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//===--- Sema.h - Semantic Analysis & AST Building --------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines the Sema class, which performs semantic analysis and
// builds ASTs.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_SEMA_SEMA_H
#define LLVM_CLANG_SEMA_SEMA_H

#include "clang/AST/ASTConcept.h"
#include "clang/AST/ASTFwd.h"
#include "clang/AST/Attr.h"
#include "clang/AST/Availability.h"
#include "clang/AST/ComparisonCategories.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/DeclarationName.h"
#include "clang/AST/Expr.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/ExprConcepts.h"
#include "clang/AST/ExprObjC.h"
#include "clang/AST/ExprOpenMP.h"
#include "clang/AST/ExternalASTSource.h"
#include "clang/AST/LocInfoType.h"
#include "clang/AST/MangleNumberingContext.h"
#include "clang/AST/NSAPI.h"
#include "clang/AST/PrettyPrinter.h"
#include "clang/AST/StmtCXX.h"
#include "clang/AST/TypeLoc.h"
#include "clang/AST/TypeOrdering.h"
#include "clang/Basic/BitmaskEnum.h"
#include "clang/Basic/ExpressionTraits.h"
#include "clang/Basic/Module.h"
#include "clang/Basic/OpenCLOptions.h"
#include "clang/Basic/OpenMPKinds.h"
#include "clang/Basic/PragmaKinds.h"
#include "clang/Basic/Specifiers.h"
#include "clang/Basic/TemplateKinds.h"
#include "clang/Basic/TypeTraits.h"
#include "clang/Sema/AnalysisBasedWarnings.h"
#include "clang/Sema/CleanupInfo.h"
#include "clang/Sema/DeclSpec.h"
#include "clang/Sema/ExternalSemaSource.h"
#include "clang/Sema/IdentifierResolver.h"
#include "clang/Sema/ObjCMethodList.h"
#include "clang/Sema/Ownership.h"
#include "clang/Sema/Scope.h"
#include "clang/Sema/SemaConcept.h"
#include "clang/Sema/TypoCorrection.h"
#include "clang/Sema/Weak.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallBitVector.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/TinyPtrVector.h"
#include "llvm/Frontend/OpenMP/OMPConstants.h"
#include <deque>
#include <memory>
#include <string>
#include <tuple>
#include <vector>

namespace llvm {
  class APSInt;
  template <typename ValueT> struct DenseMapInfo;
  template <typename ValueT, typename ValueInfoT> class DenseSet;
  class SmallBitVector;
  struct InlineAsmIdentifierInfo;
}

namespace clang {
  class ADLResult;
  class ASTConsumer;
  class ASTContext;
  class ASTMutationListener;
  class ASTReader;
  class ASTWriter;
  class ArrayType;
  class ParsedAttr;
  class BindingDecl;
  class BlockDecl;
  class CapturedDecl;
  class CXXBasePath;
  class CXXBasePaths;
  class CXXBindTemporaryExpr;
  typedef SmallVector<CXXBaseSpecifier*, 4> CXXCastPath;
  class CXXConstructorDecl;
  class CXXConversionDecl;
  class CXXDeleteExpr;
  class CXXDestructorDecl;
  class CXXFieldCollector;
  class CXXMemberCallExpr;
  class CXXMethodDecl;
  class CXXScopeSpec;
  class CXXTemporary;
  class CXXTryStmt;
  class CallExpr;
  class ClassTemplateDecl;
  class ClassTemplatePartialSpecializationDecl;
  class ClassTemplateSpecializationDecl;
  class VarTemplatePartialSpecializationDecl;
  class CodeCompleteConsumer;
  class CodeCompletionAllocator;
  class CodeCompletionTUInfo;
  class CodeCompletionResult;
  class CoroutineBodyStmt;
  class Decl;
  class DeclAccessPair;
  class DeclContext;
  class DeclRefExpr;
  class DeclaratorDecl;
  class DeducedTemplateArgument;
  class DependentDiagnostic;
  class DesignatedInitExpr;
  class Designation;
  class EnableIfAttr;
  class EnumConstantDecl;
  class Expr;
  class ExtVectorType;
  class FormatAttr;
  class FriendDecl;
  class FunctionDecl;
  class FunctionProtoType;
  class FunctionTemplateDecl;
  class ImplicitConversionSequence;
  typedef MutableArrayRef<ImplicitConversionSequence> ConversionSequenceList;
  class InitListExpr;
  class InitializationKind;
  class InitializationSequence;
  class InitializedEntity;
  class IntegerLiteral;
  class LabelStmt;
  class LambdaExpr;
  class LangOptions;
  class LocalInstantiationScope;
  class LookupResult;
  class MacroInfo;
  typedef ArrayRef<std::pair<IdentifierInfo *, SourceLocation>> ModuleIdPath;
  class ModuleLoader;
  class MultiLevelTemplateArgumentList;
  class NamedDecl;
  class ObjCCategoryDecl;
  class ObjCCategoryImplDecl;
  class ObjCCompatibleAliasDecl;
  class ObjCContainerDecl;
  class ObjCImplDecl;
  class ObjCImplementationDecl;
  class ObjCInterfaceDecl;
  class ObjCIvarDecl;
  template <class T> class ObjCList;
  class ObjCMessageExpr;
  class ObjCMethodDecl;
  class ObjCPropertyDecl;
  class ObjCProtocolDecl;
  class OMPThreadPrivateDecl;
  class OMPRequiresDecl;
  class OMPDeclareReductionDecl;
  class OMPDeclareSimdDecl;
  class OMPClause;
  struct OMPVarListLocTy;
  struct OverloadCandidate;
  enum class OverloadCandidateParamOrder : char;
  enum OverloadCandidateRewriteKind : unsigned;
  class OverloadCandidateSet;
  class OverloadExpr;
  class ParenListExpr;
  class ParmVarDecl;
  class Preprocessor;
  class PseudoDestructorTypeStorage;
  class PseudoObjectExpr;
  class QualType;
  class StandardConversionSequence;
  class Stmt;
  class StringLiteral;
  class SwitchStmt;
  class TemplateArgument;
  class TemplateArgumentList;
  class TemplateArgumentLoc;
  class TemplateDecl;
  class TemplateInstantiationCallback;
  class TemplateParameterList;
  class TemplatePartialOrderingContext;
  class TemplateTemplateParmDecl;
  class Token;
  class TypeAliasDecl;
  class TypedefDecl;
  class TypedefNameDecl;
  class TypeLoc;
  class TypoCorrectionConsumer;
  class UnqualifiedId;
  class UnresolvedLookupExpr;
  class UnresolvedMemberExpr;
  class UnresolvedSetImpl;
  class UnresolvedSetIterator;
  class UsingDecl;
  class UsingShadowDecl;
  class ValueDecl;
  class VarDecl;
  class VarTemplateSpecializationDecl;
  class VisibilityAttr;
  class VisibleDeclConsumer;
  class IndirectFieldDecl;
  struct DeductionFailureInfo;
  class TemplateSpecCandidateSet;

namespace sema {
  class AccessedEntity;
  class BlockScopeInfo;
  class Capture;
  class CapturedRegionScopeInfo;
  class CapturingScopeInfo;
  class CompoundScopeInfo;
  class DelayedDiagnostic;
  class DelayedDiagnosticPool;
  class FunctionScopeInfo;
  class LambdaScopeInfo;
  class PossiblyUnreachableDiag;
  class SemaPPCallbacks;
  class TemplateDeductionInfo;
}

namespace threadSafety {
  class BeforeSet;
  void threadSafetyCleanup(BeforeSet* Cache);
}

// FIXME: No way to easily map from TemplateTypeParmTypes to
// TemplateTypeParmDecls, so we have this horrible PointerUnion.
typedef std::pair<llvm::PointerUnion<const TemplateTypeParmType*, NamedDecl*>,
                  SourceLocation> UnexpandedParameterPack;

/// Describes whether we've seen any nullability information for the given
/// file.
struct FileNullability {
  /// The first pointer declarator (of any pointer kind) in the file that does
  /// not have a corresponding nullability annotation.
  SourceLocation PointerLoc;

  /// The end location for the first pointer declarator in the file. Used for
  /// placing fix-its.
  SourceLocation PointerEndLoc;

  /// Which kind of pointer declarator we saw.
  uint8_t PointerKind;

  /// Whether we saw any type nullability annotations in the given file.
  bool SawTypeNullability = false;
};

/// A mapping from file IDs to a record of whether we've seen nullability
/// information in that file.
class FileNullabilityMap {
  /// A mapping from file IDs to the nullability information for each file ID.
  llvm::DenseMap<FileID, FileNullability> Map;

  /// A single-element cache based on the file ID.
  struct {
    FileID File;
    FileNullability Nullability;
  } Cache;

public:
  FileNullability &operator[](FileID file) {
    // Check the single-element cache.
    if (file == Cache.File)
      return Cache.Nullability;

    // It's not in the single-element cache; flush the cache if we have one.
    if (!Cache.File.isInvalid()) {
      Map[Cache.File] = Cache.Nullability;
    }

    // Pull this entry into the cache.
    Cache.File = file;
    Cache.Nullability = Map[file];
    return Cache.Nullability;
  }
};

/// Keeps track of expected type during expression parsing. The type is tied to
/// a particular token, all functions that update or consume the type take a
/// start location of the token they are looking at as a parameter. This allows
/// to avoid updating the type on hot paths in the parser.
class PreferredTypeBuilder {
public:
  PreferredTypeBuilder() = default;
  explicit PreferredTypeBuilder(QualType Type) : Type(Type) {}

  void enterCondition(Sema &S, SourceLocation Tok);
  void enterReturn(Sema &S, SourceLocation Tok);
  void enterVariableInit(SourceLocation Tok, Decl *D);
  /// Computing a type for the function argument may require running
  /// overloading, so we postpone its computation until it is actually needed.
  ///
  /// Clients should be very careful when using this funciton, as it stores a
  /// function_ref, clients should make sure all calls to get() with the same
  /// location happen while function_ref is alive.
  void enterFunctionArgument(SourceLocation Tok,
                             llvm::function_ref<QualType()> ComputeType);

  void enterParenExpr(SourceLocation Tok, SourceLocation LParLoc);
  void enterUnary(Sema &S, SourceLocation Tok, tok::TokenKind OpKind,
                  SourceLocation OpLoc);
  void enterBinary(Sema &S, SourceLocation Tok, Expr *LHS, tok::TokenKind Op);
  void enterMemAccess(Sema &S, SourceLocation Tok, Expr *Base);
  void enterSubscript(Sema &S, SourceLocation Tok, Expr *LHS);
  /// Handles all type casts, including C-style cast, C++ casts, etc.
  void enterTypeCast(SourceLocation Tok, QualType CastType);

  QualType get(SourceLocation Tok) const {
    if (Tok != ExpectedLoc)
      return QualType();
    if (!Type.isNull())
      return Type;
    if (ComputeType)
      return ComputeType();
    return QualType();
  }

private:
  /// Start position of a token for which we store expected type.
  SourceLocation ExpectedLoc;
  /// Expected type for a token starting at ExpectedLoc.
  QualType Type;
  /// A function to compute expected type at ExpectedLoc. It is only considered
  /// if Type is null.
  llvm::function_ref<QualType()> ComputeType;
};

/// Sema - This implements semantic analysis and AST building for C.
class Sema final {
  Sema(const Sema &) = delete;
  void operator=(const Sema &) = delete;

  /// A key method to reduce duplicate debug info from Sema.
  virtual void anchor();

  ///Source of additional semantic information.
  ExternalSemaSource *ExternalSource;

  ///Whether Sema has generated a multiplexer and has to delete it.
  bool isMultiplexExternalSource;

  static bool mightHaveNonExternalLinkage(const DeclaratorDecl *FD);

  bool isVisibleSlow(const NamedDecl *D);

  /// Determine whether two declarations should be linked together, given that
  /// the old declaration might not be visible and the new declaration might
  /// not have external linkage.
  bool shouldLinkPossiblyHiddenDecl(const NamedDecl *Old,
                                    const NamedDecl *New) {
    if (isVisible(Old))
     return true;
    // See comment in below overload for why it's safe to compute the linkage
    // of the new declaration here.
    if (New->isExternallyDeclarable()) {
      assert(Old->isExternallyDeclarable() &&
             "should not have found a non-externally-declarable previous decl");
      return true;
    }
    return false;
  }
  bool shouldLinkPossiblyHiddenDecl(LookupResult &Old, const NamedDecl *New);

  void setupImplicitSpecialMemberType(CXXMethodDecl *SpecialMem,
                                      QualType ResultTy,
                                      ArrayRef<QualType> Args);

public:
  /// The maximum alignment, same as in llvm::Value. We duplicate them here
  /// because that allows us not to duplicate the constants in clang code,
  /// which we must to since we can't directly use the llvm constants.
  /// The value is verified against llvm here: lib/CodeGen/CGDecl.cpp
  ///
  /// This is the greatest alignment value supported by load, store, and alloca
  /// instructions, and global values.
  static const unsigned MaxAlignmentExponent = 29;
  static const unsigned MaximumAlignment = 1u << MaxAlignmentExponent;

  typedef OpaquePtr<DeclGroupRef> DeclGroupPtrTy;
  typedef OpaquePtr<TemplateName> TemplateTy;
  typedef OpaquePtr<QualType> TypeTy;

  OpenCLOptions OpenCLFeatures;
  FPOptions CurFPFeatures;

  const LangOptions &LangOpts;
  Preprocessor &PP;
  ASTContext &Context;
  ASTConsumer &Consumer;
  DiagnosticsEngine &Diags;
  SourceManager &SourceMgr;

  /// Flag indicating whether or not to collect detailed statistics.
  bool CollectStats;

  /// Code-completion consumer.
  CodeCompleteConsumer *CodeCompleter;

  /// CurContext - This is the current declaration context of parsing.
  DeclContext *CurContext;

  /// Generally null except when we temporarily switch decl contexts,
  /// like in \see ActOnObjCTemporaryExitContainerContext.
  DeclContext *OriginalLexicalContext;

  /// VAListTagName - The declaration name corresponding to __va_list_tag.
  /// This is used as part of a hack to omit that class from ADL results.
  DeclarationName VAListTagName;

  bool MSStructPragmaOn; // True when \#pragma ms_struct on

  /// Controls member pointer representation format under the MS ABI.
  LangOptions::PragmaMSPointersToMembersKind
      MSPointerToMemberRepresentationMethod;

  /// Stack of active SEH __finally scopes.  Can be empty.
  SmallVector<Scope*, 2> CurrentSEHFinally;

  /// Source location for newly created implicit MSInheritanceAttrs
  SourceLocation ImplicitMSInheritanceAttrLoc;

  /// Holds TypoExprs that are created from `createDelayedTypo`. This is used by
  /// `TransformTypos` in order to keep track of any TypoExprs that are created
  /// recursively during typo correction and wipe them away if the correction
  /// fails.
  llvm::SmallVector<TypoExpr *, 2> TypoExprs;

  /// pragma clang section kind
  enum PragmaClangSectionKind {
    PCSK_Invalid      = 0,
    PCSK_BSS          = 1,
    PCSK_Data         = 2,
    PCSK_Rodata       = 3,
    PCSK_Text         = 4,
    PCSK_Relro        = 5
   };

  enum PragmaClangSectionAction {
    PCSA_Set     = 0,
    PCSA_Clear   = 1
  };

  struct PragmaClangSection {
    std::string SectionName;
    bool Valid = false;
    SourceLocation PragmaLocation;

    void Act(SourceLocation PragmaLocation,
             PragmaClangSectionAction Action,
             StringLiteral* Name);
   };

   PragmaClangSection PragmaClangBSSSection;
   PragmaClangSection PragmaClangDataSection;
   PragmaClangSection PragmaClangRodataSection;
   PragmaClangSection PragmaClangRelroSection;
   PragmaClangSection PragmaClangTextSection;

  enum PragmaMsStackAction {
    PSK_Reset     = 0x0,                // #pragma ()
    PSK_Set       = 0x1,                // #pragma (value)
    PSK_Push      = 0x2,                // #pragma (push[, id])
    PSK_Pop       = 0x4,                // #pragma (pop[, id])
    PSK_Show      = 0x8,                // #pragma (show) -- only for "pack"!
    PSK_Push_Set  = PSK_Push | PSK_Set, // #pragma (push[, id], value)
    PSK_Pop_Set   = PSK_Pop | PSK_Set,  // #pragma (pop[, id], value)
  };

  template<typename ValueType>
  struct PragmaStack {
    struct Slot {
      llvm::StringRef StackSlotLabel;
      ValueType Value;
      SourceLocation PragmaLocation;
      SourceLocation PragmaPushLocation;
      Slot(llvm::StringRef StackSlotLabel, ValueType Value,
           SourceLocation PragmaLocation, SourceLocation PragmaPushLocation)
          : StackSlotLabel(StackSlotLabel), Value(Value),
            PragmaLocation(PragmaLocation),
            PragmaPushLocation(PragmaPushLocation) {}
    };

    void Act(SourceLocation PragmaLocation, PragmaMsStackAction Action,
             llvm::StringRef StackSlotLabel, ValueType Value) {
      if (Action == PSK_Reset) {
        CurrentValue = DefaultValue;
        CurrentPragmaLocation = PragmaLocation;
        return;
      }
      if (Action & PSK_Push)
        Stack.emplace_back(StackSlotLabel, CurrentValue, CurrentPragmaLocation,
                           PragmaLocation);
      else if (Action & PSK_Pop) {
        if (!StackSlotLabel.empty()) {
          // If we've got a label, try to find it and jump there.
          auto I = llvm::find_if(llvm::reverse(Stack), [&](const Slot &x) {
            return x.StackSlotLabel == StackSlotLabel;
          });
          // If we found the label so pop from there.
          if (I != Stack.rend()) {
            CurrentValue = I->Value;
            CurrentPragmaLocation = I->PragmaLocation;
            Stack.erase(std::prev(I.base()), Stack.end());
          }
        } else if (!Stack.empty()) {
          // We do not have a label, just pop the last entry.
          CurrentValue = Stack.back().Value;
          CurrentPragmaLocation = Stack.back().PragmaLocation;
          Stack.pop_back();
        }
      }
      if (Action & PSK_Set) {
        CurrentValue = Value;
        CurrentPragmaLocation = PragmaLocation;
      }
    }

    // MSVC seems to add artificial slots to #pragma stacks on entering a C++
    // method body to restore the stacks on exit, so it works like this:
    //
    //   struct S {
    //     #pragma <name>(push, InternalPragmaSlot, <current_pragma_value>)
    //     void Method {}
    //     #pragma <name>(pop, InternalPragmaSlot)
    //   };
    //
    // It works even with #pragma vtordisp, although MSVC doesn't support
    //   #pragma vtordisp(push [, id], n)
    // syntax.
    //
    // Push / pop a named sentinel slot.
    void SentinelAction(PragmaMsStackAction Action, StringRef Label) {
      assert((Action == PSK_Push || Action == PSK_Pop) &&
             "Can only push / pop #pragma stack sentinels!");
      Act(CurrentPragmaLocation, Action, Label, CurrentValue);
    }

    // Constructors.
    explicit PragmaStack(const ValueType &Default)
        : DefaultValue(Default), CurrentValue(Default) {}

    bool hasValue() const { return CurrentValue != DefaultValue; }

    SmallVector<Slot, 2> Stack;
    ValueType DefaultValue; // Value used for PSK_Reset action.
    ValueType CurrentValue;
    SourceLocation CurrentPragmaLocation;
  };
  // FIXME: We should serialize / deserialize these if they occur in a PCH (but
  // we shouldn't do so if they're in a module).

  /// Whether to insert vtordisps prior to virtual bases in the Microsoft
  /// C++ ABI.  Possible values are 0, 1, and 2, which mean:
  ///
  /// 0: Suppress all vtordisps
  /// 1: Insert vtordisps in the presence of vbase overrides and non-trivial
  ///    structors
  /// 2: Always insert vtordisps to support RTTI on partially constructed
  ///    objects
  PragmaStack<MSVtorDispMode> VtorDispStack;
  // #pragma pack.
  // Sentinel to represent when the stack is set to mac68k alignment.
  static const unsigned kMac68kAlignmentSentinel = ~0U;
  PragmaStack<unsigned> PackStack;
  // The current #pragma pack values and locations at each #include.
  struct PackIncludeState {
    unsigned CurrentValue;
    SourceLocation CurrentPragmaLocation;
    bool HasNonDefaultValue, ShouldWarnOnInclude;
  };
  SmallVector<PackIncludeState, 8> PackIncludeStack;
  // Segment #pragmas.
  PragmaStack<StringLiteral *> DataSegStack;
  PragmaStack<StringLiteral *> BSSSegStack;
  PragmaStack<StringLiteral *> ConstSegStack;
  PragmaStack<StringLiteral *> CodeSegStack;

  // This stack tracks the current state of Sema.CurFPFeatures.
  PragmaStack<FPOptionsOverride> FpPragmaStack;
  FPOptionsOverride CurFPFeatureOverrides() {
    FPOptionsOverride result;
    if (!FpPragmaStack.hasValue()) {
      result = FPOptionsOverride();
    } else {
      result = FpPragmaStack.CurrentValue;
    }
    return result;
  }

  // RAII object to push / pop sentinel slots for all MS #pragma stacks.
  // Actions should be performed only if we enter / exit a C++ method body.
  class PragmaStackSentinelRAII {
  public:
    PragmaStackSentinelRAII(Sema &S, StringRef SlotLabel, bool ShouldAct);
    ~PragmaStackSentinelRAII();

  private:
    Sema &S;
    StringRef SlotLabel;
    bool ShouldAct;
  };

  /// A mapping that describes the nullability we've seen in each header file.
  FileNullabilityMap NullabilityMap;

  /// Last section used with #pragma init_seg.
  StringLiteral *CurInitSeg;
  SourceLocation CurInitSegLoc;

  /// VisContext - Manages the stack for \#pragma GCC visibility.
  void *VisContext; // Really a "PragmaVisStack*"

  /// This an attribute introduced by \#pragma clang attribute.
  struct PragmaAttributeEntry {
    SourceLocation Loc;
    ParsedAttr *Attribute;
    SmallVector<attr::SubjectMatchRule, 4> MatchRules;
    bool IsUsed;
  };

  /// A push'd group of PragmaAttributeEntries.
  struct PragmaAttributeGroup {
    /// The location of the push attribute.
    SourceLocation Loc;
    /// The namespace of this push group.
    const IdentifierInfo *Namespace;
    SmallVector<PragmaAttributeEntry, 2> Entries;
  };

  SmallVector<PragmaAttributeGroup, 2> PragmaAttributeStack;

  /// The declaration that is currently receiving an attribute from the
  /// #pragma attribute stack.
  const Decl *PragmaAttributeCurrentTargetDecl;

  /// This represents the last location of a "#pragma clang optimize off"
  /// directive if such a directive has not been closed by an "on" yet. If
  /// optimizations are currently "on", this is set to an invalid location.
  SourceLocation OptimizeOffPragmaLocation;

  /// Flag indicating if Sema is building a recovery call expression.
  ///
  /// This flag is used to avoid building recovery call expressions
  /// if Sema is already doing so, which would cause infinite recursions.
  bool IsBuildingRecoveryCallExpr;

  /// Used to control the generation of ExprWithCleanups.
  CleanupInfo Cleanup;

  /// ExprCleanupObjects - This is the stack of objects requiring
  /// cleanup that are created by the current full expression.
  SmallVector<ExprWithCleanups::CleanupObject, 8> ExprCleanupObjects;

  /// Store a set of either DeclRefExprs or MemberExprs that contain a reference
  /// to a variable (constant) that may or may not be odr-used in this Expr, and
  /// we won't know until all lvalue-to-rvalue and discarded value conversions
  /// have been applied to all subexpressions of the enclosing full expression.
  /// This is cleared at the end of each full expression.
  using MaybeODRUseExprSet = llvm::SetVector<Expr *, SmallVector<Expr *, 4>,
                                             llvm::SmallPtrSet<Expr *, 4>>;
  MaybeODRUseExprSet MaybeODRUseExprs;

  std::unique_ptr<sema::FunctionScopeInfo> CachedFunctionScope;

  /// Stack containing information about each of the nested
  /// function, block, and method scopes that are currently active.
  SmallVector<sema::FunctionScopeInfo *, 4> FunctionScopes;

  /// The index of the first FunctionScope that corresponds to the current
  /// context.
  unsigned FunctionScopesStart = 0;

  ArrayRef<sema::FunctionScopeInfo*> getFunctionScopes() const {
    return llvm::makeArrayRef(FunctionScopes.begin() + FunctionScopesStart,
                              FunctionScopes.end());
  }

  /// Stack containing information needed when in C++2a an 'auto' is encountered
  /// in a function declaration parameter type specifier in order to invent a
  /// corresponding template parameter in the enclosing abbreviated function
  /// template. This information is also present in LambdaScopeInfo, stored in
  /// the FunctionScopes stack.
  SmallVector<InventedTemplateParameterInfo, 4> InventedParameterInfos;

  /// The index of the first InventedParameterInfo that refers to the current
  /// context.
  unsigned InventedParameterInfosStart = 0;

  ArrayRef<InventedTemplateParameterInfo> getInventedParameterInfos() const {
    return llvm::makeArrayRef(InventedParameterInfos.begin() +
                                  InventedParameterInfosStart,
                              InventedParameterInfos.end());
  }

  typedef LazyVector<TypedefNameDecl *, ExternalSemaSource,
                     &ExternalSemaSource::ReadExtVectorDecls, 2, 2>
    ExtVectorDeclsType;

  /// ExtVectorDecls - This is a list all the extended vector types. This allows
  /// us to associate a raw vector type with one of the ext_vector type names.
  /// This is only necessary for issuing pretty diagnostics.
  ExtVectorDeclsType ExtVectorDecls;

  /// FieldCollector - Collects CXXFieldDecls during parsing of C++ classes.
  std::unique_ptr<CXXFieldCollector> FieldCollector;

  typedef llvm::SmallSetVector<NamedDecl *, 16> NamedDeclSetType;

  /// Set containing all declared private fields that are not used.
  NamedDeclSetType UnusedPrivateFields;

  /// Set containing all typedefs that are likely unused.
  llvm::SmallSetVector<const TypedefNameDecl *, 4>
      UnusedLocalTypedefNameCandidates;

  /// Delete-expressions to be analyzed at the end of translation unit
  ///
  /// This list contains class members, and locations of delete-expressions
  /// that could not be proven as to whether they mismatch with new-expression
  /// used in initializer of the field.
  typedef std::pair<SourceLocation, bool> DeleteExprLoc;
  typedef llvm::SmallVector<DeleteExprLoc, 4> DeleteLocs;
  llvm::MapVector<FieldDecl *, DeleteLocs> DeleteExprs;

  typedef llvm::SmallPtrSet<const CXXRecordDecl*, 8> RecordDeclSetTy;

  /// PureVirtualClassDiagSet - a set of class declarations which we have
  /// emitted a list of pure virtual functions. Used to prevent emitting the
  /// same list more than once.
  std::unique_ptr<RecordDeclSetTy> PureVirtualClassDiagSet;

  /// ParsingInitForAutoVars - a set of declarations with auto types for which
  /// we are currently parsing the initializer.
  llvm::SmallPtrSet<const Decl*, 4> ParsingInitForAutoVars;

  /// Look for a locally scoped extern "C" declaration by the given name.
  NamedDecl *findLocallyScopedExternCDecl(DeclarationName Name);

  typedef LazyVector<VarDecl *, ExternalSemaSource,
                     &ExternalSemaSource::ReadTentativeDefinitions, 2, 2>
    TentativeDefinitionsType;

  /// All the tentative definitions encountered in the TU.
  TentativeDefinitionsType TentativeDefinitions;

  /// All the external declarations encoutered and used in the TU.
  SmallVector<VarDecl *, 4> ExternalDeclarations;

  typedef LazyVector<const DeclaratorDecl *, ExternalSemaSource,
                     &ExternalSemaSource::ReadUnusedFileScopedDecls, 2, 2>
    UnusedFileScopedDeclsType;

  /// The set of file scoped decls seen so far that have not been used
  /// and must warn if not used. Only contains the first declaration.
  UnusedFileScopedDeclsType UnusedFileScopedDecls;

  typedef LazyVector<CXXConstructorDecl *, ExternalSemaSource,
                     &ExternalSemaSource::ReadDelegatingConstructors, 2, 2>
    DelegatingCtorDeclsType;

  /// All the delegating constructors seen so far in the file, used for
  /// cycle detection at the end of the TU.
  DelegatingCtorDeclsType DelegatingCtorDecls;

  /// All the overriding functions seen during a class definition
  /// that had their exception spec checks delayed, plus the overridden
  /// function.
  SmallVector<std::pair<const CXXMethodDecl*, const CXXMethodDecl*>, 2>
    DelayedOverridingExceptionSpecChecks;

  /// All the function redeclarations seen during a class definition that had
  /// their exception spec checks delayed, plus the prior declaration they
  /// should be checked against. Except during error recovery, the new decl
  /// should always be a friend declaration, as that's the only valid way to
  /// redeclare a special member before its class is complete.
  SmallVector<std::pair<FunctionDecl*, FunctionDecl*>, 2>
    DelayedEquivalentExceptionSpecChecks;

  typedef llvm::MapVector<const FunctionDecl *,
                          std::unique_ptr<LateParsedTemplate>>
      LateParsedTemplateMapT;
  LateParsedTemplateMapT LateParsedTemplateMap;

  /// Callback to the parser to parse templated functions when needed.
  typedef void LateTemplateParserCB(void *P, LateParsedTemplate &LPT);
  typedef void LateTemplateParserCleanupCB(void *P);
  LateTemplateParserCB *LateTemplateParser;
  LateTemplateParserCleanupCB *LateTemplateParserCleanup;
  void *OpaqueParser;

  void SetLateTemplateParser(LateTemplateParserCB *LTP,
                             LateTemplateParserCleanupCB *LTPCleanup,
                             void *P) {
    LateTemplateParser = LTP;
    LateTemplateParserCleanup = LTPCleanup;
    OpaqueParser = P;
  }

  class DelayedDiagnostics;

  class DelayedDiagnosticsState {
    sema::DelayedDiagnosticPool *SavedPool;
    friend class Sema::DelayedDiagnostics;
  };
  typedef DelayedDiagnosticsState ParsingDeclState;
  typedef DelayedDiagnosticsState ProcessingContextState;

  /// A class which encapsulates the logic for delaying diagnostics
  /// during parsing and other processing.
  class DelayedDiagnostics {
    /// The current pool of diagnostics into which delayed
    /// diagnostics should go.
    sema::DelayedDiagnosticPool *CurPool;

  public:
    DelayedDiagnostics() : CurPool(nullptr) {}

    /// Adds a delayed diagnostic.
    void add(const sema::DelayedDiagnostic &diag); // in DelayedDiagnostic.h

    /// Determines whether diagnostics should be delayed.
    bool shouldDelayDiagnostics() { return CurPool != nullptr; }

    /// Returns the current delayed-diagnostics pool.
    sema::DelayedDiagnosticPool *getCurrentPool() const {
      return CurPool;
    }

    /// Enter a new scope.  Access and deprecation diagnostics will be
    /// collected in this pool.
    DelayedDiagnosticsState push(sema::DelayedDiagnosticPool &pool) {
      DelayedDiagnosticsState state;
      state.SavedPool = CurPool;
      CurPool = &pool;
      return state;
    }

    /// Leave a delayed-diagnostic state that was previously pushed.
    /// Do not emit any of the diagnostics.  This is performed as part
    /// of the bookkeeping of popping a pool "properly".
    void popWithoutEmitting(DelayedDiagnosticsState state) {
      CurPool = state.SavedPool;
    }

    /// Enter a new scope where access and deprecation diagnostics are
    /// not delayed.
    DelayedDiagnosticsState pushUndelayed() {
      DelayedDiagnosticsState state;
      state.SavedPool = CurPool;
      CurPool = nullptr;
      return state;
    }

    /// Undo a previous pushUndelayed().
    void popUndelayed(DelayedDiagnosticsState state) {
      assert(CurPool == nullptr);
      CurPool = state.SavedPool;
    }
  } DelayedDiagnostics;

  /// A RAII object to temporarily push a declaration context.
  class ContextRAII {
  private:
    Sema &S;
    DeclContext *SavedContext;
    ProcessingContextState SavedContextState;
    QualType SavedCXXThisTypeOverride;
    unsigned SavedFunctionScopesStart;
    unsigned SavedInventedParameterInfosStart;

  public:
    ContextRAII(Sema &S, DeclContext *ContextToPush, bool NewThisContext = true)
      : S(S), SavedContext(S.CurContext),
        SavedContextState(S.DelayedDiagnostics.pushUndelayed()),
        SavedCXXThisTypeOverride(S.CXXThisTypeOverride),
        SavedFunctionScopesStart(S.FunctionScopesStart),
        SavedInventedParameterInfosStart(S.InventedParameterInfosStart)
    {
      assert(ContextToPush && "pushing null context");
      S.CurContext = ContextToPush;
      if (NewThisContext)
        S.CXXThisTypeOverride = QualType();
      // Any saved FunctionScopes do not refer to this context.
      S.FunctionScopesStart = S.FunctionScopes.size();
      S.InventedParameterInfosStart = S.InventedParameterInfos.size();
    }

    void pop() {
      if (!SavedContext) return903k;
      S.CurContext = SavedContext;
      S.DelayedDiagnostics.popUndelayed(SavedContextState);
      S.CXXThisTypeOverride = SavedCXXThisTypeOverride;
      S.FunctionScopesStart = SavedFunctionScopesStart;
      S.InventedParameterInfosStart = SavedInventedParameterInfosStart;
      SavedContext = nullptr;
    }

    ~ContextRAII() {
      pop();
    }
  };

  /// Whether the AST is currently being rebuilt to correct immediate
  /// invocations. Immediate invocation candidates and references to consteval
  /// functions aren't tracked when this is set.
  bool RebuildingImmediateInvocation = false;

  /// Used to change context to isConstantEvaluated without pushing a heavy
  /// ExpressionEvaluationContextRecord object.
  bool isConstantEvaluatedOverride;

  bool isConstantEvaluated() {
    return ExprEvalContexts.back().isConstantEvaluated() ||
           isConstantEvaluatedOverride;
  }

  /// RAII object to handle the state changes required to synthesize
  /// a function body.
  class SynthesizedFunctionScope {
    Sema &S;
    Sema::ContextRAII SavedContext;
    bool PushedCodeSynthesisContext = false;

  public:
    SynthesizedFunctionScope(Sema &S, DeclContext *DC)
        : S(S), SavedContext(S, DC) {
      S.PushFunctionScope();
      S.PushExpressionEvaluationContext(
          Sema::ExpressionEvaluationContext::PotentiallyEvaluated);
      if (auto *FD = dyn_cast<FunctionDecl>(DC))
        FD->setWillHaveBody(true);
      else
        assert(isa<ObjCMethodDecl>(DC));
    }

    void addContextNote(SourceLocation UseLoc) {
      assert(!PushedCodeSynthesisContext);

      Sema::CodeSynthesisContext Ctx;
      Ctx.Kind = Sema::CodeSynthesisContext::DefiningSynthesizedFunction;
      Ctx.PointOfInstantiation = UseLoc;
      Ctx.Entity = cast<Decl>(S.CurContext);
      S.pushCodeSynthesisContext(Ctx);

      PushedCodeSynthesisContext = true;
    }

    ~SynthesizedFunctionScope() {
      if (PushedCodeSynthesisContext)
        S.popCodeSynthesisContext();
      if (auto *FD = dyn_cast<FunctionDecl>(S.CurContext))
        FD->setWillHaveBody(false);
      S.PopExpressionEvaluationContext();
      S.PopFunctionScopeInfo();
    }
  };

  /// WeakUndeclaredIdentifiers - Identifiers contained in
  /// \#pragma weak before declared. rare. may alias another
  /// identifier, declared or undeclared
  llvm::MapVector<IdentifierInfo *, WeakInfo> WeakUndeclaredIdentifiers;

  /// ExtnameUndeclaredIdentifiers - Identifiers contained in
  /// \#pragma redefine_extname before declared.  Used in Solaris system headers
  /// to define functions that occur in multiple standards to call the version
  /// in the currently selected standard.
  llvm::DenseMap<IdentifierInfo*,AsmLabelAttr*> ExtnameUndeclaredIdentifiers;


  /// Load weak undeclared identifiers from the external source.
  void LoadExternalWeakUndeclaredIdentifiers();

  /// WeakTopLevelDecl - Translation-unit scoped declarations generated by
  /// \#pragma weak during processing of other Decls.
  /// I couldn't figure out a clean way to generate these in-line, so
  /// we store them here and handle separately -- which is a hack.
  /// It would be best to refactor this.
  SmallVector<Decl*,2> WeakTopLevelDecl;

  IdentifierResolver IdResolver;

  /// Translation Unit Scope - useful to Objective-C actions that need
  /// to lookup file scope declarations in the "ordinary" C decl namespace.
  /// For example, user-defined classes, built-in "id" type, etc.
  Scope *TUScope;

  /// The C++ "std" namespace, where the standard library resides.
  LazyDeclPtr StdNamespace;

  /// The C++ "std::bad_alloc" class, which is defined by the C++
  /// standard library.
  LazyDeclPtr StdBadAlloc;

  /// The C++ "std::align_val_t" enum class, which is defined by the C++
  /// standard library.
  LazyDeclPtr StdAlignValT;

  /// The C++ "std::experimental" namespace, where the experimental parts
  /// of the standard library resides.
  NamespaceDecl *StdExperimentalNamespaceCache;

  /// The C++ "std::initializer_list" template, which is defined in
  /// \<initializer_list>.
  ClassTemplateDecl *StdInitializerList;

  /// The C++ "std::coroutine_traits" template, which is defined in
  /// \<coroutine_traits>
  ClassTemplateDecl *StdCoroutineTraitsCache;

  /// The C++ "type_info" declaration, which is defined in \<typeinfo>.
  RecordDecl *CXXTypeInfoDecl;

  /// The MSVC "_GUID" struct, which is defined in MSVC header files.
  RecordDecl *MSVCGuidDecl;

  /// Caches identifiers/selectors for NSFoundation APIs.
  std::unique_ptr<NSAPI> NSAPIObj;

  /// The declaration of the Objective-C NSNumber class.
  ObjCInterfaceDecl *NSNumberDecl;

  /// The declaration of the Objective-C NSValue class.
  ObjCInterfaceDecl *NSValueDecl;

  /// Pointer to NSNumber type (NSNumber *).
  QualType NSNumberPointer;

  /// Pointer to NSValue type (NSValue *).
  QualType NSValuePointer;

  /// The Objective-C NSNumber methods used to create NSNumber literals.
  ObjCMethodDecl *NSNumberLiteralMethods[NSAPI::NumNSNumberLiteralMethods];

  /// The declaration of the Objective-C NSString class.
  ObjCInterfaceDecl *NSStringDecl;

  /// Pointer to NSString type (NSString *).
  QualType NSStringPointer;

  /// The declaration of the stringWithUTF8String: method.
  ObjCMethodDecl *StringWithUTF8StringMethod;

  /// The declaration of the valueWithBytes:objCType: method.
  ObjCMethodDecl *ValueWithBytesObjCTypeMethod;

  /// The declaration of the Objective-C NSArray class.
  ObjCInterfaceDecl *NSArrayDecl;

  /// The declaration of the arrayWithObjects:count: method.
  ObjCMethodDecl *ArrayWithObjectsMethod;

  /// The declaration of the Objective-C NSDictionary class.
  ObjCInterfaceDecl *NSDictionaryDecl;

  /// The declaration of the dictionaryWithObjects:forKeys:count: method.
  ObjCMethodDecl *DictionaryWithObjectsMethod;

  /// id<NSCopying> type.
  QualType QIDNSCopying;

  /// will hold 'respondsToSelector:'
  Selector RespondsToSelectorSel;

  /// A flag to remember whether the implicit forms of operator new and delete
  /// have been declared.
  bool GlobalNewDeleteDeclared;

  /// A flag to indicate that we're in a context that permits abstract
  /// references to fields.  This is really a
  bool AllowAbstractFieldReference;

  /// Describes how the expressions currently being parsed are
  /// evaluated at run-time, if at all.
  enum class ExpressionEvaluationContext {
    /// The current expression and its subexpressions occur within an
    /// unevaluated operand (C++11 [expr]p7), such as the subexpression of
    /// \c sizeof, where the type of the expression may be significant but
    /// no code will be generated to evaluate the value of the expression at
    /// run time.
    Unevaluated,

    /// The current expression occurs within a braced-init-list within
    /// an unevaluated operand. This is mostly like a regular unevaluated
    /// context, except that we still instantiate constexpr functions that are
    /// referenced here so that we can perform narrowing checks correctly.
    UnevaluatedList,

    /// The current expression occurs within a discarded statement.
    /// This behaves largely similarly to an unevaluated operand in preventing
    /// definitions from being required, but not in other ways.
    DiscardedStatement,

    /// The current expression occurs within an unevaluated
    /// operand that unconditionally permits abstract references to
    /// fields, such as a SIZE operator in MS-style inline assembly.
    UnevaluatedAbstract,

    /// The current context is "potentially evaluated" in C++11 terms,
    /// but the expression is evaluated at compile-time (like the values of
    /// cases in a switch statement).
    ConstantEvaluated,

    /// The current expression is potentially evaluated at run time,
    /// which means that code may be generated to evaluate the value of the
    /// expression at run time.
    PotentiallyEvaluated,

    /// The current expression is potentially evaluated, but any
    /// declarations referenced inside that expression are only used if
    /// in fact the current expression is used.
    ///
    /// This value is used when parsing default function arguments, for which
    /// we would like to provide diagnostics (e.g., passing non-POD arguments
    /// through varargs) but do not want to mark declarations as "referenced"
    /// until the default argument is used.
    PotentiallyEvaluatedIfUsed
  };

  using ImmediateInvocationCandidate = llvm::PointerIntPair<ConstantExpr *, 1>;

  /// Data structure used to record current or nested
  /// expression evaluation contexts.
  struct ExpressionEvaluationContextRecord {
    /// The expression evaluation context.
    ExpressionEvaluationContext Context;

    /// Whether the enclosing context needed a cleanup.
    CleanupInfo ParentCleanup;

    /// Whether we are in a decltype expression.
    bool IsDecltype;

    /// The number of active cleanup objects when we entered
    /// this expression evaluation context.
    unsigned NumCleanupObjects;

    /// The number of typos encountered during this expression evaluation
    /// context (i.e. the number of TypoExprs created).
    unsigned NumTypos;

    MaybeODRUseExprSet SavedMaybeODRUseExprs;

    /// The lambdas that are present within this context, if it
    /// is indeed an unevaluated context.
    SmallVector<LambdaExpr *, 2> Lambdas;

    /// The declaration that provides context for lambda expressions
    /// and block literals if the normal declaration context does not
    /// suffice, e.g., in a default function argument.
    Decl *ManglingContextDecl;

    /// If we are processing a decltype type, a set of call expressions
    /// for which we have deferred checking the completeness of the return type.
    SmallVector<CallExpr *, 8> DelayedDecltypeCalls;

    /// If we are processing a decltype type, a set of temporary binding
    /// expressions for which we have deferred checking the destructor.
    SmallVector<CXXBindTemporaryExpr *, 8> DelayedDecltypeBinds;

    llvm::SmallPtrSet<const Expr *, 8> PossibleDerefs;

    /// Expressions appearing as the LHS of a volatile assignment in this
    /// context. We produce a warning for these when popping the context if
    /// they are not discarded-value expressions nor unevaluated operands.
    SmallVector<Expr*, 2> VolatileAssignmentLHSs;

    /// Set of candidates for starting an immediate invocation.
    llvm::SmallVector<ImmediateInvocationCandidate, 4> ImmediateInvocationCandidates;

    /// Set of DeclRefExprs referencing a consteval function when used in a
    /// context not already known to be immediately invoked.
    llvm::SmallPtrSet<DeclRefExpr *, 4> ReferenceToConsteval;

    /// \brief Describes whether we are in an expression constext which we have
    /// to handle differently.
    enum ExpressionKind {
      EK_Decltype, EK_TemplateArgument, EK_Other
    } ExprContext;

    ExpressionEvaluationContextRecord(ExpressionEvaluationContext Context,
                                      unsigned NumCleanupObjects,
                                      CleanupInfo ParentCleanup,
                                      Decl *ManglingContextDecl,
                                      ExpressionKind ExprContext)
        : Context(Context), ParentCleanup(ParentCleanup),
          NumCleanupObjects(NumCleanupObjects), NumTypos(0),
          ManglingContextDecl(ManglingContextDecl), ExprContext(ExprContext) {}

    bool isUnevaluated() const {
      return Context == ExpressionEvaluationContext::Unevaluated ||
             Context == ExpressionEvaluationContext::UnevaluatedAbstract ||
             Context == ExpressionEvaluationContext::UnevaluatedList;
    }
    bool isConstantEvaluated() const {
      return Context == ExpressionEvaluationContext::ConstantEvaluated;
    }
  };

  /// A stack of expression evaluation contexts.
  SmallVector<ExpressionEvaluationContextRecord, 8> ExprEvalContexts;

  /// Emit a warning for all pending noderef expressions that we recorded.
  void WarnOnPendingNoDerefs(ExpressionEvaluationContextRecord &Rec);

  /// Compute the mangling number context for a lambda expression or
  /// block literal. Also return the extra mangling decl if any.
  ///
  /// \param DC - The DeclContext containing the lambda expression or
  /// block literal.
  std::tuple<MangleNumberingContext *, Decl *>
  getCurrentMangleNumberContext(const DeclContext *DC);


  /// SpecialMemberOverloadResult - The overloading result for a special member
  /// function.
  ///
  /// This is basically a wrapper around PointerIntPair. The lowest bits of the
  /// integer are used to determine whether overload resolution succeeded.
  class SpecialMemberOverloadResult {
  public:
    enum Kind {
      NoMemberOrDeleted,
      Ambiguous,
      Success
    };

  private:
    llvm::PointerIntPair<CXXMethodDecl*, 2> Pair;

  public:
    SpecialMemberOverloadResult() : Pair() {}
    SpecialMemberOverloadResult(CXXMethodDecl *MD)
        : Pair(MD, MD->isDeleted() ? NoMemberOrDeleted : Success) {}

    CXXMethodDecl *getMethod() const { return Pair.getPointer(); }
    void setMethod(CXXMethodDecl *MD) { Pair.setPointer(MD); }

    Kind getKind() const { return static_cast<Kind>(Pair.getInt()); }
    void setKind(Kind K) { Pair.setInt(K); }
  };

  class SpecialMemberOverloadResultEntry
      : public llvm::FastFoldingSetNode,
        public SpecialMemberOverloadResult {
  public:
    SpecialMemberOverloadResultEntry(const llvm::FoldingSetNodeID &ID)
      : FastFoldingSetNode(ID)
    {}
  };

  /// A cache of special member function overload resolution results
  /// for C++ records.
  llvm::FoldingSet<SpecialMemberOverloadResultEntry> SpecialMemberCache;

  /// A cache of the flags available in enumerations with the flag_bits
  /// attribute.
  mutable llvm::DenseMap<const EnumDecl*, llvm::APInt> FlagBitsCache;

  /// The kind of translation unit we are processing.
  ///
  /// When we're processing a complete translation unit, Sema will perform
  /// end-of-translation-unit semantic tasks (such as creating
  /// initializers for tentative definitions in C) once parsing has
  /// completed. Modules and precompiled headers perform different kinds of
  /// checks.
  TranslationUnitKind TUKind;

  llvm::BumpPtrAllocator BumpAlloc;

  /// The number of SFINAE diagnostics that have been trapped.
  unsigned NumSFINAEErrors;

  typedef llvm::DenseMap<ParmVarDecl *, llvm::TinyPtrVector<ParmVarDecl *>>
    UnparsedDefaultArgInstantiationsMap;

  /// A mapping from parameters with unparsed default arguments to the
  /// set of instantiations of each parameter.
  ///
  /// This mapping is a temporary data structure used when parsing
  /// nested class templates or nested classes of class templates,
  /// where we might end up instantiating an inner class before the
  /// default arguments of its methods have been parsed.
  UnparsedDefaultArgInstantiationsMap UnparsedDefaultArgInstantiations;

  // Contains the locations of the beginning of unparsed default
  // argument locations.
  llvm::DenseMap<ParmVarDecl *, SourceLocation> UnparsedDefaultArgLocs;

  /// UndefinedInternals - all the used, undefined objects which require a
  /// definition in this translation unit.
  llvm::MapVector<NamedDecl *, SourceLocation> UndefinedButUsed;

  /// Determine if VD, which must be a variable or function, is an external
  /// symbol that nonetheless can't be referenced from outside this translation
  /// unit because its type has no linkage and it's not extern "C".
  bool isExternalWithNoLinkageType(ValueDecl *VD);

  /// Obtain a sorted list of functions that are undefined but ODR-used.
  void getUndefinedButUsed(
      SmallVectorImpl<std::pair<NamedDecl *, SourceLocation> > &Undefined);

  /// Retrieves list of suspicious delete-expressions that will be checked at
  /// the end of translation unit.
  const llvm::MapVector<FieldDecl *, DeleteLocs> &
  getMismatchingDeleteExpressions() const;

  typedef std::pair<ObjCMethodList, ObjCMethodList> GlobalMethods;
  typedef llvm::DenseMap<Selector, GlobalMethods> GlobalMethodPool;

  /// Method Pool - allows efficient lookup when typechecking messages to "id".
  /// We need to maintain a list, since selectors can have differing signatures
  /// across classes. In Cocoa, this happens to be extremely uncommon (only 1%
  /// of selectors are "overloaded").
  /// At the head of the list it is recorded whether there were 0, 1, or >= 2
  /// methods inside categories with a particular selector.
  GlobalMethodPool MethodPool;

  /// Method selectors used in a \@selector expression. Used for implementation
  /// of -Wselector.
  llvm::MapVector<Selector, SourceLocation> ReferencedSelectors;

  /// List of SourceLocations where 'self' is implicitly retained inside a
  /// block.
  llvm::SmallVector<std::pair<SourceLocation, const BlockDecl *>, 1>
      ImplicitlyRetainedSelfLocs;

  /// Kinds of C++ special members.
  enum CXXSpecialMember {
    CXXDefaultConstructor,
    CXXCopyConstructor,
    CXXMoveConstructor,
    CXXCopyAssignment,
    CXXMoveAssignment,
    CXXDestructor,
    CXXInvalid
  };

  typedef llvm::PointerIntPair<CXXRecordDecl *, 3, CXXSpecialMember>
      SpecialMemberDecl;

  /// The C++ special members which we are currently in the process of
  /// declaring. If this process recursively triggers the declaration of the
  /// same special member, we should act as if it is not yet declared.
  llvm::SmallPtrSet<SpecialMemberDecl, 4> SpecialMembersBeingDeclared;

  /// Kinds of defaulted comparison operator functions.
  enum class DefaultedComparisonKind : unsigned char {
    /// This is not a defaultable comparison operator.
    None,
    /// This is an operator== that should be implemented as a series of
    /// subobject comparisons.
    Equal,
    /// This is an operator<=> that should be implemented as a series of
    /// subobject comparisons.
    ThreeWay,
    /// This is an operator!= that should be implemented as a rewrite in terms
    /// of a == comparison.
    NotEqual,
    /// This is an <, <=, >, or >= that should be implemented as a rewrite in
    /// terms of a <=> comparison.
    Relational,
  };

  /// The function definitions which were renamed as part of typo-correction
  /// to match their respective declarations. We want to keep track of them
  /// to ensure that we don't emit a "redefinition" error if we encounter a
  /// correctly named definition after the renamed definition.
  llvm::SmallPtrSet<const NamedDecl *, 4> TypoCorrectedFunctionDefinitions;

  /// Stack of types that correspond to the parameter entities that are
  /// currently being copy-initialized. Can be empty.
  llvm::SmallVector<QualType, 4> CurrentParameterCopyTypes;

  void ReadMethodPool(Selector Sel);
  void updateOutOfDateSelector(Selector Sel);

  /// Private Helper predicate to check for 'self'.
  bool isSelfExpr(Expr *RExpr);
  bool isSelfExpr(Expr *RExpr, const ObjCMethodDecl *Method);

  /// Cause the active diagnostic on the DiagosticsEngine to be
  /// emitted. This is closely coupled to the SemaDiagnosticBuilder class and
  /// should not be used elsewhere.
  void EmitCurrentDiagnostic(unsigned DiagID);

  /// Records and restores the CurFPFeatures state on entry/exit of compound
  /// statements.
  class FPFeaturesStateRAII {
  public:
    FPFeaturesStateRAII(Sema &S) : S(S), OldFPFeaturesState(S.CurFPFeatures) {
      OldOverrides = S.FpPragmaStack.CurrentValue;
    }
    ~FPFeaturesStateRAII() {
      S.CurFPFeatures = OldFPFeaturesState;
      S.FpPragmaStack.CurrentValue = OldOverrides;
    }
    FPOptionsOverride getOverrides() { return OldOverrides; }

  private:
    Sema& S;
    FPOptions OldFPFeaturesState;
    FPOptionsOverride OldOverrides;
  };

  void addImplicitTypedef(StringRef Name, QualType T);

  bool WarnedStackExhausted = false;

public:
  Sema(Preprocessor &pp, ASTContext &ctxt, ASTConsumer &consumer,
       TranslationUnitKind TUKind = TU_Complete,
       CodeCompleteConsumer *CompletionConsumer = nullptr);
  ~Sema();

  /// Perform initialization that occurs after the parser has been
  /// initialized but before it parses anything.
  void Initialize();

  const LangOptions &getLangOpts() const { return LangOpts; }
  OpenCLOptions &getOpenCLOptions() { return OpenCLFeatures; }
  FPOptions     &getCurFPFeatures() { return CurFPFeatures; }

  DiagnosticsEngine &getDiagnostics() const { return Diags; }
  SourceManager &getSourceManager() const { return SourceMgr; }
  Preprocessor &getPreprocessor() const { return PP; }
  ASTContext &getASTContext() const { return Context; }
  ASTConsumer &getASTConsumer() const { return Consumer; }
  ASTMutationListener *getASTMutationListener() const;
  ExternalSemaSource* getExternalSource() const { return ExternalSource; }

  ///Registers an external source. If an external source already exists,
  /// creates a multiplex external source and appends to it.
  ///
  ///\param[in] E - A non-null external sema source.
  ///
  void addExternalSource(ExternalSemaSource *E);

  void PrintStats() const;

  /// Warn that the stack is nearly exhausted.
  void warnStackExhausted(SourceLocation Loc);

  /// Run some code with "sufficient" stack space. (Currently, at least 256K is
  /// guaranteed). Produces a warning if we're low on stack space and allocates
  /// more in that case. Use this in code that may recurse deeply (for example,
  /// in template instantiation) to avoid stack overflow.
  void runWithSufficientStackSpace(SourceLocation Loc,
                                   llvm::function_ref<void()> Fn);

  /// Helper class that creates diagnostics with optional
  /// template instantiation stacks.
  ///
  /// This class provides a wrapper around the basic DiagnosticBuilder
  /// class that emits diagnostics. SemaDiagnosticBuilder is
  /// responsible for emitting the diagnostic (as DiagnosticBuilder
  /// does) and, if the diagnostic comes from inside a template
  /// instantiation, printing the template instantiation stack as
  /// well.
  class SemaDiagnosticBuilder : public DiagnosticBuilder {
    Sema &SemaRef;
    unsigned DiagID;

  public:
    SemaDiagnosticBuilder(DiagnosticBuilder &DB, Sema &SemaRef, unsigned DiagID)
      : DiagnosticBuilder(DB), SemaRef(SemaRef), DiagID(DiagID) { }

    // This is a cunning lie. DiagnosticBuilder actually performs move
    // construction in its copy constructor (but due to varied uses, it's not
    // possible to conveniently express this as actual move construction). So
    // the default copy ctor here is fine, because the base class disables the
    // source anyway, so the user-defined ~SemaDiagnosticBuilder is a safe no-op
    // in that case anwyay.
    SemaDiagnosticBuilder(const SemaDiagnosticBuilder&) = default;

    ~SemaDiagnosticBuilder() {
      // If we aren't active, there is nothing to do.
      if (!isActive()) return6.55k;

      // Otherwise, we need to emit the diagnostic. First flush the underlying
      // DiagnosticBuilder data, and clear the diagnostic builder itself so it
      // won't emit the diagnostic in its own destructor.
      //
      // This seems wasteful, in that as written the DiagnosticBuilder dtor will
      // do its own needless checks to see if the diagnostic needs to be
      // emitted. However, because we take care to ensure that the builder
      // objects never escape, a sufficiently smart compiler will be able to
      // eliminate that code.
      FlushCounts();
      Clear();

      // Dispatch to Sema to emit the diagnostic.
      SemaRef.EmitCurrentDiagnostic(DiagID);
    }

    /// Teach operator<< to produce an object of the correct type.
    template<typename T>
    friend const SemaDiagnosticBuilder &operator<<(
        const SemaDiagnosticBuilder &Diag, const T &Value) {
      const DiagnosticBuilder &BaseDiag = Diag;
      BaseDiag << Value;
      return Diag;
    }
  };

  /// Emit a diagnostic.
  SemaDiagnosticBuilder Diag(SourceLocation Loc, unsigned DiagID) {
    DiagnosticBuilder DB = Diags.Report(Loc, DiagID);
    return SemaDiagnosticBuilder(DB, *this, DiagID);
  }

  /// Emit a partial diagnostic.
  SemaDiagnosticBuilder Diag(SourceLocation Loc, const PartialDiagnostic& PD);

  /// Build a partial diagnostic.
  PartialDiagnostic PDiag(unsigned DiagID = 0); // in SemaInternal.h

  bool findMacroSpelling(SourceLocation &loc, StringRef name);

  /// Get a string to suggest for zero-initialization of a type.
  std::string
  getFixItZeroInitializerForType(QualType T, SourceLocation Loc) const;
  std::string getFixItZeroLiteralForType(QualType T, SourceLocation Loc) const;

  /// Calls \c Lexer::getLocForEndOfToken()
  SourceLocation getLocForEndOfToken(SourceLocation Loc, unsigned Offset = 0);

  /// Retrieve the module loader associated with the preprocessor.
  ModuleLoader &getModuleLoader() const;

  /// Invent a new identifier for parameters of abbreviated templates.
  IdentifierInfo *
  InventAbbreviatedTemplateParameterTypeName(IdentifierInfo *ParamName,
                                             unsigned Index);

  void emitAndClearUnusedLocalTypedefWarnings();

  private:
    /// Function or variable declarations to be checked for whether the deferred
    /// diagnostics should be emitted.
    SmallVector<Decl *, 4> DeclsToCheckForDeferredDiags;

  public:
  // Emit all deferred diagnostics.
  void emitDeferredDiags();

  enum TUFragmentKind {
    /// The global module fragment, between 'module;' and a module-declaration.
    Global,
    /// A normal translation unit fragment. For a non-module unit, this is the
    /// entire translation unit. Otherwise, it runs from the module-declaration
    /// to the private-module-fragment (if any) or the end of the TU (if not).
    Normal,
    /// The private module fragment, between 'module :private;' and the end of
    /// the translation unit.
    Private
  };

  void ActOnStartOfTranslationUnit();
  void ActOnEndOfTranslationUnit();
  void ActOnEndOfTranslationUnitFragment(TUFragmentKind Kind);

  void CheckDelegatingCtorCycles();

  Scope *getScopeForContext(DeclContext *Ctx);

  void PushFunctionScope();
  void PushBlockScope(Scope *BlockScope, BlockDecl *Block);
  sema::LambdaScopeInfo *PushLambdaScope();

  /// This is used to inform Sema what the current TemplateParameterDepth
  /// is during Parsing.  Currently it is used to pass on the depth
  /// when parsing generic lambda 'auto' parameters.
  void RecordParsingTemplateParameterDepth(unsigned Depth);

  void PushCapturedRegionScope(Scope *RegionScope, CapturedDecl *CD,
                               RecordDecl *RD, CapturedRegionKind K,
                               unsigned OpenMPCaptureLevel = 0);

  /// Custom deleter to allow FunctionScopeInfos to be kept alive for a short
  /// time after they've been popped.
  class PoppedFunctionScopeDeleter {
    Sema *Self;

  public:
    explicit PoppedFunctionScopeDeleter(Sema *Self) : Self(Self) {}
    void operator()(sema::FunctionScopeInfo *Scope) const;
  };

  using PoppedFunctionScopePtr =
      std::unique_ptr<sema::FunctionScopeInfo, PoppedFunctionScopeDeleter>;

  PoppedFunctionScopePtr
  PopFunctionScopeInfo(const sema::AnalysisBasedWarnings::Policy *WP = nullptr,
                       const Decl *D = nullptr,
                       QualType BlockType = QualType());

  sema::FunctionScopeInfo *getCurFunction() const {
    return FunctionScopes.empty() ? nullptr242k : FunctionScopes.back();
  }

  sema::FunctionScopeInfo *getEnclosingFunction() const;

  void setFunctionHasBranchIntoScope();
  void setFunctionHasBranchProtectedScope();
  void setFunctionHasIndirectGoto();

  void PushCompoundScope(bool IsStmtExpr);
  void PopCompoundScope();

  sema::CompoundScopeInfo &getCurCompoundScope() const;

  bool hasAnyUnrecoverableErrorsInThisFunction() const;

  /// Retrieve the current block, if any.
  sema::BlockScopeInfo *getCurBlock();

  /// Get the innermost lambda enclosing the current location, if any. This
  /// looks through intervening non-lambda scopes such as local functions and
  /// blocks.
  sema::LambdaScopeInfo *getEnclosingLambda() const;

  /// Retrieve the current lambda scope info, if any.
  /// \param IgnoreNonLambdaCapturingScope true if should find the top-most
  /// lambda scope info ignoring all inner capturing scopes that are not
  /// lambda scopes.
  sema::LambdaScopeInfo *
  getCurLambda(bool IgnoreNonLambdaCapturingScope = false);

  /// Retrieve the current generic lambda info, if any.
  sema::LambdaScopeInfo *getCurGenericLambda();

  /// Retrieve the current captured region, if any.
  sema::CapturedRegionScopeInfo *getCurCapturedRegion();

  /// WeakTopLevelDeclDecls - access to \#pragma weak-generated Decls
  SmallVectorImpl<Decl *> &WeakTopLevelDecls() { return WeakTopLevelDecl; }

  /// Called before parsing a function declarator belonging to a function
  /// declaration.
  void ActOnStartFunctionDeclarationDeclarator(Declarator &D,
                                               unsigned TemplateParameterDepth);

  /// Called after parsing a function declarator belonging to a function
  /// declaration.
  void ActOnFinishFunctionDeclarationDeclarator(Declarator &D);

  void ActOnComment(SourceRange Comment);

  //===--------------------------------------------------------------------===//
  // Type Analysis / Processing: SemaType.cpp.
  //

  QualType BuildQualifiedType(QualType T, SourceLocation Loc, Qualifiers Qs,
                              const DeclSpec *DS = nullptr);
  QualType BuildQualifiedType(QualType T, SourceLocation Loc, unsigned CVRA,
                              const DeclSpec *DS = nullptr);
  QualType BuildPointerType(QualType T,
                            SourceLocation Loc, DeclarationName Entity);
  QualType BuildReferenceType(QualType T, bool LValueRef,
                              SourceLocation Loc, DeclarationName Entity);
  QualType BuildArrayType(QualType T, ArrayType::ArraySizeModifier ASM,
                          Expr *ArraySize, unsigned Quals,
                          SourceRange Brackets, DeclarationName Entity);
  QualType BuildVectorType(QualType T, Expr *VecSize, SourceLocation AttrLoc);
  QualType BuildExtVectorType(QualType T, Expr *ArraySize,
                              SourceLocation AttrLoc);
  QualType BuildMatrixType(QualType T, Expr *NumRows, Expr *NumColumns,
                           SourceLocation AttrLoc);

  QualType BuildAddressSpaceAttr(QualType &T, LangAS ASIdx, Expr *AddrSpace,
                                 SourceLocation AttrLoc);

  /// Same as above, but constructs the AddressSpace index if not provided.
  QualType BuildAddressSpaceAttr(QualType &T, Expr *AddrSpace,
                                 SourceLocation AttrLoc);

  bool CheckQualifiedFunctionForTypeId(QualType T, SourceLocation Loc);

  bool CheckFunctionReturnType(QualType T, SourceLocation Loc);

  /// Build a function type.
  ///
  /// This routine checks the function type according to C++ rules and
  /// under the assumption that the result type and parameter types have
  /// just been instantiated from a template. It therefore duplicates
  /// some of the behavior of GetTypeForDeclarator, but in a much
  /// simpler form that is only suitable for this narrow use case.
  ///
  /// \param T The return type of the function.
  ///
  /// \param ParamTypes The parameter types of the function. This array
  /// will be modified to account for adjustments to the types of the
  /// function parameters.
  ///
  /// \param Loc The location of the entity whose type involves this
  /// function type or, if there is no such entity, the location of the
  /// type that will have function type.
  ///
  /// \param Entity The name of the entity that involves the function
  /// type, if known.
  ///
  /// \param EPI Extra information about the function type. Usually this will
  /// be taken from an existing function with the same prototype.
  ///
  /// \returns A suitable function type, if there are no errors. The
  /// unqualified type will always be a FunctionProtoType.
  /// Otherwise, returns a NULL type.
  QualType BuildFunctionType(QualType T,
                             MutableArrayRef<QualType> ParamTypes,
                             SourceLocation Loc, DeclarationName Entity,
                             const FunctionProtoType::ExtProtoInfo &EPI);

  QualType BuildMemberPointerType(QualType T, QualType Class,
                                  SourceLocation Loc,
                                  DeclarationName Entity);
  QualType BuildBlockPointerType(QualType T,
                                 SourceLocation Loc, DeclarationName Entity);
  QualType BuildParenType(QualType T);
  QualType BuildAtomicType(QualType T, SourceLocation Loc);
  QualType BuildReadPipeType(QualType T,
                         SourceLocation Loc);
  QualType BuildWritePipeType(QualType T,
                         SourceLocation Loc);
  QualType BuildExtIntType(bool IsUnsigned, Expr *BitWidth, SourceLocation Loc);

  TypeSourceInfo *GetTypeForDeclarator(Declarator &D, Scope *S);
  TypeSourceInfo *GetTypeForDeclaratorCast(Declarator &D, QualType FromTy);

  /// Package the given type and TSI into a ParsedType.
  ParsedType CreateParsedType(QualType T, TypeSourceInfo *TInfo);
  DeclarationNameInfo GetNameForDeclarator(Declarator &D);
  DeclarationNameInfo GetNameFromUnqualifiedId(const UnqualifiedId &Name);
  static QualType GetTypeFromParser(ParsedType Ty,
                                    TypeSourceInfo **TInfo = nullptr);
  CanThrowResult canThrow(const Stmt *E);
  /// Determine whether the callee of a particular function call can throw.
  /// E, D and Loc are all optional.
  static CanThrowResult canCalleeThrow(Sema &S, const Expr *E, const Decl *D,
                                       SourceLocation Loc = SourceLocation());
  const FunctionProtoType *ResolveExceptionSpec(SourceLocation Loc,
                                                const FunctionProtoType *FPT);
  void UpdateExceptionSpec(FunctionDecl *FD,
                           const FunctionProtoType::ExceptionSpecInfo &ESI);
  bool CheckSpecifiedExceptionType(QualType &T, SourceRange Range);
  bool CheckDistantExceptionSpec(QualType T);
  bool CheckEquivalentExceptionSpec(FunctionDecl *Old, FunctionDecl *New);
  bool CheckEquivalentExceptionSpec(
      const FunctionProtoType *Old, SourceLocation OldLoc,
      const FunctionProtoType *New, SourceLocation NewLoc);
  bool CheckEquivalentExceptionSpec(
      const PartialDiagnostic &DiagID, const PartialDiagnostic & NoteID,
      const FunctionProtoType *Old, SourceLocation OldLoc,
      const FunctionProtoType *New, SourceLocation NewLoc);
  bool handlerCanCatch(QualType HandlerType, QualType ExceptionType);
  bool CheckExceptionSpecSubset(const PartialDiagnostic &DiagID,
                                const PartialDiagnostic &NestedDiagID,
                                const PartialDiagnostic &NoteID,
                                const PartialDiagnostic &NoThrowDiagID,
                                const FunctionProtoType *Superset,
                                SourceLocation SuperLoc,
                                const FunctionProtoType *Subset,
                                SourceLocation SubLoc);
  bool CheckParamExceptionSpec(const PartialDiagnostic &NestedDiagID,
                               const PartialDiagnostic &NoteID,
                               const FunctionProtoType *Target,
                               SourceLocation TargetLoc,
                               const FunctionProtoType *Source,
                               SourceLocation SourceLoc);

  TypeResult ActOnTypeName(Scope *S, Declarator &D);

  /// The parser has parsed the context-sensitive type 'instancetype'
  /// in an Objective-C message declaration. Return the appropriate type.
  ParsedType ActOnObjCInstanceType(SourceLocation Loc);

  /// Abstract class used to diagnose incomplete types.
  struct TypeDiagnoser {
    TypeDiagnoser() {}

    virtual void diagnose(Sema &S, SourceLocation Loc, QualType T) = 0;
    virtual ~TypeDiagnoser() {}
  };

  static int getPrintable(int I) { return I; }
  static unsigned getPrintable(unsigned I) { return I; }
  static bool getPrintable(bool B) { return B; }
  static const char * getPrintable(const char *S) { return S; }
  static StringRef getPrintable(StringRef S) { return S; }
  static const std::string &getPrintable(const std::string &S) { return S; }
  static const IdentifierInfo *getPrintable(const IdentifierInfo *II) {
    return II;
  }
  static DeclarationName getPrintable(DeclarationName N) { return N; }
  static QualType getPrintable(QualType T) { return T; }
  static SourceRange getPrintable(SourceRange R) { return R; }
  static SourceRange getPrintable(SourceLocation L) { return L; }
  static SourceRange getPrintable(const Expr *E) { return E->getSourceRange(); }
  static SourceRange getPrintable(TypeLoc TL) { return TL.getSourceRange();}

  template <typename... Ts> class BoundTypeDiagnoser : public TypeDiagnoser {
  protected:
    unsigned DiagID;
    std::tuple<const Ts &...> Args;

    template <std::size_t... Is>
    void emit(const SemaDiagnosticBuilder &DB,
              std::index_sequence<Is...>) const {
      // Apply all tuple elements to the builder in order.
      bool Dummy[] = {false, (DB << getPrintable(std::get<Is>(Args)))...};
      (void)Dummy;
    }

  public:
    BoundTypeDiagnoser(unsigned DiagID, const Ts &...Args)
        : TypeDiagnoser(), DiagID(DiagID), Args(Args...) {
      assert(DiagID != 0 && "no diagnostic for type diagnoser");
    }

    void diagnose(Sema &S, SourceLocation Loc, QualType T) override {
      const SemaDiagnosticBuilder &DB = S.Diag(Loc, DiagID);
      emit(DB, std::index_sequence_for<Ts...>());
      DB << T;
    }
  };

  /// A derivative of BoundTypeDiagnoser for which the diagnostic's type
  /// parameter is preceded by a 0/1 enum that is 1 if the type is sizeless.
  /// For example, a diagnostic with no other parameters would generally have
  /// the form "...%select{incomplete|sizeless}0 type %1...".
  template <typename... Ts>
  class SizelessTypeDiagnoser : public BoundTypeDiagnoser<Ts...> {
  public:
    SizelessTypeDiagnoser(unsigned DiagID, const Ts &... Args)
        : BoundTypeDiagnoser<Ts...>(DiagID, Args...) {}

    void diagnose(Sema &S, SourceLocation Loc, QualType T) override {
      const SemaDiagnosticBuilder &DB = S.Diag(Loc, this->DiagID);
      this->emit(DB, std::index_sequence_for<Ts...>());
      DB << T->isSizelessType() << T;
    }
  };

  enum class CompleteTypeKind {
    /// Apply the normal rules for complete types.  In particular,
    /// treat all sizeless types as incomplete.
    Normal,

    /// Relax the normal rules for complete types so that they include
    /// sizeless built-in types.
    AcceptSizeless,

    // FIXME: Eventually we should flip the default to Normal and opt in
    // to AcceptSizeless rather than opt out of it.
    Default = AcceptSizeless
  };

private:
  /// Methods for marking which expressions involve dereferencing a pointer
  /// marked with the 'noderef' attribute. Expressions are checked bottom up as
  /// they are parsed, meaning that a noderef pointer may not be accessed. For
  /// example, in `&*p` where `p` is a noderef pointer, we will first parse the
  /// `*p`, but need to check that `address of` is called on it. This requires
  /// keeping a container of all pending expressions and checking if the address
  /// of them are eventually taken.
  void CheckSubscriptAccessOfNoDeref(const ArraySubscriptExpr *E);
  void CheckAddressOfNoDeref(const Expr *E);
  void CheckMemberAccessOfNoDeref(const MemberExpr *E);

  bool RequireCompleteTypeImpl(SourceLocation Loc, QualType T,
                               CompleteTypeKind Kind, TypeDiagnoser *Diagnoser);

  struct ModuleScope {
    SourceLocation BeginLoc;
    clang::Module *Module = nullptr;
    bool ModuleInterface = false;
    bool ImplicitGlobalModuleFragment = false;
    VisibleModuleSet OuterVisibleModules;
  };
  /// The modules we're currently parsing.
  llvm::SmallVector<ModuleScope, 16> ModuleScopes;

  /// Namespace definitions that we will export when they finish.
  llvm::SmallPtrSet<const NamespaceDecl*, 8> DeferredExportedNamespaces;

  /// Get the module whose scope we are currently within.
  Module *getCurrentModule() const {
    return ModuleScopes.empty() ? nullptr : ModuleScopes.back().Module169k;
  }

  VisibleModuleSet VisibleModules;

public:
  /// Get the module owning an entity.
  Module *getOwningModule(const Decl *Entity) {
    return Entity->getOwningModule();
  }

  /// Make a merged definition of an existing hidden definition \p ND
  /// visible at the specified location.
  void makeMergedDefinitionVisible(NamedDecl *ND);

  bool isModuleVisible(const Module *M, bool ModulePrivate = false);

  // When loading a non-modular PCH files, this is used to restore module
  // visibility.
  void makeModuleVisible(Module *Mod, SourceLocation ImportLoc) {
    VisibleModules.setVisible(Mod, ImportLoc);
  }

  /// Determine whether a declaration is visible to name lookup.
  bool isVisible(const NamedDecl *D) {
    return D->isUnconditionallyVisible() || isVisibleSlow(D)44.6k;
  }

  /// Determine whether any declaration of an entity is visible.
  bool
  hasVisibleDeclaration(const NamedDecl *D,
                        llvm::SmallVectorImpl<Module *> *Modules = nullptr) {
    return isVisible(D) || hasVisibleDeclarationSlow(D, Modules)71;
  }
  bool hasVisibleDeclarationSlow(const NamedDecl *D,
                                 llvm::SmallVectorImpl<Module *> *Modules);

  bool hasVisibleMergedDefinition(NamedDecl *Def);
  bool hasMergedDefinitionInCurrentModule(NamedDecl *Def);

  /// Determine if \p D and \p Suggested have a structurally compatible
  /// layout as described in C11 6.2.7/1.
  bool hasStructuralCompatLayout(Decl *D, Decl *Suggested);

  /// Determine if \p D has a visible definition. If not, suggest a declaration
  /// that should be made visible to expose the definition.
  bool hasVisibleDefinition(NamedDecl *D, NamedDecl **Suggested,
                            bool OnlyNeedComplete = false);
  bool hasVisibleDefinition(const NamedDecl *D) {
    NamedDecl *Hidden;
    return hasVisibleDefinition(const_cast<NamedDecl*>(D), &Hidden);
  }

  /// Determine if the template parameter \p D has a visible default argument.
  bool
  hasVisibleDefaultArgument(const NamedDecl *D,
                            llvm::SmallVectorImpl<Module *> *Modules = nullptr);

  /// Determine if there is a visible declaration of \p D that is an explicit
  /// specialization declaration for a specialization of a template. (For a
  /// member specialization, use hasVisibleMemberSpecialization.)
  bool hasVisibleExplicitSpecialization(
      const NamedDecl *D, llvm::SmallVectorImpl<Module *> *Modules = nullptr);

  /// Determine if there is a visible declaration of \p D that is a member
  /// specialization declaration (as opposed to an instantiated declaration).
  bool hasVisibleMemberSpecialization(
      const NamedDecl *D, llvm::SmallVectorImpl<Module *> *Modules = nullptr);

  /// Determine if \p A and \p B are equivalent internal linkage declarations
  /// from different modules, and thus an ambiguity error can be downgraded to
  /// an extension warning.
  bool isEquivalentInternalLinkageDeclaration(const NamedDecl *A,
                                              const NamedDecl *B);
  void diagnoseEquivalentInternalLinkageDeclarations(
      SourceLocation Loc, const NamedDecl *D,
      ArrayRef<const NamedDecl *> Equiv);

  bool isUsualDeallocationFunction(const CXXMethodDecl *FD);

  bool isCompleteType(SourceLocation Loc, QualType T,
                      CompleteTypeKind Kind = CompleteTypeKind::Default) {
    return !RequireCompleteTypeImpl(Loc, T, Kind, nullptr);
  }
  bool RequireCompleteType(SourceLocation Loc, QualType T,
                           CompleteTypeKind Kind, TypeDiagnoser &Diagnoser);
  bool RequireCompleteType(SourceLocation Loc, QualType T,
                           CompleteTypeKind Kind, unsigned DiagID);

  bool RequireCompleteType(SourceLocation Loc, QualType T,
                           TypeDiagnoser &Diagnoser) {
    return RequireCompleteType(Loc, T, CompleteTypeKind::Default, Diagnoser);
  }
  bool RequireCompleteType(SourceLocation Loc, QualType T, unsigned DiagID) {
    return RequireCompleteType(Loc, T, CompleteTypeKind::Default, DiagID);
  }

  template <typename... Ts>
  bool RequireCompleteType(SourceLocation Loc, QualType T, unsigned DiagID,
                           const Ts &...Args) {
    BoundTypeDiagnoser<Ts...> Diagnoser(DiagID, Args...);
    return RequireCompleteType(Loc, T, Diagnoser);
  }

  template <typename... Ts>
  bool RequireCompleteSizedType(SourceLocation Loc, QualType T, unsigned DiagID,
                                const Ts &... Args) {
    SizelessTypeDiagnoser<Ts...> Diagnoser(DiagID, Args...);
    return RequireCompleteType(Loc, T, CompleteTypeKind::Normal, Diagnoser);
  }

  void completeExprArrayBound(Expr *E);
  bool RequireCompleteExprType(Expr *E, CompleteTypeKind Kind,
                               TypeDiagnoser &Diagnoser);
  bool RequireCompleteExprType(Expr *E, unsigned DiagID);

  template <typename... Ts>
  bool RequireCompleteExprType(Expr *E, unsigned DiagID, const Ts &...Args) {
    BoundTypeDiagnoser<Ts...> Diagnoser(DiagID, Args...);
    return RequireCompleteExprType(E, CompleteTypeKind::Default, Diagnoser);
  }

  template <typename... Ts>
  bool RequireCompleteSizedExprType(Expr *E, unsigned DiagID,
                                    const Ts &... Args) {
    SizelessTypeDiagnoser<Ts...> Diagnoser(DiagID, Args...);
    return RequireCompleteExprType(E, CompleteTypeKind::Normal, Diagnoser);
  }

  bool RequireLiteralType(SourceLocation Loc, QualType T,
                          TypeDiagnoser &Diagnoser);
  bool RequireLiteralType(SourceLocation Loc, QualType T, unsigned DiagID);

  template <typename... Ts>
  bool RequireLiteralType(SourceLocation Loc, QualType T, unsigned DiagID,
                          const Ts &...Args) {
    BoundTypeDiagnoser<Ts...> Diagnoser(DiagID, Args...);
    return RequireLiteralType(Loc, T, Diagnoser);
  }

  QualType getElaboratedType(ElaboratedTypeKeyword Keyword,
                             const CXXScopeSpec &SS, QualType T,
                             TagDecl *OwnedTagDecl = nullptr);

  QualType BuildTypeofExprType(Expr *E, SourceLocation Loc);
  /// If AsUnevaluated is false, E is treated as though it were an evaluated
  /// context, such as when building a type for decltype(auto).
  QualType BuildDecltypeType(Expr *E, SourceLocation Loc,
                             bool AsUnevaluated = true);
  QualType BuildUnaryTransformType(QualType BaseType,
                                   UnaryTransformType::UTTKind UKind,
                                   SourceLocation Loc);

  //===--------------------------------------------------------------------===//
  // Symbol table / Decl tracking callbacks: SemaDecl.cpp.
  //

  struct SkipBodyInfo {
    SkipBodyInfo()
        : ShouldSkip(false), CheckSameAsPrevious(false), Previous(nullptr),
          New(nullptr) {}
    bool ShouldSkip;
    bool CheckSameAsPrevious;
    NamedDecl *Previous;
    NamedDecl *New;
  };

  DeclGroupPtrTy ConvertDeclToDeclGroup(Decl *Ptr, Decl *OwnedType = nullptr);

  void DiagnoseUseOfUnimplementedSelectors();

  bool isSimpleTypeSpecifier(tok::TokenKind Kind) const;

  ParsedType getTypeName(const IdentifierInfo &II, SourceLocation NameLoc,
                         Scope *S, CXXScopeSpec *SS = nullptr,
                         bool isClassName = false, bool HasTrailingDot = false,
                         ParsedType ObjectType = nullptr,
                         bool IsCtorOrDtorName = false,
                         bool WantNontrivialTypeSourceInfo = false,
                         bool IsClassTemplateDeductionContext = true,
                         IdentifierInfo **CorrectedII = nullptr);
  TypeSpecifierType isTagName(IdentifierInfo &II, Scope *S);
  bool isMicrosoftMissingTypename(const CXXScopeSpec *SS, Scope *S);
  void DiagnoseUnknownTypeName(IdentifierInfo *&II,
                               SourceLocation IILoc,
                               Scope *S,
                               CXXScopeSpec *SS,
                               ParsedType &SuggestedType,
                               bool IsTemplateName = false);

  /// Attempt to behave like MSVC in situations where lookup of an unqualified
  /// type name has failed in a dependent context. In these situations, we
  /// automatically form a DependentTypeName that will retry lookup in a related
  /// scope during instantiation.
  ParsedType ActOnMSVCUnknownTypeName(const IdentifierInfo &II,
                                      SourceLocation NameLoc,
                                      bool IsTemplateTypeArg);

  /// Describes the result of the name lookup and resolution performed
  /// by \c ClassifyName().
  enum NameClassificationKind {
    /// This name is not a type or template in this context, but might be
    /// something else.
    NC_Unknown,
    /// Classification failed; an error has been produced.
    NC_Error,
    /// The name has been typo-corrected to a keyword.
    NC_Keyword,
    /// The name was classified as a type.
    NC_Type,
    /// The name was classified as a specific non-type, non-template
    /// declaration. ActOnNameClassifiedAsNonType should be called to
    /// convert the declaration to an expression.
    NC_NonType,
    /// The name was classified as an ADL-only function name.
    /// ActOnNameClassifiedAsUndeclaredNonType should be called to convert the
    /// result to an expression.
    NC_UndeclaredNonType,
    /// The name denotes a member of a dependent type that could not be
    /// resolved. ActOnNameClassifiedAsDependentNonType should be called to
    /// convert the result to an expression.
    NC_DependentNonType,
    /// The name was classified as an overload set, and an expression
    /// representing that overload set has been formed.
    /// ActOnNameClassifiedAsOverloadSet should be called to form a suitable
    /// expression referencing the overload set.
    NC_OverloadSet,
    /// The name was classified as a template whose specializations are types.
    NC_TypeTemplate,
    /// The name was classified as a variable template name.
    NC_VarTemplate,
    /// The name was classified as a function template name.
    NC_FunctionTemplate,
    /// The name was classified as an ADL-only function template name.
    NC_UndeclaredTemplate,
    /// The name was classified as a concept name.
    NC_Concept,
  };

  class NameClassification {
    NameClassificationKind Kind;
    union {
      ExprResult Expr;
      NamedDecl *NonTypeDecl;
      TemplateName Template;
      ParsedType Type;
    };

    explicit NameClassification(NameClassificationKind Kind) : Kind(Kind) {}

  public:
    NameClassification(ParsedType Type) : Kind(NC_Type), Type(Type) {}

    NameClassification(const IdentifierInfo *Keyword) : Kind(NC_Keyword) {}

    static NameClassification Error() {
      return NameClassification(NC_Error);
    }

    static NameClassification Unknown() {
      return NameClassification(NC_Unknown);
    }

    static NameClassification OverloadSet(ExprResult E) {
      NameClassification Result(NC_OverloadSet);
      Result.Expr = E;
      return Result;
    }

    static NameClassification NonType(NamedDecl *D) {
      NameClassification Result(NC_NonType);
      Result.NonTypeDecl = D;
      return Result;
    }

    static NameClassification UndeclaredNonType() {
      return NameClassification(NC_UndeclaredNonType);
    }

    static NameClassification DependentNonType() {
      return NameClassification(NC_DependentNonType);
    }

    static NameClassification TypeTemplate(TemplateName Name) {
      NameClassification Result(NC_TypeTemplate);
      Result.Template = Name;
      return Result;
    }

    static NameClassification VarTemplate(TemplateName Name) {
      NameClassification Result(NC_VarTemplate);
      Result.Template = Name;
      return Result;
    }

    static NameClassification FunctionTemplate(TemplateName Name) {
      NameClassification Result(NC_FunctionTemplate);
      Result.Template = Name;
      return Result;
    }

    static NameClassification Concept(TemplateName Name) {
      NameClassification Result(NC_Concept);
      Result.Template = Name;
      return Result;
    }

    static NameClassification UndeclaredTemplate(TemplateName Name) {
      NameClassification Result(NC_UndeclaredTemplate);
      Result.Template = Name;
      return Result;
    }

    NameClassificationKind getKind() const { return Kind; }

    ExprResult getExpression() const {
      assert(Kind == NC_OverloadSet);
      return Expr;
    }

    ParsedType getType() const {
      assert(Kind == NC_Type);
      return Type;
    }

    NamedDecl *getNonTypeDecl() const {
      assert(Kind == NC_NonType);
      return NonTypeDecl;
    }

    TemplateName getTemplateName() const {
      assert(Kind == NC_TypeTemplate || Kind == NC_FunctionTemplate ||
             Kind == NC_VarTemplate || Kind == NC_Concept ||
             Kind == NC_UndeclaredTemplate);
      return Template;
    }

    TemplateNameKind getTemplateNameKind() const {
      switch (Kind) {
      case NC_TypeTemplate:
        return TNK_Type_template;
      case NC_FunctionTemplate:
        return TNK_Function_template;
      case NC_VarTemplate:
        return TNK_Var_template;
      case NC_Concept:
        return TNK_Concept_template;
      case NC_UndeclaredTemplate:
        return TNK_Undeclared_template;
      default:
        llvm_unreachable("unsupported name classification.");
      }
    }
  };

  /// Perform name lookup on the given name, classifying it based on
  /// the results of name lookup and the following token.
  ///
  /// This routine is used by the parser to resolve identifiers and help direct
  /// parsing. When the identifier cannot be found, this routine will attempt
  /// to correct the typo and classify based on the resulting name.
  ///
  /// \param S The scope in which we're performing name lookup.
  ///
  /// \param SS The nested-name-specifier that precedes the name.
  ///
  /// \param Name The identifier. If typo correction finds an alternative name,
  /// this pointer parameter will be updated accordingly.
  ///
  /// \param NameLoc The location of the identifier.
  ///
  /// \param NextToken The token following the identifier. Used to help
  /// disambiguate the name.
  ///
  /// \param CCC The correction callback, if typo correction is desired.
  NameClassification ClassifyName(Scope *S, CXXScopeSpec &SS,
                                  IdentifierInfo *&Name, SourceLocation NameLoc,
                                  const Token &NextToken,
                                  CorrectionCandidateCallback *CCC = nullptr);

  /// Act on the result of classifying a name as an undeclared (ADL-only)
  /// non-type declaration.
  ExprResult ActOnNameClassifiedAsUndeclaredNonType(IdentifierInfo *Name,
                                                    SourceLocation NameLoc);
  /// Act on the result of classifying a name as an undeclared member of a
  /// dependent base class.
  ExprResult ActOnNameClassifiedAsDependentNonType(const CXXScopeSpec &SS,
                                                   IdentifierInfo *Name,
                                                   SourceLocation NameLoc,
                                                   bool IsAddressOfOperand);
  /// Act on the result of classifying a name as a specific non-type
  /// declaration.
  ExprResult ActOnNameClassifiedAsNonType(Scope *S, const CXXScopeSpec &SS,
                                          NamedDecl *Found,
                                          SourceLocation NameLoc,
                                          const Token &NextToken);
  /// Act on the result of classifying a name as an overload set.
  ExprResult ActOnNameClassifiedAsOverloadSet(Scope *S, Expr *OverloadSet);

  /// Describes the detailed kind of a template name. Used in diagnostics.
  enum class TemplateNameKindForDiagnostics {
    ClassTemplate,
    FunctionTemplate,
    VarTemplate,
    AliasTemplate,
    TemplateTemplateParam,
    Concept,
    DependentTemplate
  };
  TemplateNameKindForDiagnostics
  getTemplateNameKindForDiagnostics(TemplateName Name);

  /// Determine whether it's plausible that E was intended to be a
  /// template-name.
  bool mightBeIntendedToBeTemplateName(ExprResult E, bool &Dependent) {
    if (!getLangOpts().CPlusPlus || E.isInvalid()177k)
      return false;
    Dependent = false;
    if (auto *DRE = dyn_cast<DeclRefExpr>(E.get()))
      return !DRE->hasExplicitTemplateArgs();
    if (auto *ME = dyn_cast<MemberExpr>(E.get()))
      return !ME->hasExplicitTemplateArgs();
    Dependent = true;
    if (auto *DSDRE = dyn_cast<DependentScopeDeclRefExpr>(E.get()))
      return !DSDRE->hasExplicitTemplateArgs();
    if (auto *DSME = dyn_cast<CXXDependentScopeMemberExpr>(E.get()))
      return !DSME->hasExplicitTemplateArgs();
    // Any additional cases recognized here should also be handled by
    // diagnoseExprIntendedAsTemplateName.
    return false;
  }
  void diagnoseExprIntendedAsTemplateName(Scope *S, ExprResult TemplateName,
                                          SourceLocation Less,
                                          SourceLocation Greater);

  Decl *ActOnDeclarator(Scope *S, Declarator &D);

  NamedDecl *HandleDeclarator(Scope *S, Declarator &D,
                              MultiTemplateParamsArg TemplateParameterLists);
  void RegisterLocallyScopedExternCDecl(NamedDecl *ND, Scope *S);
  bool DiagnoseClassNameShadow(DeclContext *DC, DeclarationNameInfo Info);
  bool diagnoseQualifiedDeclaration(CXXScopeSpec &SS, DeclContext *DC,
                                    DeclarationName Name, SourceLocation Loc,
                                    bool IsTemplateId);
  void
  diagnoseIgnoredQualifiers(unsigned DiagID, unsigned Quals,
                            SourceLocation FallbackLoc,
                            SourceLocation ConstQualLoc = SourceLocation(),
                            SourceLocation VolatileQualLoc = SourceLocation(),
                            SourceLocation RestrictQualLoc = SourceLocation(),
                            SourceLocation AtomicQualLoc = SourceLocation(),
                            SourceLocation UnalignedQualLoc = SourceLocation());

  static bool adjustContextForLocalExternDecl(DeclContext *&DC);
  void DiagnoseFunctionSpecifiers(const DeclSpec &DS);
  NamedDecl *getShadowedDeclaration(const TypedefNameDecl *D,
                                    const LookupResult &R);
  NamedDecl *getShadowedDeclaration(const VarDecl *D, const LookupResult &R);
  void CheckShadow(NamedDecl *D, NamedDecl *ShadowedDecl,
                   const LookupResult &R);
  void CheckShadow(Scope *S, VarDecl *D);

  /// Warn if 'E', which is an expression that is about to be modified, refers
  /// to a shadowing declaration.
  void CheckShadowingDeclModification(Expr *E, SourceLocation Loc);

  void DiagnoseShadowingLambdaDecls(const sema::LambdaScopeInfo *LSI);

private:
  /// Map of current shadowing declarations to shadowed declarations. Warn if
  /// it looks like the user is trying to modify the shadowing declaration.
  llvm::DenseMap<const NamedDecl *, const NamedDecl *> ShadowingDecls;

public:
  void CheckCastAlign(Expr *Op, QualType T, SourceRange TRange);
  void handleTagNumbering(const TagDecl *Tag, Scope *TagScope);
  void setTagNameForLinkagePurposes(TagDecl *TagFromDeclSpec,
                                    TypedefNameDecl *NewTD);
  void CheckTypedefForVariablyModifiedType(Scope *S, TypedefNameDecl *D);
  NamedDecl* ActOnTypedefDeclarator(Scope* S, Declarator& D, DeclContext* DC,
                                    TypeSourceInfo *TInfo,
                                    LookupResult &Previous);
  NamedDecl* ActOnTypedefNameDecl(Scope* S, DeclContext* DC, TypedefNameDecl *D,
                                  LookupResult &Previous, bool &Redeclaration);
  NamedDecl *ActOnVariableDeclarator(Scope *S, Declarator &D, DeclContext *DC,
                                     TypeSourceInfo *TInfo,
                                     LookupResult &Previous,
                                     MultiTemplateParamsArg TemplateParamLists,
                                     bool &AddToScope,
                                     ArrayRef<BindingDecl *> Bindings = None);
  NamedDecl *
  ActOnDecompositionDeclarator(Scope *S, Declarator &D,
                               MultiTemplateParamsArg TemplateParamLists);
  // Returns true if the variable declaration is a redeclaration
  bool CheckVariableDeclaration(VarDecl *NewVD, LookupResult &Previous);
  void CheckVariableDeclarationType(VarDecl *NewVD);
  bool DeduceVariableDeclarationType(VarDecl *VDecl, bool DirectInit,
                                     Expr *Init);
  void CheckCompleteVariableDeclaration(VarDecl *VD);
  void CheckCompleteDecompositionDeclaration(DecompositionDecl *DD);
  void MaybeSuggestAddingStaticToDecl(const FunctionDecl *D);

  NamedDecl* ActOnFunctionDeclarator(Scope* S, Declarator& D, DeclContext* DC,
                                     TypeSourceInfo *TInfo,
                                     LookupResult &Previous,
                                     MultiTemplateParamsArg TemplateParamLists,
                                     bool &AddToScope);
  bool AddOverriddenMethods(CXXRecordDecl *DC, CXXMethodDecl *MD);

  enum class CheckConstexprKind {
    /// Diagnose issues that are non-constant or that are extensions.
    Diagnose,
    /// Identify whether this function satisfies the formal rules for constexpr
    /// functions in the current lanugage mode (with no extensions).
    CheckValid
  };

  bool CheckConstexprFunctionDefinition(const FunctionDecl *FD,
                                        CheckConstexprKind Kind);

  void DiagnoseHiddenVirtualMethods(CXXMethodDecl *MD);
  void FindHiddenVirtualMethods(CXXMethodDecl *MD,
                          SmallVectorImpl<CXXMethodDecl*> &OverloadedMethods);
  void NoteHiddenVirtualMethods(CXXMethodDecl *MD,
                          SmallVectorImpl<CXXMethodDecl*> &OverloadedMethods);
  // Returns true if the function declaration is a redeclaration
  bool CheckFunctionDeclaration(Scope *S,
                                FunctionDecl *NewFD, LookupResult &Previous,
                                bool IsMemberSpecialization);
  bool shouldLinkDependentDeclWithPrevious(Decl *D, Decl *OldDecl);
  bool canFullyTypeCheckRedeclaration(ValueDecl *NewD, ValueDecl *OldD,
                                      QualType NewT, QualType OldT);
  void CheckMain(FunctionDecl *FD, const DeclSpec &D);
  void CheckMSVCRTEntryPoint(FunctionDecl *FD);
  Attr *getImplicitCodeSegOrSectionAttrForFunction(const FunctionDecl *FD,
                                                   bool IsDefinition);
  void CheckFunctionOrTemplateParamDeclarator(Scope *S, Declarator &D);
  Decl *ActOnParamDeclarator(Scope *S, Declarator &D);
  ParmVarDecl *BuildParmVarDeclForTypedef(DeclContext *DC,
                                          SourceLocation Loc,
                                          QualType T);
  ParmVarDecl *CheckParameter(DeclContext *DC, SourceLocation StartLoc,
                              SourceLocation NameLoc, IdentifierInfo *Name,
                              QualType T, TypeSourceInfo *TSInfo,
                              StorageClass SC);
  void ActOnParamDefaultArgument(Decl *param,
                                 SourceLocation EqualLoc,
                                 Expr *defarg);
  void ActOnParamUnparsedDefaultArgument(Decl *param, SourceLocation EqualLoc,
                                         SourceLocation ArgLoc);
  void ActOnParamDefaultArgumentError(Decl *param, SourceLocation EqualLoc);
  ExprResult ConvertParamDefaultArgument(const ParmVarDecl *Param,
                                         Expr *DefaultArg,
                                         SourceLocation EqualLoc);
  void SetParamDefaultArgument(ParmVarDecl *Param, Expr *DefaultArg,
                               SourceLocation EqualLoc);

  // Contexts where using non-trivial C union types can be disallowed. This is
  // passed to err_non_trivial_c_union_in_invalid_context.
  enum NonTrivialCUnionContext {
    // Function parameter.
    NTCUC_FunctionParam,
    // Function return.
    NTCUC_FunctionReturn,
    // Default-initialized object.
    NTCUC_DefaultInitializedObject,
    // Variable with automatic storage duration.
    NTCUC_AutoVar,
    // Initializer expression that might copy from another object.
    NTCUC_CopyInit,
    // Assignment.
    NTCUC_Assignment,
    // Compound literal.
    NTCUC_CompoundLiteral,
    // Block capture.
    NTCUC_BlockCapture,
    // lvalue-to-rvalue conversion of volatile type.
    NTCUC_LValueToRValueVolatile,
  };

  /// Emit diagnostics if the initializer or any of its explicit or
  /// implicitly-generated subexpressions require copying or
  /// default-initializing a type that is or contains a C union type that is
  /// non-trivial to copy or default-initialize.
  void checkNonTrivialCUnionInInitializer(const Expr *Init, SourceLocation Loc);

  // These flags are passed to checkNonTrivialCUnion.
  enum NonTrivialCUnionKind {
    NTCUK_Init = 0x1,
    NTCUK_Destruct = 0x2,
    NTCUK_Copy = 0x4,
  };

  /// Emit diagnostics if a non-trivial C union type or a struct that contains
  /// a non-trivial C union is used in an invalid context.
  void checkNonTrivialCUnion(QualType QT, SourceLocation Loc,
                             NonTrivialCUnionContext UseContext,
                             unsigned NonTrivialKind);

  void AddInitializerToDecl(Decl *dcl, Expr *init, bool DirectInit);
  void ActOnUninitializedDecl(Decl *dcl);
  void ActOnInitializerError(Decl *Dcl);

  void ActOnPureSpecifier(Decl *D, SourceLocation PureSpecLoc);
  void ActOnCXXForRangeDecl(Decl *D);
  StmtResult ActOnCXXForRangeIdentifier(Scope *S, SourceLocation IdentLoc,
                                        IdentifierInfo *Ident,
                                        ParsedAttributes &Attrs,
                                        SourceLocation AttrEnd);
  void SetDeclDeleted(Decl *dcl, SourceLocation DelLoc);
  void SetDeclDefaulted(Decl *dcl, SourceLocation DefaultLoc);
  void CheckStaticLocalForDllExport(VarDecl *VD);
  void FinalizeDeclaration(Decl *D);
  DeclGroupPtrTy FinalizeDeclaratorGroup(Scope *S, const DeclSpec &DS,
                                         ArrayRef<Decl *> Group);
  DeclGroupPtrTy BuildDeclaratorGroup(MutableArrayRef<Decl *> Group);

  /// Should be called on all declarations that might have attached
  /// documentation comments.
  void ActOnDocumentableDecl(Decl *D);
  void ActOnDocumentableDecls(ArrayRef<Decl *> Group);

  void ActOnFinishKNRParamDeclarations(Scope *S, Declarator &D,
                                       SourceLocation LocAfterDecls);
  void CheckForFunctionRedefinition(
      FunctionDecl *FD, const FunctionDecl *EffectiveDefinition = nullptr,
      SkipBodyInfo *SkipBody = nullptr);
  Decl *ActOnStartOfFunctionDef(Scope *S, Declarator &D,
                                MultiTemplateParamsArg TemplateParamLists,
                                SkipBodyInfo *SkipBody = nullptr);
  Decl *ActOnStartOfFunctionDef(Scope *S, Decl *D,
                                SkipBodyInfo *SkipBody = nullptr);
  void ActOnStartTrailingRequiresClause(Scope *S, Declarator &D);
  ExprResult ActOnFinishTrailingRequiresClause(ExprResult ConstraintExpr);
  void ActOnStartOfObjCMethodDef(Scope *S, Decl *D);
  bool isObjCMethodDecl(Decl *D) {
    return D && isa<ObjCMethodDecl>(D);
  }

  /// Determine whether we can delay parsing the body of a function or
  /// function template until it is used, assuming we don't care about emitting
  /// code for that function.
  ///
  /// This will be \c false if we may need the body of the function in the
  /// middle of parsing an expression (where it's impractical to switch to
  /// parsing a different function), for instance, if it's constexpr in C++11
  /// or has an 'auto' return type in C++14. These cases are essentially bugs.
  bool canDelayFunctionBody(const Declarator &D);

  /// Determine whether we can skip parsing the body of a function
  /// definition, assuming we don't care about analyzing its body or emitting
  /// code for that function.
  ///
  /// This will be \c false only if we may need the body of the function in
  /// order to parse the rest of the program (for instance, if it is
  /// \c constexpr in C++11 or has an 'auto' return type in C++14).
  bool canSkipFunctionBody(Decl *D);

  void computeNRVO(Stmt *Body, sema::FunctionScopeInfo *Scope);
  Decl *ActOnFinishFunctionBody(Decl *Decl, Stmt *Body);
  Decl *ActOnFinishFunctionBody(Decl *Decl, Stmt *Body, bool IsInstantiation);
  Decl *ActOnSkippedFunctionBody(Decl *Decl);
  void ActOnFinishInlineFunctionDef(FunctionDecl *D);

  /// ActOnFinishDelayedAttribute - Invoked when we have finished parsing an
  /// attribute for which parsing is delayed.
  void ActOnFinishDelayedAttribute(Scope *S, Decl *D, ParsedAttributes &Attrs);

  /// Diagnose any unused parameters in the given sequence of
  /// ParmVarDecl pointers.
  void DiagnoseUnusedParameters(ArrayRef<ParmVarDecl *> Parameters);

  /// Diagnose whether the size of parameters or return value of a
  /// function or obj-c method definition is pass-by-value and larger than a
  /// specified threshold.
  void
  DiagnoseSizeOfParametersAndReturnValue(ArrayRef<ParmVarDecl *> Parameters,
                                         QualType ReturnTy, NamedDecl *D);

  void DiagnoseInvalidJumps(Stmt *Body);
  Decl *ActOnFileScopeAsmDecl(Expr *expr,
                              SourceLocation AsmLoc,
                              SourceLocation RParenLoc);

  /// Handle a C++11 empty-declaration and attribute-declaration.
  Decl *ActOnEmptyDeclaration(Scope *S, const ParsedAttributesView &AttrList,
                              SourceLocation SemiLoc);

  enum class ModuleDeclKind {
    Interface,      ///< 'export module X;'
    Implementation, ///< 'module X;'
  };

  /// The parser has processed a module-declaration that begins the definition
  /// of a module interface or implementation.
  DeclGroupPtrTy ActOnModuleDecl(SourceLocation StartLoc,
                                 SourceLocation ModuleLoc, ModuleDeclKind MDK,
                                 ModuleIdPath Path, bool IsFirstDecl);

  /// The parser has processed a global-module-fragment declaration that begins
  /// the definition of the global module fragment of the current module unit.
  /// \param ModuleLoc The location of the 'module' keyword.
  DeclGroupPtrTy ActOnGlobalModuleFragmentDecl(SourceLocation ModuleLoc);

  /// The parser has processed a private-module-fragment declaration that begins
  /// the definition of the private module fragment of the current module unit.
  /// \param ModuleLoc The location of the 'module' keyword.
  /// \param PrivateLoc The location of the 'private' keyword.
  DeclGroupPtrTy ActOnPrivateModuleFragmentDecl(SourceLocation ModuleLoc,
                                                SourceLocation PrivateLoc);

  /// The parser has processed a module import declaration.
  ///
  /// \param StartLoc The location of the first token in the declaration. This
  ///        could be the location of an '@', 'export', or 'import'.
  /// \param ExportLoc The location of the 'export' keyword, if any.
  /// \param ImportLoc The location of the 'import' keyword.
  /// \param Path The module access path.
  DeclResult ActOnModuleImport(SourceLocation StartLoc,
                               SourceLocation ExportLoc,
                               SourceLocation ImportLoc, ModuleIdPath Path);
  DeclResult ActOnModuleImport(SourceLocation StartLoc,
                               SourceLocation ExportLoc,
                               SourceLocation ImportLoc, Module *M,
                               ModuleIdPath Path = {});

  /// The parser has processed a module import translated from a
  /// #include or similar preprocessing directive.
  void ActOnModuleInclude(SourceLocation DirectiveLoc, Module *Mod);
  void BuildModuleInclude(SourceLocation DirectiveLoc, Module *Mod);

  /// The parsed has entered a submodule.
  void ActOnModuleBegin(SourceLocation DirectiveLoc, Module *Mod);
  /// The parser has left a submodule.
  void ActOnModuleEnd(SourceLocation DirectiveLoc, Module *Mod);

  /// Create an implicit import of the given module at the given
  /// source location, for error recovery, if possible.
  ///
  /// This routine is typically used when an entity found by name lookup
  /// is actually hidden within a module that we know about but the user
  /// has forgotten to import.
  void createImplicitModuleImportForErrorRecovery(SourceLocation Loc,
                                                  Module *Mod);

  /// Kinds of missing import. Note, the values of these enumerators correspond
  /// to %select values in diagnostics.
  enum class MissingImportKind {
    Declaration,
    Definition,
    DefaultArgument,
    ExplicitSpecialization,
    PartialSpecialization
  };

  /// Diagnose that the specified declaration needs to be visible but
  /// isn't, and suggest a module import that would resolve the problem.
  void diagnoseMissingImport(SourceLocation Loc, NamedDecl *Decl,
                             MissingImportKind MIK, bool Recover = true);
  void diagnoseMissingImport(SourceLocation Loc, NamedDecl *Decl,
                             SourceLocation DeclLoc, ArrayRef<Module *> Modules,
                             MissingImportKind MIK, bool Recover);

  Decl *ActOnStartExportDecl(Scope *S, SourceLocation ExportLoc,
                             SourceLocation LBraceLoc);
  Decl *ActOnFinishExportDecl(Scope *S, Decl *ExportDecl,
                              SourceLocation RBraceLoc);

  /// We've found a use of a templated declaration that would trigger an
  /// implicit instantiation. Check that any relevant explicit specializations
  /// and partial specializations are visible, and diagnose if not.
  void checkSpecializationVisibility(SourceLocation Loc, NamedDecl *Spec);

  /// We've found a use of a template specialization that would select a
  /// partial specialization. Check that the partial specialization is visible,
  /// and diagnose if not.
  void checkPartialSpecializationVisibility(SourceLocation Loc,
                                            NamedDecl *Spec);

  /// Retrieve a suitable printing policy for diagnostics.
  PrintingPolicy getPrintingPolicy() const {
    return getPrintingPolicy(Context, PP);
  }

  /// Retrieve a suitable printing policy for diagnostics.
  static PrintingPolicy getPrintingPolicy(const ASTContext &Ctx,
                                          const Preprocessor &PP);

  /// Scope actions.
  void ActOnPopScope(SourceLocation Loc, Scope *S);
  void ActOnTranslationUnitScope(Scope *S);

  Decl *ParsedFreeStandingDeclSpec(Scope *S, AccessSpecifier AS, DeclSpec &DS,
                                   RecordDecl *&AnonRecord);
  Decl *ParsedFreeStandingDeclSpec(Scope *S, AccessSpecifier AS, DeclSpec &DS,
                                   MultiTemplateParamsArg TemplateParams,
                                   bool IsExplicitInstantiation,
                                   RecordDecl *&AnonRecord);

  Decl *BuildAnonymousStructOrUnion(Scope *S, DeclSpec &DS,
                                    AccessSpecifier AS,
                                    RecordDecl *Record,
                                    const PrintingPolicy &Policy);

  Decl *BuildMicrosoftCAnonymousStruct(Scope *S, DeclSpec &DS,
                                       RecordDecl *Record);

  /// Common ways to introduce type names without a tag for use in diagnostics.
  /// Keep in sync with err_tag_reference_non_tag.
  enum NonTagKind {
    NTK_NonStruct,
    NTK_NonClass,
    NTK_NonUnion,
    NTK_NonEnum,
    NTK_Typedef,
    NTK_TypeAlias,
    NTK_Template,
    NTK_TypeAliasTemplate,
    NTK_TemplateTemplateArgument,
  };

  /// Given a non-tag type declaration, returns an enum useful for indicating
  /// what kind of non-tag type this is.
  NonTagKind getNonTagTypeDeclKind(const Decl *D, TagTypeKind TTK);

  bool isAcceptableTagRedeclaration(const TagDecl *Previous,
                                    TagTypeKind NewTag, bool isDefinition,
                                    SourceLocation NewTagLoc,
                                    const IdentifierInfo *Name);

  enum TagUseKind {
    TUK_Reference,   // Reference to a tag:  'struct foo *X;'
    TUK_Declaration, // Fwd decl of a tag:   'struct foo;'
    TUK_Definition,  // Definition of a tag: 'struct foo { int X; } Y;'
    TUK_Friend       // Friend declaration:  'friend struct foo;'
  };

  Decl *ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK,
                 SourceLocation KWLoc, CXXScopeSpec &SS, IdentifierInfo *Name,
                 SourceLocation NameLoc, const ParsedAttributesView &Attr,
                 AccessSpecifier AS, SourceLocation ModulePrivateLoc,
                 MultiTemplateParamsArg TemplateParameterLists, bool &OwnedDecl,
                 bool &IsDependent, SourceLocation ScopedEnumKWLoc,
                 bool ScopedEnumUsesClassTag, TypeResult UnderlyingType,
                 bool IsTypeSpecifier, bool IsTemplateParamOrArg,
                 SkipBodyInfo *SkipBody = nullptr);

  Decl *ActOnTemplatedFriendTag(Scope *S, SourceLocation FriendLoc,
                                unsigned TagSpec, SourceLocation TagLoc,
                                CXXScopeSpec &SS, IdentifierInfo *Name,
                                SourceLocation NameLoc,
                                const ParsedAttributesView &Attr,
                                MultiTemplateParamsArg TempParamLists);

  TypeResult ActOnDependentTag(Scope *S,
                               unsigned TagSpec,
                               TagUseKind TUK,
                               const CXXScopeSpec &SS,
                               IdentifierInfo *Name,
                               SourceLocation TagLoc,
                               SourceLocation NameLoc);

  void ActOnDefs(Scope *S, Decl *TagD, SourceLocation DeclStart,
                 IdentifierInfo *ClassName,
                 SmallVectorImpl<Decl *> &Decls);
  Decl *ActOnField(Scope *S, Decl *TagD, SourceLocation DeclStart,
                   Declarator &D, Expr *BitfieldWidth);

  FieldDecl *HandleField(Scope *S, RecordDecl *TagD, SourceLocation DeclStart,
                         Declarator &D, Expr *BitfieldWidth,
                         InClassInitStyle InitStyle,
                         AccessSpecifier AS);
  MSPropertyDecl *HandleMSProperty(Scope *S, RecordDecl *TagD,
                                   SourceLocation DeclStart, Declarator &D,
                                   Expr *BitfieldWidth,
                                   InClassInitStyle InitStyle,
                                   AccessSpecifier AS,
                                   const ParsedAttr &MSPropertyAttr);

  FieldDecl *CheckFieldDecl(DeclarationName Name, QualType T,
                            TypeSourceInfo *TInfo,
                            RecordDecl *Record, SourceLocation Loc,
                            bool Mutable, Expr *BitfieldWidth,
                            InClassInitStyle InitStyle,
                            SourceLocation TSSL,
                            AccessSpecifier AS, NamedDecl *PrevDecl,
                            Declarator *D = nullptr);

  bool CheckNontrivialField(FieldDecl *FD);
  void DiagnoseNontrivial(const CXXRecordDecl *Record, CXXSpecialMember CSM);

  enum TrivialABIHandling {
    /// The triviality of a method unaffected by "trivial_abi".
    TAH_IgnoreTrivialABI,

    /// The triviality of a method affected by "trivial_abi".
    TAH_ConsiderTrivialABI
  };

  bool SpecialMemberIsTrivial(CXXMethodDecl *MD, CXXSpecialMember CSM,
                              TrivialABIHandling TAH = TAH_IgnoreTrivialABI,
                              bool Diagnose = false);

  /// For a defaulted function, the kind of defaulted function that it is.
  class DefaultedFunctionKind {
    CXXSpecialMember SpecialMember : 8;
    DefaultedComparisonKind Comparison : 8;

  public:
    DefaultedFunctionKind()
        : SpecialMember(CXXInvalid), Comparison(DefaultedComparisonKind::None) {
    }
    DefaultedFunctionKind(CXXSpecialMember CSM)
        : SpecialMember(CSM), Comparison(DefaultedComparisonKind::None) {}
    DefaultedFunctionKind(DefaultedComparisonKind Comp)
        : SpecialMember(CXXInvalid), Comparison(Comp) {}

    bool isSpecialMember() const { return SpecialMember != CXXInvalid; }
    bool isComparison() const {
      return Comparison != DefaultedComparisonKind::None;
    }

    explicit operator bool() const {
      return isSpecialMember() || isComparison()1.10k;
    }

    CXXSpecialMember asSpecialMember() const { return SpecialMember; }
    DefaultedComparisonKind asComparison() const { return Comparison; }

    /// Get the index of this function kind for use in diagnostics.
    unsigned getDiagnosticIndex() const {
      static_assert(CXXInvalid > CXXDestructor,
                    "invalid should have highest index");
      static_assert((unsigned)DefaultedComparisonKind::None == 0,
                    "none should be equal to zero");
      return SpecialMember + (unsigned)Comparison;
    }
  };

  DefaultedFunctionKind getDefaultedFunctionKind(const FunctionDecl *FD);

  CXXSpecialMember getSpecialMember(const CXXMethodDecl *MD) {
    return getDefaultedFunctionKind(MD).asSpecialMember();
  }
  DefaultedComparisonKind getDefaultedComparisonKind(const FunctionDecl *FD) {
    return getDefaultedFunctionKind(FD).asComparison();
  }

  void ActOnLastBitfield(SourceLocation DeclStart,
                         SmallVectorImpl<Decl *> &AllIvarDecls);
  Decl *ActOnIvar(Scope *S, SourceLocation DeclStart,
                  Declarator &D, Expr *BitfieldWidth,
                  tok::ObjCKeywordKind visibility);

  // This is used for both record definitions and ObjC interface declarations.
  void ActOnFields(Scope *S, SourceLocation RecLoc, Decl *TagDecl,
                   ArrayRef<Decl *> Fields, SourceLocation LBrac,
                   SourceLocation RBrac, const ParsedAttributesView &AttrList);

  /// ActOnTagStartDefinition - Invoked when we have entered the
  /// scope of a tag's definition (e.g., for an enumeration, class,
  /// struct, or union).
  void ActOnTagStartDefinition(Scope *S, Decl *TagDecl);

  /// Perform ODR-like check for C/ObjC when merging tag types from modules.
  /// Differently from C++, actually parse the body and reject / error out
  /// in case of a structural mismatch.
  bool ActOnDuplicateDefinition(DeclSpec &DS, Decl *Prev,
                                SkipBodyInfo &SkipBody);

  typedef void *SkippedDefinitionContext;

  /// Invoked when we enter a tag definition that we're skipping.
  SkippedDefinitionContext ActOnTagStartSkippedDefinition(Scope *S, Decl *TD);

  Decl *ActOnObjCContainerStartDefinition(Decl *IDecl);

  /// ActOnStartCXXMemberDeclarations - Invoked when we have parsed a
  /// C++ record definition's base-specifiers clause and are starting its
  /// member declarations.
  void ActOnStartCXXMemberDeclarations(Scope *S, Decl *TagDecl,
                                       SourceLocation FinalLoc,
                                       bool IsFinalSpelledSealed,
                                       SourceLocation LBraceLoc);

  /// ActOnTagFinishDefinition - Invoked once we have finished parsing
  /// the definition of a tag (enumeration, class, struct, or union).
  void ActOnTagFinishDefinition(Scope *S, Decl *TagDecl,
                                SourceRange BraceRange);

  void ActOnTagFinishSkippedDefinition(SkippedDefinitionContext Context);

  void ActOnObjCContainerFinishDefinition();

  /// Invoked when we must temporarily exit the objective-c container
  /// scope for parsing/looking-up C constructs.
  ///
  /// Must be followed by a call to \see ActOnObjCReenterContainerContext
  void ActOnObjCTemporaryExitContainerContext(DeclContext *DC);
  void ActOnObjCReenterContainerContext(DeclContext *DC);

  /// ActOnTagDefinitionError - Invoked when there was an unrecoverable
  /// error parsing the definition of a tag.
  void ActOnTagDefinitionError(Scope *S, Decl *TagDecl);

  EnumConstantDecl *CheckEnumConstant(EnumDecl *Enum,
                                      EnumConstantDecl *LastEnumConst,
                                      SourceLocation IdLoc,


Coverage Report

Created: 2020-09-22 08:39