[PATCH] avoid -Wnonnull for printf format in dead code (PR 87041)

[Christophe Lyon]

On Thu, 15 Nov 2018 at 10:39, Matthew Malcomson
<Matthew.Malcomson@arm.com> wrote:
>
> On 02/11/18 09:54, Christophe Lyon wrote:
> > Hi,
> >
> > I've noticed failure on targets using newlib (aarch64-elf and arm-eabi):
> > FAIL: gcc.c-torture/execute/printf-2.c
> > FAIL: gcc.c-torture/execute/user-printf.c
> >
> > my gcc.log contains:
> > gcc.c-torture/execute/user-printf.c   -O0  execution test (reason: TCL
> > LOOKUP CHANNEL exp5)
> > which is not very helpful
> >
>
> @Christophe
> Can I ask if your DejaGNU board setup has "needs_status_wrapper 1" for
> both of these boards?
>
Yes, I do use this.

> I believe this problem is caused by an interaction with the DejaGNU
> status wrapper.
>
> When the status wrapper is needed, DejaGNU looks at stdout for a line
> saying "*** EXIT code <number>" indicating what the status code was.
> When it doesn't find that line it assumes an exit code of 2.
> Without the status wrapper DejaGNU takes the return code from the
> program executed.
>
> Because these tests use "freopen ()" on stdout, the status wrapper fails
> to print to the IO channel DejaGNU is listening on, hence DejaGNU fails
> to find it's line, uses an exit code of 2, and fails the test.
>
>
> @Martin
> Would these tests still be valid having run freopen on stderr and using
> fprintf instead of printf?
> That makes the testcases pass for me.
>
> If not we could add an
>     { dg-require-effective-target unwrapped }
> directive in the testcases to stop the failure complaints.