Migration: Expressions in annotations don't get control flow instance, cause NPE

[MichaelRFairhurst]

class Foo {                                                                      
  const Foo(bool x);                                                             
}                                                                                
                                                                                 
@Foo(true)                                                                       
int x;

Boolean literals can affect control flow, so EdgeBuilder tries to inform control flow about this true literal, but we have not created an instance of control flow, so it crashes.

The solution is to create control flow for annotation expressions.

NoSuchMethodError: The method 'booleanLiteral' was called on null.
Receiver: null
Tried calling: booleanLiteral(Instance of 'BooleanLiteralImpl', true)

#0      Object.noSuchMethod (dart:core-patch/object_patch.dart:51:5)
#1      EdgeBuilder.visitBooleanLiteral (package:nnbd_migration/src/edge_builder.dart:474:19)
#2      BooleanLiteralImpl.accept (package:analyzer/src/dart/ast/ast.dart:1116:49)
#3      EdgeBuilder._dispatch (package:nnbd_migration/src/edge_builder.dart:2038:22)
#4      EdgeBuilder.visitNode (package:nnbd_migration/src/edge_builder.dart:1198:9)
#5      GeneralizingAstVisitor.visitArgumentList (package:analyzer/dart/ast/visitor.dart:140:45)
#6      ArgumentListImpl.accept (package:analyzer/src/dart/ast/ast.dart:359:49)
#7      EdgeBuilder._dispatch (package:nnbd_migration/src/edge_builder.dart:2038:22)
#8      EdgeBuilder.visitNode (package:nnbd_migration/src/edge_builder.dart:1198:9)
#9      GeneralizingAstVisitor.visitAnnotation (package:analyzer/dart/ast/visitor.dart:137:41)
#10     CompletenessTracker.visitAnnotation (package:nnbd_migration/src/utilities/completeness_tracker.dart:26:18)
#11     AnnotationImpl.accept (package:analyzer/src/dart/ast/ast.dart:284:49)
#12     EdgeBuilder._dispatch (package:nnbd_migration/src/edge_builder.dart:2038:22)
#13     EdgeBuilder.visitNode (package:nnbd_migration/src/edge_builder.dart:1198:9)
#14     GeneralizingAstVisitor.visitAnnotatedNode (package:analyzer/dart/ast/visitor.dart:134:47)
#15     GeneralizingAstVisitor.visitDeclaration (package:analyzer/dart/ast/visitor.dart:227:43)
#16     GeneralizingAstVisitor.visitCompilationUnitMember (package:analyzer/dart/ast/visitor.dart:202:7)
#17     GeneralizingAstVisitor.visitTopLevelVariableDeclaration (package:analyzer/dart/ast/visitor.dart:551:7)
#18     TopLevelVariableDeclarationImpl.accept (package:analyzer/src/dart/ast/ast.dart:9866:15)
#19     EdgeBuilder._dispatch (package:nnbd_migration/src/edge_builder.dart:2038:22)
#20     EdgeBuilder.visitNode (package:nnbd_migration/src/edge_builder.dart:1198:9)
#21     GeneralizingAstVisitor.visitCompilationUnit (package:analyzer/dart/ast/visitor.dart:199:51)
#22     CompletenessTracker.visitCompilationUnit.<anonymous closure> (package:nnbd_migration/src/utilities/completeness_tracker.dart:48:24)
#23     PermissiveModeVisitor.reportExceptionsIfPermissive (package:nnbd_migration/src/utilities/permissive_mode.dart:26:24)
#24     CompletenessTracker.visitCompilationUnit (package:nnbd_migration/src/utilities/completeness_tracker.dart:39:5)
#25     CompilationUnitImpl.accept (package:analyzer/src/dart/ast/ast.dart:2125:49)
#26     NullabilityMigrationImpl.processInput (package:nnbd_migration/src/nullability_migration_impl.dart:191:12)
#27     NonNullableFix.processUnit (package:nnbd_migration/src/front_end/non_nullable_fix.dart:150:19)
#28     _FixCodeProcessor.runLaterPhases.<anonymous closure> (package:nnbd_migration/migration_cli.dart:923:21)
#29     _FixCodeProcessor.processResources (package:nnbd_migration/migration_cli.dart:869:30)
<asynchronous suspension>
#30     _FixCodeProcessor.runLaterPhases (package:nnbd_migration/migration_cli.dart:921:13)
#31     MigrationCli.run.<anonymous closure> (package:nnbd_migration/migration_cli.dart:445:45)
<asynchronous suspension>
#32     MigrationCli.run.<anonymous closure> (package:nnbd_migration/migration_cli.dart)
#33     MigrationCli._withProgress (package:nnbd_migration/migration_cli.dart:709:21)
#34     MigrationCli.run (package:nnbd_migration/migration_cli.dart:420:11)
#35     main (file:///home/mfairhurst/projects/dart/sdk/pkg/nnbd_migration/bin/migrate.dart:18:39)
#36     _startIsolate.<anonymous closure> (dart:isolate-patch/isolate_patch.dart:299:32)
#37     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:168:12)

[hillelcoren]

We're seeing this error as well

[vsmenon]

@kevmoo @mit-mit - do you know why the dart-bot closed this on us?

[srawlins]

@vsmenon didn't the bot close this because I landed a fix in b907f99 ?

[vsmenon]

Ahh, sorry. I missed that! Thanks @srawlins . @hillelcoren - please open a new issue if you're still seeing the bug. See

b907f99

for what branches the fix is in.

[hillelcoren]

Thanks for the info, sorry for the confusion!