Makes the <functional> operator functors constexpr. Per N4139, part of this motion (constexpr on equal_to, not_equal_to, greater, less, greater_equal, less_equal comparison operators) was mis-applied and corrected in the C++14 IS (N4141), also resolving DIS comments JP 08/JP 09..
Other papers in Relaxed constexpr
N3302Constexpr Library Additions: complex, v2Portland 2012N3469Constexpr Library Additions: chrono, v3Portland 2012N3470Constexpr Library Additions: containers, v2Portland 2012N3471Constexpr Library Additions: utilities, v3Portland 2012N3652Relaxing constraints on constexpr functions / constexpr member functions and implicit constBristol 2013N3669Fixing constexpr member functions without constBristol 2013All 7 papers in Relaxed constexpr →