Idiom exclusion is really so important

Yeah. That would be nice. My idea is that it would be scope based. The compiler would trap any integer overflows and goto the label. I've left off \ characters and probably made typos but you get the idea:

#define saturate(math...) (__attribute__(overflow overflowed_label) {
size_t result;
bool overflow = false;
result = (math);
goto done;

overflowed_label:
overflow = true;
done:
overflow ? SIZE_MAX : result;
})