re PR c++/42021 (Misleading error message when inherited typedefs cause ambiguity)

2013-06-12  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/42021
	* parser.c (cp_parser_nested_name_specifier_opt): Avoid emitting
	again diagnostic already emitted by cp_parser_lookup_name.

From-SVN: r200013

gcc/cp/ChangeLog

+2013-06-12  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/42021
+	* parser.c (cp_parser_nested_name_specifier_opt): Avoid emitting
+	again diagnostic already emitted by cp_parser_lookup_name.
+
 2013-06-11  Jan Hubicka  <jh@suse.cz>
 
 	PR c++/57551
-	* cp/pt.c (mark_decl_instantiated): Do not export explicit instantiations
-	of anonymous namespace templates.
+	* cp/pt.c (mark_decl_instantiated): Do not export explicit
+	instantiations of anonymous namespace templates.
 
 2013-06-10  Jason Merrill  <jason@redhat.com>
 

gcc/cp/parser.c

@@ -5230,10 +5230,16 @@ cp_parser_nested_name_specifier_opt (cp_parser *parser,
 				  decl);
 		      else if (ambiguous_decls)
 			{
+			  // cp_parser_lookup_name has the same diagnostic,
+			  // thus make sure to emit it almost once.
+			  if (cp_parser_uncommitted_to_tentative_parse_p
+			      (parser))
+			    {
 			      error_at (token->location,
 					"reference to %qD is ambiguous",
 					token->u.value);
 			      print_candidates (ambiguous_decls);
+			    }
 			  decl = error_mark_node;
 			}
 		      else