Re: [patch 01/10] compiler: define __attribute_unused__

Rusty Russell
2007-05-02T07:52:11Z

On Wed, 2007-05-02 at 00:22 -0700, David Rientjes wrote:
> On Wed, 2 May 2007, Rusty Russell wrote:
>
> > That sounds exactly right to me! If the author says it's optional, it
> > might be discarded. If they say it's needed, it won't be. At least,
> > when I'm coding and gcc warns me something is unused, this is the
> > decision I have to make ("is this really needed or not?").
> >
>
> Hi Rusty,
>
> There are many instances in the tree of functions that have no callers
> whatsoever because they've been commented out temporarily, disabled
> through configuration, etc. These are marked __attribute__ ((unused))
> right now so that the compiler doesn't emit a warning (and with gcc >=3.4
> it doesn't even emit code for them). What's __optional about these
> functions if they have no callers? They're unused. So we cover all our
> bases with __maybe_unused.

Hi David,

If they're really unused, they should be deleted, not
warning-suppressed. The interesting case is where they may or may not
be used because of config options. ie. they're optional.

__maybe_unused does not, at a glance, tell me that it's OK for gcc to
drop them. __optional comes closer. However, it's better than
__unused, so I'll stop now 8)

Thanks,
Rusty.