Method overriding rules might be too permissive #5786

class T1 {
    prop1: string = 'T1/prop1';
}

class T2 extends T1 {
    prop2: string = 'T2/prop2';
}

class A {
    propA: string;
    checkValue(value: T1) {
        console.assert(!!value.prop1);
    }
}

class B extends A {
    propB: string;
    checkValue(value: T2) {
        console.assert(!!value.prop2);
    }
}

const a: A = new B();
const t1: T1 = new T1();
a.checkValue(t1); // B.prototype.checkValue(), expecting T2 but getting T1.