I genuinely forgot stdbool.h existed, I don't actually write that much C myself.

My point was more around the conditionals being weakly typed around unsigned ints rather than a specific lack of built-ins. A lot of commenters were going into arithmetic mod 2 or philosophical issues, neither of which actually apply here.

_Bool isn't part of stdbool. It's a language keyword. C23 introduces full support for bool with true and false as keywords.