linux-kernel - Re: [patch 01/10] compiler: define __attribute_unused_

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Date:	Wed, 02 May 2007 17:51:55 +1000
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	David Rientjes <rientjes@...gle.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [patch 01/10] compiler: define __attribute_unused__

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.

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