[Bug libstdc++/59969] std::pair nonstandard constructor interferes when calling map::emplace with noncopyable nonmovable object

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59969

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
P.S. http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n4064.html will
improve things in this area, but isn't implemented yet.