I'm not sure I agree with this. Or at least, I'm not sure I think this will hold true once macros are used for more than control flow mechanisms, which are approximately half of the uses of the macros in the stdlib right now as far as I can see. After all, most C style guidelines do insist on some way of differentiating macros, commonly making them all-caps, but it makes it no less sketchy to throw a return into a macro.