EIC code displayed by LXR master/​include/​clang/​AST/​DeclBase.h	Source navigation Diff markup Identifier search General search
	Version: master test Revert   Change

File indexing completed on 2026-05-10 08:36:31

 //===- DeclBase.h - Base Classes for representing declarations --*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 //  This file defines the Decl and DeclContext interfaces.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CLANG_AST_DECLBASE_H
 #define LLVM_CLANG_AST_DECLBASE_H
 
 #include "clang/AST/ASTDumperUtils.h"
 #include "clang/AST/AttrIterator.h"
 #include "clang/AST/DeclID.h"
 #include "clang/AST/DeclarationName.h"
 #include "clang/AST/SelectorLocationsKind.h"
 #include "clang/Basic/IdentifierTable.h"
 #include "clang/Basic/LLVM.h"
 #include "clang/Basic/LangOptions.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 BlockDecl;
 class DeclContext;
 class ExternalSourceSymbolAttr;
 class FunctionDecl;
 class FunctionType;
 class IdentifierInfo;
 enum class Linkage : unsigned char;
 class LinkageSpecDecl;
 class Module;
 class NamedDecl;
 class ObjCContainerDecl;
 class ObjCMethodDecl;
 struct PrintingPolicy;
 class RecordDecl;
 class SourceManager;
 class Stmt;
 class StoredDeclsMap;
 class TemplateDecl;
 class TemplateParameterList;
 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,
 
     /// This declaration is an OpenMP user defined mapper.
     IDNS_OMPMapper           = 0x2000,
   };
 
   /// 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 char {
     /// 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, and is visible to lookups
     /// that occurs within that module. And it is reachable in other module
     /// when the owning module is transitively imported.
     ReachableWhenImported,
 
     /// This declaration has an owning module, but is only visible to
     /// lookups that occur within that module.
     /// The discarded declarations in global module fragment belongs
     /// to this group too.
     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 three bits are used for the ModuleOwnershipKind.
   llvm::PointerIntPair<Decl *, 3, 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 isa<DeclContext *>(DeclCtx); }
   bool isOutOfSemaDC() const { return isa<MultipleDC *>(DeclCtx); }
 
   MultipleDC *getMultipleDC() const { return cast<MultipleDC *>(DeclCtx); }
 
   DeclContext *getSemanticDC() const { return cast<DeclContext *>(DeclCtx); }
 
   /// Loc - The location of this decl.
   SourceLocation Loc;
 
   /// DeclKind - This indicates which class this is.
   LLVM_PREFERRED_TYPE(Kind)
   unsigned DeclKind : 7;
 
   /// InvalidDecl - This indicates a semantic error occurred.
   LLVM_PREFERRED_TYPE(bool)
   unsigned InvalidDecl :  1;
 
   /// HasAttrs - This indicates whether the decl has attributes or not.
   LLVM_PREFERRED_TYPE(bool)
   unsigned HasAttrs : 1;
 
   /// Implicit - Whether this declaration was implicitly generated by
   /// the implementation rather than explicitly written by the user.
   LLVM_PREFERRED_TYPE(bool)
   unsigned Implicit : 1;
 
   /// Whether this declaration was "used", meaning that a definition is
   /// required.
   LLVM_PREFERRED_TYPE(bool)
   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".
   LLVM_PREFERRED_TYPE(bool)
   unsigned Referenced : 1;
 
   /// Whether this declaration is a top-level declaration (function,
   /// global variable, etc.) that is lexically inside an objc container
   /// definition.
   LLVM_PREFERRED_TYPE(bool)
   unsigned TopLevelDeclInObjCContainer : 1;
 
   /// Whether statistic collection is enabled.
   static bool StatisticsEnabled;
 
 protected:
   friend class ASTDeclMerger;
   friend class ASTDeclReader;
   friend class ASTDeclWriter;
   friend class ASTNodeImporter;
   friend class ASTReader;
   friend class CXXClassMemberWrapper;
   friend class LinkageComputer;
   friend class RecordDecl;
   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
   LLVM_PREFERRED_TYPE(AccessSpecifier)
   unsigned Access : 2;
 
   /// Whether this declaration was loaded from an AST file.
   LLVM_PREFERRED_TYPE(bool)
   unsigned FromASTFile : 1;
 
   /// IdentifierNamespace - This specifies what IDNS_* namespace this lives in.
   LLVM_PREFERRED_TYPE(IdentifierNamespace)
   unsigned IdentifierNamespace : 14;
 
   /// If 0, we have not computed the linkage of this declaration.
   LLVM_PREFERRED_TYPE(Linkage)
   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, GlobalDeclID 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 AccessDeclContextCheck() 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;
   }
 
 public:
   Decl() = delete;
   Decl(const Decl&) = delete;
   Decl(Decl &&) = delete;
   Decl &operator=(const Decl&) = delete;
   Decl &operator=(Decl&&) = delete;
 
 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(llvm::to_underlying(Linkage::Invalid)) {
     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(llvm::to_underlying(Linkage::Invalid)) {
     if (StatisticsEnabled) add(DK);
   }
 
   virtual ~Decl();
 
   /// Update a potentially out-of-date declaration.
   void updateOutOfDate(IdentifierInfo &II) const;
 
   Linkage getCachedLinkage() const {
     return static_cast<Linkage>(CacheValidAndLinkage);
   }
 
   void setCachedLinkage(Linkage L) const {
     CacheValidAndLinkage = llvm::to_underlying(L);
   }
 
   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();
   }
 
   /// Return the non transparent context.
   /// See the comment of `DeclContext::isTransparentContext()` for the
   /// definition of transparent context.
   DeclContext *getNonTransparentDeclContext();
   const DeclContext *getNonTransparentDeclContext() const {
     return const_cast<Decl *>(this)->getNonTransparentDeclContext();
   }
 
   /// 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;
 
   // Return true if this is a FileContext Decl.
   bool isFileContextDecl() const;
 
   /// Whether it resembles a flexible array member. This is a static member
   /// because we want to be able to call it with a nullptr. That allows us to
   /// perform non-Decl specific checks based on the object's type and strict
   /// flex array level.
   static bool isFlexibleArrayMemberLike(
       ASTContext &Context, const Decl *D, QualType Ty,
       LangOptions::StrictFlexArraysLevelKind StrictFlexArraysLevel,
       bool IgnoreTemplateOrMacroSubstitution);
 
   ASTContext &getASTContext() const LLVM_READONLY;
 
   /// Helper to get the language options from the ASTContext.
   /// Defined out of line to avoid depending on ASTContext.h.
   const LangOptions &getLangOpts() const LLVM_READONLY;
 
   void setAccess(AccessSpecifier AS) {
     Access = AS;
     assert(AccessDeclContextCheck());
   }
 
   AccessSpecifier getAccess() const {
     assert(AccessDeclContextCheck());
     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... Ts> void dropAttrs() {
     if (!HasAttrs) return;
 
     AttrVec &Vec = getAttrs();
     llvm::erase_if(Vec, [](Attr *A) { return isa<Ts...>(A); });
 
     if (Vec.empty())
       HasAttrs = false;
   }
 
   template <typename T> void dropAttr() { dropAttrs<T>(); }
 
   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 was exported in a lexical context.
   /// e.g.:
   ///
   ///   export namespace A {
   ///      void f1();        // isInExportDeclContext() == true
   ///   }
   ///   void A::f1();        // isInExportDeclContext() == false
   ///
   ///   namespace B {
   ///      void f2();        // isInExportDeclContext() == false
   ///   }
   ///   export void B::f2(); // isInExportDeclContext() == true
   bool isInExportDeclContext() const;
 
   bool isInvisibleOutsideTheOwningModule() const {
     return getModuleOwnershipKind() > ModuleOwnershipKind::VisibleWhenImported;
   }
 
   /// Whether this declaration comes from another module unit.
   bool isInAnotherModuleUnit() const;
 
   /// Whether this declaration comes from the same module unit being compiled.
   bool isInCurrentModuleUnit() const;
 
   /// Whether the definition of the declaration should be emitted in external
   /// sources.
   bool shouldEmitInExternalSource() const;
 
   /// Whether this declaration comes from explicit global module.
   bool isFromExplicitGlobalModule() const;
 
   /// Whether this declaration comes from global module.
   bool isFromGlobalModule() const;
 
   /// Whether this declaration comes from a named module.
   bool isInNamedModule() const;
 
   /// Whether this declaration comes from a header unit.
   bool isFromHeaderUnit() 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);
   }
 
 public:
   /// Set the FromASTFile flag. This indicates that this declaration
   /// was deserialized and not parsed from source code and enables
   /// features such as module ownership information.
   void setFromASTFile() {
     FromASTFile = true;
   }
 
   /// Set the owning module ID.  This may only be called for
   /// deserialized Decls.
   void setOwningModuleID(unsigned 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.
   GlobalDeclID getGlobalID() const;
 
   /// Retrieve the global ID of the module that owns this particular
   /// declaration.
   unsigned getOwningModuleID() const;
 
 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 top level owning named module that owns this declaration if any.
   /// \returns nullptr if the declaration is not owned by a named module.
   Module *getTopLevelOwningNamedModule() const;
 
   /// Get the module that owns this declaration for linkage purposes.
   /// There only ever is such a standard C++ module.
   Module *getOwningModuleForLinkage() const;
 
   /// Determine whether this declaration is definitely visible to name lookup,
   /// independent of whether the owning module is visible.
   /// Note: The declaration may be visible even if this returns \c false if the
   /// owning module is visible within the query context. This is a low-level
   /// helper function; most code should be calling Sema::isVisible() instead.
   bool isUnconditionallyVisible() const {
     return (int)getModuleOwnershipKind() <= (int)ModuleOwnershipKind::Visible;
   }
 
   bool isReachable() const {
     return (int)getModuleOwnershipKind() <=
            (int)ModuleOwnershipKind::ReachableWhenImported;
   }
 
   /// Set that this declaration is globally visible, even if it came from a
   /// module that is not visible.
   void setVisibleDespiteOwningModule() {
     if (!isUnconditionallyVisible())
       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;
 
   /// Determine the number of levels of template parameter surrounding this
   /// declaration.
   unsigned getTemplateDepth() 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;
   }
 
   /// Determine whether a substitution into this declaration would occur as
   /// part of a substitution into a dependent local scope. Such a substitution
   /// transitively substitutes into all constructs nested within this
   /// declaration.
   ///
   /// This recognizes non-defining declarations as well as members of local
   /// classes and lambdas:
   /// \code
   ///     template<typename T> void foo() { void bar(); }
   ///     template<typename T> void foo2() { class ABC { void bar(); }; }
   ///     template<typename T> inline int x = [](){ return 0; }();
   /// \endcode
   bool isInLocalScopeForInstantiation() const;
 
   /// If this decl is defined inside a function/method/block it returns
   /// the corresponding DeclContext, otherwise it returns null.
   const DeclContext *
   getParentFunctionOrMethod(bool LexicalParent = false) const;
   DeclContext *getParentFunctionOrMethod(bool LexicalParent = false) {
     return const_cast<DeclContext *>(
         const_cast<const Decl *>(this)->getParentFunctionOrMethod(
             LexicalParent));
   }
 
   /// 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 previous 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.
   ///
   /// Note that this returns nullptr for partial specializations, because they
   /// are not modeled as TemplateDecls. Use getDescribedTemplateParams to handle
   /// those cases.
   TemplateDecl *getDescribedTemplate() const;
 
   /// If this is a declaration that describes some template or partial
   /// specialization, this returns the corresponding template parameter list.
   const TemplateParameterList *getDescribedTemplateParams() 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() const {
     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;
     }
   }
 
   /// Clears the namespace of this declaration.
   ///
   /// This is useful if we want this declaration to be available for
   /// redeclaration lookup but otherwise hidden for ordinary name lookups.
   void clearIdentifierNamespace() { IdentifierNamespace = 0; }
 
   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,
             ASTDumpOutputFormat OutputFormat = ADOF_Default) const;
 
   /// \return Unique reproducible object identifier
   int64_t getID() const;
 
   /// Looks through the Decl's underlying type to extract a FunctionType
   /// when possible. This includes direct FunctionDecls, along with various
   /// function types and typedefs. This includes function pointers/references,
   /// member function pointers, and optionally if \p BlocksToo is set
   /// Objective-C block pointers. Returns nullptr if the type underlying the
   /// Decl does not have a FunctionType.
   const FunctionType *getFunctionType(bool BlocksToo = true) const;
 
   // Looks through the Decl's underlying type to determine if it's a
   // function pointer type.
   bool isFunctionPointerType() 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;
 };
 } // namespace clang
 
 // Required to determine the layout of the PointerUnion<NamedDecl*> before
 // seeing the NamedDecl definition being first used in DeclListNode::operator*.
 namespace llvm {
   template <> struct PointerLikeTypeTraits<::clang::NamedDecl *> {
     static inline void *getAsVoidPointer(::clang::NamedDecl *P) { return P; }
     static inline ::clang::NamedDecl *getFromVoidPointer(void *P) {
       return static_cast<::clang::NamedDecl *>(P);
     }
     static constexpr int NumLowBitsAvailable = 3;
   };
 }
 
 namespace clang {
 /// A list storing NamedDecls in the lookup tables.
 class DeclListNode {
   friend class ASTContext; // allocate, deallocate nodes.
   friend class StoredDeclsList;
 public:
   using Decls = llvm::PointerUnion<NamedDecl*, DeclListNode*>;
   class iterator {
     friend class DeclContextLookupResult;
     friend class StoredDeclsList;
 
     Decls Ptr;
     iterator(Decls Node) : Ptr(Node) { }
   public:
     using difference_type = ptrdiff_t;
     using value_type = NamedDecl*;
     using pointer = void;
     using reference = value_type;
     using iterator_category = std::forward_iterator_tag;
 
     iterator() = default;
 
     reference operator*() const {
       assert(Ptr && "dereferencing end() iterator");
       if (DeclListNode *CurNode = dyn_cast<DeclListNode *>(Ptr))
         return CurNode->D;
       return cast<NamedDecl *>(Ptr);
     }
     void operator->() const { } // Unsupported.
     bool operator==(const iterator &X) const { return Ptr == X.Ptr; }
     bool operator!=(const iterator &X) const { return Ptr != X.Ptr; }
     inline iterator &operator++() { // ++It
       assert(!Ptr.isNull() && "Advancing empty iterator");
 
       if (DeclListNode *CurNode = dyn_cast<DeclListNode *>(Ptr))
         Ptr = CurNode->Rest;
       else
         Ptr = nullptr;
       return *this;
     }
     iterator operator++(int) { // It++
       iterator temp = *this;
       ++(*this);
       return temp;
     }
     // Enables the pattern for (iterator I =..., E = I.end(); I != E; ++I)
     iterator end() { return iterator(); }
   };
 private:
   NamedDecl *D = nullptr;
   Decls Rest = nullptr;
   DeclListNode(NamedDecl *ND) : D(ND) {}
 };
 
 /// The results of name lookup within a DeclContext.
 class DeclContextLookupResult {
   using Decls = DeclListNode::Decls;
 
   /// When in collection form, this is what the Data pointer points to.
   Decls Result;
 
 public:
   DeclContextLookupResult() = default;
   DeclContextLookupResult(Decls Result) : Result(Result) {}
 
   using iterator = DeclListNode::iterator;
   using const_iterator = iterator;
   using reference = iterator::reference;
 
   iterator begin() { return iterator(Result); }
   iterator end() { return iterator(); }
   const_iterator begin() const {
     return const_cast<DeclContextLookupResult*>(this)->begin();
   }
   const_iterator end() const { return iterator(); }
 
   bool empty() const { return Result.isNull();  }
   bool isSingleResult() const { return isa_and_present<NamedDecl *>(Result); }
   reference front() const { return *begin(); }
 
   // Find the first declaration of the given type in the list. Note that this
   // is not in general the earliest-declared declaration, and should only be
   // used when it's not possible for there to be more than one match or where
   // it doesn't matter which one is found.
   template<class T> T *find_first() const {
     for (auto *D : *this)
       if (T *Decl = dyn_cast<T>(D))
         return Decl;
 
     return nullptr;
   }
 };
 
 /// Only used by CXXDeductionGuideDecl.
 enum class DeductionCandidate : unsigned char {
   Normal,
   Copy,
   Aggregate,
 };
 
 enum class RecordArgPassingKind;
 enum class OMPDeclareReductionInitKind;
 enum class ObjCImplementationControl;
 enum class LinkageSpecLanguageIDs;
 
 /// 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
 ///   OMPDeclareMapperDecl
 ///   FunctionDecl
 ///   ObjCMethodDecl
 ///   ObjCContainerDecl
 ///   LinkageSpecDecl
 ///   ExportDecl
 ///   BlockDecl
 ///   CapturedDecl
 class DeclContext {
   /// For makeDeclVisibleInContextImpl
   friend class ASTDeclReader;
   /// For checking the new bits in the Serialization part.
   friend class ASTDeclWriter;
   /// For reconcileExternalVisibleStorage, CreateStoredDeclsMap,
   /// hasNeedToReconcileExternalVisibleStorage
   friend class ExternalASTSource;
   /// For CreateStoredDeclsMap
   friend class DependentDiagnostic;
   /// For hasNeedToReconcileExternalVisibleStorage,
   /// hasLazyLocalLexicalLookups, hasLazyExternalLexicalLookups
   friend class ASTWriter;
 
 protected:
   enum { NumOdrHashBits = 25 };
 
   // 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.
     LLVM_PREFERRED_TYPE(Decl::Kind)
     uint64_t DeclKind : 7;
 
     /// Whether this declaration context also has some external
     /// storage that contains additional declarations that are lexically
     /// part of this context.
     LLVM_PREFERRED_TYPE(bool)
     mutable uint64_t ExternalLexicalStorage : 1;
 
     /// Whether this declaration context also has some external
     /// storage that contains additional declarations that are visible
     /// in this context.
     LLVM_PREFERRED_TYPE(bool)
     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.
     LLVM_PREFERRED_TYPE(bool)
     mutable uint64_t NeedToReconcileExternalVisibleStorage : 1;
 
     /// If \c true, this context may have local lexical declarations
     /// that are missing from the lookup table.
     LLVM_PREFERRED_TYPE(bool)
     mutable uint64_t HasLazyLocalLexicalLookups : 1;
 
     /// If \c true, the external source may have lexical declarations
     /// that are missing from the lookup table.
     LLVM_PREFERRED_TYPE(bool)
     mutable uint64_t HasLazyExternalLexicalLookups : 1;
 
     /// If \c true, lookups should only return identifier from
     /// DeclContext scope (for example TranslationUnit). Used in
     /// LookupQualifiedName()
     LLVM_PREFERRED_TYPE(bool)
     mutable uint64_t UseQualifiedLookup : 1;
   };
 
   /// Number of bits in DeclContextBitfields.
   enum { NumDeclContextBits = 13 };
 
   /// Stores the bits used by NamespaceDecl.
   /// If modified NumNamespaceDeclBits and the accessor
   /// methods in NamespaceDecl should be updated appropriately.
   class NamespaceDeclBitfields {
     friend class NamespaceDecl;
     /// For the bits in DeclContextBitfields
     LLVM_PREFERRED_TYPE(DeclContextBitfields)
     uint64_t : NumDeclContextBits;
 
     /// True if this is an inline namespace.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsInline : 1;
 
     /// True if this is a nested-namespace-definition.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsNested : 1;
   };
 
   /// Number of inherited and non-inherited bits in NamespaceDeclBitfields.
   enum { NumNamespaceDeclBits = NumDeclContextBits + 2 };
 
   /// 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
     LLVM_PREFERRED_TYPE(DeclContextBitfields)
     uint64_t : NumDeclContextBits;
 
     /// The TagKind enum.
     LLVM_PREFERRED_TYPE(TagTypeKind)
     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.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsCompleteDefinition : 1;
 
     /// True if this is currently being defined.
     LLVM_PREFERRED_TYPE(bool)
     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.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsEmbeddedInDeclarator : 1;
 
     /// True if this tag is free standing, e.g. "struct foo;".
     LLVM_PREFERRED_TYPE(bool)
     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.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t MayHaveOutOfDateDef : 1;
 
     /// Has the full definition of this type been required by a use somewhere in
     /// the TU.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsCompleteDefinitionRequired : 1;
 
     /// Whether this tag is a definition which was demoted due to
     /// a module merge.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsThisDeclarationADemotedDefinition : 1;
   };
 
   /// Number of inherited and non-inherited bits in TagDeclBitfields.
   enum { NumTagDeclBits = NumDeclContextBits + 10 };
 
   /// 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 TagDeclBitfields.
     LLVM_PREFERRED_TYPE(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.
     LLVM_PREFERRED_TYPE(bool)
     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.
     LLVM_PREFERRED_TYPE(bool)
     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.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsFixed : 1;
 
     /// True if a valid hash is stored in ODRHash.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t HasODRHash : 1;
   };
 
   /// Number of inherited and non-inherited bits in EnumDeclBitfields.
   enum { NumEnumDeclBits = NumTagDeclBits + 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 TagDeclBitfields.
     LLVM_PREFERRED_TYPE(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.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t HasFlexibleArrayMember : 1;
 
     /// Whether this is the type of an anonymous struct or union.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t AnonymousStructOrUnion : 1;
 
     /// This is true if this struct has at least one member
     /// containing an Objective-C object pointer type.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t HasObjectMember : 1;
 
     /// This is true if struct has at least one member of
     /// 'volatile' type.
     LLVM_PREFERRED_TYPE(bool)
     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.
     LLVM_PREFERRED_TYPE(bool)
     mutable uint64_t LoadedFieldsFromExternalStorage : 1;
 
     /// Basic properties of non-trivial C structs.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t NonTrivialToPrimitiveDefaultInitialize : 1;
     LLVM_PREFERRED_TYPE(bool)
     uint64_t NonTrivialToPrimitiveCopy : 1;
     LLVM_PREFERRED_TYPE(bool)
     uint64_t NonTrivialToPrimitiveDestroy : 1;
 
     /// The following bits indicate whether this is or contains a C union that
     /// is non-trivial to default-initialize, destruct, or copy. These bits
     /// imply the associated basic non-triviality predicates declared above.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t HasNonTrivialToPrimitiveDefaultInitializeCUnion : 1;
     LLVM_PREFERRED_TYPE(bool)
     uint64_t HasNonTrivialToPrimitiveDestructCUnion : 1;
     LLVM_PREFERRED_TYPE(bool)
     uint64_t HasNonTrivialToPrimitiveCopyCUnion : 1;
 
     /// True if any field is marked as requiring explicit initialization with
     /// [[clang::require_explicit_initialization]].
     /// In C++, this is also set for types without a user-provided default
     /// constructor, and is propagated from any base classes and/or member
     /// variables whose types are aggregates.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t HasUninitializedExplicitInitFields : 1;
 
     /// Indicates whether this struct is destroyed in the callee.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t ParamDestroyedInCallee : 1;
 
     /// Represents the way this type is passed to a function.
     LLVM_PREFERRED_TYPE(RecordArgPassingKind)
     uint64_t ArgPassingRestrictions : 2;
 
     /// Indicates whether this struct has had its field layout randomized.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsRandomized : 1;
 
     /// True if a valid hash is stored in ODRHash. This should shave off some
     /// extra storage and prevent CXXRecordDecl to store unused bits.
     uint64_t ODRHash : NumOdrHashBits;
   };
 
   /// Number of inherited and non-inherited bits in RecordDeclBitfields.
   enum { NumRecordDeclBits = NumTagDeclBits + 41 };
 
   /// 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
     LLVM_PREFERRED_TYPE(DeclContextBitfields)
     uint64_t : NumDeclContextBits;
 
     /// Kind of initializer,
     /// function call or omp_priv<init_expr> initialization.
     LLVM_PREFERRED_TYPE(OMPDeclareReductionInitKind)
     uint64_t InitializerKind : 2;
   };
 
   /// Number of inherited and non-inherited bits in
   /// OMPDeclareReductionDeclBitfields.
   enum { NumOMPDeclareReductionDeclBits = NumDeclContextBits + 2 };
 
   /// Stores the bits used by FunctionDecl.
   /// If modified NumFunctionDeclBits and the accessor
   /// methods in FunctionDecl and CXXDeductionGuideDecl
   /// (for DeductionCandidateKind) should be updated appropriately.
   class FunctionDeclBitfields {
     friend class FunctionDecl;
     /// For DeductionCandidateKind
     friend class CXXDeductionGuideDecl;
     /// For the bits in DeclContextBitfields.
     LLVM_PREFERRED_TYPE(DeclContextBitfields)
     uint64_t : NumDeclContextBits;
 
     LLVM_PREFERRED_TYPE(StorageClass)
     uint64_t SClass : 3;
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsInline : 1;
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsInlineSpecified : 1;
 
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsVirtualAsWritten : 1;
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsPureVirtual : 1;
     LLVM_PREFERRED_TYPE(bool)
     uint64_t HasInheritedPrototype : 1;
     LLVM_PREFERRED_TYPE(bool)
     uint64_t HasWrittenPrototype : 1;
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsDeleted : 1;
     /// Used by CXXMethodDecl
     LLVM_PREFERRED_TYPE(bool)
     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.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsTrivialForCall : 1;
 
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsDefaulted : 1;
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsExplicitlyDefaulted : 1;
     LLVM_PREFERRED_TYPE(bool)
     uint64_t HasDefaultedOrDeletedInfo : 1;
 
     /// For member functions of complete types, whether this is an ineligible
     /// special member function or an unselected destructor. See
     /// [class.mem.special].
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsIneligibleOrNotSelected : 1;
 
     LLVM_PREFERRED_TYPE(bool)
     uint64_t HasImplicitReturnZero : 1;
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsLateTemplateParsed : 1;
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsInstantiatedFromMemberTemplate : 1;
 
     /// Kind of contexpr specifier as defined by ConstexprSpecKind.
     LLVM_PREFERRED_TYPE(ConstexprSpecKind)
     uint64_t ConstexprKind : 2;
     LLVM_PREFERRED_TYPE(bool)
     uint64_t BodyContainsImmediateEscalatingExpression : 1;
 
     LLVM_PREFERRED_TYPE(bool)
     uint64_t InstantiationIsPending : 1;
 
     /// Indicates if the function uses __try.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t UsesSEHTry : 1;
 
     /// Indicates if the function was a definition
     /// but its body was skipped.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t HasSkippedBody : 1;
 
     /// Indicates if the function declaration will
     /// have a body, once we're done parsing it.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t WillHaveBody : 1;
 
     /// Indicates that this function is a multiversioned
     /// function using attribute 'target'.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsMultiVersion : 1;
 
     /// Only used by CXXDeductionGuideDecl. Indicates the kind
     /// of the Deduction Guide that is implicitly generated
     /// (used during overload resolution).
     LLVM_PREFERRED_TYPE(DeductionCandidate)
     uint64_t DeductionCandidateKind : 2;
 
     /// Store the ODRHash after first calculation.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t HasODRHash : 1;
 
     /// Indicates if the function uses Floating Point Constrained Intrinsics
     LLVM_PREFERRED_TYPE(bool)
     uint64_t UsesFPIntrin : 1;
 
     // Indicates this function is a constrained friend, where the constraint
     // refers to an enclosing template for hte purposes of [temp.friend]p9.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t FriendConstraintRefersToEnclosingTemplate : 1;
   };
 
   /// Number of inherited and non-inherited bits in FunctionDeclBitfields.
   enum { NumFunctionDeclBits = NumDeclContextBits + 32 };
 
   /// 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 FunctionDeclBitfields.
     LLVM_PREFERRED_TYPE(FunctionDeclBitfields)
     uint64_t : NumFunctionDeclBits;
 
     /// 19 bits to fit in the remaining available 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 : 16;
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsInheritingConstructor : 1;
 
     /// Whether this constructor has a trail-allocated explicit specifier.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t HasTrailingExplicitSpecifier : 1;
     /// If this constructor does't have a trail-allocated explicit specifier.
     /// Whether this constructor is explicit specified.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsSimpleExplicit : 1;
   };
 
   /// Number of inherited and non-inherited bits in CXXConstructorDeclBitfields.
   enum { NumCXXConstructorDeclBits = NumFunctionDeclBits + 19 };
 
   /// 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.
     LLVM_PREFERRED_TYPE(DeclContextBitfields)
     uint64_t : NumDeclContextBits;
 
     /// The conventional meaning of this method; an ObjCMethodFamily.
     /// This is not serialized; instead, it is computed on demand and
     /// cached.
     LLVM_PREFERRED_TYPE(ObjCMethodFamily)
     mutable uint64_t Family : ObjCMethodFamilyBitWidth;
 
     /// instance (true) or class (false) method.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsInstance : 1;
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsVariadic : 1;
 
     /// True if this method is the getter or setter for an explicit property.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsPropertyAccessor : 1;
 
     /// True if this method is a synthesized property accessor stub.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsSynthesizedAccessorStub : 1;
 
     /// Method has a definition.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsDefined : 1;
 
     /// Method redeclaration in the same interface.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsRedeclaration : 1;
 
     /// Is redeclared in the same interface.
     LLVM_PREFERRED_TYPE(bool)
     mutable uint64_t HasRedeclaration : 1;
 
     /// \@required/\@optional
     LLVM_PREFERRED_TYPE(ObjCImplementationControl)
     uint64_t DeclImplementation : 2;
 
     /// in, inout, etc.
     LLVM_PREFERRED_TYPE(Decl::ObjCDeclQualifier)
     uint64_t objcDeclQualifier : 7;
 
     /// Indicates whether this method has a related result type.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t RelatedResultType : 1;
 
     /// Whether the locations of the selector identifiers are in a
     /// "standard" position, a enum SelectorLocationsKind.
     LLVM_PREFERRED_TYPE(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.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsOverriding : 1;
 
     /// Indicates if the method was a definition but its body was skipped.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t HasSkippedBody : 1;
   };
 
   /// Number of inherited and non-inherited bits in ObjCMethodDeclBitfields.
   enum { NumObjCMethodDeclBits = NumDeclContextBits + 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
     LLVM_PREFERRED_TYPE(DeclContextBitfields)
     uint32_t : NumDeclContextBits;
 
     // Not a bitfield but this saves space.
     // Note that ObjCContainerDeclBitfields is full.
     SourceLocation AtStart;
   };
 
   /// Number of inherited and 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 };
 
   /// 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.
     LLVM_PREFERRED_TYPE(DeclContextBitfields)
     uint64_t : NumDeclContextBits;
 
     /// The language for this linkage specification.
     LLVM_PREFERRED_TYPE(LinkageSpecLanguageIDs)
     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.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t HasBraces : 1;
   };
 
   /// Number of inherited and non-inherited bits in LinkageSpecDeclBitfields.
   enum { NumLinkageSpecDeclBits = NumDeclContextBits + 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.
     LLVM_PREFERRED_TYPE(DeclContextBitfields)
     uint64_t : NumDeclContextBits;
 
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsVariadic : 1;
     LLVM_PREFERRED_TYPE(bool)
     uint64_t CapturesCXXThis : 1;
     LLVM_PREFERRED_TYPE(bool)
     uint64_t BlockMissingReturnType : 1;
     LLVM_PREFERRED_TYPE(bool)
     uint64_t IsConversionFromLambda : 1;
 
     /// A bit that indicates this block is passed directly to a function as a
     /// non-escaping parameter.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t DoesNotEscape : 1;
 
     /// A bit that indicates whether it's possible to avoid coying this block to
     /// the heap when it initializes or is assigned to a local variable with
     /// automatic storage.
     LLVM_PREFERRED_TYPE(bool)
     uint64_t CanAvoidCopyToHeap : 1;
   };
 
   /// Number of inherited and non-inherited bits in BlockDeclBitfields.
   enum { NumBlockDeclBits = NumDeclContextBits + 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;
     NamespaceDeclBitfields NamespaceDeclBits;
     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(NamespaceDeclBitfields) <= 8,
                   "NamespaceDeclBitfields 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();
 
   // For use when debugging; hasValidDeclKind() will always return true for
   // a correctly constructed object within its lifetime.
   bool hasValidDeclKind() const;
 
   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; }
 
   /// Return this DeclContext if it is a BlockDecl. Otherwise, return the
   /// innermost enclosing BlockDecl or null if there are no enclosing blocks.
   const BlockDecl *getInnermostBlockDecl() const;
 
   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:
     case Decl::TopLevelStmt:
       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 isRequiresExprBody() const {
     return getDeclKind() == Decl::RequiresExprBody;
   }
 
   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), C++ linkage specifications and export declaration.
   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();
   }
 
   // Retrieve the nearest context that is not a transparent context.
   DeclContext *getNonTransparentContext();
   const DeclContext *getNonTransparentContext() const {
     return const_cast<DeclContext *>(this)->getNonTransparentContext();
   }
 
   /// 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,
                                   typename lookup_iterator::iterator_category,
                                   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);
   }
 
   void setUseQualifiedLookup(bool use = true) const {
     DeclContextBits.UseQualifiedLookup = use;
   }
 
   bool shouldUseQualifiedLookup() const {
     return DeclContextBits.UseQualifiedLookup;
   }
 
   static bool classof(const Decl *D);
   static bool classof(const DeclContext *D) { return true; }
 
   void dumpAsDecl() const;
   void dumpAsDecl(const ASTContext *Ctx) const;
   void dumpDeclContext() const;
   void dumpLookups() const;
   void dumpLookups(llvm::raw_ostream &OS, bool DumpDecls = false,
                    bool Deserialize = false) const;
 
 private:
   lookup_result lookupImpl(DeclarationName Name,
                            const DeclContext *OriginalLookupDC) const;
 
   /// 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;
 
   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

This page was automatically generated by the 2.3.7 LXR engine. The LXR team