r191064 - Switch the semantic DeclContext for a block-scope declaration of a function or

Argyrios Kyrtzidis kyrtzidis at apple.com
Tue Dec 10 18:44:10 PST 2013


Ping ?

On Dec 5, 2013, at 10:16 PM, Argyrios Kyrtzidis <kyrtzidis at apple.com> wrote:

> Hi Richard,
> 
> This commit is causing a compiler error for the attached test case, could you look into it ?
> 
> $ clang -fsyntax-only t.cpp
> t.cpp:10:27: error: 'private_struct' is a private member of 'test'
>  extern int array[sizeof(private_struct)];
>                          ^
> t.cpp:3:10: note: declared private here
>  struct private_struct {
>         ^
> 1 error generated.
> 
> <t.cpp>
> On Sep 19, 2013, at 6:15 PM, Richard Smith <richard-llvm at metafoo.co.uk> wrote:
> 
>> Author: rsmith
>> Date: Thu Sep 19 20:15:31 2013
>> New Revision: 191064
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=191064&view=rev
>> Log:
>> Switch the semantic DeclContext for a block-scope declaration of a function or
>> variable from being the function to being the enclosing namespace scope (in
>> C++) or the TU (in C). This allows us to fix a selection of related issues
>> where we would build incorrect redeclaration chains for such declarations, and
>> fail to notice type mismatches.
>> 
>> Such declarations are put into a new IdentifierNamespace, IDNS_LocalExtern,
>> which is only found when searching scopes, and not found when searching
>> DeclContexts. Such a declaration is only made visible in its DeclContext if
>> there are no non-LocalExtern declarations.
>> 
>> Added:
>>   cfe/trunk/test/CXX/basic/basic.link/p7.cpp
>> Modified:
>>   cfe/trunk/include/clang/AST/Decl.h
>>   cfe/trunk/include/clang/AST/DeclBase.h
>>   cfe/trunk/include/clang/Sema/Lookup.h
>>   cfe/trunk/include/clang/Sema/Sema.h
>>   cfe/trunk/lib/Sema/SemaAccess.cpp
>>   cfe/trunk/lib/Sema/SemaCodeComplete.cpp
>>   cfe/trunk/lib/Sema/SemaDecl.cpp
>>   cfe/trunk/lib/Sema/SemaDeclCXX.cpp
>>   cfe/trunk/lib/Sema/SemaExpr.cpp
>>   cfe/trunk/lib/Sema/SemaLookup.cpp
>>   cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp
>>   cfe/trunk/lib/Serialization/ASTReaderDecl.cpp
>>   cfe/trunk/test/CXX/dcl.decl/dcl.meaning/dcl.array/p3.cpp
>>   cfe/trunk/test/CXX/drs/dr0xx.cpp
>>   cfe/trunk/test/CodeGenCXX/mangle.cpp
>>   cfe/trunk/test/Index/usrs.m
>>   cfe/trunk/test/Sema/struct-decl.c
>>   cfe/trunk/test/SemaCXX/blocks-1.cpp
>>   cfe/trunk/test/SemaCXX/cxx0x-initializer-references.cpp
>>   cfe/trunk/test/SemaCXX/extern-c.cpp
>>   cfe/trunk/test/SemaCXX/function-redecl.cpp
>>   cfe/trunk/test/SemaCXX/warn-unreachable.cpp
>>   cfe/trunk/www/cxx_dr_status.html
>> 
>> Modified: cfe/trunk/include/clang/AST/Decl.h
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/AST/Decl.h?rev=191064&r1=191063&r2=191064&view=diff
>> ==============================================================================
>> --- cfe/trunk/include/clang/AST/Decl.h (original)
>> +++ cfe/trunk/include/clang/AST/Decl.h Thu Sep 19 20:15:31 2013
>> @@ -873,7 +873,7 @@ public:
>>  bool isLocalVarDecl() const {
>>    if (getKind() != Decl::Var)
>>      return false;
>> -    if (const DeclContext *DC = getDeclContext())
>> +    if (const DeclContext *DC = getLexicalDeclContext())
>>      return DC->getRedeclContext()->isFunctionOrMethod();
>>    return false;
>>  }
>> @@ -883,7 +883,7 @@ public:
>>  bool isFunctionOrMethodVarDecl() const {
>>    if (getKind() != Decl::Var)
>>      return false;
>> -    const DeclContext *DC = getDeclContext()->getRedeclContext();
>> +    const DeclContext *DC = getLexicalDeclContext()->getRedeclContext();
>>    return DC->isFunctionOrMethod() && DC->getDeclKind() != Decl::Block;
>>  }
>> 
>> @@ -959,7 +959,7 @@ public:
>>    if (K == ParmVar || K == ImplicitParam)
>>      return false;
>> 
>> -    if (getDeclContext()->getRedeclContext()->isFileContext())
>> +    if (getLexicalDeclContext()->getRedeclContext()->isFileContext())
>>      return true;
>> 
>>    if (isStaticDataMember())
>> @@ -3472,10 +3472,8 @@ void Redeclarable<decl_type>::setPreviou
>> 
>>    // If the declaration was previously visible, a redeclaration of it remains
>>    // visible even if it wouldn't be visible by itself.
>> -    // FIXME: Once we handle local extern decls properly, this should inherit
>> -    // the visibility from MostRecent, not from PrevDecl.
>>    static_cast<decl_type*>(this)->IdentifierNamespace |=
>> -      PrevDecl->getIdentifierNamespace() &
>> +      MostRecent->getIdentifierNamespace() &
>>      (Decl::IDNS_Ordinary | Decl::IDNS_Tag | Decl::IDNS_Type);
>>  } else {
>>    // Make this first.
>> 
>> Modified: cfe/trunk/include/clang/AST/DeclBase.h
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/AST/DeclBase.h?rev=191064&r1=191063&r2=191064&view=diff
>> ==============================================================================
>> --- cfe/trunk/include/clang/AST/DeclBase.h (original)
>> +++ cfe/trunk/include/clang/AST/DeclBase.h Thu Sep 19 20:15:31 2013
>> @@ -159,7 +159,12 @@ public:
>>    /// This declaration is a C++ operator declared in a non-class
>>    /// context.  All such operators are also in IDNS_Ordinary.
>>    /// C++ lexical operator lookup looks for these.
>> -    IDNS_NonMemberOperator   = 0x0400
>> +    IDNS_NonMemberOperator   = 0x0400,
>> +
>> +    /// This declaration is a function-local extern declaration of a
>> +    /// variable or function. This may also be IDNS_Ordinary if it
>> +    /// has been declared outside any function.
>> +    IDNS_LocalExtern         = 0x0800
>>  };
>> 
>>  /// ObjCDeclQualifier - 'Qualifiers' written next to the return and
>> @@ -829,6 +834,32 @@ public:
>>  bool isFunctionOrFunctionTemplate() const;
>> 
>>  /// \brief Changes the namespace of this declaration to reflect that it's
>> +  /// a function-local extern declaration.
>> +  ///
>> +  /// These declarations appear in the lexical context of the extern
>> +  /// declaration, but in the semantic context of the enclosing namespace
>> +  /// scope.
>> +  void setLocalExternDecl() {
>> +    assert((IdentifierNamespace == IDNS_Ordinary ||
>> +            IdentifierNamespace == IDNS_OrdinaryFriend) &&
>> +           "namespace is not ordinary");
>> +
>> +    Decl *Prev = getPreviousDecl();
>> +    IdentifierNamespace &= ~IDNS_Ordinary;
>> +
>> +    IdentifierNamespace |= IDNS_LocalExtern;
>> +    if (Prev && Prev->getIdentifierNamespace() & IDNS_Ordinary)
>> +      IdentifierNamespace |= IDNS_Ordinary;
>> +  }
>> +
>> +  /// \brief Determine whether this is a block-scope declaration with linkage.
>> +  /// This will either be a local variable declaration declared 'extern', or a
>> +  /// local function declaration.
>> +  bool isLocalExternDecl() {
>> +    return IdentifierNamespace & IDNS_LocalExtern;
>> +  }
>> +
>> +  /// \brief Changes the namespace of this declaration to reflect that it's
>>  /// the object of a friend declaration.
>>  ///
>>  /// These declarations appear in the lexical context of the friending
>> @@ -838,22 +869,25 @@ public:
>>  void setObjectOfFriendDecl(bool PerformFriendInjection = false) {
>>    unsigned OldNS = IdentifierNamespace;
>>    assert((OldNS & (IDNS_Tag | IDNS_Ordinary |
>> -                     IDNS_TagFriend | IDNS_OrdinaryFriend)) &&
>> +                     IDNS_TagFriend | IDNS_OrdinaryFriend |
>> +                     IDNS_LocalExtern)) &&
>>           "namespace includes neither ordinary nor tag");
>>    assert(!(OldNS & ~(IDNS_Tag | IDNS_Ordinary | IDNS_Type |
>> -                       IDNS_TagFriend | IDNS_OrdinaryFriend)) &&
>> +                       IDNS_TagFriend | IDNS_OrdinaryFriend |
>> +                       IDNS_LocalExtern)) &&
>>           "namespace includes other than ordinary or tag");
>> 
>>    Decl *Prev = getPreviousDecl();
>> -    IdentifierNamespace = 0;
>> +    IdentifierNamespace &= ~(IDNS_Ordinary | IDNS_Tag | IDNS_Type);
>> +
>>    if (OldNS & (IDNS_Tag | IDNS_TagFriend)) {
>>      IdentifierNamespace |= IDNS_TagFriend;
>> -      if (PerformFriendInjection || 
>> +      if (PerformFriendInjection ||
>>          (Prev && Prev->getIdentifierNamespace() & IDNS_Tag))
>>        IdentifierNamespace |= IDNS_Tag | IDNS_Type;
>>    }
>> 
>> -    if (OldNS & (IDNS_Ordinary | IDNS_OrdinaryFriend)) {
>> +    if (OldNS & (IDNS_Ordinary | IDNS_OrdinaryFriend | IDNS_LocalExtern)) {
>>      IdentifierNamespace |= IDNS_OrdinaryFriend;
>>      if (PerformFriendInjection ||
>>          (Prev && Prev->getIdentifierNamespace() & IDNS_Ordinary))
>> 
>> Modified: cfe/trunk/include/clang/Sema/Lookup.h
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Sema/Lookup.h?rev=191064&r1=191063&r2=191064&view=diff
>> ==============================================================================
>> --- cfe/trunk/include/clang/Sema/Lookup.h (original)
>> +++ cfe/trunk/include/clang/Sema/Lookup.h Thu Sep 19 20:15:31 2013
>> @@ -613,6 +613,13 @@ public:
>>    return Filter(*this);
>>  }
>> 
>> +  void setFindLocalExtern(bool FindLocalExtern) {
>> +    if (FindLocalExtern)
>> +      IDNS |= Decl::IDNS_LocalExtern;
>> +    else
>> +      IDNS &= ~Decl::IDNS_LocalExtern;
>> +  }
>> +
>> private:
>>  void diagnose() {
>>    if (isAmbiguous())
>> 
>> Modified: cfe/trunk/include/clang/Sema/Sema.h
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Sema/Sema.h?rev=191064&r1=191063&r2=191064&view=diff
>> ==============================================================================
>> --- cfe/trunk/include/clang/Sema/Sema.h (original)
>> +++ cfe/trunk/include/clang/Sema/Sema.h Thu Sep 19 20:15:31 2013
>> @@ -1451,6 +1451,7 @@ public:
>>  bool diagnoseQualifiedDeclaration(CXXScopeSpec &SS, DeclContext *DC,
>>                                    DeclarationName Name,
>>                                    SourceLocation Loc);
>> +  static bool adjustContextForLocalExternDecl(DeclContext *&DC);
>>  void DiagnoseFunctionSpecifiers(const DeclSpec &DS);
>>  void CheckShadow(Scope *S, VarDecl *D, const LookupResult& R);
>>  void CheckShadow(Scope *S, VarDecl *D);
>> @@ -6465,8 +6466,9 @@ public:
>>  void
>>  BuildVariableInstantiation(VarDecl *NewVar, VarDecl *OldVar,
>>                             const MultiLevelTemplateArgumentList &TemplateArgs,
>> -                             LateInstantiatedAttrVec *LateAttrs = 0,
>> -                             LocalInstantiationScope *StartingScope = 0,
>> +                             LateInstantiatedAttrVec *LateAttrs,
>> +                             DeclContext *Owner,
>> +                             LocalInstantiationScope *StartingScope,
>>                             bool InstantiatingVarTemplate = false);
>>  void InstantiateVariableInitializer(
>>      VarDecl *Var, VarDecl *OldVar,
>> 
>> Modified: cfe/trunk/lib/Sema/SemaAccess.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaAccess.cpp?rev=191064&r1=191063&r2=191064&view=diff
>> ==============================================================================
>> --- cfe/trunk/lib/Sema/SemaAccess.cpp (original)
>> +++ cfe/trunk/lib/Sema/SemaAccess.cpp Thu Sep 19 20:15:31 2013
>> @@ -1483,7 +1483,9 @@ void Sema::HandleDelayedAccessCheck(Dela
>> 
>>  DeclContext *DC = D->getDeclContext();
>>  if (FunctionDecl *FN = dyn_cast<FunctionDecl>(D)) {
>> -    if (!DC->isFunctionOrMethod())
>> +    if (D->getLexicalDeclContext()->isFunctionOrMethod())
>> +      DC = D->getLexicalDeclContext();
>> +    else
>>      DC = FN;
>>  } else if (TemplateDecl *TD = dyn_cast<TemplateDecl>(D)) {
>>    DC = cast<DeclContext>(TD->getTemplatedDecl());
>> 
>> Modified: cfe/trunk/lib/Sema/SemaCodeComplete.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaCodeComplete.cpp?rev=191064&r1=191063&r2=191064&view=diff
>> ==============================================================================
>> --- cfe/trunk/lib/Sema/SemaCodeComplete.cpp (original)
>> +++ cfe/trunk/lib/Sema/SemaCodeComplete.cpp Thu Sep 19 20:15:31 2013
>> @@ -715,8 +715,8 @@ unsigned ResultBuilder::getBasePriority(
>>    return CCP_Unlikely;
>> 
>>  // Context-based decisions.
>> -  const DeclContext *DC = ND->getDeclContext()->getRedeclContext();
>> -  if (DC->isFunctionOrMethod() || isa<BlockDecl>(DC)) {
>> +  const DeclContext *LexicalDC = ND->getLexicalDeclContext();
>> +  if (LexicalDC->isFunctionOrMethod()) {
>>    // _cmd is relatively rare
>>    if (const ImplicitParamDecl *ImplicitParam =
>>        dyn_cast<ImplicitParamDecl>(ND))
>> @@ -726,6 +726,8 @@ unsigned ResultBuilder::getBasePriority(
>> 
>>    return CCP_LocalDeclaration;
>>  }
>> +
>> +  const DeclContext *DC = ND->getDeclContext()->getRedeclContext();
>>  if (DC->isRecord() || isa<ObjCContainerDecl>(DC))
>>    return CCP_MemberDeclaration;
>> 
>> @@ -876,8 +878,8 @@ void ResultBuilder::MaybeAddResult(Resul
>>    for (; I != IEnd; ++I) {
>>      // A tag declaration does not hide a non-tag declaration.
>>      if (I->first->hasTagIdentifierNamespace() &&
>> -          (IDNS & (Decl::IDNS_Member | Decl::IDNS_Ordinary | 
>> -                   Decl::IDNS_ObjCProtocol)))
>> +          (IDNS & (Decl::IDNS_Member | Decl::IDNS_Ordinary |
>> +                   Decl::IDNS_LocalExtern | Decl::IDNS_ObjCProtocol)))
>>        continue;
>> 
>>      // Protocols are in distinct namespaces from everything else.
>> @@ -1038,7 +1040,9 @@ void ResultBuilder::ExitScope() {
>> bool ResultBuilder::IsOrdinaryName(const NamedDecl *ND) const {
>>  ND = cast<NamedDecl>(ND->getUnderlyingDecl());
>> 
>> -  unsigned IDNS = Decl::IDNS_Ordinary;
>> +  // If name lookup finds a local extern declaration, then we are in a
>> +  // context where it behaves like an ordinary name.
>> +  unsigned IDNS = Decl::IDNS_Ordinary | Decl::IDNS_LocalExtern;
>>  if (SemaRef.getLangOpts().CPlusPlus)
>>    IDNS |= Decl::IDNS_Tag | Decl::IDNS_Namespace | Decl::IDNS_Member;
>>  else if (SemaRef.getLangOpts().ObjC1) {
>> @@ -1056,7 +1060,7 @@ bool ResultBuilder::IsOrdinaryNonTypeNam
>>  if (isa<TypeDecl>(ND) || isa<ObjCInterfaceDecl>(ND))
>>    return false;
>> 
>> -  unsigned IDNS = Decl::IDNS_Ordinary;
>> +  unsigned IDNS = Decl::IDNS_Ordinary | Decl::IDNS_LocalExtern;
>>  if (SemaRef.getLangOpts().CPlusPlus)
>>    IDNS |= Decl::IDNS_Tag | Decl::IDNS_Namespace | Decl::IDNS_Member;
>>  else if (SemaRef.getLangOpts().ObjC1) {
>> @@ -1083,7 +1087,7 @@ bool ResultBuilder::IsIntegralConstantVa
>> bool ResultBuilder::IsOrdinaryNonValueName(const NamedDecl *ND) const {
>>  ND = cast<NamedDecl>(ND->getUnderlyingDecl());
>> 
>> -  unsigned IDNS = Decl::IDNS_Ordinary;
>> +  unsigned IDNS = Decl::IDNS_Ordinary | Decl::IDNS_LocalExtern;
>>  if (SemaRef.getLangOpts().CPlusPlus)
>>    IDNS |= Decl::IDNS_Tag | Decl::IDNS_Namespace;
>> 
>> 
>> Modified: cfe/trunk/lib/Sema/SemaDecl.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDecl.cpp?rev=191064&r1=191063&r2=191064&view=diff
>> ==============================================================================
>> --- cfe/trunk/lib/Sema/SemaDecl.cpp (original)
>> +++ cfe/trunk/lib/Sema/SemaDecl.cpp Thu Sep 19 20:15:31 2013
>> @@ -1020,12 +1020,12 @@ void Sema::PushOnScopeChains(NamedDecl *
>>  if (AddToContext)
>>    CurContext->addDecl(D);
>> 
>> -  // Out-of-line definitions shouldn't be pushed into scope in C++.
>> -  // Out-of-line variable and function definitions shouldn't even in C.
>> -  if ((getLangOpts().CPlusPlus || isa<VarDecl>(D) || isa<FunctionDecl>(D)) &&
>> -      D->isOutOfLine() &&
>> +  // Out-of-line definitions shouldn't be pushed into scope in C++, unless they
>> +  // are function-local declarations.
>> +  if (getLangOpts().CPlusPlus && D->isOutOfLine() &&
>>      !D->getDeclContext()->getRedeclContext()->Equals(
>> -        D->getLexicalDeclContext()->getRedeclContext()))
>> +        D->getLexicalDeclContext()->getRedeclContext()) &&
>> +      !D->getLexicalDeclContext()->isFunctionOrMethod())
>>    return;
>> 
>>  // Template instantiations should also not be pushed into scope.
>> @@ -2426,7 +2426,9 @@ bool Sema::MergeFunctionDecl(FunctionDec
>>      ? New->getTypeSourceInfo()->getType()->castAs<FunctionType>()
>>      : NewType)->getResultType();
>>    QualType ResQT;
>> -    if (!Context.hasSameType(OldDeclaredReturnType, NewDeclaredReturnType)) {
>> +    if (!Context.hasSameType(OldDeclaredReturnType, NewDeclaredReturnType) &&
>> +        !((NewQType->isDependentType() || OldQType->isDependentType()) &&
>> +          New->isLocalExternDecl())) {
>>      if (NewDeclaredReturnType->isObjCObjectPointerType() &&
>>          OldDeclaredReturnType->isObjCObjectPointerType())
>>        ResQT = Context.mergeObjCGCQualifiers(NewQType, OldQType);
>> @@ -2578,6 +2580,14 @@ bool Sema::MergeFunctionDecl(FunctionDec
>>    if (OldQTypeForComparison == NewQType)
>>      return MergeCompatibleFunctionDecls(New, Old, S, MergeTypeWithOld);
>> 
>> +    if ((NewQType->isDependentType() || OldQType->isDependentType()) &&
>> +        New->isLocalExternDecl()) {
>> +      // It's OK if we couldn't merge types for a local function declaraton
>> +      // if either the old or new type is dependent. We'll merge the types
>> +      // when we instantiate the function.
>> +      return false;
>> +    }
>> +
>>    // Fall through for conflicting redeclarations and redefinitions.
>>  }
>> 
>> @@ -2710,7 +2720,7 @@ bool Sema::MergeFunctionDecl(FunctionDec
>>      // local declaration will produce a hard error; if it doesn't
>>      // remain visible, a single bogus local redeclaration (which is
>>      // actually only a warning) could break all the downstream code.
>> -      if (!New->getDeclContext()->isFunctionOrMethod())
>> +      if (!New->getLexicalDeclContext()->isFunctionOrMethod())
>>        New->getIdentifier()->setBuiltinID(Builtin::NotBuiltin);
>> 
>>      return false;
>> @@ -2820,18 +2830,21 @@ void Sema::MergeVarDeclTypes(VarDecl *Ne
>>                              NewArray->getElementType()))
>>        MergedT = New->getType();
>>    } else if (Old->getType()->isArrayType() &&
>> -             New->getType()->isIncompleteArrayType()) {
>> +               New->getType()->isIncompleteArrayType()) {
>>      const ArrayType *OldArray = Context.getAsArrayType(Old->getType());
>>      const ArrayType *NewArray = Context.getAsArrayType(New->getType());
>>      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 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()) {
>> @@ -4308,8 +4321,15 @@ NamedDecl *Sema::HandleDeclarator(Scope
>>  // If this has an identifier and is not an invalid redeclaration or 
>>  // function template specialization, add it to the scope stack.
>>  if (New->getDeclName() && AddToScope &&
>> -       !(D.isRedeclaration() && New->isInvalidDecl()))
>> -    PushOnScopeChains(New, S);
>> +       !(D.isRedeclaration() && New->isInvalidDecl())) {
>> +    // Only make a locally-scoped extern declaration visible if it is the first
>> +    // declaration of this entity. Qualified lookup for such an entity should
>> +    // only find this declaration if there is no visible declaration of it.
>> +    bool AddToContext = !D.isRedeclaration() || !New->isLocalExternDecl();
>> +    PushOnScopeChains(New, S, AddToContext);
>> +    if (!AddToContext)
>> +      CurContext->addHiddenDecl(New);
>> +  }
>> 
>>  return New;
>> }
>> @@ -4808,6 +4828,30 @@ static bool shouldConsiderLinkage(const
>>  llvm_unreachable("Unexpected context");
>> }
>> 
>> +/// Adjust the \c DeclContext for a function or variable that might be a
>> +/// function-local external declaration.
>> +bool Sema::adjustContextForLocalExternDecl(DeclContext *&DC) {
>> +  if (!DC->isFunctionOrMethod())
>> +    return false;
>> +
>> +  // If this is a local extern function or variable declared within a function
>> +  // template, don't add it into the enclosing namespace scope until it is
>> +  // instantiated; it might have a dependent type right now.
>> +  if (DC->isDependentContext())
>> +    return true;
>> +
>> +  // C++11 [basic.link]p7:
>> +  //   When a block scope declaration of an entity with linkage is not found to
>> +  //   refer to some other declaration, then that entity is a member of the
>> +  //   innermost enclosing namespace.
>> +  //
>> +  // Per C++11 [namespace.def]p6, the innermost enclosing namespace is a
>> +  // semantically-enclosing namespace, not a lexically-enclosing one.
>> +  while (!DC->isFileContext() && !isa<LinkageSpecDecl>(DC))
>> +    DC = DC->getParent();
>> +  return true;
>> +}
>> +
>> NamedDecl *
>> Sema::ActOnVariableDeclarator(Scope *S, Declarator &D, DeclContext *DC,
>>                              TypeSourceInfo *TInfo, LookupResult &Previous,
>> @@ -4820,6 +4864,10 @@ Sema::ActOnVariableDeclarator(Scope *S,
>>  VarDecl::StorageClass SC =
>>    StorageClassSpecToVarDeclStorageClass(D.getDeclSpec());
>> 
>> +  DeclContext *OriginalDC = DC;
>> +  bool IsLocalExternDecl = SC == SC_Extern &&
>> +                           adjustContextForLocalExternDecl(DC);
>> +
>>  if (getLangOpts().OpenCL && !getOpenCLOptions().cl_khr_fp16) {
>>    // OpenCL v1.2 s6.1.1.1: reject declaring variables of the half and
>>    // half array type (unless the cl_khr_fp16 extension is enabled).
>> @@ -5150,6 +5198,9 @@ Sema::ActOnVariableDeclarator(Scope *S,
>>  if (NewTemplate)
>>    NewTemplate->setLexicalDeclContext(CurContext);
>> 
>> +  if (IsLocalExternDecl)
>> +    NewVD->setLocalExternDecl();
>> +
>>  if (DeclSpec::TSCS TSCS = D.getDeclSpec().getThreadStorageClassSpec()) {
>>    if (NewVD->hasLocalStorage()) {
>>      // C++11 [dcl.stc]p4:
>> @@ -5277,7 +5328,7 @@ Sema::ActOnVariableDeclarator(Scope *S,
>>  // scope and are out-of-semantic-context declarations (if the new
>>  // declaration has linkage).
>>  FilterLookupForScope(
>> -      Previous, DC, S, shouldConsiderLinkage(NewVD),
>> +      Previous, OriginalDC, S, shouldConsiderLinkage(NewVD),
>>      IsExplicitSpecialization || IsVariableTemplateSpecialization);
>> 
>>  // Check whether the previous declaration is in the same block scope. This
>> @@ -5286,7 +5337,7 @@ Sema::ActOnVariableDeclarator(Scope *S,
>>      NewVD->isLocalVarDecl() && NewVD->hasExternalStorage())
>>    NewVD->setPreviousDeclInSameBlockScope(
>>        Previous.isSingleResult() && !Previous.isShadowed() &&
>> -        isDeclInScope(Previous.getFoundDecl(), DC, S, false));
>> +        isDeclInScope(Previous.getFoundDecl(), OriginalDC, S, false));
>> 
>>  if (!getLangOpts().CPlusPlus) {
>>    D.setRedeclaration(CheckVariableDeclaration(NewVD, Previous));
>> @@ -5543,12 +5594,8 @@ static bool checkForConflictWithNonVisib
>>                                                  LookupResult &Previous) {
>>  if (!S.getLangOpts().CPlusPlus) {
>>    // In C, when declaring a global variable, look for a corresponding 'extern'
>> -    // variable declared in function scope.
>> -    //
>> -    // FIXME: The corresponding case in C++ does not work.  We should instead
>> -    // set the semantic DC for an extern local variable to be the innermost
>> -    // enclosing namespace, and ensure they are only found by redeclaration
>> -    // lookup.
>> +    // variable declared in function scope. We don't need this in C++, because
>> +    // we find local extern decls in the surrounding file-scope DeclContext.
>>    if (ND->getDeclContext()->getRedeclContext()->isTranslationUnit()) {
>>      if (NamedDecl *Prev = S.findLocallyScopedExternCDecl(ND->getDeclName())) {
>>        Previous.clear();
>> @@ -6032,6 +6079,7 @@ static NamedDecl *DiagnoseInvalidRedecla
>>    bool FDisConst = MD && MD->isConst();
>>    bool IsMember = MD || !IsLocalFriend;
>> 
>> +    // FIXME: These notes are poorly worded for the local friend case.
>>    if (unsigned Idx = NearMatch->second) {
>>      ParmVarDecl *FDParam = FD->getParamDecl(Idx-1);
>>      SourceLocation Loc = FDParam->getTypeSpecStartLoc();
>> @@ -6455,6 +6503,9 @@ Sema::ActOnFunctionDeclarator(Scope *S,
>> 
>>  bool isVirtualOkay = false;
>> 
>> +  DeclContext *OriginalDC = DC;
>> +  bool IsLocalExternDecl = adjustContextForLocalExternDecl(DC);
>> +
>>  FunctionDecl *NewFD = CreateNewFunctionDecl(*this, D, DC, R, TInfo, SC,
>>                                              isVirtualOkay);
>>  if (!NewFD) return 0;
>> @@ -6462,6 +6513,14 @@ Sema::ActOnFunctionDeclarator(Scope *S,
>>  if (OriginalLexicalContext && OriginalLexicalContext->isObjCContainer())
>>    NewFD->setTopLevelDeclInObjCContainer();
>> 
>> +  // Set the lexical context. If this is a function-scope declaration, or has a
>> +  // C++ scope specifier, or is the object of a friend declaration, the lexical
>> +  // context will be different from the semantic context.
>> +  NewFD->setLexicalDeclContext(CurContext);
>> +
>> +  if (IsLocalExternDecl)
>> +    NewFD->setLocalExternDecl();
>> +
>>  if (getLangOpts().CPlusPlus) {
>>    bool isInline = D.getDeclSpec().isInlineSpecified();
>>    bool isVirtual = D.getDeclSpec().isVirtualSpecified();
>> @@ -6489,12 +6548,7 @@ Sema::ActOnFunctionDeclarator(Scope *S,
>>    isFunctionTemplateSpecialization = false;
>>    if (D.isInvalidType())
>>      NewFD->setInvalidDecl();
>> -    
>> -    // Set the lexical context. If the declarator has a C++
>> -    // scope specifier, or is the object of a friend declaration, the
>> -    // lexical context will be different from the semantic context.
>> -    NewFD->setLexicalDeclContext(CurContext);
>> -        
>> +
>>    // Match up the template parameter lists with the scope specifier, then
>>    // determine whether we have a template or a template specialization.
>>    bool Invalid = false;
>> @@ -6750,7 +6804,7 @@ Sema::ActOnFunctionDeclarator(Scope *S,
>>  }
>> 
>>  // Filter out previous declarations that don't match the scope.
>> -  FilterLookupForScope(Previous, DC, S, shouldConsiderLinkage(NewFD),
>> +  FilterLookupForScope(Previous, OriginalDC, S, shouldConsiderLinkage(NewFD),
>>                       isExplicitSpecialization ||
>>                       isFunctionTemplateSpecialization);
>> 
>> @@ -9232,21 +9286,21 @@ static bool ShouldWarnAboutMissingProtot
>>  // Don't warn for OpenCL kernels.
>>  if (FD->hasAttr<OpenCLKernelAttr>())
>>    return false;
>> -  
>> +
>>  bool MissingPrototype = true;
>>  for (const FunctionDecl *Prev = FD->getPreviousDecl();
>>       Prev; Prev = Prev->getPreviousDecl()) {
>>    // Ignore any declarations that occur in function or method
>>    // scope, because they aren't visible from the header.
>> -    if (Prev->getDeclContext()->isFunctionOrMethod())
>> +    if (Prev->getLexicalDeclContext()->isFunctionOrMethod())
>>      continue;
>> -      
>> +
>>    MissingPrototype = !Prev->getType()->isFunctionProtoType();
>>    if (FD->getNumParams() == 0)
>>      PossibleZeroParamPrototype = Prev;
>>    break;
>>  }
>> -    
>> +
>>  return MissingPrototype;
>> }
>> 
>> 
>> Modified: cfe/trunk/lib/Sema/SemaDeclCXX.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDeclCXX.cpp?rev=191064&r1=191063&r2=191064&view=diff
>> ==============================================================================
>> --- cfe/trunk/lib/Sema/SemaDeclCXX.cpp (original)
>> +++ cfe/trunk/lib/Sema/SemaDeclCXX.cpp Thu Sep 19 20:15:31 2013
>> @@ -438,9 +438,9 @@ bool Sema::MergeCXXFunctionDecl(Function
>>  //   declaration (not even to the same value).
>>  //
>>  // C++ [dcl.fct.default]p6:
>> -  //   Except for member functions of class templates, the default arguments 
>> -  //   in a member function definition that appears outside of the class 
>> -  //   definition are added to the set of default arguments provided by the 
>> +  //   Except for member functions of class templates, the default arguments
>> +  //   in a member function definition that appears outside of the class
>> +  //   definition are added to the set of default arguments provided by the
>>  //   member function declaration in the class definition.
>>  for (unsigned p = 0, NumParams = Old->getNumParams(); p < NumParams; ++p) {
>>    ParmVarDecl *OldParam = Old->getParamDecl(p);
>> @@ -450,9 +450,18 @@ bool Sema::MergeCXXFunctionDecl(Function
>>    bool NewParamHasDfl = NewParam->hasDefaultArg();
>> 
>>    NamedDecl *ND = Old;
>> -    if (S && !isDeclInScope(ND, New->getDeclContext(), S))
>> +
>> +    // The declaration context corresponding to the scope is the semantic
>> +    // parent, unless this is a local function declaration, in which case
>> +    // it is that surrounding function.
>> +    DeclContext *ScopeDC = New->getLexicalDeclContext();
>> +    if (!ScopeDC->isFunctionOrMethod())
>> +      ScopeDC = New->getDeclContext();
>> +    if (S && !isDeclInScope(ND, ScopeDC, S) &&
>> +        !New->getDeclContext()->isRecord())
>>      // Ignore default parameters of old decl if they are not in
>> -      // the same scope.
>> +      // the same scope and this is not an out-of-line definition of
>> +      // a member function.
>>      OldParamHasDfl = false;
>> 
>>    if (OldParamHasDfl && NewParamHasDfl) {
>> @@ -11486,6 +11495,7 @@ NamedDecl *Sema::ActOnFriendFunctionDecl
>>      // declared the function in, if we were permitted to, for error recovery.
>>      DC = FunctionContainingLocalClass;
>>    }
>> +    adjustContextForLocalExternDecl(DC);
>> 
>>    // C++ [class.friend]p6:
>>    //   A function can be defined in a friend declaration of a class if and
>> 
>> Modified: cfe/trunk/lib/Sema/SemaExpr.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExpr.cpp?rev=191064&r1=191063&r2=191064&view=diff
>> ==============================================================================
>> --- cfe/trunk/lib/Sema/SemaExpr.cpp (original)
>> +++ cfe/trunk/lib/Sema/SemaExpr.cpp Thu Sep 19 20:15:31 2013
>> @@ -2459,7 +2459,7 @@ bool Sema::UseArgumentDependentLookup(co
>>    // turn off ADL anyway).
>>    if (isa<UsingShadowDecl>(D))
>>      D = cast<UsingShadowDecl>(D)->getTargetDecl();
>> -    else if (D->getDeclContext()->isFunctionOrMethod())
>> +    else if (D->getLexicalDeclContext()->isFunctionOrMethod())
>>      return false;
>> 
>>    // C++0x [basic.lookup.argdep]p3:
>> 
>> Modified: cfe/trunk/lib/Sema/SemaLookup.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaLookup.cpp?rev=191064&r1=191063&r2=191064&view=diff
>> ==============================================================================
>> --- cfe/trunk/lib/Sema/SemaLookup.cpp (original)
>> +++ cfe/trunk/lib/Sema/SemaLookup.cpp Thu Sep 19 20:15:31 2013
>> @@ -223,6 +223,8 @@ static inline unsigned getIDNS(Sema::Loo
>>      if (Redeclaration)
>>        IDNS |= Decl::IDNS_TagFriend | Decl::IDNS_OrdinaryFriend;
>>    }
>> +    if (Redeclaration)
>> +      IDNS |= Decl::IDNS_LocalExtern;
>>    break;
>> 
>>  case Sema::LookupOperatorName:
>> @@ -847,6 +849,26 @@ static std::pair<DeclContext *, bool> fi
>>  return std::make_pair(Lexical, false);
>> }
>> 
>> +namespace {
>> +/// An RAII object to specify that we want to find block scope extern
>> +/// declarations.
>> +struct FindLocalExternScope {
>> +  FindLocalExternScope(LookupResult &R)
>> +      : R(R), OldFindLocalExtern(R.getIdentifierNamespace() &
>> +                                 Decl::IDNS_LocalExtern) {
>> +    R.setFindLocalExtern(R.getIdentifierNamespace() & Decl::IDNS_Ordinary);
>> +  }
>> +  void restore() {
>> +    R.setFindLocalExtern(OldFindLocalExtern);
>> +  }
>> +  ~FindLocalExternScope() {
>> +    restore();
>> +  }
>> +  LookupResult &R;
>> +  bool OldFindLocalExtern;
>> +};
>> +}
>> +
>> bool Sema::CppLookupName(LookupResult &R, Scope *S) {
>>  assert(getLangOpts().CPlusPlus && "Can perform only C++ lookup");
>> 
>> @@ -891,6 +913,10 @@ bool Sema::CppLookupName(LookupResult &R
>>  bool VisitedUsingDirectives = false;
>>  bool LeftStartingScope = false;
>>  DeclContext *OutsideOfTemplateParamDC = 0;
>> +
>> +  // When performing a scope lookup, we want to find local extern decls.
>> +  FindLocalExternScope FindLocals(R);
>> +
>>  for (; S && !isNamespaceOrTranslationUnitScope(S); S = S->getParent()) {
>>    DeclContext *Ctx = static_cast<DeclContext*>(S->getEntity());
>> 
>> @@ -1046,7 +1072,12 @@ bool Sema::CppLookupName(LookupResult &R
>>    UDirs.visitScopeChain(Initial, S);
>>    UDirs.done();
>>  }
>> -  
>> +
>> +  // If we're not performing redeclaration lookup, do not look for local
>> +  // extern declarations outside of a function scope.
>> +  if (!R.isForRedeclaration())
>> +    FindLocals.restore();
>> +
>>  // Lookup namespace scope, and global scope.
>>  // Unqualified name lookup in C++ requires looking into scopes
>>  // that aren't strictly lexical, and therefore we walk through the
>> @@ -1292,6 +1323,9 @@ bool Sema::LookupName(LookupResult &R, S
>>        S = S->getParent();
>>    }
>> 
>> +    // When performing a scope lookup, we want to find local extern decls.
>> +    FindLocalExternScope FindLocals(R);
>> +
>>    // Scan up the scope chain looking for a decl that matches this
>>    // identifier that is in the appropriate namespace.  This search
>>    // should not take long, as shadowing of names is uncommon, and
>> @@ -1361,6 +1395,7 @@ bool Sema::LookupName(LookupResult &R, S
>> 
>>          R.resolveKind();
>>        }
>> +
>>        return true;
>>      }
>>  } else {
>> @@ -2858,7 +2893,11 @@ void Sema::ArgumentDependentLookup(Decla
>>      NamedDecl *D = *I;
>>      // If the only declaration here is an ordinary friend, consider
>>      // it only if it was declared in an associated classes.
>> -      if (D->getIdentifierNamespace() == Decl::IDNS_OrdinaryFriend) {
>> +      if ((D->getIdentifierNamespace() & Decl::IDNS_Ordinary) == 0) {
>> +        // If it's neither ordinarily visible nor a friend, we can't find it.
>> +        if ((D->getIdentifierNamespace() & Decl::IDNS_OrdinaryFriend) == 0)
>> +          continue;
>> +
>>        bool DeclaredInAssociatedClass = false;
>>        for (Decl *DI = D; DI; DI = DI->getPreviousDecl()) {
>>          DeclContext *LexDC = DI->getLexicalDeclContext();
>> @@ -3160,6 +3199,7 @@ static void LookupVisibleDecls(Scope *S,
>>      (!S->getParent() &&
>>       !Visited.alreadyVisitedContext((DeclContext *)S->getEntity())) ||
>>      ((DeclContext *)S->getEntity())->isFunctionOrMethod()) {
>> +    FindLocalExternScope FindLocals(Result);
>>    // Walk through the declarations in this Scope.
>>    for (Scope::decl_iterator D = S->decl_begin(), DEnd = S->decl_end();
>>         D != DEnd; ++D) {
>> 
>> Modified: cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp?rev=191064&r1=191063&r2=191064&view=diff
>> ==============================================================================
>> --- cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp (original)
>> +++ cfe/trunk/lib/Sema/SemaTemplateInstantiateDecl.cpp Thu Sep 19 20:15:31 2013
>> @@ -347,8 +347,12 @@ Decl *TemplateDeclInstantiator::VisitVar
>>    return 0;
>>  }
>> 
>> +  DeclContext *DC = Owner;
>> +  if (D->isLocalExternDecl())
>> +    SemaRef.adjustContextForLocalExternDecl(DC);
>> +
>>  // Build the instantiated declaration.
>> -  VarDecl *Var = VarDecl::Create(SemaRef.Context, Owner, D->getInnerLocStart(),
>> +  VarDecl *Var = VarDecl::Create(SemaRef.Context, DC, D->getInnerLocStart(),
>>                                 D->getLocation(), D->getIdentifier(),
>>                                 DI->getType(), DI, D->getStorageClass());
>> 
>> @@ -361,7 +365,7 @@ Decl *TemplateDeclInstantiator::VisitVar
>>  if (SubstQualifier(D, Var))
>>    return 0;
>> 
>> -  SemaRef.BuildVariableInstantiation(Var, D, TemplateArgs, LateAttrs,
>> +  SemaRef.BuildVariableInstantiation(Var, D, TemplateArgs, LateAttrs, Owner,
>>                                     StartingScope, InstantiatingVarTemplate);
>>  return Var;
>> }
>> @@ -1199,11 +1203,13 @@ Decl *TemplateDeclInstantiator::VisitFun
>>  }
>> 
>>  // If we're instantiating a local function declaration, put the result
>> -  // in the owner;  otherwise we need to find the instantiated context.
>> +  // in the enclosing namespace; otherwise we need to find the instantiated
>> +  // context.
>>  DeclContext *DC;
>> -  if (D->getDeclContext()->isFunctionOrMethod())
>> +  if (D->isLocalExternDecl()) {
>>    DC = Owner;
>> -  else if (isFriend && QualifierLoc) {
>> +    SemaRef.adjustContextForLocalExternDecl(DC);
>> +  } else if (isFriend && QualifierLoc) {
>>    CXXScopeSpec SS;
>>    SS.Adopt(QualifierLoc);
>>    DC = SemaRef.computeDeclContext(SS);
>> @@ -1227,8 +1233,11 @@ Decl *TemplateDeclInstantiator::VisitFun
>>  if (QualifierLoc)
>>    Function->setQualifierInfo(QualifierLoc);
>> 
>> +  if (D->isLocalExternDecl())
>> +    Function->setLocalExternDecl();
>> +
>>  DeclContext *LexicalDC = Owner;
>> -  if (!isFriend && D->isOutOfLine()) {
>> +  if (!isFriend && D->isOutOfLine() && !D->isLocalExternDecl()) {
>>    assert(D->getDeclContext()->isFileContext());
>>    LexicalDC = D->getDeclContext();
>>  }
>> @@ -1294,8 +1303,11 @@ Decl *TemplateDeclInstantiator::VisitFun
>> 
>>  bool isExplicitSpecialization = false;
>> 
>> -  LookupResult Previous(SemaRef, Function->getDeclName(), SourceLocation(),
>> -                        Sema::LookupOrdinaryName, Sema::ForRedeclaration);
>> +  LookupResult Previous(
>> +      SemaRef, Function->getDeclName(), SourceLocation(),
>> +      D->isLocalExternDecl() ? Sema::LookupRedeclarationWithLinkage
>> +                             : Sema::LookupOrdinaryName,
>> +      Sema::ForRedeclaration);
>> 
>>  if (DependentFunctionTemplateSpecializationInfo *Info
>>        = D->getDependentSpecializationInfo()) {
>> @@ -1427,6 +1439,9 @@ Decl *TemplateDeclInstantiator::VisitFun
>>    }
>>  }
>> 
>> +  if (Function->isLocalExternDecl() && !Function->getPreviousDecl())
>> +    DC->makeDeclVisibleInContext(PrincipalDecl);
>> +
>>  if (Function->isOverloadedOperator() && !DC->isRecord() &&
>>      PrincipalDecl->isInIdentifierNamespace(Decl::IDNS_Ordinary))
>>    PrincipalDecl->setNonMemberOperator();
>> @@ -2358,7 +2373,7 @@ Decl *TemplateDeclInstantiator::VisitVar
>>    return 0;
>> 
>>  SemaRef.BuildVariableInstantiation(Var, D, TemplateArgs, LateAttrs,
>> -                                     StartingScope);
>> +                                     Owner, StartingScope);
>> 
>>  return Var;
>> }
>> @@ -2680,7 +2695,7 @@ TemplateDeclInstantiator::InstantiateVar
>>  if (VarDecl *Def = PartialSpec->getDefinition(SemaRef.getASTContext()))
>>    PartialSpec = cast<VarTemplatePartialSpecializationDecl>(Def);
>>  SemaRef.BuildVariableInstantiation(InstPartialSpec, PartialSpec, TemplateArgs,
>> -                                     LateAttrs, StartingScope);
>> +                                     LateAttrs, Owner, StartingScope);
>>  InstPartialSpec->setInit(PartialSpec->getInit());
>> 
>>  return InstPartialSpec;
>> @@ -3335,13 +3350,19 @@ VarTemplateSpecializationDecl *Sema::Com
>> void Sema::BuildVariableInstantiation(
>>    VarDecl *NewVar, VarDecl *OldVar,
>>    const MultiLevelTemplateArgumentList &TemplateArgs,
>> -    LateInstantiatedAttrVec *LateAttrs, LocalInstantiationScope *StartingScope,
>> +    LateInstantiatedAttrVec *LateAttrs, DeclContext *Owner,
>> +    LocalInstantiationScope *StartingScope,
>>    bool InstantiatingVarTemplate) {
>> 
>> +  // If we are instantiating a local extern declaration, the
>> +  // instantiation belongs lexically to the containing function.
>>  // If we are instantiating a static data member defined
>>  // out-of-line, the instantiation will have the same lexical
>>  // context (which will be a namespace scope) as the template.
>> -  if (OldVar->isOutOfLine())
>> +  if (OldVar->isLocalExternDecl()) {
>> +    NewVar->setLocalExternDecl();
>> +    NewVar->setLexicalDeclContext(Owner);
>> +  } else if (OldVar->isOutOfLine())
>>    NewVar->setLexicalDeclContext(OldVar->getLexicalDeclContext());
>>  NewVar->setTSCSpec(OldVar->getTSCSpec());
>>  NewVar->setInitStyle(OldVar->getInitStyle());
>> @@ -3374,11 +3395,13 @@ void Sema::BuildVariableInstantiation(
>>  if (NewVar->hasAttrs())
>>    CheckAlignasUnderalignment(NewVar);
>> 
>> -  LookupResult Previous(*this, NewVar->getDeclName(), NewVar->getLocation(),
>> -                        Sema::LookupOrdinaryName, Sema::ForRedeclaration);
>> +  LookupResult Previous(
>> +      *this, NewVar->getDeclName(), NewVar->getLocation(),
>> +      NewVar->isLocalExternDecl() ? Sema::LookupRedeclarationWithLinkage
>> +                                  : Sema::LookupOrdinaryName,
>> +      Sema::ForRedeclaration);
>> 
>> -  if (NewVar->getLexicalDeclContext()->isFunctionOrMethod() &&
>> -      OldVar->getPreviousDecl()) {
>> +  if (NewVar->isLocalExternDecl() && OldVar->getPreviousDecl()) {
>>    // We have a previous declaration. Use that one, so we merge with the
>>    // right type.
>>    if (NamedDecl *NewPrev = FindInstantiatedDecl(
>> @@ -3389,13 +3412,13 @@ void Sema::BuildVariableInstantiation(
>>    LookupQualifiedName(Previous, NewVar->getDeclContext(), false);
>>  CheckVariableDeclaration(NewVar, Previous);
>> 
>> -  if (OldVar->isOutOfLine()) {
>> -    OldVar->getLexicalDeclContext()->addDecl(NewVar);
>> -    if (!InstantiatingVarTemplate)
>> +  if (!InstantiatingVarTemplate) {
>> +    NewVar->getLexicalDeclContext()->addHiddenDecl(NewVar);
>> +    if (!NewVar->isLocalExternDecl() || !NewVar->getPreviousDecl())
>>      NewVar->getDeclContext()->makeDeclVisibleInContext(NewVar);
>> -  } else {
>> -    if (!InstantiatingVarTemplate)
>> -      NewVar->getDeclContext()->addDecl(NewVar);
>> +  }
>> +
>> +  if (!OldVar->isOutOfLine()) {
>>    if (NewVar->getDeclContext()->isFunctionOrMethod())
>>      CurrentInstantiationScope->InstantiatedLocal(OldVar, NewVar);
>>  }
>> 
>> Modified: cfe/trunk/lib/Serialization/ASTReaderDecl.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Serialization/ASTReaderDecl.cpp?rev=191064&r1=191063&r2=191064&view=diff
>> ==============================================================================
>> --- cfe/trunk/lib/Serialization/ASTReaderDecl.cpp (original)
>> +++ cfe/trunk/lib/Serialization/ASTReaderDecl.cpp Thu Sep 19 20:15:31 2013
>> @@ -946,7 +946,13 @@ ASTDeclReader::RedeclarableResult ASTDec
>>  VD->VarDeclBits.ARCPseudoStrong = Record[Idx++];
>>  VD->VarDeclBits.IsConstexpr = Record[Idx++];
>>  VD->VarDeclBits.PreviousDeclInSameBlockScope = Record[Idx++];
>> -  VD->setCachedLinkage(Linkage(Record[Idx++]));
>> +  Linkage VarLinkage = Linkage(Record[Idx++]);
>> +  VD->setCachedLinkage(VarLinkage);
>> +
>> +  // Reconstruct the one piece of the IdentifierNamespace that we need.
>> +  if (VarLinkage != NoLinkage &&
>> +      VD->getLexicalDeclContext()->isFunctionOrMethod())
>> +    VD->setLocalExternDecl();
>> 
>>  // Only true variables (not parameters or implicit parameters) can be merged.
>>  if (VD->getKind() != Decl::ParmVar && VD->getKind() != Decl::ImplicitParam)
>> @@ -2199,8 +2205,6 @@ void ASTDeclReader::attachPreviousDecl(D
>>  //
>>  // FIXME: In this case, the declaration should only be visible if a module
>>  //        that makes it visible has been imported.
>> -  // FIXME: This is not correct in the case where previous is a local extern
>> -  //        declaration and D is a friend declaraton.
>>  D->IdentifierNamespace |=
>>      previous->IdentifierNamespace &
>>      (Decl::IDNS_Ordinary | Decl::IDNS_Tag | Decl::IDNS_Type);
>> 
>> Added: cfe/trunk/test/CXX/basic/basic.link/p7.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CXX/basic/basic.link/p7.cpp?rev=191064&view=auto
>> ==============================================================================
>> --- cfe/trunk/test/CXX/basic/basic.link/p7.cpp (added)
>> +++ cfe/trunk/test/CXX/basic/basic.link/p7.cpp Thu Sep 19 20:15:31 2013
>> @@ -0,0 +1,73 @@
>> +// RUN: %clang_cc1 -verify -std=c++1y %s
>> +
>> +// Example from the standard.
>> +namespace X {
>> +  void p() {
>> +    q(); // expected-error {{undeclared}}
>> +    extern void q();
>> +  }
>> +  void middle() {
>> +    q(); // expected-error {{undeclared}}
>> +  }
>> +  void q() { /*...*/ }
>> +  void bottom() {
>> +    q();
>> +  }
>> +}
>> +int q();
>> +
>> +namespace Test1 {
>> +  void f() {
>> +    extern int a; // expected-note {{previous}}
>> +    int g(void); // expected-note {{previous}}
>> +  }
>> +  double a; // expected-error {{different type: 'double' vs 'int'}}
>> +  double g(); // expected-error {{differ only in their return type}}
>> +}
>> +
>> +namespace Test2 {
>> +  void f() {
>> +    extern int a; // expected-note {{previous}}
>> +    int g(void); // expected-note {{previous}}
>> +  }
>> +  void h() {
>> +    extern double a; // expected-error {{different type: 'double' vs 'int'}}
>> +    double g(void); // expected-error {{differ only in their return type}}
>> +  }
>> +}
>> +
>> +namespace Test3 {
>> +  constexpr void (*f())() {
>> +    void h();
>> +    return &h;
>> +  }
>> +  constexpr void (*g())() {
>> +    void h();
>> +    return &h;
>> +  }
>> +  static_assert(f() == g(), "");
>> +}
>> +
>> +namespace Test4 {
>> +  template<typename T>
>> +  constexpr void (*f())() {
>> +    void h();
>> +    return &h;
>> +  }
>> +  static_assert(f<int>() == f<char>(), "");
>> +  void h();
>> +  static_assert(f<int>() == &h, "");
>> +}
>> +
>> +namespace Test5 {
>> +  constexpr auto f() -> void (*)() {
>> +    void g();
>> +    struct X {
>> +      friend void g();
>> +      static constexpr auto h() -> void (*)() { return g; }
>> +    };
>> +    return X::h();
>> +  }
>> +  void g();
>> +  static_assert(f() == g, "");
>> +}
>> 
>> Modified: cfe/trunk/test/CXX/dcl.decl/dcl.meaning/dcl.array/p3.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CXX/dcl.decl/dcl.meaning/dcl.array/p3.cpp?rev=191064&r1=191063&r2=191064&view=diff
>> ==============================================================================
>> --- cfe/trunk/test/CXX/dcl.decl/dcl.meaning/dcl.array/p3.cpp (original)
>> +++ cfe/trunk/test/CXX/dcl.decl/dcl.meaning/dcl.array/p3.cpp Thu Sep 19 20:15:31 2013
>> @@ -61,6 +61,8 @@ namespace test6 {
>>      int x = sizeof(array); // expected-error {{invalid application of 'sizeof' to an incomplete type 'int []'}}
>>    }
>>    int y = sizeof(array);
>> +    extern int array[];
>> +    int z = sizeof(array);
>>  }
>> }
>> 
>> @@ -71,6 +73,19 @@ namespace test7 {
>>    int x = sizeof(array); // expected-error {{invalid application of 'sizeof' to an incomplete type 'int []'}}
>>  }
>>  int y = sizeof(array);
>> +  extern int array[];
>> +  int z = sizeof(array);
>> +}
>> +
>> +namespace test8 {
>> +  extern int array[];
>> +  void test() {
>> +    extern int array[100];
>> +    int x = sizeof(array);
>> +  }
>> +  int y = sizeof(array); // expected-error {{invalid application of 'sizeof' to an incomplete type 'int []'}}
>> +  extern int array[];
>> +  int z = sizeof(array); // expected-error {{invalid application of 'sizeof' to an incomplete type 'int []'}}
>> }
>> 
>> namespace dependent {
>> @@ -143,10 +158,52 @@ namespace dependent {
>>  }
>> 
>>  template<typename T> void n() {
>> -    extern T n_var;
>> +    extern T n_var; // expected-error {{redefinition of 'n_var' with a different type: 'double' vs 'int'}} expected-note {{previous}}
>> +    extern T n_fn(); // expected-error {{functions that differ only in their return type cannot be overloaded}} expected-note {{previous}}
>>  }
>>  template void n<int>();
>> -  // FIXME: Diagnose this!
>> -  float n_var;
>> -  template void n<double>();
>> +  template void n<double>(); // expected-note {{in instantiation of}}
>> +
>> +  template<typename T> void o() {
>> +    extern T o_var; // expected-note {{previous}}
>> +    extern T o_fn(); // expected-note {{previous}}
>> +  }
>> +  template void o<int>();
>> +  float o_var; // expected-error {{redefinition of 'o_var' with a different type: 'float' vs 'int'}}
>> +  float o_fn(); // expected-error {{functions that differ only in their return type cannot be overloaded}}
>> +
>> +  int p_var;
>> +  int p_fn();
>> +  template<typename T> void p() {
>> +    extern T p_var;
>> +    extern T p_fn();
>> +  }
>> +}
>> +
>> +namespace use_outside_ns {
>> +  namespace A {
>> +    extern int a[3];
>> +    extern int b[];
>> +    extern int c[3];
>> +    void f() {
>> +      extern int a[];
>> +      extern int b[3];
>> +    }
>> +    template<typename T> void x() {
>> +      extern T c;
>> +      extern T d;
>> +    }
>> +    extern int d[3];
>> +    template void x<int[]>();
>> +  }
>> +  int w = sizeof(A::a);
>> +  int x = sizeof(A::b); // expected-error {{incomplete}}
>> +  int y = sizeof(A::c);
>> +  int z = sizeof(A::d);
>> +  namespace A {
>> +    int g() { return sizeof(a); }
>> +    int h() { return sizeof(b); } // expected-error {{incomplete}}
>> +    int i() { return sizeof(c); }
>> +    int j() { return sizeof(d); }
>> +  }
>> }
>> 
>> Modified: cfe/trunk/test/CXX/drs/dr0xx.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CXX/drs/dr0xx.cpp?rev=191064&r1=191063&r2=191064&view=diff
>> ==============================================================================
>> --- cfe/trunk/test/CXX/drs/dr0xx.cpp (original)
>> +++ cfe/trunk/test/CXX/drs/dr0xx.cpp Thu Sep 19 20:15:31 2013
>> @@ -280,7 +280,7 @@ namespace dr27 { // dr27: yes
>> 
>> // dr28: na
>> 
>> -namespace dr29 { // dr29: no
>> +namespace dr29 { // dr29: 3.4
>>  void dr29_f0(); // expected-note {{here}}
>>  void g0() { void dr29_f0(); }
>>  extern "C++" void g0_cxx() { void dr29_f0(); }
>> @@ -291,17 +291,14 @@ namespace dr29 { // dr29: no
>>  extern "C" void g1_c() { void dr29_f1(); }
>>  extern "C++" void g1_cxx() { void dr29_f1(); } // expected-error {{different language linkage}}
>> 
>> -  // FIXME: We should reject this.
>> -  void g2() { void dr29_f2(); }
>> -  extern "C" void dr29_f2();
>> -
>> -  // FIXME: We should reject this.
>> -  extern "C" void g3() { void dr29_f3(); }
>> -  extern "C++" void dr29_f3();
>> -
>> -  // FIXME: We should reject this.
>> -  extern "C++" void g4() { void dr29_f4(); }
>> -  extern "C" void dr29_f4();
>> +  void g2() { void dr29_f2(); } // expected-note {{here}}
>> +  extern "C" void dr29_f2(); // expected-error {{different language linkage}}
>> +
>> +  extern "C" void g3() { void dr29_f3(); } // expected-note {{here}}
>> +  extern "C++" void dr29_f3(); // expected-error {{different language linkage}}
>> +
>> +  extern "C++" void g4() { void dr29_f4(); } // expected-note {{here}}
>> +  extern "C" void dr29_f4(); // expected-error {{different language linkage}}
>> 
>>  extern "C" void g5();
>>  extern "C++" void dr29_f5();
>> 
>> Modified: cfe/trunk/test/CodeGenCXX/mangle.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/mangle.cpp?rev=191064&r1=191063&r2=191064&view=diff
>> ==============================================================================
>> --- cfe/trunk/test/CodeGenCXX/mangle.cpp (original)
>> +++ cfe/trunk/test/CodeGenCXX/mangle.cpp Thu Sep 19 20:15:31 2013
>> @@ -9,7 +9,7 @@ struct Y { };
>> // CHECK: @_ZGVZN1N1gEvE1a = internal global
>> 
>> //CHECK: @pr5966_i = external global
>> -//CHECK: @_ZL8pr5966_i = internal global
>> +//CHECK: @_ZL8pr5966_j = internal global
>> 
>> // CHECK-LABEL: define zeroext i1 @_ZplRK1YRA100_P1X
>> bool operator+(const Y&, X* (&xs)[100]) { return false; }
>> @@ -314,10 +314,10 @@ void pr5966_foo() {
>>  pr5966_i = 0;
>> }
>> 
>> -static int pr5966_i;
>> +static int pr5966_j;
>> 
>> void pr5966_bar() {
>> -  pr5966_i = 0;
>> +  pr5966_j = 0;
>> }
>> 
>> namespace test0 {
>> @@ -652,10 +652,10 @@ namespace test24 {
>>    foo();
>>  }
>> 
>> -  static char foo() {}
>> +  static char bar() {}
>>  void test1() {
>> -    // CHECK: call signext i8 @_ZN6test24L3fooEv()
>> -    foo();
>> +    // CHECK: call signext i8 @_ZN6test24L3barEv()
>> +    bar();
>>  }
>> }
>> 
>> 
>> Modified: cfe/trunk/test/Index/usrs.m
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Index/usrs.m?rev=191064&r1=191063&r2=191064&view=diff
>> ==============================================================================
>> --- cfe/trunk/test/Index/usrs.m (original)
>> +++ cfe/trunk/test/Index/usrs.m Thu Sep 19 20:15:31 2013
>> @@ -118,7 +118,7 @@ int test_multi_declaration(void) {
>> // CHECK: usrs.m c:objc(cs)Foo Extent=[34:1 - 45:2]
>> // CHECK: usrs.m c:objc(cs)Foo(im)godzilla Extent=[35:1 - 39:2]
>> // CHECK: usrs.m c:usrs.m at 402objc(cs)Foo(im)godzilla at a Extent=[36:3 - 36:19]
>> -// CHECK: usrs.m c:objc(cs)Foo(im)godzilla at z Extent=[37:3 - 37:15]
>> +// CHECK: usrs.m c:@z Extent=[37:3 - 37:15]
>> // CHECK: usrs.m c:objc(cs)Foo(cm)kingkong Extent=[40:1 - 43:2]
>> // CHECK: usrs.m c:usrs.m at 470objc(cs)Foo(cm)kingkong at local_var Extent=[41:3 - 41:16]
>> // CHECK: usrs.m c:objc(cs)Foo(py)d1 Extent=[44:1 - 44:15]
>> 
>> Modified: cfe/trunk/test/Sema/struct-decl.c
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/struct-decl.c?rev=191064&r1=191063&r2=191064&view=diff
>> ==============================================================================
>> --- cfe/trunk/test/Sema/struct-decl.c (original)
>> +++ cfe/trunk/test/Sema/struct-decl.c Thu Sep 19 20:15:31 2013
>> @@ -57,3 +57,12 @@ const struct test2 { // expected-warning
>> inline struct test3 { // expected-error {{'inline' can only appear on functions}}
>>  int x;
>> };
>> +
>> +struct hiding_1 {};
>> +struct hiding_2 {};
>> +void test_hiding() {
>> +  struct hiding_1 *hiding_1();
>> +  extern struct hiding_2 *hiding_2;
>> +  struct hiding_1 *p = hiding_1();
>> +  struct hiding_2 *q = hiding_2;
>> +}
>> 
>> Modified: cfe/trunk/test/SemaCXX/blocks-1.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/blocks-1.cpp?rev=191064&r1=191063&r2=191064&view=diff
>> ==============================================================================
>> --- cfe/trunk/test/SemaCXX/blocks-1.cpp (original)
>> +++ cfe/trunk/test/SemaCXX/blocks-1.cpp Thu Sep 19 20:15:31 2013
>> @@ -1,5 +1,4 @@
>> -// RUN: %clang_cc1 -fsyntax-only -verify %s -fblocks -std=c++11
>> -// expected-no-diagnostics
>> +// RUN: %clang_cc1 -fsyntax-only -verify %s -fblocks -std=c++1y
>> 
>> extern "C" int exit(int);
>> 
>> @@ -57,3 +56,18 @@ namespace rdar11055105 {
>>    foo(a);
>>  };
>> }
>> +
>> +namespace LocalDecls {
>> +  void f() {
>> +    (void) ^{
>> +      extern int a; // expected-note {{previous}}
>> +      extern int b(); // expected-note {{previous}}
>> +    };
>> +  }
>> +  void g() {
>> +    (void) ^{
>> +      extern float a; // expected-error {{different type}}
>> +      extern float b(); // expected-error {{cannot be overloaded}}
>> +    };
>> +  }
>> +}
>> 
>> Modified: cfe/trunk/test/SemaCXX/cxx0x-initializer-references.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/cxx0x-initializer-references.cpp?rev=191064&r1=191063&r2=191064&view=diff
>> ==============================================================================
>> --- cfe/trunk/test/SemaCXX/cxx0x-initializer-references.cpp (original)
>> +++ cfe/trunk/test/SemaCXX/cxx0x-initializer-references.cpp Thu Sep 19 20:15:31 2013
>> @@ -36,10 +36,10 @@ namespace reference {
>>  };
>> 
>>  void call() {
>> -    void f(const int&);
>> +    one f(const int&);
>>    f({1});
>> 
>> -    void g(int&); // expected-note {{passing argument}}
>> +    one g(int&); // expected-note {{passing argument}}
>>    g({1}); // expected-error {{cannot bind to an initializer list temporary}}
>>    int i = 0;
>>    g({i});
>> 
>> Modified: cfe/trunk/test/SemaCXX/extern-c.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/extern-c.cpp?rev=191064&r1=191063&r2=191064&view=diff
>> ==============================================================================
>> --- cfe/trunk/test/SemaCXX/extern-c.cpp (original)
>> +++ cfe/trunk/test/SemaCXX/extern-c.cpp Thu Sep 19 20:15:31 2013
>> @@ -29,16 +29,27 @@ namespace test3 {
>>  }
>> }
>> 
>> -extern "C" {
>> -  void test4_f() {
>> -    extern int test4_b; // expected-note {{declared with C language linkage here}}
>> +namespace N {
>> +  extern "C" {
>> +    void test4_f() {
>> +      extern int test4_b; // expected-note {{declared with C language linkage here}}
>> +    }
>>  }
>> }
>> static float test4_b; // expected-error {{declaration of 'test4_b' in global scope conflicts with declaration with C language linkage}}
>> 
>> extern "C" {
>> -  void test5_f() {
>> -    extern int test5_b; // expected-note {{declared with C language linkage here}}
>> +  void test4c_f() {
>> +    extern int test4_c; // expected-note {{previous}}
>> +  }
>> +}
>> +static float test4_c; // expected-error {{redefinition of 'test4_c' with a different type: 'float' vs 'int'}}
>> +
>> +namespace N {
>> +  extern "C" {
>> +    void test5_f() {
>> +      extern int test5_b; // expected-note {{declared with C language linkage here}}
>> +    }
>>  }
>> }
>> extern "C" {
>> @@ -46,6 +57,15 @@ extern "C" {
>> }
>> 
>> extern "C" {
>> +  void test5c_f() {
>> +    extern int test5_c; // expected-note {{previous}}
>> +  }
>> +}
>> +extern "C" {
>> +  static float test5_c; // expected-error {{redefinition of 'test5_c' with a different type: 'float' vs 'int'}}
>> +}
>> +
>> +extern "C" {
>>  void f() {
>>    extern int test6_b;
>>  }
>> 
>> Modified: cfe/trunk/test/SemaCXX/function-redecl.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/function-redecl.cpp?rev=191064&r1=191063&r2=191064&view=diff
>> ==============================================================================
>> --- cfe/trunk/test/SemaCXX/function-redecl.cpp (original)
>> +++ cfe/trunk/test/SemaCXX/function-redecl.cpp Thu Sep 19 20:15:31 2013
>> @@ -4,17 +4,14 @@ int foo(int);
>> namespace N {
>>  void f1() {
>>    void foo(int); // okay
>> -    void bar(int);
>> +    void bar(int); // expected-note 2{{previous declaration is here}}
>>  }
>> 
>>  void foo(int); // expected-note 2{{previous declaration is here}}
>> 
>>  void f2() {
>>    int foo(int); // expected-error {{functions that differ only in their return type cannot be overloaded}}
>> -    // FIXME: We should be able to diagnose the conflict between this
>> -    // declaration of 'bar' and the previous one, even though they come
>> -    // from different lexical scopes.
>> -    int bar(int); // expected-note {{previous declaration is here}}
>> +    int bar(int); // expected-error {{functions that differ only in their return type cannot be overloaded}}
>>    int baz(int); // expected-note {{previous declaration is here}}
>> 
>>    {
>> 
>> Modified: cfe/trunk/test/SemaCXX/warn-unreachable.cpp
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/warn-unreachable.cpp?rev=191064&r1=191063&r2=191064&view=diff
>> ==============================================================================
>> --- cfe/trunk/test/SemaCXX/warn-unreachable.cpp (original)
>> +++ cfe/trunk/test/SemaCXX/warn-unreachable.cpp Thu Sep 19 20:15:31 2013
>> @@ -62,8 +62,8 @@ void test5() {
>>  struct S {
>>    int mem;
>>  } s;
>> -  S &foor() __attribute__((noreturn));
>> -  foor()
>> +  S &foonr() __attribute__((noreturn));
>> +  foonr()
>>    .mem;       // expected-warning {{will never be executed}}
>> }
>> 
>> 
>> Modified: cfe/trunk/www/cxx_dr_status.html
>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/www/cxx_dr_status.html?rev=191064&r1=191063&r2=191064&view=diff
>> ==============================================================================
>> --- cfe/trunk/www/cxx_dr_status.html (original)
>> +++ cfe/trunk/www/cxx_dr_status.html Thu Sep 19 20:15:31 2013
>> @@ -212,7 +212,7 @@
>>    <td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#29">29</a></td>
>>    <td>CD1</td>
>>    <td>Linkage of locally declared functions</td>
>> -    <td class="none" align="center">No</td>
>> +    <td class="svn" align="center">SVN</td>
>>  </tr>
>>  <tr>
>>    <td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#30">30</a></td>
>> 
>> 
>> _______________________________________________
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>> cfe-commits at cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
> 
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