Is there a possibility you could change the title of the post to something relevant to its content? HN unfortunately has a policy against providing useful titles to links when page authors haven't done so themselves, and the intersection of people who will want to read your post and people who are interested in late medieval personal protective equipment is probably pretty low.

I'd love an explanation of how bool bit validity causes undefined behavior. Does the compiler emit "jump if equal to 1" instructions instead of "jump if equal or above 1" when comparing operands?