The whole <cfenv> thing is a giant mess - see Not sure what we should do here - just document them all as UB? T. Canens (talk) 15:35, 5 May 2016 (PDT)

the vendors that support fenv.h, along with the STDC pragmas, in their C front ends (Oracle, IBM, HP), support cfenv and the same STDC pragmas in their C++ front ends (when I wrote much of these pages, those were the compilers I used daily). I believe it would be a disservice to the community to remove something supported by multiple vendors just because a strict reading of the ISO standard may not require every vendor to do the same -- that's also why I've put IEEE rules in every function in cmath (under "if the implementation supports IEEE). I would much rather say "If the compiler supports C99 floating-point environment, then..." (and then hopefully more people would ask their neighborhood opensource vendors what's the deal with C99 support). --Cubbi (talk) 17:48, 5 May 2016 (PDT)