Use FooImpl in BarImpl getters/setters, property related.

I think we might get away with this now, because we don't let users
create elements manually.

Presubmit in google3 looks green.
https://fusion2.corp.google.com/presubmit/tap/483535261/OCL:483535261:BASE:483575659:1666678949553:5d26313d/targets

Change-Id: Id9618e2d8a15ab98c5919750461c508e87f76c7b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/265405
Reviewed-by: Samuel Rawlins <srawlins@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>

pkg/analysis_server/lib/src/lsp/handlers/handler_definition.dart

@@ -177,10 +177,7 @@ class DefinitionHandler extends MessageHandler<TextDocumentPositionParams,
     // For synthetic getters created for fields, we need to access the associated
     // variable to get the codeOffset/codeLength.
     if (codeElement.isSynthetic && codeElement is PropertyAccessorElementImpl) {
-      final variable = codeElement.variable;
-      if (variable is ElementImpl) {
-        codeElement = variable as ElementImpl;
-      }
+      codeElement = codeElement.variable;
     }
 
     // Read the main codeOffset from the element. This may include doc comments

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

@@ -74,7 +74,7 @@ abstract class AbstractClassElementImpl extends _ExistingElementImpl
   List<PropertyAccessorElement> _accessors = _Sentinel.propertyAccessorElement;
 
   /// A list containing all of the fields contained in this class.
-  List<FieldElement> _fields = _Sentinel.fieldElement;
+  List<FieldElementImpl> _fields = _Sentinel.fieldElement;
 
   /// A list containing all of the methods contained in this class.
   List<MethodElement> _methods = _Sentinel.methodElement;
@@ -122,10 +122,13 @@ abstract class AbstractClassElementImpl extends _ExistingElementImpl
   @override
   CompilationUnitElementImpl get enclosingElement3 => enclosingElement;
 
+  @override
+  List<FieldElementImpl> get fields;
+
   /// Set the fields contained in this class to the given [fields].
-  set fields(List<FieldElement> fields) {
-    for (FieldElement field in fields) {
-      (field as FieldElementImpl).enclosingElement = this;
+  set fields(List<FieldElementImpl> fields) {
+    for (var field in fields) {
+      field.enclosingElement = this;
     }
     _fields = fields;
   }
@@ -609,7 +612,7 @@ class ClassElementImpl extends ClassOrMixinElementImpl implements ClassElement {
   }
 
   @override
-  set fields(List<FieldElement> fields) {
+  set fields(List<FieldElementImpl> fields) {
     assert(!isMixinApplication);
     super.fields = fields;
   }
@@ -968,7 +971,7 @@ abstract class ClassOrMixinElementImpl extends AbstractClassElementImpl {
   }
 
   @override
-  List<FieldElement> get fields {
+  List<FieldElementImpl> get fields {
     if (!identical(_fields, _Sentinel.fieldElement)) {
       return _fields;
     }
@@ -1099,7 +1102,7 @@ class CompilationUnitElementImpl extends UriReferencedElementImpl
   List<TypeAliasElement> _typeAliases = const [];
 
   /// A list containing all of the variables contained in this compilation unit.
-  List<TopLevelVariableElement> _variables = const [];
+  List<TopLevelVariableElementImpl> _variables = const [];
 
   ElementLinkedData? linkedData;
 
@@ -1255,15 +1258,15 @@ class CompilationUnitElementImpl extends UriReferencedElementImpl
   AnalysisSession get session => enclosingElement.session;
 
   @override
-  List<TopLevelVariableElement> get topLevelVariables {
+  List<TopLevelVariableElementImpl> get topLevelVariables {
     return _variables;
   }
 
   /// Set the top-level variables contained in this compilation unit to the
   ///  given[variables].
-  set topLevelVariables(List<TopLevelVariableElement> variables) {
-    for (TopLevelVariableElement field in variables) {
-      (field as TopLevelVariableElementImpl).enclosingElement = this;
+  set topLevelVariables(List<TopLevelVariableElementImpl> variables) {
+    for (var variable in variables) {
+      variable.enclosingElement = this;
     }
     _variables = variables;
   }
@@ -2947,7 +2950,7 @@ class EnumElementImpl extends AbstractClassElementImpl implements EnumElement {
   }
 
   @override
-  List<FieldElement> get fields {
+  List<FieldElementImpl> get fields {
     return _fields;
   }
 
@@ -3242,7 +3245,7 @@ class ExtensionElementImpl extends _ExistingElementImpl
   List<PropertyAccessorElement> _accessors = const [];
 
   /// A list containing all of the fields contained in this extension.
-  List<FieldElement> _fields = const [];
+  List<FieldElementImpl> _fields = const [];
 
   /// A list containing all of the methods contained in this extension.
   List<MethodElement> _methods = const [];
@@ -3303,13 +3306,13 @@ class ExtensionElementImpl extends _ExistingElementImpl
   }
 
   @override
-  List<FieldElement> get fields {
+  List<FieldElementImpl> get fields {
     return _fields;
   }
 
-  set fields(List<FieldElement> fields) {
-    for (FieldElement field in fields) {
-      (field as FieldElementImpl).enclosingElement = this;
+  set fields(List<FieldElementImpl> fields) {
+    for (var field in fields) {
+      field.enclosingElement = this;
     }
     _fields = fields;
   }
@@ -5506,7 +5509,7 @@ class PropertyAccessorElementImpl extends ExecutableElementImpl
     implements PropertyAccessorElement {
   /// The variable associated with this accessor.
   @override
-  late PropertyInducingElement variable;
+  late PropertyInducingElementImpl variable;
 
   /// If this method is a synthetic element which is based on another method
   /// with some modifications (such as making some parameters covariant),
@@ -5632,7 +5635,7 @@ class PropertyAccessorElementImpl_ImplicitGetter
   }
 
   @override
-  Element get enclosingElement => variable.enclosingElement!;
+  Element get enclosingElement => variable.enclosingElement;
 
   @Deprecated('Use enclosingElement instead')
   @override
@@ -5697,7 +5700,7 @@ class PropertyAccessorElementImpl_ImplicitSetter
   }
 
   @override
-  Element get enclosingElement => variable.enclosingElement!;
+  Element get enclosingElement => variable.enclosingElement;
 
   @Deprecated('Use enclosingElement instead')
   @override
@@ -5760,13 +5763,13 @@ abstract class PropertyInducingElementImpl
     extends NonParameterVariableElementImpl implements PropertyInducingElement {
   /// The getter associated with this element.
   @override
-  PropertyAccessorElement? getter;
+  PropertyAccessorElementImpl? getter;
 
   /// The setter associated with this element, or `null` if the element is
   /// effectively `final` and therefore does not have a setter associated with
   /// it.
   @override
-  PropertyAccessorElement? setter;
+  PropertyAccessorElementImpl? setter;
 
   /// This field is set during linking, and performs type inference for
   /// this property. After linking this field is always `null`.
@@ -6554,7 +6557,7 @@ class _Sentinel {
       List.unmodifiable([]);
   static final List<ConstructorElement> constructorElement =
       List.unmodifiable([]);
-  static final List<FieldElement> fieldElement = List.unmodifiable([]);
+  static final List<FieldElementImpl> fieldElement = List.unmodifiable([]);
   static final List<LibraryExportElement> libraryExportElement =
       List.unmodifiable([]);
   static final List<LibraryImportElement> libraryImportElement =

pkg/analyzer/lib/src/dart/element/inheritance_manager3.dart

@@ -779,7 +779,7 @@ class InheritanceManager3 {
       return result;
     }
 
-    if (executable is PropertyAccessorElement) {
+    if (executable is PropertyAccessorElementImpl) {
       assert(executable.isSetter);
       var result = PropertyAccessorElementImpl(executable.name, -1);
       result.enclosingElement = class_;

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

@@ -630,7 +630,7 @@ class LibraryReader {
     Reference reference,
   ) {
     var accessors = <PropertyAccessorElementImpl>[];
-    var fields = <FieldElement>[];
+    var fields = <FieldElementImpl>[];
     _readFields(unitElement, element, reference, accessors, fields);
     _readPropertyAccessors(
         unitElement, element, reference, accessors, fields, '@field');
@@ -783,7 +783,7 @@ class LibraryReader {
     element.typeParameters = _readTypeParameters();
 
     var accessors = <PropertyAccessorElement>[];
-    var fields = <FieldElement>[];
+    var fields = <FieldElementImpl>[];
 
     _readFields(unitElement, element, reference, accessors, fields);
     _readPropertyAccessors(
@@ -869,7 +869,7 @@ class LibraryReader {
     element.typeParameters = _readTypeParameters();
 
     var accessors = <PropertyAccessorElement>[];
-    var fields = <FieldElement>[];
+    var fields = <FieldElementImpl>[];
     _readPropertyAccessors(
         unitElement, element, reference, accessors, fields, '@field');
     _readFields(unitElement, element, reference, accessors, fields);
@@ -1127,7 +1127,7 @@ class LibraryReader {
 
     element.typeParameters = _readTypeParameters();
 
-    var fields = <FieldElement>[];
+    var fields = <FieldElementImpl>[];
     var accessors = <PropertyAccessorElement>[];
     _readFields(unitElement, element, reference, accessors, fields);
     _readPropertyAccessors(

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

@@ -242,8 +242,7 @@ class BundleWriter {
 
       _writeList(
         element.fields.where((e) {
-          return !e.isSynthetic ||
-              e is FieldElementImpl && e.isSyntheticEnumField;
+          return !e.isSynthetic || e.isSyntheticEnumField;
         }).toList(),
         _writeFieldElement,
       );

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

@@ -434,7 +434,7 @@ class ElementBuilder extends ThrowingAstVisitor<void> {
         _visitPropertyFirst<FieldDeclaration>(node.members);
       });
       element.accessors = holder.propertyAccessors;
-      element.fields = holder.properties.whereType<FieldElement>().toList();
+      element.fields = holder.properties.whereType<FieldElementImpl>().toList();
       element.methods = holder.methods;
     }
 
@@ -1140,7 +1140,7 @@ class ElementBuilder extends ThrowingAstVisitor<void> {
 
     element.accessors = holder.propertyAccessors;
     element.constructors = holder.constructors;
-    element.fields = holder.properties.whereType<FieldElement>().toList();
+    element.fields = holder.properties.whereType<FieldElementImpl>().toList();
     element.methods = holder.methods;
 
     _resolveConstructorFieldFormals(element);
@@ -1179,7 +1179,7 @@ class ElementBuilder extends ThrowingAstVisitor<void> {
 
     element.accessors = holder.propertyAccessors;
     element.constructors = holder.constructors;
-    element.fields = holder.properties.whereType<FieldElement>().toList();
+    element.fields = holder.properties.whereType<FieldElementImpl>().toList();
     element.methods = holder.methods;
 
     _resolveConstructorFieldFormals(element);

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

@@ -273,6 +273,7 @@ class LibraryBuilder {
     // Transplant built elements as if the augmentation was applied.
     final augmentedUnitElement = element.definingCompilationUnit;
     for (final augmentation in unitElement.classes) {
+      augmentation as ClassElementImpl;
       // TODO(scheglov) if augmentation
       final augmented = element.getClass(augmentation.name);
       if (augmented is ClassElementImpl) {

pkg/analyzer/lib/src/task/strong_mode.dart

@@ -327,7 +327,7 @@ class InstanceMemberInferrer {
         currentInterfaceElement = classElement;
         for (var field in classElement.fields) {
           _inferAccessorOrField(
-            field: field as FieldElementImpl,
+            field: field,
           );
         }
         for (var accessor in classElement.accessors) {

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

@@ -138,7 +138,7 @@ class _MockSdkElementsBuilder {
     _deprecatedElement = deprecatedElement = _class(name: 'Deprecated');
     deprecatedElement.supertype = objectType;
 
-    deprecatedElement.fields = <FieldElement>[
+    deprecatedElement.fields = [
       _field('message', stringType, isFinal: true),
     ];
 
@@ -167,11 +167,11 @@ class _MockSdkElementsBuilder {
     );
     doubleElement.supertype = numType;
 
-    FieldElement staticConstDoubleField(String name) {
+    FieldElementImpl staticConstDoubleField(String name) {
       return _field(name, doubleType, isStatic: true, isConst: true);
     }
 
-    doubleElement.fields = <FieldElement>[
+    doubleElement.fields = <FieldElementImpl>[
       staticConstDoubleField('nan'),
       staticConstDoubleField('infinity'),
       staticConstDoubleField('negativeInfinity'),
@@ -969,7 +969,7 @@ class _MockSdkElementsBuilder {
       overrideVariable.getter!,
       proxyVariable.getter!,
     ];
-    coreUnit.topLevelVariables = <TopLevelVariableElement>[
+    coreUnit.topLevelVariables = <TopLevelVariableElementImpl>[
       deprecatedVariable,
       overrideVariable,
       proxyVariable,
@@ -1014,7 +1014,7 @@ class _MockSdkElementsBuilder {
     return element;
   }
 
-  FieldElement _field(
+  FieldElementImpl _field(
     String name,
     DartType type, {
     bool isConst = false,
@@ -1133,11 +1133,14 @@ class _MockSdkElementsBuilder {
     classElement.accessors = accessors;
     classElement.fields = accessors
         .map((accessor) => accessor.variable)
-        .cast<FieldElement>()
+        .cast<FieldElementImpl>()
         .toList();
   }
 
-  TopLevelVariableElement _topLevelVariableConst(String name, DartType type) {
+  TopLevelVariableElementImpl _topLevelVariableConst(
+    String name,
+    DartType type,
+  ) {
     final variable = ConstTopLevelVariableElementImpl(name, -1)
       ..isConst = true
       ..type = type;

pkg/analyzer/test/src/dart/element/element_test.dart

@@ -40,7 +40,7 @@ class ClassElementImplTest extends AbstractTypeSystemTest {
     String fieldName = "f";
     FieldElementImpl field =
         ElementFactory.fieldElement(fieldName, false, false, false, intNone);
-    classA.fields = <FieldElement>[field];
+    classA.fields = [field];
     expect(classA.getField(fieldName), same(field));
     expect(field.isEnumConstant, false);
     // no such field
@@ -65,7 +65,7 @@ class ClassElementImplTest extends AbstractTypeSystemTest {
 
   void test_hasNonFinalField_false_const() {
     var classA = class_(name: 'A');
-    classA.fields = <FieldElement>[
+    classA.fields = [
       ElementFactory.fieldElement(
           "f", false, false, true, interfaceTypeStar(classA))
     ];
@@ -74,7 +74,7 @@ class ClassElementImplTest extends AbstractTypeSystemTest {
 
   void test_hasNonFinalField_false_final() {
     var classA = class_(name: 'A');
-    classA.fields = <FieldElement>[
+    classA.fields = [
       ElementFactory.fieldElement(
           "f", false, true, false, interfaceTypeStar(classA))
     ];
@@ -93,7 +93,7 @@ class ClassElementImplTest extends AbstractTypeSystemTest {
 
   void test_hasNonFinalField_true_immediate() {
     var classA = class_(name: 'A');
-    classA.fields = <FieldElement>[
+    classA.fields = [
       ElementFactory.fieldElement(
           "f", false, false, false, interfaceTypeStar(classA))
     ];
@@ -105,7 +105,7 @@ class ClassElementImplTest extends AbstractTypeSystemTest {
     var classA = class_(name: 'A');
     ClassElementImpl classB =
         ElementFactory.classElement("B", interfaceTypeStar(classA));
-    classA.fields = <FieldElement>[
+    classA.fields = [
       ElementFactory.fieldElement(
           "f", false, false, false, interfaceTypeStar(classA))
     ];
@@ -421,7 +421,7 @@ class ElementImplTest extends AbstractTypeSystemTest {
     LibraryElementImpl library = ElementFactory.library(analysisContext, "lib");
     ClassElementImpl classElement = ElementFactory.classElement2("C");
     (library.definingCompilationUnit).classes = <ClassElement>[classElement];
-    FieldElement field = ElementFactory.fieldElement(
+    var field = ElementFactory.fieldElement(
       "next",
       false,
       false,
@@ -431,7 +431,7 @@ class ElementImplTest extends AbstractTypeSystemTest {
         nullabilitySuffix: NullabilitySuffix.star,
       ),
     );
-    classElement.fields = <FieldElement>[field];
+    classElement.fields = [field];
     expect(field == field, isTrue);
     // ignore: unrelated_type_equality_checks
     expect(field == field.getter, isFalse);

pkg/analyzer/test/src/summary/elements_test.dart

@@ -11236,16 +11236,14 @@ library
       synthetic static get y @-1
         returnType: Object
 ''');
-    var x = library.definingCompilationUnit.topLevelVariables[0]
-        as TopLevelVariableElementImpl;
+    var x = library.definingCompilationUnit.topLevelVariables[0];
     var xExpr = x.constantInitializer as InstanceCreationExpression;
     var xType = xExpr.constructorName.staticElement!.returnType;
     _assertTypeStr(
       xType,
       'C<int>',
     );
-    var y = library.definingCompilationUnit.topLevelVariables[0]
-        as TopLevelVariableElementImpl;
+    var y = library.definingCompilationUnit.topLevelVariables[0];
     var yExpr = y.constantInitializer as InstanceCreationExpression;
     var yType = yExpr.constructorName.staticElement!.returnType;
     _assertTypeStr(yType, 'C<int>');