linux-kernel - Re: [PATCH] CodingStyle: Add a chapter on conditional compilation

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Message-ID: <20141029222015.GA17755@jtriplet-mobl1>
Date:	Wed, 29 Oct 2014 15:20:15 -0700
From:	Josh Triplett <josh@...htriplett.org>
To:	Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:	Jonathan Corbet <corbet@....net>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] CodingStyle: Add a chapter on conditional compilation

On Wed, Oct 29, 2014 at 08:12:49PM +0100, Geert Uytterhoeven wrote:
> On Wed, Oct 29, 2014 at 7:15 PM, Josh Triplett <josh@...htriplett.org> wrote:
> > Document several common practices and conventions regarding conditional
> > compilation, most notably the preference for ifdefs in headers rather
> > than .c files.
> >
> > Signed-off-by: Josh Triplett <josh@...htriplett.org>
> 
> > +If you have a function or variable which may potentially go unused in a
> > +particular configuration, and the compiler would warn about its definition
> > +going unused, mark the definition as __maybe_unused rather than wrapping it in
> > +a preprocessor conditional.  (However, if a function or variable *always* goes
> > +unused, delete it.)
> 
> Personally, I don't like __maybe_unused. Once it's there, the compiler
> will stop warning about it, even if it really becomes unused.

True.  It's a tradeoff between getting the compiler to warn about unused
code to allow removing it, and putting #ifdefs in .c files.  However,
in previous patch discussions, developers seem to come down pretty
consistently on the side of "don't put #ifdefs in .c files".

> Apart from that:
> Acked-by: Geert Uytterhoeven <geert@...ux-m68k.org>

Thanks!

- Josh Triplett
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