On Tue, Mar 20, 2018 at 4:23 PM, Linus Torvalds <torva...@linux-foundation.org> wrote: > > Hmm. So thanks to the diseased mind of Martin Uecker, there's a better > test for "__is_constant()": > > /* Glory to Martin Uecker <martin.uec...@med.uni-goettingen.de> */ > #define __is_constant(a) \ > (sizeof(int) == sizeof(*(1 ? ((void*)((a) * 0l)) : (int*)1))) > > that is actually *specified* by the C standard to work, and doesn't > even depend on any gcc extensions.
Well, it does depend on 'sizeof(*(void *)X)' being 1 and the compiler not complaining about it, and that sizeof(int) is not 1. But since we depend on those things in the kernel anyway, that's fine. Linus -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html