re PR c++/45588 (unused-but-set-variable false trigger building gold)

	PR c++/45588
	* pt.c (tsubst) <case INTEGER_TYPE>: Call mark_rvalue_use
	before calling fold_decl_constant_value.

	* g++.dg/warn/Wunused-var-15.C: New test.

From-SVN: r164051

gcc/cp/ChangeLog

+2010-09-08  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/45588
+	* pt.c (tsubst) <case INTEGER_TYPE>: Call mark_rvalue_use
+	before calling fold_decl_constant_value.
+
 2010-09-07  Arnaud Charlet  <charlet@adacore.com>
 
 	* cp-tree.h (build_enumerator): Add new location_t parameter.

gcc/cp/pt.c

@@ -10116,6 +10116,7 @@ tsubst (tree t, tree args, tsubst_flags_t complain, tree in_decl)
 	    && !TREE_TYPE (max))
 	  TREE_TYPE (max) = TREE_TYPE (TREE_OPERAND (max, 0));
 
+	max = mark_rvalue_use (max);
 	max = fold_decl_constant_value (max);
 
 	/* If we're in a partial instantiation, preserve the magic NOP_EXPR

gcc/testsuite/ChangeLog

+2010-09-08  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/45588
+	* g++.dg/warn/Wunused-var-15.C: New test.
+
 2010-09-08  John David Anglin  <dave.anglin@nrc-cnrc.gc.ca>
 
 	* c-c++-common/Wunused-var-12.c: Add -fno-common to options on 32-bit

gcc/testsuite/g++.dg/warn/Wunused-var-15.C

+// PR c++/45588
+// { dg-do compile }
+// { dg-options "-Wunused" }
+
+void bar (unsigned char *);
+
+template <int N>
+struct S
+{
+  static const int k = 6;
+};
+
+template <int N>
+const int S<N>::k;
+
+template <int N>
+void
+foo ()
+{
+  const int i = S<N>::k;
+  unsigned char a[i];
+  bar (a);
+}
+
+void
+baz ()
+{
+  foo<0> ();
+}