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Date: Wed, 03 Sep 2008 11:57:07 +0300 From: Boaz Harrosh <bharrosh@...asas.com> To: Jan Beulich <jbeulich@...ell.com> CC: "David S. Miller" <davem@...emloft.net>, Ingo Molnar <mingo@...e.hu>, Ivo van Doorn <IvDoorn@...il.com>, Rusty Russell <rusty@...tcorp.com.au>, "John W. Linville" <linville@...driver.com>, Alexey Dobriyan <adobriyan@...il.com>, Andrew Morton <akpm@...ux-foundation.org>, Linus Torvalds <torvalds@...ux-foundation.org>, Theodore Tso <tytso@....edu>, linux-kernel <linux-kernel@...r.kernel.org> Subject: Re: [PATCH 5/5 ver2] debug: BUILD_BUG_ON: error on non-const expressions Jan Beulich wrote: >>>> Boaz Harrosh <bharrosh@...asas.com> 02.09.08 17:57 >>> >> -#define BUILD_BUG_ON_ZERO(e) (sizeof(char[1 - 2 * !!(e)]) - 1) >> +#define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); })) >> + >> +/* Force a compilation error if condition is true */ >> +#define BUILD_BUG_ON(e) \ >> + do { struct {int:-!!(e); } x __maybe_unused;} while(0) > > As indicated before, you should at the very least use __x as the variable > name. > The name does not matter. The scope of x is confined to the do {} while() and will not interfere with any local or global name. > But didn't you have reservations against using a bitfield here? Or was it > really just the void cast on the sizeof() that you disliked? > I like it it's fine. Also an added bonus is that on the good case it compiles to a size-less structure in a code-less block so even the most stupid non-optimizing compiler will get it right. OK that could be done with 0-length array too. But for consistency's sake I like it that both macros are the same. > Jan > I would like it if you sent your Signed-off-by: (or something) on this patch. Thanks for your help Boaz -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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