Implementing pure virtual function from abstract base class: does override specifier have any meaning?

Question

Background

I just stumbled over a use case of the override specifier that, as far as I can tell, seems redundant and also without any particular semantics meaning,

Answer 1

I'm not a big fan of override, but, assuming it's something that you find useful in general, then, yes, putting override on a virtual function that overrides a pure virtual functions is useful. Consider this rather contrived example:

struct Base {
    virtual void f() = 0;
};

struct Derived : Base {
    virtual void f();
    virtual void f(int);
};

Now suppose that the maintainer of Base (perhaps even your future self) changes Base to look like this:

struct Base {
    virtual void f(int) = 0;
};

Now the behavior of Derived has quietly changed. With override the compiler would report an error.