Is it possible to dynamic_cast from one base class to another?

Question

For instance I have code like that

class Base1
{
  virtual void wonderFULL() = 0;
};

class Base2
{
  // all this weird members
};

class Derived : public Base1, public Base2
{
  // not so weird members
};

int main()
{
  Derived Wonder;
  magicFunction(&Wonder);
  return 0;
}

void magicFunction(Base2 *ptr)
{
  if (Base1 *b1 = dynamic_cast<Base1 *>(ptr))
    b1->wonderFULL();
}

However wonderFULL is never executed due to impossibility to cast ptr to b1. Is it possible at all to perform such a conversion?

Answer 1

This

#include <iostream>

class Base1 {
public:
    virtual void wonderFULL() = 0;
};

class Base2 {
public:
    virtual ~Base2() {}                                       // added so the code compiles
};

class Derived : public Base1, public Base2 {
    virtual void wonderFULL() {std::cout << "wonderful\n";}   // added so the code compiles
};

void magicFunction(Base2 *ptr) {
    if (Base1 *b1 = dynamic_cast<Base1 *>(ptr))
        b1->wonderFULL();
}

int main() {
    Derived Wonder;
    magicFunction(&Wonder);
    return 0;
}

prints wonderful for me. My conclusion is that you're not showing the code necessary for your problem to reproduce.

Take (a copy of) your actual code and by removing uneccessary code step by step distill it until you derive at a self-contained (needs no other headers except from the std lib), compilable example that reproduces the problem. Very likely you will find the problem while doing so. However, if you don't, you have the perfect repro case to come back here and ask about.