[boost] [Hana/Fit] about constexpr/noexcept on equivalent functions to std::overload

Hi, On the C++ standard meating in Oulu, we decided to make the std::overload function constexpr and conditionaly noexcept and ensure that the overloaded functions shall be constexpr if the stored finctions are. I don't find in the reference documentation of Hana and Fit any reference of whether the overloaded functions preserve constexpr or not. There is a reedit post [1] and CWG issue 1581 [2] that are related. Could the authors clarify? What other think? Best, Vicente [1] https://www.reddit.com/r/cpp/comments/35g7f6/c17_progress_update/cr4mvid [2] http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1581