Suppose we have the following code:

#include <iostream>

struct A
{
    virtual void f() { 
        std::cout << "A::f()" << std::endl;
    }
};

struct B: A
{
    void f() { 
        std::cout << "B::f()" << std::endl;
    }
};

void to_A(void* voidp) {
    A* aptr = static_cast<A*>(voidp);
    aptr->f();
}

void to_B(void* voidp) {
    B* bptr2 = static_cast<B*>(voidp);
    bptr2->f();
}

int main() {
    B* bptr = new B;
    void* voidp = bptr; 
    to_A(voidp); // prints B::f()
    to_B(voidp); // prints B::f()
}

is this code guaranteed to always work as in the code comments or is it UB? AFAIK it should be ok, but I'd like to be reassured.