title: How to print result of a compile-time calculation in C++?
body: <p>I've wrote several constexpr functions and use them in static_asserts to control some resource limits. But I'd like to not only enforce compile-time predicate but also to see the actual values calculated during normal compilation process or at least when assertion fails.</p>
  
  <p>There are ways to print string messages during compilation, but what's about printing results of constexpr computations?</p>