> I wonder if we can find an example of a function that is externally observable to a user, but that is guaranteed to finish. I don't think the standard has su

> I wonder if we can find an example of a function that is externally observable to a user, but that is guaranteed to finish. I don't think the standard has such a thing, but if it did, the closest thing would probably be a write to a volatile variable. You'd have to make sure the compiler sees the variable as having a side-effect in the first place (so it would probably need external linkage).