On Tue, 2009-10-20 at 11:42 +1030, Rusty Russell wrote: > On Tue, 20 Oct 2009 04:49:29 am Hollis Blanchard wrote: > > On Thu, 2009-10-15 at 08:27 +0100, Jan Beulich wrote: > > > My perspective is that it just uncovered already existing brokenness. > > > > Sorry, I thought it was clear, but to be more explicit: I propose the > > following patch, which replaces the current BUILD_BUG_ON implementation > > with Rusty's version. > > OK, I switched my brain back on. Yeah, I agree: we may still want > BUILD_OR_RUNTIME_BUG_ON one day, but I like this. > > It's just missing the giant comment that it needs :) > > /** > * BUILD_BUG_ON - break compile if a condition is true. > * @cond: the condition which the compiler should know is false. > * > * If you have some code which relies on certain constants being equal, or > * other compile-time-evaluated condition, you should use BUILD_BUG_ON to > * detect if someone changes it. > * > * The implementation uses gcc's reluctance to create a negative array, but > * gcc (as of 4.4) only emits that error for obvious cases (eg. not arguments > * to inline functions). So as a fallback we use the optimizer; if it can't > * prove the condition is false, it will cause a link error on the undefined > * "__build_bug_on_failed". This error is less neat, and can be harder to > * track down. > */ Do you want to put together a signed-off patch Rusty? It's your code, so I don't feel comfortable doing that. Once we have that, can we remove the mysterious MAYBE_BUILD_BUG_ON statements introduced in previous patches? (Does it BUG or doesn't it??) -- 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
