Issue for discussion of super mixin type argument inference

[leafpetersen]

I've updated the Dart 2.0 super mixin type inference specification to use the syntax from this proposal here. This issue is for any relevant discussion, comments, or feedback.

cc @lrhn @eernstg @munificent

[leafpetersen]

No new discusssion (unsurprising) I'll go ahead and close this out.

[yjbanov]

Somehow I missed this issue. There's one instance where Flutter has to ignore the MIXIN_INFERENCE_INCONSISTENT_MATCHING_CLASSES check. However, from what I can tell, the new proposal fixes the issue.

[leafpetersen]

Hmm, why does the proposal address this - it's just porting over what's already implemented for class based super-mixins? Can you point me at what the inconsistent matching classes are?

[yjbanov]

https://github.com/flutter/flutter/blob/master/packages/flutter/lib/src/widgets/dismissible.dart#L190

The reason I believe that the proposal addresses the issue is in the first example given in the Inference proceeds outwards section, which seems to match Flutter's usage if you substitute _DismissibleState for A, State<Dismissible> for M0<int>, and AutomaticKeepAliveClientMixin for M1. The example states that "M1 is inferred as M1<int>", which for Flutter should translate to "AutomaticKeepAliveClientMixin is inferred as AutomaticKeepAliveClientMixin<Dismissible>".

I did overlook the fact that Flutter's case contains not one but two mixins, which may be where things break down.

[leafpetersen]

You're right. It's a bug that this isn't working already.

dart-lang/sdk#34404