linux-kernel - Re: [PATCH] Clarify error on directive in macro arguments (Re: [PATCH] jffs2: fix sparse errors: directive in argument list)

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Message-ID: <20131118023443.GN13318@ZenIV.linux.org.uk>
Date:	Mon, 18 Nov 2013 02:34:43 +0000
From:	Al Viro <viro@...IV.linux.org.uk>
To:	Joe Perches <joe@...ches.com>
Cc:	Greg Price <price@....EDU>, Christopher Li <sparse@...isli.org>,
	Erico Nunes <nunes.erico@...il.com>,
	linux-sparse@...r.kernel.org, dwmw2 <dwmw2@...radead.org>,
	linux-mtd <linux-mtd@...ts.infradead.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Clarify error on directive in macro arguments (Re:
 [PATCH] jffs2: fix sparse errors: directive in argument list)

On Sun, Nov 17, 2013 at 06:15:32PM -0800, Joe Perches wrote:
> > > sparse matches gcc behaviour (I hope), but it warns about such abuses.
> > > It's a defect, all right - one being reported by sparse.
> > 
> > Perhaps the following tweak to the error message would make this
> > subtlety clearer?
> 
> Maybe, but this case isn't a macro.  It's a function.
> Dunno if differentiating when it's a macro or a
> function is difficult though.

In which case?  With printk() it's perfectly fine and sparse
will not complain at all.  With pr_info(), OTOH, we have
#define pr_info(fmt, ...) \
        printk(KERN_INFO pr_fmt(fmt), ##__VA_ARGS__)
and when you start playing that kind of games with it, you get warnings.
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