linux-kernel - Re: kernel coding style for if ... else which cross #ifdef

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Date:	Fri, 23 May 2008 16:03:27 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Steve French <smfrench@...il.com>
CC:	lkml <linux-kernel@...r.kernel.org>
Subject: Re: kernel coding style for if ... else which cross #ifdef

Steve French wrote:
> A question splitting "else" and "if" on distinct lines vs. using an
> extra line and extra #else came up as I was reviewing a proposed cifs
> patch.   Which is the preferred style?
> 
> #ifdef CONFIG_SOMETHING
>    if (foo)
>       something ...
>    else
> #endif
>    if ((mode & S_IWUGO) == 0)
> 
> or alternatively
> 
> #ifdef CONFIG_SOMETHING
>    if (foo)
>       something ...
>    else if ((mode & S_IWUGO) == 0)
> #else
>    if ((mode & S_IWUGO) == 0)
> #endif
> 

The former.  Why?  Because the latter case has unbalanced indentation: 
to an editor, and to the human eye, it looks like the if in the #else 
clause is a child to the "else if".

*However*, the best would really be if we changed Kconfig to emit 
configuration constants what were 0/1 instead of undefined/defined. 
That way we could do:

	if (CONFIG_SOMETHING && foo) {
		/* ... something ... */
	} else if ((mode & S_IWUGO) == 0) {
		/* ... */

... in many cases.

	-hpa
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