diff --git a/contrib/llvm-project/clang/include/clang/Sema/Sema.h b/contrib/llvm-project/clang/include/clang/Sema/Sema.h
index 681a76dfa56a..53257a1bb028 100644
--- a/contrib/llvm-project/clang/include/clang/Sema/Sema.h
+++ b/contrib/llvm-project/clang/include/clang/Sema/Sema.h
@@ -1,13632 +1,13635 @@
 //===--- 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/Optional.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 <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 funciton, 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.
   ExternalSemaSource *ExternalSource;
 
   ///Whether Sema has generated a multiplexer and has to delete it.
   bool isMultiplexExternalSource;
 
   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)
   };
 
   // #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;
 
   // 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;
   }
 
   // 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::SetVector<Expr *, SmallVector<Expr *, 4>,
                                              llvm::SmallPtrSet<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;
 
   ArrayRef<sema::FunctionScopeInfo*> getFunctionScopes() const {
     return llvm::makeArrayRef(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::makeArrayRef(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<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;
     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;
 
   public:
     DelayedDiagnostics() : CurPool(nullptr) {}
 
     /// 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() {
     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) {
       S.PushFunctionScope();
       S.PushExpressionEvaluationContext(
           Sema::ExpressionEvaluationContext::PotentiallyEvaluated);
       if (auto *FD = dyn_cast<FunctionDecl>(DC))
         FD->setWillHaveBody(true);
       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.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::experimental" namespace, where the experimental parts
   /// of the standard library resides.
   NamespaceDecl *StdExperimentalNamespaceCache;
 
   /// 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 namespace where coroutine components are defined. In standard,
   /// they are defined in std namespace. And in the previous implementation,
   /// they are defined in std::experimental namespace.
   NamespaceDecl *CoroTraitsNamespaceCache;
 
   /// The C++ "type_info" declaration, which is defined in \<typeinfo>.
   RecordDecl *CXXTypeInfoDecl;
 
   /// The MSVC "_GUID" struct, which is defined in MSVC header files.
   RecordDecl *MSVCGuidDecl;
 
   /// 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 function.
     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;
 
     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) {}
 
     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);
     }
 
     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(ValueDecl *VD);
 
   /// 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;
 
 private:
   std::unique_ptr<sema::RISCVIntrinsicManager> RVIntrinsicManager;
 
   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; }
 
   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 = typename std::enable_if<
                               !std::is_lvalue_reference<T>::value>::type>
     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,
                           FunctionDecl *Fn, Sema &S);
     SemaDiagnosticBuilder(SemaDiagnosticBuilder &&D);
     SemaDiagnosticBuilder(const SemaDiagnosticBuilder &) = default;
     ~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 = typename std::enable_if<
                               !std::is_lvalue_reference<T>::value>::type>
     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;
     FunctionDecl *Fn;
     bool ShowCallStack;
 
     // Invariant: At most one of these Optionals has a value.
     // FIXME: Switch these to a Variant once that exists.
     llvm::Optional<ImmediateDiagBuilder> ImmediateDiag;
     llvm::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;
     bool IsPartition = false;
     bool ImplicitGlobalModuleFragment = false;
     VisibleModuleSet OuterVisibleModules;
   };
   /// The modules we're currently parsing.
   llvm::SmallVector<ModuleScope, 16> ModuleScopes;
   /// The global module fragment of the current translation unit.
   clang::Module *GlobalModuleFragment = nullptr;
 
   /// The modules we imported directly.
   llvm::SmallPtrSet<clang::Module *, 8> DirectModuleImports;
 
   /// Namespace definitions that we will export when they finish.
   llvm::SmallPtrSet<const NamespaceDecl*, 8> DeferredExportedNamespaces;
 
   /// 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 global module.
   Module *PushGlobalModuleFragment(SourceLocation BeginLoc, bool IsImplicit);
   /// Leave the scope of the global module.
   void PopGlobalModuleFragment();
 
   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);
 
   // Determine whether the module M belongs to the  current TU.
   bool isModuleUnitOfCurrentTU(const Module *M) const;
 
 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;
   }
 
   /// Get the module owning an entity.
   Module *getOwningModule(const Decl *Entity) {
     return Entity->getOwningModule();
   }
 
   bool isModuleDirectlyImported(const Module *M) {
     return DirectModuleImports.contains(M);
   }
 
   /// 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(NamedDecl *Def);
   bool hasMergedDefinitionInCurrentModule(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);
 
   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);
   /// 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);
   QualType BuildUnaryTransformType(QualType BaseType,
                                    UnaryTransformType::UTTKind UKind,
                                    SourceLocation Loc);
 
   //===--------------------------------------------------------------------===//
   // Symbol table / Decl tracking callbacks: SemaDecl.cpp.
   //
 
   struct SkipBodyInfo {
     SkipBodyInfo()
         : ShouldSkip(false), CheckSameAsPrevious(false), Previous(nullptr),
           New(nullptr) {}
     bool ShouldSkip;
     bool CheckSameAsPrevious;
     NamedDecl *Previous;
     NamedDecl *New;
   };
 
   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,
                          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 = None);
   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);
   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 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);
 
   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);
 
   /// 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.
     PrivateFragment, ///< after 'module :private;'.
     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, NamedDecl *Decl,
                              MissingImportKind MIK, bool Recover = true);
   void diagnoseMissingImport(SourceLocation Loc, 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;'
   };
 
   Decl *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,
                  SkipBodyInfo *SkipBody = nullptr);
 
   Decl *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);
 
   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);
 
   /// 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);
 
   /// 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();
 
   /// 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);
 
   /// 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 IsForUsingDecl);
   bool IsOverload(FunctionDecl *New, FunctionDecl *Old, bool IsForUsingDecl,
                   bool ConsiderCudaAttrs = true,
                   bool ConsiderRequiresClauses = true);
 
   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.
   };
   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 = None,
                             OverloadCandidateParamOrder PO = {});
   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 = None,
                           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 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(
       NamedDecl *Found, 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);
 
   bool ResolveAndFixSingleFunctionTemplateSpecialization(
                       ExprResult &SrcExpr,
                       bool DoFunctionPointerConverion = 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() {
     // 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(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 checkTargetClonesAttrString(SourceLocation LiteralLoc, StringRef Str,
                                    const StringLiteral *Literal,
                                    bool &HasDefault, bool &HasCommas,
                                    SmallVectorImpl<StringRef> &Strings);
   bool checkMSInheritanceAttrOnDefinition(
       CXXRecordDecl *RD, SourceRange Range, bool BestCase,
       MSInheritanceModel SemanticSpelling);
 
   void CheckAlignasUnderalignment(Decl *D);
 
   /// 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);
 
   /// 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 DiagnoseUnusedDecl(const NamedDecl *ND);
 
   /// If VD is set but not otherwise used, diagnose, for a parameter or a
   /// variable.
   void DiagnoseUnusedButSetDecl(const VarDecl *VD);
 
   /// 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);
   bool DiagnoseUseOfDecl(NamedDecl *D, ArrayRef<SourceLocation> Locs,
                          const ObjCInterfaceDecl *UnknownObjCClass = nullptr,
                          bool ObjCPropertyAccess = false,
                          bool AvoidPartialAvailabilityChecks = false,
                          ObjCInterfaceDecl *ClassReciever = nullptr);
   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(VarDecl *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(VarDecl *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(VarDecl *Var, SourceLocation Loc,
                           TryCaptureKind Kind = TryCapture_Implicit,
                           SourceLocation EllipsisLoc = SourceLocation());
 
   /// Checks if the variable must be captured.
   bool NeedToCaptureVariable(VarDecl *Var, SourceLocation Loc);
 
   /// Given a variable, determine the type that a reference to that
   /// variable will have in the given scope.
   QualType getCapturedDeclRefType(VarDecl *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 = None);
 
   /// 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(LookupResult &R);
 
   bool
   DiagnoseEmptyLookup(Scope *S, CXXScopeSpec &SS, LookupResult &R,
                       CorrectionCandidateCallback &CCC,
                       TemplateArgumentListInfo *ExplicitTemplateArgs = nullptr,
                       ArrayRef<Expr *> Args = None, 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 ActOnGenericSelectionExpr(SourceLocation KeyLoc,
                                        SourceLocation DefaultLoc,
                                        SourceLocation RParenLoc,
                                        Expr *ControllingExpr,
                                        ArrayRef<ParsedType> ArgTypes,
                                        ArrayRef<Expr *> ArgExprs);
   ExprResult CreateGenericSelectionExpr(SourceLocation KeyLoc,
                                         SourceLocation DefaultLoc,
                                         SourceLocation RParenLoc,
                                         Expr *ControllingExpr,
                                         ArrayRef<TypeSourceInfo *> Types,
                                         ArrayRef<Expr *> Exprs);
 
   // Binary/Unary Operators.  'Tok' is the token for the operator.
   ExprResult CreateBuiltinUnaryOp(SourceLocation OpLoc, UnaryOperatorKind Opc,
                                   Expr *InputExpr);
   ExprResult BuildUnaryOp(Scope *S, SourceLocation OpLoc,
                           UnaryOperatorKind Opc, Expr *Input);
   ExprResult ActOnUnaryOp(Scope *S, SourceLocation OpLoc,
                           tok::TokenKind Op, Expr *Input);
 
   bool isQualifiedMemberAccess(Expr *E);
   QualType CheckAddressOfOperand(ExprResult &Operand, SourceLocation OpLoc);
 
   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);
   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_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);
 
   //===---------------------------- 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);
   void ActOnFinishNamespaceDef(Decl *Dcl, SourceLocation RBrace);
 
   NamespaceDecl *getStdNamespace() const;
   NamespaceDecl *getOrCreateStdNamespace();
 
   NamespaceDecl *lookupStdExperimentalNamespace();
   NamespaceDecl *getCachedCoroNamespace() { return CoroTraitsNamespaceCache; }
 
   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, 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, const DeclSpec &);
   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 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);
 
   /// BuildCXXDefaultArgExpr - Creates a CXXDefaultArgExpr, instantiating
   /// the default expr if needed.
   ExprResult BuildCXXDefaultArgExpr(SourceLocation CallLoc,
                                     FunctionDecl *FD,
                                     ParmVarDecl *Param);
 
   /// 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 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,
                               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,
                          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);
   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);
   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 isNonTypeNestedNameSpecifier(Scope *S, CXXScopeSpec &SS,
                                     NestedNameSpecInfo &IdInfo);
 
   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 ErrorRecoveryLookup If true, then this method is called to improve
   /// error recovery. In this case do not emit error message.
   ///
   /// \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);
 
   /// Start the definition of a lambda expression.
   CXXMethodDecl *startLambdaDefinition(CXXRecordDecl *Class,
                                        SourceRange IntroducerRange,
                                        TypeSourceInfo *MethodType,
                                        SourceLocation EndLoc,
                                        ArrayRef<ParmVarDecl *> Params,
                                        ConstexprSpecKind ConstexprKind,
                                        Expr *TrailingRequiresClause);
 
   /// Number lambda for linkage purposes if necessary.
   void handleLambdaNumbering(
       CXXRecordDecl *Class, CXXMethodDecl *Method,
       Optional<std::tuple<bool, unsigned, unsigned, Decl *>> Mangling = None);
 
   /// 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 ExplicitResultType,
                         bool Mutable);
 
   /// 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, None, Id,
         InitKind != LambdaCaptureInitKind::CopyInit, Init));
   }
   QualType buildLambdaInitCaptureInitialization(
       SourceLocation Loc, bool ByRef, SourceLocation EllipsisLoc,
       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);
 
   /// Add an init-capture to a lambda scope.
   void addInitCapture(sema::LambdaScopeInfo *LSI, VarDecl *Var);
 
   /// Note that we have finished the explicit captures for the
   /// given lambda.
   void finishLambdaExplicitCaptures(sema::LambdaScopeInfo *LSI);
 
   /// \brief This is called after parsing the explicit template parameter list
   /// on a lambda (if it exists) in C++2a.
   void ActOnLambdaExplicitTemplateParameterList(SourceLocation LAngleLoc,
                                                 ArrayRef<NamedDecl *> TParams,
                                                 SourceLocation RAngleLoc,
                                                 ExprResult RequiresClause);
 
   /// Introduce the lambda parameters into scope.
   void addLambdaParameters(
       ArrayRef<LambdaIntroducer::LambdaCapture> Captures,
       CXXMethodDecl *CallOperator, Scope *CurScope);
 
   /// Deduce a block or lambda's return type based on the return
   /// statements present in the body.
   void deduceClosureReturnType(sema::CapturingScopeInfo &CSI);
 
   /// 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, Scope *CurScope);
 
   /// 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);
 
   /// 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);
 
 public:
   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, ArrayRef<const Expr *> AC1,
                               NamedDecl *D2, ArrayRef<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 TemplateArgs 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,
       ArrayRef<TemplateArgument> TemplateArgs,
       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());
 
 
   /// \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,
                                        ArrayRef<TemplateArgument> 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 = None);
 
   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();
 
   Decl *ActOnStaticAssertDeclaration(SourceLocation StaticAssertLoc,
                                      Expr *AssertExpr,
                                      Expr *AssertMessageExpr,
                                      SourceLocation RParenLoc);
   Decl *BuildStaticAssertDeclaration(SourceLocation StaticAssertLoc,
                                      Expr *AssertExpr,
                                      StringLiteral *AssertMessageExpr,
                                      SourceLocation RParenLoc,
                                      bool Failed);
 
   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);
   void CheckDeductionGuideDeclarator(Declarator &D, QualType &R,
                                      StorageClass &SC);
   void CheckDeductionGuideTemplate(FunctionTemplateDecl *TD);
 
   void CheckExplicitlyDefaultedFunction(Scope *S, FunctionDecl *MD);
 
   bool CheckExplicitlyDefaultedSpecialMember(CXXMethodDecl *MD,
                                              CXXSpecialMember CSM);
   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:
     llvm::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,
                             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 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 *ConstrainedParameter,
                             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);
 
   /// 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,
                                           SmallVectorImpl<TemplateArgument>
                                             &Converted,
                                           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> &Converted,
                              CheckTemplateArgumentKind CTAK = CTAK_Specified);
 
   /// Check that the given template arguments can be 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> &Converted,
                                  bool UpdateArgsWithConversions = true,
                                  bool *ConstraintsNotSatisfied = nullptr);
 
   bool CheckTemplateTypeArgument(TemplateTypeParmDecl *Param,
                                  TemplateArgumentLoc &Arg,
                            SmallVectorImpl<TemplateArgument> &Converted);
 
   bool CheckTemplateArgument(TypeSourceInfo *Arg);
   ExprResult CheckTemplateArgument(NonTypeTemplateParmDecl *Param,
                                    QualType InstantiatedParamType, Expr *Arg,
                                    TemplateArgument &Converted,
                                CheckTemplateArgumentKind CTAK = CTAK_Specified);
   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
   };
 
   bool TemplateParameterListsAreEqual(TemplateParameterList *New,
                                       TemplateParameterList *Old,
                                       bool Complain,
                                       TemplateParameterListEqualKind Kind,
                                       SourceLocation TemplateArgLoc
                                         = SourceLocation());
 
   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.
   TypeResult
   ActOnTypenameType(Scope *S, SourceLocation TypenameLoc,
                     const CXXScopeSpec &SS, const IdentifierInfo &II,
                     SourceLocation IdLoc);
 
   /// 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(
       concepts::Requirement::SubstitutionDiagnostic *SubstDiag);
   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,
                                      Optional<unsigned> NumExpansions);
 
   /// Construct a pack expansion type from the pattern of the pack
   /// expansion.
   QualType CheckPackExpansion(QualType Pattern,
                               SourceRange PatternRange,
                               SourceLocation EllipsisLoc,
                               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,
                                 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,
                                        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.
   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,
       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.
   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
   };
 
   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,
       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);
 
   /// Result type of DeduceAutoType.
   enum DeduceAutoResult {
     DAR_Succeeded,
     DAR_Failed,
     DAR_FailedAlreadyDiagnosed
   };
 
   DeduceAutoResult
   DeduceAutoType(TypeSourceInfo *AutoType, Expr *&Initializer, QualType &Result,
                  Optional<unsigned> DependentDeductionDepth = None,
                  bool IgnoreConstraints = false);
   DeduceAutoResult
   DeduceAutoType(TypeLoc AutoTypeLoc, Expr *&Initializer, QualType &Result,
                  Optional<unsigned> DependentDeductionDepth = None,
                  bool IgnoreConstraints = false);
   void DiagnoseAutoDeductionFailure(VarDecl *VDecl, Expr *Init);
   bool DeduceReturnType(FunctionDecl *FD, SourceLocation Loc,
                         bool Diagnose = true);
 
   /// Declare implicit deduction guides for a class template if we've
   /// not already done so.
   void DeclareImplicitDeductionGuides(TemplateDecl *Template,
                                       SourceLocation Loc);
 
   QualType DeduceTemplateSpecializationFromInitializer(
       TypeSourceInfo *TInfo, const InitializedEntity &Entity,
       const InitializationKind &Kind, MultiExprArg Init);
 
   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,
       bool AllowOrderingByConstraints = true);
   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, const TemplateArgumentList *Innermost = nullptr,
       bool RelativeToPrimary = false, const FunctionDecl *Pattern = nullptr);
 
   /// 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 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,
 
       // 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
     } 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());
 
     /// 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 = None,
         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.
   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 isImmediateFunctionContext() const {
     assert(!ExprEvalContexts.empty() &&
            "Must be in an expression evaluation context");
     return ExprEvalContexts.back().isImmediateFunctionContext();
   }
 
   /// 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;
 
   class GlobalEagerInstantiationScope {
   public:
     GlobalEagerInstantiationScope(Sema &S, bool Enabled)
         : S(S), Enabled(Enabled) {
       if (!Enabled) return;
 
       SavedPendingInstantiations.swap(S.PendingInstantiations);
       SavedVTableUses.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(SavedVTableUses);
 
       // 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(SavedPendingInstantiations);
       } else {
         // Template instantiations in the PCH may be delayed until the TU.
         S.PendingInstantiations.swap(SavedPendingInstantiations);
         S.PendingInstantiations.insert(S.PendingInstantiations.end(),
                                        SavedPendingInstantiations.begin(),
                                        SavedPendingInstantiations.end());
       }
     }
 
   private:
     Sema &S;
     SmallVector<VTableUse, 16> SavedVTableUses;
     std::deque<PendingImplicitInstantiation> SavedPendingInstantiations;
     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);
   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,
                                 Optional<unsigned> NumExpansions,
                                 bool ExpectParameterPack);
   bool SubstParmTypes(SourceLocation Loc, ArrayRef<ParmVarDecl *> Params,
                       const FunctionProtoType::ExtParameterInfo *ExtParamInfos,
                       const MultiLevelTemplateArgumentList &TemplateArgs,
                       SmallVectorImpl<QualType> &ParamTypes,
                       SmallVectorImpl<ParmVarDecl *> *OutParams,
                       ExtParameterInfoBuilder &ParamInfos);
   ExprResult SubstExpr(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
   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
   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 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);
 
   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);
 
   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 = false);
 
   /// 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 = None,
                    ArrayRef<DeclGroupPtrTy> allTUVars = None);
 
   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();
 
   /// 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);
 
   /// 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 TS
   //
   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,
                                            NamespaceDecl *&Namespace);
   /// 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.
     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();
   ExprResult
   VerifyPositiveIntegerConstantInClause(Expr *Op, OpenMPClauseKind CKind,
                                         bool StrictlyPositive = true,
                                         bool SuppressExprDiags = false);
   /// 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();
   }
 
   /// 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);
   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());
   /// 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 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 None, if the function/variant function are not compatible with
   /// the pragma, pair of original function/variant ref expression otherwise.
   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<OMPDeclareVariantAttr::InteropType> 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(Expr *Size, SourceLocation StartLoc,
                                         SourceLocation LParenLoc,
                                         SourceLocation EndLoc);
   /// Called on well-formed 'num_tasks' clause.
   OMPClause *ActOnOpenMPNumTasksClause(Expr *NumTasks, SourceLocation StartLoc,
                                        SourceLocation LParenLoc,
                                        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(OpenMPOrderClauseKind Kind,
                                     SourceLocation KindLoc,
                                     SourceLocation StartLoc,
                                     SourceLocation LParenLoc,
                                     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, ArrayRef<Expr *> PrefExprs,
                                    bool IsTarget, bool IsTargetSync,
                                    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);
 
   /// Data used for processing a list of variables in OpenMP clauses.
   struct OpenMPVarListDataTy final {
     Expr *DepModOrTailExpr = 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 = llvm::None);
   /// 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 = llvm::None);
   /// 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 = llvm::None);
   /// 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(
       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 = llvm::None);
   /// 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 = llvm::None);
   /// 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 = llvm::None);
   /// 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);
 
   /// 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,
 
     /// 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 areMatrixTypesOfTheSameDimension(QualType srcTy, QualType destTy);
 
   bool areVectorTypesSameSize(QualType srcType, QualType destType);
   bool areLaxCompatibleVectorTypes(QualType srcType, QualType destType);
   bool isLaxVectorConversion(QualType srcType, QualType destType);
   bool areSameVectorElemTypes(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;
     bool HasKnownValue;
     bool KnownValue;
 
     friend class Sema;
     ConditionResult(Sema &S, Decl *ConditionVar, FullExprArg Condition,
                     bool IsConstexpr)
         : ConditionVar(ConditionVar), Condition(Condition), Invalid(false),
           HasKnownValue(IsConstexpr && Condition.get() &&
                         !Condition.get()->isValueDependent()),
           KnownValue(HasKnownValue &&
                      !!Condition.get()->EvaluateKnownConstInt(S.Context)) {}
     explicit ConditionResult(bool Invalid)
         : ConditionVar(nullptr), Condition(nullptr), Invalid(Invalid),
           HasKnownValue(false), KnownValue(false) {}
 
   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());
     }
     llvm::Optional<bool> getKnownValue() const {
       if (!HasKnownValue)
         return None;
       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);
 
   /// ConvertIntegerToTypeWarnOnOverflow - Convert the specified APInt to have
   /// the specified width and sign.  If an overflow occurs, detect it and emit
   /// the specified diagnostic.
   void ConvertIntegerToTypeWarnOnOverflow(llvm::APSInt &OldVal,
                                           unsigned NewWidth, bool NewSign,
                                           SourceLocation Loc, unsigned DiagID);
 
   /// 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<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<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<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, 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, FunctionDecl *FD);
 
   SemaDiagnosticBuilder targetDiag(SourceLocation Loc, unsigned DiagID,
                                    FunctionDecl *FD = nullptr);
   SemaDiagnosticBuilder targetDiag(SourceLocation Loc,
                                    const PartialDiagnostic &PD,
                                    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 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, 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);
 
   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 PrepareBuiltinElementwiseMathOneArgCall(CallExpr *TheCall);
   bool PrepareBuiltinReduceMathOneArgCall(CallExpr *TheCall);
 
   // Matrix builtin handling.
   ExprResult SemaBuiltinMatrixTranspose(CallExpr *TheCall,
                                         ExprResult CallResult);
   ExprResult SemaBuiltinMatrixColumnMajorLoad(CallExpr *TheCall,
                                               ExprResult CallResult);
   ExprResult SemaBuiltinMatrixColumnMajorStore(CallExpr *TheCall,
                                                ExprResult CallResult);
 
 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(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;
   mutable IdentifierInfo *Ident___float128;
 
   /// 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;
   IdentifierInfo *getFloat128Identifier() 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);
 
   /// Check whether we're allowed to call Callee from the current context.
   ///
   /// - If the call is never allowed in a semantically-correct program
   ///   emits an error and returns false.
   ///
   /// - If the call is allowed in semantically-correct programs, but only if
   ///   it's never codegen'ed, creates a deferred diagnostic to be emitted if
   ///   and when the caller is codegen'ed, and returns true.
   ///
   /// - Otherwise, returns true without emitting any diagnostics.
   ///
   /// Adds Callee to DeviceCallGraph if we don't know if its caller will be
   /// codegen'ed yet.
   bool checkSYCLDeviceFunction(SourceLocation Loc, FunctionDecl *Callee);
   void deepTypeCheckForSYCLDevice(SourceLocation UsedAt,
                                   llvm::DenseSet<QualType> Visited,
                                   ValueDecl *DeclToCheck);
 };
 
 /// RAII object that enters a new expression evaluation context.
 class EnterExpressionEvaluationContext {
   Sema &Actions;
   bool Entered = true;
 
 public:
   EnterExpressionEvaluationContext(
       Sema &Actions, Sema::ExpressionEvaluationContext NewContext,
       Decl *LambdaContextDecl = nullptr,
       Sema::ExpressionEvaluationContextRecord::ExpressionKind ExprContext =
           Sema::ExpressionEvaluationContextRecord::EK_Other,
       bool ShouldEnter = true)
       : Actions(Actions), Entered(ShouldEnter) {
     if (Entered)
       Actions.PushExpressionEvaluationContext(NewContext, LambdaContextDecl,
                                               ExprContext);
   }
   EnterExpressionEvaluationContext(
       Sema &Actions, Sema::ExpressionEvaluationContext NewContext,
       Sema::ReuseLambdaContextDecl_t,
       Sema::ExpressionEvaluationContextRecord::ExpressionKind ExprContext =
           Sema::ExpressionEvaluationContextRecord::EK_Other)
       : Actions(Actions) {
     Actions.PushExpressionEvaluationContext(
         NewContext, Sema::ReuseLambdaContextDecl, ExprContext);
   }
 
   enum InitListTag { InitList };
   EnterExpressionEvaluationContext(Sema &Actions, InitListTag,
                                    bool ShouldEnter = true)
       : Actions(Actions), Entered(false) {
     // In C++11 onwards, narrowing checks are performed on the contents of
     // braced-init-lists, even when they occur within unevaluated operands.
     // Therefore we still need to instantiate constexpr functions used in such
     // a context.
     if (ShouldEnter && Actions.isUnevaluatedContext() &&
         Actions.getLangOpts().CPlusPlus11) {
       Actions.PushExpressionEvaluationContext(
           Sema::ExpressionEvaluationContext::UnevaluatedList);
       Entered = true;
     }
   }
 
   ~EnterExpressionEvaluationContext() {
     if (Entered)
       Actions.PopExpressionEvaluationContext();
   }
 };
 
 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;
 };
 
 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<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/SemaExpr.cpp b/contrib/llvm-project/clang/lib/Sema/SemaExpr.cpp
index 83081bbf0aa0..a8fe9a68c8cb 100644
--- a/contrib/llvm-project/clang/lib/Sema/SemaExpr.cpp
+++ b/contrib/llvm-project/clang/lib/Sema/SemaExpr.cpp
@@ -1,20815 +1,20825 @@
 //===--- 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/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"
 
 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) {
   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 (FD->getTrailingRequiresClause()) {
       ConstraintSatisfaction Satisfaction;
       if (CheckFunctionConstraints(FD, Satisfaction, Loc))
         // 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 (getLangOpts().SYCLIsDevice && !checkSYCLDeviceFunction(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
   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 (auto *VD = dyn_cast<ValueDecl>(D))
     checkTypeSupport(VD->getType(), Loc, VD);
 
   if (LangOpts.SYCLIsDevice || (LangOpts.OpenMP && LangOpts.OpenMPIsDevice)) {
     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 (Ty->isPromotableIntegerType()) {
       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 (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);
     LLVM_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(),
                                     None, 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 = cast<ComplexType>(ComplexTy)->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;
 }
 
 /// Handle arithmetic conversion with complex types.  Helper function of
 /// UsualArithmeticConversions()
 static QualType handleComplexFloatConversion(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;
 
   // 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".
 
   // Compute the rank of the two types, regardless of whether they are complex.
   int Order = S.Context.getFloatingTypeOrder(LHSType, RHSType);
 
   auto *LHSComplexType = dyn_cast<ComplexType>(LHSType);
   auto *RHSComplexType = dyn_cast<ComplexType>(RHSType);
   QualType LHSElementType =
       LHSComplexType ? LHSComplexType->getElementType() : LHSType;
   QualType RHSElementType =
       RHSComplexType ? RHSComplexType->getElementType() : RHSType;
 
   QualType ResultType = S.Context.getComplexType(LHSElementType);
   if (Order < 0) {
     // Promote the precision of the LHS if not an assignment.
     ResultType = S.Context.getComplexType(RHSElementType);
     if (!IsCompAssign) {
       if (LHSComplexType)
         LHS =
             S.ImpCastExprToType(LHS.get(), ResultType, CK_FloatingComplexCast);
       else
         LHS = S.ImpCastExprToType(LHS.get(), RHSElementType, CK_FloatingCast);
     }
   } else if (Order > 0) {
     // Promote the precision of the RHS.
     if (RHSComplexType)
       RHS = S.ImpCastExprToType(RHS.get(), ResultType, CK_FloatingComplexCast);
     else
       RHS = S.ImpCastExprToType(RHS.get(), LHSElementType, CK_FloatingCast);
   }
   return ResultType;
 }
 
 /// 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 =
     Context.getCanonicalType(LHS.get()->getType()).getUnqualifiedType();
   QualType RHSType =
     Context.getCanonicalType(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 (LHSType == RHSType)
     return LHSType;
 
   // 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 (LHSType->isPromotableIntegerType())
     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 (LHSType == RHSType)
     return LHSType;
 
   // 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 handleComplexFloatConversion(*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,
                                 Expr *ControllingExpr,
                                 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;
   }
 
   ExprResult ER = CreateGenericSelectionExpr(KeyLoc, DefaultLoc, RParenLoc,
                                              ControllingExpr,
                                              llvm::makeArrayRef(Types, NumAssocs),
                                              ArgExprs);
   delete [] Types;
   return ER;
 }
 
 ExprResult
 Sema::CreateGenericSelectionExpr(SourceLocation KeyLoc,
                                  SourceLocation DefaultLoc,
                                  SourceLocation RParenLoc,
                                  Expr *ControllingExpr,
                                  ArrayRef<TypeSourceInfo *> Types,
                                  ArrayRef<Expr *> Exprs) {
   unsigned NumAssocs = Types.size();
   assert(NumAssocs == Exprs.size());
 
   // 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(ControllingExpr);
     if (R.isInvalid())
       return ExprError();
     ControllingExpr = R.get();
   }
 
   bool TypeErrorFound = false,
        IsResultDependent = ControllingExpr->isTypeDependent(),
        ContainsUnexpandedParameterPack
          = ControllingExpr->containsUnexpandedParameterPack();
 
   // The controlling expression is an unevaluated operand, so side effects are
   // likely unintended.
   if (!inTemplateInstantiation() && !IsResultDependent &&
       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 {
         // 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 (Types[i]->getType()->isIncompleteType())
           D = diag::err_assoc_type_incomplete;
         else if (!Types[i]->getType()->isObjectType())
           D = diag::err_assoc_type_nonobject;
         else if (Types[i]->getType()->isVariablyModifiedType())
           D = diag::err_assoc_type_variably_modified;
         else {
           // 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.
           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)
     return GenericSelectionExpr::Create(Context, KeyLoc, ControllingExpr, 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 (Context.typesAreCompatible(
                  ControllingExpr->getType().getCanonicalType(),
                                         Types[i]->getType()))
       CompatIndices.push_back(i);
   }
 
   // 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) {
     // We strip parens here because the controlling expression is typically
     // parenthesized in macro definitions.
     ControllingExpr = ControllingExpr->IgnoreParens();
     Diag(ControllingExpr->getBeginLoc(), diag::err_generic_sel_multi_match)
         << ControllingExpr->getSourceRange() << ControllingExpr->getType()
         << (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) {
     // We strip parens here because the controlling expression is typically
     // parenthesized in macro definitions.
     ControllingExpr = ControllingExpr->IgnoreParens();
     Diag(ControllingExpr->getBeginLoc(), diag::err_generic_sel_no_match)
         << ControllingExpr->getSourceRange() << ControllingExpr->getType();
     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;
 
   return GenericSelectionExpr::Create(
       Context, KeyLoc, ControllingExpr, 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::makeArrayRef(ArgTy, Args.size()),
                               /*AllowRaw*/ false, /*AllowTemplate*/ false,
                               /*AllowStringTemplatePack*/ false,
                               /*DiagnoseMissing*/ true) == Sema::LOLR_Error)
     return ExprError();
 
   return S.BuildLiteralOperatorCall(R, OpNameInfo, Args, LitEndLoc);
 }
 
 /// 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, None, 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, None, 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>(D) &&
       NeedToCaptureVariable(cast<VarDecl>(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 (auto *FPT = Ty->getAs<FunctionProtoType>()) {
     if (isUnresolvedExceptionSpec(FPT->getExceptionSpecType())) {
       if (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);
 
   FieldDecl *FD = dyn_cast<FieldDecl>(D);
   if (IndirectFieldDecl *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 (auto *BD = dyn_cast<BindingDecl>(D))
     if (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(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;
   CXXMethodDecl *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 (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,
                             None, &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) {
   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)
     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) {
   CXXRecordDecl *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 (CXXMethodDecl *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 (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 (isa<FunctionDecl>(D)) {
       FunctionDecl *FDecl = 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) {
   if (D->isInvalidDecl())
     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()))
     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 diagnoseUncapturableValueReference(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)) {
     // 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 (IndirectFieldDecl *indirectField = dyn_cast<IndirectFieldDecl>(VD))
     if (!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;
     }
     LLVM_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();
     // FIXME: Support lambda-capture of BindingDecls, once CWG actually
     // decides how that's supposed to work.
     auto *BD = cast<BindingDecl>(VD);
     if (BD->getDeclContext() != CurContext) {
       auto *DD = dyn_cast_or_null<VarDecl>(BD->getDecomposedDecl());
       if (DD && DD->hasLocalStorage())
         diagnoseUncapturableValueReference(*this, Loc, BD);
     }
     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;
     }
     LLVM_FALLTHROUGH;
 
   case Decl::CXXConversion:
   case Decl::CXXDestructor:
   case Decl::CXXConstructor:
     valueKind = VK_PRValue;
     break;
   }
 
   return BuildDeclRefExpr(VD, type, valueKind, NameInfo, &SS, FoundD,
                           /*FIXME: TemplateKWLoc*/ SourceLocation(),
                           TemplateArgs);
 }
 
 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, 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.
     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, None, 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;
 
     // 'long long' is a C99 or C++11 feature.
     if (!getLangOpts().C99 && Literal.isLongLong) {
       if (getLangOpts().CPlusPlus)
         Diag(Tok.getLocation(),
              getLangOpts().CPlusPlus11 ?
              diag::warn_cxx98_compat_longlong : diag::ext_cxx11_longlong);
       else
         Diag(Tok.getLocation(), diag::ext_c99_longlong);
     }
 
     // 'z/uz' literals are a C++2b feature.
     if (Literal.isSizeT)
       Diag(Tok.getLocation(), getLangOpts().CPlusPlus
                                   ? getLangOpts().CPlusPlus2b
                                         ? diag::warn_cxx20_compat_size_t_suffix
                                         : diag::ext_cxx2b_size_t_suffix
                                   : diag::err_cxx2b_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++2b 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;
         }
       }
 
       // 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,
                                      Expr *E) {
   // Don't warn if the operation changed the type.
   if (T != E->getType())
     return;
 
   // Now look for array decays.
   ImplicitCastExpr *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;
 
   // '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 (DeclRefExpr *DeclRef = dyn_cast<DeclRefExpr>(E->IgnoreParens())) {
       if (ParmVarDecl *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 (BinaryOperator *BO = dyn_cast<BinaryOperator>(E->IgnoreParens())) {
       warnOnSizeofOnArrayDecay(*this, BO->getOperatorLoc(), BO->getType(),
                                BO->getLHS());
       warnOnSizeofOnArrayDecay(*this, BO->getOperatorLoc(), BO->getType(),
                                BO->getRHS());
     }
   }
 
   return false;
 }
 
 /// 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) {
   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,
           getTraitSpelling(ExprKind), ExprRange))
     return true;
 
   if (ExprType->isFunctionType()) {
     Diag(OpLoc, diag::err_sizeof_alignof_function_type)
         << getTraitSpelling(ExprKind) << ExprRange;
     return true;
   }
 
   if (CheckObjCTraitOperandConstraints(*this, ExprType, OpLoc, ExprRange,
                                        ExprKind))
     return true;
 
   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::Elaborated:
     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::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());
 }
 
 /// 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))
     return ExprError();
 
   if (T->isVariablyModifiedType() && FunctionScopes.size() > 1) {
     if (auto *TT = T->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, T, CSI);
         }
       }
     }
   }
 
   // C99 6.5.3.4p4: the type (an unsigned integer type) is size_t.
   if (isUnevaluatedContext() && ExprKind == UETT_SizeOf &&
       TInfo->getType()->isVariablyModifiedType())
     TInfo = TransformToPotentiallyEvaluated(TInfo);
 
   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;
 }
 
 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->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);
   }
 
   // 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))) {
     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 || 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 (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);
     }
     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;
       }
       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() &&
              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) {
   if (Param->hasUnparsedDefaultArg()) {
     // 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() &&
       InstantiateDefaultArgument(CallLoc, FD, Param))
     return true;
 
   assert(Param->hasInit() && "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 Init = dyn_cast<ExprWithCleanups>(Param->getInit())) {
     // Set the "needs cleanups" bit regardless of whether there are
     // any explicit objects.
     Cleanup.setExprNeedsCleanups(Init->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(!Init->getNumObjects() &&
            "default argument expression has capturing blocks?");
   }
 
   // We already type-checked the argument, so we know it works.
   // Just mark all of the declarations in this potentially-evaluated expression
   // as being "referenced".
   EnterExpressionEvaluationContext EvalContext(
       *this, ExpressionEvaluationContext::PotentiallyEvaluated, Param);
   MarkDeclarationsReferencedInExpr(Param->getDefaultArg(),
                                    /*SkipLocalVariables=*/true);
   return false;
 }
 
 ExprResult Sema::BuildCXXDefaultArgExpr(SourceLocation CallLoc,
                                         FunctionDecl *FD, ParmVarDecl *Param) {
   assert(Param->hasDefaultArg() && "can't build nonexistent default arg");
   if (CheckCXXDefaultArgExpr(CallLoc, FD, Param))
     return ExprError();
   return CXXDefaultArgExpr::Create(Context, CallLoc, Param, CurContext);
 }
 
 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;
 
       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;
 
       // 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;
   }
 
   Optional<CharUnits> ArgSize =
       getASTContext().getTypeSizeInCharsIfKnown(ArgCAT);
   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 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()) {
       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 (isa<MemberExpr>(NakedFn))
     NDecl = cast<MemberExpr>(NakedFn)->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.");
     QualType ReturnType =
         llvm::isa_and_nonnull<FunctionDecl>(NDecl)
             ? cast<FunctionDecl>(NDecl)->getCallResultType()
             : Context.DependentTy;
     return CallExpr::Create(Context, Fn, ArgExprs, ReturnType,
                             Expr::getValueKindForType(ReturnType), 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::makeArrayRef(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()));
 
   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()) {
       if (!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->isSizelessBuiltinType())
       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 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);
   bool IsDestTyAltivec = DestTy->isVectorType() &&
                          (DestTy->castAs<VectorType>()->getVectorKind() ==
                           VectorType::AltiVecVector);
 
   return (IsSrcTyAltivec || IsDestTyAltivec);
 }
 
 // This returns true if both vectors have the same element type.
 bool Sema::areSameVectorElemTypes(QualType SrcTy, QualType DestTy) {
   assert((DestTy->isVectorType() || SrcTy->isVectorType()) &&
          "expected at least one type to be a vector here");
 
   uint64_t SrcLen, DestLen;
   QualType SrcEltTy, DestEltTy;
   if (!breakDownVectorType(SrcTy, SrcLen, SrcEltTy))
     return false;
   if (!breakDownVectorType(DestTy, DestLen, DestEltTy))
     return false;
 
   return (SrcEltTy == DestEltTy);
 }
 
 /// 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;
 }
 
 /// Handle when one or both operands are void type.
 static QualType checkConditionalVoidType(Sema &S, ExprResult &LHS,
                                          ExprResult &RHS) {
     Expr *LHSExpr = LHS.get();
     Expr *RHSExpr = RHS.get();
 
     if (!LHSExpr->getType()->isVoidType())
       S.Diag(RHSExpr->getBeginLoc(), diag::ext_typecheck_cond_one_void)
           << RHSExpr->getSourceRange();
     if (!RHSExpr->getType()->isVoidType())
       S.Diag(LHSExpr->getBeginLoc(), diag::ext_typecheck_cond_one_void)
           << LHSExpr->getSourceRange();
     LHS = S.ImpCastExprToType(LHS.get(), S.Context.VoidTy, CK_ToVoid);
     RHS = S.ImpCastExprToType(RHS.get(), S.Context.VoidTy, CK_ToVoid);
     return S.Context.VoidTy;
 }
 
 /// 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 LHSTy;
   }
 
   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);
 
   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();
 
   QualType LHSTy = LHS.get()->getType();
   QualType RHSTy = RHS.get()->getType();
 
   // 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 LHSTy;
   }
 
   // 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 LHSTy.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()) {
     return checkConditionalVoidType(*this, LHS, RHS);
   }
 
   // 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 LHSTy;
 
   // 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 = [&Ctx](QualType Ty) {
     Optional<NullabilityKind> Kind = Ty->getNullability(Ctx);
     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(Ctx))
     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) {
   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;
   }
 
   // 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 (anyAltivecTypes(RHSType, LHSType) &&
             !areSameVectorElemTypes(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 (VecType->getVectorKind() == VectorType::AltiVecVector)
           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->isSizelessBuiltinType() && RHSType->isVectorType()) ||
         (LHSType->isVectorType() && RHSType->isSizelessBuiltinType()))
       if (Context.areCompatibleSveTypes(LHSType, RHSType) ||
           Context.areLaxCompatibleSveTypes(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);
     }
 
     // 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;
   }
 
   // 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;
   }
 
   // C99 6.5.16.1p1: the left operand is a pointer and the right is
   // a null pointer constant.
   if ((LHSType->isPointerType() || LHSType->isObjCObjectPointerType() ||
        LHSType->isBlockPointerType()) &&
       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;
   }
 
   // OpenCL queue_t type assignment.
   if (LHSType->isQueueT() && RHS.get()->isNullPointerConstant(
                                  Context, Expr::NPC_ValueDependentIsNull)) {
     RHS = ImpCastExprToType(RHS.get(), LHSType, CK_NullToPointer);
     return Compatible;
   }
 
   // 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).
   //
   // 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;
   }
   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.getMinSignedBits()
                                                   : 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 (Scalar) {
     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);
 
   if ((LHSVecType && LHSVecType->getElementType()->isBFloat16Type()) ||
       (RHSVecType && RHSVecType->getElementType()->isBFloat16Type()))
     return ReportInvalid ? InvalidOperands(Loc, LHS, RHS) : QualType();
 
   // 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 LHSType;
 
   // 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 vectors are invalid
   // since the ambiguity can affect the ABI.
   auto IsSveConversion = [](QualType FirstType, QualType SecondType) {
     const VectorType *VecType = SecondType->getAs<VectorType>();
     return FirstType->isSizelessBuiltinType() && VecType &&
            (VecType->getVectorKind() == VectorType::SveFixedLengthDataVector ||
             VecType->getVectorKind() ==
                 VectorType::SveFixedLengthPredicateVector);
   };
 
   if (IsSveConversion(LHSType, RHSType) || IsSveConversion(RHSType, LHSType)) {
     Diag(Loc, diag::err_typecheck_sve_ambiguous) << LHSType << RHSType;
     return QualType();
   }
 
   // Expressions containing GNU and SVE (fixed or sizeless) vectors are invalid
   // since the ambiguity can affect the ABI.
   auto IsSveGnuConversion = [](QualType FirstType, QualType SecondType) {
     const VectorType *FirstVecType = FirstType->getAs<VectorType>();
     const VectorType *SecondVecType = SecondType->getAs<VectorType>();
 
     if (FirstVecType && SecondVecType)
       return FirstVecType->getVectorKind() == VectorType::GenericVector &&
              (SecondVecType->getVectorKind() ==
                   VectorType::SveFixedLengthDataVector ||
               SecondVecType->getVectorKind() ==
                   VectorType::SveFixedLengthPredicateVector);
 
     return FirstType->isSizelessBuiltinType() && SecondVecType &&
            SecondVecType->getVectorKind() == VectorType::GenericVector;
   };
 
   if (IsSveGnuConversion(LHSType, RHSType) ||
       IsSveGnuConversion(RHSType, LHSType)) {
     Diag(Loc, diag::err_typecheck_sve_gnu_ambiguous) << 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 (anyAltivecTypes(RHSType, LHSType) &&
         !areSameVectorElemTypes(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 (LHSTy->isPromotableIntegerType())
         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.getMinSignedBits();
   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.getMinSignedBits() << 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->getAs<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->getAs<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;
 
   // 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 (IntType->isPromotableIntegerType())
       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);
 
   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);
 
   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());
 
     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();
   }
 
   if (getLangOpts().CPlusPlus) {
     // 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.
     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();
       }
     }
 
     // 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 (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 LHSType;
 
   // 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->getElementType(),
                              RHSMatType->getElementType()))
       return InvalidOperands(Loc, LHS, RHS);
 
     return Context.getConstantMatrixType(LHSMatType->getElementType(),
                                          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);
 
   // 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();
   }
 
   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);
     } else {
       // C++20 [expr.ass]p6:
       //   [Compound-assignment] expressions are deprecated if E1 has
       //   volatile-qualified type and op is not one of the bitwise
       //   operators |, &, ˆ.
       switch (Opc) {
       case BO_OrAssign:
       case BO_AndAssign:
       case BO_XorAssign:
         break;
       default:
         Diag(Loc, diag::warn_deprecated_compound_assign_volatile) << LHSType;
       }
     }
   }
 
   // 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();
 }
 
 // Only ignore explicit casts to void.
 static bool IgnoreCommaOperand(const Expr *E) {
   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;
     }
   }
 
   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))
     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());
 
   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) {
   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();
   }
 
   // Note that per both C89 and C99, indirection is always legal, even if Result
   // is an incomplete type or void.  It would be possible to warn about
   // dereferencing a void pointer, but it's completely well-defined, and such a
   // warning is unlikely to catch any mistakes. In C++, indirection is not valid
   // for pointers to 'void' but is fine for any other pointer type:
   //
   // 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
   if (S.getLangOpts().CPlusPlus && Result->isVoidType())
     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);
     LLVM_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);
     LLVM_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());
 }
 
 /// Returns true if the given expression can be evaluated as a constant
 /// 'true'.
 static bool EvaluatesAsTrue(Sema &S, Expr *E) {
   bool Res;
   return !E->isValueDependent() &&
          E->EvaluateAsBooleanCondition(Res, S.getASTContext()) && Res;
 }
 
 /// Returns true if the given expression can be evaluated as a constant
 /// 'false'.
 static bool EvaluatesAsFalse(Sema &S, Expr *E) {
   bool Res;
   return !E->isValueDependent() &&
          E->EvaluateAsBooleanCondition(Res, S.getASTContext()) && !Res;
 }
 
 /// 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 "a && b || 0" don't warn since the precedence doesn't matter.
       if (EvaluatesAsFalse(S, RHSExpr))
         return;
       // If it's "1 && a || b" don't warn since the precedence doesn't matter.
       if (!EvaluatesAsTrue(S, Bop->getLHS()))
         return EmitDiagnosticForLogicalAndInLogicalOr(S, OpLoc, Bop);
     } else if (Bop->getOpcode() == BO_LOr) {
       if (BinaryOperator *RBop = dyn_cast<BinaryOperator>(Bop->getRHS())) {
         // If it's "a || b && 1 || c" we didn't warn earlier for
         // "a || b && 1", but warn now.
         if (RBop->getOpcode() == BO_LAnd && EvaluatesAsTrue(S, RBop->getRHS()))
           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 "0 || a && b" don't warn since the precedence doesn't matter.
       if (EvaluatesAsFalse(S, LHSExpr))
         return;
       // If it's "a || b && 1" don't warn since the precedence doesn't matter.
       if (!EvaluatesAsTrue(S, Bop->getRHS()))
         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:
   case BO_DivAssign:
   case BO_RemAssign:
   case BO_SubAssign:
   case BO_AndAssign:
   case BO_OrAssign:
   case BO_XorAssign:
     DiagnoseSelfAssignment(S, LHS, RHS, OpLoc, false);
     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 (!T->isPromotableIntegerType())
     return true;
 
   return Ctx.getIntWidth(T) >= Ctx.getIntWidth(Ctx.IntTy);
 }
 
 ExprResult Sema::CreateBuiltinUnaryOp(SourceLocation OpLoc,
                                       UnaryOperatorKind Opc,
                                       Expr *InputExpr) {
   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) {
     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);
     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;
     }
 
     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) {
   // 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);
 }
 
 // Unary Operators.  'Tok' is the token for the operator.
 ExprResult Sema::ActOnUnaryOp(Scope *S, SourceLocation OpLoc,
                               tok::TokenKind Op, Expr *Input) {
   return BuildUnaryOp(S, OpLoc, ConvertTokenKindToUnaryOpcode(Op), Input);
 }
 
 /// 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*'.
   return new (Context) AddrLabelExpr(OpLoc, LabLoc, TheDecl,
                                      Context.getPointerType(Context.VoidTy));
 }
 
 void Sema::ActOnStartStmtExpr() {
   PushExpressionEvaluationContext(ExprEvalContexts.back().Context);
 }
 
 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, None, 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);
     }
   }
 }
 
 /// 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, None, 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, None, 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;
 
     VarDecl *Var = 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);
 
   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().OpenMPIsDevice &&
       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 (TInfo->getType()->isPromotableIntegerType()) {
       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(0);
   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::Function: {
     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 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();
   ExprEvalContexts.back().InImmediateFunctionContext =
       ExprEvalContexts[ExprEvalContexts.size() - 2]
           .isImmediateFunctionContext();
 
   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());
     }
   }
 }
 
 ExprResult Sema::CheckForImmediateInvocation(ExprResult E, FunctionDecl *Decl) {
   if (isUnevaluatedContext() || !E.isUsable() || !Decl ||
       !Decl->isConsteval() || isConstantEvaluated() ||
       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);
 
   E = MaybeCreateExprWithCleanups(E);
 
   ConstantExpr *Res = ConstantExpr::Create(
       getASTContext(), E.get(),
       ConstantExpr::getStorageKind(Decl->getReturnType().getTypePtr(),
                                    getASTContext()),
       /*IsImmediateInvocation*/ true);
   /// 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->isConsteval());
     SemaRef.Diag(CE->getBeginLoc(), diag::err_invalid_consteval_call) << 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;
                              });
-      assert(It != IISet.rend() &&
-             "ConstantExpr marked IsImmediateInvocation should "
-             "be present");
-      It->setInt(1); // Mark as deleted
+      // 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());
   assert(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 then 1 ImmediateInvocationCandidates we need to check
-  /// for nested ImmediateInvocationCandidates. when we have only 1 we only
-  /// need to remove ReferenceToConsteval in the immediate invocation.
-  if (Rec.ImmediateInvocationCandidates.size() > 1) {
+  /// 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<bool> 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) {
     auto *FD = cast<FunctionDecl>(DR->getDecl());
     SemaRef.Diag(DR->getBeginLoc(), diag::err_invalid_consteval_take_address)
         << FD;
     SemaRef.Diag(FD->getLocation(), diag::note_declared_at);
   }
 }
 
 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 (getLangOpts().SYCLIsDevice)
     checkSYCLDeviceFunction(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);
         }
       }
     });
   }
 
   // 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(VarDecl *Var, 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.
   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(Var);
   SemaRef.tryCaptureVariable(Var, 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);
     }
   }
 
   Var->markUsed(SemaRef.Context);
 }
 
 void Sema::MarkCaptureUsedInEnclosingContext(VarDecl *Capture,
                                              SourceLocation Loc,
                                              unsigned CapturingScopeIndex) {
   MarkVarDeclODRUsed(Capture, Loc, *this, &CapturingScopeIndex);
 }
 
 static void diagnoseUncapturableValueReference(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, VarDecl *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, VarDecl *Var,
                                  SourceLocation Loc,
                                  const bool Diagnose, Sema &S) {
   if (isa<BlockDecl>(DC) || isa<CapturedDecl>(DC) || isLambdaCallOperator(DC))
     return getLambdaAwareParentOfDeclContext(DC);
   else if (Var->hasLocalStorage()) {
     if (Diagnose)
        diagnoseUncapturableValueReference(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, VarDecl *Var,
                                  SourceLocation Loc,
                                  const bool Diagnose, Sema &S) {
 
   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;
   }
 
   return true;
 }
 
 // Returns true if the capture by block was successful.
 static bool captureInBlock(BlockScopeInfo *BSI, VarDecl *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, VarDecl *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,
                             VarDecl *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);
   }
 
   // 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(VarDecl *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,
                                     VarDecl *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(
     VarDecl *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();
   if (Var->isInitCapture())
     VarDC = VarDC->getParent();
 
   DeclContext *DC = CurContext;
   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;
     }
   }
 
 
   // If the variable is declared in the current context, there is no need to
   // capture it.
   if (VarDC == DC) return true;
 
   // Capture global variables if it is required to use private copy of this
   // variable.
   bool IsGlobal = !Var->hasLocalStorage();
   if (IsGlobal &&
       !(LangOpts.OpenMP && isOpenMPCapturedDecl(Var, /*CheckScopeInfo=*/true,
                                                 MaxFunctionScopesIndex)))
     return true;
   Var = 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 {
     // Only block literals, captured statements, and lambda expressions can
     // capture; other scopes don't work.
     DeclContext *ParentDC = 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;
     }
     // 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
           diagnoseUncapturableValueReference(*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;
     }
 
     FunctionScopesIndex--;
     DC = ParentDC;
     Explicit = false;
   } 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(VarDecl *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(VarDecl *Var, SourceLocation Loc) {
   QualType CaptureType;
   QualType DeclRefType;
   return !tryCaptureVariable(Var, Loc, TryCapture_Implicit, SourceLocation(),
                              /*BuildAndDiagnose=*/false, CaptureType,
                              DeclRefType, nullptr);
 }
 
 QualType Sema::getCapturedDeclRefType(VarDecl *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);
       }
     }
 
     return AnyChanged ? S.CreateGenericSelectionExpr(
                             GSE->getGenericLoc(), GSE->getDefaultLoc(),
                             GSE->getRParenLoc(), GSE->getControllingExpr(),
                             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 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 ||
                  isa<VarTemplateSpecializationDecl>(Var)) {
         // 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.
         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:
     assert((!E || isa<FunctionParmPackExpr>(E)) &&
            "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)?
     const bool RefersToEnclosingScope =
         (SemaRef.CurContext != Var->getDeclContext() &&
          Var->getDeclContext()->isFunctionOrMethod() && Var->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() ||
             !Var->isUsableInConstantExpressions(SemaRef.Context))
           LSI->addPotentialCapture(E->IgnoreParens());
       }
     }
     break;
   }
 }
 
 /// 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;
   }
 
   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() &&
         FD->isConsteval() && !RebuildingImmediateInvocation)
       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::makeArrayRef(Statement) : llvm::None, 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 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) -> 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 None;
     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);
 }