re PR c/43981 (-Wunused-but-set-variable does not consider array sizing use of a variable)

	PR c/43981
	* c-parser.c (c_parser_direct_declarator_inner): Call mark_exp_read
	on dimen.

	* gcc.dg/Wunused-var-8.c: New test.

From-SVN: r159044

gcc/ChangeLog

+2010-05-04  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c/43981
+	* c-parser.c (c_parser_direct_declarator_inner): Call mark_exp_read
+	on dimen.
+
 2010-05-04  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR target/43799

gcc/c-parser.c

@@ -2474,6 +2474,8 @@ c_parser_direct_declarator_inner (c_parser *parser, bool id_present,
 				     "expected %<]%>");
 	  return NULL;
 	}
+      if (dimen)
+	mark_exp_read (dimen);
       declarator = build_array_declarator (brace_loc, dimen, quals_attrs,
 					   static_seen, star_seen);
       if (declarator == NULL)

gcc/testsuite/ChangeLog

+2010-05-04  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c/43981
+	* gcc.dg/Wunused-var-8.c: New test.
+
 2010-05-04  Jason Merrill  <jason@redhat.com>
 
 	PR c++/38064

gcc/testsuite/gcc.dg/Wunused-var-8.c

+/* PR c/43981 */
+/* { dg-do compile } */
+/* { dg-options "-Wunused" } */
+
+void g (char *);
+
+char
+f (int a)
+{
+  int len = a * 3;
+  char t[len];
+
+  g (t);
+  return t[0];
+}