re PR c++/51786 ([c++0x] Invalid declaration with decltype accepted)

/cp
2013-07-09  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/51786
	* parser.c (cp_parser_simple_declaration): Before calling shadow_tag
	also check declares_class_or_enum.

/testsuite
2013-07-09  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/51786
	* g++.dg/cpp0x/pr51786.C: New.

From-SVN: r200813

gcc/cp/ChangeLog

+2013-07-09  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/51786
+	* parser.c (cp_parser_simple_declaration): Before calling shadow_tag
+	also check declares_class_or_enum.
+
 2013-07-08  Jason Merrill  <jason@redhat.com>
 
 	PR c++/57550

gcc/cp/parser.c

@@ -11009,11 +11009,20 @@ cp_parser_simple_declaration (cp_parser* parser,
 
   /* Issue an error message if no declarators are present, and the
      decl-specifier-seq does not itself declare a class or
-     enumeration.  */
+     enumeration: [dcl.dcl]/3.  */
   if (!saw_declarator)
     {
       if (cp_parser_declares_only_class_p (parser))
-	shadow_tag (&decl_specifiers);
+	{
+	  if (!declares_class_or_enum
+	      && decl_specifiers.type
+	      && OVERLOAD_TYPE_P (decl_specifiers.type))
+	    /* Ensure an error is issued anyway when finish_decltype_type,
+	       called via cp_parser_decl_specifier_seq, returns a class or
+	       an enumeration (c++/51786).  */
+	    decl_specifiers.type = NULL_TREE;
+	  shadow_tag (&decl_specifiers);
+	}
       /* Perform any deferred access checks.  */
       perform_deferred_access_checks (tf_warning_or_error);
     }

gcc/testsuite/ChangeLog

+2013-07-09  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/51786
+	* g++.dg/cpp0x/pr51786.C: New.
+
 2013-07-08  Janis Johnson  <janisjo@codesourcery.com>
 
 	* gcc.target/powerpc/tfmode_off.c: Skip for EABI targets.

gcc/testsuite/g++.dg/cpp0x/pr51786.C

+// PR c++/51786
+// { dg-do compile { target c++11 } }
+
+enum E {};
+struct A {};
+
+void foo() { decltype(E{}); }  // { dg-error "does not declare anything" }
+void bar() { decltype(A{}); }  // { dg-error "does not declare anything" }