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From: Rusty Russell <rusty@rustcorp.com.au>
To: Boaz Harrosh <bharrosh@panasas.com>
Subject: Re: [PATCH] debug: fix BUILD_BUG_ON() for non-constant expressions
Date: Mon, 25 Aug 2008 11:19:09 +1000
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Cc: Ingo Molnar <mingo@elte.hu>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Alexey Dobriyan <adobriyan@gmail.com>,
       Andrew Morton <akpm@linux-foundation.org>,
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       Sam Ravnborg <sam@ravnborg.org>
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On Wednesday 20 August 2008 02:33:59 Boaz Harrosh wrote:
> If the user of virtio_has_feature() must pass a compile-time constant then
> it must be converted to a MACRO, and then the BUILD_BUG_ON will work.
> Or it should be changed to a BUG_ON() if fbit is a runtime variable.

I was (ab)using the current slackness of BUILD_BUG_ON() to be a noop on 
non-constants.  We can replace with a BUG_ON if we fix BUILD_BUG_ON() to 
insist on a compile-time constant; I think that's still an overall win.

Cheers,
Rusty.