Hi, On Fri, Jul 05, 2024 at 06:30:50PM GMT, Martin Uecker wrote: > Am Freitag, dem 05.07.2024 um 17:24 +0100 schrieb Jonathan Wakely: > > On Fri, 5 Jul 2024 at 17:02, Xi Ruoyao via Gcc <gcc@gcc.gnu.org> wrote: > > > > > > On Fri, 2024-07-05 at 17:53 +0200, Alejandro Colomar wrote: > > > > 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. > > > > > > It **shouldn't**. strtol will only violate restrict if it's wrongly > > > implemented, or something dumb is done like "strtol((const char*) &p, > > > &p, 0)". > > > > > > See my previous reply.
That's not right. See my reply to yours, Xi. The restrict in
char **endptr
already prevents calls such as strtol(x, x, 0).
The restrict in
const char *nptr
provides nothing.
> >
> > Right, is there a valid use of strtol where a warning would be justified?
Is there any valid reason to have restrict in the _first_ parameter of
strtol(3)? Other than "ISO C says so"? I'll take my beef with ISO C to
WG14, and hopefully get that fixed. Can we please discuss this
technically, ignoring the existence of ISO C, for the time being?
> > Showing that you can contrive a case where a const char* restrict and
> > char** restrict can alias doesn't mean there's a problem with strtol.
>
> I think his point is that a const char* restrict and something which
> is stored in a char* whose address is then passed can alias and there
> a warning would make sense in other situations.
Indeed.
> But I am also not convinced removing restrict would be an improvement.
> It would make more sense to have an annotation that indicates that
> endptr is only used as output.
What is the benefit of keeping restrict there? It doesn't provide any
benefits, AFAICS.
I've prepared a paper for wg14. I'll ask for a number, but will attach
it here already. I also attach the man(7) source code for it.
Cheers,
Alex
--
<https://www.alejandro-colomar.es/>
strtol.man
Description: Unix manual page
strtol.pdf
Description: Adobe PDF document
signature.asc
Description: PGP signature
