This comment was originally written by shalmak...@gmail.com

It seems to me that there are 2 additional issues here -
1 - an instance method receiving an int and returning void doesn't match RequestAnimationFrameCallback (presumably because of the hidden "this" argument?). I guessed that this is why the above is failing and successfully worked around it with another method like this:
  RequestAnimationFrameCallback callback_maker()
  {
    return (int time) { my_method(time); };
  }

// ...
      RequestAnimationFrameCallback c = callback_maker();
    window.requestAnimationFrame(c);

2 - the error message doesn't accurately describe the problem because type '(int) => void' IS in fact identical to RequestAnimationFrameCallback. If it would say '(myobject, int) => void' is not a subtype etc. then I would understand why it is failing.

I don't know whether #­1 would be considered a defect or a desirable behavior. I would either expect methods to be acceptable as callbacks with "this" being passed implicitly, or alternately I would expect an error message that would explicitly show the problematic "this" argument.

Removed Priority-Medium label.
Added Priority-Unassigned label.

This comment was originally written by @mhausner

Would be nice to have a simpler, standalone example that reproduces the situation.

Removed Type-Defect label.
Added Type-Enhancement label.

My pleasure. Here's an app:

typedef bool DoThing(int x);

run(DoThing callback) {
  callback(1);
}

main() {
  run(() => print('this will fail at runtime'));
}

Run it this way:

sethladd:~/tmp$ dart --checked typedef.dart

Get this error:

Unhandled exception:
type '() => dynamic' is not a subtype of type 'DoThing' of 'callback'.
#­0 run (file:///Users/sethladd/tmp/typedef.dart:3:13)
#­1 main (file:///Users/sethladd/tmp/typedef.dart:8:6)

Suggestion:

Can we print out what the signature of DoThing is? Maybe:

type '() => dynamic' is not a subtype of type '(int) => bool' of 'callback'.

Thanks for taking a look.

This comment was originally written by @mhausner

Thank you for the simple repro case!

Set owner to @mhausner.
Added Accepted label.

I am still puzzled as to what we are supposed to fix here. DoThing takes an int parameter, it is being assigned a value that takes no parameter. Mismatch, checked mode failure, all is well.

The one thing that could be worded better is the "of 'callback'."

cc @gbracha.

Hi Ivan,

Can we tell the user what the signature of DoThing is? That would be really helpful. And yes, "of callback" isn't very clear.

dart ~/dart/Bug5740.dart
Unhandled exception:
Closure call with mismatched arguments: function 'main.'

NoSuchMethodError: incorrect number of arguments passed to method named 'main.'
Receiver: Closure: () => dynamic
Tried calling: main.(1)
Found: main.()
#0 Object._noSuchMethod (dart:core-patch/object_patch.dart:42)
#1 Object.noSuchMethod (dart:core-patch/object_patch.dart:45)
#2 run (file:///Users/iposva/dart/Bug5740.dart:4:11)
#3 main (file:///Users/iposva/dart/Bug5740.dart:8:3)
#4 _startIsolate. (dart:isolate-patch/isolate_patch.dart:261)
#5 _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:148)