Re: [C++ Patch] PR 51786

[Paolo Carlini]

On 07/08/2013 08:01 PM, Jason Merrill wrote:

On 07/08/2013 01:49 PM, Paolo Carlini wrote:

Ah I see. I take your indication as meaning class *or enum*

Yes.

Thanks. Thus, as agreed, I tested the below. Ok?

Paolo.

///////////////////////////

Index: cp/parser.c
===================================================================
--- cp/parser.c (revision 200780)
+++ cp/parser.c (working copy)
@@ -11009,11 +11009,21 @@ 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
+             && (CLASS_TYPE_P (decl_specifiers.type)
+                 || TREE_CODE (decl_specifiers.type) == ENUMERAL_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);
     }
Index: testsuite/g++.dg/cpp0x/pr51786.C
===================================================================
--- testsuite/g++.dg/cpp0x/pr51786.C    (revision 0)
+++ testsuite/g++.dg/cpp0x/pr51786.C    (working copy)
@@ -0,0 +1,8 @@
+// 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" }