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List:       freebsd-current
Subject:    Re: (void)foo or __unused foo ?
From:       Tim Kientzle <tim () kientzle ! com>
Date:       2012-07-28 6:41:10
Message-ID: B86B2D65-25E3-4887-9203-AFED9563CE51 () kientzle ! com
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On Jul 27, 2012, at 2:38 AM, Luigi Rizzo wrote:
> 
> The alternative way to avoid an 'unused' warning from the compiler
> is an empty statement
> 
> 	(void)foo;
> 
> that the compiler hopefully optimizes away.

I learned the void-cast convention many years ago.
I used it throughout the libarchive code and have yet to
run into any problems.  I always use it in exactly this form
(with the exact comment here) so that I can easily search
on it:

int foo(int a) {

   (void) a; /* UNUSED */
    …
}

I agree with PHK that it would be nice to express this
intent in a way that static checkers could verify.   I also
agree that having static checkers interpret comments is Evil.
But I have yet to see any alternative that was as
straightforward and widely-supported as this one.

Every other viable alternative seems to require tangled
clumps of macros.

Tim

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