[backport from gcc-4.7/trunk <mikpe@it.uu.se>]

gcc/

2011-11-30  Andrew Pinski  <apinski@cavium.com>

	PR c/51321
	* c-parser.c (c_parser_postfix_expression): Check groktypename results
	before looking at the main variant.

gcc/testsuite/

2011-11-30  Andrew Pinski  <apinski@cavium.com>

	* gcc.dg/pr51321.c: New testcase.

--- gcc-4.6.2/gcc/c-parser.c.~1~	2011-01-19 22:59:47.000000000 +0100
+++ gcc-4.6.2/gcc/c-parser.c	2011-12-10 18:54:50.000000000 +0100
@@ -6366,9 +6366,16 @@ c_parser_postfix_expression (c_parser *p
 				     "expected %<)%>");
 	  {
 	    tree e1, e2;
+	    e1 = groktypename (t1, NULL, NULL);
+	    e2 = groktypename (t2, NULL, NULL);
+	    if (e1 == error_mark_node || e2 == error_mark_node)
+	      {
+		expr.value = error_mark_node;
+		break;
+	      }
 
-	    e1 = TYPE_MAIN_VARIANT (groktypename (t1, NULL, NULL));
-	    e2 = TYPE_MAIN_VARIANT (groktypename (t2, NULL, NULL));
+	    e1 = TYPE_MAIN_VARIANT (e1);
+	    e2 = TYPE_MAIN_VARIANT (e2);
 
 	    expr.value
 	      = comptypes (e1, e2) ? integer_one_node : integer_zero_node;
--- gcc-4.6.2/gcc/testsuite/gcc.dg/pr51321.c.~1~	1970-01-01 01:00:00.000000000 +0100
+++ gcc-4.6.2/gcc/testsuite/gcc.dg/pr51321.c	2011-12-10 18:55:26.000000000 +0100
@@ -0,0 +1,7 @@
+/* { dg-do compile } */
+int main ()
+{
+  return (__builtin_types_compatible_p (char[1][], char[1][1])); /* { dg-error "array type has incomplete element type" } */
+}
+
+