Re: [PATCH] Use more gcc extensions in the Linux headers

[Robert P. J. Day]

On Sat, 10 Mar 2007, Rusty Russell wrote:

> On Fri, 2007-03-09 at 16:56 +1100, Rusty Russell wrote:
> > __builtin_types_compatible_p() has been around since gcc 2.95, and we
> > don't use it anywhere.  This patch quietly fixes that.
>
> OK, many people complained that it needed a comment.  Good point!
> ==
> Add comment to ARRAY_SIZE macro.
>
> Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
>
> diff -r 933e410f204f include/linux/kernel.h
> --- a/include/linux/kernel.h	Sat Mar 10 09:55:31 2007 +1100
> +++ b/include/linux/kernel.h	Sat Mar 10 09:55:53 2007 +1100
> @@ -35,6 +35,7 @@ extern const char linux_proc_banner[];
>  #define ALIGN(x,a)		__ALIGN_MASK(x,(typeof(x))(a)-1)
>  #define __ALIGN_MASK(x,mask)	(((x)+(mask))&~(mask))
>
> +/* GCC is awesome. */
>  #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0])			      \
>  	+ sizeof(typeof(int[1 - 2*!!__builtin_types_compatible_p(typeof(arr), \
>  		 typeof(&arr[0]))]))*0)

ah, but is that "universe" kind of awesome, or the "hot dogs" kind of
awesome?

http://youtube.com/watch?v=0rYT0YvQ3hs

rday

-- 
========================================================================
Robert P. J. Day
Linux Consulting, Training and Annoying Kernel Pedantry
Waterloo, Ontario, CANADA

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