Hi, Despite a helpful, scary comment above its definition in mfbt/Assertions.h, MOZ_ASSUME_UNREACHABLE is being misused. Not pointing fingers to anything specific here, but see http://dxr.mozilla.org/mozilla-central/search?q=MOZ_ASSUME_UNREACHABLE&case=true.
The only reason why one might want an unreachability marker instead of simply doing nothing, is as an optimization --- a rather arcane, dangerous, I-know-what-I-am-doing kind of optimization. How can we help people not misuse? Should we rename it to something more explicit about what it is doing, such as perhaps MOZ_UNREACHABLE_UNDEFINED_BEHAVIOR ? Should we give typical code a macro that does what they want and sounds like what they want? Really, what typical code wants is a no-operation instead of undefined-behavior; now, that is exactly the same as MOZ_ASSERT(false, "error"). Maybe this syntax is unnecessarily annoying, and it would be worth adding a macro for that, i.e. similar to MOZ_CRASH but only affecting DEBUG builds? What would be a good name for it? Is it worth keeping a close analogy with the unreachable-marker macro to steer people away from it --- e.g. maybe MOZ_UNREACHABLE_NO_OPERATION or even just MOZ_UNREACHABLE? So that people couldn't miss it when they look for "UNREACHABLE" macros? Benoit _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
