rpc package tests broken with "not a subtype" errors in 2.2+

[jcollins-g]

See dart-lang/sdk#35009.

[supermuka]

Uff.. I was thinking that it was doing something wrong!

Using rpc 0.6.0 with sdk 2.1.0-dev.8.0 , in my code is thrown the following error:

Field members has wrong type: type 'List<dynamic>' is not a subtype of type 'List<UserBase>' of 'value'

With sdk 2.0.0 it works.

[jcollins-g]

@supermuka I suggest reverting to 2.1.0-dev.7.1 (that seems to still have the good behavior) if you need the 2.1 branch. Hopefully the referenced SDK bug is getting enough attention, I'll keep advocating for it. At the very least, if the rpc package itself is doing something wrong we need to know what it is so we can change it.

[jcollins-g]

Investigation in dart-lang/sdk#35009 revealed a way out for the rpc package: a refactor changing how the rpc package instantiates objects for clients to take into account their types with the mirror system. (A sample of some of the work required is in https://github.com/dart-lang/rpc/compare/experimental-mirrors-refactor).

[supermuka]

Just a thought, without depth: maybe it could be an alternative to make a refactory of the rpc package by changing the method for serialization, from mirror to code generated as a json_serialization (https://pub.dartlang.org/packages/json_serializable) does. I think we could have a performance improvement in runtime too.

[jcollins-g]

@supermuka It's certainly possible, though at that point I might look to a transition to grpc for my project (dart-services, the DartPad backend) rather than redesigning this package. grpc already uses generated code -- watching the rest of the dart ecosystem that seems to be the way folks are heading.

[jcollins-g]

@supermuka Just to let you know, we've decided to ship a version of rpc with a more complete fix for this, since the mirrors change is going to go into a future version of 2.1 stable. I'll try and get a PR set up for this in the next day or so and if you'd like I'd appreciate your feedback on it as a fellow customer of the package.

[supermuka]

@jcollins-g, I tested and it works fine now, including generic problem #134, using the branch experimental-mirrors-refactor and Dart version 2.1.1-dev.1.0.