Forwarding ref. and variadic make_optional overloads missing

[daniel-j-h]

The stdlib provides forwarding ref. overloads and variadic template overloads for make_optional:
http://en.cppreference.com/w/cpp/utility/optional/make_optional

The same is missing from boost::optional at least from what I can tell (correct me if I'm wrong).

All I could find here are these two overloads:

optional<T> make_optional ( T const& v )
optional<T> make_optional ( bool cond, T const& v )

Which is sub-optimal since now users expecting a move will end up doing a copy instead:

boost::make_optional(std::move(bigObject)); // oops, calls T const& overload making a copy

cc @K-ballo

[akrzemi1]

Indeed. The rvalue overloads are missing.