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From: Al Viro <viro@ftp.linux.org.uk>
To: Dave Jones <davej@redhat.com>,
	Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: Fix empty macros in acpi.
Date: Wed, 13 Jun 2007 01:26:31 +0100	[thread overview]
Message-ID: <20070613002631.GL21478@ftp.linux.org.uk> (raw)
In-Reply-To: <20070613002115.GA28778@redhat.com>

On Tue, Jun 12, 2007 at 08:21:15PM -0400, Dave Jones wrote:
> On Wed, Jun 13, 2007 at 01:00:29AM +0100, Al Viro wrote:
>  > On Tue, Jun 12, 2007 at 07:33:09PM -0400, Dave Jones wrote:
>  > > +#define DBG(x...) do { } while(0)
>  > 
>  > Eh...  Please, stop it - if you want a function-call-like no-op returning void,
>  > use ((void)0).  At least that way one can say DBG(....),foo(), etc.
> 
> They both end up compiled to nothing anyway, so I'm not bothered
> either way..   I'm not sure I follow why the syntax of that last part
> is a good thing.  It looks like something we'd want to avoid rather
> than promote?

If on one side of ifdef it's a void-valued expression, so it should be
on another; the reason is that we don't get surprise differences between
the builds...

IOW, if it doesn't build in some context, it should consistently fail to
build in that context.

  reply	other threads:[~2007-06-13  0:26 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-06-12 23:33 Fix empty macros in acpi Dave Jones
2007-06-13  0:00 ` Al Viro
2007-06-13  0:21   ` Dave Jones
2007-06-13  0:26     ` Al Viro [this message]
2007-07-03  5:22       ` Len Brown
2007-07-03  5:44         ` Dave Jones
2007-07-22  4:55           ` Len Brown

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