Messages in this thread | | | Date | Wed, 03 Sep 2008 11:19:51 +0100 | From | "Jan Beulich" <> | Subject | Re: [PATCH 5/5 ver2] debug: BUILD_BUG_ON: error on non-const expressions |
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>>> Boaz Harrosh <bharrosh@panasas.com> 03.09.08 10:57 >>> >Jan Beulich wrote: >>>>> Boaz Harrosh <bharrosh@panasas.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.
I'm sorry to repeat this: If x is #define-d to anything but a simple identifier, this will break no matter that it's in a private scope. The absence of any identifier was a benefit of the sizeof() approach here.
Jan
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