enforce @redeclare annotation target restrictions

See: #53121

Change-Id: I994aac6c733704ac7adc4a7923ee733cdc77aacb
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/319561
Commit-Queue: Phil Quitslund <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>

Author: pq

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

@@ -849,7 +849,10 @@ abstract class ElementAnnotation implements ConstantEvaluationTarget {
   /// object.
   bool get isProxy;
 
-  /// Whether the marks the associated member as being reopened.
+  /// Whether the annotation marks the associated member as redeclaring.
+  bool get isRedeclare;
+
+  /// Whether the annotation marks the associated member as being reopened.
   bool get isReopen;
 
   /// Whether the annotation marks the associated member as being required.

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

@@ -1556,6 +1556,9 @@ class ElementAnnotationImpl implements ElementAnnotation {
   /// protected.
   static const String _protectedVariableName = 'protected';
 
+  /// The name of the top-level variable used to mark a member as redeclaring.
+  static const String _redeclareVariableName = 'redeclare';
+
   /// The name of the top-level variable used to mark a class or mixin as being
   /// reopened.
   static const String _reopenVariableName = 'reopen';
@@ -1710,6 +1713,9 @@ class ElementAnnotationImpl implements ElementAnnotation {
   @override
   bool get isProxy => false;
 
+  @override
+  bool get isRedeclare => _isPackageMetaGetter(_redeclareVariableName);
+
   @override
   bool get isReopen => _isPackageMetaGetter(_reopenVariableName);
 

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

@@ -54,6 +54,8 @@ class AnnotationVerifier {
       _checkNonVirtual(node);
     } else if (element.isReopen) {
       _checkReopen(node);
+    } else if (element.isRedeclare) {
+      _checkRedeclare(node);
     } else if (element.isSealed) {
       _checkSealed(node);
     } else if (element.isUseResult) {
@@ -254,6 +256,20 @@ class AnnotationVerifier {
     }
   }
 
+  /// Reports a warning if [parent] is not a valid target for a
+  /// `@redeclare` annotation.
+  void _checkRedeclare(Annotation node) {
+    var parent = node.parent;
+    if (parent.parent is! ExtensionTypeDeclaration ||
+        parent is MethodDeclaration && parent.isStatic) {
+      _errorReporter.reportErrorForNode(
+        WarningCode.INVALID_ANNOTATION_TARGET,
+        node,
+        [node.name.name, 'instance members of extension types'],
+      );
+    }
+  }
+
   /// Reports a warning if [parent] is not a valid target for a `@reopen`
   /// annotation.
   void _checkReopen(AstNode node) {

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

@@ -11,6 +11,7 @@ main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(InvalidAnnotationTarget_MustBeOverriddenTest);
     defineReflectiveTests(InvalidAnnotationTarget_MustCallSuperTest);
+    defineReflectiveTests(InvalidAnnotationTarget_RedeclareTest);
     defineReflectiveTests(InvalidAnnotationTargetTest);
   });
 }
@@ -343,6 +344,124 @@ void m() {}
   }
 }
 
+@reflectiveTest
+class InvalidAnnotationTarget_RedeclareTest extends PubPackageResolutionTest {
+  @override
+  void setUp() {
+    super.setUp();
+    writeTestPackageConfigWithMeta();
+  }
+
+  test_class_instance_method() async {
+    await assertErrorsInCode(r'''
+import 'package:meta/meta.dart';
+
+class C {
+  @redeclare
+  void m() {}
+}
+''', [
+      error(WarningCode.INVALID_ANNOTATION_TARGET, 46, 10),
+    ]);
+  }
+
+  test_extensionType_instance_getter() async {
+    await assertNoErrorsInCode(r'''
+import 'package:meta/meta.dart';
+
+class C {
+  int get g => 0; 
+}
+
+extension type E(C c) {
+  @redeclare
+  int get g => 0; 
+}
+''');
+  }
+
+  test_extensionType_instance_method() async {
+    await assertNoErrorsInCode(r'''
+import 'package:meta/meta.dart';
+
+class C {
+  void m() {}
+}
+
+extension type E(C c) {
+  @redeclare
+  void m() {}
+}
+''');
+  }
+
+  test_extensionType_instance_setter() async {
+    await assertNoErrorsInCode(r'''
+import 'package:meta/meta.dart';
+
+class C {
+  set g(int i) {}
+}
+
+extension type E(C c) {
+  @redeclare
+  set g(int i) {}
+}
+''');
+  }
+
+  test_extensionType_static_getter() async {
+    await assertErrorsInCode(r'''
+import 'package:meta/meta.dart';
+
+class C {
+  static int get g => 0; 
+}
+
+extension type E(C c) {
+  @redeclare
+  static int get g => 0; 
+}
+''', [
+      error(WarningCode.INVALID_ANNOTATION_TARGET, 99, 10),
+    ]);
+  }
+
+  test_extensionType_static_method() async {
+    await assertErrorsInCode(r'''
+import 'package:meta/meta.dart';
+
+class C {
+  static void m() {}
+}
+
+extension type E(C c) {
+  @redeclare
+  static void m() {}
+}
+''', [
+      error(WarningCode.INVALID_ANNOTATION_TARGET, 94, 10),
+    ]);
+  }
+
+  test_extensionType_static_setter() async {
+    await assertErrorsInCode(r'''
+import 'package:meta/meta.dart';
+
+class C {
+  static set g(int i) {}
+}
+
+extension type E(C c) {
+  @redeclare
+  static set g(int i) {}
+}
+''', [
+      error(WarningCode.INVALID_ANNOTATION_TARGET, 98, 10),
+    ]);
+  }
+}
+
 @reflectiveTest
 class InvalidAnnotationTargetTest extends PubPackageResolutionTest {
   @override