http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44436
--- Comment #27 from Jonathan Wakely <redi at gcc dot gnu.org> 2011-06-09 13:13:36 UTC --- (In reply to comment #25) > When I googled for this problem a year ago I've read that the second line > doesn't work by *specification* and that you *have* to use emplace. No, that's never been true. The type of instancesByIds_[id] is a reference to the mapped_type, i.e. unique_ptr<User>& and you have always been able to move assign to a unique_ptr from an rvalue, by design. You would have to use emplace for a container of objects which were not copyable *or* movable, but unique_ptr is movable.
