Eric Blake <ebb9 <at> byu.net> writes:
>
> So, what should I do? Options:
> 1. Check in the patches below as-is
> 2. Ditch this series, and instead go and change all uses of GNULIB_POSIXCHECK
> that used
> #define func(args) (GL_LINK_WARNING("..."),func(args))
> to instead use
> #define func (GL_LINK_WARNING("..."),func)
> 3. Like 2, but also check in the new va-args module (others might have a use
> for it, even though it would be unused in gnulib at this point)
Another thing to consider. Why are we even bothering with a link warning,
which only works for ELF, when gcc provides a more generic solution that will
also work for Cygwin and other non-ELF platforms?
For example, on cygwin:
$ cat foo.c
#include <stdlib.h>
int
main (int argc, char **argv)
{
char x[] = "aaaXXXXXX";
char * (*func) (char *) = mktemp;
func (x);
mktemp (x);
return 0;
}
$ gcc -E foo.c | grep mktemp
char * __attribute__((__cdecl__)) mktemp (char *) __attribute__ ((warning ("the
use of `mktemp' is dangerous; use `mkstemp' instead")));
char * __attribute__((__cdecl__)) _mktemp_r (struct _reent *, char *)
__attribute__ ((warning ("the use of `mktemp' is dangerous; use `mkstemp'
instead")));
char * (*func) (char *) = mktemp;
mktemp (x);
$ gcc -Wall -o foo foo.c
foo.c: In function ‘main’:
foo.c:8: warning: call to ‘mktemp’ declared with attribute warning: the use of
`mktemp' is dangerous; use `mkstemp' instead
OK, so gcc didn't warn about the suspicious use of the address of mktemp in
line 6, such that the call to mktemp in line 7 didn't warn. I guess we should
report that as a bug to the gcc folks. But as indirection is less common, the
use of __attribute__((__warning__(""))) would allow even more platforms to
detect GNULIB_POSIXCHECK holes, without resorting to ELF-only magic that
doesn't kick in until the link phase.
In other words, maybe I should go with option:
4. Redefine GL_LINK_WARNING to instead be a way to apply __attribute__
((__warning__)) as a function attribute when gcc supports it (and probably
rename the module/macro from link-warning/GL_LINK_WARNING to usage-
warning/GL_USAGE_WARNING, since it would now be a compiler rather than a linker
warning), and adjust all GNULIB_POSIXCHECK call points to use the new semantics.
--
Eric Blake
