Elements. Store InterfaceElementImpl2 in InterfaceTypeImpl.

Change-Id: Id7cf5dd51abb331c851b0244e9be0f0db15b73ee
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/404380
Commit-Queue: Konstantin Shcheglov <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>

Author: scheglov

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

@@ -6091,14 +6091,6 @@ abstract class InterfaceElementImpl extends InstanceElementImpl
   /// of this class have been inferred.
   bool hasBeenInferred = false;
 
-  /// The non-nullable instance of this element, without alias.
-  /// Should be used only when the element has no type parameters.
-  InterfaceTypeImpl? _nonNullableInstance;
-
-  /// The nullable instance of this element, without alias.
-  /// Should be used only when the element has no type parameters.
-  InterfaceTypeImpl? _nullableInstance;
-
   List<ConstructorElementImpl> _constructors = _Sentinel.constructorElement;
 
   /// Initialize a newly created class element to have the given [name] at the
@@ -6275,43 +6267,10 @@ abstract class InterfaceElementImpl extends InstanceElementImpl
     required List<DartType> typeArguments,
     required NullabilitySuffix nullabilitySuffix,
   }) {
-    assert(typeArguments.length == typeParameters.length);
-
-    if (typeArguments.isEmpty) {
-      switch (nullabilitySuffix) {
-        case NullabilitySuffix.none:
-          if (_nonNullableInstance case var instance?) {
-            return instance;
-          }
-        case NullabilitySuffix.question:
-          if (_nullableInstance case var instance?) {
-            return instance;
-          }
-        case NullabilitySuffix.star:
-          // TODO(scheglov): remove together with `star`
-          break;
-      }
-    }
-
-    var result = InterfaceTypeImpl(
-      element: this,
+    return element.instantiate(
       typeArguments: typeArguments,
       nullabilitySuffix: nullabilitySuffix,
     );
-
-    if (typeArguments.isEmpty) {
-      switch (nullabilitySuffix) {
-        case NullabilitySuffix.none:
-          _nonNullableInstance = result;
-        case NullabilitySuffix.question:
-          _nullableInstance = result;
-        case NullabilitySuffix.star:
-          // TODO(scheglov): remove together with `star`
-          break;
-      }
-    }
-
-    return result;
   }
 
   @override
@@ -6535,6 +6494,14 @@ abstract class InterfaceElementImpl extends InstanceElementImpl
 abstract class InterfaceElementImpl2 extends InstanceElementImpl2
     with _HasSinceSdkVersionMixin
     implements AugmentedInterfaceElement, InterfaceElement2 {
+  /// The non-nullable instance of this element, without alias.
+  /// Should be used only when the element has no type parameters.
+  InterfaceTypeImpl? _nonNullableInstance;
+
+  /// The nullable instance of this element, without alias.
+  /// Should be used only when the element has no type parameters.
+  InterfaceTypeImpl? _nullableInstance;
+
   @override
   List<InterfaceType> interfaces = [];
 
@@ -6633,12 +6600,48 @@ abstract class InterfaceElementImpl2 extends InstanceElementImpl2
   }
 
   @override
-  InterfaceType instantiate({
+  InterfaceTypeImpl instantiate({
     required List<DartType> typeArguments,
     required NullabilitySuffix nullabilitySuffix,
-  }) =>
-      firstFragment.instantiate(
-          typeArguments: typeArguments, nullabilitySuffix: nullabilitySuffix);
+  }) {
+    assert(typeArguments.length == typeParameters2.length);
+
+    if (typeArguments.isEmpty) {
+      switch (nullabilitySuffix) {
+        case NullabilitySuffix.none:
+          if (_nonNullableInstance case var instance?) {
+            return instance;
+          }
+        case NullabilitySuffix.question:
+          if (_nullableInstance case var instance?) {
+            return instance;
+          }
+        case NullabilitySuffix.star:
+          // TODO(scheglov): remove together with `star`
+          break;
+      }
+    }
+
+    var result = InterfaceTypeImpl.v2(
+      element: this,
+      typeArguments: typeArguments,
+      nullabilitySuffix: nullabilitySuffix,
+    );
+
+    if (typeArguments.isEmpty) {
+      switch (nullabilitySuffix) {
+        case NullabilitySuffix.none:
+          _nonNullableInstance = result;
+        case NullabilitySuffix.question:
+          _nullableInstance = result;
+        case NullabilitySuffix.star:
+          // TODO(scheglov): remove together with `star`
+          break;
+      }
+    }
+
+    return result;
+  }
 
   @override
   MethodElement2? lookUpConcreteMethod(

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

@@ -526,12 +526,12 @@ class FunctionTypeImpl extends TypeImpl
 /// A concrete implementation of [DartType] representing types of the form
 /// `FutureOr<...>`.
 class FutureOrTypeImpl extends InterfaceTypeImpl {
-  FutureOrTypeImpl(
-      {required super.element,
-      required super.typeArgument,
-      required super.nullabilitySuffix,
-      super.alias})
-      : super._futureOr();
+  FutureOrTypeImpl({
+    required super.element3,
+    required super.typeArgument,
+    required super.nullabilitySuffix,
+    super.alias,
+  }) : super._futureOr();
 
   @override
   bool get isDartAsyncFutureOr => true;
@@ -543,7 +543,7 @@ class FutureOrTypeImpl extends InterfaceTypeImpl {
     if (this.nullabilitySuffix == nullabilitySuffix) return this;
 
     return FutureOrTypeImpl(
-      element: element,
+      element3: element3,
       typeArgument: typeArgument,
       nullabilitySuffix: nullabilitySuffix,
       alias: alias,
@@ -570,7 +570,7 @@ class InstantiatedTypeAliasElementImpl implements InstantiatedTypeAliasElement {
 /// A concrete implementation of an [InterfaceType].
 class InterfaceTypeImpl extends TypeImpl implements InterfaceType {
   @override
-  final InterfaceElementImpl element;
+  final InterfaceElementImpl2 element3;
 
   @override
   final List<DartType> typeArguments;
@@ -587,30 +587,20 @@ class InterfaceTypeImpl extends TypeImpl implements InterfaceType {
   /// Cached [MethodElement]s - members or raw elements.
   List<MethodElement>? _methods;
 
-  factory InterfaceTypeImpl(
-      {required InterfaceElement element,
-      required List<DartType> typeArguments,
-      required NullabilitySuffix nullabilitySuffix,
-      InstantiatedTypeAliasElement? alias}) {
+  factory InterfaceTypeImpl({
+    required InterfaceElement element,
+    required List<DartType> typeArguments,
+    required NullabilitySuffix nullabilitySuffix,
+    InstantiatedTypeAliasElement? alias,
+  }) {
     // TODO(paulberry): avoid this cast by changing the type of `element`
     element as InterfaceElementImpl;
-    if (element.name == 'FutureOr' && element.library.isDartAsync) {
-      return FutureOrTypeImpl(
-          element: element,
-          typeArgument: typeArguments.isNotEmpty
-              ? typeArguments[0]
-              : InvalidTypeImpl.instance,
-          nullabilitySuffix: nullabilitySuffix,
-          alias: alias);
-    } else if (element.name == 'Null' && element.library.isDartCore) {
-      return NullTypeImpl(element: element, alias: alias);
-    } else {
-      return InterfaceTypeImpl._(
-          element: element,
-          typeArguments: typeArguments,
-          nullabilitySuffix: nullabilitySuffix,
-          alias: alias);
-    }
+    return InterfaceTypeImpl.v2(
+      element: element.asElement2,
+      typeArguments: typeArguments,
+      nullabilitySuffix: nullabilitySuffix,
+      alias: alias,
+    );
   }
 
   factory InterfaceTypeImpl.v2({
@@ -619,51 +609,53 @@ class InterfaceTypeImpl extends TypeImpl implements InterfaceType {
     required NullabilitySuffix nullabilitySuffix,
     InstantiatedTypeAliasElement? alias,
   }) {
-    return InterfaceTypeImpl(
-      element: element.asElement,
-      typeArguments: typeArguments,
-      nullabilitySuffix: nullabilitySuffix,
-      alias: alias,
-    );
+    if (element.name3 == 'FutureOr' && element.library2.isDartAsync) {
+      return FutureOrTypeImpl(
+        element3: element,
+        typeArgument: typeArguments.isNotEmpty
+            ? typeArguments[0]
+            : InvalidTypeImpl.instance,
+        nullabilitySuffix: nullabilitySuffix,
+        alias: alias,
+      );
+    } else if (element.name3 == 'Null' && element.library2.isDartCore) {
+      return NullTypeImpl(
+        element3: element,
+        alias: alias,
+      );
+    } else {
+      return InterfaceTypeImpl._(
+        element3: element,
+        typeArguments: typeArguments,
+        nullabilitySuffix: nullabilitySuffix,
+        alias: alias,
+      );
+    }
   }
 
   InterfaceTypeImpl._({
-    required this.element,
+    required this.element3,
     required this.typeArguments,
     required this.nullabilitySuffix,
     required super.alias,
-  }) {
-    if (element.augmentationTarget != null) {
-      throw ArgumentError(
-        'InterfaceType(s) can only be created for declarations',
-      );
-    }
-    var typeParameters = element.typeParameters;
-    if (typeArguments.length != typeParameters.length) {
-      throw ArgumentError(
-        '[typeParameters.length: ${typeParameters.length}]'
-        '[typeArguments.length: ${typeArguments.length}]'
-        '[element: $element]'
-        '[typeParameters: $typeParameters]'
-        '[typeArguments: $typeArguments]',
-      );
-    }
-  }
+  });
 
-  InterfaceTypeImpl._futureOr(
-      {required this.element,
-      required DartType typeArgument,
-      required this.nullabilitySuffix,
-      super.alias})
-      : typeArguments = [typeArgument] {
-    assert(element.name == 'FutureOr' && element.library.isDartAsync);
+  InterfaceTypeImpl._futureOr({
+    required this.element3,
+    required DartType typeArgument,
+    required this.nullabilitySuffix,
+    super.alias,
+  }) : typeArguments = [typeArgument] {
+    assert(element3.name3 == 'FutureOr' && element3.library2.isDartAsync);
     assert(this is FutureOrTypeImpl);
   }
 
-  InterfaceTypeImpl._null({required this.element, super.alias})
-      : typeArguments = const [],
+  InterfaceTypeImpl._null({
+    required this.element3,
+    super.alias,
+  })  : typeArguments = const [],
         nullabilitySuffix = NullabilitySuffix.none {
-    assert(element.name == 'Null' && element.library.isDartCore);
+    assert(element3.name3 == 'Null' && element3.library2.isDartCore);
     assert(this is NullTypeImpl);
   }
 
@@ -708,7 +700,7 @@ class InterfaceTypeImpl extends TypeImpl implements InterfaceType {
       .toList();
 
   @override
-  InterfaceElementImpl2 get element3 => element.element;
+  InterfaceElementImpl get element => element3.asElement;
 
   @override
   List<GetterElement> get getters => accessors
@@ -1341,7 +1333,10 @@ class NeverTypeImpl extends TypeImpl implements NeverType {
 /// no type parameters and no nullability suffix.
 class NullTypeImpl extends InterfaceTypeImpl
     implements SharedNullTypeStructure<DartType> {
-  NullTypeImpl({required super.element, super.alias}) : super._null();
+  NullTypeImpl({
+    required super.element3,
+    super.alias,
+  }) : super._null();
 
   @override
   bool get isDartCoreNull => true;

pkg/analyzer/lib/src/test_utilities/mock_sdk_elements.dart

@@ -943,7 +943,7 @@ class _MockSdkElementsBuilder {
   }
 
   void _buildClassElement(ClassElementImpl fragment) {
-    var element = ClassElementImpl2(Reference.root(), fragment);
+    var element = fragment.element;
     element.mixins = fragment.mixins;
     element.interfaces = fragment.interfaces;
     element.fields = fragment.fields;
@@ -979,13 +979,14 @@ class _MockSdkElementsBuilder {
     List<TypeParameterElementImpl> typeParameters = const [],
     required CompilationUnitElementImpl unit,
   }) {
-    var element = ClassElementImpl(name, 0);
-    element.typeParameters = typeParameters;
-    element.constructors = <ConstructorElementImpl>[
+    var fragment = ClassElementImpl(name, 0);
+    ClassElementImpl2(Reference.root(), fragment);
+    fragment.typeParameters = typeParameters;
+    fragment.constructors = <ConstructorElementImpl>[
       _constructor(),
     ];
-    unit.encloseElement(element);
-    return element;
+    unit.encloseElement(fragment);
+    return fragment;
   }
 
   ConstructorElementImpl _constructor({

pkg/analyzer/lib/src/utilities/extensions/element.dart

@@ -272,6 +272,12 @@ extension EnumElementExtension on EnumElement {
   }
 }
 
+extension EnumElementImplExtension on EnumElementImpl {
+  EnumElementImpl2 get asElement2 {
+    return element;
+  }
+}
+
 extension ExecutableElement2Extension on ExecutableElement2 {
   ExecutableElement get asElement {
     if (this case ExecutableMember member) {
@@ -380,6 +386,18 @@ extension InterfaceElementExtension on InterfaceElement {
   }
 }
 
+extension InterfaceElementImpl2Extension on InterfaceElementImpl2 {
+  InterfaceElementImpl get asElement {
+    return firstFragment;
+  }
+}
+
+extension InterfaceElementImplExtension on InterfaceElementImpl {
+  InterfaceElementImpl2 get asElement2 {
+    return element;
+  }
+}
+
 extension LabelElement2Extension on LabelElement2 {
   LabelElement get asElement {
     return firstFragment as LabelElement;