CFE crashes when compiling some code that has Future in it and that requires some inference

[chloestefantsova]

CFE crashes when it compiles the following code:

class Foo<T> {
  final Future<dynamic> Function() quux;
  T t;

  Foo(this.quux, this.t);

  Future<T> call() => quux().then<T>((_) => t);
}

class Bar {
  Foo<Baz> qux;

  Future<void> quuz() =>
      qux().then((baz) => corge(baz)).then((grault) => garply(grault));

  Grault corge(Baz baz) => null;

  void garply(Grault grault) {}
}

class Baz {}

class Grault {}

The top of the stack trace is the following:

Unhandled exception:                                                                                                                                                                                                                                                            
Crash when compiling file:///tmp/asdf.dart,                                                                                                                                                                                                                                     
at character offset 191:                                                                                                                                                                                                                                                        
dynamic is not a subtype of dart.async::Future in this.{#lib1::Bar::qux}()                                                                                                                                                                                                      
#0      TypeEnvironment.typeError (package:kernel/type_environment.dart:103:7)                                                                                                                                                                                                  
#1      Expression.getStaticTypeAsInstanceOf (package:kernel/ast.dart:2186:11)                                                                                                                                                                                                  
#2      MethodInvocation.getStaticType (package:kernel/ast.dart:2795:35)                                                                                                                                                                                                        
#3      KernelLibraryBuilder.checkBoundsInMethodInvocation (package:front_end/src/fasta/kernel/kernel_library_builder.dart:1831:36)                                                                                                                                             
#4      InferenceVistor.visitMethodInvocationJudgment (file:///usr/local/google/home/dmitryas/dart/sdk/pkg/front_end/lib/src/fasta/kernel/inference_visitor.dart:887:23)                                                                                                        
#5      MethodInvocationJudgment.acceptInference (package:front_end/src/fasta/kernel/kernel_shadow_ast.dart:1129:20)                                                                                                                                                            
#6      ShadowTypeInferrer.inferExpression (package:front_end/src/fasta/kernel/kernel_shadow_ast.dart:1631:18)                                                                                                                                                                  
#7      InferenceVistor.visitReturnJudgment (file:///usr/local/google/home/dmitryas/dart/sdk/pkg/front_end/lib/src/fasta/kernel/inference_visitor.dart:1024:16)                                                                                                                 
#8      ReturnJudgment.acceptInference (package:front_end/src/fasta/kernel/kernel_shadow_ast.dart:1302:20)                                                                                                                                                                      
#9      ShadowTypeInferrer.inferStatement (package:front_end/src/fasta/kernel/kernel_shadow_ast.dart:1679:24)                                                                                                                                                                   
#10     TypeInferrerImpl.inferFunctionBody (package:front_end/src/fasta/type_inference/type_inferrer.dart:1223:5)                                                                                                                                                               
#11     BodyBuilder.finishFunction (package:front_end/src/fasta/kernel/body_builder.dart:724:19)                                                                                                                                                                                
#12     DietListener.listenerFinishFunction (package:front_end/src/fasta/source/diet_listener.dart:795:14)                                                                                                                                                                      
#13     DietListener.buildFunctionBody (package:front_end/src/fasta/source/diet_listener.dart:829:7)                                                                                                                                                                            
#14     DietListener.endMethod (package:front_end/src/fasta/source/diet_listener.dart:578:5)                                                                                                                                                                                    
#15     Parser.parseMethod (package:front_end/src/fasta/parser/parser.dart:3030:14)                                                                                                                                                                                             
#16     Parser.parseClassOrMixinMemberImpl (package:front_end/src/fasta/parser/parser.dart:2895:15)                                                                                                                                                                             
#17     Parser.parseClassOrMixinBody (package:front_end/src/fasta/parser/parser.dart:2700:15)                                                                                                                                                                                   
#18     Parser.parseClass (package:front_end/src/fasta/parser/parser.dart:1710:13)                                                                                                                                                                                              
#19     Parser.parseClassOrNamedMixinApplication (package:front_end/src/fasta/parser/parser.dart:1670:14)                                                                                                                                                                       
#20     Parser.parseTopLevelKeywordDeclaration (package:front_end/src/fasta/parser/parser.dart:565:14)                                                                                                                                                                          
#21     Parser.parseTopLevelDeclarationImpl (package:front_end/src/fasta/parser/parser.dart:457:14)                                                                                                                                                                             
#22     Parser.parseUnit (package:front_end/src/fasta/parser/parser.dart:336:15)                                                                                                                                                                                                
#23     SourceLoader.buildBody (package:front_end/src/fasta/source/source_loader.dart:253:14)
...

[kmillikin]

One underlying problem with the existing implementation in terms of getStaticType is issue #34497.

Basically, for an invocation of a getter whose static type is a callable object (this.qux() in the test case) we generate MethodInvocation(This, 'qux', []) and we should generate MethodInvocation(PropertyGet(This, 'qux'), 'call', []). The former is not what we intend and the Kernel type checker says that it has type dynamic.

(This is inconsistent with what we do for static getters whose static type is a callable object, where we produce MethodInvocation(StaticGet(target), 'call', []); and for invoking a local variable whose static type is a callable object, where we produce MethodInvocation(VariableGet(definition), 'call', []).)

I've started work on #34497.

[kmillikin]

Work in progress on a fix is in https://dart-review.googlesource.com/c/sdk/+/81266