http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36587
--- Comment #9 from Jonathan Wakely <redi at gcc dot gnu.org> --- I still think it would be nice to get a warning for e.g. std::unique_lock<M>(m); where "M m" is visible in an enclosing scope and would have been a viable argument for another constructor, but that would be a different enhancement request.
