This is a library approximation of the WG21 proposal N3694 "Feature-testing recommendations for C++" by Clark Nelson.
The actual data on support comes from C++ Compilers standard conformance comparison by Raffaele Rialdi (Twitter @raffaeler).
Initial implementation is derived from Mach7 library, that had to reinvent the wheel as everyone else had to before Clark decided to put the proposal up.
Feel free to add/modify data on any other compilers you know.