Don't report unimplemented abstract for 'index' in enum.

Bug: https://github.com/dart-lang/sdk/issues/48438
Change-Id: I5d6357ce0dcff872a2f4b356359a19554833bf97
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/233968
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>

pkg/analyzer/lib/src/error/inheritance_override.dart

@@ -242,10 +242,16 @@ class _ClassVerifier {
 
         // No concrete implementation of the name.
         if (concreteElement == null) {
-          if (!_reportConcreteClassWithAbstractMember(name.name)) {
-            inheritedAbstract ??= [];
-            inheritedAbstract.add(interfaceElement);
+          if (_reportConcreteClassWithAbstractMember(name.name)) {
+            continue;
           }
+          // We already reported ILLEGAL_ENUM_VALUES_INHERITANCE.
+          if (classElement.isEnum &&
+              const {'values', 'values='}.contains(name.name)) {
+            continue;
+          }
+          inheritedAbstract ??= [];
+          inheritedAbstract.add(interfaceElement);
           continue;
         }
 

pkg/analyzer/test/src/diagnostics/illegal_enum_values_inheritance_test.dart

@@ -87,7 +87,35 @@ abstract class B extends A implements Enum {}
     ]);
   }
 
-  test_enum_method() async {
+  test_enum_getter_fromImplements() async {
+    await assertErrorsInCode(r'''
+class A {
+  int get values => 0;
+}
+
+enum E implements A {
+  v
+}
+''', [
+      error(CompileTimeErrorCode.ILLEGAL_ENUM_VALUES_INHERITANCE, 41, 1),
+    ]);
+  }
+
+  test_enum_method_fromImplements() async {
+    await assertErrorsInCode(r'''
+class A {
+  int values() => 0;
+}
+
+enum E implements A {
+  v
+}
+''', [
+      error(CompileTimeErrorCode.ILLEGAL_ENUM_VALUES_INHERITANCE, 39, 1),
+    ]);
+  }
+
+  test_enum_method_fromWith() async {
     await assertErrorsInCode(r'''
 mixin M {
   int values() => 0;
@@ -101,6 +129,34 @@ enum E with M {
     ]);
   }
 
+  test_enum_setter_fromImplements() async {
+    await assertErrorsInCode(r'''
+class A {
+  set values(int _) {}
+}
+
+enum E implements A {
+  v
+}
+''', [
+      error(CompileTimeErrorCode.ILLEGAL_ENUM_VALUES_INHERITANCE, 41, 1),
+    ]);
+  }
+
+  test_enum_setter_fromWith() async {
+    await assertErrorsInCode(r'''
+mixin M {
+  set values(int _) {}
+}
+
+enum E with M {
+  v
+}
+''', [
+      error(CompileTimeErrorCode.ILLEGAL_ENUM_VALUES_INHERITANCE, 41, 1),
+    ]);
+  }
+
   test_mixin_field() async {
     await assertErrorsInCode(r'''
 class A {