[Bug c++/57588] [C++11][constexpr] static constexpr in class fails to link

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57588

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Although shouldn't it fail to compile, due to private destructor and copy
constructor?