[1ris]

>C has been adding generics anyway, like _Generic.

"_Generic" added function overloads to c, not generics. The naming is exceptionally poor.

The submission is an example of generic programming. It an implementatin of something that works on all types that fullfill certain constrains. In this case comparable and swapable. "All types" include user defined types.

"_Generic" does something completely different. The C++ equvivalent would be std::conditional_v<std::is_same<T, int>, myIntFunc, std::conditional<std::is_same<T, double>, myDoubleFunc ............ The exact opposite of a generic, I'd argue, as myIntFunc and myDoubleFunc do depend on the type. You might use the preprocessor to create these functions that differ only in type, but then again, you might do what OP did.