Messages in this thread | | | Date | Sun, 17 Aug 2008 11:39:36 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: [PATCH] debug: fix BUILD_BUG_ON() for non-constant expressions |
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On Sun, 17 Aug 2008, Ingo Molnar wrote: > > try the patch below - it only gives this error during build:
Well, you didn't do it right:
> +#define __BBO(c) sizeof(const char[1 - 2*!!(c)]) > +#define __BBONC(c) __BBO(!__builtin_constant_p(c)) > +#define BUILD_BUG_ON_ZERO2(c) (__BBO(c) - __BBONC(c)) > +#define BUILD_BUG_ON2(c) (void)BUILD_BUG_ON_ZERO(c)
Look at the #define of BUILD_BUG_ON2 a bit more.
Hint: you're using the _wrong_ BUILD_BUG_ON_ZERO. The old one, not the v2 one!
That said, with that fixed, there's still something wrong. It does seem like gcc has some very odd interaction there with __builtin_constant_p. Odd.
Linus
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