Due to the introduction of "virtual parameters" (parameters of virtual functions) there was a new pattern that allowed for non-converging types. If two functions are mutually recursive and one makes a virtual call to the other, then we end up with a cycle in the parameter types.
That part isn't new, that cycle already existed. However, now the cycle can include the virtual parameters for those functions. The way we enqueue the users after resolving a virtual parameter can cause an alternating pattern of refinement that doesn't allow the cycle to fully resolve itself.
We resolve this by manually enqueueing the concrete parameter and its associated NarrowTypeInformation (which enforces the static type). The key is that these are enqueued before other users of the virtual parameter which in the bad case are other members in the cycle that were being processed out of order.
Change-Id: Ic20afcc55ca6e75152d7858eaab1cb24a57ea20e
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/303120
Commit-Queue: Nate Biggs <natebiggs@google.com>
Reviewed-by: Mayank Patke <fishythefish@google.com>
Nate Biggs
bb179504c0