Index: head/contrib/llvm/tools/clang/include/clang/AST/DeclBase.h
===================================================================
--- head/contrib/llvm/tools/clang/include/clang/AST/DeclBase.h	(revision 349875)
+++ head/contrib/llvm/tools/clang/include/clang/AST/DeclBase.h	(revision 349876)
@@ -1,2526 +1,2526 @@
 //===- DeclBase.h - Base Classes for representing declarations --*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 //  This file defines the Decl and DeclContext interfaces.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CLANG_AST_DECLBASE_H
 #define LLVM_CLANG_AST_DECLBASE_H
 
 #include "clang/AST/AttrIterator.h"
 #include "clang/AST/DeclarationName.h"
 #include "clang/Basic/IdentifierTable.h"
 #include "clang/Basic/LLVM.h"
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Basic/Specifiers.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/PointerIntPair.h"
 #include "llvm/ADT/PointerUnion.h"
 #include "llvm/ADT/iterator.h"
 #include "llvm/ADT/iterator_range.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/PrettyStackTrace.h"
 #include "llvm/Support/VersionTuple.h"
 #include <algorithm>
 #include <cassert>
 #include <cstddef>
 #include <iterator>
 #include <string>
 #include <type_traits>
 #include <utility>
 
 namespace clang {
 
 class ASTContext;
 class ASTMutationListener;
 class Attr;
 class DeclContext;
 class ExternalSourceSymbolAttr;
 class FunctionDecl;
 class FunctionType;
 class IdentifierInfo;
 enum Linkage : unsigned char;
 class LinkageSpecDecl;
 class Module;
 class NamedDecl;
 class ObjCCategoryDecl;
 class ObjCCategoryImplDecl;
 class ObjCContainerDecl;
 class ObjCImplDecl;
 class ObjCImplementationDecl;
 class ObjCInterfaceDecl;
 class ObjCMethodDecl;
 class ObjCProtocolDecl;
 struct PrintingPolicy;
 class RecordDecl;
 class SourceManager;
 class Stmt;
 class StoredDeclsMap;
 class TemplateDecl;
 class TranslationUnitDecl;
 class UsingDirectiveDecl;
 
 /// Captures the result of checking the availability of a
 /// declaration.
 enum AvailabilityResult {
   AR_Available = 0,
   AR_NotYetIntroduced,
   AR_Deprecated,
   AR_Unavailable
 };
 
 /// Decl - This represents one declaration (or definition), e.g. a variable,
 /// typedef, function, struct, etc.
 ///
 /// Note: There are objects tacked on before the *beginning* of Decl
 /// (and its subclasses) in its Decl::operator new(). Proper alignment
 /// of all subclasses (not requiring more than the alignment of Decl) is
 /// asserted in DeclBase.cpp.
 class alignas(8) Decl {
 public:
   /// Lists the kind of concrete classes of Decl.
   enum Kind {
 #define DECL(DERIVED, BASE) DERIVED,
 #define ABSTRACT_DECL(DECL)
 #define DECL_RANGE(BASE, START, END) \
         first##BASE = START, last##BASE = END,
 #define LAST_DECL_RANGE(BASE, START, END) \
         first##BASE = START, last##BASE = END
 #include "clang/AST/DeclNodes.inc"
   };
 
   /// A placeholder type used to construct an empty shell of a
   /// decl-derived type that will be filled in later (e.g., by some
   /// deserialization method).
   struct EmptyShell {};
 
   /// IdentifierNamespace - The different namespaces in which
   /// declarations may appear.  According to C99 6.2.3, there are
   /// four namespaces, labels, tags, members and ordinary
   /// identifiers.  C++ describes lookup completely differently:
   /// certain lookups merely "ignore" certain kinds of declarations,
   /// usually based on whether the declaration is of a type, etc.
   ///
   /// These are meant as bitmasks, so that searches in
   /// C++ can look into the "tag" namespace during ordinary lookup.
   ///
   /// Decl currently provides 15 bits of IDNS bits.
   enum IdentifierNamespace {
     /// Labels, declared with 'x:' and referenced with 'goto x'.
     IDNS_Label               = 0x0001,
 
     /// Tags, declared with 'struct foo;' and referenced with
     /// 'struct foo'.  All tags are also types.  This is what
     /// elaborated-type-specifiers look for in C.
     /// This also contains names that conflict with tags in the
     /// same scope but that are otherwise ordinary names (non-type
     /// template parameters and indirect field declarations).
     IDNS_Tag                 = 0x0002,
 
     /// Types, declared with 'struct foo', typedefs, etc.
     /// This is what elaborated-type-specifiers look for in C++,
     /// but note that it's ill-formed to find a non-tag.
     IDNS_Type                = 0x0004,
 
     /// Members, declared with object declarations within tag
     /// definitions.  In C, these can only be found by "qualified"
     /// lookup in member expressions.  In C++, they're found by
     /// normal lookup.
     IDNS_Member              = 0x0008,
 
     /// Namespaces, declared with 'namespace foo {}'.
     /// Lookup for nested-name-specifiers find these.
     IDNS_Namespace           = 0x0010,
 
     /// Ordinary names.  In C, everything that's not a label, tag,
     /// member, or function-local extern ends up here.
     IDNS_Ordinary            = 0x0020,
 
     /// Objective C \@protocol.
     IDNS_ObjCProtocol        = 0x0040,
 
     /// This declaration is a friend function.  A friend function
     /// declaration is always in this namespace but may also be in
     /// IDNS_Ordinary if it was previously declared.
     IDNS_OrdinaryFriend      = 0x0080,
 
     /// This declaration is a friend class.  A friend class
     /// declaration is always in this namespace but may also be in
     /// IDNS_Tag|IDNS_Type if it was previously declared.
     IDNS_TagFriend           = 0x0100,
 
     /// This declaration is a using declaration.  A using declaration
     /// *introduces* a number of other declarations into the current
     /// scope, and those declarations use the IDNS of their targets,
     /// but the actual using declarations go in this namespace.
     IDNS_Using               = 0x0200,
 
     /// This declaration is a C++ operator declared in a non-class
     /// context.  All such operators are also in IDNS_Ordinary.
     /// C++ lexical operator lookup looks for these.
     IDNS_NonMemberOperator   = 0x0400,
 
     /// This declaration is a function-local extern declaration of a
     /// variable or function. This may also be IDNS_Ordinary if it
     /// has been declared outside any function. These act mostly like
     /// invisible friend declarations, but are also visible to unqualified
     /// lookup within the scope of the declaring function.
     IDNS_LocalExtern         = 0x0800,
 
     /// This declaration is an OpenMP user defined reduction construction.
     IDNS_OMPReduction        = 0x1000
   };
 
   /// ObjCDeclQualifier - 'Qualifiers' written next to the return and
   /// parameter types in method declarations.  Other than remembering
   /// them and mangling them into the method's signature string, these
   /// are ignored by the compiler; they are consumed by certain
   /// remote-messaging frameworks.
   ///
   /// in, inout, and out are mutually exclusive and apply only to
   /// method parameters.  bycopy and byref are mutually exclusive and
   /// apply only to method parameters (?).  oneway applies only to
   /// results.  All of these expect their corresponding parameter to
   /// have a particular type.  None of this is currently enforced by
   /// clang.
   ///
   /// This should be kept in sync with ObjCDeclSpec::ObjCDeclQualifier.
   enum ObjCDeclQualifier {
     OBJC_TQ_None = 0x0,
     OBJC_TQ_In = 0x1,
     OBJC_TQ_Inout = 0x2,
     OBJC_TQ_Out = 0x4,
     OBJC_TQ_Bycopy = 0x8,
     OBJC_TQ_Byref = 0x10,
     OBJC_TQ_Oneway = 0x20,
 
     /// The nullability qualifier is set when the nullability of the
     /// result or parameter was expressed via a context-sensitive
     /// keyword.
     OBJC_TQ_CSNullability = 0x40
   };
 
   /// The kind of ownership a declaration has, for visibility purposes.
   /// This enumeration is designed such that higher values represent higher
   /// levels of name hiding.
   enum class ModuleOwnershipKind : unsigned {
     /// This declaration is not owned by a module.
     Unowned,
 
     /// This declaration has an owning module, but is globally visible
     /// (typically because its owning module is visible and we know that
     /// modules cannot later become hidden in this compilation).
     /// After serialization and deserialization, this will be converted
     /// to VisibleWhenImported.
     Visible,
 
     /// This declaration has an owning module, and is visible when that
     /// module is imported.
     VisibleWhenImported,
 
     /// This declaration has an owning module, but is only visible to
     /// lookups that occur within that module.
     ModulePrivate
   };
 
 protected:
   /// The next declaration within the same lexical
   /// DeclContext. These pointers form the linked list that is
   /// traversed via DeclContext's decls_begin()/decls_end().
   ///
   /// The extra two bits are used for the ModuleOwnershipKind.
   llvm::PointerIntPair<Decl *, 2, ModuleOwnershipKind> NextInContextAndBits;
 
 private:
   friend class DeclContext;
 
   struct MultipleDC {
     DeclContext *SemanticDC;
     DeclContext *LexicalDC;
   };
 
   /// DeclCtx - Holds either a DeclContext* or a MultipleDC*.
   /// For declarations that don't contain C++ scope specifiers, it contains
   /// the DeclContext where the Decl was declared.
   /// For declarations with C++ scope specifiers, it contains a MultipleDC*
   /// with the context where it semantically belongs (SemanticDC) and the
   /// context where it was lexically declared (LexicalDC).
   /// e.g.:
   ///
   ///   namespace A {
   ///      void f(); // SemanticDC == LexicalDC == 'namespace A'
   ///   }
   ///   void A::f(); // SemanticDC == namespace 'A'
   ///                // LexicalDC == global namespace
   llvm::PointerUnion<DeclContext*, MultipleDC*> DeclCtx;
 
   bool isInSemaDC() const { return DeclCtx.is<DeclContext*>(); }
   bool isOutOfSemaDC() const { return DeclCtx.is<MultipleDC*>(); }
 
   MultipleDC *getMultipleDC() const {
     return DeclCtx.get<MultipleDC*>();
   }
 
   DeclContext *getSemanticDC() const {
     return DeclCtx.get<DeclContext*>();
   }
 
   /// Loc - The location of this decl.
   SourceLocation Loc;
 
   /// DeclKind - This indicates which class this is.
   unsigned DeclKind : 7;
 
   /// InvalidDecl - This indicates a semantic error occurred.
   unsigned InvalidDecl :  1;
 
   /// HasAttrs - This indicates whether the decl has attributes or not.
   unsigned HasAttrs : 1;
 
   /// Implicit - Whether this declaration was implicitly generated by
   /// the implementation rather than explicitly written by the user.
   unsigned Implicit : 1;
 
   /// Whether this declaration was "used", meaning that a definition is
   /// required.
   unsigned Used : 1;
 
   /// Whether this declaration was "referenced".
   /// The difference with 'Used' is whether the reference appears in a
   /// evaluated context or not, e.g. functions used in uninstantiated templates
   /// are regarded as "referenced" but not "used".
   unsigned Referenced : 1;
 
   /// Whether this declaration is a top-level declaration (function,
   /// global variable, etc.) that is lexically inside an objc container
   /// definition.
   unsigned TopLevelDeclInObjCContainer : 1;
 
   /// Whether statistic collection is enabled.
   static bool StatisticsEnabled;
 
 protected:
   friend class ASTDeclReader;
   friend class ASTDeclWriter;
   friend class ASTNodeImporter;
   friend class ASTReader;
   friend class CXXClassMemberWrapper;
   friend class LinkageComputer;
   template<typename decl_type> friend class Redeclarable;
 
   /// Access - Used by C++ decls for the access specifier.
   // NOTE: VC++ treats enums as signed, avoid using the AccessSpecifier enum
   unsigned Access : 2;
 
   /// Whether this declaration was loaded from an AST file.
   unsigned FromASTFile : 1;
 
   /// IdentifierNamespace - This specifies what IDNS_* namespace this lives in.
   unsigned IdentifierNamespace : 13;
 
   /// If 0, we have not computed the linkage of this declaration.
   /// Otherwise, it is the linkage + 1.
   mutable unsigned CacheValidAndLinkage : 3;
 
   /// Allocate memory for a deserialized declaration.
   ///
   /// This routine must be used to allocate memory for any declaration that is
   /// deserialized from a module file.
   ///
   /// \param Size The size of the allocated object.
   /// \param Ctx The context in which we will allocate memory.
   /// \param ID The global ID of the deserialized declaration.
   /// \param Extra The amount of extra space to allocate after the object.
   void *operator new(std::size_t Size, const ASTContext &Ctx, unsigned ID,
                      std::size_t Extra = 0);
 
   /// Allocate memory for a non-deserialized declaration.
   void *operator new(std::size_t Size, const ASTContext &Ctx,
                      DeclContext *Parent, std::size_t Extra = 0);
 
 private:
   bool AccessDeclContextSanity() const;
 
   /// Get the module ownership kind to use for a local lexical child of \p DC,
   /// which may be either a local or (rarely) an imported declaration.
   static ModuleOwnershipKind getModuleOwnershipKindForChildOf(DeclContext *DC) {
     if (DC) {
       auto *D = cast<Decl>(DC);
       auto MOK = D->getModuleOwnershipKind();
       if (MOK != ModuleOwnershipKind::Unowned &&
           (!D->isFromASTFile() || D->hasLocalOwningModuleStorage()))
         return MOK;
       // If D is not local and we have no local module storage, then we don't
       // need to track module ownership at all.
     }
     return ModuleOwnershipKind::Unowned;
   }
 
 protected:
   Decl(Kind DK, DeclContext *DC, SourceLocation L)
       : NextInContextAndBits(nullptr, getModuleOwnershipKindForChildOf(DC)),
         DeclCtx(DC), Loc(L), DeclKind(DK), InvalidDecl(false), HasAttrs(false),
         Implicit(false), Used(false), Referenced(false),
         TopLevelDeclInObjCContainer(false), Access(AS_none), FromASTFile(0),
         IdentifierNamespace(getIdentifierNamespaceForKind(DK)),
         CacheValidAndLinkage(0) {
     if (StatisticsEnabled) add(DK);
   }
 
   Decl(Kind DK, EmptyShell Empty)
       : DeclKind(DK), InvalidDecl(false), HasAttrs(false), Implicit(false),
         Used(false), Referenced(false), TopLevelDeclInObjCContainer(false),
         Access(AS_none), FromASTFile(0),
         IdentifierNamespace(getIdentifierNamespaceForKind(DK)),
         CacheValidAndLinkage(0) {
     if (StatisticsEnabled) add(DK);
   }
 
   virtual ~Decl();
 
   /// Update a potentially out-of-date declaration.
   void updateOutOfDate(IdentifierInfo &II) const;
 
   Linkage getCachedLinkage() const {
     return Linkage(CacheValidAndLinkage - 1);
   }
 
   void setCachedLinkage(Linkage L) const {
     CacheValidAndLinkage = L + 1;
   }
 
   bool hasCachedLinkage() const {
     return CacheValidAndLinkage;
   }
 
 public:
   /// Source range that this declaration covers.
   virtual SourceRange getSourceRange() const LLVM_READONLY {
     return SourceRange(getLocation(), getLocation());
   }
 
   SourceLocation getBeginLoc() const LLVM_READONLY {
     return getSourceRange().getBegin();
   }
 
   SourceLocation getEndLoc() const LLVM_READONLY {
     return getSourceRange().getEnd();
   }
 
   SourceLocation getLocation() const { return Loc; }
   void setLocation(SourceLocation L) { Loc = L; }
 
   Kind getKind() const { return static_cast<Kind>(DeclKind); }
   const char *getDeclKindName() const;
 
   Decl *getNextDeclInContext() { return NextInContextAndBits.getPointer(); }
   const Decl *getNextDeclInContext() const {return NextInContextAndBits.getPointer();}
 
   DeclContext *getDeclContext() {
     if (isInSemaDC())
       return getSemanticDC();
     return getMultipleDC()->SemanticDC;
   }
   const DeclContext *getDeclContext() const {
     return const_cast<Decl*>(this)->getDeclContext();
   }
 
   /// Find the innermost non-closure ancestor of this declaration,
   /// walking up through blocks, lambdas, etc.  If that ancestor is
   /// not a code context (!isFunctionOrMethod()), returns null.
   ///
   /// A declaration may be its own non-closure context.
   Decl *getNonClosureContext();
   const Decl *getNonClosureContext() const {
     return const_cast<Decl*>(this)->getNonClosureContext();
   }
 
   TranslationUnitDecl *getTranslationUnitDecl();
   const TranslationUnitDecl *getTranslationUnitDecl() const {
     return const_cast<Decl*>(this)->getTranslationUnitDecl();
   }
 
   bool isInAnonymousNamespace() const;
 
   bool isInStdNamespace() const;
 
   ASTContext &getASTContext() const LLVM_READONLY;
 
   void setAccess(AccessSpecifier AS) {
     Access = AS;
     assert(AccessDeclContextSanity());
   }
 
   AccessSpecifier getAccess() const {
     assert(AccessDeclContextSanity());
     return AccessSpecifier(Access);
   }
 
   /// Retrieve the access specifier for this declaration, even though
   /// it may not yet have been properly set.
   AccessSpecifier getAccessUnsafe() const {
     return AccessSpecifier(Access);
   }
 
   bool hasAttrs() const { return HasAttrs; }
 
   void setAttrs(const AttrVec& Attrs) {
     return setAttrsImpl(Attrs, getASTContext());
   }
 
   AttrVec &getAttrs() {
     return const_cast<AttrVec&>(const_cast<const Decl*>(this)->getAttrs());
   }
 
   const AttrVec &getAttrs() const;
   void dropAttrs();
   void addAttr(Attr *A);
 
   using attr_iterator = AttrVec::const_iterator;
   using attr_range = llvm::iterator_range<attr_iterator>;
 
   attr_range attrs() const {
     return attr_range(attr_begin(), attr_end());
   }
 
   attr_iterator attr_begin() const {
     return hasAttrs() ? getAttrs().begin() : nullptr;
   }
   attr_iterator attr_end() const {
     return hasAttrs() ? getAttrs().end() : nullptr;
   }
 
   template <typename T>
   void dropAttr() {
     if (!HasAttrs) return;
 
     AttrVec &Vec = getAttrs();
     Vec.erase(std::remove_if(Vec.begin(), Vec.end(), isa<T, Attr*>), Vec.end());
 
     if (Vec.empty())
       HasAttrs = false;
   }
 
   template <typename T>
   llvm::iterator_range<specific_attr_iterator<T>> specific_attrs() const {
     return llvm::make_range(specific_attr_begin<T>(), specific_attr_end<T>());
   }
 
   template <typename T>
   specific_attr_iterator<T> specific_attr_begin() const {
     return specific_attr_iterator<T>(attr_begin());
   }
 
   template <typename T>
   specific_attr_iterator<T> specific_attr_end() const {
     return specific_attr_iterator<T>(attr_end());
   }
 
   template<typename T> T *getAttr() const {
     return hasAttrs() ? getSpecificAttr<T>(getAttrs()) : nullptr;
   }
 
   template<typename T> bool hasAttr() const {
     return hasAttrs() && hasSpecificAttr<T>(getAttrs());
   }
 
   /// getMaxAlignment - return the maximum alignment specified by attributes
   /// on this decl, 0 if there are none.
   unsigned getMaxAlignment() const;
 
   /// setInvalidDecl - Indicates the Decl had a semantic error. This
   /// allows for graceful error recovery.
   void setInvalidDecl(bool Invalid = true);
   bool isInvalidDecl() const { return (bool) InvalidDecl; }
 
   /// isImplicit - Indicates whether the declaration was implicitly
   /// generated by the implementation. If false, this declaration
   /// was written explicitly in the source code.
   bool isImplicit() const { return Implicit; }
   void setImplicit(bool I = true) { Implicit = I; }
 
   /// Whether *any* (re-)declaration of the entity was used, meaning that
   /// a definition is required.
   ///
   /// \param CheckUsedAttr When true, also consider the "used" attribute
   /// (in addition to the "used" bit set by \c setUsed()) when determining
   /// whether the function is used.
   bool isUsed(bool CheckUsedAttr = true) const;
 
   /// Set whether the declaration is used, in the sense of odr-use.
   ///
   /// This should only be used immediately after creating a declaration.
   /// It intentionally doesn't notify any listeners.
   void setIsUsed() { getCanonicalDecl()->Used = true; }
 
   /// Mark the declaration used, in the sense of odr-use.
   ///
   /// This notifies any mutation listeners in addition to setting a bit
   /// indicating the declaration is used.
   void markUsed(ASTContext &C);
 
   /// Whether any declaration of this entity was referenced.
   bool isReferenced() const;
 
   /// Whether this declaration was referenced. This should not be relied
   /// upon for anything other than debugging.
   bool isThisDeclarationReferenced() const { return Referenced; }
 
   void setReferenced(bool R = true) { Referenced = R; }
 
   /// Whether this declaration is a top-level declaration (function,
   /// global variable, etc.) that is lexically inside an objc container
   /// definition.
   bool isTopLevelDeclInObjCContainer() const {
     return TopLevelDeclInObjCContainer;
   }
 
   void setTopLevelDeclInObjCContainer(bool V = true) {
     TopLevelDeclInObjCContainer = V;
   }
 
   /// Looks on this and related declarations for an applicable
   /// external source symbol attribute.
   ExternalSourceSymbolAttr *getExternalSourceSymbolAttr() const;
 
   /// Whether this declaration was marked as being private to the
   /// module in which it was defined.
   bool isModulePrivate() const {
     return getModuleOwnershipKind() == ModuleOwnershipKind::ModulePrivate;
   }
 
   /// Whether this declaration is exported (by virtue of being lexically
   /// within an ExportDecl or by being a NamespaceDecl).
   bool isExported() const;
 
   /// Return true if this declaration has an attribute which acts as
   /// definition of the entity, such as 'alias' or 'ifunc'.
   bool hasDefiningAttr() const;
 
   /// Return this declaration's defining attribute if it has one.
   const Attr *getDefiningAttr() const;
 
 protected:
   /// Specify that this declaration was marked as being private
   /// to the module in which it was defined.
   void setModulePrivate() {
     // The module-private specifier has no effect on unowned declarations.
     // FIXME: We should track this in some way for source fidelity.
     if (getModuleOwnershipKind() == ModuleOwnershipKind::Unowned)
       return;
     setModuleOwnershipKind(ModuleOwnershipKind::ModulePrivate);
   }
 
   /// Set the owning module ID.
   void setOwningModuleID(unsigned ID) {
     assert(isFromASTFile() && "Only works on a deserialized declaration");
     *((unsigned*)this - 2) = ID;
   }
 
 public:
   /// Determine the availability of the given declaration.
   ///
   /// This routine will determine the most restrictive availability of
   /// the given declaration (e.g., preferring 'unavailable' to
   /// 'deprecated').
   ///
   /// \param Message If non-NULL and the result is not \c
   /// AR_Available, will be set to a (possibly empty) message
   /// describing why the declaration has not been introduced, is
   /// deprecated, or is unavailable.
   ///
   /// \param EnclosingVersion The version to compare with. If empty, assume the
   /// deployment target version.
   ///
   /// \param RealizedPlatform If non-NULL and the availability result is found
   /// in an available attribute it will set to the platform which is written in
   /// the available attribute.
   AvailabilityResult
   getAvailability(std::string *Message = nullptr,
                   VersionTuple EnclosingVersion = VersionTuple(),
                   StringRef *RealizedPlatform = nullptr) const;
 
   /// Retrieve the version of the target platform in which this
   /// declaration was introduced.
   ///
   /// \returns An empty version tuple if this declaration has no 'introduced'
   /// availability attributes, or the version tuple that's specified in the
   /// attribute otherwise.
   VersionTuple getVersionIntroduced() const;
 
   /// Determine whether this declaration is marked 'deprecated'.
   ///
   /// \param Message If non-NULL and the declaration is deprecated,
   /// this will be set to the message describing why the declaration
   /// was deprecated (which may be empty).
   bool isDeprecated(std::string *Message = nullptr) const {
     return getAvailability(Message) == AR_Deprecated;
   }
 
   /// Determine whether this declaration is marked 'unavailable'.
   ///
   /// \param Message If non-NULL and the declaration is unavailable,
   /// this will be set to the message describing why the declaration
   /// was made unavailable (which may be empty).
   bool isUnavailable(std::string *Message = nullptr) const {
     return getAvailability(Message) == AR_Unavailable;
   }
 
   /// Determine whether this is a weak-imported symbol.
   ///
   /// Weak-imported symbols are typically marked with the
   /// 'weak_import' attribute, but may also be marked with an
   /// 'availability' attribute where we're targing a platform prior to
   /// the introduction of this feature.
   bool isWeakImported() const;
 
   /// Determines whether this symbol can be weak-imported,
   /// e.g., whether it would be well-formed to add the weak_import
   /// attribute.
   ///
   /// \param IsDefinition Set to \c true to indicate that this
   /// declaration cannot be weak-imported because it has a definition.
   bool canBeWeakImported(bool &IsDefinition) const;
 
   /// Determine whether this declaration came from an AST file (such as
   /// a precompiled header or module) rather than having been parsed.
   bool isFromASTFile() const { return FromASTFile; }
 
   /// Retrieve the global declaration ID associated with this
   /// declaration, which specifies where this Decl was loaded from.
   unsigned getGlobalID() const {
     if (isFromASTFile())
       return *((const unsigned*)this - 1);
     return 0;
   }
 
   /// Retrieve the global ID of the module that owns this particular
   /// declaration.
   unsigned getOwningModuleID() const {
     if (isFromASTFile())
       return *((const unsigned*)this - 2);
     return 0;
   }
 
 private:
   Module *getOwningModuleSlow() const;
 
 protected:
   bool hasLocalOwningModuleStorage() const;
 
 public:
   /// Get the imported owning module, if this decl is from an imported
   /// (non-local) module.
   Module *getImportedOwningModule() const {
     if (!isFromASTFile() || !hasOwningModule())
       return nullptr;
 
     return getOwningModuleSlow();
   }
 
   /// Get the local owning module, if known. Returns nullptr if owner is
   /// not yet known or declaration is not from a module.
   Module *getLocalOwningModule() const {
     if (isFromASTFile() || !hasOwningModule())
       return nullptr;
 
     assert(hasLocalOwningModuleStorage() &&
            "owned local decl but no local module storage");
     return reinterpret_cast<Module *const *>(this)[-1];
   }
   void setLocalOwningModule(Module *M) {
     assert(!isFromASTFile() && hasOwningModule() &&
            hasLocalOwningModuleStorage() &&
            "should not have a cached owning module");
     reinterpret_cast<Module **>(this)[-1] = M;
   }
 
   /// Is this declaration owned by some module?
   bool hasOwningModule() const {
     return getModuleOwnershipKind() != ModuleOwnershipKind::Unowned;
   }
 
   /// Get the module that owns this declaration (for visibility purposes).
   Module *getOwningModule() const {
     return isFromASTFile() ? getImportedOwningModule() : getLocalOwningModule();
   }
 
   /// Get the module that owns this declaration for linkage purposes.
   /// There only ever is such a module under the C++ Modules TS.
   ///
   /// \param IgnoreLinkage Ignore the linkage of the entity; assume that
   /// all declarations in a global module fragment are unowned.
   Module *getOwningModuleForLinkage(bool IgnoreLinkage = false) const;
 
   /// Determine whether this declaration might be hidden from name
   /// lookup. Note that the declaration might be visible even if this returns
   /// \c false, if the owning module is visible within the query context.
   // FIXME: Rename this to make it clearer what it does.
   bool isHidden() const {
     return (int)getModuleOwnershipKind() > (int)ModuleOwnershipKind::Visible;
   }
 
   /// Set that this declaration is globally visible, even if it came from a
   /// module that is not visible.
   void setVisibleDespiteOwningModule() {
     if (isHidden())
       setModuleOwnershipKind(ModuleOwnershipKind::Visible);
   }
 
   /// Get the kind of module ownership for this declaration.
   ModuleOwnershipKind getModuleOwnershipKind() const {
     return NextInContextAndBits.getInt();
   }
 
   /// Set whether this declaration is hidden from name lookup.
   void setModuleOwnershipKind(ModuleOwnershipKind MOK) {
     assert(!(getModuleOwnershipKind() == ModuleOwnershipKind::Unowned &&
              MOK != ModuleOwnershipKind::Unowned && !isFromASTFile() &&
              !hasLocalOwningModuleStorage()) &&
            "no storage available for owning module for this declaration");
     NextInContextAndBits.setInt(MOK);
   }
 
   unsigned getIdentifierNamespace() const {
     return IdentifierNamespace;
   }
 
   bool isInIdentifierNamespace(unsigned NS) const {
     return getIdentifierNamespace() & NS;
   }
 
   static unsigned getIdentifierNamespaceForKind(Kind DK);
 
   bool hasTagIdentifierNamespace() const {
     return isTagIdentifierNamespace(getIdentifierNamespace());
   }
 
   static bool isTagIdentifierNamespace(unsigned NS) {
     // TagDecls have Tag and Type set and may also have TagFriend.
     return (NS & ~IDNS_TagFriend) == (IDNS_Tag | IDNS_Type);
   }
 
   /// getLexicalDeclContext - The declaration context where this Decl was
   /// lexically declared (LexicalDC). May be different from
   /// getDeclContext() (SemanticDC).
   /// e.g.:
   ///
   ///   namespace A {
   ///      void f(); // SemanticDC == LexicalDC == 'namespace A'
   ///   }
   ///   void A::f(); // SemanticDC == namespace 'A'
   ///                // LexicalDC == global namespace
   DeclContext *getLexicalDeclContext() {
     if (isInSemaDC())
       return getSemanticDC();
     return getMultipleDC()->LexicalDC;
   }
   const DeclContext *getLexicalDeclContext() const {
     return const_cast<Decl*>(this)->getLexicalDeclContext();
   }
 
   /// Determine whether this declaration is declared out of line (outside its
   /// semantic context).
   virtual bool isOutOfLine() const;
 
   /// setDeclContext - Set both the semantic and lexical DeclContext
   /// to DC.
   void setDeclContext(DeclContext *DC);
 
   void setLexicalDeclContext(DeclContext *DC);
 
   /// Determine whether this declaration is a templated entity (whether it is
   // within the scope of a template parameter).
   bool isTemplated() const;
 
   /// isDefinedOutsideFunctionOrMethod - This predicate returns true if this
   /// scoped decl is defined outside the current function or method.  This is
   /// roughly global variables and functions, but also handles enums (which
   /// could be defined inside or outside a function etc).
   bool isDefinedOutsideFunctionOrMethod() const {
     return getParentFunctionOrMethod() == nullptr;
   }
 
   /// Returns true if this declaration lexically is inside a function.
   /// It recognizes non-defining declarations as well as members of local
   /// classes:
   /// \code
   ///     void foo() { void bar(); }
   ///     void foo2() { class ABC { void bar(); }; }
   /// \endcode
   bool isLexicallyWithinFunctionOrMethod() const;
 
   /// If this decl is defined inside a function/method/block it returns
   /// the corresponding DeclContext, otherwise it returns null.
   const DeclContext *getParentFunctionOrMethod() const;
   DeclContext *getParentFunctionOrMethod() {
     return const_cast<DeclContext*>(
                     const_cast<const Decl*>(this)->getParentFunctionOrMethod());
   }
 
   /// Retrieves the "canonical" declaration of the given declaration.
   virtual Decl *getCanonicalDecl() { return this; }
   const Decl *getCanonicalDecl() const {
     return const_cast<Decl*>(this)->getCanonicalDecl();
   }
 
   /// Whether this particular Decl is a canonical one.
   bool isCanonicalDecl() const { return getCanonicalDecl() == this; }
 
 protected:
   /// Returns the next redeclaration or itself if this is the only decl.
   ///
   /// Decl subclasses that can be redeclared should override this method so that
   /// Decl::redecl_iterator can iterate over them.
   virtual Decl *getNextRedeclarationImpl() { return this; }
 
   /// Implementation of getPreviousDecl(), to be overridden by any
   /// subclass that has a redeclaration chain.
   virtual Decl *getPreviousDeclImpl() { return nullptr; }
 
   /// Implementation of getMostRecentDecl(), to be overridden by any
   /// subclass that has a redeclaration chain.
   virtual Decl *getMostRecentDeclImpl() { return this; }
 
 public:
   /// Iterates through all the redeclarations of the same decl.
   class redecl_iterator {
     /// Current - The current declaration.
     Decl *Current = nullptr;
     Decl *Starter;
 
   public:
     using value_type = Decl *;
     using reference = const value_type &;
     using pointer = const value_type *;
     using iterator_category = std::forward_iterator_tag;
     using difference_type = std::ptrdiff_t;
 
     redecl_iterator() = default;
     explicit redecl_iterator(Decl *C) : Current(C), Starter(C) {}
 
     reference operator*() const { return Current; }
     value_type operator->() const { return Current; }
 
     redecl_iterator& operator++() {
       assert(Current && "Advancing while iterator has reached end");
       // Get either previous decl or latest decl.
       Decl *Next = Current->getNextRedeclarationImpl();
       assert(Next && "Should return next redeclaration or itself, never null!");
       Current = (Next != Starter) ? Next : nullptr;
       return *this;
     }
 
     redecl_iterator operator++(int) {
       redecl_iterator tmp(*this);
       ++(*this);
       return tmp;
     }
 
     friend bool operator==(redecl_iterator x, redecl_iterator y) {
       return x.Current == y.Current;
     }
 
     friend bool operator!=(redecl_iterator x, redecl_iterator y) {
       return x.Current != y.Current;
     }
   };
 
   using redecl_range = llvm::iterator_range<redecl_iterator>;
 
   /// Returns an iterator range for all the redeclarations of the same
   /// decl. It will iterate at least once (when this decl is the only one).
   redecl_range redecls() const {
     return redecl_range(redecls_begin(), redecls_end());
   }
 
   redecl_iterator redecls_begin() const {
     return redecl_iterator(const_cast<Decl *>(this));
   }
 
   redecl_iterator redecls_end() const { return redecl_iterator(); }
 
   /// Retrieve the previous declaration that declares the same entity
   /// as this declaration, or NULL if there is no previous declaration.
   Decl *getPreviousDecl() { return getPreviousDeclImpl(); }
 
   /// Retrieve the most recent declaration that declares the same entity
   /// as this declaration, or NULL if there is no previous declaration.
   const Decl *getPreviousDecl() const {
     return const_cast<Decl *>(this)->getPreviousDeclImpl();
   }
 
   /// True if this is the first declaration in its redeclaration chain.
   bool isFirstDecl() const {
     return getPreviousDecl() == nullptr;
   }
 
   /// Retrieve the most recent declaration that declares the same entity
   /// as this declaration (which may be this declaration).
   Decl *getMostRecentDecl() { return getMostRecentDeclImpl(); }
 
   /// Retrieve the most recent declaration that declares the same entity
   /// as this declaration (which may be this declaration).
   const Decl *getMostRecentDecl() const {
     return const_cast<Decl *>(this)->getMostRecentDeclImpl();
   }
 
   /// getBody - If this Decl represents a declaration for a body of code,
   ///  such as a function or method definition, this method returns the
   ///  top-level Stmt* of that body.  Otherwise this method returns null.
   virtual Stmt* getBody() const { return nullptr; }
 
   /// Returns true if this \c Decl represents a declaration for a body of
   /// code, such as a function or method definition.
   /// Note that \c hasBody can also return true if any redeclaration of this
   /// \c Decl represents a declaration for a body of code.
   virtual bool hasBody() const { return getBody() != nullptr; }
 
   /// getBodyRBrace - Gets the right brace of the body, if a body exists.
   /// This works whether the body is a CompoundStmt or a CXXTryStmt.
   SourceLocation getBodyRBrace() const;
 
   // global temp stats (until we have a per-module visitor)
   static void add(Kind k);
   static void EnableStatistics();
   static void PrintStats();
 
   /// isTemplateParameter - Determines whether this declaration is a
   /// template parameter.
   bool isTemplateParameter() const;
 
   /// isTemplateParameter - Determines whether this declaration is a
   /// template parameter pack.
   bool isTemplateParameterPack() const;
 
   /// Whether this declaration is a parameter pack.
   bool isParameterPack() const;
 
   /// returns true if this declaration is a template
   bool isTemplateDecl() const;
 
   /// Whether this declaration is a function or function template.
   bool isFunctionOrFunctionTemplate() const {
     return (DeclKind >= Decl::firstFunction &&
             DeclKind <= Decl::lastFunction) ||
            DeclKind == FunctionTemplate;
   }
 
   /// If this is a declaration that describes some template, this
   /// method returns that template declaration.
   TemplateDecl *getDescribedTemplate() const;
 
   /// Returns the function itself, or the templated function if this is a
   /// function template.
   FunctionDecl *getAsFunction() LLVM_READONLY;
 
   const FunctionDecl *getAsFunction() const {
     return const_cast<Decl *>(this)->getAsFunction();
   }
 
   /// Changes the namespace of this declaration to reflect that it's
   /// a function-local extern declaration.
   ///
   /// These declarations appear in the lexical context of the extern
   /// declaration, but in the semantic context of the enclosing namespace
   /// scope.
   void setLocalExternDecl() {
     Decl *Prev = getPreviousDecl();
     IdentifierNamespace &= ~IDNS_Ordinary;
 
     // It's OK for the declaration to still have the "invisible friend" flag or
     // the "conflicts with tag declarations in this scope" flag for the outer
     // scope.
     assert((IdentifierNamespace & ~(IDNS_OrdinaryFriend | IDNS_Tag)) == 0 &&
            "namespace is not ordinary");
 
     IdentifierNamespace |= IDNS_LocalExtern;
     if (Prev && Prev->getIdentifierNamespace() & IDNS_Ordinary)
       IdentifierNamespace |= IDNS_Ordinary;
   }
 
   /// Determine whether this is a block-scope declaration with linkage.
   /// This will either be a local variable declaration declared 'extern', or a
   /// local function declaration.
   bool isLocalExternDecl() {
     return IdentifierNamespace & IDNS_LocalExtern;
   }
 
   /// Changes the namespace of this declaration to reflect that it's
   /// the object of a friend declaration.
   ///
   /// These declarations appear in the lexical context of the friending
   /// class, but in the semantic context of the actual entity.  This property
   /// applies only to a specific decl object;  other redeclarations of the
   /// same entity may not (and probably don't) share this property.
   void setObjectOfFriendDecl(bool PerformFriendInjection = false) {
     unsigned OldNS = IdentifierNamespace;
     assert((OldNS & (IDNS_Tag | IDNS_Ordinary |
                      IDNS_TagFriend | IDNS_OrdinaryFriend |
                      IDNS_LocalExtern | IDNS_NonMemberOperator)) &&
            "namespace includes neither ordinary nor tag");
     assert(!(OldNS & ~(IDNS_Tag | IDNS_Ordinary | IDNS_Type |
                        IDNS_TagFriend | IDNS_OrdinaryFriend |
                        IDNS_LocalExtern | IDNS_NonMemberOperator)) &&
            "namespace includes other than ordinary or tag");
 
     Decl *Prev = getPreviousDecl();
     IdentifierNamespace &= ~(IDNS_Ordinary | IDNS_Tag | IDNS_Type);
 
     if (OldNS & (IDNS_Tag | IDNS_TagFriend)) {
       IdentifierNamespace |= IDNS_TagFriend;
       if (PerformFriendInjection ||
           (Prev && Prev->getIdentifierNamespace() & IDNS_Tag))
         IdentifierNamespace |= IDNS_Tag | IDNS_Type;
     }
 
     if (OldNS & (IDNS_Ordinary | IDNS_OrdinaryFriend |
                  IDNS_LocalExtern | IDNS_NonMemberOperator)) {
       IdentifierNamespace |= IDNS_OrdinaryFriend;
       if (PerformFriendInjection ||
           (Prev && Prev->getIdentifierNamespace() & IDNS_Ordinary))
         IdentifierNamespace |= IDNS_Ordinary;
     }
   }
 
   enum FriendObjectKind {
     FOK_None,      ///< Not a friend object.
     FOK_Declared,  ///< A friend of a previously-declared entity.
     FOK_Undeclared ///< A friend of a previously-undeclared entity.
   };
 
   /// Determines whether this declaration is the object of a
   /// friend declaration and, if so, what kind.
   ///
   /// There is currently no direct way to find the associated FriendDecl.
   FriendObjectKind getFriendObjectKind() const {
     unsigned mask =
         (IdentifierNamespace & (IDNS_TagFriend | IDNS_OrdinaryFriend));
     if (!mask) return FOK_None;
     return (IdentifierNamespace & (IDNS_Tag | IDNS_Ordinary) ? FOK_Declared
                                                              : FOK_Undeclared);
   }
 
   /// Specifies that this declaration is a C++ overloaded non-member.
   void setNonMemberOperator() {
     assert(getKind() == Function || getKind() == FunctionTemplate);
     assert((IdentifierNamespace & IDNS_Ordinary) &&
            "visible non-member operators should be in ordinary namespace");
     IdentifierNamespace |= IDNS_NonMemberOperator;
   }
 
   static bool classofKind(Kind K) { return true; }
   static DeclContext *castToDeclContext(const Decl *);
   static Decl *castFromDeclContext(const DeclContext *);
 
   void print(raw_ostream &Out, unsigned Indentation = 0,
              bool PrintInstantiation = false) const;
   void print(raw_ostream &Out, const PrintingPolicy &Policy,
              unsigned Indentation = 0, bool PrintInstantiation = false) const;
   static void printGroup(Decl** Begin, unsigned NumDecls,
                          raw_ostream &Out, const PrintingPolicy &Policy,
                          unsigned Indentation = 0);
 
   // Debuggers don't usually respect default arguments.
   void dump() const;
 
   // Same as dump(), but forces color printing.
   void dumpColor() const;
 
   void dump(raw_ostream &Out, bool Deserialize = false) const;
 
   /// \return Unique reproducible object identifier
   int64_t getID() const;
 
   /// Looks through the Decl's underlying type to extract a FunctionType
   /// when possible. Will return null if the type underlying the Decl does not
   /// have a FunctionType.
   const FunctionType *getFunctionType(bool BlocksToo = true) const;
 
 private:
   void setAttrsImpl(const AttrVec& Attrs, ASTContext &Ctx);
   void setDeclContextsImpl(DeclContext *SemaDC, DeclContext *LexicalDC,
                            ASTContext &Ctx);
 
 protected:
   ASTMutationListener *getASTMutationListener() const;
 };
 
 /// Determine whether two declarations declare the same entity.
 inline bool declaresSameEntity(const Decl *D1, const Decl *D2) {
   if (!D1 || !D2)
     return false;
 
   if (D1 == D2)
     return true;
 
   return D1->getCanonicalDecl() == D2->getCanonicalDecl();
 }
 
 /// PrettyStackTraceDecl - If a crash occurs, indicate that it happened when
 /// doing something to a specific decl.
 class PrettyStackTraceDecl : public llvm::PrettyStackTraceEntry {
   const Decl *TheDecl;
   SourceLocation Loc;
   SourceManager &SM;
   const char *Message;
 
 public:
   PrettyStackTraceDecl(const Decl *theDecl, SourceLocation L,
                        SourceManager &sm, const char *Msg)
       : TheDecl(theDecl), Loc(L), SM(sm), Message(Msg) {}
 
   void print(raw_ostream &OS) const override;
 };
 
 /// The results of name lookup within a DeclContext. This is either a
 /// single result (with no stable storage) or a collection of results (with
 /// stable storage provided by the lookup table).
 class DeclContextLookupResult {
   using ResultTy = ArrayRef<NamedDecl *>;
 
   ResultTy Result;
 
   // If there is only one lookup result, it would be invalidated by
   // reallocations of the name table, so store it separately.
   NamedDecl *Single = nullptr;
 
   static NamedDecl *const SingleElementDummyList;
 
 public:
   DeclContextLookupResult() = default;
   DeclContextLookupResult(ArrayRef<NamedDecl *> Result)
       : Result(Result) {}
   DeclContextLookupResult(NamedDecl *Single)
       : Result(SingleElementDummyList), Single(Single) {}
 
   class iterator;
 
   using IteratorBase =
       llvm::iterator_adaptor_base<iterator, ResultTy::iterator,
                                   std::random_access_iterator_tag,
                                   NamedDecl *const>;
 
   class iterator : public IteratorBase {
     value_type SingleElement;
 
   public:
     explicit iterator(pointer Pos, value_type Single = nullptr)
         : IteratorBase(Pos), SingleElement(Single) {}
 
     reference operator*() const {
       return SingleElement ? SingleElement : IteratorBase::operator*();
     }
   };
 
   using const_iterator = iterator;
   using pointer = iterator::pointer;
   using reference = iterator::reference;
 
   iterator begin() const { return iterator(Result.begin(), Single); }
   iterator end() const { return iterator(Result.end(), Single); }
 
   bool empty() const { return Result.empty(); }
   pointer data() const { return Single ? &Single : Result.data(); }
   size_t size() const { return Single ? 1 : Result.size(); }
   reference front() const { return Single ? Single : Result.front(); }
   reference back() const { return Single ? Single : Result.back(); }
   reference operator[](size_t N) const { return Single ? Single : Result[N]; }
 
   // FIXME: Remove this from the interface
   DeclContextLookupResult slice(size_t N) const {
     DeclContextLookupResult Sliced = Result.slice(N);
     Sliced.Single = Single;
     return Sliced;
   }
 };
 
 /// DeclContext - This is used only as base class of specific decl types that
 /// can act as declaration contexts. These decls are (only the top classes
 /// that directly derive from DeclContext are mentioned, not their subclasses):
 ///
 ///   TranslationUnitDecl
 ///   ExternCContext
 ///   NamespaceDecl
 ///   TagDecl
 ///   OMPDeclareReductionDecl
 ///   FunctionDecl
 ///   ObjCMethodDecl
 ///   ObjCContainerDecl
 ///   LinkageSpecDecl
 ///   ExportDecl
 ///   BlockDecl
 ///   CapturedDecl
 class DeclContext {
   /// For makeDeclVisibleInContextImpl
   friend class ASTDeclReader;
   /// For reconcileExternalVisibleStorage, CreateStoredDeclsMap,
   /// hasNeedToReconcileExternalVisibleStorage
   friend class ExternalASTSource;
   /// For CreateStoredDeclsMap
   friend class DependentDiagnostic;
   /// For hasNeedToReconcileExternalVisibleStorage,
   /// hasLazyLocalLexicalLookups, hasLazyExternalLexicalLookups
   friend class ASTWriter;
 
   // We use uint64_t in the bit-fields below since some bit-fields
   // cross the unsigned boundary and this breaks the packing.
 
   /// Stores the bits used by DeclContext.
   /// If modified NumDeclContextBit, the ctor of DeclContext and the accessor
   /// methods in DeclContext should be updated appropriately.
   class DeclContextBitfields {
     friend class DeclContext;
     /// DeclKind - This indicates which class this is.
     uint64_t DeclKind : 7;
 
     /// Whether this declaration context also has some external
     /// storage that contains additional declarations that are lexically
     /// part of this context.
     mutable uint64_t ExternalLexicalStorage : 1;
 
     /// Whether this declaration context also has some external
     /// storage that contains additional declarations that are visible
     /// in this context.
     mutable uint64_t ExternalVisibleStorage : 1;
 
     /// Whether this declaration context has had externally visible
     /// storage added since the last lookup. In this case, \c LookupPtr's
     /// invariant may not hold and needs to be fixed before we perform
     /// another lookup.
     mutable uint64_t NeedToReconcileExternalVisibleStorage : 1;
 
     /// If \c true, this context may have local lexical declarations
     /// that are missing from the lookup table.
     mutable uint64_t HasLazyLocalLexicalLookups : 1;
 
     /// If \c true, the external source may have lexical declarations
     /// that are missing from the lookup table.
     mutable uint64_t HasLazyExternalLexicalLookups : 1;
 
     /// If \c true, lookups should only return identifier from
     /// DeclContext scope (for example TranslationUnit). Used in
     /// LookupQualifiedName()
     mutable uint64_t UseQualifiedLookup : 1;
   };
 
   /// Number of bits in DeclContextBitfields.
   enum { NumDeclContextBits = 13 };
 
   /// Stores the bits used by TagDecl.
   /// If modified NumTagDeclBits and the accessor
   /// methods in TagDecl should be updated appropriately.
   class TagDeclBitfields {
     friend class TagDecl;
     /// For the bits in DeclContextBitfields
     uint64_t : NumDeclContextBits;
 
     /// The TagKind enum.
     uint64_t TagDeclKind : 3;
 
     /// True if this is a definition ("struct foo {};"), false if it is a
     /// declaration ("struct foo;").  It is not considered a definition
     /// until the definition has been fully processed.
     uint64_t IsCompleteDefinition : 1;
 
     /// True if this is currently being defined.
     uint64_t IsBeingDefined : 1;
 
     /// True if this tag declaration is "embedded" (i.e., defined or declared
     /// for the very first time) in the syntax of a declarator.
     uint64_t IsEmbeddedInDeclarator : 1;
 
     /// True if this tag is free standing, e.g. "struct foo;".
     uint64_t IsFreeStanding : 1;
 
     /// Indicates whether it is possible for declarations of this kind
     /// to have an out-of-date definition.
     ///
     /// This option is only enabled when modules are enabled.
     uint64_t MayHaveOutOfDateDef : 1;
 
     /// Has the full definition of this type been required by a use somewhere in
     /// the TU.
     uint64_t IsCompleteDefinitionRequired : 1;
   };
 
   /// Number of non-inherited bits in TagDeclBitfields.
   enum { NumTagDeclBits = 9 };
 
   /// Stores the bits used by EnumDecl.
   /// If modified NumEnumDeclBit and the accessor
   /// methods in EnumDecl should be updated appropriately.
   class EnumDeclBitfields {
     friend class EnumDecl;
     /// For the bits in DeclContextBitfields.
     uint64_t : NumDeclContextBits;
     /// For the bits in TagDeclBitfields.
     uint64_t : NumTagDeclBits;
 
     /// Width in bits required to store all the non-negative
     /// enumerators of this enum.
     uint64_t NumPositiveBits : 8;
 
     /// Width in bits required to store all the negative
     /// enumerators of this enum.
     uint64_t NumNegativeBits : 8;
 
     /// True if this tag declaration is a scoped enumeration. Only
     /// possible in C++11 mode.
     uint64_t IsScoped : 1;
 
     /// If this tag declaration is a scoped enum,
     /// then this is true if the scoped enum was declared using the class
     /// tag, false if it was declared with the struct tag. No meaning is
     /// associated if this tag declaration is not a scoped enum.
     uint64_t IsScopedUsingClassTag : 1;
 
     /// True if this is an enumeration with fixed underlying type. Only
     /// possible in C++11, Microsoft extensions, or Objective C mode.
     uint64_t IsFixed : 1;
 
     /// True if a valid hash is stored in ODRHash.
     uint64_t HasODRHash : 1;
   };
 
   /// Number of non-inherited bits in EnumDeclBitfields.
   enum { NumEnumDeclBits = 20 };
 
   /// Stores the bits used by RecordDecl.
   /// If modified NumRecordDeclBits and the accessor
   /// methods in RecordDecl should be updated appropriately.
   class RecordDeclBitfields {
     friend class RecordDecl;
     /// For the bits in DeclContextBitfields.
     uint64_t : NumDeclContextBits;
     /// For the bits in TagDeclBitfields.
     uint64_t : NumTagDeclBits;
 
     /// This is true if this struct ends with a flexible
     /// array member (e.g. int X[]) or if this union contains a struct that does.
     /// If so, this cannot be contained in arrays or other structs as a member.
     uint64_t HasFlexibleArrayMember : 1;
 
     /// Whether this is the type of an anonymous struct or union.
     uint64_t AnonymousStructOrUnion : 1;
 
     /// This is true if this struct has at least one member
     /// containing an Objective-C object pointer type.
     uint64_t HasObjectMember : 1;
 
     /// This is true if struct has at least one member of
     /// 'volatile' type.
     uint64_t HasVolatileMember : 1;
 
     /// Whether the field declarations of this record have been loaded
     /// from external storage. To avoid unnecessary deserialization of
     /// methods/nested types we allow deserialization of just the fields
     /// when needed.
     mutable uint64_t LoadedFieldsFromExternalStorage : 1;
 
     /// Basic properties of non-trivial C structs.
     uint64_t NonTrivialToPrimitiveDefaultInitialize : 1;
     uint64_t NonTrivialToPrimitiveCopy : 1;
     uint64_t NonTrivialToPrimitiveDestroy : 1;
 
     /// Indicates whether this struct is destroyed in the callee.
     uint64_t ParamDestroyedInCallee : 1;
 
     /// Represents the way this type is passed to a function.
     uint64_t ArgPassingRestrictions : 2;
   };
 
   /// Number of non-inherited bits in RecordDeclBitfields.
   enum { NumRecordDeclBits = 11 };
 
   /// Stores the bits used by OMPDeclareReductionDecl.
   /// If modified NumOMPDeclareReductionDeclBits and the accessor
   /// methods in OMPDeclareReductionDecl should be updated appropriately.
   class OMPDeclareReductionDeclBitfields {
     friend class OMPDeclareReductionDecl;
     /// For the bits in DeclContextBitfields
     uint64_t : NumDeclContextBits;
 
     /// Kind of initializer,
     /// function call or omp_priv<init_expr> initializtion.
     uint64_t InitializerKind : 2;
   };
 
   /// Number of non-inherited bits in OMPDeclareReductionDeclBitfields.
   enum { NumOMPDeclareReductionDeclBits = 2 };
 
   /// Stores the bits used by FunctionDecl.
   /// If modified NumFunctionDeclBits and the accessor
   /// methods in FunctionDecl and CXXDeductionGuideDecl
   /// (for IsCopyDeductionCandidate) should be updated appropriately.
   class FunctionDeclBitfields {
     friend class FunctionDecl;
     /// For IsCopyDeductionCandidate
     friend class CXXDeductionGuideDecl;
     /// For the bits in DeclContextBitfields.
     uint64_t : NumDeclContextBits;
 
     uint64_t SClass : 3;
     uint64_t IsInline : 1;
     uint64_t IsInlineSpecified : 1;
 
     /// This is shared by CXXConstructorDecl,
     /// CXXConversionDecl, and CXXDeductionGuideDecl.
     uint64_t IsExplicitSpecified : 1;
 
     uint64_t IsVirtualAsWritten : 1;
     uint64_t IsPure : 1;
     uint64_t HasInheritedPrototype : 1;
     uint64_t HasWrittenPrototype : 1;
     uint64_t IsDeleted : 1;
     /// Used by CXXMethodDecl
     uint64_t IsTrivial : 1;
 
     /// This flag indicates whether this function is trivial for the purpose of
     /// calls. This is meaningful only when this function is a copy/move
     /// constructor or a destructor.
     uint64_t IsTrivialForCall : 1;
 
     /// Used by CXXMethodDecl
     uint64_t IsDefaulted : 1;
     /// Used by CXXMethodDecl
     uint64_t IsExplicitlyDefaulted : 1;
     uint64_t HasImplicitReturnZero : 1;
     uint64_t IsLateTemplateParsed : 1;
     uint64_t IsConstexpr : 1;
     uint64_t InstantiationIsPending : 1;
 
     /// Indicates if the function uses __try.
     uint64_t UsesSEHTry : 1;
 
     /// Indicates if the function was a definition
     /// but its body was skipped.
     uint64_t HasSkippedBody : 1;
 
     /// Indicates if the function declaration will
     /// have a body, once we're done parsing it.
     uint64_t WillHaveBody : 1;
 
     /// Indicates that this function is a multiversioned
     /// function using attribute 'target'.
     uint64_t IsMultiVersion : 1;
 
     /// [C++17] Only used by CXXDeductionGuideDecl. Indicates that
     /// the Deduction Guide is the implicitly generated 'copy
     /// deduction candidate' (is used during overload resolution).
     uint64_t IsCopyDeductionCandidate : 1;
 
     /// Store the ODRHash after first calculation.
     uint64_t HasODRHash : 1;
   };
 
   /// Number of non-inherited bits in FunctionDeclBitfields.
   enum { NumFunctionDeclBits = 25 };
 
   /// Stores the bits used by CXXConstructorDecl. If modified
   /// NumCXXConstructorDeclBits and the accessor
   /// methods in CXXConstructorDecl should be updated appropriately.
   class CXXConstructorDeclBitfields {
     friend class CXXConstructorDecl;
     /// For the bits in DeclContextBitfields.
     uint64_t : NumDeclContextBits;
     /// For the bits in FunctionDeclBitfields.
     uint64_t : NumFunctionDeclBits;
 
     /// 25 bits to fit in the remaining availible space.
     /// Note that this makes CXXConstructorDeclBitfields take
     /// exactly 64 bits and thus the width of NumCtorInitializers
     /// will need to be shrunk if some bit is added to NumDeclContextBitfields,
     /// NumFunctionDeclBitfields or CXXConstructorDeclBitfields.
     uint64_t NumCtorInitializers : 25;
     uint64_t IsInheritingConstructor : 1;
   };
 
   /// Number of non-inherited bits in CXXConstructorDeclBitfields.
   enum { NumCXXConstructorDeclBits = 26 };
 
   /// Stores the bits used by ObjCMethodDecl.
   /// If modified NumObjCMethodDeclBits and the accessor
   /// methods in ObjCMethodDecl should be updated appropriately.
   class ObjCMethodDeclBitfields {
     friend class ObjCMethodDecl;
 
     /// For the bits in DeclContextBitfields.
     uint64_t : NumDeclContextBits;
 
     /// The conventional meaning of this method; an ObjCMethodFamily.
     /// This is not serialized; instead, it is computed on demand and
     /// cached.
     mutable uint64_t Family : ObjCMethodFamilyBitWidth;
 
     /// instance (true) or class (false) method.
     uint64_t IsInstance : 1;
     uint64_t IsVariadic : 1;
 
     /// True if this method is the getter or setter for an explicit property.
     uint64_t IsPropertyAccessor : 1;
 
     /// Method has a definition.
     uint64_t IsDefined : 1;
 
     /// Method redeclaration in the same interface.
     uint64_t IsRedeclaration : 1;
 
     /// Is redeclared in the same interface.
     mutable uint64_t HasRedeclaration : 1;
 
     /// \@required/\@optional
     uint64_t DeclImplementation : 2;
 
     /// in, inout, etc.
     uint64_t objcDeclQualifier : 7;
 
     /// Indicates whether this method has a related result type.
     uint64_t RelatedResultType : 1;
 
     /// Whether the locations of the selector identifiers are in a
     /// "standard" position, a enum SelectorLocationsKind.
     uint64_t SelLocsKind : 2;
 
     /// Whether this method overrides any other in the class hierarchy.
     ///
     /// A method is said to override any method in the class's
     /// base classes, its protocols, or its categories' protocols, that has
     /// the same selector and is of the same kind (class or instance).
     /// A method in an implementation is not considered as overriding the same
     /// method in the interface or its categories.
     uint64_t IsOverriding : 1;
 
     /// Indicates if the method was a definition but its body was skipped.
     uint64_t HasSkippedBody : 1;
   };
 
   /// Number of non-inherited bits in ObjCMethodDeclBitfields.
   enum { NumObjCMethodDeclBits = 24 };
 
   /// Stores the bits used by ObjCContainerDecl.
   /// If modified NumObjCContainerDeclBits and the accessor
   /// methods in ObjCContainerDecl should be updated appropriately.
   class ObjCContainerDeclBitfields {
     friend class ObjCContainerDecl;
     /// For the bits in DeclContextBitfields
     uint32_t : NumDeclContextBits;
 
     // Not a bitfield but this saves space.
     // Note that ObjCContainerDeclBitfields is full.
     SourceLocation AtStart;
   };
 
   /// Number of non-inherited bits in ObjCContainerDeclBitfields.
   /// Note that here we rely on the fact that SourceLocation is 32 bits
   /// wide. We check this with the static_assert in the ctor of DeclContext.
   enum { NumObjCContainerDeclBits = 64 - NumDeclContextBits };
 
   /// Stores the bits used by LinkageSpecDecl.
   /// If modified NumLinkageSpecDeclBits and the accessor
   /// methods in LinkageSpecDecl should be updated appropriately.
   class LinkageSpecDeclBitfields {
     friend class LinkageSpecDecl;
     /// For the bits in DeclContextBitfields.
     uint64_t : NumDeclContextBits;
 
     /// The language for this linkage specification with values
     /// in the enum LinkageSpecDecl::LanguageIDs.
     uint64_t Language : 3;
 
     /// True if this linkage spec has braces.
     /// This is needed so that hasBraces() returns the correct result while the
     /// linkage spec body is being parsed.  Once RBraceLoc has been set this is
     /// not used, so it doesn't need to be serialized.
     uint64_t HasBraces : 1;
   };
 
   /// Number of non-inherited bits in LinkageSpecDeclBitfields.
   enum { NumLinkageSpecDeclBits = 4 };
 
   /// Stores the bits used by BlockDecl.
   /// If modified NumBlockDeclBits and the accessor
   /// methods in BlockDecl should be updated appropriately.
   class BlockDeclBitfields {
     friend class BlockDecl;
     /// For the bits in DeclContextBitfields.
     uint64_t : NumDeclContextBits;
 
     uint64_t IsVariadic : 1;
     uint64_t CapturesCXXThis : 1;
     uint64_t BlockMissingReturnType : 1;
     uint64_t IsConversionFromLambda : 1;
 
     /// A bit that indicates this block is passed directly to a function as a
     /// non-escaping parameter.
     uint64_t DoesNotEscape : 1;
   };
 
   /// Number of non-inherited bits in BlockDeclBitfields.
   enum { NumBlockDeclBits = 5 };
 
   /// Pointer to the data structure used to lookup declarations
   /// within this context (or a DependentStoredDeclsMap if this is a
   /// dependent context). We maintain the invariant that, if the map
   /// contains an entry for a DeclarationName (and we haven't lazily
   /// omitted anything), then it contains all relevant entries for that
   /// name (modulo the hasExternalDecls() flag).
   mutable StoredDeclsMap *LookupPtr = nullptr;
 
 protected:
   /// This anonymous union stores the bits belonging to DeclContext and classes
   /// deriving from it. The goal is to use otherwise wasted
   /// space in DeclContext to store data belonging to derived classes.
   /// The space saved is especially significient when pointers are aligned
   /// to 8 bytes. In this case due to alignment requirements we have a
   /// little less than 8 bytes free in DeclContext which we can use.
   /// We check that none of the classes in this union is larger than
   /// 8 bytes with static_asserts in the ctor of DeclContext.
   union {
     DeclContextBitfields DeclContextBits;
     TagDeclBitfields TagDeclBits;
     EnumDeclBitfields EnumDeclBits;
     RecordDeclBitfields RecordDeclBits;
     OMPDeclareReductionDeclBitfields OMPDeclareReductionDeclBits;
     FunctionDeclBitfields FunctionDeclBits;
     CXXConstructorDeclBitfields CXXConstructorDeclBits;
     ObjCMethodDeclBitfields ObjCMethodDeclBits;
     ObjCContainerDeclBitfields ObjCContainerDeclBits;
     LinkageSpecDeclBitfields LinkageSpecDeclBits;
     BlockDeclBitfields BlockDeclBits;
-
-    static_assert(sizeof(DeclContextBitfields) <= 8,
-                  "DeclContextBitfields is larger than 8 bytes!");
-    static_assert(sizeof(TagDeclBitfields) <= 8,
-                  "TagDeclBitfields is larger than 8 bytes!");
-    static_assert(sizeof(EnumDeclBitfields) <= 8,
-                  "EnumDeclBitfields is larger than 8 bytes!");
-    static_assert(sizeof(RecordDeclBitfields) <= 8,
-                  "RecordDeclBitfields is larger than 8 bytes!");
-    static_assert(sizeof(OMPDeclareReductionDeclBitfields) <= 8,
-                  "OMPDeclareReductionDeclBitfields is larger than 8 bytes!");
-    static_assert(sizeof(FunctionDeclBitfields) <= 8,
-                  "FunctionDeclBitfields is larger than 8 bytes!");
-    static_assert(sizeof(CXXConstructorDeclBitfields) <= 8,
-                  "CXXConstructorDeclBitfields is larger than 8 bytes!");
-    static_assert(sizeof(ObjCMethodDeclBitfields) <= 8,
-                  "ObjCMethodDeclBitfields is larger than 8 bytes!");
-    static_assert(sizeof(ObjCContainerDeclBitfields) <= 8,
-                  "ObjCContainerDeclBitfields is larger than 8 bytes!");
-    static_assert(sizeof(LinkageSpecDeclBitfields) <= 8,
-                  "LinkageSpecDeclBitfields is larger than 8 bytes!");
-    static_assert(sizeof(BlockDeclBitfields) <= 8,
-                  "BlockDeclBitfields is larger than 8 bytes!");
   };
+
+  static_assert(sizeof(DeclContextBitfields) <= 8,
+                "DeclContextBitfields is larger than 8 bytes!");
+  static_assert(sizeof(TagDeclBitfields) <= 8,
+                "TagDeclBitfields is larger than 8 bytes!");
+  static_assert(sizeof(EnumDeclBitfields) <= 8,
+                "EnumDeclBitfields is larger than 8 bytes!");
+  static_assert(sizeof(RecordDeclBitfields) <= 8,
+                "RecordDeclBitfields is larger than 8 bytes!");
+  static_assert(sizeof(OMPDeclareReductionDeclBitfields) <= 8,
+                "OMPDeclareReductionDeclBitfields is larger than 8 bytes!");
+  static_assert(sizeof(FunctionDeclBitfields) <= 8,
+                "FunctionDeclBitfields is larger than 8 bytes!");
+  static_assert(sizeof(CXXConstructorDeclBitfields) <= 8,
+                "CXXConstructorDeclBitfields is larger than 8 bytes!");
+  static_assert(sizeof(ObjCMethodDeclBitfields) <= 8,
+                "ObjCMethodDeclBitfields is larger than 8 bytes!");
+  static_assert(sizeof(ObjCContainerDeclBitfields) <= 8,
+                "ObjCContainerDeclBitfields is larger than 8 bytes!");
+  static_assert(sizeof(LinkageSpecDeclBitfields) <= 8,
+                "LinkageSpecDeclBitfields is larger than 8 bytes!");
+  static_assert(sizeof(BlockDeclBitfields) <= 8,
+                "BlockDeclBitfields is larger than 8 bytes!");
 
   /// FirstDecl - The first declaration stored within this declaration
   /// context.
   mutable Decl *FirstDecl = nullptr;
 
   /// LastDecl - The last declaration stored within this declaration
   /// context. FIXME: We could probably cache this value somewhere
   /// outside of the DeclContext, to reduce the size of DeclContext by
   /// another pointer.
   mutable Decl *LastDecl = nullptr;
 
   /// Build up a chain of declarations.
   ///
   /// \returns the first/last pair of declarations.
   static std::pair<Decl *, Decl *>
   BuildDeclChain(ArrayRef<Decl*> Decls, bool FieldsAlreadyLoaded);
 
   DeclContext(Decl::Kind K);
 
 public:
   ~DeclContext();
 
   Decl::Kind getDeclKind() const {
     return static_cast<Decl::Kind>(DeclContextBits.DeclKind);
   }
 
   const char *getDeclKindName() const;
 
   /// getParent - Returns the containing DeclContext.
   DeclContext *getParent() {
     return cast<Decl>(this)->getDeclContext();
   }
   const DeclContext *getParent() const {
     return const_cast<DeclContext*>(this)->getParent();
   }
 
   /// getLexicalParent - Returns the containing lexical DeclContext. May be
   /// different from getParent, e.g.:
   ///
   ///   namespace A {
   ///      struct S;
   ///   }
   ///   struct A::S {}; // getParent() == namespace 'A'
   ///                   // getLexicalParent() == translation unit
   ///
   DeclContext *getLexicalParent() {
     return cast<Decl>(this)->getLexicalDeclContext();
   }
   const DeclContext *getLexicalParent() const {
     return const_cast<DeclContext*>(this)->getLexicalParent();
   }
 
   DeclContext *getLookupParent();
 
   const DeclContext *getLookupParent() const {
     return const_cast<DeclContext*>(this)->getLookupParent();
   }
 
   ASTContext &getParentASTContext() const {
     return cast<Decl>(this)->getASTContext();
   }
 
   bool isClosure() const { return getDeclKind() == Decl::Block; }
 
   bool isObjCContainer() const {
     switch (getDeclKind()) {
     case Decl::ObjCCategory:
     case Decl::ObjCCategoryImpl:
     case Decl::ObjCImplementation:
     case Decl::ObjCInterface:
     case Decl::ObjCProtocol:
       return true;
     default:
       return false;
     }
   }
 
   bool isFunctionOrMethod() const {
     switch (getDeclKind()) {
     case Decl::Block:
     case Decl::Captured:
     case Decl::ObjCMethod:
       return true;
     default:
       return getDeclKind() >= Decl::firstFunction &&
              getDeclKind() <= Decl::lastFunction;
     }
   }
 
   /// Test whether the context supports looking up names.
   bool isLookupContext() const {
     return !isFunctionOrMethod() && getDeclKind() != Decl::LinkageSpec &&
            getDeclKind() != Decl::Export;
   }
 
   bool isFileContext() const {
     return getDeclKind() == Decl::TranslationUnit ||
            getDeclKind() == Decl::Namespace;
   }
 
   bool isTranslationUnit() const {
     return getDeclKind() == Decl::TranslationUnit;
   }
 
   bool isRecord() const {
     return getDeclKind() >= Decl::firstRecord &&
            getDeclKind() <= Decl::lastRecord;
   }
 
   bool isNamespace() const { return getDeclKind() == Decl::Namespace; }
 
   bool isStdNamespace() const;
 
   bool isInlineNamespace() const;
 
   /// Determines whether this context is dependent on a
   /// template parameter.
   bool isDependentContext() const;
 
   /// isTransparentContext - Determines whether this context is a
   /// "transparent" context, meaning that the members declared in this
   /// context are semantically declared in the nearest enclosing
   /// non-transparent (opaque) context but are lexically declared in
   /// this context. For example, consider the enumerators of an
   /// enumeration type:
   /// @code
   /// enum E {
   ///   Val1
   /// };
   /// @endcode
   /// Here, E is a transparent context, so its enumerator (Val1) will
   /// appear (semantically) that it is in the same context of E.
   /// Examples of transparent contexts include: enumerations (except for
   /// C++0x scoped enums), and C++ linkage specifications.
   bool isTransparentContext() const;
 
   /// Determines whether this context or some of its ancestors is a
   /// linkage specification context that specifies C linkage.
   bool isExternCContext() const;
 
   /// Retrieve the nearest enclosing C linkage specification context.
   const LinkageSpecDecl *getExternCContext() const;
 
   /// Determines whether this context or some of its ancestors is a
   /// linkage specification context that specifies C++ linkage.
   bool isExternCXXContext() const;
 
   /// Determine whether this declaration context is equivalent
   /// to the declaration context DC.
   bool Equals(const DeclContext *DC) const {
     return DC && this->getPrimaryContext() == DC->getPrimaryContext();
   }
 
   /// Determine whether this declaration context encloses the
   /// declaration context DC.
   bool Encloses(const DeclContext *DC) const;
 
   /// Find the nearest non-closure ancestor of this context,
   /// i.e. the innermost semantic parent of this context which is not
   /// a closure.  A context may be its own non-closure ancestor.
   Decl *getNonClosureAncestor();
   const Decl *getNonClosureAncestor() const {
     return const_cast<DeclContext*>(this)->getNonClosureAncestor();
   }
 
   /// getPrimaryContext - There may be many different
   /// declarations of the same entity (including forward declarations
   /// of classes, multiple definitions of namespaces, etc.), each with
   /// a different set of declarations. This routine returns the
   /// "primary" DeclContext structure, which will contain the
   /// information needed to perform name lookup into this context.
   DeclContext *getPrimaryContext();
   const DeclContext *getPrimaryContext() const {
     return const_cast<DeclContext*>(this)->getPrimaryContext();
   }
 
   /// getRedeclContext - Retrieve the context in which an entity conflicts with
   /// other entities of the same name, or where it is a redeclaration if the
   /// two entities are compatible. This skips through transparent contexts.
   DeclContext *getRedeclContext();
   const DeclContext *getRedeclContext() const {
     return const_cast<DeclContext *>(this)->getRedeclContext();
   }
 
   /// Retrieve the nearest enclosing namespace context.
   DeclContext *getEnclosingNamespaceContext();
   const DeclContext *getEnclosingNamespaceContext() const {
     return const_cast<DeclContext *>(this)->getEnclosingNamespaceContext();
   }
 
   /// Retrieve the outermost lexically enclosing record context.
   RecordDecl *getOuterLexicalRecordContext();
   const RecordDecl *getOuterLexicalRecordContext() const {
     return const_cast<DeclContext *>(this)->getOuterLexicalRecordContext();
   }
 
   /// Test if this context is part of the enclosing namespace set of
   /// the context NS, as defined in C++0x [namespace.def]p9. If either context
   /// isn't a namespace, this is equivalent to Equals().
   ///
   /// The enclosing namespace set of a namespace is the namespace and, if it is
   /// inline, its enclosing namespace, recursively.
   bool InEnclosingNamespaceSetOf(const DeclContext *NS) const;
 
   /// Collects all of the declaration contexts that are semantically
   /// connected to this declaration context.
   ///
   /// For declaration contexts that have multiple semantically connected but
   /// syntactically distinct contexts, such as C++ namespaces, this routine
   /// retrieves the complete set of such declaration contexts in source order.
   /// For example, given:
   ///
   /// \code
   /// namespace N {
   ///   int x;
   /// }
   /// namespace N {
   ///   int y;
   /// }
   /// \endcode
   ///
   /// The \c Contexts parameter will contain both definitions of N.
   ///
   /// \param Contexts Will be cleared and set to the set of declaration
   /// contexts that are semanticaly connected to this declaration context,
   /// in source order, including this context (which may be the only result,
   /// for non-namespace contexts).
   void collectAllContexts(SmallVectorImpl<DeclContext *> &Contexts);
 
   /// decl_iterator - Iterates through the declarations stored
   /// within this context.
   class decl_iterator {
     /// Current - The current declaration.
     Decl *Current = nullptr;
 
   public:
     using value_type = Decl *;
     using reference = const value_type &;
     using pointer = const value_type *;
     using iterator_category = std::forward_iterator_tag;
     using difference_type = std::ptrdiff_t;
 
     decl_iterator() = default;
     explicit decl_iterator(Decl *C) : Current(C) {}
 
     reference operator*() const { return Current; }
 
     // This doesn't meet the iterator requirements, but it's convenient
     value_type operator->() const { return Current; }
 
     decl_iterator& operator++() {
       Current = Current->getNextDeclInContext();
       return *this;
     }
 
     decl_iterator operator++(int) {
       decl_iterator tmp(*this);
       ++(*this);
       return tmp;
     }
 
     friend bool operator==(decl_iterator x, decl_iterator y) {
       return x.Current == y.Current;
     }
 
     friend bool operator!=(decl_iterator x, decl_iterator y) {
       return x.Current != y.Current;
     }
   };
 
   using decl_range = llvm::iterator_range<decl_iterator>;
 
   /// decls_begin/decls_end - Iterate over the declarations stored in
   /// this context.
   decl_range decls() const { return decl_range(decls_begin(), decls_end()); }
   decl_iterator decls_begin() const;
   decl_iterator decls_end() const { return decl_iterator(); }
   bool decls_empty() const;
 
   /// noload_decls_begin/end - Iterate over the declarations stored in this
   /// context that are currently loaded; don't attempt to retrieve anything
   /// from an external source.
   decl_range noload_decls() const {
     return decl_range(noload_decls_begin(), noload_decls_end());
   }
   decl_iterator noload_decls_begin() const { return decl_iterator(FirstDecl); }
   decl_iterator noload_decls_end() const { return decl_iterator(); }
 
   /// specific_decl_iterator - Iterates over a subrange of
   /// declarations stored in a DeclContext, providing only those that
   /// are of type SpecificDecl (or a class derived from it). This
   /// iterator is used, for example, to provide iteration over just
   /// the fields within a RecordDecl (with SpecificDecl = FieldDecl).
   template<typename SpecificDecl>
   class specific_decl_iterator {
     /// Current - The current, underlying declaration iterator, which
     /// will either be NULL or will point to a declaration of
     /// type SpecificDecl.
     DeclContext::decl_iterator Current;
 
     /// SkipToNextDecl - Advances the current position up to the next
     /// declaration of type SpecificDecl that also meets the criteria
     /// required by Acceptable.
     void SkipToNextDecl() {
       while (*Current && !isa<SpecificDecl>(*Current))
         ++Current;
     }
 
   public:
     using value_type = SpecificDecl *;
     // TODO: Add reference and pointer types (with some appropriate proxy type)
     // if we ever have a need for them.
     using reference = void;
     using pointer = void;
     using difference_type =
         std::iterator_traits<DeclContext::decl_iterator>::difference_type;
     using iterator_category = std::forward_iterator_tag;
 
     specific_decl_iterator() = default;
 
     /// specific_decl_iterator - Construct a new iterator over a
     /// subset of the declarations the range [C,
     /// end-of-declarations). If A is non-NULL, it is a pointer to a
     /// member function of SpecificDecl that should return true for
     /// all of the SpecificDecl instances that will be in the subset
     /// of iterators. For example, if you want Objective-C instance
     /// methods, SpecificDecl will be ObjCMethodDecl and A will be
     /// &ObjCMethodDecl::isInstanceMethod.
     explicit specific_decl_iterator(DeclContext::decl_iterator C) : Current(C) {
       SkipToNextDecl();
     }
 
     value_type operator*() const { return cast<SpecificDecl>(*Current); }
 
     // This doesn't meet the iterator requirements, but it's convenient
     value_type operator->() const { return **this; }
 
     specific_decl_iterator& operator++() {
       ++Current;
       SkipToNextDecl();
       return *this;
     }
 
     specific_decl_iterator operator++(int) {
       specific_decl_iterator tmp(*this);
       ++(*this);
       return tmp;
     }
 
     friend bool operator==(const specific_decl_iterator& x,
                            const specific_decl_iterator& y) {
       return x.Current == y.Current;
     }
 
     friend bool operator!=(const specific_decl_iterator& x,
                            const specific_decl_iterator& y) {
       return x.Current != y.Current;
     }
   };
 
   /// Iterates over a filtered subrange of declarations stored
   /// in a DeclContext.
   ///
   /// This iterator visits only those declarations that are of type
   /// SpecificDecl (or a class derived from it) and that meet some
   /// additional run-time criteria. This iterator is used, for
   /// example, to provide access to the instance methods within an
   /// Objective-C interface (with SpecificDecl = ObjCMethodDecl and
   /// Acceptable = ObjCMethodDecl::isInstanceMethod).
   template<typename SpecificDecl, bool (SpecificDecl::*Acceptable)() const>
   class filtered_decl_iterator {
     /// Current - The current, underlying declaration iterator, which
     /// will either be NULL or will point to a declaration of
     /// type SpecificDecl.
     DeclContext::decl_iterator Current;
 
     /// SkipToNextDecl - Advances the current position up to the next
     /// declaration of type SpecificDecl that also meets the criteria
     /// required by Acceptable.
     void SkipToNextDecl() {
       while (*Current &&
              (!isa<SpecificDecl>(*Current) ||
               (Acceptable && !(cast<SpecificDecl>(*Current)->*Acceptable)())))
         ++Current;
     }
 
   public:
     using value_type = SpecificDecl *;
     // TODO: Add reference and pointer types (with some appropriate proxy type)
     // if we ever have a need for them.
     using reference = void;
     using pointer = void;
     using difference_type =
         std::iterator_traits<DeclContext::decl_iterator>::difference_type;
     using iterator_category = std::forward_iterator_tag;
 
     filtered_decl_iterator() = default;
 
     /// filtered_decl_iterator - Construct a new iterator over a
     /// subset of the declarations the range [C,
     /// end-of-declarations). If A is non-NULL, it is a pointer to a
     /// member function of SpecificDecl that should return true for
     /// all of the SpecificDecl instances that will be in the subset
     /// of iterators. For example, if you want Objective-C instance
     /// methods, SpecificDecl will be ObjCMethodDecl and A will be
     /// &ObjCMethodDecl::isInstanceMethod.
     explicit filtered_decl_iterator(DeclContext::decl_iterator C) : Current(C) {
       SkipToNextDecl();
     }
 
     value_type operator*() const { return cast<SpecificDecl>(*Current); }
     value_type operator->() const { return cast<SpecificDecl>(*Current); }
 
     filtered_decl_iterator& operator++() {
       ++Current;
       SkipToNextDecl();
       return *this;
     }
 
     filtered_decl_iterator operator++(int) {
       filtered_decl_iterator tmp(*this);
       ++(*this);
       return tmp;
     }
 
     friend bool operator==(const filtered_decl_iterator& x,
                            const filtered_decl_iterator& y) {
       return x.Current == y.Current;
     }
 
     friend bool operator!=(const filtered_decl_iterator& x,
                            const filtered_decl_iterator& y) {
       return x.Current != y.Current;
     }
   };
 
   /// Add the declaration D into this context.
   ///
   /// This routine should be invoked when the declaration D has first
   /// been declared, to place D into the context where it was
   /// (lexically) defined. Every declaration must be added to one
   /// (and only one!) context, where it can be visited via
   /// [decls_begin(), decls_end()). Once a declaration has been added
   /// to its lexical context, the corresponding DeclContext owns the
   /// declaration.
   ///
   /// If D is also a NamedDecl, it will be made visible within its
   /// semantic context via makeDeclVisibleInContext.
   void addDecl(Decl *D);
 
   /// Add the declaration D into this context, but suppress
   /// searches for external declarations with the same name.
   ///
   /// Although analogous in function to addDecl, this removes an
   /// important check.  This is only useful if the Decl is being
   /// added in response to an external search; in all other cases,
   /// addDecl() is the right function to use.
   /// See the ASTImporter for use cases.
   void addDeclInternal(Decl *D);
 
   /// Add the declaration D to this context without modifying
   /// any lookup tables.
   ///
   /// This is useful for some operations in dependent contexts where
   /// the semantic context might not be dependent;  this basically
   /// only happens with friends.
   void addHiddenDecl(Decl *D);
 
   /// Removes a declaration from this context.
   void removeDecl(Decl *D);
 
   /// Checks whether a declaration is in this context.
   bool containsDecl(Decl *D) const;
 
   /// Checks whether a declaration is in this context.
   /// This also loads the Decls from the external source before the check.
   bool containsDeclAndLoad(Decl *D) const;
 
   using lookup_result = DeclContextLookupResult;
   using lookup_iterator = lookup_result::iterator;
 
   /// lookup - Find the declarations (if any) with the given Name in
   /// this context. Returns a range of iterators that contains all of
   /// the declarations with this name, with object, function, member,
   /// and enumerator names preceding any tag name. Note that this
   /// routine will not look into parent contexts.
   lookup_result lookup(DeclarationName Name) const;
 
   /// Find the declarations with the given name that are visible
   /// within this context; don't attempt to retrieve anything from an
   /// external source.
   lookup_result noload_lookup(DeclarationName Name);
 
   /// A simplistic name lookup mechanism that performs name lookup
   /// into this declaration context without consulting the external source.
   ///
   /// This function should almost never be used, because it subverts the
   /// usual relationship between a DeclContext and the external source.
   /// See the ASTImporter for the (few, but important) use cases.
   ///
   /// FIXME: This is very inefficient; replace uses of it with uses of
   /// noload_lookup.
   void localUncachedLookup(DeclarationName Name,
                            SmallVectorImpl<NamedDecl *> &Results);
 
   /// Makes a declaration visible within this context.
   ///
   /// This routine makes the declaration D visible to name lookup
   /// within this context and, if this is a transparent context,
   /// within its parent contexts up to the first enclosing
   /// non-transparent context. Making a declaration visible within a
   /// context does not transfer ownership of a declaration, and a
   /// declaration can be visible in many contexts that aren't its
   /// lexical context.
   ///
   /// If D is a redeclaration of an existing declaration that is
   /// visible from this context, as determined by
   /// NamedDecl::declarationReplaces, the previous declaration will be
   /// replaced with D.
   void makeDeclVisibleInContext(NamedDecl *D);
 
   /// all_lookups_iterator - An iterator that provides a view over the results
   /// of looking up every possible name.
   class all_lookups_iterator;
 
   using lookups_range = llvm::iterator_range<all_lookups_iterator>;
 
   lookups_range lookups() const;
   // Like lookups(), but avoids loading external declarations.
   // If PreserveInternalState, avoids building lookup data structures too.
   lookups_range noload_lookups(bool PreserveInternalState) const;
 
   /// Iterators over all possible lookups within this context.
   all_lookups_iterator lookups_begin() const;
   all_lookups_iterator lookups_end() const;
 
   /// Iterators over all possible lookups within this context that are
   /// currently loaded; don't attempt to retrieve anything from an external
   /// source.
   all_lookups_iterator noload_lookups_begin() const;
   all_lookups_iterator noload_lookups_end() const;
 
   struct udir_iterator;
 
   using udir_iterator_base =
       llvm::iterator_adaptor_base<udir_iterator, lookup_iterator,
                                   std::random_access_iterator_tag,
                                   UsingDirectiveDecl *>;
 
   struct udir_iterator : udir_iterator_base {
     udir_iterator(lookup_iterator I) : udir_iterator_base(I) {}
 
     UsingDirectiveDecl *operator*() const;
   };
 
   using udir_range = llvm::iterator_range<udir_iterator>;
 
   udir_range using_directives() const;
 
   // These are all defined in DependentDiagnostic.h.
   class ddiag_iterator;
 
   using ddiag_range = llvm::iterator_range<DeclContext::ddiag_iterator>;
 
   inline ddiag_range ddiags() const;
 
   // Low-level accessors
 
   /// Mark that there are external lexical declarations that we need
   /// to include in our lookup table (and that are not available as external
   /// visible lookups). These extra lookup results will be found by walking
   /// the lexical declarations of this context. This should be used only if
   /// setHasExternalLexicalStorage() has been called on any decl context for
   /// which this is the primary context.
   void setMustBuildLookupTable() {
     assert(this == getPrimaryContext() &&
            "should only be called on primary context");
     DeclContextBits.HasLazyExternalLexicalLookups = true;
   }
 
   /// Retrieve the internal representation of the lookup structure.
   /// This may omit some names if we are lazily building the structure.
   StoredDeclsMap *getLookupPtr() const { return LookupPtr; }
 
   /// Ensure the lookup structure is fully-built and return it.
   StoredDeclsMap *buildLookup();
 
   /// Whether this DeclContext has external storage containing
   /// additional declarations that are lexically in this context.
   bool hasExternalLexicalStorage() const {
     return DeclContextBits.ExternalLexicalStorage;
   }
 
   /// State whether this DeclContext has external storage for
   /// declarations lexically in this context.
   void setHasExternalLexicalStorage(bool ES = true) const {
     DeclContextBits.ExternalLexicalStorage = ES;
   }
 
   /// Whether this DeclContext has external storage containing
   /// additional declarations that are visible in this context.
   bool hasExternalVisibleStorage() const {
     return DeclContextBits.ExternalVisibleStorage;
   }
 
   /// State whether this DeclContext has external storage for
   /// declarations visible in this context.
   void setHasExternalVisibleStorage(bool ES = true) const {
     DeclContextBits.ExternalVisibleStorage = ES;
     if (ES && LookupPtr)
       DeclContextBits.NeedToReconcileExternalVisibleStorage = true;
   }
 
   /// Determine whether the given declaration is stored in the list of
   /// declarations lexically within this context.
   bool isDeclInLexicalTraversal(const Decl *D) const {
     return D && (D->NextInContextAndBits.getPointer() || D == FirstDecl ||
                  D == LastDecl);
   }
 
   bool setUseQualifiedLookup(bool use = true) const {
     bool old_value = DeclContextBits.UseQualifiedLookup;
     DeclContextBits.UseQualifiedLookup = use;
     return old_value;
   }
 
   bool shouldUseQualifiedLookup() const {
     return DeclContextBits.UseQualifiedLookup;
   }
 
   static bool classof(const Decl *D);
   static bool classof(const DeclContext *D) { return true; }
 
   void dumpDeclContext() const;
   void dumpLookups() const;
   void dumpLookups(llvm::raw_ostream &OS, bool DumpDecls = false,
                    bool Deserialize = false) const;
 
 private:
   /// Whether this declaration context has had externally visible
   /// storage added since the last lookup. In this case, \c LookupPtr's
   /// invariant may not hold and needs to be fixed before we perform
   /// another lookup.
   bool hasNeedToReconcileExternalVisibleStorage() const {
     return DeclContextBits.NeedToReconcileExternalVisibleStorage;
   }
 
   /// State that this declaration context has had externally visible
   /// storage added since the last lookup. In this case, \c LookupPtr's
   /// invariant may not hold and needs to be fixed before we perform
   /// another lookup.
   void setNeedToReconcileExternalVisibleStorage(bool Need = true) const {
     DeclContextBits.NeedToReconcileExternalVisibleStorage = Need;
   }
 
   /// If \c true, this context may have local lexical declarations
   /// that are missing from the lookup table.
   bool hasLazyLocalLexicalLookups() const {
     return DeclContextBits.HasLazyLocalLexicalLookups;
   }
 
   /// If \c true, this context may have local lexical declarations
   /// that are missing from the lookup table.
   void setHasLazyLocalLexicalLookups(bool HasLLLL = true) const {
     DeclContextBits.HasLazyLocalLexicalLookups = HasLLLL;
   }
 
   /// If \c true, the external source may have lexical declarations
   /// that are missing from the lookup table.
   bool hasLazyExternalLexicalLookups() const {
     return DeclContextBits.HasLazyExternalLexicalLookups;
   }
 
   /// If \c true, the external source may have lexical declarations
   /// that are missing from the lookup table.
   void setHasLazyExternalLexicalLookups(bool HasLELL = true) const {
     DeclContextBits.HasLazyExternalLexicalLookups = HasLELL;
   }
 
   void reconcileExternalVisibleStorage() const;
   bool LoadLexicalDeclsFromExternalStorage() const;
 
   /// Makes a declaration visible within this context, but
   /// suppresses searches for external declarations with the same
   /// name.
   ///
   /// Analogous to makeDeclVisibleInContext, but for the exclusive
   /// use of addDeclInternal().
   void makeDeclVisibleInContextInternal(NamedDecl *D);
 
   StoredDeclsMap *CreateStoredDeclsMap(ASTContext &C) const;
 
   void loadLazyLocalLexicalLookups();
   void buildLookupImpl(DeclContext *DCtx, bool Internal);
   void makeDeclVisibleInContextWithFlags(NamedDecl *D, bool Internal,
                                          bool Rediscoverable);
   void makeDeclVisibleInContextImpl(NamedDecl *D, bool Internal);
 };
 
 inline bool Decl::isTemplateParameter() const {
   return getKind() == TemplateTypeParm || getKind() == NonTypeTemplateParm ||
          getKind() == TemplateTemplateParm;
 }
 
 // Specialization selected when ToTy is not a known subclass of DeclContext.
 template <class ToTy,
           bool IsKnownSubtype = ::std::is_base_of<DeclContext, ToTy>::value>
 struct cast_convert_decl_context {
   static const ToTy *doit(const DeclContext *Val) {
     return static_cast<const ToTy*>(Decl::castFromDeclContext(Val));
   }
 
   static ToTy *doit(DeclContext *Val) {
     return static_cast<ToTy*>(Decl::castFromDeclContext(Val));
   }
 };
 
 // Specialization selected when ToTy is a known subclass of DeclContext.
 template <class ToTy>
 struct cast_convert_decl_context<ToTy, true> {
   static const ToTy *doit(const DeclContext *Val) {
     return static_cast<const ToTy*>(Val);
   }
 
   static ToTy *doit(DeclContext *Val) {
     return static_cast<ToTy*>(Val);
   }
 };
 
 } // namespace clang
 
 namespace llvm {
 
 /// isa<T>(DeclContext*)
 template <typename To>
 struct isa_impl<To, ::clang::DeclContext> {
   static bool doit(const ::clang::DeclContext &Val) {
     return To::classofKind(Val.getDeclKind());
   }
 };
 
 /// cast<T>(DeclContext*)
 template<class ToTy>
 struct cast_convert_val<ToTy,
                         const ::clang::DeclContext,const ::clang::DeclContext> {
   static const ToTy &doit(const ::clang::DeclContext &Val) {
     return *::clang::cast_convert_decl_context<ToTy>::doit(&Val);
   }
 };
 
 template<class ToTy>
 struct cast_convert_val<ToTy, ::clang::DeclContext, ::clang::DeclContext> {
   static ToTy &doit(::clang::DeclContext &Val) {
     return *::clang::cast_convert_decl_context<ToTy>::doit(&Val);
   }
 };
 
 template<class ToTy>
 struct cast_convert_val<ToTy,
                      const ::clang::DeclContext*, const ::clang::DeclContext*> {
   static const ToTy *doit(const ::clang::DeclContext *Val) {
     return ::clang::cast_convert_decl_context<ToTy>::doit(Val);
   }
 };
 
 template<class ToTy>
 struct cast_convert_val<ToTy, ::clang::DeclContext*, ::clang::DeclContext*> {
   static ToTy *doit(::clang::DeclContext *Val) {
     return ::clang::cast_convert_decl_context<ToTy>::doit(Val);
   }
 };
 
 /// Implement cast_convert_val for Decl -> DeclContext conversions.
 template<class FromTy>
 struct cast_convert_val< ::clang::DeclContext, FromTy, FromTy> {
   static ::clang::DeclContext &doit(const FromTy &Val) {
     return *FromTy::castToDeclContext(&Val);
   }
 };
 
 template<class FromTy>
 struct cast_convert_val< ::clang::DeclContext, FromTy*, FromTy*> {
   static ::clang::DeclContext *doit(const FromTy *Val) {
     return FromTy::castToDeclContext(Val);
   }
 };
 
 template<class FromTy>
 struct cast_convert_val< const ::clang::DeclContext, FromTy, FromTy> {
   static const ::clang::DeclContext &doit(const FromTy &Val) {
     return *FromTy::castToDeclContext(&Val);
   }
 };
 
 template<class FromTy>
 struct cast_convert_val< const ::clang::DeclContext, FromTy*, FromTy*> {
   static const ::clang::DeclContext *doit(const FromTy *Val) {
     return FromTy::castToDeclContext(Val);
   }
 };
 
 } // namespace llvm
 
 #endif // LLVM_CLANG_AST_DECLBASE_H
Index: head/contrib/llvm/tools/clang/include/clang/AST/Type.h
===================================================================
--- head/contrib/llvm/tools/clang/include/clang/AST/Type.h	(revision 349875)
+++ head/contrib/llvm/tools/clang/include/clang/AST/Type.h	(revision 349876)
@@ -1,6849 +1,6849 @@
 //===- Type.h - C Language Family Type Representation -----------*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 /// \file
 /// C Language Family Type Representation
 ///
 /// This file defines the clang::Type interface and subclasses, used to
 /// represent types for languages in the C family.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CLANG_AST_TYPE_H
 #define LLVM_CLANG_AST_TYPE_H
 
 #include "clang/AST/NestedNameSpecifier.h"
 #include "clang/AST/TemplateName.h"
 #include "clang/Basic/AddressSpaces.h"
 #include "clang/Basic/AttrKinds.h"
 #include "clang/Basic/Diagnostic.h"
 #include "clang/Basic/ExceptionSpecificationType.h"
 #include "clang/Basic/LLVM.h"
 #include "clang/Basic/Linkage.h"
 #include "clang/Basic/PartialDiagnostic.h"
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Basic/Specifiers.h"
 #include "clang/Basic/Visibility.h"
 #include "llvm/ADT/APInt.h"
 #include "llvm/ADT/APSInt.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/FoldingSet.h"
 #include "llvm/ADT/None.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/PointerIntPair.h"
 #include "llvm/ADT/PointerUnion.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/ADT/iterator_range.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/PointerLikeTypeTraits.h"
 #include "llvm/Support/type_traits.h"
 #include "llvm/Support/TrailingObjects.h"
 #include <cassert>
 #include <cstddef>
 #include <cstdint>
 #include <cstring>
 #include <string>
 #include <type_traits>
 #include <utility>
 
 namespace clang {
 
 class ExtQuals;
 class QualType;
 class TagDecl;
 class Type;
 
 enum {
   TypeAlignmentInBits = 4,
   TypeAlignment = 1 << TypeAlignmentInBits
 };
 
 } // namespace clang
 
 namespace llvm {
 
   template <typename T>
   struct PointerLikeTypeTraits;
   template<>
   struct PointerLikeTypeTraits< ::clang::Type*> {
     static inline void *getAsVoidPointer(::clang::Type *P) { return P; }
 
     static inline ::clang::Type *getFromVoidPointer(void *P) {
       return static_cast< ::clang::Type*>(P);
     }
 
     enum { NumLowBitsAvailable = clang::TypeAlignmentInBits };
   };
 
   template<>
   struct PointerLikeTypeTraits< ::clang::ExtQuals*> {
     static inline void *getAsVoidPointer(::clang::ExtQuals *P) { return P; }
 
     static inline ::clang::ExtQuals *getFromVoidPointer(void *P) {
       return static_cast< ::clang::ExtQuals*>(P);
     }
 
     enum { NumLowBitsAvailable = clang::TypeAlignmentInBits };
   };
 
   template <>
   struct isPodLike<clang::QualType> { static const bool value = true; };
 
 } // namespace llvm
 
 namespace clang {
 
 class ASTContext;
 template <typename> class CanQual;
 class CXXRecordDecl;
 class DeclContext;
 class EnumDecl;
 class Expr;
 class ExtQualsTypeCommonBase;
 class FunctionDecl;
 class IdentifierInfo;
 class NamedDecl;
 class ObjCInterfaceDecl;
 class ObjCProtocolDecl;
 class ObjCTypeParamDecl;
 struct PrintingPolicy;
 class RecordDecl;
 class Stmt;
 class TagDecl;
 class TemplateArgument;
 class TemplateArgumentListInfo;
 class TemplateArgumentLoc;
 class TemplateTypeParmDecl;
 class TypedefNameDecl;
 class UnresolvedUsingTypenameDecl;
 
 using CanQualType = CanQual<Type>;
 
 // Provide forward declarations for all of the *Type classes.
 #define TYPE(Class, Base) class Class##Type;
 #include "clang/AST/TypeNodes.def"
 
 /// The collection of all-type qualifiers we support.
 /// Clang supports five independent qualifiers:
 /// * C99: const, volatile, and restrict
 /// * MS: __unaligned
 /// * Embedded C (TR18037): address spaces
 /// * Objective C: the GC attributes (none, weak, or strong)
 class Qualifiers {
 public:
   enum TQ { // NOTE: These flags must be kept in sync with DeclSpec::TQ.
     Const    = 0x1,
     Restrict = 0x2,
     Volatile = 0x4,
     CVRMask = Const | Volatile | Restrict
   };
 
   enum GC {
     GCNone = 0,
     Weak,
     Strong
   };
 
   enum ObjCLifetime {
     /// There is no lifetime qualification on this type.
     OCL_None,
 
     /// This object can be modified without requiring retains or
     /// releases.
     OCL_ExplicitNone,
 
     /// Assigning into this object requires the old value to be
     /// released and the new value to be retained.  The timing of the
     /// release of the old value is inexact: it may be moved to
     /// immediately after the last known point where the value is
     /// live.
     OCL_Strong,
 
     /// Reading or writing from this object requires a barrier call.
     OCL_Weak,
 
     /// Assigning into this object requires a lifetime extension.
     OCL_Autoreleasing
   };
 
   enum {
     /// The maximum supported address space number.
     /// 23 bits should be enough for anyone.
     MaxAddressSpace = 0x7fffffu,
 
     /// The width of the "fast" qualifier mask.
     FastWidth = 3,
 
     /// The fast qualifier mask.
     FastMask = (1 << FastWidth) - 1
   };
 
   /// Returns the common set of qualifiers while removing them from
   /// the given sets.
   static Qualifiers removeCommonQualifiers(Qualifiers &L, Qualifiers &R) {
     // If both are only CVR-qualified, bit operations are sufficient.
     if (!(L.Mask & ~CVRMask) && !(R.Mask & ~CVRMask)) {
       Qualifiers Q;
       Q.Mask = L.Mask & R.Mask;
       L.Mask &= ~Q.Mask;
       R.Mask &= ~Q.Mask;
       return Q;
     }
 
     Qualifiers Q;
     unsigned CommonCRV = L.getCVRQualifiers() & R.getCVRQualifiers();
     Q.addCVRQualifiers(CommonCRV);
     L.removeCVRQualifiers(CommonCRV);
     R.removeCVRQualifiers(CommonCRV);
 
     if (L.getObjCGCAttr() == R.getObjCGCAttr()) {
       Q.setObjCGCAttr(L.getObjCGCAttr());
       L.removeObjCGCAttr();
       R.removeObjCGCAttr();
     }
 
     if (L.getObjCLifetime() == R.getObjCLifetime()) {
       Q.setObjCLifetime(L.getObjCLifetime());
       L.removeObjCLifetime();
       R.removeObjCLifetime();
     }
 
     if (L.getAddressSpace() == R.getAddressSpace()) {
       Q.setAddressSpace(L.getAddressSpace());
       L.removeAddressSpace();
       R.removeAddressSpace();
     }
     return Q;
   }
 
   static Qualifiers fromFastMask(unsigned Mask) {
     Qualifiers Qs;
     Qs.addFastQualifiers(Mask);
     return Qs;
   }
 
   static Qualifiers fromCVRMask(unsigned CVR) {
     Qualifiers Qs;
     Qs.addCVRQualifiers(CVR);
     return Qs;
   }
 
   static Qualifiers fromCVRUMask(unsigned CVRU) {
     Qualifiers Qs;
     Qs.addCVRUQualifiers(CVRU);
     return Qs;
   }
 
   // Deserialize qualifiers from an opaque representation.
   static Qualifiers fromOpaqueValue(unsigned opaque) {
     Qualifiers Qs;
     Qs.Mask = opaque;
     return Qs;
   }
 
   // Serialize these qualifiers into an opaque representation.
   unsigned getAsOpaqueValue() const {
     return Mask;
   }
 
   bool hasConst() const { return Mask & Const; }
   bool hasOnlyConst() const { return Mask == Const; }
   void removeConst() { Mask &= ~Const; }
   void addConst() { Mask |= Const; }
 
   bool hasVolatile() const { return Mask & Volatile; }
   bool hasOnlyVolatile() const { return Mask == Volatile; }
   void removeVolatile() { Mask &= ~Volatile; }
   void addVolatile() { Mask |= Volatile; }
 
   bool hasRestrict() const { return Mask & Restrict; }
   bool hasOnlyRestrict() const { return Mask == Restrict; }
   void removeRestrict() { Mask &= ~Restrict; }
   void addRestrict() { Mask |= Restrict; }
 
   bool hasCVRQualifiers() const { return getCVRQualifiers(); }
   unsigned getCVRQualifiers() const { return Mask & CVRMask; }
   unsigned getCVRUQualifiers() const { return Mask & (CVRMask | UMask); }
 
   void setCVRQualifiers(unsigned mask) {
     assert(!(mask & ~CVRMask) && "bitmask contains non-CVR bits");
     Mask = (Mask & ~CVRMask) | mask;
   }
   void removeCVRQualifiers(unsigned mask) {
     assert(!(mask & ~CVRMask) && "bitmask contains non-CVR bits");
     Mask &= ~mask;
   }
   void removeCVRQualifiers() {
     removeCVRQualifiers(CVRMask);
   }
   void addCVRQualifiers(unsigned mask) {
     assert(!(mask & ~CVRMask) && "bitmask contains non-CVR bits");
     Mask |= mask;
   }
   void addCVRUQualifiers(unsigned mask) {
     assert(!(mask & ~CVRMask & ~UMask) && "bitmask contains non-CVRU bits");
     Mask |= mask;
   }
 
   bool hasUnaligned() const { return Mask & UMask; }
   void setUnaligned(bool flag) {
     Mask = (Mask & ~UMask) | (flag ? UMask : 0);
   }
   void removeUnaligned() { Mask &= ~UMask; }
   void addUnaligned() { Mask |= UMask; }
 
   bool hasObjCGCAttr() const { return Mask & GCAttrMask; }
   GC getObjCGCAttr() const { return GC((Mask & GCAttrMask) >> GCAttrShift); }
   void setObjCGCAttr(GC type) {
     Mask = (Mask & ~GCAttrMask) | (type << GCAttrShift);
   }
   void removeObjCGCAttr() { setObjCGCAttr(GCNone); }
   void addObjCGCAttr(GC type) {
     assert(type);
     setObjCGCAttr(type);
   }
   Qualifiers withoutObjCGCAttr() const {
     Qualifiers qs = *this;
     qs.removeObjCGCAttr();
     return qs;
   }
   Qualifiers withoutObjCLifetime() const {
     Qualifiers qs = *this;
     qs.removeObjCLifetime();
     return qs;
   }
 
   bool hasObjCLifetime() const { return Mask & LifetimeMask; }
   ObjCLifetime getObjCLifetime() const {
     return ObjCLifetime((Mask & LifetimeMask) >> LifetimeShift);
   }
   void setObjCLifetime(ObjCLifetime type) {
     Mask = (Mask & ~LifetimeMask) | (type << LifetimeShift);
   }
   void removeObjCLifetime() { setObjCLifetime(OCL_None); }
   void addObjCLifetime(ObjCLifetime type) {
     assert(type);
     assert(!hasObjCLifetime());
     Mask |= (type << LifetimeShift);
   }
 
   /// True if the lifetime is neither None or ExplicitNone.
   bool hasNonTrivialObjCLifetime() const {
     ObjCLifetime lifetime = getObjCLifetime();
     return (lifetime > OCL_ExplicitNone);
   }
 
   /// True if the lifetime is either strong or weak.
   bool hasStrongOrWeakObjCLifetime() const {
     ObjCLifetime lifetime = getObjCLifetime();
     return (lifetime == OCL_Strong || lifetime == OCL_Weak);
   }
 
   bool hasAddressSpace() const { return Mask & AddressSpaceMask; }
   LangAS getAddressSpace() const {
     return static_cast<LangAS>(Mask >> AddressSpaceShift);
   }
   bool hasTargetSpecificAddressSpace() const {
     return isTargetAddressSpace(getAddressSpace());
   }
   /// Get the address space attribute value to be printed by diagnostics.
   unsigned getAddressSpaceAttributePrintValue() const {
     auto Addr = getAddressSpace();
     // This function is not supposed to be used with language specific
     // address spaces. If that happens, the diagnostic message should consider
     // printing the QualType instead of the address space value.
     assert(Addr == LangAS::Default || hasTargetSpecificAddressSpace());
     if (Addr != LangAS::Default)
       return toTargetAddressSpace(Addr);
     // TODO: The diagnostic messages where Addr may be 0 should be fixed
     // since it cannot differentiate the situation where 0 denotes the default
     // address space or user specified __attribute__((address_space(0))).
     return 0;
   }
   void setAddressSpace(LangAS space) {
     assert((unsigned)space <= MaxAddressSpace);
     Mask = (Mask & ~AddressSpaceMask)
          | (((uint32_t) space) << AddressSpaceShift);
   }
   void removeAddressSpace() { setAddressSpace(LangAS::Default); }
   void addAddressSpace(LangAS space) {
     assert(space != LangAS::Default);
     setAddressSpace(space);
   }
 
   // Fast qualifiers are those that can be allocated directly
   // on a QualType object.
   bool hasFastQualifiers() const { return getFastQualifiers(); }
   unsigned getFastQualifiers() const { return Mask & FastMask; }
   void setFastQualifiers(unsigned mask) {
     assert(!(mask & ~FastMask) && "bitmask contains non-fast qualifier bits");
     Mask = (Mask & ~FastMask) | mask;
   }
   void removeFastQualifiers(unsigned mask) {
     assert(!(mask & ~FastMask) && "bitmask contains non-fast qualifier bits");
     Mask &= ~mask;
   }
   void removeFastQualifiers() {
     removeFastQualifiers(FastMask);
   }
   void addFastQualifiers(unsigned mask) {
     assert(!(mask & ~FastMask) && "bitmask contains non-fast qualifier bits");
     Mask |= mask;
   }
 
   /// Return true if the set contains any qualifiers which require an ExtQuals
   /// node to be allocated.
   bool hasNonFastQualifiers() const { return Mask & ~FastMask; }
   Qualifiers getNonFastQualifiers() const {
     Qualifiers Quals = *this;
     Quals.setFastQualifiers(0);
     return Quals;
   }
 
   /// Return true if the set contains any qualifiers.
   bool hasQualifiers() const { return Mask; }
   bool empty() const { return !Mask; }
 
   /// Add the qualifiers from the given set to this set.
   void addQualifiers(Qualifiers Q) {
     // If the other set doesn't have any non-boolean qualifiers, just
     // bit-or it in.
     if (!(Q.Mask & ~CVRMask))
       Mask |= Q.Mask;
     else {
       Mask |= (Q.Mask & CVRMask);
       if (Q.hasAddressSpace())
         addAddressSpace(Q.getAddressSpace());
       if (Q.hasObjCGCAttr())
         addObjCGCAttr(Q.getObjCGCAttr());
       if (Q.hasObjCLifetime())
         addObjCLifetime(Q.getObjCLifetime());
     }
   }
 
   /// Remove the qualifiers from the given set from this set.
   void removeQualifiers(Qualifiers Q) {
     // If the other set doesn't have any non-boolean qualifiers, just
     // bit-and the inverse in.
     if (!(Q.Mask & ~CVRMask))
       Mask &= ~Q.Mask;
     else {
       Mask &= ~(Q.Mask & CVRMask);
       if (getObjCGCAttr() == Q.getObjCGCAttr())
         removeObjCGCAttr();
       if (getObjCLifetime() == Q.getObjCLifetime())
         removeObjCLifetime();
       if (getAddressSpace() == Q.getAddressSpace())
         removeAddressSpace();
     }
   }
 
   /// Add the qualifiers from the given set to this set, given that
   /// they don't conflict.
   void addConsistentQualifiers(Qualifiers qs) {
     assert(getAddressSpace() == qs.getAddressSpace() ||
            !hasAddressSpace() || !qs.hasAddressSpace());
     assert(getObjCGCAttr() == qs.getObjCGCAttr() ||
            !hasObjCGCAttr() || !qs.hasObjCGCAttr());
     assert(getObjCLifetime() == qs.getObjCLifetime() ||
            !hasObjCLifetime() || !qs.hasObjCLifetime());
     Mask |= qs.Mask;
   }
 
   /// Returns true if this address space is a superset of the other one.
   /// OpenCL v2.0 defines conversion rules (OpenCLC v2.0 s6.5.5) and notion of
   /// overlapping address spaces.
   /// CL1.1 or CL1.2:
   ///   every address space is a superset of itself.
   /// CL2.0 adds:
   ///   __generic is a superset of any address space except for __constant.
   bool isAddressSpaceSupersetOf(Qualifiers other) const {
     return
         // Address spaces must match exactly.
         getAddressSpace() == other.getAddressSpace() ||
         // Otherwise in OpenCLC v2.0 s6.5.5: every address space except
         // for __constant can be used as __generic.
         (getAddressSpace() == LangAS::opencl_generic &&
          other.getAddressSpace() != LangAS::opencl_constant);
   }
 
   /// Determines if these qualifiers compatibly include another set.
   /// Generally this answers the question of whether an object with the other
   /// qualifiers can be safely used as an object with these qualifiers.
   bool compatiblyIncludes(Qualifiers other) const {
     return isAddressSpaceSupersetOf(other) &&
            // ObjC GC qualifiers can match, be added, or be removed, but can't
            // be changed.
            (getObjCGCAttr() == other.getObjCGCAttr() || !hasObjCGCAttr() ||
             !other.hasObjCGCAttr()) &&
            // ObjC lifetime qualifiers must match exactly.
            getObjCLifetime() == other.getObjCLifetime() &&
            // CVR qualifiers may subset.
            (((Mask & CVRMask) | (other.Mask & CVRMask)) == (Mask & CVRMask)) &&
            // U qualifier may superset.
            (!other.hasUnaligned() || hasUnaligned());
   }
 
   /// Determines if these qualifiers compatibly include another set of
   /// qualifiers from the narrow perspective of Objective-C ARC lifetime.
   ///
   /// One set of Objective-C lifetime qualifiers compatibly includes the other
   /// if the lifetime qualifiers match, or if both are non-__weak and the
   /// including set also contains the 'const' qualifier, or both are non-__weak
   /// and one is None (which can only happen in non-ARC modes).
   bool compatiblyIncludesObjCLifetime(Qualifiers other) const {
     if (getObjCLifetime() == other.getObjCLifetime())
       return true;
 
     if (getObjCLifetime() == OCL_Weak || other.getObjCLifetime() == OCL_Weak)
       return false;
 
     if (getObjCLifetime() == OCL_None || other.getObjCLifetime() == OCL_None)
       return true;
 
     return hasConst();
   }
 
   /// Determine whether this set of qualifiers is a strict superset of
   /// another set of qualifiers, not considering qualifier compatibility.
   bool isStrictSupersetOf(Qualifiers Other) const;
 
   bool operator==(Qualifiers Other) const { return Mask == Other.Mask; }
   bool operator!=(Qualifiers Other) const { return Mask != Other.Mask; }
 
   explicit operator bool() const { return hasQualifiers(); }
 
   Qualifiers &operator+=(Qualifiers R) {
     addQualifiers(R);
     return *this;
   }
 
   // Union two qualifier sets.  If an enumerated qualifier appears
   // in both sets, use the one from the right.
   friend Qualifiers operator+(Qualifiers L, Qualifiers R) {
     L += R;
     return L;
   }
 
   Qualifiers &operator-=(Qualifiers R) {
     removeQualifiers(R);
     return *this;
   }
 
   /// Compute the difference between two qualifier sets.
   friend Qualifiers operator-(Qualifiers L, Qualifiers R) {
     L -= R;
     return L;
   }
 
   std::string getAsString() const;
   std::string getAsString(const PrintingPolicy &Policy) const;
 
   bool isEmptyWhenPrinted(const PrintingPolicy &Policy) const;
   void print(raw_ostream &OS, const PrintingPolicy &Policy,
              bool appendSpaceIfNonEmpty = false) const;
 
   void Profile(llvm::FoldingSetNodeID &ID) const {
     ID.AddInteger(Mask);
   }
 
 private:
   // bits:     |0 1 2|3|4 .. 5|6  ..  8|9   ...   31|
   //           |C R V|U|GCAttr|Lifetime|AddressSpace|
   uint32_t Mask = 0;
 
   static const uint32_t UMask = 0x8;
   static const uint32_t UShift = 3;
   static const uint32_t GCAttrMask = 0x30;
   static const uint32_t GCAttrShift = 4;
   static const uint32_t LifetimeMask = 0x1C0;
   static const uint32_t LifetimeShift = 6;
   static const uint32_t AddressSpaceMask =
       ~(CVRMask | UMask | GCAttrMask | LifetimeMask);
   static const uint32_t AddressSpaceShift = 9;
 };
 
 /// A std::pair-like structure for storing a qualified type split
 /// into its local qualifiers and its locally-unqualified type.
 struct SplitQualType {
   /// The locally-unqualified type.
   const Type *Ty = nullptr;
 
   /// The local qualifiers.
   Qualifiers Quals;
 
   SplitQualType() = default;
   SplitQualType(const Type *ty, Qualifiers qs) : Ty(ty), Quals(qs) {}
 
   SplitQualType getSingleStepDesugaredType() const; // end of this file
 
   // Make std::tie work.
   std::pair<const Type *,Qualifiers> asPair() const {
     return std::pair<const Type *, Qualifiers>(Ty, Quals);
   }
 
   friend bool operator==(SplitQualType a, SplitQualType b) {
     return a.Ty == b.Ty && a.Quals == b.Quals;
   }
   friend bool operator!=(SplitQualType a, SplitQualType b) {
     return a.Ty != b.Ty || a.Quals != b.Quals;
   }
 };
 
 /// The kind of type we are substituting Objective-C type arguments into.
 ///
 /// The kind of substitution affects the replacement of type parameters when
 /// no concrete type information is provided, e.g., when dealing with an
 /// unspecialized type.
 enum class ObjCSubstitutionContext {
   /// An ordinary type.
   Ordinary,
 
   /// The result type of a method or function.
   Result,
 
   /// The parameter type of a method or function.
   Parameter,
 
   /// The type of a property.
   Property,
 
   /// The superclass of a type.
   Superclass,
 };
 
 /// A (possibly-)qualified type.
 ///
 /// For efficiency, we don't store CV-qualified types as nodes on their
 /// own: instead each reference to a type stores the qualifiers.  This
 /// greatly reduces the number of nodes we need to allocate for types (for
 /// example we only need one for 'int', 'const int', 'volatile int',
 /// 'const volatile int', etc).
 ///
 /// As an added efficiency bonus, instead of making this a pair, we
 /// just store the two bits we care about in the low bits of the
 /// pointer.  To handle the packing/unpacking, we make QualType be a
 /// simple wrapper class that acts like a smart pointer.  A third bit
 /// indicates whether there are extended qualifiers present, in which
 /// case the pointer points to a special structure.
 class QualType {
   friend class QualifierCollector;
 
   // Thankfully, these are efficiently composable.
   llvm::PointerIntPair<llvm::PointerUnion<const Type *, const ExtQuals *>,
                        Qualifiers::FastWidth> Value;
 
   const ExtQuals *getExtQualsUnsafe() const {
     return Value.getPointer().get<const ExtQuals*>();
   }
 
   const Type *getTypePtrUnsafe() const {
     return Value.getPointer().get<const Type*>();
   }
 
   const ExtQualsTypeCommonBase *getCommonPtr() const {
     assert(!isNull() && "Cannot retrieve a NULL type pointer");
     auto CommonPtrVal = reinterpret_cast<uintptr_t>(Value.getOpaqueValue());
     CommonPtrVal &= ~(uintptr_t)((1 << TypeAlignmentInBits) - 1);
     return reinterpret_cast<ExtQualsTypeCommonBase*>(CommonPtrVal);
   }
 
 public:
   QualType() = default;
   QualType(const Type *Ptr, unsigned Quals) : Value(Ptr, Quals) {}
   QualType(const ExtQuals *Ptr, unsigned Quals) : Value(Ptr, Quals) {}
 
   unsigned getLocalFastQualifiers() const { return Value.getInt(); }
   void setLocalFastQualifiers(unsigned Quals) { Value.setInt(Quals); }
 
   /// Retrieves a pointer to the underlying (unqualified) type.
   ///
   /// This function requires that the type not be NULL. If the type might be
   /// NULL, use the (slightly less efficient) \c getTypePtrOrNull().
   const Type *getTypePtr() const;
 
   const Type *getTypePtrOrNull() const;
 
   /// Retrieves a pointer to the name of the base type.
   const IdentifierInfo *getBaseTypeIdentifier() const;
 
   /// Divides a QualType into its unqualified type and a set of local
   /// qualifiers.
   SplitQualType split() const;
 
   void *getAsOpaquePtr() const { return Value.getOpaqueValue(); }
 
   static QualType getFromOpaquePtr(const void *Ptr) {
     QualType T;
     T.Value.setFromOpaqueValue(const_cast<void*>(Ptr));
     return T;
   }
 
   const Type &operator*() const {
     return *getTypePtr();
   }
 
   const Type *operator->() const {
     return getTypePtr();
   }
 
   bool isCanonical() const;
   bool isCanonicalAsParam() const;
 
   /// Return true if this QualType doesn't point to a type yet.
   bool isNull() const {
     return Value.getPointer().isNull();
   }
 
   /// Determine whether this particular QualType instance has the
   /// "const" qualifier set, without looking through typedefs that may have
   /// added "const" at a different level.
   bool isLocalConstQualified() const {
     return (getLocalFastQualifiers() & Qualifiers::Const);
   }
 
   /// Determine whether this type is const-qualified.
   bool isConstQualified() const;
 
   /// Determine whether this particular QualType instance has the
   /// "restrict" qualifier set, without looking through typedefs that may have
   /// added "restrict" at a different level.
   bool isLocalRestrictQualified() const {
     return (getLocalFastQualifiers() & Qualifiers::Restrict);
   }
 
   /// Determine whether this type is restrict-qualified.
   bool isRestrictQualified() const;
 
   /// Determine whether this particular QualType instance has the
   /// "volatile" qualifier set, without looking through typedefs that may have
   /// added "volatile" at a different level.
   bool isLocalVolatileQualified() const {
     return (getLocalFastQualifiers() & Qualifiers::Volatile);
   }
 
   /// Determine whether this type is volatile-qualified.
   bool isVolatileQualified() const;
 
   /// Determine whether this particular QualType instance has any
   /// qualifiers, without looking through any typedefs that might add
   /// qualifiers at a different level.
   bool hasLocalQualifiers() const {
     return getLocalFastQualifiers() || hasLocalNonFastQualifiers();
   }
 
   /// Determine whether this type has any qualifiers.
   bool hasQualifiers() const;
 
   /// Determine whether this particular QualType instance has any
   /// "non-fast" qualifiers, e.g., those that are stored in an ExtQualType
   /// instance.
   bool hasLocalNonFastQualifiers() const {
     return Value.getPointer().is<const ExtQuals*>();
   }
 
   /// Retrieve the set of qualifiers local to this particular QualType
   /// instance, not including any qualifiers acquired through typedefs or
   /// other sugar.
   Qualifiers getLocalQualifiers() const;
 
   /// Retrieve the set of qualifiers applied to this type.
   Qualifiers getQualifiers() const;
 
   /// Retrieve the set of CVR (const-volatile-restrict) qualifiers
   /// local to this particular QualType instance, not including any qualifiers
   /// acquired through typedefs or other sugar.
   unsigned getLocalCVRQualifiers() const {
     return getLocalFastQualifiers();
   }
 
   /// Retrieve the set of CVR (const-volatile-restrict) qualifiers
   /// applied to this type.
   unsigned getCVRQualifiers() const;
 
   bool isConstant(const ASTContext& Ctx) const {
     return QualType::isConstant(*this, Ctx);
   }
 
   /// Determine whether this is a Plain Old Data (POD) type (C++ 3.9p10).
   bool isPODType(const ASTContext &Context) const;
 
   /// Return true if this is a POD type according to the rules of the C++98
   /// standard, regardless of the current compilation's language.
   bool isCXX98PODType(const ASTContext &Context) const;
 
   /// Return true if this is a POD type according to the more relaxed rules
   /// of the C++11 standard, regardless of the current compilation's language.
   /// (C++0x [basic.types]p9). Note that, unlike
   /// CXXRecordDecl::isCXX11StandardLayout, this takes DRs into account.
   bool isCXX11PODType(const ASTContext &Context) const;
 
   /// Return true if this is a trivial type per (C++0x [basic.types]p9)
   bool isTrivialType(const ASTContext &Context) const;
 
   /// Return true if this is a trivially copyable type (C++0x [basic.types]p9)
   bool isTriviallyCopyableType(const ASTContext &Context) const;
 
 
   /// Returns true if it is a class and it might be dynamic.
   bool mayBeDynamicClass() const;
 
   /// Returns true if it is not a class or if the class might not be dynamic.
   bool mayBeNotDynamicClass() const;
 
   // Don't promise in the API that anything besides 'const' can be
   // easily added.
 
   /// Add the `const` type qualifier to this QualType.
   void addConst() {
     addFastQualifiers(Qualifiers::Const);
   }
   QualType withConst() const {
     return withFastQualifiers(Qualifiers::Const);
   }
 
   /// Add the `volatile` type qualifier to this QualType.
   void addVolatile() {
     addFastQualifiers(Qualifiers::Volatile);
   }
   QualType withVolatile() const {
     return withFastQualifiers(Qualifiers::Volatile);
   }
 
   /// Add the `restrict` qualifier to this QualType.
   void addRestrict() {
     addFastQualifiers(Qualifiers::Restrict);
   }
   QualType withRestrict() const {
     return withFastQualifiers(Qualifiers::Restrict);
   }
 
   QualType withCVRQualifiers(unsigned CVR) const {
     return withFastQualifiers(CVR);
   }
 
   void addFastQualifiers(unsigned TQs) {
     assert(!(TQs & ~Qualifiers::FastMask)
            && "non-fast qualifier bits set in mask!");
     Value.setInt(Value.getInt() | TQs);
   }
 
   void removeLocalConst();
   void removeLocalVolatile();
   void removeLocalRestrict();
   void removeLocalCVRQualifiers(unsigned Mask);
 
   void removeLocalFastQualifiers() { Value.setInt(0); }
   void removeLocalFastQualifiers(unsigned Mask) {
     assert(!(Mask & ~Qualifiers::FastMask) && "mask has non-fast qualifiers");
     Value.setInt(Value.getInt() & ~Mask);
   }
 
   // Creates a type with the given qualifiers in addition to any
   // qualifiers already on this type.
   QualType withFastQualifiers(unsigned TQs) const {
     QualType T = *this;
     T.addFastQualifiers(TQs);
     return T;
   }
 
   // Creates a type with exactly the given fast qualifiers, removing
   // any existing fast qualifiers.
   QualType withExactLocalFastQualifiers(unsigned TQs) const {
     return withoutLocalFastQualifiers().withFastQualifiers(TQs);
   }
 
   // Removes fast qualifiers, but leaves any extended qualifiers in place.
   QualType withoutLocalFastQualifiers() const {
     QualType T = *this;
     T.removeLocalFastQualifiers();
     return T;
   }
 
   QualType getCanonicalType() const;
 
   /// Return this type with all of the instance-specific qualifiers
   /// removed, but without removing any qualifiers that may have been applied
   /// through typedefs.
   QualType getLocalUnqualifiedType() const { return QualType(getTypePtr(), 0); }
 
   /// Retrieve the unqualified variant of the given type,
   /// removing as little sugar as possible.
   ///
   /// This routine looks through various kinds of sugar to find the
   /// least-desugared type that is unqualified. For example, given:
   ///
   /// \code
   /// typedef int Integer;
   /// typedef const Integer CInteger;
   /// typedef CInteger DifferenceType;
   /// \endcode
   ///
   /// Executing \c getUnqualifiedType() on the type \c DifferenceType will
   /// desugar until we hit the type \c Integer, which has no qualifiers on it.
   ///
   /// The resulting type might still be qualified if it's sugar for an array
   /// type.  To strip qualifiers even from within a sugared array type, use
   /// ASTContext::getUnqualifiedArrayType.
   inline QualType getUnqualifiedType() const;
 
   /// Retrieve the unqualified variant of the given type, removing as little
   /// sugar as possible.
   ///
   /// Like getUnqualifiedType(), but also returns the set of
   /// qualifiers that were built up.
   ///
   /// The resulting type might still be qualified if it's sugar for an array
   /// type.  To strip qualifiers even from within a sugared array type, use
   /// ASTContext::getUnqualifiedArrayType.
   inline SplitQualType getSplitUnqualifiedType() const;
 
   /// Determine whether this type is more qualified than the other
   /// given type, requiring exact equality for non-CVR qualifiers.
   bool isMoreQualifiedThan(QualType Other) const;
 
   /// Determine whether this type is at least as qualified as the other
   /// given type, requiring exact equality for non-CVR qualifiers.
   bool isAtLeastAsQualifiedAs(QualType Other) const;
 
   QualType getNonReferenceType() const;
 
   /// Determine the type of a (typically non-lvalue) expression with the
   /// specified result type.
   ///
   /// This routine should be used for expressions for which the return type is
   /// explicitly specified (e.g., in a cast or call) and isn't necessarily
   /// an lvalue. It removes a top-level reference (since there are no
   /// expressions of reference type) and deletes top-level cvr-qualifiers
   /// from non-class types (in C++) or all types (in C).
   QualType getNonLValueExprType(const ASTContext &Context) const;
 
   /// Return the specified type with any "sugar" removed from
   /// the type.  This takes off typedefs, typeof's etc.  If the outer level of
   /// the type is already concrete, it returns it unmodified.  This is similar
   /// to getting the canonical type, but it doesn't remove *all* typedefs.  For
   /// example, it returns "T*" as "T*", (not as "int*"), because the pointer is
   /// concrete.
   ///
   /// Qualifiers are left in place.
   QualType getDesugaredType(const ASTContext &Context) const {
     return getDesugaredType(*this, Context);
   }
 
   SplitQualType getSplitDesugaredType() const {
     return getSplitDesugaredType(*this);
   }
 
   /// Return the specified type with one level of "sugar" removed from
   /// the type.
   ///
   /// This routine takes off the first typedef, typeof, etc. If the outer level
   /// of the type is already concrete, it returns it unmodified.
   QualType getSingleStepDesugaredType(const ASTContext &Context) const {
     return getSingleStepDesugaredTypeImpl(*this, Context);
   }
 
   /// Returns the specified type after dropping any
   /// outer-level parentheses.
   QualType IgnoreParens() const {
     if (isa<ParenType>(*this))
       return QualType::IgnoreParens(*this);
     return *this;
   }
 
   /// Indicate whether the specified types and qualifiers are identical.
   friend bool operator==(const QualType &LHS, const QualType &RHS) {
     return LHS.Value == RHS.Value;
   }
   friend bool operator!=(const QualType &LHS, const QualType &RHS) {
     return LHS.Value != RHS.Value;
   }
 
   static std::string getAsString(SplitQualType split,
                                  const PrintingPolicy &Policy) {
     return getAsString(split.Ty, split.Quals, Policy);
   }
   static std::string getAsString(const Type *ty, Qualifiers qs,
                                  const PrintingPolicy &Policy);
 
   std::string getAsString() const;
   std::string getAsString(const PrintingPolicy &Policy) const;
 
   void print(raw_ostream &OS, const PrintingPolicy &Policy,
              const Twine &PlaceHolder = Twine(),
              unsigned Indentation = 0) const;
 
   static void print(SplitQualType split, raw_ostream &OS,
                     const PrintingPolicy &policy, const Twine &PlaceHolder,
                     unsigned Indentation = 0) {
     return print(split.Ty, split.Quals, OS, policy, PlaceHolder, Indentation);
   }
 
   static void print(const Type *ty, Qualifiers qs,
                     raw_ostream &OS, const PrintingPolicy &policy,
                     const Twine &PlaceHolder,
                     unsigned Indentation = 0);
 
   void getAsStringInternal(std::string &Str,
                            const PrintingPolicy &Policy) const;
 
   static void getAsStringInternal(SplitQualType split, std::string &out,
                                   const PrintingPolicy &policy) {
     return getAsStringInternal(split.Ty, split.Quals, out, policy);
   }
 
   static void getAsStringInternal(const Type *ty, Qualifiers qs,
                                   std::string &out,
                                   const PrintingPolicy &policy);
 
   class StreamedQualTypeHelper {
     const QualType &T;
     const PrintingPolicy &Policy;
     const Twine &PlaceHolder;
     unsigned Indentation;
 
   public:
     StreamedQualTypeHelper(const QualType &T, const PrintingPolicy &Policy,
                            const Twine &PlaceHolder, unsigned Indentation)
         : T(T), Policy(Policy), PlaceHolder(PlaceHolder),
           Indentation(Indentation) {}
 
     friend raw_ostream &operator<<(raw_ostream &OS,
                                    const StreamedQualTypeHelper &SQT) {
       SQT.T.print(OS, SQT.Policy, SQT.PlaceHolder, SQT.Indentation);
       return OS;
     }
   };
 
   StreamedQualTypeHelper stream(const PrintingPolicy &Policy,
                                 const Twine &PlaceHolder = Twine(),
                                 unsigned Indentation = 0) const {
     return StreamedQualTypeHelper(*this, Policy, PlaceHolder, Indentation);
   }
 
   void dump(const char *s) const;
   void dump() const;
   void dump(llvm::raw_ostream &OS) const;
 
   void Profile(llvm::FoldingSetNodeID &ID) const {
     ID.AddPointer(getAsOpaquePtr());
   }
 
   /// Return the address space of this type.
   inline LangAS getAddressSpace() const;
 
   /// Returns gc attribute of this type.
   inline Qualifiers::GC getObjCGCAttr() const;
 
   /// true when Type is objc's weak.
   bool isObjCGCWeak() const {
     return getObjCGCAttr() == Qualifiers::Weak;
   }
 
   /// true when Type is objc's strong.
   bool isObjCGCStrong() const {
     return getObjCGCAttr() == Qualifiers::Strong;
   }
 
   /// Returns lifetime attribute of this type.
   Qualifiers::ObjCLifetime getObjCLifetime() const {
     return getQualifiers().getObjCLifetime();
   }
 
   bool hasNonTrivialObjCLifetime() const {
     return getQualifiers().hasNonTrivialObjCLifetime();
   }
 
   bool hasStrongOrWeakObjCLifetime() const {
     return getQualifiers().hasStrongOrWeakObjCLifetime();
   }
 
   // true when Type is objc's weak and weak is enabled but ARC isn't.
   bool isNonWeakInMRRWithObjCWeak(const ASTContext &Context) const;
 
   enum PrimitiveDefaultInitializeKind {
     /// The type does not fall into any of the following categories. Note that
     /// this case is zero-valued so that values of this enum can be used as a
     /// boolean condition for non-triviality.
     PDIK_Trivial,
 
     /// The type is an Objective-C retainable pointer type that is qualified
     /// with the ARC __strong qualifier.
     PDIK_ARCStrong,
 
     /// The type is an Objective-C retainable pointer type that is qualified
     /// with the ARC __weak qualifier.
     PDIK_ARCWeak,
 
     /// The type is a struct containing a field whose type is not PCK_Trivial.
     PDIK_Struct
   };
 
   /// Functions to query basic properties of non-trivial C struct types.
 
   /// Check if this is a non-trivial type that would cause a C struct
   /// transitively containing this type to be non-trivial to default initialize
   /// and return the kind.
   PrimitiveDefaultInitializeKind
   isNonTrivialToPrimitiveDefaultInitialize() const;
 
   enum PrimitiveCopyKind {
     /// The type does not fall into any of the following categories. Note that
     /// this case is zero-valued so that values of this enum can be used as a
     /// boolean condition for non-triviality.
     PCK_Trivial,
 
     /// The type would be trivial except that it is volatile-qualified. Types
     /// that fall into one of the other non-trivial cases may additionally be
     /// volatile-qualified.
     PCK_VolatileTrivial,
 
     /// The type is an Objective-C retainable pointer type that is qualified
     /// with the ARC __strong qualifier.
     PCK_ARCStrong,
 
     /// The type is an Objective-C retainable pointer type that is qualified
     /// with the ARC __weak qualifier.
     PCK_ARCWeak,
 
     /// The type is a struct containing a field whose type is neither
     /// PCK_Trivial nor PCK_VolatileTrivial.
     /// Note that a C++ struct type does not necessarily match this; C++ copying
     /// semantics are too complex to express here, in part because they depend
     /// on the exact constructor or assignment operator that is chosen by
     /// overload resolution to do the copy.
     PCK_Struct
   };
 
   /// Check if this is a non-trivial type that would cause a C struct
   /// transitively containing this type to be non-trivial to copy and return the
   /// kind.
   PrimitiveCopyKind isNonTrivialToPrimitiveCopy() const;
 
   /// Check if this is a non-trivial type that would cause a C struct
   /// transitively containing this type to be non-trivial to destructively
   /// move and return the kind. Destructive move in this context is a C++-style
   /// move in which the source object is placed in a valid but unspecified state
   /// after it is moved, as opposed to a truly destructive move in which the
   /// source object is placed in an uninitialized state.
   PrimitiveCopyKind isNonTrivialToPrimitiveDestructiveMove() const;
 
   enum DestructionKind {
     DK_none,
     DK_cxx_destructor,
     DK_objc_strong_lifetime,
     DK_objc_weak_lifetime,
     DK_nontrivial_c_struct
   };
 
   /// Returns a nonzero value if objects of this type require
   /// non-trivial work to clean up after.  Non-zero because it's
   /// conceivable that qualifiers (objc_gc(weak)?) could make
   /// something require destruction.
   DestructionKind isDestructedType() const {
     return isDestructedTypeImpl(*this);
   }
 
   /// Determine whether expressions of the given type are forbidden
   /// from being lvalues in C.
   ///
   /// The expression types that are forbidden to be lvalues are:
   ///   - 'void', but not qualified void
   ///   - function types
   ///
   /// The exact rule here is C99 6.3.2.1:
   ///   An lvalue is an expression with an object type or an incomplete
   ///   type other than void.
   bool isCForbiddenLValueType() const;
 
   /// Substitute type arguments for the Objective-C type parameters used in the
   /// subject type.
   ///
   /// \param ctx ASTContext in which the type exists.
   ///
   /// \param typeArgs The type arguments that will be substituted for the
   /// Objective-C type parameters in the subject type, which are generally
   /// computed via \c Type::getObjCSubstitutions. If empty, the type
   /// parameters will be replaced with their bounds or id/Class, as appropriate
   /// for the context.
   ///
   /// \param context The context in which the subject type was written.
   ///
   /// \returns the resulting type.
   QualType substObjCTypeArgs(ASTContext &ctx,
                              ArrayRef<QualType> typeArgs,
                              ObjCSubstitutionContext context) const;
 
   /// Substitute type arguments from an object type for the Objective-C type
   /// parameters used in the subject type.
   ///
   /// This operation combines the computation of type arguments for
   /// substitution (\c Type::getObjCSubstitutions) with the actual process of
   /// substitution (\c QualType::substObjCTypeArgs) for the convenience of
   /// callers that need to perform a single substitution in isolation.
   ///
   /// \param objectType The type of the object whose member type we're
   /// substituting into. For example, this might be the receiver of a message
   /// or the base of a property access.
   ///
   /// \param dc The declaration context from which the subject type was
   /// retrieved, which indicates (for example) which type parameters should
   /// be substituted.
   ///
   /// \param context The context in which the subject type was written.
   ///
   /// \returns the subject type after replacing all of the Objective-C type
   /// parameters with their corresponding arguments.
   QualType substObjCMemberType(QualType objectType,
                                const DeclContext *dc,
                                ObjCSubstitutionContext context) const;
 
   /// Strip Objective-C "__kindof" types from the given type.
   QualType stripObjCKindOfType(const ASTContext &ctx) const;
 
   /// Remove all qualifiers including _Atomic.
   QualType getAtomicUnqualifiedType() const;
 
 private:
   // These methods are implemented in a separate translation unit;
   // "static"-ize them to avoid creating temporary QualTypes in the
   // caller.
   static bool isConstant(QualType T, const ASTContext& Ctx);
   static QualType getDesugaredType(QualType T, const ASTContext &Context);
   static SplitQualType getSplitDesugaredType(QualType T);
   static SplitQualType getSplitUnqualifiedTypeImpl(QualType type);
   static QualType getSingleStepDesugaredTypeImpl(QualType type,
                                                  const ASTContext &C);
   static QualType IgnoreParens(QualType T);
   static DestructionKind isDestructedTypeImpl(QualType type);
 };
 
 } // namespace clang
 
 namespace llvm {
 
 /// Implement simplify_type for QualType, so that we can dyn_cast from QualType
 /// to a specific Type class.
 template<> struct simplify_type< ::clang::QualType> {
   using SimpleType = const ::clang::Type *;
 
   static SimpleType getSimplifiedValue(::clang::QualType Val) {
     return Val.getTypePtr();
   }
 };
 
 // Teach SmallPtrSet that QualType is "basically a pointer".
 template<>
 struct PointerLikeTypeTraits<clang::QualType> {
   static inline void *getAsVoidPointer(clang::QualType P) {
     return P.getAsOpaquePtr();
   }
 
   static inline clang::QualType getFromVoidPointer(void *P) {
     return clang::QualType::getFromOpaquePtr(P);
   }
 
   // Various qualifiers go in low bits.
   enum { NumLowBitsAvailable = 0 };
 };
 
 } // namespace llvm
 
 namespace clang {
 
 /// Base class that is common to both the \c ExtQuals and \c Type
 /// classes, which allows \c QualType to access the common fields between the
 /// two.
 class ExtQualsTypeCommonBase {
   friend class ExtQuals;
   friend class QualType;
   friend class Type;
 
   /// The "base" type of an extended qualifiers type (\c ExtQuals) or
   /// a self-referential pointer (for \c Type).
   ///
   /// This pointer allows an efficient mapping from a QualType to its
   /// underlying type pointer.
   const Type *const BaseType;
 
   /// The canonical type of this type.  A QualType.
   QualType CanonicalType;
 
   ExtQualsTypeCommonBase(const Type *baseType, QualType canon)
       : BaseType(baseType), CanonicalType(canon) {}
 };
 
 /// We can encode up to four bits in the low bits of a
 /// type pointer, but there are many more type qualifiers that we want
 /// to be able to apply to an arbitrary type.  Therefore we have this
 /// struct, intended to be heap-allocated and used by QualType to
 /// store qualifiers.
 ///
 /// The current design tags the 'const', 'restrict', and 'volatile' qualifiers
 /// in three low bits on the QualType pointer; a fourth bit records whether
 /// the pointer is an ExtQuals node. The extended qualifiers (address spaces,
 /// Objective-C GC attributes) are much more rare.
 class ExtQuals : public ExtQualsTypeCommonBase, public llvm::FoldingSetNode {
   // NOTE: changing the fast qualifiers should be straightforward as
   // long as you don't make 'const' non-fast.
   // 1. Qualifiers:
   //    a) Modify the bitmasks (Qualifiers::TQ and DeclSpec::TQ).
   //       Fast qualifiers must occupy the low-order bits.
   //    b) Update Qualifiers::FastWidth and FastMask.
   // 2. QualType:
   //    a) Update is{Volatile,Restrict}Qualified(), defined inline.
   //    b) Update remove{Volatile,Restrict}, defined near the end of
   //       this header.
   // 3. ASTContext:
   //    a) Update get{Volatile,Restrict}Type.
 
   /// The immutable set of qualifiers applied by this node. Always contains
   /// extended qualifiers.
   Qualifiers Quals;
 
   ExtQuals *this_() { return this; }
 
 public:
   ExtQuals(const Type *baseType, QualType canon, Qualifiers quals)
       : ExtQualsTypeCommonBase(baseType,
                                canon.isNull() ? QualType(this_(), 0) : canon),
         Quals(quals) {
     assert(Quals.hasNonFastQualifiers()
            && "ExtQuals created with no fast qualifiers");
     assert(!Quals.hasFastQualifiers()
            && "ExtQuals created with fast qualifiers");
   }
 
   Qualifiers getQualifiers() const { return Quals; }
 
   bool hasObjCGCAttr() const { return Quals.hasObjCGCAttr(); }
   Qualifiers::GC getObjCGCAttr() const { return Quals.getObjCGCAttr(); }
 
   bool hasObjCLifetime() const { return Quals.hasObjCLifetime(); }
   Qualifiers::ObjCLifetime getObjCLifetime() const {
     return Quals.getObjCLifetime();
   }
 
   bool hasAddressSpace() const { return Quals.hasAddressSpace(); }
   LangAS getAddressSpace() const { return Quals.getAddressSpace(); }
 
   const Type *getBaseType() const { return BaseType; }
 
 public:
   void Profile(llvm::FoldingSetNodeID &ID) const {
     Profile(ID, getBaseType(), Quals);
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID,
                       const Type *BaseType,
                       Qualifiers Quals) {
     assert(!Quals.hasFastQualifiers() && "fast qualifiers in ExtQuals hash!");
     ID.AddPointer(BaseType);
     Quals.Profile(ID);
   }
 };
 
 /// The kind of C++11 ref-qualifier associated with a function type.
 /// This determines whether a member function's "this" object can be an
 /// lvalue, rvalue, or neither.
 enum RefQualifierKind {
   /// No ref-qualifier was provided.
   RQ_None = 0,
 
   /// An lvalue ref-qualifier was provided (\c &).
   RQ_LValue,
 
   /// An rvalue ref-qualifier was provided (\c &&).
   RQ_RValue
 };
 
 /// Which keyword(s) were used to create an AutoType.
 enum class AutoTypeKeyword {
   /// auto
   Auto,
 
   /// decltype(auto)
   DecltypeAuto,
 
   /// __auto_type (GNU extension)
   GNUAutoType
 };
 
 /// The base class of the type hierarchy.
 ///
 /// A central concept with types is that each type always has a canonical
 /// type.  A canonical type is the type with any typedef names stripped out
 /// of it or the types it references.  For example, consider:
 ///
 ///  typedef int  foo;
 ///  typedef foo* bar;
 ///    'int *'    'foo *'    'bar'
 ///
 /// There will be a Type object created for 'int'.  Since int is canonical, its
 /// CanonicalType pointer points to itself.  There is also a Type for 'foo' (a
 /// TypedefType).  Its CanonicalType pointer points to the 'int' Type.  Next
 /// there is a PointerType that represents 'int*', which, like 'int', is
 /// canonical.  Finally, there is a PointerType type for 'foo*' whose canonical
 /// type is 'int*', and there is a TypedefType for 'bar', whose canonical type
 /// is also 'int*'.
 ///
 /// Non-canonical types are useful for emitting diagnostics, without losing
 /// information about typedefs being used.  Canonical types are useful for type
 /// comparisons (they allow by-pointer equality tests) and useful for reasoning
 /// about whether something has a particular form (e.g. is a function type),
 /// because they implicitly, recursively, strip all typedefs out of a type.
 ///
 /// Types, once created, are immutable.
 ///
 class Type : public ExtQualsTypeCommonBase {
 public:
   enum TypeClass {
 #define TYPE(Class, Base) Class,
 #define LAST_TYPE(Class) TypeLast = Class,
 #define ABSTRACT_TYPE(Class, Base)
 #include "clang/AST/TypeNodes.def"
     TagFirst = Record, TagLast = Enum
   };
 
 private:
   /// Bitfields required by the Type class.
   class TypeBitfields {
     friend class Type;
     template <class T> friend class TypePropertyCache;
 
     /// TypeClass bitfield - Enum that specifies what subclass this belongs to.
     unsigned TC : 8;
 
     /// Whether this type is a dependent type (C++ [temp.dep.type]).
     unsigned Dependent : 1;
 
     /// Whether this type somehow involves a template parameter, even
     /// if the resolution of the type does not depend on a template parameter.
     unsigned InstantiationDependent : 1;
 
     /// Whether this type is a variably-modified type (C99 6.7.5).
     unsigned VariablyModified : 1;
 
     /// Whether this type contains an unexpanded parameter pack
     /// (for C++11 variadic templates).
     unsigned ContainsUnexpandedParameterPack : 1;
 
     /// True if the cache (i.e. the bitfields here starting with
     /// 'Cache') is valid.
     mutable unsigned CacheValid : 1;
 
     /// Linkage of this type.
     mutable unsigned CachedLinkage : 3;
 
     /// Whether this type involves and local or unnamed types.
     mutable unsigned CachedLocalOrUnnamed : 1;
 
     /// Whether this type comes from an AST file.
     mutable unsigned FromAST : 1;
 
     bool isCacheValid() const {
       return CacheValid;
     }
 
     Linkage getLinkage() const {
       assert(isCacheValid() && "getting linkage from invalid cache");
       return static_cast<Linkage>(CachedLinkage);
     }
 
     bool hasLocalOrUnnamedType() const {
       assert(isCacheValid() && "getting linkage from invalid cache");
       return CachedLocalOrUnnamed;
     }
   };
   enum { NumTypeBits = 18 };
 
 protected:
   // These classes allow subclasses to somewhat cleanly pack bitfields
   // into Type.
 
   class ArrayTypeBitfields {
     friend class ArrayType;
 
     unsigned : NumTypeBits;
 
     /// CVR qualifiers from declarations like
     /// 'int X[static restrict 4]'. For function parameters only.
     unsigned IndexTypeQuals : 3;
 
     /// Storage class qualifiers from declarations like
     /// 'int X[static restrict 4]'. For function parameters only.
     /// Actually an ArrayType::ArraySizeModifier.
     unsigned SizeModifier : 3;
   };
 
   class BuiltinTypeBitfields {
     friend class BuiltinType;
 
     unsigned : NumTypeBits;
 
     /// The kind (BuiltinType::Kind) of builtin type this is.
     unsigned Kind : 8;
   };
 
   /// FunctionTypeBitfields store various bits belonging to FunctionProtoType.
   /// Only common bits are stored here. Additional uncommon bits are stored
   /// in a trailing object after FunctionProtoType.
   class FunctionTypeBitfields {
     friend class FunctionProtoType;
     friend class FunctionType;
 
     unsigned : NumTypeBits;
 
     /// Extra information which affects how the function is called, like
     /// regparm and the calling convention.
     unsigned ExtInfo : 12;
 
     /// The ref-qualifier associated with a \c FunctionProtoType.
     ///
     /// This is a value of type \c RefQualifierKind.
     unsigned RefQualifier : 2;
 
     /// Used only by FunctionProtoType, put here to pack with the
     /// other bitfields.
     /// The qualifiers are part of FunctionProtoType because...
     ///
     /// C++ 8.3.5p4: The return type, the parameter type list and the
     /// cv-qualifier-seq, [...], are part of the function type.
     unsigned FastTypeQuals : Qualifiers::FastWidth;
     /// Whether this function has extended Qualifiers.
     unsigned HasExtQuals : 1;
 
     /// The number of parameters this function has, not counting '...'.
     /// According to [implimits] 8 bits should be enough here but this is
     /// somewhat easy to exceed with metaprogramming and so we would like to
     /// keep NumParams as wide as reasonably possible.
     unsigned NumParams : 16;
 
     /// The type of exception specification this function has.
     unsigned ExceptionSpecType : 4;
 
     /// Whether this function has extended parameter information.
     unsigned HasExtParameterInfos : 1;
 
     /// Whether the function is variadic.
     unsigned Variadic : 1;
 
     /// Whether this function has a trailing return type.
     unsigned HasTrailingReturn : 1;
   };
 
   class ObjCObjectTypeBitfields {
     friend class ObjCObjectType;
 
     unsigned : NumTypeBits;
 
     /// The number of type arguments stored directly on this object type.
     unsigned NumTypeArgs : 7;
 
     /// The number of protocols stored directly on this object type.
     unsigned NumProtocols : 6;
 
     /// Whether this is a "kindof" type.
     unsigned IsKindOf : 1;
   };
 
   class ReferenceTypeBitfields {
     friend class ReferenceType;
 
     unsigned : NumTypeBits;
 
     /// True if the type was originally spelled with an lvalue sigil.
     /// This is never true of rvalue references but can also be false
     /// on lvalue references because of C++0x [dcl.typedef]p9,
     /// as follows:
     ///
     ///   typedef int &ref;    // lvalue, spelled lvalue
     ///   typedef int &&rvref; // rvalue
     ///   ref &a;              // lvalue, inner ref, spelled lvalue
     ///   ref &&a;             // lvalue, inner ref
     ///   rvref &a;            // lvalue, inner ref, spelled lvalue
     ///   rvref &&a;           // rvalue, inner ref
     unsigned SpelledAsLValue : 1;
 
     /// True if the inner type is a reference type.  This only happens
     /// in non-canonical forms.
     unsigned InnerRef : 1;
   };
 
   class TypeWithKeywordBitfields {
     friend class TypeWithKeyword;
 
     unsigned : NumTypeBits;
 
     /// An ElaboratedTypeKeyword.  8 bits for efficient access.
     unsigned Keyword : 8;
   };
 
   enum { NumTypeWithKeywordBits = 8 };
 
   class ElaboratedTypeBitfields {
     friend class ElaboratedType;
 
     unsigned : NumTypeBits;
     unsigned : NumTypeWithKeywordBits;
 
     /// Whether the ElaboratedType has a trailing OwnedTagDecl.
     unsigned HasOwnedTagDecl : 1;
   };
 
   class VectorTypeBitfields {
     friend class VectorType;
     friend class DependentVectorType;
 
     unsigned : NumTypeBits;
 
     /// The kind of vector, either a generic vector type or some
     /// target-specific vector type such as for AltiVec or Neon.
     unsigned VecKind : 3;
 
     /// The number of elements in the vector.
     unsigned NumElements : 29 - NumTypeBits;
 
     enum { MaxNumElements = (1 << (29 - NumTypeBits)) - 1 };
   };
 
   class AttributedTypeBitfields {
     friend class AttributedType;
 
     unsigned : NumTypeBits;
 
     /// An AttributedType::Kind
     unsigned AttrKind : 32 - NumTypeBits;
   };
 
   class AutoTypeBitfields {
     friend class AutoType;
 
     unsigned : NumTypeBits;
 
     /// Was this placeholder type spelled as 'auto', 'decltype(auto)',
     /// or '__auto_type'?  AutoTypeKeyword value.
     unsigned Keyword : 2;
   };
 
   class SubstTemplateTypeParmPackTypeBitfields {
     friend class SubstTemplateTypeParmPackType;
 
     unsigned : NumTypeBits;
 
     /// The number of template arguments in \c Arguments, which is
     /// expected to be able to hold at least 1024 according to [implimits].
     /// However as this limit is somewhat easy to hit with template
     /// metaprogramming we'd prefer to keep it as large as possible.
     /// At the moment it has been left as a non-bitfield since this type
     /// safely fits in 64 bits as an unsigned, so there is no reason to
     /// introduce the performance impact of a bitfield.
     unsigned NumArgs;
   };
 
   class TemplateSpecializationTypeBitfields {
     friend class TemplateSpecializationType;
 
     unsigned : NumTypeBits;
 
     /// Whether this template specialization type is a substituted type alias.
     unsigned TypeAlias : 1;
 
     /// The number of template arguments named in this class template
     /// specialization, which is expected to be able to hold at least 1024
     /// according to [implimits]. However, as this limit is somewhat easy to
     /// hit with template metaprogramming we'd prefer to keep it as large
     /// as possible. At the moment it has been left as a non-bitfield since
     /// this type safely fits in 64 bits as an unsigned, so there is no reason
     /// to introduce the performance impact of a bitfield.
     unsigned NumArgs;
   };
 
   class DependentTemplateSpecializationTypeBitfields {
     friend class DependentTemplateSpecializationType;
 
     unsigned : NumTypeBits;
     unsigned : NumTypeWithKeywordBits;
 
     /// The number of template arguments named in this class template
     /// specialization, which is expected to be able to hold at least 1024
     /// according to [implimits]. However, as this limit is somewhat easy to
     /// hit with template metaprogramming we'd prefer to keep it as large
     /// as possible. At the moment it has been left as a non-bitfield since
     /// this type safely fits in 64 bits as an unsigned, so there is no reason
     /// to introduce the performance impact of a bitfield.
     unsigned NumArgs;
   };
 
   class PackExpansionTypeBitfields {
     friend class PackExpansionType;
 
     unsigned : NumTypeBits;
 
     /// The number of expansions that this pack expansion will
     /// generate when substituted (+1), which is expected to be able to
     /// hold at least 1024 according to [implimits]. However, as this limit
     /// is somewhat easy to hit with template metaprogramming we'd prefer to
     /// keep it as large as possible. At the moment it has been left as a
     /// non-bitfield since this type safely fits in 64 bits as an unsigned, so
     /// there is no reason to introduce the performance impact of a bitfield.
     ///
     /// This field will only have a non-zero value when some of the parameter
     /// packs that occur within the pattern have been substituted but others
     /// have not.
     unsigned NumExpansions;
   };
 
   union {
     TypeBitfields TypeBits;
     ArrayTypeBitfields ArrayTypeBits;
     AttributedTypeBitfields AttributedTypeBits;
     AutoTypeBitfields AutoTypeBits;
     BuiltinTypeBitfields BuiltinTypeBits;
     FunctionTypeBitfields FunctionTypeBits;
     ObjCObjectTypeBitfields ObjCObjectTypeBits;
     ReferenceTypeBitfields ReferenceTypeBits;
     TypeWithKeywordBitfields TypeWithKeywordBits;
     ElaboratedTypeBitfields ElaboratedTypeBits;
     VectorTypeBitfields VectorTypeBits;
     SubstTemplateTypeParmPackTypeBitfields SubstTemplateTypeParmPackTypeBits;
     TemplateSpecializationTypeBitfields TemplateSpecializationTypeBits;
     DependentTemplateSpecializationTypeBitfields
       DependentTemplateSpecializationTypeBits;
     PackExpansionTypeBitfields PackExpansionTypeBits;
-
-    static_assert(sizeof(TypeBitfields) <= 8,
-                  "TypeBitfields is larger than 8 bytes!");
-    static_assert(sizeof(ArrayTypeBitfields) <= 8,
-                  "ArrayTypeBitfields is larger than 8 bytes!");
-    static_assert(sizeof(AttributedTypeBitfields) <= 8,
-                  "AttributedTypeBitfields is larger than 8 bytes!");
-    static_assert(sizeof(AutoTypeBitfields) <= 8,
-                  "AutoTypeBitfields is larger than 8 bytes!");
-    static_assert(sizeof(BuiltinTypeBitfields) <= 8,
-                  "BuiltinTypeBitfields is larger than 8 bytes!");
-    static_assert(sizeof(FunctionTypeBitfields) <= 8,
-                  "FunctionTypeBitfields is larger than 8 bytes!");
-    static_assert(sizeof(ObjCObjectTypeBitfields) <= 8,
-                  "ObjCObjectTypeBitfields is larger than 8 bytes!");
-    static_assert(sizeof(ReferenceTypeBitfields) <= 8,
-                  "ReferenceTypeBitfields is larger than 8 bytes!");
-    static_assert(sizeof(TypeWithKeywordBitfields) <= 8,
-                  "TypeWithKeywordBitfields is larger than 8 bytes!");
-    static_assert(sizeof(ElaboratedTypeBitfields) <= 8,
-                  "ElaboratedTypeBitfields is larger than 8 bytes!");
-    static_assert(sizeof(VectorTypeBitfields) <= 8,
-                  "VectorTypeBitfields is larger than 8 bytes!");
-    static_assert(sizeof(SubstTemplateTypeParmPackTypeBitfields) <= 8,
-                  "SubstTemplateTypeParmPackTypeBitfields is larger"
-                  " than 8 bytes!");
-    static_assert(sizeof(TemplateSpecializationTypeBitfields) <= 8,
-                  "TemplateSpecializationTypeBitfields is larger"
-                  " than 8 bytes!");
-    static_assert(sizeof(DependentTemplateSpecializationTypeBitfields) <= 8,
-                  "DependentTemplateSpecializationTypeBitfields is larger"
-                  " than 8 bytes!");
-    static_assert(sizeof(PackExpansionTypeBitfields) <= 8,
-                  "PackExpansionTypeBitfields is larger than 8 bytes");
   };
+
+  static_assert(sizeof(TypeBitfields) <= 8,
+		"TypeBitfields is larger than 8 bytes!");
+  static_assert(sizeof(ArrayTypeBitfields) <= 8,
+		"ArrayTypeBitfields is larger than 8 bytes!");
+  static_assert(sizeof(AttributedTypeBitfields) <= 8,
+		"AttributedTypeBitfields is larger than 8 bytes!");
+  static_assert(sizeof(AutoTypeBitfields) <= 8,
+		"AutoTypeBitfields is larger than 8 bytes!");
+  static_assert(sizeof(BuiltinTypeBitfields) <= 8,
+		"BuiltinTypeBitfields is larger than 8 bytes!");
+  static_assert(sizeof(FunctionTypeBitfields) <= 8,
+		"FunctionTypeBitfields is larger than 8 bytes!");
+  static_assert(sizeof(ObjCObjectTypeBitfields) <= 8,
+		"ObjCObjectTypeBitfields is larger than 8 bytes!");
+  static_assert(sizeof(ReferenceTypeBitfields) <= 8,
+		"ReferenceTypeBitfields is larger than 8 bytes!");
+  static_assert(sizeof(TypeWithKeywordBitfields) <= 8,
+		"TypeWithKeywordBitfields is larger than 8 bytes!");
+  static_assert(sizeof(ElaboratedTypeBitfields) <= 8,
+		"ElaboratedTypeBitfields is larger than 8 bytes!");
+  static_assert(sizeof(VectorTypeBitfields) <= 8,
+		"VectorTypeBitfields is larger than 8 bytes!");
+  static_assert(sizeof(SubstTemplateTypeParmPackTypeBitfields) <= 8,
+		"SubstTemplateTypeParmPackTypeBitfields is larger"
+		" than 8 bytes!");
+  static_assert(sizeof(TemplateSpecializationTypeBitfields) <= 8,
+		"TemplateSpecializationTypeBitfields is larger"
+		" than 8 bytes!");
+  static_assert(sizeof(DependentTemplateSpecializationTypeBitfields) <= 8,
+		"DependentTemplateSpecializationTypeBitfields is larger"
+		" than 8 bytes!");
+  static_assert(sizeof(PackExpansionTypeBitfields) <= 8,
+		"PackExpansionTypeBitfields is larger than 8 bytes");
 
 private:
   template <class T> friend class TypePropertyCache;
 
   /// Set whether this type comes from an AST file.
   void setFromAST(bool V = true) const {
     TypeBits.FromAST = V;
   }
 
 protected:
   friend class ASTContext;
 
   Type(TypeClass tc, QualType canon, bool Dependent,
        bool InstantiationDependent, bool VariablyModified,
        bool ContainsUnexpandedParameterPack)
       : ExtQualsTypeCommonBase(this,
                                canon.isNull() ? QualType(this_(), 0) : canon) {
     TypeBits.TC = tc;
     TypeBits.Dependent = Dependent;
     TypeBits.InstantiationDependent = Dependent || InstantiationDependent;
     TypeBits.VariablyModified = VariablyModified;
     TypeBits.ContainsUnexpandedParameterPack = ContainsUnexpandedParameterPack;
     TypeBits.CacheValid = false;
     TypeBits.CachedLocalOrUnnamed = false;
     TypeBits.CachedLinkage = NoLinkage;
     TypeBits.FromAST = false;
   }
 
   // silence VC++ warning C4355: 'this' : used in base member initializer list
   Type *this_() { return this; }
 
   void setDependent(bool D = true) {
     TypeBits.Dependent = D;
     if (D)
       TypeBits.InstantiationDependent = true;
   }
 
   void setInstantiationDependent(bool D = true) {
     TypeBits.InstantiationDependent = D; }
 
   void setVariablyModified(bool VM = true) { TypeBits.VariablyModified = VM; }
 
   void setContainsUnexpandedParameterPack(bool PP = true) {
     TypeBits.ContainsUnexpandedParameterPack = PP;
   }
 
 public:
   friend class ASTReader;
   friend class ASTWriter;
 
   Type(const Type &) = delete;
   Type &operator=(const Type &) = delete;
 
   TypeClass getTypeClass() const { return static_cast<TypeClass>(TypeBits.TC); }
 
   /// Whether this type comes from an AST file.
   bool isFromAST() const { return TypeBits.FromAST; }
 
   /// Whether this type is or contains an unexpanded parameter
   /// pack, used to support C++0x variadic templates.
   ///
   /// A type that contains a parameter pack shall be expanded by the
   /// ellipsis operator at some point. For example, the typedef in the
   /// following example contains an unexpanded parameter pack 'T':
   ///
   /// \code
   /// template<typename ...T>
   /// struct X {
   ///   typedef T* pointer_types; // ill-formed; T is a parameter pack.
   /// };
   /// \endcode
   ///
   /// Note that this routine does not specify which
   bool containsUnexpandedParameterPack() const {
     return TypeBits.ContainsUnexpandedParameterPack;
   }
 
   /// Determines if this type would be canonical if it had no further
   /// qualification.
   bool isCanonicalUnqualified() const {
     return CanonicalType == QualType(this, 0);
   }
 
   /// Pull a single level of sugar off of this locally-unqualified type.
   /// Users should generally prefer SplitQualType::getSingleStepDesugaredType()
   /// or QualType::getSingleStepDesugaredType(const ASTContext&).
   QualType getLocallyUnqualifiedSingleStepDesugaredType() const;
 
   /// Types are partitioned into 3 broad categories (C99 6.2.5p1):
   /// object types, function types, and incomplete types.
 
   /// Return true if this is an incomplete type.
   /// A type that can describe objects, but which lacks information needed to
   /// determine its size (e.g. void, or a fwd declared struct). Clients of this
   /// routine will need to determine if the size is actually required.
   ///
   /// Def If non-null, and the type refers to some kind of declaration
   /// that can be completed (such as a C struct, C++ class, or Objective-C
   /// class), will be set to the declaration.
   bool isIncompleteType(NamedDecl **Def = nullptr) const;
 
   /// Return true if this is an incomplete or object
   /// type, in other words, not a function type.
   bool isIncompleteOrObjectType() const {
     return !isFunctionType();
   }
 
   /// Determine whether this type is an object type.
   bool isObjectType() const {
     // C++ [basic.types]p8:
     //   An object type is a (possibly cv-qualified) type that is not a
     //   function type, not a reference type, and not a void type.
     return !isReferenceType() && !isFunctionType() && !isVoidType();
   }
 
   /// Return true if this is a literal type
   /// (C++11 [basic.types]p10)
   bool isLiteralType(const ASTContext &Ctx) const;
 
   /// Test if this type is a standard-layout type.
   /// (C++0x [basic.type]p9)
   bool isStandardLayoutType() const;
 
   /// Helper methods to distinguish type categories. All type predicates
   /// operate on the canonical type, ignoring typedefs and qualifiers.
 
   /// Returns true if the type is a builtin type.
   bool isBuiltinType() const;
 
   /// Test for a particular builtin type.
   bool isSpecificBuiltinType(unsigned K) const;
 
   /// Test for a type which does not represent an actual type-system type but
   /// is instead used as a placeholder for various convenient purposes within
   /// Clang.  All such types are BuiltinTypes.
   bool isPlaceholderType() const;
   const BuiltinType *getAsPlaceholderType() const;
 
   /// Test for a specific placeholder type.
   bool isSpecificPlaceholderType(unsigned K) const;
 
   /// Test for a placeholder type other than Overload; see
   /// BuiltinType::isNonOverloadPlaceholderType.
   bool isNonOverloadPlaceholderType() const;
 
   /// isIntegerType() does *not* include complex integers (a GCC extension).
   /// isComplexIntegerType() can be used to test for complex integers.
   bool isIntegerType() const;     // C99 6.2.5p17 (int, char, bool, enum)
   bool isEnumeralType() const;
 
   /// Determine whether this type is a scoped enumeration type.
   bool isScopedEnumeralType() const;
   bool isBooleanType() const;
   bool isCharType() const;
   bool isWideCharType() const;
   bool isChar8Type() const;
   bool isChar16Type() const;
   bool isChar32Type() const;
   bool isAnyCharacterType() const;
   bool isIntegralType(const ASTContext &Ctx) const;
 
   /// Determine whether this type is an integral or enumeration type.
   bool isIntegralOrEnumerationType() const;
 
   /// Determine whether this type is an integral or unscoped enumeration type.
   bool isIntegralOrUnscopedEnumerationType() const;
 
   /// Floating point categories.
   bool isRealFloatingType() const; // C99 6.2.5p10 (float, double, long double)
   /// isComplexType() does *not* include complex integers (a GCC extension).
   /// isComplexIntegerType() can be used to test for complex integers.
   bool isComplexType() const;      // C99 6.2.5p11 (complex)
   bool isAnyComplexType() const;   // C99 6.2.5p11 (complex) + Complex Int.
   bool isFloatingType() const;     // C99 6.2.5p11 (real floating + complex)
   bool isHalfType() const;         // OpenCL 6.1.1.1, NEON (IEEE 754-2008 half)
   bool isFloat16Type() const;      // C11 extension ISO/IEC TS 18661
   bool isFloat128Type() const;
   bool isRealType() const;         // C99 6.2.5p17 (real floating + integer)
   bool isArithmeticType() const;   // C99 6.2.5p18 (integer + floating)
   bool isVoidType() const;         // C99 6.2.5p19
   bool isScalarType() const;       // C99 6.2.5p21 (arithmetic + pointers)
   bool isAggregateType() const;
   bool isFundamentalType() const;
   bool isCompoundType() const;
 
   // Type Predicates: Check to see if this type is structurally the specified
   // type, ignoring typedefs and qualifiers.
   bool isFunctionType() const;
   bool isFunctionNoProtoType() const { return getAs<FunctionNoProtoType>(); }
   bool isFunctionProtoType() const { return getAs<FunctionProtoType>(); }
   bool isPointerType() const;
   bool isAnyPointerType() const;   // Any C pointer or ObjC object pointer
   bool isBlockPointerType() const;
   bool isVoidPointerType() const;
   bool isReferenceType() const;
   bool isLValueReferenceType() const;
   bool isRValueReferenceType() const;
   bool isFunctionPointerType() const;
   bool isMemberPointerType() const;
   bool isMemberFunctionPointerType() const;
   bool isMemberDataPointerType() const;
   bool isArrayType() const;
   bool isConstantArrayType() const;
   bool isIncompleteArrayType() const;
   bool isVariableArrayType() const;
   bool isDependentSizedArrayType() const;
   bool isRecordType() const;
   bool isClassType() const;
   bool isStructureType() const;
   bool isObjCBoxableRecordType() const;
   bool isInterfaceType() const;
   bool isStructureOrClassType() const;
   bool isUnionType() const;
   bool isComplexIntegerType() const;            // GCC _Complex integer type.
   bool isVectorType() const;                    // GCC vector type.
   bool isExtVectorType() const;                 // Extended vector type.
   bool isDependentAddressSpaceType() const;     // value-dependent address space qualifier
   bool isObjCObjectPointerType() const;         // pointer to ObjC object
   bool isObjCRetainableType() const;            // ObjC object or block pointer
   bool isObjCLifetimeType() const;              // (array of)* retainable type
   bool isObjCIndirectLifetimeType() const;      // (pointer to)* lifetime type
   bool isObjCNSObjectType() const;              // __attribute__((NSObject))
   bool isObjCIndependentClassType() const;      // __attribute__((objc_independent_class))
   // FIXME: change this to 'raw' interface type, so we can used 'interface' type
   // for the common case.
   bool isObjCObjectType() const;                // NSString or typeof(*(id)0)
   bool isObjCQualifiedInterfaceType() const;    // NSString<foo>
   bool isObjCQualifiedIdType() const;           // id<foo>
   bool isObjCQualifiedClassType() const;        // Class<foo>
   bool isObjCObjectOrInterfaceType() const;
   bool isObjCIdType() const;                    // id
 
   /// Was this type written with the special inert-in-ARC __unsafe_unretained
   /// qualifier?
   ///
   /// This approximates the answer to the following question: if this
   /// translation unit were compiled in ARC, would this type be qualified
   /// with __unsafe_unretained?
   bool isObjCInertUnsafeUnretainedType() const {
     return hasAttr(attr::ObjCInertUnsafeUnretained);
   }
 
   /// Whether the type is Objective-C 'id' or a __kindof type of an
   /// object type, e.g., __kindof NSView * or __kindof id
   /// <NSCopying>.
   ///
   /// \param bound Will be set to the bound on non-id subtype types,
   /// which will be (possibly specialized) Objective-C class type, or
   /// null for 'id.
   bool isObjCIdOrObjectKindOfType(const ASTContext &ctx,
                                   const ObjCObjectType *&bound) const;
 
   bool isObjCClassType() const;                 // Class
 
   /// Whether the type is Objective-C 'Class' or a __kindof type of an
   /// Class type, e.g., __kindof Class <NSCopying>.
   ///
   /// Unlike \c isObjCIdOrObjectKindOfType, there is no relevant bound
   /// here because Objective-C's type system cannot express "a class
   /// object for a subclass of NSFoo".
   bool isObjCClassOrClassKindOfType() const;
 
   bool isBlockCompatibleObjCPointerType(ASTContext &ctx) const;
   bool isObjCSelType() const;                 // Class
   bool isObjCBuiltinType() const;               // 'id' or 'Class'
   bool isObjCARCBridgableType() const;
   bool isCARCBridgableType() const;
   bool isTemplateTypeParmType() const;          // C++ template type parameter
   bool isNullPtrType() const;                   // C++11 std::nullptr_t
   bool isAlignValT() const;                     // C++17 std::align_val_t
   bool isStdByteType() const;                   // C++17 std::byte
   bool isAtomicType() const;                    // C11 _Atomic()
 
 #define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \
   bool is##Id##Type() const;
 #include "clang/Basic/OpenCLImageTypes.def"
 
   bool isImageType() const;                     // Any OpenCL image type
 
   bool isSamplerT() const;                      // OpenCL sampler_t
   bool isEventT() const;                        // OpenCL event_t
   bool isClkEventT() const;                     // OpenCL clk_event_t
   bool isQueueT() const;                        // OpenCL queue_t
   bool isReserveIDT() const;                    // OpenCL reserve_id_t
 
 #define EXT_OPAQUE_TYPE(ExtType, Id, Ext) \
   bool is##Id##Type() const;
 #include "clang/Basic/OpenCLExtensionTypes.def"
   // Type defined in cl_intel_device_side_avc_motion_estimation OpenCL extension
   bool isOCLIntelSubgroupAVCType() const;
   bool isOCLExtOpaqueType() const;              // Any OpenCL extension type
 
   bool isPipeType() const;                      // OpenCL pipe type
   bool isOpenCLSpecificType() const;            // Any OpenCL specific type
 
   /// Determines if this type, which must satisfy
   /// isObjCLifetimeType(), is implicitly __unsafe_unretained rather
   /// than implicitly __strong.
   bool isObjCARCImplicitlyUnretainedType() const;
 
   /// Return the implicit lifetime for this type, which must not be dependent.
   Qualifiers::ObjCLifetime getObjCARCImplicitLifetime() const;
 
   enum ScalarTypeKind {
     STK_CPointer,
     STK_BlockPointer,
     STK_ObjCObjectPointer,
     STK_MemberPointer,
     STK_Bool,
     STK_Integral,
     STK_Floating,
     STK_IntegralComplex,
     STK_FloatingComplex,
     STK_FixedPoint
   };
 
   /// Given that this is a scalar type, classify it.
   ScalarTypeKind getScalarTypeKind() const;
 
   /// Whether this type is a dependent type, meaning that its definition
   /// somehow depends on a template parameter (C++ [temp.dep.type]).
   bool isDependentType() const { return TypeBits.Dependent; }
 
   /// Determine whether this type is an instantiation-dependent type,
   /// meaning that the type involves a template parameter (even if the
   /// definition does not actually depend on the type substituted for that
   /// template parameter).
   bool isInstantiationDependentType() const {
     return TypeBits.InstantiationDependent;
   }
 
   /// Determine whether this type is an undeduced type, meaning that
   /// it somehow involves a C++11 'auto' type or similar which has not yet been
   /// deduced.
   bool isUndeducedType() const;
 
   /// Whether this type is a variably-modified type (C99 6.7.5).
   bool isVariablyModifiedType() const { return TypeBits.VariablyModified; }
 
   /// Whether this type involves a variable-length array type
   /// with a definite size.
   bool hasSizedVLAType() const;
 
   /// Whether this type is or contains a local or unnamed type.
   bool hasUnnamedOrLocalType() const;
 
   bool isOverloadableType() const;
 
   /// Determine wither this type is a C++ elaborated-type-specifier.
   bool isElaboratedTypeSpecifier() const;
 
   bool canDecayToPointerType() const;
 
   /// Whether this type is represented natively as a pointer.  This includes
   /// pointers, references, block pointers, and Objective-C interface,
   /// qualified id, and qualified interface types, as well as nullptr_t.
   bool hasPointerRepresentation() const;
 
   /// Whether this type can represent an objective pointer type for the
   /// purpose of GC'ability
   bool hasObjCPointerRepresentation() const;
 
   /// Determine whether this type has an integer representation
   /// of some sort, e.g., it is an integer type or a vector.
   bool hasIntegerRepresentation() const;
 
   /// Determine whether this type has an signed integer representation
   /// of some sort, e.g., it is an signed integer type or a vector.
   bool hasSignedIntegerRepresentation() const;
 
   /// Determine whether this type has an unsigned integer representation
   /// of some sort, e.g., it is an unsigned integer type or a vector.
   bool hasUnsignedIntegerRepresentation() const;
 
   /// Determine whether this type has a floating-point representation
   /// of some sort, e.g., it is a floating-point type or a vector thereof.
   bool hasFloatingRepresentation() const;
 
   // Type Checking Functions: Check to see if this type is structurally the
   // specified type, ignoring typedefs and qualifiers, and return a pointer to
   // the best type we can.
   const RecordType *getAsStructureType() const;
   /// NOTE: getAs*ArrayType are methods on ASTContext.
   const RecordType *getAsUnionType() const;
   const ComplexType *getAsComplexIntegerType() const; // GCC complex int type.
   const ObjCObjectType *getAsObjCInterfaceType() const;
 
   // The following is a convenience method that returns an ObjCObjectPointerType
   // for object declared using an interface.
   const ObjCObjectPointerType *getAsObjCInterfacePointerType() const;
   const ObjCObjectPointerType *getAsObjCQualifiedIdType() const;
   const ObjCObjectPointerType *getAsObjCQualifiedClassType() const;
   const ObjCObjectType *getAsObjCQualifiedInterfaceType() const;
 
   /// Retrieves the CXXRecordDecl that this type refers to, either
   /// because the type is a RecordType or because it is the injected-class-name
   /// type of a class template or class template partial specialization.
   CXXRecordDecl *getAsCXXRecordDecl() const;
 
   /// Retrieves the RecordDecl this type refers to.
   RecordDecl *getAsRecordDecl() const;
 
   /// Retrieves the TagDecl that this type refers to, either
   /// because the type is a TagType or because it is the injected-class-name
   /// type of a class template or class template partial specialization.
   TagDecl *getAsTagDecl() const;
 
   /// If this is a pointer or reference to a RecordType, return the
   /// CXXRecordDecl that the type refers to.
   ///
   /// If this is not a pointer or reference, or the type being pointed to does
   /// not refer to a CXXRecordDecl, returns NULL.
   const CXXRecordDecl *getPointeeCXXRecordDecl() const;
 
   /// Get the DeducedType whose type will be deduced for a variable with
   /// an initializer of this type. This looks through declarators like pointer
   /// types, but not through decltype or typedefs.
   DeducedType *getContainedDeducedType() const;
 
   /// Get the AutoType whose type will be deduced for a variable with
   /// an initializer of this type. This looks through declarators like pointer
   /// types, but not through decltype or typedefs.
   AutoType *getContainedAutoType() const {
     return dyn_cast_or_null<AutoType>(getContainedDeducedType());
   }
 
   /// Determine whether this type was written with a leading 'auto'
   /// corresponding to a trailing return type (possibly for a nested
   /// function type within a pointer to function type or similar).
   bool hasAutoForTrailingReturnType() const;
 
   /// Member-template getAs<specific type>'.  Look through sugar for
   /// an instance of \<specific type>.   This scheme will eventually
   /// replace the specific getAsXXXX methods above.
   ///
   /// There are some specializations of this member template listed
   /// immediately following this class.
   template <typename T> const T *getAs() const;
 
   /// Member-template getAsAdjusted<specific type>. Look through specific kinds
   /// of sugar (parens, attributes, etc) for an instance of \<specific type>.
   /// This is used when you need to walk over sugar nodes that represent some
   /// kind of type adjustment from a type that was written as a \<specific type>
   /// to another type that is still canonically a \<specific type>.
   template <typename T> const T *getAsAdjusted() const;
 
   /// A variant of getAs<> for array types which silently discards
   /// qualifiers from the outermost type.
   const ArrayType *getAsArrayTypeUnsafe() const;
 
   /// Member-template castAs<specific type>.  Look through sugar for
   /// the underlying instance of \<specific type>.
   ///
   /// This method has the same relationship to getAs<T> as cast<T> has
   /// to dyn_cast<T>; which is to say, the underlying type *must*
   /// have the intended type, and this method will never return null.
   template <typename T> const T *castAs() const;
 
   /// A variant of castAs<> for array type which silently discards
   /// qualifiers from the outermost type.
   const ArrayType *castAsArrayTypeUnsafe() const;
 
   /// Determine whether this type had the specified attribute applied to it
   /// (looking through top-level type sugar).
   bool hasAttr(attr::Kind AK) const;
 
   /// Get the base element type of this type, potentially discarding type
   /// qualifiers.  This should never be used when type qualifiers
   /// are meaningful.
   const Type *getBaseElementTypeUnsafe() const;
 
   /// If this is an array type, return the element type of the array,
   /// potentially with type qualifiers missing.
   /// This should never be used when type qualifiers are meaningful.
   const Type *getArrayElementTypeNoTypeQual() const;
 
   /// If this is a pointer type, return the pointee type.
   /// If this is an array type, return the array element type.
   /// This should never be used when type qualifiers are meaningful.
   const Type *getPointeeOrArrayElementType() const;
 
   /// If this is a pointer, ObjC object pointer, or block
   /// pointer, this returns the respective pointee.
   QualType getPointeeType() const;
 
   /// Return the specified type with any "sugar" removed from the type,
   /// removing any typedefs, typeofs, etc., as well as any qualifiers.
   const Type *getUnqualifiedDesugaredType() const;
 
   /// More type predicates useful for type checking/promotion
   bool isPromotableIntegerType() const; // C99 6.3.1.1p2
 
   /// Return true if this is an integer type that is
   /// signed, according to C99 6.2.5p4 [char, signed char, short, int, long..],
   /// or an enum decl which has a signed representation.
   bool isSignedIntegerType() const;
 
   /// Return true if this is an integer type that is
   /// unsigned, according to C99 6.2.5p6 [which returns true for _Bool],
   /// or an enum decl which has an unsigned representation.
   bool isUnsignedIntegerType() const;
 
   /// Determines whether this is an integer type that is signed or an
   /// enumeration types whose underlying type is a signed integer type.
   bool isSignedIntegerOrEnumerationType() const;
 
   /// Determines whether this is an integer type that is unsigned or an
   /// enumeration types whose underlying type is a unsigned integer type.
   bool isUnsignedIntegerOrEnumerationType() const;
 
   /// Return true if this is a fixed point type according to
   /// ISO/IEC JTC1 SC22 WG14 N1169.
   bool isFixedPointType() const;
 
   /// Return true if this is a saturated fixed point type according to
   /// ISO/IEC JTC1 SC22 WG14 N1169. This type can be signed or unsigned.
   bool isSaturatedFixedPointType() const;
 
   /// Return true if this is a saturated fixed point type according to
   /// ISO/IEC JTC1 SC22 WG14 N1169. This type can be signed or unsigned.
   bool isUnsaturatedFixedPointType() const;
 
   /// Return true if this is a fixed point type that is signed according
   /// to ISO/IEC JTC1 SC22 WG14 N1169. This type can also be saturated.
   bool isSignedFixedPointType() const;
 
   /// Return true if this is a fixed point type that is unsigned according
   /// to ISO/IEC JTC1 SC22 WG14 N1169. This type can also be saturated.
   bool isUnsignedFixedPointType() const;
 
   /// Return true if this is not a variable sized type,
   /// according to the rules of C99 6.7.5p3.  It is not legal to call this on
   /// incomplete types.
   bool isConstantSizeType() const;
 
   /// Returns true if this type can be represented by some
   /// set of type specifiers.
   bool isSpecifierType() const;
 
   /// Determine the linkage of this type.
   Linkage getLinkage() const;
 
   /// Determine the visibility of this type.
   Visibility getVisibility() const {
     return getLinkageAndVisibility().getVisibility();
   }
 
   /// Return true if the visibility was explicitly set is the code.
   bool isVisibilityExplicit() const {
     return getLinkageAndVisibility().isVisibilityExplicit();
   }
 
   /// Determine the linkage and visibility of this type.
   LinkageInfo getLinkageAndVisibility() const;
 
   /// True if the computed linkage is valid. Used for consistency
   /// checking. Should always return true.
   bool isLinkageValid() const;
 
   /// Determine the nullability of the given type.
   ///
   /// Note that nullability is only captured as sugar within the type
   /// system, not as part of the canonical type, so nullability will
   /// be lost by canonicalization and desugaring.
   Optional<NullabilityKind> getNullability(const ASTContext &context) const;
 
   /// Determine whether the given type can have a nullability
   /// specifier applied to it, i.e., if it is any kind of pointer type.
   ///
   /// \param ResultIfUnknown The value to return if we don't yet know whether
   ///        this type can have nullability because it is dependent.
   bool canHaveNullability(bool ResultIfUnknown = true) const;
 
   /// Retrieve the set of substitutions required when accessing a member
   /// of the Objective-C receiver type that is declared in the given context.
   ///
   /// \c *this is the type of the object we're operating on, e.g., the
   /// receiver for a message send or the base of a property access, and is
   /// expected to be of some object or object pointer type.
   ///
   /// \param dc The declaration context for which we are building up a
   /// substitution mapping, which should be an Objective-C class, extension,
   /// category, or method within.
   ///
   /// \returns an array of type arguments that can be substituted for
   /// the type parameters of the given declaration context in any type described
   /// within that context, or an empty optional to indicate that no
   /// substitution is required.
   Optional<ArrayRef<QualType>>
   getObjCSubstitutions(const DeclContext *dc) const;
 
   /// Determines if this is an ObjC interface type that may accept type
   /// parameters.
   bool acceptsObjCTypeParams() const;
 
   const char *getTypeClassName() const;
 
   QualType getCanonicalTypeInternal() const {
     return CanonicalType;
   }
 
   CanQualType getCanonicalTypeUnqualified() const; // in CanonicalType.h
   void dump() const;
   void dump(llvm::raw_ostream &OS) const;
 };
 
 /// This will check for a TypedefType by removing any existing sugar
 /// until it reaches a TypedefType or a non-sugared type.
 template <> const TypedefType *Type::getAs() const;
 
 /// This will check for a TemplateSpecializationType by removing any
 /// existing sugar until it reaches a TemplateSpecializationType or a
 /// non-sugared type.
 template <> const TemplateSpecializationType *Type::getAs() const;
 
 /// This will check for an AttributedType by removing any existing sugar
 /// until it reaches an AttributedType or a non-sugared type.
 template <> const AttributedType *Type::getAs() const;
 
 // We can do canonical leaf types faster, because we don't have to
 // worry about preserving child type decoration.
 #define TYPE(Class, Base)
 #define LEAF_TYPE(Class) \
 template <> inline const Class##Type *Type::getAs() const { \
   return dyn_cast<Class##Type>(CanonicalType); \
 } \
 template <> inline const Class##Type *Type::castAs() const { \
   return cast<Class##Type>(CanonicalType); \
 }
 #include "clang/AST/TypeNodes.def"
 
 /// This class is used for builtin types like 'int'.  Builtin
 /// types are always canonical and have a literal name field.
 class BuiltinType : public Type {
 public:
   enum Kind {
 // OpenCL image types
 #define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) Id,
 #include "clang/Basic/OpenCLImageTypes.def"
 // OpenCL extension types
 #define EXT_OPAQUE_TYPE(ExtType, Id, Ext) Id,
 #include "clang/Basic/OpenCLExtensionTypes.def"
 // All other builtin types
 #define BUILTIN_TYPE(Id, SingletonId) Id,
 #define LAST_BUILTIN_TYPE(Id) LastKind = Id
 #include "clang/AST/BuiltinTypes.def"
   };
 
 private:
   friend class ASTContext; // ASTContext creates these.
 
   BuiltinType(Kind K)
       : Type(Builtin, QualType(), /*Dependent=*/(K == Dependent),
              /*InstantiationDependent=*/(K == Dependent),
              /*VariablyModified=*/false,
              /*Unexpanded parameter pack=*/false) {
     BuiltinTypeBits.Kind = K;
   }
 
 public:
   Kind getKind() const { return static_cast<Kind>(BuiltinTypeBits.Kind); }
   StringRef getName(const PrintingPolicy &Policy) const;
 
   const char *getNameAsCString(const PrintingPolicy &Policy) const {
     // The StringRef is null-terminated.
     StringRef str = getName(Policy);
     assert(!str.empty() && str.data()[str.size()] == '\0');
     return str.data();
   }
 
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   bool isInteger() const {
     return getKind() >= Bool && getKind() <= Int128;
   }
 
   bool isSignedInteger() const {
     return getKind() >= Char_S && getKind() <= Int128;
   }
 
   bool isUnsignedInteger() const {
     return getKind() >= Bool && getKind() <= UInt128;
   }
 
   bool isFloatingPoint() const {
     return getKind() >= Half && getKind() <= Float128;
   }
 
   /// Determines whether the given kind corresponds to a placeholder type.
   static bool isPlaceholderTypeKind(Kind K) {
     return K >= Overload;
   }
 
   /// Determines whether this type is a placeholder type, i.e. a type
   /// which cannot appear in arbitrary positions in a fully-formed
   /// expression.
   bool isPlaceholderType() const {
     return isPlaceholderTypeKind(getKind());
   }
 
   /// Determines whether this type is a placeholder type other than
   /// Overload.  Most placeholder types require only syntactic
   /// information about their context in order to be resolved (e.g.
   /// whether it is a call expression), which means they can (and
   /// should) be resolved in an earlier "phase" of analysis.
   /// Overload expressions sometimes pick up further information
   /// from their context, like whether the context expects a
   /// specific function-pointer type, and so frequently need
   /// special treatment.
   bool isNonOverloadPlaceholderType() const {
     return getKind() > Overload;
   }
 
   static bool classof(const Type *T) { return T->getTypeClass() == Builtin; }
 };
 
 /// Complex values, per C99 6.2.5p11.  This supports the C99 complex
 /// types (_Complex float etc) as well as the GCC integer complex extensions.
 class ComplexType : public Type, public llvm::FoldingSetNode {
   friend class ASTContext; // ASTContext creates these.
 
   QualType ElementType;
 
   ComplexType(QualType Element, QualType CanonicalPtr)
       : Type(Complex, CanonicalPtr, Element->isDependentType(),
              Element->isInstantiationDependentType(),
              Element->isVariablyModifiedType(),
              Element->containsUnexpandedParameterPack()),
         ElementType(Element) {}
 
 public:
   QualType getElementType() const { return ElementType; }
 
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, getElementType());
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, QualType Element) {
     ID.AddPointer(Element.getAsOpaquePtr());
   }
 
   static bool classof(const Type *T) { return T->getTypeClass() == Complex; }
 };
 
 /// Sugar for parentheses used when specifying types.
 class ParenType : public Type, public llvm::FoldingSetNode {
   friend class ASTContext; // ASTContext creates these.
 
   QualType Inner;
 
   ParenType(QualType InnerType, QualType CanonType)
       : Type(Paren, CanonType, InnerType->isDependentType(),
              InnerType->isInstantiationDependentType(),
              InnerType->isVariablyModifiedType(),
              InnerType->containsUnexpandedParameterPack()),
         Inner(InnerType) {}
 
 public:
   QualType getInnerType() const { return Inner; }
 
   bool isSugared() const { return true; }
   QualType desugar() const { return getInnerType(); }
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, getInnerType());
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, QualType Inner) {
     Inner.Profile(ID);
   }
 
   static bool classof(const Type *T) { return T->getTypeClass() == Paren; }
 };
 
 /// PointerType - C99 6.7.5.1 - Pointer Declarators.
 class PointerType : public Type, public llvm::FoldingSetNode {
   friend class ASTContext; // ASTContext creates these.
 
   QualType PointeeType;
 
   PointerType(QualType Pointee, QualType CanonicalPtr)
       : Type(Pointer, CanonicalPtr, Pointee->isDependentType(),
              Pointee->isInstantiationDependentType(),
              Pointee->isVariablyModifiedType(),
              Pointee->containsUnexpandedParameterPack()),
         PointeeType(Pointee) {}
 
 public:
   QualType getPointeeType() const { return PointeeType; }
 
   /// Returns true if address spaces of pointers overlap.
   /// OpenCL v2.0 defines conversion rules for pointers to different
   /// address spaces (OpenCLC v2.0 s6.5.5) and notion of overlapping
   /// address spaces.
   /// CL1.1 or CL1.2:
   ///   address spaces overlap iff they are they same.
   /// CL2.0 adds:
   ///   __generic overlaps with any address space except for __constant.
   bool isAddressSpaceOverlapping(const PointerType &other) const {
     Qualifiers thisQuals = PointeeType.getQualifiers();
     Qualifiers otherQuals = other.getPointeeType().getQualifiers();
     // Address spaces overlap if at least one of them is a superset of another
     return thisQuals.isAddressSpaceSupersetOf(otherQuals) ||
            otherQuals.isAddressSpaceSupersetOf(thisQuals);
   }
 
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, getPointeeType());
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, QualType Pointee) {
     ID.AddPointer(Pointee.getAsOpaquePtr());
   }
 
   static bool classof(const Type *T) { return T->getTypeClass() == Pointer; }
 };
 
 /// Represents a type which was implicitly adjusted by the semantic
 /// engine for arbitrary reasons.  For example, array and function types can
 /// decay, and function types can have their calling conventions adjusted.
 class AdjustedType : public Type, public llvm::FoldingSetNode {
   QualType OriginalTy;
   QualType AdjustedTy;
 
 protected:
   friend class ASTContext; // ASTContext creates these.
 
   AdjustedType(TypeClass TC, QualType OriginalTy, QualType AdjustedTy,
                QualType CanonicalPtr)
       : Type(TC, CanonicalPtr, OriginalTy->isDependentType(),
              OriginalTy->isInstantiationDependentType(),
              OriginalTy->isVariablyModifiedType(),
              OriginalTy->containsUnexpandedParameterPack()),
         OriginalTy(OriginalTy), AdjustedTy(AdjustedTy) {}
 
 public:
   QualType getOriginalType() const { return OriginalTy; }
   QualType getAdjustedType() const { return AdjustedTy; }
 
   bool isSugared() const { return true; }
   QualType desugar() const { return AdjustedTy; }
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, OriginalTy, AdjustedTy);
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, QualType Orig, QualType New) {
     ID.AddPointer(Orig.getAsOpaquePtr());
     ID.AddPointer(New.getAsOpaquePtr());
   }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == Adjusted || T->getTypeClass() == Decayed;
   }
 };
 
 /// Represents a pointer type decayed from an array or function type.
 class DecayedType : public AdjustedType {
   friend class ASTContext; // ASTContext creates these.
 
   inline
   DecayedType(QualType OriginalType, QualType Decayed, QualType Canonical);
 
 public:
   QualType getDecayedType() const { return getAdjustedType(); }
 
   inline QualType getPointeeType() const;
 
   static bool classof(const Type *T) { return T->getTypeClass() == Decayed; }
 };
 
 /// Pointer to a block type.
 /// This type is to represent types syntactically represented as
 /// "void (^)(int)", etc. Pointee is required to always be a function type.
 class BlockPointerType : public Type, public llvm::FoldingSetNode {
   friend class ASTContext; // ASTContext creates these.
 
   // Block is some kind of pointer type
   QualType PointeeType;
 
   BlockPointerType(QualType Pointee, QualType CanonicalCls)
       : Type(BlockPointer, CanonicalCls, Pointee->isDependentType(),
              Pointee->isInstantiationDependentType(),
              Pointee->isVariablyModifiedType(),
              Pointee->containsUnexpandedParameterPack()),
         PointeeType(Pointee) {}
 
 public:
   // Get the pointee type. Pointee is required to always be a function type.
   QualType getPointeeType() const { return PointeeType; }
 
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   void Profile(llvm::FoldingSetNodeID &ID) {
       Profile(ID, getPointeeType());
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, QualType Pointee) {
       ID.AddPointer(Pointee.getAsOpaquePtr());
   }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == BlockPointer;
   }
 };
 
 /// Base for LValueReferenceType and RValueReferenceType
 class ReferenceType : public Type, public llvm::FoldingSetNode {
   QualType PointeeType;
 
 protected:
   ReferenceType(TypeClass tc, QualType Referencee, QualType CanonicalRef,
                 bool SpelledAsLValue)
       : Type(tc, CanonicalRef, Referencee->isDependentType(),
              Referencee->isInstantiationDependentType(),
              Referencee->isVariablyModifiedType(),
              Referencee->containsUnexpandedParameterPack()),
         PointeeType(Referencee) {
     ReferenceTypeBits.SpelledAsLValue = SpelledAsLValue;
     ReferenceTypeBits.InnerRef = Referencee->isReferenceType();
   }
 
 public:
   bool isSpelledAsLValue() const { return ReferenceTypeBits.SpelledAsLValue; }
   bool isInnerRef() const { return ReferenceTypeBits.InnerRef; }
 
   QualType getPointeeTypeAsWritten() const { return PointeeType; }
 
   QualType getPointeeType() const {
     // FIXME: this might strip inner qualifiers; okay?
     const ReferenceType *T = this;
     while (T->isInnerRef())
       T = T->PointeeType->castAs<ReferenceType>();
     return T->PointeeType;
   }
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, PointeeType, isSpelledAsLValue());
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID,
                       QualType Referencee,
                       bool SpelledAsLValue) {
     ID.AddPointer(Referencee.getAsOpaquePtr());
     ID.AddBoolean(SpelledAsLValue);
   }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == LValueReference ||
            T->getTypeClass() == RValueReference;
   }
 };
 
 /// An lvalue reference type, per C++11 [dcl.ref].
 class LValueReferenceType : public ReferenceType {
   friend class ASTContext; // ASTContext creates these
 
   LValueReferenceType(QualType Referencee, QualType CanonicalRef,
                       bool SpelledAsLValue)
       : ReferenceType(LValueReference, Referencee, CanonicalRef,
                       SpelledAsLValue) {}
 
 public:
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == LValueReference;
   }
 };
 
 /// An rvalue reference type, per C++11 [dcl.ref].
 class RValueReferenceType : public ReferenceType {
   friend class ASTContext; // ASTContext creates these
 
   RValueReferenceType(QualType Referencee, QualType CanonicalRef)
        : ReferenceType(RValueReference, Referencee, CanonicalRef, false) {}
 
 public:
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == RValueReference;
   }
 };
 
 /// A pointer to member type per C++ 8.3.3 - Pointers to members.
 ///
 /// This includes both pointers to data members and pointer to member functions.
 class MemberPointerType : public Type, public llvm::FoldingSetNode {
   friend class ASTContext; // ASTContext creates these.
 
   QualType PointeeType;
 
   /// The class of which the pointee is a member. Must ultimately be a
   /// RecordType, but could be a typedef or a template parameter too.
   const Type *Class;
 
   MemberPointerType(QualType Pointee, const Type *Cls, QualType CanonicalPtr)
       : Type(MemberPointer, CanonicalPtr,
              Cls->isDependentType() || Pointee->isDependentType(),
              (Cls->isInstantiationDependentType() ||
               Pointee->isInstantiationDependentType()),
              Pointee->isVariablyModifiedType(),
              (Cls->containsUnexpandedParameterPack() ||
               Pointee->containsUnexpandedParameterPack())),
              PointeeType(Pointee), Class(Cls) {}
 
 public:
   QualType getPointeeType() const { return PointeeType; }
 
   /// Returns true if the member type (i.e. the pointee type) is a
   /// function type rather than a data-member type.
   bool isMemberFunctionPointer() const {
     return PointeeType->isFunctionProtoType();
   }
 
   /// Returns true if the member type (i.e. the pointee type) is a
   /// data type rather than a function type.
   bool isMemberDataPointer() const {
     return !PointeeType->isFunctionProtoType();
   }
 
   const Type *getClass() const { return Class; }
   CXXRecordDecl *getMostRecentCXXRecordDecl() const;
 
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, getPointeeType(), getClass());
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, QualType Pointee,
                       const Type *Class) {
     ID.AddPointer(Pointee.getAsOpaquePtr());
     ID.AddPointer(Class);
   }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == MemberPointer;
   }
 };
 
 /// Represents an array type, per C99 6.7.5.2 - Array Declarators.
 class ArrayType : public Type, public llvm::FoldingSetNode {
 public:
   /// Capture whether this is a normal array (e.g. int X[4])
   /// an array with a static size (e.g. int X[static 4]), or an array
   /// with a star size (e.g. int X[*]).
   /// 'static' is only allowed on function parameters.
   enum ArraySizeModifier {
     Normal, Static, Star
   };
 
 private:
   /// The element type of the array.
   QualType ElementType;
 
 protected:
   friend class ASTContext; // ASTContext creates these.
 
   // C++ [temp.dep.type]p1:
   //   A type is dependent if it is...
   //     - an array type constructed from any dependent type or whose
   //       size is specified by a constant expression that is
   //       value-dependent,
   ArrayType(TypeClass tc, QualType et, QualType can,
             ArraySizeModifier sm, unsigned tq,
             bool ContainsUnexpandedParameterPack)
       : Type(tc, can, et->isDependentType() || tc == DependentSizedArray,
              et->isInstantiationDependentType() || tc == DependentSizedArray,
              (tc == VariableArray || et->isVariablyModifiedType()),
              ContainsUnexpandedParameterPack),
         ElementType(et) {
     ArrayTypeBits.IndexTypeQuals = tq;
     ArrayTypeBits.SizeModifier = sm;
   }
 
 public:
   QualType getElementType() const { return ElementType; }
 
   ArraySizeModifier getSizeModifier() const {
     return ArraySizeModifier(ArrayTypeBits.SizeModifier);
   }
 
   Qualifiers getIndexTypeQualifiers() const {
     return Qualifiers::fromCVRMask(getIndexTypeCVRQualifiers());
   }
 
   unsigned getIndexTypeCVRQualifiers() const {
     return ArrayTypeBits.IndexTypeQuals;
   }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == ConstantArray ||
            T->getTypeClass() == VariableArray ||
            T->getTypeClass() == IncompleteArray ||
            T->getTypeClass() == DependentSizedArray;
   }
 };
 
 /// Represents the canonical version of C arrays with a specified constant size.
 /// For example, the canonical type for 'int A[4 + 4*100]' is a
 /// ConstantArrayType where the element type is 'int' and the size is 404.
 class ConstantArrayType : public ArrayType {
   llvm::APInt Size; // Allows us to unique the type.
 
   ConstantArrayType(QualType et, QualType can, const llvm::APInt &size,
                     ArraySizeModifier sm, unsigned tq)
       : ArrayType(ConstantArray, et, can, sm, tq,
                   et->containsUnexpandedParameterPack()),
         Size(size) {}
 
 protected:
   friend class ASTContext; // ASTContext creates these.
 
   ConstantArrayType(TypeClass tc, QualType et, QualType can,
                     const llvm::APInt &size, ArraySizeModifier sm, unsigned tq)
       : ArrayType(tc, et, can, sm, tq, et->containsUnexpandedParameterPack()),
         Size(size) {}
 
 public:
   const llvm::APInt &getSize() const { return Size; }
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   /// Determine the number of bits required to address a member of
   // an array with the given element type and number of elements.
   static unsigned getNumAddressingBits(const ASTContext &Context,
                                        QualType ElementType,
                                        const llvm::APInt &NumElements);
 
   /// Determine the maximum number of active bits that an array's size
   /// can require, which limits the maximum size of the array.
   static unsigned getMaxSizeBits(const ASTContext &Context);
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, getElementType(), getSize(),
             getSizeModifier(), getIndexTypeCVRQualifiers());
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, QualType ET,
                       const llvm::APInt &ArraySize, ArraySizeModifier SizeMod,
                       unsigned TypeQuals) {
     ID.AddPointer(ET.getAsOpaquePtr());
     ID.AddInteger(ArraySize.getZExtValue());
     ID.AddInteger(SizeMod);
     ID.AddInteger(TypeQuals);
   }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == ConstantArray;
   }
 };
 
 /// Represents a C array with an unspecified size.  For example 'int A[]' has
 /// an IncompleteArrayType where the element type is 'int' and the size is
 /// unspecified.
 class IncompleteArrayType : public ArrayType {
   friend class ASTContext; // ASTContext creates these.
 
   IncompleteArrayType(QualType et, QualType can,
                       ArraySizeModifier sm, unsigned tq)
       : ArrayType(IncompleteArray, et, can, sm, tq,
                   et->containsUnexpandedParameterPack()) {}
 
 public:
   friend class StmtIteratorBase;
 
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == IncompleteArray;
   }
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, getElementType(), getSizeModifier(),
             getIndexTypeCVRQualifiers());
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, QualType ET,
                       ArraySizeModifier SizeMod, unsigned TypeQuals) {
     ID.AddPointer(ET.getAsOpaquePtr());
     ID.AddInteger(SizeMod);
     ID.AddInteger(TypeQuals);
   }
 };
 
 /// Represents a C array with a specified size that is not an
 /// integer-constant-expression.  For example, 'int s[x+foo()]'.
 /// Since the size expression is an arbitrary expression, we store it as such.
 ///
 /// Note: VariableArrayType's aren't uniqued (since the expressions aren't) and
 /// should not be: two lexically equivalent variable array types could mean
 /// different things, for example, these variables do not have the same type
 /// dynamically:
 ///
 /// void foo(int x) {
 ///   int Y[x];
 ///   ++x;
 ///   int Z[x];
 /// }
 class VariableArrayType : public ArrayType {
   friend class ASTContext; // ASTContext creates these.
 
   /// An assignment-expression. VLA's are only permitted within
   /// a function block.
   Stmt *SizeExpr;
 
   /// The range spanned by the left and right array brackets.
   SourceRange Brackets;
 
   VariableArrayType(QualType et, QualType can, Expr *e,
                     ArraySizeModifier sm, unsigned tq,
                     SourceRange brackets)
       : ArrayType(VariableArray, et, can, sm, tq,
                   et->containsUnexpandedParameterPack()),
         SizeExpr((Stmt*) e), Brackets(brackets) {}
 
 public:
   friend class StmtIteratorBase;
 
   Expr *getSizeExpr() const {
     // We use C-style casts instead of cast<> here because we do not wish
     // to have a dependency of Type.h on Stmt.h/Expr.h.
     return (Expr*) SizeExpr;
   }
 
   SourceRange getBracketsRange() const { return Brackets; }
   SourceLocation getLBracketLoc() const { return Brackets.getBegin(); }
   SourceLocation getRBracketLoc() const { return Brackets.getEnd(); }
 
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == VariableArray;
   }
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     llvm_unreachable("Cannot unique VariableArrayTypes.");
   }
 };
 
 /// Represents an array type in C++ whose size is a value-dependent expression.
 ///
 /// For example:
 /// \code
 /// template<typename T, int Size>
 /// class array {
 ///   T data[Size];
 /// };
 /// \endcode
 ///
 /// For these types, we won't actually know what the array bound is
 /// until template instantiation occurs, at which point this will
 /// become either a ConstantArrayType or a VariableArrayType.
 class DependentSizedArrayType : public ArrayType {
   friend class ASTContext; // ASTContext creates these.
 
   const ASTContext &Context;
 
   /// An assignment expression that will instantiate to the
   /// size of the array.
   ///
   /// The expression itself might be null, in which case the array
   /// type will have its size deduced from an initializer.
   Stmt *SizeExpr;
 
   /// The range spanned by the left and right array brackets.
   SourceRange Brackets;
 
   DependentSizedArrayType(const ASTContext &Context, QualType et, QualType can,
                           Expr *e, ArraySizeModifier sm, unsigned tq,
                           SourceRange brackets);
 
 public:
   friend class StmtIteratorBase;
 
   Expr *getSizeExpr() const {
     // We use C-style casts instead of cast<> here because we do not wish
     // to have a dependency of Type.h on Stmt.h/Expr.h.
     return (Expr*) SizeExpr;
   }
 
   SourceRange getBracketsRange() const { return Brackets; }
   SourceLocation getLBracketLoc() const { return Brackets.getBegin(); }
   SourceLocation getRBracketLoc() const { return Brackets.getEnd(); }
 
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == DependentSizedArray;
   }
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, Context, getElementType(),
             getSizeModifier(), getIndexTypeCVRQualifiers(), getSizeExpr());
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &Context,
                       QualType ET, ArraySizeModifier SizeMod,
                       unsigned TypeQuals, Expr *E);
 };
 
 /// Represents an extended address space qualifier where the input address space
 /// value is dependent. Non-dependent address spaces are not represented with a
 /// special Type subclass; they are stored on an ExtQuals node as part of a QualType.
 ///
 /// For example:
 /// \code
 /// template<typename T, int AddrSpace>
 /// class AddressSpace {
 ///   typedef T __attribute__((address_space(AddrSpace))) type;
 /// }
 /// \endcode
 class DependentAddressSpaceType : public Type, public llvm::FoldingSetNode {
   friend class ASTContext;
 
   const ASTContext &Context;
   Expr *AddrSpaceExpr;
   QualType PointeeType;
   SourceLocation loc;
 
   DependentAddressSpaceType(const ASTContext &Context, QualType PointeeType,
                             QualType can, Expr *AddrSpaceExpr,
                             SourceLocation loc);
 
 public:
   Expr *getAddrSpaceExpr() const { return AddrSpaceExpr; }
   QualType getPointeeType() const { return PointeeType; }
   SourceLocation getAttributeLoc() const { return loc; }
 
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == DependentAddressSpace;
   }
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, Context, getPointeeType(), getAddrSpaceExpr());
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &Context,
                       QualType PointeeType, Expr *AddrSpaceExpr);
 };
 
 /// Represents an extended vector type where either the type or size is
 /// dependent.
 ///
 /// For example:
 /// \code
 /// template<typename T, int Size>
 /// class vector {
 ///   typedef T __attribute__((ext_vector_type(Size))) type;
 /// }
 /// \endcode
 class DependentSizedExtVectorType : public Type, public llvm::FoldingSetNode {
   friend class ASTContext;
 
   const ASTContext &Context;
   Expr *SizeExpr;
 
   /// The element type of the array.
   QualType ElementType;
 
   SourceLocation loc;
 
   DependentSizedExtVectorType(const ASTContext &Context, QualType ElementType,
                               QualType can, Expr *SizeExpr, SourceLocation loc);
 
 public:
   Expr *getSizeExpr() const { return SizeExpr; }
   QualType getElementType() const { return ElementType; }
   SourceLocation getAttributeLoc() const { return loc; }
 
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == DependentSizedExtVector;
   }
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, Context, getElementType(), getSizeExpr());
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &Context,
                       QualType ElementType, Expr *SizeExpr);
 };
 
 
 /// Represents a GCC generic vector type. This type is created using
 /// __attribute__((vector_size(n)), where "n" specifies the vector size in
 /// bytes; or from an Altivec __vector or vector declaration.
 /// Since the constructor takes the number of vector elements, the
 /// client is responsible for converting the size into the number of elements.
 class VectorType : public Type, public llvm::FoldingSetNode {
 public:
   enum VectorKind {
     /// not a target-specific vector type
     GenericVector,
 
     /// is AltiVec vector
     AltiVecVector,
 
     /// is AltiVec 'vector Pixel'
     AltiVecPixel,
 
     /// is AltiVec 'vector bool ...'
     AltiVecBool,
 
     /// is ARM Neon vector
     NeonVector,
 
     /// is ARM Neon polynomial vector
     NeonPolyVector
   };
 
 protected:
   friend class ASTContext; // ASTContext creates these.
 
   /// The element type of the vector.
   QualType ElementType;
 
   VectorType(QualType vecType, unsigned nElements, QualType canonType,
              VectorKind vecKind);
 
   VectorType(TypeClass tc, QualType vecType, unsigned nElements,
              QualType canonType, VectorKind vecKind);
 
 public:
   QualType getElementType() const { return ElementType; }
   unsigned getNumElements() const { return VectorTypeBits.NumElements; }
 
   static bool isVectorSizeTooLarge(unsigned NumElements) {
     return NumElements > VectorTypeBitfields::MaxNumElements;
   }
 
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   VectorKind getVectorKind() const {
     return VectorKind(VectorTypeBits.VecKind);
   }
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, getElementType(), getNumElements(),
             getTypeClass(), getVectorKind());
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, QualType ElementType,
                       unsigned NumElements, TypeClass TypeClass,
                       VectorKind VecKind) {
     ID.AddPointer(ElementType.getAsOpaquePtr());
     ID.AddInteger(NumElements);
     ID.AddInteger(TypeClass);
     ID.AddInteger(VecKind);
   }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == Vector || T->getTypeClass() == ExtVector;
   }
 };
 
 /// Represents a vector type where either the type or size is dependent.
 ////
 /// For example:
 /// \code
 /// template<typename T, int Size>
 /// class vector {
 ///   typedef T __attribute__((vector_size(Size))) type;
 /// }
 /// \endcode
 class DependentVectorType : public Type, public llvm::FoldingSetNode {
   friend class ASTContext;
 
   const ASTContext &Context;
   QualType ElementType;
   Expr *SizeExpr;
   SourceLocation Loc;
 
   DependentVectorType(const ASTContext &Context, QualType ElementType,
                            QualType CanonType, Expr *SizeExpr,
                            SourceLocation Loc, VectorType::VectorKind vecKind);
 
 public:
   Expr *getSizeExpr() const { return SizeExpr; }
   QualType getElementType() const { return ElementType; }
   SourceLocation getAttributeLoc() const { return Loc; }
   VectorType::VectorKind getVectorKind() const {
     return VectorType::VectorKind(VectorTypeBits.VecKind);
   }
 
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == DependentVector;
   }
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, Context, getElementType(), getSizeExpr(), getVectorKind());
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &Context,
                       QualType ElementType, const Expr *SizeExpr,
                       VectorType::VectorKind VecKind);
 };
 
 /// ExtVectorType - Extended vector type. This type is created using
 /// __attribute__((ext_vector_type(n)), where "n" is the number of elements.
 /// Unlike vector_size, ext_vector_type is only allowed on typedef's. This
 /// class enables syntactic extensions, like Vector Components for accessing
 /// points (as .xyzw), colors (as .rgba), and textures (modeled after OpenGL
 /// Shading Language).
 class ExtVectorType : public VectorType {
   friend class ASTContext; // ASTContext creates these.
 
   ExtVectorType(QualType vecType, unsigned nElements, QualType canonType)
       : VectorType(ExtVector, vecType, nElements, canonType, GenericVector) {}
 
 public:
   static int getPointAccessorIdx(char c) {
     switch (c) {
     default: return -1;
     case 'x': case 'r': return 0;
     case 'y': case 'g': return 1;
     case 'z': case 'b': return 2;
     case 'w': case 'a': return 3;
     }
   }
 
   static int getNumericAccessorIdx(char c) {
     switch (c) {
       default: return -1;
       case '0': return 0;
       case '1': return 1;
       case '2': return 2;
       case '3': return 3;
       case '4': return 4;
       case '5': return 5;
       case '6': return 6;
       case '7': return 7;
       case '8': return 8;
       case '9': return 9;
       case 'A':
       case 'a': return 10;
       case 'B':
       case 'b': return 11;
       case 'C':
       case 'c': return 12;
       case 'D':
       case 'd': return 13;
       case 'E':
       case 'e': return 14;
       case 'F':
       case 'f': return 15;
     }
   }
 
   static int getAccessorIdx(char c, bool isNumericAccessor) {
     if (isNumericAccessor)
       return getNumericAccessorIdx(c);
     else
       return getPointAccessorIdx(c);
   }
 
   bool isAccessorWithinNumElements(char c, bool isNumericAccessor) const {
     if (int idx = getAccessorIdx(c, isNumericAccessor)+1)
       return unsigned(idx-1) < getNumElements();
     return false;
   }
 
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == ExtVector;
   }
 };
 
 /// FunctionType - C99 6.7.5.3 - Function Declarators.  This is the common base
 /// class of FunctionNoProtoType and FunctionProtoType.
 class FunctionType : public Type {
   // The type returned by the function.
   QualType ResultType;
 
 public:
   /// Interesting information about a specific parameter that can't simply
   /// be reflected in parameter's type. This is only used by FunctionProtoType
   /// but is in FunctionType to make this class available during the
   /// specification of the bases of FunctionProtoType.
   ///
   /// It makes sense to model language features this way when there's some
   /// sort of parameter-specific override (such as an attribute) that
   /// affects how the function is called.  For example, the ARC ns_consumed
   /// attribute changes whether a parameter is passed at +0 (the default)
   /// or +1 (ns_consumed).  This must be reflected in the function type,
   /// but isn't really a change to the parameter type.
   ///
   /// One serious disadvantage of modelling language features this way is
   /// that they generally do not work with language features that attempt
   /// to destructure types.  For example, template argument deduction will
   /// not be able to match a parameter declared as
   ///   T (*)(U)
   /// against an argument of type
   ///   void (*)(__attribute__((ns_consumed)) id)
   /// because the substitution of T=void, U=id into the former will
   /// not produce the latter.
   class ExtParameterInfo {
     enum {
       ABIMask = 0x0F,
       IsConsumed = 0x10,
       HasPassObjSize = 0x20,
       IsNoEscape = 0x40,
     };
     unsigned char Data = 0;
 
   public:
     ExtParameterInfo() = default;
 
     /// Return the ABI treatment of this parameter.
     ParameterABI getABI() const { return ParameterABI(Data & ABIMask); }
     ExtParameterInfo withABI(ParameterABI kind) const {
       ExtParameterInfo copy = *this;
       copy.Data = (copy.Data & ~ABIMask) | unsigned(kind);
       return copy;
     }
 
     /// Is this parameter considered "consumed" by Objective-C ARC?
     /// Consumed parameters must have retainable object type.
     bool isConsumed() const { return (Data & IsConsumed); }
     ExtParameterInfo withIsConsumed(bool consumed) const {
       ExtParameterInfo copy = *this;
       if (consumed)
         copy.Data |= IsConsumed;
       else
         copy.Data &= ~IsConsumed;
       return copy;
     }
 
     bool hasPassObjectSize() const { return Data & HasPassObjSize; }
     ExtParameterInfo withHasPassObjectSize() const {
       ExtParameterInfo Copy = *this;
       Copy.Data |= HasPassObjSize;
       return Copy;
     }
 
     bool isNoEscape() const { return Data & IsNoEscape; }
     ExtParameterInfo withIsNoEscape(bool NoEscape) const {
       ExtParameterInfo Copy = *this;
       if (NoEscape)
         Copy.Data |= IsNoEscape;
       else
         Copy.Data &= ~IsNoEscape;
       return Copy;
     }
 
     unsigned char getOpaqueValue() const { return Data; }
     static ExtParameterInfo getFromOpaqueValue(unsigned char data) {
       ExtParameterInfo result;
       result.Data = data;
       return result;
     }
 
     friend bool operator==(ExtParameterInfo lhs, ExtParameterInfo rhs) {
       return lhs.Data == rhs.Data;
     }
 
     friend bool operator!=(ExtParameterInfo lhs, ExtParameterInfo rhs) {
       return lhs.Data != rhs.Data;
     }
   };
 
   /// A class which abstracts out some details necessary for
   /// making a call.
   ///
   /// It is not actually used directly for storing this information in
   /// a FunctionType, although FunctionType does currently use the
   /// same bit-pattern.
   ///
   // If you add a field (say Foo), other than the obvious places (both,
   // constructors, compile failures), what you need to update is
   // * Operator==
   // * getFoo
   // * withFoo
   // * functionType. Add Foo, getFoo.
   // * ASTContext::getFooType
   // * ASTContext::mergeFunctionTypes
   // * FunctionNoProtoType::Profile
   // * FunctionProtoType::Profile
   // * TypePrinter::PrintFunctionProto
   // * AST read and write
   // * Codegen
   class ExtInfo {
     friend class FunctionType;
 
     // Feel free to rearrange or add bits, but if you go over 12,
     // you'll need to adjust both the Bits field below and
     // Type::FunctionTypeBitfields.
 
     //   |  CC  |noreturn|produces|nocallersavedregs|regparm|nocfcheck|
     //   |0 .. 4|   5    |    6   |       7         |8 .. 10|    11   |
     //
     // regparm is either 0 (no regparm attribute) or the regparm value+1.
     enum { CallConvMask = 0x1F };
     enum { NoReturnMask = 0x20 };
     enum { ProducesResultMask = 0x40 };
     enum { NoCallerSavedRegsMask = 0x80 };
     enum { NoCfCheckMask = 0x800 };
     enum {
       RegParmMask = ~(CallConvMask | NoReturnMask | ProducesResultMask |
                       NoCallerSavedRegsMask | NoCfCheckMask),
       RegParmOffset = 8
     }; // Assumed to be the last field
     uint16_t Bits = CC_C;
 
     ExtInfo(unsigned Bits) : Bits(static_cast<uint16_t>(Bits)) {}
 
    public:
      // Constructor with no defaults. Use this when you know that you
      // have all the elements (when reading an AST file for example).
      ExtInfo(bool noReturn, bool hasRegParm, unsigned regParm, CallingConv cc,
              bool producesResult, bool noCallerSavedRegs, bool NoCfCheck) {
        assert((!hasRegParm || regParm < 7) && "Invalid regparm value");
        Bits = ((unsigned)cc) | (noReturn ? NoReturnMask : 0) |
               (producesResult ? ProducesResultMask : 0) |
               (noCallerSavedRegs ? NoCallerSavedRegsMask : 0) |
               (hasRegParm ? ((regParm + 1) << RegParmOffset) : 0) |
               (NoCfCheck ? NoCfCheckMask : 0);
     }
 
     // Constructor with all defaults. Use when for example creating a
     // function known to use defaults.
     ExtInfo() = default;
 
     // Constructor with just the calling convention, which is an important part
     // of the canonical type.
     ExtInfo(CallingConv CC) : Bits(CC) {}
 
     bool getNoReturn() const { return Bits & NoReturnMask; }
     bool getProducesResult() const { return Bits & ProducesResultMask; }
     bool getNoCallerSavedRegs() const { return Bits & NoCallerSavedRegsMask; }
     bool getNoCfCheck() const { return Bits & NoCfCheckMask; }
     bool getHasRegParm() const { return (Bits >> RegParmOffset) != 0; }
 
     unsigned getRegParm() const {
       unsigned RegParm = (Bits & RegParmMask) >> RegParmOffset;
       if (RegParm > 0)
         --RegParm;
       return RegParm;
     }
 
     CallingConv getCC() const { return CallingConv(Bits & CallConvMask); }
 
     bool operator==(ExtInfo Other) const {
       return Bits == Other.Bits;
     }
     bool operator!=(ExtInfo Other) const {
       return Bits != Other.Bits;
     }
 
     // Note that we don't have setters. That is by design, use
     // the following with methods instead of mutating these objects.
 
     ExtInfo withNoReturn(bool noReturn) const {
       if (noReturn)
         return ExtInfo(Bits | NoReturnMask);
       else
         return ExtInfo(Bits & ~NoReturnMask);
     }
 
     ExtInfo withProducesResult(bool producesResult) const {
       if (producesResult)
         return ExtInfo(Bits | ProducesResultMask);
       else
         return ExtInfo(Bits & ~ProducesResultMask);
     }
 
     ExtInfo withNoCallerSavedRegs(bool noCallerSavedRegs) const {
       if (noCallerSavedRegs)
         return ExtInfo(Bits | NoCallerSavedRegsMask);
       else
         return ExtInfo(Bits & ~NoCallerSavedRegsMask);
     }
 
     ExtInfo withNoCfCheck(bool noCfCheck) const {
       if (noCfCheck)
         return ExtInfo(Bits | NoCfCheckMask);
       else
         return ExtInfo(Bits & ~NoCfCheckMask);
     }
 
     ExtInfo withRegParm(unsigned RegParm) const {
       assert(RegParm < 7 && "Invalid regparm value");
       return ExtInfo((Bits & ~RegParmMask) |
                      ((RegParm + 1) << RegParmOffset));
     }
 
     ExtInfo withCallingConv(CallingConv cc) const {
       return ExtInfo((Bits & ~CallConvMask) | (unsigned) cc);
     }
 
     void Profile(llvm::FoldingSetNodeID &ID) const {
       ID.AddInteger(Bits);
     }
   };
 
   /// A simple holder for a QualType representing a type in an
   /// exception specification. Unfortunately needed by FunctionProtoType
   /// because TrailingObjects cannot handle repeated types.
   struct ExceptionType { QualType Type; };
 
   /// A simple holder for various uncommon bits which do not fit in
   /// FunctionTypeBitfields. Aligned to alignof(void *) to maintain the
   /// alignment of subsequent objects in TrailingObjects. You must update
   /// hasExtraBitfields in FunctionProtoType after adding extra data here.
   struct alignas(void *) FunctionTypeExtraBitfields {
     /// The number of types in the exception specification.
     /// A whole unsigned is not needed here and according to
     /// [implimits] 8 bits would be enough here.
     unsigned NumExceptionType;
   };
 
 protected:
   FunctionType(TypeClass tc, QualType res,
                QualType Canonical, bool Dependent,
                bool InstantiationDependent,
                bool VariablyModified, bool ContainsUnexpandedParameterPack,
                ExtInfo Info)
       : Type(tc, Canonical, Dependent, InstantiationDependent, VariablyModified,
              ContainsUnexpandedParameterPack),
         ResultType(res) {
     FunctionTypeBits.ExtInfo = Info.Bits;
   }
 
   Qualifiers getFastTypeQuals() const {
     return Qualifiers::fromFastMask(FunctionTypeBits.FastTypeQuals);
   }
 
 public:
   QualType getReturnType() const { return ResultType; }
 
   bool getHasRegParm() const { return getExtInfo().getHasRegParm(); }
   unsigned getRegParmType() const { return getExtInfo().getRegParm(); }
 
   /// Determine whether this function type includes the GNU noreturn
   /// attribute. The C++11 [[noreturn]] attribute does not affect the function
   /// type.
   bool getNoReturnAttr() const { return getExtInfo().getNoReturn(); }
 
   CallingConv getCallConv() const { return getExtInfo().getCC(); }
   ExtInfo getExtInfo() const { return ExtInfo(FunctionTypeBits.ExtInfo); }
 
   static_assert((~Qualifiers::FastMask & Qualifiers::CVRMask) == 0,
                 "Const, volatile and restrict are assumed to be a subset of "
                 "the fast qualifiers.");
 
   bool isConst() const { return getFastTypeQuals().hasConst(); }
   bool isVolatile() const { return getFastTypeQuals().hasVolatile(); }
   bool isRestrict() const { return getFastTypeQuals().hasRestrict(); }
 
   /// Determine the type of an expression that calls a function of
   /// this type.
   QualType getCallResultType(const ASTContext &Context) const {
     return getReturnType().getNonLValueExprType(Context);
   }
 
   static StringRef getNameForCallConv(CallingConv CC);
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == FunctionNoProto ||
            T->getTypeClass() == FunctionProto;
   }
 };
 
 /// Represents a K&R-style 'int foo()' function, which has
 /// no information available about its arguments.
 class FunctionNoProtoType : public FunctionType, public llvm::FoldingSetNode {
   friend class ASTContext; // ASTContext creates these.
 
   FunctionNoProtoType(QualType Result, QualType Canonical, ExtInfo Info)
       : FunctionType(FunctionNoProto, Result, Canonical,
                      /*Dependent=*/false, /*InstantiationDependent=*/false,
                      Result->isVariablyModifiedType(),
                      /*ContainsUnexpandedParameterPack=*/false, Info) {}
 
 public:
   // No additional state past what FunctionType provides.
 
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, getReturnType(), getExtInfo());
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, QualType ResultType,
                       ExtInfo Info) {
     Info.Profile(ID);
     ID.AddPointer(ResultType.getAsOpaquePtr());
   }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == FunctionNoProto;
   }
 };
 
 /// Represents a prototype with parameter type info, e.g.
 /// 'int foo(int)' or 'int foo(void)'.  'void' is represented as having no
 /// parameters, not as having a single void parameter. Such a type can have
 /// an exception specification, but this specification is not part of the
 /// canonical type. FunctionProtoType has several trailing objects, some of
 /// which optional. For more information about the trailing objects see
 /// the first comment inside FunctionProtoType.
 class FunctionProtoType final
     : public FunctionType,
       public llvm::FoldingSetNode,
       private llvm::TrailingObjects<
           FunctionProtoType, QualType, FunctionType::FunctionTypeExtraBitfields,
           FunctionType::ExceptionType, Expr *, FunctionDecl *,
           FunctionType::ExtParameterInfo, Qualifiers> {
   friend class ASTContext; // ASTContext creates these.
   friend TrailingObjects;
 
   // FunctionProtoType is followed by several trailing objects, some of
   // which optional. They are in order:
   //
   // * An array of getNumParams() QualType holding the parameter types.
   //   Always present. Note that for the vast majority of FunctionProtoType,
   //   these will be the only trailing objects.
   //
   // * Optionally if some extra data is stored in FunctionTypeExtraBitfields
   //   (see FunctionTypeExtraBitfields and FunctionTypeBitfields):
   //   a single FunctionTypeExtraBitfields. Present if and only if
   //   hasExtraBitfields() is true.
   //
   // * Optionally exactly one of:
   //   * an array of getNumExceptions() ExceptionType,
   //   * a single Expr *,
   //   * a pair of FunctionDecl *,
   //   * a single FunctionDecl *
   //   used to store information about the various types of exception
   //   specification. See getExceptionSpecSize for the details.
   //
   // * Optionally an array of getNumParams() ExtParameterInfo holding
   //   an ExtParameterInfo for each of the parameters. Present if and
   //   only if hasExtParameterInfos() is true.
   //
   // * Optionally a Qualifiers object to represent extra qualifiers that can't
   //   be represented by FunctionTypeBitfields.FastTypeQuals. Present if and only
   //   if hasExtQualifiers() is true.
   //
   // The optional FunctionTypeExtraBitfields has to be before the data
   // related to the exception specification since it contains the number
   // of exception types.
   //
   // We put the ExtParameterInfos last.  If all were equal, it would make
   // more sense to put these before the exception specification, because
   // it's much easier to skip past them compared to the elaborate switch
   // required to skip the exception specification.  However, all is not
   // equal; ExtParameterInfos are used to model very uncommon features,
   // and it's better not to burden the more common paths.
 
 public:
   /// Holds information about the various types of exception specification.
   /// ExceptionSpecInfo is not stored as such in FunctionProtoType but is
   /// used to group together the various bits of information about the
   /// exception specification.
   struct ExceptionSpecInfo {
     /// The kind of exception specification this is.
     ExceptionSpecificationType Type = EST_None;
 
     /// Explicitly-specified list of exception types.
     ArrayRef<QualType> Exceptions;
 
     /// Noexcept expression, if this is a computed noexcept specification.
     Expr *NoexceptExpr = nullptr;
 
     /// The function whose exception specification this is, for
     /// EST_Unevaluated and EST_Uninstantiated.
     FunctionDecl *SourceDecl = nullptr;
 
     /// The function template whose exception specification this is instantiated
     /// from, for EST_Uninstantiated.
     FunctionDecl *SourceTemplate = nullptr;
 
     ExceptionSpecInfo() = default;
 
     ExceptionSpecInfo(ExceptionSpecificationType EST) : Type(EST) {}
   };
 
   /// Extra information about a function prototype. ExtProtoInfo is not
   /// stored as such in FunctionProtoType but is used to group together
   /// the various bits of extra information about a function prototype.
   struct ExtProtoInfo {
     FunctionType::ExtInfo ExtInfo;
     bool Variadic : 1;
     bool HasTrailingReturn : 1;
     Qualifiers TypeQuals;
     RefQualifierKind RefQualifier = RQ_None;
     ExceptionSpecInfo ExceptionSpec;
     const ExtParameterInfo *ExtParameterInfos = nullptr;
 
     ExtProtoInfo() : Variadic(false), HasTrailingReturn(false) {}
 
     ExtProtoInfo(CallingConv CC)
         : ExtInfo(CC), Variadic(false), HasTrailingReturn(false) {}
 
     ExtProtoInfo withExceptionSpec(const ExceptionSpecInfo &ESI) {
       ExtProtoInfo Result(*this);
       Result.ExceptionSpec = ESI;
       return Result;
     }
   };
 
 private:
   unsigned numTrailingObjects(OverloadToken<QualType>) const {
     return getNumParams();
   }
 
   unsigned numTrailingObjects(OverloadToken<FunctionTypeExtraBitfields>) const {
     return hasExtraBitfields();
   }
 
   unsigned numTrailingObjects(OverloadToken<ExceptionType>) const {
     return getExceptionSpecSize().NumExceptionType;
   }
 
   unsigned numTrailingObjects(OverloadToken<Expr *>) const {
     return getExceptionSpecSize().NumExprPtr;
   }
 
   unsigned numTrailingObjects(OverloadToken<FunctionDecl *>) const {
     return getExceptionSpecSize().NumFunctionDeclPtr;
   }
 
   unsigned numTrailingObjects(OverloadToken<ExtParameterInfo>) const {
     return hasExtParameterInfos() ? getNumParams() : 0;
   }
 
   /// Determine whether there are any argument types that
   /// contain an unexpanded parameter pack.
   static bool containsAnyUnexpandedParameterPack(const QualType *ArgArray,
                                                  unsigned numArgs) {
     for (unsigned Idx = 0; Idx < numArgs; ++Idx)
       if (ArgArray[Idx]->containsUnexpandedParameterPack())
         return true;
 
     return false;
   }
 
   FunctionProtoType(QualType result, ArrayRef<QualType> params,
                     QualType canonical, const ExtProtoInfo &epi);
 
   /// This struct is returned by getExceptionSpecSize and is used to
   /// translate an ExceptionSpecificationType to the number and kind
   /// of trailing objects related to the exception specification.
   struct ExceptionSpecSizeHolder {
     unsigned NumExceptionType;
     unsigned NumExprPtr;
     unsigned NumFunctionDeclPtr;
   };
 
   /// Return the number and kind of trailing objects
   /// related to the exception specification.
   static ExceptionSpecSizeHolder
   getExceptionSpecSize(ExceptionSpecificationType EST, unsigned NumExceptions) {
     switch (EST) {
     case EST_None:
     case EST_DynamicNone:
     case EST_MSAny:
     case EST_BasicNoexcept:
     case EST_Unparsed:
       return {0, 0, 0};
 
     case EST_Dynamic:
       return {NumExceptions, 0, 0};
 
     case EST_DependentNoexcept:
     case EST_NoexceptFalse:
     case EST_NoexceptTrue:
       return {0, 1, 0};
 
     case EST_Uninstantiated:
       return {0, 0, 2};
 
     case EST_Unevaluated:
       return {0, 0, 1};
     }
     llvm_unreachable("bad exception specification kind");
   }
 
   /// Return the number and kind of trailing objects
   /// related to the exception specification.
   ExceptionSpecSizeHolder getExceptionSpecSize() const {
     return getExceptionSpecSize(getExceptionSpecType(), getNumExceptions());
   }
 
   /// Whether the trailing FunctionTypeExtraBitfields is present.
   static bool hasExtraBitfields(ExceptionSpecificationType EST) {
     // If the exception spec type is EST_Dynamic then we have > 0 exception
     // types and the exact number is stored in FunctionTypeExtraBitfields.
     return EST == EST_Dynamic;
   }
 
   /// Whether the trailing FunctionTypeExtraBitfields is present.
   bool hasExtraBitfields() const {
     return hasExtraBitfields(getExceptionSpecType());
   }
 
   bool hasExtQualifiers() const {
     return FunctionTypeBits.HasExtQuals;
   }
 
 public:
   unsigned getNumParams() const { return FunctionTypeBits.NumParams; }
 
   QualType getParamType(unsigned i) const {
     assert(i < getNumParams() && "invalid parameter index");
     return param_type_begin()[i];
   }
 
   ArrayRef<QualType> getParamTypes() const {
     return llvm::makeArrayRef(param_type_begin(), param_type_end());
   }
 
   ExtProtoInfo getExtProtoInfo() const {
     ExtProtoInfo EPI;
     EPI.ExtInfo = getExtInfo();
     EPI.Variadic = isVariadic();
     EPI.HasTrailingReturn = hasTrailingReturn();
     EPI.ExceptionSpec.Type = getExceptionSpecType();
     EPI.TypeQuals = getTypeQuals();
     EPI.RefQualifier = getRefQualifier();
     if (EPI.ExceptionSpec.Type == EST_Dynamic) {
       EPI.ExceptionSpec.Exceptions = exceptions();
     } else if (isComputedNoexcept(EPI.ExceptionSpec.Type)) {
       EPI.ExceptionSpec.NoexceptExpr = getNoexceptExpr();
     } else if (EPI.ExceptionSpec.Type == EST_Uninstantiated) {
       EPI.ExceptionSpec.SourceDecl = getExceptionSpecDecl();
       EPI.ExceptionSpec.SourceTemplate = getExceptionSpecTemplate();
     } else if (EPI.ExceptionSpec.Type == EST_Unevaluated) {
       EPI.ExceptionSpec.SourceDecl = getExceptionSpecDecl();
     }
     EPI.ExtParameterInfos = getExtParameterInfosOrNull();
     return EPI;
   }
 
   /// Get the kind of exception specification on this function.
   ExceptionSpecificationType getExceptionSpecType() const {
     return static_cast<ExceptionSpecificationType>(
         FunctionTypeBits.ExceptionSpecType);
   }
 
   /// Return whether this function has any kind of exception spec.
   bool hasExceptionSpec() const { return getExceptionSpecType() != EST_None; }
 
   /// Return whether this function has a dynamic (throw) exception spec.
   bool hasDynamicExceptionSpec() const {
     return isDynamicExceptionSpec(getExceptionSpecType());
   }
 
   /// Return whether this function has a noexcept exception spec.
   bool hasNoexceptExceptionSpec() const {
     return isNoexceptExceptionSpec(getExceptionSpecType());
   }
 
   /// Return whether this function has a dependent exception spec.
   bool hasDependentExceptionSpec() const;
 
   /// Return whether this function has an instantiation-dependent exception
   /// spec.
   bool hasInstantiationDependentExceptionSpec() const;
 
   /// Return the number of types in the exception specification.
   unsigned getNumExceptions() const {
     return getExceptionSpecType() == EST_Dynamic
                ? getTrailingObjects<FunctionTypeExtraBitfields>()
                      ->NumExceptionType
                : 0;
   }
 
   /// Return the ith exception type, where 0 <= i < getNumExceptions().
   QualType getExceptionType(unsigned i) const {
     assert(i < getNumExceptions() && "Invalid exception number!");
     return exception_begin()[i];
   }
 
   /// Return the expression inside noexcept(expression), or a null pointer
   /// if there is none (because the exception spec is not of this form).
   Expr *getNoexceptExpr() const {
     if (!isComputedNoexcept(getExceptionSpecType()))
       return nullptr;
     return *getTrailingObjects<Expr *>();
   }
 
   /// If this function type has an exception specification which hasn't
   /// been determined yet (either because it has not been evaluated or because
   /// it has not been instantiated), this is the function whose exception
   /// specification is represented by this type.
   FunctionDecl *getExceptionSpecDecl() const {
     if (getExceptionSpecType() != EST_Uninstantiated &&
         getExceptionSpecType() != EST_Unevaluated)
       return nullptr;
     return getTrailingObjects<FunctionDecl *>()[0];
   }
 
   /// If this function type has an uninstantiated exception
   /// specification, this is the function whose exception specification
   /// should be instantiated to find the exception specification for
   /// this type.
   FunctionDecl *getExceptionSpecTemplate() const {
     if (getExceptionSpecType() != EST_Uninstantiated)
       return nullptr;
     return getTrailingObjects<FunctionDecl *>()[1];
   }
 
   /// Determine whether this function type has a non-throwing exception
   /// specification.
   CanThrowResult canThrow() const;
 
   /// Determine whether this function type has a non-throwing exception
   /// specification. If this depends on template arguments, returns
   /// \c ResultIfDependent.
   bool isNothrow(bool ResultIfDependent = false) const {
     return ResultIfDependent ? canThrow() != CT_Can : canThrow() == CT_Cannot;
   }
 
   /// Whether this function prototype is variadic.
   bool isVariadic() const { return FunctionTypeBits.Variadic; }
 
   /// Determines whether this function prototype contains a
   /// parameter pack at the end.
   ///
   /// A function template whose last parameter is a parameter pack can be
   /// called with an arbitrary number of arguments, much like a variadic
   /// function.
   bool isTemplateVariadic() const;
 
   /// Whether this function prototype has a trailing return type.
   bool hasTrailingReturn() const { return FunctionTypeBits.HasTrailingReturn; }
 
   Qualifiers getTypeQuals() const {
     if (hasExtQualifiers())
       return *getTrailingObjects<Qualifiers>();
     else
       return getFastTypeQuals();
   }
 
   /// Retrieve the ref-qualifier associated with this function type.
   RefQualifierKind getRefQualifier() const {
     return static_cast<RefQualifierKind>(FunctionTypeBits.RefQualifier);
   }
 
   using param_type_iterator = const QualType *;
   using param_type_range = llvm::iterator_range<param_type_iterator>;
 
   param_type_range param_types() const {
     return param_type_range(param_type_begin(), param_type_end());
   }
 
   param_type_iterator param_type_begin() const {
     return getTrailingObjects<QualType>();
   }
 
   param_type_iterator param_type_end() const {
     return param_type_begin() + getNumParams();
   }
 
   using exception_iterator = const QualType *;
 
   ArrayRef<QualType> exceptions() const {
     return llvm::makeArrayRef(exception_begin(), exception_end());
   }
 
   exception_iterator exception_begin() const {
     return reinterpret_cast<exception_iterator>(
         getTrailingObjects<ExceptionType>());
   }
 
   exception_iterator exception_end() const {
     return exception_begin() + getNumExceptions();
   }
 
   /// Is there any interesting extra information for any of the parameters
   /// of this function type?
   bool hasExtParameterInfos() const {
     return FunctionTypeBits.HasExtParameterInfos;
   }
 
   ArrayRef<ExtParameterInfo> getExtParameterInfos() const {
     assert(hasExtParameterInfos());
     return ArrayRef<ExtParameterInfo>(getTrailingObjects<ExtParameterInfo>(),
                                       getNumParams());
   }
 
   /// Return a pointer to the beginning of the array of extra parameter
   /// information, if present, or else null if none of the parameters
   /// carry it.  This is equivalent to getExtProtoInfo().ExtParameterInfos.
   const ExtParameterInfo *getExtParameterInfosOrNull() const {
     if (!hasExtParameterInfos())
       return nullptr;
     return getTrailingObjects<ExtParameterInfo>();
   }
 
   ExtParameterInfo getExtParameterInfo(unsigned I) const {
     assert(I < getNumParams() && "parameter index out of range");
     if (hasExtParameterInfos())
       return getTrailingObjects<ExtParameterInfo>()[I];
     return ExtParameterInfo();
   }
 
   ParameterABI getParameterABI(unsigned I) const {
     assert(I < getNumParams() && "parameter index out of range");
     if (hasExtParameterInfos())
       return getTrailingObjects<ExtParameterInfo>()[I].getABI();
     return ParameterABI::Ordinary;
   }
 
   bool isParamConsumed(unsigned I) const {
     assert(I < getNumParams() && "parameter index out of range");
     if (hasExtParameterInfos())
       return getTrailingObjects<ExtParameterInfo>()[I].isConsumed();
     return false;
   }
 
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   void printExceptionSpecification(raw_ostream &OS,
                                    const PrintingPolicy &Policy) const;
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == FunctionProto;
   }
 
   void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &Ctx);
   static void Profile(llvm::FoldingSetNodeID &ID, QualType Result,
                       param_type_iterator ArgTys, unsigned NumArgs,
                       const ExtProtoInfo &EPI, const ASTContext &Context,
                       bool Canonical);
 };
 
 /// Represents the dependent type named by a dependently-scoped
 /// typename using declaration, e.g.
 ///   using typename Base<T>::foo;
 ///
 /// Template instantiation turns these into the underlying type.
 class UnresolvedUsingType : public Type {
   friend class ASTContext; // ASTContext creates these.
 
   UnresolvedUsingTypenameDecl *Decl;
 
   UnresolvedUsingType(const UnresolvedUsingTypenameDecl *D)
       : Type(UnresolvedUsing, QualType(), true, true, false,
              /*ContainsUnexpandedParameterPack=*/false),
         Decl(const_cast<UnresolvedUsingTypenameDecl*>(D)) {}
 
 public:
   UnresolvedUsingTypenameDecl *getDecl() const { return Decl; }
 
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == UnresolvedUsing;
   }
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     return Profile(ID, Decl);
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID,
                       UnresolvedUsingTypenameDecl *D) {
     ID.AddPointer(D);
   }
 };
 
 class TypedefType : public Type {
   TypedefNameDecl *Decl;
 
 protected:
   friend class ASTContext; // ASTContext creates these.
 
   TypedefType(TypeClass tc, const TypedefNameDecl *D, QualType can)
       : Type(tc, can, can->isDependentType(),
              can->isInstantiationDependentType(),
              can->isVariablyModifiedType(),
              /*ContainsUnexpandedParameterPack=*/false),
         Decl(const_cast<TypedefNameDecl*>(D)) {
     assert(!isa<TypedefType>(can) && "Invalid canonical type");
   }
 
 public:
   TypedefNameDecl *getDecl() const { return Decl; }
 
   bool isSugared() const { return true; }
   QualType desugar() const;
 
   static bool classof(const Type *T) { return T->getTypeClass() == Typedef; }
 };
 
 /// Represents a `typeof` (or __typeof__) expression (a GCC extension).
 class TypeOfExprType : public Type {
   Expr *TOExpr;
 
 protected:
   friend class ASTContext; // ASTContext creates these.
 
   TypeOfExprType(Expr *E, QualType can = QualType());
 
 public:
   Expr *getUnderlyingExpr() const { return TOExpr; }
 
   /// Remove a single level of sugar.
   QualType desugar() const;
 
   /// Returns whether this type directly provides sugar.
   bool isSugared() const;
 
   static bool classof(const Type *T) { return T->getTypeClass() == TypeOfExpr; }
 };
 
 /// Internal representation of canonical, dependent
 /// `typeof(expr)` types.
 ///
 /// This class is used internally by the ASTContext to manage
 /// canonical, dependent types, only. Clients will only see instances
 /// of this class via TypeOfExprType nodes.
 class DependentTypeOfExprType
   : public TypeOfExprType, public llvm::FoldingSetNode {
   const ASTContext &Context;
 
 public:
   DependentTypeOfExprType(const ASTContext &Context, Expr *E)
       : TypeOfExprType(E), Context(Context) {}
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, Context, getUnderlyingExpr());
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &Context,
                       Expr *E);
 };
 
 /// Represents `typeof(type)`, a GCC extension.
 class TypeOfType : public Type {
   friend class ASTContext; // ASTContext creates these.
 
   QualType TOType;
 
   TypeOfType(QualType T, QualType can)
       : Type(TypeOf, can, T->isDependentType(),
              T->isInstantiationDependentType(),
              T->isVariablyModifiedType(),
              T->containsUnexpandedParameterPack()),
         TOType(T) {
     assert(!isa<TypedefType>(can) && "Invalid canonical type");
   }
 
 public:
   QualType getUnderlyingType() const { return TOType; }
 
   /// Remove a single level of sugar.
   QualType desugar() const { return getUnderlyingType(); }
 
   /// Returns whether this type directly provides sugar.
   bool isSugared() const { return true; }
 
   static bool classof(const Type *T) { return T->getTypeClass() == TypeOf; }
 };
 
 /// Represents the type `decltype(expr)` (C++11).
 class DecltypeType : public Type {
   Expr *E;
   QualType UnderlyingType;
 
 protected:
   friend class ASTContext; // ASTContext creates these.
 
   DecltypeType(Expr *E, QualType underlyingType, QualType can = QualType());
 
 public:
   Expr *getUnderlyingExpr() const { return E; }
   QualType getUnderlyingType() const { return UnderlyingType; }
 
   /// Remove a single level of sugar.
   QualType desugar() const;
 
   /// Returns whether this type directly provides sugar.
   bool isSugared() const;
 
   static bool classof(const Type *T) { return T->getTypeClass() == Decltype; }
 };
 
 /// Internal representation of canonical, dependent
 /// decltype(expr) types.
 ///
 /// This class is used internally by the ASTContext to manage
 /// canonical, dependent types, only. Clients will only see instances
 /// of this class via DecltypeType nodes.
 class DependentDecltypeType : public DecltypeType, public llvm::FoldingSetNode {
   const ASTContext &Context;
 
 public:
   DependentDecltypeType(const ASTContext &Context, Expr *E);
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, Context, getUnderlyingExpr());
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &Context,
                       Expr *E);
 };
 
 /// A unary type transform, which is a type constructed from another.
 class UnaryTransformType : public Type {
 public:
   enum UTTKind {
     EnumUnderlyingType
   };
 
 private:
   /// The untransformed type.
   QualType BaseType;
 
   /// The transformed type if not dependent, otherwise the same as BaseType.
   QualType UnderlyingType;
 
   UTTKind UKind;
 
 protected:
   friend class ASTContext;
 
   UnaryTransformType(QualType BaseTy, QualType UnderlyingTy, UTTKind UKind,
                      QualType CanonicalTy);
 
 public:
   bool isSugared() const { return !isDependentType(); }
   QualType desugar() const { return UnderlyingType; }
 
   QualType getUnderlyingType() const { return UnderlyingType; }
   QualType getBaseType() const { return BaseType; }
 
   UTTKind getUTTKind() const { return UKind; }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == UnaryTransform;
   }
 };
 
 /// Internal representation of canonical, dependent
 /// __underlying_type(type) types.
 ///
 /// This class is used internally by the ASTContext to manage
 /// canonical, dependent types, only. Clients will only see instances
 /// of this class via UnaryTransformType nodes.
 class DependentUnaryTransformType : public UnaryTransformType,
                                     public llvm::FoldingSetNode {
 public:
   DependentUnaryTransformType(const ASTContext &C, QualType BaseType,
                               UTTKind UKind);
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, getBaseType(), getUTTKind());
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, QualType BaseType,
                       UTTKind UKind) {
     ID.AddPointer(BaseType.getAsOpaquePtr());
     ID.AddInteger((unsigned)UKind);
   }
 };
 
 class TagType : public Type {
   friend class ASTReader;
 
   /// Stores the TagDecl associated with this type. The decl may point to any
   /// TagDecl that declares the entity.
   TagDecl *decl;
 
 protected:
   TagType(TypeClass TC, const TagDecl *D, QualType can);
 
 public:
   TagDecl *getDecl() const;
 
   /// Determines whether this type is in the process of being defined.
   bool isBeingDefined() const;
 
   static bool classof(const Type *T) {
     return T->getTypeClass() >= TagFirst && T->getTypeClass() <= TagLast;
   }
 };
 
 /// A helper class that allows the use of isa/cast/dyncast
 /// to detect TagType objects of structs/unions/classes.
 class RecordType : public TagType {
 protected:
   friend class ASTContext; // ASTContext creates these.
 
   explicit RecordType(const RecordDecl *D)
       : TagType(Record, reinterpret_cast<const TagDecl*>(D), QualType()) {}
   explicit RecordType(TypeClass TC, RecordDecl *D)
       : TagType(TC, reinterpret_cast<const TagDecl*>(D), QualType()) {}
 
 public:
   RecordDecl *getDecl() const {
     return reinterpret_cast<RecordDecl*>(TagType::getDecl());
   }
 
   /// Recursively check all fields in the record for const-ness. If any field
   /// is declared const, return true. Otherwise, return false.
   bool hasConstFields() const;
 
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   static bool classof(const Type *T) { return T->getTypeClass() == Record; }
 };
 
 /// A helper class that allows the use of isa/cast/dyncast
 /// to detect TagType objects of enums.
 class EnumType : public TagType {
   friend class ASTContext; // ASTContext creates these.
 
   explicit EnumType(const EnumDecl *D)
       : TagType(Enum, reinterpret_cast<const TagDecl*>(D), QualType()) {}
 
 public:
   EnumDecl *getDecl() const {
     return reinterpret_cast<EnumDecl*>(TagType::getDecl());
   }
 
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   static bool classof(const Type *T) { return T->getTypeClass() == Enum; }
 };
 
 /// An attributed type is a type to which a type attribute has been applied.
 ///
 /// The "modified type" is the fully-sugared type to which the attributed
 /// type was applied; generally it is not canonically equivalent to the
 /// attributed type. The "equivalent type" is the minimally-desugared type
 /// which the type is canonically equivalent to.
 ///
 /// For example, in the following attributed type:
 ///     int32_t __attribute__((vector_size(16)))
 ///   - the modified type is the TypedefType for int32_t
 ///   - the equivalent type is VectorType(16, int32_t)
 ///   - the canonical type is VectorType(16, int)
 class AttributedType : public Type, public llvm::FoldingSetNode {
 public:
   using Kind = attr::Kind;
 
 private:
   friend class ASTContext; // ASTContext creates these
 
   QualType ModifiedType;
   QualType EquivalentType;
 
   AttributedType(QualType canon, attr::Kind attrKind, QualType modified,
                  QualType equivalent)
       : Type(Attributed, canon, equivalent->isDependentType(),
              equivalent->isInstantiationDependentType(),
              equivalent->isVariablyModifiedType(),
              equivalent->containsUnexpandedParameterPack()),
         ModifiedType(modified), EquivalentType(equivalent) {
     AttributedTypeBits.AttrKind = attrKind;
   }
 
 public:
   Kind getAttrKind() const {
     return static_cast<Kind>(AttributedTypeBits.AttrKind);
   }
 
   QualType getModifiedType() const { return ModifiedType; }
   QualType getEquivalentType() const { return EquivalentType; }
 
   bool isSugared() const { return true; }
   QualType desugar() const { return getEquivalentType(); }
 
   /// Does this attribute behave like a type qualifier?
   ///
   /// A type qualifier adjusts a type to provide specialized rules for
   /// a specific object, like the standard const and volatile qualifiers.
   /// This includes attributes controlling things like nullability,
   /// address spaces, and ARC ownership.  The value of the object is still
   /// largely described by the modified type.
   ///
   /// In contrast, many type attributes "rewrite" their modified type to
   /// produce a fundamentally different type, not necessarily related in any
   /// formalizable way to the original type.  For example, calling convention
   /// and vector attributes are not simple type qualifiers.
   ///
   /// Type qualifiers are often, but not always, reflected in the canonical
   /// type.
   bool isQualifier() const;
 
   bool isMSTypeSpec() const;
 
   bool isCallingConv() const;
 
   llvm::Optional<NullabilityKind> getImmediateNullability() const;
 
   /// Retrieve the attribute kind corresponding to the given
   /// nullability kind.
   static Kind getNullabilityAttrKind(NullabilityKind kind) {
     switch (kind) {
     case NullabilityKind::NonNull:
       return attr::TypeNonNull;
 
     case NullabilityKind::Nullable:
       return attr::TypeNullable;
 
     case NullabilityKind::Unspecified:
       return attr::TypeNullUnspecified;
     }
     llvm_unreachable("Unknown nullability kind.");
   }
 
   /// Strip off the top-level nullability annotation on the given
   /// type, if it's there.
   ///
   /// \param T The type to strip. If the type is exactly an
   /// AttributedType specifying nullability (without looking through
   /// type sugar), the nullability is returned and this type changed
   /// to the underlying modified type.
   ///
   /// \returns the top-level nullability, if present.
   static Optional<NullabilityKind> stripOuterNullability(QualType &T);
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, getAttrKind(), ModifiedType, EquivalentType);
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, Kind attrKind,
                       QualType modified, QualType equivalent) {
     ID.AddInteger(attrKind);
     ID.AddPointer(modified.getAsOpaquePtr());
     ID.AddPointer(equivalent.getAsOpaquePtr());
   }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == Attributed;
   }
 };
 
 class TemplateTypeParmType : public Type, public llvm::FoldingSetNode {
   friend class ASTContext; // ASTContext creates these
 
   // Helper data collector for canonical types.
   struct CanonicalTTPTInfo {
     unsigned Depth : 15;
     unsigned ParameterPack : 1;
     unsigned Index : 16;
   };
 
   union {
     // Info for the canonical type.
     CanonicalTTPTInfo CanTTPTInfo;
 
     // Info for the non-canonical type.
     TemplateTypeParmDecl *TTPDecl;
   };
 
   /// Build a non-canonical type.
   TemplateTypeParmType(TemplateTypeParmDecl *TTPDecl, QualType Canon)
       : Type(TemplateTypeParm, Canon, /*Dependent=*/true,
              /*InstantiationDependent=*/true,
              /*VariablyModified=*/false,
              Canon->containsUnexpandedParameterPack()),
         TTPDecl(TTPDecl) {}
 
   /// Build the canonical type.
   TemplateTypeParmType(unsigned D, unsigned I, bool PP)
       : Type(TemplateTypeParm, QualType(this, 0),
              /*Dependent=*/true,
              /*InstantiationDependent=*/true,
              /*VariablyModified=*/false, PP) {
     CanTTPTInfo.Depth = D;
     CanTTPTInfo.Index = I;
     CanTTPTInfo.ParameterPack = PP;
   }
 
   const CanonicalTTPTInfo& getCanTTPTInfo() const {
     QualType Can = getCanonicalTypeInternal();
     return Can->castAs<TemplateTypeParmType>()->CanTTPTInfo;
   }
 
 public:
   unsigned getDepth() const { return getCanTTPTInfo().Depth; }
   unsigned getIndex() const { return getCanTTPTInfo().Index; }
   bool isParameterPack() const { return getCanTTPTInfo().ParameterPack; }
 
   TemplateTypeParmDecl *getDecl() const {
     return isCanonicalUnqualified() ? nullptr : TTPDecl;
   }
 
   IdentifierInfo *getIdentifier() const;
 
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, getDepth(), getIndex(), isParameterPack(), getDecl());
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, unsigned Depth,
                       unsigned Index, bool ParameterPack,
                       TemplateTypeParmDecl *TTPDecl) {
     ID.AddInteger(Depth);
     ID.AddInteger(Index);
     ID.AddBoolean(ParameterPack);
     ID.AddPointer(TTPDecl);
   }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == TemplateTypeParm;
   }
 };
 
 /// Represents the result of substituting a type for a template
 /// type parameter.
 ///
 /// Within an instantiated template, all template type parameters have
 /// been replaced with these.  They are used solely to record that a
 /// type was originally written as a template type parameter;
 /// therefore they are never canonical.
 class SubstTemplateTypeParmType : public Type, public llvm::FoldingSetNode {
   friend class ASTContext;
 
   // The original type parameter.
   const TemplateTypeParmType *Replaced;
 
   SubstTemplateTypeParmType(const TemplateTypeParmType *Param, QualType Canon)
       : Type(SubstTemplateTypeParm, Canon, Canon->isDependentType(),
              Canon->isInstantiationDependentType(),
              Canon->isVariablyModifiedType(),
              Canon->containsUnexpandedParameterPack()),
         Replaced(Param) {}
 
 public:
   /// Gets the template parameter that was substituted for.
   const TemplateTypeParmType *getReplacedParameter() const {
     return Replaced;
   }
 
   /// Gets the type that was substituted for the template
   /// parameter.
   QualType getReplacementType() const {
     return getCanonicalTypeInternal();
   }
 
   bool isSugared() const { return true; }
   QualType desugar() const { return getReplacementType(); }
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, getReplacedParameter(), getReplacementType());
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID,
                       const TemplateTypeParmType *Replaced,
                       QualType Replacement) {
     ID.AddPointer(Replaced);
     ID.AddPointer(Replacement.getAsOpaquePtr());
   }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == SubstTemplateTypeParm;
   }
 };
 
 /// Represents the result of substituting a set of types for a template
 /// type parameter pack.
 ///
 /// When a pack expansion in the source code contains multiple parameter packs
 /// and those parameter packs correspond to different levels of template
 /// parameter lists, this type node is used to represent a template type
 /// parameter pack from an outer level, which has already had its argument pack
 /// substituted but that still lives within a pack expansion that itself
 /// could not be instantiated. When actually performing a substitution into
 /// that pack expansion (e.g., when all template parameters have corresponding
 /// arguments), this type will be replaced with the \c SubstTemplateTypeParmType
 /// at the current pack substitution index.
 class SubstTemplateTypeParmPackType : public Type, public llvm::FoldingSetNode {
   friend class ASTContext;
 
   /// The original type parameter.
   const TemplateTypeParmType *Replaced;
 
   /// A pointer to the set of template arguments that this
   /// parameter pack is instantiated with.
   const TemplateArgument *Arguments;
 
   SubstTemplateTypeParmPackType(const TemplateTypeParmType *Param,
                                 QualType Canon,
                                 const TemplateArgument &ArgPack);
 
 public:
   IdentifierInfo *getIdentifier() const { return Replaced->getIdentifier(); }
 
   /// Gets the template parameter that was substituted for.
   const TemplateTypeParmType *getReplacedParameter() const {
     return Replaced;
   }
 
   unsigned getNumArgs() const {
     return SubstTemplateTypeParmPackTypeBits.NumArgs;
   }
 
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   TemplateArgument getArgumentPack() const;
 
   void Profile(llvm::FoldingSetNodeID &ID);
   static void Profile(llvm::FoldingSetNodeID &ID,
                       const TemplateTypeParmType *Replaced,
                       const TemplateArgument &ArgPack);
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == SubstTemplateTypeParmPack;
   }
 };
 
 /// Common base class for placeholders for types that get replaced by
 /// placeholder type deduction: C++11 auto, C++14 decltype(auto), C++17 deduced
 /// class template types, and (eventually) constrained type names from the C++
 /// Concepts TS.
 ///
 /// These types are usually a placeholder for a deduced type. However, before
 /// the initializer is attached, or (usually) if the initializer is
 /// type-dependent, there is no deduced type and the type is canonical. In
 /// the latter case, it is also a dependent type.
 class DeducedType : public Type {
 protected:
   DeducedType(TypeClass TC, QualType DeducedAsType, bool IsDependent,
               bool IsInstantiationDependent, bool ContainsParameterPack)
       : Type(TC,
              // FIXME: Retain the sugared deduced type?
              DeducedAsType.isNull() ? QualType(this, 0)
                                     : DeducedAsType.getCanonicalType(),
              IsDependent, IsInstantiationDependent,
              /*VariablyModified=*/false, ContainsParameterPack) {
     if (!DeducedAsType.isNull()) {
       if (DeducedAsType->isDependentType())
         setDependent();
       if (DeducedAsType->isInstantiationDependentType())
         setInstantiationDependent();
       if (DeducedAsType->containsUnexpandedParameterPack())
         setContainsUnexpandedParameterPack();
     }
   }
 
 public:
   bool isSugared() const { return !isCanonicalUnqualified(); }
   QualType desugar() const { return getCanonicalTypeInternal(); }
 
   /// Get the type deduced for this placeholder type, or null if it's
   /// either not been deduced or was deduced to a dependent type.
   QualType getDeducedType() const {
     return !isCanonicalUnqualified() ? getCanonicalTypeInternal() : QualType();
   }
   bool isDeduced() const {
     return !isCanonicalUnqualified() || isDependentType();
   }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == Auto ||
            T->getTypeClass() == DeducedTemplateSpecialization;
   }
 };
 
 /// Represents a C++11 auto or C++14 decltype(auto) type.
 class AutoType : public DeducedType, public llvm::FoldingSetNode {
   friend class ASTContext; // ASTContext creates these
 
   AutoType(QualType DeducedAsType, AutoTypeKeyword Keyword,
            bool IsDeducedAsDependent)
       : DeducedType(Auto, DeducedAsType, IsDeducedAsDependent,
                     IsDeducedAsDependent, /*ContainsPack=*/false) {
     AutoTypeBits.Keyword = (unsigned)Keyword;
   }
 
 public:
   bool isDecltypeAuto() const {
     return getKeyword() == AutoTypeKeyword::DecltypeAuto;
   }
 
   AutoTypeKeyword getKeyword() const {
     return (AutoTypeKeyword)AutoTypeBits.Keyword;
   }
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, getDeducedType(), getKeyword(), isDependentType());
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, QualType Deduced,
                       AutoTypeKeyword Keyword, bool IsDependent) {
     ID.AddPointer(Deduced.getAsOpaquePtr());
     ID.AddInteger((unsigned)Keyword);
     ID.AddBoolean(IsDependent);
   }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == Auto;
   }
 };
 
 /// Represents a C++17 deduced template specialization type.
 class DeducedTemplateSpecializationType : public DeducedType,
                                           public llvm::FoldingSetNode {
   friend class ASTContext; // ASTContext creates these
 
   /// The name of the template whose arguments will be deduced.
   TemplateName Template;
 
   DeducedTemplateSpecializationType(TemplateName Template,
                                     QualType DeducedAsType,
                                     bool IsDeducedAsDependent)
       : DeducedType(DeducedTemplateSpecialization, DeducedAsType,
                     IsDeducedAsDependent || Template.isDependent(),
                     IsDeducedAsDependent || Template.isInstantiationDependent(),
                     Template.containsUnexpandedParameterPack()),
         Template(Template) {}
 
 public:
   /// Retrieve the name of the template that we are deducing.
   TemplateName getTemplateName() const { return Template;}
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, getTemplateName(), getDeducedType(), isDependentType());
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, TemplateName Template,
                       QualType Deduced, bool IsDependent) {
     Template.Profile(ID);
     ID.AddPointer(Deduced.getAsOpaquePtr());
     ID.AddBoolean(IsDependent);
   }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == DeducedTemplateSpecialization;
   }
 };
 
 /// Represents a type template specialization; the template
 /// must be a class template, a type alias template, or a template
 /// template parameter.  A template which cannot be resolved to one of
 /// these, e.g. because it is written with a dependent scope
 /// specifier, is instead represented as a
 /// @c DependentTemplateSpecializationType.
 ///
 /// A non-dependent template specialization type is always "sugar",
 /// typically for a \c RecordType.  For example, a class template
 /// specialization type of \c vector<int> will refer to a tag type for
 /// the instantiation \c std::vector<int, std::allocator<int>>
 ///
 /// Template specializations are dependent if either the template or
 /// any of the template arguments are dependent, in which case the
 /// type may also be canonical.
 ///
 /// Instances of this type are allocated with a trailing array of
 /// TemplateArguments, followed by a QualType representing the
 /// non-canonical aliased type when the template is a type alias
 /// template.
 class alignas(8) TemplateSpecializationType
     : public Type,
       public llvm::FoldingSetNode {
   friend class ASTContext; // ASTContext creates these
 
   /// The name of the template being specialized.  This is
   /// either a TemplateName::Template (in which case it is a
   /// ClassTemplateDecl*, a TemplateTemplateParmDecl*, or a
   /// TypeAliasTemplateDecl*), a
   /// TemplateName::SubstTemplateTemplateParmPack, or a
   /// TemplateName::SubstTemplateTemplateParm (in which case the
   /// replacement must, recursively, be one of these).
   TemplateName Template;
 
   TemplateSpecializationType(TemplateName T,
                              ArrayRef<TemplateArgument> Args,
                              QualType Canon,
                              QualType Aliased);
 
 public:
   /// Determine whether any of the given template arguments are dependent.
   static bool anyDependentTemplateArguments(ArrayRef<TemplateArgumentLoc> Args,
                                             bool &InstantiationDependent);
 
   static bool anyDependentTemplateArguments(const TemplateArgumentListInfo &,
                                             bool &InstantiationDependent);
 
   /// True if this template specialization type matches a current
   /// instantiation in the context in which it is found.
   bool isCurrentInstantiation() const {
     return isa<InjectedClassNameType>(getCanonicalTypeInternal());
   }
 
   /// Determine if this template specialization type is for a type alias
   /// template that has been substituted.
   ///
   /// Nearly every template specialization type whose template is an alias
   /// template will be substituted. However, this is not the case when
   /// the specialization contains a pack expansion but the template alias
   /// does not have a corresponding parameter pack, e.g.,
   ///
   /// \code
   /// template<typename T, typename U, typename V> struct S;
   /// template<typename T, typename U> using A = S<T, int, U>;
   /// template<typename... Ts> struct X {
   ///   typedef A<Ts...> type; // not a type alias
   /// };
   /// \endcode
   bool isTypeAlias() const { return TemplateSpecializationTypeBits.TypeAlias; }
 
   /// Get the aliased type, if this is a specialization of a type alias
   /// template.
   QualType getAliasedType() const {
     assert(isTypeAlias() && "not a type alias template specialization");
     return *reinterpret_cast<const QualType*>(end());
   }
 
   using iterator = const TemplateArgument *;
 
   iterator begin() const { return getArgs(); }
   iterator end() const; // defined inline in TemplateBase.h
 
   /// Retrieve the name of the template that we are specializing.
   TemplateName getTemplateName() const { return Template; }
 
   /// Retrieve the template arguments.
   const TemplateArgument *getArgs() const {
     return reinterpret_cast<const TemplateArgument *>(this + 1);
   }
 
   /// Retrieve the number of template arguments.
   unsigned getNumArgs() const {
     return TemplateSpecializationTypeBits.NumArgs;
   }
 
   /// Retrieve a specific template argument as a type.
   /// \pre \c isArgType(Arg)
   const TemplateArgument &getArg(unsigned Idx) const; // in TemplateBase.h
 
   ArrayRef<TemplateArgument> template_arguments() const {
     return {getArgs(), getNumArgs()};
   }
 
   bool isSugared() const {
     return !isDependentType() || isCurrentInstantiation() || isTypeAlias();
   }
 
   QualType desugar() const {
     return isTypeAlias() ? getAliasedType() : getCanonicalTypeInternal();
   }
 
   void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &Ctx) {
     Profile(ID, Template, template_arguments(), Ctx);
     if (isTypeAlias())
       getAliasedType().Profile(ID);
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, TemplateName T,
                       ArrayRef<TemplateArgument> Args,
                       const ASTContext &Context);
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == TemplateSpecialization;
   }
 };
 
 /// Print a template argument list, including the '<' and '>'
 /// enclosing the template arguments.
 void printTemplateArgumentList(raw_ostream &OS,
                                ArrayRef<TemplateArgument> Args,
                                const PrintingPolicy &Policy);
 
 void printTemplateArgumentList(raw_ostream &OS,
                                ArrayRef<TemplateArgumentLoc> Args,
                                const PrintingPolicy &Policy);
 
 void printTemplateArgumentList(raw_ostream &OS,
                                const TemplateArgumentListInfo &Args,
                                const PrintingPolicy &Policy);
 
 /// The injected class name of a C++ class template or class
 /// template partial specialization.  Used to record that a type was
 /// spelled with a bare identifier rather than as a template-id; the
 /// equivalent for non-templated classes is just RecordType.
 ///
 /// Injected class name types are always dependent.  Template
 /// instantiation turns these into RecordTypes.
 ///
 /// Injected class name types are always canonical.  This works
 /// because it is impossible to compare an injected class name type
 /// with the corresponding non-injected template type, for the same
 /// reason that it is impossible to directly compare template
 /// parameters from different dependent contexts: injected class name
 /// types can only occur within the scope of a particular templated
 /// declaration, and within that scope every template specialization
 /// will canonicalize to the injected class name (when appropriate
 /// according to the rules of the language).
 class InjectedClassNameType : public Type {
   friend class ASTContext; // ASTContext creates these.
   friend class ASTNodeImporter;
   friend class ASTReader; // FIXME: ASTContext::getInjectedClassNameType is not
                           // currently suitable for AST reading, too much
                           // interdependencies.
 
   CXXRecordDecl *Decl;
 
   /// The template specialization which this type represents.
   /// For example, in
   ///   template <class T> class A { ... };
   /// this is A<T>, whereas in
   ///   template <class X, class Y> class A<B<X,Y> > { ... };
   /// this is A<B<X,Y> >.
   ///
   /// It is always unqualified, always a template specialization type,
   /// and always dependent.
   QualType InjectedType;
 
   InjectedClassNameType(CXXRecordDecl *D, QualType TST)
       : Type(InjectedClassName, QualType(), /*Dependent=*/true,
              /*InstantiationDependent=*/true,
              /*VariablyModified=*/false,
              /*ContainsUnexpandedParameterPack=*/false),
         Decl(D), InjectedType(TST) {
     assert(isa<TemplateSpecializationType>(TST));
     assert(!TST.hasQualifiers());
     assert(TST->isDependentType());
   }
 
 public:
   QualType getInjectedSpecializationType() const { return InjectedType; }
 
   const TemplateSpecializationType *getInjectedTST() const {
     return cast<TemplateSpecializationType>(InjectedType.getTypePtr());
   }
 
   TemplateName getTemplateName() const {
     return getInjectedTST()->getTemplateName();
   }
 
   CXXRecordDecl *getDecl() const;
 
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == InjectedClassName;
   }
 };
 
 /// The kind of a tag type.
 enum TagTypeKind {
   /// The "struct" keyword.
   TTK_Struct,
 
   /// The "__interface" keyword.
   TTK_Interface,
 
   /// The "union" keyword.
   TTK_Union,
 
   /// The "class" keyword.
   TTK_Class,
 
   /// The "enum" keyword.
   TTK_Enum
 };
 
 /// The elaboration keyword that precedes a qualified type name or
 /// introduces an elaborated-type-specifier.
 enum ElaboratedTypeKeyword {
   /// The "struct" keyword introduces the elaborated-type-specifier.
   ETK_Struct,
 
   /// The "__interface" keyword introduces the elaborated-type-specifier.
   ETK_Interface,
 
   /// The "union" keyword introduces the elaborated-type-specifier.
   ETK_Union,
 
   /// The "class" keyword introduces the elaborated-type-specifier.
   ETK_Class,
 
   /// The "enum" keyword introduces the elaborated-type-specifier.
   ETK_Enum,
 
   /// The "typename" keyword precedes the qualified type name, e.g.,
   /// \c typename T::type.
   ETK_Typename,
 
   /// No keyword precedes the qualified type name.
   ETK_None
 };
 
 /// A helper class for Type nodes having an ElaboratedTypeKeyword.
 /// The keyword in stored in the free bits of the base class.
 /// Also provides a few static helpers for converting and printing
 /// elaborated type keyword and tag type kind enumerations.
 class TypeWithKeyword : public Type {
 protected:
   TypeWithKeyword(ElaboratedTypeKeyword Keyword, TypeClass tc,
                   QualType Canonical, bool Dependent,
                   bool InstantiationDependent, bool VariablyModified,
                   bool ContainsUnexpandedParameterPack)
       : Type(tc, Canonical, Dependent, InstantiationDependent, VariablyModified,
              ContainsUnexpandedParameterPack) {
     TypeWithKeywordBits.Keyword = Keyword;
   }
 
 public:
   ElaboratedTypeKeyword getKeyword() const {
     return static_cast<ElaboratedTypeKeyword>(TypeWithKeywordBits.Keyword);
   }
 
   /// Converts a type specifier (DeclSpec::TST) into an elaborated type keyword.
   static ElaboratedTypeKeyword getKeywordForTypeSpec(unsigned TypeSpec);
 
   /// Converts a type specifier (DeclSpec::TST) into a tag type kind.
   /// It is an error to provide a type specifier which *isn't* a tag kind here.
   static TagTypeKind getTagTypeKindForTypeSpec(unsigned TypeSpec);
 
   /// Converts a TagTypeKind into an elaborated type keyword.
   static ElaboratedTypeKeyword getKeywordForTagTypeKind(TagTypeKind Tag);
 
   /// Converts an elaborated type keyword into a TagTypeKind.
   /// It is an error to provide an elaborated type keyword
   /// which *isn't* a tag kind here.
   static TagTypeKind getTagTypeKindForKeyword(ElaboratedTypeKeyword Keyword);
 
   static bool KeywordIsTagTypeKind(ElaboratedTypeKeyword Keyword);
 
   static StringRef getKeywordName(ElaboratedTypeKeyword Keyword);
 
   static StringRef getTagTypeKindName(TagTypeKind Kind) {
     return getKeywordName(getKeywordForTagTypeKind(Kind));
   }
 
   class CannotCastToThisType {};
   static CannotCastToThisType classof(const Type *);
 };
 
 /// Represents a type that was referred to using an elaborated type
 /// keyword, e.g., struct S, or via a qualified name, e.g., N::M::type,
 /// or both.
 ///
 /// This type is used to keep track of a type name as written in the
 /// source code, including tag keywords and any nested-name-specifiers.
 /// The type itself is always "sugar", used to express what was written
 /// in the source code but containing no additional semantic information.
 class ElaboratedType final
     : public TypeWithKeyword,
       public llvm::FoldingSetNode,
       private llvm::TrailingObjects<ElaboratedType, TagDecl *> {
   friend class ASTContext; // ASTContext creates these
   friend TrailingObjects;
 
   /// The nested name specifier containing the qualifier.
   NestedNameSpecifier *NNS;
 
   /// The type that this qualified name refers to.
   QualType NamedType;
 
   /// The (re)declaration of this tag type owned by this occurrence is stored
   /// as a trailing object if there is one. Use getOwnedTagDecl to obtain
   /// it, or obtain a null pointer if there is none.
 
   ElaboratedType(ElaboratedTypeKeyword Keyword, NestedNameSpecifier *NNS,
                  QualType NamedType, QualType CanonType, TagDecl *OwnedTagDecl)
       : TypeWithKeyword(Keyword, Elaborated, CanonType,
                         NamedType->isDependentType(),
                         NamedType->isInstantiationDependentType(),
                         NamedType->isVariablyModifiedType(),
                         NamedType->containsUnexpandedParameterPack()),
         NNS(NNS), NamedType(NamedType) {
     ElaboratedTypeBits.HasOwnedTagDecl = false;
     if (OwnedTagDecl) {
       ElaboratedTypeBits.HasOwnedTagDecl = true;
       *getTrailingObjects<TagDecl *>() = OwnedTagDecl;
     }
     assert(!(Keyword == ETK_None && NNS == nullptr) &&
            "ElaboratedType cannot have elaborated type keyword "
            "and name qualifier both null.");
   }
 
 public:
   /// Retrieve the qualification on this type.
   NestedNameSpecifier *getQualifier() const { return NNS; }
 
   /// Retrieve the type named by the qualified-id.
   QualType getNamedType() const { return NamedType; }
 
   /// Remove a single level of sugar.
   QualType desugar() const { return getNamedType(); }
 
   /// Returns whether this type directly provides sugar.
   bool isSugared() const { return true; }
 
   /// Return the (re)declaration of this type owned by this occurrence of this
   /// type, or nullptr if there is none.
   TagDecl *getOwnedTagDecl() const {
     return ElaboratedTypeBits.HasOwnedTagDecl ? *getTrailingObjects<TagDecl *>()
                                               : nullptr;
   }
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, getKeyword(), NNS, NamedType, getOwnedTagDecl());
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, ElaboratedTypeKeyword Keyword,
                       NestedNameSpecifier *NNS, QualType NamedType,
                       TagDecl *OwnedTagDecl) {
     ID.AddInteger(Keyword);
     ID.AddPointer(NNS);
     NamedType.Profile(ID);
     ID.AddPointer(OwnedTagDecl);
   }
 
   static bool classof(const Type *T) { return T->getTypeClass() == Elaborated; }
 };
 
 /// Represents a qualified type name for which the type name is
 /// dependent.
 ///
 /// DependentNameType represents a class of dependent types that involve a
 /// possibly dependent nested-name-specifier (e.g., "T::") followed by a
 /// name of a type. The DependentNameType may start with a "typename" (for a
 /// typename-specifier), "class", "struct", "union", or "enum" (for a
 /// dependent elaborated-type-specifier), or nothing (in contexts where we
 /// know that we must be referring to a type, e.g., in a base class specifier).
 /// Typically the nested-name-specifier is dependent, but in MSVC compatibility
 /// mode, this type is used with non-dependent names to delay name lookup until
 /// instantiation.
 class DependentNameType : public TypeWithKeyword, public llvm::FoldingSetNode {
   friend class ASTContext; // ASTContext creates these
 
   /// The nested name specifier containing the qualifier.
   NestedNameSpecifier *NNS;
 
   /// The type that this typename specifier refers to.
   const IdentifierInfo *Name;
 
   DependentNameType(ElaboratedTypeKeyword Keyword, NestedNameSpecifier *NNS,
                     const IdentifierInfo *Name, QualType CanonType)
       : TypeWithKeyword(Keyword, DependentName, CanonType, /*Dependent=*/true,
                         /*InstantiationDependent=*/true,
                         /*VariablyModified=*/false,
                         NNS->containsUnexpandedParameterPack()),
         NNS(NNS), Name(Name) {}
 
 public:
   /// Retrieve the qualification on this type.
   NestedNameSpecifier *getQualifier() const { return NNS; }
 
   /// Retrieve the type named by the typename specifier as an identifier.
   ///
   /// This routine will return a non-NULL identifier pointer when the
   /// form of the original typename was terminated by an identifier,
   /// e.g., "typename T::type".
   const IdentifierInfo *getIdentifier() const {
     return Name;
   }
 
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, getKeyword(), NNS, Name);
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, ElaboratedTypeKeyword Keyword,
                       NestedNameSpecifier *NNS, const IdentifierInfo *Name) {
     ID.AddInteger(Keyword);
     ID.AddPointer(NNS);
     ID.AddPointer(Name);
   }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == DependentName;
   }
 };
 
 /// Represents a template specialization type whose template cannot be
 /// resolved, e.g.
 ///   A<T>::template B<T>
 class alignas(8) DependentTemplateSpecializationType
     : public TypeWithKeyword,
       public llvm::FoldingSetNode {
   friend class ASTContext; // ASTContext creates these
 
   /// The nested name specifier containing the qualifier.
   NestedNameSpecifier *NNS;
 
   /// The identifier of the template.
   const IdentifierInfo *Name;
 
   DependentTemplateSpecializationType(ElaboratedTypeKeyword Keyword,
                                       NestedNameSpecifier *NNS,
                                       const IdentifierInfo *Name,
                                       ArrayRef<TemplateArgument> Args,
                                       QualType Canon);
 
   const TemplateArgument *getArgBuffer() const {
     return reinterpret_cast<const TemplateArgument*>(this+1);
   }
 
   TemplateArgument *getArgBuffer() {
     return reinterpret_cast<TemplateArgument*>(this+1);
   }
 
 public:
   NestedNameSpecifier *getQualifier() const { return NNS; }
   const IdentifierInfo *getIdentifier() const { return Name; }
 
   /// Retrieve the template arguments.
   const TemplateArgument *getArgs() const {
     return getArgBuffer();
   }
 
   /// Retrieve the number of template arguments.
   unsigned getNumArgs() const {
     return DependentTemplateSpecializationTypeBits.NumArgs;
   }
 
   const TemplateArgument &getArg(unsigned Idx) const; // in TemplateBase.h
 
   ArrayRef<TemplateArgument> template_arguments() const {
     return {getArgs(), getNumArgs()};
   }
 
   using iterator = const TemplateArgument *;
 
   iterator begin() const { return getArgs(); }
   iterator end() const; // inline in TemplateBase.h
 
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &Context) {
     Profile(ID, Context, getKeyword(), NNS, Name, {getArgs(), getNumArgs()});
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID,
                       const ASTContext &Context,
                       ElaboratedTypeKeyword Keyword,
                       NestedNameSpecifier *Qualifier,
                       const IdentifierInfo *Name,
                       ArrayRef<TemplateArgument> Args);
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == DependentTemplateSpecialization;
   }
 };
 
 /// Represents a pack expansion of types.
 ///
 /// Pack expansions are part of C++11 variadic templates. A pack
 /// expansion contains a pattern, which itself contains one or more
 /// "unexpanded" parameter packs. When instantiated, a pack expansion
 /// produces a series of types, each instantiated from the pattern of
 /// the expansion, where the Ith instantiation of the pattern uses the
 /// Ith arguments bound to each of the unexpanded parameter packs. The
 /// pack expansion is considered to "expand" these unexpanded
 /// parameter packs.
 ///
 /// \code
 /// template<typename ...Types> struct tuple;
 ///
 /// template<typename ...Types>
 /// struct tuple_of_references {
 ///   typedef tuple<Types&...> type;
 /// };
 /// \endcode
 ///
 /// Here, the pack expansion \c Types&... is represented via a
 /// PackExpansionType whose pattern is Types&.
 class PackExpansionType : public Type, public llvm::FoldingSetNode {
   friend class ASTContext; // ASTContext creates these
 
   /// The pattern of the pack expansion.
   QualType Pattern;
 
   PackExpansionType(QualType Pattern, QualType Canon,
                     Optional<unsigned> NumExpansions)
       : Type(PackExpansion, Canon, /*Dependent=*/Pattern->isDependentType(),
              /*InstantiationDependent=*/true,
              /*VariablyModified=*/Pattern->isVariablyModifiedType(),
              /*ContainsUnexpandedParameterPack=*/false),
         Pattern(Pattern) {
     PackExpansionTypeBits.NumExpansions =
         NumExpansions ? *NumExpansions + 1 : 0;
   }
 
 public:
   /// Retrieve the pattern of this pack expansion, which is the
   /// type that will be repeatedly instantiated when instantiating the
   /// pack expansion itself.
   QualType getPattern() const { return Pattern; }
 
   /// Retrieve the number of expansions that this pack expansion will
   /// generate, if known.
   Optional<unsigned> getNumExpansions() const {
     if (PackExpansionTypeBits.NumExpansions)
       return PackExpansionTypeBits.NumExpansions - 1;
     return None;
   }
 
   bool isSugared() const { return !Pattern->isDependentType(); }
   QualType desugar() const { return isSugared() ? Pattern : QualType(this, 0); }
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, getPattern(), getNumExpansions());
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, QualType Pattern,
                       Optional<unsigned> NumExpansions) {
     ID.AddPointer(Pattern.getAsOpaquePtr());
     ID.AddBoolean(NumExpansions.hasValue());
     if (NumExpansions)
       ID.AddInteger(*NumExpansions);
   }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == PackExpansion;
   }
 };
 
 /// This class wraps the list of protocol qualifiers. For types that can
 /// take ObjC protocol qualifers, they can subclass this class.
 template <class T>
 class ObjCProtocolQualifiers {
 protected:
   ObjCProtocolQualifiers() = default;
 
   ObjCProtocolDecl * const *getProtocolStorage() const {
     return const_cast<ObjCProtocolQualifiers*>(this)->getProtocolStorage();
   }
 
   ObjCProtocolDecl **getProtocolStorage() {
     return static_cast<T*>(this)->getProtocolStorageImpl();
   }
 
   void setNumProtocols(unsigned N) {
     static_cast<T*>(this)->setNumProtocolsImpl(N);
   }
 
   void initialize(ArrayRef<ObjCProtocolDecl *> protocols) {
     setNumProtocols(protocols.size());
     assert(getNumProtocols() == protocols.size() &&
            "bitfield overflow in protocol count");
     if (!protocols.empty())
       memcpy(getProtocolStorage(), protocols.data(),
              protocols.size() * sizeof(ObjCProtocolDecl*));
   }
 
 public:
   using qual_iterator = ObjCProtocolDecl * const *;
   using qual_range = llvm::iterator_range<qual_iterator>;
 
   qual_range quals() const { return qual_range(qual_begin(), qual_end()); }
   qual_iterator qual_begin() const { return getProtocolStorage(); }
   qual_iterator qual_end() const { return qual_begin() + getNumProtocols(); }
 
   bool qual_empty() const { return getNumProtocols() == 0; }
 
   /// Return the number of qualifying protocols in this type, or 0 if
   /// there are none.
   unsigned getNumProtocols() const {
     return static_cast<const T*>(this)->getNumProtocolsImpl();
   }
 
   /// Fetch a protocol by index.
   ObjCProtocolDecl *getProtocol(unsigned I) const {
     assert(I < getNumProtocols() && "Out-of-range protocol access");
     return qual_begin()[I];
   }
 
   /// Retrieve all of the protocol qualifiers.
   ArrayRef<ObjCProtocolDecl *> getProtocols() const {
     return ArrayRef<ObjCProtocolDecl *>(qual_begin(), getNumProtocols());
   }
 };
 
 /// Represents a type parameter type in Objective C. It can take
 /// a list of protocols.
 class ObjCTypeParamType : public Type,
                           public ObjCProtocolQualifiers<ObjCTypeParamType>,
                           public llvm::FoldingSetNode {
   friend class ASTContext;
   friend class ObjCProtocolQualifiers<ObjCTypeParamType>;
 
   /// The number of protocols stored on this type.
   unsigned NumProtocols : 6;
 
   ObjCTypeParamDecl *OTPDecl;
 
   /// The protocols are stored after the ObjCTypeParamType node. In the
   /// canonical type, the list of protocols are sorted alphabetically
   /// and uniqued.
   ObjCProtocolDecl **getProtocolStorageImpl();
 
   /// Return the number of qualifying protocols in this interface type,
   /// or 0 if there are none.
   unsigned getNumProtocolsImpl() const {
     return NumProtocols;
   }
 
   void setNumProtocolsImpl(unsigned N) {
     NumProtocols = N;
   }
 
   ObjCTypeParamType(const ObjCTypeParamDecl *D,
                     QualType can,
                     ArrayRef<ObjCProtocolDecl *> protocols);
 
 public:
   bool isSugared() const { return true; }
   QualType desugar() const { return getCanonicalTypeInternal(); }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == ObjCTypeParam;
   }
 
   void Profile(llvm::FoldingSetNodeID &ID);
   static void Profile(llvm::FoldingSetNodeID &ID,
                       const ObjCTypeParamDecl *OTPDecl,
                       ArrayRef<ObjCProtocolDecl *> protocols);
 
   ObjCTypeParamDecl *getDecl() const { return OTPDecl; }
 };
 
 /// Represents a class type in Objective C.
 ///
 /// Every Objective C type is a combination of a base type, a set of
 /// type arguments (optional, for parameterized classes) and a list of
 /// protocols.
 ///
 /// Given the following declarations:
 /// \code
 ///   \@class C<T>;
 ///   \@protocol P;
 /// \endcode
 ///
 /// 'C' is an ObjCInterfaceType C.  It is sugar for an ObjCObjectType
 /// with base C and no protocols.
 ///
 /// 'C<P>' is an unspecialized ObjCObjectType with base C and protocol list [P].
 /// 'C<C*>' is a specialized ObjCObjectType with type arguments 'C*' and no
 /// protocol list.
 /// 'C<C*><P>' is a specialized ObjCObjectType with base C, type arguments 'C*',
 /// and protocol list [P].
 ///
 /// 'id' is a TypedefType which is sugar for an ObjCObjectPointerType whose
 /// pointee is an ObjCObjectType with base BuiltinType::ObjCIdType
 /// and no protocols.
 ///
 /// 'id<P>' is an ObjCObjectPointerType whose pointee is an ObjCObjectType
 /// with base BuiltinType::ObjCIdType and protocol list [P].  Eventually
 /// this should get its own sugar class to better represent the source.
 class ObjCObjectType : public Type,
                        public ObjCProtocolQualifiers<ObjCObjectType> {
   friend class ObjCProtocolQualifiers<ObjCObjectType>;
 
   // ObjCObjectType.NumTypeArgs - the number of type arguments stored
   // after the ObjCObjectPointerType node.
   // ObjCObjectType.NumProtocols - the number of protocols stored
   // after the type arguments of ObjCObjectPointerType node.
   //
   // These protocols are those written directly on the type.  If
   // protocol qualifiers ever become additive, the iterators will need
   // to get kindof complicated.
   //
   // In the canonical object type, these are sorted alphabetically
   // and uniqued.
 
   /// Either a BuiltinType or an InterfaceType or sugar for either.
   QualType BaseType;
 
   /// Cached superclass type.
   mutable llvm::PointerIntPair<const ObjCObjectType *, 1, bool>
     CachedSuperClassType;
 
   QualType *getTypeArgStorage();
   const QualType *getTypeArgStorage() const {
     return const_cast<ObjCObjectType *>(this)->getTypeArgStorage();
   }
 
   ObjCProtocolDecl **getProtocolStorageImpl();
   /// Return the number of qualifying protocols in this interface type,
   /// or 0 if there are none.
   unsigned getNumProtocolsImpl() const {
     return ObjCObjectTypeBits.NumProtocols;
   }
   void setNumProtocolsImpl(unsigned N) {
     ObjCObjectTypeBits.NumProtocols = N;
   }
 
 protected:
   enum Nonce_ObjCInterface { Nonce_ObjCInterface };
 
   ObjCObjectType(QualType Canonical, QualType Base,
                  ArrayRef<QualType> typeArgs,
                  ArrayRef<ObjCProtocolDecl *> protocols,
                  bool isKindOf);
 
   ObjCObjectType(enum Nonce_ObjCInterface)
         : Type(ObjCInterface, QualType(), false, false, false, false),
           BaseType(QualType(this_(), 0)) {
     ObjCObjectTypeBits.NumProtocols = 0;
     ObjCObjectTypeBits.NumTypeArgs = 0;
     ObjCObjectTypeBits.IsKindOf = 0;
   }
 
   void computeSuperClassTypeSlow() const;
 
 public:
   /// Gets the base type of this object type.  This is always (possibly
   /// sugar for) one of:
   ///  - the 'id' builtin type (as opposed to the 'id' type visible to the
   ///    user, which is a typedef for an ObjCObjectPointerType)
   ///  - the 'Class' builtin type (same caveat)
   ///  - an ObjCObjectType (currently always an ObjCInterfaceType)
   QualType getBaseType() const { return BaseType; }
 
   bool isObjCId() const {
     return getBaseType()->isSpecificBuiltinType(BuiltinType::ObjCId);
   }
 
   bool isObjCClass() const {
     return getBaseType()->isSpecificBuiltinType(BuiltinType::ObjCClass);
   }
 
   bool isObjCUnqualifiedId() const { return qual_empty() && isObjCId(); }
   bool isObjCUnqualifiedClass() const { return qual_empty() && isObjCClass(); }
   bool isObjCUnqualifiedIdOrClass() const {
     if (!qual_empty()) return false;
     if (const BuiltinType *T = getBaseType()->getAs<BuiltinType>())
       return T->getKind() == BuiltinType::ObjCId ||
              T->getKind() == BuiltinType::ObjCClass;
     return false;
   }
   bool isObjCQualifiedId() const { return !qual_empty() && isObjCId(); }
   bool isObjCQualifiedClass() const { return !qual_empty() && isObjCClass(); }
 
   /// Gets the interface declaration for this object type, if the base type
   /// really is an interface.
   ObjCInterfaceDecl *getInterface() const;
 
   /// Determine whether this object type is "specialized", meaning
   /// that it has type arguments.
   bool isSpecialized() const;
 
   /// Determine whether this object type was written with type arguments.
   bool isSpecializedAsWritten() const {
     return ObjCObjectTypeBits.NumTypeArgs > 0;
   }
 
   /// Determine whether this object type is "unspecialized", meaning
   /// that it has no type arguments.
   bool isUnspecialized() const { return !isSpecialized(); }
 
   /// Determine whether this object type is "unspecialized" as
   /// written, meaning that it has no type arguments.
   bool isUnspecializedAsWritten() const { return !isSpecializedAsWritten(); }
 
   /// Retrieve the type arguments of this object type (semantically).
   ArrayRef<QualType> getTypeArgs() const;
 
   /// Retrieve the type arguments of this object type as they were
   /// written.
   ArrayRef<QualType> getTypeArgsAsWritten() const {
     return llvm::makeArrayRef(getTypeArgStorage(),
                               ObjCObjectTypeBits.NumTypeArgs);
   }
 
   /// Whether this is a "__kindof" type as written.
   bool isKindOfTypeAsWritten() const { return ObjCObjectTypeBits.IsKindOf; }
 
   /// Whether this ia a "__kindof" type (semantically).
   bool isKindOfType() const;
 
   /// Retrieve the type of the superclass of this object type.
   ///
   /// This operation substitutes any type arguments into the
   /// superclass of the current class type, potentially producing a
   /// specialization of the superclass type. Produces a null type if
   /// there is no superclass.
   QualType getSuperClassType() const {
     if (!CachedSuperClassType.getInt())
       computeSuperClassTypeSlow();
 
     assert(CachedSuperClassType.getInt() && "Superclass not set?");
     return QualType(CachedSuperClassType.getPointer(), 0);
   }
 
   /// Strip off the Objective-C "kindof" type and (with it) any
   /// protocol qualifiers.
   QualType stripObjCKindOfTypeAndQuals(const ASTContext &ctx) const;
 
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == ObjCObject ||
            T->getTypeClass() == ObjCInterface;
   }
 };
 
 /// A class providing a concrete implementation
 /// of ObjCObjectType, so as to not increase the footprint of
 /// ObjCInterfaceType.  Code outside of ASTContext and the core type
 /// system should not reference this type.
 class ObjCObjectTypeImpl : public ObjCObjectType, public llvm::FoldingSetNode {
   friend class ASTContext;
 
   // If anyone adds fields here, ObjCObjectType::getProtocolStorage()
   // will need to be modified.
 
   ObjCObjectTypeImpl(QualType Canonical, QualType Base,
                      ArrayRef<QualType> typeArgs,
                      ArrayRef<ObjCProtocolDecl *> protocols,
                      bool isKindOf)
       : ObjCObjectType(Canonical, Base, typeArgs, protocols, isKindOf) {}
 
 public:
   void Profile(llvm::FoldingSetNodeID &ID);
   static void Profile(llvm::FoldingSetNodeID &ID,
                       QualType Base,
                       ArrayRef<QualType> typeArgs,
                       ArrayRef<ObjCProtocolDecl *> protocols,
                       bool isKindOf);
 };
 
 inline QualType *ObjCObjectType::getTypeArgStorage() {
   return reinterpret_cast<QualType *>(static_cast<ObjCObjectTypeImpl*>(this)+1);
 }
 
 inline ObjCProtocolDecl **ObjCObjectType::getProtocolStorageImpl() {
     return reinterpret_cast<ObjCProtocolDecl**>(
              getTypeArgStorage() + ObjCObjectTypeBits.NumTypeArgs);
 }
 
 inline ObjCProtocolDecl **ObjCTypeParamType::getProtocolStorageImpl() {
     return reinterpret_cast<ObjCProtocolDecl**>(
              static_cast<ObjCTypeParamType*>(this)+1);
 }
 
 /// Interfaces are the core concept in Objective-C for object oriented design.
 /// They basically correspond to C++ classes.  There are two kinds of interface
 /// types: normal interfaces like `NSString`, and qualified interfaces, which
 /// are qualified with a protocol list like `NSString<NSCopyable, NSAmazing>`.
 ///
 /// ObjCInterfaceType guarantees the following properties when considered
 /// as a subtype of its superclass, ObjCObjectType:
 ///   - There are no protocol qualifiers.  To reinforce this, code which
 ///     tries to invoke the protocol methods via an ObjCInterfaceType will
 ///     fail to compile.
 ///   - It is its own base type.  That is, if T is an ObjCInterfaceType*,
 ///     T->getBaseType() == QualType(T, 0).
 class ObjCInterfaceType : public ObjCObjectType {
   friend class ASTContext; // ASTContext creates these.
   friend class ASTReader;
   friend class ObjCInterfaceDecl;
 
   mutable ObjCInterfaceDecl *Decl;
 
   ObjCInterfaceType(const ObjCInterfaceDecl *D)
       : ObjCObjectType(Nonce_ObjCInterface),
         Decl(const_cast<ObjCInterfaceDecl*>(D)) {}
 
 public:
   /// Get the declaration of this interface.
   ObjCInterfaceDecl *getDecl() const { return Decl; }
 
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == ObjCInterface;
   }
 
   // Nonsense to "hide" certain members of ObjCObjectType within this
   // class.  People asking for protocols on an ObjCInterfaceType are
   // not going to get what they want: ObjCInterfaceTypes are
   // guaranteed to have no protocols.
   enum {
     qual_iterator,
     qual_begin,
     qual_end,
     getNumProtocols,
     getProtocol
   };
 };
 
 inline ObjCInterfaceDecl *ObjCObjectType::getInterface() const {
   QualType baseType = getBaseType();
   while (const auto *ObjT = baseType->getAs<ObjCObjectType>()) {
     if (const auto *T = dyn_cast<ObjCInterfaceType>(ObjT))
       return T->getDecl();
 
     baseType = ObjT->getBaseType();
   }
 
   return nullptr;
 }
 
 /// Represents a pointer to an Objective C object.
 ///
 /// These are constructed from pointer declarators when the pointee type is
 /// an ObjCObjectType (or sugar for one).  In addition, the 'id' and 'Class'
 /// types are typedefs for these, and the protocol-qualified types 'id<P>'
 /// and 'Class<P>' are translated into these.
 ///
 /// Pointers to pointers to Objective C objects are still PointerTypes;
 /// only the first level of pointer gets it own type implementation.
 class ObjCObjectPointerType : public Type, public llvm::FoldingSetNode {
   friend class ASTContext; // ASTContext creates these.
 
   QualType PointeeType;
 
   ObjCObjectPointerType(QualType Canonical, QualType Pointee)
       : Type(ObjCObjectPointer, Canonical,
              Pointee->isDependentType(),
              Pointee->isInstantiationDependentType(),
              Pointee->isVariablyModifiedType(),
              Pointee->containsUnexpandedParameterPack()),
         PointeeType(Pointee) {}
 
 public:
   /// Gets the type pointed to by this ObjC pointer.
   /// The result will always be an ObjCObjectType or sugar thereof.
   QualType getPointeeType() const { return PointeeType; }
 
   /// Gets the type pointed to by this ObjC pointer.  Always returns non-null.
   ///
   /// This method is equivalent to getPointeeType() except that
   /// it discards any typedefs (or other sugar) between this
   /// type and the "outermost" object type.  So for:
   /// \code
   ///   \@class A; \@protocol P; \@protocol Q;
   ///   typedef A<P> AP;
   ///   typedef A A1;
   ///   typedef A1<P> A1P;
   ///   typedef A1P<Q> A1PQ;
   /// \endcode
   /// For 'A*', getObjectType() will return 'A'.
   /// For 'A<P>*', getObjectType() will return 'A<P>'.
   /// For 'AP*', getObjectType() will return 'A<P>'.
   /// For 'A1*', getObjectType() will return 'A'.
   /// For 'A1<P>*', getObjectType() will return 'A1<P>'.
   /// For 'A1P*', getObjectType() will return 'A1<P>'.
   /// For 'A1PQ*', getObjectType() will return 'A1<Q>', because
   ///   adding protocols to a protocol-qualified base discards the
   ///   old qualifiers (for now).  But if it didn't, getObjectType()
   ///   would return 'A1P<Q>' (and we'd have to make iterating over
   ///   qualifiers more complicated).
   const ObjCObjectType *getObjectType() const {
     return PointeeType->castAs<ObjCObjectType>();
   }
 
   /// If this pointer points to an Objective C
   /// \@interface type, gets the type for that interface.  Any protocol
   /// qualifiers on the interface are ignored.
   ///
   /// \return null if the base type for this pointer is 'id' or 'Class'
   const ObjCInterfaceType *getInterfaceType() const;
 
   /// If this pointer points to an Objective \@interface
   /// type, gets the declaration for that interface.
   ///
   /// \return null if the base type for this pointer is 'id' or 'Class'
   ObjCInterfaceDecl *getInterfaceDecl() const {
     return getObjectType()->getInterface();
   }
 
   /// True if this is equivalent to the 'id' type, i.e. if
   /// its object type is the primitive 'id' type with no protocols.
   bool isObjCIdType() const {
     return getObjectType()->isObjCUnqualifiedId();
   }
 
   /// True if this is equivalent to the 'Class' type,
   /// i.e. if its object tive is the primitive 'Class' type with no protocols.
   bool isObjCClassType() const {
     return getObjectType()->isObjCUnqualifiedClass();
   }
 
   /// True if this is equivalent to the 'id' or 'Class' type,
   bool isObjCIdOrClassType() const {
     return getObjectType()->isObjCUnqualifiedIdOrClass();
   }
 
   /// True if this is equivalent to 'id<P>' for some non-empty set of
   /// protocols.
   bool isObjCQualifiedIdType() const {
     return getObjectType()->isObjCQualifiedId();
   }
 
   /// True if this is equivalent to 'Class<P>' for some non-empty set of
   /// protocols.
   bool isObjCQualifiedClassType() const {
     return getObjectType()->isObjCQualifiedClass();
   }
 
   /// Whether this is a "__kindof" type.
   bool isKindOfType() const { return getObjectType()->isKindOfType(); }
 
   /// Whether this type is specialized, meaning that it has type arguments.
   bool isSpecialized() const { return getObjectType()->isSpecialized(); }
 
   /// Whether this type is specialized, meaning that it has type arguments.
   bool isSpecializedAsWritten() const {
     return getObjectType()->isSpecializedAsWritten();
   }
 
   /// Whether this type is unspecialized, meaning that is has no type arguments.
   bool isUnspecialized() const { return getObjectType()->isUnspecialized(); }
 
   /// Determine whether this object type is "unspecialized" as
   /// written, meaning that it has no type arguments.
   bool isUnspecializedAsWritten() const { return !isSpecializedAsWritten(); }
 
   /// Retrieve the type arguments for this type.
   ArrayRef<QualType> getTypeArgs() const {
     return getObjectType()->getTypeArgs();
   }
 
   /// Retrieve the type arguments for this type.
   ArrayRef<QualType> getTypeArgsAsWritten() const {
     return getObjectType()->getTypeArgsAsWritten();
   }
 
   /// An iterator over the qualifiers on the object type.  Provided
   /// for convenience.  This will always iterate over the full set of
   /// protocols on a type, not just those provided directly.
   using qual_iterator = ObjCObjectType::qual_iterator;
   using qual_range = llvm::iterator_range<qual_iterator>;
 
   qual_range quals() const { return qual_range(qual_begin(), qual_end()); }
 
   qual_iterator qual_begin() const {
     return getObjectType()->qual_begin();
   }
 
   qual_iterator qual_end() const {
     return getObjectType()->qual_end();
   }
 
   bool qual_empty() const { return getObjectType()->qual_empty(); }
 
   /// Return the number of qualifying protocols on the object type.
   unsigned getNumProtocols() const {
     return getObjectType()->getNumProtocols();
   }
 
   /// Retrieve a qualifying protocol by index on the object type.
   ObjCProtocolDecl *getProtocol(unsigned I) const {
     return getObjectType()->getProtocol(I);
   }
 
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   /// Retrieve the type of the superclass of this object pointer type.
   ///
   /// This operation substitutes any type arguments into the
   /// superclass of the current class type, potentially producing a
   /// pointer to a specialization of the superclass type. Produces a
   /// null type if there is no superclass.
   QualType getSuperClassType() const;
 
   /// Strip off the Objective-C "kindof" type and (with it) any
   /// protocol qualifiers.
   const ObjCObjectPointerType *stripObjCKindOfTypeAndQuals(
                                  const ASTContext &ctx) const;
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, getPointeeType());
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, QualType T) {
     ID.AddPointer(T.getAsOpaquePtr());
   }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == ObjCObjectPointer;
   }
 };
 
 class AtomicType : public Type, public llvm::FoldingSetNode {
   friend class ASTContext; // ASTContext creates these.
 
   QualType ValueType;
 
   AtomicType(QualType ValTy, QualType Canonical)
       : Type(Atomic, Canonical, ValTy->isDependentType(),
              ValTy->isInstantiationDependentType(),
              ValTy->isVariablyModifiedType(),
              ValTy->containsUnexpandedParameterPack()),
         ValueType(ValTy) {}
 
 public:
   /// Gets the type contained by this atomic type, i.e.
   /// the type returned by performing an atomic load of this atomic type.
   QualType getValueType() const { return ValueType; }
 
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, getValueType());
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, QualType T) {
     ID.AddPointer(T.getAsOpaquePtr());
   }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == Atomic;
   }
 };
 
 /// PipeType - OpenCL20.
 class PipeType : public Type, public llvm::FoldingSetNode {
   friend class ASTContext; // ASTContext creates these.
 
   QualType ElementType;
   bool isRead;
 
   PipeType(QualType elemType, QualType CanonicalPtr, bool isRead)
       : Type(Pipe, CanonicalPtr, elemType->isDependentType(),
              elemType->isInstantiationDependentType(),
              elemType->isVariablyModifiedType(),
              elemType->containsUnexpandedParameterPack()),
         ElementType(elemType), isRead(isRead) {}
 
 public:
   QualType getElementType() const { return ElementType; }
 
   bool isSugared() const { return false; }
 
   QualType desugar() const { return QualType(this, 0); }
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, getElementType(), isReadOnly());
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, QualType T, bool isRead) {
     ID.AddPointer(T.getAsOpaquePtr());
     ID.AddBoolean(isRead);
   }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == Pipe;
   }
 
   bool isReadOnly() const { return isRead; }
 };
 
 /// A qualifier set is used to build a set of qualifiers.
 class QualifierCollector : public Qualifiers {
 public:
   QualifierCollector(Qualifiers Qs = Qualifiers()) : Qualifiers(Qs) {}
 
   /// Collect any qualifiers on the given type and return an
   /// unqualified type.  The qualifiers are assumed to be consistent
   /// with those already in the type.
   const Type *strip(QualType type) {
     addFastQualifiers(type.getLocalFastQualifiers());
     if (!type.hasLocalNonFastQualifiers())
       return type.getTypePtrUnsafe();
 
     const ExtQuals *extQuals = type.getExtQualsUnsafe();
     addConsistentQualifiers(extQuals->getQualifiers());
     return extQuals->getBaseType();
   }
 
   /// Apply the collected qualifiers to the given type.
   QualType apply(const ASTContext &Context, QualType QT) const;
 
   /// Apply the collected qualifiers to the given type.
   QualType apply(const ASTContext &Context, const Type* T) const;
 };
 
 // Inline function definitions.
 
 inline SplitQualType SplitQualType::getSingleStepDesugaredType() const {
   SplitQualType desugar =
     Ty->getLocallyUnqualifiedSingleStepDesugaredType().split();
   desugar.Quals.addConsistentQualifiers(Quals);
   return desugar;
 }
 
 inline const Type *QualType::getTypePtr() const {
   return getCommonPtr()->BaseType;
 }
 
 inline const Type *QualType::getTypePtrOrNull() const {
   return (isNull() ? nullptr : getCommonPtr()->BaseType);
 }
 
 inline SplitQualType QualType::split() const {
   if (!hasLocalNonFastQualifiers())
     return SplitQualType(getTypePtrUnsafe(),
                          Qualifiers::fromFastMask(getLocalFastQualifiers()));
 
   const ExtQuals *eq = getExtQualsUnsafe();
   Qualifiers qs = eq->getQualifiers();
   qs.addFastQualifiers(getLocalFastQualifiers());
   return SplitQualType(eq->getBaseType(), qs);
 }
 
 inline Qualifiers QualType::getLocalQualifiers() const {
   Qualifiers Quals;
   if (hasLocalNonFastQualifiers())
     Quals = getExtQualsUnsafe()->getQualifiers();
   Quals.addFastQualifiers(getLocalFastQualifiers());
   return Quals;
 }
 
 inline Qualifiers QualType::getQualifiers() const {
   Qualifiers quals = getCommonPtr()->CanonicalType.getLocalQualifiers();
   quals.addFastQualifiers(getLocalFastQualifiers());
   return quals;
 }
 
 inline unsigned QualType::getCVRQualifiers() const {
   unsigned cvr = getCommonPtr()->CanonicalType.getLocalCVRQualifiers();
   cvr |= getLocalCVRQualifiers();
   return cvr;
 }
 
 inline QualType QualType::getCanonicalType() const {
   QualType canon = getCommonPtr()->CanonicalType;
   return canon.withFastQualifiers(getLocalFastQualifiers());
 }
 
 inline bool QualType::isCanonical() const {
   return getTypePtr()->isCanonicalUnqualified();
 }
 
 inline bool QualType::isCanonicalAsParam() const {
   if (!isCanonical()) return false;
   if (hasLocalQualifiers()) return false;
 
   const Type *T = getTypePtr();
   if (T->isVariablyModifiedType() && T->hasSizedVLAType())
     return false;
 
   return !isa<FunctionType>(T) && !isa<ArrayType>(T);
 }
 
 inline bool QualType::isConstQualified() const {
   return isLocalConstQualified() ||
          getCommonPtr()->CanonicalType.isLocalConstQualified();
 }
 
 inline bool QualType::isRestrictQualified() const {
   return isLocalRestrictQualified() ||
          getCommonPtr()->CanonicalType.isLocalRestrictQualified();
 }
 
 
 inline bool QualType::isVolatileQualified() const {
   return isLocalVolatileQualified() ||
          getCommonPtr()->CanonicalType.isLocalVolatileQualified();
 }
 
 inline bool QualType::hasQualifiers() const {
   return hasLocalQualifiers() ||
          getCommonPtr()->CanonicalType.hasLocalQualifiers();
 }
 
 inline QualType QualType::getUnqualifiedType() const {
   if (!getTypePtr()->getCanonicalTypeInternal().hasLocalQualifiers())
     return QualType(getTypePtr(), 0);
 
   return QualType(getSplitUnqualifiedTypeImpl(*this).Ty, 0);
 }
 
 inline SplitQualType QualType::getSplitUnqualifiedType() const {
   if (!getTypePtr()->getCanonicalTypeInternal().hasLocalQualifiers())
     return split();
 
   return getSplitUnqualifiedTypeImpl(*this);
 }
 
 inline void QualType::removeLocalConst() {
   removeLocalFastQualifiers(Qualifiers::Const);
 }
 
 inline void QualType::removeLocalRestrict() {
   removeLocalFastQualifiers(Qualifiers::Restrict);
 }
 
 inline void QualType::removeLocalVolatile() {
   removeLocalFastQualifiers(Qualifiers::Volatile);
 }
 
 inline void QualType::removeLocalCVRQualifiers(unsigned Mask) {
   assert(!(Mask & ~Qualifiers::CVRMask) && "mask has non-CVR bits");
   static_assert((int)Qualifiers::CVRMask == (int)Qualifiers::FastMask,
                 "Fast bits differ from CVR bits!");
 
   // Fast path: we don't need to touch the slow qualifiers.
   removeLocalFastQualifiers(Mask);
 }
 
 /// Return the address space of this type.
 inline LangAS QualType::getAddressSpace() const {
   return getQualifiers().getAddressSpace();
 }
 
 /// Return the gc attribute of this type.
 inline Qualifiers::GC QualType::getObjCGCAttr() const {
   return getQualifiers().getObjCGCAttr();
 }
 
 inline FunctionType::ExtInfo getFunctionExtInfo(const Type &t) {
   if (const auto *PT = t.getAs<PointerType>()) {
     if (const auto *FT = PT->getPointeeType()->getAs<FunctionType>())
       return FT->getExtInfo();
   } else if (const auto *FT = t.getAs<FunctionType>())
     return FT->getExtInfo();
 
   return FunctionType::ExtInfo();
 }
 
 inline FunctionType::ExtInfo getFunctionExtInfo(QualType t) {
   return getFunctionExtInfo(*t);
 }
 
 /// Determine whether this type is more
 /// qualified than the Other type. For example, "const volatile int"
 /// is more qualified than "const int", "volatile int", and
 /// "int". However, it is not more qualified than "const volatile
 /// int".
 inline bool QualType::isMoreQualifiedThan(QualType other) const {
   Qualifiers MyQuals = getQualifiers();
   Qualifiers OtherQuals = other.getQualifiers();
   return (MyQuals != OtherQuals && MyQuals.compatiblyIncludes(OtherQuals));
 }
 
 /// Determine whether this type is at last
 /// as qualified as the Other type. For example, "const volatile
 /// int" is at least as qualified as "const int", "volatile int",
 /// "int", and "const volatile int".
 inline bool QualType::isAtLeastAsQualifiedAs(QualType other) const {
   Qualifiers OtherQuals = other.getQualifiers();
 
   // Ignore __unaligned qualifier if this type is a void.
   if (getUnqualifiedType()->isVoidType())
     OtherQuals.removeUnaligned();
 
   return getQualifiers().compatiblyIncludes(OtherQuals);
 }
 
 /// If Type is a reference type (e.g., const
 /// int&), returns the type that the reference refers to ("const
 /// int"). Otherwise, returns the type itself. This routine is used
 /// throughout Sema to implement C++ 5p6:
 ///
 ///   If an expression initially has the type "reference to T" (8.3.2,
 ///   8.5.3), the type is adjusted to "T" prior to any further
 ///   analysis, the expression designates the object or function
 ///   denoted by the reference, and the expression is an lvalue.
 inline QualType QualType::getNonReferenceType() const {
   if (const auto *RefType = (*this)->getAs<ReferenceType>())
     return RefType->getPointeeType();
   else
     return *this;
 }
 
 inline bool QualType::isCForbiddenLValueType() const {
   return ((getTypePtr()->isVoidType() && !hasQualifiers()) ||
           getTypePtr()->isFunctionType());
 }
 
 /// Tests whether the type is categorized as a fundamental type.
 ///
 /// \returns True for types specified in C++0x [basic.fundamental].
 inline bool Type::isFundamentalType() const {
   return isVoidType() ||
          // FIXME: It's really annoying that we don't have an
          // 'isArithmeticType()' which agrees with the standard definition.
          (isArithmeticType() && !isEnumeralType());
 }
 
 /// Tests whether the type is categorized as a compound type.
 ///
 /// \returns True for types specified in C++0x [basic.compound].
 inline bool Type::isCompoundType() const {
   // C++0x [basic.compound]p1:
   //   Compound types can be constructed in the following ways:
   //    -- arrays of objects of a given type [...];
   return isArrayType() ||
   //    -- functions, which have parameters of given types [...];
          isFunctionType() ||
   //    -- pointers to void or objects or functions [...];
          isPointerType() ||
   //    -- references to objects or functions of a given type. [...]
          isReferenceType() ||
   //    -- classes containing a sequence of objects of various types, [...];
          isRecordType() ||
   //    -- unions, which are classes capable of containing objects of different
   //               types at different times;
          isUnionType() ||
   //    -- enumerations, which comprise a set of named constant values. [...];
          isEnumeralType() ||
   //    -- pointers to non-static class members, [...].
          isMemberPointerType();
 }
 
 inline bool Type::isFunctionType() const {
   return isa<FunctionType>(CanonicalType);
 }
 
 inline bool Type::isPointerType() const {
   return isa<PointerType>(CanonicalType);
 }
 
 inline bool Type::isAnyPointerType() const {
   return isPointerType() || isObjCObjectPointerType();
 }
 
 inline bool Type::isBlockPointerType() const {
   return isa<BlockPointerType>(CanonicalType);
 }
 
 inline bool Type::isReferenceType() const {
   return isa<ReferenceType>(CanonicalType);
 }
 
 inline bool Type::isLValueReferenceType() const {
   return isa<LValueReferenceType>(CanonicalType);
 }
 
 inline bool Type::isRValueReferenceType() const {
   return isa<RValueReferenceType>(CanonicalType);
 }
 
 inline bool Type::isFunctionPointerType() const {
   if (const auto *T = getAs<PointerType>())
     return T->getPointeeType()->isFunctionType();
   else
     return false;
 }
 
 inline bool Type::isMemberPointerType() const {
   return isa<MemberPointerType>(CanonicalType);
 }
 
 inline bool Type::isMemberFunctionPointerType() const {
   if (const auto *T = getAs<MemberPointerType>())
     return T->isMemberFunctionPointer();
   else
     return false;
 }
 
 inline bool Type::isMemberDataPointerType() const {
   if (const auto *T = getAs<MemberPointerType>())
     return T->isMemberDataPointer();
   else
     return false;
 }
 
 inline bool Type::isArrayType() const {
   return isa<ArrayType>(CanonicalType);
 }
 
 inline bool Type::isConstantArrayType() const {
   return isa<ConstantArrayType>(CanonicalType);
 }
 
 inline bool Type::isIncompleteArrayType() const {
   return isa<IncompleteArrayType>(CanonicalType);
 }
 
 inline bool Type::isVariableArrayType() const {
   return isa<VariableArrayType>(CanonicalType);
 }
 
 inline bool Type::isDependentSizedArrayType() const {
   return isa<DependentSizedArrayType>(CanonicalType);
 }
 
 inline bool Type::isBuiltinType() const {
   return isa<BuiltinType>(CanonicalType);
 }
 
 inline bool Type::isRecordType() const {
   return isa<RecordType>(CanonicalType);
 }
 
 inline bool Type::isEnumeralType() const {
   return isa<EnumType>(CanonicalType);
 }
 
 inline bool Type::isAnyComplexType() const {
   return isa<ComplexType>(CanonicalType);
 }
 
 inline bool Type::isVectorType() const {
   return isa<VectorType>(CanonicalType);
 }
 
 inline bool Type::isExtVectorType() const {
   return isa<ExtVectorType>(CanonicalType);
 }
 
 inline bool Type::isDependentAddressSpaceType() const {
   return isa<DependentAddressSpaceType>(CanonicalType);
 }
 
 inline bool Type::isObjCObjectPointerType() const {
   return isa<ObjCObjectPointerType>(CanonicalType);
 }
 
 inline bool Type::isObjCObjectType() const {
   return isa<ObjCObjectType>(CanonicalType);
 }
 
 inline bool Type::isObjCObjectOrInterfaceType() const {
   return isa<ObjCInterfaceType>(CanonicalType) ||
     isa<ObjCObjectType>(CanonicalType);
 }
 
 inline bool Type::isAtomicType() const {
   return isa<AtomicType>(CanonicalType);
 }
 
 inline bool Type::isObjCQualifiedIdType() const {
   if (const auto *OPT = getAs<ObjCObjectPointerType>())
     return OPT->isObjCQualifiedIdType();
   return false;
 }
 
 inline bool Type::isObjCQualifiedClassType() const {
   if (const auto *OPT = getAs<ObjCObjectPointerType>())
     return OPT->isObjCQualifiedClassType();
   return false;
 }
 
 inline bool Type::isObjCIdType() const {
   if (const auto *OPT = getAs<ObjCObjectPointerType>())
     return OPT->isObjCIdType();
   return false;
 }
 
 inline bool Type::isObjCClassType() const {
   if (const auto *OPT = getAs<ObjCObjectPointerType>())
     return OPT->isObjCClassType();
   return false;
 }
 
 inline bool Type::isObjCSelType() const {
   if (const auto *OPT = getAs<PointerType>())
     return OPT->getPointeeType()->isSpecificBuiltinType(BuiltinType::ObjCSel);
   return false;
 }
 
 inline bool Type::isObjCBuiltinType() const {
   return isObjCIdType() || isObjCClassType() || isObjCSelType();
 }
 
 #define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \
   inline bool Type::is##Id##Type() const { \
     return isSpecificBuiltinType(BuiltinType::Id); \
   }
 #include "clang/Basic/OpenCLImageTypes.def"
 
 inline bool Type::isSamplerT() const {
   return isSpecificBuiltinType(BuiltinType::OCLSampler);
 }
 
 inline bool Type::isEventT() const {
   return isSpecificBuiltinType(BuiltinType::OCLEvent);
 }
 
 inline bool Type::isClkEventT() const {
   return isSpecificBuiltinType(BuiltinType::OCLClkEvent);
 }
 
 inline bool Type::isQueueT() const {
   return isSpecificBuiltinType(BuiltinType::OCLQueue);
 }
 
 inline bool Type::isReserveIDT() const {
   return isSpecificBuiltinType(BuiltinType::OCLReserveID);
 }
 
 inline bool Type::isImageType() const {
 #define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) is##Id##Type() ||
   return
 #include "clang/Basic/OpenCLImageTypes.def"
       false; // end boolean or operation
 }
 
 inline bool Type::isPipeType() const {
   return isa<PipeType>(CanonicalType);
 }
 
 #define EXT_OPAQUE_TYPE(ExtType, Id, Ext) \
   inline bool Type::is##Id##Type() const { \
     return isSpecificBuiltinType(BuiltinType::Id); \
   }
 #include "clang/Basic/OpenCLExtensionTypes.def"
 
 inline bool Type::isOCLIntelSubgroupAVCType() const {
 #define INTEL_SUBGROUP_AVC_TYPE(ExtType, Id) \
   isOCLIntelSubgroupAVC##Id##Type() ||
   return
 #include "clang/Basic/OpenCLExtensionTypes.def"
     false; // end of boolean or operation
 }
 
 inline bool Type::isOCLExtOpaqueType() const {
 #define EXT_OPAQUE_TYPE(ExtType, Id, Ext) is##Id##Type() ||
   return
 #include "clang/Basic/OpenCLExtensionTypes.def"
     false; // end of boolean or operation
 }
 
 inline bool Type::isOpenCLSpecificType() const {
   return isSamplerT() || isEventT() || isImageType() || isClkEventT() ||
          isQueueT() || isReserveIDT() || isPipeType() || isOCLExtOpaqueType();
 }
 
 inline bool Type::isTemplateTypeParmType() const {
   return isa<TemplateTypeParmType>(CanonicalType);
 }
 
 inline bool Type::isSpecificBuiltinType(unsigned K) const {
   if (const BuiltinType *BT = getAs<BuiltinType>())
     if (BT->getKind() == (BuiltinType::Kind) K)
       return true;
   return false;
 }
 
 inline bool Type::isPlaceholderType() const {
   if (const auto *BT = dyn_cast<BuiltinType>(this))
     return BT->isPlaceholderType();
   return false;
 }
 
 inline const BuiltinType *Type::getAsPlaceholderType() const {
   if (const auto *BT = dyn_cast<BuiltinType>(this))
     if (BT->isPlaceholderType())
       return BT;
   return nullptr;
 }
 
 inline bool Type::isSpecificPlaceholderType(unsigned K) const {
   assert(BuiltinType::isPlaceholderTypeKind((BuiltinType::Kind) K));
   if (const auto *BT = dyn_cast<BuiltinType>(this))
     return (BT->getKind() == (BuiltinType::Kind) K);
   return false;
 }
 
 inline bool Type::isNonOverloadPlaceholderType() const {
   if (const auto *BT = dyn_cast<BuiltinType>(this))
     return BT->isNonOverloadPlaceholderType();
   return false;
 }
 
 inline bool Type::isVoidType() const {
   if (const auto *BT = dyn_cast<BuiltinType>(CanonicalType))
     return BT->getKind() == BuiltinType::Void;
   return false;
 }
 
 inline bool Type::isHalfType() const {
   if (const auto *BT = dyn_cast<BuiltinType>(CanonicalType))
     return BT->getKind() == BuiltinType::Half;
   // FIXME: Should we allow complex __fp16? Probably not.
   return false;
 }
 
 inline bool Type::isFloat16Type() const {
   if (const auto *BT = dyn_cast<BuiltinType>(CanonicalType))
     return BT->getKind() == BuiltinType::Float16;
   return false;
 }
 
 inline bool Type::isFloat128Type() const {
   if (const auto *BT = dyn_cast<BuiltinType>(CanonicalType))
     return BT->getKind() == BuiltinType::Float128;
   return false;
 }
 
 inline bool Type::isNullPtrType() const {
   if (const auto *BT = getAs<BuiltinType>())
     return BT->getKind() == BuiltinType::NullPtr;
   return false;
 }
 
 bool IsEnumDeclComplete(EnumDecl *);
 bool IsEnumDeclScoped(EnumDecl *);
 
 inline bool Type::isIntegerType() const {
   if (const auto *BT = dyn_cast<BuiltinType>(CanonicalType))
     return BT->getKind() >= BuiltinType::Bool &&
            BT->getKind() <= BuiltinType::Int128;
   if (const EnumType *ET = dyn_cast<EnumType>(CanonicalType)) {
     // Incomplete enum types are not treated as integer types.
     // FIXME: In C++, enum types are never integer types.
     return IsEnumDeclComplete(ET->getDecl()) &&
       !IsEnumDeclScoped(ET->getDecl());
   }
   return false;
 }
 
 inline bool Type::isFixedPointType() const {
   if (const auto *BT = dyn_cast<BuiltinType>(CanonicalType)) {
     return BT->getKind() >= BuiltinType::ShortAccum &&
            BT->getKind() <= BuiltinType::SatULongFract;
   }
   return false;
 }
 
 inline bool Type::isSaturatedFixedPointType() const {
   if (const auto *BT = dyn_cast<BuiltinType>(CanonicalType)) {
     return BT->getKind() >= BuiltinType::SatShortAccum &&
            BT->getKind() <= BuiltinType::SatULongFract;
   }
   return false;
 }
 
 inline bool Type::isUnsaturatedFixedPointType() const {
   return isFixedPointType() && !isSaturatedFixedPointType();
 }
 
 inline bool Type::isSignedFixedPointType() const {
   if (const auto *BT = dyn_cast<BuiltinType>(CanonicalType)) {
     return ((BT->getKind() >= BuiltinType::ShortAccum &&
              BT->getKind() <= BuiltinType::LongAccum) ||
             (BT->getKind() >= BuiltinType::ShortFract &&
              BT->getKind() <= BuiltinType::LongFract) ||
             (BT->getKind() >= BuiltinType::SatShortAccum &&
              BT->getKind() <= BuiltinType::SatLongAccum) ||
             (BT->getKind() >= BuiltinType::SatShortFract &&
              BT->getKind() <= BuiltinType::SatLongFract));
   }
   return false;
 }
 
 inline bool Type::isUnsignedFixedPointType() const {
   return isFixedPointType() && !isSignedFixedPointType();
 }
 
 inline bool Type::isScalarType() const {
   if (const auto *BT = dyn_cast<BuiltinType>(CanonicalType))
     return BT->getKind() > BuiltinType::Void &&
            BT->getKind() <= BuiltinType::NullPtr;
   if (const EnumType *ET = dyn_cast<EnumType>(CanonicalType))
     // Enums are scalar types, but only if they are defined.  Incomplete enums
     // are not treated as scalar types.
     return IsEnumDeclComplete(ET->getDecl());
   return isa<PointerType>(CanonicalType) ||
          isa<BlockPointerType>(CanonicalType) ||
          isa<MemberPointerType>(CanonicalType) ||
          isa<ComplexType>(CanonicalType) ||
          isa<ObjCObjectPointerType>(CanonicalType);
 }
 
 inline bool Type::isIntegralOrEnumerationType() const {
   if (const auto *BT = dyn_cast<BuiltinType>(CanonicalType))
     return BT->getKind() >= BuiltinType::Bool &&
            BT->getKind() <= BuiltinType::Int128;
 
   // Check for a complete enum type; incomplete enum types are not properly an
   // enumeration type in the sense required here.
   if (const auto *ET = dyn_cast<EnumType>(CanonicalType))
     return IsEnumDeclComplete(ET->getDecl());
 
   return false;
 }
 
 inline bool Type::isBooleanType() const {
   if (const auto *BT = dyn_cast<BuiltinType>(CanonicalType))
     return BT->getKind() == BuiltinType::Bool;
   return false;
 }
 
 inline bool Type::isUndeducedType() const {
   auto *DT = getContainedDeducedType();
   return DT && !DT->isDeduced();
 }
 
 /// Determines whether this is a type for which one can define
 /// an overloaded operator.
 inline bool Type::isOverloadableType() const {
   return isDependentType() || isRecordType() || isEnumeralType();
 }
 
 /// Determines whether this type can decay to a pointer type.
 inline bool Type::canDecayToPointerType() const {
   return isFunctionType() || isArrayType();
 }
 
 inline bool Type::hasPointerRepresentation() const {
   return (isPointerType() || isReferenceType() || isBlockPointerType() ||
           isObjCObjectPointerType() || isNullPtrType());
 }
 
 inline bool Type::hasObjCPointerRepresentation() const {
   return isObjCObjectPointerType();
 }
 
 inline const Type *Type::getBaseElementTypeUnsafe() const {
   const Type *type = this;
   while (const ArrayType *arrayType = type->getAsArrayTypeUnsafe())
     type = arrayType->getElementType().getTypePtr();
   return type;
 }
 
 inline const Type *Type::getPointeeOrArrayElementType() const {
   const Type *type = this;
   if (type->isAnyPointerType())
     return type->getPointeeType().getTypePtr();
   else if (type->isArrayType())
     return type->getBaseElementTypeUnsafe();
   return type;
 }
 
 /// Insertion operator for diagnostics. This allows sending Qualifiers into a
 /// diagnostic with <<.
 inline const DiagnosticBuilder &operator<<(const DiagnosticBuilder &DB,
                                            Qualifiers Q) {
   DB.AddTaggedVal(Q.getAsOpaqueValue(),
                   DiagnosticsEngine::ArgumentKind::ak_qual);
   return DB;
 }
 
 /// Insertion operator for partial diagnostics. This allows sending Qualifiers
 /// into a diagnostic with <<.
 inline const PartialDiagnostic &operator<<(const PartialDiagnostic &PD,
                                            Qualifiers Q) {
   PD.AddTaggedVal(Q.getAsOpaqueValue(),
                   DiagnosticsEngine::ArgumentKind::ak_qual);
   return PD;
 }
 
 /// Insertion operator for diagnostics.  This allows sending QualType's into a
 /// diagnostic with <<.
 inline const DiagnosticBuilder &operator<<(const DiagnosticBuilder &DB,
                                            QualType T) {
   DB.AddTaggedVal(reinterpret_cast<intptr_t>(T.getAsOpaquePtr()),
                   DiagnosticsEngine::ak_qualtype);
   return DB;
 }
 
 /// Insertion operator for partial diagnostics.  This allows sending QualType's
 /// into a diagnostic with <<.
 inline const PartialDiagnostic &operator<<(const PartialDiagnostic &PD,
                                            QualType T) {
   PD.AddTaggedVal(reinterpret_cast<intptr_t>(T.getAsOpaquePtr()),
                   DiagnosticsEngine::ak_qualtype);
   return PD;
 }
 
 // Helper class template that is used by Type::getAs to ensure that one does
 // not try to look through a qualified type to get to an array type.
 template <typename T>
 using TypeIsArrayType =
     std::integral_constant<bool, std::is_same<T, ArrayType>::value ||
                                      std::is_base_of<ArrayType, T>::value>;
 
 // Member-template getAs<specific type>'.
 template <typename T> const T *Type::getAs() const {
   static_assert(!TypeIsArrayType<T>::value,
                 "ArrayType cannot be used with getAs!");
 
   // If this is directly a T type, return it.
   if (const auto *Ty = dyn_cast<T>(this))
     return Ty;
 
   // If the canonical form of this type isn't the right kind, reject it.
   if (!isa<T>(CanonicalType))
     return nullptr;
 
   // If this is a typedef for the type, strip the typedef off without
   // losing all typedef information.
   return cast<T>(getUnqualifiedDesugaredType());
 }
 
 template <typename T> const T *Type::getAsAdjusted() const {
   static_assert(!TypeIsArrayType<T>::value, "ArrayType cannot be used with getAsAdjusted!");
 
   // If this is directly a T type, return it.
   if (const auto *Ty = dyn_cast<T>(this))
     return Ty;
 
   // If the canonical form of this type isn't the right kind, reject it.
   if (!isa<T>(CanonicalType))
     return nullptr;
 
   // Strip off type adjustments that do not modify the underlying nature of the
   // type.
   const Type *Ty = this;
   while (Ty) {
     if (const auto *A = dyn_cast<AttributedType>(Ty))
       Ty = A->getModifiedType().getTypePtr();
     else if (const auto *E = dyn_cast<ElaboratedType>(Ty))
       Ty = E->desugar().getTypePtr();
     else if (const auto *P = dyn_cast<ParenType>(Ty))
       Ty = P->desugar().getTypePtr();
     else if (const auto *A = dyn_cast<AdjustedType>(Ty))
       Ty = A->desugar().getTypePtr();
     else
       break;
   }
 
   // Just because the canonical type is correct does not mean we can use cast<>,
   // since we may not have stripped off all the sugar down to the base type.
   return dyn_cast<T>(Ty);
 }
 
 inline const ArrayType *Type::getAsArrayTypeUnsafe() const {
   // If this is directly an array type, return it.
   if (const auto *arr = dyn_cast<ArrayType>(this))
     return arr;
 
   // If the canonical form of this type isn't the right kind, reject it.
   if (!isa<ArrayType>(CanonicalType))
     return nullptr;
 
   // If this is a typedef for the type, strip the typedef off without
   // losing all typedef information.
   return cast<ArrayType>(getUnqualifiedDesugaredType());
 }
 
 template <typename T> const T *Type::castAs() const {
   static_assert(!TypeIsArrayType<T>::value,
                 "ArrayType cannot be used with castAs!");
 
   if (const auto *ty = dyn_cast<T>(this)) return ty;
   assert(isa<T>(CanonicalType));
   return cast<T>(getUnqualifiedDesugaredType());
 }
 
 inline const ArrayType *Type::castAsArrayTypeUnsafe() const {
   assert(isa<ArrayType>(CanonicalType));
   if (const auto *arr = dyn_cast<ArrayType>(this)) return arr;
   return cast<ArrayType>(getUnqualifiedDesugaredType());
 }
 
 DecayedType::DecayedType(QualType OriginalType, QualType DecayedPtr,
                          QualType CanonicalPtr)
     : AdjustedType(Decayed, OriginalType, DecayedPtr, CanonicalPtr) {
 #ifndef NDEBUG
   QualType Adjusted = getAdjustedType();
   (void)AttributedType::stripOuterNullability(Adjusted);
   assert(isa<PointerType>(Adjusted));
 #endif
 }
 
 QualType DecayedType::getPointeeType() const {
   QualType Decayed = getDecayedType();
   (void)AttributedType::stripOuterNullability(Decayed);
   return cast<PointerType>(Decayed)->getPointeeType();
 }
 
 // Get the decimal string representation of a fixed point type, represented
 // as a scaled integer.
 void FixedPointValueToString(SmallVectorImpl<char> &Str, llvm::APSInt Val,
                              unsigned Scale);
 
 } // namespace clang
 
 #endif // LLVM_CLANG_AST_TYPE_H