On Wed, 2009-09-30 at 07:35 +0100, Jan Beulich wrote: > >>> Hollis Blanchard <hollisb@xxxxxxxxxx> 30.09.09 01:39 >>> > >On Tue, 2009-09-29 at 10:28 +0100, Jan Beulich wrote: > >> >>> Hollis Blanchard 09/29/09 2:00 AM >>> > >> >First, I think there is a real bug here, and the code should read like > >> >this (to match the comment): > >> > /* type has to be known at build time for optimization */ > >> >- BUILD_BUG_ON(__builtin_constant_p(type)); > >> >+ BUILD_BUG_ON(!__builtin_constant_p(type)); > >> > > >> >However, I get the same build error *both* ways, i.e. > >> >__builtin_constant_p(type) evaluates to both 0 and 1? Either that, or > >> >the new BUILD_BUG_ON() macro isn't working... > >> > >> No, at this point of the compilation process it's neither zero nor one, > >> it's simply considered non-constant by the compiler at that stage > >> (this builtin is used for optimization, not during parsing, and the > >> error gets generated when the body of the function gets parsed, > >> not when code gets generated from it). > > > >I think I see what you're saying. Do you have a fix to suggest? > > The one Rusty suggested the other day may help here. I don't like it > as a drop-in replacement for BUILD_BUG_ON() though (due to it > deferring the error generated to the linking stage), I'd rather view > this as an improvement to MAYBE_BUILD_BUG_ON() (which should > then be used here). Can you be more specific? I have no idea what Rusty suggested where. I can't even guess what MAYBE_BUILD_BUG_ON() is supposed to do (sounds like a terrible name). All I know is that this used to build... -- Hollis Blanchard IBM Linux Technology Center -- To unsubscribe from this list: send the line "unsubscribe linux-next" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
