Do not provide different default arguments for a virtual function and an overrider

Reason

That can cause confusion: An overrider does not inherit default arguments.

Example, bad

class Base {
public:
    virtual int multiply(int value, int factor = 2) = 0;
    virtual ~Base() = default;
};

class Derived : public Base {
public:
    int multiply(int value, int factor = 10) override;
};

Derived d;
Base& b = d;

b.multiply(10);  // these two calls will call the same function but
d.multiply(10);  // with different arguments and so different results

Enforcement

Flag default arguments on virtual functions if they differ between base and derived declarations.

C.hier-access: Accessing objects in a hierarchy