On Fri, Mar 04, 2016 at 06:41:26PM +0100, Jakub Jelinek wrote:
> I'm ok with it for gcc6.
Cool.
> But IMHO you should add dg-bogus directives here.
Ok, version with dg-bogus:
Bootstrapped/regtested on x86_64-linux, ok for trunk?
2016-03-04 Marek Polacek <pola...@redhat.com>
PR c/69407
* c-common.c (resolve_overloaded_builtin): Set TREE_USED for the fetch
operations.
* gcc.dg/atomic-op-6.c: New test.
diff --git gcc/c-family/c-common.c gcc/c-family/c-common.c
index 965cf49..25afa9c 100644
--- gcc/c-family/c-common.c
+++ gcc/c-family/c-common.c
@@ -11443,6 +11443,10 @@ resolve_overloaded_builtin (location_t loc, tree
function,
&& orig_code != BUILT_IN_ATOMIC_STORE_N)
result = sync_resolve_return (first_param, result, orig_format);
+ if (fetch_op)
+ /* Prevent -Wunused-value warning. */
+ TREE_USED (result) = true;
+
/* If new_return is set, assign function to that expr and cast the
result to void since the generic interface returned void. */
if (new_return)
diff --git gcc/testsuite/gcc.dg/atomic-op-6.c gcc/testsuite/gcc.dg/atomic-op-6.c
index e69de29..f88c293 100644
--- gcc/testsuite/gcc.dg/atomic-op-6.c
+++ gcc/testsuite/gcc.dg/atomic-op-6.c
@@ -0,0 +1,11 @@
+/* Test we don't generate bogus warnings. */
+/* PR c/69407 */
+/* { dg-do compile } */
+/* { dg-options "-Wall -Wextra" } */
+
+void
+foo (int *p, int a)
+{
+ __atomic_fetch_add (&p, a, 0); /* { dg-bogus "value computed is not used" }
*/
+ __atomic_add_fetch (&p, a, 0); /* { dg-bogus "value computed is not used" }
*/
+}
Marek
