[Bug c/66425] (void) cast doesn't suppress __attribute__((warn_unused_result))

["lucas.de.marchi at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66425

--- Comment #15 from Lucas De Marchi <lucas.de.marchi at gmail dot com> ---
(In reply to Manuel LÃpez-IbÃÃez from comment #14)
> (In reply to Filipe Brandenburger from comment #12)
> > Can I have this issue reopened please?
> 
> If that makes you happy...
> 
> > Ok, how can we assign this bug to the appropriate team then?
> 
> It doesn't work like that. Individual contributors will work on things that
> they find interesting or get paid to fix.

Rusty, who opened this issue, seemed inclined to prepare such a patch.

> > I can't really think of a situation in the Linux kernel source code where
> > I'd find a __must_check function with a void cast, exactly for that reason,
> > right now it would generate a warning.
> 
> The users of _wur added _wur to a function expecting that any use of this
> function that does not assign the result will get a warning, even if there
> is a cast to void. Not warning for a cast to void breaks that expectation.

As I said, the people who add the attribute may not be the same people who use
the interface with that attribute.  I myself when writing libraries use the
_wur to give my users a warning if they are ignoring the return value.  However
they have all the rights to ignore it.  Be it simply by not using
-Wunused-result, hacking a macro to ignore the result or use the de facto
standard to cast to void.  IMO the latter is the best one since there might be
1 particular case in the entire codebase in which ignoring the return makes
sense.