Re: [PATCH] debug: fix BUILD_BUG_ON() for non-constant expressions

From: Ingo Molnar
Date: Thu Aug 21 2008 - 08:18:41 EST



* Boaz Harrosh <bharrosh@xxxxxxxxxxx> wrote:

> Ingo Molnar wrote:
> > * Boaz Harrosh <bharrosh@xxxxxxxxxxx> wrote:
> >
> >> If the user of virtio_has_feature() must pass a compile-time constant
> >> then it must be converted to a MACRO, and then the BUILD_BUG_ON will
> >> work. Or it should be changed to a BUG_ON() if fbit is a runtime
> >> variable.
> >
>
> The use of __builtin_constant_p in inline functions is broken. This is
> because it will give different results depending on the -O level used.
> So I think that using it in the Kernel with inlines is plain broken.
> And should be discouraged.

ok - that's convincing, so your approach is superior to my hack on
multiple levels.

Could you please (re-)send your patch(es) with a changelog, etc., so
that i can apply it and drop my patches?

Thanks,

Ingo
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