C++ const semantics for a reference

Question

If there is something like below in code:

func(const base& obj)

what does the const semantics mean? What is constant here ? Is obj a const reference to a non-const object or a non-const reference to a const object?

Answer 1

There is no such thing as a "non-const" reference, that is, a reference is always bound to the same object and there is no way to change that. "const type&" means reference to const type.