[DAS] Makes EXTENSION_DECLARES_INSTANCE_FIELD trigger on all field names

[email protected], [email protected]

Fixes #59847

Change-Id: Ic4b41973d0d74d809d813ba57b85f50fab4c9a47
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/407080
Auto-Submit: Felipe Morschel <[email protected]>
Reviewed-by: Paul Berry <[email protected]>
Reviewed-by: Jens Johansen <[email protected]>
Commit-Queue: Jens Johansen <[email protected]>

Author: FMorschel

pkg/_fe_analyzer_shared/lib/src/messages/codes_generated.dart

@@ -4,8 +4,8 @@
 
 // NOTE: THIS FILE IS GENERATED. DO NOT EDIT.
 //
-// Instead modify 'pkg/front_end/messages.yaml' and run
-// 'pkg/front_end/tool/cfe generate-messages' to update.
+// Instead modify 'pkg/front_end/messages.yaml' and defer to it for the
+// commands to update this file.
 
 // ignore_for_file: lines_longer_than_80_chars
 
@@ -5380,7 +5380,7 @@ const Code<Null> codeExtensionAugmentationHasOnClause =
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const MessageCode messageExtensionAugmentationHasOnClause = const MessageCode(
   "ExtensionAugmentationHasOnClause",
-  index: 179,
+  index: 93,
   problemMessage: r"""Extension augmentations can't have 'on' clauses.""",
   correctionMessage: r"""Try removing the 'on' clause.""",
 );
@@ -5416,7 +5416,7 @@ const Code<Null> codeExtensionDeclaresInstanceField =
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const MessageCode messageExtensionDeclaresInstanceField = const MessageCode(
   "ExtensionDeclaresInstanceField",
-  index: 93,
+  analyzerCodes: <String>["EXTENSION_DECLARES_INSTANCE_FIELD"],
   problemMessage: r"""Extensions can't declare instance fields""",
   correctionMessage:
       r"""Try removing the field declaration or making it a static field""",

pkg/analysis_server/lib/src/services/correction/error_fix_status.yaml

@@ -651,6 +651,10 @@ CompileTimeErrorCode.EXTENSION_CONFLICTING_STATIC_AND_INSTANCE:
   status: noFix
 CompileTimeErrorCode.EXTENSION_DECLARES_MEMBER_OF_OBJECT:
   status: hasFix
+CompileTimeErrorCode.EXTENSION_DECLARES_INSTANCE_FIELD:
+  status: needsFix
+  notes: |-
+    Remove the field, or add `static`.
 CompileTimeErrorCode.EXTENSION_OVERRIDE_ACCESS_TO_STATIC_MEMBER:
   status: hasFix
 CompileTimeErrorCode.EXTENSION_OVERRIDE_ARGUMENT_NOT_ASSIGNABLE:
@@ -666,9 +670,9 @@ CompileTimeErrorCode.EXTENSION_TYPE_CONSTRUCTOR_WITH_SUPER_FORMAL_PARAMETER:
 CompileTimeErrorCode.EXTENSION_TYPE_CONSTRUCTOR_WITH_SUPER_INVOCATION:
   status: needsFix
   notes: |-
-    Remove it.
+    Remove the field, or add `static`.
 CompileTimeErrorCode.EXTENSION_TYPE_DECLARES_INSTANCE_FIELD:
-  status: noFix
+  status: needsFix
 CompileTimeErrorCode.EXTENSION_TYPE_DECLARES_MEMBER_OF_OBJECT:
   status: hasFix
 CompileTimeErrorCode.EXTENSION_TYPE_IMPLEMENTS_DISALLOWED_TYPE:
@@ -2771,10 +2775,6 @@ ParserErrorCode.EXTENSION_DECLARES_ABSTRACT_MEMBER:
     Provide an empty body for the member.
 ParserErrorCode.EXTENSION_DECLARES_CONSTRUCTOR:
   status: hasFix
-ParserErrorCode.EXTENSION_DECLARES_INSTANCE_FIELD:
-  status: needsFix
-  notes: |-
-    Remove the field, or add `static`.
 ParserErrorCode.EXTENSION_TYPE_EXTENDS:
   status: needsEvaluation
 ParserErrorCode.EXTENSION_TYPE_WITH:

pkg/analyzer/lib/src/dart/error/syntactic_errors.g.dart

@@ -114,7 +114,7 @@ final fastaAnalyzerErrorCodes = <ErrorCode?>[
   ParserErrorCode.INVALID_INITIALIZER,
   ParserErrorCode.ANNOTATION_WITH_TYPE_ARGUMENTS,
   ParserErrorCode.EXTENSION_DECLARES_CONSTRUCTOR,
-  ParserErrorCode.EXTENSION_DECLARES_INSTANCE_FIELD,
+  ParserErrorCode.EXTENSION_AUGMENTATION_HAS_ON_CLAUSE,
   ParserErrorCode.EXTENSION_DECLARES_ABSTRACT_MEMBER,
   ParserErrorCode.MIXIN_DECLARES_CONSTRUCTOR,
   ParserErrorCode.NULL_AWARE_CASCADE_OUT_OF_ORDER,
@@ -200,7 +200,6 @@ final fastaAnalyzerErrorCodes = <ErrorCode?>[
   ParserErrorCode.ABSTRACT_FINAL_BASE_CLASS,
   ParserErrorCode.ABSTRACT_FINAL_INTERFACE_CLASS,
   ParserErrorCode.EXTERNAL_CONSTRUCTOR_WITH_FIELD_INITIALIZERS,
-  ParserErrorCode.EXTENSION_AUGMENTATION_HAS_ON_CLAUSE,
 ];
 
 class ParserErrorCode extends ErrorCode {
@@ -752,16 +751,6 @@ class ParserErrorCode extends ErrorCode {
     hasPublishedDocs: true,
   );
 
-  ///  No parameters.
-  static const ParserErrorCode EXTENSION_DECLARES_INSTANCE_FIELD =
-      ParserErrorCode(
-    'EXTENSION_DECLARES_INSTANCE_FIELD',
-    "Extensions can't declare instance fields",
-    correctionMessage:
-        "Try removing the field declaration or making it a static field",
-    hasPublishedDocs: true,
-  );
-
   static const ParserErrorCode EXTENSION_TYPE_EXTENDS = ParserErrorCode(
     'EXTENSION_TYPE_EXTENDS',
     "An extension type declaration can't have an 'extends' clause.",

pkg/analyzer/lib/src/error/codes.g.dart

@@ -1745,6 +1745,15 @@ class CompileTimeErrorCode extends ErrorCode {
     hasPublishedDocs: true,
   );
 
+  ///  No parameters.
+  static const CompileTimeErrorCode EXTENSION_DECLARES_INSTANCE_FIELD =
+      CompileTimeErrorCode(
+    'EXTENSION_DECLARES_INSTANCE_FIELD',
+    "Extensions can't declare instance fields.",
+    correctionMessage: "Try replacing the field with a getter.",
+    hasPublishedDocs: true,
+  );
+
   ///  No parameters.
   static const CompileTimeErrorCode EXTENSION_DECLARES_MEMBER_OF_OBJECT =
       CompileTimeErrorCode(

pkg/analyzer/lib/src/error/error_code_values.g.dart

@@ -208,6 +208,7 @@ const List<ErrorCode> errorCodeValues = [
   CompileTimeErrorCode.EXTENDS_TYPE_ALIAS_EXPANDS_TO_TYPE_PARAMETER,
   CompileTimeErrorCode.EXTENSION_AS_EXPRESSION,
   CompileTimeErrorCode.EXTENSION_CONFLICTING_STATIC_AND_INSTANCE,
+  CompileTimeErrorCode.EXTENSION_DECLARES_INSTANCE_FIELD,
   CompileTimeErrorCode.EXTENSION_DECLARES_MEMBER_OF_OBJECT,
   CompileTimeErrorCode.EXTENSION_OVERRIDE_ACCESS_TO_STATIC_MEMBER,
   CompileTimeErrorCode.EXTENSION_OVERRIDE_ARGUMENT_NOT_ASSIGNABLE,
@@ -735,7 +736,6 @@ const List<ErrorCode> errorCodeValues = [
   ParserErrorCode.EXTENSION_AUGMENTATION_HAS_ON_CLAUSE,
   ParserErrorCode.EXTENSION_DECLARES_ABSTRACT_MEMBER,
   ParserErrorCode.EXTENSION_DECLARES_CONSTRUCTOR,
-  ParserErrorCode.EXTENSION_DECLARES_INSTANCE_FIELD,
   ParserErrorCode.EXTENSION_TYPE_EXTENDS,
   ParserErrorCode.EXTENSION_TYPE_WITH,
   ParserErrorCode.EXTERNAL_CLASS,

pkg/analyzer/lib/src/fasta/error_converter.dart

@@ -141,6 +141,10 @@ class FastaErrorReporter {
           errorCode: ParserErrorCode.EXPECTED_TYPE_NAME,
         );
         return;
+      case "EXTENSION_DECLARES_INSTANCE_FIELD":
+        // Reported by
+        // [ErrorVerifier._checkForExtensionDeclaresInstanceField]
+        return;
       case "FIELD_INITIALIZER_REDIRECTING_CONSTRUCTOR":
         errorReporter?.atOffset(
           offset: offset,
@@ -517,7 +521,7 @@ class FastaErrorReporter {
         return;
       case "ABSTRACT_EXTENSION_FIELD":
         // Not reported but followed by a
-        // ParserErrorCode.EXTENSION_DECLARES_INSTANCE_FIELD.
+        // CompileTimeErrorCode.EXTENSION_DECLARES_INSTANCE_FIELD.
         return;
       case "EXTENSION_TYPE_WITH_ABSTRACT_MEMBER":
         // Reported by [ErrorVerifier._checkForExtensionTypeWithAbstractMember].

pkg/analyzer/lib/src/generated/error_verifier.dart

@@ -885,6 +885,7 @@ class ErrorVerifier extends RecursiveAstVisitor<void>
     var oldHasAccessToThis = _hasAccessToThis;
     try {
       _hasAccessToThis = !node.isStatic && node.fields.isLate;
+      _checkForExtensionDeclaresInstanceField(node);
       _checkForExtensionTypeDeclaresInstanceField(node);
       _checkForNotInitializedNonNullableStaticField(node);
       _checkForWrongTypeParameterVarianceInField(node);
@@ -3389,6 +3390,23 @@ class ErrorVerifier extends RecursiveAstVisitor<void>
         _typeProvider.isNonSubtypableClass(type.element);
   }
 
+  void _checkForExtensionDeclaresInstanceField(FieldDeclaration node) {
+    if (node.parent is! ExtensionDeclaration) {
+      return;
+    }
+
+    if (node.isStatic || node.externalKeyword != null) {
+      return;
+    }
+
+    for (var field in node.fields.variables) {
+      errorReporter.atToken(
+        field.name,
+        CompileTimeErrorCode.EXTENSION_DECLARES_INSTANCE_FIELD,
+      );
+    }
+  }
+
   void _checkForExtensionDeclaresMemberOfObject(MethodDeclaration node) {
     if (_enclosingExtension != null) {
       if (node.hasObjectMemberName) {

pkg/analyzer/messages.yaml

@@ -4,7 +4,7 @@
 
 # Run
 #
-#     dart run analyzer/tool/messages/generate.dart
+#     dart run pkg/analyzer/tool/messages/generate.dart
 #
 # to regenerate messages after having edited this file.
 
@@ -5111,6 +5111,61 @@ CompileTimeErrorCode:
         static int b() => 0;
       }
       ```
+  EXTENSION_DECLARES_INSTANCE_FIELD:
+    problemMessage: "Extensions can't declare instance fields."
+    correctionMessage: Try replacing the field with a getter.
+    hasPublishedDocs: true
+    comment: No parameters.
+    documentation: |-
+      #### Description
+
+      The analyzer produces this diagnostic when an instance field declaration is
+      found in an extension. It isn't valid to define an instance field because
+      extensions can only add behavior, not state.
+
+      #### Example
+
+      The following code produces this diagnostic because `s` is an instance
+      field:
+
+      ```dart
+      %language=2.9
+      extension E on String {
+        String [!s!];
+      }
+      ```
+
+      #### Common fixes
+
+      If the value can be computed without storing it in a field, then try using a getter or a method:
+
+      ```dart
+      extension E on String {
+        String get s => '';
+
+        void s(String value) => print(s);
+      }
+      ```
+
+      If the value must be stored, but is the same for every instance, try using a static field:
+
+      ```dart
+      extension E on String {
+        static String s = '';
+      }
+      ```
+
+      If each instance needs to have its own value stored, then try using a getter and setter pair backed by a static Expando:
+
+      ```dart
+      extension E on SomeType {
+        static final _s = Expando<String>();
+
+        String get s => _s[this] ?? '';
+        set s(String value) => _s[this] = value;
+      }
+      ```
+
   EXTENSION_DECLARES_MEMBER_OF_OBJECT:
     problemMessage: "Extensions can't declare members with the same name as a member declared by 'Object'."
     correctionMessage: Try specifying a different name for the member.

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

@@ -2,7 +2,6 @@
 // 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/dart/error/syntactic_errors.dart';
 import 'package:analyzer/src/error/codes.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
@@ -246,7 +245,7 @@ extension<U> on A<U> {
 ''', [
       // An instance field is illegal, but we should not also report an
       // additional error for the type variable.
-      error(ParserErrorCode.EXTENSION_DECLARES_INSTANCE_FIELD, 63, 1),
+      error(CompileTimeErrorCode.EXTENSION_DECLARES_INSTANCE_FIELD, 63, 1),
     ]);
   }
 

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

@@ -2,7 +2,7 @@
 // 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/dart/error/syntactic_errors.dart';
+import 'package:analyzer/src/error/codes.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import '../dart/resolution/context_collection_resolution.dart';
@@ -15,15 +15,19 @@ main() {
 
 @reflectiveTest
 class ExtensionDeclaresFieldTest extends PubPackageResolutionTest {
-  test_multiple() async {
+  Future<void> test_multiple() async {
     await assertErrorsInCode('''
 extension E on String {
   String? one, two, three;
 }
-''', [error(ParserErrorCode.EXTENSION_DECLARES_INSTANCE_FIELD, 34, 3)]);
+''', [
+      error(CompileTimeErrorCode.EXTENSION_DECLARES_INSTANCE_FIELD, 34, 3),
+      error(CompileTimeErrorCode.EXTENSION_DECLARES_INSTANCE_FIELD, 39, 3),
+      error(CompileTimeErrorCode.EXTENSION_DECLARES_INSTANCE_FIELD, 44, 5),
+    ]);
   }
 
-  test_none() async {
+  Future<void> test_none() async {
     await assertNoErrorsInCode('''
 extension E on String {}
 ''');
@@ -34,10 +38,10 @@ extension E on String {}
 extension E on String {
   String? s;
 }
-''', [error(ParserErrorCode.EXTENSION_DECLARES_INSTANCE_FIELD, 34, 1)]);
+''', [error(CompileTimeErrorCode.EXTENSION_DECLARES_INSTANCE_FIELD, 34, 1)]);
   }
 
-  test_static() async {
+  Future<void> test_static() async {
     await assertNoErrorsInCode('''
 extension E on String {
   static String EMPTY = '';