[CONCEPTS] Add diagnostic; invalid tag when concept specified

[nwilson]

Summary

Adding check to emit diagnostic for invalid tag when concept is specified and associated tests.

[nwilson]

Addressing comments which were discussed on the mailing list - Apply the same text when diagnosing a free standing declaration as suggested by Aaron. Replace diagnostic identifier err_concept_decl_non_template with err_concept_wrong_decl_kind as suggested by Hubert and Richard. Fix tests corresponding to the changes.

[aaron.ballman]

LGTM!

~Aaron

cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td

def note_non_literal_nontrivial_dtor : Note<
   "%0 is not literal because it has a non-trivial destructor">;
 def warn_private_extern : Warning<
   "use of __private_extern__ on a declaration may not produce external symbol "
   "private to the linkage unit and is deprecated">, InGroup<PrivateExtern>;
 def note_private_extern : Note<
   "use __attribute__((visibility(\"hidden\"))) attribute instead">;
 
 // C++ Concepts TS
-def err_concept_decl_non_template : Error<
+def err_concept_wrong_decl_kind : Error<
   "'concept' can only appear on the definition of a function template or variable template">;
 def err_concept_decls_may_only_appear_in_namespace_scope : Error<
   "concept declarations may only appear in namespace scope">;
 def err_function_concept_not_defined : Error<
   "function concept declaration must be a definition">;
 def err_var_concept_not_initialized : Error<
   "variable concept declaration must be initialized">;
 

cfe/trunk/lib/Sema/SemaDecl.cpp

if (Tag)
       Diag(DS.getConstexprSpecLoc(), diag::err_constexpr_tag)
           << GetDiagnosticTypeSpecifierID(DS.getTypeSpecType());
     else
       Diag(DS.getConstexprSpecLoc(), diag::err_constexpr_no_declarators);
     // Don't emit warnings after this error.
     return TagD;
   }
 
+  if (DS.isConceptSpecified()) {
+    // C++ Concepts TS [dcl.spec.concept]p1: A concept definition refers to
+    // either a function concept and its definition or a variable concept and
+    // its initializer.
+    Diag(DS.getConceptSpecLoc(), diag::err_concept_wrong_decl_kind);
+    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);
if (getLangOpts().CPlusPlus)
     CheckExtraCXXDefaultArguments(D);
 
   if (D.getDeclSpec().isConceptSpecified()) {
     // C++ Concepts TS [dcl.spec.concept]p1: The concept specifier shall be
     // applied only to the definition of a function template or variable
     // template, declared in namespace scope
     if (!TemplateParamLists.size()) {
       Diag(D.getDeclSpec().getConceptSpecLoc(),
-           diag::err_concept_decl_non_template);
+           diag:: err_concept_wrong_decl_kind);
       return nullptr;
     }
 
     if (!DC->getRedeclContext()->isFileContext()) {
       Diag(D.getIdentifierLoc(),
            diag::err_concept_decls_may_only_appear_in_namespace_scope);
       return nullptr;
     }

cfe/trunk/test/SemaCXX/cxx-concept-declaration.cpp

 
 concept bool D4() { return true; } // expected-error {{'concept' can only appear on the definition of a function template or variable template}}
 
 concept bool D5 = true; // expected-error {{'concept' can only appear on the definition of a function template or variable template}}
 
 template<typename T>
 concept bool D6; // expected-error {{variable concept declaration must be initialized}}
 
+// Tag
+concept class CC1 {}; // expected-error {{'concept' can only appear on the definition of a function template or variable template}}
+concept struct CS1 {}; // expected-error {{'concept' can only appear on the definition of a function template or variable template}}
+concept union CU1 {}; // expected-error {{'concept' can only appear on the definition of a function template or variable template}}
+concept enum CE1 {}; // expected-error {{'concept' can only appear on the definition of a function template or variable template}}
+template <typename T> concept class TCC1 {}; // expected-error {{'concept' can only appear on the definition of a function template or variable template}}
+template <typename T> concept struct TCS1 {}; // expected-error {{'concept' can only appear on the definition of a function template or variable template}}
+template <typename T> concept union TCU1 {}; // expected-error {{'concept' can only appear on the definition of a function template or variable template}}
+
+concept bool; // expected-error {{'concept' can only appear on the definition of a function template or variable template}}