text: //===--- Decl.h - Classes for representing declarations ---------*- C++ -*-===//
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is distributed under the University of Illinois Open Source
  // License. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  //
  //  This file defines the Decl subclasses.
  //
  //===----------------------------------------------------------------------===//
  
  #ifndef LLVM_CLANG_AST_DECL_H
  #define LLVM_CLANG_AST_DECL_H
  
  #include "clang/AST/APValue.h"
  #include "clang/AST/DeclBase.h"
  #include "clang/AST/DeclarationName.h"
  #include "clang/AST/ExternalASTSource.h"
  #include "clang/AST/Redeclarable.h"
  #include "clang/AST/Type.h"
  #include "clang/Basic/Linkage.h"
  #include "clang/Basic/OperatorKinds.h"
  #include "llvm/ADT/ArrayRef.h"
  #include "llvm/ADT/Optional.h"
  #include "llvm/Support/Compiler.h"
  #include "llvm/Support/raw_ostream.h"
  
  namespace clang {
  struct ASTTemplateArgumentListInfo;
  class CXXTemporary;
  class CompoundStmt;
  class DependentFunctionTemplateSpecializationInfo;
  class Expr;
  class FunctionTemplateDecl;
  class FunctionTemplateSpecializationInfo;
  class LabelStmt;
  class MemberSpecializationInfo;
  class Module;
  class NestedNameSpecifier;
  class Stmt;
  class StringLiteral;
  class TemplateArgumentList;
  class TemplateParameterList;
  class TypeAliasTemplateDecl;
  class TypeLoc;
  class UnresolvedSetImpl;
  class VarTemplateDecl;
  
  /// \brief A container of type source information.
  ///
  /// A client can read the relevant info using TypeLoc wrappers, e.g:
  /// @code
  /// TypeLoc TL = TypeSourceInfo->getTypeLoc();
  /// TL.getStartLoc().print(OS, SrcMgr);
  /// @endcode
  ///
  class TypeSourceInfo {
    QualType Ty;
    // Contains a memory block after the class, used for type source information,
    // allocated by ASTContext.
    friend class ASTContext;
    TypeSourceInfo(QualType ty) : Ty(ty) { }
  public:
    /// \brief Return the type wrapped by this type source info.
    QualType getType() const { return Ty; }
  
    /// \brief Return the TypeLoc wrapper for the type source info.
    TypeLoc getTypeLoc() const; // implemented in TypeLoc.h
    
    /// \brief Override the type stored in this TypeSourceInfo. Use with caution!
    void overrideType(QualType T) { Ty = T; }
  };
  
  /// TranslationUnitDecl - The top declaration context.
  class TranslationUnitDecl : public Decl, public DeclContext {
    virtual void anchor();
    ASTContext &Ctx;
  
    /// The (most recently entered) anonymous namespace for this
    /// translation unit, if one has been created.
    NamespaceDecl *AnonymousNamespace;
  
    explicit TranslationUnitDecl(ASTContext &ctx)
      : Decl(TranslationUnit, nullptr, SourceLocation()),
        DeclContext(TranslationUnit),
        Ctx(ctx), AnonymousNamespace(nullptr) {}
  public:
    ASTContext &getASTContext() const { return Ctx; }
  
    NamespaceDecl *getAnonymousNamespace() const { return AnonymousNamespace; }
    void setAnonymousNamespace(NamespaceDecl *D) { AnonymousNamespace = D; }
  
    static TranslationUnitDecl *Create(ASTContext &C);
    // Implement isa/cast/dyncast/etc.
    static bool classof(const Decl *D) { return classofKind(D->getKind()); }
    static bool classofKind(Kind K) { return K == TranslationUnit; }
    static DeclContext *castToDeclContext(const TranslationUnitDecl *D) {
      return static_cast<DeclContext *>(const_cast<TranslationUnitDecl*>(D));
    }
    static TranslationUnitDecl *castFromDeclContext(const DeclContext *DC) {
      return static_cast<TranslationUnitDecl *>(const_cast<DeclContext*>(DC));
    }
  };
  
  /// NamedDecl - This represents a decl with a name.  Many decls have names such
  /// as ObjCMethodDecl, but not \@class, etc.
  class NamedDecl : public Decl {
    virtual void anchor();
    /// Name - The name of this declaration, which is typically a normal
    /// identifier but may also be a special kind of name (C++
    /// constructor, Objective-C selector, etc.)
    DeclarationName Name;
  
  private:
    NamedDecl *getUnderlyingDeclImpl() LLVM_READONLY;
  
  protected:
    NamedDecl(Kind DK, DeclContext *DC, SourceLocation L, DeclarationName N)
      : Decl(DK, DC, L), Name(N) { }
  
  public:
    /// getIdentifier - Get the identifier that names this declaration,
    /// if there is one. This will return NULL if this declaration has
    /// no name (e.g., for an unnamed class) or if the name is a special
    /// name (C++ constructor, Objective-C selector, etc.).
    IdentifierInfo *getIdentifier() const { return Name.getAsIdentifierInfo(); }
  
    /// getName - Get the name of identifier for this declaration as a StringRef.
    /// This requires that the declaration have a name and that it be a simple
    /// identifier.
    StringRef getName() const {
      assert(Name.isIdentifier() && "Name is not a simple identifier");
      return getIdentifier() ? getIdentifier()->getName() : "";
    }
  
    /// getNameAsString - Get a human-readable name for the declaration, even if
    /// it is one of the special kinds of names (C++ constructor, Objective-C
    /// selector, etc).  Creating this name requires expensive string
    /// manipulation, so it should be called only when performance doesn't matter.
    /// For simple declarations, getNameAsCString() should suffice.
    //
    // FIXME: This function should be renamed to indicate that it is not just an
    // alternate form of getName(), and clients should move as appropriate.
    //
    // FIXME: Deprecated, move clients to getName().
    std::string getNameAsString() const { return Name.getAsString(); }
  
    void printName(raw_ostream &os) const { os << Name; }
  
    /// getDeclName - Get the actual, stored name of the declaration,
    /// which may be a special name.
    DeclarationName getDeclName() const { return Name; }
  
    /// \brief Set the name of this declaration.
    void setDeclName(DeclarationName N) { Name = N; }
  
    /// printQualifiedName - Returns human-readable qualified name for
    /// declaration, like A::B::i, for i being member of namespace A::B.
    /// If declaration is not member of context which can be named (record,
    /// namespace), it will return same result as printName().
    /// Creating this name is expensive, so it should be called only when
    /// performance doesn't matter.
    void printQualifiedName(raw_ostream &OS) const;
    void printQualifiedName(raw_ostream &OS, const PrintingPolicy &Policy) const;
  
    // FIXME: Remove string version.
    std::string getQualifiedNameAsString() const;
  
    /// getNameForDiagnostic - Appends a human-readable name for this
    /// declaration into the given stream.
    ///
    /// This is the method invoked by Sema when displaying a NamedDecl
    /// in a diagnostic.  It does not necessarily produce the same
    /// result as printName(); for example, class template
    /// specializations are printed with their template arguments.
    virtual void getNameForDiagnostic(raw_ostream &OS,
                                      const PrintingPolicy &Policy,
                                      bool Qualified) const;
  
    /// declarationReplaces - Determine whether this declaration, if
    /// known to be well-formed within its context, will replace the
    /// declaration OldD if introduced into scope. A declaration will
    /// replace another declaration if, for example, it is a
    /// redeclaration of the same variable or function, but not if it is
    /// a declaration of a different kind (function vs. class) or an
    /// overloaded function.
    bool declarationReplaces(NamedDecl *OldD) const;
  
    /// \brief Determine whether this declaration has linkage.
    bool hasLinkage() const;
  
    using Decl::isModulePrivate;
    using Decl::setModulePrivate;
  
    /// \brief Determine whether this declaration is hidden from name lookup.
    bool isHidden() const { return Hidden; }
  
    /// \brief Set whether this declaration is hidden from name lookup.
    void setHidden(bool Hide) { Hidden = Hide; }
  
    /// \brief Determine whether this declaration is a C++ class member.
    bool isCXXClassMember() const {
      const DeclContext *DC = getDeclContext();
  
      // C++0x [class.mem]p1:
      //   The enumerators of an unscoped enumeration defined in
      //   the class are members of the class.
      if (isa<EnumDecl>(DC))
        DC = DC->getRedeclContext();
  
      return DC->isRecord();
    }
  
    /// \brief Determine whether the given declaration is an instance member of
    /// a C++ class.
    bool isCXXInstanceMember() const;
  
    /// \brief Determine what kind of linkage this entity has.
    /// This is not the linkage as defined by the standard or the codegen notion
    /// of linkage. It is just an implementation detail that is used to compute
    /// those.
    Linkage getLinkageInternal() const;
  
    /// \brief Get the linkage from a semantic point of view. Entities in
    /// anonymous namespaces are external (in c++98).
    Linkage getFormalLinkage() const {
      return clang::getFormalLinkage(getLinkageInternal());
    }
  
    /// \brief True if this decl has external linkage.
    bool hasExternalFormalLinkage() const {
      return isExternalFormalLinkage(getLinkageInternal());
    }
  
    bool isExternallyVisible() const {
      return clang::isExternallyVisible(getLinkageInternal());
    }
  
    /// \brief Determines the visibility of this entity.
    Visibility getVisibility() const {
      return getLinkageAndVisibility().getVisibility();
    }
  
    /// \brief Determines the linkage and visibility of this entity.
    LinkageInfo getLinkageAndVisibility() const;
  
    /// Kinds of explicit visibility.
    enum ExplicitVisibilityKind {
      VisibilityForType,
      VisibilityForValue
    };
  
    /// \brief If visibility was explicitly specified for this
    /// declaration, return that visibility.
    Optional<Visibility>
    getExplicitVisibility(ExplicitVisibilityKind kind) const;
  
    /// \brief True if the computed linkage is valid. Used for consistency
    /// checking. Should always return true.
    bool isLinkageValid() const;
  
    /// \brief True if something has required us to compute the linkage
    /// of this declaration.
    ///
    /// Language features which can retroactively change linkage (like a
    /// typedef name for linkage purposes) may need to consider this,
    /// but hopefully only in transitory ways during parsing.
    bool hasLinkageBeenComputed() const {
      return hasCachedLinkage();
    }
  
    /// \brief Looks through UsingDecls and ObjCCompatibleAliasDecls for
    /// the underlying named decl.
    NamedDecl *getUnderlyingDecl() {
      // Fast-path the common case.
      if (this->getKind() != UsingShadow &&
          this->getKind() != ObjCCompatibleAlias)
        return this;
  
      return getUnderlyingDeclImpl();
    }
    const NamedDecl *getUnderlyingDecl() const {
      return const_cast<NamedDecl*>(this)->getUnderlyingDecl();
    }
  
    NamedDecl *getMostRecentDecl() {
      return cast<NamedDecl>(static_cast<Decl *>(this)->getMostRecentDecl());
    }
    const NamedDecl *getMostRecentDecl() const {
      return const_cast<NamedDecl*>(this)->getMostRecentDecl();
    }
  
    ObjCStringFormatFamily getObjCFStringFormattingFamily() const;
  
    static bool classof(const Decl *D) { return classofKind(D->getKind()); }
    static bool classofKind(Kind K) { return K >= firstNamed && K <= lastNamed; }
  };
  
  inline raw_ostream &operator<<(raw_ostream &OS, const NamedDecl &ND) {
    ND.printName(OS);
    return OS;
  }
  
  /// LabelDecl - Represents the declaration of a label.  Labels also have a
  /// corresponding LabelStmt, which indicates the position that the label was
  /// defined at.  For normal labels, the location of the decl is the same as the
  /// location of the statement.  For GNU local labels (__label__), the decl
  /// location is where the __label__ is.
  class LabelDecl : public NamedDecl {
    void anchor() override;
    LabelStmt *TheStmt;
    StringRef MSAsmName;
    bool MSAsmNameResolved;
    /// LocStart - For normal labels, this is the same as the main declaration
    /// label, i.e., the location of the identifier; for GNU local labels,
    /// this is the location of the __label__ keyword.
    SourceLocation LocStart;
  
    LabelDecl(DeclContext *DC, SourceLocation IdentL, IdentifierInfo *II,
              LabelStmt *S, SourceLocation StartL)
      : NamedDecl(Label, DC, IdentL, II),
        TheStmt(S),
        MSAsmNameResolved(false),
        LocStart(StartL) {}
  
  public:
    static LabelDecl *Create(ASTContext &C, DeclContext *DC,
                             SourceLocation IdentL, IdentifierInfo *II);
    static LabelDecl *Create(ASTContext &C, DeclContext *DC,
                             SourceLocation IdentL, IdentifierInfo *II,
                             SourceLocation GnuLabelL);
    static LabelDecl *CreateDeserialized(ASTContext &C, unsigned ID);
    
    LabelStmt *getStmt() const { return TheStmt; }
    void setStmt(LabelStmt *T) { TheStmt = T; }
  
    bool isGnuLocal() const { return LocStart != getLocation(); }
    void setLocStart(SourceLocation L) { LocStart = L; }
  
    SourceRange getSourceRange() const override LLVM_READONLY {
      return SourceRange(LocStart, getLocation());
    }
  
    bool isMSAsmLabel() const { return MSAsmName.size() != 0; }
    bool isResolvedMSAsmLabel() const { return isMSAsmLabel() && MSAsmNameResolved; }
    void setMSAsmLabel(StringRef Name);
    StringRef getMSAsmLabel() const { return MSAsmName; }
    void setMSAsmLabelResolved() { MSAsmNameResolved = true; }
  
    // Implement isa/cast/dyncast/etc.
    static bool classof(const Decl *D) { return classofKind(D->getKind()); }
    static bool classofKind(Kind K) { return K == Label; }
  };
  
  /// NamespaceDecl - Represent a C++ namespace.
  class NamespaceDecl : public NamedDecl, public DeclContext, 
                        public Redeclarable<NamespaceDecl> 
  {
    /// LocStart - The starting location of the source range, pointing
    /// to either the namespace or the inline keyword.
    SourceLocation LocStart;
    /// RBraceLoc - The ending location of the source range.
    SourceLocation RBraceLoc;
  
    /// \brief A pointer to either the anonymous namespace that lives just inside
    /// this namespace or to the first namespace in the chain (the latter case
    /// only when this is not the first in the chain), along with a 
    /// boolean value indicating whether this is an inline namespace.
    llvm::PointerIntPair<NamespaceDecl *, 1, bool> AnonOrFirstNamespaceAndInline;
  
    NamespaceDecl(ASTContext &C, DeclContext *DC, bool Inline,
                  SourceLocation StartLoc, SourceLocation IdLoc,
                  IdentifierInfo *Id, NamespaceDecl *PrevDecl);
  
    typedef Redeclarable<NamespaceDecl> redeclarable_base;
    NamespaceDecl *getNextRedeclarationImpl() override;
    NamespaceDecl *getPreviousDeclImpl() override;
    NamespaceDecl *getMostRecentDeclImpl() override;
  
  public:
    static NamespaceDecl *Create(ASTContext &C, DeclContext *DC,
                                 bool Inline, SourceLocation StartLoc,
                                 SourceLocation IdLoc, IdentifierInfo *Id,
                                 NamespaceDecl *PrevDecl);
  
    static NamespaceDecl *CreateDeserialized(ASTContext &C, unsigned ID);
  
    typedef redeclarable_base::redecl_range redecl_range;
    typedef redeclarable_base::redecl_iterator redecl_iterator;
    using redeclarable_base::redecls_begin;
    using redeclarable_base::redecls_end;
    using redeclarable_base::redecls;
    using redeclarable_base::getPreviousDecl;
    using redeclarable_base::getMostRecentDecl;
    using redeclarable_base::isFirstDecl;
  
    /// \brief Returns true if this is an anonymous namespace declaration.
    ///
    /// For example:
    /// \code
    ///   namespace {
    ///     ...
    ///   };
    /// \endcode
    /// q.v. C++ [namespace.unnamed]
    bool isAnonymousNamespace() const {
      return !getIdentifier();
    }
  
    /// \brief Returns true if this is an inline namespace declaration.
    bool isInline() const {
      return AnonOrFirstNamespaceAndInline.getInt();
    }
  
    /// \brief Set whether this is an inline namespace declaration.
    void setInline(bool Inline) {
      AnonOrFirstNamespaceAndInline.setInt(Inline);
    }
  
    /// \brief Get the original (first) namespace declaration.
    NamespaceDecl *getOriginalNamespace() {
      if (isFirstDecl())
        return this;
  
      return AnonOrFirstNamespaceAndInline.getPointer();
    }
  
    /// \brief Get the original (first) namespace declaration.
    const NamespaceDecl *getOriginalNamespace() const {
      if (isFirstDecl())
        return this;
  
      return AnonOrFirstNamespaceAndInline.getPointer();
    }
  
    /// \brief Return true if this declaration is an original (first) declaration
    /// of the namespace. This is false for non-original (subsequent) namespace
    /// declarations and anonymous namespaces.
    bool isOriginalNamespace() const { return isFirstDecl(); }
  
    /// \brief Retrieve the anonymous namespace nested inside this namespace,
    /// if any.
    NamespaceDecl *getAnonymousNamespace() const {
      return getOriginalNamespace()->AnonOrFirstNamespaceAndInline.getPointer();
    }
  
    void setAnonymousNamespace(NamespaceDecl *D) {
      getOriginalNamespace()->AnonOrFirstNamespaceAndInline.setPointer(D);
    }
  
    /// Retrieves the canonical declaration of this namespace.
    NamespaceDecl *getCanonicalDecl() override {
      return getOriginalNamespace();
    }
    const NamespaceDecl *getCanonicalDecl() const {
      return getOriginalNamespace();
    }
  
    SourceRange getSourceRange() const override LLVM_READONLY {
      return SourceRange(LocStart, RBraceLoc);
    }
  
    SourceLocation getLocStart() const LLVM_READONLY { return LocStart; }
    SourceLocation getRBraceLoc() const { return RBraceLoc; }
    void setLocStart(SourceLocation L) { LocStart = L; }
    void setRBraceLoc(SourceLocation L) { RBraceLoc = L; }
  
    // Implement isa/cast/dyncast/etc.
    static bool classof(const Decl *D) { return classofKind(D->getKind()); }
    static bool classofKind(Kind K) { return K == Namespace; }
    static DeclContext *castToDeclContext(const NamespaceDecl *D) {
      return static_cast<DeclContext *>(const_cast<NamespaceDecl*>(D));
    }
    static NamespaceDecl *castFromDeclContext(const DeclContext *DC) {
      return static_cast<NamespaceDecl *>(const_cast<DeclContext*>(DC));
    }
  
    friend class ASTDeclReader;
    friend class ASTDeclWriter;
  };
  
  /// ValueDecl - Represent the declaration of a variable (in which case it is
  /// an lvalue) a function (in which case it is a function designator) or
  /// an enum constant.
  class ValueDecl : public NamedDecl {
    void anchor() override;
    QualType DeclType;
  
  protected:
    ValueDecl(Kind DK, DeclContext *DC, SourceLocation L,
              DeclarationName N, QualType T)
      : NamedDecl(DK, DC, L, N), DeclType(T) {}
  public:
    QualType getType() const { return DeclType; }
    void setType(QualType newType) { DeclType = newType; }
  
    /// \brief Determine whether this symbol is weakly-imported,
    ///        or declared with the weak or weak-ref attr.
    bool isWeak() const;
  
    // Implement isa/cast/dyncast/etc.
    static bool classof(const Decl *D) { return classofKind(D->getKind()); }
    static bool classofKind(Kind K) { return K >= firstValue && K <= lastValue; }
  };
  
  /// QualifierInfo - A struct with extended info about a syntactic
  /// name qualifier, to be used for the case of out-of-line declarations.
  struct QualifierInfo {
    NestedNameSpecifierLoc QualifierLoc;
  
    /// NumTemplParamLists - The number of "outer" template parameter lists.
    /// The count includes all of the template parameter lists that were matched
    /// against the template-ids occurring into the NNS and possibly (in the
    /// case of an explicit specialization) a final "template <>".
    unsigned NumTemplParamLists;
  
    /// TemplParamLists - A new-allocated array of size NumTemplParamLists,
    /// containing pointers to the "outer" template parameter lists.
    /// It includes all of the template parameter lists that were matched
    /// against the template-ids occurring into the NNS and possibly (in the
    /// case of an explicit specialization) a final "template <>".
    TemplateParameterList** TemplParamLists;
  
    /// Default constructor.
    QualifierInfo()
      : QualifierLoc(), NumTemplParamLists(0), TemplParamLists(nullptr) {}
  
    /// setTemplateParameterListsInfo - Sets info about "outer" template
    /// parameter lists.
    void setTemplateParameterListsInfo(ASTContext &Context,
                                       unsigned NumTPLists,
                                       TemplateParameterList **TPLists);
  
  private:
    // Copy constructor and copy assignment are disabled.
    QualifierInfo(const QualifierInfo&) LLVM_DELETED_FUNCTION;
    QualifierInfo& operator=(const QualifierInfo&) LLVM_DELETED_FUNCTION;
  };
  
  /// \brief Represents a ValueDecl that came out of a declarator.
  /// Contains type source information through TypeSourceInfo.
  class DeclaratorDecl : public ValueDecl {
    // A struct representing both a TInfo and a syntactic qualifier,
    // to be used for the (uncommon) case of out-of-line declarations.
    struct ExtInfo : public QualifierInfo {
      TypeSourceInfo *TInfo;
    };
  
    llvm::PointerUnion<TypeSourceInfo*, ExtInfo*> DeclInfo;
  
    /// InnerLocStart - The start of the source range for this declaration,
    /// ignoring outer template declarations.
    SourceLocation InnerLocStart;
  
    bool hasExtInfo() const { return DeclInfo.is<ExtInfo*>(); }
    ExtInfo *getExtInfo() { return DeclInfo.get<ExtInfo*>(); }
    const ExtInfo *getExtInfo() const { return DeclInfo.get<ExtInfo*>(); }
  
  protected:
    DeclaratorDecl(Kind DK, DeclContext *DC, SourceLocation L,
                   DeclarationName N, QualType T, TypeSourceInfo *TInfo,
                   SourceLocation StartL)
      : ValueDecl(DK, DC, L, N, T), DeclInfo(TInfo), InnerLocStart(StartL) {
    }
  
  public:
    TypeSourceInfo *getTypeSourceInfo() const {
      return hasExtInfo()
        ? getExtInfo()->TInfo
        : DeclInfo.get<TypeSourceInfo*>();
    }
    void setTypeSourceInfo(TypeSourceInfo *TI) {
      if (hasExtInfo())
        getExtInfo()->TInfo = TI;
      else
        DeclInfo = TI;
    }
  
    /// getInnerLocStart - Return SourceLocation representing start of source
    /// range ignoring outer template declarations.
    SourceLocation getInnerLocStart() const { return InnerLocStart; }
    void setInnerLocStart(SourceLocation L) { InnerLocStart = L; }
  
    /// getOuterLocStart - Return SourceLocation representing start of source
    /// range taking into account any outer template declarations.
    SourceLocation getOuterLocStart() const;
  
    SourceRange getSourceRange() const override LLVM_READONLY;
    SourceLocation getLocStart() const LLVM_READONLY {
      return getOuterLocStart();
    }
  
    /// \brief Retrieve the nested-name-specifier that qualifies the name of this
    /// declaration, if it was present in the source.
    NestedNameSpecifier *getQualifier() const {
      return hasExtInfo() ? getExtInfo()->QualifierLoc.getNestedNameSpecifier()
                          : nullptr;
    }
  
    /// \brief Retrieve the nested-name-specifier (with source-location
    /// information) that qualifies the name of this declaration, if it was
    /// present in the source.
    NestedNameSpecifierLoc getQualifierLoc() const {
      return hasExtInfo() ? getExtInfo()->QualifierLoc
                          : NestedNameSpecifierLoc();
    }
  
    void setQualifierInfo(NestedNameSpecifierLoc QualifierLoc);
  
    unsigned getNumTemplateParameterLists() const {
      return hasExtInfo() ? getExtInfo()->NumTemplParamLists : 0;
    }
    TemplateParameterList *getTemplateParameterList(unsigned index) const {
      assert(index < getNumTemplateParameterLists());
      return getExtInfo()->TemplParamLists[index];
    }
    void setTemplateParameterListsInfo(ASTContext &Context, unsigned NumTPLists,
                                       TemplateParameterList **TPLists);
  
    SourceLocation getTypeSpecStartLoc() const;
  
    // Implement isa/cast/dyncast/etc.
    static bool classof(const Decl *D) { return classofKind(D->getKind()); }
    static bool classofKind(Kind K) {
      return K >= firstDeclarator && K <= lastDeclarator;
    }
  
    friend class ASTDeclReader;
    friend class ASTDeclWriter;
  };
  
  /// \brief Structure used to store a statement, the constant value to
  /// which it was evaluated (if any), and whether or not the statement
  /// is an integral constant expression (if known).
  struct EvaluatedStmt {
    EvaluatedStmt() : WasEvaluated(false), IsEvaluating(false), CheckedICE(false),
                      CheckingICE(false), IsICE(false) { }
  
    /// \brief Whether this statement was already evaluated.
    bool WasEvaluated : 1;
  
    /// \brief Whether this statement is being evaluated.
    bool IsEvaluating : 1;
  
    /// \brief Whether we already checked whether this statement was an
    /// integral constant expression.
    bool CheckedICE : 1;
  
    /// \brief Whether we are checking whether this statement is an
    /// integral constant expression.
    bool CheckingICE : 1;
  
    /// \brief Whether this statement is an integral constant expression,
    /// or in C++11, whether the statement is a constant expression. Only
    /// valid if CheckedICE is true.
    bool IsICE : 1;
  
    Stmt *Value;
    APValue Evaluated;
  };
  
  /// VarDecl - An instance of this class is created to represent a variable
  /// declaration or definition.
  class VarDecl : public DeclaratorDecl, public Redeclarable<VarDecl> {
  public:
    /// getStorageClassSpecifierString - Return the string used to
    /// specify the storage class \p SC.
    ///
    /// It is illegal to call this function with SC == None.
    static const char *getStorageClassSpecifierString(StorageClass SC);
  
    /// \brief Initialization styles.
    enum InitializationStyle {
      CInit,    ///< C-style initialization with assignment
      CallInit, ///< Call-style initialization (C++98)
      ListInit  ///< Direct list-initialization (C++11)
    };
  
    /// \brief Kinds of thread-local storage.
    enum TLSKind {
      TLS_None,   ///< Not a TLS variable.
      TLS_Static, ///< TLS with a known-constant initializer.
      TLS_Dynamic ///< TLS with a dynamic initializer.
    };
  
  protected:
    /// \brief Placeholder type used in Init to denote an unparsed C++ default
    /// argument.
    struct UnparsedDefaultArgument;
  
    /// \brief Placeholder type used in Init to denote an uninstantiated C++
    /// default argument.
    struct UninstantiatedDefaultArgument;
  
    typedef llvm::PointerUnion4<Stmt *, EvaluatedStmt *,
                                UnparsedDefaultArgument *,
                                UninstantiatedDefaultArgument *> InitType;
  
    /// \brief The initializer for this variable or, for a ParmVarDecl, the
    /// C++ default argument.
    mutable InitType Init;
  
  private:
    class VarDeclBitfields {
      friend class VarDecl;
      friend class ASTDeclReader;
  
      unsigned SClass : 3;
      unsigned TSCSpec : 2;
      unsigned InitStyle : 2;
  
      /// \brief Whether this variable is the exception variable in a C++ catch
      /// or an Objective-C @catch statement.
      unsigned ExceptionVar : 1;
  
      /// \brief Whether this local variable could be allocated in the return
      /// slot of its function, enabling the named return value optimization
      /// (NRVO).
      unsigned NRVOVariable : 1;
  
      /// \brief Whether this variable is the for-range-declaration in a C++0x
      /// for-range statement.
      unsigned CXXForRangeDecl : 1;
  
      /// \brief Whether this variable is an ARC pseudo-__strong
      /// variable;  see isARCPseudoStrong() for details.
      unsigned ARCPseudoStrong : 1;
  
      /// \brief Whether this variable is (C++0x) constexpr.
      unsigned IsConstexpr : 1;
  
      /// \brief Whether this variable is the implicit variable for a lambda
      /// init-capture.
      unsigned IsInitCapture : 1;
  
      /// \brief Whether this local extern variable's previous declaration was
      /// declared in the same block scope. This controls whether we should merge
      /// the type of this declaration with its previous declaration.
      unsigned PreviousDeclInSameBlockScope : 1;
    };
    enum { NumVarDeclBits = 14 };
  
    friend class ASTDeclReader;
    friend class StmtIteratorBase;
    friend class ASTNodeImporter;
  
  protected:
    enum { NumParameterIndexBits = 8 };
  
    class ParmVarDeclBitfields {
      friend class ParmVarDecl;
      friend class ASTDeclReader;
  
      unsigned : NumVarDeclBits;
  
      /// Whether this parameter inherits a default argument from a
      /// prior declaration.
      unsigned HasInheritedDefaultArg : 1;
  
      /// Whether this parameter undergoes K&R argument promotion.
      unsigned IsKNRPromoted : 1;
  
      /// Whether this parameter is an ObjC method parameter or not.
      unsigned IsObjCMethodParam : 1;
  
      /// If IsObjCMethodParam, a Decl::ObjCDeclQualifier.
      /// Otherwise, the number of function parameter scopes enclosing
      /// the function parameter scope in which this parameter was
      /// declared.
      unsigned ScopeDepthOrObjCQuals : 7;
  
      /// The number of parameters preceding this parameter in the
      /// function parameter scope in which it was declared.
      unsigned ParameterIndex : NumParameterIndexBits;
    };
  
    union {
      unsigned AllBits;
      VarDeclBitfields VarDeclBits;
      ParmVarDeclBitfields ParmVarDeclBits;
    };
  
    VarDecl(Kind DK, ASTContext &C, DeclContext *DC, SourceLocation StartLoc,
            SourceLocation IdLoc, IdentifierInfo *Id, QualType T,
            TypeSourceInfo *TInfo, StorageClass SC);
  
    typedef Redeclarable<VarDecl> redeclarable_base;
    VarDecl *getNextRedeclarationImpl() override {
      return getNextRedeclaration();
    }
    VarDecl *getPreviousDeclImpl() override {
      return getPreviousDecl();
    }
    VarDecl *getMostRecentDeclImpl() override {
      return getMostRecentDecl();
    }
  
  public:
    typedef redeclarable_base::redecl_range redecl_range;
    typedef redeclarable_base::redecl_iterator redecl_iterator;
    using redeclarable_base::redecls_begin;
    using redeclarable_base::redecls_end;
    using redeclarable_base::redecls;
    using redeclarable_base::getPreviousDecl;
    using redeclarable_base::getMostRecentDecl;
    using redeclarable_base::isFirstDecl;
  
    static VarDecl *Create(ASTContext &C, DeclContext *DC,
                           SourceLocation StartLoc, SourceLocation IdLoc,
                           IdentifierInfo *Id, QualType T, TypeSourceInfo *TInfo,
                           StorageClass S);
  
    static VarDecl *CreateDeserialized(ASTContext &C, unsigned ID);
  
    SourceRange getSourceRange() const override LLVM_READONLY;
  
    /// \brief Returns the storage class as written in the source. For the
    /// computed linkage of symbol, see getLinkage.
    StorageClass getStorageClass() const {
      return (StorageClass) VarDeclBits.SClass;
    }
    void setStorageClass(StorageClass SC);
  
    void setTSCSpec(ThreadStorageClassSpecifier TSC) {
      VarDeclBits.TSCSpec = TSC;
      assert(VarDeclBits.TSCSpec == TSC && "truncation");
    }
    ThreadStorageClassSpecifier getTSCSpec() const {
      return static_cast<ThreadStorageClassSpecifier>(VarDeclBits.TSCSpec);
    }
    TLSKind getTLSKind() const;
  
    /// hasLocalStorage - Returns true if a variable with function scope
    ///  is a non-static local variable.
    bool hasLocalStorage() const {
      if (getStorageClass() == SC_None)
        // Second check is for C++11 [dcl.stc]p4.
        return !isFileVarDecl() && getTSCSpec() == TSCS_unspecified;
  
      // Global Named Register (GNU extension)
      if (getStorageClass() == SC_Register && !isLocalVarDecl())
        return false;
  
      // Return true for:  Auto, Register.
      // Return false for: Extern, Static, PrivateExtern, OpenCLWorkGroupLocal.
  
      return getStorageClass() >= SC_Auto;
    }
  
    /// isStaticLocal - Returns true if a variable with function scope is a
    /// static local variable.
    bool isStaticLocal() const {
      return (getStorageClass() == SC_Static ||
              // C++11 [dcl.stc]p4
              (getStorageClass() == SC_None && getTSCSpec() == TSCS_thread_local))
        && !isFileVarDecl();
    }
  
    /// \brief Returns true if a variable has extern or __private_extern__
    /// storage.
    bool hasExternalStorage() const {
      return getStorageClass() == SC_Extern ||
             getStorageClass() == SC_PrivateExtern;
    }
  
    /// \brief Returns true for all variables that do not have local storage.
    ///
    /// This includes all global variables as well as static variables declared
    /// within a function.
    bool hasGlobalStorage() const { return !hasLocalStorage(); }
  
    /// \brief Get the storage duration of this variable, per C++ [basic.stc].
    StorageDuration getStorageDuration() const {
      return hasLocalStorage() ? SD_Automatic :
             getTSCSpec() ? SD_Thread : SD_Static;
    }
  
    /// \brief Compute the language linkage.
    LanguageLinkage getLanguageLinkage() const;
  
    /// \brief Determines whether this variable is a variable with
    /// external, C linkage.
    bool isExternC() const;
  
    /// \brief Determines whether this variable's context is, or is nested within,
    /// a C++ extern "C" linkage spec.
    bool isInExternCContext() const;
  
    /// \brief Determines whether this variable's context is, or is nested within,
    /// a C++ extern "C++" linkage spec.
    bool isInExternCXXContext() const;
  
    /// isLocalVarDecl - Returns true for local variable declarations
    /// other than parameters.  Note that this includes static variables
    /// inside of functions. It also includes variables inside blocks.
    ///
    ///   void foo() { int x; static int y; extern int z; }
    ///
    bool isLocalVarDecl() const {
      if (getKind() != Decl::Var)
        return false;
      if (const DeclContext *DC = getLexicalDeclContext())
        return DC->getRedeclContext()->isFunctionOrMethod();
      return false;
    }
  
    /// isFunctionOrMethodVarDecl - Similar to isLocalVarDecl, but
    /// excludes variables declared in blocks.
    bool isFunctionOrMethodVarDecl() const {
      if (getKind() != Decl::Var)
        return false;
      const DeclContext *DC = getLexicalDeclContext()->getRedeclContext();
      return DC->isFunctionOrMethod() && DC->getDeclKind() != Decl::Block;
    }
  
    /// \brief Determines whether this is a static data member.
    ///
    /// This will only be true in C++, and applies to, e.g., the
    /// variable 'x' in:
    /// \code
    /// struct S {
    ///   static int x;
    /// };
    /// \endcode
    bool isStaticDataMember() const {
      // If it wasn't static, it would be a FieldDecl.
      return getKind() != Decl::ParmVar && getDeclContext()->isRecord();
    }
  
    VarDecl *getCanonicalDecl() override;
    const VarDecl *getCanonicalDecl() const {
      return const_cast<VarDecl*>(this)->getCanonicalDecl();
    }
  
    enum DefinitionKind {
      DeclarationOnly,      ///< This declaration is only a declaration.
      TentativeDefinition,  ///< This declaration is a tentative definition.
      Definition            ///< This declaration is definitely a definition.
    };
  
    /// \brief Check whether this declaration is a definition. If this could be
    /// a tentative definition (in C), don't check whether there's an overriding
    /// definition.
    DefinitionKind isThisDeclarationADefinition(ASTContext &) const;
    DefinitionKind isThisDeclarationADefinition() const {
      return isThisDeclarationADefinition(getASTContext());
    }
  
    /// \brief Check whether this variable is defined in this
    /// translation unit.
    DefinitionKind hasDefinition(ASTContext &) const;
    DefinitionKind hasDefinition() const {
      return hasDefinition(getASTContext());
    }
  
    /// \brief Get the tentative definition that acts as the real definition in
    /// a TU. Returns null if there is a proper definition available.
    VarDecl *getActingDefinition();
    const VarDecl *getActingDefinition() const {
      return const_cast<VarDecl*>(this)->getActingDefinition();
    }
  
    /// \brief Get the real (not just tentative) definition for this declaration.
    VarDecl *getDefinition(ASTContext &);
    const VarDecl *getDefinition(ASTContext &C) const {
      return const_cast<VarDecl*>(this)->getDefinition(C);
    }
    VarDecl *getDefinition() {
      return getDefinition(getASTContext());
    }
    const VarDecl *getDefinition() const {
      return const_cast<VarDecl*>(this)->getDefinition();
    }
  
    /// \brief Determine whether this is or was instantiated from an out-of-line
    /// definition of a static data member.
    bool isOutOfLine() const override;
  
    /// \brief If this is a static data member, find its out-of-line definition.
    VarDecl *getOutOfLineDefinition();
  
    /// isFileVarDecl - Returns true for file scoped variable declaration.
    bool isFileVarDecl() const {
      Kind K = getKind();
      if (K == ParmVar || K == ImplicitParam)
        return false;
  
      if (getLexicalDeclContext()->getRedeclContext()->isFileContext())
        return true;
  
      if (isStaticDataMember())
        return true;
  
      return false;
    }
  
    /// getAnyInitializer - Get the initializer for this variable, no matter which
    /// declaration it is attached to.
    const Expr *getAnyInitializer() const {
      const VarDecl *D;
      return getAnyInitializer(D);
    }
  
    /// getAnyInitializer - Get the initializer for this variable, no matter which
    /// declaration it is attached to. Also get that declaration.
    const Expr *getAnyInitializer(const VarDecl *&D) const;
  
    bool hasInit() const {
      return !Init.isNull() && (Init.is<Stmt *>() || Init.is<EvaluatedStmt *>());
    }
    const Expr *getInit() const {
      if (Init.isNull())
        return nullptr;
  
      const Stmt *S = Init.dyn_cast<Stmt *>();
      if (!S) {
        if (EvaluatedStmt *ES = Init.dyn_cast<EvaluatedStmt*>())
          S = ES->Value;
      }
      return (const Expr*) S;
    }
    Expr *getInit() {
      if (Init.isNull())
        return nullptr;
  
      Stmt *S = Init.dyn_cast<Stmt *>();
      if (!S) {
        if (EvaluatedStmt *ES = Init.dyn_cast<EvaluatedStmt*>())
          S = ES->Value;
      }
  
      return (Expr*) S;
    }
  
    /// \brief Retrieve the address of the initializer expression.
    Stmt **getInitAddress() {
      if (EvaluatedStmt *ES = Init.dyn_cast<EvaluatedStmt*>())
        return &ES->Value;
  
      // This union hack tip-toes around strict-aliasing rules.
      union {
        InitType *InitPtr;
        Stmt **StmtPtr;
      };
  
      InitPtr = &Init;
      return StmtPtr;
    }
  
    void setInit(Expr *I);
  
    /// \brief Determine whether this variable's value can be used in a
    /// constant expression, according to the relevant language standard.
    /// This only checks properties of the declaration, and does not check
    /// whether the initializer is in fact a constant expression.
    bool isUsableInConstantExpressions(ASTContext &C) const;
  
    EvaluatedStmt *ensureEvaluatedStmt() const;
  
    /// \brief Attempt to evaluate the value of the initializer attached to this
    /// declaration, and produce notes explaining why it cannot be evaluated or is
    /// not a constant expression. Returns a pointer to the value if evaluation
    /// succeeded, 0 otherwise.
    APValue *evaluateValue() const;
    APValue *evaluateValue(SmallVectorImpl<PartialDiagnosticAt> &Notes) const;
  
    /// \brief Return the already-evaluated value of this variable's
    /// initializer, or NULL if the value is not yet known. Returns pointer
    /// to untyped APValue if the value could not be evaluated.
    APValue *getEvaluatedValue() const {
      if (EvaluatedStmt *Eval = Init.dyn_cast<EvaluatedStmt *>())
        if (Eval->WasEvaluated)
          return &Eval->Evaluated;
  
      return nullptr;
    }
  
    /// \brief Determines whether it is already known whether the
    /// initializer is an integral constant expression or not.
    bool isInitKnownICE() const {
      if (EvaluatedStmt *Eval = Init.dyn_cast<EvaluatedStmt *>())
        return Eval->CheckedICE;
  
      return false;
    }
  
    /// \brief Determines whether the initializer is an integral constant
    /// expression, or in C++11, whether the initializer is a constant
    /// expression.
    ///
    /// \pre isInitKnownICE()
    bool isInitICE() const {
      assert(isInitKnownICE() &&
             "Check whether we already know that the initializer is an ICE");
      return Init.get<EvaluatedStmt *>()->IsICE;
    }
  
    /// \brief Determine whether the value of the initializer attached to this
    /// declaration is an integral constant expression.
    bool checkInitIsICE() const;
  
    void setInitStyle(InitializationStyle Style) {
      VarDeclBits.InitStyle = Style;
    }
  
    /// \brief The style of initialization for this declaration.
    ///
    /// C-style initialization is "int x = 1;". Call-style initialization is
    /// a C++98 direct-initializer, e.g. "int x(1);". The Init expression will be
    /// the expression inside the parens or a "ClassType(a,b,c)" class constructor
    /// expression for class types. List-style initialization is C++11 syntax,
    /// e.g. "int x{1};". Clients can distinguish between different forms of
    /// initialization by checking this value. In particular, "int x = {1};" is
    /// C-style, "int x({1})" is call-style, and "int x{1};" is list-style; the
    /// Init expression in all three cases is an InitListExpr.
    InitializationStyle getInitStyle() const {
      return static_cast<InitializationStyle>(VarDeclBits.InitStyle);
    }
  
    /// \brief Whether the initializer is a direct-initializer (list or call).
    bool isDirectInit() const {
      return getInitStyle() != CInit;
    }
  
    /// \brief Determine whether this variable is the exception variable in a
    /// C++ catch statememt or an Objective-C \@catch statement.
    bool isExceptionVariable() const {
      return VarDeclBits.ExceptionVar;
    }
    void setExceptionVariable(bool EV) { VarDeclBits.ExceptionVar = EV; }
  
    /// \brief Determine whether this local variable can be used with the named
    /// return value optimization (NRVO).
    ///
    /// The named return value optimization (NRVO) works by marking certain
    /// non-volatile local variables of class type as NRVO objects. These
    /// locals can be allocated within the return slot of their containing
    /// function, in which case there is no need to copy the object to the
    /// return slot when returning from the function. Within the function body,
    /// each return that returns the NRVO object will have this variable as its
    /// NRVO candidate.
    bool isNRVOVariable() const { return VarDeclBits.NRVOVariable; }
    void setNRVOVariable(bool NRVO) { VarDeclBits.NRVOVariable = NRVO; }
  
    /// \brief Determine whether this variable is the for-range-declaration in
    /// a C++0x for-range statement.
    bool isCXXForRangeDecl() const { return VarDeclBits.CXXForRangeDecl; }
    void setCXXForRangeDecl(bool FRD) { VarDeclBits.CXXForRangeDecl = FRD; }
  
    /// \brief Determine whether this variable is an ARC pseudo-__strong
    /// variable.  A pseudo-__strong variable has a __strong-qualified
    /// type but does not actually retain the object written into it.
    /// Generally such variables are also 'const' for safety.
    bool isARCPseudoStrong() const { return VarDeclBits.ARCPseudoStrong; }
    void setARCPseudoStrong(bool ps) { VarDeclBits.ARCPseudoStrong = ps; }
  
    /// Whether this variable is (C++11) constexpr.
    bool isConstexpr() const { return VarDeclBits.IsConstexpr; }
    void setConstexpr(bool IC) { VarDeclBits.IsConstexpr = IC; }
  
    /// Whether this variable is the implicit variable for a lambda init-capture.
    bool isInitCapture() const { return VarDeclBits.IsInitCapture; }
    void setInitCapture(bool IC) { VarDeclBits.IsInitCapture = IC; }
  
    /// Whether this local extern variable declaration's previous declaration
    /// was declared in the same block scope. Only correct in C++.
    bool isPreviousDeclInSameBlockScope() const {
      return VarDeclBits.PreviousDeclInSameBlockScope;
    }
    void setPreviousDeclInSameBlockScope(bool Same) {
      VarDeclBits.PreviousDeclInSameBlockScope = Same;
    }
  
    /// \brief If this variable is an instantiated static data member of a
    /// class template specialization, returns the templated static data member
    /// from which it was instantiated.
    VarDecl *getInstantiatedFromStaticDataMember() const;
  
    /// \brief If this variable is an instantiation of a variable template or a
    /// static data member of a class template, determine what kind of
    /// template specialization or instantiation this is.
    TemplateSpecializationKind getTemplateSpecializationKind() const;
  
    /// \brief If this variable is an instantiation of a variable template or a
    /// static data member of a class template, determine its point of
    /// instantiation.
    SourceLocation getPointOfInstantiation() const;
  
    /// \brief If this variable is an instantiation of a static data member of a
    /// class template specialization, retrieves the member specialization
    /// information.
    MemberSpecializationInfo *getMemberSpecializationInfo() const;
  
    /// \brief For a static data member that was instantiated from a static
    /// data member of a class template, set the template specialiation kind.
    void setTemplateSpecializationKind(TemplateSpecializationKind TSK,
                          SourceLocation PointOfInstantiation = SourceLocation());
  
    /// \brief Specify that this variable is an instantiation of the
    /// static data member VD.
    void setInstantiationOfStaticDataMember(VarDecl *VD,
                                            TemplateSpecializationKind TSK);
  
    /// \brief Retrieves the variable template that is described by this
    /// variable declaration.
    ///
    /// Every variable template is represented as a VarTemplateDecl and a
    /// VarDecl. The former contains template properties (such as
    /// the template parameter lists) while the latter contains the
    /// actual description of the template's
    /// contents. VarTemplateDecl::getTemplatedDecl() retrieves the
    /// VarDecl that from a VarTemplateDecl, while
    /// getDescribedVarTemplate() retrieves the VarTemplateDecl from
    /// a VarDecl.
    VarTemplateDecl *getDescribedVarTemplate() const;
  
    void setDescribedVarTemplate(VarTemplateDecl *Template);
  
    // Implement isa/cast/dyncast/etc.
    static bool classof(const Decl *D) { return classofKind(D->getKind()); }
    static bool classofKind(Kind K) { return K >= firstVar && K <= lastVar; }
  };
  
  class ImplicitParamDecl : public VarDecl {
    void anchor() override;
  public:
    static ImplicitParamDecl *Create(ASTContext &C, DeclContext *DC,
                                     SourceLocation IdLoc, IdentifierInfo *Id,
                                     QualType T);
  
    static ImplicitParamDecl *CreateDeserialized(ASTContext &C, unsigned ID);
  
    ImplicitParamDecl(ASTContext &C, DeclContext *DC, SourceLocation IdLoc,
                      IdentifierInfo *Id, QualType Type)
      : VarDecl(ImplicitParam, C, DC, IdLoc, IdLoc, Id, Type,
                /*tinfo*/ nullptr, SC_None) {
      setImplicit();
    }
  
    // Implement isa/cast/dyncast/etc.
    static bool classof(const Decl *D) { return classofKind(D->getKind()); }
    static bool classofKind(Kind K) { return K == ImplicitParam; }
  };
  
  /// ParmVarDecl - Represents a parameter to a function.
  class ParmVarDecl : public VarDecl {
  public:
    enum { MaxFunctionScopeDepth = 255 };
    enum { MaxFunctionScopeIndex = 255 };
  
  protected:
    ParmVarDecl(Kind DK, ASTContext &C, DeclContext *DC, SourceLocation StartLoc,
                SourceLocation IdLoc, IdentifierInfo *Id, QualType T,
                TypeSourceInfo *TInfo, StorageClass S, Expr *DefArg)
        : VarDecl(DK, C, DC, StartLoc, IdLoc, Id, T, TInfo, S) {
      assert(ParmVarDeclBits.HasInheritedDefaultArg == false);
      assert(ParmVarDeclBits.IsKNRPromoted == false);
      assert(ParmVarDeclBits.IsObjCMethodParam == false);
      setDefaultArg(DefArg);
    }
  
  public:
    static ParmVarDecl *Create(ASTContext &C, DeclContext *DC,
                               SourceLocation StartLoc,
                               SourceLocation IdLoc, IdentifierInfo *Id,
                               QualType T, TypeSourceInfo *TInfo,
                               StorageClass S, Expr *DefArg);
  
    static ParmVarDecl *CreateDeserialized(ASTContext &C, unsigned ID);
  
    SourceRange getSourceRange() const override LLVM_READONLY;
  
    void setObjCMethodScopeInfo(unsigned parameterIndex) {
      ParmVarDeclBits.IsObjCMethodParam = true;
      setParameterIndex(parameterIndex);
    }
  
    void setScopeInfo(unsigned scopeDepth, unsigned parameterIndex) {
      assert(!ParmVarDeclBits.IsObjCMethodParam);
  
      ParmVarDeclBits.ScopeDepthOrObjCQuals = scopeDepth;
      assert(ParmVarDeclBits.ScopeDepthOrObjCQuals == scopeDepth
             && "truncation!");
  
      setParameterIndex(parameterIndex);
    }
  
    bool isObjCMethodParameter() const {
      return ParmVarDeclBits.IsObjCMethodParam;
    }
  
    unsigned getFunctionScopeDepth() const {
      if (ParmVarDeclBits.IsObjCMethodParam) return 0;
      return ParmVarDeclBits.ScopeDepthOrObjCQuals;
    }
  
    /// Returns the index of this parameter in its prototype or method scope.
    unsigned getFunctionScopeIndex() const {
      return getParameterIndex();
    }
  
    ObjCDeclQualifier getObjCDeclQualifier() const {
      if (!ParmVarDeclBits.IsObjCMethodParam) return OBJC_TQ_None;
      return ObjCDeclQualifier(ParmVarDeclBits.ScopeDepthOrObjCQuals);
    }
    void setObjCDeclQualifier(ObjCDeclQualifier QTVal) {
      assert(ParmVarDeclBits.IsObjCMethodParam);
      ParmVarDeclBits.ScopeDepthOrObjCQuals = QTVal;
    }
  
    /// True if the value passed to this parameter must undergo
    /// K&R-style default argument promotion:
    ///
    /// C99 6.5.2.2.
    ///   If the expression that denotes the called function has a type
    ///   that does not include a prototype, the integer promotions are
    ///   performed on each argument, and arguments that have type float
    ///   are promoted to double.
    bool isKNRPromoted() const {
      return ParmVarDeclBits.IsKNRPromoted;
    }
    void setKNRPromoted(bool promoted) {
      ParmVarDeclBits.IsKNRPromoted = promoted;
    }
  
    Expr *getDefaultArg();
    const Expr *getDefaultArg() const {
      return const_cast<ParmVarDecl *>(this)->getDefaultArg();
    }
  
    void setDefaultArg(Expr *defarg) {
      Init = reinterpret_cast<Stmt *>(defarg);
    }
  
    /// \brief Retrieve the source range that covers the entire default
    /// argument.
    SourceRange getDefaultArgRange() const;
    void setUninstantiatedDefaultArg(Expr *arg) {
      Init = reinterpret_cast<UninstantiatedDefaultArgument *>(arg);
    }
    Expr *getUninstantiatedDefaultArg() {
      return (Expr *)Init.get<UninstantiatedDefaultArgument *>();
    }
    const Expr *getUninstantiatedDefaultArg() const {
      return (const Expr *)Init.get<UninstantiatedDefaultArgument *>();
    }
  
    /// hasDefaultArg - Determines whether this parameter has a default argument,
    /// either parsed or not.
    bool hasDefaultArg() const {
      return getInit() || hasUnparsedDefaultArg() ||
        hasUninstantiatedDefaultArg();
    }
  
    /// hasUnparsedDefaultArg - Determines whether this parameter has a
    /// default argument that has not yet been parsed. This will occur
    /// during the processing of a C++ class whose member functions have
    /// default arguments, e.g.,
    /// @code
    ///   class X {
    ///   public:
    ///     void f(int x = 17); // x has an unparsed default argument now
    ///   }; // x has a regular default argument now
    /// @endcode
    bool hasUnparsedDefaultArg() const {
      return Init.is<UnparsedDefaultArgument*>();
    }
  
    bool hasUninstantiatedDefaultArg() const {
      return Init.is<UninstantiatedDefaultArgument*>();
    }
  
    /// setUnparsedDefaultArg - Specify that this parameter has an
    /// unparsed default argument. The argument will be replaced with a
    /// real default argument via setDefaultArg when the class
    /// definition enclosing the function declaration that owns this
    /// default argument is completed.
    void setUnparsedDefaultArg() { Init = (UnparsedDefaultArgument *)nullptr; }
  
    bool hasInheritedDefaultArg() const {
      return ParmVarDeclBits.HasInheritedDefaultArg;
    }
  
    void setHasInheritedDefaultArg(bool I = true) {
      ParmVarDeclBits.HasInheritedDefaultArg = I;
    }
  
    QualType getOriginalType() const;
  
    /// \brief Determine whether this parameter is actually a function
    /// parameter pack.
    bool isParameterPack() const;
  
    /// setOwningFunction - Sets the function declaration that owns this
    /// ParmVarDecl. Since ParmVarDecls are often created before the
    /// FunctionDecls that own them, this routine is required to update
    /// the DeclContext appropriately.
    void setOwningFunction(DeclContext *FD) { setDeclContext(FD); }
  
    // Implement isa/cast/dyncast/etc.
    static bool classof(const Decl *D) { return classofKind(D->getKind()); }
    static bool classofKind(Kind K) { return K == ParmVar; }
  
  private:
    enum { ParameterIndexSentinel = (1 << NumParameterIndexBits) - 1 };
  
    void setParameterIndex(unsigned parameterIndex) {
      if (parameterIndex >= ParameterIndexSentinel) {
        setParameterIndexLarge(parameterIndex);
        return;
      }
  
      ParmVarDeclBits.ParameterIndex = parameterIndex;
      assert(ParmVarDeclBits.ParameterIndex == parameterIndex && "truncation!");
    }
    unsigned getParameterIndex() const {
      unsigned d = ParmVarDeclBits.ParameterIndex;
      return d == ParameterIndexSentinel ? getParameterIndexLarge() : d;
    }
  
    void setParameterIndexLarge(unsigned parameterIndex);
    unsigned getParameterIndexLarge() const;
  };
  
  /// FunctionDecl - An instance of this class is created to represent a
  /// function declaration or definition.
  ///
  /// Since a given function can be declared several times in a program,
  /// there may be several FunctionDecls that correspond to that
  /// function. Only one of those FunctionDecls will be found when
  /// traversing the list of declarations in the context of the
  /// FunctionDecl (e.g., the translation unit); this FunctionDecl
  /// contains all of the information known about the function. Other,
  /// previous declarations of the function are available via the
  /// getPreviousDecl() chain.
  class FunctionDecl : public DeclaratorDecl, public DeclContext,
                       public Redeclarable<FunctionDecl> {
  public:
    /// \brief The kind of templated function a FunctionDecl can be.
    enum TemplatedKind {
      TK_NonTemplate,
      TK_FunctionTemplate,
      TK_MemberSpecialization,
      TK_FunctionTemplateSpecialization,
      TK_DependentFunctionTemplateSpecialization
    };
  
  private:
    /// ParamInfo - new[]'d array of pointers to VarDecls for the formal
    /// parameters of this function.  This is null if a prototype or if there are
    /// no formals.
    ParmVarDecl **ParamInfo;
  
    /// DeclsInPrototypeScope - Array of pointers to NamedDecls for
    /// decls defined in the function prototype that are not parameters. E.g.
    /// 'enum Y' in 'void f(enum Y {AA} x) {}'.
    ArrayRef<NamedDecl *> DeclsInPrototypeScope;
  
    LazyDeclStmtPtr Body;
  
    // FIXME: This can be packed into the bitfields in Decl.
    // NOTE: VC++ treats enums as signed, avoid using the StorageClass enum
    unsigned SClass : 2;
    bool IsInline : 1;
    bool IsInlineSpecified : 1;
    bool IsVirtualAsWritten : 1;
    bool IsPure : 1;
    bool HasInheritedPrototype : 1;
    bool HasWrittenPrototype : 1;
    bool IsDeleted : 1;
    bool IsTrivial : 1; // sunk from CXXMethodDecl
    bool IsDefaulted : 1; // sunk from CXXMethoDecl
    bool IsExplicitlyDefaulted : 1; //sunk from CXXMethodDecl
    bool HasImplicitReturnZero : 1;
    bool IsLateTemplateParsed : 1;
    bool IsConstexpr : 1;
  
    /// \brief Indicates if the function was a definition but its body was
    /// skipped.
    unsigned HasSkippedBody : 1;
  
    /// \brief End part of this FunctionDecl's source range.
    ///
    /// We could compute the full range in getSourceRange(). However, when we're
    /// dealing with a function definition deserialized from a PCH/AST file,
    /// we can only compute the full range once the function body has been
    /// de-serialized, so it's far better to have the (sometimes-redundant)
    /// EndRangeLoc.
    SourceLocation EndRangeLoc;
  
    /// \brief The template or declaration that this declaration
    /// describes or was instantiated from, respectively.
    ///
    /// For non-templates, this value will be NULL. For function
    /// declarations that describe a function template, this will be a
    /// pointer to a FunctionTemplateDecl. For member functions
    /// of class template specializations, this will be a MemberSpecializationInfo
    /// pointer containing information about the specialization.
    /// For function template specializations, this will be a
    /// FunctionTemplateSpecializationInfo, which contains information about
    /// the template being specialized and the template arguments involved in
    /// that specialization.
    llvm::PointerUnion4<FunctionTemplateDecl *,
                        MemberSpecializationInfo *,
                        FunctionTemplateSpecializationInfo *,
                        DependentFunctionTemplateSpecializationInfo *>
      TemplateOrSpecialization;
  
    /// DNLoc - Provides source/type location info for the
    /// declaration name embedded in the DeclaratorDecl base class.
    DeclarationNameLoc DNLoc;
  
    /// \brief Specify that this function declaration is actually a function
    /// template specialization.
    ///
    /// \param C the ASTContext.
    ///
    /// \param Template the function template that this function template
    /// specialization specializes.
    ///
    /// \param TemplateArgs the template arguments that produced this
    /// function template specialization from the template.
    ///
    /// \param InsertPos If non-NULL, the position in the function template
    /// specialization set where the function template specialization data will
    /// be inserted.
    ///
    /// \param TSK the kind of template specialization this is.
    ///
    /// \param TemplateArgsAsWritten location info of template arguments.
    ///
    /// \param PointOfInstantiation point at which the function template
    /// specialization was first instantiated.
    void setFunctionTemplateSpecialization(ASTContext &C,
                                           FunctionTemplateDecl *Template,
                                         const TemplateArgumentList *TemplateArgs,
                                           void *InsertPos,
                                           TemplateSpecializationKind TSK,
                            const TemplateArgumentListInfo *TemplateArgsAsWritten,
                                           SourceLocation PointOfInstantiation);
  
    /// \brief Specify that this record is an instantiation of the
    /// member function FD.
    void setInstantiationOfMemberFunction(ASTContext &C, FunctionDecl *FD,
                                          TemplateSpecializationKind TSK);
  
    void setParams(ASTContext &C, ArrayRef<ParmVarDecl *> NewParamInfo);
  
  protected:
    FunctionDecl(Kind DK, ASTContext &C, DeclContext *DC, SourceLocation StartLoc,
                 const DeclarationNameInfo &NameInfo,
                 QualType T, TypeSourceInfo *TInfo,
                 StorageClass S, bool isInlineSpecified,
                 bool isConstexprSpecified)
      : DeclaratorDecl(DK, DC, NameInfo.getLoc(), NameInfo.getName(), T, TInfo,
                       StartLoc),
        DeclContext(DK),
        redeclarable_base(C),
        ParamInfo(nullptr), Body(),
        SClass(S),
        IsInline(isInlineSpecified), IsInlineSpecified(isInlineSpecified),
        IsVirtualAsWritten(false), IsPure(false), HasInheritedPrototype(false),
        HasWrittenPrototype(true), IsDeleted(false), IsTrivial(false),
        IsDefaulted(false), IsExplicitlyDefaulted(false),
        HasImplicitReturnZero(false), IsLateTemplateParsed(false),
        IsConstexpr(isConstexprSpecified), HasSkippedBody(false),
        EndRangeLoc(NameInfo.getEndLoc()),
        TemplateOrSpecialization(),
        DNLoc(NameInfo.getInfo()) {}
  
    typedef Redeclarable<FunctionDecl> redeclarable_base;
    FunctionDecl *getNextRedeclarationImpl() override {
      return getNextRedeclaration();
    }
    FunctionDecl *getPreviousDeclImpl() override {
      return getPreviousDecl();
    }
    FunctionDecl *getMostRecentDeclImpl() override {
      return getMostRecentDecl();
    }
  
  public:
    typedef redeclarable_base::redecl_range redecl_range;
    typedef redeclarable_base::redecl_iterator redecl_iterator;
    using redeclarable_base::redecls_begin;
    using redeclarable_base::redecls_end;
    using redeclarable_base::redecls;
    using redeclarable_base::getPreviousDecl;
    using redeclarable_base::getMostRecentDecl;
    using redeclarable_base::isFirstDecl;
  
    static FunctionDecl *Create(ASTContext &C, DeclContext *DC,
                                SourceLocation StartLoc, SourceLocation NLoc,
                                DeclarationName N, QualType T,
                                TypeSourceInfo *TInfo,
                                StorageClass SC,
                                bool isInlineSpecified = false,
                                bool hasWrittenPrototype = true,
                                bool isConstexprSpecified = false) {
      DeclarationNameInfo NameInfo(N, NLoc);
      return FunctionDecl::Create(C, DC, StartLoc, NameInfo, T, TInfo,
                                  SC,
                                  isInlineSpecified, hasWrittenPrototype,
                                  isConstexprSpecified);
    }
  
    static FunctionDecl *Create(ASTContext &C, DeclContext *DC,
                                SourceLocation StartLoc,
                                const DeclarationNameInfo &NameInfo,
                                QualType T, TypeSourceInfo *TInfo,
                                StorageClass SC,
                                bool isInlineSpecified,
                                bool hasWrittenPrototype,
                                bool isConstexprSpecified = false);
  
    static FunctionDecl *CreateDeserialized(ASTContext &C, unsigned ID);
                         
    DeclarationNameInfo getNameInfo() const {
      return DeclarationNameInfo(getDeclName(), getLocation(), DNLoc);
    }
  
    void getNameForDiagnostic(raw_ostream &OS, const PrintingPolicy &Policy,
                              bool Qualified) const override;
  
    void setRangeEnd(SourceLocation E) { EndRangeLoc = E; }
  
    SourceRange getSourceRange() const override LLVM_READONLY;
  
    /// \brief Returns true if the function has a body (definition). The
    /// function body might be in any of the (re-)declarations of this
    /// function. The variant that accepts a FunctionDecl pointer will
    /// set that function declaration to the actual declaration
    /// containing the body (if there is one).
    bool hasBody(const FunctionDecl *&Definition) const;
  
    bool hasBody() const override {
      const FunctionDecl* Definition;
      return hasBody(Definition);
    }
  
    /// hasTrivialBody - Returns whether the function has a trivial body that does
    /// not require any specific codegen.
    bool hasTrivialBody() const;
  
    /// isDefined - Returns true if the function is defined at all, including
    /// a deleted definition. Except for the behavior when the function is
    /// deleted, behaves like hasBody.
    bool isDefined(const FunctionDecl *&Definition) const;
  
    virtual bool isDefined() const {
      const FunctionDecl* Definition;
      return isDefined(Definition);
    }
  
    /// getBody - Retrieve the body (definition) of the function. The
    /// function body might be in any of the (re-)declarations of this
    /// function. The variant that accepts a FunctionDecl pointer will
    /// set that function declaration to the actual declaration
    /// containing the body (if there is one).
    /// NOTE: For checking if there is a body, use hasBody() instead, to avoid
    /// unnecessary AST de-serialization of the body.
    Stmt *getBody(const FunctionDecl *&Definition) const;
  
    Stmt *getBody() const override {
      const FunctionDecl* Definition;
      return getBody(Definition);
    }
  
    /// isThisDeclarationADefinition - Returns whether this specific
    /// declaration of the function is also a definition. This does not
    /// determine whether the function has been defined (e.g., in a
    /// previous definition); for that information, use isDefined. Note
    /// that this returns false for a defaulted function unless that function
    /// has been implicitly defined (possibly as deleted).
    bool isThisDeclarationADefinition() const {
      return IsDeleted || Body || IsLateTemplateParsed;
    }
  
    /// doesThisDeclarationHaveABody - Returns whether this specific
    /// declaration of the function has a body - that is, if it is a non-
    /// deleted definition.
    bool doesThisDeclarationHaveABody() const {
      return Body || IsLateTemplateParsed;
    }
  
    void setBody(Stmt *B);
    void setLazyBody(uint64_t Offset) { Body = Offset; }
  
    /// Whether this function is variadic.
    bool isVariadic() const;
  
    /// Whether this function is marked as virtual explicitly.
    bool isVirtualAsWritten() const { return IsVirtualAsWritten; }
    void setVirtualAsWritten(bool V) { IsVirtualAsWritten = V; }
  
    /// Whether this virtual function is pure, i.e. makes the containing class
    /// abstract.
    bool isPure() const { return IsPure; }
    void setPure(bool P = true);
  
    /// Whether this templated function will be late parsed.
    bool isLateTemplateParsed() const { return IsLateTemplateParsed; }
    void setLateTemplateParsed(bool ILT = true) { IsLateTemplateParsed = ILT; }
  
    /// Whether this function is "trivial" in some specialized C++ senses.
    /// Can only be true for default constructors, copy constructors,
    /// copy assignment operators, and destructors.  Not meaningful until
    /// the class has been fully built by Sema.
    bool isTrivial() const { return IsTrivial; }
    void setTrivial(bool IT) { IsTrivial = IT; }
  
    /// Whether this function is defaulted per C++0x. Only valid for
    /// special member functions.
    bool isDefaulted() const { return IsDefaulted; }
    void setDefaulted(bool D = true) { IsDefaulted = D; }
  
    /// Whether this function is explicitly defaulted per C++0x. Only valid
    /// for special member functions.
    bool isExplicitlyDefaulted() const { return IsExplicitlyDefaulted; }
    void setExplicitlyDefaulted(bool ED = true) { IsExplicitlyDefaulted = ED; }
  
    /// Whether falling off this function implicitly returns null/zero.
    /// If a more specific implicit return value is required, front-ends
    /// should synthesize the appropriate return statements.
    bool hasImplicitReturnZero() const { return HasImplicitReturnZero; }
    void setHasImplicitReturnZero(bool IRZ) { HasImplicitReturnZero = IRZ; }
  
    /// \brief Whether this function has a prototype, either because one
    /// was explicitly written or because it was "inherited" by merging
    /// a declaration without a prototype with a declaration that has a
    /// prototype.
    bool hasPrototype() const {
      return HasWrittenPrototype || HasInheritedPrototype;
    }
  
    bool hasWrittenPrototype() const { return HasWrittenPrototype; }
  
    /// \brief Whether this function inherited its prototype from a
    /// previous declaration.
    bool hasInheritedPrototype() const { return HasInheritedPrototype; }
    void setHasInheritedPrototype(bool P = true) { HasInheritedPrototype = P; }
  
    /// Whether this is a (C++11) constexpr function or constexpr constructor.
    bool isConstexpr() const { return IsConstexpr; }
    void setConstexpr(bool IC) { IsConstexpr = IC; }
  
    /// \brief Whether this function has been deleted.
    ///
    /// A function that is "deleted" (via the C++0x "= delete" syntax)
    /// acts like a normal function, except that it cannot actually be
    /// called or have its address taken. Deleted functions are
    /// typically used in C++ overload resolution to attract arguments
    /// whose type or lvalue/rvalue-ness would permit the use of a
    /// different overload that would behave incorrectly. For example,
    /// one might use deleted functions to ban implicit conversion from
    /// a floating-point number to an Integer type:
    ///
    /// @code
    /// struct Integer {
    ///   Integer(long); // construct from a long
    ///   Integer(double) = delete; // no construction from float or double
    ///   Integer(long double) = delete; // no construction from long double
    /// };
    /// @endcode
    // If a function is deleted, its first declaration must be.
    bool isDeleted() const { return getCanonicalDecl()->IsDeleted; }
    bool isDeletedAsWritten() const { return IsDeleted && !IsDefaulted; }
    void setDeletedAsWritten(bool D = true) { IsDeleted = D; }
  
    /// \brief Determines whether this function is "main", which is the
    /// entry point into an executable program.
    bool isMain() const;
  
    /// \brief Determines whether this function is a MSVCRT user defined entry
    /// point.
    bool isMSVCRTEntryPoint() const;
  
    /// \brief Determines whether this operator new or delete is one
    /// of the reserved global placement operators:
    ///    void *operator new(size_t, void *);
    ///    void *operator new[](size_t, void *);
    ///    void operator delete(void *, void *);
    ///    void operator delete[](void *, void *);
    /// These functions have special behavior under [new.delete.placement]:
    ///    These functions are reserved, a C++ program may not define
    ///    functions that displace the versions in the Standard C++ library.
    ///    The provisions of [basic.stc.dynamic] do not apply to these
    ///    reserved placement forms of operator new and operator delete.
    ///
    /// This function must be an allocation or deallocation function.
    bool isReservedGlobalPlacementOperator() const;
  
    /// \brief Determines whether this function is one of the replaceable
    /// global allocation functions:
    ///    void *operator new(size_t);
    ///    void *operator new(size_t, const std::nothrow_t &) noexcept;
    ///    void *operator new[](size_t);
    ///    void *operator new[](size_t, const std::nothrow_t &) noexcept;
    ///    void operator delete(void *) noexcept;
    ///    void operator delete(void *, std::size_t) noexcept;      [C++1y]
    ///    void operator delete(void *, const std::nothrow_t &) noexcept;
    ///    void operator delete[](void *) noexcept;
    ///    void operator delete[](void *, std::size_t) noexcept;    [C++1y]
    ///    void operator delete[](void *, const std::nothrow_t &) noexcept;
    /// These functions have special behavior under C++1y [expr.new]:
    ///    An implementation is allowed to omit a call to a replaceable global
    ///    allocation function. [...]
    bool isReplaceableGlobalAllocationFunction() const;
  
    /// \brief Determine whether this function is a sized global deallocation
    /// function in C++1y. If so, find and return the corresponding unsized
    /// deallocation function.
    FunctionDecl *getCorrespondingUnsizedGlobalDeallocationFunction() const;
  
    /// Compute the language linkage.
    LanguageLinkage getLanguageLinkage() const;
  
    /// \brief Determines whether this function is a function with
    /// external, C linkage.
    bool isExternC() const;
  
    /// \brief Determines whether this function's context is, or is nested within,
    /// a C++ extern "C" linkage spec.
    bool isInExternCContext() const;
  
    /// \brief Determines whether this function's context is, or is nested within,
    /// a C++ extern "C++" linkage spec.
    bool isInExternCXXContext() const;
  
    /// \brief Determines whether this is a global function.
    bool isGlobal() const;
  
    /// \brief Determines whether this function is known to be 'noreturn', through
    /// an attribute on its declaration or its type.
    bool isNoReturn() const;
  
    /// \brief True if the function was a definition but its body was skipped.
    bool hasSkippedBody() const { return HasSkippedBody; }
    void setHasSkippedBody(bool Skipped = true) { HasSkippedBody = Skipped; }
  
    void setPreviousDeclaration(FunctionDecl * PrevDecl);
  
    virtual const FunctionDecl *getCanonicalDecl() const;
    FunctionDecl *getCanonicalDecl() override;
  
    unsigned getBuiltinID() const;
  
    // Iterator access to formal parameters.
    unsigned param_size() const { return getNumParams(); }
    typedef ParmVarDecl **param_iterator;
    typedef ParmVarDecl * const *param_const_iterator;
    typedef llvm::iterator_range<param_iterator> param_range;
    typedef llvm::iterator_range<param_const_iterator> param_const_range;
  
    param_iterator param_begin() { return param_iterator(ParamInfo); }
    param_iterator param_end() {
      return param_iterator(ParamInfo + param_size());
    }
    param_range params() { return param_range(param_begin(), param_end()); }
  
    param_const_iterator param_begin() const {
      return param_const_iterator(ParamInfo);
    }
    param_const_iterator param_end() const {
      return param_const_iterator(ParamInfo + param_size());
    }
    param_const_range params() const {
      return param_const_range(param_begin(), param_end());
    }
  
    /// getNumParams - Return the number of parameters this function must have
    /// based on its FunctionType.  This is the length of the ParamInfo array
    /// after it has been created.
    unsigned getNumParams() const;
  
    const ParmVarDecl *getParamDecl(unsigned i) const {
      assert(i < getNumParams() && "Illegal param #");
      return ParamInfo[i];
    }
    ParmVarDecl *getParamDecl(unsigned i) {
      assert(i < getNumParams() && "Illegal param #");
      return ParamInfo[i];
    }
    void setParams(ArrayRef<ParmVarDecl *> NewParamInfo) {
      setParams(getASTContext(), NewParamInfo);
    }
  
    // ArrayRef iterface to parameters.
    // FIXME: Should one day replace iterator interface.
    ArrayRef<ParmVarDecl*> parameters() const {
      return llvm::makeArrayRef(ParamInfo, getNumParams());
    }
  
    ArrayRef<NamedDecl *> getDeclsInPrototypeScope() const {
      return DeclsInPrototypeScope;
    }
    void setDeclsInPrototypeScope(ArrayRef<NamedDecl *> NewDecls);
  
    /// getMinRequiredArguments - Returns the minimum number of arguments
    /// needed to call this function. This may be fewer than the number of
    /// function parameters, if some of the parameters have default
    /// arguments (in C++).
    unsigned getMinRequiredArguments() const;
  
    QualType getReturnType() const {
      return getType()->getAs<FunctionType>()->getReturnType();
    }
  
    /// \brief Attempt to compute an informative source range covering the
    /// function return type. This may omit qualifiers and other information with
    /// limited representation in the AST.
    SourceRange getReturnTypeSourceRange() const;
  
    /// \brief Determine the type of an expression that calls this function.
    QualType getCallResultType() const {
      return getType()->getAs<FunctionType>()->getCallResultType(getASTContext());
    }
  
    /// \brief Returns the storage class as written in the source. For the
    /// computed linkage of symbol, see getLinkage.
    StorageClass getStorageClass() const { return StorageClass(SClass); }
  
    /// \brief Determine whether the "inline" keyword was specified for this
    /// function.
    bool isInlineSpecified() const { return IsInlineSpecified; }
  
    /// Set whether the "inline" keyword was specified for this function.
    void setInlineSpecified(bool I) {
      IsInlineSpecified = I;
      IsInline = I;
    }
  
    /// Flag that this function is implicitly inline.
    void setImplicitlyInline() {
      IsInline = true;
    }
  
    /// \brief Determine whether this function should be inlined, because it is
    /// either marked "inline" or "constexpr" or is a member function of a class
    /// that was defined in the class body.
    bool isInlined() const { return IsInline; }
  
    bool isInlineDefinitionExternallyVisible() const;
  
    bool isMSExternInline() const;
  
    bool doesDeclarationForceExternallyVisibleDefinition() const;
  
    /// isOverloadedOperator - Whether this function declaration
    /// represents an C++ overloaded operator, e.g., "operator+".
    bool isOverloadedOperator() const {
      return getOverloadedOperator() != OO_None;
    }
  
    OverloadedOperatorKind getOverloadedOperator() const;
  
    const IdentifierInfo *getLiteralIdentifier() const;
  
    /// \brief If this function is an instantiation of a member function
    /// of a class template specialization, retrieves the function from
    /// which it was instantiated.
    ///
    /// This routine will return non-NULL for (non-templated) member
    /// functions of class templates and for instantiations of function
    /// templates. For example, given:
    ///
    /// \code
    /// template<typename T>
    /// struct X {
    ///   void f(T);
    /// };
    /// \endcode
    ///
    /// The declaration for X<int>::f is a (non-templated) FunctionDecl
    /// whose parent is the class template specialization X<int>. For
    /// this declaration, getInstantiatedFromFunction() will return
    /// the FunctionDecl X<T>::A. When a complete definition of
    /// X<int>::A is required, it will be instantiated from the
    /// declaration returned by getInstantiatedFromMemberFunction().
    FunctionDecl *getInstantiatedFromMemberFunction() const;
  
    /// \brief What kind of templated function this is.
    TemplatedKind getTemplatedKind() const;
  
    /// \brief If this function is an instantiation of a member function of a
    /// class template specialization, retrieves the member specialization
    /// information.
    MemberSpecializationInfo *getMemberSpecializationInfo() const {
      return TemplateOrSpecialization.dyn_cast<MemberSpecializationInfo*>();
    }
  
    /// \brief Specify that this record is an instantiation of the
    /// member function FD.
    void setInstantiationOfMemberFunction(FunctionDecl *FD,
                                          TemplateSpecializationKind TSK) {
      setInstantiationOfMemberFunction(getASTContext(), FD, TSK);
    }
  
    /// \brief Retrieves the function template that is described by this
    /// function declaration.
    ///
    /// Every function template is represented as a FunctionTemplateDecl
    /// and a FunctionDecl (or something derived from FunctionDecl). The
    /// former contains template properties (such as the template
    /// parameter lists) while the latter contains the actual
    /// description of the template's
    /// contents. FunctionTemplateDecl::getTemplatedDecl() retrieves the
    /// FunctionDecl that describes the function template,
    /// getDescribedFunctionTemplate() retrieves the
    /// FunctionTemplateDecl from a FunctionDecl.
    FunctionTemplateDecl *getDescribedFunctionTemplate() const {
      return TemplateOrSpecialization.dyn_cast<FunctionTemplateDecl*>();
    }
  
    void setDescribedFunctionTemplate(FunctionTemplateDecl *Template) {
      TemplateOrSpecialization = Template;
    }
  
    /// \brief Determine whether this function is a function template
    /// specialization.
    bool isFunctionTemplateSpecialization() const {
      return getPrimaryTemplate() != nullptr;
    }
  
    /// \brief Retrieve the class scope template pattern that this function
    ///  template specialization is instantiated from.
    FunctionDecl *getClassScopeSpecializationPattern() const;
  
    /// \brief If this function is actually a function template specialization,
    /// retrieve information about this function template specialization.
    /// Otherwise, returns NULL.
    FunctionTemplateSpecializationInfo *getTemplateSpecializationInfo() const {
      return TemplateOrSpecialization.
               dyn_cast<FunctionTemplateSpecializationInfo*>();
    }
  
    /// \brief Determines whether this function is a function template
    /// specialization or a member of a class template specialization that can
    /// be implicitly instantiated.
    bool isImplicitlyInstantiable() const;
  
    /// \brief Determines if the given function was instantiated from a
    /// function template.
    bool isTemplateInstantiation() const;
  
    /// \brief Retrieve the function declaration from which this function could
    /// be instantiated, if it is an instantiation (rather than a non-template
    /// or a specialization, for example).
    FunctionDecl *getTemplateInstantiationPattern() const;
  
    /// \brief Retrieve the primary template that this function template
    /// specialization either specializes or was instantiated from.
    ///
    /// If this function declaration is not a function template specialization,
    /// returns NULL.
    FunctionTemplateDecl *getPrimaryTemplate() const;
  
    /// \brief Retrieve the template arguments used to produce this function
    /// template specialization from the primary template.
    ///
    /// If this function declaration is not a function template specialization,
    /// returns NULL.
    const TemplateArgumentList *getTemplateSpecializationArgs() const;
  
    /// \brief Retrieve the template argument list as written in the sources,
    /// if any.
    ///
    /// If this function declaration is not a function template specialization
    /// or if it had no explicit template argument list, returns NULL.
    /// Note that it an explicit template argument list may be written empty,
    /// e.g., template<> void foo<>(char* s);
    const ASTTemplateArgumentListInfo*
    getTemplateSpecializationArgsAsWritten() const;
  
    /// \brief Specify that this function declaration is actually a function
    /// template specialization.
    ///
    /// \param Template the function template that this function template
    /// specialization specializes.
    ///
    /// \param TemplateArgs the template arguments that produced this
    /// function template specialization from the template.
    ///
    /// \param InsertPos If non-NULL, the position in the function template
    /// specialization set where the function template specialization data will
    /// be inserted.
    ///
    /// \param TSK the kind of template specialization this is.
    ///
    /// \param TemplateArgsAsWritten location info of template arguments.
    ///
    /// \param PointOfInstantiation point at which the function template
    /// specialization was first instantiated.
    void setFunctionTemplateSpecialization(FunctionTemplateDecl *Template,
                  const TemplateArgumentList *TemplateArgs,
                  void *InsertPos,
                  TemplateSpecializationKind TSK = TSK_ImplicitInstantiation,
                  const TemplateArgumentListInfo *TemplateArgsAsWritten = nullptr,
                  SourceLocation PointOfInstantiation = SourceLocation()) {
      setFunctionTemplateSpecialization(getASTContext(), Template, TemplateArgs,
                                        InsertPos, TSK, TemplateArgsAsWritten,
                                        PointOfInstantiation);
    }
  
    /// \brief Specifies that this function declaration is actually a
    /// dependent function template specialization.
    void setDependentTemplateSpecialization(ASTContext &Context,
                               const UnresolvedSetImpl &Templates,
                        const TemplateArgumentListInfo &TemplateArgs);
  
    DependentFunctionTemplateSpecializationInfo *
    getDependentSpecializationInfo() const {
      return TemplateOrSpecialization.
               dyn_cast<DependentFunctionTemplateSpecializationInfo*>();
    }
  
    /// \brief Determine what kind of template instantiation this function
    /// represents.
    TemplateSpecializationKind getTemplateSpecializationKind() const;
  
    /// \brief Determine what kind of template instantiation this function
    /// represents.
    void setTemplateSpecializationKind(TemplateSpecializationKind TSK,
                          SourceLocation PointOfInstantiation = SourceLocation());
  
    /// \brief Retrieve the (first) point of instantiation of a function template
    /// specialization or a member of a class template specialization.
    ///
    /// \returns the first point of instantiation, if this function was
    /// instantiated from a template; otherwise, returns an invalid source
    /// location.
    SourceLocation getPointOfInstantiation() const;
  
    /// \brief Determine whether this is or was instantiated from an out-of-line
    /// definition of a member function.
    bool isOutOfLine() const override;
  
    /// \brief Identify a memory copying or setting function.
    /// If the given function is a memory copy or setting function, returns
    /// the corresponding Builtin ID. If the function is not a memory function,
    /// returns 0.
    unsigned getMemoryFunctionKind() const;
  
    // Implement isa/cast/dyncast/etc.
    static bool classof(const Decl *D) { return classofKind(D->getKind()); }
    static bool classofKind(Kind K) {
      return K >= firstFunction && K <= lastFunction;
    }
    static DeclContext *castToDeclContext(const FunctionDecl *D) {
      return static_cast<DeclContext *>(const_cast<FunctionDecl*>(D));
    }
    static FunctionDecl *castFromDeclContext(const DeclContext *DC) {
      return static_cast<FunctionDecl *>(const_cast<DeclContext*>(DC));
    }
  
    friend class ASTDeclReader;
    friend class ASTDeclWriter;
  };
  
  
  /// FieldDecl - An instance of this class is created by Sema::ActOnField to
  /// represent a member of a struct/union/class.
  class FieldDecl : public DeclaratorDecl, public Mergeable<FieldDecl> {
    // FIXME: This can be packed into the bitfields in Decl.
    bool Mutable : 1;
    mutable unsigned CachedFieldIndex : 31;
  
    /// The kinds of value we can store in InitializerOrBitWidth.
    ///
    /// Note that this is compatible with InClassInitStyle except for
    /// ISK_CapturedVLAType.
    enum InitStorageKind {
      /// If the pointer is null, there's nothing special.  Otherwise,
      /// this is a bitfield and the pointer is the Expr* storing the
      /// bit-width.
      ISK_BitWidthOrNothing = (unsigned) ICIS_NoInit,
  
      /// The pointer is an (optional due to delayed parsing) Expr*
      /// holding the copy-initializer.
      ISK_InClassCopyInit = (unsigned) ICIS_CopyInit,
  
      /// The pointer is an (optional due to delayed parsing) Expr*
      /// holding the list-initializer.
      ISK_InClassListInit = (unsigned) ICIS_ListInit,
  
      /// The pointer is a VariableArrayType* that's been captured;
      /// the enclosing context is a lambda or captured statement.
      ISK_CapturedVLAType,
    };
  
    /// \brief Storage for either the bit-width, the in-class
    /// initializer, or the captured variable length array bound.
    ///
    /// We can safely combine these because in-class initializers are
    /// not permitted for bit-fields, and both are exclusive with VLA
    /// captures.
    ///
    /// If the storage kind is ISK_InClassCopyInit or
    /// ISK_InClassListInit, but the initializer is null, then this
    /// field has an in-class initializer which has not yet been parsed
    /// and attached.
    llvm::PointerIntPair<void *, 2, InitStorageKind> InitStorage;
  protected:
    FieldDecl(Kind DK, DeclContext *DC, SourceLocation StartLoc,
              SourceLocation IdLoc, IdentifierInfo *Id,
              QualType T, TypeSourceInfo *TInfo, Expr *BW, bool Mutable,
              InClassInitStyle InitStyle)
      : DeclaratorDecl(DK, DC, IdLoc, Id, T, TInfo, StartLoc),
        Mutable(Mutable), CachedFieldIndex(0),
        InitStorage(BW, (InitStorageKind) InitStyle) {
      assert((!BW || InitStyle == ICIS_NoInit) && "got initializer for bitfield");
    }
  
  public:
    static FieldDecl *Create(const ASTContext &C, DeclContext *DC,
                             SourceLocation StartLoc, SourceLocation IdLoc,
                             IdentifierInfo *Id, QualType T,
                             TypeSourceInfo *TInfo, Expr *BW, bool Mutable,
                             InClassInitStyle InitStyle);
  
    static FieldDecl *CreateDeserialized(ASTContext &C, unsigned ID);
    
    /// getFieldIndex - Returns the index of this field within its record,
    /// as appropriate for passing to ASTRecordLayout::getFieldOffset.
    unsigned getFieldIndex() const;
  
    /// isMutable - Determines whether this field is mutable (C++ only).
    bool isMutable() const { return Mutable; }
  
    /// \brief Determines whether this field is a bitfield.
    bool isBitField() const {
      return InitStorage.getInt() == ISK_BitWidthOrNothing &&
             InitStorage.getPointer() != nullptr;
    }
  
    /// @brief Determines whether this is an unnamed bitfield.
    bool isUnnamedBitfield() const { return isBitField() && !getDeclName(); }
  
    /// isAnonymousStructOrUnion - Determines whether this field is a
    /// representative for an anonymous struct or union. Such fields are
    /// unnamed and are implicitly generated by the implementation to
    /// store the data for the anonymous union or struct.
    bool isAnonymousStructOrUnion() const;
  
    Expr *getBitWidth() const {
      return isBitField()
                 ? static_cast<Expr *>(InitStorage.getPointer())
                 : nullptr;
    }
    unsigned getBitWidthValue(const ASTContext &Ctx) const;
  
    /// setBitWidth - Set the bit-field width for this member.
    // Note: used by some clients (i.e., do not remove it).
    void setBitWidth(Expr *Width) {
      assert(InitStorage.getInt() == ISK_BitWidthOrNothing &&
             InitStorage.getPointer() == nullptr &&
             "bit width, initializer or captured type already set");
      InitStorage.setPointerAndInt(Width, ISK_BitWidthOrNothing);
    }
  
    /// removeBitWidth - Remove the bit-field width from this member.
    // Note: used by some clients (i.e., do not remove it).
    void removeBitWidth() {
      assert(isBitField() && "no bitfield width to remove");
      InitStorage.setPointerAndInt(nullptr, ISK_BitWidthOrNothing);
    }
  
    /// getInClassInitStyle - Get the kind of (C++11) in-class initializer which
    /// this field has.
    InClassInitStyle getInClassInitStyle() const {
      InitStorageKind storageKind = InitStorage.getInt();
      return (storageKind == ISK_CapturedVLAType
                ? ICIS_NoInit : (InClassInitStyle) storageKind);
    }
  
    /// hasInClassInitializer - Determine whether this member has a C++11 in-class
    /// initializer.
    bool hasInClassInitializer() const {
      return getInClassInitStyle() != ICIS_NoInit;
    }
  
    /// getInClassInitializer - Get the C++11 in-class initializer for this
    /// member, or null if one has not been set. If a valid declaration has an
    /// in-class initializer, but this returns null, then we have not parsed and
    /// attached it yet.
    Expr *getInClassInitializer() const {
      return hasInClassInitializer()
                 ? static_cast<Expr *>(InitStorage.getPointer())
                 : nullptr;
    }
  
    /// setInClassInitializer - Set the C++11 in-class initializer for this
    /// member.
    void setInClassInitializer(Expr *Init) {
      assert(hasInClassInitializer() &&
             InitStorage.getPointer() == nullptr &&
             "bit width, initializer or captured type already set");
      InitStorage.setPointer(Init);
    }
  
    /// removeInClassInitializer - Remove the C++11 in-class initializer from this
    /// member.
    void removeInClassInitializer() {
      assert(hasInClassInitializer() && "no initializer to remove");
      InitStorage.setPointerAndInt(nullptr, ISK_BitWidthOrNothing);
    }
  
    /// \brief Determine whether this member captures the variable length array
    /// type.
    bool hasCapturedVLAType() const {
      return InitStorage.getInt() == ISK_CapturedVLAType;
    }
  
    /// \brief Get the captured variable length array type.
    const VariableArrayType *getCapturedVLAType() const {
      return hasCapturedVLAType() ? static_cast<const VariableArrayType *>(
                                        InitStorage.getPointer())
                                  : nullptr;
    }
    /// \brief Set the captured variable length array type for this field.
    void setCapturedVLAType(const VariableArrayType *VLAType);
  
    /// getParent - Returns the parent of this field declaration, which
    /// is the struct in which this method is defined.
    const RecordDecl *getParent() const {
      return cast<RecordDecl>(getDeclContext());
    }
  
    RecordDecl *getParent() {
      return cast<RecordDecl>(getDeclContext());
    }
  
    SourceRange getSourceRange() const override LLVM_READONLY;
  
    /// Retrieves the canonical declaration of this field.
    FieldDecl *getCanonicalDecl() override { return getFirstDecl(); }
    const FieldDecl *getCanonicalDecl() const { return getFirstDecl(); }
  
    // Implement isa/cast/dyncast/etc.
    static bool classof(const Decl *D) { return classofKind(D->getKind()); }
    static bool classofKind(Kind K) { return K >= firstField && K <= lastField; }
  
    friend class ASTDeclReader;
    friend class ASTDeclWriter;
  };
  
  /// EnumConstantDecl - An instance of this object exists for each enum constant
  /// that is defined.  For example, in "enum X {a,b}", each of a/b are
  /// EnumConstantDecl's, X is an instance of EnumDecl, and the type of a/b is a
  /// TagType for the X EnumDecl.
  class EnumConstantDecl : public ValueDecl, public Mergeable<EnumConstantDecl> {
    Stmt *Init; // an integer constant expression
    llvm::APSInt Val; // The value.
  protected:
    EnumConstantDecl(DeclContext *DC, SourceLocation L,
                     IdentifierInfo *Id, QualType T, Expr *E,
                     const llvm::APSInt &V)
      : ValueDecl(EnumConstant, DC, L, Id, T), Init((Stmt*)E), Val(V) {}
  
  public:
  
    static EnumConstantDecl *Create(ASTContext &C, EnumDecl *DC,
                                    SourceLocation L, IdentifierInfo *Id,
                                    QualType T, Expr *E,
                                    const llvm::APSInt &V);
    static EnumConstantDecl *CreateDeserialized(ASTContext &C, unsigned ID);
    
    const Expr *getInitExpr() const { return (const Expr*) Init; }
    Expr *getInitExpr() { return (Expr*) Init; }
    const llvm::APSInt &getInitVal() const { return Val; }
  
    void setInitExpr(Expr *E) { Init = (Stmt*) E; }
    void setInitVal(const llvm::APSInt &V) { Val = V; }
  
    SourceRange getSourceRange() const override LLVM_READONLY;
  
    /// Retrieves the canonical declaration of this enumerator.
    EnumConstantDecl *getCanonicalDecl() override { return getFirstDecl(); }
    const EnumConstantDecl *getCanonicalDecl() const { return getFirstDecl(); }
  
    // Implement isa/cast/dyncast/etc.
    static bool classof(const Decl *D) { return classofKind(D->getKind()); }
    static bool classofKind(Kind K) { return K == EnumConstant; }
  
    friend class StmtIteratorBase;
  };
  
  /// IndirectFieldDecl - An instance of this class is created to represent a
  /// field injected from an anonymous union/struct into the parent scope.
  /// IndirectFieldDecl are always implicit.
  class IndirectFieldDecl : public ValueDecl {
    void anchor() override;
    NamedDecl **Chaining;
    unsigned ChainingSize;
  
    IndirectFieldDecl(DeclContext *DC, SourceLocation L,
                      DeclarationName N, QualType T,
                      NamedDecl **CH, unsigned CHS)
      : ValueDecl(IndirectField, DC, L, N, T), Chaining(CH), ChainingSize(CHS) {}
  
  public:
    static IndirectFieldDecl *Create(ASTContext &C, DeclContext *DC,
                                     SourceLocation L, IdentifierInfo *Id,
                                     QualType T, NamedDecl **CH, unsigned CHS);
  
    static IndirectFieldDecl *CreateDeserialized(ASTContext &C, unsigned ID);
    
    typedef NamedDecl * const *chain_iterator;
    typedef llvm::iterator_range<chain_iterator> chain_range;
  
    chain_range chain() const { return chain_range(chain_begin(), chain_end()); }
    chain_iterator chain_begin() const { return chain_iterator(Chaining); }
    chain_iterator chain_end() const {
      return chain_iterator(Chaining + ChainingSize);
    }
  
    unsigned getChainingSize() const { return ChainingSize; }
  
    FieldDecl *getAnonField() const {
      assert(ChainingSize >= 2);
      return cast<FieldDecl>(Chaining[ChainingSize - 1]);
    }
  
    VarDecl *getVarDecl() const {
      assert(ChainingSize >= 2);
      return dyn_cast<VarDecl>(*chain_begin());
    }
  
    // Implement isa/cast/dyncast/etc.
    static bool classof(const Decl *D) { return classofKind(D->getKind()); }
    static bool classofKind(Kind K) { return K == IndirectField; }
    friend class ASTDeclReader;
  };
  
  /// TypeDecl - Represents a declaration of a type.
  ///
  class TypeDecl : public NamedDecl {
    void anchor() override;
    /// TypeForDecl - This indicates the Type object that represents
    /// this TypeDecl.  It is a cache maintained by
    /// ASTContext::getTypedefType, ASTContext::getTagDeclType, and
    /// ASTContext::getTemplateTypeParmType, and TemplateTypeParmDecl.
    mutable const Type *TypeForDecl;
    /// LocStart - The start of the source range for this declaration.
    SourceLocation LocStart;
    friend class ASTContext;
  
  protected:
    TypeDecl(Kind DK, DeclContext *DC, SourceLocation L, IdentifierInfo *Id,
             SourceLocation StartL = SourceLocation())
      : NamedDecl(DK, DC, L, Id), TypeForDecl(nullptr), LocStart(StartL) {}
  
  public:
    // Low-level accessor. If you just want the type defined by this node,
    // check out ASTContext::getTypeDeclType or one of
    // ASTContext::getTypedefType, ASTContext::getRecordType, etc. if you
    // already know the specific kind of node this is.
    const Type *getTypeForDecl() const { return TypeForDecl; }
    void setTypeForDecl(const Type *TD) { TypeForDecl = TD; }
  
    SourceLocation getLocStart() const LLVM_READONLY { return LocStart; }
    void setLocStart(SourceLocation L) { LocStart = L; }
    SourceRange getSourceRange() const override LLVM_READONLY {
      if (LocStart.isValid())
        return SourceRange(LocStart, getLocation());
      else
        return SourceRange(getLocation());
    }
  
    // Implement isa/cast/dyncast/etc.
    static bool classof(const Decl *D) { return classofKind(D->getKind()); }
    static bool classofKind(Kind K) { return K >= firstType && K <= lastType; }
  };
  
  
  /// Base class for declarations which introduce a typedef-name.
  class TypedefNameDecl : public TypeDecl, public Redeclarable<TypedefNameDecl> {
    void anchor() override;
    typedef std::pair<TypeSourceInfo*, QualType> ModedTInfo;
    llvm::PointerUnion<TypeSourceInfo*, ModedTInfo*> MaybeModedTInfo;
  
  protected:
    TypedefNameDecl(Kind DK, ASTContext &C, DeclContext *DC,
                    SourceLocation StartLoc, SourceLocation IdLoc,
                    IdentifierInfo *Id, TypeSourceInfo *TInfo)
        : TypeDecl(DK, DC, IdLoc, Id, StartLoc), redeclarable_base(C),
          MaybeModedTInfo(TInfo) {}
  
    typedef Redeclarable<TypedefNameDecl> redeclarable_base;
    TypedefNameDecl *getNextRedeclarationImpl() override {
      return getNextRedeclaration();
    }
    TypedefNameDecl *getPreviousDeclImpl() override {
      return getPreviousDecl();
    }
    TypedefNameDecl *getMostRecentDeclImpl() override {
      return getMostRecentDecl();
    }
  
  public:
    typedef redeclarable_base::redecl_range redecl_range;
    typedef redeclarable_base::redecl_iterator redecl_iterator;
    using redeclarable_base::redecls_begin;
    using redeclarable_base::redecls_end;
    using redeclarable_base::redecls;
    using redeclarable_base::getPreviousDecl;
    using redeclarable_base::getMostRecentDecl;
    using redeclarable_base::isFirstDecl;
  
    bool isModed() const { return MaybeModedTInfo.is<ModedTInfo*>(); }
  
    TypeSourceInfo *getTypeSourceInfo() const {
      return isModed()
        ? MaybeModedTInfo.get<ModedTInfo*>()->first
        : MaybeModedTInfo.get<TypeSourceInfo*>();
    }
    QualType getUnderlyingType() const {
      return isModed()
        ? MaybeModedTInfo.get<ModedTInfo*>()->second
        : MaybeModedTInfo.get<TypeSourceInfo*>()->getType();
    }
    void setTypeSourceInfo(TypeSourceInfo *newType) {
      MaybeModedTInfo = newType;
    }
    void setModedTypeSourceInfo(TypeSourceInfo *unmodedTSI, QualType modedTy) {
      MaybeModedTInfo = new (getASTContext()) ModedTInfo(unmodedTSI, modedTy);
    }
  
    /// Retrieves the canonical declaration of this typedef-name.
    TypedefNameDecl *getCanonicalDecl() override { return getFirstDecl(); }
    const TypedefNameDecl *getCanonicalDecl() const { return getFirstDecl(); }
  
    // Implement isa/cast/dyncast/etc.
    static bool classof(const Decl *D) { return classofKind(D->getKind()); }
    static bool classofKind(Kind K) {
      return K >= firstTypedefName && K <= lastTypedefName;
    }
  };
  
  /// TypedefDecl - Represents the declaration of a typedef-name via the 'typedef'
  /// type specifier.
  class TypedefDecl : public TypedefNameDecl {
    TypedefDecl(ASTContext &C, DeclContext *DC, SourceLocation StartLoc,
                SourceLocation IdLoc, IdentifierInfo *Id, TypeSourceInfo *TInfo)
        : TypedefNameDecl(Typedef, C, DC, StartLoc, IdLoc, Id, TInfo) {}
  
  public:
    static TypedefDecl *Create(ASTContext &C, DeclContext *DC,
                               SourceLocation StartLoc, SourceLocation IdLoc,
                               IdentifierInfo *Id, TypeSourceInfo *TInfo);
    static TypedefDecl *CreateDeserialized(ASTContext &C, unsigned ID);
  
    SourceRange getSourceRange() const override LLVM_READONLY;
  
    // Implement isa/cast/dyncast/etc.
    static bool classof(const Decl *D) { return classofKind(D->getKind()); }
    static bool classofKind(Kind K) { return K == Typedef; }
  };
  
  /// TypeAliasDecl - Represents the declaration of a typedef-name via a C++0x
  /// alias-declaration.
  class TypeAliasDecl : public TypedefNameDecl {
    /// The template for which this is the pattern, if any.
    TypeAliasTemplateDecl *Template;
  
    TypeAliasDecl(ASTContext &C, DeclContext *DC, SourceLocation StartLoc,
                  SourceLocation IdLoc, IdentifierInfo *Id, TypeSourceInfo *TInfo)
        : TypedefNameDecl(TypeAlias, C, DC, StartLoc, IdLoc, Id, TInfo),
          Template(nullptr) {}
  
  public:
    static TypeAliasDecl *Create(ASTContext &C, DeclContext *DC,
                                 SourceLocation StartLoc, SourceLocation IdLoc,
                                 IdentifierInfo *Id, TypeSourceInfo *TInfo);
    static TypeAliasDecl *CreateDeserialized(ASTContext &C, unsigned ID);
  
    SourceRange getSourceRange() const override LLVM_READONLY;
  
    TypeAliasTemplateDecl *getDescribedAliasTemplate() const { return Template; }
    void setDescribedAliasTemplate(TypeAliasTemplateDecl *TAT) { Template = TAT; }
  
    // Implement isa/cast/dyncast/etc.
    static bool classof(const Decl *D) { return classofKind(D->getKind()); }
    static bool classofKind(Kind K) { return K == TypeAlias; }
  };
  
  /// TagDecl - Represents the declaration of a struct/union/class/enum.
  class TagDecl
    : public TypeDecl, public DeclContext, public Redeclarable<TagDecl> {
  public:
    // This is really ugly.
    typedef TagTypeKind TagKind;
  
  private:
    // FIXME: This can be packed into the bitfields in Decl.
    /// TagDeclKind - The TagKind enum.
    unsigned TagDeclKind : 3;
  
    /// IsCompleteDefinition - True if this is a definition ("struct foo
    /// {};"), false if it is a declaration ("struct foo;").  It is not
    /// a definition until the definition has been fully processed.
    bool IsCompleteDefinition : 1;
  
  protected:
    /// IsBeingDefined - True if this is currently being defined.
    bool IsBeingDefined : 1;
  
  private:
    /// IsEmbeddedInDeclarator - True if this tag declaration is
    /// "embedded" (i.e., defined or declared for the very first time)
    /// in the syntax of a declarator.
    bool IsEmbeddedInDeclarator : 1;
  
    /// \brief True if this tag is free standing, e.g. "struct foo;".
    bool IsFreeStanding : 1;
  
  protected:
    // These are used by (and only defined for) EnumDecl.
    unsigned NumPositiveBits : 8;
    unsigned NumNegativeBits : 8;
  
    /// IsScoped - True if this tag declaration is a scoped enumeration. Only
    /// possible in C++11 mode.
    bool IsScoped : 1;
    /// IsScopedUsingClassTag - 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.
    bool IsScopedUsingClassTag : 1;
  
    /// IsFixed - True if this is an enumeration with fixed underlying type. Only
    /// possible in C++11, Microsoft extensions, or Objective C mode.
    bool IsFixed : 1;
  
    /// \brief 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.
    bool MayHaveOutOfDateDef : 1;
  
    /// Has the full definition of this type been required by a use somewhere in
    /// the TU.
    bool IsCompleteDefinitionRequired : 1;
  private:
    SourceLocation RBraceLoc;
  
    // A struct representing syntactic qualifier info,
    // to be used for the (uncommon) case of out-of-line declarations.
    typedef QualifierInfo ExtInfo;
  
    /// \brief If the (out-of-line) tag declaration name
    /// is qualified, it points to the qualifier info (nns and range);
    /// otherwise, if the tag declaration is anonymous and it is part of
    /// a typedef or alias, it points to the TypedefNameDecl (used for mangling);
    /// otherwise, if the tag declaration is anonymous and it is used as a
    /// declaration specifier for variables, it points to the first VarDecl (used
    /// for mangling);
    /// otherwise, it is a null (TypedefNameDecl) pointer.
    llvm::PointerUnion<NamedDecl *, ExtInfo *> NamedDeclOrQualifier;
  
    bool hasExtInfo() const { return NamedDeclOrQualifier.is<ExtInfo *>(); }
    ExtInfo *getExtInfo() { return NamedDeclOrQualifier.get<ExtInfo *>(); }
    const ExtInfo *getExtInfo() const {
      return NamedDeclOrQualifier.get<ExtInfo *>();
    }
  
  protected:
    TagDecl(Kind DK, TagKind TK, const ASTContext &C, DeclContext *DC,
            SourceLocation L, IdentifierInfo *Id, TagDecl *PrevDecl,
            SourceLocation StartL)
        : TypeDecl(DK, DC, L, Id, StartL), DeclContext(DK), redeclarable_base(C),
          TagDeclKind(TK), IsCompleteDefinition(false), IsBeingDefined(false),
          IsEmbeddedInDeclarator(false), IsFreeStanding(false),
          IsCompleteDefinitionRequired(false),
          NamedDeclOrQualifier((NamedDecl *)nullptr) {
      assert((DK != Enum || TK == TTK_Enum) &&
             "EnumDecl not matched with TTK_Enum");
      setPreviousDecl(PrevDecl);
    }
  
    typedef Redeclarable<TagDecl> redeclarable_base;
    TagDecl *getNextRedeclarationImpl() override {
      return getNextRedeclaration();
    }
    TagDecl *getPreviousDeclImpl() override {
      return getPreviousDecl();
    }
    TagDecl *getMostRecentDeclImpl() override {
      return getMostRecentDecl();
    }
  
    /// @brief Completes the definition of this tag declaration.
    ///
    /// This is a helper function for derived classes.
    void completeDefinition();
  
  public:
    typedef redeclarable_base::redecl_range redecl_range;
    typedef redeclarable_base::redecl_iterator redecl_iterator;
    using redeclarable_base::redecls_begin;
    using redeclarable_base::redecls_end;
    using redeclarable_base::redecls;
    using redeclarable_base::getPreviousDecl;
    using redeclarable_base::getMostRecentDecl;
    using redeclarable_base::isFirstDecl;
  
    SourceLocation getRBraceLoc() const { return RBraceLoc; }
    void setRBraceLoc(SourceLocation L) { RBraceLoc = L; }
  
    /// getInnerLocStart - Return SourceLocation representing start of source
    /// range ignoring outer template declarations.
    SourceLocation getInnerLocStart() const { return getLocStart(); }
  
    /// getOuterLocStart - Return SourceLocation representing start of source
    /// range taking into account any outer template declarations.
    SourceLocation getOuterLocStart() const;
    SourceRange getSourceRange() const override LLVM_READONLY;
  
    TagDecl *getCanonicalDecl() override;
    const TagDecl *getCanonicalDecl() const {
      return const_cast<TagDecl*>(this)->getCanonicalDecl();
    }
  
    /// isThisDeclarationADefinition() - Return true if this declaration
    /// is a completion definition of the type.  Provided for consistency.
    bool isThisDeclarationADefinition() const {
      return isCompleteDefinition();
    }
  
    /// isCompleteDefinition - Return true if this decl has its body
    /// fully specified.
    bool isCompleteDefinition() const {
      return IsCompleteDefinition;
    }
  
    /// \brief Return true if this complete decl is
    /// required to be complete for some existing use.
    bool isCompleteDefinitionRequired() const {
      return IsCompleteDefinitionRequired;
    }
  
    /// isBeingDefined - Return true if this decl is currently being defined.
    bool isBeingDefined() const {
      return IsBeingDefined;
    }
  
    bool isEmbeddedInDeclarator() const {
      return IsEmbeddedInDeclarator;
    }
    void setEmbeddedInDeclarator(bool isInDeclarator) {
      IsEmbeddedInDeclarator = isInDeclarator;
    }
  
    bool isFreeStanding() const { return IsFreeStanding; }
    void setFreeStanding(bool isFreeStanding = true) {
      IsFreeStanding = isFreeStanding;
    }
  
    /// \brief Whether this declaration declares a type that is
    /// dependent, i.e., a type that somehow depends on template
    /// parameters.
    bool isDependentType() const { return isDependentContext(); }
  
    /// @brief Starts the definition of this tag declaration.
    ///
    /// This method should be invoked at the beginning of the definition
    /// of this tag declaration. It will set the tag type into a state
    /// where it is in the process of being defined.
    void startDefinition();
  
    /// getDefinition - Returns the TagDecl that actually defines this
    ///  struct/union/class/enum.  When determining whether or not a
    ///  struct/union/class/enum has a definition, one should use this
    ///  method as opposed to 'isDefinition'.  'isDefinition' indicates
    ///  whether or not a specific TagDecl is defining declaration, not
    ///  whether or not the struct/union/class/enum type is defined.
    ///  This method returns NULL if there is no TagDecl that defines
    ///  the struct/union/class/enum.
    TagDecl *getDefinition() const;
  
    void setCompleteDefinition(bool V) { IsCompleteDefinition = V; }
  
    void setCompleteDefinitionRequired(bool V = true) {
      IsCompleteDefinitionRequired = V;
    }
  
    StringRef getKindName() const {
      return TypeWithKeyword::getTagTypeKindName(getTagKind());
    }
  
    TagKind getTagKind() const {
      return TagKind(TagDeclKind);
    }
  
    void setTagKind(TagKind TK) { TagDeclKind = TK; }
  
    bool isStruct() const { return getTagKind() == TTK_Struct; }
    bool isInterface() const { return getTagKind() == TTK_Interface; }
    bool isClass()  const { return getTagKind() == TTK_Class; }
    bool isUnion()  const { return getTagKind() == TTK_Union; }
    bool isEnum()   const { return getTagKind() == TTK_Enum; }
  
    /// Is this tag type named, either directly or via being defined in
    /// a typedef of this type?
    ///
    /// C++11 [basic.link]p8:
    ///   A type is said to have linkage if and only if:
    ///     - it is a class or enumeration type that is named (or has a
    ///       name for linkage purposes) and the name has linkage; ...
    /// C++11 [dcl.typedef]p9:
    ///   If the typedef declaration defines an unnamed class (or enum),
    ///   the first typedef-name declared by the declaration to be that
    ///   class type (or enum type) is used to denote the class type (or
    ///   enum type) for linkage purposes only.
    ///
    /// C does not have an analogous rule, but the same concept is
    /// nonetheless useful in some places.
    bool hasNameForLinkage() const {
      return (getDeclName() || getTypedefNameForAnonDecl());
    }
  
    bool hasDeclaratorForAnonDecl() const {
      return dyn_cast_or_null<DeclaratorDecl>(
          NamedDeclOrQualifier.get<NamedDecl *>());
    }
    DeclaratorDecl *getDeclaratorForAnonDecl() const {
      return hasExtInfo() ? nullptr : dyn_cast_or_null<DeclaratorDecl>(
                                    NamedDeclOrQualifier.get<NamedDecl *>());
    }
  
    TypedefNameDecl *getTypedefNameForAnonDecl() const {
      return hasExtInfo() ? nullptr : dyn_cast_or_null<TypedefNameDecl>(
                                    NamedDeclOrQualifier.get<NamedDecl *>());
    }
  
    void setDeclaratorForAnonDecl(DeclaratorDecl *DD) { NamedDeclOrQualifier = DD; }
  
    void setTypedefNameForAnonDecl(TypedefNameDecl *TDD);
  
    /// \brief Retrieve the nested-name-specifier that qualifies the name of this
    /// declaration, if it was present in the source.
    NestedNameSpecifier *getQualifier() const {
      return hasExtInfo() ? getExtInfo()->QualifierLoc.getNestedNameSpecifier()
                          : nullptr;
    }
  
    /// \brief Retrieve the nested-name-specifier (with source-location
    /// information) that qualifies the name of this declaration, if it was
    /// present in the source.
    NestedNameSpecifierLoc getQualifierLoc() const {
      return hasExtInfo() ? getExtInfo()->QualifierLoc
                          : NestedNameSpecifierLoc();
    }
  
    void setQualifierInfo(NestedNameSpecifierLoc QualifierLoc);
  
    unsigned getNumTemplateParameterLists() const {
      return hasExtInfo() ? getExtInfo()->NumTemplParamLists : 0;
    }
    TemplateParameterList *getTemplateParameterList(unsigned i) const {
      assert(i < getNumTemplateParameterLists());
      return getExtInfo()->TemplParamLists[i];
    }
    void setTemplateParameterListsInfo(ASTContext &Context, unsigned NumTPLists,
                                       TemplateParameterList **TPLists);
  
    // Implement isa/cast/dyncast/etc.
    static bool classof(const Decl *D) { return classofKind(D->getKind()); }
    static bool classofKind(Kind K) { return K >= firstTag && K <= lastTag; }
  
    static DeclContext *castToDeclContext(const TagDecl *D) {
      return static_cast<DeclContext *>(const_cast<TagDecl*>(D));
    }
    static TagDecl *castFromDeclContext(const DeclContext *DC) {
      return static_cast<TagDecl *>(const_cast<DeclContext*>(DC));
    }
  
    friend class ASTDeclReader;
    friend class ASTDeclWriter;
  };
  
  /// EnumDecl - Represents an enum.  In C++11, enums can be forward-declared
  /// with a fixed underlying type, and in C we allow them to be forward-declared
  /// with no underlying type as an extension.
  class EnumDecl : public TagDecl {
    void anchor() override;
    /// IntegerType - This represent the integer type that the enum corresponds
    /// to for code generation purposes.  Note that the enumerator constants may
    /// have a different type than this does.
    ///
    /// If the underlying integer type was explicitly stated in the source
    /// code, this is a TypeSourceInfo* for that type. Otherwise this type
    /// was automatically deduced somehow, and this is a Type*.
    ///
    /// Normally if IsFixed(), this would contain a TypeSourceInfo*, but in
    /// some cases it won't.
    ///
    /// The underlying type of an enumeration never has any qualifiers, so
    /// we can get away with just storing a raw Type*, and thus save an
    /// extra pointer when TypeSourceInfo is needed.
  
    llvm::PointerUnion<const Type*, TypeSourceInfo*> IntegerType;
  
    /// PromotionType - The integer type that values of this type should
    /// promote to.  In C, enumerators are generally of an integer type
    /// directly, but gcc-style large enumerators (and all enumerators
    /// in C++) are of the enum type instead.
    QualType PromotionType;
  
    /// \brief If this enumeration is an instantiation of a member enumeration
    /// of a class template specialization, this is the member specialization
    /// information.
    MemberSpecializationInfo *SpecializationInfo;
  
    EnumDecl(ASTContext &C, DeclContext *DC, SourceLocation StartLoc,
             SourceLocation IdLoc, IdentifierInfo *Id, EnumDecl *PrevDecl,
             bool Scoped, bool ScopedUsingClassTag, bool Fixed)
        : TagDecl(Enum, TTK_Enum, C, DC, IdLoc, Id, PrevDecl, StartLoc),
          SpecializationInfo(nullptr) {
      assert(Scoped || !ScopedUsingClassTag);
      IntegerType = (const Type *)nullptr;
      NumNegativeBits = 0;
      NumPositiveBits = 0;
      IsScoped = Scoped;
      IsScopedUsingClassTag = ScopedUsingClassTag;
      IsFixed = Fixed;
    }
  
    void setInstantiationOfMemberEnum(ASTContext &C, EnumDecl *ED,
                                      TemplateSpecializationKind TSK);
  public:
    EnumDecl *getCanonicalDecl() override {
      return cast<EnumDecl>(TagDecl::getCanonicalDecl());
    }
    const EnumDecl *getCanonicalDecl() const {
      return const_cast<EnumDecl*>(this)->getCanonicalDecl();
    }
  
    EnumDecl *getPreviousDecl() {
      return cast_or_null<EnumDecl>(
              static_cast<TagDecl *>(this)->getPreviousDecl());
    }
    const EnumDecl *getPreviousDecl() const {
      return const_cast<EnumDecl*>(this)->getPreviousDecl();
    }
  
    EnumDecl *getMostRecentDecl() {
      return cast<EnumDecl>(static_cast<TagDecl *>(this)->getMostRecentDecl());
    }
    const EnumDecl *getMostRecentDecl() const {
      return const_cast<EnumDecl*>(this)->getMostRecentDecl();
    }
  
    EnumDecl *getDefinition() const {
      return cast_or_null<EnumDecl>(TagDecl::getDefinition());
    }
  
    static EnumDecl *Create(ASTContext &C, DeclContext *DC,
                            SourceLocation StartLoc, SourceLocation IdLoc,
                            IdentifierInfo *Id, EnumDecl *PrevDecl,
                            bool IsScoped, bool IsScopedUsingClassTag,
                            bool IsFixed);
    static EnumDecl *CreateDeserialized(ASTContext &C, unsigned ID);
  
    /// completeDefinition - When created, the EnumDecl corresponds to a
    /// forward-declared enum. This method is used to mark the
    /// declaration as being defined; it's enumerators have already been
    /// added (via DeclContext::addDecl). NewType is the new underlying
    /// type of the enumeration type.
    void completeDefinition(QualType NewType,
                            QualType PromotionType,
                            unsigned NumPositiveBits,
                            unsigned NumNegativeBits);
  
    // enumerator_iterator - Iterates through the enumerators of this
    // enumeration.
    typedef specific_decl_iterator<EnumConstantDecl> enumerator_iterator;
    typedef llvm::iterator_range<specific_decl_iterator<EnumConstantDecl>>
      enumerator_range;
  
    enumerator_range enumerators() const {
      return enumerator_range(enumerator_begin(), enumerator_end());
    }
  
    enumerator_iterator enumerator_begin() const {
      const EnumDecl *E = getDefinition();
      if (!E)
        E = this;
      return enumerator_iterator(E->decls_begin());
    }
  
    enumerator_iterator enumerator_end() const {
      const EnumDecl *E = getDefinition();
      if (!E)
        E = this;
      return enumerator_iterator(E->decls_end());
    }
  
    /// getPromotionType - Return the integer type that enumerators
    /// should promote to.
    QualType getPromotionType() const { return PromotionType; }
  
    /// \brief Set the promotion type.
    void setPromotionType(QualType T) { PromotionType = T; }
  
    /// getIntegerType - Return the integer type this enum decl corresponds to.
    /// This returns a null QualType for an enum forward definition with no fixed
    /// underlying type.
    QualType getIntegerType() const {
      if (!IntegerType)
        return QualType();
      if (const Type *T = IntegerType.dyn_cast<const Type*>())
        return QualType(T, 0);
      return IntegerType.get<TypeSourceInfo*>()->getType().getUnqualifiedType();
    }
  
    /// \brief Set the underlying integer type.
    void setIntegerType(QualType T) { IntegerType = T.getTypePtrOrNull(); }
  
    /// \brief Set the underlying integer type source info.
    void setIntegerTypeSourceInfo(TypeSourceInfo *TInfo) { IntegerType = TInfo; }
  
    /// \brief Return the type source info for the underlying integer type,
    /// if no type source info exists, return 0.
    TypeSourceInfo *getIntegerTypeSourceInfo() const {
      return IntegerType.dyn_cast<TypeSourceInfo*>();
    }
  
    /// \brief Retrieve the source range that covers the underlying type if
    /// specified.
    SourceRange getIntegerTypeRange() const LLVM_READONLY;
  
    /// \brief Returns the width in bits required to store all the
    /// non-negative enumerators of this enum.
    unsigned getNumPositiveBits() const {
      return NumPositiveBits;
    }
    void setNumPositiveBits(unsigned Num) {
      NumPositiveBits = Num;
      assert(NumPositiveBits == Num && "can't store this bitcount");
    }
  
    /// \brief Returns the width in bits required to store all the
    /// negative enumerators of this enum.  These widths include
    /// the rightmost leading 1;  that is:
    ///
    /// MOST NEGATIVE ENUMERATOR     PATTERN     NUM NEGATIVE BITS
    /// ------------------------     -------     -----------------
    ///                       -1     1111111                     1
    ///                      -10     1110110                     5
    ///                     -101     1001011                     8
    unsigned getNumNegativeBits() const {
      return NumNegativeBits;
    }
    void setNumNegativeBits(unsigned Num) {
      NumNegativeBits = Num;
    }
  
    /// \brief Returns true if this is a C++11 scoped enumeration.
    bool isScoped() const {
      return IsScoped;
    }
  
    /// \brief Returns true if this is a C++11 scoped enumeration.
    bool isScopedUsingClassTag() const {
      return IsScopedUsingClassTag;
    }
  
    /// \brief Returns true if this is an Objective-C, C++11, or
    /// Microsoft-style enumeration with a fixed underlying type.
    bool isFixed() const {
      return IsFixed;
    }
  
    /// \brief Returns true if this can be considered a complete type.
    bool isComplete() const {
      return isCompleteDefinition() || isFixed();
    }
  
    /// \brief Returns the enumeration (declared within the template)
    /// from which this enumeration type was instantiated, or NULL if
    /// this enumeration was not instantiated from any template.
    EnumDecl *getInstantiatedFromMemberEnum() const;
  
    /// \brief If this enumeration is a member of a specialization of a
    /// templated class, determine what kind of template specialization
    /// or instantiation this is.
    TemplateSpecializationKind getTemplateSpecializationKind() const;
  
    /// \brief For an enumeration member that was instantiated from a member
    /// enumeration of a templated class, set the template specialiation kind.
    void setTemplateSpecializationKind(TemplateSpecializationKind TSK,
                          SourceLocation PointOfInstantiation = SourceLocation());
  
    /// \brief If this enumeration is an instantiation of a member enumeration of
    /// a class template specialization, retrieves the member specialization
    /// information.
    MemberSpecializationInfo *getMemberSpecializationInfo() const {
      return SpecializationInfo;
    }
  
    /// \brief Specify that this enumeration is an instantiation of the
    /// member enumeration ED.
    void setInstantiationOfMemberEnum(EnumDecl *ED,
                                      TemplateSpecializationKind TSK) {
      setInstantiationOfMemberEnum(getASTContext(), ED, TSK);
    }
  
    static bool classof(const Decl *D) { return classofKind(D->getKind()); }
    static bool classofKind(Kind K) { return K == Enum; }
  
    friend class ASTDeclReader;
  };
  
  
  /// RecordDecl - Represents a struct/union/class.  For example:
  ///   struct X;                  // Forward declaration, no "body".
  ///   union Y { int A, B; };     // Has body with members A and B (FieldDecls).
  /// This decl will be marked invalid if *any* members are invalid.
  ///
  class RecordDecl : public TagDecl {
    // FIXME: This can be packed into the bitfields in Decl.
    /// HasFlexibleArrayMember - 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.
    bool HasFlexibleArrayMember : 1;
  
    /// AnonymousStructOrUnion - Whether this is the type of an anonymous struct
    /// or union.
    bool AnonymousStructOrUnion : 1;
  
    /// HasObjectMember - This is true if this struct has at least one member
    /// containing an Objective-C object pointer type.
    bool HasObjectMember : 1;
    
    /// HasVolatileMember - This is true if struct has at least one member of
    /// 'volatile' type.
    bool HasVolatileMember : 1;
  
    /// \brief Whether the field declarations of this record have been loaded
    /// from external storage. To avoid unnecessary deserialization of
    /// methods/nested types we allow deserialization of just the fields
    /// when needed.
    mutable bool LoadedFieldsFromExternalStorage : 1;
    friend class DeclContext;
  
  protected:
    RecordDecl(Kind DK, TagKind TK, const ASTContext &C, DeclContext *DC,
               SourceLocation StartLoc, SourceLocation IdLoc,
               IdentifierInfo *Id, RecordDecl *PrevDecl);
  
  public:
    static RecordDecl *Create(const ASTContext &C, TagKind TK, DeclContext *DC,
                              SourceLocation StartLoc, SourceLocation IdLoc,
                              IdentifierInfo *Id, RecordDecl* PrevDecl = nullptr);
    static RecordDecl *CreateDeserialized(const ASTContext &C, unsigned ID);
  
    RecordDecl *getPreviousDecl() {
      return cast_or_null<RecordDecl>(
              static_cast<TagDecl *>(this)->getPreviousDecl());
    }
    const RecordDecl *getPreviousDecl() const {
      return const_cast<RecordDecl*>(this)->getPreviousDecl();
    }
  
    RecordDecl *getMostRecentDecl() {
      return cast<RecordDecl>(static_cast<TagDecl *>(this)->getMostRecentDecl());
    }
    const RecordDecl *getMostRecentDecl() const {
      return const_cast<RecordDecl*>(this)->getMostRecentDecl();
    }
  
    bool hasFlexibleArrayMember() const { return HasFlexibleArrayMember; }
    void setHasFlexibleArrayMember(bool V) { HasFlexibleArrayMember = V; }
  
    /// isAnonymousStructOrUnion - Whether this is an anonymous struct
    /// or union. To be an anonymous struct or union, it must have been
    /// declared without a name and there must be no objects of this
    /// type declared, e.g.,
    /// @code
    ///   union { int i; float f; };
    /// @endcode
    /// is an anonymous union but neither of the following are:
    /// @code
    ///  union X { int i; float f; };
    ///  union { int i; float f; } obj;
    /// @endcode
    bool isAnonymousStructOrUnion() const { return AnonymousStructOrUnion; }
    void setAnonymousStructOrUnion(bool Anon) {
      AnonymousStructOrUnion = Anon;
    }
  
    bool hasObjectMember() const { return HasObjectMember; }
    void setHasObjectMember (bool val) { HasObjectMember = val; }
  
    bool hasVolatileMember() const { return HasVolatileMember; }
    void setHasVolatileMember (bool val) { HasVolatileMember = val; }
    
    /// \brief Determines whether this declaration represents the
    /// injected class name.
    ///
    /// The injected class name in C++ is the name of the class that
    /// appears inside the class itself. For example:
    ///
    /// \code
    /// struct C {
    ///   // C is implicitly declared here as a synonym for the class name.
    /// };
    ///
    /// C::C c; // same as "C c;"
    /// \endcode
    bool isInjectedClassName() const;
  
    /// \brief Determine whether this record is a class describing a lambda
    /// function object.
    bool isLambda() const;
  
    /// \brief Determine whether this record is a record for captured variables in
    /// CapturedStmt construct.
    bool isCapturedRecord() const;
    /// \brief Mark the record as a record for captured variables in CapturedStmt
    /// construct.
    void setCapturedRecord();
  
    /// getDefinition - Returns the RecordDecl that actually defines
    ///  this struct/union/class.  When determining whether or not a
    ///  struct/union/class is completely defined, one should use this
    ///  method as opposed to 'isCompleteDefinition'.
    ///  'isCompleteDefinition' indicates whether or not a specific
    ///  RecordDecl is a completed definition, not whether or not the
    ///  record type is defined.  This method returns NULL if there is
    ///  no RecordDecl that defines the struct/union/tag.
    RecordDecl *getDefinition() const {
      return cast_or_null<RecordDecl>(TagDecl::getDefinition());
    }
  
    // Iterator access to field members. The field iterator only visits
    // the non-static data members of this class, ignoring any static
    // data members, functions, constructors, destructors, etc.
    typedef specific_decl_iterator<FieldDecl> field_iterator;
    typedef llvm::iterator_range<specific_decl_iterator<FieldDecl>> field_range;
  
    field_range fields() const { return field_range(field_begin(), field_end()); }
    field_iterator field_begin() const;
  
    field_iterator field_end() const {
      return field_iterator(decl_iterator());
    }
  
    // field_empty - Whether there are any fields (non-static data
    // members) in this record.
    bool field_empty() const {
      return field_begin() == field_end();
    }
  
    /// completeDefinition - Notes that the definition of this type is
    /// now complete.
    virtual void completeDefinition();
  
    static bool classof(const Decl *D) { return classofKind(D->getKind()); }
    static bool classofKind(Kind K) {
      return K >= firstRecord && K <= lastRecord;
    }
  
    /// isMsStrust - Get whether or not this is an ms_struct which can
    /// be turned on with an attribute, pragma, or -mms-bitfields
    /// commandline option.
    bool isMsStruct(const ASTContext &C) const;
  
    /// \brief Whether we are allowed to insert extra padding between fields.
    /// These padding are added to help AddressSanitizer detect
    /// intra-object-overflow bugs.
    bool mayInsertExtraPadding(bool EmitRemark = false) const;
  
    /// Finds the first data member which has a name.
    /// nullptr is returned if no named data member exists.
    const FieldDecl *findFirstNamedDataMember() const;  
  
  private:
    /// \brief Deserialize just the fields.
    void LoadFieldsFromExternalStorage() const;
  };
  
  class FileScopeAsmDecl : public Decl {
    virtual void anchor();
    StringLiteral *AsmString;
    SourceLocation RParenLoc;
    FileScopeAsmDecl(DeclContext *DC, StringLiteral *asmstring,
                     SourceLocation StartL, SourceLocation EndL)
      : Decl(FileScopeAsm, DC, StartL), AsmString(asmstring), RParenLoc(EndL) {}
  public:
    static FileScopeAsmDecl *Create(ASTContext &C, DeclContext *DC,
                                    StringLiteral *Str, SourceLocation AsmLoc,
                                    SourceLocation RParenLoc);
  
    static FileScopeAsmDecl *CreateDeserialized(ASTContext &C, unsigned ID);
    
    SourceLocation getAsmLoc() const { return getLocation(); }
    SourceLocation getRParenLoc() const { return RParenLoc; }
    void setRParenLoc(SourceLocation L) { RParenLoc = L; }
    SourceRange getSourceRange() const override LLVM_READONLY {
      return SourceRange(getAsmLoc(), getRParenLoc());
    }
  
    const StringLiteral *getAsmString() const { return AsmString; }
    StringLiteral *getAsmString() { return AsmString; }
    void setAsmString(StringLiteral *Asm) { AsmString = Asm; }
  
    static bool classof(const Decl *D) { return classofKind(D->getKind()); }
    static bool classofKind(Kind K) { return K == FileScopeAsm; }
  };
  
  /// BlockDecl - This represents a block literal declaration, which is like an
  /// unnamed FunctionDecl.  For example:
  /// ^{ statement-body }   or   ^(int arg1, float arg2){ statement-body }
  ///
  class BlockDecl : public Decl, public DeclContext {
  public:
    /// A class which contains all the information about a particular
    /// captured value.
    class Capture {
      enum {
        flag_isByRef = 0x1,
        flag_isNested = 0x2
      };
  
      /// The variable being captured.
      llvm::PointerIntPair<VarDecl*, 2> VariableAndFlags;
  
      /// The copy expression, expressed in terms of a DeclRef (or
      /// BlockDeclRef) to the captured variable.  Only required if the
      /// variable has a C++ class type.
      Expr *CopyExpr;
  
    public:
      Capture(VarDecl *variable, bool byRef, bool nested, Expr *copy)
        : VariableAndFlags(variable,
                    (byRef ? flag_isByRef : 0) | (nested ? flag_isNested : 0)),
          CopyExpr(copy) {}
  
      /// The variable being captured.
      VarDecl *getVariable() const { return VariableAndFlags.getPointer(); }
  
      /// Whether this is a "by ref" capture, i.e. a capture of a __block
      /// variable.
      bool isByRef() const { return VariableAndFlags.getInt() & flag_isByRef; }
  
      /// Whether this is a nested capture, i.e. the variable captured
      /// is not from outside the immediately enclosing function/block.
      bool isNested() const { return VariableAndFlags.getInt() & flag_isNested; }
  
      bool hasCopyExpr() const { return CopyExpr != nullptr; }
      Expr *getCopyExpr() const { return CopyExpr; }
      void setCopyExpr(Expr *e) { CopyExpr = e; }
    };
  
  private:
    // FIXME: This can be packed into the bitfields in Decl.
    bool IsVariadic : 1;
    bool CapturesCXXThis : 1;
    bool BlockMissingReturnType : 1;
    bool IsConversionFromLambda : 1;
    /// ParamInfo - new[]'d array of pointers to ParmVarDecls for the formal
    /// parameters of this function.  This is null if a prototype or if there are
    /// no formals.
    ParmVarDecl **ParamInfo;
    unsigned NumParams;
  
    Stmt *Body;
    TypeSourceInfo *SignatureAsWritten;
  
    Capture *Captures;
    unsigned NumCaptures;
  
    unsigned ManglingNumber;
    Decl *ManglingContextDecl;
  
  protected:
    BlockDecl(DeclContext *DC, SourceLocation CaretLoc)
      : Decl(Block, DC, CaretLoc), DeclContext(Block),
        IsVariadic(false), CapturesCXXThis(false),
        BlockMissingReturnType(true), IsConversionFromLambda(false),
        ParamInfo(nullptr), NumParams(0), Body(nullptr),
        SignatureAsWritten(nullptr), Captures(nullptr), NumCaptures(0),
        ManglingNumber(0), ManglingContextDecl(nullptr) {}
  
  public:
    static BlockDecl *Create(ASTContext &C, DeclContext *DC, SourceLocation L); 
    static BlockDecl *CreateDeserialized(ASTContext &C, unsigned ID);
    
    SourceLocation getCaretLocation() const { return getLocation(); }
  
    bool isVariadic() const { return IsVariadic; }
    void setIsVariadic(bool value) { IsVariadic = value; }
  
    CompoundStmt *getCompoundBody() const { return (CompoundStmt*) Body; }
    Stmt *getBody() const override { return (Stmt*) Body; }
    void setBody(CompoundStmt *B) { Body = (Stmt*) B; }
  
    void setSignatureAsWritten(TypeSourceInfo *Sig) { SignatureAsWritten = Sig; }
    TypeSourceInfo *getSignatureAsWritten() const { return SignatureAsWritten; }
  
    // Iterator access to formal parameters.
    unsigned param_size() const { return getNumParams(); }
    typedef ParmVarDecl **param_iterator;
    typedef ParmVarDecl * const *param_const_iterator;
    typedef llvm::iterator_range<param_iterator> param_range;
    typedef llvm::iterator_range<param_const_iterator> param_const_range;
  
    // ArrayRef access to formal parameters.
    // FIXME: Should eventual replace iterator access.
    ArrayRef<ParmVarDecl*> parameters() const {
      return llvm::makeArrayRef(ParamInfo, param_size());
    }
  
    bool param_empty() const { return NumParams == 0; }
    param_range params() { return param_range(param_begin(), param_end()); }
    param_iterator param_begin() { return param_iterator(ParamInfo); }
    param_iterator param_end() {
      return param_iterator(ParamInfo + param_size());
    }
  
    param_const_range params() const {
      return param_const_range(param_begin(), param_end());
    }
    param_const_iterator param_begin() const {
      return param_const_iterator(ParamInfo);
    }
    param_const_iterator param_end() const {
      return param_const_iterator(ParamInfo + param_size());
    }
  
    unsigned getNumParams() const { return NumParams; }
    const ParmVarDecl *getParamDecl(unsigned i) const {
      assert(i < getNumParams() && "Illegal param #");
      return ParamInfo[i];
    }
    ParmVarDecl *getParamDecl(unsigned i) {
      assert(i < getNumParams() && "Illegal param #");
      return ParamInfo[i];
    }
    void setParams(ArrayRef<ParmVarDecl *> NewParamInfo);
  
    /// hasCaptures - True if this block (or its nested blocks) captures
    /// anything of local storage from its enclosing scopes.
    bool hasCaptures() const { return NumCaptures != 0 || CapturesCXXThis; }
  
    /// getNumCaptures - Returns the number of captured variables.
    /// Does not include an entry for 'this'.
    unsigned getNumCaptures() const { return NumCaptures; }
  
    typedef const Capture *capture_iterator;
    typedef const Capture *capture_const_iterator;
    typedef llvm::iterator_range<capture_iterator> capture_range;
    typedef llvm::iterator_range<capture_const_iterator> capture_const_range;
  
    capture_range captures() {
      return capture_range(capture_begin(), capture_end());
    }
    capture_const_range captures() const {
      return capture_const_range(capture_begin(), capture_end());
    }
  
    capture_iterator capture_begin() { return Captures; }
    capture_iterator capture_end() { return Captures + NumCaptures; }
    capture_const_iterator capture_begin() const { return Captures; }
    capture_const_iterator capture_end() const { return Captures + NumCaptures; }
  
    bool capturesCXXThis() const { return CapturesCXXThis; }
    bool blockMissingReturnType() const { return BlockMissingReturnType; }
    void setBlockMissingReturnType(bool val) { BlockMissingReturnType = val; }
  
    bool isConversionFromLambda() const { return IsConversionFromLambda; }
    void setIsConversionFromLambda(bool val) { IsConversionFromLambda = val; }
  
    bool capturesVariable(const VarDecl *var) const;
  
    void setCaptures(ASTContext &Context,
                     const Capture *begin,
                     const Capture *end,
                     bool capturesCXXThis);
  
     unsigned getBlockManglingNumber() const {
       return ManglingNumber;
     }
     Decl *getBlockManglingContextDecl() const {
       return ManglingContextDecl;    
     }
  
    void setBlockMangling(unsigned Number, Decl *Ctx) {
      ManglingNumber = Number;
      ManglingContextDecl = Ctx;
    }
  
    SourceRange getSourceRange() const override LLVM_READONLY;
  
    // Implement isa/cast/dyncast/etc.
    static bool classof(const Decl *D) { return classofKind(D->getKind()); }
    static bool classofKind(Kind K) { return K == Block; }
    static DeclContext *castToDeclContext(const BlockDecl *D) {
      return static_cast<DeclContext *>(const_cast<BlockDecl*>(D));
    }
    static BlockDecl *castFromDeclContext(const DeclContext *DC) {
      return static_cast<BlockDecl *>(const_cast<DeclContext*>(DC));
    }
  };
  
  /// \brief This represents the body of a CapturedStmt, and serves as its
  /// DeclContext.
  class CapturedDecl : public Decl, public DeclContext {
  private:
    /// \brief The number of parameters to the outlined function.
    unsigned NumParams;
    /// \brief The position of context parameter in list of parameters.
    unsigned ContextParam;
    /// \brief The body of the outlined function.
    llvm::PointerIntPair<Stmt *, 1, bool> BodyAndNothrow;
  
    explicit CapturedDecl(DeclContext *DC, unsigned NumParams)
      : Decl(Captured, DC, SourceLocation()), DeclContext(Captured),
        NumParams(NumParams), ContextParam(0), BodyAndNothrow(nullptr, false) { }
  
    ImplicitParamDecl **getParams() const {
      return reinterpret_cast<ImplicitParamDecl **>(
               const_cast<CapturedDecl *>(this) + 1);
    }
  
  public:
    static CapturedDecl *Create(ASTContext &C, DeclContext *DC,
                                unsigned NumParams);
    static CapturedDecl *CreateDeserialized(ASTContext &C, unsigned ID,
                                            unsigned NumParams);
  
    Stmt *getBody() const override { return BodyAndNothrow.getPointer(); }
    void setBody(Stmt *B) { BodyAndNothrow.setPointer(B); }
  
    bool isNothrow() const { return BodyAndNothrow.getInt(); }
    void setNothrow(bool Nothrow = true) { BodyAndNothrow.setInt(Nothrow); }
  
    unsigned getNumParams() const { return NumParams; }
  
    ImplicitParamDecl *getParam(unsigned i) const {
      assert(i < NumParams);
      return getParams()[i];
    }
    void setParam(unsigned i, ImplicitParamDecl *P) {
      assert(i < NumParams);
      getParams()[i] = P;
    }
  
    /// \brief Retrieve the parameter containing captured variables.
    ImplicitParamDecl *getContextParam() const {
      assert(ContextParam < NumParams);
      return getParam(ContextParam);
    }
    void setContextParam(unsigned i, ImplicitParamDecl *P) {
      assert(i < NumParams);
      ContextParam = i;
      setParam(i, P);
    }
    unsigned getContextParamPosition() const { return ContextParam; }
  
    typedef ImplicitParamDecl **param_iterator;
    typedef llvm::iterator_range<param_iterator> param_range;
  
    /// \brief Retrieve an iterator pointing to the first parameter decl.
    param_iterator param_begin() const { return getParams(); }
    /// \brief Retrieve an iterator one past the last parameter decl.
    param_iterator param_end() const { return getParams() + NumParams; }
  
    /// \brief Retrieve an iterator range for the parameter declarations.
    param_range params() const { return param_range(param_begin(), param_end()); }
  
    // Implement isa/cast/dyncast/etc.
    static bool classof(const Decl *D) { return classofKind(D->getKind()); }
    static bool classofKind(Kind K) { return K == Captured; }
    static DeclContext *castToDeclContext(const CapturedDecl *D) {
      return static_cast<DeclContext *>(const_cast<CapturedDecl *>(D));
    }
    static CapturedDecl *castFromDeclContext(const DeclContext *DC) {
      return static_cast<CapturedDecl *>(const_cast<DeclContext *>(DC));
    }
  
    friend class ASTDeclReader;
    friend class ASTDeclWriter;
  };
  
  /// \brief Describes a module import declaration, which makes the contents
  /// of the named module visible in the current translation unit.
  ///
  /// An import declaration imports the named module (or submodule). For example:
  /// \code
  ///   @import std.vector;
  /// \endcode
  ///
  /// Import declarations can also be implicitly generated from
  /// \#include/\#import directives.
  class ImportDecl : public Decl {
    /// \brief The imported module, along with a bit that indicates whether
    /// we have source-location information for each identifier in the module
    /// name. 
    ///
    /// When the bit is false, we only have a single source location for the
    /// end of the import declaration.
    llvm::PointerIntPair<Module *, 1, bool> ImportedAndComplete;
    
    /// \brief The next import in the list of imports local to the translation
    /// unit being parsed (not loaded from an AST file).
    ImportDecl *NextLocalImport;
    
    friend class ASTReader;
    friend class ASTDeclReader;
    friend class ASTContext;
    
    ImportDecl(DeclContext *DC, SourceLocation StartLoc, Module *Imported,
               ArrayRef<SourceLocation> IdentifierLocs);
  
    ImportDecl(DeclContext *DC, SourceLocation StartLoc, Module *Imported,
               SourceLocation EndLoc);
  
    ImportDecl(EmptyShell Empty) : Decl(Import, Empty), NextLocalImport() { }
    
  public:
    /// \brief Create a new module import declaration.
    static ImportDecl *Create(ASTContext &C, DeclContext *DC, 
                              SourceLocation StartLoc, Module *Imported,
                              ArrayRef<SourceLocation> IdentifierLocs);
    
    /// \brief Create a new module import declaration for an implicitly-generated
    /// import.
    static ImportDecl *CreateImplicit(ASTContext &C, DeclContext *DC, 
                                      SourceLocation StartLoc, Module *Imported, 
                                      SourceLocation EndLoc);
    
    /// \brief Create a new, deserialized module import declaration.
    static ImportDecl *CreateDeserialized(ASTContext &C, unsigned ID, 
                                          unsigned NumLocations);
    
    /// \brief Retrieve the module that was imported by the import declaration.
    Module *getImportedModule() const { return ImportedAndComplete.getPointer(); }
    
    /// \brief Retrieves the locations of each of the identifiers that make up
    /// the complete module name in the import declaration.
    ///
    /// This will return an empty array if the locations of the individual
    /// identifiers aren't available.
    ArrayRef<SourceLocation> getIdentifierLocs() const;
  
    SourceRange getSourceRange() const override LLVM_READONLY;
  
    static bool classof(const Decl *D) { return classofKind(D->getKind()); }
    static bool classofKind(Kind K) { return K == Import; }
  };
  
  /// \brief Represents an empty-declaration.
  class EmptyDecl : public Decl {
    virtual void anchor();
    EmptyDecl(DeclContext *DC, SourceLocation L)
      : Decl(Empty, DC, L) { }
  
  public:
    static EmptyDecl *Create(ASTContext &C, DeclContext *DC,
                             SourceLocation L);
    static EmptyDecl *CreateDeserialized(ASTContext &C, unsigned ID);
  
    static bool classof(const Decl *D) { return classofKind(D->getKind()); }
    static bool classofKind(Kind K) { return K == Empty; }
  };
  
  /// Insertion operator for diagnostics.  This allows sending NamedDecl's
  /// into a diagnostic with <<.
  inline const DiagnosticBuilder &operator<<(const DiagnosticBuilder &DB,
                                             const NamedDecl* ND) {
    DB.AddTaggedVal(reinterpret_cast<intptr_t>(ND),
                    DiagnosticsEngine::ak_nameddecl);
    return DB;
  }
  inline const PartialDiagnostic &operator<<(const PartialDiagnostic &PD,
                                             const NamedDecl* ND) {
    PD.AddTaggedVal(reinterpret_cast<intptr_t>(ND),
                    DiagnosticsEngine::ak_nameddecl);
    return PD;
  }
  
  template<typename decl_type>
  void Redeclarable<decl_type>::setPreviousDecl(decl_type *PrevDecl) {
    // Note: This routine is implemented here because we need both NamedDecl
    // and Redeclarable to be defined.
    assert(RedeclLink.NextIsLatest() &&
           "setPreviousDecl on a decl already in a redeclaration chain");
  
    decl_type *First;
  
    if (PrevDecl) {
      // Point to previous. Make sure that this is actually the most recent
      // redeclaration, or we can build invalid chains. If the most recent
      // redeclaration is invalid, it won't be PrevDecl, but we want it anyway.
      First = PrevDecl->getFirstDecl();
      assert(First->RedeclLink.NextIsLatest() && "Expected first");
      decl_type *MostRecent = First->getNextRedeclaration();
      RedeclLink = PreviousDeclLink(cast<decl_type>(MostRecent));
  
      // If the declaration was previously visible, a redeclaration of it remains
      // visible even if it wouldn't be visible by itself.
      static_cast<decl_type*>(this)->IdentifierNamespace |=
        MostRecent->getIdentifierNamespace() &
        (Decl::IDNS_Ordinary | Decl::IDNS_Tag | Decl::IDNS_Type);
    } else {
      // Make this first.
      First = static_cast<decl_type*>(this);
    }
  
    // First one will point to this one as latest.
    First->RedeclLink.setLatest(static_cast<decl_type*>(this));
  
    assert(!isa<NamedDecl>(static_cast<decl_type*>(this)) ||
           cast<NamedDecl>(static_cast<decl_type*>(this))->isLinkageValid());
  }
  
  // Inline function definitions.
  
  /// \brief Check if the given decl is complete.
  ///
  /// We use this function to break a cycle between the inline definitions in
  /// Type.h and Decl.h.
  inline bool IsEnumDeclComplete(EnumDecl *ED) {
    return ED->isComplete();
  }
  
  /// \brief Check if the given decl is scoped.
  ///
  /// We use this function to break a cycle between the inline definitions in
  /// Type.h and Decl.h.
  inline bool IsEnumDeclScoped(EnumDecl *ED) {
    return ED->isScoped();
  }
  
  }  // end namespace clang
  
  #endif
  