Am Freitag, dem 05.07.2024 um 17:53 +0200 schrieb Alejandro Colomar:
> Hi Martin,
>
> On Fri, Jul 05, 2024 at 05:34:55PM GMT, Martin Uecker wrote:
> > > I've written functions that more closely resemble strtol(3), to show
> > > that in the end they all share the same issue regarding const-ness:
>
> (Above I meant s/const/restrict/)
>
> > >
> > > $ cat d.c
> > > int d(const char *restrict ca, char *restrict a)
> > > {
> > > return ca > a;
> > > }
> > >
> > > int main(void)
> > > {
> > > char x = 3;
> > > char *xp = &x;
> > > d(xp, xp);
> > > }
> > > $ cc -Wall -Wextra d.c
> > > d.c: In function ‘main’:
> > > d.c:10:9: warning: passing argument 2 to ‘restrict’-qualified parameter
> > > aliases with argument 1 [-Wrestrict]
> > > 10 | d(xp, xp);
> > > | ^
> > >
> > > This trivial program causes a diagnostic. (Although I think the '>'
> > > should also cause a diagnostic!!)
> > >
> > > Let's add a reference, to resemble strtol(3):
> > >
> > > $ cat d2.c
> > > int d2(const char *restrict ca, char *restrict *restrict ap)
> > > {
> > > return ca > *ap;
> > > }
> > >
> > > int main(void)
> > > {
> > > char x = 3;
> > > char *xp = &x;
> > > d2(xp, &xp);
> > > }
> > > $ cc -Wall -Wextra d2.c
> > > $
> > >
> > > Why does this not cause a -Wrestrict diagnostic, while d.c does? How
> > > are these programs any different regarding pointer restrict-ness?
> >
> > It would require data flow anaylsis to produce the diagnostic while
> > the first can simply be diagnosed by comparing arguments.
>
> Agree. It seems like a task for -fanalyzer.
>
> $ cc -Wall -Wextra -fanalyzer -fuse-linker-plugin -flto d2.c
> $
>
> I'm unable to trigger that at all. It's probably not implemented, I
> guess. I've updated the bug report
> <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112833> to change the
> component to 'analyzer'.
>
> At least, I hope there's consensus that while current GCC doesn't warn
> about this, ideally it should, which means it should warn for valid uses
> of strtol(3), which means strtol(3) should be fixed, in all of ISO,
> POSIX, and glibc.
I am not sure.
>
> > > > > Well, I don't know how to report that defect to WG14. If you help me,
> > > > > I'll be pleased to do so. Do they have a public mailing list or
> > > > > anything like that?
> > > >
> > > > One can submit clarification or change requests:
> > > >
> > > > https://www.open-std.org/jtc1/sc22/wg14/www/contributing.html
>
> P.S.:
>
> I've sent a mail to UNE (the Spanish National Body for ISO), and
> asked them about joining WG14. Let's see what they say.
>
> P.S. 2:
>
> I'm also preparing a paper; would you mind championing it if I'm not yet
> able to do it when it's ready?
Guests can present too.
>
> P.S. 3:
>
> Do you know of any Spanish member of WG14? Maybe I can talk with them
> to have more information about how they work.
You could ask Miguel Ojeda.
Martin
>
