This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
Re: [C PATCH] Prevent -Wunused-value warning with __atomic_fetch_* (PR c/69407)
- From: Jakub Jelinek <jakub at redhat dot com>
- To: Marek Polacek <polacek at redhat dot com>
- Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>, Joseph Myers <joseph at codesourcery dot com>
- Date: Fri, 4 Mar 2016 18:41:26 +0100
- Subject: Re: [C PATCH] Prevent -Wunused-value warning with __atomic_fetch_* (PR c/69407)
- Authentication-results: sourceware.org; auth=none
- References: <20160304173040 dot GM10006 at redhat dot com>
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
On Fri, Mar 04, 2016 at 06:30:40PM +0100, Marek Polacek wrote:
> This is not a regression but I thought I'd post this anyway. Martin reported
> that we generate -Wunused-value warnings on the attached testcase, which
> arguable doesn't make sense. Setting TREE_USED suppresses the warning. Since
> we already compute 'fetch_op' I used that. (This warning doesn't trigger e.g.
> for __atomic_load/store/compare.)
>
> Bootstrapped/regtested on x86_64-linux, ok for trunk or gcc7?
I'm ok with it for gcc6.
> diff --git gcc/testsuite/gcc.dg/atomic-op-6.c gcc/testsuite/gcc.dg/atomic-op-6.c
> index e69de29..c8d93a4 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);
> + __atomic_add_fetch (&p, a, 0);
> +}
But IMHO you should add dg-bogus directives here.
Jakub