/build/source/clang/lib/Sema/SemaDecl.cpp

Bug Summary

File:	build/source/clang/lib/Sema/SemaDecl.cpp
Warning:	line 4185, column 44 Called C++ object pointer is null
Annotated Source Code

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name SemaDecl.cpp -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mframe-pointer=none -relaxed-aliasing -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -ffunction-sections -fdata-sections -fcoverage-compilation-dir=/build/source/build-llvm -resource-dir /usr/lib/llvm-17/lib/clang/17 -D _DEBUG -D _GLIBCXX_ASSERTIONS -D _GNU_SOURCE -D _LIBCPP_ENABLE_ASSERTIONS -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I tools/clang/lib/Sema -I /build/source/clang/lib/Sema -I /build/source/clang/include -I tools/clang/include -I include -I /build/source/llvm/include -D _FORTIFY_SOURCE=2 -D NDEBUG -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/x86_64-linux-gnu/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward -internal-isystem /usr/lib/llvm-17/lib/clang/17/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fmacro-prefix-map=/build/source/build-llvm=build-llvm -fmacro-prefix-map=/build/source/= -fcoverage-prefix-map=/build/source/build-llvm=build-llvm -fcoverage-prefix-map=/build/source/= -source-date-epoch 1680127704 -O3 -Wno-unused-command-line-argument -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wno-comment -Wno-misleading-indentation -std=c++17 -fdeprecated-macro -fdebug-compilation-dir=/build/source/build-llvm -fdebug-prefix-map=/build/source/build-llvm=build-llvm -fdebug-prefix-map=/build/source/= -fdebug-prefix-map=/build/source/build-llvm=build-llvm -fdebug-prefix-map=/build/source/= -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -fcolor-diagnostics -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/scan-build-2023-03-30-003104-16399-1 -x c++ /build/source/clang/lib/Sema/SemaDecl.cpp
1//===--- SemaDecl.cpp - Semantic Analysis for Declarations ----------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9//  This file implements semantic analysis for declarations.
10//
11//===----------------------------------------------------------------------===//

13#include "TypeLocBuilder.h"
14#include "clang/AST/ASTConsumer.h"
15#include "clang/AST/ASTContext.h"
16#include "clang/AST/ASTLambda.h"
17#include "clang/AST/CXXInheritance.h"
18#include "clang/AST/CharUnits.h"
19#include "clang/AST/CommentDiagnostic.h"
20#include "clang/AST/DeclCXX.h"
21#include "clang/AST/DeclObjC.h"
22#include "clang/AST/DeclTemplate.h"
23#include "clang/AST/EvaluatedExprVisitor.h"
24#include "clang/AST/Expr.h"
25#include "clang/AST/ExprCXX.h"
26#include "clang/AST/NonTrivialTypeVisitor.h"
27#include "clang/AST/Randstruct.h"
28#include "clang/AST/StmtCXX.h"
29#include "clang/Basic/Builtins.h"
30#include "clang/Basic/HLSLRuntime.h"
31#include "clang/Basic/PartialDiagnostic.h"
32#include "clang/Basic/SourceManager.h"
33#include "clang/Basic/TargetInfo.h"
34#include "clang/Lex/HeaderSearch.h" // TODO: Sema shouldn't depend on Lex
35#include "clang/Lex/Lexer.h" // TODO: Extract static functions to fix layering.
36#include "clang/Lex/ModuleLoader.h" // TODO: Sema shouldn't depend on Lex
37#include "clang/Lex/Preprocessor.h" // Included for isCodeCompletionEnabled()
38#include "clang/Sema/CXXFieldCollector.h"
39#include "clang/Sema/DeclSpec.h"
40#include "clang/Sema/DelayedDiagnostic.h"
41#include "clang/Sema/Initialization.h"
42#include "clang/Sema/Lookup.h"
43#include "clang/Sema/ParsedTemplate.h"
44#include "clang/Sema/Scope.h"
45#include "clang/Sema/ScopeInfo.h"
46#include "clang/Sema/SemaInternal.h"
47#include "clang/Sema/Template.h"
48#include "llvm/ADT/SmallString.h"
49#include "llvm/TargetParser/Triple.h"
50#include <algorithm>
51#include <cstring>
52#include <functional>
53#include <optional>
54#include <unordered_map>

56using namespace clang;
57using namespace sema;

59Sema::DeclGroupPtrTy Sema::ConvertDeclToDeclGroup(Decl *Ptr, Decl *OwnedType) {
if (OwnedType) {
  Decl *Group[2] = { OwnedType, Ptr };
  return DeclGroupPtrTy::make(DeclGroupRef::Create(Context, Group, 2));
}

return DeclGroupPtrTy::make(DeclGroupRef(Ptr));
66}

68namespace {

70class TypeNameValidatorCCC final : public CorrectionCandidateCallback {
public:
 TypeNameValidatorCCC(bool AllowInvalid, bool WantClass = false,
                      bool AllowTemplates = false,
                      bool AllowNonTemplates = true)
     : AllowInvalidDecl(AllowInvalid), WantClassName(WantClass),
       AllowTemplates(AllowTemplates), AllowNonTemplates(AllowNonTemplates) {
   WantExpressionKeywords = false;
   WantCXXNamedCasts = false;
   WantRemainingKeywords = false;
}

bool ValidateCandidate(const TypoCorrection &candidate) override {
  if (NamedDecl *ND = candidate.getCorrectionDecl()) {
    if (!AllowInvalidDecl && ND->isInvalidDecl())
      return false;

    if (getAsTypeTemplateDecl(ND))
      return AllowTemplates;

    bool IsType = isa<TypeDecl>(ND) || isa<ObjCInterfaceDecl>(ND);
    if (!IsType)
      return false;

    if (AllowNonTemplates)
      return true;

    // An injected-class-name of a class template (specialization) is valid
    // as a template or as a non-template.
    if (AllowTemplates) {
      auto *RD = dyn_cast<CXXRecordDecl>(ND);
      if (!RD || !RD->isInjectedClassName())
        return false;
      RD = cast<CXXRecordDecl>(RD->getDeclContext());
      return RD->getDescribedClassTemplate() ||
             isa<ClassTemplateSpecializationDecl>(RD);
    }

    return false;
  }

  return !WantClassName && candidate.isKeyword();
}

std::unique_ptr<CorrectionCandidateCallback> clone() override {
  return std::make_unique<TypeNameValidatorCCC>(*this);
}

private:
bool AllowInvalidDecl;
bool WantClassName;
bool AllowTemplates;
bool AllowNonTemplates;
123};

125} // end anonymous namespace

127/// Determine whether the token kind starts a simple-type-specifier.
128bool Sema::isSimpleTypeSpecifier(tok::TokenKind Kind) const {
switch (Kind) {
// FIXME: Take into account the current language when deciding whether a
// token kind is a valid type specifier
case tok::kw_short:
case tok::kw_long:
case tok::kw___int64:
case tok::kw___int128:
case tok::kw_signed:
case tok::kw_unsigned:
case tok::kw_void:
case tok::kw_char:
case tok::kw_int:
case tok::kw_half:
case tok::kw_float:
case tok::kw_double:
case tok::kw___bf16:
case tok::kw__Float16:
case tok::kw___float128:
case tok::kw___ibm128:
case tok::kw_wchar_t:
case tok::kw_bool:
150#define TRANSFORM_TYPE_TRAIT_DEF(_, Trait) case tok::kw___##Trait:
151#include "clang/Basic/TransformTypeTraits.def"
case tok::kw___auto_type:
  return true;

case tok::annot_typename:
case tok::kw_char16_t:
case tok::kw_char32_t:
case tok::kw_typeof:
case tok::annot_decltype:
case tok::kw_decltype:
  return getLangOpts().CPlusPlus;

case tok::kw_char8_t:
  return getLangOpts().Char8;

default:
  break;
}

return false;
171}

173namespace {
174enum class UnqualifiedTypeNameLookupResult {
NotFound,
FoundNonType,
FoundType
178};
179} // end anonymous namespace

181/// Tries to perform unqualified lookup of the type decls in bases for
182/// dependent class.
183/// \return \a NotFound if no any decls is found, \a FoundNotType if found not a
184/// type decl, \a FoundType if only type decls are found.
185static UnqualifiedTypeNameLookupResult
186lookupUnqualifiedTypeNameInBase(Sema &S, const IdentifierInfo &II,
                              SourceLocation NameLoc,
                              const CXXRecordDecl *RD) {
if (!RD->hasDefinition())
  return UnqualifiedTypeNameLookupResult::NotFound;
// Look for type decls in base classes.
UnqualifiedTypeNameLookupResult FoundTypeDecl =
    UnqualifiedTypeNameLookupResult::NotFound;
for (const auto &Base : RD->bases()) {
  const CXXRecordDecl *BaseRD = nullptr;
  if (auto *BaseTT = Base.getType()->getAs<TagType>())
    BaseRD = BaseTT->getAsCXXRecordDecl();
  else if (auto *TST = Base.getType()->getAs<TemplateSpecializationType>()) {
    // Look for type decls in dependent base classes that have known primary
    // templates.
    if (!TST || !TST->isDependentType())
      continue;
    auto *TD = TST->getTemplateName().getAsTemplateDecl();
    if (!TD)
      continue;
    if (auto *BasePrimaryTemplate =
        dyn_cast_or_null<CXXRecordDecl>(TD->getTemplatedDecl())) {
      if (BasePrimaryTemplate->getCanonicalDecl() != RD->getCanonicalDecl())
        BaseRD = BasePrimaryTemplate;
      else if (auto *CTD = dyn_cast<ClassTemplateDecl>(TD)) {
        if (const ClassTemplatePartialSpecializationDecl *PS =
                CTD->findPartialSpecialization(Base.getType()))
          if (PS->getCanonicalDecl() != RD->getCanonicalDecl())
            BaseRD = PS;
      }
    }
  }
  if (BaseRD) {
    for (NamedDecl *ND : BaseRD->lookup(&II)) {
      if (!isa<TypeDecl>(ND))
        return UnqualifiedTypeNameLookupResult::FoundNonType;
      FoundTypeDecl = UnqualifiedTypeNameLookupResult::FoundType;
    }
    if (FoundTypeDecl == UnqualifiedTypeNameLookupResult::NotFound) {
      switch (lookupUnqualifiedTypeNameInBase(S, II, NameLoc, BaseRD)) {
      case UnqualifiedTypeNameLookupResult::FoundNonType:
        return UnqualifiedTypeNameLookupResult::FoundNonType;
      case UnqualifiedTypeNameLookupResult::FoundType:
        FoundTypeDecl = UnqualifiedTypeNameLookupResult::FoundType;
        break;
      case UnqualifiedTypeNameLookupResult::NotFound:
        break;
      }
    }
  }
}

return FoundTypeDecl;
239}

241static ParsedType recoverFromTypeInKnownDependentBase(Sema &S,
                                                    const IdentifierInfo &II,
                                                    SourceLocation NameLoc) {
// Lookup in the parent class template context, if any.
const CXXRecordDecl *RD = nullptr;
UnqualifiedTypeNameLookupResult FoundTypeDecl =
    UnqualifiedTypeNameLookupResult::NotFound;
for (DeclContext *DC = S.CurContext;
     DC && FoundTypeDecl == UnqualifiedTypeNameLookupResult::NotFound;
     DC = DC->getParent()) {
  // Look for type decls in dependent base classes that have known primary
  // templates.
  RD = dyn_cast<CXXRecordDecl>(DC);
  if (RD && RD->getDescribedClassTemplate())
    FoundTypeDecl = lookupUnqualifiedTypeNameInBase(S, II, NameLoc, RD);
}
if (FoundTypeDecl != UnqualifiedTypeNameLookupResult::FoundType)
  return nullptr;

// We found some types in dependent base classes.  Recover as if the user
// wrote 'typename MyClass::II' instead of 'II'.  We'll fully resolve the
// lookup during template instantiation.
S.Diag(NameLoc, diag::ext_found_in_dependent_base) << &II;

ASTContext &Context = S.Context;
auto *NNS = NestedNameSpecifier::Create(Context, nullptr, false,
                                        cast<Type>(Context.getRecordType(RD)));
QualType T = Context.getDependentNameType(ETK_Typename, NNS, &II);

CXXScopeSpec SS;
SS.MakeTrivial(Context, NNS, SourceRange(NameLoc));

TypeLocBuilder Builder;
DependentNameTypeLoc DepTL = Builder.push<DependentNameTypeLoc>(T);
DepTL.setNameLoc(NameLoc);
DepTL.setElaboratedKeywordLoc(SourceLocation());
DepTL.setQualifierLoc(SS.getWithLocInContext(Context));
return S.CreateParsedType(T, Builder.getTypeSourceInfo(Context, T));
279}

281/// Build a ParsedType for a simple-type-specifier with a nested-name-specifier.
282static ParsedType buildNamedType(Sema &S, const CXXScopeSpec *SS, QualType T,
                               SourceLocation NameLoc,
                               bool WantNontrivialTypeSourceInfo = true) {
switch (T->getTypeClass()) {
case Type::DeducedTemplateSpecialization:
case Type::Enum:
case Type::InjectedClassName:
case Type::Record:
case Type::Typedef:
case Type::UnresolvedUsing:
case Type::Using:
  break;
// These can never be qualified so an ElaboratedType node
// would carry no additional meaning.
case Type::ObjCInterface:
case Type::ObjCTypeParam:
case Type::TemplateTypeParm:
  return ParsedType::make(T);
default:
  llvm_unreachable("Unexpected Type Class")::llvm::llvm_unreachable_internal("Unexpected Type Class", "clang/lib/Sema/SemaDecl.cpp"
, 301);
}

if (!SS || SS->isEmpty())
  return ParsedType::make(
      S.Context.getElaboratedType(ETK_None, nullptr, T, nullptr));

QualType ElTy = S.getElaboratedType(ETK_None, *SS, T);
if (!WantNontrivialTypeSourceInfo)
  return ParsedType::make(ElTy);

TypeLocBuilder Builder;
Builder.pushTypeSpec(T).setNameLoc(NameLoc);
ElaboratedTypeLoc ElabTL = Builder.push<ElaboratedTypeLoc>(ElTy);
ElabTL.setElaboratedKeywordLoc(SourceLocation());
ElabTL.setQualifierLoc(SS->getWithLocInContext(S.Context));
return S.CreateParsedType(ElTy, Builder.getTypeSourceInfo(S.Context, ElTy));
318}

320/// If the identifier refers to a type name within this scope,
321/// return the declaration of that type.
322///
323/// This routine performs ordinary name lookup of the identifier II
324/// within the given scope, with optional C++ scope specifier SS, to
325/// determine whether the name refers to a type. If so, returns an
326/// opaque pointer (actually a QualType) corresponding to that
327/// type. Otherwise, returns NULL.
328ParsedType Sema::getTypeName(const IdentifierInfo &II, SourceLocation NameLoc,
                           Scope *S, CXXScopeSpec *SS, bool isClassName,
                           bool HasTrailingDot, ParsedType ObjectTypePtr,
                           bool IsCtorOrDtorName,
                           bool WantNontrivialTypeSourceInfo,
                           bool IsClassTemplateDeductionContext,
                           ImplicitTypenameContext AllowImplicitTypename,
                           IdentifierInfo **CorrectedII) {
// FIXME: Consider allowing this outside C++1z mode as an extension.
bool AllowDeducedTemplate = IsClassTemplateDeductionContext &&
                            getLangOpts().CPlusPlus17 && !IsCtorOrDtorName &&
                            !isClassName && !HasTrailingDot;

// Determine where we will perform name lookup.
DeclContext *LookupCtx = nullptr;
if (ObjectTypePtr) {
  QualType ObjectType = ObjectTypePtr.get();
  if (ObjectType->isRecordType())
    LookupCtx = computeDeclContext(ObjectType);
} else if (SS && SS->isNotEmpty()) {
  LookupCtx = computeDeclContext(*SS, false);

  if (!LookupCtx) {
    if (isDependentScopeSpecifier(*SS)) {
      // C++ [temp.res]p3:
      //   A qualified-id that refers to a type and in which the
      //   nested-name-specifier depends on a template-parameter (14.6.2)
      //   shall be prefixed by the keyword typename to indicate that the
      //   qualified-id denotes a type, forming an
      //   elaborated-type-specifier (7.1.5.3).
      //
      // We therefore do not perform any name lookup if the result would
      // refer to a member of an unknown specialization.
      // In C++2a, in several contexts a 'typename' is not required. Also
      // allow this as an extension.
      if (AllowImplicitTypename == ImplicitTypenameContext::No &&
          !isClassName && !IsCtorOrDtorName)
        return nullptr;
      bool IsImplicitTypename = !isClassName && !IsCtorOrDtorName;
      if (IsImplicitTypename) {
        SourceLocation QualifiedLoc = SS->getRange().getBegin();
        if (getLangOpts().CPlusPlus20)
          Diag(QualifiedLoc, diag::warn_cxx17_compat_implicit_typename);
        else
          Diag(QualifiedLoc, diag::ext_implicit_typename)
              << SS->getScopeRep() << II.getName()
              << FixItHint::CreateInsertion(QualifiedLoc, "typename ");
      }

      // We know from the grammar that this name refers to a type,
      // so build a dependent node to describe the type.
      if (WantNontrivialTypeSourceInfo)
        return ActOnTypenameType(S, SourceLocation(), *SS, II, NameLoc,
                                 (ImplicitTypenameContext)IsImplicitTypename)
            .get();

      NestedNameSpecifierLoc QualifierLoc = SS->getWithLocInContext(Context);
      QualType T =
          CheckTypenameType(IsImplicitTypename ? ETK_Typename : ETK_None,
                            SourceLocation(), QualifierLoc, II, NameLoc);
      return ParsedType::make(T);
    }

    return nullptr;
  }

  if (!LookupCtx->isDependentContext() &&
      RequireCompleteDeclContext(*SS, LookupCtx))
    return nullptr;
}

// FIXME: LookupNestedNameSpecifierName isn't the right kind of
// lookup for class-names.
LookupNameKind Kind = isClassName ? LookupNestedNameSpecifierName :
                                    LookupOrdinaryName;
LookupResult Result(*this, &II, NameLoc, Kind);
if (LookupCtx) {
  // Perform "qualified" name lookup into the declaration context we
  // computed, which is either the type of the base of a member access
  // expression or the declaration context associated with a prior
  // nested-name-specifier.
  LookupQualifiedName(Result, LookupCtx);

  if (ObjectTypePtr && Result.empty()) {
    // C++ [basic.lookup.classref]p3:
    //   If the unqualified-id is ~type-name, the type-name is looked up
    //   in the context of the entire postfix-expression. If the type T of
    //   the object expression is of a class type C, the type-name is also
    //   looked up in the scope of class C. At least one of the lookups shall
    //   find a name that refers to (possibly cv-qualified) T.
    LookupName(Result, S);
  }
} else {
  // Perform unqualified name lookup.
  LookupName(Result, S);

  // For unqualified lookup in a class template in MSVC mode, look into
  // dependent base classes where the primary class template is known.
  if (Result.empty() && getLangOpts().MSVCCompat && (!SS || SS->isEmpty())) {
    if (ParsedType TypeInBase =
            recoverFromTypeInKnownDependentBase(*this, II, NameLoc))
      return TypeInBase;
  }
}

NamedDecl *IIDecl = nullptr;
UsingShadowDecl *FoundUsingShadow = nullptr;
switch (Result.getResultKind()) {
case LookupResult::NotFound:
case LookupResult::NotFoundInCurrentInstantiation:
  if (CorrectedII) {
    TypeNameValidatorCCC CCC(/*AllowInvalid=*/true, isClassName,
                             AllowDeducedTemplate);
    TypoCorrection Correction = CorrectTypo(Result.getLookupNameInfo(), Kind,
                                            S, SS, CCC, CTK_ErrorRecovery);
    IdentifierInfo *NewII = Correction.getCorrectionAsIdentifierInfo();
    TemplateTy Template;
    bool MemberOfUnknownSpecialization;
    UnqualifiedId TemplateName;
    TemplateName.setIdentifier(NewII, NameLoc);
    NestedNameSpecifier *NNS = Correction.getCorrectionSpecifier();
    CXXScopeSpec NewSS, *NewSSPtr = SS;
    if (SS && NNS) {
      NewSS.MakeTrivial(Context, NNS, SourceRange(NameLoc));
      NewSSPtr = &NewSS;
    }
    if (Correction && (NNS || NewII != &II) &&
        // Ignore a correction to a template type as the to-be-corrected
        // identifier is not a template (typo correction for template names
        // is handled elsewhere).
        !(getLangOpts().CPlusPlus && NewSSPtr &&
          isTemplateName(S, *NewSSPtr, false, TemplateName, nullptr, false,
                         Template, MemberOfUnknownSpecialization))) {
      ParsedType Ty = getTypeName(*NewII, NameLoc, S, NewSSPtr,
                                  isClassName, HasTrailingDot, ObjectTypePtr,
                                  IsCtorOrDtorName,
                                  WantNontrivialTypeSourceInfo,
                                  IsClassTemplateDeductionContext);
      if (Ty) {
        diagnoseTypo(Correction,
                     PDiag(diag::err_unknown_type_or_class_name_suggest)
                       << Result.getLookupName() << isClassName);
        if (SS && NNS)
          SS->MakeTrivial(Context, NNS, SourceRange(NameLoc));
        *CorrectedII = NewII;
        return Ty;
      }
    }
  }
  // If typo correction failed or was not performed, fall through
  [[fallthrough]];
case LookupResult::FoundOverloaded:
case LookupResult::FoundUnresolvedValue:
  Result.suppressDiagnostics();
  return nullptr;

case LookupResult::Ambiguous:
  // Recover from type-hiding ambiguities by hiding the type.  We'll
  // do the lookup again when looking for an object, and we can
  // diagnose the error then.  If we don't do this, then the error
  // about hiding the type will be immediately followed by an error
  // that only makes sense if the identifier was treated like a type.
  if (Result.getAmbiguityKind() == LookupResult::AmbiguousTagHiding) {
    Result.suppressDiagnostics();
    return nullptr;
  }

  // Look to see if we have a type anywhere in the list of results.
  for (LookupResult::iterator Res = Result.begin(), ResEnd = Result.end();
       Res != ResEnd; ++Res) {
    NamedDecl *RealRes = (*Res)->getUnderlyingDecl();
    if (isa<TypeDecl, ObjCInterfaceDecl, UnresolvedUsingIfExistsDecl>(
            RealRes) ||
        (AllowDeducedTemplate && getAsTypeTemplateDecl(RealRes))) {
      if (!IIDecl ||
          // Make the selection of the recovery decl deterministic.
          RealRes->getLocation() < IIDecl->getLocation()) {
        IIDecl = RealRes;
        FoundUsingShadow = dyn_cast<UsingShadowDecl>(*Res);
      }
    }
  }

  if (!IIDecl) {
    // None of the entities we found is a type, so there is no way
    // to even assume that the result is a type. In this case, don't
    // complain about the ambiguity. The parser will either try to
    // perform this lookup again (e.g., as an object name), which
    // will produce the ambiguity, or will complain that it expected
    // a type name.
    Result.suppressDiagnostics();
    return nullptr;
  }

  // We found a type within the ambiguous lookup; diagnose the
  // ambiguity and then return that type. This might be the right
  // answer, or it might not be, but it suppresses any attempt to
  // perform the name lookup again.
  break;

case LookupResult::Found:
  IIDecl = Result.getFoundDecl();
  FoundUsingShadow = dyn_cast<UsingShadowDecl>(*Result.begin());
  break;
}

assert(IIDecl && "Didn't find decl")(static_cast <bool> (IIDecl && "Didn't find decl"
) ? void (0) : __assert_fail ("IIDecl && \"Didn't find decl\""
, "clang/lib/Sema/SemaDecl.cpp", 534, __extension__ __PRETTY_FUNCTION__
));

QualType T;
if (TypeDecl *TD = dyn_cast<TypeDecl>(IIDecl)) {
  // C++ [class.qual]p2: A lookup that would find the injected-class-name
  // instead names the constructors of the class, except when naming a class.
  // This is ill-formed when we're not actually forming a ctor or dtor name.
  auto *LookupRD = dyn_cast_or_null<CXXRecordDecl>(LookupCtx);
  auto *FoundRD = dyn_cast<CXXRecordDecl>(TD);
  if (!isClassName && !IsCtorOrDtorName && LookupRD && FoundRD &&
      FoundRD->isInjectedClassName() &&
      declaresSameEntity(LookupRD, cast<Decl>(FoundRD->getParent())))
    Diag(NameLoc, diag::err_out_of_line_qualified_id_type_names_constructor)
        << &II << /*Type*/1;

  DiagnoseUseOfDecl(IIDecl, NameLoc);

  T = Context.getTypeDeclType(TD);
  MarkAnyDeclReferenced(TD->getLocation(), TD, /*OdrUse=*/false);
} else if (ObjCInterfaceDecl *IDecl = dyn_cast<ObjCInterfaceDecl>(IIDecl)) {
  (void)DiagnoseUseOfDecl(IDecl, NameLoc);
  if (!HasTrailingDot)
    T = Context.getObjCInterfaceType(IDecl);
  FoundUsingShadow = nullptr; // FIXME: Target must be a TypeDecl.
} else if (auto *UD = dyn_cast<UnresolvedUsingIfExistsDecl>(IIDecl)) {
  (void)DiagnoseUseOfDecl(UD, NameLoc);
  // Recover with 'int'
  return ParsedType::make(Context.IntTy);
} else if (AllowDeducedTemplate) {
  if (auto *TD = getAsTypeTemplateDecl(IIDecl)) {
    assert(!FoundUsingShadow || FoundUsingShadow->getTargetDecl() == TD)(static_cast <bool> (!FoundUsingShadow || FoundUsingShadow
->getTargetDecl() == TD) ? void (0) : __assert_fail ("!FoundUsingShadow || FoundUsingShadow->getTargetDecl() == TD"
, "clang/lib/Sema/SemaDecl.cpp", 564, __extension__ __PRETTY_FUNCTION__
));
    TemplateName Template =
        FoundUsingShadow ? TemplateName(FoundUsingShadow) : TemplateName(TD);
    T = Context.getDeducedTemplateSpecializationType(Template, QualType(),
                                                     false);
    // Don't wrap in a further UsingType.
    FoundUsingShadow = nullptr;
  }
}

if (T.isNull()) {
  // If it's not plausibly a type, suppress diagnostics.
  Result.suppressDiagnostics();
  return nullptr;
}

if (FoundUsingShadow)
  T = Context.getUsingType(FoundUsingShadow, T);

return buildNamedType(*this, SS, T, NameLoc, WantNontrivialTypeSourceInfo);
584}

586// Builds a fake NNS for the given decl context.
587static NestedNameSpecifier *
588synthesizeCurrentNestedNameSpecifier(ASTContext &Context, DeclContext *DC) {
for (;; DC = DC->getLookupParent()) {
  DC = DC->getPrimaryContext();
  auto *ND = dyn_cast<NamespaceDecl>(DC);
  if (ND && !ND->isInline() && !ND->isAnonymousNamespace())
    return NestedNameSpecifier::Create(Context, nullptr, ND);
  else if (auto *RD = dyn_cast<CXXRecordDecl>(DC))
    return NestedNameSpecifier::Create(Context, nullptr, RD->isTemplateDecl(),
                                       RD->getTypeForDecl());
  else if (isa<TranslationUnitDecl>(DC))
    return NestedNameSpecifier::GlobalSpecifier(Context);
}
llvm_unreachable("something isn't in TU scope?")::llvm::llvm_unreachable_internal("something isn't in TU scope?"
, "clang/lib/Sema/SemaDecl.cpp", 600);
601}

603/// Find the parent class with dependent bases of the innermost enclosing method
604/// context. Do not look for enclosing CXXRecordDecls directly, or we will end
605/// up allowing unqualified dependent type names at class-level, which MSVC
606/// correctly rejects.
607static const CXXRecordDecl *
608findRecordWithDependentBasesOfEnclosingMethod(const DeclContext *DC) {
for (; DC && DC->isDependentContext(); DC = DC->getLookupParent()) {
  DC = DC->getPrimaryContext();
  if (const auto *MD = dyn_cast<CXXMethodDecl>(DC))
    if (MD->getParent()->hasAnyDependentBases())
      return MD->getParent();
}
return nullptr;
616}

618ParsedType Sema::ActOnMSVCUnknownTypeName(const IdentifierInfo &II,
                                        SourceLocation NameLoc,
                                        bool IsTemplateTypeArg) {
assert(getLangOpts().MSVCCompat && "shouldn't be called in non-MSVC mode")(static_cast <bool> (getLangOpts().MSVCCompat &&
 "shouldn't be called in non-MSVC mode") ? void (0) : __assert_fail
 ("getLangOpts().MSVCCompat && \"shouldn't be called in non-MSVC mode\""
, "clang/lib/Sema/SemaDecl.cpp", 621, __extension__ __PRETTY_FUNCTION__
));

NestedNameSpecifier *NNS = nullptr;
if (IsTemplateTypeArg && getCurScope()->isTemplateParamScope()) {
  // If we weren't able to parse a default template argument, delay lookup
  // until instantiation time by making a non-dependent DependentTypeName. We
  // pretend we saw a NestedNameSpecifier referring to the current scope, and
  // lookup is retried.
  // FIXME: This hurts our diagnostic quality, since we get errors like "no
  // type named 'Foo' in 'current_namespace'" when the user didn't write any
  // name specifiers.
  NNS = synthesizeCurrentNestedNameSpecifier(Context, CurContext);
  Diag(NameLoc, diag::ext_ms_delayed_template_argument) << &II;
} else if (const CXXRecordDecl *RD =
               findRecordWithDependentBasesOfEnclosingMethod(CurContext)) {
  // Build a DependentNameType that will perform lookup into RD at
  // instantiation time.
  NNS = NestedNameSpecifier::Create(Context, nullptr, RD->isTemplateDecl(),
                                    RD->getTypeForDecl());

  // Diagnose that this identifier was undeclared, and retry the lookup during
  // template instantiation.
  Diag(NameLoc, diag::ext_undeclared_unqual_id_with_dependent_base) << &II
                                                                    << RD;
} else {
  // This is not a situation that we should recover from.
  return ParsedType();
}

QualType T = Context.getDependentNameType(ETK_None, NNS, &II);

// Build type location information.  We synthesized the qualifier, so we have
// to build a fake NestedNameSpecifierLoc.
NestedNameSpecifierLocBuilder NNSLocBuilder;
NNSLocBuilder.MakeTrivial(Context, NNS, SourceRange(NameLoc));
NestedNameSpecifierLoc QualifierLoc = NNSLocBuilder.getWithLocInContext(Context);

TypeLocBuilder Builder;
DependentNameTypeLoc DepTL = Builder.push<DependentNameTypeLoc>(T);
DepTL.setNameLoc(NameLoc);
DepTL.setElaboratedKeywordLoc(SourceLocation());
DepTL.setQualifierLoc(QualifierLoc);
return CreateParsedType(T, Builder.getTypeSourceInfo(Context, T));
664}

666/// isTagName() - This method is called *for error recovery purposes only*
667/// to determine if the specified name is a valid tag name ("struct foo").  If
668/// so, this returns the TST for the tag corresponding to it (TST_enum,
669/// TST_union, TST_struct, TST_interface, TST_class).  This is used to diagnose
670/// cases in C where the user forgot to specify the tag.
671DeclSpec::TST Sema::isTagName(IdentifierInfo &II, Scope *S) {
// Do a tag name lookup in this scope.
LookupResult R(*this, &II, SourceLocation(), LookupTagName);
LookupName(R, S, false);
R.suppressDiagnostics();
if (R.getResultKind() == LookupResult::Found)
  if (const TagDecl *TD = R.getAsSingle<TagDecl>()) {
    switch (TD->getTagKind()) {
    case TTK_Struct: return DeclSpec::TST_struct;
    case TTK_Interface: return DeclSpec::TST_interface;
    case TTK_Union:  return DeclSpec::TST_union;
    case TTK_Class:  return DeclSpec::TST_class;
    case TTK_Enum:   return DeclSpec::TST_enum;
    }
  }

return DeclSpec::TST_unspecified;
688}

690/// isMicrosoftMissingTypename - In Microsoft mode, within class scope,
691/// if a CXXScopeSpec's type is equal to the type of one of the base classes
692/// then downgrade the missing typename error to a warning.
693/// This is needed for MSVC compatibility; Example:
694/// @code
695/// template<class T> class A {
696/// public:
697///   typedef int TYPE;
698/// };
699/// template<class T> class B : public A<T> {
700/// public:
701///   A<T>::TYPE a; // no typename required because A<T> is a base class.
702/// };
703/// @endcode
704bool Sema::isMicrosoftMissingTypename(const CXXScopeSpec *SS, Scope *S) {
if (CurContext->isRecord()) {
  if (SS->getScopeRep()->getKind() == NestedNameSpecifier::Super)
    return true;

  const Type *Ty = SS->getScopeRep()->getAsType();

  CXXRecordDecl *RD = cast<CXXRecordDecl>(CurContext);
  for (const auto &Base : RD->bases())
    if (Ty && Context.hasSameUnqualifiedType(QualType(Ty, 1), Base.getType()))
      return true;
  return S->isFunctionPrototypeScope();
}
return CurContext->isFunctionOrMethod() || S->isFunctionPrototypeScope();
718}

720void Sema::DiagnoseUnknownTypeName(IdentifierInfo *&II,
                                 SourceLocation IILoc,
                                 Scope *S,
                                 CXXScopeSpec *SS,
                                 ParsedType &SuggestedType,
                                 bool IsTemplateName) {
// Don't report typename errors for editor placeholders.
if (II->isEditorPlaceholder())
  return;
// We don't have anything to suggest (yet).
SuggestedType = nullptr;

// There may have been a typo in the name of the type. Look up typo
// results, in case we have something that we can suggest.
TypeNameValidatorCCC CCC(/*AllowInvalid=*/false, /*WantClass=*/false,
                         /*AllowTemplates=*/IsTemplateName,
                         /*AllowNonTemplates=*/!IsTemplateName);
if (TypoCorrection Corrected =
        CorrectTypo(DeclarationNameInfo(II, IILoc), LookupOrdinaryName, S, SS,
                    CCC, CTK_ErrorRecovery)) {
  // FIXME: Support error recovery for the template-name case.
  bool CanRecover = !IsTemplateName;
  if (Corrected.isKeyword()) {
    // We corrected to a keyword.
    diagnoseTypo(Corrected,
                 PDiag(IsTemplateName ? diag::err_no_template_suggest
                                      : diag::err_unknown_typename_suggest)
                     << II);
    II = Corrected.getCorrectionAsIdentifierInfo();
  } else {
    // We found a similarly-named type or interface; suggest that.
    if (!SS || !SS->isSet()) {
      diagnoseTypo(Corrected,
                   PDiag(IsTemplateName ? diag::err_no_template_suggest
                                        : diag::err_unknown_typename_suggest)
                       << II, CanRecover);
    } else if (DeclContext *DC = computeDeclContext(*SS, false)) {
      std::string CorrectedStr(Corrected.getAsString(getLangOpts()));
      bool DroppedSpecifier = Corrected.WillReplaceSpecifier() &&
                              II->getName().equals(CorrectedStr);
      diagnoseTypo(Corrected,
                   PDiag(IsTemplateName
                             ? diag::err_no_member_template_suggest
                             : diag::err_unknown_nested_typename_suggest)
                       << II << DC << DroppedSpecifier << SS->getRange(),
                   CanRecover);
    } else {
      llvm_unreachable("could not have corrected a typo here")::llvm::llvm_unreachable_internal("could not have corrected a typo here"
, "clang/lib/Sema/SemaDecl.cpp", 767);
    }

    if (!CanRecover)
      return;

    CXXScopeSpec tmpSS;
    if (Corrected.getCorrectionSpecifier())
      tmpSS.MakeTrivial(Context, Corrected.getCorrectionSpecifier(),
                        SourceRange(IILoc));
    // FIXME: Support class template argument deduction here.
    SuggestedType =
        getTypeName(*Corrected.getCorrectionAsIdentifierInfo(), IILoc, S,
                    tmpSS.isSet() ? &tmpSS : SS, false, false, nullptr,
                    /*IsCtorOrDtorName=*/false,
                    /*WantNontrivialTypeSourceInfo=*/true);
  }
  return;
}

if (getLangOpts().CPlusPlus && !IsTemplateName) {
  // See if II is a class template that the user forgot to pass arguments to.
  UnqualifiedId Name;
  Name.setIdentifier(II, IILoc);
  CXXScopeSpec EmptySS;
  TemplateTy TemplateResult;
  bool MemberOfUnknownSpecialization;
  if (isTemplateName(S, SS ? *SS : EmptySS, /*hasTemplateKeyword=*/false,
                     Name, nullptr, true, TemplateResult,
                     MemberOfUnknownSpecialization) == TNK_Type_template) {
    diagnoseMissingTemplateArguments(TemplateResult.get(), IILoc);
    return;
  }
}

// FIXME: Should we move the logic that tries to recover from a missing tag
// (struct, union, enum) from Parser::ParseImplicitInt here, instead?

if (!SS || (!SS->isSet() && !SS->isInvalid()))
  Diag(IILoc, IsTemplateName ? diag::err_no_template
                             : diag::err_unknown_typename)
      << II;
else if (DeclContext *DC = computeDeclContext(*SS, false))
  Diag(IILoc, IsTemplateName ? diag::err_no_member_template
                             : diag::err_typename_nested_not_found)
      << II << DC << SS->getRange();
else if (SS->isValid() && SS->getScopeRep()->containsErrors()) {
  SuggestedType =
      ActOnTypenameType(S, SourceLocation(), *SS, *II, IILoc).get();
} else if (isDependentScopeSpecifier(*SS)) {
  unsigned DiagID = diag::err_typename_missing;
  if (getLangOpts().MSVCCompat && isMicrosoftMissingTypename(SS, S))
    DiagID = diag::ext_typename_missing;

  Diag(SS->getRange().getBegin(), DiagID)
    << SS->getScopeRep() << II->getName()
    << SourceRange(SS->getRange().getBegin(), IILoc)
    << FixItHint::CreateInsertion(SS->getRange().getBegin(), "typename ");
  SuggestedType = ActOnTypenameType(S, SourceLocation(),
                                    *SS, *II, IILoc).get();
} else {
  assert(SS && SS->isInvalid() &&(static_cast <bool> (SS && SS->isInvalid() &&
 "Invalid scope specifier has already been diagnosed") ? void
 (0) : __assert_fail ("SS && SS->isInvalid() && \"Invalid scope specifier has already been diagnosed\""
, "clang/lib/Sema/SemaDecl.cpp", 829, __extension__ __PRETTY_FUNCTION__
))
         "Invalid scope specifier has already been diagnosed")(static_cast <bool> (SS && SS->isInvalid() &&
 "Invalid scope specifier has already been diagnosed") ? void
 (0) : __assert_fail ("SS && SS->isInvalid() && \"Invalid scope specifier has already been diagnosed\""
, "clang/lib/Sema/SemaDecl.cpp", 829, __extension__ __PRETTY_FUNCTION__
));
}
831}

833/// Determine whether the given result set contains either a type name
834/// or
835static bool isResultTypeOrTemplate(LookupResult &R, const Token &NextToken) {
bool CheckTemplate = R.getSema().getLangOpts().CPlusPlus &&
                     NextToken.is(tok::less);

for (LookupResult::iterator I = R.begin(), IEnd = R.end(); I != IEnd; ++I) {
  if (isa<TypeDecl>(*I) || isa<ObjCInterfaceDecl>(*I))
    return true;

  if (CheckTemplate && isa<TemplateDecl>(*I))
    return true;
}

return false;
848}

850static bool isTagTypeWithMissingTag(Sema &SemaRef, LookupResult &Result,
                                  Scope *S, CXXScopeSpec &SS,
                                  IdentifierInfo *&Name,
                                  SourceLocation NameLoc) {
LookupResult R(SemaRef, Name, NameLoc, Sema::LookupTagName);
SemaRef.LookupParsedName(R, S, &SS);
if (TagDecl *Tag = R.getAsSingle<TagDecl>()) {
  StringRef FixItTagName;
  switch (Tag->getTagKind()) {
    case TTK_Class:
      FixItTagName = "class ";
      break;

    case TTK_Enum:
      FixItTagName = "enum ";
      break;

    case TTK_Struct:
      FixItTagName = "struct ";
      break;

    case TTK_Interface:
      FixItTagName = "__interface ";
      break;

    case TTK_Union:
      FixItTagName = "union ";
      break;
  }

  StringRef TagName = FixItTagName.drop_back();
  SemaRef.Diag(NameLoc, diag::err_use_of_tag_name_without_tag)
    << Name << TagName << SemaRef.getLangOpts().CPlusPlus
    << FixItHint::CreateInsertion(NameLoc, FixItTagName);

  for (LookupResult::iterator I = Result.begin(), IEnd = Result.end();
       I != IEnd; ++I)
    SemaRef.Diag((*I)->getLocation(), diag::note_decl_hiding_tag_type)
      << Name << TagName;

  // Replace lookup results with just the tag decl.
  Result.clear(Sema::LookupTagName);
  SemaRef.LookupParsedName(Result, S, &SS);
  return true;
}

return false;
897}

899Sema::NameClassification Sema::ClassifyName(Scope *S, CXXScopeSpec &SS,
                                          IdentifierInfo *&Name,
                                          SourceLocation NameLoc,
                                          const Token &NextToken,
                                          CorrectionCandidateCallback *CCC) {
DeclarationNameInfo NameInfo(Name, NameLoc);
ObjCMethodDecl *CurMethod = getCurMethodDecl();

assert(NextToken.isNot(tok::coloncolon) &&(static_cast <bool> (NextToken.isNot(tok::coloncolon) &&
 "parse nested name specifiers before calling ClassifyName") ?
 void (0) : __assert_fail ("NextToken.isNot(tok::coloncolon) && \"parse nested name specifiers before calling ClassifyName\""
, "clang/lib/Sema/SemaDecl.cpp", 908, __extension__ __PRETTY_FUNCTION__
))
       "parse nested name specifiers before calling ClassifyName")(static_cast <bool> (NextToken.isNot(tok::coloncolon) &&
 "parse nested name specifiers before calling ClassifyName") ?
 void (0) : __assert_fail ("NextToken.isNot(tok::coloncolon) && \"parse nested name specifiers before calling ClassifyName\""
, "clang/lib/Sema/SemaDecl.cpp", 908, __extension__ __PRETTY_FUNCTION__
));
if (getLangOpts().CPlusPlus && SS.isSet() &&
    isCurrentClassName(*Name, S, &SS)) {
  // Per [class.qual]p2, this names the constructors of SS, not the
  // injected-class-name. We don't have a classification for that.
  // There's not much point caching this result, since the parser
  // will reject it later.
  return NameClassification::Unknown();
}

LookupResult Result(*this, Name, NameLoc, LookupOrdinaryName);
LookupParsedName(Result, S, &SS, !CurMethod);

if (SS.isInvalid())
  return NameClassification::Error();

// For unqualified lookup in a class template in MSVC mode, look into
// dependent base classes where the primary class template is known.
if (Result.empty() && SS.isEmpty() && getLangOpts().MSVCCompat) {
  if (ParsedType TypeInBase =
          recoverFromTypeInKnownDependentBase(*this, *Name, NameLoc))
    return TypeInBase;
}

// Perform lookup for Objective-C instance variables (including automatically
// synthesized instance variables), if we're in an Objective-C method.
// FIXME: This lookup really, really needs to be folded in to the normal
// unqualified lookup mechanism.
if (SS.isEmpty() && CurMethod && !isResultTypeOrTemplate(Result, NextToken)) {
  DeclResult Ivar = LookupIvarInObjCMethod(Result, S, Name);
  if (Ivar.isInvalid())
    return NameClassification::Error();
  if (Ivar.isUsable())
    return NameClassification::NonType(cast<NamedDecl>(Ivar.get()));

  // We defer builtin creation until after ivar lookup inside ObjC methods.
  if (Result.empty())
    LookupBuiltin(Result);
}

bool SecondTry = false;
bool IsFilteredTemplateName = false;

951Corrected:
switch (Result.getResultKind()) {
case LookupResult::NotFound:
  // If an unqualified-id is followed by a '(', then we have a function
  // call.
  if (SS.isEmpty() && NextToken.is(tok::l_paren)) {
    // In C++, this is an ADL-only call.
    // FIXME: Reference?
    if (getLangOpts().CPlusPlus)
      return NameClassification::UndeclaredNonType();

    // C90 6.3.2.2:
    //   If the expression that precedes the parenthesized argument list in a
    //   function call consists solely of an identifier, and if no
    //   declaration is visible for this identifier, the identifier is
    //   implicitly declared exactly as if, in the innermost block containing
    //   the function call, the declaration
    //
    //     extern int identifier ();
    //
    //   appeared.
    //
    // We also allow this in C99 as an extension. However, this is not
    // allowed in all language modes as functions without prototypes may not
    // be supported.
    if (getLangOpts().implicitFunctionsAllowed()) {
      if (NamedDecl *D = ImplicitlyDefineFunction(NameLoc, *Name, S))
        return NameClassification::NonType(D);
    }
  }

  if (getLangOpts().CPlusPlus20 && SS.isEmpty() && NextToken.is(tok::less)) {
    // In C++20 onwards, this could be an ADL-only call to a function
    // template, and we're required to assume that this is a template name.
    //
    // FIXME: Find a way to still do typo correction in this case.
    TemplateName Template =
        Context.getAssumedTemplateName(NameInfo.getName());
    return NameClassification::UndeclaredTemplate(Template);
  }

  // In C, we first see whether there is a tag type by the same name, in
  // which case it's likely that the user just forgot to write "enum",
  // "struct", or "union".
  if (!getLangOpts().CPlusPlus && !SecondTry &&
      isTagTypeWithMissingTag(*this, Result, S, SS, Name, NameLoc)) {
    break;
  }

  // Perform typo correction to determine if there is another name that is
  // close to this name.
  if (!SecondTry && CCC) {
    SecondTry = true;
    if (TypoCorrection Corrected =
            CorrectTypo(Result.getLookupNameInfo(), Result.getLookupKind(), S,
                        &SS, *CCC, CTK_ErrorRecovery)) {
      unsigned UnqualifiedDiag = diag::err_undeclared_var_use_suggest;
      unsigned QualifiedDiag = diag::err_no_member_suggest;

      NamedDecl *FirstDecl = Corrected.getFoundDecl();
      NamedDecl *UnderlyingFirstDecl = Corrected.getCorrectionDecl();
      if (getLangOpts().CPlusPlus && NextToken.is(tok::less) &&
          UnderlyingFirstDecl && isa<TemplateDecl>(UnderlyingFirstDecl)) {
        UnqualifiedDiag = diag::err_no_template_suggest;
        QualifiedDiag = diag::err_no_member_template_suggest;
      } else if (UnderlyingFirstDecl &&
                 (isa<TypeDecl>(UnderlyingFirstDecl) ||
                  isa<ObjCInterfaceDecl>(UnderlyingFirstDecl) ||
                  isa<ObjCCompatibleAliasDecl>(UnderlyingFirstDecl))) {
        UnqualifiedDiag = diag::err_unknown_typename_suggest;
        QualifiedDiag = diag::err_unknown_nested_typename_suggest;
      }

      if (SS.isEmpty()) {
        diagnoseTypo(Corrected, PDiag(UnqualifiedDiag) << Name);
      } else {// FIXME: is this even reachable? Test it.
        std::string CorrectedStr(Corrected.getAsString(getLangOpts()));
        bool DroppedSpecifier = Corrected.WillReplaceSpecifier() &&
                                Name->getName().equals(CorrectedStr);
        diagnoseTypo(Corrected, PDiag(QualifiedDiag)
                                  << Name << computeDeclContext(SS, false)
                                  << DroppedSpecifier << SS.getRange());
      }

      // Update the name, so that the caller has the new name.
      Name = Corrected.getCorrectionAsIdentifierInfo();

      // Typo correction corrected to a keyword.
      if (Corrected.isKeyword())
        return Name;

      // Also update the LookupResult...
      // FIXME: This should probably go away at some point
      Result.clear();
      Result.setLookupName(Corrected.getCorrection());
      if (FirstDecl)
        Result.addDecl(FirstDecl);

      // If we found an Objective-C instance variable, let
      // LookupInObjCMethod build the appropriate expression to
      // reference the ivar.
      // FIXME: This is a gross hack.
      if (ObjCIvarDecl *Ivar = Result.getAsSingle<ObjCIvarDecl>()) {
        DeclResult R =
            LookupIvarInObjCMethod(Result, S, Ivar->getIdentifier());
        if (R.isInvalid())
          return NameClassification::Error();
        if (R.isUsable())
          return NameClassification::NonType(Ivar);
      }

      goto Corrected;
    }
  }

  // We failed to correct; just fall through and let the parser deal with it.
  Result.suppressDiagnostics();
  return NameClassification::Unknown();

case LookupResult::NotFoundInCurrentInstantiation: {
  // We performed name lookup into the current instantiation, and there were
  // dependent bases, so we treat this result the same way as any other
  // dependent nested-name-specifier.

  // C++ [temp.res]p2:
  //   A name used in a template declaration or definition and that is
  //   dependent on a template-parameter is assumed not to name a type
  //   unless the applicable name lookup finds a type name or the name is
  //   qualified by the keyword typename.
  //
  // FIXME: If the next token is '<', we might want to ask the parser to
  // perform some heroics to see if we actually have a
  // template-argument-list, which would indicate a missing 'template'
  // keyword here.
  return NameClassification::DependentNonType();
}

case LookupResult::Found:
case LookupResult::FoundOverloaded:
case LookupResult::FoundUnresolvedValue:
  break;

case LookupResult::Ambiguous:
  if (getLangOpts().CPlusPlus && NextToken.is(tok::less) &&
      hasAnyAcceptableTemplateNames(Result, /*AllowFunctionTemplates=*/true,
                                    /*AllowDependent=*/false)) {
    // C++ [temp.local]p3:
    //   A lookup that finds an injected-class-name (10.2) can result in an
    //   ambiguity in certain cases (for example, if it is found in more than
    //   one base class). If all of the injected-class-names that are found
    //   refer to specializations of the same class template, and if the name
    //   is followed by a template-argument-list, the reference refers to the
    //   class template itself and not a specialization thereof, and is not
    //   ambiguous.
    //
    // This filtering can make an ambiguous result into an unambiguous one,
    // so try again after filtering out template names.
    FilterAcceptableTemplateNames(Result);
    if (!Result.isAmbiguous()) {
      IsFilteredTemplateName = true;
      break;
    }
  }

  // Diagnose the ambiguity and return an error.
  return NameClassification::Error();
}

if (getLangOpts().CPlusPlus && NextToken.is(tok::less) &&
    (IsFilteredTemplateName ||
     hasAnyAcceptableTemplateNames(
         Result, /*AllowFunctionTemplates=*/true,
         /*AllowDependent=*/false,
         /*AllowNonTemplateFunctions*/ SS.isEmpty() &&
             getLangOpts().CPlusPlus20))) {
  // C++ [temp.names]p3:
  //   After name lookup (3.4) finds that a name is a template-name or that
  //   an operator-function-id or a literal- operator-id refers to a set of
  //   overloaded functions any member of which is a function template if
  //   this is followed by a <, the < is always taken as the delimiter of a
  //   template-argument-list and never as the less-than operator.
  // C++2a [temp.names]p2:
  //   A name is also considered to refer to a template if it is an
  //   unqualified-id followed by a < and name lookup finds either one
  //   or more functions or finds nothing.
  if (!IsFilteredTemplateName)
    FilterAcceptableTemplateNames(Result);

  bool IsFunctionTemplate;
  bool IsVarTemplate;
  TemplateName Template;
  if (Result.end() - Result.begin() > 1) {
    IsFunctionTemplate = true;
    Template = Context.getOverloadedTemplateName(Result.begin(),
                                                 Result.end());
  } else if (!Result.empty()) {
    auto *TD = cast<TemplateDecl>(getAsTemplateNameDecl(
        *Result.begin(), /*AllowFunctionTemplates=*/true,
        /*AllowDependent=*/false));
    IsFunctionTemplate = isa<FunctionTemplateDecl>(TD);
    IsVarTemplate = isa<VarTemplateDecl>(TD);

    UsingShadowDecl *FoundUsingShadow =
        dyn_cast<UsingShadowDecl>(*Result.begin());
    assert(!FoundUsingShadow ||(static_cast <bool> (!FoundUsingShadow || TD == cast<
TemplateDecl>(FoundUsingShadow->getTargetDecl())) ? void
 (0) : __assert_fail ("!FoundUsingShadow || TD == cast<TemplateDecl>(FoundUsingShadow->getTargetDecl())"
, "clang/lib/Sema/SemaDecl.cpp", 1156, __extension__ __PRETTY_FUNCTION__
))
           TD == cast<TemplateDecl>(FoundUsingShadow->getTargetDecl()))(static_cast <bool> (!FoundUsingShadow || TD == cast<
TemplateDecl>(FoundUsingShadow->getTargetDecl())) ? void
 (0) : __assert_fail ("!FoundUsingShadow || TD == cast<TemplateDecl>(FoundUsingShadow->getTargetDecl())"
, "clang/lib/Sema/SemaDecl.cpp", 1156, __extension__ __PRETTY_FUNCTION__
));
    Template =
        FoundUsingShadow ? TemplateName(FoundUsingShadow) : TemplateName(TD);
    if (SS.isNotEmpty())
      Template = Context.getQualifiedTemplateName(SS.getScopeRep(),
                                                  /*TemplateKeyword=*/false,
                                                  Template);
  } else {
    // All results were non-template functions. This is a function template
    // name.
    IsFunctionTemplate = true;
    Template = Context.getAssumedTemplateName(NameInfo.getName());
  }

  if (IsFunctionTemplate) {
    // Function templates always go through overload resolution, at which
    // point we'll perform the various checks (e.g., accessibility) we need
    // to based on which function we selected.
    Result.suppressDiagnostics();

    return NameClassification::FunctionTemplate(Template);
  }

  return IsVarTemplate ? NameClassification::VarTemplate(Template)
                       : NameClassification::TypeTemplate(Template);
}

auto BuildTypeFor = [&](TypeDecl *Type, NamedDecl *Found) {
  QualType T = Context.getTypeDeclType(Type);
  if (const auto *USD = dyn_cast<UsingShadowDecl>(Found))
    T = Context.getUsingType(USD, T);
  return buildNamedType(*this, &SS, T, NameLoc);
};

NamedDecl *FirstDecl = (*Result.begin())->getUnderlyingDecl();
if (TypeDecl *Type = dyn_cast<TypeDecl>(FirstDecl)) {
  DiagnoseUseOfDecl(Type, NameLoc);
  MarkAnyDeclReferenced(Type->getLocation(), Type, /*OdrUse=*/false);
  return BuildTypeFor(Type, *Result.begin());
}

ObjCInterfaceDecl *Class = dyn_cast<ObjCInterfaceDecl>(FirstDecl);
if (!Class) {
  // FIXME: It's unfortunate that we don't have a Type node for handling this.
  if (ObjCCompatibleAliasDecl *Alias =
          dyn_cast<ObjCCompatibleAliasDecl>(FirstDecl))
    Class = Alias->getClassInterface();
}

if (Class) {
  DiagnoseUseOfDecl(Class, NameLoc);

  if (NextToken.is(tok::period)) {
    // Interface. <something> is parsed as a property reference expression.
    // Just return "unknown" as a fall-through for now.
    Result.suppressDiagnostics();
    return NameClassification::Unknown();
  }

  QualType T = Context.getObjCInterfaceType(Class);
  return ParsedType::make(T);
}

if (isa<ConceptDecl>(FirstDecl))
  return NameClassification::Concept(
      TemplateName(cast<TemplateDecl>(FirstDecl)));

if (auto *EmptyD = dyn_cast<UnresolvedUsingIfExistsDecl>(FirstDecl)) {
  (void)DiagnoseUseOfDecl(EmptyD, NameLoc);
  return NameClassification::Error();
}

// We can have a type template here if we're classifying a template argument.
if (isa<TemplateDecl>(FirstDecl) && !isa<FunctionTemplateDecl>(FirstDecl) &&
    !isa<VarTemplateDecl>(FirstDecl))
  return NameClassification::TypeTemplate(
      TemplateName(cast<TemplateDecl>(FirstDecl)));

// Check for a tag type hidden by a non-type decl in a few cases where it
// seems likely a type is wanted instead of the non-type that was found.
bool NextIsOp = NextToken.isOneOf(tok::amp, tok::star);
if ((NextToken.is(tok::identifier) ||
     (NextIsOp &&
      FirstDecl->getUnderlyingDecl()->isFunctionOrFunctionTemplate())) &&
    isTagTypeWithMissingTag(*this, Result, S, SS, Name, NameLoc)) {
  TypeDecl *Type = Result.getAsSingle<TypeDecl>();
  DiagnoseUseOfDecl(Type, NameLoc);
  return BuildTypeFor(Type, *Result.begin());
}

// If we already know which single declaration is referenced, just annotate
// that declaration directly. Defer resolving even non-overloaded class
// member accesses, as we need to defer certain access checks until we know
// the context.
bool ADL = UseArgumentDependentLookup(SS, Result, NextToken.is(tok::l_paren));
if (Result.isSingleResult() && !ADL &&
    (!FirstDecl->isCXXClassMember() || isa<EnumConstantDecl>(FirstDecl)))
  return NameClassification::NonType(Result.getRepresentativeDecl());

// Otherwise, this is an overload set that we will need to resolve later.
Result.suppressDiagnostics();
return NameClassification::OverloadSet(UnresolvedLookupExpr::Create(
    Context, Result.getNamingClass(), SS.getWithLocInContext(Context),
    Result.getLookupNameInfo(), ADL, Result.isOverloadedResult(),
    Result.begin(), Result.end()));
1261}

1263ExprResult
1264Sema::ActOnNameClassifiedAsUndeclaredNonType(IdentifierInfo *Name,
                                           SourceLocation NameLoc) {
assert(getLangOpts().CPlusPlus && "ADL-only call in C?")(static_cast <bool> (getLangOpts().CPlusPlus &&
 "ADL-only call in C?") ? void (0) : __assert_fail ("getLangOpts().CPlusPlus && \"ADL-only call in C?\""
, "clang/lib/Sema/SemaDecl.cpp", 1266, __extension__ __PRETTY_FUNCTION__
));
CXXScopeSpec SS;
LookupResult Result(*this, Name, NameLoc, LookupOrdinaryName);
return BuildDeclarationNameExpr(SS, Result, /*ADL=*/true);
1270}

1272ExprResult
1273Sema::ActOnNameClassifiedAsDependentNonType(const CXXScopeSpec &SS,
                                          IdentifierInfo *Name,
                                          SourceLocation NameLoc,
                                          bool IsAddressOfOperand) {
DeclarationNameInfo NameInfo(Name, NameLoc);
return ActOnDependentIdExpression(SS, /*TemplateKWLoc=*/SourceLocation(),
                                  NameInfo, IsAddressOfOperand,
                                  /*TemplateArgs=*/nullptr);
1281}

1283ExprResult Sema::ActOnNameClassifiedAsNonType(Scope *S, const CXXScopeSpec &SS,
                                            NamedDecl *Found,
                                            SourceLocation NameLoc,
                                            const Token &NextToken) {
if (getCurMethodDecl() && SS.isEmpty())
  if (auto *Ivar = dyn_cast<ObjCIvarDecl>(Found->getUnderlyingDecl()))
    return BuildIvarRefExpr(S, NameLoc, Ivar);

// Reconstruct the lookup result.
LookupResult Result(*this, Found->getDeclName(), NameLoc, LookupOrdinaryName);
Result.addDecl(Found);
Result.resolveKind();

bool ADL = UseArgumentDependentLookup(SS, Result, NextToken.is(tok::l_paren));
return BuildDeclarationNameExpr(SS, Result, ADL, /*AcceptInvalidDecl=*/true);
1298}

1300ExprResult Sema::ActOnNameClassifiedAsOverloadSet(Scope *S, Expr *E) {
// For an implicit class member access, transform the result into a member
// access expression if necessary.
auto *ULE = cast<UnresolvedLookupExpr>(E);
if ((*ULE->decls_begin())->isCXXClassMember()) {
  CXXScopeSpec SS;
  SS.Adopt(ULE->getQualifierLoc());

  // Reconstruct the lookup result.
  LookupResult Result(*this, ULE->getName(), ULE->getNameLoc(),
                      LookupOrdinaryName);
  Result.setNamingClass(ULE->getNamingClass());
  for (auto I = ULE->decls_begin(), E = ULE->decls_end(); I != E; ++I)
    Result.addDecl(*I, I.getAccess());
  Result.resolveKind();
  return BuildPossibleImplicitMemberExpr(SS, SourceLocation(), Result,
                                         nullptr, S);
}

// Otherwise, this is already in the form we needed, and no further checks
// are necessary.
return ULE;
1322}

1324Sema::TemplateNameKindForDiagnostics
1325Sema::getTemplateNameKindForDiagnostics(TemplateName Name) {
auto *TD = Name.getAsTemplateDecl();
if (!TD)
  return TemplateNameKindForDiagnostics::DependentTemplate;
if (isa<ClassTemplateDecl>(TD))
  return TemplateNameKindForDiagnostics::ClassTemplate;
if (isa<FunctionTemplateDecl>(TD))
  return TemplateNameKindForDiagnostics::FunctionTemplate;
if (isa<VarTemplateDecl>(TD))
  return TemplateNameKindForDiagnostics::VarTemplate;
if (isa<TypeAliasTemplateDecl>(TD))
  return TemplateNameKindForDiagnostics::AliasTemplate;
if (isa<TemplateTemplateParmDecl>(TD))
  return TemplateNameKindForDiagnostics::TemplateTemplateParam;
if (isa<ConceptDecl>(TD))
  return TemplateNameKindForDiagnostics::Concept;
return TemplateNameKindForDiagnostics::DependentTemplate;
1342}

1344void Sema::PushDeclContext(Scope *S, DeclContext *DC) {
assert(DC->getLexicalParent() == CurContext &&(static_cast <bool> (DC->getLexicalParent() == CurContext
 && "The next DeclContext should be lexically contained in the current one."
) ? void (0) : __assert_fail ("DC->getLexicalParent() == CurContext && \"The next DeclContext should be lexically contained in the current one.\""
, "clang/lib/Sema/SemaDecl.cpp", 1346, __extension__ __PRETTY_FUNCTION__
))
    "The next DeclContext should be lexically contained in the current one.")(static_cast <bool> (DC->getLexicalParent() == CurContext
 && "The next DeclContext should be lexically contained in the current one."
) ? void (0) : __assert_fail ("DC->getLexicalParent() == CurContext && \"The next DeclContext should be lexically contained in the current one.\""
, "clang/lib/Sema/SemaDecl.cpp", 1346, __extension__ __PRETTY_FUNCTION__
));
CurContext = DC;
S->setEntity(DC);
1349}

1351void Sema::PopDeclContext() {
assert(CurContext && "DeclContext imbalance!")(static_cast <bool> (CurContext && "DeclContext imbalance!"
) ? void (0) : __assert_fail ("CurContext && \"DeclContext imbalance!\""
, "clang/lib/Sema/SemaDecl.cpp", 1352, __extension__ __PRETTY_FUNCTION__
));

CurContext = CurContext->getLexicalParent();
assert(CurContext && "Popped translation unit!")(static_cast <bool> (CurContext && "Popped translation unit!"
) ? void (0) : __assert_fail ("CurContext && \"Popped translation unit!\""
, "clang/lib/Sema/SemaDecl.cpp", 1355, __extension__ __PRETTY_FUNCTION__
));
1356}

1358Sema::SkippedDefinitionContext Sema::ActOnTagStartSkippedDefinition(Scope *S,
                                                                  Decl *D) {
// Unlike PushDeclContext, the context to which we return is not necessarily
// the containing DC of TD, because the new context will be some pre-existing
// TagDecl definition instead of a fresh one.
auto Result = static_cast<SkippedDefinitionContext>(CurContext);
CurContext = cast<TagDecl>(D)->getDefinition();
assert(CurContext && "skipping definition of undefined tag")(static_cast <bool> (CurContext && "skipping definition of undefined tag"
) ? void (0) : __assert_fail ("CurContext && \"skipping definition of undefined tag\""
, "clang/lib/Sema/SemaDecl.cpp", 1365, __extension__ __PRETTY_FUNCTION__
));
// Start lookups from the parent of the current context; we don't want to look
// into the pre-existing complete definition.
S->setEntity(CurContext->getLookupParent());
return Result;
1370}

1372void Sema::ActOnTagFinishSkippedDefinition(SkippedDefinitionContext Context) {
CurContext = static_cast<decltype(CurContext)>(Context);
1374}

1376/// EnterDeclaratorContext - Used when we must lookup names in the context
1377/// of a declarator's nested name specifier.
1378///
1379void Sema::EnterDeclaratorContext(Scope *S, DeclContext *DC) {
// C++0x [basic.lookup.unqual]p13:
//   A name used in the definition of a static data member of class
//   X (after the qualified-id of the static member) is looked up as
//   if the name was used in a member function of X.
// C++0x [basic.lookup.unqual]p14:
//   If a variable member of a namespace is defined outside of the
//   scope of its namespace then any name used in the definition of
//   the variable member (after the declarator-id) is looked up as
//   if the definition of the variable member occurred in its
//   namespace.
// Both of these imply that we should push a scope whose context
// is the semantic context of the declaration.  We can't use
// PushDeclContext here because that context is not necessarily
// lexically contained in the current context.  Fortunately,
// the containing scope should have the appropriate information.

assert(!S->getEntity() && "scope already has entity")(static_cast <bool> (!S->getEntity() && "scope already has entity"
) ? void (0) : __assert_fail ("!S->getEntity() && \"scope already has entity\""
, "clang/lib/Sema/SemaDecl.cpp", 1396, __extension__ __PRETTY_FUNCTION__
));

1398#ifndef NDEBUG
Scope *Ancestor = S->getParent();
while (!Ancestor->getEntity()) Ancestor = Ancestor->getParent();
assert(Ancestor->getEntity() == CurContext && "ancestor context mismatch")(static_cast <bool> (Ancestor->getEntity() == CurContext
 && "ancestor context mismatch") ? void (0) : __assert_fail
 ("Ancestor->getEntity() == CurContext && \"ancestor context mismatch\""
, "clang/lib/Sema/SemaDecl.cpp", 1401, __extension__ __PRETTY_FUNCTION__
));
1402#endif

CurContext = DC;
S->setEntity(DC);

if (S->getParent()->isTemplateParamScope()) {
  // Also set the corresponding entities for all immediately-enclosing
  // template parameter scopes.
  EnterTemplatedContext(S->getParent(), DC);
}
1412}

1414void Sema::ExitDeclaratorContext(Scope *S) {
assert(S->getEntity() == CurContext && "Context imbalance!")(static_cast <bool> (S->getEntity() == CurContext &&
 "Context imbalance!") ? void (0) : __assert_fail ("S->getEntity() == CurContext && \"Context imbalance!\""
, "clang/lib/Sema/SemaDecl.cpp", 1415, __extension__ __PRETTY_FUNCTION__
));

// Switch back to the lexical context.  The safety of this is
// enforced by an assert in EnterDeclaratorContext.
Scope *Ancestor = S->getParent();
while (!Ancestor->getEntity()) Ancestor = Ancestor->getParent();
CurContext = Ancestor->getEntity();

// We don't need to do anything with the scope, which is going to
// disappear.
1425}

1427void Sema::EnterTemplatedContext(Scope *S, DeclContext *DC) {
assert(S->isTemplateParamScope() &&(static_cast <bool> (S->isTemplateParamScope() &&
 "expected to be initializing a template parameter scope") ? void
 (0) : __assert_fail ("S->isTemplateParamScope() && \"expected to be initializing a template parameter scope\""
, "clang/lib/Sema/SemaDecl.cpp", 1429, __extension__ __PRETTY_FUNCTION__
))
       "expected to be initializing a template parameter scope")(static_cast <bool> (S->isTemplateParamScope() &&
 "expected to be initializing a template parameter scope") ? void
 (0) : __assert_fail ("S->isTemplateParamScope() && \"expected to be initializing a template parameter scope\""
, "clang/lib/Sema/SemaDecl.cpp", 1429, __extension__ __PRETTY_FUNCTION__
));

// C++20 [temp.local]p7:
//   In the definition of a member of a class template that appears outside
//   of the class template definition, the name of a member of the class
//   template hides the name of a template-parameter of any enclosing class
//   templates (but not a template-parameter of the member if the member is a
//   class or function template).
// C++20 [temp.local]p9:
//   In the definition of a class template or in the definition of a member
//   of such a template that appears outside of the template definition, for
//   each non-dependent base class (13.8.2.1), if the name of the base class
//   or the name of a member of the base class is the same as the name of a
//   template-parameter, the base class name or member name hides the
//   template-parameter name (6.4.10).
//
// This means that a template parameter scope should be searched immediately
// after searching the DeclContext for which it is a template parameter
// scope. For example, for
//   template<typename T> template<typename U> template<typename V>
//     void N::A<T>::B<U>::f(...)
// we search V then B<U> (and base classes) then U then A<T> (and base
// classes) then T then N then ::.
unsigned ScopeDepth = getTemplateDepth(S);
for (; S && S->isTemplateParamScope(); S = S->getParent(), --ScopeDepth) {
  DeclContext *SearchDCAfterScope = DC;
  for (; DC; DC = DC->getLookupParent()) {
    if (const TemplateParameterList *TPL =
            cast<Decl>(DC)->getDescribedTemplateParams()) {
      unsigned DCDepth = TPL->getDepth() + 1;
      if (DCDepth > ScopeDepth)
        continue;
      if (ScopeDepth == DCDepth)
        SearchDCAfterScope = DC = DC->getLookupParent();
      break;
    }
  }
  S->setLookupEntity(SearchDCAfterScope);
}
1468}

1470void Sema::ActOnReenterFunctionContext(Scope* S, Decl *D) {
// We assume that the caller has already called
// ActOnReenterTemplateScope so getTemplatedDecl() works.
FunctionDecl *FD = D->getAsFunction();
if (!FD)
  return;

// Same implementation as PushDeclContext, but enters the context
// from the lexical parent, rather than the top-level class.
assert(CurContext == FD->getLexicalParent() &&(static_cast <bool> (CurContext == FD->getLexicalParent
() && "The next DeclContext should be lexically contained in the current one."
) ? void (0) : __assert_fail ("CurContext == FD->getLexicalParent() && \"The next DeclContext should be lexically contained in the current one.\""
, "clang/lib/Sema/SemaDecl.cpp", 1480, __extension__ __PRETTY_FUNCTION__
))
  "The next DeclContext should be lexically contained in the current one.")(static_cast <bool> (CurContext == FD->getLexicalParent
() && "The next DeclContext should be lexically contained in the current one."
) ? void (0) : __assert_fail ("CurContext == FD->getLexicalParent() && \"The next DeclContext should be lexically contained in the current one.\""
, "clang/lib/Sema/SemaDecl.cpp", 1480, __extension__ __PRETTY_FUNCTION__
));
CurContext = FD;
S->setEntity(CurContext);

for (unsigned P = 0, NumParams = FD->getNumParams(); P < NumParams; ++P) {
  ParmVarDecl *Param = FD->getParamDecl(P);
  // If the parameter has an identifier, then add it to the scope
  if (Param->getIdentifier()) {
    S->AddDecl(Param);
    IdResolver.AddDecl(Param);
  }
}
1492}

1494void Sema::ActOnExitFunctionContext() {
// Same implementation as PopDeclContext, but returns to the lexical parent,
// rather than the top-level class.
assert(CurContext && "DeclContext imbalance!")(static_cast <bool> (CurContext && "DeclContext imbalance!"
) ? void (0) : __assert_fail ("CurContext && \"DeclContext imbalance!\""
, "clang/lib/Sema/SemaDecl.cpp", 1497, __extension__ __PRETTY_FUNCTION__
));
CurContext = CurContext->getLexicalParent();
assert(CurContext && "Popped translation unit!")(static_cast <bool> (CurContext && "Popped translation unit!"
) ? void (0) : __assert_fail ("CurContext && \"Popped translation unit!\""
, "clang/lib/Sema/SemaDecl.cpp", 1499, __extension__ __PRETTY_FUNCTION__
));
1500}

1502/// Determine whether overloading is allowed for a new function
1503/// declaration considering prior declarations of the same name.
1504///
1505/// This routine determines whether overloading is possible, not
1506/// whether a new declaration actually overloads a previous one.
1507/// It will return true in C++ (where overloads are alway permitted)
1508/// or, as a C extension, when either the new declaration or a
1509/// previous one is declared with the 'overloadable' attribute.
1510static bool AllowOverloadingOfFunction(const LookupResult &Previous,
                                     ASTContext &Context,
                                     const FunctionDecl *New) {
if (Context.getLangOpts().CPlusPlus || New->hasAttr<OverloadableAttr>())
  return true;

// Multiversion function declarations are not overloads in the
// usual sense of that term, but lookup will report that an
// overload set was found if more than one multiversion function
// declaration is present for the same name. It is therefore
// inadequate to assume that some prior declaration(s) had
// the overloadable attribute; checking is required. Since one
// declaration is permitted to omit the attribute, it is necessary
// to check at least two; hence the 'any_of' check below. Note that
// the overloadable attribute is implicitly added to declarations
// that were required to have it but did not.
if (Previous.getResultKind() == LookupResult::FoundOverloaded) {
  return llvm::any_of(Previous, [](const NamedDecl *ND) {
    return ND->hasAttr<OverloadableAttr>();
  });
} else if (Previous.getResultKind() == LookupResult::Found)
  return Previous.getFoundDecl()->hasAttr<OverloadableAttr>();

return false;
1534}

1536/// Add this decl to the scope shadowed decl chains.
1537void Sema::PushOnScopeChains(NamedDecl *D, Scope *S, bool AddToContext) {
// Move up the scope chain until we find the nearest enclosing
// non-transparent context. The declaration will be introduced into this
// scope.
while (S->getEntity() && S->getEntity()->isTransparentContext())
  S = S->getParent();

// Add scoped declarations into their context, so that they can be
// found later. Declarations without a context won't be inserted
// into any context.
if (AddToContext)
  CurContext->addDecl(D);

// Out-of-line definitions shouldn't be pushed into scope in C++, unless they
// are function-local declarations.
if (getLangOpts().CPlusPlus && D->isOutOfLine() && !S->getFnParent())
  return;

// Template instantiations should also not be pushed into scope.
if (isa<FunctionDecl>(D) &&
    cast<FunctionDecl>(D)->isFunctionTemplateSpecialization())
  return;

// If this replaces anything in the current scope,
IdentifierResolver::iterator I = IdResolver.begin(D->getDeclName()),
                             IEnd = IdResolver.end();
for (; I != IEnd; ++I) {
  if (S->isDeclScope(*I) && D->declarationReplaces(*I)) {
    S->RemoveDecl(*I);
    IdResolver.RemoveDecl(*I);

    // Should only need to replace one decl.
    break;
  }
}

S->AddDecl(D);

if (isa<LabelDecl>(D) && !cast<LabelDecl>(D)->isGnuLocal()) {
  // Implicitly-generated labels may end up getting generated in an order that
  // isn't strictly lexical, which breaks name lookup. Be careful to insert
  // the label at the appropriate place in the identifier chain.
  for (I = IdResolver.begin(D->getDeclName()); I != IEnd; ++I) {
    DeclContext *IDC = (*I)->getLexicalDeclContext()->getRedeclContext();
    if (IDC == CurContext) {
      if (!S->isDeclScope(*I))
        continue;
    } else if (IDC->Encloses(CurContext))
      break;
  }

  IdResolver.InsertDeclAfter(I, D);
} else {
  IdResolver.AddDecl(D);
}
warnOnReservedIdentifier(D);
1593}

1595bool Sema::isDeclInScope(NamedDecl *D, DeclContext *Ctx, Scope *S,
                       bool AllowInlineNamespace) const {
return IdResolver.isDeclInScope(D, Ctx, S, AllowInlineNamespace);
1598}

1600Scope *Sema::getScopeForDeclContext(Scope *S, DeclContext *DC) {
DeclContext *TargetDC = DC->getPrimaryContext();
do {
  if (DeclContext *ScopeDC = S->getEntity())
    if (ScopeDC->getPrimaryContext() == TargetDC)
      return S;
} while ((S = S->getParent()));

return nullptr;
1609}

1611static bool isOutOfScopePreviousDeclaration(NamedDecl *,
                                          DeclContext*,
                                          ASTContext&);

1615/// Filters out lookup results that don't fall within the given scope
1616/// as determined by isDeclInScope.
1617void Sema::FilterLookupForScope(LookupResult &R, DeclContext *Ctx, Scope *S,
                              bool ConsiderLinkage,
                              bool AllowInlineNamespace) {
LookupResult::Filter F = R.makeFilter();
while (F.hasNext()) {
  NamedDecl *D = F.next();

  if (isDeclInScope(D, Ctx, S, AllowInlineNamespace))
    continue;

  if (ConsiderLinkage && isOutOfScopePreviousDeclaration(D, Ctx, Context))
    continue;

  F.erase();
}

F.done();
1634}

1636/// We've determined that \p New is a redeclaration of \p Old. Check that they
1637/// have compatible owning modules.
1638bool Sema::CheckRedeclarationModuleOwnership(NamedDecl *New, NamedDecl *Old) {
// [module.interface]p7:
// A declaration is attached to a module as follows:
// - If the declaration is a non-dependent friend declaration that nominates a
// function with a declarator-id that is a qualified-id or template-id or that
// nominates a class other than with an elaborated-type-specifier with neither
// a nested-name-specifier nor a simple-template-id, it is attached to the
// module to which the friend is attached ([basic.link]).
if (New->getFriendObjectKind() &&
    Old->getOwningModuleForLinkage() != New->getOwningModuleForLinkage()) {
  New->setLocalOwningModule(Old->getOwningModule());
  makeMergedDefinitionVisible(New);
  return false;
}

Module *NewM = New->getOwningModule();
Module *OldM = Old->getOwningModule();

if (NewM && NewM->isPrivateModule())
  NewM = NewM->Parent;
if (OldM && OldM->isPrivateModule())
  OldM = OldM->Parent;

if (NewM == OldM)
  return false;

if (NewM && OldM) {
  // A module implementation unit has visibility of the decls in its
  // implicitly imported interface.
  if (NewM->isModuleImplementation() && OldM == ThePrimaryInterface)
    return false;

  // Partitions are part of the module, but a partition could import another
  // module, so verify that the PMIs agree.
  if ((NewM->isModulePartition() || OldM->isModulePartition()) &&
      NewM->getPrimaryModuleInterfaceName() ==
          OldM->getPrimaryModuleInterfaceName())
    return false;
}

bool NewIsModuleInterface = NewM && NewM->isModulePurview();
bool OldIsModuleInterface = OldM && OldM->isModulePurview();
if (NewIsModuleInterface || OldIsModuleInterface) {
  // C++ Modules TS [basic.def.odr] 6.2/6.7 [sic]:
  //   if a declaration of D [...] appears in the purview of a module, all
  //   other such declarations shall appear in the purview of the same module
  Diag(New->getLocation(), diag::err_mismatched_owning_module)
    << New
    << NewIsModuleInterface
    << (NewIsModuleInterface ? NewM->getFullModuleName() : "")
    << OldIsModuleInterface
    << (OldIsModuleInterface ? OldM->getFullModuleName() : "");
  Diag(Old->getLocation(), diag::note_previous_declaration);
  New->setInvalidDecl();
  return true;
}

return false;
1696}

1698// [module.interface]p6:
1699// A redeclaration of an entity X is implicitly exported if X was introduced by
1700// an exported declaration; otherwise it shall not be exported.
1701bool Sema::CheckRedeclarationExported(NamedDecl *New, NamedDecl *Old) {
// [module.interface]p1:
// An export-declaration shall inhabit a namespace scope.
//
// So it is meaningless to talk about redeclaration which is not at namespace
// scope.
if (!New->getLexicalDeclContext()
         ->getNonTransparentContext()
         ->isFileContext() ||
    !Old->getLexicalDeclContext()
         ->getNonTransparentContext()
         ->isFileContext())
  return false;

bool IsNewExported = New->isInExportDeclContext();
bool IsOldExported = Old->isInExportDeclContext();

// It should be irrevelant if both of them are not exported.
if (!IsNewExported && !IsOldExported)
  return false;

if (IsOldExported)
  return false;

assert(IsNewExported)(static_cast <bool> (IsNewExported) ? void (0) : __assert_fail
 ("IsNewExported", "clang/lib/Sema/SemaDecl.cpp", 1725, __extension__
 __PRETTY_FUNCTION__));

auto Lk = Old->getFormalLinkage();
int S = 0;
if (Lk == Linkage::InternalLinkage)
  S = 1;
else if (Lk == Linkage::ModuleLinkage)
  S = 2;
Diag(New->getLocation(), diag::err_redeclaration_non_exported) << New << S;
Diag(Old->getLocation(), diag::note_previous_declaration);
return true;
1736}

1738// A wrapper function for checking the semantic restrictions of
1739// a redeclaration within a module.
1740bool Sema::CheckRedeclarationInModule(NamedDecl *New, NamedDecl *Old) {
if (CheckRedeclarationModuleOwnership(New, Old))
  return true;

if (CheckRedeclarationExported(New, Old))
  return true;

return false;
1748}

1750// Check the redefinition in C++20 Modules.
1751//
1752// [basic.def.odr]p14:
1753// For any definable item D with definitions in multiple translation units,
1754// - if D is a non-inline non-templated function or variable, or
1755// - if the definitions in different translation units do not satisfy the
1756// following requirements,
1757//   the program is ill-formed; a diagnostic is required only if the definable
1758//   item is attached to a named module and a prior definition is reachable at
1759//   the point where a later definition occurs.
1760// - Each such definition shall not be attached to a named module
1761// ([module.unit]).
1762// - Each such definition shall consist of the same sequence of tokens, ...
1763// ...
1764//
1765// Return true if the redefinition is not allowed. Return false otherwise.
1766bool Sema::IsRedefinitionInModule(const NamedDecl *New,
                                   const NamedDecl *Old) const {
assert(getASTContext().isSameEntity(New, Old) &&(static_cast <bool> (getASTContext().isSameEntity(New, Old
) && "New and Old are not the same definition, we should diagnostic it "
 "immediately instead of checking it.") ? void (0) : __assert_fail
 ("getASTContext().isSameEntity(New, Old) && \"New and Old are not the same definition, we should diagnostic it \" \"immediately instead of checking it.\""
, "clang/lib/Sema/SemaDecl.cpp", 1770, __extension__ __PRETTY_FUNCTION__
))
       "New and Old are not the same definition, we should diagnostic it "(static_cast <bool> (getASTContext().isSameEntity(New, Old
) && "New and Old are not the same definition, we should diagnostic it "
 "immediately instead of checking it.") ? void (0) : __assert_fail
 ("getASTContext().isSameEntity(New, Old) && \"New and Old are not the same definition, we should diagnostic it \" \"immediately instead of checking it.\""
, "clang/lib/Sema/SemaDecl.cpp", 1770, __extension__ __PRETTY_FUNCTION__
))
       "immediately instead of checking it.")(static_cast <bool> (getASTContext().isSameEntity(New, Old
) && "New and Old are not the same definition, we should diagnostic it "
 "immediately instead of checking it.") ? void (0) : __assert_fail
 ("getASTContext().isSameEntity(New, Old) && \"New and Old are not the same definition, we should diagnostic it \" \"immediately instead of checking it.\""
, "clang/lib/Sema/SemaDecl.cpp", 1770, __extension__ __PRETTY_FUNCTION__
));
assert(const_cast<Sema *>(this)->isReachable(New) &&(static_cast <bool> (const_cast<Sema *>(this)->
isReachable(New) && const_cast<Sema *>(this)->
isReachable(Old) && "We shouldn't see unreachable definitions here."
) ? void (0) : __assert_fail ("const_cast<Sema *>(this)->isReachable(New) && const_cast<Sema *>(this)->isReachable(Old) && \"We shouldn't see unreachable definitions here.\""
, "clang/lib/Sema/SemaDecl.cpp", 1773, __extension__ __PRETTY_FUNCTION__
))
       const_cast<Sema *>(this)->isReachable(Old) &&(static_cast <bool> (const_cast<Sema *>(this)->
isReachable(New) && const_cast<Sema *>(this)->
isReachable(Old) && "We shouldn't see unreachable definitions here."
) ? void (0) : __assert_fail ("const_cast<Sema *>(this)->isReachable(New) && const_cast<Sema *>(this)->isReachable(Old) && \"We shouldn't see unreachable definitions here.\""
, "clang/lib/Sema/SemaDecl.cpp", 1773, __extension__ __PRETTY_FUNCTION__
))
       "We shouldn't see unreachable definitions here.")(static_cast <bool> (const_cast<Sema *>(this)->
isReachable(New) && const_cast<Sema *>(this)->
isReachable(Old) && "We shouldn't see unreachable definitions here."
) ? void (0) : __assert_fail ("const_cast<Sema *>(this)->isReachable(New) && const_cast<Sema *>(this)->isReachable(Old) && \"We shouldn't see unreachable definitions here.\""
, "clang/lib/Sema/SemaDecl.cpp", 1773, __extension__ __PRETTY_FUNCTION__
));

Module *NewM = New->getOwningModule();
Module *OldM = Old->getOwningModule();

// We only checks for named modules here. The header like modules is skipped.
// FIXME: This is not right if we import the header like modules in the module
// purview.
//
// For example, assuming "header.h" provides definition for `D`.
// ```C++
// //--- M.cppm
// export module M;
// import "header.h"; // or #include "header.h" but import it by clang modules
// actually.
//
// //--- Use.cpp
// import M;
// import "header.h"; // or uses clang modules.
// ```
//
// In this case, `D` has multiple definitions in multiple TU (M.cppm and
// Use.cpp) and `D` is attached to a named module `M`. The compiler should
// reject it. But the current implementation couldn't detect the case since we
// don't record the information about the importee modules.
//
// But this might not be painful in practice. Since the design of C++20 Named
// Modules suggests us to use headers in global module fragment instead of
// module purview.
if (NewM && NewM->isHeaderLikeModule())
  NewM = nullptr;
if (OldM && OldM->isHeaderLikeModule())
  OldM = nullptr;

if (!NewM && !OldM)
  return true;

// [basic.def.odr]p14.3
// Each such definition shall not be attached to a named module
// ([module.unit]).
if ((NewM && NewM->isModulePurview()) || (OldM && OldM->isModulePurview()))
  return true;

// Then New and Old lives in the same TU if their share one same module unit.
if (NewM)
  NewM = NewM->getTopLevelModule();
if (OldM)
  OldM = OldM->getTopLevelModule();
return OldM == NewM;
1822}

1824static bool isUsingDecl(NamedDecl *D) {
return isa<UsingShadowDecl>(D) ||
       isa<UnresolvedUsingTypenameDecl>(D) ||
       isa<UnresolvedUsingValueDecl>(D);
1828}

1830/// Removes using shadow declarations from the lookup results.
1831static void RemoveUsingDecls(LookupResult &R) {
LookupResult::Filter F = R.makeFilter();
while (F.hasNext())
  if (isUsingDecl(F.next()))
    F.erase();

F.done();
1838}

1840/// Check for this common pattern:
1841/// @code
1842/// class S {
1843///   S(const S&); // DO NOT IMPLEMENT
1844///   void operator=(const S&); // DO NOT IMPLEMENT
1845/// };
1846/// @endcode
1847static bool IsDisallowedCopyOrAssign(const CXXMethodDecl *D) {
// FIXME: Should check for private access too but access is set after we get
// the decl here.
if (D->doesThisDeclarationHaveABody())
  return false;

if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(D))
  return CD->isCopyConstructor();
return D->isCopyAssignmentOperator();
1856}

1858// We need this to handle
1859//
1860// typedef struct {
1861//   void *foo() { return 0; }
1862// } A;
1863//
1864// When we see foo we don't know if after the typedef we will get 'A' or '*A'
1865// for example. If 'A', foo will have external linkage. If we have '*A',
1866// foo will have no linkage. Since we can't know until we get to the end
1867// of the typedef, this function finds out if D might have non-external linkage.
1868// Callers should verify at the end of the TU if it D has external linkage or
1869// not.
1870bool Sema::mightHaveNonExternalLinkage(const DeclaratorDecl *D) {
const DeclContext *DC = D->getDeclContext();
while (!DC->isTranslationUnit()) {
  if (const RecordDecl *RD = dyn_cast<RecordDecl>(DC)){
    if (!RD->hasNameForLinkage())
      return true;
  }
  DC = DC->getParent();
}

return !D->isExternallyVisible();
1881}

1883// FIXME: This needs to be refactored; some other isInMainFile users want
1884// these semantics.
1885static bool isMainFileLoc(const Sema &S, SourceLocation Loc) {
if (S.TUKind != TU_Complete || S.getLangOpts().IsHeaderFile)
  return false;
return S.SourceMgr.isInMainFile(Loc);
1889}

1891bool Sema::ShouldWarnIfUnusedFileScopedDecl(const DeclaratorDecl *D) const {
assert(D)(static_cast <bool> (D) ? void (0) : __assert_fail ("D"
, "clang/lib/Sema/SemaDecl.cpp", 1892, __extension__ __PRETTY_FUNCTION__
));

if (D->isInvalidDecl() || D->isUsed() || D->hasAttr<UnusedAttr>())
  return false;

// Ignore all entities declared within templates, and out-of-line definitions
// of members of class templates.
if (D->getDeclContext()->isDependentContext() ||
    D->getLexicalDeclContext()->isDependentContext())
  return false;

if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
  if (FD->getTemplateSpecializationKind() == TSK_ImplicitInstantiation)
    return false;
  // A non-out-of-line declaration of a member specialization was implicitly
  // instantiated; it's the out-of-line declaration that we're interested in.
  if (FD->getTemplateSpecializationKind() == TSK_ExplicitSpecialization &&
      FD->getMemberSpecializationInfo() && !FD->isOutOfLine())
    return false;

  if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD)) {
    if (MD->isVirtual() || IsDisallowedCopyOrAssign(MD))
      return false;
  } else {
    // 'static inline' functions are defined in headers; don't warn.
    if (FD->isInlined() && !isMainFileLoc(*this, FD->getLocation()))
      return false;
  }

  if (FD->doesThisDeclarationHaveABody() &&
      Context.DeclMustBeEmitted(FD))
    return false;
} else if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
  // Constants and utility variables are defined in headers with internal
  // linkage; don't warn.  (Unlike functions, there isn't a convenient marker
  // like "inline".)
  if (!isMainFileLoc(*this, VD->getLocation()))
    return false;

  if (Context.DeclMustBeEmitted(VD))
    return false;

  if (VD->isStaticDataMember() &&
      VD->getTemplateSpecializationKind() == TSK_ImplicitInstantiation)
    return false;
  if (VD->isStaticDataMember() &&
      VD->getTemplateSpecializationKind() == TSK_ExplicitSpecialization &&
      VD->getMemberSpecializationInfo() && !VD->isOutOfLine())
    return false;

  if (VD->isInline() && !isMainFileLoc(*this, VD->getLocation()))
    return false;
} else {
  return false;
}

// Only warn for unused decls internal to the translation unit.
// FIXME: This seems like a bogus check; it suppresses -Wunused-function
// for inline functions defined in the main source file, for instance.
return mightHaveNonExternalLinkage(D);
1952}

1954void Sema::MarkUnusedFileScopedDecl(const DeclaratorDecl *D) {
if (!D)
  return;

if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
  const FunctionDecl *First = FD->getFirstDecl();
  if (FD != First && ShouldWarnIfUnusedFileScopedDecl(First))
    return; // First should already be in the vector.
}

if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
  const VarDecl *First = VD->getFirstDecl();
  if (VD != First && ShouldWarnIfUnusedFileScopedDecl(First))
    return; // First should already be in the vector.
}

if (ShouldWarnIfUnusedFileScopedDecl(D))
  UnusedFileScopedDecls.push_back(D);
1972}

1974static bool ShouldDiagnoseUnusedDecl(const NamedDecl *D) {
if (D->isInvalidDecl())
  return false;

if (auto *DD = dyn_cast<DecompositionDecl>(D)) {
  // For a decomposition declaration, warn if none of the bindings are
  // referenced, instead of if the variable itself is referenced (which
  // it is, by the bindings' expressions).
  for (auto *BD : DD->bindings())
    if (BD->isReferenced())
      return false;
} else if (!D->getDeclName()) {
  return false;
} else if (D->isReferenced() || D->isUsed()) {
  return false;
}

if (D->hasAttr<UnusedAttr>() || D->hasAttr<ObjCPreciseLifetimeAttr>())
  return false;

if (isa<LabelDecl>(D))
  return true;

// Except for labels, we only care about unused decls that are local to
// functions.
bool WithinFunction = D->getDeclContext()->isFunctionOrMethod();
if (const auto *R = dyn_cast<CXXRecordDecl>(D->getDeclContext()))
  // For dependent types, the diagnostic is deferred.
  WithinFunction =
      WithinFunction || (R->isLocalClass() && !R->isDependentType());
if (!WithinFunction)
  return false;

if (isa<TypedefNameDecl>(D))
  return true;

// White-list anything that isn't a local variable.
if (!isa<VarDecl>(D) || isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D))
  return false;

// Types of valid local variables should be complete, so this should succeed.
if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {

  const Expr *Init = VD->getInit();
  if (const auto *Cleanups = dyn_cast_or_null<ExprWithCleanups>(Init))
    Init = Cleanups->getSubExpr();

  const auto *Ty = VD->getType().getTypePtr();

  // Only look at the outermost level of typedef.
  if (const TypedefType *TT = Ty->getAs<TypedefType>()) {
    // Allow anything marked with __attribute__((unused)).
    if (TT->getDecl()->hasAttr<UnusedAttr>())
      return false;
  }

  // Warn for reference variables whose initializtion performs lifetime
  // extension.
  if (const auto *MTE = dyn_cast_or_null<MaterializeTemporaryExpr>(Init)) {
    if (MTE->getExtendingDecl()) {
      Ty = VD->getType().getNonReferenceType().getTypePtr();
      Init = MTE->getSubExpr()->IgnoreImplicitAsWritten();
    }
  }

  // If we failed to complete the type for some reason, or if the type is
  // dependent, don't diagnose the variable.
  if (Ty->isIncompleteType() || Ty->isDependentType())
    return false;

  // Look at the element type to ensure that the warning behaviour is
  // consistent for both scalars and arrays.
  Ty = Ty->getBaseElementTypeUnsafe();

  if (const TagType *TT = Ty->getAs<TagType>()) {
    const TagDecl *Tag = TT->getDecl();
    if (Tag->hasAttr<UnusedAttr>())
      return false;

    if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(Tag)) {
      if (!RD->hasTrivialDestructor() && !RD->hasAttr<WarnUnusedAttr>())
        return false;

      if (Init) {
        const CXXConstructExpr *Construct =
          dyn_cast<CXXConstructExpr>(Init);
        if (Construct && !Construct->isElidable()) {
          CXXConstructorDecl *CD = Construct->getConstructor();
          if (!CD->isTrivial() && !RD->hasAttr<WarnUnusedAttr>() &&
              (VD->getInit()->isValueDependent() || !VD->evaluateValue()))
            return false;
        }

        // Suppress the warning if we don't know how this is constructed, and
        // it could possibly be non-trivial constructor.
        if (Init->isTypeDependent()) {
          for (const CXXConstructorDecl *Ctor : RD->ctors())
            if (!Ctor->isTrivial())
              return false;
        }

        // Suppress the warning if the constructor is unresolved because
        // its arguments are dependent.
        if (isa<CXXUnresolvedConstructExpr>(Init))
          return false;
      }
    }
  }

  // TODO: __attribute__((unused)) templates?
}

return true;
2087}

2089static void GenerateFixForUnusedDecl(const NamedDecl *D, ASTContext &Ctx,
                                   FixItHint &Hint) {
if (isa<LabelDecl>(D)) {
  SourceLocation AfterColon = Lexer::findLocationAfterToken(
      D->getEndLoc(), tok::colon, Ctx.getSourceManager(), Ctx.getLangOpts(),
      true);
  if (AfterColon.isInvalid())
    return;
  Hint = FixItHint::CreateRemoval(
      CharSourceRange::getCharRange(D->getBeginLoc(), AfterColon));
}
2100}

2102void Sema::DiagnoseUnusedNestedTypedefs(const RecordDecl *D) {
DiagnoseUnusedNestedTypedefs(
    D, [this](SourceLocation Loc, PartialDiagnostic PD) { Diag(Loc, PD); });
2105}

2107void Sema::DiagnoseUnusedNestedTypedefs(const RecordDecl *D,
                                      DiagReceiverTy DiagReceiver) {
if (D->getTypeForDecl()->isDependentType())
  return;

for (auto *TmpD : D->decls()) {
  if (const auto *T = dyn_cast<TypedefNameDecl>(TmpD))
    DiagnoseUnusedDecl(T, DiagReceiver);
  else if(const auto *R = dyn_cast<RecordDecl>(TmpD))
    DiagnoseUnusedNestedTypedefs(R, DiagReceiver);
}
2118}

2120void Sema::DiagnoseUnusedDecl(const NamedDecl *D) {
DiagnoseUnusedDecl(
    D, [this](SourceLocation Loc, PartialDiagnostic PD) { Diag(Loc, PD); });
2123}

2125/// DiagnoseUnusedDecl - Emit warnings about declarations that are not used
2126/// unless they are marked attr(unused).
2127void Sema::DiagnoseUnusedDecl(const NamedDecl *D, DiagReceiverTy DiagReceiver) {
if (!ShouldDiagnoseUnusedDecl(D))
  return;

if (auto *TD = dyn_cast<TypedefNameDecl>(D)) {
  // typedefs can be referenced later on, so the diagnostics are emitted
  // at end-of-translation-unit.
  UnusedLocalTypedefNameCandidates.insert(TD);
  return;
}

FixItHint Hint;
GenerateFixForUnusedDecl(D, Context, Hint);

unsigned DiagID;
if (isa<VarDecl>(D) && cast<VarDecl>(D)->isExceptionVariable())
  DiagID = diag::warn_unused_exception_param;
else if (isa<LabelDecl>(D))
  DiagID = diag::warn_unused_label;
else
  DiagID = diag::warn_unused_variable;

DiagReceiver(D->getLocation(), PDiag(DiagID) << D << Hint);
2150}

2152void Sema::DiagnoseUnusedButSetDecl(const VarDecl *VD,
                                  DiagReceiverTy DiagReceiver) {
// If it's not referenced, it can't be set. If it has the Cleanup attribute,
// it's not really unused.
if (!VD->isReferenced() || !VD->getDeclName() || VD->hasAttr<UnusedAttr>() ||
    VD->hasAttr<CleanupAttr>())
  return;

const auto *Ty = VD->getType().getTypePtr()->getBaseElementTypeUnsafe();

if (Ty->isReferenceType() || Ty->isDependentType())
  return;

if (const TagType *TT = Ty->getAs<TagType>()) {
  const TagDecl *Tag = TT->getDecl();
  if (Tag->hasAttr<UnusedAttr>())
    return;
  // In C++, don't warn for record types that don't have WarnUnusedAttr, to
  // mimic gcc's behavior.
  if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(Tag)) {
    if (!RD->hasAttr<WarnUnusedAttr>())
      return;
  }
}

// Don't warn about __block Objective-C pointer variables, as they might
// be assigned in the block but not used elsewhere for the purpose of lifetime
// extension.
if (VD->hasAttr<BlocksAttr>() && Ty->isObjCObjectPointerType())
  return;

// Don't warn about Objective-C pointer variables with precise lifetime
// semantics; they can be used to ensure ARC releases the object at a known
// time, which may mean assignment but no other references.
if (VD->hasAttr<ObjCPreciseLifetimeAttr>() && Ty->isObjCObjectPointerType())
  return;

auto iter = RefsMinusAssignments.find(VD);
if (iter == RefsMinusAssignments.end())
  return;

assert(iter->getSecond() >= 0 &&(static_cast <bool> (iter->getSecond() >= 0 &&
 "Found a negative number of references to a VarDecl") ? void
 (0) : __assert_fail ("iter->getSecond() >= 0 && \"Found a negative number of references to a VarDecl\""
, "clang/lib/Sema/SemaDecl.cpp", 2194, __extension__ __PRETTY_FUNCTION__
))
       "Found a negative number of references to a VarDecl")(static_cast <bool> (iter->getSecond() >= 0 &&
 "Found a negative number of references to a VarDecl") ? void
 (0) : __assert_fail ("iter->getSecond() >= 0 && \"Found a negative number of references to a VarDecl\""
, "clang/lib/Sema/SemaDecl.cpp", 2194, __extension__ __PRETTY_FUNCTION__
));
if (iter->getSecond() != 0)
  return;
unsigned DiagID = isa<ParmVarDecl>(VD) ? diag::warn_unused_but_set_parameter
                                       : diag::warn_unused_but_set_variable;
DiagReceiver(VD->getLocation(), PDiag(DiagID) << VD);
2200}

2202static void CheckPoppedLabel(LabelDecl *L, Sema &S,
                           Sema::DiagReceiverTy DiagReceiver) {
// Verify that we have no forward references left.  If so, there was a goto
// or address of a label taken, but no definition of it.  Label fwd
// definitions are indicated with a null substmt which is also not a resolved
// MS inline assembly label name.
bool Diagnose = false;
if (L->isMSAsmLabel())
  Diagnose = !L->isResolvedMSAsmLabel();
else
  Diagnose = L->getStmt() == nullptr;
if (Diagnose)
  DiagReceiver(L->getLocation(), S.PDiag(diag::err_undeclared_label_use)
                                     << L);
2216}

2218void Sema::ActOnPopScope(SourceLocation Loc, Scope *S) {
S->applyNRVO();

if (S->decl_empty()) return;
assert((S->getFlags() & (Scope::DeclScope | Scope::TemplateParamScope)) &&(static_cast <bool> ((S->getFlags() & (Scope::DeclScope
 | Scope::TemplateParamScope)) && "Scope shouldn't contain decls!"
) ? void (0) : __assert_fail ("(S->getFlags() & (Scope::DeclScope | Scope::TemplateParamScope)) && \"Scope shouldn't contain decls!\""
, "clang/lib/Sema/SemaDecl.cpp", 2223, __extension__ __PRETTY_FUNCTION__
))
       "Scope shouldn't contain decls!")(static_cast <bool> ((S->getFlags() & (Scope::DeclScope
 | Scope::TemplateParamScope)) && "Scope shouldn't contain decls!"
) ? void (0) : __assert_fail ("(S->getFlags() & (Scope::DeclScope | Scope::TemplateParamScope)) && \"Scope shouldn't contain decls!\""
, "clang/lib/Sema/SemaDecl.cpp", 2223, __extension__ __PRETTY_FUNCTION__
));

/// We visit the decls in non-deterministic order, but we want diagnostics
/// emitted in deterministic order. Collect any diagnostic that may be emitted
/// and sort the diagnostics before emitting them, after we visited all decls.
struct LocAndDiag {
  SourceLocation Loc;
  std::optional<SourceLocation> PreviousDeclLoc;
  PartialDiagnostic PD;
};
SmallVector<LocAndDiag, 16> DeclDiags;
auto addDiag = [&DeclDiags](SourceLocation Loc, PartialDiagnostic PD) {
  DeclDiags.push_back(LocAndDiag{Loc, std::nullopt, std::move(PD)});
};
auto addDiagWithPrev = [&DeclDiags](SourceLocation Loc,
                                    SourceLocation PreviousDeclLoc,
                                    PartialDiagnostic PD) {
  DeclDiags.push_back(LocAndDiag{Loc, PreviousDeclLoc, std::move(PD)});
};

for (auto *TmpD : S->decls()) {
  assert(TmpD && "This decl didn't get pushed??")(static_cast <bool> (TmpD && "This decl didn't get pushed??"
) ? void (0) : __assert_fail ("TmpD && \"This decl didn't get pushed??\""
, "clang/lib/Sema/SemaDecl.cpp", 2244, __extension__ __PRETTY_FUNCTION__
));

  assert(isa<NamedDecl>(TmpD) && "Decl isn't NamedDecl?")(static_cast <bool> (isa<NamedDecl>(TmpD) &&
 "Decl isn't NamedDecl?") ? void (0) : __assert_fail ("isa<NamedDecl>(TmpD) && \"Decl isn't NamedDecl?\""
, "clang/lib/Sema/SemaDecl.cpp", 2246, __extension__ __PRETTY_FUNCTION__
));
  NamedDecl *D = cast<NamedDecl>(TmpD);

  // Diagnose unused variables in this scope.
  if (!S->hasUnrecoverableErrorOccurred()) {
    DiagnoseUnusedDecl(D, addDiag);
    if (const auto *RD = dyn_cast<RecordDecl>(D))
      DiagnoseUnusedNestedTypedefs(RD, addDiag);
    if (VarDecl *VD = dyn_cast<VarDecl>(D)) {
      DiagnoseUnusedButSetDecl(VD, addDiag);
      RefsMinusAssignments.erase(VD);
    }
  }

  if (!D->getDeclName()) continue;

  // If this was a forward reference to a label, verify it was defined.
  if (LabelDecl *LD = dyn_cast<LabelDecl>(D))
    CheckPoppedLabel(LD, *this, addDiag);

  // Remove this name from our lexical scope, and warn on it if we haven't
  // already.
  IdResolver.RemoveDecl(D);
  auto ShadowI = ShadowingDecls.find(D);
  if (ShadowI != ShadowingDecls.end()) {
    if (const auto *FD = dyn_cast<FieldDecl>(ShadowI->second)) {
      addDiagWithPrev(D->getLocation(), FD->getLocation(),
                      PDiag(diag::warn_ctor_parm_shadows_field)
                          << D << FD << FD->getParent());
    }
    ShadowingDecls.erase(ShadowI);
  }
}

llvm::sort(DeclDiags,
           [](const LocAndDiag &LHS, const LocAndDiag &RHS) -> bool {
             // The particular order for diagnostics is not important, as long
             // as the order is deterministic. Using the raw location is going
             // to generally be in source order unless there are macro
             // expansions involved.
             return LHS.Loc.getRawEncoding() < RHS.Loc.getRawEncoding();
           });
for (const LocAndDiag &D : DeclDiags) {
  Diag(D.Loc, D.PD);
  if (D.PreviousDeclLoc)
    Diag(*D.PreviousDeclLoc, diag::note_previous_declaration);
}
2293}

2295/// Look for an Objective-C class in the translation unit.
2296///
2297/// \param Id The name of the Objective-C class we're looking for. If
2298/// typo-correction fixes this name, the Id will be updated
2299/// to the fixed name.
2300///
2301/// \param IdLoc The location of the name in the translation unit.
2302///
2303/// \param DoTypoCorrection If true, this routine will attempt typo correction
2304/// if there is no class with the given name.
2305///
2306/// \returns The declaration of the named Objective-C class, or NULL if the
2307/// class could not be found.
2308ObjCInterfaceDecl *Sema::getObjCInterfaceDecl(IdentifierInfo *&Id,
                                            SourceLocation IdLoc,
                                            bool DoTypoCorrection) {
// The third "scope" argument is 0 since we aren't enabling lazy built-in
// creation from this context.
NamedDecl *IDecl = LookupSingleName(TUScope, Id, IdLoc, LookupOrdinaryName);

if (!IDecl && DoTypoCorrection) {
  // Perform typo correction at the given location, but only if we
  // find an Objective-C class name.
  DeclFilterCCC<ObjCInterfaceDecl> CCC{};
  if (TypoCorrection C =
          CorrectTypo(DeclarationNameInfo(Id, IdLoc), LookupOrdinaryName,
                      TUScope, nullptr, CCC, CTK_ErrorRecovery)) {
    diagnoseTypo(C, PDiag(diag::err_undef_interface_suggest) << Id);
    IDecl = C.getCorrectionDeclAs<ObjCInterfaceDecl>();
    Id = IDecl->getIdentifier();
  }
}
ObjCInterfaceDecl *Def = dyn_cast_or_null<ObjCInterfaceDecl>(IDecl);
// This routine must always return a class definition, if any.
if (Def && Def->getDefinition())
    Def = Def->getDefinition();
return Def;
2332}

2334/// getNonFieldDeclScope - Retrieves the innermost scope, starting
2335/// from S, where a non-field would be declared. This routine copes
2336/// with the difference between C and C++ scoping rules in structs and
2337/// unions. For example, the following code is well-formed in C but
2338/// ill-formed in C++:
2339/// @code
2340/// struct S6 {
2341///   enum { BAR } e;
2342/// };
2343///
2344/// void test_S6() {
2345///   struct S6 a;
2346///   a.e = BAR;
2347/// }
2348/// @endcode
2349/// For the declaration of BAR, this routine will return a different
2350/// scope. The scope S will be the scope of the unnamed enumeration
2351/// within S6. In C++, this routine will return the scope associated
2352/// with S6, because the enumeration's scope is a transparent
2353/// context but structures can contain non-field names. In C, this
2354/// routine will return the translation unit scope, since the
2355/// enumeration's scope is a transparent context and structures cannot
2356/// contain non-field names.
2357Scope *Sema::getNonFieldDeclScope(Scope *S) {
while (((S->getFlags() & Scope::DeclScope) == 0) ||
       (S->getEntity() && S->getEntity()->isTransparentContext()) ||
       (S->isClassScope() && !getLangOpts().CPlusPlus))
  S = S->getParent();
return S;
2363}

2365static StringRef getHeaderName(Builtin::Context &BuiltinInfo, unsigned ID,
                             ASTContext::GetBuiltinTypeError Error) {
switch (Error) {
case ASTContext::GE_None:
  return "";
case ASTContext::GE_Missing_type:
  return BuiltinInfo.getHeaderName(ID);
case ASTContext::GE_Missing_stdio:
  return "stdio.h";
case ASTContext::GE_Missing_setjmp:
  return "setjmp.h";
case ASTContext::GE_Missing_ucontext:
  return "ucontext.h";
}
llvm_unreachable("unhandled error kind")::llvm::llvm_unreachable_internal("unhandled error kind", "clang/lib/Sema/SemaDecl.cpp"
, 2379);
2380}

2382FunctionDecl *Sema::CreateBuiltin(IdentifierInfo *II, QualType Type,
                                unsigned ID, SourceLocation Loc) {
DeclContext *Parent = Context.getTranslationUnitDecl();

if (getLangOpts().CPlusPlus) {
  LinkageSpecDecl *CLinkageDecl = LinkageSpecDecl::Create(
      Context, Parent, Loc, Loc, LinkageSpecDecl::lang_c, false);
  CLinkageDecl->setImplicit();
  Parent->addDecl(CLinkageDecl);
  Parent = CLinkageDecl;
}

FunctionDecl *New = FunctionDecl::Create(Context, Parent, Loc, Loc, II, Type,
                                         /*TInfo=*/nullptr, SC_Extern,
                                         getCurFPFeatures().isFPConstrained(),
                                         false, Type->isFunctionProtoType());
New->setImplicit();
New->addAttr(BuiltinAttr::CreateImplicit(Context, ID));

// Create Decl objects for each parameter, adding them to the
// FunctionDecl.
if (const FunctionProtoType *FT = dyn_cast<FunctionProtoType>(Type)) {
  SmallVector<ParmVarDecl *, 16> Params;
  for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i) {
    ParmVarDecl *parm = ParmVarDecl::Create(
        Context, New, SourceLocation(), SourceLocation(), nullptr,
        FT->getParamType(i), /*TInfo=*/nullptr, SC_None, nullptr);
    parm->setScopeInfo(0, i);
    Params.push_back(parm);
  }
  New->setParams(Params);
}

AddKnownFunctionAttributes(New);
return New;
2417}

2419/// LazilyCreateBuiltin - The specified Builtin-ID was first used at
2420/// file scope.  lazily create a decl for it. ForRedeclaration is true
2421/// if we're creating this built-in in anticipation of redeclaring the
2422/// built-in.
2423NamedDecl *Sema::LazilyCreateBuiltin(IdentifierInfo *II, unsigned ID,
                                   Scope *S, bool ForRedeclaration,
                                   SourceLocation Loc) {
LookupNecessaryTypesForBuiltin(S, ID);

ASTContext::GetBuiltinTypeError Error;
QualType R = Context.GetBuiltinType(ID, Error);
if (Error) {
  if (!ForRedeclaration)
    return nullptr;

  // If we have a builtin without an associated type we should not emit a
  // warning when we were not able to find a type for it.
  if (Error == ASTContext::GE_Missing_type ||
      Context.BuiltinInfo.allowTypeMismatch(ID))
    return nullptr;

  // If we could not find a type for setjmp it is because the jmp_buf type was
  // not defined prior to the setjmp declaration.
  if (Error == ASTContext::GE_Missing_setjmp) {
    Diag(Loc, diag::warn_implicit_decl_no_jmp_buf)
        << Context.BuiltinInfo.getName(ID);
    return nullptr;
  }

  // Generally, we emit a warning that the declaration requires the
  // appropriate header.
  Diag(Loc, diag::warn_implicit_decl_requires_sysheader)
      << getHeaderName(Context.BuiltinInfo, ID, Error)
      << Context.BuiltinInfo.getName(ID);
  return nullptr;
}

if (!ForRedeclaration &&
    (Context.BuiltinInfo.isPredefinedLibFunction(ID) ||
     Context.BuiltinInfo.isHeaderDependentFunction(ID))) {
  Diag(Loc, LangOpts.C99 ? diag::ext_implicit_lib_function_decl_c99
                         : diag::ext_implicit_lib_function_decl)
      << Context.BuiltinInfo.getName(ID) << R;
  if (const char *Header = Context.BuiltinInfo.getHeaderName(ID))
    Diag(Loc, diag::note_include_header_or_declare)
        << Header << Context.BuiltinInfo.getName(ID);
}

if (R.isNull())
  return nullptr;

FunctionDecl *New = CreateBuiltin(II, R, ID, Loc);
RegisterLocallyScopedExternCDecl(New, S);

// TUScope is the translation-unit scope to insert this function into.
// FIXME: This is hideous. We need to teach PushOnScopeChains to
// relate Scopes to DeclContexts, and probably eliminate CurContext
// entirely, but we're not there yet.
DeclContext *SavedContext = CurContext;
CurContext = New->getDeclContext();
PushOnScopeChains(New, TUScope);
CurContext = SavedContext;
return New;
2482}

2484/// Typedef declarations don't have linkage, but they still denote the same
2485/// entity if their types are the same.
2486/// FIXME: This is notionally doing the same thing as ASTReaderDecl's
2487/// isSameEntity.
2488static void filterNonConflictingPreviousTypedefDecls(Sema &S,
                                                   TypedefNameDecl *Decl,
                                                   LookupResult &Previous) {
// This is only interesting when modules are enabled.
if (!S.getLangOpts().Modules && !S.getLangOpts().ModulesLocalVisibility)
  return;

// Empty sets are uninteresting.
if (Previous.empty())
  return;

LookupResult::Filter Filter = Previous.makeFilter();
while (Filter.hasNext()) {
  NamedDecl *Old = Filter.next();

  // Non-hidden declarations are never ignored.
  if (S.isVisible(Old))
    continue;

  // Declarations of the same entity are not ignored, even if they have
  // different linkages.
  if (auto *OldTD = dyn_cast<TypedefNameDecl>(Old)) {
    if (S.Context.hasSameType(OldTD->getUnderlyingType(),
                              Decl->getUnderlyingType()))
      continue;

    // If both declarations give a tag declaration a typedef name for linkage
    // purposes, then they declare the same entity.
    if (OldTD->getAnonDeclWithTypedefName(/*AnyRedecl*/true) &&
        Decl->getAnonDeclWithTypedefName())
      continue;
  }

  Filter.erase();
}

Filter.done();
2525}

2527bool Sema::isIncompatibleTypedef(TypeDecl *Old, TypedefNameDecl *New) {
QualType OldType;
if (TypedefNameDecl *OldTypedef = dyn_cast<TypedefNameDecl>(Old))
  OldType = OldTypedef->getUnderlyingType();
else
  OldType = Context.getTypeDeclType(Old);
QualType NewType = New->getUnderlyingType();

if (NewType->isVariablyModifiedType()) {
  // Must not redefine a typedef with a variably-modified type.
  int Kind = isa<TypeAliasDecl>(Old) ? 1 : 0;
  Diag(New->getLocation(), diag::err_redefinition_variably_modified_typedef)
    << Kind << NewType;
  if (Old->getLocation().isValid())
    notePreviousDefinition(Old, New->getLocation());
  New->setInvalidDecl();
  return true;
}

if (OldType != NewType &&
    !OldType->isDependentType() &&
    !NewType->isDependentType() &&
    !Context.hasSameType(OldType, NewType)) {
  int Kind = isa<TypeAliasDecl>(Old) ? 1 : 0;
  Diag(New->getLocation(), diag::err_redefinition_different_typedef)
    << Kind << NewType << OldType;
  if (Old->getLocation().isValid())
    notePreviousDefinition(Old, New->getLocation());
  New->setInvalidDecl();
  return true;
}
return false;
2559}

2561/// MergeTypedefNameDecl - We just parsed a typedef 'New' which has the
2562/// same name and scope as a previous declaration 'Old'.  Figure out
2563/// how to resolve this situation, merging decls or emitting
2564/// diagnostics as appropriate. If there was an error, set New to be invalid.
2565///
2566void Sema::MergeTypedefNameDecl(Scope *S, TypedefNameDecl *New,
                              LookupResult &OldDecls) {
// If the new decl is known invalid already, don't bother doing any
// merging checks.
if (New->isInvalidDecl()) return;

// Allow multiple definitions for ObjC built-in typedefs.
// FIXME: Verify the underlying types are equivalent!
if (getLangOpts().ObjC) {
  const IdentifierInfo *TypeID = New->getIdentifier();
  switch (TypeID->getLength()) {
  default: break;
  case 2:
    {
      if (!TypeID->isStr("id"))
        break;
      QualType T = New->getUnderlyingType();
      if (!T->isPointerType())
        break;
      if (!T->isVoidPointerType()) {
        QualType PT = T->castAs<PointerType>()->getPointeeType();
        if (!PT->isStructureType())
          break;
      }
      Context.setObjCIdRedefinitionType(T);
      // Install the built-in type for 'id', ignoring the current definition.
      New->setTypeForDecl(Context.getObjCIdType().getTypePtr());
      return;
    }
  case 5:
    if (!TypeID->isStr("Class"))
      break;
    Context.setObjCClassRedefinitionType(New->getUnderlyingType());
    // Install the built-in type for 'Class', ignoring the current definition.
    New->setTypeForDecl(Context.getObjCClassType().getTypePtr());
    return;
  case 3:
    if (!TypeID->isStr("SEL"))
      break;
    Context.setObjCSelRedefinitionType(New->getUnderlyingType());
    // Install the built-in type for 'SEL', ignoring the current definition.
    New->setTypeForDecl(Context.getObjCSelType().getTypePtr());
    return;
  }
  // Fall through - the typedef name was not a builtin type.
}

// Verify the old decl was also a type.
TypeDecl *Old = OldDecls.getAsSingle<TypeDecl>();
if (!Old) {
  Diag(New->getLocation(), diag::err_redefinition_different_kind)
    << New->getDeclName();

  NamedDecl *OldD = OldDecls.getRepresentativeDecl();
  if (OldD->getLocation().isValid())
    notePreviousDefinition(OldD, New->getLocation());

  return New->setInvalidDecl();
}

// If the old declaration is invalid, just give up here.
if (Old->isInvalidDecl())
  return New->setInvalidDecl();

if (auto *OldTD = dyn_cast<TypedefNameDecl>(Old)) {
  auto *OldTag = OldTD->getAnonDeclWithTypedefName(/*AnyRedecl*/true);
  auto *NewTag = New->getAnonDeclWithTypedefName();
  NamedDecl *Hidden = nullptr;
  if (OldTag && NewTag &&
      OldTag->getCanonicalDecl() != NewTag->getCanonicalDecl() &&
      !hasVisibleDefinition(OldTag, &Hidden)) {
    // There is a definition of this tag, but it is not visible. Use it
    // instead of our tag.
    New->setTypeForDecl(OldTD->getTypeForDecl());
    if (OldTD->isModed())
      New->setModedTypeSourceInfo(OldTD->getTypeSourceInfo(),
                                  OldTD->getUnderlyingType());
    else
      New->setTypeSourceInfo(OldTD->getTypeSourceInfo());

    // Make the old tag definition visible.
    makeMergedDefinitionVisible(Hidden);

    // If this was an unscoped enumeration, yank all of its enumerators
    // out of the scope.
    if (isa<EnumDecl>(NewTag)) {
      Scope *EnumScope = getNonFieldDeclScope(S);
      for (auto *D : NewTag->decls()) {
        auto *ED = cast<EnumConstantDecl>(D);
        assert(EnumScope->isDeclScope(ED))(static_cast <bool> (EnumScope->isDeclScope(ED)) ? void
 (0) : __assert_fail ("EnumScope->isDeclScope(ED)", "clang/lib/Sema/SemaDecl.cpp"
, 2655, __extension__ __PRETTY_FUNCTION__));
        EnumScope->RemoveDecl(ED);
        IdResolver.RemoveDecl(ED);
        ED->getLexicalDeclContext()->removeDecl(ED);
      }
    }
  }
}

// If the typedef types are not identical, reject them in all languages and
// with any extensions enabled.
if (isIncompatibleTypedef(Old, New))
  return;

// The types match.  Link up the redeclaration chain and merge attributes if
// the old declaration was a typedef.
if (TypedefNameDecl *Typedef = dyn_cast<TypedefNameDecl>(Old)) {
  New->setPreviousDecl(Typedef);
  mergeDeclAttributes(New, Old);
}

if (getLangOpts().MicrosoftExt)
  return;

if (getLangOpts().CPlusPlus) {
  // C++ [dcl.typedef]p2:
  //   In a given non-class scope, a typedef specifier can be used to
  //   redefine the name of any type declared in that scope to refer
  //   to the type to which it already refers.
  if (!isa<CXXRecordDecl>(CurContext))
    return;

  // C++0x [dcl.typedef]p4:
  //   In a given class scope, a typedef specifier can be used to redefine
  //   any class-name declared in that scope that is not also a typedef-name
  //   to refer to the type to which it already refers.
  //
  // This wording came in via DR424, which was a correction to the
  // wording in DR56, which accidentally banned code like:
  //
  //   struct S {
  //     typedef struct A { } A;
  //   };
  //
  // in the C++03 standard. We implement the C++0x semantics, which
  // allow the above but disallow
  //
  //   struct S {
  //     typedef int I;
  //     typedef int I;
  //   };
  //
  // since that was the intent of DR56.
  if (!isa<TypedefNameDecl>(Old))
    return;

  Diag(New->getLocation(), diag::err_redefinition)
    << New->getDeclName();
  notePreviousDefinition(Old, New->getLocation());
  return New->setInvalidDecl();
}

// Modules always permit redefinition of typedefs, as does C11.
if (getLangOpts().Modules || getLangOpts().C11)
  return;

// If we have a redefinition of a typedef in C, emit a warning.  This warning
// is normally mapped to an error, but can be controlled with
// -Wtypedef-redefinition.  If either the original or the redefinition is
// in a system header, don't emit this for compatibility with GCC.
if (getDiagnostics().getSuppressSystemWarnings() &&
    // Some standard types are defined implicitly in Clang (e.g. OpenCL).
    (Old->isImplicit() ||
     Context.getSourceManager().isInSystemHeader(Old->getLocation()) ||
     Context.getSourceManager().isInSystemHeader(New->getLocation())))
  return;

Diag(New->getLocation(), diag::ext_redefinition_of_typedef)
  << New->getDeclName();
notePreviousDefinition(Old, New->getLocation());
2735}

2737/// DeclhasAttr - returns true if decl Declaration already has the target
2738/// attribute.
2739static bool DeclHasAttr(const Decl *D, const Attr *A) {
const OwnershipAttr *OA = dyn_cast<OwnershipAttr>(A);
const AnnotateAttr *Ann = dyn_cast<AnnotateAttr>(A);
for (const auto *i : D->attrs())
  if (i->getKind() == A->getKind()) {
    if (Ann) {
      if (Ann->getAnnotation() == cast<AnnotateAttr>(i)->getAnnotation())
        return true;
      continue;
    }
    // FIXME: Don't hardcode this check
    if (OA && isa<OwnershipAttr>(i))
      return OA->getOwnKind() == cast<OwnershipAttr>(i)->getOwnKind();
    return true;
  }

return false;
2756}

2758static bool isAttributeTargetADefinition(Decl *D) {
if (VarDecl *VD = dyn_cast<VarDecl>(D))
  return VD->isThisDeclarationADefinition();
if (TagDecl *TD = dyn_cast<TagDecl>(D))
  return TD->isCompleteDefinition() || TD->isBeingDefined();
return true;
2764}

2766/// Merge alignment attributes from \p Old to \p New, taking into account the
2767/// special semantics of C11's _Alignas specifier and C++11's alignas attribute.
2768///
2769/// \return \c true if any attributes were added to \p New.
2770static bool mergeAlignedAttrs(Sema &S, NamedDecl *New, Decl *Old) {
// Look for alignas attributes on Old, and pick out whichever attribute
// specifies the strictest alignment requirement.
AlignedAttr *OldAlignasAttr = nullptr;
AlignedAttr *OldStrictestAlignAttr = nullptr;
unsigned OldAlign = 0;
for (auto *I : Old->specific_attrs<AlignedAttr>()) {
  // FIXME: We have no way of representing inherited dependent alignments
  // in a case like:
  //   template<int A, int B> struct alignas(A) X;
  //   template<int A, int B> struct alignas(B) X {};
  // For now, we just ignore any alignas attributes which are not on the
  // definition in such a case.
  if (I->isAlignmentDependent())
    return false;

  if (I->isAlignas())
    OldAlignasAttr = I;

  unsigned Align = I->getAlignment(S.Context);
  if (Align > OldAlign) {
    OldAlign = Align;
    OldStrictestAlignAttr = I;
  }
}

// Look for alignas attributes on New.
AlignedAttr *NewAlignasAttr = nullptr;
unsigned NewAlign = 0;
for (auto *I : New->specific_attrs<AlignedAttr>()) {
  if (I->isAlignmentDependent())
    return false;

  if (I->isAlignas())
    NewAlignasAttr = I;

  unsigned Align = I->getAlignment(S.Context);
  if (Align > NewAlign)
    NewAlign = Align;
}

if (OldAlignasAttr && NewAlignasAttr && OldAlign != NewAlign) {
  // Both declarations have 'alignas' attributes. We require them to match.
  // C++11 [dcl.align]p6 and C11 6.7.5/7 both come close to saying this, but
  // fall short. (If two declarations both have alignas, they must both match
  // every definition, and so must match each other if there is a definition.)

  // If either declaration only contains 'alignas(0)' specifiers, then it
  // specifies the natural alignment for the type.
  if (OldAlign == 0 || NewAlign == 0) {
    QualType Ty;
    if (ValueDecl *VD = dyn_cast<ValueDecl>(New))
      Ty = VD->getType();
    else
      Ty = S.Context.getTagDeclType(cast<TagDecl>(New));

    if (OldAlign == 0)
      OldAlign = S.Context.getTypeAlign(Ty);
    if (NewAlign == 0)
      NewAlign = S.Context.getTypeAlign(Ty);
  }

  if (OldAlign != NewAlign) {
    S.Diag(NewAlignasAttr->getLocation(), diag::err_alignas_mismatch)
      << (unsigned)S.Context.toCharUnitsFromBits(OldAlign).getQuantity()
      << (unsigned)S.Context.toCharUnitsFromBits(NewAlign).getQuantity();
    S.Diag(OldAlignasAttr->getLocation(), diag::note_previous_declaration);
  }
}

if (OldAlignasAttr && !NewAlignasAttr && isAttributeTargetADefinition(New)) {
  // C++11 [dcl.align]p6:
  //   if any declaration of an entity has an alignment-specifier,
  //   every defining declaration of that entity shall specify an
  //   equivalent alignment.
  // C11 6.7.5/7:
  //   If the definition of an object does not have an alignment
  //   specifier, any other declaration of that object shall also
  //   have no alignment specifier.
  S.Diag(New->getLocation(), diag::err_alignas_missing_on_definition)
    << OldAlignasAttr;
  S.Diag(OldAlignasAttr->getLocation(), diag::note_alignas_on_declaration)
    << OldAlignasAttr;
}

bool AnyAdded = false;

// Ensure we have an attribute representing the strictest alignment.
if (OldAlign > NewAlign) {
  AlignedAttr *Clone = OldStrictestAlignAttr->clone(S.Context);
  Clone->setInherited(true);
  New->addAttr(Clone);
  AnyAdded = true;
}

// Ensure we have an alignas attribute if the old declaration had one.
if (OldAlignasAttr && !NewAlignasAttr &&
    !(AnyAdded && OldStrictestAlignAttr->isAlignas())) {
  AlignedAttr *Clone = OldAlignasAttr->clone(S.Context);
  Clone->setInherited(true);
  New->addAttr(Clone);
  AnyAdded = true;
}

return AnyAdded;
2875}

2877#define WANT_DECL_MERGE_LOGIC
2878#include "clang/Sema/AttrParsedAttrImpl.inc"
2879#undef WANT_DECL_MERGE_LOGIC

2881static bool mergeDeclAttribute(Sema &S, NamedDecl *D,
                             const InheritableAttr *Attr,
                             Sema::AvailabilityMergeKind AMK) {
// Diagnose any mutual exclusions between the attribute that we want to add
// and attributes that already exist on the declaration.
if (!DiagnoseMutualExclusions(S, D, Attr))
  return false;

// This function copies an attribute Attr from a previous declaration to the
// new declaration D if the new declaration doesn't itself have that attribute
// yet or if that attribute allows duplicates.
// If you're adding a new attribute that requires logic different from
// "use explicit attribute on decl if present, else use attribute from
// previous decl", for example if the attribute needs to be consistent
// between redeclarations, you need to call a custom merge function here.
InheritableAttr *NewAttr = nullptr;
if (const auto *AA = dyn_cast<AvailabilityAttr>(Attr))
  NewAttr = S.mergeAvailabilityAttr(
      D, *AA, AA->getPlatform(), AA->isImplicit(), AA->getIntroduced(),
      AA->getDeprecated(), AA->getObsoleted(), AA->getUnavailable(),
      AA->getMessage(), AA->getStrict(), AA->getReplacement(), AMK,
      AA->getPriority());
else if (const auto *VA = dyn_cast<VisibilityAttr>(Attr))
  NewAttr = S.mergeVisibilityAttr(D, *VA, VA->getVisibility());
else if (const auto *VA = dyn_cast<TypeVisibilityAttr>(Attr))
  NewAttr = S.mergeTypeVisibilityAttr(D, *VA, VA->getVisibility());
else if (const auto *ImportA = dyn_cast<DLLImportAttr>(Attr))
  NewAttr = S.mergeDLLImportAttr(D, *ImportA);
else if (const auto *ExportA = dyn_cast<DLLExportAttr>(Attr))
  NewAttr = S.mergeDLLExportAttr(D, *ExportA);
else if (const auto *EA = dyn_cast<ErrorAttr>(Attr))
  NewAttr = S.mergeErrorAttr(D, *EA, EA->getUserDiagnostic());
else if (const auto *FA = dyn_cast<FormatAttr>(Attr))
  NewAttr = S.mergeFormatAttr(D, *FA, FA->getType(), FA->getFormatIdx(),
                              FA->getFirstArg());
else if (const auto *SA = dyn_cast<SectionAttr>(Attr))
  NewAttr = S.mergeSectionAttr(D, *SA, SA->getName());
else if (const auto *CSA = dyn_cast<CodeSegAttr>(Attr))
  NewAttr = S.mergeCodeSegAttr(D, *CSA, CSA->getName());
else if (const auto *IA = dyn_cast<MSInheritanceAttr>(Attr))
  NewAttr = S.mergeMSInheritanceAttr(D, *IA, IA->getBestCase(),
                                     IA->getInheritanceModel());
else if (const auto *AA = dyn_cast<AlwaysInlineAttr>(Attr))
  NewAttr = S.mergeAlwaysInlineAttr(D, *AA,
                                    &S.Context.Idents.get(AA->getSpelling()));
else if (S.getLangOpts().CUDA && isa<FunctionDecl>(D) &&
         (isa<CUDAHostAttr>(Attr) || isa<CUDADeviceAttr>(Attr) ||
          isa<CUDAGlobalAttr>(Attr))) {
  // CUDA target attributes are part of function signature for
  // overloading purposes and must not be merged.
  return false;
} else if (const auto *MA = dyn_cast<MinSizeAttr>(Attr))
  NewAttr = S.mergeMinSizeAttr(D, *MA);
else if (const auto *SNA = dyn_cast<SwiftNameAttr>(Attr))
  NewAttr = S.mergeSwiftNameAttr(D, *SNA, SNA->getName());
else if (const auto *OA = dyn_cast<OptimizeNoneAttr>(Attr))
  NewAttr = S.mergeOptimizeNoneAttr(D, *OA);
else if (const auto *InternalLinkageA = dyn_cast<InternalLinkageAttr>(Attr))
  NewAttr = S.mergeInternalLinkageAttr(D, *InternalLinkageA);
else if (isa<AlignedAttr>(Attr))
  // AlignedAttrs are handled separately, because we need to handle all
  // such attributes on a declaration at the same time.
  NewAttr = nullptr;
else if ((isa<DeprecatedAttr>(Attr) || isa<UnavailableAttr>(Attr)) &&
         (AMK == Sema::AMK_Override ||
          AMK == Sema::AMK_ProtocolImplementation ||
          AMK == Sema::AMK_OptionalProtocolImplementation))
  NewAttr = nullptr;
else if (const auto *UA = dyn_cast<UuidAttr>(Attr))
  NewAttr = S.mergeUuidAttr(D, *UA, UA->getGuid(), UA->getGuidDecl());
else if (const auto *IMA = dyn_cast<WebAssemblyImportModuleAttr>(Attr))
  NewAttr = S.mergeImportModuleAttr(D, *IMA);
else if (const auto *INA = dyn_cast<WebAssemblyImportNameAttr>(Attr))
  NewAttr = S.mergeImportNameAttr(D, *INA);
else if (const auto *TCBA = dyn_cast<EnforceTCBAttr>(Attr))
  NewAttr = S.mergeEnforceTCBAttr(D, *TCBA);
else if (const auto *TCBLA = dyn_cast<EnforceTCBLeafAttr>(Attr))
  NewAttr = S.mergeEnforceTCBLeafAttr(D, *TCBLA);
else if (const auto *BTFA = dyn_cast<BTFDeclTagAttr>(Attr))
  NewAttr = S.mergeBTFDeclTagAttr(D, *BTFA);
else if (const auto *NT = dyn_cast<HLSLNumThreadsAttr>(Attr))
  NewAttr =
      S.mergeHLSLNumThreadsAttr(D, *NT, NT->getX(), NT->getY(), NT->getZ());
else if (const auto *SA = dyn_cast<HLSLShaderAttr>(Attr))
  NewAttr = S.mergeHLSLShaderAttr(D, *SA, SA->getType());
else if (Attr->shouldInheritEvenIfAlreadyPresent() || !DeclHasAttr(D, Attr))
  NewAttr = cast<InheritableAttr>(Attr->clone(S.Context));

if (NewAttr) {
  NewAttr->setInherited(true);
  D->addAttr(NewAttr);
  if (isa<MSInheritanceAttr>(NewAttr))
    S.Consumer.AssignInheritanceModel(cast<CXXRecordDecl>(D));
  return true;
}

return false;
2978}

2980static const NamedDecl *getDefinition(const Decl *D) {
if (const TagDecl *TD = dyn_cast<TagDecl>(D))
  return TD->getDefinition();
if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
  const VarDecl *Def = VD->getDefinition();
  if (Def)
    return Def;
  return VD->getActingDefinition();
}
if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
  const FunctionDecl *Def = nullptr;
  if (FD->isDefined(Def, true))
    return Def;
}
return nullptr;
2995}

2997static bool hasAttribute(const Decl *D, attr::Kind Kind) {
for (const auto *Attribute : D->attrs())
  if (Attribute->getKind() == Kind)
    return true;
return false;
3002}

3004/// checkNewAttributesAfterDef - If we already have a definition, check that
3005/// there are no new attributes in this declaration.
3006static void checkNewAttributesAfterDef(Sema &S, Decl *New, const Decl *Old) {
if (!New->hasAttrs())
  return;

const NamedDecl *Def = getDefinition(Old);
if (!Def || Def == New)
  return;

AttrVec &NewAttributes = New->getAttrs();
for (unsigned I = 0, E = NewAttributes.size(); I != E;) {
  const Attr *NewAttribute = NewAttributes[I];

  if (isa<AliasAttr>(NewAttribute) || isa<IFuncAttr>(NewAttribute)) {
    if (FunctionDecl *FD = dyn_cast<FunctionDecl>(New)) {
      Sema::SkipBodyInfo SkipBody;
      S.CheckForFunctionRedefinition(FD, cast<FunctionDecl>(Def), &SkipBody);

      // If we're skipping this definition, drop the "alias" attribute.
      if (SkipBody.ShouldSkip) {
        NewAttributes.erase(NewAttributes.begin() + I);
        --E;
        continue;
      }
    } else {
      VarDecl *VD = cast<VarDecl>(New);
      unsigned Diag = cast<VarDecl>(Def)->isThisDeclarationADefinition() ==
                              VarDecl::TentativeDefinition
                          ? diag::err_alias_after_tentative
                          : diag::err_redefinition;
      S.Diag(VD->getLocation(), Diag) << VD->getDeclName();
      if (Diag == diag::err_redefinition)
        S.notePreviousDefinition(Def, VD->getLocation());
      else
        S.Diag(Def->getLocation(), diag::note_previous_definition);
      VD->setInvalidDecl();
    }
    ++I;
    continue;
  }

  if (const VarDecl *VD = dyn_cast<VarDecl>(Def)) {
    // Tentative definitions are only interesting for the alias check above.
    if (VD->isThisDeclarationADefinition() != VarDecl::Definition) {
      ++I;
      continue;
    }
  }

  if (hasAttribute(Def, NewAttribute->getKind())) {
    ++I;
    continue; // regular attr merging will take care of validating this.
  }

  if (isa<C11NoReturnAttr>(NewAttribute)) {
    // C's _Noreturn is allowed to be added to a function after it is defined.
    ++I;
    continue;
  } else if (isa<UuidAttr>(NewAttribute)) {
    // msvc will allow a subsequent definition to add an uuid to a class
    ++I;
    continue;
  } else if (const AlignedAttr *AA = dyn_cast<AlignedAttr>(NewAttribute)) {
    if (AA->isAlignas()) {
      // C++11 [dcl.align]p6:
      //   if any declaration of an entity has an alignment-specifier,
      //   every defining declaration of that entity shall specify an
      //   equivalent alignment.
      // C11 6.7.5/7:
      //   If the definition of an object does not have an alignment
      //   specifier, any other declaration of that object shall also
      //   have no alignment specifier.
      S.Diag(Def->getLocation(), diag::err_alignas_missing_on_definition)
        << AA;
      S.Diag(NewAttribute->getLocation(), diag::note_alignas_on_declaration)
        << AA;
      NewAttributes.erase(NewAttributes.begin() + I);
      --E;
      continue;
    }
  } else if (isa<LoaderUninitializedAttr>(NewAttribute)) {
    // If there is a C definition followed by a redeclaration with this
    // attribute then there are two different definitions. In C++, prefer the
    // standard diagnostics.
    if (!S.getLangOpts().CPlusPlus) {
      S.Diag(NewAttribute->getLocation(),
             diag::err_loader_uninitialized_redeclaration);
      S.Diag(Def->getLocation(), diag::note_previous_definition);
      NewAttributes.erase(NewAttributes.begin() + I);
      --E;
      continue;
    }
  } else if (isa<SelectAnyAttr>(NewAttribute) &&
             cast<VarDecl>(New)->isInline() &&
             !cast<VarDecl>(New)->isInlineSpecified()) {
    // Don't warn about applying selectany to implicitly inline variables.
    // Older compilers and language modes would require the use of selectany
    // to make such variables inline, and it would have no effect if we
    // honored it.
    ++I;
    continue;
  } else if (isa<OMPDeclareVariantAttr>(NewAttribute)) {
    // We allow to add OMP[Begin]DeclareVariantAttr to be added to
    // declarations after definitions.
    ++I;
    continue;
  }

  S.Diag(NewAttribute->getLocation(),
         diag::warn_attribute_precede_definition);
  S.Diag(Def->getLocation(), diag::note_previous_definition);
  NewAttributes.erase(NewAttributes.begin() + I);
  --E;
}
3119}

3121static void diagnoseMissingConstinit(Sema &S, const VarDecl *InitDecl,
                                   const ConstInitAttr *CIAttr,
                                   bool AttrBeforeInit) {
SourceLocation InsertLoc = InitDecl->getInnerLocStart();

// Figure out a good way to write this specifier on the old declaration.
// FIXME: We should just use the spelling of CIAttr, but we don't preserve
// enough of the attribute list spelling information to extract that without
// heroics.
std::string SuitableSpelling;
if (S.getLangOpts().CPlusPlus20)
  SuitableSpelling = std::string(
      S.PP.getLastMacroWithSpelling(InsertLoc, {tok::kw_constinit}));
if (SuitableSpelling.empty() && S.getLangOpts().CPlusPlus11)
  SuitableSpelling = std::string(S.PP.getLastMacroWithSpelling(
      InsertLoc, {tok::l_square, tok::l_square,
                  S.PP.getIdentifierInfo("clang"), tok::coloncolon,
                  S.PP.getIdentifierInfo("require_constant_initialization"),
                  tok::r_square, tok::r_square}));
if (SuitableSpelling.empty())
  SuitableSpelling = std::string(S.PP.getLastMacroWithSpelling(
      InsertLoc, {tok::kw___attribute, tok::l_paren, tok::r_paren,
                  S.PP.getIdentifierInfo("require_constant_initialization"),
                  tok::r_paren, tok::r_paren}));
if (SuitableSpelling.empty() && S.getLangOpts().CPlusPlus20)
  SuitableSpelling = "constinit";
if (SuitableSpelling.empty() && S.getLangOpts().CPlusPlus11)
  SuitableSpelling = "[[clang::require_constant_initialization]]";
if (SuitableSpelling.empty())
  SuitableSpelling = "__attribute__((require_constant_initialization))";
SuitableSpelling += " ";

if (AttrBeforeInit) {
  // extern constinit int a;
  // int a = 0; // error (missing 'constinit'), accepted as extension
  assert(CIAttr->isConstinit() && "should not diagnose this for attribute")(static_cast <bool> (CIAttr->isConstinit() &&
 "should not diagnose this for attribute") ? void (0) : __assert_fail
 ("CIAttr->isConstinit() && \"should not diagnose this for attribute\""
, "clang/lib/Sema/SemaDecl.cpp", 3156, __extension__ __PRETTY_FUNCTION__
));
  S.Diag(InitDecl->getLocation(), diag::ext_constinit_missing)
      << InitDecl << FixItHint::CreateInsertion(InsertLoc, SuitableSpelling);
  S.Diag(CIAttr->getLocation(), diag::note_constinit_specified_here);
} else {
  // int a = 0;
  // constinit extern int a; // error (missing 'constinit')
  S.Diag(CIAttr->getLocation(),
         CIAttr->isConstinit() ? diag::err_constinit_added_too_late
                               : diag::warn_require_const_init_added_too_late)
      << FixItHint::CreateRemoval(SourceRange(CIAttr->getLocation()));
  S.Diag(InitDecl->getLocation(), diag::note_constinit_missing_here)
      << CIAttr->isConstinit()
      << FixItHint::CreateInsertion(InsertLoc, SuitableSpelling);
}
3171}

3173/// mergeDeclAttributes - Copy attributes from the Old decl to the New one.
3174void Sema::mergeDeclAttributes(NamedDecl *New, Decl *Old,
                             AvailabilityMergeKind AMK) {
if (UsedAttr *OldAttr = Old->getMostRecentDecl()->getAttr<UsedAttr>()) {
  UsedAttr *NewAttr = OldAttr->clone(Context);
  NewAttr->setInherited(true);
  New->addAttr(NewAttr);
}
if (RetainAttr *OldAttr = Old->getMostRecentDecl()->getAttr<RetainAttr>()) {
  RetainAttr *NewAttr = OldAttr->clone(Context);
  NewAttr->setInherited(true);
  New->addAttr(NewAttr);
}

if (!Old->hasAttrs() && !New->hasAttrs())
  return;

// [dcl.constinit]p1:
//   If the [constinit] specifier is applied to any declaration of a
//   variable, it shall be applied to the initializing declaration.
const auto *OldConstInit = Old->getAttr<ConstInitAttr>();
const auto *NewConstInit = New->getAttr<ConstInitAttr>();
if (bool(OldConstInit) != bool(NewConstInit)) {
  const auto *OldVD = cast<VarDecl>(Old);
  auto *NewVD = cast<VarDecl>(New);

  // Find the initializing declaration. Note that we might not have linked
  // the new declaration into the redeclaration chain yet.
  const VarDecl *InitDecl = OldVD->getInitializingDeclaration();
  if (!InitDecl &&
      (NewVD->hasInit() || NewVD->isThisDeclarationADefinition()))
    InitDecl = NewVD;

  if (InitDecl == NewVD) {
    // This is the initializing declaration. If it would inherit 'constinit',
    // that's ill-formed. (Note that we do not apply this to the attribute
    // form).
    if (OldConstInit && OldConstInit->isConstinit())
      diagnoseMissingConstinit(*this, NewVD, OldConstInit,
                               /*AttrBeforeInit=*/true);
  } else if (NewConstInit) {
    // This is the first time we've been told that this declaration should
    // have a constant initializer. If we already saw the initializing
    // declaration, this is too late.
    if (InitDecl && InitDecl != NewVD) {
      diagnoseMissingConstinit(*this, InitDecl, NewConstInit,
                               /*AttrBeforeInit=*/false);
      NewVD->dropAttr<ConstInitAttr>();
    }
  }
}

// Attributes declared post-definition are currently ignored.
checkNewAttributesAfterDef(*this, New, Old);

if (AsmLabelAttr *NewA = New->getAttr<AsmLabelAttr>()) {
  if (AsmLabelAttr *OldA = Old->getAttr<AsmLabelAttr>()) {
    if (!OldA->isEquivalent(NewA)) {
      // This redeclaration changes __asm__ label.
      Diag(New->getLocation(), diag::err_different_asm_label);
      Diag(OldA->getLocation(), diag::note_previous_declaration);
    }
  } else if (Old->isUsed()) {
    // This redeclaration adds an __asm__ label to a declaration that has
    // already been ODR-used.
    Diag(New->getLocation(), diag::err_late_asm_label_name)
      << isa<FunctionDecl>(Old) << New->getAttr<AsmLabelAttr>()->getRange();
  }
}

// Re-declaration cannot add abi_tag's.
if (const auto *NewAbiTagAttr = New->getAttr<AbiTagAttr>()) {
  if (const auto *OldAbiTagAttr = Old->getAttr<AbiTagAttr>()) {
    for (const auto &NewTag : NewAbiTagAttr->tags()) {
      if (!llvm::is_contained(OldAbiTagAttr->tags(), NewTag)) {
        Diag(NewAbiTagAttr->getLocation(),
             diag::err_new_abi_tag_on_redeclaration)
            << NewTag;
        Diag(OldAbiTagAttr->getLocation(), diag::note_previous_declaration);
      }
    }
  } else {
    Diag(NewAbiTagAttr->getLocation(), diag::err_abi_tag_on_redeclaration);
    Diag(Old->getLocation(), diag::note_previous_declaration);
  }
}

// This redeclaration adds a section attribute.
if (New->hasAttr<SectionAttr>() && !Old->hasAttr<SectionAttr>()) {
  if (auto *VD = dyn_cast<VarDecl>(New)) {
    if (VD->isThisDeclarationADefinition() == VarDecl::DeclarationOnly) {
      Diag(New->getLocation(), diag::warn_attribute_section_on_redeclaration);
      Diag(Old->getLocation(), diag::note_previous_declaration);
    }
  }
}

// Redeclaration adds code-seg attribute.
const auto *NewCSA = New->getAttr<CodeSegAttr>();
if (NewCSA && !Old->hasAttr<CodeSegAttr>() &&
    !NewCSA->isImplicit() && isa<CXXMethodDecl>(New)) {
  Diag(New->getLocation(), diag::warn_mismatched_section)
       << 0 /*codeseg*/;
  Diag(Old->getLocation(), diag::note_previous_declaration);
}

if (!Old->hasAttrs())
  return;

bool foundAny = New->hasAttrs();

// Ensure that any moving of objects within the allocated map is done before
// we process them.
if (!foundAny) New->setAttrs(AttrVec());

for (auto *I : Old->specific_attrs<InheritableAttr>()) {
  // Ignore deprecated/unavailable/availability attributes if requested.
  AvailabilityMergeKind LocalAMK = AMK_None;
  if (isa<DeprecatedAttr>(I) ||
      isa<UnavailableAttr>(I) ||
      isa<AvailabilityAttr>(I)) {
    switch (AMK) {
    case AMK_None:
      continue;

    case AMK_Redeclaration:
    case AMK_Override:
    case AMK_ProtocolImplementation:
    case AMK_OptionalProtocolImplementation:
      LocalAMK = AMK;
      break;
    }
  }

  // Already handled.
  if (isa<UsedAttr>(I) || isa<RetainAttr>(I))
    continue;

  if (mergeDeclAttribute(*this, New, I, LocalAMK))
    foundAny = true;
}

if (mergeAlignedAttrs(*this, New, Old))
  foundAny = true;

if (!foundAny) New->dropAttrs();
3319}

3321/// mergeParamDeclAttributes - Copy attributes from the old parameter
3322/// to the new one.
3323static void mergeParamDeclAttributes(ParmVarDecl *newDecl,
                                   const ParmVarDecl *oldDecl,
                                   Sema &S) {
// C++11 [dcl.attr.depend]p2:
//   The first declaration of a function shall specify the
//   carries_dependency attribute for its declarator-id if any declaration
//   of the function specifies the carries_dependency attribute.
const CarriesDependencyAttr *CDA = newDecl->getAttr<CarriesDependencyAttr>();
if (CDA && !oldDecl->hasAttr<CarriesDependencyAttr>()) {
  S.Diag(CDA->getLocation(),
         diag::err_carries_dependency_missing_on_first_decl) << 1/*Param*/;
  // Find the first declaration of the parameter.
  // FIXME: Should we build redeclaration chains for function parameters?
  const FunctionDecl *FirstFD =
    cast<FunctionDecl>(oldDecl->getDeclContext())->getFirstDecl();
  const ParmVarDecl *FirstVD =
    FirstFD->getParamDecl(oldDecl->getFunctionScopeIndex());
  S.Diag(FirstVD->getLocation(),
         diag::note_carries_dependency_missing_first_decl) << 1/*Param*/;
}

if (!oldDecl->hasAttrs())
  return;

bool foundAny = newDecl->hasAttrs();

// Ensure that any moving of objects within the allocated map is
// done before we process them.
if (!foundAny) newDecl->setAttrs(AttrVec());

for (const auto *I : oldDecl->specific_attrs<InheritableParamAttr>()) {
  if (!DeclHasAttr(newDecl, I)) {
    InheritableAttr *newAttr =
      cast<InheritableParamAttr>(I->clone(S.Context));
    newAttr->setInherited(true);
    newDecl->addAttr(newAttr);
    foundAny = true;
  }
}

if (!foundAny) newDecl->dropAttrs();
3364}

3366static bool EquivalentArrayTypes(QualType Old, QualType New,
                               const ASTContext &Ctx) {

auto NoSizeInfo = [&Ctx](QualType Ty) {
  if (Ty->isIncompleteArrayType() || Ty->isPointerType())
    return true;
  if (const auto *VAT = Ctx.getAsVariableArrayType(Ty))
    return VAT->getSizeModifier() == ArrayType::ArraySizeModifier::Star;
  return false;
};

// `type[]` is equivalent to `type *` and `type[*]`.
if (NoSizeInfo(Old) && NoSizeInfo(New))
  return true;

// Don't try to compare VLA sizes, unless one of them has the star modifier.
if (Old->isVariableArrayType() && New->isVariableArrayType()) {
  const auto *OldVAT = Ctx.getAsVariableArrayType(Old);
  const auto *NewVAT = Ctx.getAsVariableArrayType(New);
  if ((OldVAT->getSizeModifier() == ArrayType::ArraySizeModifier::Star) ^
      (NewVAT->getSizeModifier() == ArrayType::ArraySizeModifier::Star))
    return false;
  return true;
}

// Only compare size, ignore Size modifiers and CVR.
if (Old->isConstantArrayType() && New->isConstantArrayType()) {
  return Ctx.getAsConstantArrayType(Old)->getSize() ==
         Ctx.getAsConstantArrayType(New)->getSize();
}

// Don't try to compare dependent sized array
if (Old->isDependentSizedArrayType() && New->isDependentSizedArrayType()) {
  return true;
}

return Old == New;
3403}

3405static void mergeParamDeclTypes(ParmVarDecl *NewParam,
                              const ParmVarDecl *OldParam,
                              Sema &S) {
if (auto Oldnullability = OldParam->getType()->getNullability()) {
  if (auto Newnullability = NewParam->getType()->getNullability()) {
    if (*Oldnullability != *Newnullability) {
      S.Diag(NewParam->getLocation(), diag::warn_mismatched_nullability_attr)
        << DiagNullabilityKind(
             *Newnullability,
             ((NewParam->getObjCDeclQualifier() & Decl::OBJC_TQ_CSNullability)
              != 0))
        << DiagNullabilityKind(
             *Oldnullability,
             ((OldParam->getObjCDeclQualifier() & Decl::OBJC_TQ_CSNullability)
              != 0));
      S.Diag(OldParam->getLocation(), diag::note_previous_declaration);
    }
  } else {
    QualType NewT = NewParam->getType();
    NewT = S.Context.getAttributedType(
                       AttributedType::getNullabilityAttrKind(*Oldnullability),
                       NewT, NewT);
    NewParam->setType(NewT);
  }
}
const auto *OldParamDT = dyn_cast<DecayedType>(OldParam->getType());
const auto *NewParamDT = dyn_cast<DecayedType>(NewParam->getType());
if (OldParamDT && NewParamDT &&
    OldParamDT->getPointeeType() == NewParamDT->getPointeeType()) {
  QualType OldParamOT = OldParamDT->getOriginalType();
  QualType NewParamOT = NewParamDT->getOriginalType();
  if (!EquivalentArrayTypes(OldParamOT, NewParamOT, S.getASTContext())) {
    S.Diag(NewParam->getLocation(), diag::warn_inconsistent_array_form)
        << NewParam << NewParamOT;
    S.Diag(OldParam->getLocation(), diag::note_previous_declaration_as)
        << OldParamOT;
  }
}
3443}

3445namespace {

3447/// Used in MergeFunctionDecl to keep track of function parameters in
3448/// C.
3449struct GNUCompatibleParamWarning {
ParmVarDecl *OldParm;
ParmVarDecl *NewParm;
QualType PromotedType;
3453};

3455} // end anonymous namespace

3457// Determine whether the previous declaration was a definition, implicit
3458// declaration, or a declaration.
3459template <typename T>
3460static std::pair<diag::kind, SourceLocation>
3461getNoteDiagForInvalidRedeclaration(const T *Old, const T *New) {
diag::kind PrevDiag;
SourceLocation OldLocation = Old->getLocation();
if (Old->isThisDeclarationADefinition())
  PrevDiag = diag::note_previous_definition;
else if (Old->isImplicit()) {
  PrevDiag = diag::note_previous_implicit_declaration;
  if (const auto *FD = dyn_cast<FunctionDecl>(Old)) {
    if (FD->getBuiltinID())
      PrevDiag = diag::note_previous_builtin_declaration;
  }
  if (OldLocation.isInvalid())
    OldLocation = New->getLocation();
} else
  PrevDiag = diag::note_previous_declaration;
return std::make_pair(PrevDiag, OldLocation);
3477}

3479/// canRedefineFunction - checks if a function can be redefined. Currently,
3480/// only extern inline functions can be redefined, and even then only in
3481/// GNU89 mode.
3482static bool canRedefineFunction(const FunctionDecl *FD,
                              const LangOptions& LangOpts) {
return ((FD->hasAttr<GNUInlineAttr>() || LangOpts.GNUInline) &&
        !LangOpts.CPlusPlus &&
        FD->isInlineSpecified() &&
        FD->getStorageClass() == SC_Extern);
3488}

3490const AttributedType *Sema::getCallingConvAttributedType(QualType T) const {
const AttributedType *AT = T->getAs<AttributedType>();
while (AT && !AT->isCallingConv())
  AT = AT->getModifiedType()->getAs<AttributedType>();
return AT;
3495}

3497template <typename T>
3498static bool haveIncompatibleLanguageLinkages(const T *Old, const T *New) {
const DeclContext *DC = Old->getDeclContext();
if (DC->isRecord())
  return false;

LanguageLinkage OldLinkage = Old->getLanguageLinkage();
if (OldLinkage == CXXLanguageLinkage && New->isInExternCContext())
  return true;
if (OldLinkage == CLanguageLinkage && New->isInExternCXXContext())
  return true;
return false;
3509}

3511template<typename T> static bool isExternC(T *D) { return D->isExternC(); }
3512static bool isExternC(VarTemplateDecl *) { return false; }
3513static bool isExternC(FunctionTemplateDecl *) { return false; }

3515/// Check whether a redeclaration of an entity introduced by a
3516/// using-declaration is valid, given that we know it's not an overload
3517/// (nor a hidden tag declaration).
3518template<typename ExpectedDecl>
3519static bool checkUsingShadowRedecl(Sema &S, UsingShadowDecl *OldS,
                                 ExpectedDecl *New) {
// C++11 [basic.scope.declarative]p4:
//   Given a set of declarations in a single declarative region, each of
//   which specifies the same unqualified name,
//   -- they shall all refer to the same entity, or all refer to functions
//      and function templates; or
//   -- exactly one declaration shall declare a class name or enumeration
//      name that is not a typedef name and the other declarations shall all
//      refer to the same variable or enumerator, or all refer to functions
//      and function templates; in this case the class name or enumeration
//      name is hidden (3.3.10).

// C++11 [namespace.udecl]p14:
//   If a function declaration in namespace scope or block scope has the
//   same name and the same parameter-type-list as a function introduced
//   by a using-declaration, and the declarations do not declare the same
//   function, the program is ill-formed.

auto *Old = dyn_cast<ExpectedDecl>(OldS->getTargetDecl());
if (Old &&
    !Old->getDeclContext()->getRedeclContext()->Equals(
        New->getDeclContext()->getRedeclContext()) &&
    !(isExternC(Old) && isExternC(New)))
  Old = nullptr;

if (!Old) {
  S.Diag(New->getLocation(), diag::err_using_decl_conflict_reverse);
  S.Diag(OldS->getTargetDecl()->getLocation(), diag::note_using_decl_target);
  S.Diag(OldS->getIntroducer()->getLocation(), diag::note_using_decl) << 0;
  return true;
}
return false;
3552}

3554static bool hasIdenticalPassObjectSizeAttrs(const FunctionDecl *A,
                                          const FunctionDecl *B) {
assert(A->getNumParams() == B->getNumParams())(static_cast <bool> (A->getNumParams() == B->getNumParams
()) ? void (0) : __assert_fail ("A->getNumParams() == B->getNumParams()"
, "clang/lib/Sema/SemaDecl.cpp", 3556, __extension__ __PRETTY_FUNCTION__
));

auto AttrEq = [](const ParmVarDecl *A, const ParmVarDecl *B) {
  const auto *AttrA = A->getAttr<PassObjectSizeAttr>();
  const auto *AttrB = B->getAttr<PassObjectSizeAttr>();
  if (AttrA == AttrB)
    return true;
  return AttrA && AttrB && AttrA->getType() == AttrB->getType() &&
         AttrA->isDynamic() == AttrB->isDynamic();
};

return std::equal(A->param_begin(), A->param_end(), B->param_begin(), AttrEq);
3568}

3570/// If necessary, adjust the semantic declaration context for a qualified
3571/// declaration to name the correct inline namespace within the qualifier.
3572static void adjustDeclContextForDeclaratorDecl(DeclaratorDecl *NewD,
                                             DeclaratorDecl *OldD) {
// The only case where we need to update the DeclContext is when
// redeclaration lookup for a qualified name finds a declaration
// in an inline namespace within the context named by the qualifier:
//
//   inline namespace N { int f(); }
//   int ::f(); // Sema DC needs adjusting from :: to N::.
//
// For unqualified declarations, the semantic context *can* change
// along the redeclaration chain (for local extern declarations,
// extern "C" declarations, and friend declarations in particular).
if (!NewD->getQualifier())
  return;

// NewD is probably already in the right context.
auto *NamedDC = NewD->getDeclContext()->getRedeclContext();
auto *SemaDC = OldD->getDeclContext()->getRedeclContext();
if (NamedDC->Equals(SemaDC))
  return;

assert((NamedDC->InEnclosingNamespaceSetOf(SemaDC) ||(static_cast <bool> ((NamedDC->InEnclosingNamespaceSetOf
(SemaDC) || NewD->isInvalidDecl() || OldD->isInvalidDecl
()) && "unexpected context for redeclaration") ? void
 (0) : __assert_fail ("(NamedDC->InEnclosingNamespaceSetOf(SemaDC) || NewD->isInvalidDecl() || OldD->isInvalidDecl()) && \"unexpected context for redeclaration\""
, "clang/lib/Sema/SemaDecl.cpp", 3595, __extension__ __PRETTY_FUNCTION__
))
        NewD->isInvalidDecl() || OldD->isInvalidDecl()) &&(static_cast <bool> ((NamedDC->InEnclosingNamespaceSetOf
(SemaDC) || NewD->isInvalidDecl() || OldD->isInvalidDecl
()) && "unexpected context for redeclaration") ? void
 (0) : __assert_fail ("(NamedDC->InEnclosingNamespaceSetOf(SemaDC) || NewD->isInvalidDecl() || OldD->isInvalidDecl()) && \"unexpected context for redeclaration\""
, "clang/lib/Sema/SemaDecl.cpp", 3595, __extension__ __PRETTY_FUNCTION__
))
       "unexpected context for redeclaration")(static_cast <bool> ((NamedDC->InEnclosingNamespaceSetOf
(SemaDC) || NewD->isInvalidDecl() || OldD->isInvalidDecl
()) && "unexpected context for redeclaration") ? void
 (0) : __assert_fail ("(NamedDC->InEnclosingNamespaceSetOf(SemaDC) || NewD->isInvalidDecl() || OldD->isInvalidDecl()) && \"unexpected context for redeclaration\""
, "clang/lib/Sema/SemaDecl.cpp", 3595, __extension__ __PRETTY_FUNCTION__
));

auto *LexDC = NewD->getLexicalDeclContext();
auto FixSemaDC = [=](NamedDecl *D) {
  if (!D)
    return;
  D->setDeclContext(SemaDC);
  D->setLexicalDeclContext(LexDC);
};

FixSemaDC(NewD);
if (auto *FD = dyn_cast<FunctionDecl>(NewD))
  FixSemaDC(FD->getDescribedFunctionTemplate());
else if (auto *VD = dyn_cast<VarDecl>(NewD))
  FixSemaDC(VD->getDescribedVarTemplate());
3610}

3612/// MergeFunctionDecl - We just parsed a function 'New' from
3613/// declarator D which has the same name and scope as a previous
3614/// declaration 'Old'.  Figure out how to resolve this situation,
3615/// merging decls or emitting diagnostics as appropriate.
3616///
3617/// In C++, New and Old must be declarations that are not
3618/// overloaded. Use IsOverload to determine whether New and Old are
3619/// overloaded, and to select the Old declaration that New should be
3620/// merged with.
3621///
3622/// Returns true if there was an error, false otherwise.
3623bool Sema::MergeFunctionDecl(FunctionDecl *New, NamedDecl *&OldD, Scope *S,
                           bool MergeTypeWithOld, bool NewDeclIsDefn) {
// Verify the old decl was also a function.
FunctionDecl *Old = OldD->getAsFunction();
if (!Old) {
1
Assuming 'Old' is non-null→
2
←
Taking false branch→
  if (UsingShadowDecl *Shadow = dyn_cast<UsingShadowDecl>(OldD)) {
    if (New->getFriendObjectKind()) {
      Diag(New->getLocation(), diag::err_using_decl_friend);
      Diag(Shadow->getTargetDecl()->getLocation(),
           diag::note_using_decl_target);
      Diag(Shadow->getIntroducer()->getLocation(), diag::note_using_decl)
          << 0;
      return true;
    }

    // Check whether the two declarations might declare the same function or
    // function template.
    if (FunctionTemplateDecl *NewTemplate =
            New->getDescribedFunctionTemplate()) {
      if (checkUsingShadowRedecl<FunctionTemplateDecl>(*this, Shadow,
                                                       NewTemplate))
        return true;
      OldD = Old = cast<FunctionTemplateDecl>(Shadow->getTargetDecl())
                       ->getAsFunction();
    } else {
      if (checkUsingShadowRedecl<FunctionDecl>(*this, Shadow, New))
        return true;
      OldD = Old = cast<FunctionDecl>(Shadow->getTargetDecl());
    }
  } else {
    Diag(New->getLocation(), diag::err_redefinition_different_kind)
      << New->getDeclName();
    notePreviousDefinition(OldD, New->getLocation());
    return true;
  }
}

// If the old declaration was found in an inline namespace and the new
// declaration was qualified, update the DeclContext to match.
adjustDeclContextForDeclaratorDecl(New, Old);

// If the old declaration is invalid, just give up here.
if (Old->isInvalidDecl())
3
←
Assuming the condition is false→
4
←
Taking false branch→
  return true;

// Disallow redeclaration of some builtins.
if (!getASTContext().canBuiltinBeRedeclared(Old)) {
5
←
Assuming the condition is false→
6
←
Taking false branch→
  Diag(New->getLocation(), diag::err_builtin_redeclare) << Old->getDeclName();
  Diag(Old->getLocation(), diag::note_previous_builtin_declaration)
      << Old << Old->getType();
  return true;
}

diag::kind PrevDiag;
SourceLocation OldLocation;
std::tie(PrevDiag, OldLocation) =
    getNoteDiagForInvalidRedeclaration(Old, New);

// Don't complain about this if we're in GNU89 mode and the old function
// is an extern inline function.
// Don't complain about specializations. They are not supposed to have
// storage classes.
if (!isa<CXXMethodDecl>(New) && !isa<CXXMethodDecl>(Old) &&
7
←
Assuming 'New' is not a 'CXXMethodDecl'→
8
←
Assuming 'Old' is not a 'CXXMethodDecl'→
    New->getStorageClass() == SC_Static &&
9
←
Assuming the condition is false→
    Old->hasExternalFormalLinkage() &&
    !New->getTemplateSpecializationInfo() &&
    !canRedefineFunction(Old, getLangOpts())) {
  if (getLangOpts().MicrosoftExt) {
    Diag(New->getLocation(), diag::ext_static_non_static) << New;
    Diag(OldLocation, PrevDiag);
  } else {
    Diag(New->getLocation(), diag::err_static_non_static) << New;
    Diag(OldLocation, PrevDiag);
    return true;
  }
}

if (const auto *ILA9.1
'ILA' is null
 = New->getAttr<InternalLinkageAttr>())
10
←
Taking false branch→
  if (!Old->hasAttr<InternalLinkageAttr>()) {
    Diag(New->getLocation(), diag::err_attribute_missing_on_first_decl)
        << ILA;
    Diag(Old->getLocation(), diag::note_previous_declaration);
    New->dropAttr<InternalLinkageAttr>();
  }

if (auto *EA10.1
'EA' is null
 = New->getAttr<ErrorAttr>()) {
11
←
Taking false branch→
  if (!Old->hasAttr<ErrorAttr>()) {
    Diag(EA->getLocation(), diag::err_attribute_missing_on_first_decl) << EA;
    Diag(Old->getLocation(), diag::note_previous_declaration);
    New->dropAttr<ErrorAttr>();
  }
}

if (CheckRedeclarationInModule(New, Old))
12
←
Taking false branch→
  return true;

if (!getLangOpts().CPlusPlus) {
13
←
Assuming field 'CPlusPlus' is not equal to 0→
14
←
Taking false branch→
  bool OldOvl = Old->hasAttr<OverloadableAttr>();
  if (OldOvl != New->hasAttr<OverloadableAttr>() && !Old->isImplicit()) {
    Diag(New->getLocation(), diag::err_attribute_overloadable_mismatch)
      << New << OldOvl;

    // Try our best to find a decl that actually has the overloadable
    // attribute for the note. In most cases (e.g. programs with only one
    // broken declaration/definition), this won't matter.
    //
    // FIXME: We could do this if we juggled some extra state in
    // OverloadableAttr, rather than just removing it.
    const Decl *DiagOld = Old;
    if (OldOvl) {
      auto OldIter = llvm::find_if(Old->redecls(), [](const Decl *D) {
        const auto *A = D->getAttr<OverloadableAttr>();
        return A && !A->isImplicit();
      });
      // If we've implicitly added *all* of the overloadable attrs to this
      // chain, emitting a "previous redecl" note is pointless.
      DiagOld = OldIter == Old->redecls_end() ? nullptr : *OldIter;
    }

    if (DiagOld)
      Diag(DiagOld->getLocation(),
           diag::note_attribute_overloadable_prev_overload)
        << OldOvl;

    if (OldOvl)
      New->addAttr(OverloadableAttr::CreateImplicit(Context));
    else
      New->dropAttr<OverloadableAttr>();
  }
}

// If a function is first declared with a calling convention, but is later
// declared or defined without one, all following decls assume the calling
// convention of the first.
//
// It's OK if a function is first declared without a calling convention,
// but is later declared or defined with the default calling convention.
//
// To test if either decl has an explicit calling convention, we look for
// AttributedType sugar nodes on the type as written.  If they are missing or
// were canonicalized away, we assume the calling convention was implicit.
//
// Note also that we DO NOT return at this point, because we still have
// other tests to run.
QualType OldQType = Context.getCanonicalType(Old->getType());
QualType NewQType = Context.getCanonicalType(New->getType());
const FunctionType *OldType = cast<FunctionType>(OldQType);
const FunctionType *NewType = cast<FunctionType>(NewQType);
FunctionType::ExtInfo OldTypeInfo = OldType->getExtInfo();
FunctionType::ExtInfo NewTypeInfo = NewType->getExtInfo();
bool RequiresAdjustment = false;

if (OldTypeInfo.getCC() != NewTypeInfo.getCC()) {
15
←
Assuming the condition is false→
  FunctionDecl *First = Old->getFirstDecl();
  const FunctionType *FT =
      First->getType().getCanonicalType()->castAs<FunctionType>();
  FunctionType::ExtInfo FI = FT->getExtInfo();
  bool NewCCExplicit = getCallingConvAttributedType(New->getType());
  if (!NewCCExplicit) {
    // Inherit the CC from the previous declaration if it was specified
    // there but not here.
    NewTypeInfo = NewTypeInfo.withCallingConv(OldTypeInfo.getCC());
    RequiresAdjustment = true;
  } else if (Old->getBuiltinID()) {
    // Builtin attribute isn't propagated to the new one yet at this point,
    // so we check if the old one is a builtin.

    // Calling Conventions on a Builtin aren't really useful and setting a
    // default calling convention and cdecl'ing some builtin redeclarations is
    // common, so warn and ignore the calling convention on the redeclaration.
    Diag(New->getLocation(), diag::warn_cconv_unsupported)
        << FunctionType::getNameForCallConv(NewTypeInfo.getCC())
        << (int)CallingConventionIgnoredReason::BuiltinFunction;
    NewTypeInfo = NewTypeInfo.withCallingConv(OldTypeInfo.getCC());
    RequiresAdjustment = true;
  } else {
    // Calling conventions aren't compatible, so complain.
    bool FirstCCExplicit = getCallingConvAttributedType(First->getType());
    Diag(New->getLocation(), diag::err_cconv_change)
      << FunctionType::getNameForCallConv(NewTypeInfo.getCC())
      << !FirstCCExplicit
      << (!FirstCCExplicit ? "" :
          FunctionType::getNameForCallConv(FI.getCC()));

    // Put the note on the first decl, since it is the one that matters.
    Diag(First->getLocation(), diag::note_previous_declaration);
    return true;
  }
}

// FIXME: diagnose the other way around?
if (OldTypeInfo.getNoReturn() && !NewTypeInfo.getNoReturn()) {
16
←
Assuming the condition is false→
  NewTypeInfo = NewTypeInfo.withNoReturn(true);
  RequiresAdjustment = true;
}

// Merge regparm attribute.
if (OldTypeInfo.getHasRegParm() != NewTypeInfo.getHasRegParm() ||
17
←
Taking false branch→
    OldTypeInfo.getRegParm() != NewTypeInfo.getRegParm()) {
  if (NewTypeInfo.getHasRegParm()) {
    Diag(New->getLocation(), diag::err_regparm_mismatch)
      << NewType->getRegParmType()
      << OldType->getRegParmType();
    Diag(OldLocation, diag::note_previous_declaration);
    return true;
  }

  NewTypeInfo = NewTypeInfo.withRegParm(OldTypeInfo.getRegParm());
  RequiresAdjustment = true;
}

// Merge ns_returns_retained attribute.
if (OldTypeInfo.getProducesResult() != NewTypeInfo.getProducesResult()) {
18
←
Assuming the condition is false→
19
←
Taking false branch→
  if (NewTypeInfo.getProducesResult()) {
    Diag(New->getLocation(), diag::err_function_attribute_mismatch)
        << "'ns_returns_retained'";
    Diag(OldLocation, diag::note_previous_declaration);
    return true;
  }

  NewTypeInfo = NewTypeInfo.withProducesResult(true);
  RequiresAdjustment = true;
}

if (OldTypeInfo.getNoCallerSavedRegs() !=
20
←
Assuming the condition is false→
21
←
Taking false branch→
    NewTypeInfo.getNoCallerSavedRegs()) {
  if (NewTypeInfo.getNoCallerSavedRegs()) {
    AnyX86NoCallerSavedRegistersAttr *Attr =
      New->getAttr<AnyX86NoCallerSavedRegistersAttr>();
    Diag(New->getLocation(), diag::err_function_attribute_mismatch) << Attr;
    Diag(OldLocation, diag::note_previous_declaration);
    return true;
  }

  NewTypeInfo = NewTypeInfo.withNoCallerSavedRegs(true);
  RequiresAdjustment = true;
}

if (RequiresAdjustment21.1
'RequiresAdjustment' is false
) {
  const FunctionType *AdjustedType = New->getType()->getAs<FunctionType>();
  AdjustedType = Context.adjustFunctionType(AdjustedType, NewTypeInfo);
  New->setType(QualType(AdjustedType, 0));
  NewQType = Context.getCanonicalType(New->getType());
}

// If this redeclaration makes the function inline, we may need to add it to
// UndefinedButUsed.
if (!Old->isInlined() && New->isInlined() &&
22
←
Assuming the condition is false→
    !New->hasAttr<GNUInlineAttr>() &&
    !getLangOpts().GNUInline &&
    Old->isUsed(false) &&
    !Old->isDefined() && !New->isThisDeclarationADefinition())
  UndefinedButUsed.insert(std::make_pair(Old->getCanonicalDecl(),
                                         SourceLocation()));

// If this redeclaration makes it newly gnu_inline, we don't want to warn
// about it.
if (New->hasAttr<GNUInlineAttr>() &&
    Old->isInlined() && !Old->hasAttr<GNUInlineAttr>()) {
  UndefinedButUsed.erase(Old->getCanonicalDecl());
}

// If pass_object_size params don't match up perfectly, this isn't a valid
// redeclaration.
if (Old->getNumParams() > 0 && Old->getNumParams() == New->getNumParams() &&
23
←
Assuming the condition is false→
    !hasIdenticalPassObjectSizeAttrs(Old, New)) {
  Diag(New->getLocation(), diag::err_different_pass_object_size_params)
      << New->getDeclName();
  Diag(OldLocation, PrevDiag) << Old << Old->getType();
  return true;
}

if (getLangOpts().CPlusPlus23.1
Field 'CPlusPlus' is not equal to 0
) {
24
←
Taking true branch→
  // C++1z [over.load]p2
  //   Certain function declarations cannot be overloaded:
  //     -- Function declarations that differ only in the return type,
  //        the exception specification, or both cannot be overloaded.

  // Check the exception specifications match. This may recompute the type of
  // both Old and New if it resolved exception specifications, so grab the
  // types again after this. Because this updates the type, we do this before
  // any of the other checks below, which may update the "de facto" NewQType
  // but do not necessarily update the type of New.
  if (CheckEquivalentExceptionSpec(Old, New))
25
←
Assuming the condition is false→
26
←
Taking false branch→
    return true;
  OldQType = Context.getCanonicalType(Old->getType());
  NewQType = Context.getCanonicalType(New->getType());

  // Go back to the type source info to compare the declared return types,
  // per C++1y [dcl.type.auto]p13:
  //   Redeclarations or specializations of a function or function template
  //   with a declared return type that uses a placeholder type shall also
  //   use that placeholder, not a deduced type.
  QualType OldDeclaredReturnType = Old->getDeclaredReturnType();
  QualType NewDeclaredReturnType = New->getDeclaredReturnType();
  if (!Context.hasSameType(OldDeclaredReturnType, NewDeclaredReturnType) &&
27
←
Assuming the condition is false→
      canFullyTypeCheckRedeclaration(New, Old, NewDeclaredReturnType,
                                     OldDeclaredReturnType)) {
    QualType ResQT;
    if (NewDeclaredReturnType->isObjCObjectPointerType() &&
        OldDeclaredReturnType->isObjCObjectPointerType())
      // FIXME: This does the wrong thing for a deduced return type.
      ResQT = Context.mergeObjCGCQualifiers(NewQType, OldQType);
    if (ResQT.isNull()) {
      if (New->isCXXClassMember() && New->isOutOfLine())
        Diag(New->getLocation(), diag::err_member_def_does_not_match_ret_type)
            << New << New->getReturnTypeSourceRange();
      else
        Diag(New->getLocation(), diag::err_ovl_diff_return_type)
            << New->getReturnTypeSourceRange();
      Diag(OldLocation, PrevDiag) << Old << Old->getType()
                                  << Old->getReturnTypeSourceRange();
      return true;
    }
    else
      NewQType = ResQT;
  }

  QualType OldReturnType = OldType->getReturnType();
  QualType NewReturnType = cast<FunctionType>(NewQType)->getReturnType();
  if (OldReturnType != NewReturnType) {
28
←
Taking false branch→
    // If this function has a deduced return type and has already been
    // defined, copy the deduced value from the old declaration.
    AutoType *OldAT = Old->getReturnType()->getContainedAutoType();
    if (OldAT && OldAT->isDeduced()) {
      QualType DT = OldAT->getDeducedType();
      if (DT.isNull()) {
        New->setType(SubstAutoTypeDependent(New->getType()));
        NewQType = Context.getCanonicalType(SubstAutoTypeDependent(NewQType));
      } else {
        New->setType(SubstAutoType(New->getType(), DT));
        NewQType = Context.getCanonicalType(SubstAutoType(NewQType, DT));
      }
    }
  }

  const CXXMethodDecl *OldMethod = dyn_cast<CXXMethodDecl>(Old);
29
←
Assuming 'Old' is not a 'CastReturnType'→
  CXXMethodDecl *NewMethod = dyn_cast<CXXMethodDecl>(New);
30
←
Assuming 'New' is not a 'CastReturnType'→
  if (OldMethod30.1
'OldMethod' is null
 && NewMethod) {
    // Preserve triviality.
    NewMethod->setTrivial(OldMethod->isTrivial());

    // MSVC allows explicit template specialization at class scope:
    // 2 CXXMethodDecls referring to the same function will be injected.
    // We don't want a redeclaration error.
    bool IsClassScopeExplicitSpecialization =
                            OldMethod->isFunctionTemplateSpecialization() &&
                            NewMethod->isFunctionTemplateSpecialization();
    bool isFriend = NewMethod->getFriendObjectKind();

    if (!isFriend && NewMethod->getLexicalDeclContext()->isRecord() &&
        !IsClassScopeExplicitSpecialization) {
      //    -- Member function declarations with the same name and the
      //       same parameter types cannot be overloaded if any of them
      //       is a static member function declaration.
      if (OldMethod->isStatic() != NewMethod->isStatic()) {
        Diag(New->getLocation(), diag::err_ovl_static_nonstatic_member);
        Diag(OldLocation, PrevDiag) << Old << Old->getType();
        return true;
      }

      // C++ [class.mem]p1:
      //   [...] A member shall not be declared twice in the
      //   member-specification, except that a nested class or member
      //   class template can be declared and then later defined.
      if (!inTemplateInstantiation()) {
        unsigned NewDiag;
        if (isa<CXXConstructorDecl>(OldMethod))
          NewDiag = diag::err_constructor_redeclared;
        else if (isa<CXXDestructorDecl>(NewMethod))
          NewDiag = diag::err_destructor_redeclared;
        else if (isa<CXXConversionDecl>(NewMethod))
          NewDiag = diag::err_conv_function_redeclared;
        else
          NewDiag = diag::err_member_redeclared;

        Diag(New->getLocation(), NewDiag);
      } else {
        Diag(New->getLocation(), diag::err_member_redeclared_in_instantiation)
          << New << New->getType();
      }
      Diag(OldLocation, PrevDiag) << Old << Old->getType();
      return true;

    // Complain if this is an explicit declaration of a special
    // member that was initially declared implicitly.
    //
    // As an exception, it's okay to befriend such methods in order
    // to permit the implicit constructor/destructor/operator calls.
    } else if (OldMethod->isImplicit()) {
      if (isFriend) {
        NewMethod->setImplicit();
      } else {
        Diag(NewMethod->getLocation(),
             diag::err_definition_of_implicitly_declared_member)
          << New << getSpecialMember(OldMethod);
        return true;
      }
    } else if (OldMethod->getFirstDecl()->isExplicitlyDefaulted() && !isFriend) {
      Diag(NewMethod->getLocation(),
           diag::err_definition_of_explicitly_defaulted_member)
        << getSpecialMember(OldMethod);
      return true;
    }
  }

  // C++11 [dcl.attr.noreturn]p1:
  //   The first declaration of a function shall specify the noreturn
  //   attribute if any declaration of that function specifies the noreturn
  //   attribute.
  if (const auto *NRA30.2
'NRA' is null
 = New->getAttr<CXX11NoReturnAttr>())
31
←
Taking false branch→
    if (!Old->hasAttr<CXX11NoReturnAttr>()) {
      Diag(NRA->getLocation(), diag::err_attribute_missing_on_first_decl)
          << NRA;
      Diag(Old->getLocation(), diag::note_previous_declaration);
    }

  // C++11 [dcl.attr.depend]p2:
  //   The first declaration of a function shall specify the
  //   carries_dependency attribute for its declarator-id if any declaration
  //   of the function specifies the carries_dependency attribute.
  const CarriesDependencyAttr *CDA = New->getAttr<CarriesDependencyAttr>();
  if (CDA31.1
'CDA' is null
 && !Old->hasAttr<CarriesDependencyAttr>()) {
    Diag(CDA->getLocation(),
         diag::err_carries_dependency_missing_on_first_decl) << 0/*Function*/;
    Diag(Old->getFirstDecl()->getLocation(),
         diag::note_carries_dependency_missing_first_decl) << 0/*Function*/;
  }

  // (C++98 8.3.5p3):
  //   All declarations for a function shall agree exactly in both the
  //   return type and the parameter-type-list.
  // We also want to respect all the extended bits except noreturn.

  // noreturn should now match unless the old type info didn't have it.
  QualType OldQTypeForComparison = OldQType;
  if (!OldTypeInfo.getNoReturn() && NewTypeInfo.getNoReturn()) {
32
←
Assuming the condition is false→
33
←
Taking false branch→
    auto *OldType = OldQType->castAs<FunctionProtoType>();
    const FunctionType *OldTypeForComparison
      = Context.adjustFunctionType(OldType, OldTypeInfo.withNoReturn(true));
    OldQTypeForComparison = QualType(OldTypeForComparison, 0);
    assert(OldQTypeForComparison.isCanonical())(static_cast <bool> (OldQTypeForComparison.isCanonical(
)) ? void (0) : __assert_fail ("OldQTypeForComparison.isCanonical()"
, "clang/lib/Sema/SemaDecl.cpp", 4064, __extension__ __PRETTY_FUNCTION__
));
  }

  if (haveIncompatibleLanguageLinkages(Old, New)) {
34
←
Taking false branch→
    // As a special case, retain the language linkage from previous
    // declarations of a friend function as an extension.
    //
    // This liberal interpretation of C++ [class.friend]p3 matches GCC/MSVC
    // and is useful because there's otherwise no way to specify language
    // linkage within class scope.
    //
    // Check cautiously as the friend object kind isn't yet complete.
    if (New->getFriendObjectKind() != Decl::FOK_None) {
      Diag(New->getLocation(), diag::ext_retained_language_linkage) << New;
      Diag(OldLocation, PrevDiag);
    } else {
      Diag(New->getLocation(), diag::err_different_language_linkage) << New;
      Diag(OldLocation, PrevDiag);
      return true;
    }
  }

  // If the function types are compatible, merge the declarations. Ignore the
  // exception specifier because it was already checked above in
  // CheckEquivalentExceptionSpec, and we don't want follow-on diagnostics
  // about incompatible types under -fms-compatibility.
  if (Context.hasSameFunctionTypeIgnoringExceptionSpec(OldQTypeForComparison,
35
←
Assuming the condition is false→
36
←
Taking false branch→
                                                       NewQType))
    return MergeCompatibleFunctionDecls(New, Old, S, MergeTypeWithOld);

  // If the types are imprecise (due to dependent constructs in friends or
  // local extern declarations), it's OK if they differ. We'll check again
  // during instantiation.
  if (!canFullyTypeCheckRedeclaration(New, Old, NewQType, OldQType))
37
←
Taking false branch→
    return false;

  // Fall through for conflicting redeclarations and redefinitions.
}

// C: Function types need to be compatible, not identical. This handles
// duplicate function decls like "void f(int); void f(enum X);" properly.
if (!getLangOpts().CPlusPlus) {
38
←
Assuming field 'CPlusPlus' is 0→
  // C99 6.7.5.3p15: ...If one type has a parameter type list and the other
  // type is specified by a function definition that contains a (possibly
  // empty) identifier list, both shall agree in the number of parameters
  // and the type of each parameter shall be compatible with the type that
  // results from the application of default argument promotions to the
  // type of the corresponding identifier. ...
  // This cannot be handled by ASTContext::typesAreCompatible() because that
  // doesn't know whether the function type is for a definition or not when
  // eventually calling ASTContext::mergeFunctionTypes(). The only situation
  // we need to cover here is that the number of arguments agree as the
  // default argument promotion rules were already checked by
  // ASTContext::typesAreCompatible().
  if (Old->hasPrototype() && !New->hasWrittenPrototype() && NewDeclIsDefn &&
39
←
Assuming the condition is false→
      Old->getNumParams() != New->getNumParams() && !Old->isImplicit()) {
    if (Old->hasInheritedPrototype())
      Old = Old->getCanonicalDecl();
    Diag(New->getLocation(), diag::err_conflicting_types) << New;
    Diag(Old->getLocation(), PrevDiag) << Old << Old->getType();
    return true;
  }

  // If we are merging two functions where only one of them has a prototype,
  // we may have enough information to decide to issue a diagnostic that the
  // function without a protoype will change behavior in C2x. This handles
  // cases like:
  //   void i(); void i(int j);
  //   void i(int j); void i();
  //   void i(); void i(int j) {}
  // See ActOnFinishFunctionBody() for other cases of the behavior change
  // diagnostic. See GetFullTypeForDeclarator() for handling of a function
  // type without a prototype.
  if (New->hasWrittenPrototype() != Old->hasWrittenPrototype() &&
40
←
Assuming the condition is false→
      !New->isImplicit() && !Old->isImplicit()) {
    const FunctionDecl *WithProto, *WithoutProto;
    if (New->hasWrittenPrototype()) {
      WithProto = New;
      WithoutProto = Old;
    } else {
      WithProto = Old;
      WithoutProto = New;
    }

    if (WithProto->getNumParams() != 0) {
      if (WithoutProto->getBuiltinID() == 0 && !WithoutProto->isImplicit()) {
        // The one without the prototype will be changing behavior in C2x, so
        // warn about that one so long as it's a user-visible declaration.
        bool IsWithoutProtoADef = false, IsWithProtoADef = false;
        if (WithoutProto == New)
          IsWithoutProtoADef = NewDeclIsDefn;
        else
          IsWithProtoADef = NewDeclIsDefn;
        Diag(WithoutProto->getLocation(),
             diag::warn_non_prototype_changes_behavior)
            << IsWithoutProtoADef << (WithoutProto->getNumParams() ? 0 : 1)
            << (WithoutProto == Old) << IsWithProtoADef;

        // The reason the one without the prototype will be changing behavior
        // is because of the one with the prototype, so note that so long as
        // it's a user-visible declaration. There is one exception to this:
        // when the new declaration is a definition without a prototype, the
        // old declaration with a prototype is not the cause of the issue,
        // and that does not need to be noted because the one with a
        // prototype will not change behavior in C2x.
        if (WithProto->getBuiltinID() == 0 && !WithProto->isImplicit() &&
            !IsWithoutProtoADef)
          Diag(WithProto->getLocation(), diag::note_conflicting_prototype);
      }
    }
  }

  if (Context.typesAreCompatible(OldQType, NewQType)) {
41
←
Assuming the condition is true→
42
←
Taking true branch→
    const FunctionType *OldFuncType = OldQType->getAs<FunctionType>();
43
←
Assuming the object is not a 'const class clang::FunctionType *'→
    const FunctionType *NewFuncType = NewQType->getAs<FunctionType>();
44
←
Assuming the object is not a 'const class clang::FunctionType *'→
45
←
'NewFuncType' initialized to a null pointer value→
    const FunctionProtoType *OldProto = nullptr;
    if (MergeTypeWithOld && isa<FunctionNoProtoType>(NewFuncType) &&
46
←
Assuming 'MergeTypeWithOld' is true→
47
←
Assuming 'NewFuncType' is a 'class clang::FunctionNoProtoType &'→
        (OldProto = dyn_cast<FunctionProtoType>(OldFuncType))) {
48
←
Assuming 'OldProto' is non-null→
      // The old declaration provided a function prototype, but the
      // new declaration does not. Merge in the prototype.
      assert(!OldProto->hasExceptionSpec() && "Exception spec in C")(static_cast <bool> (!OldProto->hasExceptionSpec() &&
 "Exception spec in C") ? void (0) : __assert_fail ("!OldProto->hasExceptionSpec() && \"Exception spec in C\""
, "clang/lib/Sema/SemaDecl.cpp", 4184, __extension__ __PRETTY_FUNCTION__
));
49
←
Taking true branch→
50
←
'?' condition is true→
      NewQType = Context.getFunctionType(NewFuncType->getReturnType(),
51
←
Called C++ object pointer is null
                                         OldProto->getParamTypes(),
                                         OldProto->getExtProtoInfo());
      New->setType(NewQType);
      New->setHasInheritedPrototype();

      // Synthesize parameters with the same types.
      SmallVector<ParmVarDecl *, 16> Params;
      for (const auto &ParamType : OldProto->param_types()) {
        ParmVarDecl *Param = ParmVarDecl::Create(
            Context, New, SourceLocation(), SourceLocation(), nullptr,
            ParamType, /*TInfo=*/nullptr, SC_None, nullptr);
        Param->setScopeInfo(0, Params.size());
        Param->setImplicit();
        Params.push_back(Param);
      }

      New->setParams(Params);
    }

    return MergeCompatibleFunctionDecls(New, Old, S, MergeTypeWithOld);
  }
}

// Check if the function types are compatible when pointer size address
// spaces are ignored.
if (Context.hasSameFunctionTypeIgnoringPtrSizes(OldQType, NewQType))
  return false;

// GNU C permits a K&R definition to follow a prototype declaration
// if the declared types of the parameters in the K&R definition
// match the types in the prototype declaration, even when the
// promoted types of the parameters from the K&R definition differ
// from the types in the prototype. GCC then keeps the types from
// the prototype.
//
// If a variadic prototype is followed by a non-variadic K&R definition,
// the K&R definition becomes variadic.  This is sort of an edge case, but
// it's legal per the standard depending on how you read C99 6.7.5.3p15 and
// C99 6.9.1p8.
if (!getLangOpts().CPlusPlus &&
    Old->hasPrototype() && !New->hasPrototype() &&
    New->getType()->getAs<FunctionProtoType>() &&
    Old->getNumParams() == New->getNumParams()) {
  SmallVector<QualType, 16> ArgTypes;
  SmallVector<GNUCompatibleParamWarning, 16> Warnings;
  const FunctionProtoType *OldProto
    = Old->getType()->getAs<FunctionProtoType>();
  const FunctionProtoType *NewProto
    = New->getType()->getAs<FunctionProtoType>();

  // Determine whether this is the GNU C extension.
  QualType MergedReturn = Context.mergeTypes(OldProto->getReturnType(),
                                             NewProto->getReturnType());
  bool LooseCompatible = !MergedReturn.isNull();
  for (unsigned Idx = 0, End = Old->getNumParams();
       LooseCompatible && Idx != End; ++Idx) {
    ParmVarDecl *OldParm = Old->getParamDecl(Idx);
    ParmVarDecl *NewParm = New->getParamDecl(Idx);
    if (Context.typesAreCompatible(OldParm->getType(),
                                   NewProto->getParamType(Idx))) {
      ArgTypes.push_back(NewParm->getType());
    } else if (Context.typesAreCompatible(OldParm->getType(),
                                          NewParm->getType(),
                                          /*CompareUnqualified=*/true)) {
      GNUCompatibleParamWarning Warn = { OldParm, NewParm,
                                         NewProto->getParamType(Idx) };
      Warnings.push_back(Warn);
      ArgTypes.push_back(NewParm->getType());
    } else
      LooseCompatible = false;
  }

  if (LooseCompatible) {
    for (unsigned Warn = 0; Warn < Warnings.size(); ++Warn) {
      Diag(Warnings[Warn].NewParm->getLocation(),
           diag::ext_param_promoted_not_compatible_with_prototype)
        << Warnings[Warn].PromotedType
        << Warnings[Warn].OldParm->getType();
      if (Warnings[Warn].OldParm->getLocation().isValid())
        Diag(Warnings[Warn].OldParm->getLocation(),
             diag::note_previous_declaration);
    }

    if (MergeTypeWithOld)
      New->setType(Context.getFunctionType(MergedReturn, ArgTypes,
                                           OldProto->getExtProtoInfo()));
    return MergeCompatibleFunctionDecls(New, Old, S, MergeTypeWithOld);
  }

  // Fall through to diagnose conflicting types.
}

// A function that has already been declared has been redeclared or
// defined with a different type; show an appropriate diagnostic.

// If the previous declaration was an implicitly-generated builtin
// declaration, then at the very least we should use a specialized note.
unsigned BuiltinID;
if (Old->isImplicit() && (BuiltinID = Old->getBuiltinID())) {
  // If it's actually a library-defined builtin function like 'malloc'
  // or 'printf', just warn about the incompatible redeclaration.
  if (Context.BuiltinInfo.isPredefinedLibFunction(BuiltinID)) {
    Diag(New->getLocation(), diag::warn_redecl_library_builtin) << New;
    Diag(OldLocation, diag::note_previous_builtin_declaration)
      << Old << Old->getType();
    return false;
  }

  PrevDiag = diag::note_previous_builtin_declaration;
}

Diag(New->getLocation(), diag::err_conflicting_types) << New->getDeclName();
Diag(OldLocation, PrevDiag) << Old << Old->getType();
return true;
4300}

4302/// Completes the merge of two function declarations that are
4303/// known to be compatible.
4304///
4305/// This routine handles the merging of attributes and other
4306/// properties of function declarations from the old declaration to
4307/// the new declaration, once we know that New is in fact a
4308/// redeclaration of Old.
4309///
4310/// \returns false
4311bool Sema::MergeCompatibleFunctionDecls(FunctionDecl *New, FunctionDecl *Old,
                                      Scope *S, bool MergeTypeWithOld) {
// Merge the attributes
mergeDeclAttributes(New, Old);

// Merge "pure" flag.
if (Old->isPure())
  New->setPure();

// Merge "used" flag.
if (Old->getMostRecentDecl()->isUsed(false))
  New->setIsUsed();

// Merge attributes from the parameters.  These can mismatch with K&R
// declarations.
if (New->getNumParams() == Old->getNumParams())
    for (unsigned i = 0, e = New->getNumParams(); i != e; ++i) {
      ParmVarDecl *NewParam = New->getParamDecl(i);
      ParmVarDecl *OldParam = Old->getParamDecl(i);
      mergeParamDeclAttributes(NewParam, OldParam, *this);
      mergeParamDeclTypes(NewParam, OldParam, *this);
    }

if (getLangOpts().CPlusPlus)
  return MergeCXXFunctionDecl(New, Old, S);

// Merge the function types so the we get the composite types for the return
// and argument types. Per C11 6.2.7/4, only update the type if the old decl
// was visible.
QualType Merged = Context.mergeTypes(Old->getType(), New->getType());
if (!Merged.isNull() && MergeTypeWithOld)
  New->setType(Merged);

return false;
4345}

4347void Sema::mergeObjCMethodDecls(ObjCMethodDecl *newMethod,
                              ObjCMethodDecl *oldMethod) {
// Merge the attributes, including deprecated/unavailable
AvailabilityMergeKind MergeKind =
    isa<ObjCProtocolDecl>(oldMethod->getDeclContext())
        ? (oldMethod->isOptional() ? AMK_OptionalProtocolImplementation
                                   : AMK_ProtocolImplementation)
        : isa<ObjCImplDecl>(newMethod->getDeclContext()) ? AMK_Redeclaration
                                                         : AMK_Override;

mergeDeclAttributes(newMethod, oldMethod, MergeKind);

// Merge attributes from the parameters.
ObjCMethodDecl::param_const_iterator oi = oldMethod->param_begin(),
                                     oe = oldMethod->param_end();
for (ObjCMethodDecl::param_iterator
       ni = newMethod->param_begin(), ne = newMethod->param_end();
     ni != ne && oi != oe; ++ni, ++oi)
  mergeParamDeclAttributes(*ni, *oi, *this);

CheckObjCMethodOverride(newMethod, oldMethod);
4368}

4370static void diagnoseVarDeclTypeMismatch(Sema &S, VarDecl *New, VarDecl* Old) {
assert(!S.Context.hasSameType(New->getType(), Old->getType()))(static_cast <bool> (!S.Context.hasSameType(New->getType
(), Old->getType())) ? void (0) : __assert_fail ("!S.Context.hasSameType(New->getType(), Old->getType())"
, "clang/lib/Sema/SemaDecl.cpp", 4371, __extension__ __PRETTY_FUNCTION__
));

S.Diag(New->getLocation(), New->isThisDeclarationADefinition()
       ? diag::err_redefinition_different_type
       : diag::err_redeclaration_different_type)
  << New->getDeclName() << New->getType() << Old->getType();

diag::kind PrevDiag;
SourceLocation OldLocation;
std::tie(PrevDiag, OldLocation)
  = getNoteDiagForInvalidRedeclaration(Old, New);
S.Diag(OldLocation, PrevDiag);
New->setInvalidDecl();
4384}

4386/// MergeVarDeclTypes - We parsed a variable 'New' which has the same name and
4387/// scope as a previous declaration 'Old'.  Figure out how to merge their types,
4388/// emitting diagnostics as appropriate.
4389///
4390/// Declarations using the auto type specifier (C++ [decl.spec.auto]) call back
4391/// to here in AddInitializerToDecl. We can't check them before the initializer
4392/// is attached.
4393void Sema::MergeVarDeclTypes(VarDecl *New, VarDecl *Old,
                           bool MergeTypeWithOld) {
if (New->isInvalidDecl() || Old->isInvalidDecl())
  return;

QualType MergedT;
if (getLangOpts().CPlusPlus) {
  if (New->getType()->isUndeducedType()) {
    // We don't know what the new type is until the initializer is attached.
    return;
  } else if (Context.hasSameType(New->getType(), Old->getType())) {
    // These could still be something that needs exception specs checked.
    return MergeVarDeclExceptionSpecs(New, Old);
  }
  // C++ [basic.link]p10:
  //   [...] the types specified by all declarations referring to a given
  //   object or function shall be identical, except that declarations for an
  //   array object can specify array types that differ by the presence or
  //   absence of a major array bound (8.3.4).
  else if (Old->getType()->isArrayType() && New->getType()->isArrayType()) {
    const ArrayType *OldArray = Context.getAsArrayType(Old->getType());
    const ArrayType *NewArray = Context.getAsArrayType(New->getType());

    // We are merging a variable declaration New into Old. If it has an array
    // bound, and that bound differs from Old's bound, we should diagnose the
    // mismatch.
    if (!NewArray->isIncompleteArrayType() && !NewArray->isDependentType()) {
      for (VarDecl *PrevVD = Old->getMostRecentDecl(); PrevVD;
           PrevVD = PrevVD->getPreviousDecl()) {
        QualType PrevVDTy = PrevVD->getType();
        if (PrevVDTy->isIncompleteArrayType() || PrevVDTy->isDependentType())
          continue;

        if (!Context.hasSameType(New->getType(), PrevVDTy))
          return diagnoseVarDeclTypeMismatch(*this, New, PrevVD);
      }
    }

    if (OldArray->isIncompleteArrayType() && NewArray->isArrayType()) {
      if (Context.hasSameType(OldArray->getElementType(),
                              NewArray->getElementType()))
        MergedT = New->getType();
    }
    // FIXME: Check visibility. New is hidden but has a complete type. If New
    // has no array bound, it should not inherit one from Old, if Old is not
    // visible.
    else if (OldArray->isArrayType() && NewArray->isIncompleteArrayType()) {
      if (Context.hasSameType(OldArray->getElementType(),
                              NewArray->getElementType()))
        MergedT = Old->getType();
    }
  }
  else if (New->getType()->isObjCObjectPointerType() &&
             Old->getType()->isObjCObjectPointerType()) {
    MergedT = Context.mergeObjCGCQualifiers(New->getType(),
                                            Old->getType());
  }
} else {
  // C 6.2.7p2:
  //   All declarations that refer to the same object or function shall have
  //   compatible type.
  MergedT = Context.mergeTypes(New->getType(), Old->getType());
}
if (MergedT.isNull()) {
  // It's OK if we couldn't merge types if either type is dependent, for a
  // block-scope variable. In other cases (static data members of class
  // templates, variable templates, ...), we require the types to be
  // equivalent.
  // FIXME: The C++ standard doesn't say anything about this.
  if ((New->getType()->isDependentType() ||
       Old->getType()->isDependentType()) && New->isLocalVarDecl()) {
    // If the old type was dependent, we can't merge with it, so the new type
    // becomes dependent for now. We'll reproduce the original type when we
    // instantiate the TypeSourceInfo for the variable.
    if (!New->getType()->isDependentType() && MergeTypeWithOld)
      New->setType(Context.DependentTy);
    return;
  }
  return diagnoseVarDeclTypeMismatch(*this, New, Old);
}

// Don't actually update the type on the new declaration if the old
// declaration was an extern declaration in a different scope.
if (MergeTypeWithOld)
  New->setType(MergedT);
4478}

4480static bool mergeTypeWithPrevious(Sema &S, VarDecl *NewVD, VarDecl *OldVD,
                                LookupResult &Previous) {
// C11 6.2.7p4:
//   For an identifier with internal or external linkage declared
//   in a scope in which a prior declaration of that identifier is
//   visible, if the prior declaration specifies internal or
//   external linkage, the type of the identifier at the later
//   declaration becomes the composite type.
//
// If the variable isn't visible, we do not merge with its type.
if (Previous.isShadowed())
  return false;

if (S.getLangOpts().CPlusPlus) {
  // C++11 [dcl.array]p3:
  //   If there is a preceding declaration of the entity in the same
  //   scope in which the bound was specified, an omitted array bound
  //   is taken to be the same as in that earlier declaration.
  return NewVD->isPreviousDeclInSameBlockScope() ||
         (!OldVD->getLexicalDeclContext()->isFunctionOrMethod() &&
          !NewVD->getLexicalDeclContext()->isFunctionOrMethod());
} else {
  // If the old declaration was function-local, don't merge with its
  // type unless we're in the same function.
  return !OldVD->getLexicalDeclContext()->isFunctionOrMethod() ||
         OldVD->getLexicalDeclContext() == NewVD->getLexicalDeclContext();
}
4507}

4509/// MergeVarDecl - We just parsed a variable 'New' which has the same name
4510/// and scope as a previous declaration 'Old'.  Figure out how to resolve this
4511/// situation, merging decls or emitting diagnostics as appropriate.
4512///
4513/// Tentative definition rules (C99 6.9.2p2) are checked by
4514/// FinalizeDeclaratorGroup. Unfortunately, we can't analyze tentative
4515/// definitions here, since the initializer hasn't been attached.
4516///
4517void Sema::MergeVarDecl(VarDecl *New, LookupResult &Previous) {
// If the new decl is already invalid, don't do any other checking.
if (New->isInvalidDecl())
  return;

if (!shouldLinkPossiblyHiddenDecl(Previous, New))
  return;

VarTemplateDecl *NewTemplate = New->getDescribedVarTemplate();

// Verify the old decl was also a variable or variable template.
VarDecl *Old = nullptr;
VarTemplateDecl *OldTemplate = nullptr;
if (Previous.isSingleResult()) {
  if (NewTemplate) {
    OldTemplate = dyn_cast<VarTemplateDecl>(Previous.getFoundDecl());
    Old = OldTemplate ? OldTemplate->getTemplatedDecl() : nullptr;

    if (auto *Shadow =
            dyn_cast<UsingShadowDecl>(Previous.getRepresentativeDecl()))
      if (checkUsingShadowRedecl<VarTemplateDecl>(*this, Shadow, NewTemplate))
        return New->setInvalidDecl();
  } else {
    Old = dyn_cast<VarDecl>(Previous.getFoundDecl());

    if (auto *Shadow =
            dyn_cast<UsingShadowDecl>(Previous.getRepresentativeDecl()))
      if (checkUsingShadowRedecl<VarDecl>(*this, Shadow, New))
        return New->setInvalidDecl();
  }
}
if (!Old) {
  Diag(New->getLocation(), diag::err_redefinition_different_kind)
      << New->getDeclName();
  notePreviousDefinition(Previous.getRepresentativeDecl(),
                         New->getLocation());
  return New->setInvalidDecl();
}

// If the old declaration was found in an inline namespace and the new
// declaration was qualified, update the DeclContext to match.
adjustDeclContextForDeclaratorDecl(New, Old);

// Ensure the template parameters are compatible.
if (NewTemplate &&
    !TemplateParameterListsAreEqual(NewTemplate->getTemplateParameters(),
                                    OldTemplate->getTemplateParameters(),
                                    /*Complain=*/true, TPL_TemplateMatch))
  return New->setInvalidDecl();

// C++ [class.mem]p1:
//   A member shall not be declared twice in the member-specification [...]
//
// Here, we need only consider static data members.
if (Old->isStaticDataMember() && !New->isOutOfLine()) {
  Diag(New->getLocation(), diag::err_duplicate_member)
    << New->getIdentifier();
  Diag(Old->getLocation(), diag::note_previous_declaration);
  New->setInvalidDecl();
}

mergeDeclAttributes(New, Old);
// Warn if an already-declared variable is made a weak_import in a subsequent
// declaration
if (New->hasAttr<WeakImportAttr>() &&
    Old->getStorageClass() == SC_None &&
    !Old->hasAttr<WeakImportAttr>()) {
  Diag(New->getLocation(), diag::warn_weak_import) << New->getDeclName();
  Diag(Old->getLocation(), diag::note_previous_declaration);
  // Remove weak_import attribute on new declaration.
  New->dropAttr<WeakImportAttr>();
}

if (const auto *ILA = New->getAttr<InternalLinkageAttr>())
  if (!Old->hasAttr<InternalLinkageAttr>()) {
    Diag(New->getLocation(), diag::err_attribute_missing_on_first_decl)
        << ILA;
    Diag(Old->getLocation(), diag::note_previous_declaration);
    New->dropAttr<InternalLinkageAttr>();
  }

// Merge the types.
VarDecl *MostRecent = Old->getMostRecentDecl();
if (MostRecent != Old) {
  MergeVarDeclTypes(New, MostRecent,
                    mergeTypeWithPrevious(*this, New, MostRecent, Previous));
  if (New->isInvalidDecl())
    return;
}

MergeVarDeclTypes(New, Old, mergeTypeWithPrevious(*this, New, Old, Previous));
if (New->isInvalidDecl())
  return;

diag::kind PrevDiag;
SourceLocation OldLocation;
std::tie(PrevDiag, OldLocation) =
    getNoteDiagForInvalidRedeclaration(Old, New);

// [dcl.stc]p8: Check if we have a non-static decl followed by a static.
if (New->getStorageClass() == SC_Static &&
    !New->isStaticDataMember() &&
    Old->hasExternalFormalLinkage()) {
  if (getLangOpts().MicrosoftExt) {
    Diag(New->getLocation(), diag::ext_static_non_static)
        << New->getDeclName();
    Diag(OldLocation, PrevDiag);
  } else {
    Diag(New->getLocation(), diag::err_static_non_static)
        << New->getDeclName();
    Diag(OldLocation, PrevDiag);
    return New->setInvalidDecl();
  }
}
// C99 6.2.2p4:
//   For an identifier declared with the storage-class specifier
//   extern in a scope in which a prior declaration of that
//   identifier is visible,23) if the prior declaration specifies
//   internal or external linkage, the linkage of the identifier at
//   the later declaration is the same as the linkage specified at
//   the prior declaration. If no prior declaration is visible, or
//   if the prior declaration specifies no linkage, then the
//   identifier has external linkage.
if (New->hasExternalStorage() && Old->hasLinkage())
  /* Okay */;
else if (New->getCanonicalDecl()->getStorageClass() != SC_Static &&
         !New->isStaticDataMember() &&
         Old->getCanonicalDecl()->getStorageClass() == SC_Static) {
  Diag(New->getLocation(), diag::err_non_static_static) << New->getDeclName();
  Diag(OldLocation, PrevDiag);
  return New->setInvalidDecl();
}

// Check if extern is followed by non-extern and vice-versa.
if (New->hasExternalStorage() &&
    !Old->hasLinkage() && Old->isLocalVarDeclOrParm()) {
  Diag(New->getLocation(), diag::err_extern_non_extern) << New->getDeclName();
  Diag(OldLocation, PrevDiag);
  return New->setInvalidDecl();
}
if (Old->hasLinkage() && New->isLocalVarDeclOrParm() &&
    !New->hasExternalStorage()) {
  Diag(New->getLocation(), diag::err_non_extern_extern) << New->getDeclName();
  Diag(OldLocation, PrevDiag);
  return New->setInvalidDecl();
}

if (CheckRedeclarationInModule(New, Old))
  return;

// Variables with external linkage are analyzed in FinalizeDeclaratorGroup.

// FIXME: The test for external storage here seems wrong? We still
// need to check for mismatches.
if (!New->hasExternalStorage() && !New->isFileVarDecl() &&
    // Don't complain about out-of-line definitions of static members.
    !(Old->getLexicalDeclContext()->isRecord() &&
      !New->getLexicalDeclContext()->isRecord())) {
  Diag(New->getLocation(), diag::err_redefinition) << New->getDeclName();
  Diag(OldLocation, PrevDiag);
  return New->setInvalidDecl();
}

if (New->isInline() && !Old->getMostRecentDecl()->isInline()) {
  if (VarDecl *Def = Old->getDefinition()) {
    // C++1z [dcl.fcn.spec]p4:
    //   If the definition of a variable appears in a translation unit before
    //   its first declaration as inline, the program is ill-formed.
    Diag(New->getLocation(), diag::err_inline_decl_follows_def) << New;
    Diag(Def->getLocation(), diag::note_previous_definition);
  }
}

// If this redeclaration makes the variable inline, we may need to add it to
// UndefinedButUsed.
if (!Old->isInline() && New->isInline() && Old->isUsed(false) &&
    !Old->getDefinition() && !New->isThisDeclarationADefinition())
  UndefinedButUsed.insert(std::make_pair(Old->getCanonicalDecl(),
                                         SourceLocation()));

if (New->getTLSKind() != Old->getTLSKind()) {
  if (!Old->getTLSKind()) {
    Diag(New->getLocation(), diag::err_thread_non_thread) << New->getDeclName();
    Diag(OldLocation, PrevDiag);
  } else if (!New->getTLSKind()) {
    Diag(New->getLocation(), diag::err_non_thread_thread) << New->getDeclName();
    Diag(OldLocation, PrevDiag);
  } else {
    // Do not allow redeclaration to change the variable between requiring
    // static and dynamic initialization.
    // FIXME: GCC allows this, but uses the TLS keyword on the first
    // declaration to determine the kind. Do we need to be compatible here?
    Diag(New->getLocation(), diag::err_thread_thread_different_kind)
      << New->getDeclName() << (New->getTLSKind() == VarDecl::TLS_Dynamic);
    Diag(OldLocation, PrevDiag);
  }
}

// C++ doesn't have tentative definitions, so go right ahead and check here.
if (getLangOpts().CPlusPlus) {
  if (Old->isStaticDataMember() && Old->getCanonicalDecl()->isInline() &&
      Old->getCanonicalDecl()->isConstexpr()) {
    // This definition won't be a definition any more once it's been merged.
    Diag(New->getLocation(),
         diag::warn_deprecated_redundant_constexpr_static_def);
  } else if (New->isThisDeclarationADefinition() == VarDecl::Definition) {
    VarDecl *Def = Old->getDefinition();
    if (Def && checkVarDeclRedefinition(Def, New))
      return;
  }
}

if (haveIncompatibleLanguageLinkages(Old, New)) {
  Diag(New->getLocation(), diag::err_different_language_linkage) << New;
  Diag(OldLocation, PrevDiag);
  New->setInvalidDecl();
  return;
}

// Merge "used" flag.
if (Old->getMostRecentDecl()->isUsed(false))
  New->setIsUsed();

// Keep a chain of previous declarations.
New->setPreviousDecl(Old);
if (NewTemplate)
  NewTemplate->setPreviousDecl(OldTemplate);

// Inherit access appropriately.
New->setAccess(Old->getAccess());
if (NewTemplate)
  NewTemplate->setAccess(New->getAccess());

if (Old->isInline())
  New->setImplicitlyInline();
4752}

4754void Sema::notePreviousDefinition(const NamedDecl *Old, SourceLocation New) {
SourceManager &SrcMgr = getSourceManager();
auto FNewDecLoc = SrcMgr.getDecomposedLoc(New);
auto FOldDecLoc = SrcMgr.getDecomposedLoc(Old->getLocation());
auto *FNew = SrcMgr.getFileEntryForID(FNewDecLoc.first);
auto *FOld = SrcMgr.getFileEntryForID(FOldDecLoc.first);
auto &HSI = PP.getHeaderSearchInfo();
StringRef HdrFilename =
    SrcMgr.getFilename(SrcMgr.getSpellingLoc(Old->getLocation()));

auto noteFromModuleOrInclude = [&](Module *Mod,
                                   SourceLocation IncLoc) -> bool {
  // Redefinition errors with modules are common with non modular mapped
  // headers, example: a non-modular header H in module A that also gets
  // included directly in a TU. Pointing twice to the same header/definition
  // is confusing, try to get better diagnostics when modules is on.
  if (IncLoc.isValid()) {
    if (Mod) {
      Diag(IncLoc, diag::note_redefinition_modules_same_file)
          << HdrFilename.str() << Mod->getFullModuleName();
      if (!Mod->DefinitionLoc.isInvalid())
        Diag(Mod->DefinitionLoc, diag::note_defined_here)
            << Mod->getFullModuleName();
    } else {
      Diag(IncLoc, diag::note_redefinition_include_same_file)
          << HdrFilename.str();
    }
    return true;
  }

  return false;
};

// Is it the same file and same offset? Provide more information on why
// this leads to a redefinition error.
if (FNew == FOld && FNewDecLoc.second == FOldDecLoc.second) {
  SourceLocation OldIncLoc = SrcMgr.getIncludeLoc(FOldDecLoc.first);
  SourceLocation NewIncLoc = SrcMgr.getIncludeLoc(FNewDecLoc.first);
  bool EmittedDiag =
      noteFromModuleOrInclude(Old->getOwningModule(), OldIncLoc);
  EmittedDiag |= noteFromModuleOrInclude(getCurrentModule(), NewIncLoc);

  // If the header has no guards, emit a note suggesting one.
  if (FOld && !HSI.isFileMultipleIncludeGuarded(FOld))
    Diag(Old->getLocation(), diag::note_use_ifdef_guards);

  if (EmittedDiag)
    return;
}

// Redefinition coming from different files or couldn't do better above.
if (Old->getLocation().isValid())
  Diag(Old->getLocation(), diag::note_previous_definition);
4807}

4809/// We've just determined that \p Old and \p New both appear to be definitions
4810/// of the same variable. Either diagnose or fix the problem.
4811bool Sema::checkVarDeclRedefinition(VarDecl *Old, VarDecl *New) {
if (!hasVisibleDefinition(Old) &&
    (New->getFormalLinkage() == InternalLinkage ||
     New->isInline() ||
     isa<VarTemplateSpecializationDecl>(New) ||
     New->getDescribedVarTemplate() ||
     New->getNumTemplateParameterLists() ||
     New->getDeclContext()->isDependentContext())) {
  // The previous definition is hidden, and multiple definitions are
  // permitted (in separate TUs). Demote this to a declaration.
  New->demoteThisDefinitionToDeclaration();

  // Make the canonical definition visible.
  if (auto *OldTD = Old->getDescribedVarTemplate())
    makeMergedDefinitionVisible(OldTD);
  makeMergedDefinitionVisible(Old);
  return false;
} else {
  Diag(New->getLocation(), diag::err_redefinition) << New;
  notePreviousDefinition(Old, New->getLocation());
  New->setInvalidDecl();
  return true;
}
4834}

4836/// ParsedFreeStandingDeclSpec - This method is invoked when a declspec with
4837/// no declarator (e.g. "struct foo;") is parsed.
4838Decl *Sema::ParsedFreeStandingDeclSpec(Scope *S, AccessSpecifier AS,
                                     DeclSpec &DS,
                                     const ParsedAttributesView &DeclAttrs,
                                     RecordDecl *&AnonRecord) {
return ParsedFreeStandingDeclSpec(
    S, AS, DS, DeclAttrs, MultiTemplateParamsArg(), false, AnonRecord);
4844}

4846// The MS ABI changed between VS2013 and VS2015 with regard to numbers used to
4847// disambiguate entities defined in different scopes.
4848// While the VS2015 ABI fixes potential miscompiles, it is also breaks
4849// compatibility.
4850// We will pick our mangling number depending on which version of MSVC is being
4851// targeted.
4852static unsigned getMSManglingNumber(const LangOptions &LO, Scope *S) {
return LO.isCompatibleWithMSVC(LangOptions::MSVC2015)
           ? S->getMSCurManglingNumber()
           : S->getMSLastManglingNumber();
4856}

4858void Sema::handleTagNumbering(const TagDecl *Tag, Scope *TagScope) {
if (!Context.getLangOpts().CPlusPlus)
  return;

if (isa<CXXRecordDecl>(Tag->getParent())) {
  // If this tag is the direct child of a class, number it if
  // it is anonymous.
  if (!Tag->getName().empty() || Tag->getTypedefNameForAnonDecl())
    return;
  MangleNumberingContext &MCtx =
      Context.getManglingNumberContext(Tag->getParent());
  Context.setManglingNumber(
      Tag, MCtx.getManglingNumber(
               Tag, getMSManglingNumber(getLangOpts(), TagScope)));
  return;
}

// If this tag isn't a direct child of a class, number it if it is local.
MangleNumberingContext *MCtx;
Decl *ManglingContextDecl;
std::tie(MCtx, ManglingContextDecl) =
    getCurrentMangleNumberContext(Tag->getDeclContext());
if (MCtx) {
  Context.setManglingNumber(
      Tag, MCtx->getManglingNumber(
               Tag, getMSManglingNumber(getLangOpts(), TagScope)));
}
4885}

4887namespace {
4888struct NonCLikeKind {
enum {
  None,
  BaseClass,
  DefaultMemberInit,
  Lambda,
  Friend,
  OtherMember,
  Invalid,
} Kind = None;
SourceRange Range;

explicit operator bool() { return Kind != None; }
4901};
4902}

4904/// Determine whether a class is C-like, according to the rules of C++
4905/// [dcl.typedef] for anonymous classes with typedef names for linkage.
4906static NonCLikeKind getNonCLikeKindForAnonymousStruct(const CXXRecordDecl *RD) {
if (RD->isInvalidDecl())
  return {NonCLikeKind::Invalid, {}};

// C++ [dcl.typedef]p9: [P1766R1]
//   An unnamed class with a typedef name for linkage purposes shall not
//
//    -- have any base classes
if (RD->getNumBases())
  return {NonCLikeKind::BaseClass,
          SourceRange(RD->bases_begin()->getBeginLoc(),
                      RD->bases_end()[-1].getEndLoc())};
bool Invalid = false;
for (Decl *D : RD->decls()) {
  // Don't complain about things we already diagnosed.
  if (D->isInvalidDecl()) {
    Invalid = true;
    continue;
  }

  //  -- have any [...] default member initializers
  if (auto *FD = dyn_cast<FieldDecl>(D)) {
    if (FD->hasInClassInitializer()) {
      auto *Init = FD->getInClassInitializer();
      return {NonCLikeKind::DefaultMemberInit,
              Init ? Init->getSourceRange() : D->getSourceRange()};
    }
    continue;
  }

  // FIXME: We don't allow friend declarations. This violates the wording of
  // P1766, but not the intent.
  if (isa<FriendDecl>(D))
    return {NonCLikeKind::Friend, D->getSourceRange()};

  //  -- declare any members other than non-static data members, member
  //     enumerations, or member classes,
  if (isa<StaticAssertDecl>(D) || isa<IndirectFieldDecl>(D) ||
      isa<EnumDecl>(D))
    continue;
  auto *MemberRD = dyn_cast<CXXRecordDecl>(D);
  if (!MemberRD) {
    if (D->isImplicit())
      continue;
    return {NonCLikeKind::OtherMember, D->getSourceRange()};
  }

  //  -- contain a lambda-expression,
  if (MemberRD->isLambda())
    return {NonCLikeKind::Lambda, MemberRD->getSourceRange()};

  //  and all member classes shall also satisfy these requirements
  //  (recursively).
  if (MemberRD->isThisDeclarationADefinition()) {
    if (auto Kind = getNonCLikeKindForAnonymousStruct(MemberRD))
      return Kind;
  }
}

return {Invalid ? NonCLikeKind::Invalid : NonCLikeKind::None, {}};
4966}

4968void Sema::setTagNameForLinkagePurposes(TagDecl *TagFromDeclSpec,
                                      TypedefNameDecl *NewTD) {
if (TagFromDeclSpec->isInvalidDecl())
  return;

// Do nothing if the tag already has a name for linkage purposes.
if (TagFromDeclSpec->hasNameForLinkage())
  return;

// A well-formed anonymous tag must always be a TUK_Definition.
assert(TagFromDeclSpec->isThisDeclarationADefinition())(static_cast <bool> (TagFromDeclSpec->isThisDeclarationADefinition
()) ? void (0) : __assert_fail ("TagFromDeclSpec->isThisDeclarationADefinition()"
, "clang/lib/Sema/SemaDecl.cpp", 4978, __extension__ __PRETTY_FUNCTION__
));

// The type must match the tag exactly;  no qualifiers allowed.
if (!Context.hasSameType(NewTD->getUnderlyingType(),
                         Context.getTagDeclType(TagFromDeclSpec))) {
  if (getLangOpts().CPlusPlus)
    Context.addTypedefNameForUnnamedTagDecl(TagFromDeclSpec, NewTD);
  return;
}

// C++ [dcl.typedef]p9: [P1766R1, applied as DR]
//   An unnamed class with a typedef name for linkage purposes shall [be
//   C-like].
//
// FIXME: Also diagnose if we've already computed the linkage. That ideally
// shouldn't happen, but there are constructs that the language rule doesn't
// disallow for which we can't reasonably avoid computing linkage early.
const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(TagFromDeclSpec);
NonCLikeKind NonCLike = RD ? getNonCLikeKindForAnonymousStruct(RD)
                           : NonCLikeKind();
bool ChangesLinkage = TagFromDeclSpec->hasLinkageBeenComputed();
if (NonCLike || ChangesLinkage) {
  if (NonCLike.Kind == NonCLikeKind::Invalid)
    return;

  unsigned DiagID = diag::ext_non_c_like_anon_struct_in_typedef;
  if (ChangesLinkage) {
    // If the linkage changes, we can't accept this as an extension.
    if (NonCLike.Kind == NonCLikeKind::None)
      DiagID = diag::err_typedef_changes_linkage;
    else
      DiagID = diag::err_non_c_like_anon_struct_in_typedef;
  }

  SourceLocation FixitLoc =
      getLocForEndOfToken(TagFromDeclSpec->getInnerLocStart());
  llvm::SmallString<40> TextToInsert;
  TextToInsert += ' ';
  TextToInsert += NewTD->getIdentifier()->getName();

  Diag(FixitLoc, DiagID)
    << isa<TypeAliasDecl>(NewTD)
    << FixItHint::CreateInsertion(FixitLoc, TextToInsert);
  if (NonCLike.Kind != NonCLikeKind::None) {
    Diag(NonCLike.Range.getBegin(), diag::note_non_c_like_anon_struct)
      << NonCLike.Kind - 1 << NonCLike.Range;
  }
  Diag(NewTD->getLocation(), diag::note_typedef_for_linkage_here)
    << NewTD << isa<TypeAliasDecl>(NewTD);

  if (ChangesLinkage)
    return;
}

// Otherwise, set this as the anon-decl typedef for the tag.
TagFromDeclSpec->setTypedefNameForAnonDecl(NewTD);
5034}

5036static unsigned GetDiagnosticTypeSpecifierID(DeclSpec::TST T) {
switch (T) {
case DeclSpec::TST_class:
  return 0;
case DeclSpec::TST_struct:
  return 1;
case DeclSpec::TST_interface:
  return 2;
case DeclSpec::TST_union:
  return 3;
case DeclSpec::TST_enum:
  return 4;
default:
  llvm_unreachable("unexpected type specifier")::llvm::llvm_unreachable_internal("unexpected type specifier"
, "clang/lib/Sema/SemaDecl.cpp", 5049);
}
5051}

5053/// ParsedFreeStandingDeclSpec - This method is invoked when a declspec with
5054/// no declarator (e.g. "struct foo;") is parsed. It also accepts template
5055/// parameters to cope with template friend declarations.
5056Decl *Sema::ParsedFreeStandingDeclSpec(Scope *S, AccessSpecifier AS,
                                     DeclSpec &DS,
                                     const ParsedAttributesView &DeclAttrs,
                                     MultiTemplateParamsArg TemplateParams,
                                     bool IsExplicitInstantiation,
                                     RecordDecl *&AnonRecord) {
Decl *TagD = nullptr;
TagDecl *Tag = nullptr;
if (DS.getTypeSpecType() == DeclSpec::TST_class ||
    DS.getTypeSpecType() == DeclSpec::TST_struct ||
    DS.getTypeSpecType() == DeclSpec::TST_interface ||
    DS.getTypeSpecType() == DeclSpec::TST_union ||
    DS.getTypeSpecType() == DeclSpec::TST_enum) {
  TagD = DS.getRepAsDecl();

  if (!TagD) // We probably had an error
    return nullptr;

  // Note that the above type specs guarantee that the
  // type rep is a Decl, whereas in many of the others
  // it's a Type.
  if (isa<TagDecl>(TagD))
    Tag = cast<TagDecl>(TagD);
  else if (ClassTemplateDecl *CTD = dyn_cast<ClassTemplateDecl>(TagD))
    Tag = CTD->getTemplatedDecl();
}

if (Tag) {
  handleTagNumbering(Tag, S);
  Tag->setFreeStanding();
  if (Tag->isInvalidDecl())
    return Tag;
}

if (unsigned TypeQuals = DS.getTypeQualifiers()) {
  // Enforce C99 6.7.3p2: "Types other than pointer types derived from object
  // or incomplete types shall not be restrict-qualified."
  if (TypeQuals & DeclSpec::TQ_restrict)
    Diag(DS.getRestrictSpecLoc(),
         diag::err_typecheck_invalid_restrict_not_pointer_noarg)
         << DS.getSourceRange();
}

if (DS.isInlineSpecified())
  Diag(DS.getInlineSpecLoc(), diag::err_inline_non_function)
      << getLangOpts().CPlusPlus17;

if (DS.hasConstexprSpecifier()) {
  // C++0x [dcl.constexpr]p1: constexpr can only be applied to declarations
  // and definitions of functions and variables.
  // C++2a [dcl.constexpr]p1: The consteval specifier shall be applied only to
  // the declaration of a function or function template
  if (Tag)
    Diag(DS.getConstexprSpecLoc(), diag::err_constexpr_tag)
        << GetDiagnosticTypeSpecifierID(DS.getTypeSpecType())
        << static_cast<int>(DS.getConstexprSpecifier());
  else
    Diag(DS.getConstexprSpecLoc(), diag::err_constexpr_wrong_decl_kind)
        << static_cast<int>(DS.getConstexprSpecifier());
  // Don't emit warnings after this error.
  return TagD;
}

DiagnoseFunctionSpecifiers(DS);

if (DS.isFriendSpecified()) {
  // If we're dealing with a decl but not a TagDecl, assume that
  // whatever routines created it handled the friendship aspect.
  if (TagD && !Tag)
    return nullptr;
  return ActOnFriendTypeDecl(S, DS, TemplateParams);
}

const CXXScopeSpec &SS = DS.getTypeSpecScope();
bool IsExplicitSpecialization =
  !TemplateParams.empty() && TemplateParams.back()->size() == 0;
if (Tag && SS.isNotEmpty() && !Tag->isCompleteDefinition() &&
    !IsExplicitInstantiation && !IsExplicitSpecialization &&
    !isa<ClassTemplatePartialSpecializationDecl>(Tag)) {
  // Per C++ [dcl.type.elab]p1, a class declaration cannot have a
  // nested-name-specifier unless it is an explicit instantiation
  // or an explicit specialization.
  //
  // FIXME: We allow class template partial specializations here too, per the
  // obvious intent of DR1819.
  //
  // Per C++ [dcl.enum]p1, an opaque-enum-declaration can't either.
  Diag(SS.getBeginLoc(), diag::err_standalone_class_nested_name_specifier)
      << GetDiagnosticTypeSpecifierID(DS.getTypeSpecType()) << SS.getRange();
  return nullptr;
}

// Track whether this decl-specifier declares anything.
bool DeclaresAnything = true;

// Handle anonymous struct definitions.
if (RecordDecl *Record = dyn_cast_or_null<RecordDecl>(Tag)) {
  if (!Record->getDeclName() && Record->isCompleteDefinition() &&
      DS.getStorageClassSpec() != DeclSpec::SCS_typedef) {
    if (getLangOpts().CPlusPlus ||
        Record->getDeclContext()->isRecord()) {
      // If CurContext is a DeclContext that can contain statements,
      // RecursiveASTVisitor won't visit the decls that
      // BuildAnonymousStructOrUnion() will put into CurContext.
      // Also store them here so that they can be part of the
      // DeclStmt that gets created in this case.
      // FIXME: Also return the IndirectFieldDecls created by
      // BuildAnonymousStructOr union, for the same reason?
      if (CurContext->isFunctionOrMethod())
        AnonRecord = Record;
      return BuildAnonymousStructOrUnion(S, DS, AS, Record,
                                         Context.getPrintingPolicy());
    }

    DeclaresAnything = false;
  }
}

// C11 6.7.2.1p2:
//   A struct-declaration that does not declare an anonymous structure or
//   anonymous union shall contain a struct-declarator-list.
//
// This rule also existed in C89 and C99; the grammar for struct-declaration
// did not permit a struct-declaration without a struct-declarator-list.
if (!getLangOpts().CPlusPlus && CurContext->isRecord() &&
    DS.getStorageClassSpec() == DeclSpec::SCS_unspecified) {
  // Check for Microsoft C extension: anonymous struct/union member.
  // Handle 2 kinds of anonymous struct/union:
  //   struct STRUCT;
  //   union UNION;
  // and
  //   STRUCT_TYPE;  <- where STRUCT_TYPE is a typedef struct.
  //   UNION_TYPE;   <- where UNION_TYPE is a typedef union.
  if ((Tag && Tag->getDeclName()) ||
      DS.getTypeSpecType() == DeclSpec::TST_typename) {
    RecordDecl *Record = nullptr;
    if (Tag)
      Record = dyn_cast<RecordDecl>(Tag);
    else if (const RecordType *RT =
                 DS.getRepAsType().get()->getAsStructureType())
      Record = RT->getDecl();
    else if (const RecordType *UT = DS.getRepAsType().get()->getAsUnionType())
      Record = UT->getDecl();

    if (Record && getLangOpts().MicrosoftExt) {
      Diag(DS.getBeginLoc(), diag::ext_ms_anonymous_record)
          << Record->isUnion() << DS.getSourceRange();
      return BuildMicrosoftCAnonymousStruct(S, DS, Record);
    }

    DeclaresAnything = false;
  }
}

// Skip all the checks below if we have a type error.
if (DS.getTypeSpecType() == DeclSpec::TST_error ||
    (TagD && TagD->isInvalidDecl()))
  return TagD;

if (getLangOpts().CPlusPlus &&
    DS.getStorageClassSpec() != DeclSpec::SCS_typedef)
  if (EnumDecl *Enum = dyn_cast_or_null<EnumDecl>(Tag))
    if (Enum->enumerator_begin() == Enum->enumerator_end() &&
        !Enum->getIdentifier() && !Enum->isInvalidDecl())
      DeclaresAnything = false;

if (!DS.isMissingDeclaratorOk()) {
  // Customize diagnostic for a typedef missing a name.
  if (DS.getStorageClassSpec() == DeclSpec::SCS_typedef)
    Diag(DS.getBeginLoc(), diag::ext_typedef_without_a_name)
        << DS.getSourceRange();
  else
    DeclaresAnything = false;
}

if (DS.isModulePrivateSpecified() &&
    Tag && Tag->getDeclContext()->isFunctionOrMethod())
  Diag(DS.getModulePrivateSpecLoc(), diag::err_module_private_local_class)
    << Tag->getTagKind()
    << FixItHint::CreateRemoval(DS.getModulePrivateSpecLoc());

ActOnDocumentableDecl(TagD);

// C 6.7/2:
//   A declaration [...] shall declare at least a declarator [...], a tag,
//   or the members of an enumeration.
// C++ [dcl.dcl]p3:
//   [If there are no declarators], and except for the declaration of an
//   unnamed bit-field, the decl-specifier-seq shall introduce one or more
//   names into the program, or shall redeclare a name introduced by a
//   previous declaration.
if (!DeclaresAnything) {
  // In C, we allow this as a (popular) extension / bug. Don't bother
  // producing further diagnostics for redundant qualifiers after this.
  Diag(DS.getBeginLoc(), (IsExplicitInstantiation || !TemplateParams.empty())
                             ? diag::err_no_declarators
                             : diag::ext_no_declarators)
      << DS.getSourceRange();
  return TagD;
}

// C++ [dcl.stc]p1:
//   If a storage-class-specifier appears in a decl-specifier-seq, [...] the
//   init-declarator-list of the declaration shall not be empty.
// C++ [dcl.fct.spec]p1:
//   If a cv-qualifier appears in a decl-specifier-seq, the
//   init-declarator-list of the declaration shall not be empty.
//
// Spurious qualifiers here appear to be valid in C.
unsigned DiagID = diag::warn_standalone_specifier;
if (getLangOpts().CPlusPlus)
  DiagID = diag::ext_standalone_specifier;

// Note that a linkage-specification sets a storage class, but
// 'extern "C" struct foo;' is actually valid and not theoretically
// useless.
if (DeclSpec::SCS SCS = DS.getStorageClassSpec()) {
  if (SCS == DeclSpec::SCS_mutable)
    // Since mutable is not a viable storage class specifier in C, there is
    // no reason to treat it as an extension. Instead, diagnose as an error.
    Diag(DS.getStorageClassSpecLoc(), diag::err_mutable_nonmember);
  else if (!DS.isExternInLinkageSpec() && SCS != DeclSpec::SCS_typedef)
    Diag(DS.getStorageClassSpecLoc(), DiagID)
      << DeclSpec::getSpecifierName(SCS);
}

if (DeclSpec::TSCS TSCS = DS.getThreadStorageClassSpec())
  Diag(DS.getThreadStorageClassSpecLoc(), DiagID)
    << DeclSpec::getSpecifierName(TSCS);
if (DS.getTypeQualifiers()) {
  if (DS.getTypeQualifiers() & DeclSpec::TQ_const)
    Diag(DS.getConstSpecLoc(), DiagID) << "const";
  if (DS.getTypeQualifiers() & DeclSpec::TQ_volatile)
    Diag(DS.getConstSpecLoc(), DiagID) << "volatile";
  // Restrict is covered above.
  if (DS.getTypeQualifiers() & DeclSpec::TQ_atomic)
    Diag(DS.getAtomicSpecLoc(), DiagID) << "_Atomic";
  if (DS.getTypeQualifiers() & DeclSpec::TQ_unaligned)
    Diag(DS.getUnalignedSpecLoc(), DiagID) << "__unaligned";
}

// Warn about ignored type attributes, for example:
// __attribute__((aligned)) struct A;
// Attributes should be placed after tag to apply to type declaration.
if (!DS.getAttributes().empty() || !DeclAttrs.empty()) {
  DeclSpec::TST TypeSpecType = DS.getTypeSpecType();
  if (TypeSpecType == DeclSpec::TST_class ||
      TypeSpecType == DeclSpec::TST_struct ||
      TypeSpecType == DeclSpec::TST_interface ||
      TypeSpecType == DeclSpec::TST_union ||
      TypeSpecType == DeclSpec::TST_enum) {
    for (const ParsedAttr &AL : DS.getAttributes())
      Diag(AL.getLoc(), diag::warn_declspec_attribute_ignored)
          << AL << GetDiagnosticTypeSpecifierID(TypeSpecType);
    for (const ParsedAttr &AL : DeclAttrs)
      Diag(AL.getLoc(), diag::warn_declspec_attribute_ignored)
          << AL << GetDiagnosticTypeSpecifierID(TypeSpecType);
  }
}

return TagD;
5317}

5319/// We are trying to inject an anonymous member into the given scope;
5320/// check if there's an existing declaration that can't be overloaded.
5321///
5322/// \return true if this is a forbidden redeclaration
5323static bool CheckAnonMemberRedeclaration(Sema &SemaRef,
                                       Scope *S,
                                       DeclContext *Owner,
                                       DeclarationName Name,
                                       SourceLocation NameLoc,
                                       bool IsUnion) {
LookupResult R(SemaRef, Name, NameLoc, Sema::LookupMemberName,
               Sema::ForVisibleRedeclaration);
if (!SemaRef.LookupName(R, S)) return false;

// Pick a representative declaration.
NamedDecl *PrevDecl = R.getRepresentativeDecl()->getUnderlyingDecl();
assert(PrevDecl && "Expected a non-null Decl")(static_cast <bool> (PrevDecl && "Expected a non-null Decl"
) ? void (0) : __assert_fail ("PrevDecl && \"Expected a non-null Decl\""
, "clang/lib/Sema/SemaDecl.cpp", 5335, __extension__ __PRETTY_FUNCTION__
));

if (!SemaRef.isDeclInScope(PrevDecl, Owner, S))
  return false;

SemaRef.Diag(NameLoc, diag::err_anonymous_record_member_redecl)
  << IsUnion << Name;
SemaRef.Diag(PrevDecl->getLocation(), diag::note_previous_declaration);

return true;
5345}

5347/// InjectAnonymousStructOrUnionMembers - Inject the members of the
5348/// anonymous struct or union AnonRecord into the owning context Owner
5349/// and scope S. This routine will be invoked just after we realize
5350/// that an unnamed union or struct is actually an anonymous union or
5351/// struct, e.g.,
5352///
5353/// @code
5354/// union {
5355///   int i;
5356///   float f;
5357/// }; // InjectAnonymousStructOrUnionMembers called here to inject i and
5358///    // f into the surrounding scope.x
5359/// @endcode
5360///
5361/// This routine is recursive, injecting the names of nested anonymous
5362/// structs/unions into the owning context and scope as well.
5363static bool
5364InjectAnonymousStructOrUnionMembers(Sema &SemaRef, Scope *S, DeclContext *Owner,
                                  RecordDecl *AnonRecord, AccessSpecifier AS,
                                  SmallVectorImpl<NamedDecl *> &Chaining) {
bool Invalid = false;

// Look every FieldDecl and IndirectFieldDecl with a name.
for (auto *D : AnonRecord->decls()) {
  if ((isa<FieldDecl>(D) || isa<IndirectFieldDecl>(D)) &&
      cast<NamedDecl>(D)->getDeclName()) {
    ValueDecl *VD = cast<ValueDecl>(D);
    if (CheckAnonMemberRedeclaration(SemaRef, S, Owner, VD->getDeclName(),
                                     VD->getLocation(),
                                     AnonRecord->isUnion())) {
      // C++ [class.union]p2:
      //   The names of the members of an anonymous union shall be
      //   distinct from the names of any other entity in the
      //   scope in which the anonymous union is declared.
      Invalid = true;
    } else {
      // C++ [class.union]p2:
      //   For the purpose of name lookup, after the anonymous union
      //   definition, the members of the anonymous union are
      //   considered to have been defined in the scope in which the
      //   anonymous union is declared.
      unsigned OldChainingSize = Chaining.size();
      if (IndirectFieldDecl *IF = dyn_cast<IndirectFieldDecl>(VD))
        Chaining.append(IF->chain_begin(), IF->chain_end());
      else
        Chaining.push_back(VD);

      assert(Chaining.size() >= 2)(static_cast <bool> (Chaining.size() >= 2) ? void (0
) : __assert_fail ("Chaining.size() >= 2", "clang/lib/Sema/SemaDecl.cpp"
, 5394, __extension__ __PRETTY_FUNCTION__));
      NamedDecl **NamedChain =
        new (SemaRef.Context)NamedDecl*[Chaining.size()];
      for (unsigned i = 0; i < Chaining.size(); i++)
        NamedChain[i] = Chaining[i];

      IndirectFieldDecl *IndirectField = IndirectFieldDecl::Create(
          SemaRef.Context, Owner, VD->getLocation(), VD->getIdentifier(),
          VD->getType(), {NamedChain, Chaining.size()});

      for (const auto *Attr : VD->attrs())
        IndirectField->addAttr(Attr->clone(SemaRef.Context));

      IndirectField->setAccess(AS);
      IndirectField->setImplicit();
      SemaRef.PushOnScopeChains(IndirectField, S);

      // That includes picking up the appropriate access specifier.
      if (AS != AS_none) IndirectField->setAccess(AS);

      Chaining.resize(OldChainingSize);
    }
  }
}

return Invalid;
5420}

5422/// StorageClassSpecToVarDeclStorageClass - Maps a DeclSpec::SCS to
5423/// a VarDecl::StorageClass. Any error reporting is up to the caller:
5424/// illegal input values are mapped to SC_None.
5425static StorageClass
5426StorageClassSpecToVarDeclStorageClass(const DeclSpec &DS) {
DeclSpec::SCS StorageClassSpec = DS.getStorageClassSpec();
assert(StorageClassSpec != DeclSpec::SCS_typedef &&(static_cast <bool> (StorageClassSpec != DeclSpec::SCS_typedef
 && "Parser allowed 'typedef' as storage class VarDecl."
) ? void (0) : __assert_fail ("StorageClassSpec != DeclSpec::SCS_typedef && \"Parser allowed 'typedef' as storage class VarDecl.\""
, "clang/lib/Sema/SemaDecl.cpp", 5429, __extension__ __PRETTY_FUNCTION__
))
       "Parser allowed 'typedef' as storage class VarDecl.")(static_cast <bool> (StorageClassSpec != DeclSpec::SCS_typedef
 && "Parser allowed 'typedef' as storage class VarDecl."
) ? void (0) : __assert_fail ("StorageClassSpec != DeclSpec::SCS_typedef && \"Parser allowed 'typedef' as storage class VarDecl.\""
, "clang/lib/Sema/SemaDecl.cpp", 5429, __extension__ __PRETTY_FUNCTION__
));
switch (StorageClassSpec) {
case DeclSpec::SCS_unspecified:    return SC_None;
case DeclSpec::SCS_extern:
  if (DS.isExternInLinkageSpec())
    return SC_None;
  return SC_Extern;
case DeclSpec::SCS_static:         return SC_Static;
case DeclSpec::SCS_auto:           return SC_Auto;
case DeclSpec::SCS_register:       return SC_Register;
case DeclSpec::SCS_private_extern: return SC_PrivateExtern;
  // Illegal SCSs map to None: error reporting is up to the caller.
case DeclSpec::SCS_mutable:        // Fall through.
case DeclSpec::SCS_typedef:        return SC_None;
}
llvm_unreachable("unknown storage class specifier")::llvm::llvm_unreachable_internal("unknown storage class specifier"
, "clang/lib/Sema/SemaDecl.cpp", 5444);
5445}

5447static SourceLocation findDefaultInitializer(const CXXRecordDecl *Record) {
assert(Record->hasInClassInitializer())(static_cast <bool> (Record->hasInClassInitializer()
) ? void (0) : __assert_fail ("Record->hasInClassInitializer()"
, "clang/lib/Sema/SemaDecl.cpp", 5448, __extension__ __PRETTY_FUNCTION__
));

for (const auto *I : Record->decls()) {
  const auto *FD = dyn_cast<FieldDecl>(I);
  if (const auto *IFD = dyn_cast<IndirectFieldDecl>(I))
    FD = IFD->getAnonField();
  if (FD && FD->hasInClassInitializer())
    return FD->getLocation();
}

llvm_unreachable("couldn't find in-class initializer")::llvm::llvm_unreachable_internal("couldn't find in-class initializer"
, "clang/lib/Sema/SemaDecl.cpp", 5458);
5459}

5461static void checkDuplicateDefaultInit(Sema &S, CXXRecordDecl *Parent,
                                    SourceLocation DefaultInitLoc) {
if (!Parent->isUnion() || !Parent->hasInClassInitializer())
  return;

S.Diag(DefaultInitLoc, diag::err_multiple_mem_union_initialization);
S.Diag(findDefaultInitializer(Parent), diag::note_previous_initializer) << 0;
5468}

5470static void checkDuplicateDefaultInit(Sema &S, CXXRecordDecl *Parent,
                                    CXXRecordDecl *AnonUnion) {
if (!Parent->isUnion() || !Parent->hasInClassInitializer())
  return;

checkDuplicateDefaultInit(S, Parent, findDefaultInitializer(AnonUnion));
5476}

5478/// BuildAnonymousStructOrUnion - Handle the declaration of an
5479/// anonymous structure or union. Anonymous unions are a C++ feature
5480/// (C++ [class.union]) and a C11 feature; anonymous structures
5481/// are a C11 feature and GNU C++ extension.
5482Decl *Sema::BuildAnonymousStructOrUnion(Scope *S, DeclSpec &DS,
                                      AccessSpecifier AS,
                                      RecordDecl *Record,
                                      const PrintingPolicy &Policy) {
DeclContext *Owner = Record->getDeclContext();

// Diagnose whether this anonymous struct/union is an extension.
if (Record->isUnion() && !getLangOpts().CPlusPlus && !getLangOpts().C11)
  Diag(Record->getLocation(), diag::ext_anonymous_union);
else if (!Record->isUnion() && getLangOpts().CPlusPlus)
  Diag(Record->getLocation(), diag::ext_gnu_anonymous_struct);
else if (!Record->isUnion() && !getLangOpts().C11)
  Diag(Record->getLocation(), diag::ext_c11_anonymous_struct);

// C and C++ require different kinds of checks for anonymous
// structs/unions.
bool Invalid = false;
if (getLangOpts().CPlusPlus) {
  const char *PrevSpec = nullptr;
  if (Record->isUnion()) {
    // C++ [class.union]p6:
    // C++17 [class.union.anon]p2:
    //   Anonymous unions declared in a named namespace or in the
    //   global namespace shall be declared static.
    unsigned DiagID;
    DeclContext *OwnerScope = Owner->getRedeclContext();
    if (DS.getStorageClassSpec() != DeclSpec::SCS_static &&
        (OwnerScope->isTranslationUnit() ||
         (OwnerScope->isNamespace() &&
          !cast<NamespaceDecl>(OwnerScope)->isAnonymousNamespace()))) {
      Diag(Record->getLocation(), diag::err_anonymous_union_not_static)
        << FixItHint::CreateInsertion(Record->getLocation(), "static ");

      // Recover by adding 'static'.
      DS.SetStorageClassSpec(*this, DeclSpec::SCS_static, SourceLocation(),
                             PrevSpec, DiagID, Policy);
    }
    // C++ [class.union]p6:
    //   A storage class is not allowed in a declaration of an
    //   anonymous union in a class scope.
    else if (DS.getStorageClassSpec() != DeclSpec::SCS_unspecified &&
             isa<RecordDecl>(Owner)) {
      Diag(DS.getStorageClassSpecLoc(),
           diag::err_anonymous_union_with_storage_spec)
        << FixItHint::CreateRemoval(DS.getStorageClassSpecLoc());

      // Recover by removing the storage specifier.
      DS.SetStorageClassSpec(*this, DeclSpec::SCS_unspecified,
                             SourceLocation(),
                             PrevSpec, DiagID, Context.getPrintingPolicy());
    }
  }

  // Ignore const/volatile/restrict qualifiers.
  if (DS.getTypeQualifiers()) {
    if (DS.getTypeQualifiers() & DeclSpec::TQ_const)
      Diag(DS.getConstSpecLoc(), diag::ext_anonymous_struct_union_qualified)
        << Record->isUnion() << "const"
        << FixItHint::CreateRemoval(DS.getConstSpecLoc());
    if (DS.getTypeQualifiers() & DeclSpec::TQ_volatile)
      Diag(DS.getVolatileSpecLoc(),
           diag::ext_anonymous_struct_union_qualified)
        << Record->isUnion() << "volatile"
        << FixItHint::CreateRemoval(DS.getVolatileSpecLoc());
    if (DS.getTypeQualifiers() & DeclSpec::TQ_restrict)
      Diag(DS.getRestrictSpecLoc(),
           diag::ext_anonymous_struct_union_qualified)
        << Record->isUnion() << "restrict"
        << FixItHint::CreateRemoval(DS.getRestrictSpecLoc());
    if (DS.getTypeQualifiers() & DeclSpec::TQ_atomic)
      Diag(DS.getAtomicSpecLoc(),
           diag::ext_anonymous_struct_union_qualified)
        << Record->isUnion() << "_Atomic"
        << FixItHint::CreateRemoval(DS.getAtomicSpecLoc());
    if (DS.getTypeQualifiers() & DeclSpec::TQ_unaligned)
      Diag(DS.getUnalignedSpecLoc(),
           diag::ext_anonymous_struct_union_qualified)
        << Record->isUnion() << "__unaligned"
        << FixItHint::CreateRemoval(DS.getUnalignedSpecLoc());

    DS.ClearTypeQualifiers();
  }

  // C++ [class.union]p2:
  //   The member-specification of an anonymous union shall only
  //   define non-static data members. [Note: nested types and
  //   functions cannot be declared within an anonymous union. ]
  for (auto *Mem : Record->decls()) {
    // Ignore invalid declarations; we already diagnosed them.
    if (Mem->isInvalidDecl())
      continue;

    if (auto *FD = dyn_cast<FieldDecl>(Mem)) {
      // C++ [class.union]p3:
      //   An anonymous union shall not have private or protected
      //   members (clause 11).
      assert(FD->getAccess() != AS_none)(static_cast <bool> (FD->getAccess() != AS_none) ? void
 (0) : __assert_fail ("FD->getAccess() != AS_none", "clang/lib/Sema/SemaDecl.cpp"
, 5578, __extension__ __PRETTY_FUNCTION__));
      if (FD->getAccess() != AS_public) {
        Diag(FD->getLocation(), diag::err_anonymous_record_nonpublic_member)
          << Record->isUnion() << (FD->getAccess() == AS_protected);
        Invalid = true;
      }

      // C++ [class.union]p1
      //   An object of a class with a non-trivial constructor, a non-trivial
      //   copy constructor, a non-trivial destructor, or a non-trivial copy
      //   assignment operator cannot be a member of a union, nor can an
      //   array of such objects.
      if (CheckNontrivialField(FD))
        Invalid = true;
    } else if (Mem->isImplicit()) {
      // Any implicit members are fine.
    } else if (isa<TagDecl>(Mem) && Mem->getDeclContext() != Record) {
      // This is a type that showed up in an
      // elaborated-type-specifier inside the anonymous struct or
      // union, but which actually declares a type outside of the
      // anonymous struct or union. It's okay.
    } else if (auto *MemRecord = dyn_cast<RecordDecl>(Mem)) {
      if (!MemRecord->isAnonymousStructOrUnion() &&
          MemRecord->getDeclName()) {
        // Visual C++ allows type definition in anonymous struct or union.
        if (getLangOpts().MicrosoftExt)
          Diag(MemRecord->getLocation(), diag::ext_anonymous_record_with_type)
            << Record->isUnion();
        else {
          // This is a nested type declaration.
          Diag(MemRecord->getLocation(), diag::err_anonymous_record_with_type)
            << Record->isUnion();
          Invalid = true;
        }
      } else {
        // This is an anonymous type definition within another anonymous type.
        // This is a popular extension, provided by Plan9, MSVC and GCC, but
        // not part of standard C++.
        Diag(MemRecord->getLocation(),
             diag::ext_anonymous_record_with_anonymous_type)
          << Record->isUnion();
      }
    } else if (isa<AccessSpecDecl>(Mem)) {
      // Any access specifier is fine.
    } else if (isa<StaticAssertDecl>(Mem)) {
      // In C++1z, static_assert declarations are also fine.
    } else {
      // We have something that isn't a non-static data
      // member. Complain about it.
      unsigned DK = diag::err_anonymous_record_bad_member;
      if (isa<TypeDecl>(Mem))
        DK = diag::err_anonymous_record_with_type;
      else if (isa<FunctionDecl>(Mem))
        DK = diag::err_anonymous_record_with_function;
      else if (isa<VarDecl>(Mem))
        DK = diag::err_anonymous_record_with_static;

      // Visual C++ allows type definition in anonymous struct or union.
      if (getLangOpts().MicrosoftExt &&
          DK == diag::err_anonymous_record_with_type)
        Diag(Mem->getLocation(), diag::ext_anonymous_record_with_type)
          << Record->isUnion();
      else {
        Diag(Mem->getLocation(), DK) << Record->isUnion();
        Invalid = true;
      }
    }
  }

  // C++11 [class.union]p8 (DR1460):
  //   At most one variant member of a union may have a
  //   brace-or-equal-initializer.
  if (cast<CXXRecordDecl>(Record)->hasInClassInitializer() &&
      Owner->isRecord())
    checkDuplicateDefaultInit(*this, cast<CXXRecordDecl>(Owner),
                              cast<CXXRecordDecl>(Record));
}

if (!Record->isUnion() && !Owner->isRecord()) {
  Diag(Record->getLocation(), diag::err_anonymous_struct_not_member)
    << getLangOpts().CPlusPlus;
  Invalid = true;
}

// C++ [dcl.dcl]p3:
//   [If there are no declarators], and except for the declaration of an
//   unnamed bit-field, the decl-specifier-seq shall introduce one or more
//   names into the program
// C++ [class.mem]p2:
//   each such member-declaration shall either declare at least one member
//   name of the class or declare at least one unnamed bit-field
//
// For C this is an error even for a named struct, and is diagnosed elsewhere.
if (getLangOpts().CPlusPlus && Record->field_empty())
  Diag(DS.getBeginLoc(), diag::ext_no_declarators) << DS.getSourceRange();

// Mock up a declarator.
Declarator Dc(DS, ParsedAttributesView::none(), DeclaratorContext::Member);
TypeSourceInfo *TInfo = GetTypeForDeclarator(Dc, S);
assert(TInfo && "couldn't build declarator info for anonymous struct/union")(static_cast <bool> (TInfo && "couldn't build declarator info for anonymous struct/union"
) ? void (0) : __assert_fail ("TInfo && \"couldn't build declarator info for anonymous struct/union\""
, "clang/lib/Sema/SemaDecl.cpp", 5677, __extension__ __PRETTY_FUNCTION__
));

// Create a declaration for this anonymous struct/union.
NamedDecl *Anon = nullptr;
if (RecordDecl *OwningClass = dyn_cast<RecordDecl>(Owner)) {
  Anon = FieldDecl::Create(
      Context, OwningClass, DS.getBeginLoc(), Record->getLocation(),
      /*IdentifierInfo=*/nullptr, Context.getTypeDeclType(Record), TInfo,
      /*BitWidth=*/nullptr, /*Mutable=*/false,
      /*InitStyle=*/ICIS_NoInit);
  Anon->setAccess(AS);
  ProcessDeclAttributes(S, Anon, Dc);

  if (getLangOpts().CPlusPlus)
    FieldCollector->Add(cast<FieldDecl>(Anon));
} else {
  DeclSpec::SCS SCSpec = DS.getStorageClassSpec();
  StorageClass SC = StorageClassSpecToVarDeclStorageClass(DS);
  if (SCSpec == DeclSpec::SCS_mutable) {
    // mutable can only appear on non-static class members, so it's always
    // an error here
    Diag(Record->getLocation(), diag::err_mutable_nonmember);
    Invalid = true;
    SC = SC_None;
  }

  assert(DS.getAttributes().empty() && "No attribute expected")(static_ca