Analyzer: More crashes on new "Function" syntax

[matanlurey]

Analyzer Feedback from IntelliJ

Version information

• IDEA IU-171.4694.70
• 2.0.0-dev.3.0
• IU-171.4694.70, JRE 1.8.0_112-release-736-b21x64 JetBrains s.r.o, OS Mac OS X(x86_64) v10.12.6 unknown, screens 3440x1440, 1080x1920

Dart analysis server, SDK version 2.0.0-dev.3.0, server version 1.18.4, error: Analysis failed: /.../lib/src/schema.dart context: exception_20171015_103716_986
NoSuchMethodError: The getter 'element' was called on null.
Receiver: null
Tried calling: element
#0      Object.noSuchMethod (dart:core-patch/object_patch.dart:44)
#1      TypeResolverVisitor.visitGenericFunctionType (package:analyzer/src/generated/resolver.dart:9678)
#2      GenericFunctionTypeImpl.accept (package:analyzer/src/dart/ast/ast.dart:5732)
#3      FieldFormalParameterImpl.visitChildren (package:analyzer/src/dart/ast/ast.dart:4513)
#4      UnifyingAstVisitor.visitNode (package:analyzer/dart/ast/visitor.dart:3121)
#5      TypeResolverVisitor.visitNode (package:analyzer/src/generated/resolver.dart:9839)
#6      UnifyingAstVisitor.visitFieldFormalParameter (package:analyzer/dart/ast/visitor.dart:3014)
#7      TypeResolverVisitor.visitFieldFormalParameter (package:analyzer/src/generated/resolver.dart:9608)
#8      FieldFormalParameterImpl.accept (package:analyzer/src/dart/ast/ast.dart:4508)
#9      DefaultFormalParameterImpl.visitChildren (package:analyzer/src/dart/ast/ast.dart:3469)
#10     UnifyingAstVisitor.visitNode (package:analyzer/dart/ast/visitor.dart:3121)
#11     TypeResolverVisitor.visitNode (package:analyzer/src/generated/resolver.dart:9839)
#12     UnifyingAstVisitor.visitDefaultFormalParameter (package:analyzer/dart/ast/visitor.dart:2974)

I have isolated the crash to this pattern:

class Schema<T> {
  final String name;

  final Map<String, Object> Function(T) decode;
  final T Function(Map<String, Object>) encode;

  const Schema({
    @required this.name,
    Map<String, Object> Function(T) this.decode,
    T Function(Map<String, Object>) this.encode,
  });
}

... or specifically, the initializing formals (this.*).

I can temporarily fix it by manually initializing the fields:

class Schema<T> {
  final String name;

  final Map<String, Object> Function(T) decode;
  final T Function(Map<String, Object>) encode;

  const Schema({
    @required this.name,
    Map<String, Object> Function(T) decode,
    T Function(Map<String, Object>) encode,
  // TODO: Use initializing formals after crashes stop:
  //
  // ignore: prefer_initializing_formals
  }) : decode = decode, encode = encode;
}

[lrhn]

As a side note, it's generally recommended to not write types on initializing formals. They automatically inherit the type of the field they initialize, even in Dart 1.

[matanlurey]

Sure, this was a mistake on my part, but the analyzer still shouldn't crash :)

[kevmoo]

Also crashes with Dart 2.0.0-dev.5.0

NoSuchMethodError: The getter 'element' was called on null.
Receiver: null
Tried calling: element
#0      Object.noSuchMethod (dart:core-patch/dart:core/object_patch.dart:46)
#1      TypeResolverVisitor.visitGenericFunctionType (package:analyzer/src/generated/resolver.dart:9700)
#2      GenericFunctionTypeImpl.accept (package:analyzer/src/dart/ast/ast.dart:5729)
#3      FieldFormalParameterImpl.visitChildren (package:analyzer/src/dart/ast/ast.dart:4516)
#4      UnifyingAstVisitor.visitNode (package:analyzer/dart/ast/visitor.dart:3121)
#5      TypeResolverVisitor.visitNode (package:analyzer/src/generated/resolver.dart:9861)
#6      UnifyingAstVisitor.visitFieldFormalParameter (package:analyzer/dart/ast/visitor.dart:3014)
#7      TypeResolverVisitor.visitFieldFormalParameter (package:analyzer/src/generated/resolver.dart:9630)
#8      FieldFormalParameterImpl.accept (package:analyzer/src/dart/ast/ast.dart:4511)
#9      DefaultFormalParameterImpl.visitChildren (package:analyzer/src/dart/ast/ast.dart:3469)
#10     UnifyingAstVisitor.visitNode (package:analyzer/dart/ast/visitor.dart:3121)
#11     TypeResolverVisitor.visitNode (package:analyzer/src/generated/resolver.dart:9861)
#12     UnifyingAstVisitor.visitDefaultFormalParameter (package:analyzer/dart/ast/visitor.dart:2974)
#13     DefaultFormalParameterImpl.accept (package:analyzer/src/dart/ast/ast.dart:3465)
#14     NodeListImpl.accept (package:analyzer/src/dart/ast/ast.dart:7987)
#15     FormalParameterListImpl.visitChildren (package:analyzer/src/dart/ast/ast.dart:4818)
#16     UnifyingAstVisitor.visitNode (package:analyzer/dart/ast/visitor.dart:3121)
#17     TypeResolverVisitor.visitNode (package:analyzer/src/generated/resolver.dart:9861)
#18     UnifyingAstVisitor.visitFormalParameterList (package:analyzer/dart/ast/visitor.dart:3020)
#19     ScopedVisitor.visitFormalParameterList (package:analyzer/src/generated/resolver.dart:7267)
#20     FormalParameterListImpl.accept (package:analyzer/src/dart/ast/ast.dart:4814)
#21     ScopedVisitor.visitConstructorDeclaration (package:analyzer/src/generated/resolver.dart:7153)
#22     TypeResolverVisitor.visitConstructorDeclaration (package:analyzer/src/generated/resolver.dart:9591)
#23     ConstructorDeclarationImpl.accept (package:analyzer/src/dart/ast/ast.dart:2967)
#24     TypeResolverVisitor.visitClassMembersInScope (package:analyzer/src/generated/resolver.dart:9568)
#25     ScopedVisitor.visitClassDeclaration (package:analyzer/src/generated/resolver.dart:7088)
#26     TypeResolverVisitor.visitClassDeclaration (package:analyzer/src/generated/resolver.dart:9509)
#27     ClassDeclarationImpl.accept (package:analyzer/src/dart/ast/ast.dart:1906)
#28     NodeListImpl.accept (package:analyzer/src/dart/ast/ast.dart:7987)
#29     CompilationUnitImpl.visitChildren (package:analyzer/src/dart/ast/ast.dart:2502)
#30     UnifyingAstVisitor.visitNode (package:analyzer/dart/ast/visitor.dart:3121)
#31     TypeResolverVisitor.visitNode (package:analyzer/src/generated/resolver.dart:9861)
#32     UnifyingAstVisitor.visitCompilationUnit (package:analyzer/dart/ast/visitor.dart:2949)
#33     CompilationUnitImpl.accept (package:analyzer/src/dart/ast/ast.dart:2495)
#34     LibraryAnalyzer._resolveFile (package:analyzer/src/dart/analysis/library_analyzer.dart:555)
#35     LibraryAnalyzer._analyze.<anonymous closure> (package:analyzer/src/dart/analysis/library_analyzer.dart:100)
#36     _HashVMBase&MapMixin&&_LinkedHashMapMixin.forEach (dart:collection-patch/dart:collection/compact_hash.dart:360)
#37     LibraryAnalyzer._analyze (package:analyzer/src/dart/analysis/library_analyzer.dart:99)
#38     LibraryAnalyzer.analyze.<anonymous closure> (package:analyzer/src/dart/analysis/library_analyzer.dart:75)
#39     _PerformanceTagImpl.makeCurrentWhile (package:analyzer/src/generated/utilities_general.dart:200)
#40     LibraryAnalyzer.analyze (package:analyzer/src/dart/analysis/library_analyzer.dart:74)
#41     AnalysisDriver._computeAnalysisResult.<anonymous closure> (package:analyzer/src/dart/analysis/driver.dart:1210)
<asynchronous suspension>
#42     PerformanceLog.runAsync (package:front_end/src/base/performace_logger.dart:52)
<asynchronous suspension>
#43     AnalysisDriver._computeAnalysisResult (package:analyzer/src/dart/analysis/driver.dart:1172)
<asynchronous suspension>
#44     AnalysisDriver.getErrors (package:analyzer/src/dart/analysis/driver.dart:617)
<asynchronous suspension>
#45     AnalyzerImpl.prepareErrors (package:analyzer_cli/src/analyzer_impl.dart:133)
<asynchronous suspension>
#46     AnalyzerImpl._analyze (package:analyzer_cli/src/analyzer_impl.dart:178)
<asynchronous suspension>
#47     AnalyzerImpl.analyze (package:analyzer_cli/src/analyzer_impl.dart:109)
<asynchronous suspension>
#48     Driver._runAnalyzer (package:analyzer_cli/src/driver.dart:778)
#49     Driver._analyzeAllImpl (package:analyzer_cli/src/driver.dart:328)
<asynchronous suspension>
#50     Driver._analyzeAll (package:analyzer_cli/src/driver.dart:226)
<asynchronous suspension>
#51     Driver.start (package:analyzer_cli/src/driver.dart:195)
<asynchronous suspension>
#52     main (file:///b/build/slave/dart-sdk-mac-dev/build/sdk/pkg/analyzer_cli/bin/analyzer.dart:13)
<asynchronous suspension>
#53     _startIsolate.<anonymous closure> (dart:isolate-patch/dart:isolate/isolate_patch.dart:275)
#54     _RawReceivePortImpl._handleMessage (dart:isolate-patch/dart:isolate/isolate_patch.dart:163)

#0      AnalysisDriver._computeAnalysisResult.<anonymous closure> (package:analyzer/src/dart/analysis/driver.dart:1250)
<asynchronous suspension>
#1      PerformanceLog.runAsync (package:front_end/src/base/performace_logger.dart:52)
<asynchronous suspension>
#2      AnalysisDriver._computeAnalysisResult (package:analyzer/src/dart/analysis/driver.dart:1172)
<asynchronous suspension>
#3      AnalysisDriver.getErrors (package:analyzer/src/dart/analysis/driver.dart:617)
<asynchronous suspension>
#4      AnalyzerImpl.prepareErrors (package:analyzer_cli/src/analyzer_impl.dart:133)
<asynchronous suspension>
#5      AnalyzerImpl._analyze (package:analyzer_cli/src/analyzer_impl.dart:178)
<asynchronous suspension>
#6      AnalyzerImpl.analyze (package:analyzer_cli/src/analyzer_impl.dart:109)
<asynchronous suspension>
#7      Driver._runAnalyzer (package:analyzer_cli/src/driver.dart:778)
#8      Driver._analyzeAllImpl (package:analyzer_cli/src/driver.dart:328)
<asynchronous suspension>
#9      Driver._analyzeAll (package:analyzer_cli/src/driver.dart:226)
<asynchronous suspension>
#10     Driver.start (package:analyzer_cli/src/driver.dart:195)
<asynchronous suspension>
#11     main (file:///b/build/slave/dart-sdk-mac-dev/build/sdk/pkg/analyzer_cli/bin/analyzer.dart:13)
<asynchronous suspension>
#12     _startIsolate.<anonymous closure> (dart:isolate-patch/dart:isolate/isolate_patch.dart:275)
#13     _RawReceivePortImpl._handleMessage (dart:isolate-patch/dart:isolate/isolate_patch.dart:163)