// Derived member is private, base member is not causes errors

class Base {
    foo: string;
}

class Derived extends Base {
    bar: string;
}

class A {
    public foo: Base;
}

class B extends A {
    private foo: Derived; // error
}

class A2 {
    public 1: Base; 
}

class B2 extends A2 {
    private 1: Derived; // error
}

class A3 {
    public '1': Base;
}

class B3 extends A3 {
    private '1': Derived; // error
}