Can't compile without this inside extension.

[ykmnkmi]

If I remove this. inside this extension:

extension on HTMLElement {
  @JS('__click')
  external ExternalDartReference<void Function(Event event)?> onClickReference;

  void Function(Event event)? get onClick__ {
    return this.onClickReference.toDartObject;
  }

  set onClick__(void Function(Event event)? onClick) {
    this.onClickReference = onClick.toExternalReference;
  }
}

I get these errors:

web/main.dart:37:12: Error: Undefined name 'onClickReference'.
    return onClickReference.toDartObject;
           ^^^^^^^^^^^^^^^^
web/main.dart:42:5: Error: Setter not found: 'onClickReference'.
    onClickReference = onClick.toExternalReference;
    ^^^^^^^^^^^^^^^^

DartPad example.

[kevmoo]

CC @srujzs

[srujzs]

Interesting, this looks to be specific to external fields that exist within an extension (regardless of whether the on-type is an extension type or a class). While it does get treated as a getter-setter pair by the CFE, the parsing seems to differ. cc @johnniwinther