When is static cast safe when you are using multiple inheritance?

Question

I found myself in a situation where I know what type something is. The Type is one of three (or more) levels of inheritance. I call factory which returns B* how

Answer 1

A cross cast doesn't need a dynamic_cast at all..

   struct Base1 { virtual void f1(); };
   struct Base2 { virtual void f2(); };
   struct Derived : Base1, Base2 {};

   Base1* b1 = new Derived();

   // To cast it to a base2 *, cast it first to a derived *
   Derived *d = static_cast(b1);
   Base2 *b2 = static_cast(d);