class Foo {
    protected x: string;
}

class Bar {
    protected x: string;
}

interface I3 extends Foo, Bar { // error
}

interface I4 extends Foo, Bar { // error
    x: string;
}

class Baz {
    protected y: string;
}

interface I5 extends Foo, Baz {
    z: string;
}

var i: I5;
var r: string = i.z;
var r2 = i.x; // error
var r3 = i.y; // error