Merge "Prevent calling new ftl::Optional"

    if (has_value()) return std::invoke(std::forward<F>(f), std::move(value()));

    return R();

  }

  // Delete new for this class. Its base doesn't have a virtual destructor, and

  // if it got deleted via base class pointer, it would cause undefined

  // behavior. There's not a good reason to allocate this object on the heap

  // anyway.

  static void* operator new(size_t) = delete;

  static void* operator new[](size_t) = delete;

};

template <typename T, typename U>