[CP][stable?] Prevent dart2js crash on flutter web code using package:freezed

[sigmundch]

commit(s) to merge: 5090974

merge instructions: needs special cherry-pick CL, but I'd like to discuss first whether we'd approve this hotfix before we create it. It merges cleanly on the beta channel, but not on stable due to some refactoring that occurred in between.

What is the issue: a broken invariant in the kernel representation when there are multiple redirecting factories, this can cause crashes in dart2js downstream.

What is the fix: CFE was updated to fix this invariant by picking the effective target and not the direct target of redirecting calls.

Why cherrypick: The pattern that triggers this bug is commonly generated by package:freezed, a very popular package in the flutter ecosystem. The broken representation silently works in DDC and the VM, but triggers a crash in dart2js for flutter web users.

Risk: low - fix is fairly localized, has been rolled internally.

Link to original issue(s): #47916 (multiple reports merged here, 69+ votes). This is related to flutter/flutter#100038 (a hotfix request on flutter).

/cc @mit-mit @whesse @athomas @vsmenon @devoncarew @johnniwinther

[mit-mit]

cc @kevmoo for input on customer priority

[athomas]

Not included in the beta, so we also want to merge this to beta if approved.

/cc @itsjustkevin

[sigmundch]

At our discussion we decided to proceed with including this in beta going forward, but to wait on the stable channel based on whether current users are in the beta/main channel or not.

For beta, it should be a clean merge.

[sigmundch]

I talked offline with @kevmoo and we agreed we'd like to create a cherry-pick for this on both stable and beta.

[johnniwinther]

CL for merging into stable: https://dart-review.googlesource.com/c/sdk/+/238041

[athomas]

@itsjustkevin I'm considering this one as approved for both stable and beta based on the offline conversation yesterday.

[whesse]

This CP has landed in 2.16.2 stable.

[sigmundch]

thank you @whesse and @athomas !

[long1eu]

How much to we usually need to wait for this to land in Dart and then in Flutter?

[athomas]

Dart and Flutter releases get released on the same day. In this case that's planned for tomorrow.

[long1eu]

It landed in Dart but not Flutter

[athomas]

@itsjustkevin Did the Flutter release not go out?

[long1eu]

Not on stable or on beta

[sigmundch]

It appears there was a delay from the flutter side, but just checked this morning again and the release is out in 2.10.4 🎉

[mirland]

I tested and it fixed my issue! so I think we can close the issue. Thanks for the hard work 💪