I keep forgetting that a constexpr function in C++11 has to be a single
return statement.
libstdc++-v3/ChangeLog:
PR libstdc++/99985
* include/bits/hashtable.h (_Hashtable::_S_nothrow_move()): Fix
to be a valid constexpr function in C++11.
* testsuite/23_containers/unordered_set/cons/99985.cc: New test.