PR11684, core issue 1417:

o Correct the handling of the restrictions on usage of cv-qualified and
  ref-qualified function types.
o Fix a bug where such types were rejected in template type parameter default
  arguments, due to such arguments not being treated as a template type arg
  context.
o Remove the ExtWarn for usage of such types as template arguments; that was
  a standard defect, not a GCC extension.
o Improve the wording and unify the code for diagnosing cv-qualifiers with the
  code for diagnosing ref-qualifiers.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@150244 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 123 insertions, 109 deletions

diff --git a/lib/Sema/SemaType.cpp b/lib/Sema/SemaType.cpp
index 51e1fb06e2..b402d3f2da 100644
--- a/lib/Sema/SemaType.cpp
+++ b/lib/Sema/SemaType.cpp
@@ -1789,8 +1789,8 @@ static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
   if (D.getAttributes())
     distributeTypeAttrsFromDeclarator(state, T);
 
-  // C++0x [dcl.spec.auto]p5: reject 'auto' if it is not in an allowed context.
-  // In C++0x, a function declarator using 'auto' must have a trailing return
+  // C++11 [dcl.spec.auto]p5: reject 'auto' if it is not in an allowed context.
+  // In C++11, a function declarator using 'auto' must have a trailing return
   // type (this is checked later) and we can skip this. In other languages
   // using auto, we need to check regardless.
   if (D.getDeclSpec().getTypeSpecType() == DeclSpec::TST_auto &&
@@ -1852,7 +1852,7 @@ static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
     if (D.isFunctionDeclarator())
       Error = 10;
 
-    // C++0x [dcl.spec.auto]p2: 'auto' is always fine if the declarator
+    // C++11 [dcl.spec.auto]p2: 'auto' is always fine if the declarator
     // contains a trailing return type. That is only legal at the outermost
     // level. Check all declarator chunks (outermost first) anyway, to give
     // better diagnostics.
@@ -1893,7 +1893,7 @@ static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
     case Declarator::ForContext:
     case Declarator::BlockLiteralContext:
     case Declarator::LambdaExprContext:
-      // C++0x [dcl.type]p3:
+      // C++11 [dcl.type]p3:
       //   A type-specifier-seq shall not define a class or enumeration unless
       //   it appears in the type-id of an alias-declaration (7.1.3) that is not
       //   the declaration of a template-declaration.
@@ -1937,6 +1937,66 @@ static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
   return T;
 }
 
+std::string getFunctionQualifiersAsString(const FunctionProtoType *FnTy) {
+  std::string Quals =
+    Qualifiers::fromCVRMask(FnTy->getTypeQuals()).getAsString();
+
+  switch (FnTy->getRefQualifier()) {
+  case RQ_None:
+    break;
+
+  case RQ_LValue:
+    if (!Quals.empty())
+      Quals += ' ';
+    Quals += '&';
+    break;
+
+  case RQ_RValue:
+    if (!Quals.empty())
+      Quals += ' ';
+    Quals += "&&";
+    break;
+  }
+
+  return Quals;
+}
+
+/// Check that the function type T, which has a cv-qualifier or a ref-qualifier,
+/// can be contained within the declarator chunk DeclType, and produce an
+/// appropriate diagnostic if not.
+static void checkQualifiedFunction(Sema &S, QualType T,
+                                   DeclaratorChunk &DeclType) {
+  // C++98 [dcl.fct]p4 / C++11 [dcl.fct]p6: a function type with a
+  // cv-qualifier or a ref-qualifier can only appear at the topmost level
+  // of a type.
+  int DiagKind = -1;
+  switch (DeclType.Kind) {
+  case DeclaratorChunk::Paren:
+  case DeclaratorChunk::MemberPointer:
+    // These cases are permitted.
+    return;
+  case DeclaratorChunk::Array:
+  case DeclaratorChunk::Function:
+    // These cases don't allow function types at all; no need to diagnose the
+    // qualifiers separately.
+    return;
+  case DeclaratorChunk::BlockPointer:
+    DiagKind = 0;
+    break;
+  case DeclaratorChunk::Pointer:
+    DiagKind = 1;
+    break;
+  case DeclaratorChunk::Reference:
+    DiagKind = 2;
+    break;
+  }
+
+  assert(DiagKind != -1);
+  S.Diag(DeclType.Loc, diag::err_compound_qualified_function_type)
+    << DiagKind << isa<FunctionType>(T.IgnoreParens()) << T
+    << getFunctionQualifiersAsString(T->castAs<FunctionProtoType>());
+}
+
 static TypeSourceInfo *GetFullTypeForDeclarator(TypeProcessingState &state,
                                                 QualType declSpecType,
                                                 TypeSourceInfo *TInfo) {
@@ -1968,6 +2028,11 @@ static TypeSourceInfo *GetFullTypeForDeclarator(TypeProcessingState &state,
     D.getContext() == Declarator::AliasDeclContext ||
     D.getContext() == Declarator::AliasTemplateContext;
 
+  // Does T refer to a function type with a cv-qualifier or a ref-qualifier?
+  bool IsQualifiedFunction = T->isFunctionProtoType() &&
+      (T->castAs<FunctionProtoType>()->getTypeQuals() != 0 ||
+       T->castAs<FunctionProtoType>()->getRefQualifier() != RQ_None);
+
   // Walk the DeclTypeInfo, building the recursive type as we go.
   // DeclTypeInfos are ordered from the identifier out, which is
   // opposite of what we want :).
@@ -1975,6 +2040,10 @@ static TypeSourceInfo *GetFullTypeForDeclarator(TypeProcessingState &state,
     unsigned chunkIndex = e - i - 1;
     state.setCurrentChunkIndex(chunkIndex);
     DeclaratorChunk &DeclType = D.getTypeObject(chunkIndex);
+    if (IsQualifiedFunction) {
+      checkQualifiedFunction(S, T, DeclType);
+      IsQualifiedFunction = DeclType.Kind == DeclaratorChunk::Paren;
+    }
     switch (DeclType.Kind) {
     case DeclaratorChunk::Paren:
       T = S.BuildParenType(T);
@@ -2056,6 +2125,7 @@ static TypeSourceInfo *GetFullTypeForDeclarator(TypeProcessingState &state,
       // does not have a K&R-style identifier list), then the arguments are part
       // of the type, otherwise the argument list is ().
       const DeclaratorChunk::FunctionTypeInfo &FTI = DeclType.Fun;
+      IsQualifiedFunction = FTI.TypeQuals || FTI.hasRefQualifier();
 
       // Check for auto functions and trailing return type and adjust the
       // return type accordingly.
@@ -2407,113 +2477,57 @@ static TypeSourceInfo *GetFullTypeForDeclarator(TypeProcessingState &state,
                                   FnTy->getNumArgs(), EPI);
     }
 
-    // C++0x [dcl.fct]p6:
-    //   A ref-qualifier shall only be part of the function type for a
-    //   non-static member function, the function type to which a pointer to
-    //   member refers, or the top-level function type of a function typedef 
-    //   declaration.
-    if ((FnTy->getTypeQuals() != 0 || FnTy->getRefQualifier()) &&
-        !(D.getContext() == Declarator::TemplateTypeArgContext &&
-          !D.isFunctionDeclarator()) && !IsTypedefName &&
-        (FreeFunction ||
-         D.getDeclSpec().getStorageClassSpec() == DeclSpec::SCS_static)) {
-      if (D.getContext() == Declarator::TemplateTypeArgContext) {
-        // Accept qualified function types as template type arguments as a GNU
-        // extension. This is also the subject of C++ core issue 547.
-        std::string Quals;
-        if (FnTy->getTypeQuals() != 0)
-          Quals = Qualifiers::fromCVRMask(FnTy->getTypeQuals()).getAsString();
-        
-        switch (FnTy->getRefQualifier()) {
-        case RQ_None:
-          break;
-            
-        case RQ_LValue:
-          if (!Quals.empty())
-            Quals += ' ';
-          Quals += '&';
-          break;
-          
-        case RQ_RValue:
-          if (!Quals.empty())
-            Quals += ' ';
-          Quals += "&&";
-          break;
-        }
-        
-        S.Diag(D.getIdentifierLoc(), 
-             diag::ext_qualified_function_type_template_arg)
-          << Quals;
-      } else {
-        if (FnTy->getTypeQuals() != 0) {
-          if (D.isFunctionDeclarator()) {
-            SourceRange Range = D.getIdentifierLoc();
-            for (unsigned I = 0, N = D.getNumTypeObjects(); I != N; ++I) {
-              const DeclaratorChunk &Chunk = D.getTypeObject(N-I-1);
-              if (Chunk.Kind == DeclaratorChunk::Function &&
-                  Chunk.Fun.TypeQuals != 0) {
-                switch (Chunk.Fun.TypeQuals) {
-                case Qualifiers::Const:
-                  Range = Chunk.Fun.getConstQualifierLoc();
-                  break;
-                case Qualifiers::Volatile:
-                  Range = Chunk.Fun.getVolatileQualifierLoc();
-                  break;
-                case Qualifiers::Const | Qualifiers::Volatile: {
-                    SourceLocation CLoc = Chunk.Fun.getConstQualifierLoc();
-                    SourceLocation VLoc = Chunk.Fun.getVolatileQualifierLoc();
-                    if (S.getSourceManager()
-                        .isBeforeInTranslationUnit(CLoc, VLoc)) {
-                      Range = SourceRange(CLoc, VLoc);
-                    } else {
-                      Range = SourceRange(VLoc, CLoc);
-                    }
-                  }
-                  break;
-                }
-                break;
-              }
-            }
-            S.Diag(Range.getBegin(), diag::err_invalid_qualified_function_type)
-                << FixItHint::CreateRemoval(Range);
-          } else
-            S.Diag(D.getIdentifierLoc(),
-                 diag::err_invalid_qualified_typedef_function_type_use)
-              << FreeFunction;
-        }
-          
-        if (FnTy->getRefQualifier()) {
-          if (D.isFunctionDeclarator()) {
-            SourceLocation Loc = D.getIdentifierLoc();
-            for (unsigned I = 0, N = D.getNumTypeObjects(); I != N; ++I) {
-              const DeclaratorChunk &Chunk = D.getTypeObject(N-I-1);
-              if (Chunk.Kind == DeclaratorChunk::Function &&
-                  Chunk.Fun.hasRefQualifier()) {
-                Loc = Chunk.Fun.getRefQualifierLoc();
-                break;
-              }
-            }
-
-            S.Diag(Loc, diag::err_invalid_ref_qualifier_function_type)
-              << (FnTy->getRefQualifier() == RQ_LValue)
-              << FixItHint::CreateRemoval(Loc);
-          } else {
-            S.Diag(D.getIdentifierLoc(), 
-                 diag::err_invalid_ref_qualifier_typedef_function_type_use)
-              << FreeFunction
-              << (FnTy->getRefQualifier() == RQ_LValue);
-          }
+    // C++11 [dcl.fct]p6 (w/DR1417):
+    // An attempt to specify a function type with a cv-qualifier-seq or a
+    // ref-qualifier (including by typedef-name) is ill-formed unless it is:
+    //  - the function type for a non-static member function,
+    //  - the function type to which a pointer to member refers,
+    //  - the top-level function type of a function typedef declaration or
+    //    alias-declaration,
+    //  - the type-id in the default argument of a type-parameter, or
+    //  - the type-id of a template-argument for a type-parameter
+    if (IsQualifiedFunction &&
+        !(!FreeFunction &&
+          D.getDeclSpec().getStorageClassSpec() != DeclSpec::SCS_static) &&
+        !IsTypedefName &&
+        D.getContext() != Declarator::TemplateTypeArgContext) {
+      SourceLocation Loc = D.getSourceRange().getBegin();
+      SourceRange RemovalRange;
+      unsigned I;
+      if (D.isFunctionDeclarator(I)) {
+        SmallVector<SourceLocation, 4> RemovalLocs;
+        const DeclaratorChunk &Chunk = D.getTypeObject(I);
+        assert(Chunk.Kind == DeclaratorChunk::Function);
+        if (Chunk.Fun.hasRefQualifier())
+          RemovalLocs.push_back(Chunk.Fun.getRefQualifierLoc());
+        if (Chunk.Fun.TypeQuals & Qualifiers::Const)
+          RemovalLocs.push_back(Chunk.Fun.getConstQualifierLoc());
+        if (Chunk.Fun.TypeQuals & Qualifiers::Volatile)
+          RemovalLocs.push_back(Chunk.Fun.getVolatileQualifierLoc());
+        // FIXME: We do not track the location of the __restrict qualifier.
+        //if (Chunk.Fun.TypeQuals & Qualifiers::Restrict)
+        //  RemovalLocs.push_back(Chunk.Fun.getRestrictQualifierLoc());
+        if (!RemovalLocs.empty()) {
+          std::sort(RemovalLocs.begin(), RemovalLocs.end(),
+                    SourceManager::LocBeforeThanCompare(S.getSourceManager()));
+          RemovalRange = SourceRange(RemovalLocs.front(), RemovalLocs.back());
+          Loc = RemovalLocs.front();
         }
-          
-        // Strip the cv-qualifiers and ref-qualifiers from the type.
-        FunctionProtoType::ExtProtoInfo EPI = FnTy->getExtProtoInfo();
-        EPI.TypeQuals = 0;
-        EPI.RefQualifier = RQ_None;
-          
-        T = Context.getFunctionType(FnTy->getResultType(), 
-                                    FnTy->arg_type_begin(),
-                                    FnTy->getNumArgs(), EPI);
       }
+
+      S.Diag(Loc, diag::err_invalid_qualified_function_type)
+        << FreeFunction << D.isFunctionDeclarator() << T
+        << getFunctionQualifiersAsString(FnTy)
+        << FixItHint::CreateRemoval(RemovalRange);
+
+      // Strip the cv-qualifiers and ref-qualifiers from the type.
+      FunctionProtoType::ExtProtoInfo EPI = FnTy->getExtProtoInfo();
+      EPI.TypeQuals = 0;
+      EPI.RefQualifier = RQ_None;
+
+      T = Context.getFunctionType(FnTy->getResultType(), 
+                                  FnTy->arg_type_begin(),
+                                  FnTy->getNumArgs(), EPI);
     }
   }