It is. The page starts with talk about namespaces and such, so one thinks this will be about some cool new features of C++11, but instead ends with a global #define.

Yes, coding like this is evil and will eat your hamster. For example, trying to have a variable named "platform" will break your code in strange ways. And before you say "but it's C++, it's modern", CppCoreGuidelines explicitly say this is bad and that one should favor #ifdefs. (https://github.com/isocpp/CppCoreGuidelines/blob/master/CppC...)

I agree... if I see an `#if defined _WIN32` I know what I'm looking at, but this trick would be a complete surprise.