Not sure how this is apparently working (or if it is) but the NaN should never compare equal to itself. On earlier versions of C isnan was often a macro that expanded to this comparison. isnan is in the standard library since C++11 so IMO this ought to be used on all platforms.
https://github.com/neuromore/studio/blob/1.7.3/src/Engine/Core/Math.inl#L11
Not sure how this is apparently working (or if it is) but the NaN should never compare equal to itself. On earlier versions of C
isnanwas often a macro that expanded to this comparison.isnanis in the standard library since C++11 so IMO this ought to be used on all platforms.