Collin Funk wrote:
> I was preparing a bug report for Clang, and think I found out how to fix
> the issue. See the following program:
>
> $ cat example.c
> #include <stdio.h>
> #include <stdlib.h>
> #ifdef ENABLE_NLS
> # include <libintl.h>
> #else
> __attribute__ ((__always_inline__, __gnu_inline__,
> __format_arg__ (1)))
> extern inline char const *
> gettext (const char *msgid)
> {
> return msgid;
> }
> #endif
> #define _(msgid) gettext (msgid)
> int
> main (void)
> {
> /* No warning. */
> printf (_("Hello, %s!\n"), "world");
> /* Warning. */
> printf (_("Hello, world!\n"));
> return EXIT_SUCCESS;
> }
> $ clang -Wformat-security example.c
>
> So, adding "__format_arg__ (1)" in this instance will silence it.
After extending your test case
======================== example.c ========================
#include <stdio.h>
#include <stdlib.h>
#ifdef ENABLE_NLS
# include <libintl.h>
#else
__attribute__ ((__always_inline__, __gnu_inline__
# ifdef __clang__
, __format_arg__ (1)
# endif
))
extern inline char const *
gettext (const char *msgid)
{
return msgid;
}
#endif
#define _(msgid) gettext (msgid)
int
main (void)
{
/* No warning. */
printf (_("Hello, %s!\n"), "world");
/* Warning without __format_arg__, no warning with __format_arg__. */
printf (_("Hello, world!\n"));
/* No warning. */
printf ("%s", _("tax rate: between 7% & 19%. %a %b %c %d %e %f %g %h %i %j %k
%l %m %n %o %p %q %r %s %t %u %v %w %x %y %z"));
return EXIT_SUCCESS;
}
===========================================================
I see that there is indeed no warning for the third _() invocation either:
$ gcc -Wall -Wformat=2 -Wformat-security example.c
$ clang -Wall -Wformat=2 -Wformat-security example.c
I'm surprised. But I agree that it's a nice solution.
> If that sounds okay, I'll figure out what version of GCC and Clang added
> them and submit a patch.
I can do that; thanks. Thanks a lot for finding a solution in a direction
that I never would have looked at!
Bruno
