Special case: optional<bool> and optional<T*>

While you can use optional on any type, you need to pay attention when trying to wrap boolean or pointers.

optional<bool> - what does it model? With such a construction, you have a tri-state bool. If you need it, then maybe it’s better to look for a real tri-state bool like boost::tribool.

What’s more, it might be confusing to use such type because optional<bool> converts to bool. Also, if there’s a value inside then accessing that value returns bool.

Likewise, you have a similar ambiguity with pointers: