Bug: Wrong `this` in bound methods of nested classes

[gsamokovarov]

While upgrading an application to CS2 we ran into the following issue in an obscure usage of nested classes.

As you can see, the nested bound method thought its this is the parent class. This seems to happen on a "parse" level, because it's replaced in the code. This lead to tricky to catch bug on our side.

[rdeforest]

I've been looking into this and while I don't have a solution, I believe I have a work-around which may or may not be useful to you. If you assign the bound method to a var, the generated method references the inner class name instead of the outer one.

class Outer
  class Inner
    bound: bound = =>
      @name

Compiles to

var Outer;

Outer = (function() {
  var Inner;

  class Outer {};

  Inner = (function() {
    var bound;

    class Inner {};

    Inner.prototype.bound = bound = () => {
      return Inner.name;
    };

    return Inner;

  }).call(this);

  return Outer;

}).call(this);

I hope someone finds this useful.