[dwds] Add support for --[no-]deprecated-js-interop

dwds/CHANGELOG.md

@@ -1,3 +1,10 @@
+## 27.2.0-wip
+
+- Add `deprecatedJsInterop` to `BuildSettings` and `CompilerOptions`. When it
+  is set, the expression compiler worker is started with
+  `--[no-]deprecated-js-interop`. This requires a Dart SDK that supports the
+  flag.
+
 ## 27.1.4
 
 - Fix duplicated browser tabs taking over the original tab's DWDS connection.

dwds/lib/src/loaders/strategy.dart

@@ -236,10 +236,17 @@ class BuildSettings {
   final bool isFlutterApp;
   final List<String> experiments;
 
+  /// Whether the compilers allow the deprecated JS interop libraries, such as
+  /// `dart:html`.
+  ///
+  /// If `null`, no flag is passed and the compiler default is used.
+  final bool? deprecatedJsInterop;
+
   const BuildSettings({
     this.appEntrypoint,
     this.canaryFeatures = false,
     this.isFlutterApp = true,
     this.experiments = const <String>[],
+    this.deprecatedJsInterop,
   });
 }

dwds/lib/src/services/chrome/chrome_proxy_service.dart

@@ -186,15 +186,15 @@ final class ChromeProxyService extends ProxyService<ChromeAppInspector> {
   Future<void> _updateCompilerDependencies(String entrypoint) async {
     final loadStrategy = globalToolConfiguration.loadStrategy;
     final moduleFormat = loadStrategy.moduleFormat;
-    final canaryFeatures = loadStrategy.buildSettings.canaryFeatures;
-    final experiments = loadStrategy.buildSettings.experiments;
+    final buildSettings = loadStrategy.buildSettings;
 
     _logger.info('Initializing expression compiler for $entrypoint');
 
     final compilerOptions = CompilerOptions(
       moduleFormat: ModuleFormat.values.byName(moduleFormat),
-      canaryFeatures: canaryFeatures,
-      experiments: experiments,
+      canaryFeatures: buildSettings.canaryFeatures,
+      experiments: buildSettings.experiments,
+      deprecatedJsInterop: buildSettings.deprecatedJsInterop,
     );
 
     final compiler = _compiler;

dwds/lib/src/services/expression_compiler.dart

@@ -9,10 +9,17 @@ class CompilerOptions {
   final bool canaryFeatures;
   final List<String> experiments;
 
+  /// Whether the compiler allows the deprecated JS interop libraries, such as
+  /// `dart:html`.
+  ///
+  /// If `null`, no flag is passed and the compiler default is used.
+  final bool? deprecatedJsInterop;
+
   CompilerOptions({
     required this.moduleFormat,
     required this.canaryFeatures,
     required this.experiments,
+    this.deprecatedJsInterop,
   });
 }
 

dwds/lib/src/services/expression_compiler_service.dart

@@ -9,6 +9,41 @@ import 'package:async/async.dart';
 import 'package:dwds/src/services/expression_compiler.dart';
 import 'package:dwds/src/utilities/sdk_configuration.dart';
 import 'package:logging/logging.dart';
+import 'package:meta/meta.dart';
+
+/// Returns the arguments for the DDC expression compiler worker.
+@visibleForTesting
+List<String> expressionCompilerWorkerArgs({
+  required Uri sdkSummaryUri,
+  required String address,
+  required int port,
+  required CompilerOptions compilerOptions,
+  required bool verbose,
+}) => [
+  '--experimental-expression-compiler',
+  '--dart-sdk-summary',
+  '$sdkSummaryUri',
+  '--asset-server-address',
+  address,
+  '--asset-server-port',
+  '$port',
+  '--module-format',
+  compilerOptions.moduleFormat.name,
+  if (verbose) '--verbose',
+  for (final experiment in compilerOptions.experiments)
+    '--enable-experiment=$experiment',
+  if (compilerOptions.canaryFeatures) '--canary',
+  ?_deprecatedJsInteropArg(compilerOptions.deprecatedJsInterop),
+];
+
+/// The `--[no-]deprecated-js-interop` argument, or `null` to use the compiler
+/// default.
+String? _deprecatedJsInteropArg(bool? deprecatedJsInterop) =>
+    switch (deprecatedJsInterop) {
+      null => null,
+      true => '--deprecated-js-interop',
+      false => '--no-deprecated-js-interop',
+    };
 
 class _Compiler {
   static final _logger = Logger('ExpressionCompilerService');
@@ -67,21 +102,13 @@ class _Compiler {
     final workerUri = sdkConfiguration.compilerWorkerUri!;
     final sdkSummaryUri = sdkConfiguration.sdkSummaryUri!;
 
-    final args = [
-      '--experimental-expression-compiler',
-      '--dart-sdk-summary',
-      '$sdkSummaryUri',
-      '--asset-server-address',
-      address,
-      '--asset-server-port',
-      '$port',
-      '--module-format',
-      compilerOptions.moduleFormat.name,
-      if (verbose) '--verbose',
-      for (final experiment in compilerOptions.experiments)
-        '--enable-experiment=$experiment',
-      if (compilerOptions.canaryFeatures) '--canary',
-    ];
+    final args = expressionCompilerWorkerArgs(
+      sdkSummaryUri: sdkSummaryUri,
+      address: address,
+      port: port,
+      compilerOptions: compilerOptions,
+      verbose: verbose,
+    );
 
     _logger.info('Starting...');
     _logger.finest('$workerUri ${args.join(' ')}');

dwds/pubspec.yaml

@@ -1,13 +1,13 @@
 name: dwds
 # Every time this changes you need to run `dart run tool/build.dart`.
-version: 27.1.4
+version: 27.2.0-wip
 
 description: >-
   A service that proxies between the Chrome debug protocol and the Dart VM
   service protocol.
 repository: https://github.com/dart-lang/webdev/tree/main/dwds
 environment:
-  sdk: ^3.13.0-107.0.dev
+  sdk: ^3.14.0-286.0.dev
 
 dependencies:
   async: ^2.9.0

dwds/test/services/expression_compiler_worker_args_test.dart

@@ -0,0 +1,56 @@
+// Copyright (c) 2026, 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:dwds/src/services/expression_compiler.dart';
+import 'package:dwds/src/services/expression_compiler_service.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group('expressionCompilerWorkerArgs', () {
+    List<String> argsFor({bool? deprecatedJsInterop}) =>
+        expressionCompilerWorkerArgs(
+          sdkSummaryUri: Uri.file('/sdk/ddc_outline.dill'),
+          address: 'localhost',
+          port: 1234,
+          compilerOptions: CompilerOptions(
+            moduleFormat: ModuleFormat.ddc,
+            canaryFeatures: true,
+            experiments: const ['records'],
+            deprecatedJsInterop: deprecatedJsInterop,
+          ),
+          verbose: false,
+        );
+
+    test('passes the compiler options', () {
+      expect(argsFor(), [
+        '--experimental-expression-compiler',
+        '--dart-sdk-summary',
+        'file:///sdk/ddc_outline.dill',
+        '--asset-server-address',
+        'localhost',
+        '--asset-server-port',
+        '1234',
+        '--module-format',
+        'ddc',
+        '--canary',
+      ]);
+    });
+
+    test('does not pass deprecated-js-interop when not configured', () {
+      expect(argsFor(), isNot(contains(contains('deprecated-js-interop'))));
+    });
+
+    test('passes --deprecated-js-interop', () {
+      final args = argsFor(deprecatedJsInterop: true);
+      expect(args, contains('--deprecated-js-interop'));
+      expect(args, isNot(contains('--no-deprecated-js-interop')));
+    });
+
+    test('passes --no-deprecated-js-interop', () {
+      final args = argsFor(deprecatedJsInterop: false);
+      expect(args, contains('--no-deprecated-js-interop'));
+      expect(args, isNot(contains('--deprecated-js-interop')));
+    });
+  });
+}