Sure, if you write all the code. If you're writing a library or more generic functions, you don't have that power.
And, even then, while you can do this it's going to be much more code and more prone to bugs. C++ is complex, but that complexity can often bring simplicity. I don't need to specialize for int, double, float, etc because the compiler can do it for me. And I know the implementation will be correct. If I specialize by hand, I can make mistakes.
In addition, this isn't something where C "shines". You can do the exact same thing in C++, if you want. Many templates have hand-rolled specializations for some types.
> apples vs apples
It is, they're both qsort. When every single comparison requires multiple dereferences + a function call it adds up.
> For some inputs if you're willing to use a specialist sort the best option today is C
I don't understand how. Even if this is the case, which I doubt, you could just include the C headers in a C++ application. So, C++ is equally as good of a choice + you get whatever else you want/need.
> Rust has significantly faster sort (stable and unstable) than any of the three C++ stdlibs
Maybe, but there's a new std::sort implementation in LLVM 17. Regardless, the Rust implementations are very fast for the same reason the C++ implementations are fast - encoding information in types at compile-time and aggressively inlining the comparison function. Rust has a very similar generic methodology to C++.
