linux-kernel - Re: [PATCH] Documentation: Explain a second alternative for multi-line macros.

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Date:	Sun, 31 Dec 2006 19:23:28 -0800
From:	Randy Dunlap <randy.dunlap@...cle.com>
To:	Segher Boessenkool <segher@...nel.crashing.org>
CC:	"Robert P. J. Day" <rpjday@...dspring.com>,
	Muli Ben-Yehuda <muli@...ibm.com>,
	Linux kernel mailing list <linux-kernel@...r.kernel.org>,
	trivial@...nel.org
Subject: Re: [PATCH] Documentation: Explain a second alternative for multi-line
 macros.

Segher Boessenkool wrote:
>>> In this case, the second form
>>> should be used when the macro needs to return a value (and you can't
>>> use an inline function for whatever reason), whereas the first form
>>> should be used at all other times.
>>
>> that's a fair point, although it's certainly not the coding style
>> that's in play now.  for example,
>>
>>   #define setcc(cc) ({ \
>>     partial_status &= ~(SW_C0|SW_C1|SW_C2|SW_C3); \
>>     partial_status |= (cc) & (SW_C0|SW_C1|SW_C2|SW_C3); })
> 
> This _does_ return a value though, bad example.

Where does it return a value?  I don't see any uses of it
in arch/i386/math-emu/* that use it as returning a value.

And with a small change to put it inside a do-while block
instead of ({ ... }), it at least builds cleanly.
I expected some complaints.

-- 
~Randy
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