Hello!

Thank you for a great library. I've been using it with great pleasure. Today I found an interesting deviation from how std::optional works, and I was wondering if it's on purpose or not: std::optional<const X> allows emplacing with a new value, whereas nonstd::optional<const X> seemingly does not.

This snippet fails with what I think is trying to placement-new into const memory:

  nonstd::optional<const int> nonstd_opt;
  nonstd_opt.emplace(0);

Godbolt link: https://godbolt.org/z/r46fccxEj

Thank you for your consideration.