Type inference error in NNBD SDK

[liamappelbe]

I'm hitting a type inference error in when I run some tests with the NNBD SDK. Minimal example:

import 'dart:async';

var events = [];

foo() async {
  return 'in async function';
}

void main() {
  var asyncValueFuture = foo().then(events.add);
  Future.wait(<Future>[asyncValueFuture]).then((_) {
    print(events);
  });
}

This outputs "[in async function]" on the old SDK, but in the NNBD SDK it gives this error:

Unhandled exception:
type '(Object) => void' is not a subtype of type '(dynamic) => FutureOr<dynamic>' of 'f'
#0      main (file:///usr/local/google/home/liama/dart-sdk/junk/future_bug.dart:10:32)
#1      _startIsolate.<anonymous closure> (dart:isolate-patch/isolate_patch.dart:300:19)
#2      _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:167:12)

I can work around it by wrapping events.add in a lambda: (x) => events.add(x)

@a-siva fixed a similar issue in the libs by specifying the arg type in the lambda, and thinks it's a type inference bug in the CFE.

[johnniwinther]

Like caused by the missing normalization as with #40454

[johnniwinther]

This seems to have been fixed by https://dart-review.googlesource.com/c/sdk/+/134842