Extension types. Report when implemented extension type representation is not a supertype of the declared extention type.

Change-Id: Iebb19c3f57046db600305993cc69dae04946889d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/319861
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Konstantin Shcheglov <[email protected]>

Author: scheglov

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

@@ -656,6 +656,8 @@ CompileTimeErrorCode.EXTENSION_TYPE_IMPLEMENTS_ITSELF:
   status: noFix
 CompileTimeErrorCode.EXTENSION_TYPE_IMPLEMENTS_NOT_SUPERTYPE_OF_ERASURE:
   status: noFix
+CompileTimeErrorCode.EXTENSION_TYPE_IMPLEMENTS_REPRESENTATION_NOT_SUPERTYPE:
+  status: noFix
 CompileTimeErrorCode.EXTENSION_TYPE_INHERITED_MEMBER_CONFLICT:
   status: noFix
 CompileTimeErrorCode.EXTENSION_TYPE_REPRESENTATION_DEPENDS_ON_ITSELF:

pkg/analyzer/lib/src/dart/resolver/resolution_visitor.dart

@@ -1780,17 +1780,39 @@ class ResolutionVisitor extends RecursiveAstVisitor<void> {
       return;
     }
 
-    if (type.element is! ExtensionTypeElement) {
-      final erasure = declaredElement.typeErasure;
-      if (!typeSystem.isSubtypeOf(erasure, type)) {
-        _errorReporter.reportErrorForNode(
-          CompileTimeErrorCode
-              .EXTENSION_TYPE_IMPLEMENTS_NOT_SUPERTYPE_OF_ERASURE,
-          node,
-          [type, erasure],
-        );
+    // When `type` is an extension type.
+    if (type is InterfaceTypeImpl) {
+      final implementedRepresentation = type.representationType;
+      if (implementedRepresentation != null) {
+        final declaredRepresentation = declaredElement.representation.type;
+        if (!typeSystem.isSubtypeOf(
+          declaredRepresentation,
+          implementedRepresentation,
+        )) {
+          _errorReporter.reportErrorForNode(
+            CompileTimeErrorCode
+                .EXTENSION_TYPE_IMPLEMENTS_REPRESENTATION_NOT_SUPERTYPE,
+            node,
+            [
+              implementedRepresentation,
+              type.element.name,
+              declaredRepresentation,
+              declaredElement.name,
+            ],
+          );
+        }
+        return;
       }
     }
+
+    final erasure = declaredElement.typeErasure;
+    if (!typeSystem.isSubtypeOf(erasure, type)) {
+      _errorReporter.reportErrorForNode(
+        CompileTimeErrorCode.EXTENSION_TYPE_IMPLEMENTS_NOT_SUPERTYPE_OF_ERASURE,
+        node,
+        [type, erasure],
+      );
+    }
   }
 
   void _visitIf(IfElementOrStatementImpl node) {

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

@@ -1663,6 +1663,21 @@ class CompileTimeErrorCode extends AnalyzerErrorCode {
         "Try specifying a different type, or remove the type from the list.",
   );
 
+  ///  Parameters:
+  ///  0: the representation type of the implemented extension type
+  ///  1: the name of the implemented extension type
+  ///  2: the representation type of the this extension type
+  ///  3: the name of the this extension type
+  static const CompileTimeErrorCode
+      EXTENSION_TYPE_IMPLEMENTS_REPRESENTATION_NOT_SUPERTYPE =
+      CompileTimeErrorCode(
+    'EXTENSION_TYPE_IMPLEMENTS_REPRESENTATION_NOT_SUPERTYPE',
+    "'{0}', the representation type of '{1}', is not a supertype of '{2}', the "
+        "representation type of '{3}'.",
+    correctionMessage:
+        "Try specifying a different type, or remove the type from the list.",
+  );
+
   ///  Parameters:
   ///  0: the name of the extension type
   ///  1: the name of the conflicting member

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

@@ -198,6 +198,7 @@ const List<ErrorCode> errorCodeValues = [
   CompileTimeErrorCode.EXTENSION_TYPE_IMPLEMENTS_DISALLOWED_TYPE,
   CompileTimeErrorCode.EXTENSION_TYPE_IMPLEMENTS_ITSELF,
   CompileTimeErrorCode.EXTENSION_TYPE_IMPLEMENTS_NOT_SUPERTYPE_OF_ERASURE,
+  CompileTimeErrorCode.EXTENSION_TYPE_IMPLEMENTS_REPRESENTATION_NOT_SUPERTYPE,
   CompileTimeErrorCode.EXTENSION_TYPE_INHERITED_MEMBER_CONFLICT,
   CompileTimeErrorCode.EXTENSION_TYPE_REPRESENTATION_DEPENDS_ON_ITSELF,
   CompileTimeErrorCode.EXTERNAL_FIELD_CONSTRUCTOR_INITIALIZER,

pkg/analyzer/messages.yaml

@@ -5090,6 +5090,15 @@ CompileTimeErrorCode:
       Parameters:
       0: the implemented not extension type
       1: the ultimate representation type
+  EXTENSION_TYPE_IMPLEMENTS_REPRESENTATION_NOT_SUPERTYPE:
+    problemMessage: "'{0}', the representation type of '{1}', is not a supertype of '{2}', the representation type of '{3}'."
+    correctionMessage: Try specifying a different type, or remove the type from the list.
+    comment: |-
+      Parameters:
+      0: the representation type of the implemented extension type
+      1: the name of the implemented extension type
+      2: the representation type of the this extension type
+      3: the name of the this extension type
   EXTENSION_TYPE_INHERITED_MEMBER_CONFLICT:
     problemMessage: "The extension type '{0}' has more than one distinct member named '{1}' from implemented types."
     correctionMessage: Try redeclaring the corresponding member in this extension type.

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

@@ -9,12 +9,12 @@ import '../dart/resolution/context_collection_resolution.dart';
 
 main() {
   defineReflectiveSuite(() {
-    defineReflectiveTests(ExtensionTypeImplementsDisallowedTypeTest);
+    defineReflectiveTests(ExtensionTypeImplementsNotSupertypeOfErasureTest);
   });
 }
 
 @reflectiveTest
-class ExtensionTypeImplementsDisallowedTypeTest
+class ExtensionTypeImplementsNotSupertypeOfErasureTest
     extends PubPackageResolutionTest {
   test_notSupertype() async {
     await assertErrorsInCode('''

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

@@ -0,0 +1,49 @@
+// Copyright (c) 2023, 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(
+        ExtensionTypeImplementsRepresentationNotSupertypeTest);
+  });
+}
+
+@reflectiveTest
+class ExtensionTypeImplementsRepresentationNotSupertypeTest
+    extends PubPackageResolutionTest {
+  test_notSupertype() async {
+    await assertErrorsInCode('''
+extension type A(String it) {}
+extension type B(int it) implements A {}
+''', [
+      error(
+          CompileTimeErrorCode
+              .EXTENSION_TYPE_IMPLEMENTS_REPRESENTATION_NOT_SUPERTYPE,
+          67,
+          1),
+    ]);
+  }
+
+  test_supertype() async {
+    await assertNoErrorsInCode('''
+extension type A(num it) {}
+extension type B(int it) implements A {}
+''');
+  }
+
+  test_supertype2() async {
+    await assertNoErrorsInCode('''
+extension type A(S1 it) {}
+extension type B(S3 it) implements A {}
+class S1 {}
+class S2 extends S1 {}
+class S3 extends S2 {}
+''');
+  }
+}

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

@@ -252,6 +252,8 @@ import 'extension_type_implements_itself_test.dart'
     as extension_type_implements_itself;
 import 'extension_type_implements_not_supertype_of_erasure_test.dart'
     as extension_type_implements_not_supertype_of_erasure;
+import 'extension_type_implements_representation_not_supertype_test.dart'
+    as extension_type_implements_representation_not_supertype;
 import 'extension_type_inherited_member_conflict_test.dart'
     as extension_type_inherited_member_conflict;
 import 'extension_type_representation_depends_on_itself_test.dart'
@@ -1061,6 +1063,7 @@ main() {
     extension_type_implements_disallowed_type.main();
     extension_type_implements_itself.main();
     extension_type_implements_not_supertype_of_erasure.main();
+    extension_type_implements_representation_not_supertype.main();
     extension_type_inherited_member_conflict.main();
     extension_type_representation_depends_on_itself.main();
     external_field_constructor_initializer.main();