Why isn't abs constexpr?

Question

In , since C++11, there are the following two overloads:

std::intmax_t abs( std::intmax_t n );
std::intmax_t imaxabs( std::intm         


        

Answer 1

The simple explanation is probably that nobody went through every function listed as part of the standard library, and updated the entry to make it constexpr.

Updating a standard is a process involving human effort to propose changes and get those proposals reviewed and accepted. And that means, when a new feature is added - and constexpr is a new feature - not everything else is automagically updated to use that feature. This particular case may well be updated in a future evolution of the standard - if some people take on the - often thankless - task of proposing the set of changes, some other people take on the task of reviewing it, and convincing those with voting power on the committee to accept it.