \c TransformExpr() for each subexpression. However, it also provides
   /// support for variadic templates by expanding any pack expansions (if the
   /// derived class permits such expansion) along the way. When pack expansions
   /// are present, the number of outputs may not equal the number of inputs.
   ///
   /// \param Inputs The set of expressions to be transformed.
   ///
   /// \param NumInputs The number of expressions in \c Inputs.
   ///
   /// \param IsCall If \c true, then this transform is being performed on
   /// function-call arguments, and any arguments that should be dropped, will
   /// be.
   ///
   /// \param Outputs The transformed input expressions will be added to this
   /// vector.
   ///
   /// \param ArgChanged If non-NULL, will be set \c true if any argument changed
   /// due to transformation.
   ///
   /// \returns true if an error occurred, false otherwise.
   bool TransformExprs(Expr *const *Inputs, unsigned NumInputs, bool IsCall,
                       SmallVectorImpl<Expr *> &Outputs,
                       bool *ArgChanged = nullptr);
 
   /// Transform the given declaration, which is referenced from a type
   /// or expression.
   ///
   /// By default, acts as the identity function on declarations, unless the
   /// transformer has had to transform the declaration itself. Subclasses
   /// may override this function to provide alternate behavior.
   Decl *TransformDecl(SourceLocation Loc, Decl *D) {
     llvm::DenseMap<Decl *, Decl *>::iterator Known
       = TransformedLocalDecls.find(D);
     if (Known != TransformedLocalDecls.end())
       return Known->second;
 
     return D;
   }
 
   /// Transform the specified condition.
   ///
   /// By default, this transforms the variable and expression and rebuilds
   /// the condition.
   Sema::ConditionResult TransformCondition(SourceLocation Loc, VarDecl *Var,
                                            Expr *Expr,
                                            Sema::ConditionKind Kind);
 
   /// Transform the attributes associated with the given declaration and
   /// place them on the new declaration.
   ///
   /// By default, this operation does nothing. Subclasses may override this
   /// behavior to transform attributes.
   void transformAttrs(Decl *Old, Decl *New) { }
 
   /// Note that a local declaration has been transformed by this
   /// transformer.
   ///
   /// Local declarations are typically transformed via a call to
   /// TransformDefinition. However, in some cases (e.g., lambda expressions),
   /// the transformer itself has to transform the declarations. This routine
   /// can be overridden by a subclass that keeps track of such mappings.
   void transformedLocalDecl(Decl *Old, ArrayRef<Decl *> New) {
     assert(New.size() == 1 &&
            "must override transformedLocalDecl if performing pack expansion");
     TransformedLocalDecls[Old] = New.front();
   }
 
   /// Transform the definition of the given declaration.
   ///
   /// By default, invokes TransformDecl() to transform the declaration.
   /// Subclasses may override this function to provide alternate behavior.
   Decl *TransformDefinition(SourceLocation Loc, Decl *D) {
     return getDerived().TransformDecl(Loc, D);
   }
 
   /// Transform the given declaration, which was the first part of a
   /// nested-name-specifier in a member access expression.
   ///
   /// This specific declaration transformation only applies to the first
   /// identifier in a nested-name-specifier of a member access expression, e.g.,
   /// the \c T in \c x->T::member
   ///
   /// By default, invokes TransformDecl() to transform the declaration.
   /// Subclasses may override this function to provide alternate behavior.
   NamedDecl *TransformFirstQualifierInScope(NamedDecl *D, SourceLocation Loc) {
     return cast_or_null<NamedDecl>(getDerived().TransformDecl(Loc, D));
   }
 
   /// Transform the set of declarations in an OverloadExpr.
   bool TransformOverloadExprDecls(OverloadExpr *Old, bool RequiresADL,
                                   LookupResult &R);
 
   /// Transform the given nested-name-specifier with source-location
   /// information.
   ///
   /// By default, transforms all of the types and declarations within the
   /// nested-name-specifier. Subclasses may override this function to provide
   /// alternate behavior.
   NestedNameSpecifierLoc
   TransformNestedNameSpecifierLoc(NestedNameSpecifierLoc NNS,
                                   QualType ObjectType = QualType(),
                                   NamedDecl *FirstQualifierInScope = nullptr);
 
   /// Transform the given declaration name.
   ///
   /// By default, transforms the types of conversion function, constructor,
   /// and destructor names and then (if needed) rebuilds the declaration name.
   /// Identifiers and selectors are returned unmodified. Subclasses may
   /// override this function to provide alternate behavior.
   DeclarationNameInfo
   TransformDeclarationNameInfo(const DeclarationNameInfo &NameInfo);
 
   bool TransformRequiresExprRequirements(ArrayRef<concepts::Requirement *> Reqs,
       llvm::SmallVectorImpl<concepts::Requirement *> &Transformed);
   concepts::TypeRequirement *
   TransformTypeRequirement(concepts::TypeRequirement *Req);
   concepts::ExprRequirement *
   TransformExprRequirement(concepts::ExprRequirement *Req);
   concepts::NestedRequirement *
   TransformNestedRequirement(concepts::NestedRequirement *Req);
 
   /// Transform the given template name.
   ///
   /// \param SS The nested-name-specifier that qualifies the template
   /// name. This nested-name-specifier must already have been transformed.
   ///
   /// \param Name The template name to transform.
   ///
   /// \param NameLoc The source location of the template name.
   ///
   /// \param ObjectType If we're translating a template name within a member
   /// access expression, this is the type of the object whose member template
   /// is being referenced.
   ///
   /// \param FirstQualifierInScope If the first part of a nested-name-specifier
   /// also refers to a name within the current (lexical) scope, this is the
   /// declaration it refers to.
   ///
   /// By default, transforms the template name by transforming the declarations
   /// and nested-name-specifiers that occur within the template name.
   /// Subclasses may override this function to provide alternate behavior.
   TemplateName
   TransformTemplateName(CXXScopeSpec &SS, TemplateName Name,
                         SourceLocation NameLoc,
                         QualType ObjectType = QualType(),
                         NamedDecl *FirstQualifierInScope = nullptr,
                         bool AllowInjectedClassName = false);
 
   /// Transform the given template argument.
   ///
   /// By default, this operation transforms the type, expression, or
   /// declaration stored within the template argument and constructs a
   /// new template argument from the transformed result. Subclasses may
   /// override this function to provide alternate behavior.
   ///
   /// Returns true if there was an error.
   bool TransformTemplateArgument(const TemplateArgumentLoc &Input,
                                  TemplateArgumentLoc &Output,
                                  bool Uneval = false);
 
   /// Transform the given set of template arguments.
   ///
   /// By default, this operation transforms all of the template arguments
   /// in the input set using \c TransformTemplateArgument(), and appends
   /// the transformed arguments to the output list.
   ///
   /// Note that this overload of \c TransformTemplateArguments() is merely
   /// a convenience function. Subclasses that wish to override this behavior
   /// should override the iterator-based member template version.
   ///
   /// \param Inputs The set of template arguments to be transformed.
   ///
   /// \param NumInputs The number of template arguments in \p Inputs.
   ///
   /// \param Outputs The set of transformed template arguments output by this
   /// routine.
   ///
   /// Returns true if an error occurred.
   bool TransformTemplateArguments(const TemplateArgumentLoc *Inputs,
                                   unsigned NumInputs,
                                   TemplateArgumentListInfo &Outputs,
                                   bool Uneval = false) {
     return TransformTemplateArguments(Inputs, Inputs + NumInputs, Outputs,
                                       Uneval);
   }
 
   /// Transform the given set of template arguments.
   ///
   /// By default, this operation transforms all of the template arguments
   /// in the input set using \c TransformTemplateArgument(), and appends
   /// the transformed arguments to the output list.
   ///
   /// \param First An iterator to the first template argument.
   ///
   /// \param Last An iterator one step past the last template argument.
   ///
   /// \param Outputs The set of transformed template arguments output by this
   /// routine.
   ///
   /// Returns true if an error occurred.
   template<typename InputIterator>
   bool TransformTemplateArguments(InputIterator First,
                                   InputIterator Last,
                                   TemplateArgumentListInfo &Outputs,
                                   bool Uneval = false);
 
   /// Fakes up a TemplateArgumentLoc for a given TemplateArgument.
   void InventTemplateArgumentLoc(const TemplateArgument &Arg,
                                  TemplateArgumentLoc &ArgLoc);
 
   /// Fakes up a TypeSourceInfo for a type.
   TypeSourceInfo *InventTypeSourceInfo(QualType T) {
     return SemaRef.Context.getTrivialTypeSourceInfo(T,
                        getDerived().getBaseLocation());
   }
 
 #define ABSTRACT_TYPELOC(CLASS, PARENT)
 #define TYPELOC(CLASS, PARENT)                                   \
   QualType Transform##CLASS##Type(TypeLocBuilder &TLB, CLASS##TypeLoc T);
 #include "clang/AST/TypeLocNodes.def"
 
   QualType TransformTemplateTypeParmType(TypeLocBuilder &TLB,
                                          TemplateTypeParmTypeLoc TL,
                                          bool SuppressObjCLifetime);
   QualType
   TransformSubstTemplateTypeParmPackType(TypeLocBuilder &TLB,
                                          SubstTemplateTypeParmPackTypeLoc TL,
                                          bool SuppressObjCLifetime);
 
   template<typename Fn>
   QualType TransformFunctionProtoType(TypeLocBuilder &TLB,
                                       FunctionProtoTypeLoc TL,
                                       CXXRecordDecl *ThisContext,
                                       Qualifiers ThisTypeQuals,
                                       Fn TransformExceptionSpec);
 
   bool TransformExceptionSpec(SourceLocation Loc,
                               FunctionProtoType::ExceptionSpecInfo &ESI,
                               SmallVectorImpl<QualType> &Exceptions,
                               bool &Changed);
 
   StmtResult TransformSEHHandler(Stmt *Handler);
 
   QualType
   TransformTemplateSpecializationType(TypeLocBuilder &TLB,
                                       TemplateSpecializationTypeLoc TL,
                                       TemplateName Template);
 
   QualType
   TransformDependentTemplateSpecializationType(TypeLocBuilder &TLB,
                                       DependentTemplateSpecializationTypeLoc TL,
                                                TemplateName Template,
                                                CXXScopeSpec &SS);
 
   QualType TransformDependentTemplateSpecializationType(
       TypeLocBuilder &TLB, DependentTemplateSpecializationTypeLoc TL,
       NestedNameSpecifierLoc QualifierLoc);
 
   /// Transforms the parameters of a function type into the
   /// given vectors.
   ///
   /// The result vectors should be kept in sync; null entries in the
   /// variables vector are acceptable.
   ///
   /// LastParamTransformed, if non-null, will be set to the index of the last
   /// parameter on which transfromation was started. In the event of an error,
   /// this will contain the parameter which failed to instantiate.
   ///
   /// Return true on error.
   bool TransformFunctionTypeParams(
       SourceLocation Loc, ArrayRef<ParmVarDecl *> Params,
       const QualType *ParamTypes,
       const FunctionProtoType::ExtParameterInfo *ParamInfos,
       SmallVectorImpl<QualType> &PTypes, SmallVectorImpl<ParmVarDecl *> *PVars,
       Sema::ExtParameterInfoBuilder &PInfos, unsigned *LastParamTransformed);
 
   bool TransformFunctionTypeParams(
       SourceLocation Loc, ArrayRef<ParmVarDecl *> Params,
       const QualType *ParamTypes,
       const FunctionProtoType::ExtParameterInfo *ParamInfos,
       SmallVectorImpl<QualType> &PTypes, SmallVectorImpl<ParmVarDecl *> *PVars,
       Sema::ExtParameterInfoBuilder &PInfos) {
     return getDerived().TransformFunctionTypeParams(
         Loc, Params, ParamTypes, ParamInfos, PTypes, PVars, PInfos, nullptr);
   }
 
   /// Transforms the parameters of a requires expresison into the given vectors.
   ///
   /// The result vectors should be kept in sync; null entries in the
   /// variables vector are acceptable.
   ///
   /// Returns an unset ExprResult on success.  Returns an ExprResult the 'not
   /// satisfied' RequiresExpr if subsitution failed, OR an ExprError, both of
   /// which are cases where transformation shouldn't continue.
   ExprResult TransformRequiresTypeParams(
       SourceLocation KWLoc, SourceLocation RBraceLoc, const RequiresExpr *RE,
       RequiresExprBodyDecl *Body, ArrayRef<ParmVarDecl *> Params,
       SmallVectorImpl<QualType> &PTypes,
       SmallVectorImpl<ParmVarDecl *> &TransParams,
       Sema::ExtParameterInfoBuilder &PInfos) {
     if (getDerived().TransformFunctionTypeParams(
             KWLoc, Params, /*ParamTypes=*/nullptr,
             /*ParamInfos=*/nullptr, PTypes, &TransParams, PInfos))
       return ExprError();
 
     return ExprResult{};
   }
 
   /// Transforms a single function-type parameter.  Return null
   /// on error.
   ///
   /// \param indexAdjustment - A number to add to the parameter's
   ///   scope index;  can be negative
   ParmVarDecl *TransformFunctionTypeParam(ParmVarDecl *OldParm,
                                           int indexAdjustment,
                                           std::optional<unsigned> NumExpansions,
                                           bool ExpectParameterPack);
 
   /// Transform the body of a lambda-expression.
   StmtResult TransformLambdaBody(LambdaExpr *E, Stmt *Body);
   /// Alternative implementation of TransformLambdaBody that skips transforming
   /// the body.
   StmtResult SkipLambdaBody(LambdaExpr *E, Stmt *Body);
 
   QualType TransformReferenceType(TypeLocBuilder &TLB, ReferenceTypeLoc TL);
 
   StmtResult TransformCompoundStmt(CompoundStmt *S, bool IsStmtExpr);
   ExprResult TransformCXXNamedCastExpr(CXXNamedCastExpr *E);
 
   TemplateParameterList *TransformTemplateParameterList(
         TemplateParameterList *TPL) {
     return TPL;
   }
 
   ExprResult TransformAddressOfOperand(Expr *E);
 
   ExprResult TransformDependentScopeDeclRefExpr(DependentScopeDeclRefExpr *E,
                                                 bool IsAddressOfOperand,
                                                 TypeSourceInfo **RecoveryTSI);
 
   ExprResult TransformParenDependentScopeDeclRefExpr(
       ParenExpr *PE, DependentScopeDeclRefExpr *DRE, bool IsAddressOfOperand,
       TypeSourceInfo **RecoveryTSI);
 
   StmtResult TransformOMPExecutableDirective(OMPExecutableDirective *S);
 
 // FIXME: We use LLVM_ATTRIBUTE_NOINLINE because inlining causes a ridiculous
 // amount of stack usage with clang.
 #define STMT(Node, Parent)                        \
   LLVM_ATTRIBUTE_NOINLINE \
   StmtResult Transform##Node(Node *S);
 #define VALUESTMT(Node, Parent)                   \
   LLVM_ATTRIBUTE_NOINLINE \
   StmtResult Transform##Node(Node *S, StmtDiscardKind SDK);
 #define EXPR(Node, Parent)                        \
   LLVM_ATTRIBUTE_NOINLINE \
   ExprResult Transform##Node(Node *E);
 #define ABSTRACT_STMT(Stmt)
 #include "clang/AST/StmtNodes.inc"
 
 #define GEN_CLANG_CLAUSE_CLASS
 #define CLAUSE_CLASS(Enum, Str, Class)                                         \
   LLVM_ATTRIBUTE_NOINLINE                                                      \
   OMPClause *Transform##Class(Class *S);
 #include "llvm/Frontend/OpenMP/OMP.inc"
 
   /// Build a new qualified type given its unqualified type and type location.
   ///
   /// By default, this routine adds type qualifiers only to types that can
   /// have qualifiers, and silently suppresses those qualifiers that are not
   /// permitted. Subclasses may override this routine to provide different
   /// behavior.
   QualType RebuildQualifiedType(QualType T, QualifiedTypeLoc TL);
 
   /// Build a new pointer type given its pointee type.
   ///
   /// By default, performs semantic analysis when building the pointer type.
   /// Subclasses may override this routine to provide different behavior.
   QualType RebuildPointerType(QualType PointeeType, SourceLocation Sigil);
 
   /// Build a new block pointer type given its pointee type.
   ///
   /// By default, performs semantic analysis when building the block pointer
   /// type. Subclasses may override this routine to provide different behavior.
   QualType RebuildBlockPointerType(QualType PointeeType, SourceLocation Sigil);
 
   /// Build a new reference type given the type it references.
   ///
   /// By default, performs semantic analysis when building the
   /// reference type. Subclasses may override this routine to provide
   /// different behavior.
   ///
   /// \param LValue whether the type was written with an lvalue sigil
   /// or an rvalue sigil.
   QualType RebuildReferenceType(QualType ReferentType,
                                 bool LValue,
                                 SourceLocation Sigil);
 
   /// Build a new member pointer type given the pointee type and the
   /// class type it refers into.
   ///
   /// By default, performs semantic analysis when building the member pointer
   /// type. Subclasses may override this routine to provide different behavior.
   QualType RebuildMemberPointerType(QualType PointeeType, QualType ClassType,
                                     SourceLocation Sigil);
 
   QualType RebuildObjCTypeParamType(const ObjCTypeParamDecl *Decl,
                                     SourceLocation ProtocolLAngleLoc,
                                     ArrayRef<ObjCProtocolDecl *> Protocols,
                                     ArrayRef<SourceLocation> ProtocolLocs,
                                     SourceLocation ProtocolRAngleLoc);
 
   /// Build an Objective-C object type.
   ///
   /// By default, performs semantic analysis when building the object type.
   /// Subclasses may override this routine to provide different behavior.
   QualType RebuildObjCObjectType(QualType BaseType,
                                  SourceLocation Loc,
                                  SourceLocation TypeArgsLAngleLoc,
                                  ArrayRef<TypeSourceInfo *> TypeArgs,
                                  SourceLocation TypeArgsRAngleLoc,
                                  SourceLocation ProtocolLAngleLoc,
                                  ArrayRef<ObjCProtocolDecl *> Protocols,
                                  ArrayRef<SourceLocation> ProtocolLocs,
                                  SourceLocation ProtocolRAngleLoc);
 
   /// Build a new Objective-C object pointer type given the pointee type.
   ///
   /// By default, directly builds the pointer type, with no additional semantic
   /// analysis.
   QualType RebuildObjCObjectPointerType(QualType PointeeType,
                                         SourceLocation Star);
 
   /// Build a new array type given the element type, size
   /// modifier, size of the array (if known), size expression, and index type
   /// qualifiers.
   ///
   /// By default, performs semantic analysis when building the array type.
   /// Subclasses may override this routine to provide different behavior.
   /// Also by default, all of the other Rebuild*Array
   QualType RebuildArrayType(QualType ElementType,
                             ArrayType::ArraySizeModifier SizeMod,
                             const llvm::APInt *Size,
                             Expr *SizeExpr,
                             unsigned IndexTypeQuals,
                             SourceRange BracketsRange);
 
   /// Build a new constant array type given the element type, size
   /// modifier, (known) size of the array, and index type qualifiers.
   ///
   /// By default, performs semantic analysis when building the array type.
   /// Subclasses may override this routine to provide different behavior.
   QualType RebuildConstantArrayType(QualType ElementType,
                                     ArrayType::ArraySizeModifier SizeMod,
                                     const llvm::APInt &Size,
                                     Expr *SizeExpr,
                                     unsigned IndexTypeQuals,
                                     SourceRange BracketsRange);
 
   /// Build a new incomplete array type given the element type, size
   /// modifier, and index type qualifiers.
   ///
   /// By default, performs semantic analysis when building the array type.
   /// Subclasses may override this routine to provide different behavior.
   QualType RebuildIncompleteArrayType(QualType ElementType,
                                       ArrayType::ArraySizeModifier SizeMod,
                                       unsigned IndexTypeQuals,
                                       SourceRange BracketsRange);
 
   /// Build a new variable-length array type given the element type,
   /// size modifier, size expression, and index type qualifiers.
   ///
   /// By default, performs semantic analysis when building the array type.
   /// Subclasses may override this routine to provide different behavior.
   QualType RebuildVariableArrayType(QualType ElementType,
                                     ArrayType::ArraySizeModifier SizeMod,
                                     Expr *SizeExpr,
                                     unsigned IndexTypeQuals,
                                     SourceRange BracketsRange);
 
   /// Build a new dependent-sized array type given the element type,
   /// size modifier, size expression, and index type qualifiers.
   ///
   /// By default, performs semantic analysis when building the array type.
   /// Subclasses may override this routine to provide different behavior.
   QualType RebuildDependentSizedArrayType(QualType ElementType,
                                           ArrayType::ArraySizeModifier SizeMod,
                                           Expr *SizeExpr,
                                           unsigned IndexTypeQuals,
                                           SourceRange BracketsRange);
 
   /// Build a new vector type given the element type and
   /// number of elements.
   ///
   /// By default, performs semantic analysis when building the vector type.
   /// Subclasses may override this routine to provide different behavior.
   QualType RebuildVectorType(QualType ElementType, unsigned NumElements,
                              VectorType::VectorKind VecKind);
 
   /// Build a new potentially dependently-sized extended vector type
   /// given the element type and number of elements.
   ///
   /// By default, performs semantic analysis when building the vector type.
   /// Subclasses may override this routine to provide different behavior.
   QualType RebuildDependentVectorType(QualType ElementType, Expr *SizeExpr,
                                            SourceLocation AttributeLoc,
                                            VectorType::VectorKind);
 
   /// Build a new extended vector type given the element type and
   /// number of elements.
   ///
   /// By default, performs semantic analysis when building the vector type.
   /// Subclasses may override this routine to provide different behavior.
   QualType RebuildExtVectorType(QualType ElementType, unsigned NumElements,
                                 SourceLocation AttributeLoc);
 
   /// Build a new potentially dependently-sized extended vector type
   /// given the element type and number of elements.
   ///
   /// By default, performs semantic analysis when building the vector type.
   /// Subclasses may override this routine to provide different behavior.
   QualType RebuildDependentSizedExtVectorType(QualType ElementType,
                                               Expr *SizeExpr,
                                               SourceLocation AttributeLoc);
 
   /// Build a new matrix type given the element type and dimensions.
   QualType RebuildConstantMatrixType(QualType ElementType, unsigned NumRows,
                                      unsigned NumColumns);
 
   /// Build a new matrix type given the type and dependently-defined
   /// dimensions.
   QualType RebuildDependentSizedMatrixType(QualType ElementType, Expr *RowExpr,
                                            Expr *ColumnExpr,
                                            SourceLocation AttributeLoc);
 
   /// Build a new DependentAddressSpaceType or return the pointee
   /// type variable with the correct address space (retrieved from
   /// AddrSpaceExpr) applied to it. The former will be returned in cases
   /// where the address space remains dependent.
   ///
   /// By default, performs semantic analysis when building the type with address
   /// space applied. Subclasses may override this routine to provide different
   /// behavior.
   QualType RebuildDependentAddressSpaceType(QualType PointeeType,
                                             Expr *AddrSpaceExpr,
                                             SourceLocation AttributeLoc);
 
   /// Build a new function type.
   ///
   /// By default, performs semantic analysis when building the function type.
   /// Subclasses may override this routine to provide different behavior.
   QualType RebuildFunctionProtoType(QualType T,
                                     MutableArrayRef<QualType> ParamTypes,
                                     const FunctionProtoType::ExtProtoInfo &EPI);
 
   /// Build a new unprototyped function type.
   QualType RebuildFunctionNoProtoType(QualType ResultType);
 
   /// Rebuild an unresolved typename type, given the decl that
   /// the UnresolvedUsingTypenameDecl was transformed to.
   QualType RebuildUnresolvedUsingType(SourceLocation NameLoc, Decl *D);
 
   /// Build a new type found via an alias.
   QualType RebuildUsingType(UsingShadowDecl *Found, QualType Underlying) {
     return SemaRef.Context.getUsingType(Found, Underlying);
   }
 
   /// Build a new typedef type.
   QualType RebuildTypedefType(TypedefNameDecl *Typedef) {
     return SemaRef.Context.getTypeDeclType(Typedef);
   }
 
   /// Build a new MacroDefined type.
   QualType RebuildMacroQualifiedType(QualType T,
                                      const IdentifierInfo *MacroII) {
     return SemaRef.Context.getMacroQualifiedType(T, MacroII);
   }
 
   /// Build a new class/struct/union type.
   QualType RebuildRecordType(RecordDecl *Record) {
     return SemaRef.Context.getTypeDeclType(Record);
   }
 
   /// Build a new Enum type.
   QualType RebuildEnumType(EnumDecl *Enum) {
     return SemaRef.Context.getTypeDeclType(Enum);
   }
 
   /// Build a new typeof(expr) type.
   ///
   /// By default, performs semantic analysis when building the typeof type.
   /// Subclasses may override this routine to provide different behavior.
   QualType RebuildTypeOfExprType(Expr *Underlying, SourceLocation Loc,
                                  TypeOfKind Kind);
 
   /// Build a new typeof(type) type.
   ///
   /// By default, builds a new TypeOfType with the given underlying type.
   QualType RebuildTypeOfType(QualType Underlying, TypeOfKind Kind);
 
   /// Build a new unary transform type.
   QualType RebuildUnaryTransformType(QualType BaseType,
                                      UnaryTransformType::UTTKind UKind,
                                      SourceLocation Loc);
 
   /// Build a new C++11 decltype type.
   ///
   /// By default, performs semantic analysis when building the decltype type.
   /// Subclasses may override this routine to provide different behavior.
   QualType RebuildDecltypeType(Expr *Underlying, SourceLocation Loc);
 
   /// Build a new C++11 auto type.
   ///
   /// By default, builds a new AutoType with the given deduced type.
   QualType RebuildAutoType(QualType Deduced, AutoTypeKeyword Keyword,
                            ConceptDecl *TypeConstraintConcept,
                            ArrayRef<TemplateArgument> TypeConstraintArgs) {
     // Note, IsDependent is always false here: we implicitly convert an 'auto'
     // which has been deduced to a dependent type into an undeduced 'auto', so
     // that we'll retry deduction after the transformation.
     return SemaRef.Context.getAutoType(Deduced, Keyword,
                                        /*IsDependent*/ false, /*IsPack=*/false,
                                        TypeConstraintConcept,
                                        TypeConstraintArgs);
   }
 
   /// By default, builds a new DeducedTemplateSpecializationType with the given
   /// deduced type.
   QualType RebuildDeducedTemplateSpecializationType(TemplateName Template,
       QualType Deduced) {
     return SemaRef.Context.getDeducedTemplateSpecializationType(
         Template, Deduced, /*IsDependent*/ false);
   }
 
   /// Build a new template specialization type.
   ///
   /// By default, performs semantic analysis when building the template
   /// specialization type. Subclasses may override this routine to provide
   /// different behavior.
   QualType RebuildTemplateSpecializationType(TemplateName Template,
                                              SourceLocation TemplateLoc,
                                              TemplateArgumentListInfo &Args);
 
   /// Build a new parenthesized type.
   ///
   /// By default, builds a new ParenType type from the inner type.
   /// Subclasses may override this routine to provide different behavior.
   QualType RebuildParenType(QualType InnerType) {
     return SemaRef.BuildParenType(InnerType);
   }
 
   /// Build a new qualified name type.
   ///
   /// By default, builds a new ElaboratedType type from the keyword,
   /// the nested-name-specifier and the named type.
   /// Subclasses may override this routine to provide different behavior.
   QualType RebuildElaboratedType(SourceLocation KeywordLoc,
                                  ElaboratedTypeKeyword Keyword,
                                  NestedNameSpecifierLoc QualifierLoc,
                                  QualType Named) {
     return SemaRef.Context.getElaboratedType(Keyword,
                                          QualifierLoc.getNestedNameSpecifier(),
                                              Named);
   }
 
   /// Build a new typename type that refers to a template-id.
   ///
   /// By default, builds a new DependentNameType type from the
   /// nested-name-specifier and the given type. Subclasses may override
   /// this routine to provide different behavior.
   QualType RebuildDependentTemplateSpecializationType(
                                           ElaboratedTypeKeyword Keyword,
                                           NestedNameSpecifierLoc QualifierLoc,
                                           SourceLocation TemplateKWLoc,
                                           const IdentifierInfo *Name,
                                           SourceLocation NameLoc,
                                           TemplateArgumentListInfo &Args,
                                           bool AllowInjectedClassName) {
     // Rebuild the template name.
     // TODO: avoid TemplateName abstraction
     CXXScopeSpec SS;
     SS.Adopt(QualifierLoc);
     TemplateName InstName = getDerived().RebuildTemplateName(
         SS, TemplateKWLoc, *Name, NameLoc, QualType(), nullptr,
         AllowInjectedClassName);
 
     if (InstName.isNull())
       return QualType();
 
     // If it's still dependent, make a dependent specialization.
     if (InstName.getAsDependentTemplateName())
       return SemaRef.Context.getDependentTemplateSpecializationType(
           Keyword, QualifierLoc.getNestedNameSpecifier(), Name,
           Args.arguments());
 
     // Otherwise, make an elaborated type wrapping a non-dependent
     // specialization.
     QualType T =
         getDerived().RebuildTemplateSpecializationType(InstName, NameLoc, Args);
     if (T.isNull())
       return QualType();
     return SemaRef.Context.getElaboratedType(
         Keyword, QualifierLoc.getNestedNameSpecifier(), T);
   }
 
   /// Build a new typename type that refers to an identifier.
   ///
   /// By default, performs semantic analysis when building the typename type
   /// (or elaborated type). Subclasses may override this routine to provide
   /// different behavior.
   QualType RebuildDependentNameType(ElaboratedTypeKeyword Keyword,
                                     SourceLocation KeywordLoc,
                                     NestedNameSpecifierLoc QualifierLoc,
                                     const IdentifierInfo *Id,
                                     SourceLocation IdLoc,
                                     bool DeducedTSTContext) {
     CXXScopeSpec SS;
     SS.Adopt(QualifierLoc);
 
     if (QualifierLoc.getNestedNameSpecifier()->isDependent()) {
       // If the name is still dependent, just build a new dependent name type.
       if (!SemaRef.computeDeclContext(SS))
         return SemaRef.Context.getDependentNameType(Keyword,
                                           QualifierLoc.getNestedNameSpecifier(),
                                                     Id);
     }
 
     if (Keyword == ETK_None || Keyword == ETK_Typename) {
       return SemaRef.CheckTypenameType(Keyword, KeywordLoc, QualifierLoc,
                                        *Id, IdLoc, DeducedTSTContext);
     }
 
     TagTypeKind Kind = TypeWithKeyword::getTagTypeKindForKeyword(Keyword);
 
     // We had a dependent elaborated-type-specifier that has been transformed
     // into a non-dependent elaborated-type-specifier. Find the tag we're
     // referring to.
     LookupResult Result(SemaRef, Id, IdLoc, Sema::LookupTagName);
     DeclContext *DC = SemaRef.computeDeclContext(SS, false);
     if (!DC)
       return QualType();
 
     if (SemaRef.RequireCompleteDeclContext(SS, DC))
       return QualType();
 
     TagDecl *Tag = nullptr;
     SemaRef.LookupQualifiedName(Result, DC);
     switch (Result.getResultKind()) {
       case LookupResult::NotFound:
       case LookupResult::NotFoundInCurrentInstantiation:
         break;
 
       case LookupResult::Found:
         Tag = Result.getAsSingle<TagDecl>();
         break;
 
       case LookupResult::FoundOverloaded:
       case LookupResult::FoundUnresolvedValue:
         llvm_unreachable("Tag lookup cannot find non-tags");
 
       case LookupResult::Ambiguous:
         // Let the LookupResult structure handle ambiguities.
         return QualType();
     }
 
     if (!Tag) {
       // Check where the name exists but isn't a tag type and use that to emit
       // better diagnostics.
       LookupResult Result(SemaRef, Id, IdLoc, Sema::LookupTagName);
       SemaRef.LookupQualifiedName(Result, DC);
       switch (Result.getResultKind()) {
         case LookupResult::Found:
         case LookupResult::FoundOverloaded:
         case LookupResult::FoundUnresolvedValue: {
           NamedDecl *SomeDecl = Result.getRepresentativeDecl();
           Sema::NonTagKind NTK = SemaRef.getNonTagTypeDeclKind(SomeDecl, Kind);
           SemaRef.Diag(IdLoc, diag::err_tag_reference_non_tag) << SomeDecl
                                                                << NTK << Kind;
           SemaRef.Diag(SomeDecl->getLocation(), diag::note_declared_at);
           break;
         }
         default:
           SemaRef.Diag(IdLoc, diag::err_not_tag_in_scope)
               << Kind << Id << DC << QualifierLoc.getSourceRange();
           break;
       }
       return QualType();
     }
 
     if (!SemaRef.isAcceptableTagRedeclaration(Tag, Kind, /*isDefinition*/false,
                                               IdLoc, Id)) {
       SemaRef.Diag(KeywordLoc, diag::err_use_with_wrong_tag) << Id;
       SemaRef.Diag(Tag->getLocation(), diag::note_previous_use);
       return QualType();
     }
 
     // Build the elaborated-type-specifier type.
     QualType T = SemaRef.Context.getTypeDeclType(Tag);
     return SemaRef.Context.getElaboratedType(Keyword,
                                          QualifierLoc.getNestedNameSpecifier(),
                                              T);
   }
 
   /// Build a new pack expansion type.
   ///
   /// By default, builds a new PackExpansionType type from the given pattern.
   /// Subclasses may override this routine to provide different behavior.
   QualType RebuildPackExpansionType(QualType Pattern, SourceRange PatternRange,
                                     SourceLocation EllipsisLoc,
                                     std::optional<unsigned> NumExpansions) {
     return getSema().CheckPackExpansion(Pattern, PatternRange, EllipsisLoc,
                                         NumExpansions);
   }
 
   /// Build a new atomic type given its value type.
   ///
   /// By default, performs semantic analysis when building the atomic type.
   /// Subclasses may override this routine to provide different behavior.
   QualType RebuildAtomicType(QualType ValueType, SourceLocation KWLoc);
 
   /// Build a new pipe type given its value type.
   QualType RebuildPipeType(QualType ValueType, SourceLocation KWLoc,
                            bool isReadPipe);
 
   /// Build a bit-precise int given its value type.
   QualType RebuildBitIntType(bool IsUnsigned, unsigned NumBits,
                              SourceLocation Loc);
 
   /// Build a dependent bit-precise int given its value type.
   QualType RebuildDependentBitIntType(bool IsUnsigned, Expr *NumBitsExpr,
                                       SourceLocation Loc);
 
   /// Build a new template name given a nested name specifier, a flag
   /// indicating whether the "template" keyword was provided, and the template
   /// that the template name refers to.
   ///
   /// By default, builds the new template name directly. Subclasses may override
   /// this routine to provide different behavior.
   TemplateName RebuildTemplateName(CXXScopeSpec &SS,
                                    bool TemplateKW,
                                    TemplateDecl *Template);
 
   /// Build a new template name given a nested name specifier and the
   /// name that is referred to as a template.
   ///
   /// By default, performs semantic analysis to determine whether the name can
   /// be resolved to a specific template, then builds the appropriate kind of
   /// template name. Subclasses may override this routine to provide different
   /// behavior.
   TemplateName RebuildTemplateName(CXXScopeSpec &SS,
                                    SourceLocation TemplateKWLoc,
                                    const IdentifierInfo &Name,
                                    SourceLocation NameLoc, QualType ObjectType,
                                    NamedDecl *FirstQualifierInScope,
                                    bool AllowInjectedClassName);
 
   /// Build a new template name given a nested name specifier and the
   /// overloaded operator name that is referred to as a template.
   ///
   /// By default, performs semantic analysis to determine whether the name can
   /// be resolved to a specific template, then builds the appropriate kind of
   /// template name. Subclasses may override this routine to provide different
   /// behavior.
   TemplateName RebuildTemplateName(CXXScopeSpec &SS,
                                    SourceLocation TemplateKWLoc,
                                    OverloadedOperatorKind Operator,
                                    SourceLocation NameLoc, QualType ObjectType,
                                    bool AllowInjectedClassName);
 
   /// Build a new template name given a template template parameter pack
   /// and the
   ///
   /// By default, performs semantic analysis to determine whether the name can
   /// be resolved to a specific template, then builds the appropriate kind of
   /// template name. Subclasses may override this routine to provide different
   /// behavior.
   TemplateName RebuildTemplateName(const TemplateArgument &ArgPack,
                                    Decl *AssociatedDecl, unsigned Index,
                                    bool Final) {
     return getSema().Context.getSubstTemplateTemplateParmPack(
         ArgPack, AssociatedDecl, Index, Final);
   }
 
   /// Build a new compound statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildCompoundStmt(SourceLocation LBraceLoc,
                                        MultiStmtArg Statements,
                                        SourceLocation RBraceLoc,
                                        bool IsStmtExpr) {
     return getSema().ActOnCompoundStmt(LBraceLoc, RBraceLoc, Statements,
                                        IsStmtExpr);
   }
 
   /// Build a new case statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildCaseStmt(SourceLocation CaseLoc,
                                    Expr *LHS,
                                    SourceLocation EllipsisLoc,
                                    Expr *RHS,
                                    SourceLocation ColonLoc) {
     return getSema().ActOnCaseStmt(CaseLoc, LHS, EllipsisLoc, RHS,
                                    ColonLoc);
   }
 
   /// Attach the body to a new case statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildCaseStmtBody(Stmt *S, Stmt *Body) {
     getSema().ActOnCaseStmtBody(S, Body);
     return S;
   }
 
   /// Build a new default statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildDefaultStmt(SourceLocation DefaultLoc,
                                       SourceLocation ColonLoc,
                                       Stmt *SubStmt) {
     return getSema().ActOnDefaultStmt(DefaultLoc, ColonLoc, SubStmt,
                                       /*CurScope=*/nullptr);
   }
 
   /// Build a new label statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildLabelStmt(SourceLocation IdentLoc, LabelDecl *L,
                               SourceLocation ColonLoc, Stmt *SubStmt) {
     return SemaRef.ActOnLabelStmt(IdentLoc, L, ColonLoc, SubStmt);
   }
 
   /// Build a new attributed statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildAttributedStmt(SourceLocation AttrLoc,
                                    ArrayRef<const Attr *> Attrs,
                                    Stmt *SubStmt) {
     return SemaRef.BuildAttributedStmt(AttrLoc, Attrs, SubStmt);
   }
 
   /// Build a new "if" statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildIfStmt(SourceLocation IfLoc, IfStatementKind Kind,
                            SourceLocation LParenLoc, Sema::ConditionResult Cond,
                            SourceLocation RParenLoc, Stmt *Init, Stmt *Then,
                            SourceLocation ElseLoc, Stmt *Else) {
     return getSema().ActOnIfStmt(IfLoc, Kind, LParenLoc, Init, Cond, RParenLoc,
                                  Then, ElseLoc, Else);
   }
 
   /// Start building a new switch statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildSwitchStmtStart(SourceLocation SwitchLoc,
                                     SourceLocation LParenLoc, Stmt *Init,
                                     Sema::ConditionResult Cond,
                                     SourceLocation RParenLoc) {
     return getSema().ActOnStartOfSwitchStmt(SwitchLoc, LParenLoc, Init, Cond,
                                             RParenLoc);
   }
 
   /// Attach the body to the switch statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildSwitchStmtBody(SourceLocation SwitchLoc,
                                    Stmt *Switch, Stmt *Body) {
     return getSema().ActOnFinishSwitchStmt(SwitchLoc, Switch, Body);
   }
 
   /// Build a new while statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildWhileStmt(SourceLocation WhileLoc, SourceLocation LParenLoc,
                               Sema::ConditionResult Cond,
                               SourceLocation RParenLoc, Stmt *Body) {
     return getSema().ActOnWhileStmt(WhileLoc, LParenLoc, Cond, RParenLoc, Body);
   }
 
   /// Build a new do-while statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildDoStmt(SourceLocation DoLoc, Stmt *Body,
                            SourceLocation WhileLoc, SourceLocation LParenLoc,
                            Expr *Cond, SourceLocation RParenLoc) {
     return getSema().ActOnDoStmt(DoLoc, Body, WhileLoc, LParenLoc,
                                  Cond, RParenLoc);
   }
 
   /// Build a new for statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildForStmt(SourceLocation ForLoc, SourceLocation LParenLoc,
                             Stmt *Init, Sema::ConditionResult Cond,
                             Sema::FullExprArg Inc, SourceLocation RParenLoc,
                             Stmt *Body) {
     return getSema().ActOnForStmt(ForLoc, LParenLoc, Init, Cond,
                                   Inc, RParenLoc, Body);
   }
 
   /// Build a new goto statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildGotoStmt(SourceLocation GotoLoc, SourceLocation LabelLoc,
                              LabelDecl *Label) {
     return getSema().ActOnGotoStmt(GotoLoc, LabelLoc, Label);
   }
 
   /// Build a new indirect goto statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildIndirectGotoStmt(SourceLocation GotoLoc,
                                      SourceLocation StarLoc,
                                      Expr *Target) {
     return getSema().ActOnIndirectGotoStmt(GotoLoc, StarLoc, Target);
   }
 
   /// Build a new return statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildReturnStmt(SourceLocation ReturnLoc, Expr *Result) {
     return getSema().BuildReturnStmt(ReturnLoc, Result);
   }
 
   /// Build a new declaration statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildDeclStmt(MutableArrayRef<Decl *> Decls,
                              SourceLocation StartLoc, SourceLocation EndLoc) {
     Sema::DeclGroupPtrTy DG = getSema().BuildDeclaratorGroup(Decls);
     return getSema().ActOnDeclStmt(DG, StartLoc, EndLoc);
   }
 
   /// Build a new inline asm statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildGCCAsmStmt(SourceLocation AsmLoc, bool IsSimple,
                                bool IsVolatile, unsigned NumOutputs,
                                unsigned NumInputs, IdentifierInfo **Names,
                                MultiExprArg Constraints, MultiExprArg Exprs,
                                Expr *AsmString, MultiExprArg Clobbers,
                                unsigned NumLabels,
                                SourceLocation RParenLoc) {
     return getSema().ActOnGCCAsmStmt(AsmLoc, IsSimple, IsVolatile, NumOutputs,
                                      NumInputs, Names, Constraints, Exprs,
                                      AsmString, Clobbers, NumLabels, RParenLoc);
   }
 
   /// Build a new MS style inline asm statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildMSAsmStmt(SourceLocation AsmLoc, SourceLocation LBraceLoc,
                               ArrayRef<Token> AsmToks,
                               StringRef AsmString,
                               unsigned NumOutputs, unsigned NumInputs,
                               ArrayRef<StringRef> Constraints,
                               ArrayRef<StringRef> Clobbers,
                               ArrayRef<Expr*> Exprs,
                               SourceLocation EndLoc) {
     return getSema().ActOnMSAsmStmt(AsmLoc, LBraceLoc, AsmToks, AsmString,
                                     NumOutputs, NumInputs,
                                     Constraints, Clobbers, Exprs, EndLoc);
   }
 
   /// Build a new co_return statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildCoreturnStmt(SourceLocation CoreturnLoc, Expr *Result,
                                  bool IsImplicit) {
     return getSema().BuildCoreturnStmt(CoreturnLoc, Result, IsImplicit);
   }
 
   /// Build a new co_await expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildCoawaitExpr(SourceLocation CoawaitLoc, Expr *Operand,
                                 UnresolvedLookupExpr *OpCoawaitLookup,
                                 bool IsImplicit) {
     // This function rebuilds a coawait-expr given its operator.
     // For an explicit coawait-expr, the rebuild involves the full set
     // of transformations performed by BuildUnresolvedCoawaitExpr(),
     // including calling await_transform().
     // For an implicit coawait-expr, we need to rebuild the "operator
     // coawait" but not await_transform(), so use BuildResolvedCoawaitExpr().
     // This mirrors how the implicit CoawaitExpr is originally created
     // in Sema::ActOnCoroutineBodyStart().
     if (IsImplicit) {
       ExprResult Suspend = getSema().BuildOperatorCoawaitCall(
           CoawaitLoc, Operand, OpCoawaitLookup);
       if (Suspend.isInvalid())
         return ExprError();
       return getSema().BuildResolvedCoawaitExpr(CoawaitLoc, Operand,
                                                 Suspend.get(), true);
     }
 
     return getSema().BuildUnresolvedCoawaitExpr(CoawaitLoc, Operand,
                                                 OpCoawaitLookup);
   }
 
   /// Build a new co_await expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildDependentCoawaitExpr(SourceLocation CoawaitLoc,
                                          Expr *Result,
                                          UnresolvedLookupExpr *Lookup) {
     return getSema().BuildUnresolvedCoawaitExpr(CoawaitLoc, Result, Lookup);
   }
 
   /// Build a new co_yield expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildCoyieldExpr(SourceLocation CoyieldLoc, Expr *Result) {
     return getSema().BuildCoyieldExpr(CoyieldLoc, Result);
   }
 
   StmtResult RebuildCoroutineBodyStmt(CoroutineBodyStmt::CtorArgs Args) {
     return getSema().BuildCoroutineBodyStmt(Args);
   }
 
   /// Build a new Objective-C \@try statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildObjCAtTryStmt(SourceLocation AtLoc,
                                         Stmt *TryBody,
                                         MultiStmtArg CatchStmts,
                                         Stmt *Finally) {
     return getSema().ActOnObjCAtTryStmt(AtLoc, TryBody, CatchStmts,
                                         Finally);
   }
 
   /// Rebuild an Objective-C exception declaration.
   ///
   /// By default, performs semantic analysis to build the new declaration.
   /// Subclasses may override this routine to provide different behavior.
   VarDecl *RebuildObjCExceptionDecl(VarDecl *ExceptionDecl,
                                     TypeSourceInfo *TInfo, QualType T) {
     return getSema().BuildObjCExceptionDecl(TInfo, T,
                                             ExceptionDecl->getInnerLocStart(),
                                             ExceptionDecl->getLocation(),
                                             ExceptionDecl->getIdentifier());
   }
 
   /// Build a new Objective-C \@catch statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildObjCAtCatchStmt(SourceLocation AtLoc,
                                           SourceLocation RParenLoc,
                                           VarDecl *Var,
                                           Stmt *Body) {
     return getSema().ActOnObjCAtCatchStmt(AtLoc, RParenLoc,
                                           Var, Body);
   }
 
   /// Build a new Objective-C \@finally statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildObjCAtFinallyStmt(SourceLocation AtLoc,
                                             Stmt *Body) {
     return getSema().ActOnObjCAtFinallyStmt(AtLoc, Body);
   }
 
   /// Build a new Objective-C \@throw statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildObjCAtThrowStmt(SourceLocation AtLoc,
                                           Expr *Operand) {
     return getSema().BuildObjCAtThrowStmt(AtLoc, Operand);
   }
 
   /// Build a new OpenMP Canonical loop.
   ///
   /// Ensures that the outermost loop in @p LoopStmt is wrapped by a
   /// OMPCanonicalLoop.
   StmtResult RebuildOMPCanonicalLoop(Stmt *LoopStmt) {
     return getSema().ActOnOpenMPCanonicalLoop(LoopStmt);
   }
 
   /// Build a new OpenMP executable directive.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildOMPExecutableDirective(OpenMPDirectiveKind Kind,
                                            DeclarationNameInfo DirName,
                                            OpenMPDirectiveKind CancelRegion,
                                            ArrayRef<OMPClause *> Clauses,
                                            Stmt *AStmt, SourceLocation StartLoc,
                                            SourceLocation EndLoc) {
     return getSema().ActOnOpenMPExecutableDirective(
         Kind, DirName, CancelRegion, Clauses, AStmt, StartLoc, EndLoc);
   }
 
   /// Build a new OpenMP 'if' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPIfClause(OpenMPDirectiveKind NameModifier,
                                 Expr *Condition, SourceLocation StartLoc,
                                 SourceLocation LParenLoc,
                                 SourceLocation NameModifierLoc,
                                 SourceLocation ColonLoc,
                                 SourceLocation EndLoc) {
     return getSema().ActOnOpenMPIfClause(NameModifier, Condition, StartLoc,
                                          LParenLoc, NameModifierLoc, ColonLoc,
                                          EndLoc);
   }
 
   /// Build a new OpenMP 'final' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPFinalClause(Expr *Condition, SourceLocation StartLoc,
                                    SourceLocation LParenLoc,
                                    SourceLocation EndLoc) {
     return getSema().ActOnOpenMPFinalClause(Condition, StartLoc, LParenLoc,
                                             EndLoc);
   }
 
   /// Build a new OpenMP 'num_threads' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPNumThreadsClause(Expr *NumThreads,
                                         SourceLocation StartLoc,
                                         SourceLocation LParenLoc,
                                         SourceLocation EndLoc) {
     return getSema().ActOnOpenMPNumThreadsClause(NumThreads, StartLoc,
                                                  LParenLoc, EndLoc);
   }
 
   /// Build a new OpenMP 'safelen' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPSafelenClause(Expr *Len, SourceLocation StartLoc,
                                      SourceLocation LParenLoc,
                                      SourceLocation EndLoc) {
     return getSema().ActOnOpenMPSafelenClause(Len, StartLoc, LParenLoc, EndLoc);
   }
 
   /// Build a new OpenMP 'simdlen' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPSimdlenClause(Expr *Len, SourceLocation StartLoc,
                                      SourceLocation LParenLoc,
                                      SourceLocation EndLoc) {
     return getSema().ActOnOpenMPSimdlenClause(Len, StartLoc, LParenLoc, EndLoc);
   }
 
   OMPClause *RebuildOMPSizesClause(ArrayRef<Expr *> Sizes,
                                    SourceLocation StartLoc,
                                    SourceLocation LParenLoc,
                                    SourceLocation EndLoc) {
     return getSema().ActOnOpenMPSizesClause(Sizes, StartLoc, LParenLoc, EndLoc);
   }
 
   /// Build a new OpenMP 'full' clause.
   OMPClause *RebuildOMPFullClause(SourceLocation StartLoc,
                                   SourceLocation EndLoc) {
     return getSema().ActOnOpenMPFullClause(StartLoc, EndLoc);
   }
 
   /// Build a new OpenMP 'partial' clause.
   OMPClause *RebuildOMPPartialClause(Expr *Factor, SourceLocation StartLoc,
                                      SourceLocation LParenLoc,
                                      SourceLocation EndLoc) {
     return getSema().ActOnOpenMPPartialClause(Factor, StartLoc, LParenLoc,
                                               EndLoc);
   }
 
   /// Build a new OpenMP 'allocator' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPAllocatorClause(Expr *A, SourceLocation StartLoc,
                                        SourceLocation LParenLoc,
                                        SourceLocation EndLoc) {
     return getSema().ActOnOpenMPAllocatorClause(A, StartLoc, LParenLoc, EndLoc);
   }
 
   /// Build a new OpenMP 'collapse' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPCollapseClause(Expr *Num, SourceLocation StartLoc,
                                       SourceLocation LParenLoc,
                                       SourceLocation EndLoc) {
     return getSema().ActOnOpenMPCollapseClause(Num, StartLoc, LParenLoc,
                                                EndLoc);
   }
 
   /// Build a new OpenMP 'default' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPDefaultClause(DefaultKind Kind, SourceLocation KindKwLoc,
                                      SourceLocation StartLoc,
                                      SourceLocation LParenLoc,
                                      SourceLocation EndLoc) {
     return getSema().ActOnOpenMPDefaultClause(Kind, KindKwLoc,
                                               StartLoc, LParenLoc, EndLoc);
   }
 
   /// Build a new OpenMP 'proc_bind' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPProcBindClause(ProcBindKind Kind,
                                       SourceLocation KindKwLoc,
                                       SourceLocation StartLoc,
                                       SourceLocation LParenLoc,
                                       SourceLocation EndLoc) {
     return getSema().ActOnOpenMPProcBindClause(Kind, KindKwLoc,
                                                StartLoc, LParenLoc, EndLoc);
   }
 
   /// Build a new OpenMP 'schedule' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPScheduleClause(
       OpenMPScheduleClauseModifier M1, OpenMPScheduleClauseModifier M2,
       OpenMPScheduleClauseKind Kind, Expr *ChunkSize, SourceLocation StartLoc,
       SourceLocation LParenLoc, SourceLocation M1Loc, SourceLocation M2Loc,
       SourceLocation KindLoc, SourceLocation CommaLoc, SourceLocation EndLoc) {
     return getSema().ActOnOpenMPScheduleClause(
         M1, M2, Kind, ChunkSize, StartLoc, LParenLoc, M1Loc, M2Loc, KindLoc,
         CommaLoc, EndLoc);
   }
 
   /// Build a new OpenMP 'ordered' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPOrderedClause(SourceLocation StartLoc,
                                      SourceLocation EndLoc,
                                      SourceLocation LParenLoc, Expr *Num) {
     return getSema().ActOnOpenMPOrderedClause(StartLoc, EndLoc, LParenLoc, Num);
   }
 
   /// Build a new OpenMP 'private' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPPrivateClause(ArrayRef<Expr *> VarList,
                                      SourceLocation StartLoc,
                                      SourceLocation LParenLoc,
                                      SourceLocation EndLoc) {
     return getSema().ActOnOpenMPPrivateClause(VarList, StartLoc, LParenLoc,
                                               EndLoc);
   }
 
   /// Build a new OpenMP 'firstprivate' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPFirstprivateClause(ArrayRef<Expr *> VarList,
                                           SourceLocation StartLoc,
                                           SourceLocation LParenLoc,
                                           SourceLocation EndLoc) {
     return getSema().ActOnOpenMPFirstprivateClause(VarList, StartLoc, LParenLoc,
                                                    EndLoc);
   }
 
   /// Build a new OpenMP 'lastprivate' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPLastprivateClause(ArrayRef<Expr *> VarList,
                                          OpenMPLastprivateModifier LPKind,
                                          SourceLocation LPKindLoc,
                                          SourceLocation ColonLoc,
                                          SourceLocation StartLoc,
                                          SourceLocation LParenLoc,
                                          SourceLocation EndLoc) {
     return getSema().ActOnOpenMPLastprivateClause(
         VarList, LPKind, LPKindLoc, ColonLoc, StartLoc, LParenLoc, EndLoc);
   }
 
   /// Build a new OpenMP 'shared' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPSharedClause(ArrayRef<Expr *> VarList,
                                     SourceLocation StartLoc,
                                     SourceLocation LParenLoc,
                                     SourceLocation EndLoc) {
     return getSema().ActOnOpenMPSharedClause(VarList, StartLoc, LParenLoc,
                                              EndLoc);
   }
 
   /// Build a new OpenMP 'reduction' clause.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPReductionClause(
       ArrayRef<Expr *> VarList, OpenMPReductionClauseModifier Modifier,
       SourceLocation StartLoc, SourceLocation LParenLoc,
       SourceLocation ModifierLoc, SourceLocation ColonLoc,
       SourceLocation EndLoc, CXXScopeSpec &ReductionIdScopeSpec,
       const DeclarationNameInfo &ReductionId,
       ArrayRef<Expr *> UnresolvedReductions) {
     return getSema().ActOnOpenMPReductionClause(
         VarList, Modifier, StartLoc, LParenLoc, ModifierLoc, ColonLoc, EndLoc,
         ReductionIdScopeSpec, ReductionId, UnresolvedReductions);
   }
 
   /// Build a new OpenMP 'task_reduction' clause.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPTaskReductionClause(
       ArrayRef<Expr *> VarList, SourceLocation StartLoc,
       SourceLocation LParenLoc, SourceLocation ColonLoc, SourceLocation EndLoc,
       CXXScopeSpec &ReductionIdScopeSpec,
       const DeclarationNameInfo &ReductionId,
       ArrayRef<Expr *> UnresolvedReductions) {
     return getSema().ActOnOpenMPTaskReductionClause(
         VarList, StartLoc, LParenLoc, ColonLoc, EndLoc, ReductionIdScopeSpec,
         ReductionId, UnresolvedReductions);
   }
 
   /// Build a new OpenMP 'in_reduction' clause.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *
   RebuildOMPInReductionClause(ArrayRef<Expr *> VarList, SourceLocation StartLoc,
                               SourceLocation LParenLoc, SourceLocation ColonLoc,
                               SourceLocation EndLoc,
                               CXXScopeSpec &ReductionIdScopeSpec,
                               const DeclarationNameInfo &ReductionId,
                               ArrayRef<Expr *> UnresolvedReductions) {
     return getSema().ActOnOpenMPInReductionClause(
         VarList, StartLoc, LParenLoc, ColonLoc, EndLoc, ReductionIdScopeSpec,
         ReductionId, UnresolvedReductions);
   }
 
   /// Build a new OpenMP 'linear' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPLinearClause(ArrayRef<Expr *> VarList, Expr *Step,
                                     SourceLocation StartLoc,
                                     SourceLocation LParenLoc,
                                     OpenMPLinearClauseKind Modifier,
                                     SourceLocation ModifierLoc,
                                     SourceLocation ColonLoc,
                                     SourceLocation EndLoc) {
     return getSema().ActOnOpenMPLinearClause(VarList, Step, StartLoc, LParenLoc,
                                              Modifier, ModifierLoc, ColonLoc,
                                              EndLoc);
   }
 
   /// Build a new OpenMP 'aligned' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPAlignedClause(ArrayRef<Expr *> VarList, Expr *Alignment,
                                      SourceLocation StartLoc,
                                      SourceLocation LParenLoc,
                                      SourceLocation ColonLoc,
                                      SourceLocation EndLoc) {
     return getSema().ActOnOpenMPAlignedClause(VarList, Alignment, StartLoc,
                                               LParenLoc, ColonLoc, EndLoc);
   }
 
   /// Build a new OpenMP 'copyin' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPCopyinClause(ArrayRef<Expr *> VarList,
                                     SourceLocation StartLoc,
                                     SourceLocation LParenLoc,
                                     SourceLocation EndLoc) {
     return getSema().ActOnOpenMPCopyinClause(VarList, StartLoc, LParenLoc,
                                              EndLoc);
   }
 
   /// Build a new OpenMP 'copyprivate' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPCopyprivateClause(ArrayRef<Expr *> VarList,
                                          SourceLocation StartLoc,
                                          SourceLocation LParenLoc,
                                          SourceLocation EndLoc) {
     return getSema().ActOnOpenMPCopyprivateClause(VarList, StartLoc, LParenLoc,
                                                   EndLoc);
   }
 
   /// Build a new OpenMP 'flush' pseudo clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPFlushClause(ArrayRef<Expr *> VarList,
                                    SourceLocation StartLoc,
                                    SourceLocation LParenLoc,
                                    SourceLocation EndLoc) {
     return getSema().ActOnOpenMPFlushClause(VarList, StartLoc, LParenLoc,
                                             EndLoc);
   }
 
   /// Build a new OpenMP 'depobj' pseudo clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPDepobjClause(Expr *Depobj, SourceLocation StartLoc,
                                     SourceLocation LParenLoc,
                                     SourceLocation EndLoc) {
     return getSema().ActOnOpenMPDepobjClause(Depobj, StartLoc, LParenLoc,
                                              EndLoc);
   }
 
   /// Build a new OpenMP 'depend' pseudo clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPDependClause(OMPDependClause::DependDataTy Data,
                                     Expr *DepModifier, ArrayRef<Expr *> VarList,
                                     SourceLocation StartLoc,
                                     SourceLocation LParenLoc,
                                     SourceLocation EndLoc) {
     return getSema().ActOnOpenMPDependClause(Data, DepModifier, VarList,
                                              StartLoc, LParenLoc, EndLoc);
   }
 
   /// Build a new OpenMP 'device' clause.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPDeviceClause(OpenMPDeviceClauseModifier Modifier,
                                     Expr *Device, SourceLocation StartLoc,
                                     SourceLocation LParenLoc,
                                     SourceLocation ModifierLoc,
                                     SourceLocation EndLoc) {
     return getSema().ActOnOpenMPDeviceClause(Modifier, Device, StartLoc,
                                              LParenLoc, ModifierLoc, EndLoc);
   }
 
   /// Build a new OpenMP 'map' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPMapClause(
       Expr *IteratorModifier, ArrayRef<OpenMPMapModifierKind> MapTypeModifiers,
       ArrayRef<SourceLocation> MapTypeModifiersLoc,
       CXXScopeSpec MapperIdScopeSpec, DeclarationNameInfo MapperId,
       OpenMPMapClauseKind MapType, bool IsMapTypeImplicit,
       SourceLocation MapLoc, SourceLocation ColonLoc, ArrayRef<Expr *> VarList,
       const OMPVarListLocTy &Locs, ArrayRef<Expr *> UnresolvedMappers) {
     return getSema().ActOnOpenMPMapClause(
         IteratorModifier, MapTypeModifiers, MapTypeModifiersLoc,
         MapperIdScopeSpec, MapperId, MapType, IsMapTypeImplicit, MapLoc,
         ColonLoc, VarList, Locs,
         /*NoDiagnose=*/false, UnresolvedMappers);
   }
 
   /// Build a new OpenMP 'allocate' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPAllocateClause(Expr *Allocate, ArrayRef<Expr *> VarList,
                                       SourceLocation StartLoc,
                                       SourceLocation LParenLoc,
                                       SourceLocation ColonLoc,
                                       SourceLocation EndLoc) {
     return getSema().ActOnOpenMPAllocateClause(Allocate, VarList, StartLoc,
                                                LParenLoc, ColonLoc, EndLoc);
   }
 
   /// Build a new OpenMP 'num_teams' clause.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPNumTeamsClause(Expr *NumTeams, SourceLocation StartLoc,
                                       SourceLocation LParenLoc,
                                       SourceLocation EndLoc) {
     return getSema().ActOnOpenMPNumTeamsClause(NumTeams, StartLoc, LParenLoc,
                                                EndLoc);
   }
 
   /// Build a new OpenMP 'thread_limit' clause.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPThreadLimitClause(Expr *ThreadLimit,
                                          SourceLocation StartLoc,
                                          SourceLocation LParenLoc,
                                          SourceLocation EndLoc) {
     return getSema().ActOnOpenMPThreadLimitClause(ThreadLimit, StartLoc,
                                                   LParenLoc, EndLoc);
   }
 
   /// Build a new OpenMP 'priority' clause.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPPriorityClause(Expr *Priority, SourceLocation StartLoc,
                                       SourceLocation LParenLoc,
                                       SourceLocation EndLoc) {
     return getSema().ActOnOpenMPPriorityClause(Priority, StartLoc, LParenLoc,
                                                EndLoc);
   }
 
   /// Build a new OpenMP 'grainsize' clause.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPGrainsizeClause(OpenMPGrainsizeClauseModifier Modifier,
                                        Expr *Device, SourceLocation StartLoc,
                                        SourceLocation LParenLoc,
                                        SourceLocation ModifierLoc,
                                        SourceLocation EndLoc) {
     return getSema().ActOnOpenMPGrainsizeClause(Modifier, Device, StartLoc,
                                                 LParenLoc, ModifierLoc, EndLoc);
   }
 
   /// Build a new OpenMP 'num_tasks' clause.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPNumTasksClause(OpenMPNumTasksClauseModifier Modifier,
                                       Expr *NumTasks, SourceLocation StartLoc,
                                       SourceLocation LParenLoc,
                                       SourceLocation ModifierLoc,
                                       SourceLocation EndLoc) {
     return getSema().ActOnOpenMPNumTasksClause(Modifier, NumTasks, StartLoc,
                                                LParenLoc, ModifierLoc, EndLoc);
   }
 
   /// Build a new OpenMP 'hint' clause.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPHintClause(Expr *Hint, SourceLocation StartLoc,
                                   SourceLocation LParenLoc,
                                   SourceLocation EndLoc) {
     return getSema().ActOnOpenMPHintClause(Hint, StartLoc, LParenLoc, EndLoc);
   }
 
   /// Build a new OpenMP 'detach' clause.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPDetachClause(Expr *Evt, SourceLocation StartLoc,
                                     SourceLocation LParenLoc,
                                     SourceLocation EndLoc) {
     return getSema().ActOnOpenMPDetachClause(Evt, StartLoc, LParenLoc, EndLoc);
   }
 
   /// Build a new OpenMP 'dist_schedule' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *
   RebuildOMPDistScheduleClause(OpenMPDistScheduleClauseKind Kind,
                                Expr *ChunkSize, SourceLocation StartLoc,
                                SourceLocation LParenLoc, SourceLocation KindLoc,
                                SourceLocation CommaLoc, SourceLocation EndLoc) {
     return getSema().ActOnOpenMPDistScheduleClause(
         Kind, ChunkSize, StartLoc, LParenLoc, KindLoc, CommaLoc, EndLoc);
   }
 
   /// Build a new OpenMP 'to' clause.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *
   RebuildOMPToClause(ArrayRef<OpenMPMotionModifierKind> MotionModifiers,
                      ArrayRef<SourceLocation> MotionModifiersLoc,
                      CXXScopeSpec &MapperIdScopeSpec,
                      DeclarationNameInfo &MapperId, SourceLocation ColonLoc,
                      ArrayRef<Expr *> VarList, const OMPVarListLocTy &Locs,
                      ArrayRef<Expr *> UnresolvedMappers) {
     return getSema().ActOnOpenMPToClause(MotionModifiers, MotionModifiersLoc,
                                          MapperIdScopeSpec, MapperId, ColonLoc,
                                          VarList, Locs, UnresolvedMappers);
   }
 
   /// Build a new OpenMP 'from' clause.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *
   RebuildOMPFromClause(ArrayRef<OpenMPMotionModifierKind> MotionModifiers,
                        ArrayRef<SourceLocation> MotionModifiersLoc,
                        CXXScopeSpec &MapperIdScopeSpec,
                        DeclarationNameInfo &MapperId, SourceLocation ColonLoc,
                        ArrayRef<Expr *> VarList, const OMPVarListLocTy &Locs,
                        ArrayRef<Expr *> UnresolvedMappers) {
     return getSema().ActOnOpenMPFromClause(
         MotionModifiers, MotionModifiersLoc, MapperIdScopeSpec, MapperId,
         ColonLoc, VarList, Locs, UnresolvedMappers);
   }
 
   /// Build a new OpenMP 'use_device_ptr' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPUseDevicePtrClause(ArrayRef<Expr *> VarList,
                                           const OMPVarListLocTy &Locs) {
     return getSema().ActOnOpenMPUseDevicePtrClause(VarList, Locs);
   }
 
   /// Build a new OpenMP 'use_device_addr' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPUseDeviceAddrClause(ArrayRef<Expr *> VarList,
                                            const OMPVarListLocTy &Locs) {
     return getSema().ActOnOpenMPUseDeviceAddrClause(VarList, Locs);
   }
 
   /// Build a new OpenMP 'is_device_ptr' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPIsDevicePtrClause(ArrayRef<Expr *> VarList,
                                          const OMPVarListLocTy &Locs) {
     return getSema().ActOnOpenMPIsDevicePtrClause(VarList, Locs);
   }
 
   /// Build a new OpenMP 'has_device_addr' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPHasDeviceAddrClause(ArrayRef<Expr *> VarList,
                                            const OMPVarListLocTy &Locs) {
     return getSema().ActOnOpenMPHasDeviceAddrClause(VarList, Locs);
   }
 
   /// Build a new OpenMP 'defaultmap' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPDefaultmapClause(OpenMPDefaultmapClauseModifier M,
                                         OpenMPDefaultmapClauseKind Kind,
                                         SourceLocation StartLoc,
                                         SourceLocation LParenLoc,
                                         SourceLocation MLoc,
                                         SourceLocation KindLoc,
                                         SourceLocation EndLoc) {
     return getSema().ActOnOpenMPDefaultmapClause(M, Kind, StartLoc, LParenLoc,
                                                  MLoc, KindLoc, EndLoc);
   }
 
   /// Build a new OpenMP 'nontemporal' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPNontemporalClause(ArrayRef<Expr *> VarList,
                                          SourceLocation StartLoc,
                                          SourceLocation LParenLoc,
                                          SourceLocation EndLoc) {
     return getSema().ActOnOpenMPNontemporalClause(VarList, StartLoc, LParenLoc,
                                                   EndLoc);
   }
 
   /// Build a new OpenMP 'inclusive' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPInclusiveClause(ArrayRef<Expr *> VarList,
                                        SourceLocation StartLoc,
                                        SourceLocation LParenLoc,
                                        SourceLocation EndLoc) {
     return getSema().ActOnOpenMPInclusiveClause(VarList, StartLoc, LParenLoc,
                                                 EndLoc);
   }
 
   /// Build a new OpenMP 'exclusive' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPExclusiveClause(ArrayRef<Expr *> VarList,
                                        SourceLocation StartLoc,
                                        SourceLocation LParenLoc,
                                        SourceLocation EndLoc) {
     return getSema().ActOnOpenMPExclusiveClause(VarList, StartLoc, LParenLoc,
                                                 EndLoc);
   }
 
   /// Build a new OpenMP 'uses_allocators' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPUsesAllocatorsClause(
       ArrayRef<Sema::UsesAllocatorsData> Data, SourceLocation StartLoc,
       SourceLocation LParenLoc, SourceLocation EndLoc) {
     return getSema().ActOnOpenMPUsesAllocatorClause(StartLoc, LParenLoc, EndLoc,
                                                     Data);
   }
 
   /// Build a new OpenMP 'affinity' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPAffinityClause(SourceLocation StartLoc,
                                       SourceLocation LParenLoc,
                                       SourceLocation ColonLoc,
                                       SourceLocation EndLoc, Expr *Modifier,
                                       ArrayRef<Expr *> Locators) {
     return getSema().ActOnOpenMPAffinityClause(StartLoc, LParenLoc, ColonLoc,
                                                EndLoc, Modifier, Locators);
   }
 
   /// Build a new OpenMP 'order' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPOrderClause(
       OpenMPOrderClauseKind Kind, SourceLocation KindKwLoc,
       SourceLocation StartLoc, SourceLocation LParenLoc, SourceLocation EndLoc,
       OpenMPOrderClauseModifier Modifier, SourceLocation ModifierKwLoc) {
     return getSema().ActOnOpenMPOrderClause(Modifier, Kind, StartLoc, LParenLoc,
                                             ModifierKwLoc, KindKwLoc, EndLoc);
   }
 
   /// Build a new OpenMP 'init' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPInitClause(Expr *InteropVar, OMPInteropInfo &InteropInfo,
                                   SourceLocation StartLoc,
                                   SourceLocation LParenLoc,
                                   SourceLocation VarLoc,
                                   SourceLocation EndLoc) {
     return getSema().ActOnOpenMPInitClause(InteropVar, InteropInfo, StartLoc,
                                            LParenLoc, VarLoc, EndLoc);
   }
 
   /// Build a new OpenMP 'use' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPUseClause(Expr *InteropVar, SourceLocation StartLoc,
                                  SourceLocation LParenLoc,
                                  SourceLocation VarLoc, SourceLocation EndLoc) {
     return getSema().ActOnOpenMPUseClause(InteropVar, StartLoc, LParenLoc,
                                           VarLoc, EndLoc);
   }
 
   /// Build a new OpenMP 'destroy' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPDestroyClause(Expr *InteropVar, SourceLocation StartLoc,
                                      SourceLocation LParenLoc,
                                      SourceLocation VarLoc,
                                      SourceLocation EndLoc) {
     return getSema().ActOnOpenMPDestroyClause(InteropVar, StartLoc, LParenLoc,
                                               VarLoc, EndLoc);
   }
 
   /// Build a new OpenMP 'novariants' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPNovariantsClause(Expr *Condition,
                                         SourceLocation StartLoc,
                                         SourceLocation LParenLoc,
                                         SourceLocation EndLoc) {
     return getSema().ActOnOpenMPNovariantsClause(Condition, StartLoc, LParenLoc,
                                                  EndLoc);
   }
 
   /// Build a new OpenMP 'nocontext' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPNocontextClause(Expr *Condition, SourceLocation StartLoc,
                                        SourceLocation LParenLoc,
                                        SourceLocation EndLoc) {
     return getSema().ActOnOpenMPNocontextClause(Condition, StartLoc, LParenLoc,
                                                 EndLoc);
   }
 
   /// Build a new OpenMP 'filter' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPFilterClause(Expr *ThreadID, SourceLocation StartLoc,
                                     SourceLocation LParenLoc,
                                     SourceLocation EndLoc) {
     return getSema().ActOnOpenMPFilterClause(ThreadID, StartLoc, LParenLoc,
                                              EndLoc);
   }
 
   /// Build a new OpenMP 'bind' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPBindClause(OpenMPBindClauseKind Kind,
                                   SourceLocation KindLoc,
                                   SourceLocation StartLoc,
                                   SourceLocation LParenLoc,
                                   SourceLocation EndLoc) {
     return getSema().ActOnOpenMPBindClause(Kind, KindLoc, StartLoc, LParenLoc,
                                            EndLoc);
   }
 
   /// Build a new OpenMP 'ompx_dyn_cgroup_mem' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPXDynCGroupMemClause(Expr *Size, SourceLocation StartLoc,
                                            SourceLocation LParenLoc,
                                            SourceLocation EndLoc) {
     return getSema().ActOnOpenMPXDynCGroupMemClause(Size, StartLoc, LParenLoc,
                                                     EndLoc);
   }
 
   /// Build a new OpenMP 'align' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPAlignClause(Expr *A, SourceLocation StartLoc,
                                    SourceLocation LParenLoc,
                                    SourceLocation EndLoc) {
     return getSema().ActOnOpenMPAlignClause(A, StartLoc, LParenLoc, EndLoc);
   }
 
   /// Build a new OpenMP 'at' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPAtClause(OpenMPAtClauseKind Kind, SourceLocation KwLoc,
                                 SourceLocation StartLoc,
                                 SourceLocation LParenLoc,
                                 SourceLocation EndLoc) {
     return getSema().ActOnOpenMPAtClause(Kind, KwLoc, StartLoc, LParenLoc,
                                          EndLoc);
   }
 
   /// Build a new OpenMP 'severity' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPSeverityClause(OpenMPSeverityClauseKind Kind,
                                       SourceLocation KwLoc,
                                       SourceLocation StartLoc,
                                       SourceLocation LParenLoc,
                                       SourceLocation EndLoc) {
     return getSema().ActOnOpenMPSeverityClause(Kind, KwLoc, StartLoc, LParenLoc,
                                                EndLoc);
   }
 
   /// Build a new OpenMP 'message' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *RebuildOMPMessageClause(Expr *MS, SourceLocation StartLoc,
                                      SourceLocation LParenLoc,
                                      SourceLocation EndLoc) {
     return getSema().ActOnOpenMPMessageClause(MS, StartLoc, LParenLoc, EndLoc);
   }
 
   /// Build a new OpenMP 'doacross' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
   OMPClause *
   RebuildOMPDoacrossClause(OpenMPDoacrossClauseModifier DepType,
                            SourceLocation DepLoc, SourceLocation ColonLoc,
                            ArrayRef<Expr *> VarList, SourceLocation StartLoc,
                            SourceLocation LParenLoc, SourceLocation EndLoc) {
     return getSema().ActOnOpenMPDoacrossClause(
         DepType, DepLoc, ColonLoc, VarList, StartLoc, LParenLoc, EndLoc);
   }
 
   /// Rebuild the operand to an Objective-C \@synchronized statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildObjCAtSynchronizedOperand(SourceLocation atLoc,
                                               Expr *object) {
     return getSema().ActOnObjCAtSynchronizedOperand(atLoc, object);
   }
 
   /// Build a new Objective-C \@synchronized statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildObjCAtSynchronizedStmt(SourceLocation AtLoc,
                                            Expr *Object, Stmt *Body) {
     return getSema().ActOnObjCAtSynchronizedStmt(AtLoc, Object, Body);
   }
 
   /// Build a new Objective-C \@autoreleasepool statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildObjCAutoreleasePoolStmt(SourceLocation AtLoc,
                                             Stmt *Body) {
     return getSema().ActOnObjCAutoreleasePoolStmt(AtLoc, Body);
   }
 
   /// Build a new Objective-C fast enumeration statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildObjCForCollectionStmt(SourceLocation ForLoc,
                                           Stmt *Element,
                                           Expr *Collection,
                                           SourceLocation RParenLoc,
                                           Stmt *Body) {
     StmtResult ForEachStmt = getSema().ActOnObjCForCollectionStmt(ForLoc,
                                                 Element,
                                                 Collection,
                                                 RParenLoc);
     if (ForEachStmt.isInvalid())
       return StmtError();
 
     return getSema().FinishObjCForCollectionStmt(ForEachStmt.get(), Body);
   }
 
   /// Build a new C++ exception declaration.
   ///
   /// By default, performs semantic analysis to build the new decaration.
   /// Subclasses may override this routine to provide different behavior.
   VarDecl *RebuildExceptionDecl(VarDecl *ExceptionDecl,
                                 TypeSourceInfo *Declarator,
                                 SourceLocation StartLoc,
                                 SourceLocation IdLoc,
                                 IdentifierInfo *Id) {
     VarDecl *Var = getSema().BuildExceptionDeclaration(nullptr, Declarator,
                                                        StartLoc, IdLoc, Id);
     if (Var)
       getSema().CurContext->addDecl(Var);
     return Var;
   }
 
   /// Build a new C++ catch statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildCXXCatchStmt(SourceLocation CatchLoc,
                                  VarDecl *ExceptionDecl,
                                  Stmt *Handler) {
     return Owned(new (getSema().Context) CXXCatchStmt(CatchLoc, ExceptionDecl,
                                                       Handler));
   }
 
   /// Build a new C++ try statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildCXXTryStmt(SourceLocation TryLoc, Stmt *TryBlock,
                                ArrayRef<Stmt *> Handlers) {
     return getSema().ActOnCXXTryBlock(TryLoc, TryBlock, Handlers);
   }
 
   /// Build a new C++0x range-based for statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildCXXForRangeStmt(SourceLocation ForLoc,
                                     SourceLocation CoawaitLoc, Stmt *Init,
                                     SourceLocation ColonLoc, Stmt *Range,
                                     Stmt *Begin, Stmt *End, Expr *Cond,
                                     Expr *Inc, Stmt *LoopVar,
                                     SourceLocation RParenLoc) {
     // If we've just learned that the range is actually an Objective-C
     // collection, treat this as an Objective-C fast enumeration loop.
     if (DeclStmt *RangeStmt = dyn_cast<DeclStmt>(Range)) {
       if (RangeStmt->isSingleDecl()) {
         if (VarDecl *RangeVar = dyn_cast<VarDecl>(RangeStmt->getSingleDecl())) {
           if (RangeVar->isInvalidDecl())
             return StmtError();
 
           Expr *RangeExpr = RangeVar->getInit();
           if (!RangeExpr->isTypeDependent() &&
               RangeExpr->getType()->isObjCObjectPointerType()) {
             // FIXME: Support init-statements in Objective-C++20 ranged for
             // statement.
             if (Init) {
               return SemaRef.Diag(Init->getBeginLoc(),
                                   diag::err_objc_for_range_init_stmt)
                          << Init->getSourceRange();
             }
             return getSema().ActOnObjCForCollectionStmt(ForLoc, LoopVar,
                                                         RangeExpr, RParenLoc);
           }
         }
       }
     }
 
     return getSema().BuildCXXForRangeStmt(ForLoc, CoawaitLoc, Init, ColonLoc,
                                           Range, Begin, End, Cond, Inc, LoopVar,
                                           RParenLoc, Sema::BFRK_Rebuild);
   }
 
   /// Build a new C++0x range-based for statement.
   ///
   /// By default, performs semantic analysis to build the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult RebuildMSDependentExistsStmt(SourceLocation KeywordLoc,
                                           bool IsIfExists,
                                           NestedNameSpecifierLoc QualifierLoc,
                                           DeclarationNameInfo NameInfo,
                                           Stmt *Nested) {
     return getSema().BuildMSDependentExistsStmt(KeywordLoc, IsIfExists,
                                                 QualifierLoc, NameInfo, Nested);
   }
 
   /// Attach body to a C++0x range-based for statement.
   ///
   /// By default, performs semantic analysis to finish the new statement.
   /// Subclasses may override this routine to provide different behavior.
   StmtResult FinishCXXForRangeStmt(Stmt *ForRange, Stmt *Body) {
     return getSema().FinishCXXForRangeStmt(ForRange, Body);
   }
 
   StmtResult RebuildSEHTryStmt(bool IsCXXTry, SourceLocation TryLoc,
                                Stmt *TryBlock, Stmt *Handler) {
     return getSema().ActOnSEHTryBlock(IsCXXTry, TryLoc, TryBlock, Handler);
   }
 
   StmtResult RebuildSEHExceptStmt(SourceLocation Loc, Expr *FilterExpr,
                                   Stmt *Block) {
     return getSema().ActOnSEHExceptBlock(Loc, FilterExpr, Block);
   }
 
   StmtResult RebuildSEHFinallyStmt(SourceLocation Loc, Stmt *Block) {
     return SEHFinallyStmt::Create(getSema().getASTContext(), Loc, Block);
   }
 
   ExprResult RebuildSYCLUniqueStableNameExpr(SourceLocation OpLoc,
                                              SourceLocation LParen,
                                              SourceLocation RParen,
                                              TypeSourceInfo *TSI) {
     return getSema().BuildSYCLUniqueStableNameExpr(OpLoc, LParen, RParen, TSI);
   }
 
   /// Build a new predefined expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildPredefinedExpr(SourceLocation Loc,
                                    PredefinedExpr::IdentKind IK) {
     return getSema().BuildPredefinedExpr(Loc, IK);
   }
 
   /// Build a new expression that references a declaration.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildDeclarationNameExpr(const CXXScopeSpec &SS,
                                         LookupResult &R,
                                         bool RequiresADL) {
     return getSema().BuildDeclarationNameExpr(SS, R, RequiresADL);
   }
 
 
   /// Build a new expression that references a declaration.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildDeclRefExpr(NestedNameSpecifierLoc QualifierLoc,
                                 ValueDecl *VD,
                                 const DeclarationNameInfo &NameInfo,
                                 NamedDecl *Found,
                                 TemplateArgumentListInfo *TemplateArgs) {
     CXXScopeSpec SS;
     SS.Adopt(QualifierLoc);
     return getSema().BuildDeclarationNameExpr(SS, NameInfo, VD, Found,
                                               TemplateArgs);
   }
 
   /// Build a new expression in parentheses.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildParenExpr(Expr *SubExpr, SourceLocation LParen,
                                     SourceLocation RParen) {
     return getSema().ActOnParenExpr(LParen, RParen, SubExpr);
   }
 
   /// Build a new pseudo-destructor expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildCXXPseudoDestructorExpr(Expr *Base,
                                             SourceLocation OperatorLoc,
                                             bool isArrow,
                                             CXXScopeSpec &SS,
                                             TypeSourceInfo *ScopeType,
                                             SourceLocation CCLoc,
                                             SourceLocation TildeLoc,
                                         PseudoDestructorTypeStorage Destroyed);
 
   /// Build a new unary operator expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildUnaryOperator(SourceLocation OpLoc,
                                         UnaryOperatorKind Opc,
                                         Expr *SubExpr) {
     return getSema().BuildUnaryOp(/*Scope=*/nullptr, OpLoc, Opc, SubExpr);
   }
 
   /// Build a new builtin offsetof expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildOffsetOfExpr(SourceLocation OperatorLoc,
                                  TypeSourceInfo *Type,
                                  ArrayRef<Sema::OffsetOfComponent> Components,
                                  SourceLocation RParenLoc) {
     return getSema().BuildBuiltinOffsetOf(OperatorLoc, Type, Components,
                                           RParenLoc);
   }
 
   /// Build a new sizeof, alignof or vec_step expression with a
   /// type argument.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildUnaryExprOrTypeTrait(TypeSourceInfo *TInfo,
                                          SourceLocation OpLoc,
                                          UnaryExprOrTypeTrait ExprKind,
                                          SourceRange R) {
     return getSema().CreateUnaryExprOrTypeTraitExpr(TInfo, OpLoc, ExprKind, R);
   }
 
   /// Build a new sizeof, alignof or vec step expression with an
   /// expression argument.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildUnaryExprOrTypeTrait(Expr *SubExpr, SourceLocation OpLoc,
                                          UnaryExprOrTypeTrait ExprKind,
                                          SourceRange R) {
     ExprResult Result
       = getSema().CreateUnaryExprOrTypeTraitExpr(SubExpr, OpLoc, ExprKind);
     if (Result.isInvalid())
       return ExprError();
 
     return Result;
   }
 
   /// Build a new array subscript expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildArraySubscriptExpr(Expr *LHS,
                                              SourceLocation LBracketLoc,
                                              Expr *RHS,
                                              SourceLocation RBracketLoc) {
     return getSema().ActOnArraySubscriptExpr(/*Scope=*/nullptr, LHS,
                                              LBracketLoc, RHS,
                                              RBracketLoc);
   }
 
   /// Build a new matrix subscript expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildMatrixSubscriptExpr(Expr *Base, Expr *RowIdx,
                                         Expr *ColumnIdx,
                                         SourceLocation RBracketLoc) {
     return getSema().CreateBuiltinMatrixSubscriptExpr(Base, RowIdx, ColumnIdx,
                                                       RBracketLoc);
   }
 
   /// Build a new array section expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildOMPArraySectionExpr(Expr *Base, SourceLocation LBracketLoc,
                                         Expr *LowerBound,
                                         SourceLocation ColonLocFirst,
                                         SourceLocation ColonLocSecond,
                                         Expr *Length, Expr *Stride,
                                         SourceLocation RBracketLoc) {
     return getSema().ActOnOMPArraySectionExpr(Base, LBracketLoc, LowerBound,
                                               ColonLocFirst, ColonLocSecond,
                                               Length, Stride, RBracketLoc);
   }
 
   /// Build a new array shaping expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildOMPArrayShapingExpr(Expr *Base, SourceLocation LParenLoc,
                                         SourceLocation RParenLoc,
                                         ArrayRef<Expr *> Dims,
                                         ArrayRef<SourceRange> BracketsRanges) {
     return getSema().ActOnOMPArrayShapingExpr(Base, LParenLoc, RParenLoc, Dims,
                                               BracketsRanges);
   }
 
   /// Build a new iterator expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildOMPIteratorExpr(
       SourceLocation IteratorKwLoc, SourceLocation LLoc, SourceLocation RLoc,
       ArrayRef<Sema::OMPIteratorData> Data) {
     return getSema().ActOnOMPIteratorExpr(/*Scope=*/nullptr, IteratorKwLoc,
                                           LLoc, RLoc, Data);
   }
 
   /// Build a new call expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildCallExpr(Expr *Callee, SourceLocation LParenLoc,
                                    MultiExprArg Args,
                                    SourceLocation RParenLoc,
                                    Expr *ExecConfig = nullptr) {
     return getSema().ActOnCallExpr(
         /*Scope=*/nullptr, Callee, LParenLoc, Args, RParenLoc, ExecConfig);
   }
 
   ExprResult RebuildCxxSubscriptExpr(Expr *Callee, SourceLocation LParenLoc,
                                      MultiExprArg Args,
                                      SourceLocation RParenLoc) {
     return getSema().ActOnArraySubscriptExpr(
         /*Scope=*/nullptr, Callee, LParenLoc, Args, RParenLoc);
   }
 
   /// Build a new member access expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildMemberExpr(Expr *Base, SourceLocation OpLoc,
                                bool isArrow,
                                NestedNameSpecifierLoc QualifierLoc,
                                SourceLocation TemplateKWLoc,
                                const DeclarationNameInfo &MemberNameInfo,
                                ValueDecl *Member,
                                NamedDecl *FoundDecl,
                         const TemplateArgumentListInfo *ExplicitTemplateArgs,
                                NamedDecl *FirstQualifierInScope) {
     ExprResult BaseResult = getSema().PerformMemberExprBaseConversion(Base,
                                                                       isArrow);
     if (!Member->getDeclName()) {
       // We have a reference to an unnamed field.  This is always the
       // base of an anonymous struct/union member access, i.e. the
       // field is always of record type.
       assert(Member->getType()->isRecordType() &&
              "unnamed member not of record type?");
 
       BaseResult =
         getSema().PerformObjectMemberConversion(BaseResult.get(),
                                                 QualifierLoc.getNestedNameSpecifier(),
                                                 FoundDecl, Member);
       if (BaseResult.isInvalid())
         return ExprError();
       Base = BaseResult.get();
 
       CXXScopeSpec EmptySS;
       return getSema().BuildFieldReferenceExpr(
           Base, isArrow, OpLoc, EmptySS, cast<FieldDecl>(Member),
           DeclAccessPair::make(FoundDecl, FoundDecl->getAccess()), MemberNameInfo);
     }
 
     CXXScopeSpec SS;
     SS.Adopt(QualifierLoc);
 
     Base = BaseResult.get();
     QualType BaseType = Base->getType();
 
     if (isArrow && !BaseType->isPointerType())
       return ExprError();
 
     // FIXME: this involves duplicating earlier analysis in a lot of
     // cases; we should avoid this when possible.
     LookupResult R(getSema(), MemberNameInfo, Sema::LookupMemberName);
     R.addDecl(FoundDecl);
     R.resolveKind();
 
     if (getSema().isUnevaluatedContext() && Base->isImplicitCXXThis() &&
         isa<FieldDecl, IndirectFieldDecl, MSPropertyDecl>(Member)) {
       if (auto *ThisClass = cast<CXXThisExpr>(Base)
                                 ->getType()
                                 ->getPointeeType()
                                 ->getAsCXXRecordDecl()) {
         auto *Class = cast<CXXRecordDecl>(Member->getDeclContext());
         // In unevaluated contexts, an expression supposed to be a member access
         // might reference a member in an unrelated class.
         if (!ThisClass->Equals(Class) && !ThisClass->isDerivedFrom(Class))
           return getSema().BuildDeclRefExpr(Member, Member->getType(),
                                             VK_LValue, Member->getLocation());
       }
     }
 
     return getSema().BuildMemberReferenceExpr(Base, BaseType, OpLoc, isArrow,
                                               SS, TemplateKWLoc,
                                               FirstQualifierInScope,
                                               R, ExplicitTemplateArgs,
                                               /*S*/nullptr);
   }
 
   /// Build a new binary operator expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildBinaryOperator(SourceLocation OpLoc,
                                          BinaryOperatorKind Opc,
                                          Expr *LHS, Expr *RHS) {
     return getSema().BuildBinOp(/*Scope=*/nullptr, OpLoc, Opc, LHS, RHS);
   }
 
   /// Build a new rewritten operator expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildCXXRewrittenBinaryOperator(
       SourceLocation OpLoc, BinaryOperatorKind Opcode,
       const UnresolvedSetImpl &UnqualLookups, Expr *LHS, Expr *RHS) {
     return getSema().CreateOverloadedBinOp(OpLoc, Opcode, UnqualLookups, LHS,
                                            RHS, /*RequiresADL*/false);
   }
 
   /// Build a new conditional operator expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildConditionalOperator(Expr *Cond,
                                         SourceLocation QuestionLoc,
                                         Expr *LHS,
                                         SourceLocation ColonLoc,
                                         Expr *RHS) {
     return getSema().ActOnConditionalOp(QuestionLoc, ColonLoc, Cond,
                                         LHS, RHS);
   }
 
   /// Build a new C-style cast expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildCStyleCastExpr(SourceLocation LParenLoc,
                                          TypeSourceInfo *TInfo,
                                          SourceLocation RParenLoc,
                                          Expr *SubExpr) {
     return getSema().BuildCStyleCastExpr(LParenLoc, TInfo, RParenLoc,
                                          SubExpr);
   }
 
   /// Build a new compound literal expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildCompoundLiteralExpr(SourceLocation LParenLoc,
                                               TypeSourceInfo *TInfo,
                                               SourceLocation RParenLoc,
                                               Expr *Init) {
     return getSema().BuildCompoundLiteralExpr(LParenLoc, TInfo, RParenLoc,
                                               Init);
   }
 
   /// Build a new extended vector element access expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildExtVectorElementExpr(Expr *Base, SourceLocation OpLoc,
                                          bool IsArrow,
                                          SourceLocation AccessorLoc,
                                          IdentifierInfo &Accessor) {
 
     CXXScopeSpec SS;
     DeclarationNameInfo NameInfo(&Accessor, AccessorLoc);
     return getSema().BuildMemberReferenceExpr(
         Base, Base->getType(), OpLoc, IsArrow, SS, SourceLocation(),
         /*FirstQualifierInScope*/ nullptr, NameInfo,
         /* TemplateArgs */ nullptr,
         /*S*/ nullptr);
   }
 
   /// Build a new initializer list expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildInitList(SourceLocation LBraceLoc,
                              MultiExprArg Inits,
                              SourceLocation RBraceLoc) {
     return SemaRef.BuildInitList(LBraceLoc, Inits, RBraceLoc);
   }
 
   /// Build a new designated initializer expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildDesignatedInitExpr(Designation &Desig,
                                              MultiExprArg ArrayExprs,
                                              SourceLocation EqualOrColonLoc,
                                              bool GNUSyntax,
                                              Expr *Init) {
     ExprResult Result
       = SemaRef.ActOnDesignatedInitializer(Desig, EqualOrColonLoc, GNUSyntax,
                                            Init);
     if (Result.isInvalid())
       return ExprError();
 
     return Result;
   }
 
   /// Build a new value-initialized expression.
   ///
   /// By default, builds the implicit value initialization without performing
   /// any semantic analysis. Subclasses may override this routine to provide
   /// different behavior.
   ExprResult RebuildImplicitValueInitExpr(QualType T) {
     return new (SemaRef.Context) ImplicitValueInitExpr(T);
   }
 
   /// Build a new \c va_arg expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildVAArgExpr(SourceLocation BuiltinLoc,
                                     Expr *SubExpr, TypeSourceInfo *TInfo,
                                     SourceLocation RParenLoc) {
     return getSema().BuildVAArgExpr(BuiltinLoc,
                                     SubExpr, TInfo,
                                     RParenLoc);
   }
 
   /// Build a new expression list in parentheses.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildParenListExpr(SourceLocation LParenLoc,
                                   MultiExprArg SubExprs,
                                   SourceLocation RParenLoc) {
     return getSema().ActOnParenListExpr(LParenLoc, RParenLoc, SubExprs);
   }
 
   /// Build a new address-of-label expression.
   ///
   /// By default, performs semantic analysis, using the name of the label
   /// rather than attempting to map the label statement itself.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildAddrLabelExpr(SourceLocation AmpAmpLoc,
                                   SourceLocation LabelLoc, LabelDecl *Label) {
     return getSema().ActOnAddrLabel(AmpAmpLoc, LabelLoc, Label);
   }
 
   /// Build a new GNU statement expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildStmtExpr(SourceLocation LParenLoc, Stmt *SubStmt,
                              SourceLocation RParenLoc, unsigned TemplateDepth) {
     return getSema().BuildStmtExpr(LParenLoc, SubStmt, RParenLoc,
                                    TemplateDepth);
   }
 
   /// Build a new __builtin_choose_expr expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildChooseExpr(SourceLocation BuiltinLoc,
                                      Expr *Cond, Expr *LHS, Expr *RHS,
                                      SourceLocation RParenLoc) {
     return SemaRef.ActOnChooseExpr(BuiltinLoc,
                                    Cond, LHS, RHS,
                                    RParenLoc);
   }
 
   /// Build a new generic selection expression with an expression predicate.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildGenericSelectionExpr(SourceLocation KeyLoc,
                                          SourceLocation DefaultLoc,
                                          SourceLocation RParenLoc,
                                          Expr *ControllingExpr,
                                          ArrayRef<TypeSourceInfo *> Types,
                                          ArrayRef<Expr *> Exprs) {
     return getSema().CreateGenericSelectionExpr(KeyLoc, DefaultLoc, RParenLoc,
                                                 /*PredicateIsExpr=*/true,
                                                 ControllingExpr, Types, Exprs);
   }
 
   /// Build a new generic selection expression with a type predicate.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildGenericSelectionExpr(SourceLocation KeyLoc,
                                          SourceLocation DefaultLoc,
                                          SourceLocation RParenLoc,
                                          TypeSourceInfo *ControllingType,
                                          ArrayRef<TypeSourceInfo *> Types,
                                          ArrayRef<Expr *> Exprs) {
     return getSema().CreateGenericSelectionExpr(KeyLoc, DefaultLoc, RParenLoc,
                                                 /*PredicateIsExpr=*/false,
                                                 ControllingType, Types, Exprs);
   }
 
   /// Build a new overloaded operator call expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// The semantic analysis provides the behavior of template instantiation,
   /// copying with transformations that turn what looks like an overloaded
   /// operator call into a use of a builtin operator, performing
   /// argument-dependent lookup, etc. Subclasses may override this routine to
   /// provide different behavior.
   ExprResult RebuildCXXOperatorCallExpr(OverloadedOperatorKind Op,
                                         SourceLocation OpLoc,
                                         SourceLocation CalleeLoc,
                                         bool RequiresADL,
                                         const UnresolvedSetImpl &Functions,
                                         Expr *First, Expr *Second);
 
   /// Build a new C++ "named" cast expression, such as static_cast or
   /// reinterpret_cast.
   ///
   /// By default, this routine dispatches to one of the more-specific routines
   /// for a particular named case, e.g., RebuildCXXStaticCastExpr().
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildCXXNamedCastExpr(SourceLocation OpLoc,
                                            Stmt::StmtClass Class,
                                            SourceLocation LAngleLoc,
                                            TypeSourceInfo *TInfo,
                                            SourceLocation RAngleLoc,
                                            SourceLocation LParenLoc,
                                            Expr *SubExpr,
                                            SourceLocation RParenLoc) {
     switch (Class) {
     case Stmt::CXXStaticCastExprClass:
       return getDerived().RebuildCXXStaticCastExpr(OpLoc, LAngleLoc, TInfo,
                                                    RAngleLoc, LParenLoc,
                                                    SubExpr, RParenLoc);
 
     case Stmt::CXXDynamicCastExprClass:
       return getDerived().RebuildCXXDynamicCastExpr(OpLoc, LAngleLoc, TInfo,
                                                     RAngleLoc, LParenLoc,
                                                     SubExpr, RParenLoc);
 
     case Stmt::CXXReinterpretCastExprClass:
       return getDerived().RebuildCXXReinterpretCastExpr(OpLoc, LAngleLoc, TInfo,
                                                         RAngleLoc, LParenLoc,
                                                         SubExpr,
                                                         RParenLoc);
 
     case Stmt::CXXConstCastExprClass:
       return getDerived().RebuildCXXConstCastExpr(OpLoc, LAngleLoc, TInfo,
                                                    RAngleLoc, LParenLoc,
                                                    SubExpr, RParenLoc);
 
     case Stmt::CXXAddrspaceCastExprClass:
       return getDerived().RebuildCXXAddrspaceCastExpr(
           OpLoc, LAngleLoc, TInfo, RAngleLoc, LParenLoc, SubExpr, RParenLoc);
 
     default:
       llvm_unreachable("Invalid C++ named cast");
     }
   }
 
   /// Build a new C++ static_cast expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildCXXStaticCastExpr(SourceLocation OpLoc,
                                             SourceLocation LAngleLoc,
                                             TypeSourceInfo *TInfo,
                                             SourceLocation RAngleLoc,
                                             SourceLocation LParenLoc,
                                             Expr *SubExpr,
                                             SourceLocation RParenLoc) {
     return getSema().BuildCXXNamedCast(OpLoc, tok::kw_static_cast,
                                        TInfo, SubExpr,
                                        SourceRange(LAngleLoc, RAngleLoc),
                                        SourceRange(LParenLoc, RParenLoc));
   }
 
   /// Build a new C++ dynamic_cast expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildCXXDynamicCastExpr(SourceLocation OpLoc,
                                              SourceLocation LAngleLoc,
                                              TypeSourceInfo *TInfo,
                                              SourceLocation RAngleLoc,
                                              SourceLocation LParenLoc,
                                              Expr *SubExpr,
                                              SourceLocation RParenLoc) {
     return getSema().BuildCXXNamedCast(OpLoc, tok::kw_dynamic_cast,
                                        TInfo, SubExpr,
                                        SourceRange(LAngleLoc, RAngleLoc),
                                        SourceRange(LParenLoc, RParenLoc));
   }
 
   /// Build a new C++ reinterpret_cast expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildCXXReinterpretCastExpr(SourceLocation OpLoc,
                                                  SourceLocation LAngleLoc,
                                                  TypeSourceInfo *TInfo,
                                                  SourceLocation RAngleLoc,
                                                  SourceLocation LParenLoc,
                                                  Expr *SubExpr,
                                                  SourceLocation RParenLoc) {
     return getSema().BuildCXXNamedCast(OpLoc, tok::kw_reinterpret_cast,
                                        TInfo, SubExpr,
                                        SourceRange(LAngleLoc, RAngleLoc),
                                        SourceRange(LParenLoc, RParenLoc));
   }
 
   /// Build a new C++ const_cast expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildCXXConstCastExpr(SourceLocation OpLoc,
                                            SourceLocation LAngleLoc,
                                            TypeSourceInfo *TInfo,
                                            SourceLocation RAngleLoc,
                                            SourceLocation LParenLoc,
                                            Expr *SubExpr,
                                            SourceLocation RParenLoc) {
     return getSema().BuildCXXNamedCast(OpLoc, tok::kw_const_cast,
                                        TInfo, SubExpr,
                                        SourceRange(LAngleLoc, RAngleLoc),
                                        SourceRange(LParenLoc, RParenLoc));
   }
 
   ExprResult
   RebuildCXXAddrspaceCastExpr(SourceLocation OpLoc, SourceLocation LAngleLoc,
                               TypeSourceInfo *TInfo, SourceLocation RAngleLoc,
                               SourceLocation LParenLoc, Expr *SubExpr,
                               SourceLocation RParenLoc) {
     return getSema().BuildCXXNamedCast(
         OpLoc, tok::kw_addrspace_cast, TInfo, SubExpr,
         SourceRange(LAngleLoc, RAngleLoc), SourceRange(LParenLoc, RParenLoc));
   }
 
   /// Build a new C++ functional-style cast expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildCXXFunctionalCastExpr(TypeSourceInfo *TInfo,
                                           SourceLocation LParenLoc,
                                           Expr *Sub,
                                           SourceLocation RParenLoc,
                                           bool ListInitialization) {
     // If Sub is a ParenListExpr, then Sub is the syntatic form of a
     // CXXParenListInitExpr. Pass its expanded arguments so that the
     // CXXParenListInitExpr can be rebuilt.
     if (auto *PLE = dyn_cast<ParenListExpr>(Sub))
       return getSema().BuildCXXTypeConstructExpr(
           TInfo, LParenLoc, MultiExprArg(PLE->getExprs(), PLE->getNumExprs()),
           RParenLoc, ListInitialization);
     return getSema().BuildCXXTypeConstructExpr(TInfo, LParenLoc,
                                                MultiExprArg(&Sub, 1), RParenLoc,
                                                ListInitialization);
   }
 
   /// Build a new C++ __builtin_bit_cast expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildBuiltinBitCastExpr(SourceLocation KWLoc,
                                        TypeSourceInfo *TSI, Expr *Sub,
                                        SourceLocation RParenLoc) {
     return getSema().BuildBuiltinBitCastExpr(KWLoc, TSI, Sub, RParenLoc);
   }
 
   /// Build a new C++ typeid(type) expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildCXXTypeidExpr(QualType TypeInfoType,
                                         SourceLocation TypeidLoc,
                                         TypeSourceInfo *Operand,
                                         SourceLocation RParenLoc) {
     return getSema().BuildCXXTypeId(TypeInfoType, TypeidLoc, Operand,
                                     RParenLoc);
   }
 
 
   /// Build a new C++ typeid(expr) expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildCXXTypeidExpr(QualType TypeInfoType,
                                         SourceLocation TypeidLoc,
                                         Expr *Operand,
                                         SourceLocation RParenLoc) {
     return getSema().BuildCXXTypeId(TypeInfoType, TypeidLoc, Operand,
                                     RParenLoc);
   }
 
   /// Build a new C++ __uuidof(type) expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildCXXUuidofExpr(QualType Type, SourceLocation TypeidLoc,
                                   TypeSourceInfo *Operand,
                                   SourceLocation RParenLoc) {
     return getSema().BuildCXXUuidof(Type, TypeidLoc, Operand, RParenLoc);
   }
 
   /// Build a new C++ __uuidof(expr) expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildCXXUuidofExpr(QualType Type, SourceLocation TypeidLoc,
                                   Expr *Operand, SourceLocation RParenLoc) {
     return getSema().BuildCXXUuidof(Type, TypeidLoc, Operand, RParenLoc);
   }
 
   /// Build a new C++ "this" expression.
   ///
   /// By default, builds a new "this" expression without performing any
   /// semantic analysis. Subclasses may override this routine to provide
   /// different behavior.
   ExprResult RebuildCXXThisExpr(SourceLocation ThisLoc,
                                 QualType ThisType,
                                 bool isImplicit) {
     return getSema().BuildCXXThisExpr(ThisLoc, ThisType, isImplicit);
   }
 
   /// Build a new C++ throw expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildCXXThrowExpr(SourceLocation ThrowLoc, Expr *Sub,
                                  bool IsThrownVariableInScope) {
     return getSema().BuildCXXThrow(ThrowLoc, Sub, IsThrownVariableInScope);
   }
 
   /// Build a new C++ default-argument expression.
   ///
   /// By default, builds a new default-argument expression, which does not
   /// require any semantic analysis. Subclasses may override this routine to
   /// provide different behavior.
   ExprResult RebuildCXXDefaultArgExpr(SourceLocation Loc, ParmVarDecl *Param,
                                       Expr *RewrittenExpr) {
     return CXXDefaultArgExpr::Create(getSema().Context, Loc, Param,
                                      RewrittenExpr, getSema().CurContext);
   }
 
   /// Build a new C++11 default-initialization expression.
   ///
   /// By default, builds a new default field initialization expression, which
   /// does not require any semantic analysis. Subclasses may override this
   /// routine to provide different behavior.
   ExprResult RebuildCXXDefaultInitExpr(SourceLocation Loc,
                                        FieldDecl *Field) {
     return getSema().BuildCXXDefaultInitExpr(Loc, Field);
   }
 
   /// Build a new C++ zero-initialization expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildCXXScalarValueInitExpr(TypeSourceInfo *TSInfo,
                                            SourceLocation LParenLoc,
                                            SourceLocation RParenLoc) {
     return getSema().BuildCXXTypeConstructExpr(TSInfo, LParenLoc, std::nullopt,
                                                RParenLoc,
                                                /*ListInitialization=*/false);
   }
 
   /// Build a new C++ "new" expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildCXXNewExpr(SourceLocation StartLoc, bool UseGlobal,
                                SourceLocation PlacementLParen,
                                MultiExprArg PlacementArgs,
                                SourceLocation PlacementRParen,
                                SourceRange TypeIdParens, QualType AllocatedType,
                                TypeSourceInfo *AllocatedTypeInfo,
                                std::optional<Expr *> ArraySize,
                                SourceRange DirectInitRange, Expr *Initializer) {
     return getSema().BuildCXXNew(StartLoc, UseGlobal,
                                  PlacementLParen,
                                  PlacementArgs,
                                  PlacementRParen,
                                  TypeIdParens,
                                  AllocatedType,
                                  AllocatedTypeInfo,
                                  ArraySize,
                                  DirectInitRange,
                                  Initializer);
   }
 
   /// Build a new C++ "delete" expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildCXXDeleteExpr(SourceLocation StartLoc,
                                         bool IsGlobalDelete,
                                         bool IsArrayForm,
                                         Expr *Operand) {
     return getSema().ActOnCXXDelete(StartLoc, IsGlobalDelete, IsArrayForm,
                                     Operand);
   }
 
   /// Build a new type trait expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildTypeTrait(TypeTrait Trait,
                               SourceLocation StartLoc,
                               ArrayRef<TypeSourceInfo *> Args,
                               SourceLocation RParenLoc) {
     return getSema().BuildTypeTrait(Trait, StartLoc, Args, RParenLoc);
   }
 
   /// Build a new array type trait expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildArrayTypeTrait(ArrayTypeTrait Trait,
                                    SourceLocation StartLoc,
                                    TypeSourceInfo *TSInfo,
                                    Expr *DimExpr,
                                    SourceLocation RParenLoc) {
     return getSema().BuildArrayTypeTrait(Trait, StartLoc, TSInfo, DimExpr, RParenLoc);
   }
 
   /// Build a new expression trait expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildExpressionTrait(ExpressionTrait Trait,
                                    SourceLocation StartLoc,
                                    Expr *Queried,
                                    SourceLocation RParenLoc) {
     return getSema().BuildExpressionTrait(Trait, StartLoc, Queried, RParenLoc);
   }
 
   /// Build a new (previously unresolved) declaration reference
   /// expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildDependentScopeDeclRefExpr(
                                           NestedNameSpecifierLoc QualifierLoc,
                                           SourceLocation TemplateKWLoc,
                                        const DeclarationNameInfo &NameInfo,
                               const TemplateArgumentListInfo *TemplateArgs,
                                           bool IsAddressOfOperand,
                                           TypeSourceInfo **RecoveryTSI) {
     CXXScopeSpec SS;
     SS.Adopt(QualifierLoc);
 
     if (TemplateArgs || TemplateKWLoc.isValid())
       return getSema().BuildQualifiedTemplateIdExpr(SS, TemplateKWLoc, NameInfo,
                                                     TemplateArgs);
 
     return getSema().BuildQualifiedDeclarationNameExpr(
         SS, NameInfo, IsAddressOfOperand, /*S*/nullptr, RecoveryTSI);
   }
 
   /// Build a new template-id expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildTemplateIdExpr(const CXXScopeSpec &SS,
                                    SourceLocation TemplateKWLoc,
                                    LookupResult &R,
                                    bool RequiresADL,
                               const TemplateArgumentListInfo *TemplateArgs) {
     return getSema().BuildTemplateIdExpr(SS, TemplateKWLoc, R, RequiresADL,
                                          TemplateArgs);
   }
 
   /// Build a new object-construction expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildCXXConstructExpr(QualType T,
                                      SourceLocation Loc,
                                      CXXConstructorDecl *Constructor,
                                      bool IsElidable,
                                      MultiExprArg Args,
                                      bool HadMultipleCandidates,
                                      bool ListInitialization,
                                      bool StdInitListInitialization,
                                      bool RequiresZeroInit,
                              CXXConstructExpr::ConstructionKind ConstructKind,
                                      SourceRange ParenRange) {
     // Reconstruct the constructor we originally found, which might be
     // different if this is a call to an inherited constructor.
     CXXConstructorDecl *FoundCtor = Constructor;
     if (Constructor->isInheritingConstructor())
       FoundCtor = Constructor->getInheritedConstructor().getConstructor();
 
     SmallVector<Expr *, 8> ConvertedArgs;
     if (getSema().CompleteConstructorCall(FoundCtor, T, Args, Loc,
                                           ConvertedArgs))
       return ExprError();
 
     return getSema().BuildCXXConstructExpr(Loc, T, Constructor,
                                            IsElidable,
                                            ConvertedArgs,
                                            HadMultipleCandidates,
                                            ListInitialization,
                                            StdInitListInitialization,
                                            RequiresZeroInit, ConstructKind,
                                            ParenRange);
   }
 
   /// Build a new implicit construction via inherited constructor
   /// expression.
   ExprResult RebuildCXXInheritedCtorInitExpr(QualType T, SourceLocation Loc,
                                              CXXConstructorDecl *Constructor,
                                              bool ConstructsVBase,
                                              bool InheritedFromVBase) {
     return new (getSema().Context) CXXInheritedCtorInitExpr(
         Loc, T, Constructor, ConstructsVBase, InheritedFromVBase);
   }
 
   /// Build a new object-construction expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildCXXTemporaryObjectExpr(TypeSourceInfo *TSInfo,
                                            SourceLocation LParenOrBraceLoc,
                                            MultiExprArg Args,
                                            SourceLocation RParenOrBraceLoc,
                                            bool ListInitialization) {
     return getSema().BuildCXXTypeConstructExpr(
         TSInfo, LParenOrBraceLoc, Args, RParenOrBraceLoc, ListInitialization);
   }
 
   /// Build a new object-construction expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildCXXUnresolvedConstructExpr(TypeSourceInfo *TSInfo,
                                                SourceLocation LParenLoc,
                                                MultiExprArg Args,
                                                SourceLocation RParenLoc,
                                                bool ListInitialization) {
     return getSema().BuildCXXTypeConstructExpr(TSInfo, LParenLoc, Args,
                                                RParenLoc, ListInitialization);
   }
 
   /// Build a new member reference expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildCXXDependentScopeMemberExpr(Expr *BaseE,
                                                 QualType BaseType,
                                                 bool IsArrow,
                                                 SourceLocation OperatorLoc,
                                           NestedNameSpecifierLoc QualifierLoc,
                                                 SourceLocation TemplateKWLoc,
                                             NamedDecl *FirstQualifierInScope,
                                    const DeclarationNameInfo &MemberNameInfo,
                               const TemplateArgumentListInfo *TemplateArgs) {
     CXXScopeSpec SS;
     SS.Adopt(QualifierLoc);
 
     return SemaRef.BuildMemberReferenceExpr(BaseE, BaseType,
                                             OperatorLoc, IsArrow,
                                             SS, TemplateKWLoc,
                                             FirstQualifierInScope,
                                             MemberNameInfo,
                                             TemplateArgs, /*S*/nullptr);
   }
 
   /// Build a new member reference expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildUnresolvedMemberExpr(Expr *BaseE, QualType BaseType,
                                          SourceLocation OperatorLoc,
                                          bool IsArrow,
                                          NestedNameSpecifierLoc QualifierLoc,
                                          SourceLocation TemplateKWLoc,
                                          NamedDecl *FirstQualifierInScope,
                                          LookupResult &R,
                                 const TemplateArgumentListInfo *TemplateArgs) {
     CXXScopeSpec SS;
     SS.Adopt(QualifierLoc);
 
     return SemaRef.BuildMemberReferenceExpr(BaseE, BaseType,
                                             OperatorLoc, IsArrow,
                                             SS, TemplateKWLoc,
                                             FirstQualifierInScope,
                                             R, TemplateArgs, /*S*/nullptr);
   }
 
   /// Build a new noexcept expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildCXXNoexceptExpr(SourceRange Range, Expr *Arg) {
     return SemaRef.BuildCXXNoexceptExpr(Range.getBegin(), Arg, Range.getEnd());
   }
 
   /// Build a new expression to compute the length of a parameter pack.
   ExprResult RebuildSizeOfPackExpr(SourceLocation OperatorLoc, NamedDecl *Pack,
                                    SourceLocation PackLoc,
                                    SourceLocation RParenLoc,
                                    std::optional<unsigned> Length,
                                    ArrayRef<TemplateArgument> PartialArgs) {
     return SizeOfPackExpr::Create(SemaRef.Context, OperatorLoc, Pack, PackLoc,
                                   RParenLoc, Length, PartialArgs);
   }
 
   /// Build a new expression representing a call to a source location
   ///  builtin.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildSourceLocExpr(SourceLocExpr::IdentKind Kind,
                                   QualType ResultTy, SourceLocation BuiltinLoc,
                                   SourceLocation RPLoc,
                                   DeclContext *ParentContext) {
     return getSema().BuildSourceLocExpr(Kind, ResultTy, BuiltinLoc, RPLoc,
                                         ParentContext);
   }
 
   /// Build a new Objective-C boxed expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildConceptSpecializationExpr(NestedNameSpecifierLoc NNS,
       SourceLocation TemplateKWLoc, DeclarationNameInfo ConceptNameInfo,
       NamedDecl *FoundDecl, ConceptDecl *NamedConcept,
       TemplateArgumentListInfo *TALI) {
     CXXScopeSpec SS;
     SS.Adopt(NNS);
     ExprResult Result = getSema().CheckConceptTemplateId(SS, TemplateKWLoc,
                                                          ConceptNameInfo,
                                                          FoundDecl,
                                                          NamedConcept, TALI);
     if (Result.isInvalid())
       return ExprError();
     return Result;
   }
 
   /// \brief Build a new requires expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildRequiresExpr(SourceLocation RequiresKWLoc,
                                  RequiresExprBodyDecl *Body,
                                  ArrayRef<ParmVarDecl *> LocalParameters,
                                  ArrayRef<concepts::Requirement *> Requirements,
                                  SourceLocation ClosingBraceLoc) {
     return RequiresExpr::Create(SemaRef.Context, RequiresKWLoc, Body,
                                 LocalParameters, Requirements, ClosingBraceLoc);
   }
 
   concepts::TypeRequirement *
   RebuildTypeRequirement(
       concepts::Requirement::SubstitutionDiagnostic *SubstDiag) {
     return SemaRef.BuildTypeRequirement(SubstDiag);
   }
 
   concepts::TypeRequirement *RebuildTypeRequirement(TypeSourceInfo *T) {
     return SemaRef.BuildTypeRequirement(T);
   }
 
   concepts::ExprRequirement *
   RebuildExprRequirement(
       concepts::Requirement::SubstitutionDiagnostic *SubstDiag, bool IsSimple,
       SourceLocation NoexceptLoc,
       concepts::ExprRequirement::ReturnTypeRequirement Ret) {
     return SemaRef.BuildExprRequirement(SubstDiag, IsSimple, NoexceptLoc,
                                         std::move(Ret));
   }
 
   concepts::ExprRequirement *
   RebuildExprRequirement(Expr *E, bool IsSimple, SourceLocation NoexceptLoc,
                          concepts::ExprRequirement::ReturnTypeRequirement Ret) {
     return SemaRef.BuildExprRequirement(E, IsSimple, NoexceptLoc,
                                         std::move(Ret));
   }
 
   concepts::NestedRequirement *
   RebuildNestedRequirement(StringRef InvalidConstraintEntity,
                            const ASTConstraintSatisfaction &Satisfaction) {
     return SemaRef.BuildNestedRequirement(InvalidConstraintEntity,
                                           Satisfaction);
   }
 
   concepts::NestedRequirement *RebuildNestedRequirement(Expr *Constraint) {
     return SemaRef.BuildNestedRequirement(Constraint);
   }
 
   /// \brief Build a new Objective-C boxed expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildObjCBoxedExpr(SourceRange SR, Expr *ValueExpr) {
     return getSema().BuildObjCBoxedExpr(SR, ValueExpr);
   }
 
   /// Build a new Objective-C array literal.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildObjCArrayLiteral(SourceRange Range,
                                      Expr **Elements, unsigned NumElements) {
     return getSema().BuildObjCArrayLiteral(Range,
                                            MultiExprArg(Elements, NumElements));
   }
 
   ExprResult RebuildObjCSubscriptRefExpr(SourceLocation RB,
                                          Expr *Base, Expr *Key,
                                          ObjCMethodDecl *getterMethod,
                                          ObjCMethodDecl *setterMethod) {
     return  getSema().BuildObjCSubscriptExpression(RB, Base, Key,
                                                    getterMethod, setterMethod);
   }
 
   /// Build a new Objective-C dictionary literal.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildObjCDictionaryLiteral(SourceRange Range,
                               MutableArrayRef<ObjCDictionaryElement> Elements) {
     return getSema().BuildObjCDictionaryLiteral(Range, Elements);
   }
 
   /// Build a new Objective-C \@encode expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildObjCEncodeExpr(SourceLocation AtLoc,
                                          TypeSourceInfo *EncodeTypeInfo,
                                          SourceLocation RParenLoc) {
     return SemaRef.BuildObjCEncodeExpression(AtLoc, EncodeTypeInfo, RParenLoc);
   }
 
   /// Build a new Objective-C class message.
   ExprResult RebuildObjCMessageExpr(TypeSourceInfo *ReceiverTypeInfo,
                                           Selector Sel,
                                           ArrayRef<SourceLocation> SelectorLocs,
                                           ObjCMethodDecl *Method,
                                           SourceLocation LBracLoc,
                                           MultiExprArg Args,
                                           SourceLocation RBracLoc) {
     return SemaRef.BuildClassMessage(ReceiverTypeInfo,
                                      ReceiverTypeInfo->getType(),
                                      /*SuperLoc=*/SourceLocation(),
                                      Sel, Method, LBracLoc, SelectorLocs,
                                      RBracLoc, Args);
   }
 
   /// Build a new Objective-C instance message.
   ExprResult RebuildObjCMessageExpr(Expr *Receiver,
                                           Selector Sel,
                                           ArrayRef<SourceLocation> SelectorLocs,
                                           ObjCMethodDecl *Method,
                                           SourceLocation LBracLoc,
                                           MultiExprArg Args,
                                           SourceLocation RBracLoc) {
     return SemaRef.BuildInstanceMessage(Receiver,
                                         Receiver->getType(),
                                         /*SuperLoc=*/SourceLocation(),
                                         Sel, Method, LBracLoc, SelectorLocs,
                                         RBracLoc, Args);
   }
 
   /// Build a new Objective-C instance/class message to 'super'.
   ExprResult RebuildObjCMessageExpr(SourceLocation SuperLoc,
                                     Selector Sel,
                                     ArrayRef<SourceLocation> SelectorLocs,
                                     QualType SuperType,
                                     ObjCMethodDecl *Method,
                                     SourceLocation LBracLoc,
                                     MultiExprArg Args,
                                     SourceLocation RBracLoc) {
     return Method->isInstanceMethod() ? SemaRef.BuildInstanceMessage(nullptr,
                                           SuperType,
                                           SuperLoc,
                                           Sel, Method, LBracLoc, SelectorLocs,
                                           RBracLoc, Args)
                                       : SemaRef.BuildClassMessage(nullptr,
                                           SuperType,
                                           SuperLoc,
                                           Sel, Method, LBracLoc, SelectorLocs,
                                           RBracLoc, Args);
 
 
   }
 
   /// Build a new Objective-C ivar reference expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildObjCIvarRefExpr(Expr *BaseArg, ObjCIvarDecl *Ivar,
                                           SourceLocation IvarLoc,
                                           bool IsArrow, bool IsFreeIvar) {
     CXXScopeSpec SS;
     DeclarationNameInfo NameInfo(Ivar->getDeclName(), IvarLoc);
     ExprResult Result = getSema().BuildMemberReferenceExpr(
         BaseArg, BaseArg->getType(),
         /*FIXME:*/ IvarLoc, IsArrow, SS, SourceLocation(),
         /*FirstQualifierInScope=*/nullptr, NameInfo,
         /*TemplateArgs=*/nullptr,
         /*S=*/nullptr);
     if (IsFreeIvar && Result.isUsable())
       cast<ObjCIvarRefExpr>(Result.get())->setIsFreeIvar(IsFreeIvar);
     return Result;
   }
 
   /// Build a new Objective-C property reference expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildObjCPropertyRefExpr(Expr *BaseArg,
                                         ObjCPropertyDecl *Property,
                                         SourceLocation PropertyLoc) {
     CXXScopeSpec SS;
     DeclarationNameInfo NameInfo(Property->getDeclName(), PropertyLoc);
     return getSema().BuildMemberReferenceExpr(BaseArg, BaseArg->getType(),
                                               /*FIXME:*/PropertyLoc,
                                               /*IsArrow=*/false,
                                               SS, SourceLocation(),
                                               /*FirstQualifierInScope=*/nullptr,
                                               NameInfo,
                                               /*TemplateArgs=*/nullptr,
                                               /*S=*/nullptr);
   }
 
   /// Build a new Objective-C property reference expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildObjCPropertyRefExpr(Expr *Base, QualType T,
                                         ObjCMethodDecl *Getter,
                                         ObjCMethodDecl *Setter,
                                         SourceLocation PropertyLoc) {
     // Since these expressions can only be value-dependent, we do not
     // need to perform semantic analysis again.
     return Owned(
       new (getSema().Context) ObjCPropertyRefExpr(Getter, Setter, T,
                                                   VK_LValue, OK_ObjCProperty,
                                                   PropertyLoc, Base));
   }
 
   /// Build a new Objective-C "isa" expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildObjCIsaExpr(Expr *BaseArg, SourceLocation IsaLoc,
                                 SourceLocation OpLoc, bool IsArrow) {
     CXXScopeSpec SS;
     DeclarationNameInfo NameInfo(&getSema().Context.Idents.get("isa"), IsaLoc);
     return getSema().BuildMemberReferenceExpr(BaseArg, BaseArg->getType(),
                                               OpLoc, IsArrow,
                                               SS, SourceLocation(),
                                               /*FirstQualifierInScope=*/nullptr,
                                               NameInfo,
                                               /*TemplateArgs=*/nullptr,
                                               /*S=*/nullptr);
   }
 
   /// Build a new shuffle vector expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildShuffleVectorExpr(SourceLocation BuiltinLoc,
                                       MultiExprArg SubExprs,
                                       SourceLocation RParenLoc) {
     // Find the declaration for __builtin_shufflevector
     const IdentifierInfo &Name
       = SemaRef.Context.Idents.get("__builtin_shufflevector");
     TranslationUnitDecl *TUDecl = SemaRef.Context.getTranslationUnitDecl();
     DeclContext::lookup_result Lookup = TUDecl->lookup(DeclarationName(&Name));
     assert(!Lookup.empty() && "No __builtin_shufflevector?");
 
     // Build a reference to the __builtin_shufflevector builtin
     FunctionDecl *Builtin = cast<FunctionDecl>(Lookup.front());
     Expr *Callee = new (SemaRef.Context)
         DeclRefExpr(SemaRef.Context, Builtin, false,
                     SemaRef.Context.BuiltinFnTy, VK_PRValue, BuiltinLoc);
     QualType CalleePtrTy = SemaRef.Context.getPointerType(Builtin->getType());
     Callee = SemaRef.ImpCastExprToType(Callee, CalleePtrTy,
                                        CK_BuiltinFnToFnPtr).get();
 
     // Build the CallExpr
     ExprResult TheCall = CallExpr::Create(
         SemaRef.Context, Callee, SubExprs, Builtin->getCallResultType(),
         Expr::getValueKindForType(Builtin->getReturnType()), RParenLoc,
         FPOptionsOverride());
 
     // Type-check the __builtin_shufflevector expression.
     return SemaRef.SemaBuiltinShuffleVector(cast<CallExpr>(TheCall.get()));
   }
 
   /// Build a new convert vector expression.
   ExprResult RebuildConvertVectorExpr(SourceLocation BuiltinLoc,
                                       Expr *SrcExpr, TypeSourceInfo *DstTInfo,
                                       SourceLocation RParenLoc) {
     return SemaRef.SemaConvertVectorExpr(SrcExpr, DstTInfo,
                                          BuiltinLoc, RParenLoc);
   }
 
   /// Build a new template argument pack expansion.
   ///
   /// By default, performs semantic analysis to build a new pack expansion
   /// for a template argument. Subclasses may override this routine to provide
   /// different behavior.
   TemplateArgumentLoc
   RebuildPackExpansion(TemplateArgumentLoc Pattern, SourceLocation EllipsisLoc,
                        std::optional<unsigned> NumExpansions) {
     switch (Pattern.getArgument().getKind()) {
     case TemplateArgument::Expression: {
       ExprResult Result
         = getSema().CheckPackExpansion(Pattern.getSourceExpression(),
                                        EllipsisLoc, NumExpansions);
       if (Result.isInvalid())
         return TemplateArgumentLoc();
 
       return TemplateArgumentLoc(Result.get(), Result.get());
     }
 
     case TemplateArgument::Template:
       return TemplateArgumentLoc(
           SemaRef.Context,
           TemplateArgument(Pattern.getArgument().getAsTemplate(),
                            NumExpansions),
           Pattern.getTemplateQualifierLoc(), Pattern.getTemplateNameLoc(),
           EllipsisLoc);
 
     case TemplateArgument::Null:
     case TemplateArgument::Integral:
     case TemplateArgument::Declaration:
     case TemplateArgument::Pack:
     case TemplateArgument::TemplateExpansion:
     case TemplateArgument::NullPtr:
       llvm_unreachable("Pack expansion pattern has no parameter packs");
 
     case TemplateArgument::Type:
       if (TypeSourceInfo *Expansion
             = getSema().CheckPackExpansion(Pattern.getTypeSourceInfo(),
                                            EllipsisLoc,
                                            NumExpansions))
         return TemplateArgumentLoc(TemplateArgument(Expansion->getType()),
                                    Expansion);
       break;
     }
 
     return TemplateArgumentLoc();
   }
 
   /// Build a new expression pack expansion.
   ///
   /// By default, performs semantic analysis to build a new pack expansion
   /// for an expression. Subclasses may override this routine to provide
   /// different behavior.
   ExprResult RebuildPackExpansion(Expr *Pattern, SourceLocation EllipsisLoc,
                                   std::optional<unsigned> NumExpansions) {
     return getSema().CheckPackExpansion(Pattern, EllipsisLoc, NumExpansions);
   }
 
   /// Build a new C++1z fold-expression.
   ///
   /// By default, performs semantic analysis in order to build a new fold
   /// expression.
   ExprResult RebuildCXXFoldExpr(UnresolvedLookupExpr *ULE,
                                 SourceLocation LParenLoc, Expr *LHS,
                                 BinaryOperatorKind Operator,
                                 SourceLocation EllipsisLoc, Expr *RHS,
                                 SourceLocation RParenLoc,
                                 std::optional<unsigned> NumExpansions) {
     return getSema().BuildCXXFoldExpr(ULE, LParenLoc, LHS, Operator,
                                       EllipsisLoc, RHS, RParenLoc,
                                       NumExpansions);
   }
 
   /// Build an empty C++1z fold-expression with the given operator.
   ///
   /// By default, produces the fallback value for the fold-expression, or
   /// produce an error if there is no fallback value.
   ExprResult RebuildEmptyCXXFoldExpr(SourceLocation EllipsisLoc,
                                      BinaryOperatorKind Operator) {
     return getSema().BuildEmptyCXXFoldExpr(EllipsisLoc, Operator);
   }
 
   /// Build a new atomic operation expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
   /// Subclasses may override this routine to provide different behavior.
   ExprResult RebuildAtomicExpr(SourceLocation BuiltinLoc, MultiExprArg SubExprs,
                                AtomicExpr::AtomicOp Op,
                                SourceLocation RParenLoc) {
     // Use this for all of the locations, since we don't know the difference
     // between the call and the expr at this point.
     SourceRange Range{BuiltinLoc, RParenLoc};
     return getSema().BuildAtomicExpr(Range, Range, RParenLoc, SubExprs, Op,
                                      Sema::AtomicArgumentOrder::AST);
   }
 
   ExprResult RebuildRecoveryExpr(SourceLocation BeginLoc, SourceLocation EndLoc,
                                  ArrayRef<Expr *> SubExprs, QualType Type) {
     return getSema().CreateRecoveryExpr(BeginLoc, EndLoc, SubExprs, Type);
   }
 
 private:
   TypeLoc TransformTypeInObjectScope(TypeLoc TL,
                                      QualType ObjectType,
                                      NamedDecl *FirstQualifierInScope,
                                      CXXScopeSpec &SS);
 
   TypeSourceInfo *TransformTypeInObjectScope(TypeSourceInfo *TSInfo,
                                              QualType ObjectType,
                                              NamedDecl *FirstQualifierInScope,
                                              CXXScopeSpec &SS);
 
   TypeSourceInfo *TransformTSIInObjectScope(TypeLoc TL, QualType ObjectType,
                                             NamedDecl *FirstQualifierInScope,
                                             CXXScopeSpec &SS);
 
   QualType TransformDependentNameType(TypeLocBuilder &TLB,
                                       DependentNameTypeLoc TL,
                                       bool DeducibleTSTContext);
 };
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformStmt(Stmt *S, StmtDiscardKind SDK) {
   if (!S)
     return S;
 
   switch (S->getStmtClass()) {
   case Stmt::NoStmtClass: break;
 
   // Transform individual statement nodes
   // Pass SDK into statements that can produce a value
 #define STMT(Node, Parent)                                              \
   case Stmt::Node##Class: return getDerived().Transform##Node(cast<Node>(S));
 #define VALUESTMT(Node, Parent)                                         \
   case Stmt::Node##Class:                                               \
     return getDerived().Transform##Node(cast<Node>(S), SDK);
 #define ABSTRACT_STMT(Node)
 #define EXPR(Node, Parent)
 #include "clang/AST/StmtNodes.inc"
 
   // Transform expressions by calling TransformExpr.
 #define STMT(Node, Parent)
 #define ABSTRACT_STMT(Stmt)
 #define EXPR(Node, Parent) case Stmt::Node##Class:
 #include "clang/AST/StmtNodes.inc"
     {
       ExprResult E = getDerived().TransformExpr(cast<Expr>(S));
 
       if (SDK == SDK_StmtExprResult)
         E = getSema().ActOnStmtExprResult(E);
       return getSema().ActOnExprStmt(E, SDK == SDK_Discarded);
     }
   }
 
   return S;
 }
 
 template<typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPClause(OMPClause *S) {
   if (!S)
     return S;
 
   switch (S->getClauseKind()) {
   default: break;
   // Transform individual clause nodes
 #define GEN_CLANG_CLAUSE_CLASS
 #define CLAUSE_CLASS(Enum, Str, Class)                                         \
   case Enum:                                                                   \
     return getDerived().Transform##Class(cast<Class>(S));
 #include "llvm/Frontend/OpenMP/OMP.inc"
   }
 
   return S;
 }
 
 
 template<typename Derived>
 ExprResult TreeTransform<Derived>::TransformExpr(Expr *E) {
   if (!E)
     return E;
 
   switch (E->getStmtClass()) {
     case Stmt::NoStmtClass: break;
 #define STMT(Node, Parent) case Stmt::Node##Class: break;
 #define ABSTRACT_STMT(Stmt)
 #define EXPR(Node, Parent)                                              \
     case Stmt::Node##Class: return getDerived().Transform##Node(cast<Node>(E));
 #include "clang/AST/StmtNodes.inc"
   }
 
   return E;
 }
 
 template<typename Derived>
 ExprResult TreeTransform<Derived>::TransformInitializer(Expr *Init,
                                                         bool NotCopyInit) {
   // Initializers are instantiated like expressions, except that various outer
   // layers are stripped.
   if (!Init)
     return Init;
 
   if (auto *FE = dyn_cast<FullExpr>(Init))
     Init = FE->getSubExpr();
 
   if (auto *AIL = dyn_cast<ArrayInitLoopExpr>(Init)) {
     OpaqueValueExpr *OVE = AIL->getCommonExpr();
     Init = OVE->getSourceExpr();
   }
 
   if (MaterializeTemporaryExpr *MTE = dyn_cast<MaterializeTemporaryExpr>(Init))
     Init = MTE->getSubExpr();
 
   while (CXXBindTemporaryExpr *Binder = dyn_cast<CXXBindTemporaryExpr>(Init))
     Init = Binder->getSubExpr();
 
   if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Init))
     Init = ICE->getSubExprAsWritten();
 
   if (CXXStdInitializerListExpr *ILE =
           dyn_cast<CXXStdInitializerListExpr>(Init))
     return TransformInitializer(ILE->getSubExpr(), NotCopyInit);
 
   // If this is copy-initialization, we only need to reconstruct
   // InitListExprs. Other forms of copy-initialization will be a no-op if
   // the initializer is already the right type.
   CXXConstructExpr *Construct = dyn_cast<CXXConstructExpr>(Init);
   if (!NotCopyInit && !(Construct && Construct->isListInitialization()))
     return getDerived().TransformExpr(Init);
 
   // Revert value-initialization back to empty parens.
   if (CXXScalarValueInitExpr *VIE = dyn_cast<CXXScalarValueInitExpr>(Init)) {
     SourceRange Parens = VIE->getSourceRange();
     return getDerived().RebuildParenListExpr(Parens.getBegin(), std::nullopt,
                                              Parens.getEnd());
   }
 
   // FIXME: We shouldn't build ImplicitValueInitExprs for direct-initialization.
   if (isa<ImplicitValueInitExpr>(Init))
     return getDerived().RebuildParenListExpr(SourceLocation(), std::nullopt,
                                              SourceLocation());
 
   // Revert initialization by constructor back to a parenthesized or braced list
   // of expressions. Any other form of initializer can just be reused directly.
   if (!Construct || isa<CXXTemporaryObjectExpr>(Construct))
     return getDerived().TransformExpr(Init);
 
   // If the initialization implicitly converted an initializer list to a
   // std::initializer_list object, unwrap the std::initializer_list too.
   if (Construct && Construct->isStdInitListInitialization())
     return TransformInitializer(Construct->getArg(0), NotCopyInit);
 
   // Enter a list-init context if this was list initialization.
   EnterExpressionEvaluationContext Context(
       getSema(), EnterExpressionEvaluationContext::InitList,
       Construct->isListInitialization());
 
   SmallVector<Expr*, 8> NewArgs;
   bool ArgChanged = false;
   if (getDerived().TransformExprs(Construct->getArgs(), Construct->getNumArgs(),
                                   /*IsCall*/true, NewArgs, &ArgChanged))
     return ExprError();
 
   // If this was list initialization, revert to syntactic list form.
   if (Construct->isListInitialization())
     return getDerived().RebuildInitList(Construct->getBeginLoc(), NewArgs,
                                         Construct->getEndLoc());
 
   // Build a ParenListExpr to represent anything else.
   SourceRange Parens = Construct->getParenOrBraceRange();
   if (Parens.isInvalid()) {
     // This was a variable declaration's initialization for which no initializer
     // was specified.
     assert(NewArgs.empty() &&
            "no parens or braces but have direct init with arguments?");
     return ExprEmpty();
   }
   return getDerived().RebuildParenListExpr(Parens.getBegin(), NewArgs,
                                            Parens.getEnd());
 }
 
 template<typename Derived>
 bool TreeTransform<Derived>::TransformExprs(Expr *const *Inputs,
                                             unsigned NumInputs,
                                             bool IsCall,
                                       SmallVectorImpl<Expr *> &Outputs,
                                             bool *ArgChanged) {
   for (unsigned I = 0; I != NumInputs; ++I) {
     // If requested, drop call arguments that need to be dropped.
     if (IsCall && getDerived().DropCallArgument(Inputs[I])) {
       if (ArgChanged)
         *ArgChanged = true;
 
       break;
     }
 
     if (PackExpansionExpr *Expansion = dyn_cast<PackExpansionExpr>(Inputs[I])) {
       Expr *Pattern = Expansion->getPattern();
 
       SmallVector<UnexpandedParameterPack, 2> Unexpanded;
       getSema().collectUnexpandedParameterPacks(Pattern, Unexpanded);
       assert(!Unexpanded.empty() && "Pack expansion without parameter packs?");
 
       // Determine whether the set of unexpanded parameter packs can and should
       // be expanded.
       bool Expand = true;
       bool RetainExpansion = false;
       std::optional<unsigned> OrigNumExpansions = Expansion->getNumExpansions();
       std::optional<unsigned> NumExpansions = OrigNumExpansions;
       if (getDerived().TryExpandParameterPacks(Expansion->getEllipsisLoc(),
                                                Pattern->getSourceRange(),
                                                Unexpanded,
                                                Expand, RetainExpansion,
                                                NumExpansions))
         return true;
 
       if (!Expand) {
         // The transform has determined that we should perform a simple
         // transformation on the pack expansion, producing another pack
         // expansion.
         Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(getSema(), -1);
         ExprResult OutPattern = getDerived().TransformExpr(Pattern);
         if (OutPattern.isInvalid())
           return true;
 
         ExprResult Out = getDerived().RebuildPackExpansion(OutPattern.get(),
                                                 Expansion->getEllipsisLoc(),
                                                            NumExpansions);
         if (Out.isInvalid())
           return true;
 
         if (ArgChanged)
           *ArgChanged = true;
         Outputs.push_back(Out.get());
         continue;
       }
 
       // Record right away that the argument was changed.  This needs
       // to happen even if the array expands to nothing.
       if (ArgChanged) *ArgChanged = true;
 
       // The transform has determined that we should perform an elementwise
       // expansion of the pattern. Do so.
       for (unsigned I = 0; I != *NumExpansions; ++I) {
         Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(getSema(), I);
         ExprResult Out = getDerived().TransformExpr(Pattern);
         if (Out.isInvalid())
           return true;
 
         if (Out.get()->containsUnexpandedParameterPack()) {
           Out = getDerived().RebuildPackExpansion(
               Out.get(), Expansion->getEllipsisLoc(), OrigNumExpansions);
           if (Out.isInvalid())
             return true;
         }
 
         Outputs.push_back(Out.get());
       }
 
       // If we're supposed to retain a pack expansion, do so by temporarily
       // forgetting the partially-substituted parameter pack.
       if (RetainExpansion) {
         ForgetPartiallySubstitutedPackRAII Forget(getDerived());
 
         ExprResult Out = getDerived().TransformExpr(Pattern);
         if (Out.isInvalid())
           return true;
 
         Out = getDerived().RebuildPackExpansion(
             Out.get(), Expansion->getEllipsisLoc(), OrigNumExpansions);
         if (Out.isInvalid())
           return true;
 
         Outputs.push_back(Out.get());
       }
 
       continue;
     }
 
     ExprResult Result =
       IsCall ? getDerived().TransformInitializer(Inputs[I], /*DirectInit*/false)
              : getDerived().TransformExpr(Inputs[I]);
     if (Result.isInvalid())
       return true;
 
     if (Result.get() != Inputs[I] && ArgChanged)
       *ArgChanged = true;
 
     Outputs.push_back(Result.get());
   }
 
   return false;
 }
 
 template <typename Derived>
 Sema::ConditionResult TreeTransform<Derived>::TransformCondition(
     SourceLocation Loc, VarDecl *Var, Expr *Expr, Sema::ConditionKind Kind) {
   if (Var) {
     VarDecl *ConditionVar = cast_or_null<VarDecl>(
         getDerived().TransformDefinition(Var->getLocation(), Var));
 
     if (!ConditionVar)
       return Sema::ConditionError();
 
     return getSema().ActOnConditionVariable(ConditionVar, Loc, Kind);
   }
 
   if (Expr) {
     ExprResult CondExpr = getDerived().TransformExpr(Expr);
 
     if (CondExpr.isInvalid())
       return Sema::ConditionError();
 
     return getSema().ActOnCondition(nullptr, Loc, CondExpr.get(), Kind,
                                     /*MissingOK=*/true);
   }
 
   return Sema::ConditionResult();
 }
 
 template <typename Derived>
 NestedNameSpecifierLoc TreeTransform<Derived>::TransformNestedNameSpecifierLoc(
     NestedNameSpecifierLoc NNS, QualType ObjectType,
     NamedDecl *FirstQualifierInScope) {
   SmallVector<NestedNameSpecifierLoc, 4> Qualifiers;
 
   auto insertNNS = [&Qualifiers](NestedNameSpecifierLoc NNS) {
     for (NestedNameSpecifierLoc Qualifier = NNS; Qualifier;
          Qualifier = Qualifier.getPrefix())
       Qualifiers.push_back(Qualifier);
   };
   insertNNS(NNS);
 
   CXXScopeSpec SS;
   while (!Qualifiers.empty()) {
     NestedNameSpecifierLoc Q = Qualifiers.pop_back_val();
     NestedNameSpecifier *QNNS = Q.getNestedNameSpecifier();
 
     switch (QNNS->getKind()) {
     case NestedNameSpecifier::Identifier: {
       Sema::NestedNameSpecInfo IdInfo(QNNS->getAsIdentifier(),
                                       Q.getLocalBeginLoc(), Q.getLocalEndLoc(),
                                       ObjectType);
       if (SemaRef.BuildCXXNestedNameSpecifier(/*Scope=*/nullptr, IdInfo, false,
                                               SS, FirstQualifierInScope, false))
         return NestedNameSpecifierLoc();
       break;
     }
 
     case NestedNameSpecifier::Namespace: {
       NamespaceDecl *NS =
           cast_or_null<NamespaceDecl>(getDerived().TransformDecl(
               Q.getLocalBeginLoc(), QNNS->getAsNamespace()));
       SS.Extend(SemaRef.Context, NS, Q.getLocalBeginLoc(), Q.getLocalEndLoc());
       break;
     }
 
     case NestedNameSpecifier::NamespaceAlias: {
       NamespaceAliasDecl *Alias =
           cast_or_null<NamespaceAliasDecl>(getDerived().TransformDecl(
               Q.getLocalBeginLoc(), QNNS->getAsNamespaceAlias()));
       SS.Extend(SemaRef.Context, Alias, Q.getLocalBeginLoc(),
                 Q.getLocalEndLoc());
       break;
     }
 
     case NestedNameSpecifier::Global:
       // There is no meaningful transformation that one could perform on the
       // global scope.
       SS.MakeGlobal(SemaRef.Context, Q.getBeginLoc());
       break;
 
     case NestedNameSpecifier::Super: {
       CXXRecordDecl *RD =
           cast_or_null<CXXRecordDecl>(getDerived().TransformDecl(
               SourceLocation(), QNNS->getAsRecordDecl()));
       SS.MakeSuper(SemaRef.Context, RD, Q.getBeginLoc(), Q.getEndLoc());
       break;
     }
 
     case NestedNameSpecifier::TypeSpecWithTemplate:
     case NestedNameSpecifier::TypeSpec: {
       TypeLoc TL = TransformTypeInObjectScope(Q.getTypeLoc(), ObjectType,
                                               FirstQualifierInScope, SS);
 
       if (!TL)
         return NestedNameSpecifierLoc();
 
       QualType T = TL.getType();
       if (T->isDependentType() || T->isRecordType() ||
           (SemaRef.getLangOpts().CPlusPlus11 && T->isEnumeralType())) {
         if (T->isEnumeralType())
           SemaRef.Diag(TL.getBeginLoc(),
                        diag::warn_cxx98_compat_enum_nested_name_spec);
 
         if (const auto ETL = TL.getAs<ElaboratedTypeLoc>()) {
           SS.Adopt(ETL.getQualifierLoc());
           TL = ETL.getNamedTypeLoc();
         }
         SS.Extend(SemaRef.Context, /*FIXME:*/ SourceLocation(), TL,
                   Q.getLocalEndLoc());
         break;
       }
       // If the nested-name-specifier is an invalid type def, don't emit an
       // error because a previous error should have already been emitted.
       TypedefTypeLoc TTL = TL.getAsAdjusted<TypedefTypeLoc>();
       if (!TTL || !TTL.getTypedefNameDecl()->isInvalidDecl()) {
         SemaRef.Diag(TL.getBeginLoc(), diag::err_nested_name_spec_non_tag)
             << T << SS.getRange();
       }
       return NestedNameSpecifierLoc();
     }
     }
 
     // The qualifier-in-scope and object type only apply to the leftmost entity.
     FirstQualifierInScope = nullptr;
     ObjectType = QualType();
   }
 
   // Don't rebuild the nested-name-specifier if we don't have to.
   if (SS.getScopeRep() == NNS.getNestedNameSpecifier() &&
       !getDerived().AlwaysRebuild())
     return NNS;
 
   // If we can re-use the source-location data from the original
   // nested-name-specifier, do so.
   if (SS.location_size() == NNS.getDataLength() &&
       memcmp(SS.location_data(), NNS.getOpaqueData(), SS.location_size()) == 0)
     return NestedNameSpecifierLoc(SS.getScopeRep(), NNS.getOpaqueData());
 
   // Allocate new nested-name-specifier location information.
   return SS.getWithLocInContext(SemaRef.Context);
 }
 
 template<typename Derived>
 DeclarationNameInfo
 TreeTransform<Derived>
 ::TransformDeclarationNameInfo(const DeclarationNameInfo &NameInfo) {
   DeclarationName Name = NameInfo.getName();
   if (!Name)
     return DeclarationNameInfo();
 
   switch (Name.getNameKind()) {
   case DeclarationName::Identifier:
   case DeclarationName::ObjCZeroArgSelector:
   case DeclarationName::ObjCOneArgSelector:
   case DeclarationName::ObjCMultiArgSelector:
   case DeclarationName::CXXOperatorName:
   case DeclarationName::CXXLiteralOperatorName:
   case DeclarationName::CXXUsingDirective:
     return NameInfo;
 
   case DeclarationName::CXXDeductionGuideName: {
     TemplateDecl *OldTemplate = Name.getCXXDeductionGuideTemplate();
     TemplateDecl *NewTemplate = cast_or_null<TemplateDecl>(
         getDerived().TransformDecl(NameInfo.getLoc(), OldTemplate));
     if (!NewTemplate)
       return DeclarationNameInfo();
 
     DeclarationNameInfo NewNameInfo(NameInfo);
     NewNameInfo.setName(
         SemaRef.Context.DeclarationNames.getCXXDeductionGuideName(NewTemplate));
     return NewNameInfo;
   }
 
   case DeclarationName::CXXConstructorName:
   case DeclarationName::CXXDestructorName:
   case DeclarationName::CXXConversionFunctionName: {
     TypeSourceInfo *NewTInfo;
     CanQualType NewCanTy;
     if (TypeSourceInfo *OldTInfo = NameInfo.getNamedTypeInfo()) {
       NewTInfo = getDerived().TransformType(OldTInfo);
       if (!NewTInfo)
         return DeclarationNameInfo();
       NewCanTy = SemaRef.Context.getCanonicalType(NewTInfo->getType());
     }
     else {
       NewTInfo = nullptr;
       TemporaryBase Rebase(*this, NameInfo.getLoc(), Name);
       QualType NewT = getDerived().TransformType(Name.getCXXNameType());
       if (NewT.isNull())
         return DeclarationNameInfo();
       NewCanTy = SemaRef.Context.getCanonicalType(NewT);
     }
 
     DeclarationName NewName
       = SemaRef.Context.DeclarationNames.getCXXSpecialName(Name.getNameKind(),
                                                            NewCanTy);
     DeclarationNameInfo NewNameInfo(NameInfo);
     NewNameInfo.setName(NewName);
     NewNameInfo.setNamedTypeInfo(NewTInfo);
     return NewNameInfo;
   }
   }
 
   llvm_unreachable("Unknown name kind.");
 }
 
 template<typename Derived>
 TemplateName
 TreeTransform<Derived>::TransformTemplateName(CXXScopeSpec &SS,
                                               TemplateName Name,
                                               SourceLocation NameLoc,
                                               QualType ObjectType,
                                               NamedDecl *FirstQualifierInScope,
                                               bool AllowInjectedClassName) {
   if (QualifiedTemplateName *QTN = Name.getAsQualifiedTemplateName()) {
     TemplateDecl *Template = QTN->getUnderlyingTemplate().getAsTemplateDecl();
     assert(Template && "qualified template name must refer to a template");
 
     TemplateDecl *TransTemplate
       = cast_or_null<TemplateDecl>(getDerived().TransformDecl(NameLoc,
                                                               Template));
     if (!TransTemplate)
       return TemplateName();
 
     if (!getDerived().AlwaysRebuild() &&
         SS.getScopeRep() == QTN->getQualifier() &&
         TransTemplate == Template)
       return Name;
 
     return getDerived().RebuildTemplateName(SS, QTN->hasTemplateKeyword(),
                                             TransTemplate);
   }
 
   if (DependentTemplateName *DTN = Name.getAsDependentTemplateName()) {
     if (SS.getScopeRep()) {
       // These apply to the scope specifier, not the template.
       ObjectType = QualType();
       FirstQualifierInScope = nullptr;
     }
 
     if (!getDerived().AlwaysRebuild() &&
         SS.getScopeRep() == DTN->getQualifier() &&
         ObjectType.isNull())
       return Name;
 
     // FIXME: Preserve the location of the "template" keyword.
     SourceLocation TemplateKWLoc = NameLoc;
 
     if (DTN->isIdentifier()) {
       return getDerived().RebuildTemplateName(SS,
                                               TemplateKWLoc,
                                               *DTN->getIdentifier(),
                                               NameLoc,
                                               ObjectType,
                                               FirstQualifierInScope,
                                               AllowInjectedClassName);
     }
 
     return getDerived().RebuildTemplateName(SS, TemplateKWLoc,
                                             DTN->getOperator(), NameLoc,
                                             ObjectType, AllowInjectedClassName);
   }
 
   if (TemplateDecl *Template = Name.getAsTemplateDecl()) {
     TemplateDecl *TransTemplate
       = cast_or_null<TemplateDecl>(getDerived().TransformDecl(NameLoc,
                                                               Template));
     if (!TransTemplate)
       return TemplateName();
 
     if (!getDerived().AlwaysRebuild() &&
         TransTemplate == Template)
       return Name;
 
     return TemplateName(TransTemplate);
   }
 
   if (SubstTemplateTemplateParmPackStorage *SubstPack
       = Name.getAsSubstTemplateTemplateParmPack()) {
     return getDerived().RebuildTemplateName(
         SubstPack->getArgumentPack(), SubstPack->getAssociatedDecl(),
         SubstPack->getIndex(), SubstPack->getFinal());
   }
 
   // These should be getting filtered out before they reach the AST.
   llvm_unreachable("overloaded function decl survived to here");
 }
 
 template<typename Derived>
 void TreeTransform<Derived>::InventTemplateArgumentLoc(
                                          const TemplateArgument &Arg,
                                          TemplateArgumentLoc &Output) {
   Output = getSema().getTrivialTemplateArgumentLoc(
       Arg, QualType(), getDerived().getBaseLocation());
 }
 
 template <typename Derived>
 bool TreeTransform<Derived>::TransformTemplateArgument(
     const TemplateArgumentLoc &Input, TemplateArgumentLoc &Output,
     bool Uneval) {
   const TemplateArgument &Arg = Input.getArgument();
   switch (Arg.getKind()) {
   case TemplateArgument::Null:
   case TemplateArgument::Pack:
     llvm_unreachable("Unexpected TemplateArgument");
 
   case TemplateArgument::Integral:
   case TemplateArgument::NullPtr:
   case TemplateArgument::Declaration: {
     // Transform a resolved template argument straight to a resolved template
     // argument. We get here when substituting into an already-substituted
     // template type argument during concept satisfaction checking.
     QualType T = Arg.getNonTypeTemplateArgumentType();
     QualType NewT = getDerived().TransformType(T);
     if (NewT.isNull())
       return true;
 
     ValueDecl *D = Arg.getKind() == TemplateArgument::Declaration
                        ? Arg.getAsDecl()
                        : nullptr;
     ValueDecl *NewD = D ? cast_or_null<ValueDecl>(getDerived().TransformDecl(
                               getDerived().getBaseLocation(), D))
                         : nullptr;
     if (D && !NewD)
       return true;
 
     if (NewT == T && D == NewD)
       Output = Input;
     else if (Arg.getKind() == TemplateArgument::Integral)
       Output = TemplateArgumentLoc(
           TemplateArgument(getSema().Context, Arg.getAsIntegral(), NewT),
           TemplateArgumentLocInfo());
     else if (Arg.getKind() == TemplateArgument::NullPtr)
       Output = TemplateArgumentLoc(TemplateArgument(NewT, /*IsNullPtr=*/true),
                                    TemplateArgumentLocInfo());
     else
       Output = TemplateArgumentLoc(TemplateArgument(NewD, NewT),
                                    TemplateArgumentLocInfo());
 
     return false;
   }
 
   case TemplateArgument::Type: {
     TypeSourceInfo *DI = Input.getTypeSourceInfo();
     if (!DI)
       DI = InventTypeSourceInfo(Input.getArgument().getAsType());
 
     DI = getDerived().TransformType(DI);
     if (!DI)
       return true;
 
     Output = TemplateArgumentLoc(TemplateArgument(DI->getType()), DI);
     return false;
   }
 
   case TemplateArgument::Template: {
     NestedNameSpecifierLoc QualifierLoc = Input.getTemplateQualifierLoc();
     if (QualifierLoc) {
       QualifierLoc = getDerived().TransformNestedNameSpecifierLoc(QualifierLoc);
       if (!QualifierLoc)
         return true;
     }
 
     CXXScopeSpec SS;
     SS.Adopt(QualifierLoc);
     TemplateName Template = getDerived().TransformTemplateName(
         SS, Arg.getAsTemplate(), Input.getTemplateNameLoc());
     if (Template.isNull())
       return true;
 
     Output = TemplateArgumentLoc(SemaRef.Context, TemplateArgument(Template),
                                  QualifierLoc, Input.getTemplateNameLoc());
     return false;
   }
 
   case TemplateArgument::TemplateExpansion:
     llvm_unreachable("Caller should expand pack expansions");
 
   case TemplateArgument::Expression: {
     // Template argument expressions are constant expressions.
     EnterExpressionEvaluationContext Unevaluated(
         getSema(),
         Uneval ? Sema::ExpressionEvaluationContext::Unevaluated
                : Sema::ExpressionEvaluationContext::ConstantEvaluated,
         Sema::ReuseLambdaContextDecl, /*ExprContext=*/
         Sema::ExpressionEvaluationContextRecord::EK_TemplateArgument);
 
     Expr *InputExpr = Input.getSourceExpression();
     if (!InputExpr)
       InputExpr = Input.getArgument().getAsExpr();
 
     ExprResult E = getDerived().TransformExpr(InputExpr);
     E = SemaRef.ActOnConstantExpression(E);
     if (E.isInvalid())
       return true;
     Output = TemplateArgumentLoc(TemplateArgument(E.get()), E.get());
     return false;
   }
   }
 
   // Work around bogus GCC warning
   return true;
 }
 
 /// Iterator adaptor that invents template argument location information
 /// for each of the template arguments in its underlying iterator.
 template<typename Derived, typename InputIterator>
 class TemplateArgumentLocInventIterator {
   TreeTransform<Derived> &Self;
   InputIterator Iter;
 
 public:
   typedef TemplateArgumentLoc value_type;
   typedef TemplateArgumentLoc reference;
   typedef typename std::iterator_traits<InputIterator>::difference_type
     difference_type;
   typedef std::input_iterator_tag iterator_category;
 
   class pointer {
     TemplateArgumentLoc Arg;
 
   public:
     explicit pointer(TemplateArgumentLoc Arg) : Arg(Arg) { }
 
     const TemplateArgumentLoc *operator->() const { return &Arg; }
   };
 
   TemplateArgumentLocInventIterator() { }
 
   explicit TemplateArgumentLocInventIterator(TreeTransform<Derived> &Self,
                                              InputIterator Iter)
     : Self(Self), Iter(Iter) { }
 
   TemplateArgumentLocInventIterator &operator++() {
     ++Iter;
     return *this;
   }
 
   TemplateArgumentLocInventIterator operator++(int) {
     TemplateArgumentLocInventIterator Old(*this);
     ++(*this);
     return Old;
   }
 
   reference operator*() const {
     TemplateArgumentLoc Result;
     Self.InventTemplateArgumentLoc(*Iter, Result);
     return Result;
   }
 
   pointer operator->() const { return pointer(**this); }
 
   friend bool operator==(const TemplateArgumentLocInventIterator &X,
                          const TemplateArgumentLocInventIterator &Y) {
     return X.Iter == Y.Iter;
   }
 
   friend bool operator!=(const TemplateArgumentLocInventIterator &X,
                          const TemplateArgumentLocInventIterator &Y) {
     return X.Iter != Y.Iter;
   }
 };
 
 template<typename Derived>
 template<typename InputIterator>
 bool TreeTransform<Derived>::TransformTemplateArguments(
     InputIterator First, InputIterator Last, TemplateArgumentListInfo &Outputs,
     bool Uneval) {
   for (; First != Last; ++First) {
     TemplateArgumentLoc Out;
     TemplateArgumentLoc In = *First;
 
     if (In.getArgument().getKind() == TemplateArgument::Pack) {
       // Unpack argument packs, which we translate them into separate
       // arguments.
       // FIXME: We could do much better if we could guarantee that the
       // TemplateArgumentLocInfo for the pack expansion would be usable for
       // all of the template arguments in the argument pack.
       typedef TemplateArgumentLocInventIterator<Derived,
                                                 TemplateArgument::pack_iterator>
         PackLocIterator;
       if (TransformTemplateArguments(PackLocIterator(*this,
                                                  In.getArgument().pack_begin()),
                                      PackLocIterator(*this,
                                                    In.getArgument().pack_end()),
                                      Outputs, Uneval))
         return true;
 
       continue;
     }
 
     if (In.getArgument().isPackExpansion()) {
       // We have a pack expansion, for which we will be substituting into
       // the pattern.
       SourceLocation Ellipsis;
       std::optional<unsigned> OrigNumExpansions;
       TemplateArgumentLoc Pattern
         = getSema().getTemplateArgumentPackExpansionPattern(
               In, Ellipsis, OrigNumExpansions);
 
       SmallVector<UnexpandedParameterPack, 2> Unexpanded;
       getSema().collectUnexpandedParameterPacks(Pattern, Unexpanded);
       assert(!Unexpanded.empty() && "Pack expansion without parameter packs?");
 
       // Determine whether the set of unexpanded parameter packs can and should
       // be expanded.
       bool Expand = true;
       bool RetainExpansion = false;
       std::optional<unsigned> NumExpansions = OrigNumExpansions;
       if (getDerived().TryExpandParameterPacks(Ellipsis,
                                                Pattern.getSourceRange(),
                                                Unexpanded,
                                                Expand,
                                                RetainExpansion,
                                                NumExpansions))
         return true;
 
       if (!Expand) {
         // The transform has determined that we should perform a simple
         // transformation on the pack expansion, producing another pack
         // expansion.
         TemplateArgumentLoc OutPattern;
         Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(getSema(), -1);
         if (getDerived().TransformTemplateArgument(Pattern, OutPattern, Uneval))
           return true;
 
         Out = getDerived().RebuildPackExpansion(OutPattern, Ellipsis,
                                                 NumExpansions);
         if (Out.getArgument().isNull())
           return true;
 
         Outputs.addArgument(Out);
         continue;
       }
 
       // The transform has determined that we should perform an elementwise
       // expansion of the pattern. Do so.
       for (unsigned I = 0; I != *NumExpansions; ++I) {
         Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(getSema(), I);
 
         if (getDerived().TransformTemplateArgument(Pattern, Out, Uneval))
           return true;
 
         if (Out.getArgument().containsUnexpandedParameterPack()) {
           Out = getDerived().RebuildPackExpansion(Out, Ellipsis,
                                                   OrigNumExpansions);
           if (Out.getArgument().isNull())
             return true;
         }
 
         Outputs.addArgument(Out);
       }
 
       // If we're supposed to retain a pack expansion, do so by temporarily
       // forgetting the partially-substituted parameter pack.
       if (RetainExpansion) {
         ForgetPartiallySubstitutedPackRAII Forget(getDerived());
 
         if (getDerived().TransformTemplateArgument(Pattern, Out, Uneval))
           return true;
 
         Out = getDerived().RebuildPackExpansion(Out, Ellipsis,
                                                 OrigNumExpansions);
         if (Out.getArgument().isNull())
           return true;
 
         Outputs.addArgument(Out);
       }
 
       continue;
     }
 
     // The simple case:
     if (getDerived().TransformTemplateArgument(In, Out, Uneval))
       return true;
 
     Outputs.addArgument(Out);
   }
 
   return false;
 
 }
 
 //===----------------------------------------------------------------------===//
 // Type transformation
 //===----------------------------------------------------------------------===//
 
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformType(QualType T) {
   if (getDerived().AlreadyTransformed(T))
     return T;
 
   // Temporary workaround.  All of these transformations should
   // eventually turn into transformations on TypeLocs.
   TypeSourceInfo *DI = getSema().Context.getTrivialTypeSourceInfo(T,
                                                 getDerived().getBaseLocation());
 
   TypeSourceInfo *NewDI = getDerived().TransformType(DI);
 
   if (!NewDI)
     return QualType();
 
   return NewDI->getType();
 }
 
 template<typename Derived>
 TypeSourceInfo *TreeTransform<Derived>::TransformType(TypeSourceInfo *DI) {
   // Refine the base location to the type's location.
   TemporaryBase Rebase(*this, DI->getTypeLoc().getBeginLoc(),
                        getDerived().getBaseEntity());
   if (getDerived().AlreadyTransformed(DI->getType()))
     return DI;
 
   TypeLocBuilder TLB;
 
   TypeLoc TL = DI->getTypeLoc();
   TLB.reserve(TL.getFullDataSize());
 
   QualType Result = getDerived().TransformType(TLB, TL);
   if (Result.isNull())
     return nullptr;
 
   return TLB.getTypeSourceInfo(SemaRef.Context, Result);
 }
 
 template<typename Derived>
 QualType
 TreeTransform<Derived>::TransformType(TypeLocBuilder &TLB, TypeLoc T) {
   switch (T.getTypeLocClass()) {
 #define ABSTRACT_TYPELOC(CLASS, PARENT)
 #define TYPELOC(CLASS, PARENT)                                                 \
   case TypeLoc::CLASS:                                                         \
     return getDerived().Transform##CLASS##Type(TLB,                            \
                                                T.castAs<CLASS##TypeLoc>());
 #include "clang/AST/TypeLocNodes.def"
   }
 
   llvm_unreachable("unhandled type loc!");
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformTypeWithDeducedTST(QualType T) {
   if (!isa<DependentNameType>(T))
     return TransformType(T);
 
   if (getDerived().AlreadyTransformed(T))
     return T;
   TypeSourceInfo *DI = getSema().Context.getTrivialTypeSourceInfo(T,
                                                 getDerived().getBaseLocation());
   TypeSourceInfo *NewDI = getDerived().TransformTypeWithDeducedTST(DI);
   return NewDI ? NewDI->getType() : QualType();
 }
 
 template<typename Derived>
 TypeSourceInfo *
 TreeTransform<Derived>::TransformTypeWithDeducedTST(TypeSourceInfo *DI) {
   if (!isa<DependentNameType>(DI->getType()))
     return TransformType(DI);
 
   // Refine the base location to the type's location.
   TemporaryBase Rebase(*this, DI->getTypeLoc().getBeginLoc(),
                        getDerived().getBaseEntity());
   if (getDerived().AlreadyTransformed(DI->getType()))
     return DI;
 
   TypeLocBuilder TLB;
 
   TypeLoc TL = DI->getTypeLoc();
   TLB.reserve(TL.getFullDataSize());
 
   auto QTL = TL.getAs<QualifiedTypeLoc>();
   if (QTL)
     TL = QTL.getUnqualifiedLoc();
 
   auto DNTL = TL.castAs<DependentNameTypeLoc>();
 
   QualType Result = getDerived().TransformDependentNameType(
       TLB, DNTL, /*DeducedTSTContext*/true);
   if (Result.isNull())
     return nullptr;
 
   if (QTL) {
     Result = getDerived().RebuildQualifiedType(Result, QTL);
     if (Result.isNull())
       return nullptr;
     TLB.TypeWasModifiedSafely(Result);
   }
 
   return TLB.getTypeSourceInfo(SemaRef.Context, Result);
 }
 
 template<typename Derived>
 QualType
 TreeTransform<Derived>::TransformQualifiedType(TypeLocBuilder &TLB,
                                                QualifiedTypeLoc T) {
   QualType Result;
   TypeLoc UnqualTL = T.getUnqualifiedLoc();
   auto SuppressObjCLifetime =
       T.getType().getLocalQualifiers().hasObjCLifetime();
   if (auto TTP = UnqualTL.getAs<TemplateTypeParmTypeLoc>()) {
     Result = getDerived().TransformTemplateTypeParmType(TLB, TTP,
                                                         SuppressObjCLifetime);
   } else if (auto STTP = UnqualTL.getAs<SubstTemplateTypeParmPackTypeLoc>()) {
     Result = getDerived().TransformSubstTemplateTypeParmPackType(
         TLB, STTP, SuppressObjCLifetime);
   } else {
     Result = getDerived().TransformType(TLB, UnqualTL);
   }
 
   if (Result.isNull())
     return QualType();
 
   Result = getDerived().RebuildQualifiedType(Result, T);
 
   if (Result.isNull())
     return QualType();
 
   // RebuildQualifiedType might have updated the type, but not in a way
   // that invalidates the TypeLoc. (There's no location information for
   // qualifiers.)
   TLB.TypeWasModifiedSafely(Result);
 
   return Result;
 }
 
 template <typename Derived>
 QualType TreeTransform<Derived>::RebuildQualifiedType(QualType T,
                                                       QualifiedTypeLoc TL) {
 
   SourceLocation Loc = TL.getBeginLoc();
   Qualifiers Quals = TL.getType().getLocalQualifiers();
 
   if ((T.getAddressSpace() != LangAS::Default &&
        Quals.getAddressSpace() != LangAS::Default) &&
       T.getAddressSpace() != Quals.getAddressSpace()) {
     SemaRef.Diag(Loc, diag::err_address_space_mismatch_templ_inst)
         << TL.getType() << T;
     return QualType();
   }
 
   // C++ [dcl.fct]p7:
   //   [When] adding cv-qualifications on top of the function type [...] the
   //   cv-qualifiers are ignored.
   if (T->isFunctionType()) {
     T = SemaRef.getASTContext().getAddrSpaceQualType(T,
                                                      Quals.getAddressSpace());
     return T;
   }
 
   // C++ [dcl.ref]p1:
   //   when the cv-qualifiers are introduced through the use of a typedef-name
   //   or decltype-specifier [...] the cv-qualifiers are ignored.
   // Note that [dcl.ref]p1 lists all cases in which cv-qualifiers can be
   // applied to a reference type.
   if (T->isReferenceType()) {
     // The only qualifier that applies to a reference type is restrict.
     if (!Quals.hasRestrict())
       return T;
     Quals = Qualifiers::fromCVRMask(Qualifiers::Restrict);
   }
 
   // Suppress Objective-C lifetime qualifiers if they don't make sense for the
   // resulting type.
   if (Quals.hasObjCLifetime()) {
     if (!T->isObjCLifetimeType() && !T->isDependentType())
       Quals.removeObjCLifetime();
     else if (T.getObjCLifetime()) {
       // Objective-C ARC:
       //   A lifetime qualifier applied to a substituted template parameter
       //   overrides the lifetime qualifier from the template argument.
       const AutoType *AutoTy;
       if ((AutoTy = dyn_cast<AutoType>(T)) && AutoTy->isDeduced()) {
         // 'auto' types behave the same way as template parameters.
         QualType Deduced = AutoTy->getDeducedType();
         Qualifiers Qs = Deduced.getQualifiers();
         Qs.removeObjCLifetime();
         Deduced =
             SemaRef.Context.getQualifiedType(Deduced.getUnqualifiedType(), Qs);
         T = SemaRef.Context.getAutoType(Deduced, AutoTy->getKeyword(),
                                         AutoTy->isDependentType(),
                                         /*isPack=*/false,
                                         AutoTy->getTypeConstraintConcept(),
                                         AutoTy->getTypeConstraintArguments());
       } else {
         // Otherwise, complain about the addition of a qualifier to an
         // already-qualified type.
         // FIXME: Why is this check not in Sema::BuildQualifiedType?
         SemaRef.Diag(Loc, diag::err_attr_objc_ownership_redundant) << T;
         Quals.removeObjCLifetime();
       }
     }
   }
 
   return SemaRef.BuildQualifiedType(T, Loc, Quals);
 }
 
 template<typename Derived>
 TypeLoc
 TreeTransform<Derived>::TransformTypeInObjectScope(TypeLoc TL,
                                                    QualType ObjectType,
                                                    NamedDecl *UnqualLookup,
                                                    CXXScopeSpec &SS) {
   if (getDerived().AlreadyTransformed(TL.getType()))
     return TL;
 
   TypeSourceInfo *TSI =
       TransformTSIInObjectScope(TL, ObjectType, UnqualLookup, SS);
   if (TSI)
     return TSI->getTypeLoc();
   return TypeLoc();
 }
 
 template<typename Derived>
 TypeSourceInfo *
 TreeTransform<Derived>::TransformTypeInObjectScope(TypeSourceInfo *TSInfo,
                                                    QualType ObjectType,
                                                    NamedDecl *UnqualLookup,
                                                    CXXScopeSpec &SS) {
   if (getDerived().AlreadyTransformed(TSInfo->getType()))
     return TSInfo;
 
   return TransformTSIInObjectScope(TSInfo->getTypeLoc(), ObjectType,
                                    UnqualLookup, SS);
 }
 
 template <typename Derived>
 TypeSourceInfo *TreeTransform<Derived>::TransformTSIInObjectScope(
     TypeLoc TL, QualType ObjectType, NamedDecl *UnqualLookup,
     CXXScopeSpec &SS) {
   QualType T = TL.getType();
   assert(!getDerived().AlreadyTransformed(T));
 
   TypeLocBuilder TLB;
   QualType Result;
 
   if (isa<TemplateSpecializationType>(T)) {
     TemplateSpecializationTypeLoc SpecTL =
         TL.castAs<TemplateSpecializationTypeLoc>();
 
     TemplateName Template = getDerived().TransformTemplateName(
         SS, SpecTL.getTypePtr()->getTemplateName(), SpecTL.getTemplateNameLoc(),
         ObjectType, UnqualLookup, /*AllowInjectedClassName*/true);
     if (Template.isNull())
       return nullptr;
 
     Result = getDerived().TransformTemplateSpecializationType(TLB, SpecTL,
                                                               Template);
   } else if (isa<DependentTemplateSpecializationType>(T)) {
     DependentTemplateSpecializationTypeLoc SpecTL =
         TL.castAs<DependentTemplateSpecializationTypeLoc>();
 
     TemplateName Template
       = getDerived().RebuildTemplateName(SS,
                                          SpecTL.getTemplateKeywordLoc(),
                                          *SpecTL.getTypePtr()->getIdentifier(),
                                          SpecTL.getTemplateNameLoc(),
                                          ObjectType, UnqualLookup,
                                          /*AllowInjectedClassName*/true);
     if (Template.isNull())
       return nullptr;
 
     Result = getDerived().TransformDependentTemplateSpecializationType(TLB,
                                                                        SpecTL,
                                                                        Template,
                                                                        SS);
   } else {
     // Nothing special needs to be done for these.
     Result = getDerived().TransformType(TLB, TL);
   }
 
   if (Result.isNull())
     return nullptr;
 
   return TLB.getTypeSourceInfo(SemaRef.Context, Result);
 }
 
 template <class TyLoc> static inline
 QualType TransformTypeSpecType(TypeLocBuilder &TLB, TyLoc T) {
   TyLoc NewT = TLB.push<TyLoc>(T.getType());
   NewT.setNameLoc(T.getNameLoc());
   return T.getType();
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformBuiltinType(TypeLocBuilder &TLB,
                                                       BuiltinTypeLoc T) {
   BuiltinTypeLoc NewT = TLB.push<BuiltinTypeLoc>(T.getType());
   NewT.setBuiltinLoc(T.getBuiltinLoc());
   if (T.needsExtraLocalData())
     NewT.getWrittenBuiltinSpecs() = T.getWrittenBuiltinSpecs();
   return T.getType();
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformComplexType(TypeLocBuilder &TLB,
                                                       ComplexTypeLoc T) {
   // FIXME: recurse?
   return TransformTypeSpecType(TLB, T);
 }
 
 template <typename Derived>
 QualType TreeTransform<Derived>::TransformAdjustedType(TypeLocBuilder &TLB,
                                                        AdjustedTypeLoc TL) {
   // Adjustments applied during transformation are handled elsewhere.
   return getDerived().TransformType(TLB, TL.getOriginalLoc());
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformDecayedType(TypeLocBuilder &TLB,
                                                       DecayedTypeLoc TL) {
   QualType OriginalType = getDerived().TransformType(TLB, TL.getOriginalLoc());
   if (OriginalType.isNull())
     return QualType();
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() ||
       OriginalType != TL.getOriginalLoc().getType())
     Result = SemaRef.Context.getDecayedType(OriginalType);
   TLB.push<DecayedTypeLoc>(Result);
   // Nothing to set for DecayedTypeLoc.
   return Result;
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformPointerType(TypeLocBuilder &TLB,
                                                       PointerTypeLoc TL) {
   QualType PointeeType
     = getDerived().TransformType(TLB, TL.getPointeeLoc());
   if (PointeeType.isNull())
     return QualType();
 
   QualType Result = TL.getType();
   if (PointeeType->getAs<ObjCObjectType>()) {
     // A dependent pointer type 'T *' has is being transformed such
     // that an Objective-C class type is being replaced for 'T'. The
     // resulting pointer type is an ObjCObjectPointerType, not a
     // PointerType.
     Result = SemaRef.Context.getObjCObjectPointerType(PointeeType);
 
     ObjCObjectPointerTypeLoc NewT = TLB.push<ObjCObjectPointerTypeLoc>(Result);
     NewT.setStarLoc(TL.getStarLoc());
     return Result;
   }
 
   if (getDerived().AlwaysRebuild() ||
       PointeeType != TL.getPointeeLoc().getType()) {
     Result = getDerived().RebuildPointerType(PointeeType, TL.getSigilLoc());
     if (Result.isNull())
       return QualType();
   }
 
   // Objective-C ARC can add lifetime qualifiers to the type that we're
   // pointing to.
   TLB.TypeWasModifiedSafely(Result->getPointeeType());
 
   PointerTypeLoc NewT = TLB.push<PointerTypeLoc>(Result);
   NewT.setSigilLoc(TL.getSigilLoc());
   return Result;
 }
 
 template<typename Derived>
 QualType
 TreeTransform<Derived>::TransformBlockPointerType(TypeLocBuilder &TLB,
                                                   BlockPointerTypeLoc TL) {
   QualType PointeeType
     = getDerived().TransformType(TLB, TL.getPointeeLoc());
   if (PointeeType.isNull())
     return QualType();
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() ||
       PointeeType != TL.getPointeeLoc().getType()) {
     Result = getDerived().RebuildBlockPointerType(PointeeType,
                                                   TL.getSigilLoc());
     if (Result.isNull())
       return QualType();
   }
 
   BlockPointerTypeLoc NewT = TLB.push<BlockPointerTypeLoc>(Result);
   NewT.setSigilLoc(TL.getSigilLoc());
   return Result;
 }
 
 /// Transforms a reference type.  Note that somewhat paradoxically we
 /// don't care whether the type itself is an l-value type or an r-value
 /// type;  we only care if the type was *written* as an l-value type
 /// or an r-value type.
 template<typename Derived>
 QualType
 TreeTransform<Derived>::TransformReferenceType(TypeLocBuilder &TLB,
                                                ReferenceTypeLoc TL) {
   const ReferenceType *T = TL.getTypePtr();
 
   // Note that this works with the pointee-as-written.
   QualType PointeeType = getDerived().TransformType(TLB, TL.getPointeeLoc());
   if (PointeeType.isNull())
     return QualType();
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() ||
       PointeeType != T->getPointeeTypeAsWritten()) {
     Result = getDerived().RebuildReferenceType(PointeeType,
                                                T->isSpelledAsLValue(),
                                                TL.getSigilLoc());
     if (Result.isNull())
       return QualType();
   }
 
   // Objective-C ARC can add lifetime qualifiers to the type that we're
   // referring to.
   TLB.TypeWasModifiedSafely(
       Result->castAs<ReferenceType>()->getPointeeTypeAsWritten());
 
   // r-value references can be rebuilt as l-value references.
   ReferenceTypeLoc NewTL;
   if (isa<LValueReferenceType>(Result))
     NewTL = TLB.push<LValueReferenceTypeLoc>(Result);
   else
     NewTL = TLB.push<RValueReferenceTypeLoc>(Result);
   NewTL.setSigilLoc(TL.getSigilLoc());
 
   return Result;
 }
 
 template<typename Derived>
 QualType
 TreeTransform<Derived>::TransformLValueReferenceType(TypeLocBuilder &TLB,
                                                  LValueReferenceTypeLoc TL) {
   return TransformReferenceType(TLB, TL);
 }
 
 template<typename Derived>
 QualType
 TreeTransform<Derived>::TransformRValueReferenceType(TypeLocBuilder &TLB,
                                                  RValueReferenceTypeLoc TL) {
   return TransformReferenceType(TLB, TL);
 }
 
 template<typename Derived>
 QualType
 TreeTransform<Derived>::TransformMemberPointerType(TypeLocBuilder &TLB,
                                                    MemberPointerTypeLoc TL) {
   QualType PointeeType = getDerived().TransformType(TLB, TL.getPointeeLoc());
   if (PointeeType.isNull())
     return QualType();
 
   TypeSourceInfo* OldClsTInfo = TL.getClassTInfo();
   TypeSourceInfo *NewClsTInfo = nullptr;
   if (OldClsTInfo) {
     NewClsTInfo = getDerived().TransformType(OldClsTInfo);
     if (!NewClsTInfo)
       return QualType();
   }
 
   const MemberPointerType *T = TL.getTypePtr();
   QualType OldClsType = QualType(T->getClass(), 0);
   QualType NewClsType;
   if (NewClsTInfo)
     NewClsType = NewClsTInfo->getType();
   else {
     NewClsType = getDerived().TransformType(OldClsType);
     if (NewClsType.isNull())
       return QualType();
   }
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() ||
       PointeeType != T->getPointeeType() ||
       NewClsType != OldClsType) {
     Result = getDerived().RebuildMemberPointerType(PointeeType, NewClsType,
                                                    TL.getStarLoc());
     if (Result.isNull())
       return QualType();
   }
 
   // If we had to adjust the pointee type when building a member pointer, make
   // sure to push TypeLoc info for it.
   const MemberPointerType *MPT = Result->getAs<MemberPointerType>();
   if (MPT && PointeeType != MPT->getPointeeType()) {
     assert(isa<AdjustedType>(MPT->getPointeeType()));
     TLB.push<AdjustedTypeLoc>(MPT->getPointeeType());
   }
 
   MemberPointerTypeLoc NewTL = TLB.push<MemberPointerTypeLoc>(Result);
   NewTL.setSigilLoc(TL.getSigilLoc());
   NewTL.setClassTInfo(NewClsTInfo);
 
   return Result;
 }
 
 template<typename Derived>
 QualType
 TreeTransform<Derived>::TransformConstantArrayType(TypeLocBuilder &TLB,
                                                    ConstantArrayTypeLoc TL) {
   const ConstantArrayType *T = TL.getTypePtr();
   QualType ElementType = getDerived().TransformType(TLB, TL.getElementLoc());
   if (ElementType.isNull())
     return QualType();
 
   // Prefer the expression from the TypeLoc;  the other may have been uniqued.
   Expr *OldSize = TL.getSizeExpr();
   if (!OldSize)
     OldSize = const_cast<Expr*>(T->getSizeExpr());
   Expr *NewSize = nullptr;
   if (OldSize) {
     EnterExpressionEvaluationContext Unevaluated(
         SemaRef, Sema::ExpressionEvaluationContext::ConstantEvaluated);
     NewSize = getDerived().TransformExpr(OldSize).template getAs<Expr>();
     NewSize = SemaRef.ActOnConstantExpression(NewSize).get();
   }
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() ||
       ElementType != T->getElementType() ||
       (T->getSizeExpr() && NewSize != OldSize)) {
     Result = getDerived().RebuildConstantArrayType(ElementType,
                                                    T->getSizeModifier(),
                                                    T->getSize(), NewSize,
                                              T->getIndexTypeCVRQualifiers(),
                                                    TL.getBracketsRange());
     if (Result.isNull())
       return QualType();
   }
 
   // We might have either a ConstantArrayType or a VariableArrayType now:
   // a ConstantArrayType is allowed to have an element type which is a
   // VariableArrayType if the type is dependent.  Fortunately, all array
   // types have the same location layout.
   ArrayTypeLoc NewTL = TLB.push<ArrayTypeLoc>(Result);
   NewTL.setLBracketLoc(TL.getLBracketLoc());
   NewTL.setRBracketLoc(TL.getRBracketLoc());
   NewTL.setSizeExpr(NewSize);
 
   return Result;
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformIncompleteArrayType(
                                               TypeLocBuilder &TLB,
                                               IncompleteArrayTypeLoc TL) {
   const IncompleteArrayType *T = TL.getTypePtr();
   QualType ElementType = getDerived().TransformType(TLB, TL.getElementLoc());
   if (ElementType.isNull())
     return QualType();
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() ||
       ElementType != T->getElementType()) {
     Result = getDerived().RebuildIncompleteArrayType(ElementType,
                                                      T->getSizeModifier(),
                                            T->getIndexTypeCVRQualifiers(),
                                                      TL.getBracketsRange());
     if (Result.isNull())
       return QualType();
   }
 
   IncompleteArrayTypeLoc NewTL = TLB.push<IncompleteArrayTypeLoc>(Result);
   NewTL.setLBracketLoc(TL.getLBracketLoc());
   NewTL.setRBracketLoc(TL.getRBracketLoc());
   NewTL.setSizeExpr(nullptr);
 
   return Result;
 }
 
 template<typename Derived>
 QualType
 TreeTransform<Derived>::TransformVariableArrayType(TypeLocBuilder &TLB,
                                                    VariableArrayTypeLoc TL) {
   const VariableArrayType *T = TL.getTypePtr();
   QualType ElementType = getDerived().TransformType(TLB, TL.getElementLoc());
   if (ElementType.isNull())
     return QualType();
 
   ExprResult SizeResult;
   {
     EnterExpressionEvaluationContext Context(
         SemaRef, Sema::ExpressionEvaluationContext::PotentiallyEvaluated);
     SizeResult = getDerived().TransformExpr(T->getSizeExpr());
   }
   if (SizeResult.isInvalid())
     return QualType();
   SizeResult =
       SemaRef.ActOnFinishFullExpr(SizeResult.get(), /*DiscardedValue*/ false);
   if (SizeResult.isInvalid())
     return QualType();
 
   Expr *Size = SizeResult.get();
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() ||
       ElementType != T->getElementType() ||
       Size != T->getSizeExpr()) {
     Result = getDerived().RebuildVariableArrayType(ElementType,
                                                    T->getSizeModifier(),
                                                    Size,
                                              T->getIndexTypeCVRQualifiers(),
                                                    TL.getBracketsRange());
     if (Result.isNull())
       return QualType();
   }
 
   // We might have constant size array now, but fortunately it has the same
   // location layout.
   ArrayTypeLoc NewTL = TLB.push<ArrayTypeLoc>(Result);
   NewTL.setLBracketLoc(TL.getLBracketLoc());
   NewTL.setRBracketLoc(TL.getRBracketLoc());
   NewTL.setSizeExpr(Size);
 
   return Result;
 }
 
 template<typename Derived>
 QualType
 TreeTransform<Derived>::TransformDependentSizedArrayType(TypeLocBuilder &TLB,
                                              DependentSizedArrayTypeLoc TL) {
   const DependentSizedArrayType *T = TL.getTypePtr();
   QualType ElementType = getDerived().TransformType(TLB, TL.getElementLoc());
   if (ElementType.isNull())
     return QualType();
 
   // Array bounds are constant expressions.
   EnterExpressionEvaluationContext Unevaluated(
       SemaRef, Sema::ExpressionEvaluationContext::ConstantEvaluated);
 
   // Prefer the expression from the TypeLoc;  the other may have been uniqued.
   Expr *origSize = TL.getSizeExpr();
   if (!origSize) origSize = T->getSizeExpr();
 
   ExprResult sizeResult
     = getDerived().TransformExpr(origSize);
   sizeResult = SemaRef.ActOnConstantExpression(sizeResult);
   if (sizeResult.isInvalid())
     return QualType();
 
   Expr *size = sizeResult.get();
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() ||
       ElementType != T->getElementType() ||
       size != origSize) {
     Result = getDerived().RebuildDependentSizedArrayType(ElementType,
                                                          T->getSizeModifier(),
                                                          size,
                                                 T->getIndexTypeCVRQualifiers(),
                                                         TL.getBracketsRange());
     if (Result.isNull())
       return QualType();
   }
 
   // We might have any sort of array type now, but fortunately they
   // all have the same location layout.
   ArrayTypeLoc NewTL = TLB.push<ArrayTypeLoc>(Result);
   NewTL.setLBracketLoc(TL.getLBracketLoc());
   NewTL.setRBracketLoc(TL.getRBracketLoc());
   NewTL.setSizeExpr(size);
 
   return Result;
 }
 
 template <typename Derived>
 QualType TreeTransform<Derived>::TransformDependentVectorType(
     TypeLocBuilder &TLB, DependentVectorTypeLoc TL) {
   const DependentVectorType *T = TL.getTypePtr();
   QualType ElementType = getDerived().TransformType(TLB, TL.getElementLoc());
   if (ElementType.isNull())
     return QualType();
 
   EnterExpressionEvaluationContext Unevaluated(
       SemaRef, Sema::ExpressionEvaluationContext::ConstantEvaluated);
 
   ExprResult Size = getDerived().TransformExpr(T->getSizeExpr());
   Size = SemaRef.ActOnConstantExpression(Size);
   if (Size.isInvalid())
     return QualType();
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() || ElementType != T->getElementType() ||
       Size.get() != T->getSizeExpr()) {
     Result = getDerived().RebuildDependentVectorType(
         ElementType, Size.get(), T->getAttributeLoc(), T->getVectorKind());
     if (Result.isNull())
       return QualType();
   }
 
   // Result might be dependent or not.
   if (isa<DependentVectorType>(Result)) {
     DependentVectorTypeLoc NewTL =
         TLB.push<DependentVectorTypeLoc>(Result);
     NewTL.setNameLoc(TL.getNameLoc());
   } else {
     VectorTypeLoc NewTL = TLB.push<VectorTypeLoc>(Result);
     NewTL.setNameLoc(TL.getNameLoc());
   }
 
   return Result;
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformDependentSizedExtVectorType(
                                       TypeLocBuilder &TLB,
                                       DependentSizedExtVectorTypeLoc TL) {
   const DependentSizedExtVectorType *T = TL.getTypePtr();
 
   // FIXME: ext vector locs should be nested
   QualType ElementType = getDerived().TransformType(TLB, TL.getElementLoc());
   if (ElementType.isNull())
     return QualType();
 
   // Vector sizes are constant expressions.
   EnterExpressionEvaluationContext Unevaluated(
       SemaRef, Sema::ExpressionEvaluationContext::ConstantEvaluated);
 
   ExprResult Size = getDerived().TransformExpr(T->getSizeExpr());
   Size = SemaRef.ActOnConstantExpression(Size);
   if (Size.isInvalid())
     return QualType();
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() ||
       ElementType != T->getElementType() ||
       Size.get() != T->getSizeExpr()) {
     Result = getDerived().RebuildDependentSizedExtVectorType(ElementType,
                                                              Size.get(),
                                                          T->getAttributeLoc());
     if (Result.isNull())
       return QualType();
   }
 
   // Result might be dependent or not.
   if (isa<DependentSizedExtVectorType>(Result)) {
     DependentSizedExtVectorTypeLoc NewTL
       = TLB.push<DependentSizedExtVectorTypeLoc>(Result);
     NewTL.setNameLoc(TL.getNameLoc());
   } else {
     ExtVectorTypeLoc NewTL = TLB.push<ExtVectorTypeLoc>(Result);
     NewTL.setNameLoc(TL.getNameLoc());
   }
 
   return Result;
 }
 
 template <typename Derived>
 QualType
 TreeTransform<Derived>::TransformConstantMatrixType(TypeLocBuilder &TLB,
                                                     ConstantMatrixTypeLoc TL) {
   const ConstantMatrixType *T = TL.getTypePtr();
   QualType ElementType = getDerived().TransformType(T->getElementType());
   if (ElementType.isNull())
     return QualType();
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() || ElementType != T->getElementType()) {
     Result = getDerived().RebuildConstantMatrixType(
         ElementType, T->getNumRows(), T->getNumColumns());
     if (Result.isNull())
       return QualType();
   }
 
   ConstantMatrixTypeLoc NewTL = TLB.push<ConstantMatrixTypeLoc>(Result);
   NewTL.setAttrNameLoc(TL.getAttrNameLoc());
   NewTL.setAttrOperandParensRange(TL.getAttrOperandParensRange());
   NewTL.setAttrRowOperand(TL.getAttrRowOperand());
   NewTL.setAttrColumnOperand(TL.getAttrColumnOperand());
 
   return Result;
 }
 
 template <typename Derived>
 QualType TreeTransform<Derived>::TransformDependentSizedMatrixType(
     TypeLocBuilder &TLB, DependentSizedMatrixTypeLoc TL) {
   const DependentSizedMatrixType *T = TL.getTypePtr();
 
   QualType ElementType = getDerived().TransformType(T->getElementType());
   if (ElementType.isNull()) {
     return QualType();
   }
 
   // Matrix dimensions are constant expressions.
   EnterExpressionEvaluationContext Unevaluated(
       SemaRef, Sema::ExpressionEvaluationContext::ConstantEvaluated);
 
   Expr *origRows = TL.getAttrRowOperand();
   if (!origRows)
     origRows = T->getRowExpr();
   Expr *origColumns = TL.getAttrColumnOperand();
   if (!origColumns)
     origColumns = T->getColumnExpr();
 
   ExprResult rowResult = getDerived().TransformExpr(origRows);
   rowResult = SemaRef.ActOnConstantExpression(rowResult);
   if (rowResult.isInvalid())
     return QualType();
 
   ExprResult columnResult = getDerived().TransformExpr(origColumns);
   columnResult = SemaRef.ActOnConstantExpression(columnResult);
   if (columnResult.isInvalid())
     return QualType();
 
   Expr *rows = rowResult.get();
   Expr *columns = columnResult.get();
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() || ElementType != T->getElementType() ||
       rows != origRows || columns != origColumns) {
     Result = getDerived().RebuildDependentSizedMatrixType(
         ElementType, rows, columns, T->getAttributeLoc());
 
     if (Result.isNull())
       return QualType();
   }
 
   // We might have any sort of matrix type now, but fortunately they
   // all have the same location layout.
   MatrixTypeLoc NewTL = TLB.push<MatrixTypeLoc>(Result);
   NewTL.setAttrNameLoc(TL.getAttrNameLoc());
   NewTL.setAttrOperandParensRange(TL.getAttrOperandParensRange());
   NewTL.setAttrRowOperand(rows);
   NewTL.setAttrColumnOperand(columns);
   return Result;
 }
 
 template <typename Derived>
 QualType TreeTransform<Derived>::TransformDependentAddressSpaceType(
     TypeLocBuilder &TLB, DependentAddressSpaceTypeLoc TL) {
   const DependentAddressSpaceType *T = TL.getTypePtr();
 
   QualType pointeeType = getDerived().TransformType(T->getPointeeType());
 
   if (pointeeType.isNull())
     return QualType();
 
   // Address spaces are constant expressions.
   EnterExpressionEvaluationContext Unevaluated(
       SemaRef, Sema::ExpressionEvaluationContext::ConstantEvaluated);
 
   ExprResult AddrSpace = getDerived().TransformExpr(T->getAddrSpaceExpr());
   AddrSpace = SemaRef.ActOnConstantExpression(AddrSpace);
   if (AddrSpace.isInvalid())
     return QualType();
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() || pointeeType != T->getPointeeType() ||
       AddrSpace.get() != T->getAddrSpaceExpr()) {
     Result = getDerived().RebuildDependentAddressSpaceType(
         pointeeType, AddrSpace.get(), T->getAttributeLoc());
     if (Result.isNull())
       return QualType();
   }
 
   // Result might be dependent or not.
   if (isa<DependentAddressSpaceType>(Result)) {
     DependentAddressSpaceTypeLoc NewTL =
         TLB.push<DependentAddressSpaceTypeLoc>(Result);
 
     NewTL.setAttrOperandParensRange(TL.getAttrOperandParensRange());
     NewTL.setAttrExprOperand(TL.getAttrExprOperand());
     NewTL.setAttrNameLoc(TL.getAttrNameLoc());
 
   } else {
     TypeSourceInfo *DI = getSema().Context.getTrivialTypeSourceInfo(
         Result, getDerived().getBaseLocation());
     TransformType(TLB, DI->getTypeLoc());
   }
 
   return Result;
 }
 
 template <typename Derived>
 QualType TreeTransform<Derived>::TransformVectorType(TypeLocBuilder &TLB,
                                                      VectorTypeLoc TL) {
   const VectorType *T = TL.getTypePtr();
   QualType ElementType = getDerived().TransformType(TLB, TL.getElementLoc());
   if (ElementType.isNull())
     return QualType();
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() ||
       ElementType != T->getElementType()) {
     Result = getDerived().RebuildVectorType(ElementType, T->getNumElements(),
                                             T->getVectorKind());
     if (Result.isNull())
       return QualType();
   }
 
   VectorTypeLoc NewTL = TLB.push<VectorTypeLoc>(Result);
   NewTL.setNameLoc(TL.getNameLoc());
 
   return Result;
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformExtVectorType(TypeLocBuilder &TLB,
                                                         ExtVectorTypeLoc TL) {
   const VectorType *T = TL.getTypePtr();
   QualType ElementType = getDerived().TransformType(TLB, TL.getElementLoc());
   if (ElementType.isNull())
     return QualType();
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() ||
       ElementType != T->getElementType()) {
     Result = getDerived().RebuildExtVectorType(ElementType,
                                                T->getNumElements(),
                                                /*FIXME*/ SourceLocation());
     if (Result.isNull())
       return QualType();
   }
 
   ExtVectorTypeLoc NewTL = TLB.push<ExtVectorTypeLoc>(Result);
   NewTL.setNameLoc(TL.getNameLoc());
 
   return Result;
 }
 
 template <typename Derived>
 ParmVarDecl *TreeTransform<Derived>::TransformFunctionTypeParam(
     ParmVarDecl *OldParm, int indexAdjustment,
     std::optional<unsigned> NumExpansions, bool ExpectParameterPack) {
   TypeSourceInfo *OldDI = OldParm->getTypeSourceInfo();
   TypeSourceInfo *NewDI = nullptr;
 
   if (NumExpansions && isa<PackExpansionType>(OldDI->getType())) {
     // If we're substituting into a pack expansion type and we know the
     // length we want to expand to, just substitute for the pattern.
     TypeLoc OldTL = OldDI->getTypeLoc();
     PackExpansionTypeLoc OldExpansionTL = OldTL.castAs<PackExpansionTypeLoc>();
 
     TypeLocBuilder TLB;
     TypeLoc NewTL = OldDI->getTypeLoc();
     TLB.reserve(NewTL.getFullDataSize());
 
     QualType Result = getDerived().TransformType(TLB,
                                                OldExpansionTL.getPatternLoc());
     if (Result.isNull())
       return nullptr;
 
     Result = RebuildPackExpansionType(Result,
                                 OldExpansionTL.getPatternLoc().getSourceRange(),
                                       OldExpansionTL.getEllipsisLoc(),
                                       NumExpansions);
     if (Result.isNull())
       return nullptr;
 
     PackExpansionTypeLoc NewExpansionTL
       = TLB.push<PackExpansionTypeLoc>(Result);
     NewExpansionTL.setEllipsisLoc(OldExpansionTL.getEllipsisLoc());
     NewDI = TLB.getTypeSourceInfo(SemaRef.Context, Result);
   } else
     NewDI = getDerived().TransformType(OldDI);
   if (!NewDI)
     return nullptr;
 
   if (NewDI == OldDI && indexAdjustment == 0)
     return OldParm;
 
   ParmVarDecl *newParm = ParmVarDecl::Create(SemaRef.Context,
                                              OldParm->getDeclContext(),
                                              OldParm->getInnerLocStart(),
                                              OldParm->getLocation(),
                                              OldParm->getIdentifier(),
                                              NewDI->getType(),
                                              NewDI,
                                              OldParm->getStorageClass(),
                                              /* DefArg */ nullptr);
   newParm->setScopeInfo(OldParm->getFunctionScopeDepth(),
                         OldParm->getFunctionScopeIndex() + indexAdjustment);
   transformedLocalDecl(OldParm, {newParm});
   return newParm;
 }
 
 template <typename Derived>
 bool TreeTransform<Derived>::TransformFunctionTypeParams(
     SourceLocation Loc, ArrayRef<ParmVarDecl *> Params,
     const QualType *ParamTypes,
     const FunctionProtoType::ExtParameterInfo *ParamInfos,
     SmallVectorImpl<QualType> &OutParamTypes,
     SmallVectorImpl<ParmVarDecl *> *PVars,
     Sema::ExtParameterInfoBuilder &PInfos,
     unsigned *LastParamTransformed) {
   int indexAdjustment = 0;
 
   unsigned NumParams = Params.size();
   for (unsigned i = 0; i != NumParams; ++i) {
     if (LastParamTransformed)
       *LastParamTransformed = i;
     if (ParmVarDecl *OldParm = Params[i]) {
       assert(OldParm->getFunctionScopeIndex() == i);
 
       std::optional<unsigned> NumExpansions;
       ParmVarDecl *NewParm = nullptr;
       if (OldParm->isParameterPack()) {
         // We have a function parameter pack that may need to be expanded.
         SmallVector<UnexpandedParameterPack, 2> Unexpanded;
 
         // Find the parameter packs that could be expanded.
         TypeLoc TL = OldParm->getTypeSourceInfo()->getTypeLoc();
         PackExpansionTypeLoc ExpansionTL = TL.castAs<PackExpansionTypeLoc>();
         TypeLoc Pattern = ExpansionTL.getPatternLoc();
         SemaRef.collectUnexpandedParameterPacks(Pattern, Unexpanded);
 
         // Determine whether we should expand the parameter packs.
         bool ShouldExpand = false;
         bool RetainExpansion = false;
         std::optional<unsigned> OrigNumExpansions;
         if (Unexpanded.size() > 0) {
           OrigNumExpansions = ExpansionTL.getTypePtr()->getNumExpansions();
           NumExpansions = OrigNumExpansions;
           if (getDerived().TryExpandParameterPacks(ExpansionTL.getEllipsisLoc(),
                                                    Pattern.getSourceRange(),
                                                    Unexpanded,
                                                    ShouldExpand,
                                                    RetainExpansion,
                                                    NumExpansions)) {
             return true;
           }
         } else {
 #ifndef NDEBUG
           const AutoType *AT =
               Pattern.getType().getTypePtr()->getContainedAutoType();
           assert((AT && (!AT->isDeduced() || AT->getDeducedType().isNull())) &&
                  "Could not find parameter packs or undeduced auto type!");
 #endif
         }
 
         if (ShouldExpand) {
           // Expand the function parameter pack into multiple, separate
           // parameters.
           getDerived().ExpandingFunctionParameterPack(OldParm);
           for (unsigned I = 0; I != *NumExpansions; ++I) {
             Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(getSema(), I);
             ParmVarDecl *NewParm
               = getDerived().TransformFunctionTypeParam(OldParm,
                                                         indexAdjustment++,
                                                         OrigNumExpansions,
                                                 /*ExpectParameterPack=*/false);
             if (!NewParm)
               return true;
 
             if (ParamInfos)
               PInfos.set(OutParamTypes.size(), ParamInfos[i]);
             OutParamTypes.push_back(NewParm->getType());
             if (PVars)
               PVars->push_back(NewParm);
           }
 
           // If we're supposed to retain a pack expansion, do so by temporarily
           // forgetting the partially-substituted parameter pack.
           if (RetainExpansion) {
             ForgetPartiallySubstitutedPackRAII Forget(getDerived());
             ParmVarDecl *NewParm
               = getDerived().TransformFunctionTypeParam(OldParm,
                                                         indexAdjustment++,
                                                         OrigNumExpansions,
                                                 /*ExpectParameterPack=*/false);
             if (!NewParm)
               return true;
 
             if (ParamInfos)
               PInfos.set(OutParamTypes.size(), ParamInfos[i]);
             OutParamTypes.push_back(NewParm->getType());
             if (PVars)
               PVars->push_back(NewParm);
           }
 
           // The next parameter should have the same adjustment as the
           // last thing we pushed, but we post-incremented indexAdjustment
           // on every push.  Also, if we push nothing, the adjustment should
           // go down by one.
           indexAdjustment--;
 
           // We're done with the pack expansion.
           continue;
         }
 
         // We'll substitute the parameter now without expanding the pack
         // expansion.
         Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(getSema(), -1);
         NewParm = getDerived().TransformFunctionTypeParam(OldParm,
                                                           indexAdjustment,
                                                           NumExpansions,
                                                   /*ExpectParameterPack=*/true);
         assert(NewParm->isParameterPack() &&
                "Parameter pack no longer a parameter pack after "
                "transformation.");
       } else {
         NewParm = getDerived().TransformFunctionTypeParam(
             OldParm, indexAdjustment, std::nullopt,
             /*ExpectParameterPack=*/false);
       }
 
       if (!NewParm)
         return true;
 
       if (ParamInfos)
         PInfos.set(OutParamTypes.size(), ParamInfos[i]);
       OutParamTypes.push_back(NewParm->getType());
       if (PVars)
         PVars->push_back(NewParm);
       continue;
     }
 
     // Deal with the possibility that we don't have a parameter
     // declaration for this parameter.
     assert(ParamTypes);
     QualType OldType = ParamTypes[i];
     bool IsPackExpansion = false;
     std::optional<unsigned> NumExpansions;
     QualType NewType;
     if (const PackExpansionType *Expansion
                                        = dyn_cast<PackExpansionType>(OldType)) {
       // We have a function parameter pack that may need to be expanded.
       QualType Pattern = Expansion->getPattern();
       SmallVector<UnexpandedParameterPack, 2> Unexpanded;
       getSema().collectUnexpandedParameterPacks(Pattern, Unexpanded);
 
       // Determine whether we should expand the parameter packs.
       bool ShouldExpand = false;
       bool RetainExpansion = false;
       if (getDerived().TryExpandParameterPacks(Loc, SourceRange(),
                                                Unexpanded,
                                                ShouldExpand,
                                                RetainExpansion,
                                                NumExpansions)) {
         return true;
       }
 
       if (ShouldExpand) {
         // Expand the function parameter pack into multiple, separate
         // parameters.
         for (unsigned I = 0; I != *NumExpansions; ++I) {
           Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(getSema(), I);
           QualType NewType = getDerived().TransformType(Pattern);
           if (NewType.isNull())
             return true;
 
           if (NewType->containsUnexpandedParameterPack()) {
             NewType = getSema().getASTContext().getPackExpansionType(
                 NewType, std::nullopt);
 
             if (NewType.isNull())
               return true;
           }
 
           if (ParamInfos)
             PInfos.set(OutParamTypes.size(), ParamInfos[i]);
           OutParamTypes.push_back(NewType);
           if (PVars)
             PVars->push_back(nullptr);
         }
 
         // We're done with the pack expansion.
         continue;
       }
 
       // If we're supposed to retain a pack expansion, do so by temporarily
       // forgetting the partially-substituted parameter pack.
       if (RetainExpansion) {
         ForgetPartiallySubstitutedPackRAII Forget(getDerived());
         QualType NewType = getDerived().TransformType(Pattern);
         if (NewType.isNull())
           return true;
 
         if (ParamInfos)
           PInfos.set(OutParamTypes.size(), ParamInfos[i]);
         OutParamTypes.push_back(NewType);
         if (PVars)
           PVars->push_back(nullptr);
       }
 
       // We'll substitute the parameter now without expanding the pack
       // expansion.
       OldType = Expansion->getPattern();
       IsPackExpansion = true;
       Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(getSema(), -1);
       NewType = getDerived().TransformType(OldType);
     } else {
       NewType = getDerived().TransformType(OldType);
     }
 
     if (NewType.isNull())
       return true;
 
     if (IsPackExpansion)
       NewType = getSema().Context.getPackExpansionType(NewType,
                                                        NumExpansions);
 
     if (ParamInfos)
       PInfos.set(OutParamTypes.size(), ParamInfos[i]);
     OutParamTypes.push_back(NewType);
     if (PVars)
       PVars->push_back(nullptr);
   }
 
 #ifndef NDEBUG
   if (PVars) {
     for (unsigned i = 0, e = PVars->size(); i != e; ++i)
       if (ParmVarDecl *parm = (*PVars)[i])
         assert(parm->getFunctionScopeIndex() == i);
   }
 #endif
 
   return false;
 }
 
 template<typename Derived>
 QualType
 TreeTransform<Derived>::TransformFunctionProtoType(TypeLocBuilder &TLB,
                                                    FunctionProtoTypeLoc TL) {
   SmallVector<QualType, 4> ExceptionStorage;
   TreeTransform *This = this; // Work around gcc.gnu.org/PR56135.
   return getDerived().TransformFunctionProtoType(
       TLB, TL, nullptr, Qualifiers(),
       [&](FunctionProtoType::ExceptionSpecInfo &ESI, bool &Changed) {
         return This->getDerived().TransformExceptionSpec(
             TL.getBeginLoc(), ESI, ExceptionStorage, Changed);
       });
 }
 
 template<typename Derived> template<typename Fn>
 QualType TreeTransform<Derived>::TransformFunctionProtoType(
     TypeLocBuilder &TLB, FunctionProtoTypeLoc TL, CXXRecordDecl *ThisContext,
     Qualifiers ThisTypeQuals, Fn TransformExceptionSpec) {
 
   // Transform the parameters and return type.
   //
   // We are required to instantiate the params and return type in source order.
   // When the function has a trailing return type, we instantiate the
   // parameters before the return type,  since the return type can then refer
   // to the parameters themselves (via decltype, sizeof, etc.).
   //
   SmallVector<QualType, 4> ParamTypes;
   SmallVector<ParmVarDecl*, 4> ParamDecls;
   Sema::ExtParameterInfoBuilder ExtParamInfos;
   const FunctionProtoType *T = TL.getTypePtr();
 
   QualType ResultType;
 
   if (T->hasTrailingReturn()) {
     if (getDerived().TransformFunctionTypeParams(
             TL.getBeginLoc(), TL.getParams(),
             TL.getTypePtr()->param_type_begin(),
             T->getExtParameterInfosOrNull(),
             ParamTypes, &ParamDecls, ExtParamInfos))
       return QualType();
 
     {
       // C++11 [expr.prim.general]p3:
       //   If a declaration declares a member function or member function
       //   template of a class X, the expression this is a prvalue of type
       //   "pointer to cv-qualifier-seq X" between the optional cv-qualifer-seq
       //   and the end of the function-definition, member-declarator, or
       //   declarator.
       Sema::CXXThisScopeRAII ThisScope(SemaRef, ThisContext, ThisTypeQuals);
 
       ResultType = getDerived().TransformType(TLB, TL.getReturnLoc());
       if (ResultType.isNull())
         return QualType();
     }
   }
   else {
     ResultType = getDerived().TransformType(TLB, TL.getReturnLoc());
     if (ResultType.isNull())
       return QualType();
 
     if (getDerived().TransformFunctionTypeParams(
             TL.getBeginLoc(), TL.getParams(),
             TL.getTypePtr()->param_type_begin(),
             T->getExtParameterInfosOrNull(),
             ParamTypes, &ParamDecls, ExtParamInfos))
       return QualType();
   }
 
   FunctionProtoType::ExtProtoInfo EPI = T->getExtProtoInfo();
 
   bool EPIChanged = false;
   if (TransformExceptionSpec(EPI.ExceptionSpec, EPIChanged))
     return QualType();
 
   // Handle extended parameter information.
   if (auto NewExtParamInfos =
         ExtParamInfos.getPointerOrNull(ParamTypes.size())) {
     if (!EPI.ExtParameterInfos ||
         llvm::ArrayRef(EPI.ExtParameterInfos, TL.getNumParams()) !=
             llvm::ArrayRef(NewExtParamInfos, ParamTypes.size())) {
       EPIChanged = true;
     }
     EPI.ExtParameterInfos = NewExtParamInfos;
   } else if (EPI.ExtParameterInfos) {
     EPIChanged = true;
     EPI.ExtParameterInfos = nullptr;
   }
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() || ResultType != T->getReturnType() ||
       T->getParamTypes() != llvm::ArrayRef(ParamTypes) || EPIChanged) {
     Result = getDerived().RebuildFunctionProtoType(ResultType, ParamTypes, EPI);
     if (Result.isNull())
       return QualType();
   }
 
   FunctionProtoTypeLoc NewTL = TLB.push<FunctionProtoTypeLoc>(Result);
   NewTL.setLocalRangeBegin(TL.getLocalRangeBegin());
   NewTL.setLParenLoc(TL.getLParenLoc());
   NewTL.setRParenLoc(TL.getRParenLoc());
   NewTL.setExceptionSpecRange(TL.getExceptionSpecRange());
   NewTL.setLocalRangeEnd(TL.getLocalRangeEnd());
   for (unsigned i = 0, e = NewTL.getNumParams(); i != e; ++i)
     NewTL.setParam(i, ParamDecls[i]);
 
   return Result;
 }
 
 template<typename Derived>
 bool TreeTransform<Derived>::TransformExceptionSpec(
     SourceLocation Loc, FunctionProtoType::ExceptionSpecInfo &ESI,
     SmallVectorImpl<QualType> &Exceptions, bool &Changed) {
   assert(ESI.Type != EST_Uninstantiated && ESI.Type != EST_Unevaluated);
 
   // Instantiate a dynamic noexcept expression, if any.
   if (isComputedNoexcept(ESI.Type)) {
     EnterExpressionEvaluationContext Unevaluated(
         getSema(), Sema::ExpressionEvaluationContext::ConstantEvaluated);
     ExprResult NoexceptExpr = getDerived().TransformExpr(ESI.NoexceptExpr);
     if (NoexceptExpr.isInvalid())
       return true;
 
     ExceptionSpecificationType EST = ESI.Type;
     NoexceptExpr =
         getSema().ActOnNoexceptSpec(NoexceptExpr.get(), EST);
     if (NoexceptExpr.isInvalid())
       return true;
 
     if (ESI.NoexceptExpr != NoexceptExpr.get() || EST != ESI.Type)
       Changed = true;
     ESI.NoexceptExpr = NoexceptExpr.get();
     ESI.Type = EST;
   }
 
   if (ESI.Type != EST_Dynamic)
     return false;
 
   // Instantiate a dynamic exception specification's type.
   for (QualType T : ESI.Exceptions) {
     if (const PackExpansionType *PackExpansion =
             T->getAs<PackExpansionType>()) {
       Changed = true;
 
       // We have a pack expansion. Instantiate it.
       SmallVector<UnexpandedParameterPack, 2> Unexpanded;
       SemaRef.collectUnexpandedParameterPacks(PackExpansion->getPattern(),
                                               Unexpanded);
       assert(!Unexpanded.empty() && "Pack expansion without parameter packs?");
 
       // Determine whether the set of unexpanded parameter packs can and
       // should
       // be expanded.
       bool Expand = false;
       bool RetainExpansion = false;
       std::optional<unsigned> NumExpansions = PackExpansion->getNumExpansions();
       // FIXME: Track the location of the ellipsis (and track source location
       // information for the types in the exception specification in general).
       if (getDerived().TryExpandParameterPacks(
               Loc, SourceRange(), Unexpanded, Expand,
               RetainExpansion, NumExpansions))
         return true;
 
       if (!Expand) {
         // We can't expand this pack expansion into separate arguments yet;
         // just substitute into the pattern and create a new pack expansion
         // type.
         Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(getSema(), -1);
         QualType U = getDerived().TransformType(PackExpansion->getPattern());
         if (U.isNull())
           return true;
 
         U = SemaRef.Context.getPackExpansionType(U, NumExpansions);
         Exceptions.push_back(U);
         continue;
       }
 
       // Substitute into the pack expansion pattern for each slice of the
       // pack.
       for (unsigned ArgIdx = 0; ArgIdx != *NumExpansions; ++ArgIdx) {
         Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(getSema(), ArgIdx);
 
         QualType U = getDerived().TransformType(PackExpansion->getPattern());
         if (U.isNull() || SemaRef.CheckSpecifiedExceptionType(U, Loc))
           return true;
 
         Exceptions.push_back(U);
       }
     } else {
       QualType U = getDerived().TransformType(T);
       if (U.isNull() || SemaRef.CheckSpecifiedExceptionType(U, Loc))
         return true;
       if (T != U)
         Changed = true;
 
       Exceptions.push_back(U);
     }
   }
 
   ESI.Exceptions = Exceptions;
   if (ESI.Exceptions.empty())
     ESI.Type = EST_DynamicNone;
   return false;
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformFunctionNoProtoType(
                                                  TypeLocBuilder &TLB,
                                                  FunctionNoProtoTypeLoc TL) {
   const FunctionNoProtoType *T = TL.getTypePtr();
   QualType ResultType = getDerived().TransformType(TLB, TL.getReturnLoc());
   if (ResultType.isNull())
     return QualType();
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() || ResultType != T->getReturnType())
     Result = getDerived().RebuildFunctionNoProtoType(ResultType);
 
   FunctionNoProtoTypeLoc NewTL = TLB.push<FunctionNoProtoTypeLoc>(Result);
   NewTL.setLocalRangeBegin(TL.getLocalRangeBegin());
   NewTL.setLParenLoc(TL.getLParenLoc());
   NewTL.setRParenLoc(TL.getRParenLoc());
   NewTL.setLocalRangeEnd(TL.getLocalRangeEnd());
 
   return Result;
 }
 
 template <typename Derived>
 QualType TreeTransform<Derived>::TransformUnresolvedUsingType(
     TypeLocBuilder &TLB, UnresolvedUsingTypeLoc TL) {
   const UnresolvedUsingType *T = TL.getTypePtr();
   Decl *D = getDerived().TransformDecl(TL.getNameLoc(), T->getDecl());
   if (!D)
     return QualType();
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() || D != T->getDecl()) {
     Result = getDerived().RebuildUnresolvedUsingType(TL.getNameLoc(), D);
     if (Result.isNull())
       return QualType();
   }
 
   // We might get an arbitrary type spec type back.  We should at
   // least always get a type spec type, though.
   TypeSpecTypeLoc NewTL = TLB.pushTypeSpec(Result);
   NewTL.setNameLoc(TL.getNameLoc());
 
   return Result;
 }
 
 template <typename Derived>
 QualType TreeTransform<Derived>::TransformUsingType(TypeLocBuilder &TLB,
                                                     UsingTypeLoc TL) {
   const UsingType *T = TL.getTypePtr();
 
   auto *Found = cast_or_null<UsingShadowDecl>(getDerived().TransformDecl(
       TL.getLocalSourceRange().getBegin(), T->getFoundDecl()));
   if (!Found)
     return QualType();
 
   QualType Underlying = getDerived().TransformType(T->desugar());
   if (Underlying.isNull())
     return QualType();
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() || Found != T->getFoundDecl() ||
       Underlying != T->getUnderlyingType()) {
     Result = getDerived().RebuildUsingType(Found, Underlying);
     if (Result.isNull())
       return QualType();
   }
 
   TLB.pushTypeSpec(Result).setNameLoc(TL.getNameLoc());
   return Result;
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformTypedefType(TypeLocBuilder &TLB,
                                                       TypedefTypeLoc TL) {
   const TypedefType *T = TL.getTypePtr();
   TypedefNameDecl *Typedef
     = cast_or_null<TypedefNameDecl>(getDerived().TransformDecl(TL.getNameLoc(),
                                                                T->getDecl()));
   if (!Typedef)
     return QualType();
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() ||
       Typedef != T->getDecl()) {
     Result = getDerived().RebuildTypedefType(Typedef);
     if (Result.isNull())
       return QualType();
   }
 
   TypedefTypeLoc NewTL = TLB.push<TypedefTypeLoc>(Result);
   NewTL.setNameLoc(TL.getNameLoc());
 
   return Result;
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformTypeOfExprType(TypeLocBuilder &TLB,
                                                       TypeOfExprTypeLoc TL) {
   // typeof expressions are not potentially evaluated contexts
   EnterExpressionEvaluationContext Unevaluated(
       SemaRef, Sema::ExpressionEvaluationContext::Unevaluated,
       Sema::ReuseLambdaContextDecl);
 
   ExprResult E = getDerived().TransformExpr(TL.getUnderlyingExpr());
   if (E.isInvalid())
     return QualType();
 
   E = SemaRef.HandleExprEvaluationContextForTypeof(E.get());
   if (E.isInvalid())
     return QualType();
 
   QualType Result = TL.getType();
   TypeOfKind Kind = Result->getAs<TypeOfExprType>()->getKind();
   if (getDerived().AlwaysRebuild() || E.get() != TL.getUnderlyingExpr()) {
     Result =
         getDerived().RebuildTypeOfExprType(E.get(), TL.getTypeofLoc(), Kind);
     if (Result.isNull())
       return QualType();
   }
 
   TypeOfExprTypeLoc NewTL = TLB.push<TypeOfExprTypeLoc>(Result);
   NewTL.setTypeofLoc(TL.getTypeofLoc());
   NewTL.setLParenLoc(TL.getLParenLoc());
   NewTL.setRParenLoc(TL.getRParenLoc());
 
   return Result;
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformTypeOfType(TypeLocBuilder &TLB,
                                                      TypeOfTypeLoc TL) {
   TypeSourceInfo* Old_Under_TI = TL.getUnmodifiedTInfo();
   TypeSourceInfo* New_Under_TI = getDerived().TransformType(Old_Under_TI);
   if (!New_Under_TI)
     return QualType();
 
   QualType Result = TL.getType();
   TypeOfKind Kind = Result->getAs<TypeOfType>()->getKind();
   if (getDerived().AlwaysRebuild() || New_Under_TI != Old_Under_TI) {
     Result = getDerived().RebuildTypeOfType(New_Under_TI->getType(), Kind);
     if (Result.isNull())
       return QualType();
   }
 
   TypeOfTypeLoc NewTL = TLB.push<TypeOfTypeLoc>(Result);
   NewTL.setTypeofLoc(TL.getTypeofLoc());
   NewTL.setLParenLoc(TL.getLParenLoc());
   NewTL.setRParenLoc(TL.getRParenLoc());
   NewTL.setUnmodifiedTInfo(New_Under_TI);
 
   return Result;
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformDecltypeType(TypeLocBuilder &TLB,
                                                        DecltypeTypeLoc TL) {
   const DecltypeType *T = TL.getTypePtr();
 
   // decltype expressions are not potentially evaluated contexts
   EnterExpressionEvaluationContext Unevaluated(
       SemaRef, Sema::ExpressionEvaluationContext::Unevaluated, nullptr,
       Sema::ExpressionEvaluationContextRecord::EK_Decltype);
 
   ExprResult E = getDerived().TransformExpr(T->getUnderlyingExpr());
   if (E.isInvalid())
     return QualType();
 
   E = getSema().ActOnDecltypeExpression(E.get());
   if (E.isInvalid())
     return QualType();
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() ||
       E.get() != T->getUnderlyingExpr()) {
     Result = getDerived().RebuildDecltypeType(E.get(), TL.getDecltypeLoc());
     if (Result.isNull())
       return QualType();
   }
   else E.get();
 
   DecltypeTypeLoc NewTL = TLB.push<DecltypeTypeLoc>(Result);
   NewTL.setDecltypeLoc(TL.getDecltypeLoc());
   NewTL.setRParenLoc(TL.getRParenLoc());
   return Result;
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformUnaryTransformType(
                                                             TypeLocBuilder &TLB,
                                                      UnaryTransformTypeLoc TL) {
   QualType Result = TL.getType();
   if (Result->isDependentType()) {
     const UnaryTransformType *T = TL.getTypePtr();
     QualType NewBase =
       getDerived().TransformType(TL.getUnderlyingTInfo())->getType();
     Result = getDerived().RebuildUnaryTransformType(NewBase,
                                                     T->getUTTKind(),
                                                     TL.getKWLoc());
     if (Result.isNull())
       return QualType();
   }
 
   UnaryTransformTypeLoc NewTL = TLB.push<UnaryTransformTypeLoc>(Result);
   NewTL.setKWLoc(TL.getKWLoc());
   NewTL.setParensRange(TL.getParensRange());
   NewTL.setUnderlyingTInfo(TL.getUnderlyingTInfo());
   return Result;
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformDeducedTemplateSpecializationType(
     TypeLocBuilder &TLB, DeducedTemplateSpecializationTypeLoc TL) {
   const DeducedTemplateSpecializationType *T = TL.getTypePtr();
 
   CXXScopeSpec SS;
   TemplateName TemplateName = getDerived().TransformTemplateName(
       SS, T->getTemplateName(), TL.getTemplateNameLoc());
   if (TemplateName.isNull())
     return QualType();
 
   QualType OldDeduced = T->getDeducedType();
   QualType NewDeduced;
   if (!OldDeduced.isNull()) {
     NewDeduced = getDerived().TransformType(OldDeduced);
     if (NewDeduced.isNull())
       return QualType();
   }
 
   QualType Result = getDerived().RebuildDeducedTemplateSpecializationType(
       TemplateName, NewDeduced);
   if (Result.isNull())
     return QualType();
 
   DeducedTemplateSpecializationTypeLoc NewTL =
       TLB.push<DeducedTemplateSpecializationTypeLoc>(Result);
   NewTL.setTemplateNameLoc(TL.getTemplateNameLoc());
 
   return Result;
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformRecordType(TypeLocBuilder &TLB,
                                                      RecordTypeLoc TL) {
   const RecordType *T = TL.getTypePtr();
   RecordDecl *Record
     = cast_or_null<RecordDecl>(getDerived().TransformDecl(TL.getNameLoc(),
                                                           T->getDecl()));
   if (!Record)
     return QualType();
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() ||
       Record != T->getDecl()) {
     Result = getDerived().RebuildRecordType(Record);
     if (Result.isNull())
       return QualType();
   }
 
   RecordTypeLoc NewTL = TLB.push<RecordTypeLoc>(Result);
   NewTL.setNameLoc(TL.getNameLoc());
 
   return Result;
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformEnumType(TypeLocBuilder &TLB,
                                                    EnumTypeLoc TL) {
   const EnumType *T = TL.getTypePtr();
   EnumDecl *Enum
     = cast_or_null<EnumDecl>(getDerived().TransformDecl(TL.getNameLoc(),
                                                         T->getDecl()));
   if (!Enum)
     return QualType();
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() ||
       Enum != T->getDecl()) {
     Result = getDerived().RebuildEnumType(Enum);
     if (Result.isNull())
       return QualType();
   }
 
   EnumTypeLoc NewTL = TLB.push<EnumTypeLoc>(Result);
   NewTL.setNameLoc(TL.getNameLoc());
 
   return Result;
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformInjectedClassNameType(
                                          TypeLocBuilder &TLB,
                                          InjectedClassNameTypeLoc TL) {
   Decl *D = getDerived().TransformDecl(TL.getNameLoc(),
                                        TL.getTypePtr()->getDecl());
   if (!D) return QualType();
 
   QualType T = SemaRef.Context.getTypeDeclType(cast<TypeDecl>(D));
   TLB.pushTypeSpec(T).setNameLoc(TL.getNameLoc());
   return T;
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformTemplateTypeParmType(
                                                 TypeLocBuilder &TLB,
                                                 TemplateTypeParmTypeLoc TL) {
   return getDerived().TransformTemplateTypeParmType(
       TLB, TL,
       /*SuppressObjCLifetime=*/false);
 }
 
 template <typename Derived>
 QualType TreeTransform<Derived>::TransformTemplateTypeParmType(
     TypeLocBuilder &TLB, TemplateTypeParmTypeLoc TL, bool) {
   return TransformTypeSpecType(TLB, TL);
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformSubstTemplateTypeParmType(
                                          TypeLocBuilder &TLB,
                                          SubstTemplateTypeParmTypeLoc TL) {
   const SubstTemplateTypeParmType *T = TL.getTypePtr();
 
   Decl *NewReplaced =
       getDerived().TransformDecl(TL.getNameLoc(), T->getAssociatedDecl());
 
   // Substitute into the replacement type, which itself might involve something
   // that needs to be transformed. This only tends to occur with default
   // template arguments of template template parameters.
   TemporaryBase Rebase(*this, TL.getNameLoc(), DeclarationName());
   QualType Replacement = getDerived().TransformType(T->getReplacementType());
   if (Replacement.isNull())
     return QualType();
 
   QualType Result = SemaRef.Context.getSubstTemplateTypeParmType(
       Replacement, NewReplaced, T->getIndex(), T->getPackIndex());
 
   // Propagate type-source information.
   SubstTemplateTypeParmTypeLoc NewTL
     = TLB.push<SubstTemplateTypeParmTypeLoc>(Result);
   NewTL.setNameLoc(TL.getNameLoc());
   return Result;
 
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformSubstTemplateTypeParmPackType(
                                           TypeLocBuilder &TLB,
                                           SubstTemplateTypeParmPackTypeLoc TL) {
   return getDerived().TransformSubstTemplateTypeParmPackType(
       TLB, TL, /*SuppressObjCLifetime=*/false);
 }
 
 template <typename Derived>
 QualType TreeTransform<Derived>::TransformSubstTemplateTypeParmPackType(
     TypeLocBuilder &TLB, SubstTemplateTypeParmPackTypeLoc TL, bool) {
   return TransformTypeSpecType(TLB, TL);
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformTemplateSpecializationType(
                                                         TypeLocBuilder &TLB,
                                            TemplateSpecializationTypeLoc TL) {
   const TemplateSpecializationType *T = TL.getTypePtr();
 
   // The nested-name-specifier never matters in a TemplateSpecializationType,
   // because we can't have a dependent nested-name-specifier anyway.
   CXXScopeSpec SS;
   TemplateName Template
     = getDerived().TransformTemplateName(SS, T->getTemplateName(),
                                          TL.getTemplateNameLoc());
   if (Template.isNull())
     return QualType();
 
   return getDerived().TransformTemplateSpecializationType(TLB, TL, Template);
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformAtomicType(TypeLocBuilder &TLB,
                                                      AtomicTypeLoc TL) {
   QualType ValueType = getDerived().TransformType(TLB, TL.getValueLoc());
   if (ValueType.isNull())
     return QualType();
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() ||
       ValueType != TL.getValueLoc().getType()) {
     Result = getDerived().RebuildAtomicType(ValueType, TL.getKWLoc());
     if (Result.isNull())
       return QualType();
   }
 
   AtomicTypeLoc NewTL = TLB.push<AtomicTypeLoc>(Result);
   NewTL.setKWLoc(TL.getKWLoc());
   NewTL.setLParenLoc(TL.getLParenLoc());
   NewTL.setRParenLoc(TL.getRParenLoc());
 
   return Result;
 }
 
 template <typename Derived>
 QualType TreeTransform<Derived>::TransformPipeType(TypeLocBuilder &TLB,
                                                    PipeTypeLoc TL) {
   QualType ValueType = getDerived().TransformType(TLB, TL.getValueLoc());
   if (ValueType.isNull())
     return QualType();
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() || ValueType != TL.getValueLoc().getType()) {
     const PipeType *PT = Result->castAs<PipeType>();
     bool isReadPipe = PT->isReadOnly();
     Result = getDerived().RebuildPipeType(ValueType, TL.getKWLoc(), isReadPipe);
     if (Result.isNull())
       return QualType();
   }
 
   PipeTypeLoc NewTL = TLB.push<PipeTypeLoc>(Result);
   NewTL.setKWLoc(TL.getKWLoc());
 
   return Result;
 }
 
 template <typename Derived>
 QualType TreeTransform<Derived>::TransformBitIntType(TypeLocBuilder &TLB,
                                                      BitIntTypeLoc TL) {
   const BitIntType *EIT = TL.getTypePtr();
   QualType Result = TL.getType();
 
   if (getDerived().AlwaysRebuild()) {
     Result = getDerived().RebuildBitIntType(EIT->isUnsigned(),
                                             EIT->getNumBits(), TL.getNameLoc());
     if (Result.isNull())
       return QualType();
   }
 
   BitIntTypeLoc NewTL = TLB.push<BitIntTypeLoc>(Result);
   NewTL.setNameLoc(TL.getNameLoc());
   return Result;
 }
 
 template <typename Derived>
 QualType TreeTransform<Derived>::TransformDependentBitIntType(
     TypeLocBuilder &TLB, DependentBitIntTypeLoc TL) {
   const DependentBitIntType *EIT = TL.getTypePtr();
 
   EnterExpressionEvaluationContext Unevaluated(
       SemaRef, Sema::ExpressionEvaluationContext::ConstantEvaluated);
   ExprResult BitsExpr = getDerived().TransformExpr(EIT->getNumBitsExpr());
   BitsExpr = SemaRef.ActOnConstantExpression(BitsExpr);
 
   if (BitsExpr.isInvalid())
     return QualType();
 
   QualType Result = TL.getType();
 
   if (getDerived().AlwaysRebuild() || BitsExpr.get() != EIT->getNumBitsExpr()) {
     Result = getDerived().RebuildDependentBitIntType(
         EIT->isUnsigned(), BitsExpr.get(), TL.getNameLoc());
 
     if (Result.isNull())
       return QualType();
   }
 
   if (isa<DependentBitIntType>(Result)) {
     DependentBitIntTypeLoc NewTL = TLB.push<DependentBitIntTypeLoc>(Result);
     NewTL.setNameLoc(TL.getNameLoc());
   } else {
     BitIntTypeLoc NewTL = TLB.push<BitIntTypeLoc>(Result);
     NewTL.setNameLoc(TL.getNameLoc());
   }
   return Result;
 }
 
   /// Simple iterator that traverses the template arguments in a
   /// container that provides a \c getArgLoc() member function.
   ///
   /// This iterator is intended to be used with the iterator form of
   /// \c TreeTransform<Derived>::TransformTemplateArguments().
   template<typename ArgLocContainer>
   class TemplateArgumentLocContainerIterator {
     ArgLocContainer *Container;
     unsigned Index;
 
   public:
     typedef TemplateArgumentLoc value_type;
     typedef TemplateArgumentLoc reference;
     typedef int difference_type;
     typedef std::input_iterator_tag iterator_category;
 
     class pointer {
       TemplateArgumentLoc Arg;
 
     public:
       explicit pointer(TemplateArgumentLoc Arg) : Arg(Arg) { }
 
       const TemplateArgumentLoc *operator->() const {
         return &Arg;
       }
     };
 
 
     TemplateArgumentLocContainerIterator() {}
 
     TemplateArgumentLocContainerIterator(ArgLocContainer &Container,
                                  unsigned Index)
       : Container(&Container), Index(Index) { }
 
     TemplateArgumentLocContainerIterator &operator++() {
       ++Index;
       return *this;
     }
 
     TemplateArgumentLocContainerIterator operator++(int) {
       TemplateArgumentLocContainerIterator Old(*this);
       ++(*this);
       return Old;
     }
 
     TemplateArgumentLoc operator*() const {
       return Container->getArgLoc(Index);
     }
 
     pointer operator->() const {
       return pointer(Container->getArgLoc(Index));
     }
 
     friend bool operator==(const TemplateArgumentLocContainerIterator &X,
                            const TemplateArgumentLocContainerIterator &Y) {
       return X.Container == Y.Container && X.Index == Y.Index;
     }
 
     friend bool operator!=(const TemplateArgumentLocContainerIterator &X,
                            const TemplateArgumentLocContainerIterator &Y) {
       return !(X == Y);
     }
   };
 
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformAutoType(TypeLocBuilder &TLB,
                                                    AutoTypeLoc TL) {
   const AutoType *T = TL.getTypePtr();
   QualType OldDeduced = T->getDeducedType();
   QualType NewDeduced;
   if (!OldDeduced.isNull()) {
     NewDeduced = getDerived().TransformType(OldDeduced);
     if (NewDeduced.isNull())
       return QualType();
   }
 
   ConceptDecl *NewCD = nullptr;
   TemplateArgumentListInfo NewTemplateArgs;
   NestedNameSpecifierLoc NewNestedNameSpec;
   if (T->isConstrained()) {
     NewCD = cast_or_null<ConceptDecl>(getDerived().TransformDecl(
         TL.getConceptNameLoc(), T->getTypeConstraintConcept()));
 
     NewTemplateArgs.setLAngleLoc(TL.getLAngleLoc());
     NewTemplateArgs.setRAngleLoc(TL.getRAngleLoc());
     typedef TemplateArgumentLocContainerIterator<AutoTypeLoc> ArgIterator;
     if (getDerived().TransformTemplateArguments(ArgIterator(TL, 0),
                                                 ArgIterator(TL,
                                                             TL.getNumArgs()),
                                                 NewTemplateArgs))
       return QualType();
 
     if (TL.getNestedNameSpecifierLoc()) {
       NewNestedNameSpec
         = getDerived().TransformNestedNameSpecifierLoc(
             TL.getNestedNameSpecifierLoc());
       if (!NewNestedNameSpec)
         return QualType();
     }
   }
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() || NewDeduced != OldDeduced ||
       T->isDependentType() || T->isConstrained()) {
     // FIXME: Maybe don't rebuild if all template arguments are the same.
     llvm::SmallVector<TemplateArgument, 4> NewArgList;
     NewArgList.reserve(NewTemplateArgs.size());
     for (const auto &ArgLoc : NewTemplateArgs.arguments())
       NewArgList.push_back(ArgLoc.getArgument());
     Result = getDerived().RebuildAutoType(NewDeduced, T->getKeyword(), NewCD,
                                           NewArgList);
     if (Result.isNull())
       return QualType();
   }
 
   AutoTypeLoc NewTL = TLB.push<AutoTypeLoc>(Result);
   NewTL.setNameLoc(TL.getNameLoc());
   NewTL.setNestedNameSpecifierLoc(NewNestedNameSpec);
   NewTL.setTemplateKWLoc(TL.getTemplateKWLoc());
   NewTL.setConceptNameLoc(TL.getConceptNameLoc());
   NewTL.setFoundDecl(TL.getFoundDecl());
   NewTL.setLAngleLoc(TL.getLAngleLoc());
   NewTL.setRAngleLoc(TL.getRAngleLoc());
   NewTL.setRParenLoc(TL.getRParenLoc());
   for (unsigned I = 0; I < NewTL.getNumArgs(); ++I)
     NewTL.setArgLocInfo(I, NewTemplateArgs.arguments()[I].getLocInfo());
 
   return Result;
 }
 
 template <typename Derived>
 QualType TreeTransform<Derived>::TransformTemplateSpecializationType(
                                                         TypeLocBuilder &TLB,
                                            TemplateSpecializationTypeLoc TL,
                                                       TemplateName Template) {
   TemplateArgumentListInfo NewTemplateArgs;
   NewTemplateArgs.setLAngleLoc(TL.getLAngleLoc());
   NewTemplateArgs.setRAngleLoc(TL.getRAngleLoc());
   typedef TemplateArgumentLocContainerIterator<TemplateSpecializationTypeLoc>
     ArgIterator;
   if (getDerived().TransformTemplateArguments(ArgIterator(TL, 0),
                                               ArgIterator(TL, TL.getNumArgs()),
                                               NewTemplateArgs))
     return QualType();
 
   // FIXME: maybe don't rebuild if all the template arguments are the same.
 
   QualType Result =
     getDerived().RebuildTemplateSpecializationType(Template,
                                                    TL.getTemplateNameLoc(),
                                                    NewTemplateArgs);
 
   if (!Result.isNull()) {
     // Specializations of template template parameters are represented as
     // TemplateSpecializationTypes, and substitution of type alias templates
     // within a dependent context can transform them into
     // DependentTemplateSpecializationTypes.
     if (isa<DependentTemplateSpecializationType>(Result)) {
       DependentTemplateSpecializationTypeLoc NewTL
         = TLB.push<DependentTemplateSpecializationTypeLoc>(Result);
       NewTL.setElaboratedKeywordLoc(SourceLocation());
       NewTL.setQualifierLoc(NestedNameSpecifierLoc());
       NewTL.setTemplateKeywordLoc(TL.getTemplateKeywordLoc());
       NewTL.setTemplateNameLoc(TL.getTemplateNameLoc());
       NewTL.setLAngleLoc(TL.getLAngleLoc());
       NewTL.setRAngleLoc(TL.getRAngleLoc());
       for (unsigned i = 0, e = NewTemplateArgs.size(); i != e; ++i)
         NewTL.setArgLocInfo(i, NewTemplateArgs[i].getLocInfo());
       return Result;
     }
 
     TemplateSpecializationTypeLoc NewTL
       = TLB.push<TemplateSpecializationTypeLoc>(Result);
     NewTL.setTemplateKeywordLoc(TL.getTemplateKeywordLoc());
     NewTL.setTemplateNameLoc(TL.getTemplateNameLoc());
     NewTL.setLAngleLoc(TL.getLAngleLoc());
     NewTL.setRAngleLoc(TL.getRAngleLoc());
     for (unsigned i = 0, e = NewTemplateArgs.size(); i != e; ++i)
       NewTL.setArgLocInfo(i, NewTemplateArgs[i].getLocInfo());
   }
 
   return Result;
 }
 
 template <typename Derived>
 QualType TreeTransform<Derived>::TransformDependentTemplateSpecializationType(
                                      TypeLocBuilder &TLB,
                                      DependentTemplateSpecializationTypeLoc TL,
                                      TemplateName Template,
                                      CXXScopeSpec &SS) {
   TemplateArgumentListInfo NewTemplateArgs;
   NewTemplateArgs.setLAngleLoc(TL.getLAngleLoc());
   NewTemplateArgs.setRAngleLoc(TL.getRAngleLoc());
   typedef TemplateArgumentLocContainerIterator<
             DependentTemplateSpecializationTypeLoc> ArgIterator;
   if (getDerived().TransformTemplateArguments(ArgIterator(TL, 0),
                                               ArgIterator(TL, TL.getNumArgs()),
                                               NewTemplateArgs))
     return QualType();
 
   // FIXME: maybe don't rebuild if all the template arguments are the same.
 
   if (DependentTemplateName *DTN = Template.getAsDependentTemplateName()) {
     QualType Result = getSema().Context.getDependentTemplateSpecializationType(
         TL.getTypePtr()->getKeyword(), DTN->getQualifier(),
         DTN->getIdentifier(), NewTemplateArgs.arguments());
 
     DependentTemplateSpecializationTypeLoc NewTL
       = TLB.push<DependentTemplateSpecializationTypeLoc>(Result);
     NewTL.setElaboratedKeywordLoc(TL.getElaboratedKeywordLoc());
     NewTL.setQualifierLoc(SS.getWithLocInContext(SemaRef.Context));
     NewTL.setTemplateKeywordLoc(TL.getTemplateKeywordLoc());
     NewTL.setTemplateNameLoc(TL.getTemplateNameLoc());
     NewTL.setLAngleLoc(TL.getLAngleLoc());
     NewTL.setRAngleLoc(TL.getRAngleLoc());
     for (unsigned i = 0, e = NewTemplateArgs.size(); i != e; ++i)
       NewTL.setArgLocInfo(i, NewTemplateArgs[i].getLocInfo());
     return Result;
   }
 
   QualType Result
     = getDerived().RebuildTemplateSpecializationType(Template,
                                                      TL.getTemplateNameLoc(),
                                                      NewTemplateArgs);
 
   if (!Result.isNull()) {
     /// FIXME: Wrap this in an elaborated-type-specifier?
     TemplateSpecializationTypeLoc NewTL
       = TLB.push<TemplateSpecializationTypeLoc>(Result);
     NewTL.setTemplateKeywordLoc(TL.getTemplateKeywordLoc());
     NewTL.setTemplateNameLoc(TL.getTemplateNameLoc());
     NewTL.setLAngleLoc(TL.getLAngleLoc());
     NewTL.setRAngleLoc(TL.getRAngleLoc());
     for (unsigned i = 0, e = NewTemplateArgs.size(); i != e; ++i)
       NewTL.setArgLocInfo(i, NewTemplateArgs[i].getLocInfo());
   }
 
   return Result;
 }
 
 template<typename Derived>
 QualType
 TreeTransform<Derived>::TransformElaboratedType(TypeLocBuilder &TLB,
                                                 ElaboratedTypeLoc TL) {
   const ElaboratedType *T = TL.getTypePtr();
 
   NestedNameSpecifierLoc QualifierLoc;
   // NOTE: the qualifier in an ElaboratedType is optional.
   if (TL.getQualifierLoc()) {
     QualifierLoc
       = getDerived().TransformNestedNameSpecifierLoc(TL.getQualifierLoc());
     if (!QualifierLoc)
       return QualType();
   }
 
   QualType NamedT = getDerived().TransformType(TLB, TL.getNamedTypeLoc());
   if (NamedT.isNull())
     return QualType();
 
   // C++0x [dcl.type.elab]p2:
   //   If the identifier resolves to a typedef-name or the simple-template-id
   //   resolves to an alias template specialization, the
   //   elaborated-type-specifier is ill-formed.
   if (T->getKeyword() != ETK_None && T->getKeyword() != ETK_Typename) {
     if (const TemplateSpecializationType *TST =
           NamedT->getAs<TemplateSpecializationType>()) {
       TemplateName Template = TST->getTemplateName();
       if (TypeAliasTemplateDecl *TAT = dyn_cast_or_null<TypeAliasTemplateDecl>(
               Template.getAsTemplateDecl())) {
         SemaRef.Diag(TL.getNamedTypeLoc().getBeginLoc(),
                      diag::err_tag_reference_non_tag)
             << TAT << Sema::NTK_TypeAliasTemplate
             << ElaboratedType::getTagTypeKindForKeyword(T->getKeyword());
         SemaRef.Diag(TAT->getLocation(), diag::note_declared_at);
       }
     }
   }
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() ||
       QualifierLoc != TL.getQualifierLoc() ||
       NamedT != T->getNamedType()) {
     Result = getDerived().RebuildElaboratedType(TL.getElaboratedKeywordLoc(),
                                                 T->getKeyword(),
                                                 QualifierLoc, NamedT);
     if (Result.isNull())
       return QualType();
   }
 
   ElaboratedTypeLoc NewTL = TLB.push<ElaboratedTypeLoc>(Result);
   NewTL.setElaboratedKeywordLoc(TL.getElaboratedKeywordLoc());
   NewTL.setQualifierLoc(QualifierLoc);
   return Result;
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformAttributedType(
                                                 TypeLocBuilder &TLB,
                                                 AttributedTypeLoc TL) {
   const AttributedType *oldType = TL.getTypePtr();
   QualType modifiedType = getDerived().TransformType(TLB, TL.getModifiedLoc());
   if (modifiedType.isNull())
     return QualType();
 
   // oldAttr can be null if we started with a QualType rather than a TypeLoc.
   const Attr *oldAttr = TL.getAttr();
   const Attr *newAttr = oldAttr ? getDerived().TransformAttr(oldAttr) : nullptr;
   if (oldAttr && !newAttr)
     return QualType();
 
   QualType result = TL.getType();
 
   // FIXME: dependent operand expressions?
   if (getDerived().AlwaysRebuild() ||
       modifiedType != oldType->getModifiedType()) {
     // TODO: this is really lame; we should really be rebuilding the
     // equivalent type from first principles.
     QualType equivalentType
       = getDerived().TransformType(oldType->getEquivalentType());
     if (equivalentType.isNull())
       return QualType();
 
     // Check whether we can add nullability; it is only represented as
     // type sugar, and therefore cannot be diagnosed in any other way.
     if (auto nullability = oldType->getImmediateNullability()) {
       if (!modifiedType->canHaveNullability()) {
         SemaRef.Diag((TL.getAttr() ? TL.getAttr()->getLocation()
                                    : TL.getModifiedLoc().getBeginLoc()),
                      diag::err_nullability_nonpointer)
             << DiagNullabilityKind(*nullability, false) << modifiedType;
         return QualType();
       }
     }
 
     result = SemaRef.Context.getAttributedType(TL.getAttrKind(),
                                                modifiedType,
                                                equivalentType);
   }
 
   AttributedTypeLoc newTL = TLB.push<AttributedTypeLoc>(result);
   newTL.setAttr(newAttr);
   return result;
 }
 
 template <typename Derived>
 QualType TreeTransform<Derived>::TransformBTFTagAttributedType(
     TypeLocBuilder &TLB, BTFTagAttributedTypeLoc TL) {
   // The BTFTagAttributedType is available for C only.
   llvm_unreachable("Unexpected TreeTransform for BTFTagAttributedType");
 }
 
 template<typename Derived>
 QualType
 TreeTransform<Derived>::TransformParenType(TypeLocBuilder &TLB,
                                            ParenTypeLoc TL) {
   QualType Inner = getDerived().TransformType(TLB, TL.getInnerLoc());
   if (Inner.isNull())
     return QualType();
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() ||
       Inner != TL.getInnerLoc().getType()) {
     Result = getDerived().RebuildParenType(Inner);
     if (Result.isNull())
       return QualType();
   }
 
   ParenTypeLoc NewTL = TLB.push<ParenTypeLoc>(Result);
   NewTL.setLParenLoc(TL.getLParenLoc());
   NewTL.setRParenLoc(TL.getRParenLoc());
   return Result;
 }
 
 template <typename Derived>
 QualType
 TreeTransform<Derived>::TransformMacroQualifiedType(TypeLocBuilder &TLB,
                                                     MacroQualifiedTypeLoc TL) {
   QualType Inner = getDerived().TransformType(TLB, TL.getInnerLoc());
   if (Inner.isNull())
     return QualType();
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() || Inner != TL.getInnerLoc().getType()) {
     Result =
         getDerived().RebuildMacroQualifiedType(Inner, TL.getMacroIdentifier());
     if (Result.isNull())
       return QualType();
   }
 
   MacroQualifiedTypeLoc NewTL = TLB.push<MacroQualifiedTypeLoc>(Result);
   NewTL.setExpansionLoc(TL.getExpansionLoc());
   return Result;
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformDependentNameType(
     TypeLocBuilder &TLB, DependentNameTypeLoc TL) {
   return TransformDependentNameType(TLB, TL, false);
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformDependentNameType(
     TypeLocBuilder &TLB, DependentNameTypeLoc TL, bool DeducedTSTContext) {
   const DependentNameType *T = TL.getTypePtr();
 
   NestedNameSpecifierLoc QualifierLoc
     = getDerived().TransformNestedNameSpecifierLoc(TL.getQualifierLoc());
   if (!QualifierLoc)
     return QualType();
 
   QualType Result
     = getDerived().RebuildDependentNameType(T->getKeyword(),
                                             TL.getElaboratedKeywordLoc(),
                                             QualifierLoc,
                                             T->getIdentifier(),
                                             TL.getNameLoc(),
                                             DeducedTSTContext);
   if (Result.isNull())
     return QualType();
 
   if (const ElaboratedType* ElabT = Result->getAs<ElaboratedType>()) {
     QualType NamedT = ElabT->getNamedType();
     TLB.pushTypeSpec(NamedT).setNameLoc(TL.getNameLoc());
 
     ElaboratedTypeLoc NewTL = TLB.push<ElaboratedTypeLoc>(Result);
     NewTL.setElaboratedKeywordLoc(TL.getElaboratedKeywordLoc());
     NewTL.setQualifierLoc(QualifierLoc);
   } else {
     DependentNameTypeLoc NewTL = TLB.push<DependentNameTypeLoc>(Result);
     NewTL.setElaboratedKeywordLoc(TL.getElaboratedKeywordLoc());
     NewTL.setQualifierLoc(QualifierLoc);
     NewTL.setNameLoc(TL.getNameLoc());
   }
   return Result;
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::
           TransformDependentTemplateSpecializationType(TypeLocBuilder &TLB,
                                  DependentTemplateSpecializationTypeLoc TL) {
   NestedNameSpecifierLoc QualifierLoc;
   if (TL.getQualifierLoc()) {
     QualifierLoc
       = getDerived().TransformNestedNameSpecifierLoc(TL.getQualifierLoc());
     if (!QualifierLoc)
       return QualType();
   }
 
   return getDerived()
            .TransformDependentTemplateSpecializationType(TLB, TL, QualifierLoc);
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::
 TransformDependentTemplateSpecializationType(TypeLocBuilder &TLB,
                                    DependentTemplateSpecializationTypeLoc TL,
                                        NestedNameSpecifierLoc QualifierLoc) {
   const DependentTemplateSpecializationType *T = TL.getTypePtr();
 
   TemplateArgumentListInfo NewTemplateArgs;
   NewTemplateArgs.setLAngleLoc(TL.getLAngleLoc());
   NewTemplateArgs.setRAngleLoc(TL.getRAngleLoc());
 
   typedef TemplateArgumentLocContainerIterator<
   DependentTemplateSpecializationTypeLoc> ArgIterator;
   if (getDerived().TransformTemplateArguments(ArgIterator(TL, 0),
                                               ArgIterator(TL, TL.getNumArgs()),
                                               NewTemplateArgs))
     return QualType();
 
   QualType Result = getDerived().RebuildDependentTemplateSpecializationType(
       T->getKeyword(), QualifierLoc, TL.getTemplateKeywordLoc(),
       T->getIdentifier(), TL.getTemplateNameLoc(), NewTemplateArgs,
       /*AllowInjectedClassName*/ false);
   if (Result.isNull())
     return QualType();
 
   if (const ElaboratedType *ElabT = dyn_cast<ElaboratedType>(Result)) {
     QualType NamedT = ElabT->getNamedType();
 
     // Copy information relevant to the template specialization.
     TemplateSpecializationTypeLoc NamedTL
       = TLB.push<TemplateSpecializationTypeLoc>(NamedT);
     NamedTL.setTemplateKeywordLoc(TL.getTemplateKeywordLoc());
     NamedTL.setTemplateNameLoc(TL.getTemplateNameLoc());
     NamedTL.setLAngleLoc(TL.getLAngleLoc());
     NamedTL.setRAngleLoc(TL.getRAngleLoc());
     for (unsigned I = 0, E = NewTemplateArgs.size(); I != E; ++I)
       NamedTL.setArgLocInfo(I, NewTemplateArgs[I].getLocInfo());
 
     // Copy information relevant to the elaborated type.
     ElaboratedTypeLoc NewTL = TLB.push<ElaboratedTypeLoc>(Result);
     NewTL.setElaboratedKeywordLoc(TL.getElaboratedKeywordLoc());
     NewTL.setQualifierLoc(QualifierLoc);
   } else if (isa<DependentTemplateSpecializationType>(Result)) {
     DependentTemplateSpecializationTypeLoc SpecTL
       = TLB.push<DependentTemplateSpecializationTypeLoc>(Result);
     SpecTL.setElaboratedKeywordLoc(TL.getElaboratedKeywordLoc());
     SpecTL.setQualifierLoc(QualifierLoc);
     SpecTL.setTemplateKeywordLoc(TL.getTemplateKeywordLoc());
     SpecTL.setTemplateNameLoc(TL.getTemplateNameLoc());
     SpecTL.setLAngleLoc(TL.getLAngleLoc());
     SpecTL.setRAngleLoc(TL.getRAngleLoc());
     for (unsigned I = 0, E = NewTemplateArgs.size(); I != E; ++I)
       SpecTL.setArgLocInfo(I, NewTemplateArgs[I].getLocInfo());
   } else {
     TemplateSpecializationTypeLoc SpecTL
       = TLB.push<TemplateSpecializationTypeLoc>(Result);
     SpecTL.setTemplateKeywordLoc(TL.getTemplateKeywordLoc());
     SpecTL.setTemplateNameLoc(TL.getTemplateNameLoc());
     SpecTL.setLAngleLoc(TL.getLAngleLoc());
     SpecTL.setRAngleLoc(TL.getRAngleLoc());
     for (unsigned I = 0, E = NewTemplateArgs.size(); I != E; ++I)
       SpecTL.setArgLocInfo(I, NewTemplateArgs[I].getLocInfo());
   }
   return Result;
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::TransformPackExpansionType(TypeLocBuilder &TLB,
                                                       PackExpansionTypeLoc TL) {
   QualType Pattern
     = getDerived().TransformType(TLB, TL.getPatternLoc());
   if (Pattern.isNull())
     return QualType();
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() ||
       Pattern != TL.getPatternLoc().getType()) {
     Result = getDerived().RebuildPackExpansionType(Pattern,
                                            TL.getPatternLoc().getSourceRange(),
                                                    TL.getEllipsisLoc(),
                                            TL.getTypePtr()->getNumExpansions());
     if (Result.isNull())
       return QualType();
   }
 
   PackExpansionTypeLoc NewT = TLB.push<PackExpansionTypeLoc>(Result);
   NewT.setEllipsisLoc(TL.getEllipsisLoc());
   return Result;
 }
 
 template<typename Derived>
 QualType
 TreeTransform<Derived>::TransformObjCInterfaceType(TypeLocBuilder &TLB,
                                                    ObjCInterfaceTypeLoc TL) {
   // ObjCInterfaceType is never dependent.
   TLB.pushFullCopy(TL);
   return TL.getType();
 }
 
 template<typename Derived>
 QualType
 TreeTransform<Derived>::TransformObjCTypeParamType(TypeLocBuilder &TLB,
                                                    ObjCTypeParamTypeLoc TL) {
   const ObjCTypeParamType *T = TL.getTypePtr();
   ObjCTypeParamDecl *OTP = cast_or_null<ObjCTypeParamDecl>(
       getDerived().TransformDecl(T->getDecl()->getLocation(), T->getDecl()));
   if (!OTP)
     return QualType();
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() ||
       OTP != T->getDecl()) {
     Result = getDerived().RebuildObjCTypeParamType(
         OTP, TL.getProtocolLAngleLoc(),
         llvm::ArrayRef(TL.getTypePtr()->qual_begin(), TL.getNumProtocols()),
         TL.getProtocolLocs(), TL.getProtocolRAngleLoc());
     if (Result.isNull())
       return QualType();
   }
 
   ObjCTypeParamTypeLoc NewTL = TLB.push<ObjCTypeParamTypeLoc>(Result);
   if (TL.getNumProtocols()) {
     NewTL.setProtocolLAngleLoc(TL.getProtocolLAngleLoc());
     for (unsigned i = 0, n = TL.getNumProtocols(); i != n; ++i)
       NewTL.setProtocolLoc(i, TL.getProtocolLoc(i));
     NewTL.setProtocolRAngleLoc(TL.getProtocolRAngleLoc());
   }
   return Result;
 }
 
 template<typename Derived>
 QualType
 TreeTransform<Derived>::TransformObjCObjectType(TypeLocBuilder &TLB,
                                                 ObjCObjectTypeLoc TL) {
   // Transform base type.
   QualType BaseType = getDerived().TransformType(TLB, TL.getBaseLoc());
   if (BaseType.isNull())
     return QualType();
 
   bool AnyChanged = BaseType != TL.getBaseLoc().getType();
 
   // Transform type arguments.
   SmallVector<TypeSourceInfo *, 4> NewTypeArgInfos;
   for (unsigned i = 0, n = TL.getNumTypeArgs(); i != n; ++i) {
     TypeSourceInfo *TypeArgInfo = TL.getTypeArgTInfo(i);
     TypeLoc TypeArgLoc = TypeArgInfo->getTypeLoc();
     QualType TypeArg = TypeArgInfo->getType();
     if (auto PackExpansionLoc = TypeArgLoc.getAs<PackExpansionTypeLoc>()) {
       AnyChanged = true;
 
       // We have a pack expansion. Instantiate it.
       const auto *PackExpansion = PackExpansionLoc.getType()
                                     ->castAs<PackExpansionType>();
       SmallVector<UnexpandedParameterPack, 2> Unexpanded;
       SemaRef.collectUnexpandedParameterPacks(PackExpansion->getPattern(),
                                               Unexpanded);
       assert(!Unexpanded.empty() && "Pack expansion without parameter packs?");
 
       // Determine whether the set of unexpanded parameter packs can
       // and should be expanded.
       TypeLoc PatternLoc = PackExpansionLoc.getPatternLoc();
       bool Expand = false;
       bool RetainExpansion = false;
       std::optional<unsigned> NumExpansions = PackExpansion->getNumExpansions();
       if (getDerived().TryExpandParameterPacks(
             PackExpansionLoc.getEllipsisLoc(), PatternLoc.getSourceRange(),
             Unexpanded, Expand, RetainExpansion, NumExpansions))
         return QualType();
 
       if (!Expand) {
         // We can't expand this pack expansion into separate arguments yet;
         // just substitute into the pattern and create a new pack expansion
         // type.
         Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(getSema(), -1);
 
         TypeLocBuilder TypeArgBuilder;
         TypeArgBuilder.reserve(PatternLoc.getFullDataSize());
         QualType NewPatternType = getDerived().TransformType(TypeArgBuilder,
                                                              PatternLoc);
         if (NewPatternType.isNull())
           return QualType();
 
         QualType NewExpansionType = SemaRef.Context.getPackExpansionType(
                                       NewPatternType, NumExpansions);
         auto NewExpansionLoc = TLB.push<PackExpansionTypeLoc>(NewExpansionType);
         NewExpansionLoc.setEllipsisLoc(PackExpansionLoc.getEllipsisLoc());
         NewTypeArgInfos.push_back(
           TypeArgBuilder.getTypeSourceInfo(SemaRef.Context, NewExpansionType));
         continue;
       }
 
       // Substitute into the pack expansion pattern for each slice of the
       // pack.
       for (unsigned ArgIdx = 0; ArgIdx != *NumExpansions; ++ArgIdx) {
         Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(getSema(), ArgIdx);
 
         TypeLocBuilder TypeArgBuilder;
         TypeArgBuilder.reserve(PatternLoc.getFullDataSize());
 
         QualType NewTypeArg = getDerived().TransformType(TypeArgBuilder,
                                                          PatternLoc);
         if (NewTypeArg.isNull())
           return QualType();
 
         NewTypeArgInfos.push_back(
           TypeArgBuilder.getTypeSourceInfo(SemaRef.Context, NewTypeArg));
       }
 
       continue;
     }
 
     TypeLocBuilder TypeArgBuilder;
     TypeArgBuilder.reserve(TypeArgLoc.getFullDataSize());
     QualType NewTypeArg =
         getDerived().TransformType(TypeArgBuilder, TypeArgLoc);
     if (NewTypeArg.isNull())
       return QualType();
 
     // If nothing changed, just keep the old TypeSourceInfo.
     if (NewTypeArg == TypeArg) {
       NewTypeArgInfos.push_back(TypeArgInfo);
       continue;
     }
 
     NewTypeArgInfos.push_back(
       TypeArgBuilder.getTypeSourceInfo(SemaRef.Context, NewTypeArg));
     AnyChanged = true;
   }
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() || AnyChanged) {
     // Rebuild the type.
     Result = getDerived().RebuildObjCObjectType(
         BaseType, TL.getBeginLoc(), TL.getTypeArgsLAngleLoc(), NewTypeArgInfos,
         TL.getTypeArgsRAngleLoc(), TL.getProtocolLAngleLoc(),
         llvm::ArrayRef(TL.getTypePtr()->qual_begin(), TL.getNumProtocols()),
         TL.getProtocolLocs(), TL.getProtocolRAngleLoc());
 
     if (Result.isNull())
       return QualType();
   }
 
   ObjCObjectTypeLoc NewT = TLB.push<ObjCObjectTypeLoc>(Result);
   NewT.setHasBaseTypeAsWritten(true);
   NewT.setTypeArgsLAngleLoc(TL.getTypeArgsLAngleLoc());
   for (unsigned i = 0, n = TL.getNumTypeArgs(); i != n; ++i)
     NewT.setTypeArgTInfo(i, NewTypeArgInfos[i]);
   NewT.setTypeArgsRAngleLoc(TL.getTypeArgsRAngleLoc());
   NewT.setProtocolLAngleLoc(TL.getProtocolLAngleLoc());
   for (unsigned i = 0, n = TL.getNumProtocols(); i != n; ++i)
     NewT.setProtocolLoc(i, TL.getProtocolLoc(i));
   NewT.setProtocolRAngleLoc(TL.getProtocolRAngleLoc());
   return Result;
 }
 
 template<typename Derived>
 QualType
 TreeTransform<Derived>::TransformObjCObjectPointerType(TypeLocBuilder &TLB,
                                                ObjCObjectPointerTypeLoc TL) {
   QualType PointeeType = getDerived().TransformType(TLB, TL.getPointeeLoc());
   if (PointeeType.isNull())
     return QualType();
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() ||
       PointeeType != TL.getPointeeLoc().getType()) {
     Result = getDerived().RebuildObjCObjectPointerType(PointeeType,
                                                        TL.getStarLoc());
     if (Result.isNull())
       return QualType();
   }
 
   ObjCObjectPointerTypeLoc NewT = TLB.push<ObjCObjectPointerTypeLoc>(Result);
   NewT.setStarLoc(TL.getStarLoc());
   return Result;
 }
 
 //===----------------------------------------------------------------------===//
 // Statement transformation
 //===----------------------------------------------------------------------===//
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformNullStmt(NullStmt *S) {
   return S;
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformCompoundStmt(CompoundStmt *S) {
   return getDerived().TransformCompoundStmt(S, false);
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformCompoundStmt(CompoundStmt *S,
                                               bool IsStmtExpr) {
   Sema::CompoundScopeRAII CompoundScope(getSema());
   Sema::FPFeaturesStateRAII FPSave(getSema());
   if (S->hasStoredFPFeatures())
     getSema().resetFPOptions(
         S->getStoredFPFeatures().applyOverrides(getSema().getLangOpts()));
 
   const Stmt *ExprResult = S->getStmtExprResult();
   bool SubStmtInvalid = false;
   bool SubStmtChanged = false;
   SmallVector<Stmt*, 8> Statements;
   for (auto *B : S->body()) {
     StmtResult Result = getDerived().TransformStmt(
         B, IsStmtExpr && B == ExprResult ? SDK_StmtExprResult : SDK_Discarded);
 
     if (Result.isInvalid()) {
       // Immediately fail if this was a DeclStmt, since it's very
       // likely that this will cause problems for future statements.
       if (isa<DeclStmt>(B))
         return StmtError();
 
       // Otherwise, just keep processing substatements and fail later.
       SubStmtInvalid = true;
       continue;
     }
 
     SubStmtChanged = SubStmtChanged || Result.get() != B;
     Statements.push_back(Result.getAs<Stmt>());
   }
 
   if (SubStmtInvalid)
     return StmtError();
 
   if (!getDerived().AlwaysRebuild() &&
       !SubStmtChanged)
     return S;
 
   return getDerived().RebuildCompoundStmt(S->getLBracLoc(),
                                           Statements,
                                           S->getRBracLoc(),
                                           IsStmtExpr);
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformCaseStmt(CaseStmt *S) {
   ExprResult LHS, RHS;
   {
     EnterExpressionEvaluationContext Unevaluated(
         SemaRef, Sema::ExpressionEvaluationContext::ConstantEvaluated);
 
     // Transform the left-hand case value.
     LHS = getDerived().TransformExpr(S->getLHS());
     LHS = SemaRef.ActOnCaseExpr(S->getCaseLoc(), LHS);
     if (LHS.isInvalid())
       return StmtError();
 
     // Transform the right-hand case value (for the GNU case-range extension).
     RHS = getDerived().TransformExpr(S->getRHS());
     RHS = SemaRef.ActOnCaseExpr(S->getCaseLoc(), RHS);
     if (RHS.isInvalid())
       return StmtError();
   }
 
   // Build the case statement.
   // Case statements are always rebuilt so that they will attached to their
   // transformed switch statement.
   StmtResult Case = getDerived().RebuildCaseStmt(S->getCaseLoc(),
                                                        LHS.get(),
                                                        S->getEllipsisLoc(),
                                                        RHS.get(),
                                                        S->getColonLoc());
   if (Case.isInvalid())
     return StmtError();
 
   // Transform the statement following the case
   StmtResult SubStmt =
       getDerived().TransformStmt(S->getSubStmt());
   if (SubStmt.isInvalid())
     return StmtError();
 
   // Attach the body to the case statement
   return getDerived().RebuildCaseStmtBody(Case.get(), SubStmt.get());
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformDefaultStmt(DefaultStmt *S) {
   // Transform the statement following the default case
   StmtResult SubStmt =
       getDerived().TransformStmt(S->getSubStmt());
   if (SubStmt.isInvalid())
     return StmtError();
 
   // Default statements are always rebuilt
   return getDerived().RebuildDefaultStmt(S->getDefaultLoc(), S->getColonLoc(),
                                          SubStmt.get());
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformLabelStmt(LabelStmt *S, StmtDiscardKind SDK) {
   StmtResult SubStmt = getDerived().TransformStmt(S->getSubStmt(), SDK);
   if (SubStmt.isInvalid())
     return StmtError();
 
   Decl *LD = getDerived().TransformDecl(S->getDecl()->getLocation(),
                                         S->getDecl());
   if (!LD)
     return StmtError();
 
   // If we're transforming "in-place" (we're not creating new local
   // declarations), assume we're replacing the old label statement
   // and clear out the reference to it.
   if (LD == S->getDecl())
     S->getDecl()->setStmt(nullptr);
 
   // FIXME: Pass the real colon location in.
   return getDerived().RebuildLabelStmt(S->getIdentLoc(),
                                        cast<LabelDecl>(LD), SourceLocation(),
                                        SubStmt.get());
 }
 
 template <typename Derived>
 const Attr *TreeTransform<Derived>::TransformAttr(const Attr *R) {
   if (!R)
     return R;
 
   switch (R->getKind()) {
 // Transform attributes by calling TransformXXXAttr.
 #define ATTR(X)                                                                \
   case attr::X:                                                                \
     return getDerived().Transform##X##Attr(cast<X##Attr>(R));
 #include "clang/Basic/AttrList.inc"
   }
   return R;
 }
 
 template <typename Derived>
 const Attr *TreeTransform<Derived>::TransformStmtAttr(const Stmt *OrigS,
                                                       const Stmt *InstS,
                                                       const Attr *R) {
   if (!R)
     return R;
 
   switch (R->getKind()) {
 // Transform attributes by calling TransformStmtXXXAttr.
 #define ATTR(X)                                                                \
   case attr::X:                                                                \
     return getDerived().TransformStmt##X##Attr(OrigS, InstS, cast<X##Attr>(R));
 #include "clang/Basic/AttrList.inc"
   }
   return TransformAttr(R);
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformAttributedStmt(AttributedStmt *S,
                                                 StmtDiscardKind SDK) {
   StmtResult SubStmt = getDerived().TransformStmt(S->getSubStmt(), SDK);
   if (SubStmt.isInvalid())
     return StmtError();
 
   bool AttrsChanged = false;
   SmallVector<const Attr *, 1> Attrs;
 
   // Visit attributes and keep track if any are transformed.
   for (const auto *I : S->getAttrs()) {
     const Attr *R =
         getDerived().TransformStmtAttr(S->getSubStmt(), SubStmt.get(), I);
     AttrsChanged |= (I != R);
     if (R)
       Attrs.push_back(R);
   }
 
   if (SubStmt.get() == S->getSubStmt() && !AttrsChanged)
     return S;
 
   // If transforming the attributes failed for all of the attributes in the
   // statement, don't make an AttributedStmt without attributes.
   if (Attrs.empty())
     return SubStmt;
 
   return getDerived().RebuildAttributedStmt(S->getAttrLoc(), Attrs,
                                             SubStmt.get());
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformIfStmt(IfStmt *S) {
   // Transform the initialization statement
   StmtResult Init = getDerived().TransformStmt(S->getInit());
   if (Init.isInvalid())
     return StmtError();
 
   Sema::ConditionResult Cond;
   if (!S->isConsteval()) {
     // Transform the condition
     Cond = getDerived().TransformCondition(
         S->getIfLoc(), S->getConditionVariable(), S->getCond(),
         S->isConstexpr() ? Sema::ConditionKind::ConstexprIf
                          : Sema::ConditionKind::Boolean);
     if (Cond.isInvalid())
       return StmtError();
   }
 
   // If this is a constexpr if, determine which arm we should instantiate.
   std::optional<bool> ConstexprConditionValue;
   if (S->isConstexpr())
     ConstexprConditionValue = Cond.getKnownValue();
 
   // Transform the "then" branch.
   StmtResult Then;
   if (!ConstexprConditionValue || *ConstexprConditionValue) {
     Then = getDerived().TransformStmt(S->getThen());
     if (Then.isInvalid())
       return StmtError();
   } else {
     Then = new (getSema().Context) NullStmt(S->getThen()->getBeginLoc());
   }
 
   // Transform the "else" branch.
   StmtResult Else;
   if (!ConstexprConditionValue || !*ConstexprConditionValue) {
     Else = getDerived().TransformStmt(S->getElse());
     if (Else.isInvalid())
       return StmtError();
   }
 
   if (!getDerived().AlwaysRebuild() &&
       Init.get() == S->getInit() &&
       Cond.get() == std::make_pair(S->getConditionVariable(), S->getCond()) &&
       Then.get() == S->getThen() &&
       Else.get() == S->getElse())
     return S;
 
   return getDerived().RebuildIfStmt(
       S->getIfLoc(), S->getStatementKind(), S->getLParenLoc(), Cond,
       S->getRParenLoc(), Init.get(), Then.get(), S->getElseLoc(), Else.get());
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformSwitchStmt(SwitchStmt *S) {
   // Transform the initialization statement
   StmtResult Init = getDerived().TransformStmt(S->getInit());
   if (Init.isInvalid())
     return StmtError();
 
   // Transform the condition.
   Sema::ConditionResult Cond = getDerived().TransformCondition(
       S->getSwitchLoc(), S->getConditionVariable(), S->getCond(),
       Sema::ConditionKind::Switch);
   if (Cond.isInvalid())
     return StmtError();
 
   // Rebuild the switch statement.
   StmtResult Switch =
       getDerived().RebuildSwitchStmtStart(S->getSwitchLoc(), S->getLParenLoc(),
                                           Init.get(), Cond, S->getRParenLoc());
   if (Switch.isInvalid())
     return StmtError();
 
   // Transform the body of the switch statement.
   StmtResult Body = getDerived().TransformStmt(S->getBody());
   if (Body.isInvalid())
     return StmtError();
 
   // Complete the switch statement.
   return getDerived().RebuildSwitchStmtBody(S->getSwitchLoc(), Switch.get(),
                                             Body.get());
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformWhileStmt(WhileStmt *S) {
   // Transform the condition
   Sema::ConditionResult Cond = getDerived().TransformCondition(
       S->getWhileLoc(), S->getConditionVariable(), S->getCond(),
       Sema::ConditionKind::Boolean);
   if (Cond.isInvalid())
     return StmtError();
 
   // Transform the body
   StmtResult Body = getDerived().TransformStmt(S->getBody());
   if (Body.isInvalid())
     return StmtError();
 
   if (!getDerived().AlwaysRebuild() &&
       Cond.get() == std::make_pair(S->getConditionVariable(), S->getCond()) &&
       Body.get() == S->getBody())
     return Owned(S);
 
   return getDerived().RebuildWhileStmt(S->getWhileLoc(), S->getLParenLoc(),
                                        Cond, S->getRParenLoc(), Body.get());
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformDoStmt(DoStmt *S) {
   // Transform the body
   StmtResult Body = getDerived().TransformStmt(S->getBody());
   if (Body.isInvalid())
     return StmtError();
 
   // Transform the condition
   ExprResult Cond = getDerived().TransformExpr(S->getCond());
   if (Cond.isInvalid())
     return StmtError();
 
   if (!getDerived().AlwaysRebuild() &&
       Cond.get() == S->getCond() &&
       Body.get() == S->getBody())
     return S;
 
   return getDerived().RebuildDoStmt(S->getDoLoc(), Body.get(), S->getWhileLoc(),
                                     /*FIXME:*/S->getWhileLoc(), Cond.get(),
                                     S->getRParenLoc());
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformForStmt(ForStmt *S) {
   if (getSema().getLangOpts().OpenMP)
     getSema().startOpenMPLoop();
 
   // Transform the initialization statement
   StmtResult Init = getDerived().TransformStmt(S->getInit());
   if (Init.isInvalid())
     return StmtError();
 
   // In OpenMP loop region loop control variable must be captured and be
   // private. Perform analysis of first part (if any).
   if (getSema().getLangOpts().OpenMP && Init.isUsable())
     getSema().ActOnOpenMPLoopInitialization(S->getForLoc(), Init.get());
 
   // Transform the condition
   Sema::ConditionResult Cond = getDerived().TransformCondition(
       S->getForLoc(), S->getConditionVariable(), S->getCond(),
       Sema::ConditionKind::Boolean);
   if (Cond.isInvalid())
     return StmtError();
 
   // Transform the increment
   ExprResult Inc = getDerived().TransformExpr(S->getInc());
   if (Inc.isInvalid())
     return StmtError();
 
   Sema::FullExprArg FullInc(getSema().MakeFullDiscardedValueExpr(Inc.get()));
   if (S->getInc() && !FullInc.get())
     return StmtError();
 
   // Transform the body
   StmtResult Body = getDerived().TransformStmt(S->getBody());
   if (Body.isInvalid())
     return StmtError();
 
   if (!getDerived().AlwaysRebuild() &&
       Init.get() == S->getInit() &&
       Cond.get() == std::make_pair(S->getConditionVariable(), S->getCond()) &&
       Inc.get() == S->getInc() &&
       Body.get() == S->getBody())
     return S;
 
   return getDerived().RebuildForStmt(S->getForLoc(), S->getLParenLoc(),
                                      Init.get(), Cond, FullInc,
                                      S->getRParenLoc(), Body.get());
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformGotoStmt(GotoStmt *S) {
   Decl *LD = getDerived().TransformDecl(S->getLabel()->getLocation(),
                                         S->getLabel());
   if (!LD)
     return StmtError();
 
   // Goto statements must always be rebuilt, to resolve the label.
   return getDerived().RebuildGotoStmt(S->getGotoLoc(), S->getLabelLoc(),
                                       cast<LabelDecl>(LD));
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformIndirectGotoStmt(IndirectGotoStmt *S) {
   ExprResult Target = getDerived().TransformExpr(S->getTarget());
   if (Target.isInvalid())
     return StmtError();
   Target = SemaRef.MaybeCreateExprWithCleanups(Target.get());
 
   if (!getDerived().AlwaysRebuild() &&
       Target.get() == S->getTarget())
     return S;
 
   return getDerived().RebuildIndirectGotoStmt(S->getGotoLoc(), S->getStarLoc(),
                                               Target.get());
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformContinueStmt(ContinueStmt *S) {
   return S;
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformBreakStmt(BreakStmt *S) {
   return S;
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformReturnStmt(ReturnStmt *S) {
   ExprResult Result = getDerived().TransformInitializer(S->getRetValue(),
                                                         /*NotCopyInit*/false);
   if (Result.isInvalid())
     return StmtError();
 
   // FIXME: We always rebuild the return statement because there is no way
   // to tell whether the return type of the function has changed.
   return getDerived().RebuildReturnStmt(S->getReturnLoc(), Result.get());
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformDeclStmt(DeclStmt *S) {
   bool DeclChanged = false;
   SmallVector<Decl *, 4> Decls;
   for (auto *D : S->decls()) {
     Decl *Transformed = getDerived().TransformDefinition(D->getLocation(), D);
     if (!Transformed)
       return StmtError();
 
     if (Transformed != D)
       DeclChanged = true;
 
     Decls.push_back(Transformed);
   }
 
   if (!getDerived().AlwaysRebuild() && !DeclChanged)
     return S;
 
   return getDerived().RebuildDeclStmt(Decls, S->getBeginLoc(), S->getEndLoc());
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformGCCAsmStmt(GCCAsmStmt *S) {
 
   SmallVector<Expr*, 8> Constraints;
   SmallVector<Expr*, 8> Exprs;
   SmallVector<IdentifierInfo *, 4> Names;
 
   ExprResult AsmString;
   SmallVector<Expr*, 8> Clobbers;
 
   bool ExprsChanged = false;
 
   // Go through the outputs.
   for (unsigned I = 0, E = S->getNumOutputs(); I != E; ++I) {
     Names.push_back(S->getOutputIdentifier(I));
 
     // No need to transform the constraint literal.
     Constraints.push_back(S->getOutputConstraintLiteral(I));
 
     // Transform the output expr.
     Expr *OutputExpr = S->getOutputExpr(I);
     ExprResult Result = getDerived().TransformExpr(OutputExpr);
     if (Result.isInvalid())
       return StmtError();
 
     ExprsChanged |= Result.get() != OutputExpr;
 
     Exprs.push_back(Result.get());
   }
 
   // Go through the inputs.
   for (unsigned I = 0, E = S->getNumInputs(); I != E; ++I) {
     Names.push_back(S->getInputIdentifier(I));
 
     // No need to transform the constraint literal.
     Constraints.push_back(S->getInputConstraintLiteral(I));
 
     // Transform the input expr.
     Expr *InputExpr = S->getInputExpr(I);
     ExprResult Result = getDerived().TransformExpr(InputExpr);
     if (Result.isInvalid())
       return StmtError();
 
     ExprsChanged |= Result.get() != InputExpr;
 
     Exprs.push_back(Result.get());
   }
 
   // Go through the Labels.
   for (unsigned I = 0, E = S->getNumLabels(); I != E; ++I) {
     Names.push_back(S->getLabelIdentifier(I));
 
     ExprResult Result = getDerived().TransformExpr(S->getLabelExpr(I));
     if (Result.isInvalid())
       return StmtError();
     ExprsChanged |= Result.get() != S->getLabelExpr(I);
     Exprs.push_back(Result.get());
   }
   if (!getDerived().AlwaysRebuild() && !ExprsChanged)
     return S;
 
   // Go through the clobbers.
   for (unsigned I = 0, E = S->getNumClobbers(); I != E; ++I)
     Clobbers.push_back(S->getClobberStringLiteral(I));
 
   // No need to transform the asm string literal.
   AsmString = S->getAsmString();
   return getDerived().RebuildGCCAsmStmt(S->getAsmLoc(), S->isSimple(),
                                         S->isVolatile(), S->getNumOutputs(),
                                         S->getNumInputs(), Names.data(),
                                         Constraints, Exprs, AsmString.get(),
                                         Clobbers, S->getNumLabels(),
                                         S->getRParenLoc());
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformMSAsmStmt(MSAsmStmt *S) {
   ArrayRef<Token> AsmToks = llvm::ArrayRef(S->getAsmToks(), S->getNumAsmToks());
 
   bool HadError = false, HadChange = false;
 
   ArrayRef<Expr*> SrcExprs = S->getAllExprs();
   SmallVector<Expr*, 8> TransformedExprs;
   TransformedExprs.reserve(SrcExprs.size());
   for (unsigned i = 0, e = SrcExprs.size(); i != e; ++i) {
     ExprResult Result = getDerived().TransformExpr(SrcExprs[i]);
     if (!Result.isUsable()) {
       HadError = true;
     } else {
       HadChange |= (Result.get() != SrcExprs[i]);
       TransformedExprs.push_back(Result.get());
     }
   }
 
   if (HadError) return StmtError();
   if (!HadChange && !getDerived().AlwaysRebuild())
     return Owned(S);
 
   return getDerived().RebuildMSAsmStmt(S->getAsmLoc(), S->getLBraceLoc(),
                                        AsmToks, S->getAsmString(),
                                        S->getNumOutputs(), S->getNumInputs(),
                                        S->getAllConstraints(), S->getClobbers(),
                                        TransformedExprs, S->getEndLoc());
 }
 
 // C++ Coroutines
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformCoroutineBodyStmt(CoroutineBodyStmt *S) {
   auto *ScopeInfo = SemaRef.getCurFunction();
   auto *FD = cast<FunctionDecl>(SemaRef.CurContext);
   assert(FD && ScopeInfo && !ScopeInfo->CoroutinePromise &&
          ScopeInfo->NeedsCoroutineSuspends &&
          ScopeInfo->CoroutineSuspends.first == nullptr &&
          ScopeInfo->CoroutineSuspends.second == nullptr &&
          "expected clean scope info");
 
   // Set that we have (possibly-invalid) suspend points before we do anything
   // that may fail.
   ScopeInfo->setNeedsCoroutineSuspends(false);
 
   // We re-build the coroutine promise object (and the coroutine parameters its
   // type and constructor depend on) based on the types used in our current
   // function. We must do so, and set it on the current FunctionScopeInfo,
   // before attempting to transform the other parts of the coroutine body
   // statement, such as the implicit suspend statements (because those
   // statements reference the FunctionScopeInfo::CoroutinePromise).
   if (!SemaRef.buildCoroutineParameterMoves(FD->getLocation()))
     return StmtError();
   auto *Promise = SemaRef.buildCoroutinePromise(FD->getLocation());
   if (!Promise)
     return StmtError();
   getDerived().transformedLocalDecl(S->getPromiseDecl(), {Promise});
   ScopeInfo->CoroutinePromise = Promise;
 
   // Transform the implicit coroutine statements constructed using dependent
   // types during the previous parse: initial and final suspensions, the return
   // object, and others. We also transform the coroutine function's body.
   StmtResult InitSuspend = getDerived().TransformStmt(S->getInitSuspendStmt());
   if (InitSuspend.isInvalid())
     return StmtError();
   StmtResult FinalSuspend =
       getDerived().TransformStmt(S->getFinalSuspendStmt());
   if (FinalSuspend.isInvalid() ||
       !SemaRef.checkFinalSuspendNoThrow(FinalSuspend.get()))
     return StmtError();
   ScopeInfo->setCoroutineSuspends(InitSuspend.get(), FinalSuspend.get());
   assert(isa<Expr>(InitSuspend.get()) && isa<Expr>(FinalSuspend.get()));
 
   StmtResult BodyRes = getDerived().TransformStmt(S->getBody());
   if (BodyRes.isInvalid())
     return StmtError();
 
   CoroutineStmtBuilder Builder(SemaRef, *FD, *ScopeInfo, BodyRes.get());
   if (Builder.isInvalid())
     return StmtError();
 
   Expr *ReturnObject = S->getReturnValueInit();
   assert(ReturnObject && "the return object is expected to be valid");
   ExprResult Res = getDerived().TransformInitializer(ReturnObject,
                                                      /*NoCopyInit*/ false);
   if (Res.isInvalid())
     return StmtError();
   Builder.ReturnValue = Res.get();
 
   // If during the previous parse the coroutine still had a dependent promise
   // statement, we may need to build some implicit coroutine statements
   // (such as exception and fallthrough handlers) for the first time.
   if (S->hasDependentPromiseType()) {
     // We can only build these statements, however, if the current promise type
     // is not dependent.
     if (!Promise->getType()->isDependentType()) {
       assert(!S->getFallthroughHandler() && !S->getExceptionHandler() &&
              !S->getReturnStmtOnAllocFailure() && !S->getDeallocate() &&
              "these nodes should not have been built yet");
       if (!Builder.buildDependentStatements())
         return StmtError();
     }
   } else {
     if (auto *OnFallthrough = S->getFallthroughHandler()) {
       StmtResult Res = getDerived().TransformStmt(OnFallthrough);
       if (Res.isInvalid())
         return StmtError();
       Builder.OnFallthrough = Res.get();
     }
 
     if (auto *OnException = S->getExceptionHandler()) {
       StmtResult Res = getDerived().TransformStmt(OnException);
       if (Res.isInvalid())
         return StmtError();
       Builder.OnException = Res.get();
     }
 
     if (auto *OnAllocFailure = S->getReturnStmtOnAllocFailure()) {
       StmtResult Res = getDerived().TransformStmt(OnAllocFailure);
       if (Res.isInvalid())
         return StmtError();
       Builder.ReturnStmtOnAllocFailure = Res.get();
     }
 
     // Transform any additional statements we may have already built
     assert(S->getAllocate() && S->getDeallocate() &&
            "allocation and deallocation calls must already be built");
     ExprResult AllocRes = getDerived().TransformExpr(S->getAllocate());
     if (AllocRes.isInvalid())
       return StmtError();
     Builder.Allocate = AllocRes.get();
 
     ExprResult DeallocRes = getDerived().TransformExpr(S->getDeallocate());
     if (DeallocRes.isInvalid())
       return StmtError();
     Builder.Deallocate = DeallocRes.get();
 
     if (auto *ResultDecl = S->getResultDecl()) {
       StmtResult Res = getDerived().TransformStmt(ResultDecl);
       if (Res.isInvalid())
         return StmtError();
       Builder.ResultDecl = Res.get();
     }
 
     if (auto *ReturnStmt = S->getReturnStmt()) {
       StmtResult Res = getDerived().TransformStmt(ReturnStmt);
       if (Res.isInvalid())
         return StmtError();
       Builder.ReturnStmt = Res.get();
     }
   }
 
   return getDerived().RebuildCoroutineBodyStmt(Builder);
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformCoreturnStmt(CoreturnStmt *S) {
   ExprResult Result = getDerived().TransformInitializer(S->getOperand(),
                                                         /*NotCopyInit*/false);
   if (Result.isInvalid())
     return StmtError();
 
   // Always rebuild; we don't know if this needs to be injected into a new
   // context or if the promise type has changed.
   return getDerived().RebuildCoreturnStmt(S->getKeywordLoc(), Result.get(),
                                           S->isImplicit());
 }
 
 template <typename Derived>
 ExprResult TreeTransform<Derived>::TransformCoawaitExpr(CoawaitExpr *E) {
   ExprResult Operand = getDerived().TransformInitializer(E->getOperand(),
                                                          /*NotCopyInit*/ false);
   if (Operand.isInvalid())
     return ExprError();
 
   // Rebuild the common-expr from the operand rather than transforming it
   // separately.
 
   // FIXME: getCurScope() should not be used during template instantiation.
   // We should pick up the set of unqualified lookup results for operator
   // co_await during the initial parse.
   ExprResult Lookup = getSema().BuildOperatorCoawaitLookupExpr(
       getSema().getCurScope(), E->getKeywordLoc());
 
   // Always rebuild; we don't know if this needs to be injected into a new
   // context or if the promise type has changed.
   return getDerived().RebuildCoawaitExpr(
       E->getKeywordLoc(), Operand.get(),
       cast<UnresolvedLookupExpr>(Lookup.get()), E->isImplicit());
 }
 
 template <typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformDependentCoawaitExpr(DependentCoawaitExpr *E) {
   ExprResult OperandResult = getDerived().TransformInitializer(E->getOperand(),
                                                         /*NotCopyInit*/ false);
   if (OperandResult.isInvalid())
     return ExprError();
 
   ExprResult LookupResult = getDerived().TransformUnresolvedLookupExpr(
           E->getOperatorCoawaitLookup());
 
   if (LookupResult.isInvalid())
     return ExprError();
 
   // Always rebuild; we don't know if this needs to be injected into a new
   // context or if the promise type has changed.
   return getDerived().RebuildDependentCoawaitExpr(
       E->getKeywordLoc(), OperandResult.get(),
       cast<UnresolvedLookupExpr>(LookupResult.get()));
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCoyieldExpr(CoyieldExpr *E) {
   ExprResult Result = getDerived().TransformInitializer(E->getOperand(),
                                                         /*NotCopyInit*/false);
   if (Result.isInvalid())
     return ExprError();
 
   // Always rebuild; we don't know if this needs to be injected into a new
   // context or if the promise type has changed.
   return getDerived().RebuildCoyieldExpr(E->getKeywordLoc(), Result.get());
 }
 
 // Objective-C Statements.
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformObjCAtTryStmt(ObjCAtTryStmt *S) {
   // Transform the body of the @try.
   StmtResult TryBody = getDerived().TransformStmt(S->getTryBody());
   if (TryBody.isInvalid())
     return StmtError();
 
   // Transform the @catch statements (if present).
   bool AnyCatchChanged = false;
   SmallVector<Stmt*, 8> CatchStmts;
   for (unsigned I = 0, N = S->getNumCatchStmts(); I != N; ++I) {
     StmtResult Catch = getDerived().TransformStmt(S->getCatchStmt(I));
     if (Catch.isInvalid())
       return StmtError();
     if (Catch.get() != S->getCatchStmt(I))
       AnyCatchChanged = true;
     CatchStmts.push_back(Catch.get());
   }
 
   // Transform the @finally statement (if present).
   StmtResult Finally;
   if (S->getFinallyStmt()) {
     Finally = getDerived().TransformStmt(S->getFinallyStmt());
     if (Finally.isInvalid())
       return StmtError();
   }
 
   // If nothing changed, just retain this statement.
   if (!getDerived().AlwaysRebuild() &&
       TryBody.get() == S->getTryBody() &&
       !AnyCatchChanged &&
       Finally.get() == S->getFinallyStmt())
     return S;
 
   // Build a new statement.
   return getDerived().RebuildObjCAtTryStmt(S->getAtTryLoc(), TryBody.get(),
                                            CatchStmts, Finally.get());
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformObjCAtCatchStmt(ObjCAtCatchStmt *S) {
   // Transform the @catch parameter, if there is one.
   VarDecl *Var = nullptr;
   if (VarDecl *FromVar = S->getCatchParamDecl()) {
     TypeSourceInfo *TSInfo = nullptr;
     if (FromVar->getTypeSourceInfo()) {
       TSInfo = getDerived().TransformType(FromVar->getTypeSourceInfo());
       if (!TSInfo)
         return StmtError();
     }
 
     QualType T;
     if (TSInfo)
       T = TSInfo->getType();
     else {
       T = getDerived().TransformType(FromVar->getType());
       if (T.isNull())
         return StmtError();
     }
 
     Var = getDerived().RebuildObjCExceptionDecl(FromVar, TSInfo, T);
     if (!Var)
       return StmtError();
   }
 
   StmtResult Body = getDerived().TransformStmt(S->getCatchBody());
   if (Body.isInvalid())
     return StmtError();
 
   return getDerived().RebuildObjCAtCatchStmt(S->getAtCatchLoc(),
                                              S->getRParenLoc(),
                                              Var, Body.get());
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformObjCAtFinallyStmt(ObjCAtFinallyStmt *S) {
   // Transform the body.
   StmtResult Body = getDerived().TransformStmt(S->getFinallyBody());
   if (Body.isInvalid())
     return StmtError();
 
   // If nothing changed, just retain this statement.
   if (!getDerived().AlwaysRebuild() &&
       Body.get() == S->getFinallyBody())
     return S;
 
   // Build a new statement.
   return getDerived().RebuildObjCAtFinallyStmt(S->getAtFinallyLoc(),
                                                Body.get());
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformObjCAtThrowStmt(ObjCAtThrowStmt *S) {
   ExprResult Operand;
   if (S->getThrowExpr()) {
     Operand = getDerived().TransformExpr(S->getThrowExpr());
     if (Operand.isInvalid())
       return StmtError();
   }
 
   if (!getDerived().AlwaysRebuild() &&
       Operand.get() == S->getThrowExpr())
     return S;
 
   return getDerived().RebuildObjCAtThrowStmt(S->getThrowLoc(), Operand.get());
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformObjCAtSynchronizedStmt(
                                                   ObjCAtSynchronizedStmt *S) {
   // Transform the object we are locking.
   ExprResult Object = getDerived().TransformExpr(S->getSynchExpr());
   if (Object.isInvalid())
     return StmtError();
   Object =
     getDerived().RebuildObjCAtSynchronizedOperand(S->getAtSynchronizedLoc(),
                                                   Object.get());
   if (Object.isInvalid())
     return StmtError();
 
   // Transform the body.
   StmtResult Body = getDerived().TransformStmt(S->getSynchBody());
   if (Body.isInvalid())
     return StmtError();
 
   // If nothing change, just retain the current statement.
   if (!getDerived().AlwaysRebuild() &&
       Object.get() == S->getSynchExpr() &&
       Body.get() == S->getSynchBody())
     return S;
 
   // Build a new statement.
   return getDerived().RebuildObjCAtSynchronizedStmt(S->getAtSynchronizedLoc(),
                                                     Object.get(), Body.get());
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformObjCAutoreleasePoolStmt(
                                               ObjCAutoreleasePoolStmt *S) {
   // Transform the body.
   StmtResult Body = getDerived().TransformStmt(S->getSubStmt());
   if (Body.isInvalid())
     return StmtError();
 
   // If nothing changed, just retain this statement.
   if (!getDerived().AlwaysRebuild() &&
       Body.get() == S->getSubStmt())
     return S;
 
   // Build a new statement.
   return getDerived().RebuildObjCAutoreleasePoolStmt(
                         S->getAtLoc(), Body.get());
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformObjCForCollectionStmt(
                                                   ObjCForCollectionStmt *S) {
   // Transform the element statement.
   StmtResult Element =
       getDerived().TransformStmt(S->getElement(), SDK_NotDiscarded);
   if (Element.isInvalid())
     return StmtError();
 
   // Transform the collection expression.
   ExprResult Collection = getDerived().TransformExpr(S->getCollection());
   if (Collection.isInvalid())
     return StmtError();
 
   // Transform the body.
   StmtResult Body = getDerived().TransformStmt(S->getBody());
   if (Body.isInvalid())
     return StmtError();
 
   // If nothing changed, just retain this statement.
   if (!getDerived().AlwaysRebuild() &&
       Element.get() == S->getElement() &&
       Collection.get() == S->getCollection() &&
       Body.get() == S->getBody())
     return S;
 
   // Build a new statement.
   return getDerived().RebuildObjCForCollectionStmt(S->getForLoc(),
                                                    Element.get(),
                                                    Collection.get(),
                                                    S->getRParenLoc(),
                                                    Body.get());
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformCXXCatchStmt(CXXCatchStmt *S) {
   // Transform the exception declaration, if any.
   VarDecl *Var = nullptr;
   if (VarDecl *ExceptionDecl = S->getExceptionDecl()) {
     TypeSourceInfo *T =
         getDerived().TransformType(ExceptionDecl->getTypeSourceInfo());
     if (!T)
       return StmtError();
 
     Var = getDerived().RebuildExceptionDecl(
         ExceptionDecl, T, ExceptionDecl->getInnerLocStart(),
         ExceptionDecl->getLocation(), ExceptionDecl->getIdentifier());
     if (!Var || Var->isInvalidDecl())
       return StmtError();
   }
 
   // Transform the actual exception handler.
   StmtResult Handler = getDerived().TransformStmt(S->getHandlerBlock());
   if (Handler.isInvalid())
     return StmtError();
 
   if (!getDerived().AlwaysRebuild() && !Var &&
       Handler.get() == S->getHandlerBlock())
     return S;
 
   return getDerived().RebuildCXXCatchStmt(S->getCatchLoc(), Var, Handler.get());
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformCXXTryStmt(CXXTryStmt *S) {
   // Transform the try block itself.
   StmtResult TryBlock = getDerived().TransformCompoundStmt(S->getTryBlock());
   if (TryBlock.isInvalid())
     return StmtError();
 
   // Transform the handlers.
   bool HandlerChanged = false;
   SmallVector<Stmt *, 8> Handlers;
   for (unsigned I = 0, N = S->getNumHandlers(); I != N; ++I) {
     StmtResult Handler = getDerived().TransformCXXCatchStmt(S->getHandler(I));
     if (Handler.isInvalid())
       return StmtError();
 
     HandlerChanged = HandlerChanged || Handler.get() != S->getHandler(I);
     Handlers.push_back(Handler.getAs<Stmt>());
   }
 
   if (!getDerived().AlwaysRebuild() && TryBlock.get() == S->getTryBlock() &&
       !HandlerChanged)
     return S;
 
   return getDerived().RebuildCXXTryStmt(S->getTryLoc(), TryBlock.get(),
                                         Handlers);
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformCXXForRangeStmt(CXXForRangeStmt *S) {
   StmtResult Init =
       S->getInit() ? getDerived().TransformStmt(S->getInit()) : StmtResult();
   if (Init.isInvalid())
     return StmtError();
 
   StmtResult Range = getDerived().TransformStmt(S->getRangeStmt());
   if (Range.isInvalid())
     return StmtError();
 
   StmtResult Begin = getDerived().TransformStmt(S->getBeginStmt());
   if (Begin.isInvalid())
     return StmtError();
   StmtResult End = getDerived().TransformStmt(S->getEndStmt());
   if (End.isInvalid())
     return StmtError();
 
   ExprResult Cond = getDerived().TransformExpr(S->getCond());
   if (Cond.isInvalid())
     return StmtError();
   if (Cond.get())
     Cond = SemaRef.CheckBooleanCondition(S->getColonLoc(), Cond.get());
   if (Cond.isInvalid())
     return StmtError();
   if (Cond.get())
     Cond = SemaRef.MaybeCreateExprWithCleanups(Cond.get());
 
   ExprResult Inc = getDerived().TransformExpr(S->getInc());
   if (Inc.isInvalid())
     return StmtError();
   if (Inc.get())
     Inc = SemaRef.MaybeCreateExprWithCleanups(Inc.get());
 
   StmtResult LoopVar = getDerived().TransformStmt(S->getLoopVarStmt());
   if (LoopVar.isInvalid())
     return StmtError();
 
   StmtResult NewStmt = S;
   if (getDerived().AlwaysRebuild() ||
       Init.get() != S->getInit() ||
       Range.get() != S->getRangeStmt() ||
       Begin.get() != S->getBeginStmt() ||
       End.get() != S->getEndStmt() ||
       Cond.get() != S->getCond() ||
       Inc.get() != S->getInc() ||
       LoopVar.get() != S->getLoopVarStmt()) {
     NewStmt = getDerived().RebuildCXXForRangeStmt(S->getForLoc(),
                                                   S->getCoawaitLoc(), Init.get(),
                                                   S->getColonLoc(), Range.get(),
                                                   Begin.get(), End.get(),
                                                   Cond.get(),
                                                   Inc.get(), LoopVar.get(),
                                                   S->getRParenLoc());
     if (NewStmt.isInvalid() && LoopVar.get() != S->getLoopVarStmt()) {
       // Might not have attached any initializer to the loop variable.
       getSema().ActOnInitializerError(
           cast<DeclStmt>(LoopVar.get())->getSingleDecl());
       return StmtError();
     }
   }
 
   StmtResult Body = getDerived().TransformStmt(S->getBody());
   if (Body.isInvalid())
     return StmtError();
 
   // Body has changed but we didn't rebuild the for-range statement. Rebuild
   // it now so we have a new statement to attach the body to.
   if (Body.get() != S->getBody() && NewStmt.get() == S) {
     NewStmt = getDerived().RebuildCXXForRangeStmt(S->getForLoc(),
                                                   S->getCoawaitLoc(), Init.get(),
                                                   S->getColonLoc(), Range.get(),
                                                   Begin.get(), End.get(),
                                                   Cond.get(),
                                                   Inc.get(), LoopVar.get(),
                                                   S->getRParenLoc());
     if (NewStmt.isInvalid())
       return StmtError();
   }
 
   if (NewStmt.get() == S)
     return S;
 
   return FinishCXXForRangeStmt(NewStmt.get(), Body.get());
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformMSDependentExistsStmt(
                                                     MSDependentExistsStmt *S) {
   // Transform the nested-name-specifier, if any.
   NestedNameSpecifierLoc QualifierLoc;
   if (S->getQualifierLoc()) {
     QualifierLoc
       = getDerived().TransformNestedNameSpecifierLoc(S->getQualifierLoc());
     if (!QualifierLoc)
       return StmtError();
   }
 
   // Transform the declaration name.
   DeclarationNameInfo NameInfo = S->getNameInfo();
   if (NameInfo.getName()) {
     NameInfo = getDerived().TransformDeclarationNameInfo(NameInfo);
     if (!NameInfo.getName())
       return StmtError();
   }
 
   // Check whether anything changed.
   if (!getDerived().AlwaysRebuild() &&
       QualifierLoc == S->getQualifierLoc() &&
       NameInfo.getName() == S->getNameInfo().getName())
     return S;
 
   // Determine whether this name exists, if we can.
   CXXScopeSpec SS;
   SS.Adopt(QualifierLoc);
   bool Dependent = false;
   switch (getSema().CheckMicrosoftIfExistsSymbol(/*S=*/nullptr, SS, NameInfo)) {
   case Sema::IER_Exists:
     if (S->isIfExists())
       break;
 
     return new (getSema().Context) NullStmt(S->getKeywordLoc());
 
   case Sema::IER_DoesNotExist:
     if (S->isIfNotExists())
       break;
 
     return new (getSema().Context) NullStmt(S->getKeywordLoc());
 
   case Sema::IER_Dependent:
     Dependent = true;
     break;
 
   case Sema::IER_Error:
     return StmtError();
   }
 
   // We need to continue with the instantiation, so do so now.
   StmtResult SubStmt = getDerived().TransformCompoundStmt(S->getSubStmt());
   if (SubStmt.isInvalid())
     return StmtError();
 
   // If we have resolved the name, just transform to the substatement.
   if (!Dependent)
     return SubStmt;
 
   // The name is still dependent, so build a dependent expression again.
   return getDerived().RebuildMSDependentExistsStmt(S->getKeywordLoc(),
                                                    S->isIfExists(),
                                                    QualifierLoc,
                                                    NameInfo,
                                                    SubStmt.get());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformMSPropertyRefExpr(MSPropertyRefExpr *E) {
   NestedNameSpecifierLoc QualifierLoc;
   if (E->getQualifierLoc()) {
     QualifierLoc
     = getDerived().TransformNestedNameSpecifierLoc(E->getQualifierLoc());
     if (!QualifierLoc)
       return ExprError();
   }
 
   MSPropertyDecl *PD = cast_or_null<MSPropertyDecl>(
     getDerived().TransformDecl(E->getMemberLoc(), E->getPropertyDecl()));
   if (!PD)
     return ExprError();
 
   ExprResult Base = getDerived().TransformExpr(E->getBaseExpr());
   if (Base.isInvalid())
     return ExprError();
 
   return new (SemaRef.getASTContext())
       MSPropertyRefExpr(Base.get(), PD, E->isArrow(),
                         SemaRef.getASTContext().PseudoObjectTy, VK_LValue,
                         QualifierLoc, E->getMemberLoc());
 }
 
 template <typename Derived>
 ExprResult TreeTransform<Derived>::TransformMSPropertySubscriptExpr(
     MSPropertySubscriptExpr *E) {
   auto BaseRes = getDerived().TransformExpr(E->getBase());
   if (BaseRes.isInvalid())
     return ExprError();
   auto IdxRes = getDerived().TransformExpr(E->getIdx());
   if (IdxRes.isInvalid())
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() &&
       BaseRes.get() == E->getBase() &&
       IdxRes.get() == E->getIdx())
     return E;
 
   return getDerived().RebuildArraySubscriptExpr(
       BaseRes.get(), SourceLocation(), IdxRes.get(), E->getRBracketLoc());
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformSEHTryStmt(SEHTryStmt *S) {
   StmtResult TryBlock = getDerived().TransformCompoundStmt(S->getTryBlock());
   if (TryBlock.isInvalid())
     return StmtError();
 
   StmtResult Handler = getDerived().TransformSEHHandler(S->getHandler());
   if (Handler.isInvalid())
     return StmtError();
 
   if (!getDerived().AlwaysRebuild() && TryBlock.get() == S->getTryBlock() &&
       Handler.get() == S->getHandler())
     return S;
 
   return getDerived().RebuildSEHTryStmt(S->getIsCXXTry(), S->getTryLoc(),
                                         TryBlock.get(), Handler.get());
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformSEHFinallyStmt(SEHFinallyStmt *S) {
   StmtResult Block = getDerived().TransformCompoundStmt(S->getBlock());
   if (Block.isInvalid())
     return StmtError();
 
   return getDerived().RebuildSEHFinallyStmt(S->getFinallyLoc(), Block.get());
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformSEHExceptStmt(SEHExceptStmt *S) {
   ExprResult FilterExpr = getDerived().TransformExpr(S->getFilterExpr());
   if (FilterExpr.isInvalid())
     return StmtError();
 
   StmtResult Block = getDerived().TransformCompoundStmt(S->getBlock());
   if (Block.isInvalid())
     return StmtError();
 
   return getDerived().RebuildSEHExceptStmt(S->getExceptLoc(), FilterExpr.get(),
                                            Block.get());
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformSEHHandler(Stmt *Handler) {
   if (isa<SEHFinallyStmt>(Handler))
     return getDerived().TransformSEHFinallyStmt(cast<SEHFinallyStmt>(Handler));
   else
     return getDerived().TransformSEHExceptStmt(cast<SEHExceptStmt>(Handler));
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformSEHLeaveStmt(SEHLeaveStmt *S) {
   return S;
 }
 
 //===----------------------------------------------------------------------===//
 // OpenMP directive transformation
 //===----------------------------------------------------------------------===//
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPCanonicalLoop(OMPCanonicalLoop *L) {
   // OMPCanonicalLoops are eliminated during transformation, since they will be
   // recomputed by semantic analysis of the associated OMPLoopBasedDirective
   // after transformation.
   return getDerived().TransformStmt(L->getLoopStmt());
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPExecutableDirective(
     OMPExecutableDirective *D) {
 
   // Transform the clauses
   llvm::SmallVector<OMPClause *, 16> TClauses;
   ArrayRef<OMPClause *> Clauses = D->clauses();
   TClauses.reserve(Clauses.size());
   for (ArrayRef<OMPClause *>::iterator I = Clauses.begin(), E = Clauses.end();
        I != E; ++I) {
     if (*I) {
       getDerived().getSema().StartOpenMPClause((*I)->getClauseKind());
       OMPClause *Clause = getDerived().TransformOMPClause(*I);
       getDerived().getSema().EndOpenMPClause();
       if (Clause)
         TClauses.push_back(Clause);
     } else {
       TClauses.push_back(nullptr);
     }
   }
   StmtResult AssociatedStmt;
   if (D->hasAssociatedStmt() && D->getAssociatedStmt()) {
     getDerived().getSema().ActOnOpenMPRegionStart(D->getDirectiveKind(),
                                                   /*CurScope=*/nullptr);
     StmtResult Body;
     {
       Sema::CompoundScopeRAII CompoundScope(getSema());
       Stmt *CS;
       if (D->getDirectiveKind() == OMPD_atomic ||
           D->getDirectiveKind() == OMPD_critical ||
           D->getDirectiveKind() == OMPD_section ||
           D->getDirectiveKind() == OMPD_master)
         CS = D->getAssociatedStmt();
       else
         CS = D->getRawStmt();
       Body = getDerived().TransformStmt(CS);
       if (Body.isUsable() && isOpenMPLoopDirective(D->getDirectiveKind()) &&
           getSema().getLangOpts().OpenMPIRBuilder)
         Body = getDerived().RebuildOMPCanonicalLoop(Body.get());
     }
     AssociatedStmt =
         getDerived().getSema().ActOnOpenMPRegionEnd(Body, TClauses);
     if (AssociatedStmt.isInvalid()) {
       return StmtError();
     }
   }
   if (TClauses.size() != Clauses.size()) {
     return StmtError();
   }
 
   // Transform directive name for 'omp critical' directive.
   DeclarationNameInfo DirName;
   if (D->getDirectiveKind() == OMPD_critical) {
     DirName = cast<OMPCriticalDirective>(D)->getDirectiveName();
     DirName = getDerived().TransformDeclarationNameInfo(DirName);
   }
   OpenMPDirectiveKind CancelRegion = OMPD_unknown;
   if (D->getDirectiveKind() == OMPD_cancellation_point) {
     CancelRegion = cast<OMPCancellationPointDirective>(D)->getCancelRegion();
   } else if (D->getDirectiveKind() == OMPD_cancel) {
     CancelRegion = cast<OMPCancelDirective>(D)->getCancelRegion();
   }
 
   return getDerived().RebuildOMPExecutableDirective(
       D->getDirectiveKind(), DirName, CancelRegion, TClauses,
       AssociatedStmt.get(), D->getBeginLoc(), D->getEndLoc());
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPMetaDirective(OMPMetaDirective *D) {
   // TODO: Fix This
   SemaRef.Diag(D->getBeginLoc(), diag::err_omp_instantiation_not_supported)
       << getOpenMPDirectiveName(D->getDirectiveKind());
   return StmtError();
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPParallelDirective(OMPParallelDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_parallel, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPSimdDirective(OMPSimdDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_simd, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPTileDirective(OMPTileDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(D->getDirectiveKind(), DirName,
                                              nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPUnrollDirective(OMPUnrollDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(D->getDirectiveKind(), DirName,
                                              nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPForDirective(OMPForDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_for, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPForSimdDirective(OMPForSimdDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_for_simd, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPSectionsDirective(OMPSectionsDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_sections, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPSectionDirective(OMPSectionDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_section, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPSingleDirective(OMPSingleDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_single, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPMasterDirective(OMPMasterDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_master, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPCriticalDirective(OMPCriticalDirective *D) {
   getDerived().getSema().StartOpenMPDSABlock(
       OMPD_critical, D->getDirectiveName(), nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPParallelForDirective(
     OMPParallelForDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_parallel_for, DirName,
                                              nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPParallelForSimdDirective(
     OMPParallelForSimdDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_parallel_for_simd, DirName,
                                              nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPParallelMasterDirective(
     OMPParallelMasterDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_parallel_master, DirName,
                                              nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPParallelMaskedDirective(
     OMPParallelMaskedDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_parallel_masked, DirName,
                                              nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPParallelSectionsDirective(
     OMPParallelSectionsDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_parallel_sections, DirName,
                                              nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPTaskDirective(OMPTaskDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_task, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPTaskyieldDirective(
     OMPTaskyieldDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_taskyield, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPBarrierDirective(OMPBarrierDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_barrier, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPTaskwaitDirective(OMPTaskwaitDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_taskwait, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPErrorDirective(OMPErrorDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_error, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPTaskgroupDirective(
     OMPTaskgroupDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_taskgroup, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPFlushDirective(OMPFlushDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_flush, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPDepobjDirective(OMPDepobjDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_depobj, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPScanDirective(OMPScanDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_scan, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPOrderedDirective(OMPOrderedDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_ordered, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPAtomicDirective(OMPAtomicDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_atomic, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPTargetDirective(OMPTargetDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_target, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPTargetDataDirective(
     OMPTargetDataDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_target_data, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPTargetEnterDataDirective(
     OMPTargetEnterDataDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_target_enter_data, DirName,
                                              nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPTargetExitDataDirective(
     OMPTargetExitDataDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_target_exit_data, DirName,
                                              nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPTargetParallelDirective(
     OMPTargetParallelDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_target_parallel, DirName,
                                              nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPTargetParallelForDirective(
     OMPTargetParallelForDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_target_parallel_for, DirName,
                                              nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPTargetUpdateDirective(
     OMPTargetUpdateDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_target_update, DirName,
                                              nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPTeamsDirective(OMPTeamsDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_teams, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPCancellationPointDirective(
     OMPCancellationPointDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_cancellation_point, DirName,
                                              nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPCancelDirective(OMPCancelDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_cancel, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPTaskLoopDirective(OMPTaskLoopDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_taskloop, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPTaskLoopSimdDirective(
     OMPTaskLoopSimdDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_taskloop_simd, DirName,
                                              nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPMasterTaskLoopDirective(
     OMPMasterTaskLoopDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_master_taskloop, DirName,
                                              nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPMaskedTaskLoopDirective(
     OMPMaskedTaskLoopDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_masked_taskloop, DirName,
                                              nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPMasterTaskLoopSimdDirective(
     OMPMasterTaskLoopSimdDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_master_taskloop_simd, DirName,
                                              nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPMaskedTaskLoopSimdDirective(
     OMPMaskedTaskLoopSimdDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_masked_taskloop_simd, DirName,
                                              nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPParallelMasterTaskLoopDirective(
     OMPParallelMasterTaskLoopDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(
       OMPD_parallel_master_taskloop, DirName, nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPParallelMaskedTaskLoopDirective(
     OMPParallelMaskedTaskLoopDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(
       OMPD_parallel_masked_taskloop, DirName, nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPParallelMasterTaskLoopSimdDirective(
     OMPParallelMasterTaskLoopSimdDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(
       OMPD_parallel_master_taskloop_simd, DirName, nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPParallelMaskedTaskLoopSimdDirective(
     OMPParallelMaskedTaskLoopSimdDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(
       OMPD_parallel_masked_taskloop_simd, DirName, nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPDistributeDirective(
     OMPDistributeDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_distribute, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPDistributeParallelForDirective(
     OMPDistributeParallelForDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(
       OMPD_distribute_parallel_for, DirName, nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPDistributeParallelForSimdDirective(
     OMPDistributeParallelForSimdDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(
       OMPD_distribute_parallel_for_simd, DirName, nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPDistributeSimdDirective(
     OMPDistributeSimdDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_distribute_simd, DirName,
                                              nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPTargetParallelForSimdDirective(
     OMPTargetParallelForSimdDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(
       OMPD_target_parallel_for_simd, DirName, nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPTargetSimdDirective(
     OMPTargetSimdDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_target_simd, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPTeamsDistributeDirective(
     OMPTeamsDistributeDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_teams_distribute, DirName,
                                              nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPTeamsDistributeSimdDirective(
     OMPTeamsDistributeSimdDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(
       OMPD_teams_distribute_simd, DirName, nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPTeamsDistributeParallelForSimdDirective(
     OMPTeamsDistributeParallelForSimdDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(
       OMPD_teams_distribute_parallel_for_simd, DirName, nullptr,
       D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPTeamsDistributeParallelForDirective(
     OMPTeamsDistributeParallelForDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(
       OMPD_teams_distribute_parallel_for, DirName, nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPTargetTeamsDirective(
     OMPTargetTeamsDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_target_teams, DirName,
                                              nullptr, D->getBeginLoc());
   auto Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPTargetTeamsDistributeDirective(
     OMPTargetTeamsDistributeDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(
       OMPD_target_teams_distribute, DirName, nullptr, D->getBeginLoc());
   auto Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPTargetTeamsDistributeParallelForDirective(
     OMPTargetTeamsDistributeParallelForDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(
       OMPD_target_teams_distribute_parallel_for, DirName, nullptr,
       D->getBeginLoc());
   auto Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::
     TransformOMPTargetTeamsDistributeParallelForSimdDirective(
         OMPTargetTeamsDistributeParallelForSimdDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(
       OMPD_target_teams_distribute_parallel_for_simd, DirName, nullptr,
       D->getBeginLoc());
   auto Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPTargetTeamsDistributeSimdDirective(
     OMPTargetTeamsDistributeSimdDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(
       OMPD_target_teams_distribute_simd, DirName, nullptr, D->getBeginLoc());
   auto Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPInteropDirective(OMPInteropDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_interop, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPDispatchDirective(OMPDispatchDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_dispatch, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPMaskedDirective(OMPMaskedDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_masked, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPGenericLoopDirective(
     OMPGenericLoopDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_loop, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPTeamsGenericLoopDirective(
     OMPTeamsGenericLoopDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_teams_loop, DirName, nullptr,
                                              D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPTargetTeamsGenericLoopDirective(
     OMPTargetTeamsGenericLoopDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_target_teams_loop, DirName,
                                              nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult TreeTransform<Derived>::TransformOMPParallelGenericLoopDirective(
     OMPParallelGenericLoopDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_parallel_loop, DirName,
                                              nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 template <typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformOMPTargetParallelGenericLoopDirective(
     OMPTargetParallelGenericLoopDirective *D) {
   DeclarationNameInfo DirName;
   getDerived().getSema().StartOpenMPDSABlock(OMPD_target_parallel_loop, DirName,
                                              nullptr, D->getBeginLoc());
   StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
   getDerived().getSema().EndOpenMPDSABlock(Res.get());
   return Res;
 }
 
 //===----------------------------------------------------------------------===//
 // OpenMP clause transformation
 //===----------------------------------------------------------------------===//
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPIfClause(OMPIfClause *C) {
   ExprResult Cond = getDerived().TransformExpr(C->getCondition());
   if (Cond.isInvalid())
     return nullptr;
   return getDerived().RebuildOMPIfClause(
       C->getNameModifier(), Cond.get(), C->getBeginLoc(), C->getLParenLoc(),
       C->getNameModifierLoc(), C->getColonLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPFinalClause(OMPFinalClause *C) {
   ExprResult Cond = getDerived().TransformExpr(C->getCondition());
   if (Cond.isInvalid())
     return nullptr;
   return getDerived().RebuildOMPFinalClause(Cond.get(), C->getBeginLoc(),
                                             C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPNumThreadsClause(OMPNumThreadsClause *C) {
   ExprResult NumThreads = getDerived().TransformExpr(C->getNumThreads());
   if (NumThreads.isInvalid())
     return nullptr;
   return getDerived().RebuildOMPNumThreadsClause(
       NumThreads.get(), C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPSafelenClause(OMPSafelenClause *C) {
   ExprResult E = getDerived().TransformExpr(C->getSafelen());
   if (E.isInvalid())
     return nullptr;
   return getDerived().RebuildOMPSafelenClause(
       E.get(), C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPAllocatorClause(OMPAllocatorClause *C) {
   ExprResult E = getDerived().TransformExpr(C->getAllocator());
   if (E.isInvalid())
     return nullptr;
   return getDerived().RebuildOMPAllocatorClause(
       E.get(), C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPSimdlenClause(OMPSimdlenClause *C) {
   ExprResult E = getDerived().TransformExpr(C->getSimdlen());
   if (E.isInvalid())
     return nullptr;
   return getDerived().RebuildOMPSimdlenClause(
       E.get(), C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPSizesClause(OMPSizesClause *C) {
   SmallVector<Expr *, 4> TransformedSizes;
   TransformedSizes.reserve(C->getNumSizes());
   bool Changed = false;
   for (Expr *E : C->getSizesRefs()) {
     if (!E) {
       TransformedSizes.push_back(nullptr);
       continue;
     }
 
     ExprResult T = getDerived().TransformExpr(E);
     if (T.isInvalid())
       return nullptr;
     if (E != T.get())
       Changed = true;
     TransformedSizes.push_back(T.get());
   }
 
   if (!Changed && !getDerived().AlwaysRebuild())
     return C;
   return RebuildOMPSizesClause(TransformedSizes, C->getBeginLoc(),
                                C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPFullClause(OMPFullClause *C) {
   if (!getDerived().AlwaysRebuild())
     return C;
   return RebuildOMPFullClause(C->getBeginLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPPartialClause(OMPPartialClause *C) {
   ExprResult T = getDerived().TransformExpr(C->getFactor());
   if (T.isInvalid())
     return nullptr;
   Expr *Factor = T.get();
   bool Changed = Factor != C->getFactor();
 
   if (!Changed && !getDerived().AlwaysRebuild())
     return C;
   return RebuildOMPPartialClause(Factor, C->getBeginLoc(), C->getLParenLoc(),
                                  C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPCollapseClause(OMPCollapseClause *C) {
   ExprResult E = getDerived().TransformExpr(C->getNumForLoops());
   if (E.isInvalid())
     return nullptr;
   return getDerived().RebuildOMPCollapseClause(
       E.get(), C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPDefaultClause(OMPDefaultClause *C) {
   return getDerived().RebuildOMPDefaultClause(
       C->getDefaultKind(), C->getDefaultKindKwLoc(), C->getBeginLoc(),
       C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPProcBindClause(OMPProcBindClause *C) {
   return getDerived().RebuildOMPProcBindClause(
       C->getProcBindKind(), C->getProcBindKindKwLoc(), C->getBeginLoc(),
       C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPScheduleClause(OMPScheduleClause *C) {
   ExprResult E = getDerived().TransformExpr(C->getChunkSize());
   if (E.isInvalid())
     return nullptr;
   return getDerived().RebuildOMPScheduleClause(
       C->getFirstScheduleModifier(), C->getSecondScheduleModifier(),
       C->getScheduleKind(), E.get(), C->getBeginLoc(), C->getLParenLoc(),
       C->getFirstScheduleModifierLoc(), C->getSecondScheduleModifierLoc(),
       C->getScheduleKindLoc(), C->getCommaLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPOrderedClause(OMPOrderedClause *C) {
   ExprResult E;
   if (auto *Num = C->getNumForLoops()) {
     E = getDerived().TransformExpr(Num);
     if (E.isInvalid())
       return nullptr;
   }
   return getDerived().RebuildOMPOrderedClause(C->getBeginLoc(), C->getEndLoc(),
                                               C->getLParenLoc(), E.get());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPDetachClause(OMPDetachClause *C) {
   ExprResult E;
   if (Expr *Evt = C->getEventHandler()) {
     E = getDerived().TransformExpr(Evt);
     if (E.isInvalid())
       return nullptr;
   }
   return getDerived().RebuildOMPDetachClause(E.get(), C->getBeginLoc(),
                                              C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPNowaitClause(OMPNowaitClause *C) {
   // No need to rebuild this clause, no template-dependent parameters.
   return C;
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPUntiedClause(OMPUntiedClause *C) {
   // No need to rebuild this clause, no template-dependent parameters.
   return C;
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPMergeableClause(OMPMergeableClause *C) {
   // No need to rebuild this clause, no template-dependent parameters.
   return C;
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPReadClause(OMPReadClause *C) {
   // No need to rebuild this clause, no template-dependent parameters.
   return C;
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPWriteClause(OMPWriteClause *C) {
   // No need to rebuild this clause, no template-dependent parameters.
   return C;
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPUpdateClause(OMPUpdateClause *C) {
   // No need to rebuild this clause, no template-dependent parameters.
   return C;
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPCaptureClause(OMPCaptureClause *C) {
   // No need to rebuild this clause, no template-dependent parameters.
   return C;
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPCompareClause(OMPCompareClause *C) {
   // No need to rebuild this clause, no template-dependent parameters.
   return C;
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPSeqCstClause(OMPSeqCstClause *C) {
   // No need to rebuild this clause, no template-dependent parameters.
   return C;
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPAcqRelClause(OMPAcqRelClause *C) {
   // No need to rebuild this clause, no template-dependent parameters.
   return C;
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPAcquireClause(OMPAcquireClause *C) {
   // No need to rebuild this clause, no template-dependent parameters.
   return C;
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPReleaseClause(OMPReleaseClause *C) {
   // No need to rebuild this clause, no template-dependent parameters.
   return C;
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPRelaxedClause(OMPRelaxedClause *C) {
   // No need to rebuild this clause, no template-dependent parameters.
   return C;
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPThreadsClause(OMPThreadsClause *C) {
   // No need to rebuild this clause, no template-dependent parameters.
   return C;
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPSIMDClause(OMPSIMDClause *C) {
   // No need to rebuild this clause, no template-dependent parameters.
   return C;
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPNogroupClause(OMPNogroupClause *C) {
   // No need to rebuild this clause, no template-dependent parameters.
   return C;
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPInitClause(OMPInitClause *C) {
   ExprResult IVR = getDerived().TransformExpr(C->getInteropVar());
   if (IVR.isInvalid())
     return nullptr;
 
   OMPInteropInfo InteropInfo(C->getIsTarget(), C->getIsTargetSync());
   InteropInfo.PreferTypes.reserve(C->varlist_size() - 1);
   for (Expr *E : llvm::drop_begin(C->varlists())) {
     ExprResult ER = getDerived().TransformExpr(cast<Expr>(E));
     if (ER.isInvalid())
       return nullptr;
     InteropInfo.PreferTypes.push_back(ER.get());
   }
   return getDerived().RebuildOMPInitClause(IVR.get(), InteropInfo,
                                            C->getBeginLoc(), C->getLParenLoc(),
                                            C->getVarLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPUseClause(OMPUseClause *C) {
   ExprResult ER = getDerived().TransformExpr(C->getInteropVar());
   if (ER.isInvalid())
     return nullptr;
   return getDerived().RebuildOMPUseClause(ER.get(), C->getBeginLoc(),
                                           C->getLParenLoc(), C->getVarLoc(),
                                           C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPDestroyClause(OMPDestroyClause *C) {
   ExprResult ER;
   if (Expr *IV = C->getInteropVar()) {
     ER = getDerived().TransformExpr(IV);
     if (ER.isInvalid())
       return nullptr;
   }
   return getDerived().RebuildOMPDestroyClause(ER.get(), C->getBeginLoc(),
                                               C->getLParenLoc(), C->getVarLoc(),
                                               C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPNovariantsClause(OMPNovariantsClause *C) {
   ExprResult Cond = getDerived().TransformExpr(C->getCondition());
   if (Cond.isInvalid())
     return nullptr;
   return getDerived().RebuildOMPNovariantsClause(
       Cond.get(), C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPNocontextClause(OMPNocontextClause *C) {
   ExprResult Cond = getDerived().TransformExpr(C->getCondition());
   if (Cond.isInvalid())
     return nullptr;
   return getDerived().RebuildOMPNocontextClause(
       Cond.get(), C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPFilterClause(OMPFilterClause *C) {
   ExprResult ThreadID = getDerived().TransformExpr(C->getThreadID());
   if (ThreadID.isInvalid())
     return nullptr;
   return getDerived().RebuildOMPFilterClause(ThreadID.get(), C->getBeginLoc(),
                                              C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPAlignClause(OMPAlignClause *C) {
   ExprResult E = getDerived().TransformExpr(C->getAlignment());
   if (E.isInvalid())
     return nullptr;
   return getDerived().RebuildOMPAlignClause(E.get(), C->getBeginLoc(),
                                             C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPUnifiedAddressClause(
     OMPUnifiedAddressClause *C) {
   llvm_unreachable("unified_address clause cannot appear in dependent context");
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPUnifiedSharedMemoryClause(
     OMPUnifiedSharedMemoryClause *C) {
   llvm_unreachable(
       "unified_shared_memory clause cannot appear in dependent context");
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPReverseOffloadClause(
     OMPReverseOffloadClause *C) {
   llvm_unreachable("reverse_offload clause cannot appear in dependent context");
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPDynamicAllocatorsClause(
     OMPDynamicAllocatorsClause *C) {
   llvm_unreachable(
       "dynamic_allocators clause cannot appear in dependent context");
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPAtomicDefaultMemOrderClause(
     OMPAtomicDefaultMemOrderClause *C) {
   llvm_unreachable(
       "atomic_default_mem_order clause cannot appear in dependent context");
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPAtClause(OMPAtClause *C) {
   return getDerived().RebuildOMPAtClause(C->getAtKind(), C->getAtKindKwLoc(),
                                          C->getBeginLoc(), C->getLParenLoc(),
                                          C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPSeverityClause(OMPSeverityClause *C) {
   return getDerived().RebuildOMPSeverityClause(
       C->getSeverityKind(), C->getSeverityKindKwLoc(), C->getBeginLoc(),
       C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPMessageClause(OMPMessageClause *C) {
   ExprResult E = getDerived().TransformExpr(C->getMessageString());
   if (E.isInvalid())
     return nullptr;
   return getDerived().RebuildOMPMessageClause(
       C->getMessageString(), C->getBeginLoc(), C->getLParenLoc(),
       C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPPrivateClause(OMPPrivateClause *C) {
   llvm::SmallVector<Expr *, 16> Vars;
   Vars.reserve(C->varlist_size());
   for (auto *VE : C->varlists()) {
     ExprResult EVar = getDerived().TransformExpr(cast<Expr>(VE));
     if (EVar.isInvalid())
       return nullptr;
     Vars.push_back(EVar.get());
   }
   return getDerived().RebuildOMPPrivateClause(
       Vars, C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPFirstprivateClause(
     OMPFirstprivateClause *C) {
   llvm::SmallVector<Expr *, 16> Vars;
   Vars.reserve(C->varlist_size());
   for (auto *VE : C->varlists()) {
     ExprResult EVar = getDerived().TransformExpr(cast<Expr>(VE));
     if (EVar.isInvalid())
       return nullptr;
     Vars.push_back(EVar.get());
   }
   return getDerived().RebuildOMPFirstprivateClause(
       Vars, C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPLastprivateClause(OMPLastprivateClause *C) {
   llvm::SmallVector<Expr *, 16> Vars;
   Vars.reserve(C->varlist_size());
   for (auto *VE : C->varlists()) {
     ExprResult EVar = getDerived().TransformExpr(cast<Expr>(VE));
     if (EVar.isInvalid())
       return nullptr;
     Vars.push_back(EVar.get());
   }
   return getDerived().RebuildOMPLastprivateClause(
       Vars, C->getKind(), C->getKindLoc(), C->getColonLoc(), C->getBeginLoc(),
       C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPSharedClause(OMPSharedClause *C) {
   llvm::SmallVector<Expr *, 16> Vars;
   Vars.reserve(C->varlist_size());
   for (auto *VE : C->varlists()) {
     ExprResult EVar = getDerived().TransformExpr(cast<Expr>(VE));
     if (EVar.isInvalid())
       return nullptr;
     Vars.push_back(EVar.get());
   }
   return getDerived().RebuildOMPSharedClause(Vars, C->getBeginLoc(),
                                              C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPReductionClause(OMPReductionClause *C) {
   llvm::SmallVector<Expr *, 16> Vars;
   Vars.reserve(C->varlist_size());
   for (auto *VE : C->varlists()) {
     ExprResult EVar = getDerived().TransformExpr(cast<Expr>(VE));
     if (EVar.isInvalid())
       return nullptr;
     Vars.push_back(EVar.get());
   }
   CXXScopeSpec ReductionIdScopeSpec;
   ReductionIdScopeSpec.Adopt(C->getQualifierLoc());
 
   DeclarationNameInfo NameInfo = C->getNameInfo();
   if (NameInfo.getName()) {
     NameInfo = getDerived().TransformDeclarationNameInfo(NameInfo);
     if (!NameInfo.getName())
       return nullptr;
   }
   // Build a list of all UDR decls with the same names ranged by the Scopes.
   // The Scope boundary is a duplication of the previous decl.
   llvm::SmallVector<Expr *, 16> UnresolvedReductions;
   for (auto *E : C->reduction_ops()) {
     // Transform all the decls.
     if (E) {
       auto *ULE = cast<UnresolvedLookupExpr>(E);
       UnresolvedSet<8> Decls;
       for (auto *D : ULE->decls()) {
         NamedDecl *InstD =
             cast<NamedDecl>(getDerived().TransformDecl(E->getExprLoc(), D));
         Decls.addDecl(InstD, InstD->getAccess());
       }
       UnresolvedReductions.push_back(
        UnresolvedLookupExpr::Create(
           SemaRef.Context, /*NamingClass=*/nullptr,
           ReductionIdScopeSpec.getWithLocInContext(SemaRef.Context),
           NameInfo, /*ADL=*/true, ULE->isOverloaded(),
           Decls.begin(), Decls.end()));
     } else
       UnresolvedReductions.push_back(nullptr);
   }
   return getDerived().RebuildOMPReductionClause(
       Vars, C->getModifier(), C->getBeginLoc(), C->getLParenLoc(),
       C->getModifierLoc(), C->getColonLoc(), C->getEndLoc(),
       ReductionIdScopeSpec, NameInfo, UnresolvedReductions);
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPTaskReductionClause(
     OMPTaskReductionClause *C) {
   llvm::SmallVector<Expr *, 16> Vars;
   Vars.reserve(C->varlist_size());
   for (auto *VE : C->varlists()) {
     ExprResult EVar = getDerived().TransformExpr(cast<Expr>(VE));
     if (EVar.isInvalid())
       return nullptr;
     Vars.push_back(EVar.get());
   }
   CXXScopeSpec ReductionIdScopeSpec;
   ReductionIdScopeSpec.Adopt(C->getQualifierLoc());
 
   DeclarationNameInfo NameInfo = C->getNameInfo();
   if (NameInfo.getName()) {
     NameInfo = getDerived().TransformDeclarationNameInfo(NameInfo);
     if (!NameInfo.getName())
       return nullptr;
   }
   // Build a list of all UDR decls with the same names ranged by the Scopes.
   // The Scope boundary is a duplication of the previous decl.
   llvm::SmallVector<Expr *, 16> UnresolvedReductions;
   for (auto *E : C->reduction_ops()) {
     // Transform all the decls.
     if (E) {
       auto *ULE = cast<UnresolvedLookupExpr>(E);
       UnresolvedSet<8> Decls;
       for (auto *D : ULE->decls()) {
         NamedDecl *InstD =
             cast<NamedDecl>(getDerived().TransformDecl(E->getExprLoc(), D));
         Decls.addDecl(InstD, InstD->getAccess());
       }
       UnresolvedReductions.push_back(UnresolvedLookupExpr::Create(
           SemaRef.Context, /*NamingClass=*/nullptr,
           ReductionIdScopeSpec.getWithLocInContext(SemaRef.Context), NameInfo,
           /*ADL=*/true, ULE->isOverloaded(), Decls.begin(), Decls.end()));
     } else
       UnresolvedReductions.push_back(nullptr);
   }
   return getDerived().RebuildOMPTaskReductionClause(
       Vars, C->getBeginLoc(), C->getLParenLoc(), C->getColonLoc(),
       C->getEndLoc(), ReductionIdScopeSpec, NameInfo, UnresolvedReductions);
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPInReductionClause(OMPInReductionClause *C) {
   llvm::SmallVector<Expr *, 16> Vars;
   Vars.reserve(C->varlist_size());
   for (auto *VE : C->varlists()) {
     ExprResult EVar = getDerived().TransformExpr(cast<Expr>(VE));
     if (EVar.isInvalid())
       return nullptr;
     Vars.push_back(EVar.get());
   }
   CXXScopeSpec ReductionIdScopeSpec;
   ReductionIdScopeSpec.Adopt(C->getQualifierLoc());
 
   DeclarationNameInfo NameInfo = C->getNameInfo();
   if (NameInfo.getName()) {
     NameInfo = getDerived().TransformDeclarationNameInfo(NameInfo);
     if (!NameInfo.getName())
       return nullptr;
   }
   // Build a list of all UDR decls with the same names ranged by the Scopes.
   // The Scope boundary is a duplication of the previous decl.
   llvm::SmallVector<Expr *, 16> UnresolvedReductions;
   for (auto *E : C->reduction_ops()) {
     // Transform all the decls.
     if (E) {
       auto *ULE = cast<UnresolvedLookupExpr>(E);
       UnresolvedSet<8> Decls;
       for (auto *D : ULE->decls()) {
         NamedDecl *InstD =
             cast<NamedDecl>(getDerived().TransformDecl(E->getExprLoc(), D));
         Decls.addDecl(InstD, InstD->getAccess());
       }
       UnresolvedReductions.push_back(UnresolvedLookupExpr::Create(
           SemaRef.Context, /*NamingClass=*/nullptr,
           ReductionIdScopeSpec.getWithLocInContext(SemaRef.Context), NameInfo,
           /*ADL=*/true, ULE->isOverloaded(), Decls.begin(), Decls.end()));
     } else
       UnresolvedReductions.push_back(nullptr);
   }
   return getDerived().RebuildOMPInReductionClause(
       Vars, C->getBeginLoc(), C->getLParenLoc(), C->getColonLoc(),
       C->getEndLoc(), ReductionIdScopeSpec, NameInfo, UnresolvedReductions);
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPLinearClause(OMPLinearClause *C) {
   llvm::SmallVector<Expr *, 16> Vars;
   Vars.reserve(C->varlist_size());
   for (auto *VE : C->varlists()) {
     ExprResult EVar = getDerived().TransformExpr(cast<Expr>(VE));
     if (EVar.isInvalid())
       return nullptr;
     Vars.push_back(EVar.get());
   }
   ExprResult Step = getDerived().TransformExpr(C->getStep());
   if (Step.isInvalid())
     return nullptr;
   return getDerived().RebuildOMPLinearClause(
       Vars, Step.get(), C->getBeginLoc(), C->getLParenLoc(), C->getModifier(),
       C->getModifierLoc(), C->getColonLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPAlignedClause(OMPAlignedClause *C) {
   llvm::SmallVector<Expr *, 16> Vars;
   Vars.reserve(C->varlist_size());
   for (auto *VE : C->varlists()) {
     ExprResult EVar = getDerived().TransformExpr(cast<Expr>(VE));
     if (EVar.isInvalid())
       return nullptr;
     Vars.push_back(EVar.get());
   }
   ExprResult Alignment = getDerived().TransformExpr(C->getAlignment());
   if (Alignment.isInvalid())
     return nullptr;
   return getDerived().RebuildOMPAlignedClause(
       Vars, Alignment.get(), C->getBeginLoc(), C->getLParenLoc(),
       C->getColonLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPCopyinClause(OMPCopyinClause *C) {
   llvm::SmallVector<Expr *, 16> Vars;
   Vars.reserve(C->varlist_size());
   for (auto *VE : C->varlists()) {
     ExprResult EVar = getDerived().TransformExpr(cast<Expr>(VE));
     if (EVar.isInvalid())
       return nullptr;
     Vars.push_back(EVar.get());
   }
   return getDerived().RebuildOMPCopyinClause(Vars, C->getBeginLoc(),
                                              C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPCopyprivateClause(OMPCopyprivateClause *C) {
   llvm::SmallVector<Expr *, 16> Vars;
   Vars.reserve(C->varlist_size());
   for (auto *VE : C->varlists()) {
     ExprResult EVar = getDerived().TransformExpr(cast<Expr>(VE));
     if (EVar.isInvalid())
       return nullptr;
     Vars.push_back(EVar.get());
   }
   return getDerived().RebuildOMPCopyprivateClause(
       Vars, C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPFlushClause(OMPFlushClause *C) {
   llvm::SmallVector<Expr *, 16> Vars;
   Vars.reserve(C->varlist_size());
   for (auto *VE : C->varlists()) {
     ExprResult EVar = getDerived().TransformExpr(cast<Expr>(VE));
     if (EVar.isInvalid())
       return nullptr;
     Vars.push_back(EVar.get());
   }
   return getDerived().RebuildOMPFlushClause(Vars, C->getBeginLoc(),
                                             C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPDepobjClause(OMPDepobjClause *C) {
   ExprResult E = getDerived().TransformExpr(C->getDepobj());
   if (E.isInvalid())
     return nullptr;
   return getDerived().RebuildOMPDepobjClause(E.get(), C->getBeginLoc(),
                                              C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPDependClause(OMPDependClause *C) {
   llvm::SmallVector<Expr *, 16> Vars;
   Expr *DepModifier = C->getModifier();
   if (DepModifier) {
     ExprResult DepModRes = getDerived().TransformExpr(DepModifier);
     if (DepModRes.isInvalid())
       return nullptr;
     DepModifier = DepModRes.get();
   }
   Vars.reserve(C->varlist_size());
   for (auto *VE : C->varlists()) {
     ExprResult EVar = getDerived().TransformExpr(cast<Expr>(VE));
     if (EVar.isInvalid())
       return nullptr;
     Vars.push_back(EVar.get());
   }
   return getDerived().RebuildOMPDependClause(
       {C->getDependencyKind(), C->getDependencyLoc(), C->getColonLoc(),
        C->getOmpAllMemoryLoc()},
       DepModifier, Vars, C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPDeviceClause(OMPDeviceClause *C) {
   ExprResult E = getDerived().TransformExpr(C->getDevice());
   if (E.isInvalid())
     return nullptr;
   return getDerived().RebuildOMPDeviceClause(
       C->getModifier(), E.get(), C->getBeginLoc(), C->getLParenLoc(),
       C->getModifierLoc(), C->getEndLoc());
 }
 
 template <typename Derived, class T>
 bool transformOMPMappableExprListClause(
     TreeTransform<Derived> &TT, OMPMappableExprListClause<T> *C,
     llvm::SmallVectorImpl<Expr *> &Vars, CXXScopeSpec &MapperIdScopeSpec,
     DeclarationNameInfo &MapperIdInfo,
     llvm::SmallVectorImpl<Expr *> &UnresolvedMappers) {
   // Transform expressions in the list.
   Vars.reserve(C->varlist_size());
   for (auto *VE : C->varlists()) {
     ExprResult EVar = TT.getDerived().TransformExpr(cast<Expr>(VE));
     if (EVar.isInvalid())
       return true;
     Vars.push_back(EVar.get());
   }
   // Transform mapper scope specifier and identifier.
   NestedNameSpecifierLoc QualifierLoc;
   if (C->getMapperQualifierLoc()) {
     QualifierLoc = TT.getDerived().TransformNestedNameSpecifierLoc(
         C->getMapperQualifierLoc());
     if (!QualifierLoc)
       return true;
   }
   MapperIdScopeSpec.Adopt(QualifierLoc);
   MapperIdInfo = C->getMapperIdInfo();
   if (MapperIdInfo.getName()) {
     MapperIdInfo = TT.getDerived().TransformDeclarationNameInfo(MapperIdInfo);
     if (!MapperIdInfo.getName())
       return true;
   }
   // Build a list of all candidate OMPDeclareMapperDecls, which is provided by
   // the previous user-defined mapper lookup in dependent environment.
   for (auto *E : C->mapperlists()) {
     // Transform all the decls.
     if (E) {
       auto *ULE = cast<UnresolvedLookupExpr>(E);
       UnresolvedSet<8> Decls;
       for (auto *D : ULE->decls()) {
         NamedDecl *InstD =
             cast<NamedDecl>(TT.getDerived().TransformDecl(E->getExprLoc(), D));
         Decls.addDecl(InstD, InstD->getAccess());
       }
       UnresolvedMappers.push_back(UnresolvedLookupExpr::Create(
           TT.getSema().Context, /*NamingClass=*/nullptr,
           MapperIdScopeSpec.getWithLocInContext(TT.getSema().Context),
           MapperIdInfo, /*ADL=*/true, ULE->isOverloaded(), Decls.begin(),
           Decls.end()));
     } else {
       UnresolvedMappers.push_back(nullptr);
     }
   }
   return false;
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPMapClause(OMPMapClause *C) {
   OMPVarListLocTy Locs(C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
   llvm::SmallVector<Expr *, 16> Vars;
   Expr *IteratorModifier = C->getIteratorModifier();
   if (IteratorModifier) {
     ExprResult MapModRes = getDerived().TransformExpr(IteratorModifier);
     if (MapModRes.isInvalid())
       return nullptr;
     IteratorModifier = MapModRes.get();
   }
   CXXScopeSpec MapperIdScopeSpec;
   DeclarationNameInfo MapperIdInfo;
   llvm::SmallVector<Expr *, 16> UnresolvedMappers;
   if (transformOMPMappableExprListClause<Derived, OMPMapClause>(
           *this, C, Vars, MapperIdScopeSpec, MapperIdInfo, UnresolvedMappers))
     return nullptr;
   return getDerived().RebuildOMPMapClause(
       IteratorModifier, C->getMapTypeModifiers(), C->getMapTypeModifiersLoc(),
       MapperIdScopeSpec, MapperIdInfo, C->getMapType(), C->isImplicitMapType(),
       C->getMapLoc(), C->getColonLoc(), Vars, Locs, UnresolvedMappers);
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPAllocateClause(OMPAllocateClause *C) {
   Expr *Allocator = C->getAllocator();
   if (Allocator) {
     ExprResult AllocatorRes = getDerived().TransformExpr(Allocator);
     if (AllocatorRes.isInvalid())
       return nullptr;
     Allocator = AllocatorRes.get();
   }
   llvm::SmallVector<Expr *, 16> Vars;
   Vars.reserve(C->varlist_size());
   for (auto *VE : C->varlists()) {
     ExprResult EVar = getDerived().TransformExpr(cast<Expr>(VE));
     if (EVar.isInvalid())
       return nullptr;
     Vars.push_back(EVar.get());
   }
   return getDerived().RebuildOMPAllocateClause(
       Allocator, Vars, C->getBeginLoc(), C->getLParenLoc(), C->getColonLoc(),
       C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPNumTeamsClause(OMPNumTeamsClause *C) {
   ExprResult E = getDerived().TransformExpr(C->getNumTeams());
   if (E.isInvalid())
     return nullptr;
   return getDerived().RebuildOMPNumTeamsClause(
       E.get(), C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPThreadLimitClause(OMPThreadLimitClause *C) {
   ExprResult E = getDerived().TransformExpr(C->getThreadLimit());
   if (E.isInvalid())
     return nullptr;
   return getDerived().RebuildOMPThreadLimitClause(
       E.get(), C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPPriorityClause(OMPPriorityClause *C) {
   ExprResult E = getDerived().TransformExpr(C->getPriority());
   if (E.isInvalid())
     return nullptr;
   return getDerived().RebuildOMPPriorityClause(
       E.get(), C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPGrainsizeClause(OMPGrainsizeClause *C) {
   ExprResult E = getDerived().TransformExpr(C->getGrainsize());
   if (E.isInvalid())
     return nullptr;
   return getDerived().RebuildOMPGrainsizeClause(
       C->getModifier(), E.get(), C->getBeginLoc(), C->getLParenLoc(),
       C->getModifierLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPNumTasksClause(OMPNumTasksClause *C) {
   ExprResult E = getDerived().TransformExpr(C->getNumTasks());
   if (E.isInvalid())
     return nullptr;
   return getDerived().RebuildOMPNumTasksClause(
       C->getModifier(), E.get(), C->getBeginLoc(), C->getLParenLoc(),
       C->getModifierLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPHintClause(OMPHintClause *C) {
   ExprResult E = getDerived().TransformExpr(C->getHint());
   if (E.isInvalid())
     return nullptr;
   return getDerived().RebuildOMPHintClause(E.get(), C->getBeginLoc(),
                                            C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPDistScheduleClause(
     OMPDistScheduleClause *C) {
   ExprResult E = getDerived().TransformExpr(C->getChunkSize());
   if (E.isInvalid())
     return nullptr;
   return getDerived().RebuildOMPDistScheduleClause(
       C->getDistScheduleKind(), E.get(), C->getBeginLoc(), C->getLParenLoc(),
       C->getDistScheduleKindLoc(), C->getCommaLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPDefaultmapClause(OMPDefaultmapClause *C) {
   // Rebuild Defaultmap Clause since we need to invoke the checking of
   // defaultmap(none:variable-category) after template initialization.
   return getDerived().RebuildOMPDefaultmapClause(C->getDefaultmapModifier(),
                                                  C->getDefaultmapKind(),
                                                  C->getBeginLoc(),
                                                  C->getLParenLoc(),
                                                  C->getDefaultmapModifierLoc(),
                                                  C->getDefaultmapKindLoc(),
                                                  C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPToClause(OMPToClause *C) {
   OMPVarListLocTy Locs(C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
   llvm::SmallVector<Expr *, 16> Vars;
   CXXScopeSpec MapperIdScopeSpec;
   DeclarationNameInfo MapperIdInfo;
   llvm::SmallVector<Expr *, 16> UnresolvedMappers;
   if (transformOMPMappableExprListClause<Derived, OMPToClause>(
           *this, C, Vars, MapperIdScopeSpec, MapperIdInfo, UnresolvedMappers))
     return nullptr;
   return getDerived().RebuildOMPToClause(
       C->getMotionModifiers(), C->getMotionModifiersLoc(), MapperIdScopeSpec,
       MapperIdInfo, C->getColonLoc(), Vars, Locs, UnresolvedMappers);
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPFromClause(OMPFromClause *C) {
   OMPVarListLocTy Locs(C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
   llvm::SmallVector<Expr *, 16> Vars;
   CXXScopeSpec MapperIdScopeSpec;
   DeclarationNameInfo MapperIdInfo;
   llvm::SmallVector<Expr *, 16> UnresolvedMappers;
   if (transformOMPMappableExprListClause<Derived, OMPFromClause>(
           *this, C, Vars, MapperIdScopeSpec, MapperIdInfo, UnresolvedMappers))
     return nullptr;
   return getDerived().RebuildOMPFromClause(
       C->getMotionModifiers(), C->getMotionModifiersLoc(), MapperIdScopeSpec,
       MapperIdInfo, C->getColonLoc(), Vars, Locs, UnresolvedMappers);
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPUseDevicePtrClause(
     OMPUseDevicePtrClause *C) {
   llvm::SmallVector<Expr *, 16> Vars;
   Vars.reserve(C->varlist_size());
   for (auto *VE : C->varlists()) {
     ExprResult EVar = getDerived().TransformExpr(cast<Expr>(VE));
     if (EVar.isInvalid())
       return nullptr;
     Vars.push_back(EVar.get());
   }
   OMPVarListLocTy Locs(C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
   return getDerived().RebuildOMPUseDevicePtrClause(Vars, Locs);
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPUseDeviceAddrClause(
     OMPUseDeviceAddrClause *C) {
   llvm::SmallVector<Expr *, 16> Vars;
   Vars.reserve(C->varlist_size());
   for (auto *VE : C->varlists()) {
     ExprResult EVar = getDerived().TransformExpr(cast<Expr>(VE));
     if (EVar.isInvalid())
       return nullptr;
     Vars.push_back(EVar.get());
   }
   OMPVarListLocTy Locs(C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
   return getDerived().RebuildOMPUseDeviceAddrClause(Vars, Locs);
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPIsDevicePtrClause(OMPIsDevicePtrClause *C) {
   llvm::SmallVector<Expr *, 16> Vars;
   Vars.reserve(C->varlist_size());
   for (auto *VE : C->varlists()) {
     ExprResult EVar = getDerived().TransformExpr(cast<Expr>(VE));
     if (EVar.isInvalid())
       return nullptr;
     Vars.push_back(EVar.get());
   }
   OMPVarListLocTy Locs(C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
   return getDerived().RebuildOMPIsDevicePtrClause(Vars, Locs);
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPHasDeviceAddrClause(
     OMPHasDeviceAddrClause *C) {
   llvm::SmallVector<Expr *, 16> Vars;
   Vars.reserve(C->varlist_size());
   for (auto *VE : C->varlists()) {
     ExprResult EVar = getDerived().TransformExpr(cast<Expr>(VE));
     if (EVar.isInvalid())
       return nullptr;
     Vars.push_back(EVar.get());
   }
   OMPVarListLocTy Locs(C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
   return getDerived().RebuildOMPHasDeviceAddrClause(Vars, Locs);
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPNontemporalClause(OMPNontemporalClause *C) {
   llvm::SmallVector<Expr *, 16> Vars;
   Vars.reserve(C->varlist_size());
   for (auto *VE : C->varlists()) {
     ExprResult EVar = getDerived().TransformExpr(cast<Expr>(VE));
     if (EVar.isInvalid())
       return nullptr;
     Vars.push_back(EVar.get());
   }
   return getDerived().RebuildOMPNontemporalClause(
       Vars, C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPInclusiveClause(OMPInclusiveClause *C) {
   llvm::SmallVector<Expr *, 16> Vars;
   Vars.reserve(C->varlist_size());
   for (auto *VE : C->varlists()) {
     ExprResult EVar = getDerived().TransformExpr(cast<Expr>(VE));
     if (EVar.isInvalid())
       return nullptr;
     Vars.push_back(EVar.get());
   }
   return getDerived().RebuildOMPInclusiveClause(
       Vars, C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPExclusiveClause(OMPExclusiveClause *C) {
   llvm::SmallVector<Expr *, 16> Vars;
   Vars.reserve(C->varlist_size());
   for (auto *VE : C->varlists()) {
     ExprResult EVar = getDerived().TransformExpr(cast<Expr>(VE));
     if (EVar.isInvalid())
       return nullptr;
     Vars.push_back(EVar.get());
   }
   return getDerived().RebuildOMPExclusiveClause(
       Vars, C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPUsesAllocatorsClause(
     OMPUsesAllocatorsClause *C) {
   SmallVector<Sema::UsesAllocatorsData, 16> Data;
   Data.reserve(C->getNumberOfAllocators());
   for (unsigned I = 0, E = C->getNumberOfAllocators(); I < E; ++I) {
     OMPUsesAllocatorsClause::Data D = C->getAllocatorData(I);
     ExprResult Allocator = getDerived().TransformExpr(D.Allocator);
     if (Allocator.isInvalid())
       continue;
     ExprResult AllocatorTraits;
     if (Expr *AT = D.AllocatorTraits) {
       AllocatorTraits = getDerived().TransformExpr(AT);
       if (AllocatorTraits.isInvalid())
         continue;
     }
     Sema::UsesAllocatorsData &NewD = Data.emplace_back();
     NewD.Allocator = Allocator.get();
     NewD.AllocatorTraits = AllocatorTraits.get();
     NewD.LParenLoc = D.LParenLoc;
     NewD.RParenLoc = D.RParenLoc;
   }
   return getDerived().RebuildOMPUsesAllocatorsClause(
       Data, C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPAffinityClause(OMPAffinityClause *C) {
   SmallVector<Expr *, 4> Locators;
   Locators.reserve(C->varlist_size());
   ExprResult ModifierRes;
   if (Expr *Modifier = C->getModifier()) {
     ModifierRes = getDerived().TransformExpr(Modifier);
     if (ModifierRes.isInvalid())
       return nullptr;
   }
   for (Expr *E : C->varlists()) {
     ExprResult Locator = getDerived().TransformExpr(E);
     if (Locator.isInvalid())
       continue;
     Locators.push_back(Locator.get());
   }
   return getDerived().RebuildOMPAffinityClause(
       C->getBeginLoc(), C->getLParenLoc(), C->getColonLoc(), C->getEndLoc(),
       ModifierRes.get(), Locators);
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPOrderClause(OMPOrderClause *C) {
   return getDerived().RebuildOMPOrderClause(
       C->getKind(), C->getKindKwLoc(), C->getBeginLoc(), C->getLParenLoc(),
       C->getEndLoc(), C->getModifier(), C->getModifierKwLoc());
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPBindClause(OMPBindClause *C) {
   return getDerived().RebuildOMPBindClause(
       C->getBindKind(), C->getBindKindLoc(), C->getBeginLoc(),
       C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *TreeTransform<Derived>::TransformOMPXDynCGroupMemClause(
     OMPXDynCGroupMemClause *C) {
   ExprResult Size = getDerived().TransformExpr(C->getSize());
   if (Size.isInvalid())
     return nullptr;
   return getDerived().RebuildOMPXDynCGroupMemClause(
       Size.get(), C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPDoacrossClause(OMPDoacrossClause *C) {
   llvm::SmallVector<Expr *, 16> Vars;
   Vars.reserve(C->varlist_size());
   for (auto *VE : C->varlists()) {
     ExprResult EVar = getDerived().TransformExpr(cast<Expr>(VE));
     if (EVar.isInvalid())
       return nullptr;
     Vars.push_back(EVar.get());
   }
   return getDerived().RebuildOMPDoacrossClause(
       C->getDependenceType(), C->getDependenceLoc(), C->getColonLoc(), Vars,
       C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
 }
 
 //===----------------------------------------------------------------------===//
 // Expression transformation
 //===----------------------------------------------------------------------===//
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformConstantExpr(ConstantExpr *E) {
   return TransformExpr(E->getSubExpr());
 }
 
 template <typename Derived>
 ExprResult TreeTransform<Derived>::TransformSYCLUniqueStableNameExpr(
     SYCLUniqueStableNameExpr *E) {
   if (!E->isTypeDependent())
     return E;
 
   TypeSourceInfo *NewT = getDerived().TransformType(E->getTypeSourceInfo());
 
   if (!NewT)
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() && E->getTypeSourceInfo() == NewT)
     return E;
 
   return getDerived().RebuildSYCLUniqueStableNameExpr(
       E->getLocation(), E->getLParenLocation(), E->getRParenLocation(), NewT);
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformPredefinedExpr(PredefinedExpr *E) {
   if (!E->isTypeDependent())
     return E;
 
   return getDerived().RebuildPredefinedExpr(E->getLocation(),
                                             E->getIdentKind());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformDeclRefExpr(DeclRefExpr *E) {
   NestedNameSpecifierLoc QualifierLoc;
   if (E->getQualifierLoc()) {
     QualifierLoc
       = getDerived().TransformNestedNameSpecifierLoc(E->getQualifierLoc());
     if (!QualifierLoc)
       return ExprError();
   }
 
   ValueDecl *ND
     = cast_or_null<ValueDecl>(getDerived().TransformDecl(E->getLocation(),
                                                          E->getDecl()));
   if (!ND)
     return ExprError();
 
   NamedDecl *Found = ND;
   if (E->getFoundDecl() != E->getDecl()) {
     Found = cast_or_null<NamedDecl>(
         getDerived().TransformDecl(E->getLocation(), E->getFoundDecl()));
     if (!Found)
       return ExprError();
   }
 
   DeclarationNameInfo NameInfo = E->getNameInfo();
   if (NameInfo.getName()) {
     NameInfo = getDerived().TransformDeclarationNameInfo(NameInfo);
     if (!NameInfo.getName())
       return ExprError();
   }
 
   if (!getDerived().AlwaysRebuild() &&
       QualifierLoc == E->getQualifierLoc() &&
       ND == E->getDecl() &&
       Found == E->getFoundDecl() &&
       NameInfo.getName() == E->getDecl()->getDeclName() &&
       !E->hasExplicitTemplateArgs()) {
 
     // Mark it referenced in the new context regardless.
     // FIXME: this is a bit instantiation-specific.
     SemaRef.MarkDeclRefReferenced(E);
 
     return E;
   }
 
   TemplateArgumentListInfo TransArgs, *TemplateArgs = nullptr;
   if (E->hasExplicitTemplateArgs()) {
     TemplateArgs = &TransArgs;
     TransArgs.setLAngleLoc(E->getLAngleLoc());
     TransArgs.setRAngleLoc(E->getRAngleLoc());
     if (getDerived().TransformTemplateArguments(E->getTemplateArgs(),
                                                 E->getNumTemplateArgs(),
                                                 TransArgs))
       return ExprError();
   }
 
   return getDerived().RebuildDeclRefExpr(QualifierLoc, ND, NameInfo,
                                          Found, TemplateArgs);
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformIntegerLiteral(IntegerLiteral *E) {
   return E;
 }
 
 template <typename Derived>
 ExprResult TreeTransform<Derived>::TransformFixedPointLiteral(
     FixedPointLiteral *E) {
   return E;
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformFloatingLiteral(FloatingLiteral *E) {
   return E;
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformImaginaryLiteral(ImaginaryLiteral *E) {
   return E;
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformStringLiteral(StringLiteral *E) {
   return E;
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCharacterLiteral(CharacterLiteral *E) {
   return E;
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformUserDefinedLiteral(UserDefinedLiteral *E) {
   return getDerived().TransformCallExpr(E);
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformGenericSelectionExpr(GenericSelectionExpr *E) {
   ExprResult ControllingExpr;
   TypeSourceInfo *ControllingType = nullptr;
   if (E->isExprPredicate())
     ControllingExpr = getDerived().TransformExpr(E->getControllingExpr());
   else
     ControllingType = getDerived().TransformType(E->getControllingType());
 
   if (ControllingExpr.isInvalid() && !ControllingType)
     return ExprError();
 
   SmallVector<Expr *, 4> AssocExprs;
   SmallVector<TypeSourceInfo *, 4> AssocTypes;
   for (const GenericSelectionExpr::Association Assoc : E->associations()) {
     TypeSourceInfo *TSI = Assoc.getTypeSourceInfo();
     if (TSI) {
       TypeSourceInfo *AssocType = getDerived().TransformType(TSI);
       if (!AssocType)
         return ExprError();
       AssocTypes.push_back(AssocType);
     } else {
       AssocTypes.push_back(nullptr);
     }
 
     ExprResult AssocExpr =
         getDerived().TransformExpr(Assoc.getAssociationExpr());
     if (AssocExpr.isInvalid())
       return ExprError();
     AssocExprs.push_back(AssocExpr.get());
   }
 
   if (!ControllingType)
   return getDerived().RebuildGenericSelectionExpr(E->getGenericLoc(),
                                                   E->getDefaultLoc(),
                                                   E->getRParenLoc(),
                                                   ControllingExpr.get(),
                                                   AssocTypes,
                                                   AssocExprs);
   return getDerived().RebuildGenericSelectionExpr(
       E->getGenericLoc(), E->getDefaultLoc(), E->getRParenLoc(),
       ControllingType, AssocTypes, AssocExprs);
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformParenExpr(ParenExpr *E) {
   ExprResult SubExpr = getDerived().TransformExpr(E->getSubExpr());
   if (SubExpr.isInvalid())
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() && SubExpr.get() == E->getSubExpr())
     return E;
 
   return getDerived().RebuildParenExpr(SubExpr.get(), E->getLParen(),
                                        E->getRParen());
 }
 
 /// The operand of a unary address-of operator has special rules: it's
 /// allowed to refer to a non-static member of a class even if there's no 'this'
 /// object available.
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformAddressOfOperand(Expr *E) {
   if (DependentScopeDeclRefExpr *DRE = dyn_cast<DependentScopeDeclRefExpr>(E))
     return getDerived().TransformDependentScopeDeclRefExpr(DRE, true, nullptr);
   else
     return getDerived().TransformExpr(E);
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformUnaryOperator(UnaryOperator *E) {
   ExprResult SubExpr;
   if (E->getOpcode() == UO_AddrOf)
     SubExpr = TransformAddressOfOperand(E->getSubExpr());
   else
     SubExpr = TransformExpr(E->getSubExpr());
   if (SubExpr.isInvalid())
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() && SubExpr.get() == E->getSubExpr())
     return E;
 
   return getDerived().RebuildUnaryOperator(E->getOperatorLoc(),
                                            E->getOpcode(),
                                            SubExpr.get());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformOffsetOfExpr(OffsetOfExpr *E) {
   // Transform the type.
   TypeSourceInfo *Type = getDerived().TransformType(E->getTypeSourceInfo());
   if (!Type)
     return ExprError();
 
   // Transform all of the components into components similar to what the
   // parser uses.
   // FIXME: It would be slightly more efficient in the non-dependent case to
   // just map FieldDecls, rather than requiring the rebuilder to look for
   // the fields again. However, __builtin_offsetof is rare enough in
   // template code that we don't care.
   bool ExprChanged = false;
   typedef Sema::OffsetOfComponent Component;
   SmallVector<Component, 4> Components;
   for (unsigned I = 0, N = E->getNumComponents(); I != N; ++I) {
     const OffsetOfNode &ON = E->getComponent(I);
     Component Comp;
     Comp.isBrackets = true;
     Comp.LocStart = ON.getSourceRange().getBegin();
     Comp.LocEnd = ON.getSourceRange().getEnd();
     switch (ON.getKind()) {
     case OffsetOfNode::Array: {
       Expr *FromIndex = E->getIndexExpr(ON.getArrayExprIndex());
       ExprResult Index = getDerived().TransformExpr(FromIndex);
       if (Index.isInvalid())
         return ExprError();
 
       ExprChanged = ExprChanged || Index.get() != FromIndex;
       Comp.isBrackets = true;
       Comp.U.E = Index.get();
       break;
     }
 
     case OffsetOfNode::Field:
     case OffsetOfNode::Identifier:
       Comp.isBrackets = false;
       Comp.U.IdentInfo = ON.getFieldName();
       if (!Comp.U.IdentInfo)
         continue;
 
       break;
 
     case OffsetOfNode::Base:
       // Will be recomputed during the rebuild.
       continue;
     }
 
     Components.push_back(Comp);
   }
 
   // If nothing changed, retain the existing expression.
   if (!getDerived().AlwaysRebuild() &&
       Type == E->getTypeSourceInfo() &&
       !ExprChanged)
     return E;
 
   // Build a new offsetof expression.
   return getDerived().RebuildOffsetOfExpr(E->getOperatorLoc(), Type,
                                           Components, E->getRParenLoc());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformOpaqueValueExpr(OpaqueValueExpr *E) {
   assert((!E->getSourceExpr() || getDerived().AlreadyTransformed(E->getType())) &&
          "opaque value expression requires transformation");
   return E;
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformTypoExpr(TypoExpr *E) {
   return E;
 }
 
 template <typename Derived>
 ExprResult TreeTransform<Derived>::TransformRecoveryExpr(RecoveryExpr *E) {
   llvm::SmallVector<Expr *, 8> Children;
   bool Changed = false;
   for (Expr *C : E->subExpressions()) {
     ExprResult NewC = getDerived().TransformExpr(C);
     if (NewC.isInvalid())
       return ExprError();
     Children.push_back(NewC.get());
 
     Changed |= NewC.get() != C;
   }
   if (!getDerived().AlwaysRebuild() && !Changed)
     return E;
   return getDerived().RebuildRecoveryExpr(E->getBeginLoc(), E->getEndLoc(),
                                           Children, E->getType());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformPseudoObjectExpr(PseudoObjectExpr *E) {
   // Rebuild the syntactic form.  The original syntactic form has
   // opaque-value expressions in it, so strip those away and rebuild
   // the result.  This is a really awful way of doing this, but the
   // better solution (rebuilding the semantic expressions and
   // rebinding OVEs as necessary) doesn't work; we'd need
   // TreeTransform to not strip away implicit conversions.
   Expr *newSyntacticForm = SemaRef.recreateSyntacticForm(E);
   ExprResult result = getDerived().TransformExpr(newSyntacticForm);
   if (result.isInvalid()) return ExprError();
 
   // If that gives us a pseudo-object result back, the pseudo-object
   // expression must have been an lvalue-to-rvalue conversion which we
   // should reapply.
   if (result.get()->hasPlaceholderType(BuiltinType::PseudoObject))
     result = SemaRef.checkPseudoObjectRValue(result.get());
 
   return result;
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformUnaryExprOrTypeTraitExpr(
                                                 UnaryExprOrTypeTraitExpr *E) {
   if (E->isArgumentType()) {
     TypeSourceInfo *OldT = E->getArgumentTypeInfo();
 
     TypeSourceInfo *NewT = getDerived().TransformType(OldT);
     if (!NewT)
       return ExprError();
 
     if (!getDerived().AlwaysRebuild() && OldT == NewT)
       return E;
 
     return getDerived().RebuildUnaryExprOrTypeTrait(NewT, E->getOperatorLoc(),
                                                     E->getKind(),
                                                     E->getSourceRange());
   }
 
   // C++0x [expr.sizeof]p1:
   //   The operand is either an expression, which is an unevaluated operand
   //   [...]
   EnterExpressionEvaluationContext Unevaluated(
       SemaRef, Sema::ExpressionEvaluationContext::Unevaluated,
       Sema::ReuseLambdaContextDecl);
 
   // Try to recover if we have something like sizeof(T::X) where X is a type.
   // Notably, there must be *exactly* one set of parens if X is a type.
   TypeSourceInfo *RecoveryTSI = nullptr;
   ExprResult SubExpr;
   auto *PE = dyn_cast<ParenExpr>(E->getArgumentExpr());
   if (auto *DRE =
           PE ? dyn_cast<DependentScopeDeclRefExpr>(PE->getSubExpr()) : nullptr)
     SubExpr = getDerived().TransformParenDependentScopeDeclRefExpr(
         PE, DRE, false, &RecoveryTSI);
   else
     SubExpr = getDerived().TransformExpr(E->getArgumentExpr());
 
   if (RecoveryTSI) {
     return getDerived().RebuildUnaryExprOrTypeTrait(
         RecoveryTSI, E->getOperatorLoc(), E->getKind(), E->getSourceRange());
   } else if (SubExpr.isInvalid())
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() && SubExpr.get() == E->getArgumentExpr())
     return E;
 
   return getDerived().RebuildUnaryExprOrTypeTrait(SubExpr.get(),
                                                   E->getOperatorLoc(),
                                                   E->getKind(),
                                                   E->getSourceRange());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformArraySubscriptExpr(ArraySubscriptExpr *E) {
   ExprResult LHS = getDerived().TransformExpr(E->getLHS());
   if (LHS.isInvalid())
     return ExprError();
 
   ExprResult RHS = getDerived().TransformExpr(E->getRHS());
   if (RHS.isInvalid())
     return ExprError();
 
 
   if (!getDerived().AlwaysRebuild() &&
       LHS.get() == E->getLHS() &&
       RHS.get() == E->getRHS())
     return E;
 
   return getDerived().RebuildArraySubscriptExpr(
       LHS.get(),
       /*FIXME:*/ E->getLHS()->getBeginLoc(), RHS.get(), E->getRBracketLoc());
 }
 
 template <typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformMatrixSubscriptExpr(MatrixSubscriptExpr *E) {
   ExprResult Base = getDerived().TransformExpr(E->getBase());
   if (Base.isInvalid())
     return ExprError();
 
   ExprResult RowIdx = getDerived().TransformExpr(E->getRowIdx());
   if (RowIdx.isInvalid())
     return ExprError();
 
   ExprResult ColumnIdx = getDerived().TransformExpr(E->getColumnIdx());
   if (ColumnIdx.isInvalid())
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() && Base.get() == E->getBase() &&
       RowIdx.get() == E->getRowIdx() && ColumnIdx.get() == E->getColumnIdx())
     return E;
 
   return getDerived().RebuildMatrixSubscriptExpr(
       Base.get(), RowIdx.get(), ColumnIdx.get(), E->getRBracketLoc());
 }
 
 template <typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformOMPArraySectionExpr(OMPArraySectionExpr *E) {
   ExprResult Base = getDerived().TransformExpr(E->getBase());
   if (Base.isInvalid())
     return ExprError();
 
   ExprResult LowerBound;
   if (E->getLowerBound()) {
     LowerBound = getDerived().TransformExpr(E->getLowerBound());
     if (LowerBound.isInvalid())
       return ExprError();
   }
 
   ExprResult Length;
   if (E->getLength()) {
     Length = getDerived().TransformExpr(E->getLength());
     if (Length.isInvalid())
       return ExprError();
   }
 
   ExprResult Stride;
   if (Expr *Str = E->getStride()) {
     Stride = getDerived().TransformExpr(Str);
     if (Stride.isInvalid())
       return ExprError();
   }
 
   if (!getDerived().AlwaysRebuild() && Base.get() == E->getBase() &&
       LowerBound.get() == E->getLowerBound() && Length.get() == E->getLength())
     return E;
 
   return getDerived().RebuildOMPArraySectionExpr(
       Base.get(), E->getBase()->getEndLoc(), LowerBound.get(),
       E->getColonLocFirst(), E->getColonLocSecond(), Length.get(), Stride.get(),
       E->getRBracketLoc());
 }
 
 template <typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformOMPArrayShapingExpr(OMPArrayShapingExpr *E) {
   ExprResult Base = getDerived().TransformExpr(E->getBase());
   if (Base.isInvalid())
     return ExprError();
 
   SmallVector<Expr *, 4> Dims;
   bool ErrorFound = false;
   for (Expr *Dim : E->getDimensions()) {
     ExprResult DimRes = getDerived().TransformExpr(Dim);
     if (DimRes.isInvalid()) {
       ErrorFound = true;
       continue;
     }
     Dims.push_back(DimRes.get());
   }
 
   if (ErrorFound)
     return ExprError();
   return getDerived().RebuildOMPArrayShapingExpr(Base.get(), E->getLParenLoc(),
                                                  E->getRParenLoc(), Dims,
                                                  E->getBracketsRanges());
 }
 
 template <typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformOMPIteratorExpr(OMPIteratorExpr *E) {
   unsigned NumIterators = E->numOfIterators();
   SmallVector<Sema::OMPIteratorData, 4> Data(NumIterators);
 
   bool ErrorFound = false;
   bool NeedToRebuild = getDerived().AlwaysRebuild();
   for (unsigned I = 0; I < NumIterators; ++I) {
     auto *D = cast<VarDecl>(E->getIteratorDecl(I));
     Data[I].DeclIdent = D->getIdentifier();
     Data[I].DeclIdentLoc = D->getLocation();
     if (D->getLocation() == D->getBeginLoc()) {
       assert(SemaRef.Context.hasSameType(D->getType(), SemaRef.Context.IntTy) &&
              "Implicit type must be int.");
     } else {
       TypeSourceInfo *TSI = getDerived().TransformType(D->getTypeSourceInfo());
       QualType DeclTy = getDerived().TransformType(D->getType());
       Data[I].Type = SemaRef.CreateParsedType(DeclTy, TSI);
     }
     OMPIteratorExpr::IteratorRange Range = E->getIteratorRange(I);
     ExprResult Begin = getDerived().TransformExpr(Range.Begin);
     ExprResult End = getDerived().TransformExpr(Range.End);
     ExprResult Step = getDerived().TransformExpr(Range.Step);
     ErrorFound = ErrorFound ||
                  !(!D->getTypeSourceInfo() || (Data[I].Type.getAsOpaquePtr() &&
                                                !Data[I].Type.get().isNull())) ||
                  Begin.isInvalid() || End.isInvalid() || Step.isInvalid();
     if (ErrorFound)
       continue;
     Data[I].Range.Begin = Begin.get();
     Data[I].Range.End = End.get();
     Data[I].Range.Step = Step.get();
     Data[I].AssignLoc = E->getAssignLoc(I);
     Data[I].ColonLoc = E->getColonLoc(I);
     Data[I].SecColonLoc = E->getSecondColonLoc(I);
     NeedToRebuild =
         NeedToRebuild ||
         (D->getTypeSourceInfo() && Data[I].Type.get().getTypePtrOrNull() !=
                                        D->getType().getTypePtrOrNull()) ||
         Range.Begin != Data[I].Range.Begin || Range.End != Data[I].Range.End ||
         Range.Step != Data[I].Range.Step;
   }
   if (ErrorFound)
     return ExprError();
   if (!NeedToRebuild)
     return E;
 
   ExprResult Res = getDerived().RebuildOMPIteratorExpr(
       E->getIteratorKwLoc(), E->getLParenLoc(), E->getRParenLoc(), Data);
   if (!Res.isUsable())
     return Res;
   auto *IE = cast<OMPIteratorExpr>(Res.get());
   for (unsigned I = 0; I < NumIterators; ++I)
     getDerived().transformedLocalDecl(E->getIteratorDecl(I),
                                       IE->getIteratorDecl(I));
   return Res;
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCallExpr(CallExpr *E) {
   // Transform the callee.
   ExprResult Callee = getDerived().TransformExpr(E->getCallee());
   if (Callee.isInvalid())
     return ExprError();
 
   // Transform arguments.
   bool ArgChanged = false;
   SmallVector<Expr*, 8> Args;
   if (getDerived().TransformExprs(E->getArgs(), E->getNumArgs(), true, Args,
                                   &ArgChanged))
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() &&
       Callee.get() == E->getCallee() &&
       !ArgChanged)
     return SemaRef.MaybeBindToTemporary(E);
 
   // FIXME: Wrong source location information for the '('.
   SourceLocation FakeLParenLoc
     = ((Expr *)Callee.get())->getSourceRange().getBegin();
 
   Sema::FPFeaturesStateRAII FPFeaturesState(getSema());
   if (E->hasStoredFPFeatures()) {
     FPOptionsOverride NewOverrides = E->getFPFeatures();
     getSema().CurFPFeatures =
         NewOverrides.applyOverrides(getSema().getLangOpts());
     getSema().FpPragmaStack.CurrentValue = NewOverrides;
   }
 
   return getDerived().RebuildCallExpr(Callee.get(), FakeLParenLoc,
                                       Args,
                                       E->getRParenLoc());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformMemberExpr(MemberExpr *E) {
   ExprResult Base = getDerived().TransformExpr(E->getBase());
   if (Base.isInvalid())
     return ExprError();
 
   NestedNameSpecifierLoc QualifierLoc;
   if (E->hasQualifier()) {
     QualifierLoc
       = getDerived().TransformNestedNameSpecifierLoc(E->getQualifierLoc());
 
     if (!QualifierLoc)
       return ExprError();
   }
   SourceLocation TemplateKWLoc = E->getTemplateKeywordLoc();
 
   ValueDecl *Member
     = cast_or_null<ValueDecl>(getDerived().TransformDecl(E->getMemberLoc(),
                                                          E->getMemberDecl()));
   if (!Member)
     return ExprError();
 
   NamedDecl *FoundDecl = E->getFoundDecl();
   if (FoundDecl == E->getMemberDecl()) {
     FoundDecl = Member;
   } else {
     FoundDecl = cast_or_null<NamedDecl>(
                    getDerived().TransformDecl(E->getMemberLoc(), FoundDecl));
     if (!FoundDecl)
       return ExprError();
   }
 
   if (!getDerived().AlwaysRebuild() &&
       Base.get() == E->getBase() &&
       QualifierLoc == E->getQualifierLoc() &&
       Member == E->getMemberDecl() &&
       FoundDecl == E->getFoundDecl() &&
       !E->hasExplicitTemplateArgs()) {
 
     // Skip for member expression of (this->f), rebuilt thisi->f is needed
     // for Openmp where the field need to be privatizized in the case.
     if (!(isa<CXXThisExpr>(E->getBase()) &&
           getSema().isOpenMPRebuildMemberExpr(cast<ValueDecl>(Member)))) {
       // Mark it referenced in the new context regardless.
       // FIXME: this is a bit instantiation-specific.
       SemaRef.MarkMemberReferenced(E);
       return E;
     }
   }
 
   TemplateArgumentListInfo TransArgs;
   if (E->hasExplicitTemplateArgs()) {
     TransArgs.setLAngleLoc(E->getLAngleLoc());
     TransArgs.setRAngleLoc(E->getRAngleLoc());
     if (getDerived().TransformTemplateArguments(E->getTemplateArgs(),
                                                 E->getNumTemplateArgs(),
                                                 TransArgs))
       return ExprError();
   }
 
   // FIXME: Bogus source location for the operator
   SourceLocation FakeOperatorLoc =
       SemaRef.getLocForEndOfToken(E->getBase()->getSourceRange().getEnd());
 
   // FIXME: to do this check properly, we will need to preserve the
   // first-qualifier-in-scope here, just in case we had a dependent
   // base (and therefore couldn't do the check) and a
   // nested-name-qualifier (and therefore could do the lookup).
   NamedDecl *FirstQualifierInScope = nullptr;
   DeclarationNameInfo MemberNameInfo = E->getMemberNameInfo();
   if (MemberNameInfo.getName()) {
     MemberNameInfo = getDerived().TransformDeclarationNameInfo(MemberNameInfo);
     if (!MemberNameInfo.getName())
       return ExprError();
   }
 
   return getDerived().RebuildMemberExpr(Base.get(), FakeOperatorLoc,
                                         E->isArrow(),
                                         QualifierLoc,
                                         TemplateKWLoc,
                                         MemberNameInfo,
                                         Member,
                                         FoundDecl,
                                         (E->hasExplicitTemplateArgs()
                                            ? &TransArgs : nullptr),
                                         FirstQualifierInScope);
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformBinaryOperator(BinaryOperator *E) {
   ExprResult LHS = getDerived().TransformExpr(E->getLHS());
   if (LHS.isInvalid())
     return ExprError();
 
   ExprResult RHS =
       getDerived().TransformInitializer(E->getRHS(), /*NotCopyInit=*/false);
   if (RHS.isInvalid())
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() &&
       LHS.get() == E->getLHS() &&
       RHS.get() == E->getRHS())
     return E;
 
   if (E->isCompoundAssignmentOp())
     // FPFeatures has already been established from trailing storage
     return getDerived().RebuildBinaryOperator(
         E->getOperatorLoc(), E->getOpcode(), LHS.get(), RHS.get());
   Sema::FPFeaturesStateRAII FPFeaturesState(getSema());
   FPOptionsOverride NewOverrides(E->getFPFeatures());
   getSema().CurFPFeatures =
       NewOverrides.applyOverrides(getSema().getLangOpts());
   getSema().FpPragmaStack.CurrentValue = NewOverrides;
   return getDerived().RebuildBinaryOperator(E->getOperatorLoc(), E->getOpcode(),
                                             LHS.get(), RHS.get());
 }
 
 template <typename Derived>
 ExprResult TreeTransform<Derived>::TransformCXXRewrittenBinaryOperator(
     CXXRewrittenBinaryOperator *E) {
   CXXRewrittenBinaryOperator::DecomposedForm Decomp = E->getDecomposedForm();
 
   ExprResult LHS = getDerived().TransformExpr(const_cast<Expr*>(Decomp.LHS));
   if (LHS.isInvalid())
     return ExprError();
 
   ExprResult RHS = getDerived().TransformExpr(const_cast<Expr*>(Decomp.RHS));
   if (RHS.isInvalid())
     return ExprError();
 
   // Extract the already-resolved callee declarations so that we can restrict
   // ourselves to using them as the unqualified lookup results when rebuilding.
   UnresolvedSet<2> UnqualLookups;
   bool ChangedAnyLookups = false;
   Expr *PossibleBinOps[] = {E->getSemanticForm(),
                             const_cast<Expr *>(Decomp.InnerBinOp)};
   for (Expr *PossibleBinOp : PossibleBinOps) {
     auto *Op = dyn_cast<CXXOperatorCallExpr>(PossibleBinOp->IgnoreImplicit());
     if (!Op)
       continue;
     auto *Callee = dyn_cast<DeclRefExpr>(Op->getCallee()->IgnoreImplicit());
     if (!Callee || isa<CXXMethodDecl>(Callee->getDecl()))
       continue;
 
     // Transform the callee in case we built a call to a local extern
     // declaration.
     NamedDecl *Found = cast_or_null<NamedDecl>(getDerived().TransformDecl(
         E->getOperatorLoc(), Callee->getFoundDecl()));
     if (!Found)
       return ExprError();
     if (Found != Callee->getFoundDecl())
       ChangedAnyLookups = true;
     UnqualLookups.addDecl(Found);
   }
 
   if (!getDerived().AlwaysRebuild() && !ChangedAnyLookups &&
       LHS.get() == Decomp.LHS && RHS.get() == Decomp.RHS) {
     // Mark all functions used in the rewrite as referenced. Note that when
     // a < b is rewritten to (a <=> b) < 0, both the <=> and the < might be
     // function calls, and/or there might be a user-defined conversion sequence
     // applied to the operands of the <.
     // FIXME: this is a bit instantiation-specific.
     const Expr *StopAt[] = {Decomp.LHS, Decomp.RHS};
     SemaRef.MarkDeclarationsReferencedInExpr(E, false, StopAt);
     return E;
   }
 
   return getDerived().RebuildCXXRewrittenBinaryOperator(
       E->getOperatorLoc(), Decomp.Opcode, UnqualLookups, LHS.get(), RHS.get());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCompoundAssignOperator(
                                                       CompoundAssignOperator *E) {
   Sema::FPFeaturesStateRAII FPFeaturesState(getSema());
   FPOptionsOverride NewOverrides(E->getFPFeatures());
   getSema().CurFPFeatures =
       NewOverrides.applyOverrides(getSema().getLangOpts());
   getSema().FpPragmaStack.CurrentValue = NewOverrides;
   return getDerived().TransformBinaryOperator(E);
 }
 
 template<typename Derived>
 ExprResult TreeTransform<Derived>::
 TransformBinaryConditionalOperator(BinaryConditionalOperator *e) {
   // Just rebuild the common and RHS expressions and see whether we
   // get any changes.
 
   ExprResult commonExpr = getDerived().TransformExpr(e->getCommon());
   if (commonExpr.isInvalid())
     return ExprError();
 
   ExprResult rhs = getDerived().TransformExpr(e->getFalseExpr());
   if (rhs.isInvalid())
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() &&
       commonExpr.get() == e->getCommon() &&
       rhs.get() == e->getFalseExpr())
     return e;
 
   return getDerived().RebuildConditionalOperator(commonExpr.get(),
                                                  e->getQuestionLoc(),
                                                  nullptr,
                                                  e->getColonLoc(),
                                                  rhs.get());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformConditionalOperator(ConditionalOperator *E) {
   ExprResult Cond = getDerived().TransformExpr(E->getCond());
   if (Cond.isInvalid())
     return ExprError();
 
   ExprResult LHS = getDerived().TransformExpr(E->getLHS());
   if (LHS.isInvalid())
     return ExprError();
 
   ExprResult RHS = getDerived().TransformExpr(E->getRHS());
   if (RHS.isInvalid())
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() &&
       Cond.get() == E->getCond() &&
       LHS.get() == E->getLHS() &&
       RHS.get() == E->getRHS())
     return E;
 
   return getDerived().RebuildConditionalOperator(Cond.get(),
                                                  E->getQuestionLoc(),
                                                  LHS.get(),
                                                  E->getColonLoc(),
                                                  RHS.get());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformImplicitCastExpr(ImplicitCastExpr *E) {
   // Implicit casts are eliminated during transformation, since they
   // will be recomputed by semantic analysis after transformation.
   return getDerived().TransformExpr(E->getSubExprAsWritten());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCStyleCastExpr(CStyleCastExpr *E) {
   TypeSourceInfo *Type = getDerived().TransformType(E->getTypeInfoAsWritten());
   if (!Type)
     return ExprError();
 
   ExprResult SubExpr
     = getDerived().TransformExpr(E->getSubExprAsWritten());
   if (SubExpr.isInvalid())
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() &&
       Type == E->getTypeInfoAsWritten() &&
       SubExpr.get() == E->getSubExpr())
     return E;
 
   return getDerived().RebuildCStyleCastExpr(E->getLParenLoc(),
                                             Type,
                                             E->getRParenLoc(),
                                             SubExpr.get());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCompoundLiteralExpr(CompoundLiteralExpr *E) {
   TypeSourceInfo *OldT = E->getTypeSourceInfo();
   TypeSourceInfo *NewT = getDerived().TransformType(OldT);
   if (!NewT)
     return ExprError();
 
   ExprResult Init = getDerived().TransformExpr(E->getInitializer());
   if (Init.isInvalid())
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() &&
       OldT == NewT &&
       Init.get() == E->getInitializer())
     return SemaRef.MaybeBindToTemporary(E);
 
   // Note: the expression type doesn't necessarily match the
   // type-as-written, but that's okay, because it should always be
   // derivable from the initializer.
 
   return getDerived().RebuildCompoundLiteralExpr(
       E->getLParenLoc(), NewT,
       /*FIXME:*/ E->getInitializer()->getEndLoc(), Init.get());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformExtVectorElementExpr(ExtVectorElementExpr *E) {
   ExprResult Base = getDerived().TransformExpr(E->getBase());
   if (Base.isInvalid())
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() &&
       Base.get() == E->getBase())
     return E;
 
   // FIXME: Bad source location
   SourceLocation FakeOperatorLoc =
       SemaRef.getLocForEndOfToken(E->getBase()->getEndLoc());
   return getDerived().RebuildExtVectorElementExpr(
       Base.get(), FakeOperatorLoc, E->isArrow(), E->getAccessorLoc(),
       E->getAccessor());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformInitListExpr(InitListExpr *E) {
   if (InitListExpr *Syntactic = E->getSyntacticForm())
     E = Syntactic;
 
   bool InitChanged = false;
 
   EnterExpressionEvaluationContext Context(
       getSema(), EnterExpressionEvaluationContext::InitList);
 
   SmallVector<Expr*, 4> Inits;
   if (getDerived().TransformExprs(E->getInits(), E->getNumInits(), false,
                                   Inits, &InitChanged))
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() && !InitChanged) {
     // FIXME: Attempt to reuse the existing syntactic form of the InitListExpr
     // in some cases. We can't reuse it in general, because the syntactic and
     // semantic forms are linked, and we can't know that semantic form will
     // match even if the syntactic form does.
   }
 
   return getDerived().RebuildInitList(E->getLBraceLoc(), Inits,
                                       E->getRBraceLoc());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformDesignatedInitExpr(DesignatedInitExpr *E) {
   Designation Desig;
 
   // transform the initializer value
   ExprResult Init = getDerived().TransformExpr(E->getInit());
   if (Init.isInvalid())
     return ExprError();
 
   // transform the designators.
   SmallVector<Expr*, 4> ArrayExprs;
   bool ExprChanged = false;
   for (const DesignatedInitExpr::Designator &D : E->designators()) {
     if (D.isFieldDesignator()) {
       Desig.AddDesignator(Designator::CreateFieldDesignator(
           D.getFieldName(), D.getDotLoc(), D.getFieldLoc()));
       if (D.getFieldDecl()) {
         FieldDecl *Field = cast_or_null<FieldDecl>(
             getDerived().TransformDecl(D.getFieldLoc(), D.getFieldDecl()));
         if (Field != D.getFieldDecl())
           // Rebuild the expression when the transformed FieldDecl is
           // different to the already assigned FieldDecl.
           ExprChanged = true;
       } else {
         // Ensure that the designator expression is rebuilt when there isn't
         // a resolved FieldDecl in the designator as we don't want to assign
         // a FieldDecl to a pattern designator that will be instantiated again.
         ExprChanged = true;
       }
       continue;
     }
 
     if (D.isArrayDesignator()) {
       ExprResult Index = getDerived().TransformExpr(E->getArrayIndex(D));
       if (Index.isInvalid())
         return ExprError();
 
       Desig.AddDesignator(
           Designator::CreateArrayDesignator(Index.get(), D.getLBracketLoc()));
 
       ExprChanged = ExprChanged || Init.get() != E->getArrayIndex(D);
       ArrayExprs.push_back(Index.get());
       continue;
     }
 
     assert(D.isArrayRangeDesignator() && "New kind of designator?");
     ExprResult Start
       = getDerived().TransformExpr(E->getArrayRangeStart(D));
     if (Start.isInvalid())
       return ExprError();
 
     ExprResult End = getDerived().TransformExpr(E->getArrayRangeEnd(D));
     if (End.isInvalid())
       return ExprError();
 
     Desig.AddDesignator(Designator::CreateArrayRangeDesignator(
         Start.get(), End.get(), D.getLBracketLoc(), D.getEllipsisLoc()));
 
     ExprChanged = ExprChanged || Start.get() != E->getArrayRangeStart(D) ||
                   End.get() != E->getArrayRangeEnd(D);
 
     ArrayExprs.push_back(Start.get());
     ArrayExprs.push_back(End.get());
   }
 
   if (!getDerived().AlwaysRebuild() &&
       Init.get() == E->getInit() &&
       !ExprChanged)
     return E;
 
   return getDerived().RebuildDesignatedInitExpr(Desig, ArrayExprs,
                                                 E->getEqualOrColonLoc(),
                                                 E->usesGNUSyntax(), Init.get());
 }
 
 // Seems that if TransformInitListExpr() only works on the syntactic form of an
 // InitListExpr, then a DesignatedInitUpdateExpr is not encountered.
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformDesignatedInitUpdateExpr(
     DesignatedInitUpdateExpr *E) {
   llvm_unreachable("Unexpected DesignatedInitUpdateExpr in syntactic form of "
                    "initializer");
   return ExprError();
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformNoInitExpr(
     NoInitExpr *E) {
   llvm_unreachable("Unexpected NoInitExpr in syntactic form of initializer");
   return ExprError();
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformArrayInitLoopExpr(ArrayInitLoopExpr *E) {
   llvm_unreachable("Unexpected ArrayInitLoopExpr outside of initializer");
   return ExprError();
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformArrayInitIndexExpr(ArrayInitIndexExpr *E) {
   llvm_unreachable("Unexpected ArrayInitIndexExpr outside of initializer");
   return ExprError();
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformImplicitValueInitExpr(
                                                      ImplicitValueInitExpr *E) {
   TemporaryBase Rebase(*this, E->getBeginLoc(), DeclarationName());
 
   // FIXME: Will we ever have proper type location here? Will we actually
   // need to transform the type?
   QualType T = getDerived().TransformType(E->getType());
   if (T.isNull())
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() &&
       T == E->getType())
     return E;
 
   return getDerived().RebuildImplicitValueInitExpr(T);
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformVAArgExpr(VAArgExpr *E) {
   TypeSourceInfo *TInfo = getDerived().TransformType(E->getWrittenTypeInfo());
   if (!TInfo)
     return ExprError();
 
   ExprResult SubExpr = getDerived().TransformExpr(E->getSubExpr());
   if (SubExpr.isInvalid())
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() &&
       TInfo == E->getWrittenTypeInfo() &&
       SubExpr.get() == E->getSubExpr())
     return E;
 
   return getDerived().RebuildVAArgExpr(E->getBuiltinLoc(), SubExpr.get(),
                                        TInfo, E->getRParenLoc());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformParenListExpr(ParenListExpr *E) {
   bool ArgumentChanged = false;
   SmallVector<Expr*, 4> Inits;
   if (TransformExprs(E->getExprs(), E->getNumExprs(), true, Inits,
                      &ArgumentChanged))
     return ExprError();
 
   return getDerived().RebuildParenListExpr(E->getLParenLoc(),
                                            Inits,
                                            E->getRParenLoc());
 }
 
 /// Transform an address-of-label expression.
 ///
 /// By default, the transformation of an address-of-label expression always
 /// rebuilds the expression, so that the label identifier can be resolved to
 /// the corresponding label statement by semantic analysis.
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformAddrLabelExpr(AddrLabelExpr *E) {
   Decl *LD = getDerived().TransformDecl(E->getLabel()->getLocation(),
                                         E->getLabel());
   if (!LD)
     return ExprError();
 
   return getDerived().RebuildAddrLabelExpr(E->getAmpAmpLoc(), E->getLabelLoc(),
                                            cast<LabelDecl>(LD));
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformStmtExpr(StmtExpr *E) {
   SemaRef.ActOnStartStmtExpr();
   StmtResult SubStmt
     = getDerived().TransformCompoundStmt(E->getSubStmt(), true);
   if (SubStmt.isInvalid()) {
     SemaRef.ActOnStmtExprError();
     return ExprError();
   }
 
   unsigned OldDepth = E->getTemplateDepth();
   unsigned NewDepth = getDerived().TransformTemplateDepth(OldDepth);
 
   if (!getDerived().AlwaysRebuild() && OldDepth == NewDepth &&
       SubStmt.get() == E->getSubStmt()) {
     // Calling this an 'error' is unintuitive, but it does the right thing.
     SemaRef.ActOnStmtExprError();
     return SemaRef.MaybeBindToTemporary(E);
   }
 
   return getDerived().RebuildStmtExpr(E->getLParenLoc(), SubStmt.get(),
                                       E->getRParenLoc(), NewDepth);
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformChooseExpr(ChooseExpr *E) {
   ExprResult Cond = getDerived().TransformExpr(E->getCond());
   if (Cond.isInvalid())
     return ExprError();
 
   ExprResult LHS = getDerived().TransformExpr(E->getLHS());
   if (LHS.isInvalid())
     return ExprError();
 
   ExprResult RHS = getDerived().TransformExpr(E->getRHS());
   if (RHS.isInvalid())
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() &&
       Cond.get() == E->getCond() &&
       LHS.get() == E->getLHS() &&
       RHS.get() == E->getRHS())
     return E;
 
   return getDerived().RebuildChooseExpr(E->getBuiltinLoc(),
                                         Cond.get(), LHS.get(), RHS.get(),
                                         E->getRParenLoc());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformGNUNullExpr(GNUNullExpr *E) {
   return E;
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXOperatorCallExpr(CXXOperatorCallExpr *E) {
   switch (E->getOperator()) {
   case OO_New:
   case OO_Delete:
   case OO_Array_New:
   case OO_Array_Delete:
     llvm_unreachable("new and delete operators cannot use CXXOperatorCallExpr");
 
   case OO_Subscript:
   case OO_Call: {
     // This is a call to an object's operator().
     assert(E->getNumArgs() >= 1 && "Object call is missing arguments");
 
     // Transform the object itself.
     ExprResult Object = getDerived().TransformExpr(E->getArg(0));
     if (Object.isInvalid())
       return ExprError();
 
     // FIXME: Poor location information
     SourceLocation FakeLParenLoc = SemaRef.getLocForEndOfToken(
         static_cast<Expr *>(Object.get())->getEndLoc());
 
     // Transform the call arguments.
     SmallVector<Expr*, 8> Args;
     if (getDerived().TransformExprs(E->getArgs() + 1, E->getNumArgs() - 1, true,
                                     Args))
       return ExprError();
 
     if (E->getOperator() == OO_Subscript)
       return getDerived().RebuildCxxSubscriptExpr(Object.get(), FakeLParenLoc,
                                                   Args, E->getEndLoc());
 
     return getDerived().RebuildCallExpr(Object.get(), FakeLParenLoc, Args,
                                         E->getEndLoc());
   }
 
 #define OVERLOADED_OPERATOR(Name, Spelling, Token, Unary, Binary, MemberOnly)  \
   case OO_##Name:                                                              \
     break;
 
 #define OVERLOADED_OPERATOR_MULTI(Name,Spelling,Unary,Binary,MemberOnly)
 #include "clang/Basic/OperatorKinds.def"
 
   case OO_Conditional:
     llvm_unreachable("conditional operator is not actually overloadable");
 
   case OO_None:
   case NUM_OVERLOADED_OPERATORS:
     llvm_unreachable("not an overloaded operator?");
   }
 
   ExprResult First;
   if (E->getOperator() == OO_Amp)
     First = getDerived().TransformAddressOfOperand(E->getArg(0));
   else
     First = getDerived().TransformExpr(E->getArg(0));
   if (First.isInvalid())
     return ExprError();
 
   ExprResult Second;
   if (E->getNumArgs() == 2) {
     Second =
         getDerived().TransformInitializer(E->getArg(1), /*NotCopyInit=*/false);
     if (Second.isInvalid())
       return ExprError();
   }
 
   Sema::FPFeaturesStateRAII FPFeaturesState(getSema());
   FPOptionsOverride NewOverrides(E->getFPFeatures());
   getSema().CurFPFeatures =
       NewOverrides.applyOverrides(getSema().getLangOpts());
   getSema().FpPragmaStack.CurrentValue = NewOverrides;
 
   Expr *Callee = E->getCallee();
   if (UnresolvedLookupExpr *ULE = dyn_cast<UnresolvedLookupExpr>(Callee)) {
     LookupResult R(SemaRef, ULE->getName(), ULE->getNameLoc(),
                    Sema::LookupOrdinaryName);
     if (getDerived().TransformOverloadExprDecls(ULE, ULE->requiresADL(), R))
       return ExprError();
 
     return getDerived().RebuildCXXOperatorCallExpr(
         E->getOperator(), E->getOperatorLoc(), Callee->getBeginLoc(),
         ULE->requiresADL(), R.asUnresolvedSet(), First.get(), Second.get());
   }
 
   UnresolvedSet<1> Functions;
   if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Callee))
     Callee = ICE->getSubExprAsWritten();
   NamedDecl *DR = cast<DeclRefExpr>(Callee)->getDecl();
   ValueDecl *VD = cast_or_null<ValueDecl>(
       getDerived().TransformDecl(DR->getLocation(), DR));
   if (!VD)
     return ExprError();
 
   if (!isa<CXXMethodDecl>(VD))
     Functions.addDecl(VD);
 
   return getDerived().RebuildCXXOperatorCallExpr(
       E->getOperator(), E->getOperatorLoc(), Callee->getBeginLoc(),
       /*RequiresADL=*/false, Functions, First.get(), Second.get());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXMemberCallExpr(CXXMemberCallExpr *E) {
   return getDerived().TransformCallExpr(E);
 }
 
 template <typename Derived>
 ExprResult TreeTransform<Derived>::TransformSourceLocExpr(SourceLocExpr *E) {
   bool NeedRebuildFunc = E->getIdentKind() == SourceLocExpr::Function &&
                          getSema().CurContext != E->getParentContext();
 
   if (!getDerived().AlwaysRebuild() && !NeedRebuildFunc)
     return E;
 
   return getDerived().RebuildSourceLocExpr(E->getIdentKind(), E->getType(),
                                            E->getBeginLoc(), E->getEndLoc(),
                                            getSema().CurContext);
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCUDAKernelCallExpr(CUDAKernelCallExpr *E) {
   // Transform the callee.
   ExprResult Callee = getDerived().TransformExpr(E->getCallee());
   if (Callee.isInvalid())
     return ExprError();
 
   // Transform exec config.
   ExprResult EC = getDerived().TransformCallExpr(E->getConfig());
   if (EC.isInvalid())
     return ExprError();
 
   // Transform arguments.
   bool ArgChanged = false;
   SmallVector<Expr*, 8> Args;
   if (getDerived().TransformExprs(E->getArgs(), E->getNumArgs(), true, Args,
                                   &ArgChanged))
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() &&
       Callee.get() == E->getCallee() &&
       !ArgChanged)
     return SemaRef.MaybeBindToTemporary(E);
 
   // FIXME: Wrong source location information for the '('.
   SourceLocation FakeLParenLoc
     = ((Expr *)Callee.get())->getSourceRange().getBegin();
   return getDerived().RebuildCallExpr(Callee.get(), FakeLParenLoc,
                                       Args,
                                       E->getRParenLoc(), EC.get());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXNamedCastExpr(CXXNamedCastExpr *E) {
   TypeSourceInfo *Type = getDerived().TransformType(E->getTypeInfoAsWritten());
   if (!Type)
     return ExprError();
 
   ExprResult SubExpr
     = getDerived().TransformExpr(E->getSubExprAsWritten());
   if (SubExpr.isInvalid())
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() &&
       Type == E->getTypeInfoAsWritten() &&
       SubExpr.get() == E->getSubExpr())
     return E;
   return getDerived().RebuildCXXNamedCastExpr(
       E->getOperatorLoc(), E->getStmtClass(), E->getAngleBrackets().getBegin(),
       Type, E->getAngleBrackets().getEnd(),
       // FIXME. this should be '(' location
       E->getAngleBrackets().getEnd(), SubExpr.get(), E->getRParenLoc());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformBuiltinBitCastExpr(BuiltinBitCastExpr *BCE) {
   TypeSourceInfo *TSI =
       getDerived().TransformType(BCE->getTypeInfoAsWritten());
   if (!TSI)
     return ExprError();
 
   ExprResult Sub = getDerived().TransformExpr(BCE->getSubExpr());
   if (Sub.isInvalid())
     return ExprError();
 
   return getDerived().RebuildBuiltinBitCastExpr(BCE->getBeginLoc(), TSI,
                                                 Sub.get(), BCE->getEndLoc());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXStaticCastExpr(CXXStaticCastExpr *E) {
   return getDerived().TransformCXXNamedCastExpr(E);
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXDynamicCastExpr(CXXDynamicCastExpr *E) {
   return getDerived().TransformCXXNamedCastExpr(E);
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXReinterpretCastExpr(
                                                       CXXReinterpretCastExpr *E) {
   return getDerived().TransformCXXNamedCastExpr(E);
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXConstCastExpr(CXXConstCastExpr *E) {
   return getDerived().TransformCXXNamedCastExpr(E);
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXAddrspaceCastExpr(CXXAddrspaceCastExpr *E) {
   return getDerived().TransformCXXNamedCastExpr(E);
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXFunctionalCastExpr(
                                                      CXXFunctionalCastExpr *E) {
   TypeSourceInfo *Type =
       getDerived().TransformTypeWithDeducedTST(E->getTypeInfoAsWritten());
   if (!Type)
     return ExprError();
 
   ExprResult SubExpr
     = getDerived().TransformExpr(E->getSubExprAsWritten());
   if (SubExpr.isInvalid())
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() &&
       Type == E->getTypeInfoAsWritten() &&
       SubExpr.get() == E->getSubExpr())
     return E;
 
   return getDerived().RebuildCXXFunctionalCastExpr(Type,
                                                    E->getLParenLoc(),
                                                    SubExpr.get(),
                                                    E->getRParenLoc(),
                                                    E->isListInitialization());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXTypeidExpr(CXXTypeidExpr *E) {
   if (E->isTypeOperand()) {
     TypeSourceInfo *TInfo
       = getDerived().TransformType(E->getTypeOperandSourceInfo());
     if (!TInfo)
       return ExprError();
 
     if (!getDerived().AlwaysRebuild() &&
         TInfo == E->getTypeOperandSourceInfo())
       return E;
 
     return getDerived().RebuildCXXTypeidExpr(E->getType(), E->getBeginLoc(),
                                              TInfo, E->getEndLoc());
   }
 
   // Typeid's operand is an unevaluated context, unless it's a polymorphic
   // type.  We must not unilaterally enter unevaluated context here, as then
   // semantic processing can re-transform an already transformed operand.
   Expr *Op = E->getExprOperand();
   auto EvalCtx = Sema::ExpressionEvaluationContext::Unevaluated;
   if (E->isGLValue())
     if (auto *RecordT = Op->getType()->getAs<RecordType>())
       if (cast<CXXRecordDecl>(RecordT->getDecl())->isPolymorphic())
         EvalCtx = SemaRef.ExprEvalContexts.back().Context;
 
   EnterExpressionEvaluationContext Unevaluated(SemaRef, EvalCtx,
                                                Sema::ReuseLambdaContextDecl);
 
   ExprResult SubExpr = getDerived().TransformExpr(Op);
   if (SubExpr.isInvalid())
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() &&
       SubExpr.get() == E->getExprOperand())
     return E;
 
   return getDerived().RebuildCXXTypeidExpr(E->getType(), E->getBeginLoc(),
                                            SubExpr.get(), E->getEndLoc());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXUuidofExpr(CXXUuidofExpr *E) {
   if (E->isTypeOperand()) {
     TypeSourceInfo *TInfo
       = getDerived().TransformType(E->getTypeOperandSourceInfo());
     if (!TInfo)
       return ExprError();
 
     if (!getDerived().AlwaysRebuild() &&
         TInfo == E->getTypeOperandSourceInfo())
       return E;
 
     return getDerived().RebuildCXXUuidofExpr(E->getType(), E->getBeginLoc(),
                                              TInfo, E->getEndLoc());
   }
 
   EnterExpressionEvaluationContext Unevaluated(
       SemaRef, Sema::ExpressionEvaluationContext::Unevaluated);
 
   ExprResult SubExpr = getDerived().TransformExpr(E->getExprOperand());
   if (SubExpr.isInvalid())
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() &&
       SubExpr.get() == E->getExprOperand())
     return E;
 
   return getDerived().RebuildCXXUuidofExpr(E->getType(), E->getBeginLoc(),
                                            SubExpr.get(), E->getEndLoc());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXBoolLiteralExpr(CXXBoolLiteralExpr *E) {
   return E;
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXNullPtrLiteralExpr(
                                                      CXXNullPtrLiteralExpr *E) {
   return E;
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXThisExpr(CXXThisExpr *E) {
-  QualType T = getSema().getCurrentThisType();
+
+  // In lambdas, the qualifiers of the type depends of where in
+  // the call operator `this` appear, and we do not have a good way to
+  // rebuild this information, so we transform the type.
+  //
+  // In other contexts, the type of `this` may be overrided
+  // for type deduction, so we need to recompute it.
+  QualType T = getSema().getCurLambda() ?
+                   getDerived().TransformType(E->getType())
+                 : getSema().getCurrentThisType();
 
   if (!getDerived().AlwaysRebuild() && T == E->getType()) {
     // Mark it referenced in the new context regardless.
     // FIXME: this is a bit instantiation-specific.
     getSema().MarkThisReferenced(E);
     return E;
   }
 
   return getDerived().RebuildCXXThisExpr(E->getBeginLoc(), T, E->isImplicit());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXThrowExpr(CXXThrowExpr *E) {
   ExprResult SubExpr = getDerived().TransformExpr(E->getSubExpr());
   if (SubExpr.isInvalid())
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() &&
       SubExpr.get() == E->getSubExpr())
     return E;
 
   return getDerived().RebuildCXXThrowExpr(E->getThrowLoc(), SubExpr.get(),
                                           E->isThrownVariableInScope());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXDefaultArgExpr(CXXDefaultArgExpr *E) {
   ParmVarDecl *Param = cast_or_null<ParmVarDecl>(
       getDerived().TransformDecl(E->getBeginLoc(), E->getParam()));
   if (!Param)
     return ExprError();
 
   ExprResult InitRes;
   if (E->hasRewrittenInit()) {
     InitRes = getDerived().TransformExpr(E->getRewrittenExpr());
     if (InitRes.isInvalid())
       return ExprError();
   }
 
   if (!getDerived().AlwaysRebuild() && Param == E->getParam() &&
       E->getUsedContext() == SemaRef.CurContext &&
       InitRes.get() == E->getRewrittenExpr())
     return E;
 
   return getDerived().RebuildCXXDefaultArgExpr(E->getUsedLocation(), Param,
                                                InitRes.get());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXDefaultInitExpr(CXXDefaultInitExpr *E) {
   FieldDecl *Field = cast_or_null<FieldDecl>(
       getDerived().TransformDecl(E->getBeginLoc(), E->getField()));
   if (!Field)
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() && Field == E->getField() &&
       E->getUsedContext() == SemaRef.CurContext)
     return E;
 
   return getDerived().RebuildCXXDefaultInitExpr(E->getExprLoc(), Field);
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXScalarValueInitExpr(
                                                     CXXScalarValueInitExpr *E) {
   TypeSourceInfo *T = getDerived().TransformType(E->getTypeSourceInfo());
   if (!T)
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() &&
       T == E->getTypeSourceInfo())
     return E;
 
   return getDerived().RebuildCXXScalarValueInitExpr(T,
                                           /*FIXME:*/T->getTypeLoc().getEndLoc(),
                                                     E->getRParenLoc());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXNewExpr(CXXNewExpr *E) {
   // Transform the type that we're allocating
   TypeSourceInfo *AllocTypeInfo =
       getDerived().TransformTypeWithDeducedTST(E->getAllocatedTypeSourceInfo());
   if (!AllocTypeInfo)
     return ExprError();
 
   // Transform the size of the array we're allocating (if any).
   std::optional<Expr *> ArraySize;
   if (E->isArray()) {
     ExprResult NewArraySize;
     if (std::optional<Expr *> OldArraySize = E->getArraySize()) {
       NewArraySize = getDerived().TransformExpr(*OldArraySize);
       if (NewArraySize.isInvalid())
         return ExprError();
     }
     ArraySize = NewArraySize.get();
   }
 
   // Transform the placement arguments (if any).
   bool ArgumentChanged = false;
   SmallVector<Expr*, 8> PlacementArgs;
   if (getDerived().TransformExprs(E->getPlacementArgs(),
                                   E->getNumPlacementArgs(), true,
                                   PlacementArgs, &ArgumentChanged))
     return ExprError();
 
   // Transform the initializer (if any).
   Expr *OldInit = E->getInitializer();
   ExprResult NewInit;
   if (OldInit)
     NewInit = getDerived().TransformInitializer(OldInit, true);
   if (NewInit.isInvalid())
     return ExprError();
 
   // Transform new operator and delete operator.
   FunctionDecl *OperatorNew = nullptr;
   if (E->getOperatorNew()) {
     OperatorNew = cast_or_null<FunctionDecl>(
         getDerived().TransformDecl(E->getBeginLoc(), E->getOperatorNew()));
     if (!OperatorNew)
       return ExprError();
   }
 
   FunctionDecl *OperatorDelete = nullptr;
   if (E->getOperatorDelete()) {
     OperatorDelete = cast_or_null<FunctionDecl>(
         getDerived().TransformDecl(E->getBeginLoc(), E->getOperatorDelete()));
     if (!OperatorDelete)
       return ExprError();
   }
 
   if (!getDerived().AlwaysRebuild() &&
       AllocTypeInfo == E->getAllocatedTypeSourceInfo() &&
       ArraySize == E->getArraySize() &&
       NewInit.get() == OldInit &&
       OperatorNew == E->getOperatorNew() &&
       OperatorDelete == E->getOperatorDelete() &&
       !ArgumentChanged) {
     // Mark any declarations we need as referenced.
     // FIXME: instantiation-specific.
     if (OperatorNew)
       SemaRef.MarkFunctionReferenced(E->getBeginLoc(), OperatorNew);
     if (OperatorDelete)
       SemaRef.MarkFunctionReferenced(E->getBeginLoc(), OperatorDelete);
 
     if (E->isArray() && !E->getAllocatedType()->isDependentType()) {
       QualType ElementType
         = SemaRef.Context.getBaseElementType(E->getAllocatedType());
       if (const RecordType *RecordT = ElementType->getAs<RecordType>()) {
         CXXRecordDecl *Record = cast<CXXRecordDecl>(RecordT->getDecl());
         if (CXXDestructorDecl *Destructor = SemaRef.LookupDestructor(Record)) {
           SemaRef.MarkFunctionReferenced(E->getBeginLoc(), Destructor);
         }
       }
     }
 
     return E;
   }
 
   QualType AllocType = AllocTypeInfo->getType();
   if (!ArraySize) {
     // If no array size was specified, but the new expression was
     // instantiated with an array type (e.g., "new T" where T is
     // instantiated with "int[4]"), extract the outer bound from the
     // array type as our array size. We do this with constant and
     // dependently-sized array types.
     const ArrayType *ArrayT = SemaRef.Context.getAsArrayType(AllocType);
     if (!ArrayT) {
       // Do nothing
     } else if (const ConstantArrayType *ConsArrayT
                                      = dyn_cast<ConstantArrayType>(ArrayT)) {
       ArraySize = IntegerLiteral::Create(SemaRef.Context, ConsArrayT->getSize(),
                                          SemaRef.Context.getSizeType(),
                                          /*FIXME:*/ E->getBeginLoc());
       AllocType = ConsArrayT->getElementType();
     } else if (const DependentSizedArrayType *DepArrayT
                               = dyn_cast<DependentSizedArrayType>(ArrayT)) {
       if (DepArrayT->getSizeExpr()) {
         ArraySize = DepArrayT->getSizeExpr();
         AllocType = DepArrayT->getElementType();
       }
     }
   }
 
   return getDerived().RebuildCXXNewExpr(
       E->getBeginLoc(), E->isGlobalNew(),
       /*FIXME:*/ E->getBeginLoc(), PlacementArgs,
       /*FIXME:*/ E->getBeginLoc(), E->getTypeIdParens(), AllocType,
       AllocTypeInfo, ArraySize, E->getDirectInitRange(), NewInit.get());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXDeleteExpr(CXXDeleteExpr *E) {
   ExprResult Operand = getDerived().TransformExpr(E->getArgument());
   if (Operand.isInvalid())
     return ExprError();
 
   // Transform the delete operator, if known.
   FunctionDecl *OperatorDelete = nullptr;
   if (E->getOperatorDelete()) {
     OperatorDelete = cast_or_null<FunctionDecl>(
         getDerived().TransformDecl(E->getBeginLoc(), E->getOperatorDelete()));
     if (!OperatorDelete)
       return ExprError();
   }
 
   if (!getDerived().AlwaysRebuild() &&
       Operand.get() == E->getArgument() &&
       OperatorDelete == E->getOperatorDelete()) {
     // Mark any declarations we need as referenced.
     // FIXME: instantiation-specific.
     if (OperatorDelete)
       SemaRef.MarkFunctionReferenced(E->getBeginLoc(), OperatorDelete);
 
     if (!E->getArgument()->isTypeDependent()) {
       QualType Destroyed = SemaRef.Context.getBaseElementType(
                                                          E->getDestroyedType());
       if (const RecordType *DestroyedRec = Destroyed->getAs<RecordType>()) {
         CXXRecordDecl *Record = cast<CXXRecordDecl>(DestroyedRec->getDecl());
         SemaRef.MarkFunctionReferenced(E->getBeginLoc(),
                                        SemaRef.LookupDestructor(Record));
       }
     }
 
     return E;
   }
 
   return getDerived().RebuildCXXDeleteExpr(
       E->getBeginLoc(), E->isGlobalDelete(), E->isArrayForm(), Operand.get());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXPseudoDestructorExpr(
                                                      CXXPseudoDestructorExpr *E) {
   ExprResult Base = getDerived().TransformExpr(E->getBase());
   if (Base.isInvalid())
     return ExprError();
 
   ParsedType ObjectTypePtr;
   bool MayBePseudoDestructor = false;
   Base = SemaRef.ActOnStartCXXMemberReference(nullptr, Base.get(),
                                               E->getOperatorLoc(),
                                         E->isArrow()? tok::arrow : tok::period,
                                               ObjectTypePtr,
                                               MayBePseudoDestructor);
   if (Base.isInvalid())
     return ExprError();
 
   QualType ObjectType = ObjectTypePtr.get();
   NestedNameSpecifierLoc QualifierLoc = E->getQualifierLoc();
   if (QualifierLoc) {
     QualifierLoc
       = getDerived().TransformNestedNameSpecifierLoc(QualifierLoc, ObjectType);
     if (!QualifierLoc)
       return ExprError();
   }
   CXXScopeSpec SS;
   SS.Adopt(QualifierLoc);
 
   PseudoDestructorTypeStorage Destroyed;
   if (E->getDestroyedTypeInfo()) {
     TypeSourceInfo *DestroyedTypeInfo
       = getDerived().TransformTypeInObjectScope(E->getDestroyedTypeInfo(),
                                                 ObjectType, nullptr, SS);
     if (!DestroyedTypeInfo)
       return ExprError();
     Destroyed = DestroyedTypeInfo;
   } else if (!ObjectType.isNull() && ObjectType->isDependentType()) {
     // We aren't likely to be able to resolve the identifier down to a type
     // now anyway, so just retain the identifier.
     Destroyed = PseudoDestructorTypeStorage(E->getDestroyedTypeIdentifier(),
                                             E->getDestroyedTypeLoc());
   } else {
     // Look for a destructor known with the given name.
     ParsedType T = SemaRef.getDestructorName(E->getTildeLoc(),
                                               *E->getDestroyedTypeIdentifier(),
                                                 E->getDestroyedTypeLoc(),
                                                 /*Scope=*/nullptr,
                                                 SS, ObjectTypePtr,
                                                 false);
     if (!T)
       return ExprError();
 
     Destroyed
       = SemaRef.Context.getTrivialTypeSourceInfo(SemaRef.GetTypeFromParser(T),
                                                  E->getDestroyedTypeLoc());
   }
 
   TypeSourceInfo *ScopeTypeInfo = nullptr;
   if (E->getScopeTypeInfo()) {
     CXXScopeSpec EmptySS;
     ScopeTypeInfo = getDerived().TransformTypeInObjectScope(
                       E->getScopeTypeInfo(), ObjectType, nullptr, EmptySS);
     if (!ScopeTypeInfo)
       return ExprError();
   }
 
   return getDerived().RebuildCXXPseudoDestructorExpr(Base.get(),
                                                      E->getOperatorLoc(),
                                                      E->isArrow(),
                                                      SS,
                                                      ScopeTypeInfo,
                                                      E->getColonColonLoc(),
                                                      E->getTildeLoc(),
                                                      Destroyed);
 }
 
 template <typename Derived>
 bool TreeTransform<Derived>::TransformOverloadExprDecls(OverloadExpr *Old,
                                                         bool RequiresADL,
                                                         LookupResult &R) {
   // Transform all the decls.
   bool AllEmptyPacks = true;
   for (auto *OldD : Old->decls()) {
     Decl *InstD = getDerived().TransformDecl(Old->getNameLoc(), OldD);
     if (!InstD) {
       // Silently ignore these if a UsingShadowDecl instantiated to nothing.
       // This can happen because of dependent hiding.
       if (isa<UsingShadowDecl>(OldD))
         continue;
       else {
         R.clear();
         return true;
       }
     }
 
     // Expand using pack declarations.
     NamedDecl *SingleDecl = cast<NamedDecl>(InstD);
     ArrayRef<NamedDecl*> Decls = SingleDecl;
     if (auto *UPD = dyn_cast<UsingPackDecl>(InstD))
       Decls = UPD->expansions();
 
     // Expand using declarations.
     for (auto *D : Decls) {
       if (auto *UD = dyn_cast<UsingDecl>(D)) {
         for (auto *SD : UD->shadows())
           R.addDecl(SD);
       } else {
         R.addDecl(D);
       }
     }
 
     AllEmptyPacks &= Decls.empty();
   };
 
   // C++ [temp.res]/8.4.2:
   //   The program is ill-formed, no diagnostic required, if [...] lookup for
   //   a name in the template definition found a using-declaration, but the
   //   lookup in the corresponding scope in the instantiation odoes not find
   //   any declarations because the using-declaration was a pack expansion and
   //   the corresponding pack is empty
   if (AllEmptyPacks && !RequiresADL) {
     getSema().Diag(Old->getNameLoc(), diag::err_using_pack_expansion_empty)
         << isa<UnresolvedMemberExpr>(Old) << Old->getName();
     return true;
   }
 
   // Resolve a kind, but don't do any further analysis.  If it's
   // ambiguous, the callee needs to deal with it.
   R.resolveKind();
   return false;
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformUnresolvedLookupExpr(
                                                   UnresolvedLookupExpr *Old) {
   LookupResult R(SemaRef, Old->getName(), Old->getNameLoc(),
                  Sema::LookupOrdinaryName);
 
   // Transform the declaration set.
   if (TransformOverloadExprDecls(Old, Old->requiresADL(), R))
     return ExprError();
 
   // Rebuild the nested-name qualifier, if present.
   CXXScopeSpec SS;
   if (Old->getQualifierLoc()) {
     NestedNameSpecifierLoc QualifierLoc
       = getDerived().TransformNestedNameSpecifierLoc(Old->getQualifierLoc());
     if (!QualifierLoc)
       return ExprError();
 
     SS.Adopt(QualifierLoc);
   }
 
   if (Old->getNamingClass()) {
     CXXRecordDecl *NamingClass
       = cast_or_null<CXXRecordDecl>(getDerived().TransformDecl(
                                                             Old->getNameLoc(),
                                                         Old->getNamingClass()));
     if (!NamingClass) {
       R.clear();
       return ExprError();
     }
 
     R.setNamingClass(NamingClass);
   }
 
   SourceLocation TemplateKWLoc = Old->getTemplateKeywordLoc();
 
   // If we have neither explicit template arguments, nor the template keyword,
   // it's a normal declaration name or member reference.
   if (!Old->hasExplicitTemplateArgs() && !TemplateKWLoc.isValid()) {
     NamedDecl *D = R.getAsSingle<NamedDecl>();
     // In a C++11 unevaluated context, an UnresolvedLookupExpr might refer to an
     // instance member. In other contexts, BuildPossibleImplicitMemberExpr will
     // give a good diagnostic.
     if (D && D->isCXXInstanceMember()) {
       return SemaRef.BuildPossibleImplicitMemberExpr(SS, TemplateKWLoc, R,
                                                      /*TemplateArgs=*/nullptr,
                                                      /*Scope=*/nullptr);
     }
 
     return getDerived().RebuildDeclarationNameExpr(SS, R, Old->requiresADL());
   }
 
   // If we have template arguments, rebuild them, then rebuild the
   // templateid expression.
   TemplateArgumentListInfo TransArgs(Old->getLAngleLoc(), Old->getRAngleLoc());
   if (Old->hasExplicitTemplateArgs() &&
       getDerived().TransformTemplateArguments(Old->getTemplateArgs(),
                                               Old->getNumTemplateArgs(),
                                               TransArgs)) {
     R.clear();
     return ExprError();
   }
 
   return getDerived().RebuildTemplateIdExpr(SS, TemplateKWLoc, R,
                                             Old->requiresADL(), &TransArgs);
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformTypeTraitExpr(TypeTraitExpr *E) {
   bool ArgChanged = false;
   SmallVector<TypeSourceInfo *, 4> Args;
   for (unsigned I = 0, N = E->getNumArgs(); I != N; ++I) {
     TypeSourceInfo *From = E->getArg(I);
     TypeLoc FromTL = From->getTypeLoc();
     if (!FromTL.getAs<PackExpansionTypeLoc>()) {
       TypeLocBuilder TLB;
       TLB.reserve(FromTL.getFullDataSize());
       QualType To = getDerived().TransformType(TLB, FromTL);
       if (To.isNull())
         return ExprError();
 
       if (To == From->getType())
         Args.push_back(From);
       else {
         Args.push_back(TLB.getTypeSourceInfo(SemaRef.Context, To));
         ArgChanged = true;
       }
       continue;
     }
 
     ArgChanged = true;
 
     // We have a pack expansion. Instantiate it.
     PackExpansionTypeLoc ExpansionTL = FromTL.castAs<PackExpansionTypeLoc>();
     TypeLoc PatternTL = ExpansionTL.getPatternLoc();
     SmallVector<UnexpandedParameterPack, 2> Unexpanded;
     SemaRef.collectUnexpandedParameterPacks(PatternTL, Unexpanded);
 
     // Determine whether the set of unexpanded parameter packs can and should
     // be expanded.
     bool Expand = true;
     bool RetainExpansion = false;
     std::optional<unsigned> OrigNumExpansions =
         ExpansionTL.getTypePtr()->getNumExpansions();
     std::optional<unsigned> NumExpansions = OrigNumExpansions;
     if (getDerived().TryExpandParameterPacks(ExpansionTL.getEllipsisLoc(),
                                              PatternTL.getSourceRange(),
                                              Unexpanded,
                                              Expand, RetainExpansion,
                                              NumExpansions))
       return ExprError();
 
     if (!Expand) {
       // The transform has determined that we should perform a simple
       // transformation on the pack expansion, producing another pack
       // expansion.
       Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(getSema(), -1);
 
       TypeLocBuilder TLB;
       TLB.reserve(From->getTypeLoc().getFullDataSize());
 
       QualType To = getDerived().TransformType(TLB, PatternTL);
       if (To.isNull())
         return ExprError();
 
       To = getDerived().RebuildPackExpansionType(To,
                                                  PatternTL.getSourceRange(),
                                                  ExpansionTL.getEllipsisLoc(),
                                                  NumExpansions);
       if (To.isNull())
         return ExprError();
 
       PackExpansionTypeLoc ToExpansionTL
         = TLB.push<PackExpansionTypeLoc>(To);
       ToExpansionTL.setEllipsisLoc(ExpansionTL.getEllipsisLoc());
       Args.push_back(TLB.getTypeSourceInfo(SemaRef.Context, To));
       continue;
     }
 
     // Expand the pack expansion by substituting for each argument in the
     // pack(s).
     for (unsigned I = 0; I != *NumExpansions; ++I) {
       Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(SemaRef, I);
       TypeLocBuilder TLB;
       TLB.reserve(PatternTL.getFullDataSize());
       QualType To = getDerived().TransformType(TLB, PatternTL);
       if (To.isNull())
         return ExprError();
 
       if (To->containsUnexpandedParameterPack()) {
         To = getDerived().RebuildPackExpansionType(To,
                                                    PatternTL.getSourceRange(),
                                                    ExpansionTL.getEllipsisLoc(),
                                                    NumExpansions);
         if (To.isNull())
           return ExprError();
 
         PackExpansionTypeLoc ToExpansionTL
           = TLB.push<PackExpansionTypeLoc>(To);
         ToExpansionTL.setEllipsisLoc(ExpansionTL.getEllipsisLoc());
       }
 
       Args.push_back(TLB.getTypeSourceInfo(SemaRef.Context, To));
     }
 
     if (!RetainExpansion)
       continue;
 
     // If we're supposed to retain a pack expansion, do so by temporarily
     // forgetting the partially-substituted parameter pack.
     ForgetPartiallySubstitutedPackRAII Forget(getDerived());
 
     TypeLocBuilder TLB;
     TLB.reserve(From->getTypeLoc().getFullDataSize());
 
     QualType To = getDerived().TransformType(TLB, PatternTL);
     if (To.isNull())
       return ExprError();
 
     To = getDerived().RebuildPackExpansionType(To,
                                                PatternTL.getSourceRange(),
                                                ExpansionTL.getEllipsisLoc(),
                                                NumExpansions);
     if (To.isNull())
       return ExprError();
 
     PackExpansionTypeLoc ToExpansionTL
       = TLB.push<PackExpansionTypeLoc>(To);
     ToExpansionTL.setEllipsisLoc(ExpansionTL.getEllipsisLoc());
     Args.push_back(TLB.getTypeSourceInfo(SemaRef.Context, To));
   }
 
   if (!getDerived().AlwaysRebuild() && !ArgChanged)
     return E;
 
   return getDerived().RebuildTypeTrait(E->getTrait(), E->getBeginLoc(), Args,
                                        E->getEndLoc());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformConceptSpecializationExpr(
                                                  ConceptSpecializationExpr *E) {
   const ASTTemplateArgumentListInfo *Old = E->getTemplateArgsAsWritten();
   TemplateArgumentListInfo TransArgs(Old->LAngleLoc, Old->RAngleLoc);
   if (getDerived().TransformTemplateArguments(Old->getTemplateArgs(),
                                               Old->NumTemplateArgs, TransArgs))
     return ExprError();
 
   return getDerived().RebuildConceptSpecializationExpr(
       E->getNestedNameSpecifierLoc(), E->getTemplateKWLoc(),
       E->getConceptNameInfo(), E->getFoundDecl(), E->getNamedConcept(),
       &TransArgs);
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformRequiresExpr(RequiresExpr *E) {
   SmallVector<ParmVarDecl*, 4> TransParams;
   SmallVector<QualType, 4> TransParamTypes;
   Sema::ExtParameterInfoBuilder ExtParamInfos;
 
   // C++2a [expr.prim.req]p2
   // Expressions appearing within a requirement-body are unevaluated operands.
   EnterExpressionEvaluationContext Ctx(
       SemaRef, Sema::ExpressionEvaluationContext::Unevaluated,
       Sema::ReuseLambdaContextDecl);
 
   RequiresExprBodyDecl *Body = RequiresExprBodyDecl::Create(
       getSema().Context, getSema().CurContext,
       E->getBody()->getBeginLoc());
 
   Sema::ContextRAII SavedContext(getSema(), Body, /*NewThisContext*/false);
 
   ExprResult TypeParamResult = getDerived().TransformRequiresTypeParams(
       E->getRequiresKWLoc(), E->getRBraceLoc(), E, Body,
       E->getLocalParameters(), TransParamTypes, TransParams, ExtParamInfos);
 
   for (ParmVarDecl *Param : TransParams)
     if (Param)
       Param->setDeclContext(Body);
 
   // On failure to transform, TransformRequiresTypeParams returns an expression
   // in the event that the transformation of the type params failed in some way.
   // It is expected that this will result in a 'not satisfied' Requires clause
   // when instantiating.
   if (!TypeParamResult.isUnset())
     return TypeParamResult;
 
   SmallVector<concepts::Requirement *, 4> TransReqs;
   if (getDerived().TransformRequiresExprRequirements(E->getRequirements(),
                                                      TransReqs))
     return ExprError();
 
   for (concepts::Requirement *Req : TransReqs) {
     if (auto *ER = dyn_cast<concepts::ExprRequirement>(Req)) {
       if (ER->getReturnTypeRequirement().isTypeConstraint()) {
         ER->getReturnTypeRequirement()
                 .getTypeConstraintTemplateParameterList()->getParam(0)
                 ->setDeclContext(Body);
       }
     }
   }
 
   return getDerived().RebuildRequiresExpr(E->getRequiresKWLoc(), Body,
                                           TransParams, TransReqs,
                                           E->getRBraceLoc());
 }
 
 template<typename Derived>
 bool TreeTransform<Derived>::TransformRequiresExprRequirements(
     ArrayRef<concepts::Requirement *> Reqs,
     SmallVectorImpl<concepts::Requirement *> &Transformed) {
   for (concepts::Requirement *Req : Reqs) {
     concepts::Requirement *TransReq = nullptr;
     if (auto *TypeReq = dyn_cast<concepts::TypeRequirement>(Req))
       TransReq = getDerived().TransformTypeRequirement(TypeReq);
     else if (auto *ExprReq = dyn_cast<concepts::ExprRequirement>(Req))
       TransReq = getDerived().TransformExprRequirement(ExprReq);
     else
       TransReq = getDerived().TransformNestedRequirement(
                      cast<concepts::NestedRequirement>(Req));
     if (!TransReq)
       return true;
     Transformed.push_back(TransReq);
   }
   return false;
 }
 
 template<typename Derived>
 concepts::TypeRequirement *
 TreeTransform<Derived>::TransformTypeRequirement(
     concepts::TypeRequirement *Req) {
   if (Req->isSubstitutionFailure()) {
     if (getDerived().AlwaysRebuild())
       return getDerived().RebuildTypeRequirement(
               Req->getSubstitutionDiagnostic());
     return Req;
   }
   TypeSourceInfo *TransType = getDerived().TransformType(Req->getType());
   if (!TransType)
     return nullptr;
   return getDerived().RebuildTypeRequirement(TransType);
 }
 
 template<typename Derived>
 concepts::ExprRequirement *
 TreeTransform<Derived>::TransformExprRequirement(concepts::ExprRequirement *Req) {
   llvm::PointerUnion<Expr *, concepts::Requirement::SubstitutionDiagnostic *> TransExpr;
   if (Req->isExprSubstitutionFailure())
     TransExpr = Req->getExprSubstitutionDiagnostic();
   else {
     ExprResult TransExprRes = getDerived().TransformExpr(Req->getExpr());
     if (TransExprRes.isUsable() && TransExprRes.get()->hasPlaceholderType())
       TransExprRes = SemaRef.CheckPlaceholderExpr(TransExprRes.get());
     if (TransExprRes.isInvalid())
       return nullptr;
     TransExpr = TransExprRes.get();
   }
 
   std::optional<concepts::ExprRequirement::ReturnTypeRequirement> TransRetReq;
   const auto &RetReq = Req->getReturnTypeRequirement();
   if (RetReq.isEmpty())
     TransRetReq.emplace();
   else if (RetReq.isSubstitutionFailure())
     TransRetReq.emplace(RetReq.getSubstitutionDiagnostic());
   else if (RetReq.isTypeConstraint()) {
     TemplateParameterList *OrigTPL =
         RetReq.getTypeConstraintTemplateParameterList();
     TemplateParameterList *TPL =
         getDerived().TransformTemplateParameterList(OrigTPL);
     if (!TPL)
       return nullptr;
     TransRetReq.emplace(TPL);
   }
   assert(TransRetReq && "All code paths leading here must set TransRetReq");
   if (Expr *E = TransExpr.dyn_cast<Expr *>())
     return getDerived().RebuildExprRequirement(E, Req->isSimple(),
                                                Req->getNoexceptLoc(),
                                                std::move(*TransRetReq));
   return getDerived().RebuildExprRequirement(
       TransExpr.get<concepts::Requirement::SubstitutionDiagnostic *>(),
       Req->isSimple(), Req->getNoexceptLoc(), std::move(*TransRetReq));
 }
 
 template<typename Derived>
 concepts::NestedRequirement *
 TreeTransform<Derived>::TransformNestedRequirement(
     concepts::NestedRequirement *Req) {
   if (Req->hasInvalidConstraint()) {
     if (getDerived().AlwaysRebuild())
       return getDerived().RebuildNestedRequirement(
           Req->getInvalidConstraintEntity(), Req->getConstraintSatisfaction());
     return Req;
   }
   ExprResult TransConstraint =
       getDerived().TransformExpr(Req->getConstraintExpr());
   if (TransConstraint.isInvalid())
     return nullptr;
   return getDerived().RebuildNestedRequirement(TransConstraint.get());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformArrayTypeTraitExpr(ArrayTypeTraitExpr *E) {
   TypeSourceInfo *T = getDerived().TransformType(E->getQueriedTypeSourceInfo());
   if (!T)
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() &&
       T == E->getQueriedTypeSourceInfo())
     return E;
 
   ExprResult SubExpr;
   {
     EnterExpressionEvaluationContext Unevaluated(
         SemaRef, Sema::ExpressionEvaluationContext::Unevaluated);
     SubExpr = getDerived().TransformExpr(E->getDimensionExpression());
     if (SubExpr.isInvalid())
       return ExprError();
 
     if (!getDerived().AlwaysRebuild() && SubExpr.get() == E->getDimensionExpression())
       return E;
   }
 
   return getDerived().RebuildArrayTypeTrait(E->getTrait(), E->getBeginLoc(), T,
                                             SubExpr.get(), E->getEndLoc());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformExpressionTraitExpr(ExpressionTraitExpr *E) {
   ExprResult SubExpr;
   {
     EnterExpressionEvaluationContext Unevaluated(
         SemaRef, Sema::ExpressionEvaluationContext::Unevaluated);
     SubExpr = getDerived().TransformExpr(E->getQueriedExpression());
     if (SubExpr.isInvalid())
       return ExprError();
 
     if (!getDerived().AlwaysRebuild() && SubExpr.get() == E->getQueriedExpression())
       return E;
   }
 
   return getDerived().RebuildExpressionTrait(E->getTrait(), E->getBeginLoc(),
                                              SubExpr.get(), E->getEndLoc());
 }
 
 template <typename Derived>
 ExprResult TreeTransform<Derived>::TransformParenDependentScopeDeclRefExpr(
     ParenExpr *PE, DependentScopeDeclRefExpr *DRE, bool AddrTaken,
     TypeSourceInfo **RecoveryTSI) {
   ExprResult NewDRE = getDerived().TransformDependentScopeDeclRefExpr(
       DRE, AddrTaken, RecoveryTSI);
 
   // Propagate both errors and recovered types, which return ExprEmpty.
   if (!NewDRE.isUsable())
     return NewDRE;
 
   // We got an expr, wrap it up in parens.
   if (!getDerived().AlwaysRebuild() && NewDRE.get() == DRE)
     return PE;
   return getDerived().RebuildParenExpr(NewDRE.get(), PE->getLParen(),
                                        PE->getRParen());
 }
 
 template <typename Derived>
 ExprResult TreeTransform<Derived>::TransformDependentScopeDeclRefExpr(
     DependentScopeDeclRefExpr *E) {
   return TransformDependentScopeDeclRefExpr(E, /*IsAddressOfOperand=*/false,
                                             nullptr);
 }
 
 template <typename Derived>
 ExprResult TreeTransform<Derived>::TransformDependentScopeDeclRefExpr(
     DependentScopeDeclRefExpr *E, bool IsAddressOfOperand,
     TypeSourceInfo **RecoveryTSI) {
   assert(E->getQualifierLoc());
   NestedNameSpecifierLoc QualifierLoc =
       getDerived().TransformNestedNameSpecifierLoc(E->getQualifierLoc());
   if (!QualifierLoc)
     return ExprError();
   SourceLocation TemplateKWLoc = E->getTemplateKeywordLoc();
 
   // TODO: If this is a conversion-function-id, verify that the
   // destination type name (if present) resolves the same way after
   // instantiation as it did in the local scope.
 
   DeclarationNameInfo NameInfo =
       getDerived().TransformDeclarationNameInfo(E->getNameInfo());
   if (!NameInfo.getName())
     return ExprError();
 
   if (!E->hasExplicitTemplateArgs()) {
     if (!getDerived().AlwaysRebuild() && QualifierLoc == E->getQualifierLoc() &&
         // Note: it is sufficient to compare the Name component of NameInfo:
         // if name has not changed, DNLoc has not changed either.
         NameInfo.getName() == E->getDeclName())
       return E;
 
     return getDerived().RebuildDependentScopeDeclRefExpr(
         QualifierLoc, TemplateKWLoc, NameInfo, /*TemplateArgs=*/nullptr,
         IsAddressOfOperand, RecoveryTSI);
   }
 
   TemplateArgumentListInfo TransArgs(E->getLAngleLoc(), E->getRAngleLoc());
   if (getDerived().TransformTemplateArguments(
           E->getTemplateArgs(), E->getNumTemplateArgs(), TransArgs))
     return ExprError();
 
   return getDerived().RebuildDependentScopeDeclRefExpr(
       QualifierLoc, TemplateKWLoc, NameInfo, &TransArgs, IsAddressOfOperand,
       RecoveryTSI);
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXConstructExpr(CXXConstructExpr *E) {
   // CXXConstructExprs other than for list-initialization and
   // CXXTemporaryObjectExpr are always implicit, so when we have
   // a 1-argument construction we just transform that argument.
   if (getDerived().AllowSkippingCXXConstructExpr() &&
       ((E->getNumArgs() == 1 ||
         (E->getNumArgs() > 1 && getDerived().DropCallArgument(E->getArg(1)))) &&
        (!getDerived().DropCallArgument(E->getArg(0))) &&
        !E->isListInitialization()))
     return getDerived().TransformInitializer(E->getArg(0),
                                              /*DirectInit*/ false);
 
   TemporaryBase Rebase(*this, /*FIXME*/ E->getBeginLoc(), DeclarationName());
 
   QualType T = getDerived().TransformType(E->getType());
   if (T.isNull())
     return ExprError();
 
   CXXConstructorDecl *Constructor = cast_or_null<CXXConstructorDecl>(
       getDerived().TransformDecl(E->getBeginLoc(), E->getConstructor()));
   if (!Constructor)
     return ExprError();
 
   bool ArgumentChanged = false;
   SmallVector<Expr*, 8> Args;
   {
     EnterExpressionEvaluationContext Context(
         getSema(), EnterExpressionEvaluationContext::InitList,
         E->isListInitialization());
     if (getDerived().TransformExprs(E->getArgs(), E->getNumArgs(), true, Args,
                                     &ArgumentChanged))
       return ExprError();
   }
 
   if (!getDerived().AlwaysRebuild() &&
       T == E->getType() &&
       Constructor == E->getConstructor() &&
       !ArgumentChanged) {
     // Mark the constructor as referenced.
     // FIXME: Instantiation-specific
     SemaRef.MarkFunctionReferenced(E->getBeginLoc(), Constructor);
     return E;
   }
 
   return getDerived().RebuildCXXConstructExpr(
       T, /*FIXME:*/ E->getBeginLoc(), Constructor, E->isElidable(), Args,
       E->hadMultipleCandidates(), E->isListInitialization(),
       E->isStdInitListInitialization(), E->requiresZeroInitialization(),
       E->getConstructionKind(), E->getParenOrBraceRange());
 }
 
 template<typename Derived>
 ExprResult TreeTransform<Derived>::TransformCXXInheritedCtorInitExpr(
     CXXInheritedCtorInitExpr *E) {
   QualType T = getDerived().TransformType(E->getType());
   if (T.isNull())
     return ExprError();
 
   CXXConstructorDecl *Constructor = cast_or_null<CXXConstructorDecl>(
       getDerived().TransformDecl(E->getBeginLoc(), E->getConstructor()));
   if (!Constructor)
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() &&
       T == E->getType() &&
       Constructor == E->getConstructor()) {
     // Mark the constructor as referenced.
     // FIXME: Instantiation-specific
     SemaRef.MarkFunctionReferenced(E->getBeginLoc(), Constructor);
     return E;
   }
 
   return getDerived().RebuildCXXInheritedCtorInitExpr(
       T, E->getLocation(), Constructor,
       E->constructsVBase(), E->inheritedFromVBase());
 }
 
 /// Transform a C++ temporary-binding expression.
 ///
 /// Since CXXBindTemporaryExpr nodes are implicitly generated, we just
 /// transform the subexpression and return that.
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXBindTemporaryExpr(CXXBindTemporaryExpr *E) {
   if (auto *Dtor = E->getTemporary()->getDestructor())
     SemaRef.MarkFunctionReferenced(E->getBeginLoc(),
                                    const_cast<CXXDestructorDecl *>(Dtor));
   return getDerived().TransformExpr(E->getSubExpr());
 }
 
 /// Transform a C++ expression that contains cleanups that should
 /// be run after the expression is evaluated.
 ///
 /// Since ExprWithCleanups nodes are implicitly generated, we
 /// just transform the subexpression and return that.
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformExprWithCleanups(ExprWithCleanups *E) {
   return getDerived().TransformExpr(E->getSubExpr());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXTemporaryObjectExpr(
                                                     CXXTemporaryObjectExpr *E) {
   TypeSourceInfo *T =
       getDerived().TransformTypeWithDeducedTST(E->getTypeSourceInfo());
   if (!T)
     return ExprError();
 
   CXXConstructorDecl *Constructor = cast_or_null<CXXConstructorDecl>(
       getDerived().TransformDecl(E->getBeginLoc(), E->getConstructor()));
   if (!Constructor)
     return ExprError();
 
   bool ArgumentChanged = false;
   SmallVector<Expr*, 8> Args;
   Args.reserve(E->getNumArgs());
   {
     EnterExpressionEvaluationContext Context(
         getSema(), EnterExpressionEvaluationContext::InitList,
         E->isListInitialization());
     if (TransformExprs(E->getArgs(), E->getNumArgs(), true, Args,
                        &ArgumentChanged))
       return ExprError();
   }
 
   if (!getDerived().AlwaysRebuild() &&
       T == E->getTypeSourceInfo() &&
       Constructor == E->getConstructor() &&
       !ArgumentChanged) {
     // FIXME: Instantiation-specific
     SemaRef.MarkFunctionReferenced(E->getBeginLoc(), Constructor);
     return SemaRef.MaybeBindToTemporary(E);
   }
 
   // FIXME: We should just pass E->isListInitialization(), but we're not
   // prepared to handle list-initialization without a child InitListExpr.
   SourceLocation LParenLoc = T->getTypeLoc().getEndLoc();
   return getDerived().RebuildCXXTemporaryObjectExpr(
       T, LParenLoc, Args, E->getEndLoc(),
       /*ListInitialization=*/LParenLoc.isInvalid());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) {
   // Transform any init-capture expressions before entering the scope of the
   // lambda body, because they are not semantically within that scope.
   typedef std::pair<ExprResult, QualType> InitCaptureInfoTy;
   struct TransformedInitCapture {
     // The location of the ... if the result is retaining a pack expansion.
     SourceLocation EllipsisLoc;
     // Zero or more expansions of the init-capture.
     SmallVector<InitCaptureInfoTy, 4> Expansions;
   };
   SmallVector<TransformedInitCapture, 4> InitCaptures;
   InitCaptures.resize(E->explicit_capture_end() - E->explicit_capture_begin());
   for (LambdaExpr::capture_iterator C = E->capture_begin(),
                                     CEnd = E->capture_end();
        C != CEnd; ++C) {
     if (!E->isInitCapture(C))
       continue;
 
     TransformedInitCapture &Result = InitCaptures[C - E->capture_begin()];
     auto *OldVD = cast<VarDecl>(C->getCapturedVar());
 
     auto SubstInitCapture = [&](SourceLocation EllipsisLoc,
                                 std::optional<unsigned> NumExpansions) {
       ExprResult NewExprInitResult = getDerived().TransformInitializer(
           OldVD->getInit(), OldVD->getInitStyle() == VarDecl::CallInit);
 
       if (NewExprInitResult.isInvalid()) {
         Result.Expansions.push_back(InitCaptureInfoTy(ExprError(), QualType()));
         return;
       }
       Expr *NewExprInit = NewExprInitResult.get();
 
       QualType NewInitCaptureType =
           getSema().buildLambdaInitCaptureInitialization(
               C->getLocation(), C->getCaptureKind() == LCK_ByRef,
               EllipsisLoc, NumExpansions, OldVD->getIdentifier(),
               cast<VarDecl>(C->getCapturedVar())->getInitStyle() !=
                   VarDecl::CInit,
               NewExprInit);
       Result.Expansions.push_back(
           InitCaptureInfoTy(NewExprInit, NewInitCaptureType));
     };
 
     // If this is an init-capture pack, consider expanding the pack now.
     if (OldVD->isParameterPack()) {
       PackExpansionTypeLoc ExpansionTL = OldVD->getTypeSourceInfo()
                                              ->getTypeLoc()
                                              .castAs<PackExpansionTypeLoc>();
       SmallVector<UnexpandedParameterPack, 2> Unexpanded;
       SemaRef.collectUnexpandedParameterPacks(OldVD->getInit(), Unexpanded);
 
       // Determine whether the set of unexpanded parameter packs can and should
       // be expanded.
       bool Expand = true;
       bool RetainExpansion = false;
       std::optional<unsigned> OrigNumExpansions =
           ExpansionTL.getTypePtr()->getNumExpansions();
       std::optional<unsigned> NumExpansions = OrigNumExpansions;
       if (getDerived().TryExpandParameterPacks(
               ExpansionTL.getEllipsisLoc(),
               OldVD->getInit()->getSourceRange(), Unexpanded, Expand,
               RetainExpansion, NumExpansions))
         return ExprError();
       if (Expand) {
         for (unsigned I = 0; I != *NumExpansions; ++I) {
           Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(getSema(), I);
           SubstInitCapture(SourceLocation(), std::nullopt);
         }
       }
       if (!Expand || RetainExpansion) {
         ForgetPartiallySubstitutedPackRAII Forget(getDerived());
         SubstInitCapture(ExpansionTL.getEllipsisLoc(), NumExpansions);
         Result.EllipsisLoc = ExpansionTL.getEllipsisLoc();
       }
     } else {
       SubstInitCapture(SourceLocation(), std::nullopt);
     }
   }
 
   LambdaScopeInfo *LSI = getSema().PushLambdaScope();
   Sema::FunctionScopeRAII FuncScopeCleanup(getSema());
 
   // Create the local class that will describe the lambda.
 
   // FIXME: DependencyKind below is wrong when substituting inside a templated
   // context that isn't a DeclContext (such as a variable template), or when
   // substituting an unevaluated lambda inside of a function's parameter's type
   // - as parameter types are not instantiated from within a function's DC. We
   // use evaluation contexts to distinguish the function parameter case.
   CXXRecordDecl::LambdaDependencyKind DependencyKind =
       CXXRecordDecl::LDK_Unknown;
   if ((getSema().isUnevaluatedContext() ||
        getSema().isConstantEvaluatedContext()) &&
       (getSema().CurContext->isFileContext() ||
        !getSema().CurContext->getParent()->isDependentContext()))
     DependencyKind = CXXRecordDecl::LDK_NeverDependent;
 
   CXXRecordDecl *OldClass = E->getLambdaClass();
   CXXRecordDecl *Class = getSema().createLambdaClosureType(
       E->getIntroducerRange(), /*Info=*/nullptr, DependencyKind,
       E->getCaptureDefault());
   getDerived().transformedLocalDecl(OldClass, {Class});
 
   CXXMethodDecl *NewCallOperator =
       getSema().CreateLambdaCallOperator(E->getIntroducerRange(), Class);
   NewCallOperator->setLexicalDeclContext(getSema().CurContext);
 
   // Enter the scope of the lambda.
   getSema().buildLambdaScope(LSI, NewCallOperator, E->getIntroducerRange(),
                              E->getCaptureDefault(), E->getCaptureDefaultLoc(),
                              E->hasExplicitParameters(), E->isMutable());
 
   // Introduce the context of the call operator.
   Sema::ContextRAII SavedContext(getSema(), NewCallOperator,
                                  /*NewThisContext*/false);
 
   bool Invalid = false;
 
   // Transform captures.
   for (LambdaExpr::capture_iterator C = E->capture_begin(),
                                  CEnd = E->capture_end();
        C != CEnd; ++C) {
     // When we hit the first implicit capture, tell Sema that we've finished
     // the list of explicit captures.
     if (C->isImplicit())
       break;
 
     // Capturing 'this' is trivial.
     if (C->capturesThis()) {
       getSema().CheckCXXThisCapture(C->getLocation(), C->isExplicit(),
                                     /*BuildAndDiagnose*/ true, nullptr,
                                     C->getCaptureKind() == LCK_StarThis);
       continue;
     }
     // Captured expression will be recaptured during captured variables
     // rebuilding.
     if (C->capturesVLAType())
       continue;
 
     // Rebuild init-captures, including the implied field declaration.
     if (E->isInitCapture(C)) {
       TransformedInitCapture &NewC = InitCaptures[C - E->capture_begin()];
 
       auto *OldVD = cast<VarDecl>(C->getCapturedVar());
       llvm::SmallVector<Decl*, 4> NewVDs;
 
       for (InitCaptureInfoTy &Info : NewC.Expansions) {
         ExprResult Init = Info.first;
         QualType InitQualType = Info.second;
         if (Init.isInvalid() || InitQualType.isNull()) {
           Invalid = true;
           break;
         }
         VarDecl *NewVD = getSema().createLambdaInitCaptureVarDecl(
             OldVD->getLocation(), InitQualType, NewC.EllipsisLoc,
             OldVD->getIdentifier(), OldVD->getInitStyle(), Init.get(),
             getSema().CurContext);
         if (!NewVD) {
           Invalid = true;
           break;
         }
         NewVDs.push_back(NewVD);
         getSema().addInitCapture(LSI, NewVD, C->getCaptureKind() == LCK_ByRef);
       }
 
       if (Invalid)
         break;
 
       getDerived().transformedLocalDecl(OldVD, NewVDs);
       continue;
     }
 
     assert(C->capturesVariable() && "unexpected kind of lambda capture");
 
     // Determine the capture kind for Sema.
     Sema::TryCaptureKind Kind
       = C->isImplicit()? Sema::TryCapture_Implicit
                        : C->getCaptureKind() == LCK_ByCopy
                            ? Sema::TryCapture_ExplicitByVal
                            : Sema::TryCapture_ExplicitByRef;
     SourceLocation EllipsisLoc;
     if (C->isPackExpansion()) {
       UnexpandedParameterPack Unexpanded(C->getCapturedVar(), C->getLocation());
       bool ShouldExpand = false;
       bool RetainExpansion = false;
       std::optional<unsigned> NumExpansions;
       if (getDerived().TryExpandParameterPacks(C->getEllipsisLoc(),
                                                C->getLocation(),
                                                Unexpanded,
                                                ShouldExpand, RetainExpansion,
                                                NumExpansions)) {
         Invalid = true;
         continue;
       }
 
       if (ShouldExpand) {
         // The transform has determined that we should perform an expansion;
         // transform and capture each of the arguments.
         // expansion of the pattern. Do so.
         auto *Pack = cast<VarDecl>(C->getCapturedVar());
         for (unsigned I = 0; I != *NumExpansions; ++I) {
           Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(getSema(), I);
           VarDecl *CapturedVar
             = cast_or_null<VarDecl>(getDerived().TransformDecl(C->getLocation(),
                                                                Pack));
           if (!CapturedVar) {
             Invalid = true;
             continue;
           }
 
           // Capture the transformed variable.
           getSema().tryCaptureVariable(CapturedVar, C->getLocation(), Kind);
         }
 
         // FIXME: Retain a pack expansion if RetainExpansion is true.
 
         continue;
       }
 
       EllipsisLoc = C->getEllipsisLoc();
     }
 
     // Transform the captured variable.
     auto *CapturedVar = cast_or_null<ValueDecl>(
         getDerived().TransformDecl(C->getLocation(), C->getCapturedVar()));
     if (!CapturedVar || CapturedVar->isInvalidDecl()) {
       Invalid = true;
       continue;
     }
 
     // Capture the transformed variable.
     getSema().tryCaptureVariable(CapturedVar, C->getLocation(), Kind,
                                  EllipsisLoc);
   }
   getSema().finishLambdaExplicitCaptures(LSI);
 
   // Transform the template parameters, and add them to the current
   // instantiation scope. The null case is handled correctly.
   auto TPL = getDerived().TransformTemplateParameterList(
       E->getTemplateParameterList());
   LSI->GLTemplateParameterList = TPL;
 
   // Transform the type of the original lambda's call operator.
   // The transformation MUST be done in the CurrentInstantiationScope since
   // it introduces a mapping of the original to the newly created
   // transformed parameters.
   TypeSourceInfo *NewCallOpTSI = nullptr;
   {
     TypeSourceInfo *OldCallOpTSI = E->getCallOperator()->getTypeSourceInfo();
     auto OldCallOpFPTL =
         OldCallOpTSI->getTypeLoc().getAs<FunctionProtoTypeLoc>();
 
     TypeLocBuilder NewCallOpTLBuilder;
     SmallVector<QualType, 4> ExceptionStorage;
     TreeTransform *This = this; // Work around gcc.gnu.org/PR56135.
     QualType NewCallOpType = TransformFunctionProtoType(
         NewCallOpTLBuilder, OldCallOpFPTL, nullptr, Qualifiers(),
         [&](FunctionProtoType::ExceptionSpecInfo &ESI, bool &Changed) {
           return This->TransformExceptionSpec(OldCallOpFPTL.getBeginLoc(), ESI,
                                               ExceptionStorage, Changed);
         });
     if (NewCallOpType.isNull())
       return ExprError();
     NewCallOpTSI =
         NewCallOpTLBuilder.getTypeSourceInfo(getSema().Context, NewCallOpType);
   }
 
   getSema().CompleteLambdaCallOperator(
       NewCallOperator, E->getCallOperator()->getLocation(),
       E->getCallOperator()->getInnerLocStart(),
       E->getCallOperator()->getTrailingRequiresClause(), NewCallOpTSI,
       E->getCallOperator()->getConstexprKind(),
       E->getCallOperator()->getStorageClass(),
       NewCallOpTSI->getTypeLoc().castAs<FunctionProtoTypeLoc>().getParams(),
       E->hasExplicitResultType());
 
   getDerived().transformAttrs(E->getCallOperator(), NewCallOperator);
   getDerived().transformedLocalDecl(E->getCallOperator(), {NewCallOperator});
 
   {
     // Number the lambda for linkage purposes if necessary.
     Sema::ContextRAII ManglingContext(getSema(), Class->getDeclContext());
 
     std::optional<CXXRecordDecl::LambdaNumbering> Numbering;
     if (getDerived().ReplacingOriginal()) {
       Numbering = OldClass->getLambdaNumbering();
     }
 
     getSema().handleLambdaNumbering(Class, NewCallOperator, Numbering);
   }
 
   // FIXME: Sema's lambda-building mechanism expects us to push an expression
   // evaluation context even if we're not transforming the function body.
   getSema().PushExpressionEvaluationContext(
       Sema::ExpressionEvaluationContext::PotentiallyEvaluated);
 
   // Instantiate the body of the lambda expression.
   StmtResult Body =
       Invalid ? StmtError() : getDerived().TransformLambdaBody(E, E->getBody());
 
   // ActOnLambda* will pop the function scope for us.
   FuncScopeCleanup.disable();
 
   if (Body.isInvalid()) {
     SavedContext.pop();
     getSema().ActOnLambdaError(E->getBeginLoc(), /*CurScope=*/nullptr,
                                /*IsInstantiation=*/true);
     return ExprError();
   }
 
   // Copy the LSI before ActOnFinishFunctionBody removes it.
   // FIXME: This is dumb. Store the lambda information somewhere that outlives
   // the call operator.
   auto LSICopy = *LSI;
   getSema().ActOnFinishFunctionBody(NewCallOperator, Body.get(),
                                     /*IsInstantiation*/ true);
   SavedContext.pop();
 
   return getSema().BuildLambdaExpr(E->getBeginLoc(), Body.get()->getEndLoc(),
                                    &LSICopy);
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformLambdaBody(LambdaExpr *E, Stmt *S) {
   return TransformStmt(S);
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::SkipLambdaBody(LambdaExpr *E, Stmt *S) {
   // Transform captures.
   for (LambdaExpr::capture_iterator C = E->capture_begin(),
                                  CEnd = E->capture_end();
        C != CEnd; ++C) {
     // When we hit the first implicit capture, tell Sema that we've finished
     // the list of explicit captures.
     if (!C->isImplicit())
       continue;
 
     // Capturing 'this' is trivial.
     if (C->capturesThis()) {
       getSema().CheckCXXThisCapture(C->getLocation(), C->isExplicit(),
                                     /*BuildAndDiagnose*/ true, nullptr,
                                     C->getCaptureKind() == LCK_StarThis);
       continue;
     }
     // Captured expression will be recaptured during captured variables
     // rebuilding.
     if (C->capturesVLAType())
       continue;
 
     assert(C->capturesVariable() && "unexpected kind of lambda capture");
     assert(!E->isInitCapture(C) && "implicit init-capture?");
 
     // Transform the captured variable.
     VarDecl *CapturedVar = cast_or_null<VarDecl>(
         getDerived().TransformDecl(C->getLocation(), C->getCapturedVar()));
     if (!CapturedVar || CapturedVar->isInvalidDecl())
       return StmtError();
 
     // Capture the transformed variable.
     getSema().tryCaptureVariable(CapturedVar, C->getLocation());
   }
 
   return S;
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXUnresolvedConstructExpr(
                                                   CXXUnresolvedConstructExpr *E) {
   TypeSourceInfo *T =
       getDerived().TransformTypeWithDeducedTST(E->getTypeSourceInfo());
   if (!T)
     return ExprError();
 
   bool ArgumentChanged = false;
   SmallVector<Expr*, 8> Args;
   Args.reserve(E->getNumArgs());
   {
     EnterExpressionEvaluationContext Context(
         getSema(), EnterExpressionEvaluationContext::InitList,
         E->isListInitialization());
     if (getDerived().TransformExprs(E->arg_begin(), E->getNumArgs(), true, Args,
                                     &ArgumentChanged))
       return ExprError();
   }
 
   if (!getDerived().AlwaysRebuild() &&
       T == E->getTypeSourceInfo() &&
       !ArgumentChanged)
     return E;
 
   // FIXME: we're faking the locations of the commas
   return getDerived().RebuildCXXUnresolvedConstructExpr(
       T, E->getLParenLoc(), Args, E->getRParenLoc(), E->isListInitialization());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXDependentScopeMemberExpr(
                                              CXXDependentScopeMemberExpr *E) {
   // Transform the base of the expression.
   ExprResult Base((Expr*) nullptr);
   Expr *OldBase;
   QualType BaseType;
   QualType ObjectType;
   if (!E->isImplicitAccess()) {
     OldBase = E->getBase();
     Base = getDerived().TransformExpr(OldBase);
     if (Base.isInvalid())
       return ExprError();
 
     // Start the member reference and compute the object's type.
     ParsedType ObjectTy;
     bool MayBePseudoDestructor = false;
     Base = SemaRef.ActOnStartCXXMemberReference(nullptr, Base.get(),
                                                 E->getOperatorLoc(),
                                       E->isArrow()? tok::arrow : tok::period,
                                                 ObjectTy,
                                                 MayBePseudoDestructor);
     if (Base.isInvalid())
       return ExprError();
 
     ObjectType = ObjectTy.get();
     BaseType = ((Expr*) Base.get())->getType();
   } else {
     OldBase = nullptr;
     BaseType = getDerived().TransformType(E->getBaseType());
     ObjectType = BaseType->castAs<PointerType>()->getPointeeType();
   }
 
   // Transform the first part of the nested-name-specifier that qualifies
   // the member name.
   NamedDecl *FirstQualifierInScope
     = getDerived().TransformFirstQualifierInScope(
                                             E->getFirstQualifierFoundInScope(),
                                             E->getQualifierLoc().getBeginLoc());
 
   NestedNameSpecifierLoc QualifierLoc;
   if (E->getQualifier()) {
     QualifierLoc
       = getDerived().TransformNestedNameSpecifierLoc(E->getQualifierLoc(),
                                                      ObjectType,
                                                      FirstQualifierInScope);
     if (!QualifierLoc)
       return ExprError();
   }
 
   SourceLocation TemplateKWLoc = E->getTemplateKeywordLoc();
 
   // TODO: If this is a conversion-function-id, verify that the
   // destination type name (if present) resolves the same way after
   // instantiation as it did in the local scope.
 
   DeclarationNameInfo NameInfo
     = getDerived().TransformDeclarationNameInfo(E->getMemberNameInfo());
   if (!NameInfo.getName())
     return ExprError();
 
   if (!E->hasExplicitTemplateArgs()) {
     // This is a reference to a member without an explicitly-specified
     // template argument list. Optimize for this common case.
     if (!getDerived().AlwaysRebuild() &&
         Base.get() == OldBase &&
         BaseType == E->getBaseType() &&
         QualifierLoc == E->getQualifierLoc() &&
         NameInfo.getName() == E->getMember() &&
         FirstQualifierInScope == E->getFirstQualifierFoundInScope())
       return E;
 
     return getDerived().RebuildCXXDependentScopeMemberExpr(Base.get(),
                                                        BaseType,
                                                        E->isArrow(),
                                                        E->getOperatorLoc(),
                                                        QualifierLoc,
                                                        TemplateKWLoc,
                                                        FirstQualifierInScope,
                                                        NameInfo,
                                                        /*TemplateArgs*/nullptr);
   }
 
   TemplateArgumentListInfo TransArgs(E->getLAngleLoc(), E->getRAngleLoc());
   if (getDerived().TransformTemplateArguments(E->getTemplateArgs(),
                                               E->getNumTemplateArgs(),
                                               TransArgs))
     return ExprError();
 
   return getDerived().RebuildCXXDependentScopeMemberExpr(Base.get(),
                                                      BaseType,
                                                      E->isArrow(),
                                                      E->getOperatorLoc(),
                                                      QualifierLoc,
                                                      TemplateKWLoc,
                                                      FirstQualifierInScope,
                                                      NameInfo,
                                                      &TransArgs);
 }
 
 template <typename Derived>
 ExprResult TreeTransform<Derived>::TransformUnresolvedMemberExpr(
     UnresolvedMemberExpr *Old) {
   // Transform the base of the expression.
   ExprResult Base((Expr *)nullptr);
   QualType BaseType;
   if (!Old->isImplicitAccess()) {
     Base = getDerived().TransformExpr(Old->getBase());
     if (Base.isInvalid())
       return ExprError();
     Base =
         getSema().PerformMemberExprBaseConversion(Base.get(), Old->isArrow());
     if (Base.isInvalid())
       return ExprError();
     BaseType = Base.get()->getType();
   } else {
     BaseType = getDerived().TransformType(Old->getBaseType());
   }
 
   NestedNameSpecifierLoc QualifierLoc;
   if (Old->getQualifierLoc()) {
     QualifierLoc =
         getDerived().TransformNestedNameSpecifierLoc(Old->getQualifierLoc());
     if (!QualifierLoc)
       return ExprError();
   }
 
   SourceLocation TemplateKWLoc = Old->getTemplateKeywordLoc();
 
   LookupResult R(SemaRef, Old->getMemberNameInfo(), Sema::LookupOrdinaryName);
 
   // Transform the declaration set.
   if (TransformOverloadExprDecls(Old, /*RequiresADL*/ false, R))
     return ExprError();
 
   // Determine the naming class.
   if (Old->getNamingClass()) {
     CXXRecordDecl *NamingClass = cast_or_null<CXXRecordDecl>(
         getDerived().TransformDecl(Old->getMemberLoc(), Old->getNamingClass()));
     if (!NamingClass)
       return ExprError();
 
     R.setNamingClass(NamingClass);
   }
 
   TemplateArgumentListInfo TransArgs;
   if (Old->hasExplicitTemplateArgs()) {
     TransArgs.setLAngleLoc(Old->getLAngleLoc());
     TransArgs.setRAngleLoc(Old->getRAngleLoc());
     if (getDerived().TransformTemplateArguments(
             Old->getTemplateArgs(), Old->getNumTemplateArgs(), TransArgs))
       return ExprError();
   }
 
   // FIXME: to do this check properly, we will need to preserve the
   // first-qualifier-in-scope here, just in case we had a dependent
   // base (and therefore couldn't do the check) and a
   // nested-name-qualifier (and therefore could do the lookup).
   NamedDecl *FirstQualifierInScope = nullptr;
 
   return getDerived().RebuildUnresolvedMemberExpr(
       Base.get(), BaseType, Old->getOperatorLoc(), Old->isArrow(), QualifierLoc,
       TemplateKWLoc, FirstQualifierInScope, R,
       (Old->hasExplicitTemplateArgs() ? &TransArgs : nullptr));
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXNoexceptExpr(CXXNoexceptExpr *E) {
   EnterExpressionEvaluationContext Unevaluated(
       SemaRef, Sema::ExpressionEvaluationContext::Unevaluated);
   ExprResult SubExpr = getDerived().TransformExpr(E->getOperand());
   if (SubExpr.isInvalid())
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() && SubExpr.get() == E->getOperand())
     return E;
 
   return getDerived().RebuildCXXNoexceptExpr(E->getSourceRange(),SubExpr.get());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformPackExpansionExpr(PackExpansionExpr *E) {
   ExprResult Pattern = getDerived().TransformExpr(E->getPattern());
   if (Pattern.isInvalid())
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() && Pattern.get() == E->getPattern())
     return E;
 
   return getDerived().RebuildPackExpansion(Pattern.get(), E->getEllipsisLoc(),
                                            E->getNumExpansions());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformSizeOfPackExpr(SizeOfPackExpr *E) {
   // If E is not value-dependent, then nothing will change when we transform it.
   // Note: This is an instantiation-centric view.
   if (!E->isValueDependent())
     return E;
 
   EnterExpressionEvaluationContext Unevaluated(
       getSema(), Sema::ExpressionEvaluationContext::Unevaluated);
 
   ArrayRef<TemplateArgument> PackArgs;
   TemplateArgument ArgStorage;
 
   // Find the argument list to transform.
   if (E->isPartiallySubstituted()) {
     PackArgs = E->getPartialArguments();
   } else if (E->isValueDependent()) {
     UnexpandedParameterPack Unexpanded(E->getPack(), E->getPackLoc());
     bool ShouldExpand = false;
     bool RetainExpansion = false;
     std::optional<unsigned> NumExpansions;
     if (getDerived().TryExpandParameterPacks(E->getOperatorLoc(), E->getPackLoc(),
                                              Unexpanded,
                                              ShouldExpand, RetainExpansion,
                                              NumExpansions))
       return ExprError();
 
     // If we need to expand the pack, build a template argument from it and
     // expand that.
     if (ShouldExpand) {
       auto *Pack = E->getPack();
       if (auto *TTPD = dyn_cast<TemplateTypeParmDecl>(Pack)) {
         ArgStorage = getSema().Context.getPackExpansionType(
             getSema().Context.getTypeDeclType(TTPD), std::nullopt);
       } else if (auto *TTPD = dyn_cast<TemplateTemplateParmDecl>(Pack)) {
         ArgStorage = TemplateArgument(TemplateName(TTPD), std::nullopt);
       } else {
         auto *VD = cast<ValueDecl>(Pack);
         ExprResult DRE = getSema().BuildDeclRefExpr(
             VD, VD->getType().getNonLValueExprType(getSema().Context),
             VD->getType()->isReferenceType() ? VK_LValue : VK_PRValue,
             E->getPackLoc());
         if (DRE.isInvalid())
           return ExprError();
         ArgStorage = new (getSema().Context)
             PackExpansionExpr(getSema().Context.DependentTy, DRE.get(),
                               E->getPackLoc(), std::nullopt);
       }
       PackArgs = ArgStorage;
     }
   }
 
   // If we're not expanding the pack, just transform the decl.
   if (!PackArgs.size()) {
     auto *Pack = cast_or_null<NamedDecl>(
         getDerived().TransformDecl(E->getPackLoc(), E->getPack()));
     if (!Pack)
       return ExprError();
     return getDerived().RebuildSizeOfPackExpr(
         E->getOperatorLoc(), Pack, E->getPackLoc(), E->getRParenLoc(),
         std::nullopt, std::nullopt);
   }
 
   // Try to compute the result without performing a partial substitution.
   std::optional<unsigned> Result = 0;
   for (const TemplateArgument &Arg : PackArgs) {
     if (!Arg.isPackExpansion()) {
       Result = *Result + 1;
       continue;
     }
 
     TemplateArgumentLoc ArgLoc;
     InventTemplateArgumentLoc(Arg, ArgLoc);
 
     // Find the pattern of the pack expansion.
     SourceLocation Ellipsis;
     std::optional<unsigned> OrigNumExpansions;
     TemplateArgumentLoc Pattern =
         getSema().getTemplateArgumentPackExpansionPattern(ArgLoc, Ellipsis,
                                                           OrigNumExpansions);
 
     // Substitute under the pack expansion. Do not expand the pack (yet).
     TemplateArgumentLoc OutPattern;
     Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(getSema(), -1);
     if (getDerived().TransformTemplateArgument(Pattern, OutPattern,
                                                /*Uneval*/ true))
       return true;
 
     // See if we can determine the number of arguments from the result.
     std::optional<unsigned> NumExpansions =
         getSema().getFullyPackExpandedSize(OutPattern.getArgument());
     if (!NumExpansions) {
       // No: we must be in an alias template expansion, and we're going to need
       // to actually expand the packs.
       Result = std::nullopt;
       break;
     }
 
     Result = *Result + *NumExpansions;
   }
 
   // Common case: we could determine the number of expansions without
   // substituting.
   if (Result)
     return getDerived().RebuildSizeOfPackExpr(
         E->getOperatorLoc(), E->getPack(), E->getPackLoc(), E->getRParenLoc(),
         *Result, std::nullopt);
 
   TemplateArgumentListInfo TransformedPackArgs(E->getPackLoc(),
                                                E->getPackLoc());
   {
     TemporaryBase Rebase(*this, E->getPackLoc(), getBaseEntity());
     typedef TemplateArgumentLocInventIterator<
         Derived, const TemplateArgument*> PackLocIterator;
     if (TransformTemplateArguments(PackLocIterator(*this, PackArgs.begin()),
                                    PackLocIterator(*this, PackArgs.end()),
                                    TransformedPackArgs, /*Uneval*/true))
       return ExprError();
   }
 
   // Check whether we managed to fully-expand the pack.
   // FIXME: Is it possible for us to do so and not hit the early exit path?
   SmallVector<TemplateArgument, 8> Args;
   bool PartialSubstitution = false;
   for (auto &Loc : TransformedPackArgs.arguments()) {
     Args.push_back(Loc.getArgument());
     if (Loc.getArgument().isPackExpansion())
       PartialSubstitution = true;
   }
 
   if (PartialSubstitution)
     return getDerived().RebuildSizeOfPackExpr(
         E->getOperatorLoc(), E->getPack(), E->getPackLoc(), E->getRParenLoc(),
         std::nullopt, Args);
 
   return getDerived().RebuildSizeOfPackExpr(E->getOperatorLoc(), E->getPack(),
                                             E->getPackLoc(), E->getRParenLoc(),
                                             Args.size(), std::nullopt);
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformSubstNonTypeTemplateParmPackExpr(
                                           SubstNonTypeTemplateParmPackExpr *E) {
   // Default behavior is to do nothing with this transformation.
   return E;
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformSubstNonTypeTemplateParmExpr(
                                           SubstNonTypeTemplateParmExpr *E) {
   // Default behavior is to do nothing with this transformation.
   return E;
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformFunctionParmPackExpr(FunctionParmPackExpr *E) {
   // Default behavior is to do nothing with this transformation.
   return E;
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformMaterializeTemporaryExpr(
                                                   MaterializeTemporaryExpr *E) {
   return getDerived().TransformExpr(E->getSubExpr());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXFoldExpr(CXXFoldExpr *E) {
   UnresolvedLookupExpr *Callee = nullptr;
   if (Expr *OldCallee = E->getCallee()) {
     ExprResult CalleeResult = getDerived().TransformExpr(OldCallee);
     if (CalleeResult.isInvalid())
       return ExprError();
     Callee = cast<UnresolvedLookupExpr>(CalleeResult.get());
   }
 
   Expr *Pattern = E->getPattern();
 
   SmallVector<UnexpandedParameterPack, 2> Unexpanded;
   getSema().collectUnexpandedParameterPacks(Pattern, Unexpanded);
   assert(!Unexpanded.empty() && "Pack expansion without parameter packs?");
 
   // Determine whether the set of unexpanded parameter packs can and should
   // be expanded.
   bool Expand = true;
   bool RetainExpansion = false;
   std::optional<unsigned> OrigNumExpansions = E->getNumExpansions(),
                           NumExpansions = OrigNumExpansions;
   if (getDerived().TryExpandParameterPacks(E->getEllipsisLoc(),
                                            Pattern->getSourceRange(),
                                            Unexpanded,
                                            Expand, RetainExpansion,
                                            NumExpansions))
     return true;
 
   if (!Expand) {
     // Do not expand any packs here, just transform and rebuild a fold
     // expression.
     Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(getSema(), -1);
 
     ExprResult LHS =
         E->getLHS() ? getDerived().TransformExpr(E->getLHS()) : ExprResult();
     if (LHS.isInvalid())
       return true;
 
     ExprResult RHS =
         E->getRHS() ? getDerived().TransformExpr(E->getRHS()) : ExprResult();
     if (RHS.isInvalid())
       return true;
 
     if (!getDerived().AlwaysRebuild() &&
         LHS.get() == E->getLHS() && RHS.get() == E->getRHS())
       return E;
 
     return getDerived().RebuildCXXFoldExpr(
         Callee, E->getBeginLoc(), LHS.get(), E->getOperator(),
         E->getEllipsisLoc(), RHS.get(), E->getEndLoc(), NumExpansions);
   }
 
   // Formally a fold expression expands to nested parenthesized expressions.
   // Enforce this limit to avoid creating trees so deep we can't safely traverse
   // them.
   if (NumExpansions && SemaRef.getLangOpts().BracketDepth < NumExpansions) {
     SemaRef.Diag(E->getEllipsisLoc(),
                  clang::diag::err_fold_expression_limit_exceeded)
         << *NumExpansions << SemaRef.getLangOpts().BracketDepth
         << E->getSourceRange();
     SemaRef.Diag(E->getEllipsisLoc(), diag::note_bracket_depth);
     return ExprError();
   }
 
   // The transform has determined that we should perform an elementwise
   // expansion of the pattern. Do so.
   ExprResult Result = getDerived().TransformExpr(E->getInit());
   if (Result.isInvalid())
     return true;
   bool LeftFold = E->isLeftFold();
 
   // If we're retaining an expansion for a right fold, it is the innermost
   // component and takes the init (if any).
   if (!LeftFold && RetainExpansion) {
     ForgetPartiallySubstitutedPackRAII Forget(getDerived());
 
     ExprResult Out = getDerived().TransformExpr(Pattern);
     if (Out.isInvalid())
       return true;
 
     Result = getDerived().RebuildCXXFoldExpr(
         Callee, E->getBeginLoc(), Out.get(), E->getOperator(),
         E->getEllipsisLoc(), Result.get(), E->getEndLoc(), OrigNumExpansions);
     if (Result.isInvalid())
       return true;
   }
 
   for (unsigned I = 0; I != *NumExpansions; ++I) {
     Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(
         getSema(), LeftFold ? I : *NumExpansions - I - 1);
     ExprResult Out = getDerived().TransformExpr(Pattern);
     if (Out.isInvalid())
       return true;
 
     if (Out.get()->containsUnexpandedParameterPack()) {
       // We still have a pack; retain a pack expansion for this slice.
       Result = getDerived().RebuildCXXFoldExpr(
           Callee, E->getBeginLoc(), LeftFold ? Result.get() : Out.get(),
           E->getOperator(), E->getEllipsisLoc(),
           LeftFold ? Out.get() : Result.get(), E->getEndLoc(),
           OrigNumExpansions);
     } else if (Result.isUsable()) {
       // We've got down to a single element; build a binary operator.
       Expr *LHS = LeftFold ? Result.get() : Out.get();
       Expr *RHS = LeftFold ? Out.get() : Result.get();
       if (Callee) {
         UnresolvedSet<16> Functions;
         Functions.append(Callee->decls_begin(), Callee->decls_end());
         Result = getDerived().RebuildCXXOperatorCallExpr(
             BinaryOperator::getOverloadedOperator(E->getOperator()),
             E->getEllipsisLoc(), Callee->getBeginLoc(), Callee->requiresADL(),
             Functions, LHS, RHS);
       } else {
         Result = getDerived().RebuildBinaryOperator(E->getEllipsisLoc(),
                                                     E->getOperator(), LHS, RHS);
       }
     } else
       Result = Out;
 
     if (Result.isInvalid())
       return true;
   }
 
   // If we're retaining an expansion for a left fold, it is the outermost
   // component and takes the complete expansion so far as its init (if any).
   if (LeftFold && RetainExpansion) {
     ForgetPartiallySubstitutedPackRAII Forget(getDerived());
 
     ExprResult Out = getDerived().TransformExpr(Pattern);
     if (Out.isInvalid())
       return true;
 
     Result = getDerived().RebuildCXXFoldExpr(
         Callee, E->getBeginLoc(), Result.get(), E->getOperator(),
         E->getEllipsisLoc(), Out.get(), E->getEndLoc(), OrigNumExpansions);
     if (Result.isInvalid())
       return true;
   }
 
   // If we had no init and an empty pack, and we're not retaining an expansion,
   // then produce a fallback value or error.
   if (Result.isUnset())
     return getDerived().RebuildEmptyCXXFoldExpr(E->getEllipsisLoc(),
                                                 E->getOperator());
 
   return Result;
 }
 
 template <typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXParenListInitExpr(CXXParenListInitExpr *E) {
   SmallVector<Expr *, 4> TransformedInits;
   ArrayRef<Expr *> InitExprs = E->getInitExprs();
   if (TransformExprs(InitExprs.data(), InitExprs.size(), true,
                      TransformedInits))
     return ExprError();
 
   return getDerived().RebuildParenListExpr(E->getBeginLoc(), TransformedInits,
                                            E->getEndLoc());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCXXStdInitializerListExpr(
     CXXStdInitializerListExpr *E) {
   return getDerived().TransformExpr(E->getSubExpr());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformObjCStringLiteral(ObjCStringLiteral *E) {
   return SemaRef.MaybeBindToTemporary(E);
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformObjCBoolLiteralExpr(ObjCBoolLiteralExpr *E) {
   return E;
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformObjCBoxedExpr(ObjCBoxedExpr *E) {
   ExprResult SubExpr = getDerived().TransformExpr(E->getSubExpr());
   if (SubExpr.isInvalid())
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() &&
       SubExpr.get() == E->getSubExpr())
     return E;
 
   return getDerived().RebuildObjCBoxedExpr(E->getSourceRange(), SubExpr.get());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformObjCArrayLiteral(ObjCArrayLiteral *E) {
   // Transform each of the elements.
   SmallVector<Expr *, 8> Elements;
   bool ArgChanged = false;
   if (getDerived().TransformExprs(E->getElements(), E->getNumElements(),
                                   /*IsCall=*/false, Elements, &ArgChanged))
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() && !ArgChanged)
     return SemaRef.MaybeBindToTemporary(E);
 
   return getDerived().RebuildObjCArrayLiteral(E->getSourceRange(),
                                               Elements.data(),
                                               Elements.size());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformObjCDictionaryLiteral(
                                                     ObjCDictionaryLiteral *E) {
   // Transform each of the elements.
   SmallVector<ObjCDictionaryElement, 8> Elements;
   bool ArgChanged = false;
   for (unsigned I = 0, N = E->getNumElements(); I != N; ++I) {
     ObjCDictionaryElement OrigElement = E->getKeyValueElement(I);
 
     if (OrigElement.isPackExpansion()) {
       // This key/value element is a pack expansion.
       SmallVector<UnexpandedParameterPack, 2> Unexpanded;
       getSema().collectUnexpandedParameterPacks(OrigElement.Key, Unexpanded);
       getSema().collectUnexpandedParameterPacks(OrigElement.Value, Unexpanded);
       assert(!Unexpanded.empty() && "Pack expansion without parameter packs?");
 
       // Determine whether the set of unexpanded parameter packs can
       // and should be expanded.
       bool Expand = true;
       bool RetainExpansion = false;
       std::optional<unsigned> OrigNumExpansions = OrigElement.NumExpansions;
       std::optional<unsigned> NumExpansions = OrigNumExpansions;
       SourceRange PatternRange(OrigElement.Key->getBeginLoc(),
                                OrigElement.Value->getEndLoc());
       if (getDerived().TryExpandParameterPacks(OrigElement.EllipsisLoc,
                                                PatternRange, Unexpanded, Expand,
                                                RetainExpansion, NumExpansions))
         return ExprError();
 
       if (!Expand) {
         // The transform has determined that we should perform a simple
         // transformation on the pack expansion, producing another pack
         // expansion.
         Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(getSema(), -1);
         ExprResult Key = getDerived().TransformExpr(OrigElement.Key);
         if (Key.isInvalid())
           return ExprError();
 
         if (Key.get() != OrigElement.Key)
           ArgChanged = true;
 
         ExprResult Value = getDerived().TransformExpr(OrigElement.Value);
         if (Value.isInvalid())
           return ExprError();
 
         if (Value.get() != OrigElement.Value)
           ArgChanged = true;
 
         ObjCDictionaryElement Expansion = {
           Key.get(), Value.get(), OrigElement.EllipsisLoc, NumExpansions
         };
         Elements.push_back(Expansion);
         continue;
       }
 
       // Record right away that the argument was changed.  This needs
       // to happen even if the array expands to nothing.
       ArgChanged = true;
 
       // The transform has determined that we should perform an elementwise
       // expansion of the pattern. Do so.
       for (unsigned I = 0; I != *NumExpansions; ++I) {
         Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(getSema(), I);
         ExprResult Key = getDerived().TransformExpr(OrigElement.Key);
         if (Key.isInvalid())
           return ExprError();
 
         ExprResult Value = getDerived().TransformExpr(OrigElement.Value);
         if (Value.isInvalid())
           return ExprError();
 
         ObjCDictionaryElement Element = {
           Key.get(), Value.get(), SourceLocation(), NumExpansions
         };
 
         // If any unexpanded parameter packs remain, we still have a
         // pack expansion.
         // FIXME: Can this really happen?
         if (Key.get()->containsUnexpandedParameterPack() ||
             Value.get()->containsUnexpandedParameterPack())
           Element.EllipsisLoc = OrigElement.EllipsisLoc;
 
         Elements.push_back(Element);
       }
 
       // FIXME: Retain a pack expansion if RetainExpansion is true.
 
       // We've finished with this pack expansion.
       continue;
     }
 
     // Transform and check key.
     ExprResult Key = getDerived().TransformExpr(OrigElement.Key);
     if (Key.isInvalid())
       return ExprError();
 
     if (Key.get() != OrigElement.Key)
       ArgChanged = true;
 
     // Transform and check value.
     ExprResult Value
       = getDerived().TransformExpr(OrigElement.Value);
     if (Value.isInvalid())
       return ExprError();
 
     if (Value.get() != OrigElement.Value)
       ArgChanged = true;
 
     ObjCDictionaryElement Element = {Key.get(), Value.get(), SourceLocation(),
                                      std::nullopt};
     Elements.push_back(Element);
   }
 
   if (!getDerived().AlwaysRebuild() && !ArgChanged)
     return SemaRef.MaybeBindToTemporary(E);
 
   return getDerived().RebuildObjCDictionaryLiteral(E->getSourceRange(),
                                                    Elements);
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformObjCEncodeExpr(ObjCEncodeExpr *E) {
   TypeSourceInfo *EncodedTypeInfo
     = getDerived().TransformType(E->getEncodedTypeSourceInfo());
   if (!EncodedTypeInfo)
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() &&
       EncodedTypeInfo == E->getEncodedTypeSourceInfo())
     return E;
 
   return getDerived().RebuildObjCEncodeExpr(E->getAtLoc(),
                                             EncodedTypeInfo,
                                             E->getRParenLoc());
 }
 
 template<typename Derived>
 ExprResult TreeTransform<Derived>::
 TransformObjCIndirectCopyRestoreExpr(ObjCIndirectCopyRestoreExpr *E) {
   // This is a kind of implicit conversion, and it needs to get dropped
   // and recomputed for the same general reasons that ImplicitCastExprs
   // do, as well a more specific one: this expression is only valid when
   // it appears *immediately* as an argument expression.
   return getDerived().TransformExpr(E->getSubExpr());
 }
 
 template<typename Derived>
 ExprResult TreeTransform<Derived>::
 TransformObjCBridgedCastExpr(ObjCBridgedCastExpr *E) {
   TypeSourceInfo *TSInfo
     = getDerived().TransformType(E->getTypeInfoAsWritten());
   if (!TSInfo)
     return ExprError();
 
   ExprResult Result = getDerived().TransformExpr(E->getSubExpr());
   if (Result.isInvalid())
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() &&
       TSInfo == E->getTypeInfoAsWritten() &&
       Result.get() == E->getSubExpr())
     return E;
 
   return SemaRef.BuildObjCBridgedCast(E->getLParenLoc(), E->getBridgeKind(),
                                       E->getBridgeKeywordLoc(), TSInfo,
                                       Result.get());
 }
 
 template <typename Derived>
 ExprResult TreeTransform<Derived>::TransformObjCAvailabilityCheckExpr(
     ObjCAvailabilityCheckExpr *E) {
   return E;
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformObjCMessageExpr(ObjCMessageExpr *E) {
   // Transform arguments.
   bool ArgChanged = false;
   SmallVector<Expr*, 8> Args;
   Args.reserve(E->getNumArgs());
   if (getDerived().TransformExprs(E->getArgs(), E->getNumArgs(), false, Args,
                                   &ArgChanged))
     return ExprError();
 
   if (E->getReceiverKind() == ObjCMessageExpr::Class) {
     // Class message: transform the receiver type.
     TypeSourceInfo *ReceiverTypeInfo
       = getDerived().TransformType(E->getClassReceiverTypeInfo());
     if (!ReceiverTypeInfo)
       return ExprError();
 
     // If nothing changed, just retain the existing message send.
     if (!getDerived().AlwaysRebuild() &&
         ReceiverTypeInfo == E->getClassReceiverTypeInfo() && !ArgChanged)
       return SemaRef.MaybeBindToTemporary(E);
 
     // Build a new class message send.
     SmallVector<SourceLocation, 16> SelLocs;
     E->getSelectorLocs(SelLocs);
     return getDerived().RebuildObjCMessageExpr(ReceiverTypeInfo,
                                                E->getSelector(),
                                                SelLocs,
                                                E->getMethodDecl(),
                                                E->getLeftLoc(),
                                                Args,
                                                E->getRightLoc());
   }
   else if (E->getReceiverKind() == ObjCMessageExpr::SuperClass ||
            E->getReceiverKind() == ObjCMessageExpr::SuperInstance) {
     if (!E->getMethodDecl())
       return ExprError();
 
     // Build a new class message send to 'super'.
     SmallVector<SourceLocation, 16> SelLocs;
     E->getSelectorLocs(SelLocs);
     return getDerived().RebuildObjCMessageExpr(E->getSuperLoc(),
                                                E->getSelector(),
                                                SelLocs,
                                                E->getReceiverType(),
                                                E->getMethodDecl(),
                                                E->getLeftLoc(),
                                                Args,
                                                E->getRightLoc());
   }
 
   // Instance message: transform the receiver
   assert(E->getReceiverKind() == ObjCMessageExpr::Instance &&
          "Only class and instance messages may be instantiated");
   ExprResult Receiver
     = getDerived().TransformExpr(E->getInstanceReceiver());
   if (Receiver.isInvalid())
     return ExprError();
 
   // If nothing changed, just retain the existing message send.
   if (!getDerived().AlwaysRebuild() &&
       Receiver.get() == E->getInstanceReceiver() && !ArgChanged)
     return SemaRef.MaybeBindToTemporary(E);
 
   // Build a new instance message send.
   SmallVector<SourceLocation, 16> SelLocs;
   E->getSelectorLocs(SelLocs);
   return getDerived().RebuildObjCMessageExpr(Receiver.get(),
                                              E->getSelector(),
                                              SelLocs,
                                              E->getMethodDecl(),
                                              E->getLeftLoc(),
                                              Args,
                                              E->getRightLoc());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformObjCSelectorExpr(ObjCSelectorExpr *E) {
   return E;
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformObjCProtocolExpr(ObjCProtocolExpr *E) {
   return E;
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformObjCIvarRefExpr(ObjCIvarRefExpr *E) {
   // Transform the base expression.
   ExprResult Base = getDerived().TransformExpr(E->getBase());
   if (Base.isInvalid())
     return ExprError();
 
   // We don't need to transform the ivar; it will never change.
 
   // If nothing changed, just retain the existing expression.
   if (!getDerived().AlwaysRebuild() &&
       Base.get() == E->getBase())
     return E;
 
   return getDerived().RebuildObjCIvarRefExpr(Base.get(), E->getDecl(),
                                              E->getLocation(),
                                              E->isArrow(), E->isFreeIvar());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformObjCPropertyRefExpr(ObjCPropertyRefExpr *E) {
   // 'super' and types never change. Property never changes. Just
   // retain the existing expression.
   if (!E->isObjectReceiver())
     return E;
 
   // Transform the base expression.
   ExprResult Base = getDerived().TransformExpr(E->getBase());
   if (Base.isInvalid())
     return ExprError();
 
   // We don't need to transform the property; it will never change.
 
   // If nothing changed, just retain the existing expression.
   if (!getDerived().AlwaysRebuild() &&
       Base.get() == E->getBase())
     return E;
 
   if (E->isExplicitProperty())
     return getDerived().RebuildObjCPropertyRefExpr(Base.get(),
                                                    E->getExplicitProperty(),
                                                    E->getLocation());
 
   return getDerived().RebuildObjCPropertyRefExpr(Base.get(),
                                                  SemaRef.Context.PseudoObjectTy,
                                                  E->getImplicitPropertyGetter(),
                                                  E->getImplicitPropertySetter(),
                                                  E->getLocation());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformObjCSubscriptRefExpr(ObjCSubscriptRefExpr *E) {
   // Transform the base expression.
   ExprResult Base = getDerived().TransformExpr(E->getBaseExpr());
   if (Base.isInvalid())
     return ExprError();
 
   // Transform the key expression.
   ExprResult Key = getDerived().TransformExpr(E->getKeyExpr());
   if (Key.isInvalid())
     return ExprError();
 
   // If nothing changed, just retain the existing expression.
   if (!getDerived().AlwaysRebuild() &&
       Key.get() == E->getKeyExpr() && Base.get() == E->getBaseExpr())
     return E;
 
   return getDerived().RebuildObjCSubscriptRefExpr(E->getRBracket(),
                                                   Base.get(), Key.get(),
                                                   E->getAtIndexMethodDecl(),
                                                   E->setAtIndexMethodDecl());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformObjCIsaExpr(ObjCIsaExpr *E) {
   // Transform the base expression.
   ExprResult Base = getDerived().TransformExpr(E->getBase());
   if (Base.isInvalid())
     return ExprError();
 
   // If nothing changed, just retain the existing expression.
   if (!getDerived().AlwaysRebuild() &&
       Base.get() == E->getBase())
     return E;
 
   return getDerived().RebuildObjCIsaExpr(Base.get(), E->getIsaMemberLoc(),
                                          E->getOpLoc(),
                                          E->isArrow());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformShuffleVectorExpr(ShuffleVectorExpr *E) {
   bool ArgumentChanged = false;
   SmallVector<Expr*, 8> SubExprs;
   SubExprs.reserve(E->getNumSubExprs());
   if (getDerived().TransformExprs(E->getSubExprs(), E->getNumSubExprs(), false,
                                   SubExprs, &ArgumentChanged))
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() &&
       !ArgumentChanged)
     return E;
 
   return getDerived().RebuildShuffleVectorExpr(E->getBuiltinLoc(),
                                                SubExprs,
                                                E->getRParenLoc());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformConvertVectorExpr(ConvertVectorExpr *E) {
   ExprResult SrcExpr = getDerived().TransformExpr(E->getSrcExpr());
   if (SrcExpr.isInvalid())
     return ExprError();
 
   TypeSourceInfo *Type = getDerived().TransformType(E->getTypeSourceInfo());
   if (!Type)
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() &&
       Type == E->getTypeSourceInfo() &&
       SrcExpr.get() == E->getSrcExpr())
     return E;
 
   return getDerived().RebuildConvertVectorExpr(E->getBuiltinLoc(),
                                                SrcExpr.get(), Type,
                                                E->getRParenLoc());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformBlockExpr(BlockExpr *E) {
   BlockDecl *oldBlock = E->getBlockDecl();
 
   SemaRef.ActOnBlockStart(E->getCaretLocation(), /*Scope=*/nullptr);
   BlockScopeInfo *blockScope = SemaRef.getCurBlock();
 
   blockScope->TheDecl->setIsVariadic(oldBlock->isVariadic());
   blockScope->TheDecl->setBlockMissingReturnType(
                          oldBlock->blockMissingReturnType());
 
   SmallVector<ParmVarDecl*, 4> params;
   SmallVector<QualType, 4> paramTypes;
 
   const FunctionProtoType *exprFunctionType = E->getFunctionType();
 
   // Parameter substitution.
   Sema::ExtParameterInfoBuilder extParamInfos;
   if (getDerived().TransformFunctionTypeParams(
           E->getCaretLocation(), oldBlock->parameters(), nullptr,
           exprFunctionType->getExtParameterInfosOrNull(), paramTypes, &params,
           extParamInfos)) {
     getSema().ActOnBlockError(E->getCaretLocation(), /*Scope=*/nullptr);
     return ExprError();
   }
 
   QualType exprResultType =
       getDerived().TransformType(exprFunctionType->getReturnType());
 
   auto epi = exprFunctionType->getExtProtoInfo();
   epi.ExtParameterInfos = extParamInfos.getPointerOrNull(paramTypes.size());
 
   QualType functionType =
     getDerived().RebuildFunctionProtoType(exprResultType, paramTypes, epi);
   blockScope->FunctionType = functionType;
 
   // Set the parameters on the block decl.
   if (!params.empty())
     blockScope->TheDecl->setParams(params);
 
   if (!oldBlock->blockMissingReturnType()) {
     blockScope->HasImplicitReturnType = false;
     blockScope->ReturnType = exprResultType;
   }
 
   // Transform the body
   StmtResult body = getDerived().TransformStmt(E->getBody());
   if (body.isInvalid()) {
     getSema().ActOnBlockError(E->getCaretLocation(), /*Scope=*/nullptr);
     return ExprError();
   }
 
 #ifndef NDEBUG
   // In builds with assertions, make sure that we captured everything we
   // captured before.
   if (!SemaRef.getDiagnostics().hasErrorOccurred()) {
     for (const auto &I : oldBlock->captures()) {
       VarDecl *oldCapture = I.getVariable();
 
       // Ignore parameter packs.
       if (oldCapture->isParameterPack())
         continue;
 
       VarDecl *newCapture =
         cast<VarDecl>(getDerived().TransformDecl(E->getCaretLocation(),
                                                  oldCapture));
       assert(blockScope->CaptureMap.count(newCapture));
     }
 
     // The this pointer may not be captured by the instantiated block, even when
     // it's captured by the original block, if the expression causing the
     // capture is in the discarded branch of a constexpr if statement.
     assert((!blockScope->isCXXThisCaptured() || oldBlock->capturesCXXThis()) &&
            "this pointer isn't captured in the old block");
   }
 #endif
 
   return SemaRef.ActOnBlockStmtExpr(E->getCaretLocation(), body.get(),
                                     /*Scope=*/nullptr);
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformAsTypeExpr(AsTypeExpr *E) {
   ExprResult SrcExpr = getDerived().TransformExpr(E->getSrcExpr());
   if (SrcExpr.isInvalid())
     return ExprError();
 
   QualType Type = getDerived().TransformType(E->getType());
 
   return SemaRef.BuildAsTypeExpr(SrcExpr.get(), Type, E->getBuiltinLoc(),
                                  E->getRParenLoc());
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformAtomicExpr(AtomicExpr *E) {
   bool ArgumentChanged = false;
   SmallVector<Expr*, 8> SubExprs;
   SubExprs.reserve(E->getNumSubExprs());
   if (getDerived().TransformExprs(E->getSubExprs(), E->getNumSubExprs(), false,
                                   SubExprs, &ArgumentChanged))
     return ExprError();
 
   if (!getDerived().AlwaysRebuild() &&
       !ArgumentChanged)
     return E;
 
   return getDerived().RebuildAtomicExpr(E->getBuiltinLoc(), SubExprs,
                                         E->getOp(), E->getRParenLoc());
 }
 
 //===----------------------------------------------------------------------===//
 // Type reconstruction
 //===----------------------------------------------------------------------===//
 
 template<typename Derived>
 QualType TreeTransform<Derived>::RebuildPointerType(QualType PointeeType,
                                                     SourceLocation Star) {
   return SemaRef.BuildPointerType(PointeeType, Star,
                                   getDerived().getBaseEntity());
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::RebuildBlockPointerType(QualType PointeeType,
                                                          SourceLocation Star) {
   return SemaRef.BuildBlockPointerType(PointeeType, Star,
                                        getDerived().getBaseEntity());
 }
 
 template<typename Derived>
 QualType
 TreeTransform<Derived>::RebuildReferenceType(QualType ReferentType,
                                              bool WrittenAsLValue,
                                              SourceLocation Sigil) {
   return SemaRef.BuildReferenceType(ReferentType, WrittenAsLValue,
                                     Sigil, getDerived().getBaseEntity());
 }
 
 template<typename Derived>
 QualType
 TreeTransform<Derived>::RebuildMemberPointerType(QualType PointeeType,
                                                  QualType ClassType,
                                                  SourceLocation Sigil) {
   return SemaRef.BuildMemberPointerType(PointeeType, ClassType, Sigil,
                                         getDerived().getBaseEntity());
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::RebuildObjCTypeParamType(
            const ObjCTypeParamDecl *Decl,
            SourceLocation ProtocolLAngleLoc,
            ArrayRef<ObjCProtocolDecl *> Protocols,
            ArrayRef<SourceLocation> ProtocolLocs,
            SourceLocation ProtocolRAngleLoc) {
   return SemaRef.BuildObjCTypeParamType(Decl,
                                         ProtocolLAngleLoc, Protocols,
                                         ProtocolLocs, ProtocolRAngleLoc,
                                         /*FailOnError=*/true);
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::RebuildObjCObjectType(
            QualType BaseType,
            SourceLocation Loc,
            SourceLocation TypeArgsLAngleLoc,
            ArrayRef<TypeSourceInfo *> TypeArgs,
            SourceLocation TypeArgsRAngleLoc,
            SourceLocation ProtocolLAngleLoc,
            ArrayRef<ObjCProtocolDecl *> Protocols,
            ArrayRef<SourceLocation> ProtocolLocs,
            SourceLocation ProtocolRAngleLoc) {
   return SemaRef.BuildObjCObjectType(BaseType, Loc, TypeArgsLAngleLoc, TypeArgs,
                                      TypeArgsRAngleLoc, ProtocolLAngleLoc,
                                      Protocols, ProtocolLocs, ProtocolRAngleLoc,
                                      /*FailOnError=*/true,
                                      /*Rebuilding=*/true);
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::RebuildObjCObjectPointerType(
            QualType PointeeType,
            SourceLocation Star) {
   return SemaRef.Context.getObjCObjectPointerType(PointeeType);
 }
 
 template<typename Derived>
 QualType
 TreeTransform<Derived>::RebuildArrayType(QualType ElementType,
                                          ArrayType::ArraySizeModifier SizeMod,
                                          const llvm::APInt *Size,
                                          Expr *SizeExpr,
                                          unsigned IndexTypeQuals,
                                          SourceRange BracketsRange) {
   if (SizeExpr || !Size)
     return SemaRef.BuildArrayType(ElementType, SizeMod, SizeExpr,
                                   IndexTypeQuals, BracketsRange,
                                   getDerived().getBaseEntity());
 
   QualType Types[] = {
     SemaRef.Context.UnsignedCharTy, SemaRef.Context.UnsignedShortTy,
     SemaRef.Context.UnsignedIntTy, SemaRef.Context.UnsignedLongTy,
     SemaRef.Context.UnsignedLongLongTy, SemaRef.Context.UnsignedInt128Ty
   };
   QualType SizeType;
   for (const auto &T : Types)
     if (Size->getBitWidth() == SemaRef.Context.getIntWidth(T)) {
       SizeType = T;
       break;
     }
 
   // Note that we can return a VariableArrayType here in the case where
   // the element type was a dependent VariableArrayType.
   IntegerLiteral *ArraySize
       = IntegerLiteral::Create(SemaRef.Context, *Size, SizeType,
                                /*FIXME*/BracketsRange.getBegin());
   return SemaRef.BuildArrayType(ElementType, SizeMod, ArraySize,
                                 IndexTypeQuals, BracketsRange,
                                 getDerived().getBaseEntity());
 }
 
 template<typename Derived>
 QualType
 TreeTransform<Derived>::RebuildConstantArrayType(QualType ElementType,
                                                  ArrayType::ArraySizeModifier SizeMod,
                                                  const llvm::APInt &Size,
                                                  Expr *SizeExpr,
                                                  unsigned IndexTypeQuals,
                                                  SourceRange BracketsRange) {
   return getDerived().RebuildArrayType(ElementType, SizeMod, &Size, SizeExpr,
                                         IndexTypeQuals, BracketsRange);
 }
 
 template<typename Derived>
 QualType
 TreeTransform<Derived>::RebuildIncompleteArrayType(QualType ElementType,
                                           ArrayType::ArraySizeModifier SizeMod,
                                                  unsigned IndexTypeQuals,
                                                    SourceRange BracketsRange) {
   return getDerived().RebuildArrayType(ElementType, SizeMod, nullptr, nullptr,
                                        IndexTypeQuals, BracketsRange);
 }
 
 template<typename Derived>
 QualType
 TreeTransform<Derived>::RebuildVariableArrayType(QualType ElementType,
                                           ArrayType::ArraySizeModifier SizeMod,
                                                  Expr *SizeExpr,
                                                  unsigned IndexTypeQuals,
                                                  SourceRange BracketsRange) {
   return getDerived().RebuildArrayType(ElementType, SizeMod, nullptr,
                                        SizeExpr,
                                        IndexTypeQuals, BracketsRange);
 }
 
 template<typename Derived>
 QualType
 TreeTransform<Derived>::RebuildDependentSizedArrayType(QualType ElementType,
                                           ArrayType::ArraySizeModifier SizeMod,
                                                        Expr *SizeExpr,
                                                        unsigned IndexTypeQuals,
                                                    SourceRange BracketsRange) {
   return getDerived().RebuildArrayType(ElementType, SizeMod, nullptr,
                                        SizeExpr,
                                        IndexTypeQuals, BracketsRange);
 }
 
 template <typename Derived>
 QualType TreeTransform<Derived>::RebuildDependentAddressSpaceType(
     QualType PointeeType, Expr *AddrSpaceExpr, SourceLocation AttributeLoc) {
   return SemaRef.BuildAddressSpaceAttr(PointeeType, AddrSpaceExpr,
                                           AttributeLoc);
 }
 
 template <typename Derived>
 QualType
 TreeTransform<Derived>::RebuildVectorType(QualType ElementType,
                                           unsigned NumElements,
                                           VectorType::VectorKind VecKind) {
   // FIXME: semantic checking!
   return SemaRef.Context.getVectorType(ElementType, NumElements, VecKind);
 }
 
 template <typename Derived>
 QualType TreeTransform<Derived>::RebuildDependentVectorType(
     QualType ElementType, Expr *SizeExpr, SourceLocation AttributeLoc,
     VectorType::VectorKind VecKind) {
   return SemaRef.BuildVectorType(ElementType, SizeExpr, AttributeLoc);
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::RebuildExtVectorType(QualType ElementType,
                                                       unsigned NumElements,
                                                  SourceLocation AttributeLoc) {
   llvm::APInt numElements(SemaRef.Context.getIntWidth(SemaRef.Context.IntTy),
                           NumElements, true);
   IntegerLiteral *VectorSize
     = IntegerLiteral::Create(SemaRef.Context, numElements, SemaRef.Context.IntTy,
                              AttributeLoc);
   return SemaRef.BuildExtVectorType(ElementType, VectorSize, AttributeLoc);
 }
 
 template<typename Derived>
 QualType
 TreeTransform<Derived>::RebuildDependentSizedExtVectorType(QualType ElementType,
                                                            Expr *SizeExpr,
                                                   SourceLocation AttributeLoc) {
   return SemaRef.BuildExtVectorType(ElementType, SizeExpr, AttributeLoc);
 }
 
 template <typename Derived>
 QualType TreeTransform<Derived>::RebuildConstantMatrixType(
     QualType ElementType, unsigned NumRows, unsigned NumColumns) {
   return SemaRef.Context.getConstantMatrixType(ElementType, NumRows,
                                                NumColumns);
 }
 
 template <typename Derived>
 QualType TreeTransform<Derived>::RebuildDependentSizedMatrixType(
     QualType ElementType, Expr *RowExpr, Expr *ColumnExpr,
     SourceLocation AttributeLoc) {
   return SemaRef.BuildMatrixType(ElementType, RowExpr, ColumnExpr,
                                  AttributeLoc);
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::RebuildFunctionProtoType(
     QualType T,
     MutableArrayRef<QualType> ParamTypes,
     const FunctionProtoType::ExtProtoInfo &EPI) {
   return SemaRef.BuildFunctionType(T, ParamTypes,
                                    getDerived().getBaseLocation(),
                                    getDerived().getBaseEntity(),
                                    EPI);
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::RebuildFunctionNoProtoType(QualType T) {
   return SemaRef.Context.getFunctionNoProtoType(T);
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::RebuildUnresolvedUsingType(SourceLocation Loc,
                                                             Decl *D) {
   assert(D && "no decl found");
   if (D->isInvalidDecl()) return QualType();
 
   // FIXME: Doesn't account for ObjCInterfaceDecl!
   if (auto *UPD = dyn_cast<UsingPackDecl>(D)) {
     // A valid resolved using typename pack expansion decl can have multiple
     // UsingDecls, but they must each have exactly one type, and it must be
     // the same type in every case. But we must have at least one expansion!
     if (UPD->expansions().empty()) {
       getSema().Diag(Loc, diag::err_using_pack_expansion_empty)
           << UPD->isCXXClassMember() << UPD;
       return QualType();
     }
 
     // We might still have some unresolved types. Try to pick a resolved type
     // if we can. The final instantiation will check that the remaining
     // unresolved types instantiate to the type we pick.
     QualType FallbackT;
     QualType T;
     for (auto *E : UPD->expansions()) {
       QualType ThisT = RebuildUnresolvedUsingType(Loc, E);
       if (ThisT.isNull())
         continue;
       else if (ThisT->getAs<UnresolvedUsingType>())
         FallbackT = ThisT;
       else if (T.isNull())
         T = ThisT;
       else
         assert(getSema().Context.hasSameType(ThisT, T) &&
                "mismatched resolved types in using pack expansion");
     }
     return T.isNull() ? FallbackT : T;
   } else if (auto *Using = dyn_cast<UsingDecl>(D)) {
     assert(Using->hasTypename() &&
            "UnresolvedUsingTypenameDecl transformed to non-typename using");
 
     // A valid resolved using typename decl points to exactly one type decl.
     assert(++Using->shadow_begin() == Using->shadow_end());
 
     UsingShadowDecl *Shadow = *Using->shadow_begin();
     if (SemaRef.DiagnoseUseOfDecl(Shadow->getTargetDecl(), Loc))
       return QualType();
     return SemaRef.Context.getUsingType(
         Shadow, SemaRef.Context.getTypeDeclType(
                     cast<TypeDecl>(Shadow->getTargetDecl())));
   } else {
     assert(isa<UnresolvedUsingTypenameDecl>(D) &&
            "UnresolvedUsingTypenameDecl transformed to non-using decl");
     return SemaRef.Context.getTypeDeclType(
         cast<UnresolvedUsingTypenameDecl>(D));
   }
 }
 
 template <typename Derived>
 QualType TreeTransform<Derived>::RebuildTypeOfExprType(Expr *E, SourceLocation,
                                                        TypeOfKind Kind) {
   return SemaRef.BuildTypeofExprType(E, Kind);
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::RebuildTypeOfType(QualType Underlying,
                                                    TypeOfKind Kind) {
   return SemaRef.Context.getTypeOfType(Underlying, Kind);
 }
 
 template <typename Derived>
 QualType TreeTransform<Derived>::RebuildDecltypeType(Expr *E, SourceLocation) {
   return SemaRef.BuildDecltypeType(E);
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::RebuildUnaryTransformType(QualType BaseType,
                                             UnaryTransformType::UTTKind UKind,
                                             SourceLocation Loc) {
   return SemaRef.BuildUnaryTransformType(BaseType, UKind, Loc);
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::RebuildTemplateSpecializationType(
                                                       TemplateName Template,
                                              SourceLocation TemplateNameLoc,
                                      TemplateArgumentListInfo &TemplateArgs) {
   return SemaRef.CheckTemplateIdType(Template, TemplateNameLoc, TemplateArgs);
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::RebuildAtomicType(QualType ValueType,
                                                    SourceLocation KWLoc) {
   return SemaRef.BuildAtomicType(ValueType, KWLoc);
 }
 
 template<typename Derived>
 QualType TreeTransform<Derived>::RebuildPipeType(QualType ValueType,
                                                  SourceLocation KWLoc,
                                                  bool isReadPipe) {
   return isReadPipe ? SemaRef.BuildReadPipeType(ValueType, KWLoc)
                     : SemaRef.BuildWritePipeType(ValueType, KWLoc);
 }
 
 template <typename Derived>
 QualType TreeTransform<Derived>::RebuildBitIntType(bool IsUnsigned,
                                                    unsigned NumBits,
                                                    SourceLocation Loc) {
   llvm::APInt NumBitsAP(SemaRef.Context.getIntWidth(SemaRef.Context.IntTy),
                         NumBits, true);
   IntegerLiteral *Bits = IntegerLiteral::Create(SemaRef.Context, NumBitsAP,
                                                 SemaRef.Context.IntTy, Loc);
   return SemaRef.BuildBitIntType(IsUnsigned, Bits, Loc);
 }
 
 template <typename Derived>
 QualType TreeTransform<Derived>::RebuildDependentBitIntType(
     bool IsUnsigned, Expr *NumBitsExpr, SourceLocation Loc) {
   return SemaRef.BuildBitIntType(IsUnsigned, NumBitsExpr, Loc);
 }
 
 template<typename Derived>
 TemplateName
 TreeTransform<Derived>::RebuildTemplateName(CXXScopeSpec &SS,
                                             bool TemplateKW,
                                             TemplateDecl *Template) {
   return SemaRef.Context.getQualifiedTemplateName(SS.getScopeRep(), TemplateKW,
                                                   TemplateName(Template));
 }
 
 template<typename Derived>
 TemplateName
 TreeTransform<Derived>::RebuildTemplateName(CXXScopeSpec &SS,
                                             SourceLocation TemplateKWLoc,
                                             const IdentifierInfo &Name,
                                             SourceLocation NameLoc,
                                             QualType ObjectType,
                                             NamedDecl *FirstQualifierInScope,
                                             bool AllowInjectedClassName) {
   UnqualifiedId TemplateName;
   TemplateName.setIdentifier(&Name, NameLoc);
   Sema::TemplateTy Template;
   getSema().ActOnTemplateName(/*Scope=*/nullptr, SS, TemplateKWLoc,
                               TemplateName, ParsedType::make(ObjectType),
                               /*EnteringContext=*/false, Template,
                               AllowInjectedClassName);
   return Template.get();
 }
 
 template<typename Derived>
 TemplateName
 TreeTransform<Derived>::RebuildTemplateName(CXXScopeSpec &SS,
                                             SourceLocation TemplateKWLoc,
                                             OverloadedOperatorKind Operator,
                                             SourceLocation NameLoc,
                                             QualType ObjectType,
                                             bool AllowInjectedClassName) {
   UnqualifiedId Name;
   // FIXME: Bogus location information.
   SourceLocation SymbolLocations[3] = { NameLoc, NameLoc, NameLoc };
   Name.setOperatorFunctionId(NameLoc, Operator, SymbolLocations);
   Sema::TemplateTy Template;
   getSema().ActOnTemplateName(
       /*Scope=*/nullptr, SS, TemplateKWLoc, Name, ParsedType::make(ObjectType),
       /*EnteringContext=*/false, Template, AllowInjectedClassName);
   return Template.get();
 }
 
 template <typename Derived>
 ExprResult TreeTransform<Derived>::RebuildCXXOperatorCallExpr(
     OverloadedOperatorKind Op, SourceLocation OpLoc, SourceLocation CalleeLoc,
     bool RequiresADL, const UnresolvedSetImpl &Functions, Expr *First,
     Expr *Second) {
   bool isPostIncDec = Second && (Op == OO_PlusPlus || Op == OO_MinusMinus);
 
   if (First->getObjectKind() == OK_ObjCProperty) {
     BinaryOperatorKind Opc = BinaryOperator::getOverloadedOpcode(Op);
     if (BinaryOperator::isAssignmentOp(Opc))
       return SemaRef.checkPseudoObjectAssignment(/*Scope=*/nullptr, OpLoc, Opc,
                                                  First, Second);
     ExprResult Result = SemaRef.CheckPlaceholderExpr(First);
     if (Result.isInvalid())
       return ExprError();
     First = Result.get();
   }
 
   if (Second && Second->getObjectKind() == OK_ObjCProperty) {
     ExprResult Result = SemaRef.CheckPlaceholderExpr(Second);
     if (Result.isInvalid())
       return ExprError();
     Second = Result.get();
   }
 
   // Determine whether this should be a builtin operation.
   if (Op == OO_Subscript) {
     if (!First->getType()->isOverloadableType() &&
         !Second->getType()->isOverloadableType())
       return getSema().CreateBuiltinArraySubscriptExpr(First, CalleeLoc, Second,
                                                        OpLoc);
   } else if (Op == OO_Arrow) {
     // It is possible that the type refers to a RecoveryExpr created earlier
     // in the tree transformation.
     if (First->getType()->isDependentType())
       return ExprError();
     // -> is never a builtin operation.
     return SemaRef.BuildOverloadedArrowExpr(nullptr, First, OpLoc);
   } else if (Second == nullptr || isPostIncDec) {
     if (!First->getType()->isOverloadableType() ||
         (Op == OO_Amp && getSema().isQualifiedMemberAccess(First))) {
       // The argument is not of overloadable type, or this is an expression
       // of the form &Class::member, so try to create a built-in unary
       // operation.
       UnaryOperatorKind Opc
         = UnaryOperator::getOverloadedOpcode(Op, isPostIncDec);
 
       return getSema().CreateBuiltinUnaryOp(OpLoc, Opc, First);
     }
   } else {
     if (!First->getType()->isOverloadableType() &&
         !Second->getType()->isOverloadableType()) {
       // Neither of the arguments is an overloadable type, so try to
       // create a built-in binary operation.
       BinaryOperatorKind Opc = BinaryOperator::getOverloadedOpcode(Op);
       ExprResult Result
         = SemaRef.CreateBuiltinBinOp(OpLoc, Opc, First, Second);
       if (Result.isInvalid())
         return ExprError();
 
       return Result;
     }
   }
 
   // Add any functions found via argument-dependent lookup.
   Expr *Args[2] = { First, Second };
   unsigned NumArgs = 1 + (Second != nullptr);
 
   // Create the overloaded operator invocation for unary operators.
   if (NumArgs == 1 || isPostIncDec) {
     UnaryOperatorKind Opc
       = UnaryOperator::getOverloadedOpcode(Op, isPostIncDec);
     return SemaRef.CreateOverloadedUnaryOp(OpLoc, Opc, Functions, First,
                                            RequiresADL);
   }
 
   // Create the overloaded operator invocation for binary operators.
   BinaryOperatorKind Opc = BinaryOperator::getOverloadedOpcode(Op);
   ExprResult Result = SemaRef.CreateOverloadedBinOp(
       OpLoc, Opc, Functions, Args[0], Args[1], RequiresADL);
   if (Result.isInvalid())
     return ExprError();
 
   return Result;
 }
 
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::RebuildCXXPseudoDestructorExpr(Expr *Base,
                                                      SourceLocation OperatorLoc,
                                                        bool isArrow,
                                                        CXXScopeSpec &SS,
                                                      TypeSourceInfo *ScopeType,
                                                        SourceLocation CCLoc,
                                                        SourceLocation TildeLoc,
                                         PseudoDestructorTypeStorage Destroyed) {
   QualType BaseType = Base->getType();
   if (Base->isTypeDependent() || Destroyed.getIdentifier() ||
       (!isArrow && !BaseType->getAs<RecordType>()) ||
       (isArrow && BaseType->getAs<PointerType>() &&
        !BaseType->castAs<PointerType>()->getPointeeType()
                                               ->template getAs<RecordType>())){
     // This pseudo-destructor expression is still a pseudo-destructor.
     return SemaRef.BuildPseudoDestructorExpr(
         Base, OperatorLoc, isArrow ? tok::arrow : tok::period, SS, ScopeType,
         CCLoc, TildeLoc, Destroyed);
   }
 
   TypeSourceInfo *DestroyedType = Destroyed.getTypeSourceInfo();
   DeclarationName Name(SemaRef.Context.DeclarationNames.getCXXDestructorName(
                  SemaRef.Context.getCanonicalType(DestroyedType->getType())));
   DeclarationNameInfo NameInfo(Name, Destroyed.getLocation());
   NameInfo.setNamedTypeInfo(DestroyedType);
 
   // The scope type is now known to be a valid nested name specifier
   // component. Tack it on to the end of the nested name specifier.
   if (ScopeType) {
     if (!ScopeType->getType()->getAs<TagType>()) {
       getSema().Diag(ScopeType->getTypeLoc().getBeginLoc(),
                      diag::err_expected_class_or_namespace)
           << ScopeType->getType() << getSema().getLangOpts().CPlusPlus;
       return ExprError();
     }
     SS.Extend(SemaRef.Context, SourceLocation(), ScopeType->getTypeLoc(),
               CCLoc);
   }
 
   SourceLocation TemplateKWLoc; // FIXME: retrieve it from caller.
   return getSema().BuildMemberReferenceExpr(Base, BaseType,
                                             OperatorLoc, isArrow,
                                             SS, TemplateKWLoc,
                                             /*FIXME: FirstQualifier*/ nullptr,
                                             NameInfo,
                                             /*TemplateArgs*/ nullptr,
                                             /*S*/nullptr);
 }
 
 template<typename Derived>
 StmtResult
 TreeTransform<Derived>::TransformCapturedStmt(CapturedStmt *S) {
   SourceLocation Loc = S->getBeginLoc();
   CapturedDecl *CD = S->getCapturedDecl();
   unsigned NumParams = CD->getNumParams();
   unsigned ContextParamPos = CD->getContextParamPosition();
   SmallVector<Sema::CapturedParamNameType, 4> Params;
   for (unsigned I = 0; I < NumParams; ++I) {
     if (I != ContextParamPos) {
       Params.push_back(
              std::make_pair(
                   CD->getParam(I)->getName(),
                   getDerived().TransformType(CD->getParam(I)->getType())));
     } else {
       Params.push_back(std::make_pair(StringRef(), QualType()));
     }
   }
   getSema().ActOnCapturedRegionStart(Loc, /*CurScope*/nullptr,
                                      S->getCapturedRegionKind(), Params);
   StmtResult Body;
   {
     Sema::CompoundScopeRAII CompoundScope(getSema());
     Body = getDerived().TransformStmt(S->getCapturedStmt());
   }
 
   if (Body.isInvalid()) {
     getSema().ActOnCapturedRegionError();
     return StmtError();
   }
 
   return getSema().ActOnCapturedRegionEnd(Body.get());
 }
 
 } // end namespace clang
 
 #endif // LLVM_CLANG_LIB_SEMA_TREETRANSFORM_H