On Mon, Apr 27, 2015 at 04:47:12PM +0200, Marek Polacek wrote:
> On Sat, Apr 25, 2015 at 10:18:59PM +0200, Gerald Pfeifer wrote:
> > In case this example feels too contrived (even though it is an
> > excerpt of Wine code), we now also warn about the following where
> > the two types and variables are defined in different places and
> > the size of one is set implicitly:
> >
> > typedef int r_fun_t (int);
> >
> > r_fun_t * text_funcs[] = {0,0,0};
> >
> > int report (unsigned t)
> > {
> > typedef int s_fun_t (long, char);
> >
> > static s_fun_t * GUI_funcs[3];
> >
> > return (t < sizeof text_funcs / sizeof text_funcs[0] &&
> > t < sizeof GUI_funcs / sizeof GUI_funcs[0]);
> > }
> >
> > (I also filed this as https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65891
> > so that we keep track.)
>
> I'm afraid there isn't an easy solution to this; the problem is that we fold
> sizeof early, so the warning sees
>
> t < sizeof 4 && t < 4
>
> and warns. Maybe using SIZEOF_EXPR would help...
That said, this isn't something that regressed with my patch. Consider e.g.:
struct S { int i; };
struct T { int i; };
int
foo (unsigned int t)
{
return t < sizeof (struct S) && t > sizeof (struct T);
}
with -Wlogical-op:
w2.c: In function ‘foo’:
w2.c:6:32: warning: logical ‘and’ of mutually exclusive tests is always false
[-Wlogical-op]
return t < sizeof (struct S) && t > sizeof (struct T);
^
