Can not override 'toString' method of a mix-in class

[spacemeowx2]

TypeScript Version: 2.2.1

Code

type Constructor<T> = new(...args: any[]) => T
function Tagged<T extends Constructor<{}>>(Base: T) {
  return class extends Base {
    _tag: string;
    constructor(...args: any[]) {
      super(...args)
      this._tag = ''
    }
  }
}

class A {
  toString () {
    return 'class A'
  }
}

class B extends Tagged(A) {
  // error TS2425
  toString () {
    return 'class B'
  }
}

class C extends A {
  toString () {
    return 'class C'
  }
}

Expected behavior:
No error.

Actual behavior:
error TS2425: Class 'Tagged.(Anonymous class) & A' defines instance member property 'toString'
, but extended class 'B' defines it as instance member function.

[govis]

Same here - it won't allow derived class to override any method that exists in both base class and the mixin. Won't let to call super.xxx() either with Error TS2340 Only public and protected methods of the base class are accessible via the 'super' keyword. A workaround would be highly appreciated.

[RyanCavanaugh]

We should be treating apparent properties as if they were on the prototype (because they are)