[sebastic]

His logic is wrong. It's not because they are objects, it's because std::sort and friends are function templates. They know what they are calling at compile time. Templates allow for compile-time polymorphism like this.

Because of compile-time polymorphism, you can pass in prvalue function pointers and objects alike and the compiler will be able to inline.

C doesn't have templates, therefore it doesn't have compile-time polymorphism, therefore it's much harder for the compiler to inline.

Compilers like GCC and Clang can inline in some runtime-polymorphism circumstances. See -flto and -fdevirtualize.

[exDM69]

> C doesn't have templates, therefore it doesn't have compile-time polymorphism, therefore it's much harder for the compiler to inline.

A C compiler can do the same inlining and optimizing as long as the called function (e.g. qsort) and the function that's pointed-to (e.g. the comparison function) are in the same compilation unit.

C++ templates do not add any magic here, std::sort() is simply faster because it's in a header file and qsort() is not. If you pass a function pointer to a function in a different object file to std::sort, it won't have a lot of advantages over qsort in terms of optimizations/performance (it still does know sizeof(T), though).

Link-time optimization should make standard qsort-type functions perform similarly to std::sort.