#define os_log_fault(log, format, ...) \
          os_log_with_type(log, OS_LOG_TYPE_FAULT, format, ##__VA_ARGS__)

It's literally just an os_log with the "fault" type set. You can call it whenever you want. Most libraries have a couple sprinkled in for things that someone should probably check at some point but there is no actual semantics to it to mean that something is necessarily broken.

This doesn't seem to indicate what you suggest. Can you link proof that even a single real world application calls it whenever it wants?

The mere fact that it's theoretically possible doesn't seem to be persuasive.

On the contrary, I find your position to be confusing. It's just a function that anyone can call. If you go on GitHub you can see many people who are using it for whatever logging they think is appropriate. Why do you think it has anything to do with correctness? This isn't like a crash or a OOM where you're generally pretty sure something is seriously wrong, because you can just trigger this whenever you want.

Then it would only take you a minute to link an example or two?