Geting Unexpected input. Please report this at dartbug.com from StreamingDartTypeTranslator::BuildTypeParameterType

[a-siva]

running flutter tests in google3 is producing an error
'Unexpected input. Please report this at dartbug.com'
from StreamingDartTypeTranslator::BuildTypeParameterType

We don't have much in terms of logs or repro instructions yet.
FlutterIosAotSnapshot action:
Error: error: Unexpected input. Please report this at dartbug.com.

[REDACTED]

[a-siva]

/cc @alexmarkov @mraleph

[mraleph]

Mixins again 🔥

class State<T> {}
class A {}
abstract class Mixin<T> extends State<T> {
  factory Mixin._() => null;
}

class AState extends State<A> {}
class AStateImpl extends AState with Mixin {}

void main() { new AStateImpl(); }

$ pkg/vm/tool/dart2 /tmp/mixin.dart
Unhandled exception:
error: Unexpected input. Please report this at dartbug.com.
#0      _startIsolate.<anonymous closure> (dart:isolate/isolate_patch.dart:279:19)
#1      _RawReceivePortImpl._handleMessage (dart:isolate/isolate_patch.dart:165:12)
$ pkg/vm/tool/precompiler2 /tmp/mixin.dart /tmp/mixin.snap
error: Unexpected input. Please report this at dartbug.com.

This is caused by factory constructor being copied as-is (with mismatching set of type arguments) into mixin application for some reason - this should not be needed. I think mixin transformation simply forgets to filter them out.

   abstract class _AState&Mixin extends mix::AState implements mix::Mixin<mix::A> {
     synthetic constructor •() → void
       : super mix::AState::•()
       ;
     static factory _<T extends core::Object>() → mix::Mixin<mix::_AState&Mixin::_::T>
       return null;
   }

[kmillikin]

Fixed in 52d1b4e.

[mraleph]

Reopening due to revert @kmillikin