Extension types. Report when await of not Future subtype.

Change-Id: I51b825c1d48b55866d8112ab6421c7937a0c7575
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/318024
Reviewed-by: Phil Quitslund <[email protected]>
Commit-Queue: Konstantin Shcheglov <[email protected]>

Author: scheglov

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

@@ -212,6 +212,8 @@ CompileTimeErrorCode.AWAIT_IN_LATE_LOCAL_VARIABLE_INITIALIZER:
     The fix is to remove the `late` modifier.
 CompileTimeErrorCode.AWAIT_IN_WRONG_CONTEXT:
   status: hasFix
+CompileTimeErrorCode.AWAIT_OF_EXTENSION_TYPE_NOT_FUTURE:
+  status: noFix
 CompileTimeErrorCode.BASE_CLASS_IMPLEMENTED_OUTSIDE_OF_LIBRARY:
   status: noFix
   notes: |-

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

@@ -232,6 +232,14 @@ class CompileTimeErrorCode extends AnalyzerErrorCode {
         "Try marking the function body with either 'async' or 'async*'.",
   );
 
+  static const CompileTimeErrorCode AWAIT_OF_EXTENSION_TYPE_NOT_FUTURE =
+      CompileTimeErrorCode(
+    'AWAIT_OF_EXTENSION_TYPE_NOT_FUTURE',
+    "The 'await' expression can't be used for an expression with an extension "
+        "type that is not a subtype of 'Future'.",
+    correctionMessage: "Try updating the extension type to implement 'Future'.",
+  );
+
   ///  Parameters:
   ///  0: the name of the base class being implemented
   static const CompileTimeErrorCode BASE_CLASS_IMPLEMENTED_OUTSIDE_OF_LIBRARY =

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

@@ -63,6 +63,7 @@ const List<ErrorCode> errorCodeValues = [
   CompileTimeErrorCode.ASYNC_FOR_IN_WRONG_CONTEXT,
   CompileTimeErrorCode.AWAIT_IN_LATE_LOCAL_VARIABLE_INITIALIZER,
   CompileTimeErrorCode.AWAIT_IN_WRONG_CONTEXT,
+  CompileTimeErrorCode.AWAIT_OF_EXTENSION_TYPE_NOT_FUTURE,
   CompileTimeErrorCode.BASE_CLASS_IMPLEMENTED_OUTSIDE_OF_LIBRARY,
   CompileTimeErrorCode.BASE_MIXIN_IMPLEMENTED_OUTSIDE_OF_LIBRARY,
   CompileTimeErrorCode.BODY_MIGHT_COMPLETE_NORMALLY,

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

@@ -354,7 +354,9 @@ class ErrorVerifier extends RecursiveAstVisitor<void>
     if (_isNonNullableByDefault) {
       checkForUseOfVoidResult(node.expression);
     }
+
     _checkForAwaitInLateLocalVariableInitializer(node);
+    _checkForAwaitOfExtensionTypeNotFuture(node);
     super.visitAwaitExpression(node);
   }
 
@@ -1784,6 +1786,22 @@ class ErrorVerifier extends RecursiveAstVisitor<void>
     }
   }
 
+  void _checkForAwaitOfExtensionTypeNotFuture(AwaitExpression node) {
+    final expression = node.expression;
+    final expressionType = expression.typeOrThrow;
+    if (expressionType.element is ExtensionTypeElement) {
+      final anyFuture = typeSystem.typeProvider.futureType(
+        typeSystem.objectQuestion,
+      );
+      if (!typeSystem.isSubtypeOf(expressionType, anyFuture)) {
+        errorReporter.reportErrorForToken(
+          CompileTimeErrorCode.AWAIT_OF_EXTENSION_TYPE_NOT_FUTURE,
+          node.awaitKeyword,
+        );
+      }
+    }
+  }
+
   /// Verifies that the nodes don't reference `Function` from `dart:core`.
   void _checkForBadFunctionUse({
     required NamedType? superclass,

pkg/analyzer/messages.yaml

@@ -1127,6 +1127,9 @@ CompileTimeErrorCode:
       16.30 Await Expressions: It is a compile-time error if the function
       immediately enclosing _a_ is not declared asynchronous. (Where _a_ is the
       await expression.)
+  AWAIT_OF_EXTENSION_TYPE_NOT_FUTURE:
+    problemMessage: "The 'await' expression can't be used for an expression with an extension type that is not a subtype of 'Future'."
+    correctionMessage: Try updating the extension type to implement 'Future'.
   BASE_CLASS_IMPLEMENTED_OUTSIDE_OF_LIBRARY:
     sharedName: INVALID_USE_OF_TYPE_OUTSIDE_LIBRARY
     problemMessage: "The class '{0}' can't be implemented outside of its library because it's a base class."

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

@@ -0,0 +1,39 @@
+// 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(AwaitOfExtensionTypeNotFutureTest);
+  });
+}
+
+@reflectiveTest
+class AwaitOfExtensionTypeNotFutureTest extends PubPackageResolutionTest {
+  test_hasError() async {
+    await assertErrorsInCode(r'''
+extension type A(int it) {}
+
+void f(A a) async {
+  await a;
+}
+''', [
+      error(CompileTimeErrorCode.AWAIT_OF_EXTENSION_TYPE_NOT_FUTURE, 51, 5),
+    ]);
+  }
+
+  test_noError() async {
+    await assertNoErrorsInCode(r'''
+extension type A(Future<int> it) implements Future<int> {}
+
+void f(A a) async {
+  await a;
+}
+''');
+  }
+}

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

@@ -41,6 +41,8 @@ import 'async_keyword_used_as_identifier_test.dart'
 import 'await_in_late_local_variable_initializer_test.dart'
     as await_in_late_local_variable_initializer;
 import 'await_in_wrong_context_test.dart' as await_in_wrong_context;
+import 'await_of_extension_type_not_future_test.dart'
+    as await_of_extension_type_not_future;
 import 'base_class_implemented_outside_of_library_test.dart'
     as base_class_implemented_outside_of_library;
 import 'base_mixin_implemented_outside_of_library_test.dart'
@@ -901,6 +903,7 @@ main() {
     async_keyword_used_as_identifier.main();
     await_in_late_local_variable_initializer.main();
     await_in_wrong_context.main();
+    await_of_extension_type_not_future.main();
     base_class_implemented_outside_of_library.main();
     base_mixin_implemented_outside_of_library.main();
     binary_operator_written_out.main();