In C++, is it allowed to cast a function pointer to one that gets as a parameter a pointer to a base or derived class?

Will the following work as expected?:

struct A {};

struct B: public A {
    int x;
    };

void f( B* o ) {
    std::cout << o->x << std::endl;
    }

int main () {
    B b;
    b.x = 5;
    reinterpret_cast<void(*)(A*)>(f)( &b );
    }