Fix the issue with reusing LinkedElementFactory and supertype for Object.

Bug: https://buganizer.corp.google.com/issues/170429675
Change-Id: Ieaec29e8b09ce5cc9c02e7dce5919e8b56278910
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/166789
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Konstantin Shcheglov <[email protected]>

Author: scheglov

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

@@ -860,18 +860,19 @@ class ClassElementImpl extends AbstractClassElementImpl
   InterfaceType get supertype {
     if (_supertype != null) return _supertype;
 
-    if (linkedNode != null) {
-      var context = enclosingUnit.linkedContext;
-
-      var coreTypes = context.bundleContext.elementFactory.coreTypes;
-      if (identical(this, coreTypes.objectClass)) {
-        return null;
-      }
+    if (hasModifier(Modifier.DART_CORE_OBJECT)) {
+      return null;
+    }
 
-      var type = context.getSuperclass(linkedNode)?.type;
+    if (linkedNode != null) {
+      var type = linkedContext.getSuperclass(linkedNode)?.type;
       if (_isInterfaceTypeClass(type)) {
         return _supertype = type;
       }
+      if (library.isDartCore && name == 'Object') {
+        setModifier(Modifier.DART_CORE_OBJECT, true);
+        return null;
+      }
       return _supertype = library.typeProvider.objectType;
     }
     return _supertype;
@@ -5898,61 +5899,65 @@ class Modifier implements Comparable<Modifier> {
   /// Indicates that the modifier 'covariant' was applied to the element.
   static const Modifier COVARIANT = Modifier('COVARIANT', 3);
 
+  /// Indicates that the class is `Object` from `dart:core`.
+  static const Modifier DART_CORE_OBJECT = Modifier('DART_CORE_OBJECT', 4);
+
   /// Indicates that the import element represents a deferred library.
-  static const Modifier DEFERRED = Modifier('DEFERRED', 4);
+  static const Modifier DEFERRED = Modifier('DEFERRED', 5);
 
   /// Indicates that a class element was defined by an enum declaration.
-  static const Modifier ENUM = Modifier('ENUM', 5);
+  static const Modifier ENUM = Modifier('ENUM', 6);
 
   /// Indicates that a class element was defined by an enum declaration.
-  static const Modifier EXTERNAL = Modifier('EXTERNAL', 6);
+  static const Modifier EXTERNAL = Modifier('EXTERNAL', 7);
 
   /// Indicates that the modifier 'factory' was applied to the element.
-  static const Modifier FACTORY = Modifier('FACTORY', 7);
+  static const Modifier FACTORY = Modifier('FACTORY', 8);
 
   /// Indicates that the modifier 'final' was applied to the element.
-  static const Modifier FINAL = Modifier('FINAL', 8);
+  static const Modifier FINAL = Modifier('FINAL', 9);
 
   /// Indicates that an executable element has a body marked as being a
   /// generator.
-  static const Modifier GENERATOR = Modifier('GENERATOR', 9);
+  static const Modifier GENERATOR = Modifier('GENERATOR', 10);
 
   /// Indicates that the pseudo-modifier 'get' was applied to the element.
-  static const Modifier GETTER = Modifier('GETTER', 10);
+  static const Modifier GETTER = Modifier('GETTER', 11);
 
   /// A flag used for libraries indicating that the defining compilation unit
   /// contains at least one import directive whose URI uses the "dart-ext"
   /// scheme.
-  static const Modifier HAS_EXT_URI = Modifier('HAS_EXT_URI', 11);
+  static const Modifier HAS_EXT_URI = Modifier('HAS_EXT_URI', 12);
 
   /// Indicates that the associated element did not have an explicit type
   /// associated with it. If the element is an [ExecutableElement], then the
   /// type being referred to is the return type.
-  static const Modifier IMPLICIT_TYPE = Modifier('IMPLICIT_TYPE', 12);
+  static const Modifier IMPLICIT_TYPE = Modifier('IMPLICIT_TYPE', 13);
 
   /// Indicates that modifier 'lazy' was applied to the element.
-  static const Modifier LATE = Modifier('LATE', 13);
+  static const Modifier LATE = Modifier('LATE', 14);
 
   /// Indicates that a class is a mixin application.
-  static const Modifier MIXIN_APPLICATION = Modifier('MIXIN_APPLICATION', 14);
+  static const Modifier MIXIN_APPLICATION = Modifier('MIXIN_APPLICATION', 15);
 
   /// Indicates that the pseudo-modifier 'set' was applied to the element.
-  static const Modifier SETTER = Modifier('SETTER', 15);
+  static const Modifier SETTER = Modifier('SETTER', 16);
 
   /// Indicates that the modifier 'static' was applied to the element.
-  static const Modifier STATIC = Modifier('STATIC', 16);
+  static const Modifier STATIC = Modifier('STATIC', 17);
 
   /// Indicates that the element does not appear in the source code but was
   /// implicitly created. For example, if a class does not define any
   /// constructors, an implicit zero-argument constructor will be created and it
   /// will be marked as being synthetic.
-  static const Modifier SYNTHETIC = Modifier('SYNTHETIC', 17);
+  static const Modifier SYNTHETIC = Modifier('SYNTHETIC', 18);
 
   static const List<Modifier> values = [
     ABSTRACT,
     ASYNCHRONOUS,
     CONST,
     COVARIANT,
+    DART_CORE_OBJECT,
     DEFERRED,
     ENUM,
     EXTERNAL,

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

@@ -10,7 +10,6 @@ import 'package:analyzer/src/dart/element/element.dart';
 import 'package:analyzer/src/dart/element/type_provider.dart';
 import 'package:analyzer/src/dart/resolver/scope.dart';
 import 'package:analyzer/src/summary/idl.dart';
-import 'package:analyzer/src/summary2/core_types.dart';
 import 'package:analyzer/src/summary2/lazy_ast.dart';
 import 'package:analyzer/src/summary2/linked_bundle_context.dart';
 import 'package:analyzer/src/summary2/linked_unit_context.dart';
@@ -22,8 +21,6 @@ class LinkedElementFactory {
   final Reference rootReference;
   final Map<String, LinkedLibraryContext> libraryMap = {};
 
-  CoreTypes _coreTypes;
-
   LinkedElementFactory(
     this.analysisContext,
     this.analysisSession,
@@ -34,10 +31,6 @@ class LinkedElementFactory {
     declareDartCoreDynamicNever();
   }
 
-  CoreTypes get coreTypes {
-    return _coreTypes ??= CoreTypes(this);
-  }
-
   Reference get dynamicRef {
     return rootReference.getChild('dart:core').getChild('dynamic');
   }

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

@@ -580,6 +580,21 @@ int b = a;
     ]);
   }
 
+  test_switchCase_implementsEquals_enum() async {
+    await assertNoErrorsInCode(r'''
+enum MyEnum {a, b, c}
+
+void f(MyEnum myEnum) {
+  switch (myEnum) {
+    case MyEnum.a:
+      break;
+    default:
+      break;
+  }
+}
+''');
+  }
+
   test_unknown_uri() async {
     await assertErrorsInCode(r'''
 import 'foo:bar';