It certainly got better, but it's still not trivial. With the sanitizers, you need to have code that actually triggers the UB, coverage is not enough. If your U

It certainly got better, but it's still not trivial. With the sanitizers, you need to have code that actually triggers the UB, coverage is not enough. If your UTF-8 parsing code UB only on some very specific input, then unless your tests or own environment happen to have this input, you'll be none the wiser. Fuzz testing helps, but it's not commonly used in my experience.