It's both. Note that this CachedObject class is an abstract class. My instances are subclasses of CachedObject, and that's why the handler has an argument of type Self, and not a static type. If I ignore the warning, everything is fine (just an inconsistent warning). If I want to discard the warning, which I did with Swift 4, I need to do "_ = object.reload()", but since Swift 5, it generates a compiler error.