invalid @doNotStore assignment analysis

Another pass at https://dart-review.googlesource.com/c/sdk/+/159841 (reverted) with a guarding type-check.



Change-Id: Ia270be4e880d71642a96c5ab93a306efba1ceedb
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/160961
Commit-Queue: Phil Quitslund <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>

pkg/analyzer/lib/error/error.dart

@@ -465,6 +465,7 @@ const List<ErrorCode> errorCodeValues = [
   FfiCode.SUBTYPE_OF_STRUCT_CLASS_IN_EXTENDS,
   FfiCode.SUBTYPE_OF_STRUCT_CLASS_IN_IMPLEMENTS,
   FfiCode.SUBTYPE_OF_STRUCT_CLASS_IN_WITH,
+  HintCode.ASSIGNMENT_OF_DO_NOT_STORE,
   HintCode.CAN_BE_NULL_AFTER_NULL_AWARE,
   HintCode.DEAD_CODE,
   HintCode.DEAD_CODE_CATCH_FOLLOWING_CATCH,

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

@@ -7,6 +7,26 @@ import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/src/dart/element/element.dart';
 import 'package:analyzer/src/generated/utilities_dart.dart';
 
+extension ElementExtension on Element {
+  /// Return `true` if this element, the enclosing class (if there is one), or
+  /// the enclosing library, has been annotated with the `@doNotStore`
+  /// annotation.
+  bool get hasOrInheritsDoNotStore {
+    if (hasDoNotStore) {
+      return true;
+    }
+    var ancestor = enclosingElement;
+    if (ancestor is ClassElement || ancestor is ExtensionElement) {
+      if (ancestor.hasDoNotStore) {
+        return true;
+      }
+      ancestor = ancestor.enclosingElement;
+    }
+    return ancestor is CompilationUnitElement &&
+        ancestor.enclosingElement.hasDoNotStore;
+  }
+}
+
 extension ParameterElementExtensions on ParameterElement {
   /// Return [ParameterElement] with the specified properties replaced.
   ParameterElement copyWith({DartType type, ParameterKind kind}) {

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

@@ -14,6 +14,14 @@ import 'package:analyzer/src/error/analyzer_error_code.dart';
  * mentioned in the Dart Language Specification.
  */
 class HintCode extends AnalyzerErrorCode {
+  /**
+   * Users should not assign values marked `@doNotStore`.
+   */
+  static const HintCode ASSIGNMENT_OF_DO_NOT_STORE = HintCode(
+      'ASSIGNMENT_OF_DO_NOT_STORE',
+      "'{0}' is marked 'doNotStore' and shouldn't be assigned to a field.",
+      correction: "Try removing the assignment.");
+
   /**
    * When the target expression uses '?.' operator, it can be `null`, so all the
    * subsequent invocations should also use '?.' operator.

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

@@ -14,6 +14,7 @@ import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/dart/element/type_provider.dart';
 import 'package:analyzer/error/listener.dart';
 import 'package:analyzer/src/dart/element/element.dart';
+import 'package:analyzer/src/dart/element/extensions.dart';
 import 'package:analyzer/src/dart/element/inheritance_manager3.dart';
 import 'package:analyzer/src/dart/element/member.dart' show ExecutableMember;
 import 'package:analyzer/src/dart/element/type.dart';
@@ -359,6 +360,37 @@ class BestPracticesVerifier extends RecursiveAstVisitor<void> {
               field.name,
               [field.name, overriddenElement.enclosingElement.name]);
         }
+
+        var expression = field.initializer;
+
+        Element element;
+        if (expression is PropertyAccess) {
+          element = expression.propertyName.staticElement;
+          // Tear-off.
+          if (element is FunctionElement || element is MethodElement) {
+            element = null;
+          }
+        } else if (expression is MethodInvocation) {
+          element = expression.methodName.staticElement;
+        } else if (expression is Identifier) {
+          element = expression.staticElement;
+          // Tear-off.
+          if (element is FunctionElement || element is MethodElement) {
+            element = null;
+          }
+        }
+        if (element != null) {
+          if (element is PropertyAccessorElement && element.isSynthetic) {
+            element = (element as PropertyAccessorElement).variable;
+          }
+          if (element.hasOrInheritsDoNotStore) {
+            _errorReporter.reportErrorForNode(
+              HintCode.ASSIGNMENT_OF_DO_NOT_STORE,
+              expression,
+              [element.name],
+            );
+          }
+        }
       }
     } finally {
       _inDeprecatedMember = wasInDeprecatedMember;

pkg/analyzer/lib/src/test_utilities/mock_packages.dart

@@ -25,6 +25,7 @@ class JS {
 library meta;
 
 const _AlwaysThrows alwaysThrows = const _AlwaysThrows();
+const _DoNotStore doNotStore = _DoNotStore();
 const _Factory factory = const _Factory();
 const Immutable immutable = const Immutable();
 const _Literal literal = const _Literal();
@@ -36,16 +37,19 @@ const Required required = const Required();
 const _Sealed sealed = const _Sealed();
 const _VisibleForTesting visibleForTesting = const _VisibleForTesting();
 
-class Immutable {
-  final String reason;
-  const Immutable([this.reason]);
-}
 class _AlwaysThrows {
   const _AlwaysThrows();
 }
+class _DoNotStore {
+  const _DoNotStore();
+}
 class _Factory {
   const _Factory();
 }
+class Immutable {
+  final String reason;
+  const Immutable([this.reason]);
+}
 class _Literal {
   const _Literal();
 }

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

@@ -0,0 +1,179 @@
+// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:analyzer/src/error/codes.dart';
+import 'package:test_reflective_loader/test_reflective_loader.dart';
+
+import '../dart/resolution/context_collection_resolution.dart';
+
+main() {
+  defineReflectiveSuite(() {
+    defineReflectiveTests(AssignmentOfDoNotStoreTest);
+  });
+}
+
+@reflectiveTest
+class AssignmentOfDoNotStoreTest extends PubPackageResolutionTest {
+  @override
+  void setUp() {
+    super.setUp();
+    writeTestPackageConfigWithMeta();
+  }
+
+  test_classMemberGetter() async {
+    await assertErrorsInCode('''
+import 'package:meta/meta.dart';
+
+class A {
+  @doNotStore
+  String get v => '';
+}
+
+class B {
+  String f = A().v;
+}
+''', [
+      error(HintCode.ASSIGNMENT_OF_DO_NOT_STORE, 106, 5),
+    ]);
+  }
+
+  test_classMemberVariable() async {
+    await assertErrorsInCode('''
+import 'package:meta/meta.dart';
+
+class A{
+  @doNotStore
+  final f = '';
+}
+
+class B {
+  String f = A().f;
+}
+''', [
+      error(HintCode.ASSIGNMENT_OF_DO_NOT_STORE, 99, 5),
+    ]);
+  }
+
+  test_classStaticGetter() async {
+    await assertErrorsInCode('''
+import 'package:meta/meta.dart';
+
+class A {
+  @doNotStore
+  static String get v => '';
+}
+
+class B {
+  String f = A.v;
+}
+''', [
+      error(HintCode.ASSIGNMENT_OF_DO_NOT_STORE, 113, 3),
+    ]);
+  }
+
+  test_classStaticVariable() async {
+    await assertErrorsInCode('''
+import 'package:meta/meta.dart';
+
+class A{
+  @doNotStore
+  static final f = '';
+}
+
+class B {
+  String f = A.f;
+}
+''', [
+      error(HintCode.ASSIGNMENT_OF_DO_NOT_STORE, 106, 3),
+    ]);
+  }
+
+  test_functionAssignment() async {
+    await assertNoErrorsInCode('''
+import 'package:meta/meta.dart';
+
+@doNotStore
+String g(int i) => '';
+
+class C {
+  String Function(int) f = g;
+}
+''');
+  }
+
+  test_functionReturnValue() async {
+    await assertErrorsInCode('''
+import 'package:meta/meta.dart';
+
+@doNotStore
+String getV() => '';
+
+class A {
+  final f = getV();
+}
+''', [
+      error(HintCode.ASSIGNMENT_OF_DO_NOT_STORE, 90, 6),
+    ]);
+  }
+
+  test_methodReturnValue() async {
+    await assertErrorsInCode('''
+import 'package:meta/meta.dart';
+
+class A {
+  @doNotStore
+  String getV() => '';
+}
+
+class B {
+  final f = A().getV();
+}
+''', [
+      error(HintCode.ASSIGNMENT_OF_DO_NOT_STORE, 106, 10),
+    ]);
+  }
+
+  test_tearOff() async {
+    await assertNoErrorsInCode('''
+import 'package:meta/meta.dart';
+
+@doNotStore
+String getV() => '';
+
+class A {
+  final f = getV;
+}
+''');
+  }
+
+  test_topLevelGetter() async {
+    await assertErrorsInCode('''
+import 'package:meta/meta.dart';
+
+@doNotStore
+String get v => '';
+
+class A {
+  final f = v;
+}
+''', [
+      error(HintCode.ASSIGNMENT_OF_DO_NOT_STORE, 89, 1),
+    ]);
+  }
+
+  test_topLevelVariable() async {
+    await assertErrorsInCode('''
+import 'package:meta/meta.dart';
+
+@doNotStore
+final v = '';
+
+class A {
+  final f = v;
+}
+''', [
+      error(HintCode.ASSIGNMENT_OF_DO_NOT_STORE, 83, 1),
+    ]);
+  }
+}

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

@@ -22,6 +22,7 @@ import 'annotation_with_non_class_test.dart' as annotation_with_non_class;
 import 'argument_type_not_assignable_test.dart' as argument_type_not_assignable;
 import 'assert_in_redirecting_constructor_test.dart'
     as assert_in_redirecting_constructor;
+import 'assignment_of_do_not_store_test.dart' as assignment_of_do_not_store;
 import 'assignment_to_const_test.dart' as assignment_to_const;
 import 'assignment_to_final_local_test.dart' as assignment_to_final_local;
 import 'assignment_to_final_no_setter_test.dart'
@@ -653,6 +654,7 @@ main() {
     annotation_with_non_class.main();
     argument_type_not_assignable.main();
     assert_in_redirecting_constructor.main();
+    assignment_of_do_not_store.main();
     assignment_to_const.main();
     assignment_to_final_local.main();
     assignment_to_final_no_setter.main();