re PR c++/58550 (][c++11] ICE with auto in function return type and lto)

	PR c++/58550
	* decl.c (grokdeclarator): Turn pedwarn about auto return type in
	c++11 into error.

From-SVN: r207055

gcc/cp/ChangeLog

 2014-01-24  Jason Merrill  <jason@redhat.com>
 
+	PR c++/58550
+	* decl.c (grokdeclarator): Turn pedwarn about auto return type in
+	c++11 into error.
+
 	PR c++/59886
 	PR c++/59659
 	* typeck2.c (process_init_constructor_array): Don't create

gcc/cp/decl.c

@@ -9599,9 +9599,14 @@ grokdeclarator (const cp_declarator *declarator,
 			    && LAMBDA_TYPE_P (current_class_type))
 			  /* OK for C++11 lambdas.  */;
 			else if (cxx_dialect < cxx1y)
-			  pedwarn (input_location, 0, "%qs function uses "
+			  {
+			    error ("%qs function uses "
 				   "%<auto%> type specifier without trailing "
 				   "return type", name);
+			    inform (input_location, "deduced return type "
+				    "only available with -std=c++1y or "
+				    "-std=gnu++1y");
+			  }
 			else if (virtualp)
 			  permerror (input_location, "virtual function cannot "
 				     "have deduced return type");

gcc/testsuite/g++.dg/cpp0x/auto41.C

+// PR c++/58550
+// { dg-options "-std=c++11" }
+
+auto foo();			// { dg-error "auto" }
+auto fp = foo;