C++ Primer, Fifth Edition

The final and override Specifiers

As we’ll see in §15.6 (p. 620), it is legal for a derived class to define a function with the same name as a virtual in its base class but with a different parameter list. The compiler considers such a function to be independent from the base-class function. In such cases, the derived version does not override the version in the base class. In practice, such declarations often are a mistake—the class author intended to override a virtual from the base class but made a mistake in specifying the parameter list.

Finding such bugs can be surprisingly hard. Under the new standard we can specify override on a virtual ...