re PR c/49120 (bogus "value computed is not used" warning (variable-length array…

re PR c/49120 (bogus "value computed is not used" warning (variable-length array in compound statement))

	PR c/49120
	* c-decl.c (start_decl): Convert expr to void_type_node.

	* gcc.dg/pr49120.c: New test.

From-SVN: r174081

gcc/ChangeLog

+2011-05-23  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c/49120
+	* c-decl.c (start_decl): Convert expr to void_type_node.
+
 2011-05-23  Richard Sandiford  <rdsandiford@googlemail.com>
 
 	PR rtl-optimization/48826

gcc/c-decl.c

@@ -3942,7 +3942,7 @@ start_decl (struct c_declarator *declarator, struct c_declspecs *declspecs,
     return 0;
 
   if (expr)
-    add_stmt (expr);
+    add_stmt (fold_convert (void_type_node, expr));
 
   if (TREE_CODE (decl) != FUNCTION_DECL && MAIN_NAME_P (DECL_NAME (decl)))
     warning (OPT_Wmain, "%q+D is usually a function", decl);

gcc/testsuite/ChangeLog

+2011-05-23  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c/49120
+	* gcc.dg/pr49120.c: New test.
+
 2011-05-23  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR target/47315

gcc/testsuite/gcc.dg/pr49120.c

+/* PR c/49120 */
+/* { dg-do compile } */
+/* { dg-options "-Wall" } */
+
+int
+main ()
+{
+  int a = 1;
+  int c = ({ char b[a + 1]; b[0] = 0; b[0]; });
+  return c;
+}