Hot reload does not work when changes include freezed models that embed a nullable realm model

[stevenosse]

What happened?

I've noticed that when i try to hot reload a page that contains a Realm model, the Dart compiler crashes and i have to run flutter clean to get it work again. This has occured several times, on both windows and macOS.
Other screens/files that does not import a realm model are not affected.

I've also created the associated issue on the Dart repo. Doing it here for tracking purpose: dart-lang/sdk#52312

Flutter doctor output:

Doctor summary (to see all details, run flutter doctor -v):
[√] Flutter (Channel stable, 3.7.12, on Microsoft Windows [version 10.0.22621.1555], locale fr-FR)
[X] Windows Version (Unable to confirm if installed Windows version is 10 or greater)
[√] Android toolchain - develop for Android devices (Android SDK version 33.0.2)
[√] Chrome - develop for the web
[√] Visual Studio - develop for Windows (Visual Studio Community 2022 17.1.0)
[√] Android Studio (version 2022.2)
[√] IntelliJ IDEA Community Edition (version 2022.3)
[√] VS Code (version 1.78.0)
[√] Connected device (3 available)
[√] HTTP Host Availability

! Doctor found issues in 1 category.

Repro steps

1. Create a blank flutter project
2. Import a realm model on any file
3. Try to run hot reload from that file
4. Boom : Crash

Version

1.0.3

What Atlas Services are you using?

Local Database only

What type of application is this?

Flutter Application

Client OS and version

Pixel 7 Pro - Android 13, Xiaomi Mi 10T Pro - Android 11

Code snippets

No response

Stacktrace of the exception/crash you're getting

Unhandled exception:
Crash when compiling:
type 'Block' is not a subtype of type 'ReturnStatement' in type cast

#0      RedirectingFactoryBody.restoreFromDill (package:front_end/src/fasta/kernel/redirecting_factory_body.dart:121:39)
#1      DillLibraryBuilder._addClass (package:front_end/src/fasta/dill/dill_library_builder.dart:202:34)
#2      List.forEach (dart:core-patch/growable_array.dart)
#3      DillLibraryBuilder.ensureLoaded (package:front_end/src/fasta/dill/dill_library_builder.dart:108:21)
#4      LazyLibraryScope.ensureScope (package:front_end/src/fasta/dill/dill_library_builder.dart:57:21)

#5      LazyScope._local (package:front_end/src/fasta/scope.dart:722:5)
#6      new ScopeNameIterator (package:front_end/src/fasta/scope.dart:1017:28)
#7      Scope.unfilteredNameIterator (package:front_end/src/fasta/scope.dart:146:16)
#8      Scope.filteredNameIterator (package:front_end/src/fasta/scope.dart:182:40)
#9      Import.finalizeImports (package:front_end/src/fasta/import.dart:78:60)
#10     SourceLibraryBuilder.addImportsToScope (package:front_end/src/fasta/source/source_library_builder.dart:1423:14)
#11     SourceLoader.computeLibraryScopes (package:front_end/src/fasta/source/source_loader.dart:1471:23)
#12     KernelTarget.buildOutlines.<anonymous closure> (package:front_end/src/fasta/kernel/kernel_target.dart:423:14)
#13     withCrashReporting (package:front_end/src/fasta/crash.dart:136:24)
#14     KernelTarget.buildOutlines (package:front_end/src/fasta/kernel/kernel_target.dart:406:12)
#15     IncrementalCompiler.computeDelta.<anonymous closure> (package:front_end/src/fasta/incremental_compiler.dart:408:59)
<asynchronous suspension>
#16     IncrementalCompiler.compile (package:vm/incremental_compiler.dart:68:50)
<asynchronous suspension>
#17     FrontendCompiler.recompileDelta (package:frontend_server/frontend_server.dart:847:52)
<asynchronous suspension>

the Dart compiler exited unexpectedly.
the Dart compiler exited unexpectedly.
Exited (1)

Relevant log output

No response

[nielsenko]

@stevenosse It has been a while since I have seen a compiler crash. Last time was regarding the Finalizable interface dart-lang/sdk#49075.

Trying to follow your repro steps I must admit I cannot reproduce the issue. This is what I did

flutter create bomb
cd bomb
flutter pub add realm
flutter pub run realm install
flutter pub run realm generate --watch

Start vscode and edit main.dart to:

import 'package:flutter/material.dart';
import 'package:realm/realm.dart';

part 'main.g.dart';

@RealmModel()
class _Stuff {
  late int first;
}

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return const Placeholder();
  }
}

Run this on (I used the iPhone 14 Pro Max simulator).

Make a change - I replaced const Placeholder() with Container(color: Colors.red) - then hot-reload.. but it worked fine - no boom.

I tried more elaborate changes, like changing the actual realm model class _Stuff, or actually using it in the code, but I still cannot reproduce your issue.

Can you elaborate more on the exact steps you use? And perhaps a full project?

I tried both flutter 3.17.12 (current stable) and 3.11.0-2.0.pre.73 (current master).

[stevenosse]

Hello @nielsenko
Thanks for the quick reply.
I've investigated more on the issue. And I apologize, I should have dug deeper before creating the issue
I've tried to isolate the problem and it seems to occur when a nullable Realm Model is used in a freezed object

This breaks the compiler:

part 'dummy_state.freezed.dart';

@freezed
class DummyState with _$DummyState {
  factory DummyState({
    required Dummy item,
    RealmModel? storedItem,
  }) = _Initial;
}

To check this hypothesis, I redid the same one without freezed and the hot reload works again.

I continue the investigation.
Everything seems to work fine when the realm model is used in freezed like:

• List type (eg. List<RealmModel>)
• Non null attribute

[stevenosse]

Answer from the Dart team: dart-lang/sdk#52312 (comment)

[nielsenko]

This should be fixed with Flutter 3.10.1 (see flutter/flutter#124369 and https://github.com/flutter/flutter/wiki/Hotfixes-to-the-Stable-Channel#3101-may-17-2023)