> But once in a blue moon they are, so why not be cautious? You have to balance the inconvenience of false positives against the consequences of false negative

> But once in a blue moon they are, so why not be cautious? You have to balance the inconvenience of false positives against the consequences of false negatives. If the false negatives are rare enough, compared to the false positives, it might be best not to be cautious. Still, in practice I am fairly cautious, and tolerate zero warning. When someone reports a warning to me, I always try to fix it. So in practice, what I do is fairly close to -Werror, with one big difference: if some compiler comes up with some new warning, or if a set of compilers are impossible to please at the same time, my users aren't blocked. Which is important, because new warnings are now overwhelmingly likely to be false positives. That mismatch bound you just showed however does set off my alarm bells. I'll need to make sure I actually got rid of it.