[ddc] Add hot reload checks in aysnc bodies

Treats async code like function expressions when adding extra
checks for correctness after a hot reload. This is intended to handle
the cases where code that was statically sound and enqueued before the
reload actually runs after a reload when the soundness may no longer
be valid.

Change-Id: I42cd010175126748937d7df830875bc5b850a565
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/444368
Reviewed-by: Nate Biggs <natebiggs@google.com>
Commit-Queue: Nicholas Shahan <nshahan@google.com>

pkg/dev_compiler/lib/src/kernel/compiler_new.dart

@@ -873,6 +873,7 @@ class LibraryCompiler extends ComputeOnceConstantVisitor<js_ast.Expression>
   final FutureOrNormalizer _futureOrNormalizer;
 
   bool _inFunctionExpression = false;
+  bool _inAsyncExpression = false;
 
   /// Returns whether or not [uri] can be hot reloaded.
   ///
@@ -5072,8 +5073,14 @@ class LibraryCompiler extends ComputeOnceConstantVisitor<js_ast.Expression>
   }
 
   js_ast.Statement _emitFunctionScopedBody(FunctionNode f) {
+    var savedInAsyncExpression = _inAsyncExpression;
+    if (f.asyncMarker != AsyncMarker.Sync) {
+      _inAsyncExpression = true;
+    }
     var jsBody = _visitStatement(f.body!);
-    return _emitScopedBody(f, jsBody);
+    var body = _emitScopedBody(f, jsBody);
+    _inAsyncExpression = savedInAsyncExpression;
+    return body;
   }
 
   js_ast.Statement _emitScopedBody(FunctionNode f, js_ast.Statement body) {
@@ -7732,7 +7739,7 @@ class LibraryCompiler extends ComputeOnceConstantVisitor<js_ast.Expression>
   /// include checks to preserve soundness in the presence of hot reloads at
   /// runtime.
   bool _shouldRewriteInvocationWithHotReloadChecks(Member target) =>
-      _inFunctionExpression &&
+      (_inFunctionExpression || _inAsyncExpression) &&
       !_isBuildingSdk &&
       !usesJSInterop(target) &&
       target != _assertInteropMethod;

tests/hot_reload/async_call_deleted_top_level_function_ddc/config.json

@@ -0,0 +1,5 @@
+{
+  "exclude": [
+    "vm"
+  ]
+}

tests/hot_reload/async_call_deleted_top_level_function_ddc/main.0.dart

@@ -0,0 +1,43 @@
+// Copyright (c) 2025, 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 'dart:async';
+
+import 'package:expect/expect.dart';
+import 'package:expect/async_helper.dart';
+import 'package:reload_test/reload_test_utils.dart';
+
+/// Shows the behavior when async code enqueued before a hot restart runs
+/// after the restart and tries to interact with code that has been deleted.
+
+bool setBeforeAwait = false;
+bool setAfterAwait = false;
+
+int deleted() {
+  return 10;
+}
+
+Future<int> helper(Future<void> timingControl) async {
+  setBeforeAwait = true;
+  await timingControl;
+  setAfterAwait = true;
+  return deleted();
+}
+
+Future<void> main() async {
+  var helperCompleter = Completer<void>();
+  var helperFuture = helper(helperCompleter.future);
+  Expect.isTrue(setBeforeAwait);
+  Expect.isFalse(setAfterAwait);
+  await hotReload();
+  Expect.isFalse(setAfterAwait);
+  helperCompleter.complete();
+  var e = await asyncExpectThrows<NoSuchMethodError>(helperFuture);
+  Expect.contains(
+    "NoSuchMethodError: 'deleted'\n"
+    'Method was deleted during a hot reload and is no longer callable.',
+    e.toString(),
+  );
+  Expect.isTrue(setAfterAwait);
+}

tests/hot_reload/async_call_deleted_top_level_function_ddc/main.1.dart

@@ -0,0 +1,59 @@
+// Copyright (c) 2025, 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 'dart:async';
+
+import 'package:expect/expect.dart';
+import 'package:expect/async_helper.dart';
+import 'package:reload_test/reload_test_utils.dart';
+
+/// Shows the behavior when async code enqueued before a hot restart runs
+/// after the restart and tries to interact with code that has been deleted.
+
+bool setBeforeAwait = false;
+bool setAfterAwait = false;
+
+Future<int> helper(Future<void> timingControl) async {
+  setBeforeAwait = true;
+  await timingControl;
+  setAfterAwait = true;
+  return 99;
+}
+
+Future<void> main() async {
+  var helperCompleter = Completer<void>();
+  var helperFuture = helper(helperCompleter.future);
+  Expect.isTrue(setBeforeAwait);
+  Expect.isFalse(setAfterAwait);
+  await hotReload();
+  Expect.isFalse(setAfterAwait);
+  helperCompleter.complete();
+  var e = await asyncExpectThrows<NoSuchMethodError>(helperFuture);
+  Expect.contains(
+    "NoSuchMethodError: 'deleted'\n"
+    'Method was deleted during a hot reload and is no longer callable.',
+    e.toString(),
+  );
+  Expect.isTrue(setAfterAwait);
+}
+
+/** DIFF **/
+/*
+ bool setBeforeAwait = false;
+ bool setAfterAwait = false;
+ 
+-int deleted() {
+-  return 10;
+-}
+-
+ Future<int> helper(Future<void> timingControl) async {
+   setBeforeAwait = true;
+   await timingControl;
+   setAfterAwait = true;
+-  return deleted();
++  return 99;
+ }
+ 
+ Future<void> main() async {
+*/

tests/hot_reload/async_call_deleted_top_level_function_vm/config.json

@@ -0,0 +1,6 @@
+{
+  "exclude": [
+    "chrome",
+    "d8"
+  ]
+}

tests/hot_reload/async_call_deleted_top_level_function_vm/main.0.dart

@@ -0,0 +1,37 @@
+// Copyright (c) 2025, 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 'dart:async';
+
+import 'package:expect/expect.dart';
+import 'package:reload_test/reload_test_utils.dart';
+
+/// Shows the behavior when async code enqueued before a hot restart runs
+/// after the restart and tries to interact with code that has been deleted.
+
+bool setBeforeAwait = false;
+bool setAfterAwait = false;
+
+int deleted() {
+  return 10;
+}
+
+Future<int> helper(Future<void> timingControl) async {
+  setBeforeAwait = true;
+  await timingControl;
+  setAfterAwait = true;
+  return deleted();
+}
+
+Future<void> main() async {
+  var helperCompleter = Completer<void>();
+  var helperFuture = helper(helperCompleter.future);
+  Expect.isTrue(setBeforeAwait);
+  Expect.isFalse(setAfterAwait);
+  await hotReload();
+  Expect.isFalse(setAfterAwait);
+  helperCompleter.complete();
+  Expect.equals(10, await helperFuture);
+  Expect.isTrue(setAfterAwait);
+}

tests/hot_reload/async_call_deleted_top_level_function_vm/main.1.dart

@@ -0,0 +1,53 @@
+// Copyright (c) 2025, 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 'dart:async';
+
+import 'package:expect/expect.dart';
+import 'package:reload_test/reload_test_utils.dart';
+
+/// Shows the behavior when async code enqueued before a hot restart runs
+/// after the restart and tries to interact with code that has been deleted.
+
+bool setBeforeAwait = false;
+bool setAfterAwait = false;
+
+Future<int> helper(Future<void> timingControl) async {
+  setBeforeAwait = true;
+  await timingControl;
+  setAfterAwait = true;
+  return 99;
+}
+
+Future<void> main() async {
+  var helperCompleter = Completer<void>();
+  var helperFuture = helper(helperCompleter.future);
+  Expect.isTrue(setBeforeAwait);
+  Expect.isFalse(setAfterAwait);
+  await hotReload();
+  Expect.isFalse(setAfterAwait);
+  helperCompleter.complete();
+  Expect.equals(10, await helperFuture);
+  Expect.isTrue(setAfterAwait);
+}
+
+/** DIFF **/
+/*
+ bool setBeforeAwait = false;
+ bool setAfterAwait = false;
+ 
+-int deleted() {
+-  return 10;
+-}
+-
+ Future<int> helper(Future<void> timingControl) async {
+   setBeforeAwait = true;
+   await timingControl;
+   setAfterAwait = true;
+-  return deleted();
++  return 99;
+ }
+ 
+ Future<void> main() async {
+*/

tests/hot_reload/async_call_top_level_function_parameters_change_ddc/config.json

@@ -0,0 +1,5 @@
+{
+  "exclude": [
+    "vm"
+  ]
+}

tests/hot_reload/async_call_top_level_function_parameters_change_ddc/main.0.dart

@@ -0,0 +1,42 @@
+// Copyright (c) 2025, 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 'dart:async';
+
+import 'package:expect/async_helper.dart';
+import 'package:expect/expect.dart';
+import 'package:reload_test/reload_test_utils.dart';
+
+/// Shows the behavior when async code enqueued before a hot restart runs
+/// after the restart and tries to interact with code that has been updated.
+
+bool setBeforeAwait = false;
+bool setAfterAwait = false;
+
+int changed(String s) {
+  return s.length;
+}
+
+Future<int> helper(Future<void> timingControl) async {
+  setBeforeAwait = true;
+  await timingControl;
+  setAfterAwait = true;
+  return changed('hello');
+}
+
+Future<void> main() async {
+  var helperCompleter = Completer<void>();
+  var helperFuture = helper(helperCompleter.future);
+  Expect.isTrue(setBeforeAwait);
+  Expect.isFalse(setAfterAwait);
+  await hotReload();
+  Expect.isFalse(setAfterAwait);
+  helperCompleter.complete();
+  var error = await asyncExpectThrows<TypeError>(helperFuture);
+  Expect.contains(
+    "type 'String' is not a subtype of type 'int'",
+    error.toString(),
+  );
+  Expect.isTrue(setAfterAwait);
+}

tests/hot_reload/async_call_top_level_function_parameters_change_ddc/main.1.dart

@@ -0,0 +1,64 @@
+// Copyright (c) 2025, 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 'dart:async';
+
+import 'package:expect/async_helper.dart';
+import 'package:expect/expect.dart';
+import 'package:reload_test/reload_test_utils.dart';
+
+/// Shows the behavior when async code enqueued before a hot restart runs
+/// after the restart and tries to interact with code that has been updated.
+
+bool setBeforeAwait = false;
+bool setAfterAwait = false;
+
+int changed(int i) {
+  return i - 10;
+}
+
+Future<int> helper(Future<void> timingControl) async {
+  setBeforeAwait = true;
+  await timingControl;
+  setAfterAwait = true;
+  return changed(99);
+}
+
+Future<void> main() async {
+  var helperCompleter = Completer<void>();
+  var helperFuture = helper(helperCompleter.future);
+  Expect.isTrue(setBeforeAwait);
+  Expect.isFalse(setAfterAwait);
+  await hotReload();
+  Expect.isFalse(setAfterAwait);
+  helperCompleter.complete();
+  var error = await asyncExpectThrows<TypeError>(helperFuture);
+  Expect.contains(
+    "type 'String' is not a subtype of type 'int'",
+    error.toString(),
+  );
+  Expect.isTrue(setAfterAwait);
+}
+
+/** DIFF **/
+/*
+ bool setBeforeAwait = false;
+ bool setAfterAwait = false;
+ 
+-int changed(String s) {
+-  return s.length;
++int changed(int i) {
++  return i - 10;
+ }
+ 
+ Future<int> helper(Future<void> timingControl) async {
+   setBeforeAwait = true;
+   await timingControl;
+   setAfterAwait = true;
+-  return changed('hello');
++  return changed(99);
+ }
+ 
+ Future<void> main() async {
+*/

tests/hot_reload/async_call_top_level_function_parameters_change_vm/config.json

@@ -0,0 +1,6 @@
+{
+  "exclude": [
+    "chrome",
+    "d8"
+  ]
+}

tests/hot_reload/async_call_top_level_function_parameters_change_vm/main.0.dart

@@ -0,0 +1,42 @@
+// Copyright (c) 2025, 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 'dart:async';
+
+import 'package:expect/async_helper.dart';
+import 'package:expect/expect.dart';
+import 'package:reload_test/reload_test_utils.dart';
+
+/// Shows the behavior when async code enqueued before a hot restart runs
+/// after the restart and tries to interact with code that has been updated.
+
+bool setBeforeAwait = false;
+bool setAfterAwait = false;
+
+int changed(String s) {
+  return s.length;
+}
+
+Future<int> helper(Future<void> timingControl) async {
+  setBeforeAwait = true;
+  await timingControl;
+  setAfterAwait = true;
+  return changed('hello');
+}
+
+Future<void> main() async {
+  var helperCompleter = Completer<void>();
+  var helperFuture = helper(helperCompleter.future);
+  Expect.isTrue(setBeforeAwait);
+  Expect.isFalse(setAfterAwait);
+  await hotReload();
+  Expect.isFalse(setAfterAwait);
+  helperCompleter.complete();
+  var error = await asyncExpectThrows<NoSuchMethodError>(helperFuture);
+  Expect.contains(
+    "Class 'String' has no instance method '-'",
+    error.toString(),
+  );
+  Expect.isTrue(setAfterAwait);
+}

tests/hot_reload/async_call_top_level_function_parameters_change_vm/main.1.dart

@@ -0,0 +1,64 @@
+// Copyright (c) 2025, 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 'dart:async';
+
+import 'package:expect/async_helper.dart';
+import 'package:expect/expect.dart';
+import 'package:reload_test/reload_test_utils.dart';
+
+/// Shows the behavior when async code enqueued before a hot restart runs
+/// after the restart and tries to interact with code that has been updated.
+
+bool setBeforeAwait = false;
+bool setAfterAwait = false;
+
+int changed(int i) {
+  return i - 10;
+}
+
+Future<int> helper(Future<void> timingControl) async {
+  setBeforeAwait = true;
+  await timingControl;
+  setAfterAwait = true;
+  return changed(99);
+}
+
+Future<void> main() async {
+  var helperCompleter = Completer<void>();
+  var helperFuture = helper(helperCompleter.future);
+  Expect.isTrue(setBeforeAwait);
+  Expect.isFalse(setAfterAwait);
+  await hotReload();
+  Expect.isFalse(setAfterAwait);
+  helperCompleter.complete();
+  var error = await asyncExpectThrows<NoSuchMethodError>(helperFuture);
+  Expect.contains(
+    "Class 'String' has no instance method '-'",
+    error.toString(),
+  );
+  Expect.isTrue(setAfterAwait);
+}
+
+/** DIFF **/
+/*
+ bool setBeforeAwait = false;
+ bool setAfterAwait = false;
+
+-int changed(String s) {
+-  return s.length;
++int changed(int i) {
++  return i - 10;
+ }
+
+ Future<int> helper(Future<void> timingControl) async {
+   setBeforeAwait = true;
+   await timingControl;
+   setAfterAwait = true;
+-  return changed('hello');
++  return changed(99);
+ }
+
+ Future<void> main() async {
+*/

tests/hot_reload/existing_field_changes_type/main.0.dart

@@ -13,11 +13,13 @@ class Foo {
   int x = 42;
 }
 
+helper() => Foo().x;
+
 Future<void> main() async {
-  Expect.type<int>(Foo().x);
-  Expect.equals(42, Foo().x);
+  Expect.type<int>(helper());
+  Expect.equals(42, helper());
   await hotReload();
 
-  Expect.type<String>(Foo().x);
-  Expect.equals('42', Foo().x);
+  Expect.type<String>(helper());
+  Expect.equals('42', helper());
 }

tests/hot_reload/existing_field_changes_type/main.1.dart

@@ -13,13 +13,15 @@ class Foo {
   String x = '42';
 }
 
+helper() => Foo().x;
+
 Future<void> main() async {
-  Expect.type<int>(Foo().x);
-  Expect.equals(42, Foo().x);
+  Expect.type<int>(helper());
+  Expect.equals(42, helper());
   await hotReload();
 
-  Expect.type<String>(Foo().x);
-  Expect.equals('42', Foo().x);
+  Expect.type<String>(helper());
+  Expect.equals('42', helper());
 }
 
 /** DIFF **/
@@ -31,5 +33,5 @@ Future<void> main() async {
 +  String x = '42';
  }
  
- Future<void> main() async {
+ helper() => Foo().x;
 */