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Re: [PATCH resend 1/2] PR c/65403 - Ignore -Wno-error=<some-future-warning>


On Fri, Aug 23, 2019 at 3:13 AM Martin Liška <mliska@suse.cz> wrote:
> On 8/23/19 6:17 AM, Alex Henrie wrote:
> > +vec<const char *> ignored_wnoerror_options;
>
> Here you'll need to add a comment.

The declaration of ignored_options in opts-global.c doesn't have a
comment either. What would you like the comment to say?

> > +      const char * opt = ignored_wnoerror_options.pop ();
>
> No space between '*' and 'opt' please.

Okay.

> You don't want to append and option that is already in the ignored_wnoerror_options:
>
> $
> ./xgcc -B. -Wunused-variable -Werror -Wno-error=some-future-warning -Wno-error=some-future-warning /tmp/main2.c
> /tmp/main2.c: In function ‘main’:
> /tmp/main2.c:3:7: error: unused variable ‘foo’ [-Werror=unused-variable]
>     3 |   int foo; /* { dg-error "unused variable 'foo'" } */
>       |       ^~~
> /tmp/main2.c: At top level:
> cc1: error: ‘-Wno-error=some-future-warning’: no option ‘-Wsome-future-warning’ [-Werror]
> cc1: error: ‘-Wno-error=some-future-warning’: no option ‘-Wsome-future-warning’ [-Werror]
> cc1: all warnings being treated as errors
>
> As seen the error is there twice.

Joseph explicitly asked me to make -Wno-error=some-future-warning
behave the same as -Wno-some-future-warning (see
<https://gcc.gnu.org/ml/gcc-patches/2019-03/msg00065.html>), and
-Wno-some-future-warning prints multiple warnings if the option is
given multiple times.

> One question about the behavior:
>
> Why do I need to have another warning to get the warning: ‘-Wno-error=some-future-warning’ printed?

If we always give a warning about -Wno-error=some-future-warning then
combining that option with -Werror would cause compilation to fail,
which we don't want.

-Alex


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