linux-kernel - RE: do { } while (0) question

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Date:	Tue, 01 Aug 2006 11:39:31 +0200
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Hua Zhong <hzhong@...il.com>
Cc:	'Jiri Slaby' <jirislaby@...il.com>,
	'Heiko Carstens' <heiko.carstens@...ibm.com>,
	'Andrew Morton' <akpm@...l.org>, linux-kernel@...r.kernel.org,
	'Martin Schwidefsky' <schwidefsky@...ibm.com>
Subject: RE: do { } while (0) question

On Tue, 2006-08-01 at 02:03 -0700, Hua Zhong wrote:
> > #if KILLER == 1
> > #define MACRO
> > #else
> > #define MACRO do { } while (0)
> > #endif
> > 
> > {
> > 	if (some_condition)
> > 		MACRO
> > 
> > 	if_this_is_not_called_you_loose_your_data();
> > }
> > 
> > How do you want to define KILLER, 0 or 1? I personally choose 0.
> 
> Really? Does it compile?

No, and that is the whole point.

The empty 'do {} while (0)' makes the missing semicolon a syntax error.


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