F bounded quantification bug

[jmesserly]

from @vsmenon, moved from dart-archive/dev_compiler#357

From f_bounded_quantification2_test.dart:

class Entities<T extends ConceptEntity<T>> implements EntitiesApi<T> { }

class ConceptEntity<T extends ConceptEntity<T>> implements EntityApi { }

abstract class EntityApi<T extends EntityApi<T>> { }

abstract class EntitiesApi<T extends EntityApi<T>> { }

class Concept extends ConceptEntity<Concept> { }

main() {
  new ConceptEntity<Concept>();
  new ConceptEntity<ConceptEntity>();
}

is triggering the following errors - newly in the task model strong mode:

severe: [AnalyzerMessage] 'T' does not extend 'EntityApi<T>' (test/codegen/language/f_bounded_quantification2_test.dart, line 7, col 67)
severe: [AnalyzerMessage] 'ConceptEntity' does not extend 'ConceptEntity<ConceptEntity>' (test/codegen/language/f_bounded_quantification2_test.dart, line 19, col 21)

This particular test isn't strictly blocking - we don't support this pattern yet in codegen, but it is a regression.

[Andersmholmgren]

I believe this is the issue I'm hitting now. I've spent the last day or so moving projects to strong mode, adding generic method parameters and getting rid of analyser warnings.

But when I go to run the unit tests pretty much everything blows up now like

  'package:frentity/src/model/entity/state.dart': malbounded type: line 12 pos 31: type parameter 'S' of class 'ComponentState' must extend bound 'ComponentState<S>', but type argument 'AddIssueSourceMember' is not a subtype of 'ComponentState<AddIssueSourceMember>'

  abstract class ComponentState<S extends ComponentState<S>> {
                                ^
  'package:gissue_client_models/src/client/model/repos/add_issue_source_list_editor.dart': malbounded type: line 181 pos 51: type 'AddIssueSourceMember' has an out of bound type argument
  class AddIssueSourceMember extends RepoListMember<AddIssueSourceMember> {
                                                    ^
  'file:///Users/blah/dart/backlogio_acdart/gitbacklog_root/gissue_root/gissue_client_models/test/client/model/repos/add_issue_source_list_editor_test.dart': malbounded type: line 30 pos 3: type 'AddIssueSourceListEditor' has an out of bound type argument
    AddIssueSourceListEditor editor;
    ^

Looking at the classes referenced here I believe the analyser is correct and the problem is at runtime.

class AddIssueSourceMember extends RepoListMember<AddIssueSourceMember> {}

class RepoListMember<M extends RepoListMember<M>>
    extends AbstractListMember<GitRepo, M> {}


abstract class AbstractListMember<E, M extends AbstractListMember<E, M>>
    extends ComponentState<M> {}

abstract class ComponentState<S extends ComponentState<S>> {}



class AddIssueSourceListEditor extends RepoListEditor<IssueSourceState,
    IssueSourceEntity, AddIssueSourceMember, AddIssueSourceListState> {
}

Any suggestions on a workaround? This is breaking things for me now

[vsmenon]

Do you have a self contained set of classes that exhibit the problem? What did the original code look like?

[Andersmholmgren]

I'll work on a repro. I might wait till #25568 is fixed on the odd chance that it is in some way related as it relates to similar classes

[jmesserly]

This version doesn't have any strong mode errors in the latest build:

class Entities<T extends ConceptEntity<T>> implements EntitiesApi<T> { }
class ConceptEntity<T extends ConceptEntity<T>> implements EntityApi<T> { }
abstract class EntityApi<T extends EntityApi<T>> { }
abstract class EntitiesApi<T extends EntityApi<T>> { }
class Concept extends ConceptEntity<Concept> { }

main() {
  new ConceptEntity<Concept>();
}

... so it may be possible to use this now.

[jmesserly]

thanks to @zoechi for pointing this out :)

[jmesserly]

this test is no longer marked failing.