Migration Exception "LUB/GLB with unexpected types: DynamicTypeImpl/InterfaceTypeImpl"

[nipunasudha]

Description

I am using RxDart (v0.26.0) ValueStreamExtensions.value getter extension. Here is the extension definition in the library.

// rxdart-0.26.0/lib/src/streams/value_stream.dart
extension ValueStreamExtensions<T> on ValueStream<T> {
  /// Returns last emitted value, or null if there has been no emission yet.
  T? get value => valueWrapper?.value;
}

Here is how I use it in one of my methods.

import 'package:rxdart/rxdart.dart';

class DefaultFileUploader {
  final BehaviorSubject<List<UploadHandler>> handlersStream =
      BehaviorSubject<List<UploadHandler>>.seeded([]);

  void forceUpdateHandlerStream() {
    final List<UploadHandler> currentHandlers = handlersStream.value ?? []; /// error line
    handlersStream.add(currentHandlers);
  }
}

Error Occurred

When I run dart migrate the following error occurs. My personal guess is the migrate tool is not configured to handle extension method getter with a ?? null check operator.

Aborting migration due to an exception. This most likely is due to a
bug in the migration tool. Please consider filing a bug report at:

https://github.com/dart-lang/sdk/issues/new
Please include the SDK version (2.12.2) in your bug report.

To attempt to perform migration anyway, you may re-run with
--ignore-exceptions.

Exception details:

UnimplementedError: LUB/GLB with unexpected types: DynamicTypeImpl/InterfaceTypeImpl in "handlersStream.value ?? []" on line 53 of "/home/nipuna/panda/flutter_projects/project-manager/lib/managers/upload_manager/definitions/default_file_uploader.dart" at offset 1777 in /home/nipuna/panda/flutter_projects/project-manager/lib/managers/upload_manager/definitions/default_file_uploader.dart (handlersStream.value ?? [])

#0 EdgeBuilder._unimplemented (package:nnbd_migration/src/edge_builder.dart:3253:5)
#1 EdgeBuilder._decorateUpperOrLowerBound (package:nnbd_migration/src/edge_builder.dart:2129:11)
#2 EdgeBuilder._decorateUpperOrLowerBound (package:nnbd_migration/src/edge_builder.dart:2058:14)
#3 EdgeBuilder.visitBinaryExpression (package:nnbd_migration/src/edge_builder.dart:495:26)
#4 BinaryExpressionImpl.accept (package:analyzer/src/dart/ast/ast.dart:967:49)
#5 EdgeBuilder._dispatch (package:nnbd_migration/src/edge_builder.dart:2207:24)
#6 EdgeBuilder._handleAssignment (package:nnbd_migration/src/edge_builder.dart:2329:20)
#7 EdgeBuilder.visitVariableDeclarationList (package:nnbd_migration/src/edge_builder.dart:1924:11)
#8 VariableDeclarationListImpl.accept (package:analyzer/src/dart/ast/ast.dart:10655:15)
#9 EdgeBuilder._dispatch (package:nnbd_migration/src/edge_builder.dart:2207:24)
#10 EdgeBuilder.visitNode (package:nnbd_migration/src/edge_builder.dart:1340:9)
#11 GeneralizingAstVisitor.visitStatement (package:analyzer/dart/ast/visitor.dart:517:39)
#12 GeneralizingAstVisitor.visitVariableDeclarationStatement (package:analyzer/dart/ast/visitor.dart:589:7)
#13 VariableDeclarationStatementImpl.accept (package:analyzer/src/dart/ast/ast.dart:10705:15)
#14 EdgeBuilder._dispatch (package:nnbd_migration/src/edge_builder.dart:2207:24)
#15 EdgeBuilder.visitNode (package:nnbd_migration/src/edge_builder.dart:1340:9)
#16 GeneralizingAstVisitor.visitStatement (package:analyzer/dart/ast/visitor.dart:517:39)
#17 GeneralizingAstVisitor.visitBlock (package:analyzer/dart/ast/visitor.dart:165:31)
#18 BlockImpl.accept (package:analyzer/src/dart/ast/ast.dart:1083:49)
#19 EdgeBuilder._dispatch (package:nnbd_migration/src/edge_builder.dart:2207:24)
#20 EdgeBuilder.visitNode (package:nnbd_migration/src/edge_builder.dart:1340:9)
#21 GeneralizingAstVisitor.visitFunctionBody (package:analyzer/dart/ast/visitor.dart:324:45)
#22 GeneralizingAstVisitor.visitBlockFunctionBody (package:analyzer/dart/ast/visitor.dart:168:55)
#23 BlockFunctionBodyImpl.accept (package:analyzer/src/dart/ast/ast.dart:1038:49)
#24 EdgeBuilder._dispatch (package:nnbd_migration/src/edge_builder.dart:2207:24)
#25 EdgeBuilder._handleExecutableDeclaration (package:nnbd_migration/src/edge_builder.dart:2488:7)
#26 EdgeBuilder.visitMethodDeclaration (package:nnbd_migration/src/edge_builder.dart:1243:5)
#27 MethodDeclarationImpl.accept (package:analyzer/src/dart/ast/ast.dart:7033:49)
#28 EdgeBuilder._dispatch (package:nnbd_migration/src/edge_builder.dart:2207:24)
#29 EdgeBuilder._dispatchList (package:nnbd_migration/src/edge_builder.dart:2229:7)
#30 EdgeBuilder.visitClassOrMixinOrExtensionDeclaration (package:nnbd_migration/src/edge_builder.dart:607:7)
#31 EdgeBuilder.visitClassDeclaration (package:nnbd_migration/src/edge_builder.dart:574:5)
#32 ClassDeclarationImpl.accept (package:analyzer/src/dart/ast/ast.dart:1536:49)
#33 EdgeBuilder._dispatch (package:nnbd_migration/src/edge_builder.dart:2207:24)
#34 EdgeBuilder.visitNode (package:nnbd_migration/src/edge_builder.dart:1340:9)
#35 GeneralizingAstVisitor.visitCompilationUnit (package:analyzer/dart/ast/visitor.dart:202:51)
#36 CompletenessTracker.visitCompilationUnit. (package:nnbd_migration/src/utilities/completeness_tracker.dart:52:24)
#37 PermissiveModeVisitor.reportExceptionsIfPermissive (package:nnbd_migration/src/utilities/permissive_mode.dart:26:24)
#38 CompletenessTracker.visitCompilationUnit (package:nnbd_migration/src/utilities/completeness_tracker.dart:43:5)
#39 CompilationUnitImpl.accept (package:analyzer/src/dart/ast/ast.dart:2134:49)
#40 NullabilityMigrationImpl.processInput (package:nnbd_migration/src/nullability_migration_impl.dart:244:12)
#41 NonNullableFix.processUnit (package:nnbd_migration/src/front_end/non_nullable_fix.dart:164:15)
#42 _FixCodeProcessor.runLaterPhases. (package:nnbd_migration/migration_cli.dart:1154:19)
#43 _FixCodeProcessor.runLaterPhases. (package:nnbd_migration/migration_cli.dart:1152:28)
#44 _FixCodeProcessor.processResources (package:nnbd_migration/migration_cli.dart:1081:30)
#45 _FixCodeProcessor.runLaterPhases (package:nnbd_migration/migration_cli.dart:1152:5)
#46 MigrationCliRunner.run (package:nnbd_migration/migration_cli.dart:749:24)
#47 MigrateCommand.run (package:nnbd_migration/migration_cli.dart:185:7)
#48 CommandRunner.runCommand (package:args/command_runner.dart:196:13)
#49 DartdevRunner.runCommand (package:dartdev/dartdev.dart:199:18)
#50 runDartdev (package:dartdev/dartdev.dart:53:16)
#51 main (file:///tmp/tmpTqI70l/dart-2.12.2/dart/pkg/dartdev/bin/dartdev.dart:11:3)

System Information

Here's my Flutter doctor output:

[✓] Flutter (Channel unknown, 2.0.3, on Linux, locale en_US.UTF-8)
• Flutter version 2.0.3 at /home/nipuna/fvm/versions/2.0.3
• Framework revision 4d7946a68d (2 weeks ago), 2021-03-18 17:24:33 -0700
• Engine revision 3459eb2436
• Dart version 2.12.2

[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.2)
• Android SDK at /home/nipuna/Android/Sdk
• Platform android-30, build-tools 30.0.2
• ANDROID_HOME = /home/nipuna/Android/Sdk
• Java binary at: /home/nipuna/.local/share/JetBrains/Toolbox/apps/AndroidStudio/ch-0/193.6626763/jre/bin/java
• Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6222593)
• All Android licenses accepted.

[✓] Chrome - develop for the web
• CHROME_EXECUTABLE = /usr/bin/google-chrome-stable

[✓] Android Studio (version 4.0)
• Android Studio at /home/nipuna/.local/share/JetBrains/Toolbox/apps/AndroidStudio/ch-0/193.6626763
• Flutter plugin can be installed from:
🔨 https://plugins.jetbrains.com/plugin/9212-flutter
• Dart plugin can be installed from:
🔨 https://plugins.jetbrains.com/plugin/6351-dart
• Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6222593)

[✓] IntelliJ IDEA Ultimate Edition (version 2020.3)
• IntelliJ at /home/nipuna/.local/share/JetBrains/Toolbox/apps/IDEA-U/ch-0/203.6682.168
• Flutter plugin version 55.0.3
• Dart plugin version 203.7759

[✓] IntelliJ IDEA Ultimate Edition (version 2020.2)
• IntelliJ at /home/nipuna/.local/share/JetBrains/Toolbox/apps/IDEA-U/ch-0/202.8194.7
• Flutter plugin version 51.0.3
• Dart plugin version 202.7319.5

[✓] Connected device (2 available)
• Android SDK built for x86 (mobile) • emulator-5554 • android-x86 • Android 6.0 (API 23) (emulator)
• Chrome (web) • chrome • web-javascript • Google Chrome 88.0.4324.150

• No issues found!

I will post more information if required, please ask :)

[stereotype441]

@nipunasudha thanks for the detailed information! I believe this is enough information that I will be able to reproduce and fix the bug.

Were you able make progress by re-running migration with --ignore-exceptions?

[nipunasudha]

Migration tool runs successfully with no errors when I use --ignore-exceptions. Migration is applied successfully, with no changes to the line with the ?? operator.