dart migrate exception: A decorated type for the bound of T should have been stored by the NodeBuilder

[kluverua]

Dart SDK version: 2.12.2 (stable) (Wed Mar 17 10:30:20 2021 +0100) on "windows_x64"

Got this error while migrating my project using the dart migrate utility:
My class: approvals_bloc.dart

No analysis issues found.

Generating migration suggestions...
[----  ]
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:

Bad state: A decorated type for the bound of T should have been stored by the NodeBuilder via recordTypeParameterBound 
at offset 2223 in C:\app\lib\blocs\approval\approvals_bloc.dart (..onItemsImported = _onItemsImported)

#0      Variables.decoratedTypeParameterBound (package:nnbd_migration/src/variables.dart:138:9)
#1      EdgeBuilder._getTypeParameterTypeBound (package:nnbd_migration/src/edge_builder.dart:2258:10)
#2      _AssignmentChecker._checkAssignment_recursion (package:nnbd_migration/src/edge_builder.dart:3470:21)
#3      _AssignmentChecker._checkAssignment (package:nnbd_migration/src/edge_builder.dart:3373:5)
#4      _AssignmentChecker._checkAssignment_recursion (package:nnbd_migration/src/edge_builder.dart:3488:9)
#5      _AssignmentChecker._checkAssignment (package:nnbd_migration/src/edge_builder.dart:3373:5)
#6      _AssignmentChecker._checkAssignment_recursion (package:nnbd_migration/src/edge_builder.dart:3513:9)
#7      _AssignmentChecker._checkAssignment (package:nnbd_migration/src/edge_builder.dart:3373:5)
#8      EdgeBuilder._handleAssignment (package:nnbd_migration/src/edge_builder.dart:2398:11)
#9      EdgeBuilder.visitAssignmentExpression (package:nnbd_migration/src/edge_builder.dart:409:26)
#10     AssignmentExpressionImpl.accept (package:analyzer/src/dart/ast/ast.dart:715:49)
#11     EdgeBuilder._dispatch (package:nnbd_migration/src/edge_builder.dart:2207:24)
#12     EdgeBuilder._dispatchList (package:nnbd_migration/src/edge_builder.dart:2229:7)
#13     EdgeBuilder.visitCascadeExpression (package:nnbd_migration/src/edge_builder.dart:552:7)
#14     CascadeExpressionImpl.accept (package:analyzer/src/dart/ast/ast.dart:1253:49)
#15     EdgeBuilder._dispatch (package:nnbd_migration/src/edge_builder.dart:2207:24)
#16     EdgeBuilder.visitExpressionStatement (package:nnbd_migration/src/edge_builder.dart:801:25)
#17     ExpressionStatementImpl.accept (package:analyzer/src/dart/ast/ast.dart:3676:49)
#18     EdgeBuilder._dispatch (package:nnbd_migration/src/edge_builder.dart:2207:24)
#19     EdgeBuilder.visitNode (package:nnbd_migration/src/edge_builder.dart:1340:9)
#20     GeneralizingAstVisitor.visitStatement (package:analyzer/dart/ast/visitor.dart:517:39)
#21     GeneralizingAstVisitor.visitBlock (package:analyzer/dart/ast/visitor.dart:165:31)
#22     BlockImpl.accept (package:analyzer/src/dart/ast/ast.dart:1083:49)
#23     EdgeBuilder._dispatch (package:nnbd_migration/src/edge_builder.dart:2207:24)
#24     EdgeBuilder.visitNode (package:nnbd_migration/src/edge_builder.dart:1340:9)
#25     GeneralizingAstVisitor.visitFunctionBody (package:analyzer/dart/ast/visitor.dart:324:45)
#26     GeneralizingAstVisitor.visitBlockFunctionBody (package:analyzer/dart/ast/visitor.dart:168:55)
#27     BlockFunctionBodyImpl.accept (package:analyzer/src/dart/ast/ast.dart:1038:49)
#28     EdgeBuilder._dispatch (package:nnbd_migration/src/edge_builder.dart:2207:24)
#29     EdgeBuilder._handleExecutableDeclaration (package:nnbd_migration/src/edge_builder.dart:2488:7)
#30     EdgeBuilder.visitConstructorDeclaration (package:nnbd_migration/src/edge_builder.dart:712:5)
#31     ConstructorDeclarationImpl.accept (package:analyzer/src/dart/ast/ast.dart:2566:15)
#32     EdgeBuilder._dispatch (package:nnbd_migration/src/edge_builder.dart:2207:24)
#33     EdgeBuilder._dispatchList (package:nnbd_migration/src/edge_builder.dart:2229:7)
#34     EdgeBuilder.visitClassOrMixinOrExtensionDeclaration (package:nnbd_migration/src/edge_builder.dart:607:7)
#35     EdgeBuilder.visitClassDeclaration (package:nnbd_migration/src/edge_builder.dart:574:5)
#36     ClassDeclarationImpl.accept (package:analyzer/src/dart/ast/ast.dart:1536:49)
#37     EdgeBuilder._dispatch (package:nnbd_migration/src/edge_builder.dart:2207:24)
#38     EdgeBuilder.visitNode (package:nnbd_migration/src/edge_builder.dart:1340:9)
#39     GeneralizingAstVisitor.visitCompilationUnit (package:analyzer/dart/ast/visitor.dart:202:51)
#40     CompletenessTracker.visitCompilationUnit.<anonymous closure> (package:nnbd_migration/src/utilities/completeness_tracker.dart:52:24)
#41     PermissiveModeVisitor.reportExceptionsIfPermissive (package:nnbd_migration/src/utilities/permissive_mode.dart:26:24)
#42     CompletenessTracker.visitCompilationUnit (package:nnbd_migration/src/utilities/completeness_tracker.dart:43:5)
#43     CompilationUnitImpl.accept (package:analyzer/src/dart/ast/ast.dart:2134:49)
#44     NullabilityMigrationImpl.processInput (package:nnbd_migration/src/nullability_migration_impl.dart:244:12)
#45     NonNullableFix.processUnit (package:nnbd_migration/src/front_end/non_nullable_fix.dart:164:15)
#46     _FixCodeProcessor.runLaterPhases.<anonymous closure> (package:nnbd_migration/migration_cli.dart:1154:19)
#47     _FixCodeProcessor.runLaterPhases.<anonymous closure> (package:nnbd_migration/migration_cli.dart:1152:28)
#48     _FixCodeProcessor.processResources (package:nnbd_migration/migration_cli.dart:1081:30)
<asynchronous suspension>
#49     _FixCodeProcessor.runLaterPhases (package:nnbd_migration/migration_cli.dart:1152:5)
<asynchronous suspension>
#50     MigrationCliRunner.run (package:nnbd_migration/migration_cli.dart:749:24)
<asynchronous suspension>
#51     MigrateCommand.run (package:nnbd_migration/migration_cli.dart:185:7)
<asynchronous suspension>
#52     CommandRunner.runCommand (package:args/command_runner.dart:196:13)
<asynchronous suspension>
#53     DartdevRunner.runCommand (package:dartdev/dartdev.dart:199:18)
<asynchronous suspension>
#54     runDartdev (package:dartdev/dartdev.dart:53:16)
<asynchronous suspension>
#55     main (file:///C:/b/s/w/ir/cache/builder/src/third_party/dart/pkg/dartdev/bin/dartdev.dart:11:3)
<asynchronous suspension>

I think the error is in this method:

  // ignore: always_specify_types
  void _onItemsImported<ApprovalModel>(List items) {
    syncIndicatorBloc?.add(SyncFinished(SyncType.import));
    add(UpdateApprovalsFromCache(items));
  }

A long time ago there was another error in this method:
The argument type 'List<ApprovalModel>' can't be assigned to the parameter type 'List<ApprovalModel>'.
I solve it with workaround:

void _onItemsImported<ApprovalModel>(List<ApprovalModel> items) {

//replace with ====>

// ignore: always_specify_types
void _onItemsImported<ApprovalModel>(List items) {

Here is UpdateApprovalsFromCache class:

/// Event for obtaining approvals.
class UpdateApprovalsFromCache extends ApprovalEvent {
  /// Approvals.
  List<ApprovalModel> approvals;

  /// Creates instance.
  UpdateApprovalsFromCache(this.approvals);
}

[stereotype441]

@kluverua thanks for the bug report! Were you able to make progress by rerunning migration with --ignore-exceptions?

[kluverua]

Doh, forgot to mention that. Yes, it is over.
It converts my method to this:

// ignore: always_specify_types
  void _onItemsImported<ApprovalModel>(List items) {
    syncIndicatorBloc?.add(SyncFinished(SyncType.import));
    add(UpdateApprovalsFromCache(items as List<ApprovalModel>));
  }

And i get error:
The argument type 'List<ApprovalModel>' can't be assigned to the parameter type 'List<ApprovalModel>'.
And now I can't find a workaround for this in any way :(

Btw, here is UpdateApprovalsFromCache class in its entirety:
approval_event.dart

[kluverua]

Now I think the error is not related to dart migration.
Should i write this error in this issue #32042 ?
Or create new issue?

[kluverua]

Here is fix:

..onItemsImported = _onItemsImported
...
void _onItemsImported<T>(List<T> items) {
  syncIndicatorBloc?.add(SyncFinished(SyncType.import));
  add(UpdateApprovalsFromCache(items as List<ApprovalModel>));
}

[stereotype441]

Hi @kluverua, thanks for all the information. I'm glad you were able to make progress with your migratoin! Unfortunately I haven't managed to reproduce the failure from the information you provided.

Do you think you understand what happened well enough that you could write a short isolated program that demonstrates it? (In other words, a short program that doesn't depend on any of your code but still fails to migrate in the same way. The program wouldn't have to do anything useful other than provoke the bug). If you could manage to do that, I would be happy to try to debug further.

[kluverua]

Ok, if you really want it :)

typedef RepositoryItemsImported = void Function<T>(List<T> items);

abstract class Class1<T> {
  RepositoryItemsImported onItemsImported;
}

class Class2 extends Class1<String> {
  Class2() {
    onItemsImported = _onItemsImported;
  }

  void add(List<String> e) {
  }

  void _onItemsImported<String>(List items) {
    add(items);
  }
}

p.s. you can even delete type RepositoryItemsImported and get same error

[stereotype441]

@kluverua awesome, thank you! That reproduces the bug for me :)

[stereotype441]

As of 1c7fe71, the null safety migration tool has been removed from active development and retired. No further work on the tool is planned.

If you still need help, or you believe this issue has been closed in error, please feel free to reopen.