Invoking a protected method from a PIMPL

gistfile1.cpp

class Foo;

class Bar {
    friend class Foo;

protected:
    void aProtectedMethod() {
    }
};

class Foo {
    class Impl {
    public:
        void invokeAProtectedMethod(Bar &b) {
            b.aProtectedMethod(); /* <-- MSVS does not allow to do it here */
        }
    };

    Impl *impl;

public:
    Foo() : impl(new Impl) {
    }

    ~Foo() {
        delete impl;
    }
    
    void invokeAProtectedMethod(Bar &b) {
        impl->invokeAProtectedMethod(b);
    }

    struct Baz {
        void invokeAProtectedMethod(Bar &b) {
            b.aProtectedMethod();
        }
    };
};


int main (int argc, char *argv[]) {
    Bar bar;
    Foo foo;
    foo.invokeAProtectedMethod(bar);

    Foo::Baz baz;
    baz.invokeAProtectedMethod(bar);
    return 0;
}