Code causing `dartdoc` errors and run-time crash. Bad code, bad analysers (or both)?

[Hugo van Galen]

The code below demonstrates two issues that I ran into, and I am unsure if I am doing wrong, or if these are bugs.

It causes the following run-time crash:
I/flutter (18372): The following assertion was thrown while finalizing the widget tree:

I/flutter (18372): _TestWidgetState.dispose failed to call super.dispose.

I/flutter (18372): dispose() implementations must always call their superclass dispose() method, to ensure that all the

I/flutter (18372): resources used by the widget are fully released.

Explicitly implementing a dispose() method that calls super.dispose() does not change the situation. I do not get what causes this, and I would like to understand (possibly the analyser should have picked up on it if invalid code?)

This same code also demonstrates errors when running `dartdoc` on the code. The generation fails with the message:

[error] The class 'TickerProviderStateMixin' can't be used as a mixin because it extends a class other than Object.

import 'package:flutter/material.dart';

abstract class _TestState<T extends StatefulWidget> extends State<T> {
  @override
  Widget build(BuildContext context);
}

class TestWidget extends StatefulWidget {
  @override
  State<StatefulWidget> createState() => new _TestWidgetState();
}

class _TestWidgetState extends _TestState<TestWidget> with TickerProviderStateMixin {
  @override
  Widget build(BuildContext context) => const Text( "foo" );
}

I like to understand why these two issues occur. Thanks in advance for any replies.

Cheers,

Hugo

[Ian Hickson]

I don't see any error when I put the code above into the "flutter create" template and replace the "body" of the Scaffold with a "new TestWidget()".

Can you file a bug with a self-contained main.dart that shows the problem?

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Ian Hickson

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