Overriding public virtual functions with private functions in C++

Question

Is there is any reason to make the permissions on an overridden C++ virtual function different from the base class? Is there any danger in doing so?

For example:

Answer 1

It can be done, and very occasionally will lead to benefits. For example, in our codebase, we are using a library that contains a class with a public function that we used to use, but now discourage the use of due to other potential problems (there are safer methods to call). We also happen to have a class derived from that class which a lot of our code uses directly. So, we made the given function private in the derived class in order to help everyone remember not to use it if they can help it. It doesn't eliminate the ability to use it, but it will catch some uses when the code tries to compile, rather than later in the code reviews.