TITLE: Cannot access inherited protected members via base ptr

[ Adapted from "C++ Gotchas", tutorial notes by Tom Cargill,
  p. 40 ]

class Base {
  protected:
    int state;
};

class Derived : public Base {
  public:
    void f () {
	state = 1;		// fine

   	D* dp = new D;
	dp->state = 2;		// fine

	B* bp = new D;		
	bp->state = 3;		// illegal
    }
};

For more discussion of this, see the ARM, p. 253.