Migrate dwds/web directory to null safety (#1648)

* Migrate web directory to null safety

* Ignore false positive analyzer warning

* Fixed analyzer warning

* Addressed CR comments

Author: Anna Gringauze

dwds/lib/src/utilities/sdk_configuration.dart

@@ -120,7 +120,7 @@ class SdkConfiguration {
 class DefaultSdkConfigurationProvider extends SdkConfigurationProvider {
   DefaultSdkConfigurationProvider();
 
-  late SdkConfiguration _configuration = _create();
+  late final SdkConfiguration _configuration = _create();
 
   /// Create and validate configuration matching the default SDK layout.
   @override

dwds/web/client.dart

@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 @JS()
 library hot_reload_client;
 
@@ -38,7 +36,7 @@ const _batchDelayMilliseconds = 1000;
 
 // GENERATE:
 // pub run build_runner build web
-Future<void> main() {
+Future<void>? main() {
   return runZonedGuarded(() async {
     // Set the unique id for this instance of the app.
     // Test apps may already have this set.
@@ -221,13 +219,13 @@ String _fixProtocol(String url) {
 external String get dartAppId;
 
 @JS(r'$dartAppInstanceId')
-external String get dartAppInstanceId;
+external String? get dartAppInstanceId;
 
 @JS(r'$dwdsDevHandlerPath')
 external String get dwdsDevHandlerPath;
 
 @JS(r'$dartAppInstanceId')
-external set dartAppInstanceId(String id);
+external set dartAppInstanceId(String? id);
 
 @JS(r'$dartModuleStrategy')
 external String get dartModuleStrategy;

dwds/web/promise.dart

@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 @JS()
 library webdev.web.promise;
 
@@ -49,7 +47,7 @@ Future<T> toFuture<T>(Promise<T> promise) {
   final completer = Completer<T>();
   promise.then(
     allowInterop(completer.complete),
-    allowInterop(completer.completeError),
+    allowInterop((e) => completer.completeError(e)),
   );
   return completer.future;
 }

dwds/web/reloader/legacy_restarter.dart

@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'dart:async';
 import 'dart:html';
 import 'dart:js';
@@ -12,7 +10,7 @@ import 'restarter.dart';
 
 class LegacyRestarter implements Restarter {
   @override
-  Future<bool> restart({String runId}) async {
+  Future<bool> restart({String? runId}) async {
     final dartLibrary = context['dart_library'] as JsObject;
     if (runId == null) {
       dartLibrary.callMethod('reload');
@@ -22,16 +20,17 @@ class LegacyRestarter implements Restarter {
       ]);
     }
     final reloadCompleter = Completer<bool>();
-    StreamSubscription sub;
-    sub = window.onMessage.listen((event) {
+    final sub = window.onMessage.listen((event) {
       final message = event.data;
       if (message is Map &&
           message['type'] == 'DDC_STATE_CHANGE' &&
           message['state'] == 'restart_end') {
         reloadCompleter.complete(true);
-        sub.cancel();
       }
     });
-    return reloadCompleter.future;
+    return reloadCompleter.future.then((value) {
+      sub.cancel();
+      return value;
+    });
   }
 }

dwds/web/reloader/manager.dart

@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'dart:async';
 import 'dart:convert';
 import 'dart:html';
@@ -28,7 +26,7 @@ class ReloadingManager {
   /// - called hotRestart with the same runId
   ///
   /// The apps are restarted at the same time on the first call.
-  Future<bool> hotRestart({String runId}) async {
+  Future<bool> hotRestart({String? runId}) async {
     _beforeRestart();
     final result = await _restarter.restart(runId: runId);
     _afterRestart(result);

dwds/web/reloader/require_restarter.dart

@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 @JS()
 library require_reloading_manager;
 
@@ -23,7 +21,8 @@ import 'restarter.dart';
 /// The last known digests of all the modules in the application.
 ///
 /// This is updated in place during calls to hotRestart.
-Map<String, String> _lastKnownDigests;
+/// TODO(annagrin): can this be a private field in RequireRestarter?
+late Map<String, String> _lastKnownDigests;
 
 @JS(r'$requireLoader')
 external RequireLoader get requireLoader;
@@ -90,8 +89,8 @@ abstract class JsMap<K, V> {
 /// Handles hot restart reloading for use with the require module system.
 class RequireRestarter implements Restarter {
   final _moduleOrdering = HashMap<String, int>();
-  SplayTreeSet<String> _dirtyModules;
-  var _running = Completer<bool>()..complete();
+  late SplayTreeSet<String> _dirtyModules;
+  var _running = Completer<bool>()..complete(true);
 
   var count = 0;
 
@@ -100,7 +99,7 @@ class RequireRestarter implements Restarter {
   }
 
   @override
-  Future<bool> restart({String runId}) async {
+  Future<bool> restart({String? runId}) async {
     final developer = getProperty(require('dart_sdk'), 'developer');
     if (callMethod(getProperty(developer, '_extensions'), 'containsKey',
         ['ext.flutter.disassemble']) as bool) {
@@ -117,7 +116,7 @@ class RequireRestarter implements Restarter {
             'Unable to find an existing digest for module: $moduleId.');
         _reloadPage();
       } else if (_lastKnownDigests[moduleId] != newDigests[moduleId]) {
-        _lastKnownDigests[moduleId] = newDigests[moduleId];
+        _lastKnownDigests[moduleId] = newDigests[moduleId]!;
         modulesToLoad.add(moduleId);
       }
     }
@@ -145,7 +144,7 @@ class RequireRestarter implements Restarter {
   }
 
   List<String> _moduleParents(String module) =>
-      requireLoader.moduleParentsGraph.get(module)?.cast() ?? [];
+      requireLoader.moduleParentsGraph.get(module).cast();
 
   int _moduleTopologicalCompare(String module1, String module2) {
     var topological = 0;
@@ -159,8 +158,8 @@ class RequireRestarter implements Restarter {
           'Unable to fetch ordering info for module: $missing');
     }
 
-    topological =
-        Comparable.compare(_moduleOrdering[module2], _moduleOrdering[module1]);
+    topological = Comparable.compare(
+        _moduleOrdering[module2]!, _moduleOrdering[module1]!);
 
     if (topological == 0) {
       // If modules are in cycle (same strongly connected component) compare
@@ -183,13 +182,13 @@ class RequireRestarter implements Restarter {
     var reloadedModules = 0;
     try {
       _dirtyModules.addAll(modules);
-      String previousModuleId;
+      String? previousModuleId;
       while (_dirtyModules.isNotEmpty) {
         final moduleId = _dirtyModules.first;
         _dirtyModules.remove(moduleId);
         final parentIds = _moduleParents(moduleId);
         // Check if this is the root / bootstrap module.
-        if (parentIds == null || parentIds.isEmpty) {
+        if (parentIds.isEmpty) {
           // The bootstrap module is not reloaded but we need to update the
           // $dartRunMain reference to the newly loaded child module.
           final childModule = callMethod(

dwds/web/reloader/restarter.dart

@@ -2,10 +2,8 @@
 // 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.
 
-// @dart = 2.9
-
 abstract class Restarter {
   /// Attemps to perform a hot restart and returns whether it was successful or
   /// not.
-  Future<bool> restart({String runId});
+  Future<bool> restart({String? runId});
 }

dwds/web/run_main.dart

@@ -1,4 +1,7 @@
-// @dart = 2.9
+// Copyright (c) 2019, 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:html';
 
 /// Creates a script that will run properly when strict CSP is enforced.
@@ -15,7 +18,7 @@ final ScriptElement Function() _createScript = (() {
 final _noncePattern = RegExp('^[\\w+/_-]+[=]{0,2}\$');
 
 /// Returns CSP nonce, if set for any script tag.
-String _findNonce() {
+String? _findNonce() {
   final elements = window.document.querySelectorAll('script');
   for (final element in elements) {
     final nonceValue =
@@ -33,6 +36,6 @@ String _findNonce() {
 /// handling zone.
 void runMain() {
   final scriptElement = _createScript()..innerHtml = r'window.$dartRunMain();';
-  document.body.append(scriptElement);
+  document.body!.append(scriptElement);
   Future.microtask(scriptElement.remove);
 }