Create a variant object holding the same alternative (if any) as the specified original object. If this variant is allocator‐aware, the currently installed default allocator is used to supply memory. If the original object is not valueless by exception', the contained value is copy‐constructed from the contained value of original. This constructor is deleted unless all alternatives are copy constructible. For simplicity of implementation, this method differs from the standard in the following ways: * conditional triviality is not implemented * constexpr is not implemented * noexcept specification is not implemented