Extension type. Issue 53935. Update constant evaluation.

Bug: #53935
Bug: #53751
Change-Id: I514c79c79c9229b7fed313712b8f1d7a3ed91ca7
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/334862
Reviewed-by: Kallen Tu <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Konstantin Shcheglov <[email protected]>

Author: scheglov

pkg/analyzer/lib/src/dart/constant/evaluation.dart

@@ -26,7 +26,8 @@ import 'package:analyzer/src/dart/element/element.dart';
 import 'package:analyzer/src/dart/element/member.dart';
 import 'package:analyzer/src/dart/element/type.dart';
 import 'package:analyzer/src/dart/element/type_algebra.dart';
-import 'package:analyzer/src/dart/element/type_system.dart' show TypeSystemImpl;
+import 'package:analyzer/src/dart/element/type_system.dart'
+    show ExtensionTypeErasure, TypeSystemImpl;
 import 'package:analyzer/src/diagnostic/diagnostic.dart';
 import 'package:analyzer/src/error/codes.dart';
 import 'package:analyzer/src/generated/engine.dart';
@@ -2510,10 +2511,18 @@ class _InstanceCreationEvaluator {
       return error;
     }
 
+    var definingType = this.definingType;
+    if (definingType.element case final ExtensionTypeElement element) {
+      final representation = _fieldMap[element.representation.name];
+      if (representation != null) {
+        return representation;
+      }
+    }
+
     return DartObjectImpl(
       typeSystem,
       definingType,
-      GenericState(definingType, _fieldMap, invocation: _invocation),
+      GenericState(_fieldMap, invocation: _invocation),
     );
   }
 
@@ -3131,6 +3140,7 @@ extension RuntimeExtensions on TypeSystemImpl {
     DartObjectImpl obj,
     DartType type,
   ) {
+    type = ExtensionTypeErasure().perform(type);
     if (!isNonNullableByDefault) {
       type = toLegacyTypeIfOptOut(type);
     }

pkg/analyzer/lib/src/dart/constant/value.dart

@@ -181,7 +181,20 @@ class DartObjectImpl implements DartObject, Constant {
   final VariableElementImpl? variable;
 
   /// Initialize a newly created object to have the given [type] and [state].
-  DartObjectImpl(this._typeSystem, this.type, this.state, {this.variable});
+  factory DartObjectImpl(
+    TypeSystemImpl typeSystem,
+    DartType type,
+    InstanceState state, {
+    VariableElementImpl? variable,
+  }) {
+    type = ExtensionTypeErasure().perform(type);
+    return DartObjectImpl._(
+      typeSystem,
+      type,
+      state,
+      variable: variable,
+    );
+  }
 
   /// Creates a duplicate instance of [other], tied to [variable].
   factory DartObjectImpl.forVariable(
@@ -216,10 +229,17 @@ class DartObjectImpl implements DartObject, Constant {
     return DartObjectImpl(
       typeSystem,
       type,
-      GenericState(type, {}, isUnknown: true),
+      GenericState({}, isUnknown: true),
     );
   }
 
+  /// Initialize a newly created object to have the given [type] and [state].
+  DartObjectImpl._(this._typeSystem, this.type, this.state, {this.variable}) {
+    if (state case final GenericState state) {
+      state._object = this;
+    }
+  }
+
   Map<String, DartObjectImpl>? get fields => state.fields;
 
   @override
@@ -1419,8 +1439,8 @@ class GenericState extends InstanceState {
   /// Pseudo-field that we use to represent fields in the superclass.
   static String SUPERCLASS_FIELD = "(super)";
 
-  /// The type of the object being represented.
-  final DartType _type;
+  /// The enclosing [DartObjectImpl].
+  late DartObjectImpl _object;
 
   /// The values of the fields of this instance.
   final Map<String, DartObjectImpl> _fieldMap;
@@ -1431,10 +1451,7 @@ class GenericState extends InstanceState {
   @override
   final bool isUnknown;
 
-  /// Initialize a newly created state to represent a newly created object. The
-  /// [fieldMap] contains the values of the fields of the instance.
   GenericState(
-    this._type,
     this._fieldMap, {
     this.invocation,
     this.isUnknown = false,
@@ -1486,7 +1503,7 @@ class GenericState extends InstanceState {
 
   @override
   bool hasPrimitiveEquality(FeatureSet featureSet) {
-    final type = _type;
+    final type = _object.type;
     if (type is InterfaceType) {
       bool isFromDartCoreObject(ExecutableElement? element) {
         final enclosing = element?.enclosingElement;
@@ -2481,19 +2498,32 @@ class ListState extends InstanceState {
   final DartType elementType;
   final List<DartObjectImpl> elements;
 
-  /// Whether the list contains an element that has an unknown value.
-  final bool _isUnknown;
+  @override
+  final bool isUnknown;
 
-  ListState({
-    required this.elementType,
-    required this.elements,
+  factory ListState({
+    required DartType elementType,
+    required List<DartObjectImpl> elements,
     bool isUnknown = false,
-  }) : _isUnknown = isUnknown;
+  }) {
+    elementType = ExtensionTypeErasure().perform(elementType);
+    return ListState._(
+      elementType: elementType,
+      elements: elements,
+      isUnknown: isUnknown,
+    );
+  }
 
   /// Creates a state that represents a list whose value is not known.
   factory ListState.unknown(DartType elementType) =>
       ListState(elementType: elementType, elements: [], isUnknown: true);
 
+  ListState._({
+    required this.elementType,
+    required this.elements,
+    required this.isUnknown,
+  });
+
   @override
   int get hashCode {
     int value = 0;
@@ -2504,9 +2534,6 @@ class ListState extends InstanceState {
     return value;
   }
 
-  @override
-  bool get isUnknown => _isUnknown;
-
   @override
   String get typeName => "List";
 
@@ -3077,8 +3104,14 @@ class TypeState extends InstanceState {
   /// The element representing the type being modeled.
   final DartType? _type;
 
-  /// Initialize a newly created state to represent the given [value].
-  TypeState(this._type);
+  factory TypeState(DartType? type) {
+    if (type != null) {
+      type = ExtensionTypeErasure().perform(type);
+    }
+    return TypeState._(type);
+  }
+
+  TypeState._(this._type);
 
   @override
   int get hashCode => _type?.hashCode ?? 0;

pkg/analyzer/lib/src/dart/element/type_system.dart

@@ -35,6 +35,22 @@ import 'package:analyzer/src/dart/element/well_bounded.dart';
 import 'package:analyzer/src/utilities/extensions/collection.dart';
 import 'package:meta/meta.dart';
 
+class ExtensionTypeErasure extends ReplacementVisitor {
+  DartType perform(DartType type) {
+    return type.accept(this) ?? type;
+  }
+
+  @override
+  DartType? visitInterfaceType(covariant InterfaceTypeImpl type) {
+    final typeErasure = type.representationTypeErasure;
+    if (typeErasure != null) {
+      return typeErasure;
+    }
+
+    return super.visitInterfaceType(type);
+  }
+}
+
 /// Fresh type parameters created to unify two lists of type parameters.
 class RelatedTypeParameters {
   static final _empty = RelatedTypeParameters._(const [], const []);

pkg/analyzer/lib/src/summary2/extension_type.dart

@@ -7,8 +7,8 @@ import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/src/dart/ast/ast.dart';
 import 'package:analyzer/src/dart/ast/extensions.dart';
 import 'package:analyzer/src/dart/element/element.dart';
-import 'package:analyzer/src/dart/element/replacement_visitor.dart';
 import 'package:analyzer/src/dart/element/type.dart';
+import 'package:analyzer/src/dart/element/type_system.dart';
 import 'package:analyzer/src/dart/element/type_visitor.dart';
 import 'package:analyzer/src/summary2/link.dart';
 import 'package:analyzer/src/utilities/extensions/collection.dart';
@@ -58,22 +58,6 @@ class _DependenciesCollector extends RecursiveTypeVisitor {
   }
 }
 
-class _ExtensionTypeErasure extends ReplacementVisitor {
-  DartType perform(DartType type) {
-    return type.accept(this) ?? type;
-  }
-
-  @override
-  DartType? visitInterfaceType(covariant InterfaceTypeImpl type) {
-    final typeErasure = type.representationTypeErasure;
-    if (typeErasure != null) {
-      return typeErasure;
-    }
-
-    return super.visitInterfaceType(type);
-  }
-}
-
 class _ImplementsNode extends graph.Node<_ImplementsNode> {
   final _ImplementsWalker walker;
   final ExtensionTypeElementImpl element;
@@ -167,7 +151,7 @@ class _Node extends graph.Node<_Node> {
     final typeSystem = element.library.typeSystem;
 
     element.representation.type = type;
-    element.typeErasure = _ExtensionTypeErasure().perform(type);
+    element.typeErasure = ExtensionTypeErasure().perform(type);
 
     var interfaces = node.implementsClause?.interfaces
         .map((e) => e.type)