Elements. Deprecate ClassElement.

Change-Id: I0bf4a73bacc4917d4f61c91bcdceba41a9c18ec9
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/418903
Reviewed-by: Samuel Rawlins <srawlins@google.com>
Reviewed-by: Paul Berry <paulberry@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>

pkg/analyzer/api.txt

@@ -3015,7 +3015,7 @@ package:analyzer/dart/element/element.dart:
   elementModelDeprecationMsg (static getter: String)
   BindPatternVariableElement (class extends Object implements PatternVariableElement, deprecated):
     new (constructor: BindPatternVariableElement Function())
-  ClassElement (class extends Object implements InterfaceElement):
+  ClassElement (class extends Object implements InterfaceElement, deprecated):
     new (constructor: ClassElement Function())
     hasNonFinalField (getter: bool)
     isAbstract (getter: bool)
@@ -3033,7 +3033,7 @@ package:analyzer/dart/element/element.dart:
     isExtendableIn (method: bool Function(LibraryElement))
     isImplementableIn (method: bool Function(LibraryElement))
     isMixableIn (method: bool Function(LibraryElement))
-  ClassMemberElement (class extends Object implements Element):
+  ClassMemberElement (class extends Object implements Element, deprecated):
     new (constructor: ClassMemberElement Function())
     enclosingElement3 (getter: Element)
     isStatic (getter: bool)
@@ -3342,9 +3342,9 @@ package:analyzer/dart/element/element.dart:
     allSupertypes (getter: List<InterfaceType>)
     constructors (getter: List<ConstructorElement>, deprecated)
     interfaces (getter: List<InterfaceType>)
-    mixins (getter: List<InterfaceType>)
+    mixins (getter: List<InterfaceType>, deprecated)
     name (getter: String)
-    supertype (getter: InterfaceType?)
+    supertype (getter: InterfaceType?, deprecated)
     thisType (getter: InterfaceType)
     unnamedConstructor (getter: ConstructorElement?, deprecated)
     getField (method: FieldElement? Function(String))
@@ -3392,7 +3392,7 @@ package:analyzer/dart/element/element.dart:
     typeProvider (getter: TypeProvider)
     typeSystem (getter: TypeSystem)
     units (getter: List<CompilationUnitElement>, deprecated)
-    getClass (method: ClassElement? Function(String))
+    getClass (method: ClassElement? Function(String), deprecated)
   LibraryExportElement (class extends Object implements _ExistingElement):
     new (constructor: LibraryExportElement Function())
     combinators (getter: List<NamespaceCombinator>)

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

@@ -78,6 +78,7 @@ abstract class BindPatternVariableElement implements PatternVariableElement {}
 /// a class body), a mixin declaration, or an enum declaration.
 ///
 /// Clients may not extend, implement or mix-in this class.
+@Deprecated('Use ClassElement2 instead')
 abstract class ClassElement implements InterfaceElement {
   /// Whether the class or its superclass declares a non-final instance field.
   bool get hasNonFinalField;
@@ -170,6 +171,13 @@ abstract class ClassElement implements InterfaceElement {
 /// An element that is contained within a [ClassElement].
 ///
 /// Clients may not extend, implement or mix-in this class.
+@Deprecated('''
+There is no common interface for class members in the new analyzer element
+model. If you are using this class in an `is` test or a pattern match, replace
+it with checks for the specific element types you are interested in (e.g.,
+`ConstructorElement2`, `MethodElement2`, etc.). If you are using this class as
+a type annotation for a variable that could hold any kind of class member, use
+`Element2` instead.''')
 abstract class ClassMemberElement implements Element {
   // TODO(brianwilkerson): Either remove this class or rename it to something
   //  more correct.
@@ -1196,7 +1204,10 @@ abstract class ExtensionTypeElement implements InterfaceElement {
 ///
 /// Clients may not extend, implement or mix-in this class.
 abstract class FieldElement
-    implements ClassMemberElement, PropertyInducingElement {
+    implements
+        // ignore:deprecated_member_use_from_same_package
+        ClassMemberElement,
+        PropertyInducingElement {
   @override
   FieldElement get declaration;
 
@@ -1369,6 +1380,7 @@ abstract class InterfaceElement implements InstanceElement {
   /// safe to assume that the inheritance structure of a class does not contain
   /// a cycle. Clients that traverse the inheritance structure must explicitly
   /// guard against infinite loops.
+  @Deprecated(elementModelDeprecationMsg)
   List<InterfaceType> get mixins;
 
   @override
@@ -1389,6 +1401,7 @@ abstract class InterfaceElement implements InstanceElement {
   /// safe to assume that the inheritance structure of a class does not contain
   /// a cycle. Clients that traverse the inheritance structure must explicitly
   /// guard against infinite loops.
+  @Deprecated(elementModelDeprecationMsg)
   InterfaceType? get supertype;
 
   @override
@@ -1713,6 +1726,7 @@ abstract class LibraryElement implements _ExistingElement {
 
   /// The class defined in this library that has the given [name], or
   /// `null` if this library does not define a class with the given name.
+  @Deprecated(elementModelDeprecationMsg)
   ClassElement? getClass(String name);
 }
 
@@ -1806,7 +1820,11 @@ abstract class LocalVariableElement implements PromotableElement {
 /// An element that represents a method defined within a class.
 ///
 /// Clients may not extend, implement or mix-in this class.
-abstract class MethodElement implements ClassMemberElement, ExecutableElement {
+abstract class MethodElement
+    implements
+        // ignore:deprecated_member_use_from_same_package
+        ClassMemberElement,
+        ExecutableElement {
   @override
   MethodElement get declaration;
 }

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

@@ -140,7 +140,10 @@ class BindPatternVariableElementImpl2 extends PatternVariableElementImpl2
 
 /// An [InterfaceElementImpl] which is a class.
 class ClassElementImpl extends ClassOrMixinElementImpl
-    implements ClassElement, ClassFragment {
+    implements
+        // ignore:deprecated_member_use_from_same_package
+        ClassElement,
+        ClassFragment {
   late ClassElementImpl2 augmentedInternal;
 
   /// Initialize a newly created class element to have the given [name] at the
@@ -221,7 +224,7 @@ class ClassElementImpl extends ClassOrMixinElementImpl
   bool get hasNoSuchMethod {
     MethodElement? method = lookUpConcreteMethod(
         FunctionElement.NO_SUCH_METHOD_METHOD_NAME, library);
-    var definingClass = method?.enclosingElement3 as ClassElement?;
+    var definingClass = method?.enclosingElement3 as ClassElementImpl?;
     return definingClass != null && !definingClass.isDartCoreObject;
   }
 
@@ -6161,6 +6164,7 @@ abstract class InterfaceElementImpl extends InstanceElementImpl
         getter.enclosingElement3 != this);
   }
 
+  @Deprecated(elementModelDeprecationMsg)
   ExecutableElement? lookUpInheritedConcreteMember(
       String name, LibraryElement library) {
     if (name.endsWith('=')) {
@@ -6181,6 +6185,7 @@ abstract class InterfaceElementImpl extends InstanceElementImpl
         method.enclosingElement3 != this);
   }
 
+  @Deprecated(elementModelDeprecationMsg)
   @override
   PropertyAccessorElement? lookUpInheritedConcreteSetter(
       String setterName, LibraryElement library) {
@@ -6242,6 +6247,7 @@ abstract class InterfaceElementImpl extends InstanceElementImpl
   /// This method should be used only for error recovery during analysis,
   /// when instance access to a static class member, defined in this class,
   /// or a superclass.
+  @Deprecated(elementModelDeprecationMsg)
   PropertyAccessorElement? lookupStaticSetter(
       String name, LibraryElement library) {
     return _implementationsOfSetter(name).firstWhereOrNull(
@@ -6326,6 +6332,7 @@ abstract class InterfaceElementImpl extends InstanceElementImpl
   /// The setters are returned based on the depth of their defining class; if
   /// this class contains a definition of the setter it will occur first, if
   /// Object contains a definition of the setter it will occur last.
+  @Deprecated(elementModelDeprecationMsg)
   Iterable<PropertyAccessorElement> _implementationsOfSetter(
       String setterName) sync* {
     var visitedClasses = <InterfaceElement>{};

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

@@ -53,18 +53,6 @@ extension BindPatternVariableElementImplExtension
   }
 }
 
-extension ClassElement2Extension on ClassElement2 {
-  ClassElement get asElement {
-    return firstFragment as ClassElement;
-  }
-}
-
-extension ClassElementExtension on ClassElement {
-  ClassElement2 get asElement2 {
-    return (this as ClassElementImpl).element;
-  }
-}
-
 extension ClassElementImpl2Extension on ClassElementImpl2 {
   ClassElementImpl get asElement {
     return firstFragment;

pkg/linter/test/rules/analyzer_use_new_elements_test.dart

@@ -42,14 +42,17 @@ class AnalyzerUseNewElementsTest extends LintRuleTest {
   }
 
   test_enablement_optedOut() async {
-    await assertDiagnostics(r'''
+    await assertDiagnostics(
+      r'''
 // ignore_for_file: analyzer_use_new_elements
 import 'package:analyzer/dart/element/element.dart';
 
 ClassElement f() {
   throw 42;
 }
-''', []);
+''',
+      [error(HintCode.DEPRECATED_MEMBER_USE_WITH_MESSAGE, 100, 12)],
+    );
   }
 
   test_interfaceTypeImpl_element() async {
@@ -138,7 +141,10 @@ ClassElement f() {
   throw 42;
 }
 ''',
-      [lint(54, 12)],
+      [
+        error(HintCode.DEPRECATED_MEMBER_USE_WITH_MESSAGE, 54, 12),
+        lint(54, 12),
+      ],
     );
   }