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

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Message-ID: <545187B6.1090704@infradead.org>
Date:	Wed, 29 Oct 2014 17:35:02 -0700
From:	Randy Dunlap <rdunlap@...radead.org>
To:	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Josh Triplett <josh@...htriplett.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 10/29/14 12:12, 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.
> 
> Apart from that:
> Acked-by: Geert Uytterhoeven <geert@...ux-m68k.org>

Is the compiler smart enough to delete (discard) the code or data instance
if it is unused or is the code or data actually wasting space?


-- 
~Randy
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