What should the returned function's 'this' be for constructor parameters?

[tbroyer]

The Anatomy of a parameter decorator section of the README shows "desugarization" for a method, but what about constructors?

Here, I'm simply changing method for constructor, and adding a super class and call to super() in the constructor:

class C extends BC {
  constructor(@A param1) {
    super(param1);
    ...
  }
}

Following the same "transformation", this should then be roughly equivalent to

var _param1_init
class C extends BC {
  static {
    _param1_init = A(undefined, { kind: "parameter", name: "param1", index: 0, /*...*/ });
  }
  constructor(param1) {
    // BOOM this breaks, you cannot reference `this` before you call `super()`
    // and you can't call super() first as _param1_init wouldn't have been called yet,
    // making it useless in many cases.
    if (_param1_init !== undefined) param1 = _param1_init.call(this, param1);
    super(param1);
    ...
  }
}

Should it then be called with undefined? with C?