[ddc] Add hot reload checks to instance getter accesses

Checks the compile and current hot reload generations. If they are not
equal the value is checked to have a getter of the expected name and
if so it gets called. If not, `.noSuchMethod` is invoked instead.

Issue: #60100

Change-Id: Ib80582b45f87f2ab41b943e0f263167b38601e0a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/429066
Reviewed-by: Srujan Gaddam <[email protected]>
Reviewed-by: Nate Biggs <[email protected]>
Commit-Queue: Nicholas Shahan <[email protected]>

Author: nshahan

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

@@ -5454,9 +5454,13 @@ class LibraryCompiler extends ComputeOnceConstantVisitor<js_ast.Expression>
   js_ast.Expression visitDynamicGet(DynamicGet node) {
     var jsReceiver = _visitExpression(node.receiver);
     var jsMemberName = _emitMemberName(node.name.text);
-    return _runtimeCall('dload$_replSuffix(#, #)', [jsReceiver, jsMemberName]);
+    return _emitDynamicGet(jsReceiver, jsMemberName);
   }
 
+  js_ast.Expression _emitDynamicGet(
+          js_ast.Expression receiver, js_ast.Expression memberName) =>
+      _runtimeCall('dload$_replSuffix(#, #)', [receiver, memberName]);
+
   @override
   js_ast.Expression visitInstanceGet(InstanceGet node) {
     // TODO(nshahan): Marking an end span for property accessors would improve
@@ -5485,6 +5489,17 @@ class LibraryCompiler extends ComputeOnceConstantVisitor<js_ast.Expression>
     var jsMemberName =
         _emitMemberName(memberName, member: node.interfaceTarget);
     var instanceGet = js_ast.PropertyAccess(jsReceiver, jsMemberName);
+    if (_shouldRewriteInvocationWithHotReloadChecks(node.interfaceTarget)) {
+      instanceGet.sourceInformation = _nodeStart(node);
+      // Since there are no arguments (unlike methods) the dynamic get path can
+      // be reused for the hot reload checks on a getter.
+      var checkedGet = _emitCast(
+          _emitDynamicGet(
+              _visitExpression(receiver), _emitMemberName(memberName)),
+          node.resultType)
+        ..sourceInformation = _nodeStart(node);
+      return _emitHotReloadSafeInvocation(instanceGet, checkedGet);
+    }
     return _isNullCheckableJsInterop(node.interfaceTarget)
         ? _wrapWithJsInteropNullCheck(instanceGet)
         : instanceGet;
@@ -6802,20 +6817,14 @@ class LibraryCompiler extends ComputeOnceConstantVisitor<js_ast.Expression>
     var staticCall = js_ast.Call(fn, args)
       ..sourceInformation = _nodeStart(node);
     if (_shouldRewriteInvocationWithHotReloadChecks(target)) {
-      var generationCheck = js.call('# === #', [
-        js.number(_hotReloadGeneration),
-        _runtimeCall('global.dartDevEmbedder.hotReloadGeneration')
-      ]);
       var checkedCall = _rewriteInvocationWithHotReloadChecks(
           target,
           node.arguments,
           node.getStaticType(_staticTypeContext),
           _nodeStart(node));
       // As an optimization, avoid extra checks when the invocation code was
       // compiled in the same generation that it is running.
-      return js_ast.InvocationWithHotReloadChecks(
-          generationCheck, staticCall, checkedCall)
-        ..sourceInformation = continueSourceMap;
+      return _emitHotReloadSafeInvocation(staticCall, checkedCall);
     }
     return _isNullCheckableJsInterop(target)
         ? _wrapWithJsInteropNullCheck(staticCall)
@@ -6831,6 +6840,17 @@ class LibraryCompiler extends ComputeOnceConstantVisitor<js_ast.Expression>
       !usesJSInterop(target) &&
       target != _assertInteropMethod;
 
+  js_ast.Expression _emitHotReloadSafeInvocation(
+      js_ast.Expression uncheckedCall, js_ast.Expression checkedCall) {
+    var generationCheck = js.call('# === #', [
+      js.number(_hotReloadGeneration),
+      _runtimeCall('global.dartDevEmbedder.hotReloadGeneration')
+    ]);
+    return js_ast.InvocationWithHotReloadChecks(
+        generationCheck, uncheckedCall, checkedCall)
+      ..sourceInformation = continueSourceMap;
+  }
+
   /// Rewrites an invocation of [target] that is statically sound at compile
   /// time to include checks to preserve soundness in the presence of hot
   /// reloads at runtime.

sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/operations.dart

@@ -1576,11 +1576,27 @@ declareClass(library, classIdentifier, classDeclaration) {
       !isStateBearingSymbol(property),
       originalClass,
     );
+    deleteClassMembers(originalClass, classDeclaration);
     copyProperties(originalClass, classDeclaration, copyWhen: copyWhen);
   }
   return JS<Object>('!', '#.#', library, classIdentifier);
 }
 
+/// Deletes the members from [oldClass] that are not present in [newClass].
+///
+/// Existing members not prefixed by a special identifier are replaced
+/// (see [isStateBearingSymbol]).
+///
+/// Called from generated code.
+void deleteClassMembers(Object oldClass, Object newClass) {
+  for (var name in getOwnNamesAndSymbols(oldClass)) {
+    if (JS<Object?>('', '#.#', newClass, name) == null &&
+        !isStateBearingSymbol(name)) {
+      JS('', 'delete #.#', oldClass, name);
+    }
+  }
+}
+
 /// Declares properties in [propertiesObject] on [topLevelContainer].
 ///
 /// [topLevelContainer] must already exist.

tests/hot_reload/call_deleted_instance_getter_ddc/config.json

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

tests/hot_reload/call_deleted_instance_getter_ddc/main.0.dart

@@ -0,0 +1,30 @@
+// 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 'package:expect/expect.dart';
+import 'package:reload_test/reload_test_utils.dart';
+
+var retained;
+C? c;
+
+class C {
+  String get deleted {
+    return 'hello';
+  }
+}
+
+helper() {
+  c = C();
+  retained = () => c!.deleted;
+  return retained();
+}
+
+Future<void> main() async {
+  helper();
+  await hotReload();
+  Expect.throws<NoSuchMethodError>(
+    helper,
+    (error) => '$error'.contains('deleted'),
+  );
+}

tests/hot_reload/call_deleted_instance_getter_ddc/main.1.dart

@@ -0,0 +1,44 @@
+// 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 'package:expect/expect.dart';
+import 'package:reload_test/reload_test_utils.dart';
+
+var retained;
+C? c;
+
+class C {}
+
+helper() {
+  return retained();
+}
+
+Future<void> main() async {
+  helper();
+  await hotReload();
+  Expect.throws<NoSuchMethodError>(
+    helper,
+    (error) => '$error'.contains('deleted'),
+  );
+}
+
+/** DIFF **/
+/*
+ var retained;
+ C? c;
+ 
+-class C {
+-  String get deleted {
+-    return 'hello';
+-  }
+-}
++class C {}
+ 
+ helper() {
+-  c = C();
+-  retained = () => c!.deleted;
+   return retained();
+ }
+ 
+*/

tests/hot_reload/call_deleted_instance_getter_vm/config.json

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

tests/hot_reload/call_deleted_instance_getter_vm/main.0.dart

@@ -0,0 +1,30 @@
+// 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 'package:expect/expect.dart';
+import 'package:reload_test/reload_test_utils.dart';
+
+var retained;
+C? c;
+
+class C {
+  String get deleted {
+    return 'hello';
+  }
+}
+
+helper() {
+  c = C();
+  retained = () => c!.deleted;
+  return retained();
+}
+
+Future<void> main() async {
+  helper();
+  await hotReload();
+  Expect.throws(
+    helper,
+    (error) => '$error'.contains('Lookup failed: deleted in @getters in C'),
+  );
+}

tests/hot_reload/call_deleted_instance_getter_vm/main.1.dart

@@ -0,0 +1,44 @@
+// 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 'package:expect/expect.dart';
+import 'package:reload_test/reload_test_utils.dart';
+
+var retained;
+C? c;
+
+class C {}
+
+helper() {
+  return retained();
+}
+
+Future<void> main() async {
+  helper();
+  await hotReload();
+  Expect.throws(
+    helper,
+    (error) => '$error'.contains('Lookup failed: deleted in @getters in C'),
+  );
+}
+
+/** DIFF **/
+/*
+ var retained;
+ C? c;
+ 
+-class C {
+-  String get deleted {
+-    return 'hello';
+-  }
+-}
++class C {}
+ 
+ helper() {
+-  c = C();
+-  retained = () => c!.deleted;
+   return retained();
+ }
+ 
+*/

tests/hot_reload/call_instance_getter_return_change_ddc/config.json

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

tests/hot_reload/call_instance_getter_return_change_ddc/main.0.dart

@@ -0,0 +1,30 @@
+// 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 'package:expect/expect.dart';
+import 'package:reload_test/reload_test_utils.dart';
+
+int Function()? retained;
+C? c;
+
+class C {
+  String get returnChange {
+    return 'hello';
+  }
+}
+
+helper() {
+  c = C();
+  retained = () => c!.returnChange.length;
+  return retained!();
+}
+
+Future<void> main() async {
+  helper();
+  await hotReload();
+  Expect.throws<TypeError>(
+    helper,
+    (error) => '$error'.contains("'double' is not a subtype of type 'String'"),
+  );
+}