Is there a way to forward declare covariance?

Question

Suppose I have these abstract classes Foo and Bar:

class Foo;
class Bar;

class Foo
{
public:
  virtual Bar* bar() = 0;
};

class Bar
{         


        

Answer 1

Doesn't static polymorphism solve your problem? Feeding the base class with the derived class through template argument? So the base class will know the derivative Type and declare a proper virtual?