When we parse a tag specifier, keep track of whether that tag

specifier resulted in the creation of a new TagDecl node, which
happens either when the tag specifier was a definition or when the tag
specifier was the first declaration of that tag type. This information
has several uses, the first of which is implemented in this commit:

  1) In C++, one is not allowed to define tag types within a type
  specifier (e.g., static_cast<struct S { int x; } *>(0) is
  ill-formed) or within the result or parameter types of a
  function. We now diagnose this.

  2) We can extend DeclGroups to contain information about any tags
  that are declared/defined within the declaration specifiers of a
  variable, e.g.,

    struct Point { int x, y, z; } p;

  This will help improve AST printing and template instantiation,
  among other things.

  3) For C99, we can keep track of whether a tag type is defined
  within the type of a parameter, to properly cope with cases like,
  e.g.,

    int bar(struct T2 { int x; } y) {
      struct T2 z;
    }

  We can also do similar things wherever there is a type specifier,
  e.g., to keep track of where the definition of S occurs in this
  legal C99 code:

    (struct S { int x, y; } *)0

  



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@72555 91177308-0d34-0410-b5e6-96231b3b80d8

8 files changed, 61 insertions, 15 deletions

diff --git a/lib/Frontend/PrintParserCallbacks.cpp b/lib/Frontend/PrintParserCallbacks.cpp
index e9aece968f..73530ef58d 100644
--- a/lib/Frontend/PrintParserCallbacks.cpp
+++ b/lib/Frontend/PrintParserCallbacks.cpp
@@ -195,7 +195,8 @@ namespace {
     virtual DeclPtrTy ActOnTag(Scope *S, unsigned TagType, TagKind TK,
                                SourceLocation KWLoc, const CXXScopeSpec &SS,
                                IdentifierInfo *Name, SourceLocation NameLoc,
-                               AttributeList *Attr, AccessSpecifier AS) {
+                               AttributeList *Attr, AccessSpecifier AS,
+                               bool &Owned) {
       // TagType is an instance of DeclSpec::TST, indicating what kind of tag this
       // is (struct/union/enum/class).
       Out << __FUNCTION__ << "\n";
diff --git a/lib/Parse/DeclSpec.cpp b/lib/Parse/DeclSpec.cpp
index e592deecd0..2a765d2124 100644
--- a/lib/Parse/DeclSpec.cpp
+++ b/lib/Parse/DeclSpec.cpp
@@ -241,12 +241,14 @@ bool DeclSpec::SetTypeSpecSign(TSS S, SourceLocation Loc,
 }
 
 bool DeclSpec::SetTypeSpecType(TST T, SourceLocation Loc,
-                               const char *&PrevSpec, void *Rep) {
+                               const char *&PrevSpec, void *Rep,
+                               bool Owned) {
   if (TypeSpecType != TST_unspecified)
     return BadSpecifier((TST)TypeSpecType, PrevSpec);
   TypeSpecType = T;
   TypeRep = Rep;
   TSTLoc = Loc;
+  TypeSpecOwned = Owned;
   return false;
 }
 
diff --git a/lib/Parse/ParseDecl.cpp b/lib/Parse/ParseDecl.cpp
index 59e9555a88..54e70be16e 100644
--- a/lib/Parse/ParseDecl.cpp
+++ b/lib/Parse/ParseDecl.cpp
@@ -1460,8 +1460,10 @@ void Parser::ParseEnumSpecifier(SourceLocation StartLoc, DeclSpec &DS,
     TK = Action::TK_Declaration;
   else
     TK = Action::TK_Reference;
+  bool Owned = false;
   DeclPtrTy TagDecl = Actions.ActOnTag(CurScope, DeclSpec::TST_enum, TK,
-                                       StartLoc, SS, Name, NameLoc, Attr, AS);
+                                       StartLoc, SS, Name, NameLoc, Attr, AS,
+                                       Owned);
   
   if (Tok.is(tok::l_brace))
     ParseEnumBody(StartLoc, TagDecl);
@@ -1469,7 +1471,7 @@ void Parser::ParseEnumSpecifier(SourceLocation StartLoc, DeclSpec &DS,
   // TODO: semantic analysis on the declspec for enums.
   const char *PrevSpec = 0;
   if (DS.SetTypeSpecType(DeclSpec::TST_enum, StartLoc, PrevSpec,
-                         TagDecl.getAs<void>()))
+                         TagDecl.getAs<void>(), Owned))
     Diag(StartLoc, diag::err_invalid_decl_spec_combination) << PrevSpec;
 }
 
diff --git a/lib/Parse/ParseDeclCXX.cpp b/lib/Parse/ParseDeclCXX.cpp
index a7d3b52bd2..cfbd9097f7 100644
--- a/lib/Parse/ParseDeclCXX.cpp
+++ b/lib/Parse/ParseDeclCXX.cpp
@@ -479,6 +479,7 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
   // FIXME: When TK == TK_Reference and we have a template-id, we need
   // to turn that template-id into a type.
 
+  bool Owned = false;
   if (TemplateId && TK != Action::TK_Reference) {
     // Explicit specialization, class template partial specialization,
     // or explicit instantiation.
@@ -582,7 +583,7 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
 
     // Declaration or definition of a class type
     TagOrTempResult = Actions.ActOnTag(CurScope, TagType, TK, StartLoc, SS, 
-                                       Name, NameLoc, Attr, AS);
+                                       Name, NameLoc, Attr, AS, Owned);
   }
 
   // Parse the optional base clause (C++ only).
@@ -608,7 +609,7 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
   }
   
   if (DS.SetTypeSpecType(TagType, StartLoc, PrevSpec, 
-                         TagOrTempResult.get().getAs<void>()))
+                         TagOrTempResult.get().getAs<void>(), Owned))
     Diag(StartLoc, diag::err_invalid_decl_spec_combination) << PrevSpec;
   
   if (DS.isFriendSpecified())
diff --git a/lib/Sema/Sema.h b/lib/Sema/Sema.h
index 0a285bd309..fae5a92747 100644
--- a/lib/Sema/Sema.h
+++ b/lib/Sema/Sema.h
@@ -346,7 +346,8 @@ public:
                              QualType *ParamTypes, unsigned NumParamTypes,
                              bool Variadic, unsigned Quals,
                              SourceLocation Loc, DeclarationName Entity);
-  QualType GetTypeForDeclarator(Declarator &D, Scope *S, unsigned Skip = 0);
+  QualType GetTypeForDeclarator(Declarator &D, Scope *S, unsigned Skip = 0,
+                                TagDecl **OwnedDecl = 0);
   DeclarationName GetNameForDeclarator(Declarator &D);
 
   QualType ObjCGetTypeForMethodDefinition(DeclPtrTy D);
@@ -444,7 +445,8 @@ public:
   virtual DeclPtrTy ActOnTag(Scope *S, unsigned TagSpec, TagKind TK,
                              SourceLocation KWLoc, const CXXScopeSpec &SS,
                              IdentifierInfo *Name, SourceLocation NameLoc,
-                             AttributeList *Attr, AccessSpecifier AS);
+                             AttributeList *Attr, AccessSpecifier AS,
+                             bool &OwnedDecl);
   
   virtual void ActOnDefs(Scope *S, DeclPtrTy TagD, SourceLocation DeclStart,
                          IdentifierInfo *ClassName,
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 7b36b13416..6a2e3099cd 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -2835,8 +2835,16 @@ Sema::ActOnParamDeclarator(Scope *S, Declarator &D) {
   if (getLangOptions().CPlusPlus)
     CheckExtraCXXDefaultArguments(D);
  
-  QualType parmDeclType = GetTypeForDeclarator(D, S);
+  TagDecl *OwnedDecl = 0;
+  QualType parmDeclType = GetTypeForDeclarator(D, S, /*Skip=*/0, &OwnedDecl);
   
+  if (getLangOptions().CPlusPlus && OwnedDecl && OwnedDecl->isDefinition()) {
+    // C++ [dcl.fct]p6:
+    //   Types shall not be defined in return or parameter types.
+    Diag(OwnedDecl->getLocation(), diag::err_type_defined_in_param_type)
+      << Context.getTypeDeclType(OwnedDecl);
+  }
+
   // TODO: CHECK FOR CONFLICTS, multiple decls with same name in one scope.
   // Can this happen for params?  We already checked that they don't conflict
   // among each other.  Here they can only shadow globals, which is ok.
@@ -3316,11 +3324,13 @@ bool Sema::isAcceptableTagRedeclaration(const TagDecl *Previous,
 Sema::DeclPtrTy Sema::ActOnTag(Scope *S, unsigned TagSpec, TagKind TK,
                                SourceLocation KWLoc, const CXXScopeSpec &SS,
                                IdentifierInfo *Name, SourceLocation NameLoc,
-                               AttributeList *Attr, AccessSpecifier AS) {
+                               AttributeList *Attr, AccessSpecifier AS,
+                               bool &OwnedDecl) {
   // If this is not a definition, it must have a name.
   assert((Name != 0 || TK == TK_Definition) &&
          "Nameless record must be a definition!");
 
+  OwnedDecl = false;
   TagDecl::TagKind Kind;
   switch (TagSpec) {
   default: assert(0 && "Unknown tag type!");
@@ -3645,6 +3655,7 @@ CreateNewDecl:
     CurContext->addDecl(Context, New);
   }
 
+  OwnedDecl = true;
   return DeclPtrTy::make(New);
 }
 
diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index b15ce295ea..179e27d8b7 100644
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -2357,8 +2357,9 @@ Sema::ActOnExplicitInstantiation(Scope *S, SourceLocation TemplateLoc,
                                  SourceLocation NameLoc,
                                  AttributeList *Attr) {
 
+  bool Owned = false;
   DeclPtrTy TagD = ActOnTag(S, TagSpec, Action::TK_Reference,
-                            KWLoc, SS, Name, NameLoc, Attr, AS_none);
+                            KWLoc, SS, Name, NameLoc, Attr, AS_none, Owned);
   if (!TagD)
     return true;
 
diff --git a/lib/Sema/SemaType.cpp b/lib/Sema/SemaType.cpp
index 298a6cddda..83f9b60fd7 100644
--- a/lib/Sema/SemaType.cpp
+++ b/lib/Sema/SemaType.cpp
@@ -604,7 +604,12 @@ QualType Sema::BuildFunctionType(QualType T,
 /// GetTypeForDeclarator - Convert the type for the specified
 /// declarator to Type instances. Skip the outermost Skip type
 /// objects.
-QualType Sema::GetTypeForDeclarator(Declarator &D, Scope *S, unsigned Skip) {
+///
+/// If OwnedDecl is non-NULL, and this declarator's decl-specifier-seq
+/// owns the declaration of a type (e.g., the definition of a struct
+/// type), then *OwnedDecl will receive the owned declaration.
+QualType Sema::GetTypeForDeclarator(Declarator &D, Scope *S, unsigned Skip,
+                                    TagDecl **OwnedDecl) {
   bool OmittedReturnType = false;
 
   if (D.getContext() == Declarator::BlockLiteralContext
@@ -637,6 +642,8 @@ QualType Sema::GetTypeForDeclarator(Declarator &D, Scope *S, unsigned Skip) {
       T = ConvertDeclSpecToType(DS, D.getIdentifierLoc(), isInvalid);
       if (isInvalid)
         D.setInvalidType(true);
+      else if (OwnedDecl && DS.isTypeSpecOwned())
+        *OwnedDecl = cast<TagDecl>((Decl *)DS.getTypeRep());
     }
     break;
   }
@@ -717,6 +724,15 @@ QualType Sema::GetTypeForDeclarator(Declarator &D, Scope *S, unsigned Skip) {
         D.setInvalidType(true);
       }
 
+      if (getLangOptions().CPlusPlus && D.getDeclSpec().isTypeSpecOwned()) {
+        // C++ [dcl.fct]p6:
+        //   Types shall not be defined in return or parameter types.
+        TagDecl *Tag = cast<TagDecl>((Decl *)D.getDeclSpec().getTypeRep());
+        if (Tag->isDefinition())
+          Diag(Tag->getLocation(), diag::err_type_defined_in_result_type)
+            << Context.getTypeDeclType(Tag);
+      }
+
       if (FTI.NumArgs == 0) {
         if (getLangOptions().CPlusPlus) {
           // C++ 8.3.5p2: If the parameter-declaration-clause is empty, the
@@ -971,14 +987,24 @@ Sema::TypeResult Sema::ActOnTypeName(Scope *S, Declarator &D) {
   // the parser.
   assert(D.getIdentifier() == 0 && "Type name should have no identifier!");
   
-  QualType T = GetTypeForDeclarator(D, S);
+  TagDecl *OwnedTag = 0;
+  QualType T = GetTypeForDeclarator(D, S, /*Skip=*/0, &OwnedTag);
   if (D.isInvalidType())
     return true;
 
-  // Check that there are no default arguments (C++ only).
-  if (getLangOptions().CPlusPlus)
+  if (getLangOptions().CPlusPlus) {
+    // Check that there are no default arguments (C++ only).
     CheckExtraCXXDefaultArguments(D);
 
+    // C++0x [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).
+    if (OwnedTag && OwnedTag->isDefinition())
+      Diag(OwnedTag->getLocation(), diag::err_type_defined_in_type_specifier)
+        << Context.getTypeDeclType(OwnedTag);
+  }
+
   return T.getAsOpaquePtr();
 }