C++-style `const` modifier on class members about typescript HOT 4 OPEN

class Point
  readonly x: number;
  readonly y: number;
  modify(this: Mutable<Point>, x: number, y: number) {

  }
}

class Point {
	readonly x: number;
	readonly y: number;

	modify(this: Mutable<Point>, x: number, y: number) {
	  this.x = x;
      this.y = y;
    }
}

const p = new Point(0, 0);

p.modify(3, 4); // error? (argument of type Point is not assignable to type Mutable<Point>)

const q = p as Mutable<Point>; // then wouldn't this also error with the same type conversion?
q.modify(3, 4);

// and if not, then i could also do this

function badFunc(point: Point) {
  (point as Mutable<Point>).modify(3, 4);
}

function createConvexHull(const poly: Polygon): Polygon {
	//...
}