analyzer: ban deprecated-functionality annotations on private declarations.

In each case, the functionality which is presumably being deprecated
is already non-existing (like extending a class outside of its library).
So in each case we should report the annotation as nonsensical.

Change-Id: Idbe36f543dfe76da4f1f8da3eaaf76bb97a58634
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/448241
Commit-Queue: Samuel Rawlins <[email protected]>
Reviewed-by: Konstantin Shcheglov <[email protected]>

Author: srawlins

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

@@ -144,7 +144,8 @@ class AnnotationVerifier {
     }
 
     if (declaredElement is ClassElement) {
-      if (declaredElement.isExtendableOutside &&
+      if (declaredElement.isPublic &&
+          declaredElement.isExtendableOutside &&
           declaredElement.hasGenerativeConstructor) {
         return;
       }
@@ -169,9 +170,11 @@ class AnnotationVerifier {
     }
 
     if (declaredElement is ClassElement &&
+        declaredElement.isPublic &&
         declaredElement.isImplementableOutside) {
       return;
     } else if (declaredElement is MixinElement &&
+        declaredElement.isPublic &&
         declaredElement.isImplementableOutside) {
       return;
     }
@@ -192,11 +195,11 @@ class AnnotationVerifier {
       declaredElement = parent.type.type?.element;
     }
 
-    if (declaredElement is ClassElement) {
-      if (!declaredElement.isAbstract &&
-          declaredElement.hasGenerativeConstructor) {
-        return;
-      }
+    if (declaredElement is ClassElement &&
+        declaredElement.isPublic &&
+        !declaredElement.isAbstract &&
+        declaredElement.hasGenerativeConstructor) {
+      return;
     }
 
     _diagnosticReporter.atNode(
@@ -206,7 +209,11 @@ class AnnotationVerifier {
   }
 
   void _checkDeprecatedMixin(Annotation node, AstNode parent) {
-    if (parent is ClassDeclaration && parent.mixinKeyword != null) return;
+    if (parent is ClassDeclaration &&
+        parent.declaredFragment!.element.isPublic &&
+        parent.mixinKeyword != null) {
+      return;
+    }
 
     _diagnosticReporter.atNode(
       node.name,
@@ -227,10 +234,12 @@ class AnnotationVerifier {
     }
 
     if (declaredElement is ClassElement &&
+        declaredElement.isPublic &&
         (declaredElement.isImplementableOutside ||
             declaredElement.isExtendableOutside)) {
       return;
     } else if (declaredElement is MixinElement &&
+        declaredElement.isPublic &&
         declaredElement.isImplementableOutside) {
       return;
     }

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

@@ -54,6 +54,19 @@ class C {
     );
   }
 
+  test_class_private() async {
+    await assertErrorsInCode(
+      r'''
+@Deprecated.extend()
+class _C {}
+''',
+      [
+        error(WarningCode.invalidDeprecatedExtendAnnotation, 1, 17),
+        error(WarningCode.unusedElement, 27, 2),
+      ],
+    );
+  }
+
   test_class_sealed() async {
     await assertErrorsInCode(
       r'''

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

@@ -43,6 +43,19 @@ final class C {}
     );
   }
 
+  test_class_private() async {
+    await assertErrorsInCode(
+      r'''
+@Deprecated.implement()
+class _C {}
+''',
+      [
+        error(WarningCode.invalidDeprecatedImplementAnnotation, 1, 20),
+        error(WarningCode.unusedElement, 30, 2),
+      ],
+    );
+  }
+
   test_class_sealed() async {
     await assertErrorsInCode(
       r'''
@@ -88,6 +101,19 @@ base mixin M {}
     );
   }
 
+  test_mixin_private() async {
+    await assertErrorsInCode(
+      r'''
+@Deprecated.implement()
+mixin _M {}
+''',
+      [
+        error(WarningCode.invalidDeprecatedImplementAnnotation, 1, 20),
+        error(WarningCode.unusedElement, 30, 2),
+      ],
+    );
+  }
+
   test_typeAlias_forClass() async {
     await assertNoErrorsInCode(r'''
 class C {}

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

@@ -33,6 +33,19 @@ abstract class C {}
     );
   }
 
+  test_class_private() async {
+    await assertErrorsInCode(
+      r'''
+@Deprecated.instantiate()
+class _C {}
+''',
+      [
+        error(WarningCode.invalidDeprecatedInstantiateAnnotation, 1, 22),
+        error(WarningCode.unusedElement, 32, 2),
+      ],
+    );
+  }
+
   test_class_privateConstructor() async {
     await assertErrorsInCode(
       r'''

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

@@ -22,6 +22,19 @@ mixin class C {}
 ''');
   }
 
+  test_class_mixin_private() async {
+    await assertErrorsInCode(
+      r'''
+@Deprecated.mixin()
+mixin class _C {}
+''',
+      [
+        error(WarningCode.invalidDeprecatedMixinAnnotation, 1, 16),
+        error(WarningCode.unusedElement, 32, 2),
+      ],
+    );
+  }
+
   test_class_noMixin() async {
     await assertErrorsInCode(
       r'''

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

@@ -32,6 +32,19 @@ final class C {}
     );
   }
 
+  test_class_private() async {
+    await assertErrorsInCode(
+      r'''
+@Deprecated.subclass()
+class _C {}
+''',
+      [
+        error(WarningCode.invalidDeprecatedSubclassAnnotation, 1, 19),
+        error(WarningCode.unusedElement, 29, 2),
+      ],
+    );
+  }
+
   test_class_sealed() async {
     await assertErrorsInCode(
       r'''
@@ -69,6 +82,19 @@ base mixin M {}
     );
   }
 
+  test_mixin_private() async {
+    await assertErrorsInCode(
+      r'''
+@Deprecated.subclass()
+mixin _M {}
+''',
+      [
+        error(WarningCode.invalidDeprecatedSubclassAnnotation, 1, 19),
+        error(WarningCode.unusedElement, 29, 2),
+      ],
+    );
+  }
+
   test_typeAlias_ofClass() async {
     await assertNoErrorsInCode(r'''
 class C {}