re PR c++/44108 (-Wunused-but-set-variable does not consider array sizing use of a const variable)

	PR c++/44108
	* decl.c (compute_array_index_type): Call mark_rvalue_use.

	* c-c++-common/Wunused-var-8.c: New test.

Co-Authored-By: Jason Merrill <jason@redhat.com>

From-SVN: r159497

gcc/cp/ChangeLog

+2010-05-17  Dodji Seketeli  <dodji@redhat.com>
+	    Jason Merrill  <jason@redhat.com>
+
+	PR c++/44108
+	* decl.c (compute_array_index_type): Call mark_rvalue_use.
+
 2010-05-15  Jason Merrill  <jason@redhat.com>
 
 	* cp-tree.h (TYPE_NOEXCEPT_P): New macro.

gcc/cp/decl.c

@@ -7369,6 +7369,8 @@ compute_array_index_type (tree name, tree size)
   /* The size might be the result of a cast.  */
   STRIP_TYPE_NOPS (size);
 
+  size = mark_rvalue_use (size);
+
   /* It might be a const variable or enumeration constant.  */
   size = integral_constant_value (size);
   if (error_operand_p (size))

gcc/testsuite/ChangeLog

+2010-05-17  Dodji Seketeli  <dodji@redhat.com>
+	    Jason Merrill  <jason@redhat.com>
+
+	PR c++/44108
+	* c-c++-common/Wunused-var-8.c: New test.
+
 2010-05-17  Jakub Jelinek  <jakub@redhat.com>
 
 	PR bootstrap/42347

gcc/testsuite/c-c++-common/Wunused-var-8.c

+/* Origin: PR c++/44108 */
+/* { dg-options "-Wunused" } */
+/* { dg-do compile } */
+
+int
+foo ()
+{
+  unsigned int M = 2;
+  const unsigned int M_CONST = 2;
+  static unsigned int M_STATIC = 2;
+  static const unsigned int M_STATIC_CONST = 2;
+
+  char n1[M];
+  char n2[M_CONST];
+  char n3[M_STATIC];
+  char n4[M_STATIC_CONST];
+
+  return sizeof (n1) + sizeof (n2) + sizeof (n3) + sizeof (n4);
+}