DDC NoSuchMethodError when using non-external factory or static methods on all `package:js` classes

[evanweible-wf]

• Dart SDK Version: 2.7.2 (I tried to test on 2.9.3 but hit Could not find an option named "sound-null-safety" build#2832)
• MacOSX
• Chrome

---

pubspec.yaml

environment:
  sdk: ">=2.7.0 <3.0.0"

dev_dependencies:
  build_runner: any
  build_web_compilers: any
  js: any

web/main.dart

@JS()
library main;

import 'package:js/js.dart';

@anonymous
@JS()
abstract class Foo {
  external String get bar;
  external factory Foo({String bar});
  factory Foo.namedFactory() => Foo(bar: '!!');
}

void main() {
  print(Foo(bar: 'baz').bar); // Prints "baz"
  Foo.namedFactory(); // Throws a "NoSuchMethodError"
}

When built with DDC, running the above throws this error:

main.dart:16 Uncaught 
NoSuchMethodError: tried to call a non-function, such as null: 'dart.global.Foo' at main.dart 16:28                       main$
main$	@	main.dart:16
(anonymous)	@	main.dart.bootstrap.js:266
window.$dartRunMain	@	main.dart.bootstrap.js:265
(anonymous)	@	VM259:1
runMain	@	client.js:8758
(anonymous)	@	client.js:22459
(anonymous)	@	client.js:3802
call$2	@	client.js:10996
_asyncStartSync	@	client.js:3766
$call$body$main__closure	@	client.js:22471
call$1	@	client.js:22398
_rootRunUnary	@	client.js:4136
runUnary$2$2	@	client.js:12301
runUnaryGuarded$1$2	@	client.js:12233
_sendData$1	@	client.js:11784
perform$1	@	client.js:11936
call$0	@	client.js:11985
_microtaskLoop	@	client.js:3969
_startMicrotaskLoop	@	client.js:3975
call$1	@	client.js:10865
invokeClosure	@	client.js:1204
(anonymous)	@	client.js:1223
childList (async)		
call$1	@	client.js:10875
_scheduleAsyncCallback	@	client.js:3989
_rootScheduleMicrotask	@	client.js:4183
scheduleMicrotask	@	client.js:4018
schedule$1	@	client.js:11967
_addPending$1	@	client.js:11775
_sendData$1	@	client.js:11607
add$1	@	client.js:11507
_onIncomingMessage$1	@	client.js:22011
eval	@	VM242:3
invokeClosure	@	client.js:1204
(anonymous)	@	client.js:1223

This works as expected when building with dart2js.

[sigmundch]

Thanks for the report @evanweible-wf

@srujzs has been working through a lot of inconsistencies of js-interop in the two compilers recently. So we may want to close this issue as a duplicate of the many checks listed in #32929

We had other similar cases for which we wanted to report a static error, but this specific case seems like one that would be nice to support.

[evanweible-wf]

That seems reasonable to me. To avoid cluttering up the other issue, I'll ask here – would this fall under "declaring Dart members on a @js class (Dart code is silently ignored)", as in this just isn't a supported use case? Could it be?

I also tried a static method, which fails similarly and probably for the same reason.

[evanweible-wf]

Oh, sorry, I missed the last part of your comment, which answers my question:

but this specific case seems like one that would be nice to support.

Folding this into #32929 sounds good to me 👍

[srujzs]

I think forwarding factories is something we want to support in ddc and dart2js, no? In that case, it would make more sense to file a separate bug to fix this in ddc rather than combine this with the static error work.

[sigmundch]

good point - let's keep it then :)

[srujzs]

Couple comments clarifying since this came up again recently:

• This affects classes with @JS and with @anonymous, effectively making non-external constructors unusable in DDC for package:js (non-external generative constructors are disallowed).
• Static methods (as mentioned above) are affected by a similar issue, which means factories with @staticInterop don't work (as they get lowered to static stubs).

I updated the title to reflect this.

[rileyporter]

I ran into this recently with a @staticInterop non-external factory constructor, and when compiling the kernel aspects for DDC I got a slightly different error:

Invalid argument(s): Missing canonical name for Reference to Foo.foo|staticInteropFactoryStub

I think it could be part of the underlying issue for this already reported bug, but it happened at a different stage in the compilation than I expected. It seems like in DDC we might need to recompute the canonical names? @srujzs does that sound like it's the same as this issue to you? If not, I'll file a separate issue with a small repro to debug further.

[srujzs]

Since References are part of the AST, I suspect the bug is within the static interop eraser or DDC in handling this factory. I'm guessing dart2js does not have this issue? It might be the same underlying issue manifesting slightly differently, but nonetheless, I think I'd like to debug that a bit further, so please file a separate issue. Thanks!