c++ - Assignment operator with derived type argument

class A {
private:
    A& operator=(const A&);
};

class B : public A {
public:
    B& operator=(const A&) {
            return *this;
    }

};


int main() {

    B b1;
    B b2;

    b1 = b2;


    return 0;
}

This gives error on compilaton:

test.cpp: In member function 'B& B::operator=(const B&)':
test.cpp:16:5: error: 'A& A::operator=(const A&)' is private
test.cpp:19:20: error: within this context
test.cpp: In function 'int main()':

test.cpp:31:7: note: synthesized method 'B& B::operator=(const B&)'
first required here 
Build error occurred, build is stopped

Since B::operator=(A&) has a non-standard signature, the compiler generates it's own B::operator=(B&) which (tries) to call A::operator(A&), which is private.

Is there any way I can get the compiler to use B::operator=(A&) also for B arguments?