What’s the consensus on using
if-constexpr in writing the Stan Math library? (See [here](https://hackernoon.com/a-tour-of-c-17-if-constexpr-3ea62f62ff65 .) As I understand it, it is a C++ 17 feature, so I am probably not allowed to use it. However, I wanted to confirm just to be sure as it would avoid a lot of code bloat in various places.
According to the cppreference, they are supported from
GCC 7, Clang 3.9, MSVC 19.11.