On Tue, 2022-12-13 at 20:15 +0100, Alejandro Colomar via Gcc wrote:
>
>
> On 12/13/22 20:08, Alejandro Colomar wrote:
> > Hi!
> >
> > For the following program:
> >
> >
> > $ cat buf.c
> > #include <stdio.h>
> >
> > int main(void)
> > {
> > char *p, buf[5];
> >
> > p = buf + 6;
> > printf("%p\n", p);
> > }
> >
> >
> > There are no warnings in gcc, as I would expect:
>
> I just re-read my text, and it is ambiguous. I meant that I expect
> warnings.
Yeah, it would be good to warn about such code.
Looking in bugzilla, I see:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81172
which seems to talk about this issue, but that bug was closed as
resolved on 2020-04-13; I'm not sure what happened here.
Dave
>
>
> >
> > $ gcc -Wall -Wextra buf.c -O0
> >
> > Clang does warn, however:
> >
> > $ clang -Weverything -Wall -Wextra buf.c -O0
> > buf.c:8:17: warning: format specifies type 'void *' but the
> > argument has
> > type 'char *' [-Wformat-pedantic]
> > printf("%p\n", p);
> > ~~ ^
> > %s
> > buf.c:7:6: warning: the pointer incremented by 6 refers past
> > the end of the
> > array (that contains 5 elements) [-Warray-bounds-pointer-
> > arithmetic]
> > p = buf + 6;
> > ^ ~
> > buf.c:5:2: note: array 'buf' declared here
> > char *p, buf[5];
> > ^
> > 2 warnings generated.
> >
> > Cheers,
> >
> > Alex
> >
> >
>
> --
> <http://www.alejandro-colomar.es/>
