[Bug c++/71243] Implicitly defined assignment operator is not constexpr even though it should be

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71243

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
The code is not valid in C++11, only C++14, and it seems that GCC 5 doesn't
implement the C++14 rules fully.

Since it's already fixed in GCC 6 I think this can be closed as FIXED.