Is the final function specifier redundant when using the final class specifier?

Question

Is there any reason to specify a function as final when the class is already final? Or is that redundant?

class B
{
public:
    virtual void f();
};

class D final : public B
{
public:
    virtual void f() final; // Redundant final?
};

Would it be a good rule of thumb to say: Start with making the whole class final, and only switch to making individual functions final when you need to derive from the class and/or override specific functions?

Answer 1

It is definitely redundant because marking whole class as final makes it impossible to derive from this class and therefore override anything.

9 Classes [class]

3. If a class is marked with the class-virt-specifier final and it appears as a base-type-specifier in a base-clause (Clause 10), the program is ill-formed.

So compiler won't even bother to check whether class deriving from final class actually tries to override anything or not.