Are move semantics incomplete?

Question

Move semantics replace copy semantics in situations where copying is inefficient. Copy semantics deals fully with copyable objects, including const objects.

Already,

Answer 1

Sorry, but the premise is flawed.

An unordered_set doesn't actually hold const objects. It's just not giving you write access to the contained elements. That's a property of the accessors only.

It would be possible to add an key erase(iterator) function which just moves the element out to a temporary. I'm not sure why you'd want a key&& there.

As for const MyClass&& ~MyClass() const, that doesn't make sense for three reasons: dtors have neither return types nor CV classification, nor is overload resolution done for them.