Class method clash

first.cpp

#include "header.hpp"

#include <iostream>

class B : public A
{
    void f()
    {
        doIt();
    }

    static void doIt()
    {
        std::cout << "first" << std::endl;
    }
};

A *makeA1()
{
    return new B();
}

header.hpp

#ifndef HEADER_HPP__
#define HEADER_HPP__

class A
{
public:
    virtual void f() = 0;
};

A *makeA1();
A *makeA2();

#endif // HEADER_HPP__

main.cpp

#include "header.hpp"

#include <iostream>

int
main(int argc, char *argv[])
{
    std::cout << "A1:" << std::endl;
    makeA1()->f();
    std::cout << "A2:" << std::endl;
    makeA2()->f();
    return 0;
}

snd.cpp

#include "header.hpp"

#include <iostream>

class B : public A
{
    void f()
    {
        doIt();
    }

    static void doIt()
    {
        std::cout << "second" << std::endl;
    }
};

A *makeA2()
{
    return new B();
}