On Tue, May 10, 2022 at 08:58:46AM -0400, Jason Merrill wrote:
> On 5/7/22 18:26, Marek Polacek wrote:
> > Corrected version that avoids an uninitialized warning:
> >
> > This PR complains that we emit the "enumeration value not handled in
> > switch" warning even though the enumerator was marked with the
> > [[maybe_unused]] attribute.
> >
> > The first snag was that I couldn't just check TREE_USED, because
> > the enumerator could have been used earlier in the function, which
> > doesn't play well with the c_do_switch_warnings warning. Instead,
> > I had to check the attributes on the CONST_DECL directly, which led
> > to the second, and worse, snag: in C we don't have direct access to
> > the CONST_DECL for the enumerator.
>
> I wonder if you want to change that instead of working around it?
I wouldn't mind looking into that; I've hit this discrepancy numerous
times throughout the years and it'd be good to unify it so that the
c-common code doesn't need to hack around it.
Let's see how far I'll get...
> > + const bool unused_p = (lookup_attribute ("unused", attrs)
> > + || lookup_attribute ("maybe_unused", attrs));
>
> Why is this calculation...
>
> > node = splay_tree_lookup (cases, (splay_tree_key) value);
> > if (node)
> > {
> > @@ -1769,6 +1784,10 @@ c_do_switch_warnings (splay_tree cases, location_t
> > switch_location,
> > /* We've now determined that this enumerated literal isn't
> > handled by the case labels of the switch statement. */
> > + /* Don't warn if the enumerator was marked as unused. */
> > + if (unused_p)
> > + continue;
>
> ...separate from this test?
Ah, that must be a remnant from a previous version of the patch. No reason
for the separation anymore.
Thanks,
Marek
