Migrate mdns_discovery and ios simulator to null safety (#92124)

packages/flutter_tools/lib/src/context_runner.dart

@@ -44,7 +44,7 @@ import 'flutter_features.dart';
 import 'fuchsia/fuchsia_device.dart' show FuchsiaDeviceTools;
 import 'fuchsia/fuchsia_sdk.dart' show FuchsiaSdk, FuchsiaArtifacts;
 import 'fuchsia/fuchsia_workflow.dart' show FuchsiaWorkflow, fuchsiaWorkflow;
-import 'globals.dart' as globals;
+import 'globals_null_migrated.dart' as globals;
 import 'ios/ios_workflow.dart';
 import 'ios/iproxy.dart';
 import 'ios/simulators.dart';

packages/flutter_tools/lib/src/globals.dart

@@ -6,9 +6,7 @@
 
 import 'base/context.dart';
 import 'doctor.dart';
-import 'ios/simulators.dart';
 
 export 'globals_null_migrated.dart';
 
 Doctor get doctor => context.get<Doctor>();
-IOSSimulatorUtils get iosSimulatorUtils => context.get<IOSSimulatorUtils>();

packages/flutter_tools/lib/src/globals_null_migrated.dart

@@ -31,6 +31,7 @@ import 'device.dart';
 import 'fuchsia/fuchsia_sdk.dart';
 import 'ios/ios_workflow.dart';
 import 'ios/plist_parser.dart';
+import 'ios/simulators.dart';
 import 'ios/xcodeproj.dart';
 import 'macos/cocoapods.dart';
 import 'macos/cocoapods_validator.dart';
@@ -54,6 +55,7 @@ Config get config => context.get<Config>()!;
 CrashReporter? get crashReporter => context.get<CrashReporter>();
 DeviceManager? get deviceManager => context.get<DeviceManager>();
 HttpClientFactory? get httpClientFactory => context.get<HttpClientFactory>();
+IOSSimulatorUtils? get iosSimulatorUtils => context.get<IOSSimulatorUtils>();
 Logger get logger => context.get<Logger>()!;
 OperatingSystemUtils get os => context.get<OperatingSystemUtils>()!;
 Signals get signals => context.get<Signals>() ?? LocalSignals.instance;

packages/flutter_tools/lib/src/ios/simulators.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'dart:async';
 import 'dart:math' as math;
 
@@ -34,7 +32,7 @@ const String iosSimulatorId = 'apple_ios_simulator';
 
 class IOSSimulators extends PollingDeviceDiscovery {
   IOSSimulators({
-    @required IOSSimulatorUtils iosSimulatorUtils,
+    required IOSSimulatorUtils iosSimulatorUtils,
   }) : _iosSimulatorUtils = iosSimulatorUtils,
        super('iOS simulators');
 
@@ -44,10 +42,10 @@ class IOSSimulators extends PollingDeviceDiscovery {
   bool get supportsPlatform => globals.platform.isMacOS;
 
   @override
-  bool get canListAnything => globals.iosWorkflow.canListDevices;
+  bool get canListAnything => globals.iosWorkflow?.canListDevices ?? false;
 
   @override
-  Future<List<Device>> pollingGetDevices({ Duration timeout }) async => _iosSimulatorUtils.getAttachedDevices();
+  Future<List<Device>> pollingGetDevices({ Duration? timeout }) async => _iosSimulatorUtils.getAttachedDevices();
 
   @override
   List<String> get wellKnownIds => const <String>[];
@@ -55,9 +53,9 @@ class IOSSimulators extends PollingDeviceDiscovery {
 
 class IOSSimulatorUtils {
   IOSSimulatorUtils({
-    @required Xcode xcode,
-    @required Logger logger,
-    @required ProcessManager processManager,
+    required Xcode xcode,
+    required Logger logger,
+    required ProcessManager processManager,
   })  : _simControl = SimControl(
           logger: logger,
           processManager: processManager,
@@ -74,23 +72,33 @@ class IOSSimulatorUtils {
     }
 
     final List<SimDevice> connected = await _simControl.getConnectedDevices();
-    return connected.map<IOSSimulator>((SimDevice device) {
+    return connected.map<IOSSimulator?>((SimDevice device) {
+      final String? udid = device.udid;
+      final String? name = device.name;
+      if (udid == null) {
+        globals.printTrace('Could not parse simulator udid');
+        return null;
+      }
+      if (name == null) {
+        globals.printTrace('Could not parse simulator name');
+        return null;
+      }
       return IOSSimulator(
-        device.udid,
-        name: device.name,
+        udid,
+        name: name,
         simControl: _simControl,
         simulatorCategory: device.category,
       );
-    }).toList();
+    }).whereType<IOSSimulator>().toList();
   }
 }
 
 /// A wrapper around the `simctl` command line tool.
 class SimControl {
   SimControl({
-    @required Logger logger,
-    @required ProcessManager processManager,
-    @required Xcode xcode,
+    required Logger logger,
+    required ProcessManager processManager,
+    required Xcode xcode,
   })  : _logger = logger,
         _xcode = xcode,
         _processUtils = ProcessUtils(processManager: processManager, logger: logger);
@@ -101,7 +109,7 @@ class SimControl {
 
   /// Runs `simctl list --json` and returns the JSON of the corresponding
   /// [section].
-  Future<Map<String, dynamic>> _list(SimControlListSection section) async {
+  Future<Map<String, Object?>> _list(SimControlListSection section) async {
     // Sample output from `simctl list --json`:
     //
     // {
@@ -130,21 +138,21 @@ class SimControl {
     final RunResult results = await _processUtils.run(command);
     if (results.exitCode != 0) {
       _logger.printError('Error executing simctl: ${results.exitCode}\n${results.stderr}');
-      return <String, Map<String, dynamic>>{};
+      return <String, Map<String, Object?>>{};
     }
     try {
-      final Object decodeResult = (json.decode(results.stdout) as Map<String, dynamic>)[section.name];
-      if (decodeResult is Map<String, dynamic>) {
+      final Object? decodeResult = (json.decode(results.stdout) as Map<String, Object?>)[section.name];
+      if (decodeResult is Map<String, Object?>) {
         return decodeResult;
       }
       _logger.printError('simctl returned unexpected JSON response: ${results.stdout}');
-      return <String, dynamic>{};
+      return <String, Object>{};
     } on FormatException {
       // We failed to parse the simctl output, or it returned junk.
       // One known message is "Install Started" isn't valid JSON but is
       // returned sometimes.
       _logger.printError('simctl returned non-JSON response: ${results.stdout}');
-      return <String, dynamic>{};
+      return <String, Object>{};
     }
   }
 
@@ -152,12 +160,12 @@ class SimControl {
   Future<List<SimDevice>> getDevices() async {
     final List<SimDevice> devices = <SimDevice>[];
 
-    final Map<String, dynamic> devicesSection = await _list(SimControlListSection.devices);
+    final Map<String, Object?> devicesSection = await _list(SimControlListSection.devices);
 
     for (final String deviceCategory in devicesSection.keys) {
-      final Object devicesData = devicesSection[deviceCategory];
-      if (devicesData != null && devicesData is List<dynamic>) {
-        for (final Map<String, dynamic> data in devicesData.map<Map<String, dynamic>>(castStringKeyedMap)) {
+      final Object? devicesData = devicesSection[deviceCategory];
+      if (devicesData != null && devicesData is List<Object?>) {
+        for (final Map<String, Object?> data in devicesData.map<Map<String, Object?>?>(castStringKeyedMap).whereType<Map<String, Object?>>()) {
           devices.add(SimDevice(deviceCategory, data));
         }
       }
@@ -220,7 +228,7 @@ class SimControl {
     return result;
   }
 
-  Future<RunResult> launch(String deviceId, String appIdentifier, [ List<String> launchArgs ]) async {
+  Future<RunResult> launch(String deviceId, String appIdentifier, [ List<String>? launchArgs ]) async {
     RunResult result;
     try {
       result = await _processUtils.run(
@@ -299,12 +307,12 @@ class SimDevice {
   SimDevice(this.category, this.data);
 
   final String category;
-  final Map<String, dynamic> data;
+  final Map<String, Object?> data;
 
-  String get state => data['state']?.toString();
-  String get availability => data['availability']?.toString();
-  String get name => data['name']?.toString();
-  String get udid => data['udid']?.toString();
+  String? get state => data['state']?.toString();
+  String? get availability => data['availability']?.toString();
+  String? get name => data['name']?.toString();
+  String? get udid => data['udid']?.toString();
 
   bool get isBooted => state == 'Booted';
 }
@@ -312,9 +320,9 @@ class SimDevice {
 class IOSSimulator extends Device {
   IOSSimulator(
     String id, {
-      this.name,
-      this.simulatorCategory,
-      @required SimControl simControl,
+      required this.name,
+      required this.simulatorCategory,
+      required SimControl simControl,
     }) : _simControl = simControl,
          super(
            id,
@@ -353,13 +361,13 @@ class IOSSimulator extends Device {
   @override
   bool supportsRuntimeMode(BuildMode buildMode) => buildMode == BuildMode.debug;
 
-  Map<ApplicationPackage, _IOSSimulatorLogReader> _logReaders;
-  _IOSSimulatorDevicePortForwarder _portForwarder;
+  final Map<IOSApp?, DeviceLogReader> _logReaders = <IOSApp?, DeviceLogReader>{};
+  _IOSSimulatorDevicePortForwarder? _portForwarder;
 
   @override
   Future<bool> isAppInstalled(
     ApplicationPackage app, {
-    String userIdentifier,
+    String? userIdentifier,
   }) {
     return _simControl.isInstalled(id, app.id);
   }
@@ -370,7 +378,7 @@ class IOSSimulator extends Device {
   @override
   Future<bool> installApp(
     covariant IOSApp app, {
-    String userIdentifier,
+    String? userIdentifier,
   }) async {
     try {
       final IOSApp iosApp = app;
@@ -384,7 +392,7 @@ class IOSSimulator extends Device {
   @override
   Future<bool> uninstallApp(
     ApplicationPackage app, {
-    String userIdentifier,
+    String? userIdentifier,
   }) async {
     try {
       await _simControl.uninstall(id, app.id);
@@ -411,7 +419,7 @@ class IOSSimulator extends Device {
     return true;
   }
 
-  String _supportMessage;
+  String? _supportMessage;
 
   @override
   String supportMessage() {
@@ -425,13 +433,13 @@ class IOSSimulator extends Device {
   @override
   Future<LaunchResult> startApp(
     covariant IOSApp package, {
-    String mainPath,
-    String route,
-    DebuggingOptions debuggingOptions,
-    Map<String, dynamic> platformArgs,
+    String? mainPath,
+    String? route,
+    required DebuggingOptions debuggingOptions,
+    Map<String, Object?> platformArgs = const <String, Object?>{},
     bool prebuiltApplication = false,
     bool ipv6 = false,
-    String userIdentifier,
+    String? userIdentifier,
   }) async {
     if (!prebuiltApplication && package is BuildableIOSApp) {
       globals.printTrace('Building ${package.name} for $id.');
@@ -439,7 +447,7 @@ class IOSSimulator extends Device {
       try {
         await _setupUpdatedApplicationBundle(package, debuggingOptions.buildInfo, mainPath);
       } on ToolExit catch (e) {
-        globals.printError(e.message);
+        globals.printError('${e.message}');
         return LaunchResult.failed();
       }
     } else {
@@ -469,7 +477,7 @@ class IOSSimulator extends Device {
       ],
     ];
 
-    ProtocolDiscovery observatoryDiscovery;
+    ProtocolDiscovery? observatoryDiscovery;
     if (debuggingOptions.debuggingEnabled) {
       observatoryDiscovery = ProtocolDiscovery.observatory(
         getLogReader(app: package),
@@ -487,7 +495,11 @@ class IOSSimulator extends Device {
       // parsing the xcodeproj or configuration files.
       // See https://github.com/flutter/flutter/issues/31037 for more information.
       final String plistPath = globals.fs.path.join(package.simulatorBundlePath, 'Info.plist');
-      final String bundleIdentifier = globals.plistParser.getValueFromFile(plistPath, PlistParser.kCFBundleIdentifierKey);
+      final String? bundleIdentifier = globals.plistParser.getValueFromFile(plistPath, PlistParser.kCFBundleIdentifierKey);
+      if (bundleIdentifier == null) {
+        globals.printError('Invalid prebuilt iOS app. Info.plist does not contain bundle identifier');
+        return LaunchResult.failed();
+      }
 
       await _simControl.launch(id, bundleIdentifier, args);
     } on Exception catch (error) {
@@ -504,7 +516,7 @@ class IOSSimulator extends Device {
     globals.printTrace('Waiting for observatory port to be available...');
 
     try {
-      final Uri deviceUri = await observatoryDiscovery.uri;
+      final Uri? deviceUri = await observatoryDiscovery?.uri;
       if (deviceUri != null) {
         return LaunchResult.succeeded(observatoryUri: deviceUri);
       }
@@ -520,7 +532,7 @@ class IOSSimulator extends Device {
     return LaunchResult.failed();
   }
 
-  Future<void> _setupUpdatedApplicationBundle(covariant BuildableIOSApp app, BuildInfo buildInfo, String mainPath) async {
+  Future<void> _setupUpdatedApplicationBundle(covariant BuildableIOSApp app, BuildInfo buildInfo, String? mainPath) async {
     // Step 1: Build the Xcode project.
     // The build mode for the simulator is always debug.
     assert(buildInfo.isDebug);
@@ -550,17 +562,18 @@ class IOSSimulator extends Device {
   @override
   Future<bool> stopApp(
     ApplicationPackage app, {
-    String userIdentifier,
+    String? userIdentifier,
   }) async {
     // Currently we don't have a way to stop an app running on iOS.
     return false;
   }
 
   String get logFilePath {
-    return globals.platform.environment.containsKey('IOS_SIMULATOR_LOG_FILE_PATH')
-      ? globals.platform.environment['IOS_SIMULATOR_LOG_FILE_PATH'].replaceAll('%{id}', id)
+    final String? logPath = globals.platform.environment['IOS_SIMULATOR_LOG_FILE_PATH'];
+    return logPath != null
+      ? logPath.replaceAll('%{id}', id)
       : globals.fs.path.join(
-          globals.fsUtils.homeDirPath,
+          globals.fsUtils.homeDirPath!,
           'Library',
           'Logs',
           'CoreSimulator',
@@ -578,18 +591,16 @@ class IOSSimulator extends Device {
   final RegExp _iosSdkRegExp = RegExp(r'iOS( |-)(\d+)');
 
   Future<int> get sdkMajorVersion async {
-    final Match sdkMatch = _iosSdkRegExp.firstMatch(await sdkNameAndVersion);
+    final Match? sdkMatch = _iosSdkRegExp.firstMatch(await sdkNameAndVersion);
     return int.parse(sdkMatch?.group(2) ?? '11');
   }
 
   @override
   DeviceLogReader getLogReader({
-    covariant IOSApp app,
+    IOSApp? app,
     bool includePastLogs = false,
   }) {
-    assert(app == null || app is IOSApp);
     assert(!includePastLogs, 'Past log reading not supported on iOS simulators.');
-    _logReaders ??= <ApplicationPackage, _IOSSimulatorLogReader>{};
     return _logReaders.putIfAbsent(app, () => _IOSSimulatorLogReader(this, app));
   }
 
@@ -630,11 +641,9 @@ class IOSSimulator extends Device {
 
   @override
   Future<void> dispose() async {
-    _logReaders?.forEach(
-      (ApplicationPackage application, _IOSSimulatorLogReader logReader) {
-        logReader.dispose();
-      },
-    );
+    for (final DeviceLogReader logReader in _logReaders.values) {
+      logReader.dispose();
+    }
     await _portForwarder?.dispose();
   }
 }
@@ -647,7 +656,7 @@ Future<Process> launchDeviceSystemLogTool(IOSSimulator device) async {
 
 /// Launches the device log reader process on the host and parses unified logging.
 @visibleForTesting
-Future<Process> launchDeviceUnifiedLogging (IOSSimulator device, String appName) async {
+Future<Process> launchDeviceUnifiedLogging (IOSSimulator device, String? appName) async {
   // Make NSPredicate concatenation easier to read.
   String orP(List<String> clauses) => '(${clauses.join(" OR ")})';
   String andP(List<String> clauses) => clauses.join(' AND ');
@@ -669,7 +678,7 @@ Future<Process> launchDeviceUnifiedLogging (IOSSimulator device, String appName)
   ]);
 
   return globals.processUtils.start(<String>[
-    ...globals.xcode.xcrunCommand(),
+    ...globals.xcode!.xcrunCommand(),
     'simctl',
     'spawn',
     device.id,
@@ -683,7 +692,7 @@ Future<Process> launchDeviceUnifiedLogging (IOSSimulator device, String appName)
 }
 
 @visibleForTesting
-Future<Process> launchSystemLogTool(IOSSimulator device) async {
+Future<Process?> launchSystemLogTool(IOSSimulator device) async {
   // Versions of iOS prior to 11 tail the simulator syslog file.
   if (await device.sdkMajorVersion < 11) {
     return globals.processUtils.start(<String>['tail', '-n', '0', '-F', '/private/var/log/system.log']);
@@ -694,23 +703,20 @@ Future<Process> launchSystemLogTool(IOSSimulator device) async {
 }
 
 class _IOSSimulatorLogReader extends DeviceLogReader {
-  _IOSSimulatorLogReader(this.device, IOSApp app) {
-    _linesController = StreamController<String>.broadcast(
-      onListen: _start,
-      onCancel: _stop,
-    );
-    _appName = app?.name?.replaceAll('.app', '');
-  }
+  _IOSSimulatorLogReader(this.device, IOSApp? app) : _appName = app?.name?.replaceAll('.app', '');
 
   final IOSSimulator device;
 
-  String _appName;
+  final String? _appName;
 
-  StreamController<String> _linesController;
+  late final StreamController<String> _linesController = StreamController<String>.broadcast(
+    onListen: _start,
+    onCancel: _stop,
+  );
 
   // We log from two files: the device and the system log.
-  Process _deviceProcess;
-  Process _systemProcess;
+  Process? _deviceProcess;
+  Process? _systemProcess;
 
   @override
   Stream<String> get logLines => _linesController.stream;
@@ -722,27 +728,27 @@ class _IOSSimulatorLogReader extends DeviceLogReader {
     // Unified logging iOS 11 and greater (introduced in iOS 10).
     if (await device.sdkMajorVersion >= 11) {
       _deviceProcess = await launchDeviceUnifiedLogging(device, _appName);
-      _deviceProcess.stdout.transform<String>(utf8.decoder).transform<String>(const LineSplitter()).listen(_onUnifiedLoggingLine);
-      _deviceProcess.stderr.transform<String>(utf8.decoder).transform<String>(const LineSplitter()).listen(_onUnifiedLoggingLine);
+      _deviceProcess?.stdout.transform<String>(utf8.decoder).transform<String>(const LineSplitter()).listen(_onUnifiedLoggingLine);
+      _deviceProcess?.stderr.transform<String>(utf8.decoder).transform<String>(const LineSplitter()).listen(_onUnifiedLoggingLine);
     } else {
       // Fall back to syslog parsing.
       await device.ensureLogsExists();
       _deviceProcess = await launchDeviceSystemLogTool(device);
-      _deviceProcess.stdout.transform<String>(utf8.decoder).transform<String>(const LineSplitter()).listen(_onSysLogDeviceLine);
-      _deviceProcess.stderr.transform<String>(utf8.decoder).transform<String>(const LineSplitter()).listen(_onSysLogDeviceLine);
+      _deviceProcess?.stdout.transform<String>(utf8.decoder).transform<String>(const LineSplitter()).listen(_onSysLogDeviceLine);
+      _deviceProcess?.stderr.transform<String>(utf8.decoder).transform<String>(const LineSplitter()).listen(_onSysLogDeviceLine);
     }
 
     // Track system.log crashes.
     // ReportCrash[37965]: Saved crash report for FlutterRunner[37941]...
     _systemProcess = await launchSystemLogTool(device);
     if (_systemProcess != null) {
-      _systemProcess.stdout.transform<String>(utf8.decoder).transform<String>(const LineSplitter()).listen(_onSystemLine);
-      _systemProcess.stderr.transform<String>(utf8.decoder).transform<String>(const LineSplitter()).listen(_onSystemLine);
+      _systemProcess?.stdout.transform<String>(utf8.decoder).transform<String>(const LineSplitter()).listen(_onSystemLine);
+      _systemProcess?.stderr.transform<String>(utf8.decoder).transform<String>(const LineSplitter()).listen(_onSystemLine);
     }
 
     // We don't want to wait for the process or its callback. Best effort
     // cleanup in the callback.
-    unawaited(_deviceProcess.exitCode.whenComplete(() {
+    unawaited(_deviceProcess?.exitCode.whenComplete(() {
       if (_linesController.hasListener) {
         _linesController.close();
       }
@@ -764,19 +770,20 @@ class _IOSSimulatorLogReader extends DeviceLogReader {
   // a multiline record
   bool _lastLineMatched = false;
 
-  String _filterDeviceLine(String string) {
-    final Match match = _mapRegex.matchAsPrefix(string);
+  String? _filterDeviceLine(String string) {
+    final Match? match = _mapRegex.matchAsPrefix(string);
     if (match != null) {
 
       // The category contains the text between the date and the PID. Depending on which version of iOS being run,
       // it can contain "hostname App Name" or just "App Name".
-      final String category = match.group(1);
-      final String tag = match.group(2);
-      final String content = match.group(3);
+      final String? category = match.group(1);
+      final String? tag = match.group(2);
+      final String? content = match.group(3);
 
       // Filter out log lines from an app other than this one (category doesn't match the app name).
       // If the hostname is included in the category, check that it doesn't end with the app name.
-      if (_appName != null && !category.endsWith(_appName)) {
+      final String? appName = _appName;
+      if (appName != null && category != null && !category.endsWith(appName)) {
         return null;
       }
 
@@ -790,13 +797,13 @@ class _IOSSimulatorLogReader extends DeviceLogReader {
       }
 
       // assertion failed: 15G1212 13E230: libxpc.dylib + 57882 [66C28065-C9DB-3C8E-926F-5A40210A6D1B]: 0x7d
-      if (content.startsWith('assertion failed: ') && content.contains(' libxpc.dylib ')) {
+      if (content != null && content.startsWith('assertion failed: ') && content.contains(' libxpc.dylib ')) {
         return null;
       }
 
-      if (_appName == null) {
+      if (appName == null) {
         return '$category: $content';
-      } else if (category == _appName || category.endsWith(' $_appName')) {
+      } else if (category != null && (category == appName || category.endsWith(' $appName'))) {
         return content;
       }
 
@@ -827,24 +834,24 @@ class _IOSSimulatorLogReader extends DeviceLogReader {
     return string;
   }
 
-  String _lastLine;
+  String? _lastLine;
 
   void _onSysLogDeviceLine(String line) {
     globals.printTrace('[DEVICE LOG] $line');
-    final Match multi = _lastMessageMultipleRegex.matchAsPrefix(line);
+    final Match? multi = _lastMessageMultipleRegex.matchAsPrefix(line);
 
     if (multi != null) {
       if (_lastLine != null) {
-        int repeat = int.parse(multi.group(1));
+        int repeat = int.parse(multi.group(1)!);
         repeat = math.max(0, math.min(100, repeat));
         for (int i = 1; i < repeat; i++) {
-          _linesController.add(_lastLine);
+          _linesController.add(_lastLine!);
         }
       }
     } else {
       _lastLine = _filterDeviceLine(line);
       if (_lastLine != null) {
-        _linesController.add(_lastLine);
+        _linesController.add(_lastLine!);
         _lastLineMatched = true;
       } else {
         _lastLineMatched = false;
@@ -856,11 +863,11 @@ class _IOSSimulatorLogReader extends DeviceLogReader {
   static final RegExp _unifiedLoggingEventMessageRegex = RegExp(r'.*"eventMessage" : (".*")');
   void _onUnifiedLoggingLine(String line) {
     // The log command predicate handles filtering, so every log eventMessage should be decoded and added.
-    final Match eventMessageMatch = _unifiedLoggingEventMessageRegex.firstMatch(line);
+    final Match? eventMessageMatch = _unifiedLoggingEventMessageRegex.firstMatch(line);
     if (eventMessageMatch != null) {
-      final String message = eventMessageMatch.group(1);
+      final String message = eventMessageMatch.group(1)!;
       try {
-        final dynamic decodedJson = jsonDecode(message);
+        final Object? decodedJson = jsonDecode(message);
         if (decodedJson is String) {
           _linesController.add(decodedJson);
         }
@@ -871,7 +878,7 @@ class _IOSSimulatorLogReader extends DeviceLogReader {
   }
 
   String _filterSystemLog(String string) {
-    final Match match = _mapRegex.matchAsPrefix(string);
+    final Match? match = _mapRegex.matchAsPrefix(string);
     return match == null ? string : '${match.group(1)}: ${match.group(2)}';
   }
 
@@ -916,37 +923,6 @@ int compareIosVersions(String v1, String v2) {
   return v1Fragments.length.compareTo(v2Fragments.length);
 }
 
-/// Matches on device type given an identifier.
-///
-/// Example device type identifiers:
-///
-/// - ✓ com.apple.CoreSimulator.SimDeviceType.iPhone-5
-/// - ✓ com.apple.CoreSimulator.SimDeviceType.iPhone-6
-/// - ✓ com.apple.CoreSimulator.SimDeviceType.iPhone-6s-Plus
-/// - ✗ com.apple.CoreSimulator.SimDeviceType.iPad-2
-/// - ✗ com.apple.CoreSimulator.SimDeviceType.Apple-Watch-38mm
-final RegExp _iosDeviceTypePattern =
-    RegExp(r'com.apple.CoreSimulator.SimDeviceType.iPhone-(\d+)(.*)');
-
-int compareIphoneVersions(String id1, String id2) {
-  final Match m1 = _iosDeviceTypePattern.firstMatch(id1);
-  final Match m2 = _iosDeviceTypePattern.firstMatch(id2);
-
-  final int v1 = int.parse(m1[1]);
-  final int v2 = int.parse(m2[1]);
-
-  if (v1 != v2) {
-    return v1.compareTo(v2);
-  }
-
-  // Sorted in the least preferred first order.
-  const List<String> qualifiers = <String>['-Plus', '', 's-Plus', 's'];
-
-  final int q1 = qualifiers.indexOf(m1[2]);
-  final int q2 = qualifiers.indexOf(m2[2]);
-  return q1.compareTo(q2);
-}
-
 class _IOSSimulatorDevicePortForwarder extends DevicePortForwarder {
   _IOSSimulatorDevicePortForwarder(this.device);
 
@@ -958,7 +934,7 @@ class _IOSSimulatorDevicePortForwarder extends DevicePortForwarder {
   List<ForwardedPort> get forwardedPorts => _ports;
 
   @override
-  Future<int> forward(int devicePort, { int hostPort }) async {
+  Future<int> forward(int devicePort, { int? hostPort }) async {
     if (hostPort == null || hostPort == 0) {
       hostPort = devicePort;
     }

packages/flutter_tools/lib/src/mdns_discovery.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'package:meta/meta.dart';
 import 'package:multicast_dns/multicast_dns.dart';
 
@@ -24,9 +22,9 @@ class MDnsObservatoryDiscovery {
   /// automatically select which application to use if multiple are advertising
   /// Dart observatory ports.
   MDnsObservatoryDiscovery({
-    MDnsClient mdnsClient,
-    @required Logger logger,
-    @required Usage flutterUsage,
+    MDnsClient? mdnsClient,
+    required Logger logger,
+    required Usage flutterUsage,
   }): _client = mdnsClient ?? MDnsClient(),
       _logger = logger,
       _flutterUsage = flutterUsage;
@@ -38,7 +36,7 @@ class MDnsObservatoryDiscovery {
   @visibleForTesting
   static const String dartObservatoryName = '_dartobservatory._tcp.local';
 
-  static MDnsObservatoryDiscovery get instance => context.get<MDnsObservatoryDiscovery>();
+  static MDnsObservatoryDiscovery? get instance => context.get<MDnsObservatoryDiscovery>();
 
   /// Executes an mDNS query for a Dart Observatory.
   ///
@@ -59,7 +57,7 @@ class MDnsObservatoryDiscovery {
   /// it will return that instance's information regardless of what application
   /// the Observatory instance is for.
   @visibleForTesting
-  Future<MDnsObservatoryDiscoveryResult> query({String applicationId, int deviceVmservicePort}) async {
+  Future<MDnsObservatoryDiscoveryResult?> query({String? applicationId, int? deviceVmservicePort}) async {
     _logger.printTrace('Checking for advertised Dart observatories...');
     try {
       await _client.start();
@@ -78,7 +76,7 @@ class MDnsObservatoryDiscovery {
         .map<String>((PtrResourceRecord record) => record.domainName)
         .toSet();
 
-      String domainName;
+      String? domainName;
       if (applicationId != null) {
         for (final String name in uniqueDomainNames) {
           if (name.toLowerCase().startsWith(applicationId.toLowerCase())) {
@@ -93,7 +91,7 @@ class MDnsObservatoryDiscovery {
         final StringBuffer buffer = StringBuffer();
         buffer.writeln('There are multiple observatory ports available.');
         buffer.writeln('Rerun this command with one of the following passed in as the appId:');
-        buffer.writeln('');
+        buffer.writeln();
         for (final String uniqueDomainName in uniqueDomainNames) {
           buffer.writeln('  flutter attach --app-id ${uniqueDomainName.replaceAll('.$dartObservatoryName', '')}');
         }
@@ -120,15 +118,18 @@ class MDnsObservatoryDiscovery {
         .lookup<TxtResourceRecord>(
             ResourceRecordQuery.text(domainName),
         )
-        ?.toList();
+        .toList();
       if (txt == null || txt.isEmpty) {
         return MDnsObservatoryDiscoveryResult(srv.first.port, '');
       }
       const String authCodePrefix = 'authCode=';
-      final String raw = txt.first.text.split('\n').firstWhere(
-        (String s) => s.startsWith(authCodePrefix),
-        orElse: () => null,
-      );
+      String? raw;
+      for (final String record in txt.first.text.split('\n')) {
+        if (record.startsWith(authCodePrefix)) {
+          raw = record;
+          break;
+        }
+      }
       if (raw == null) {
         return MDnsObservatoryDiscoveryResult(srv.first.port, '');
       }
@@ -144,12 +145,12 @@ class MDnsObservatoryDiscovery {
     }
   }
 
-  Future<Uri> getObservatoryUri(String applicationId, Device device, {
+  Future<Uri?> getObservatoryUri(String applicationId, Device device, {
     bool usesIpv6 = false,
-    int hostVmservicePort,
-    int deviceVmservicePort,
+    int? hostVmservicePort,
+    int? deviceVmservicePort,
   }) async {
-    final MDnsObservatoryDiscoveryResult result = await query(
+    final MDnsObservatoryDiscoveryResult? result = await query(
       applicationId: applicationId,
       deviceVmservicePort: deviceVmservicePort,
     );
@@ -246,8 +247,8 @@ Future<Uri> buildObservatoryUri(
   Device device,
   String host,
   int devicePort, [
-  int hostVmservicePort,
-  String authCode,
+  int? hostVmservicePort,
+  String? authCode,
 ]) async {
   String path = '/';
   if (authCode != null) {
@@ -259,8 +260,8 @@ Future<Uri> buildObservatoryUri(
     path += '/';
   }
   hostVmservicePort ??= 0;
-  final int actualHostPort = hostVmservicePort == 0 ?
-    await device.portForwarder.forward(devicePort) :
+  final int? actualHostPort = hostVmservicePort == 0 ?
+    await device.portForwarder?.forward(devicePort) :
     hostVmservicePort;
   return Uri(scheme: 'http', host: host, port: actualHostPort, path: path);
 }

packages/flutter_tools/lib/src/sksl_writer.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'dart:async';
 
 import 'package:file/file.dart';
@@ -15,9 +13,9 @@ import 'convert.dart';
 import 'device.dart';
 import 'globals_null_migrated.dart' as globals;
 
-Future<String> sharedSkSlWriter(Device device, Map<String, Object> data, {
-  File outputFile,
-  Logger logger,
+Future<String?> sharedSkSlWriter(Device device, Map<String, Object> data, {
+  File? outputFile,
+  Logger? logger,
 }) async {
   logger ??= globals.logger;
   if (data.isEmpty) {

packages/flutter_tools/test/general.shard/ios/simulators_test.dart

@@ -59,7 +59,9 @@ void main() {
     testUsingContext('dispose() does not throw an exception', () async {
       final IOSSimulator simulator = IOSSimulator(
         '123',
+        name: 'iPhone 11',
         simControl: simControl,
+        simulatorCategory: 'com.apple.CoreSimulator.SimRuntime.iOS-14-4',
       );
       final DevicePortForwarder portForwarder = simulator.portForwarder;
       await portForwarder.forward(123);
@@ -82,7 +84,9 @@ void main() {
   testUsingContext('simulators only support debug mode', () async {
     final IOSSimulator simulator = IOSSimulator(
       '123',
+      name: 'iPhone 11',
       simControl: FakeSimControl(),
+      simulatorCategory: 'com.apple.CoreSimulator.SimRuntime.iOS-14-4',
     );
 
     expect(simulator.supportsRuntimeMode(BuildMode.debug), true);
@@ -106,7 +110,9 @@ void main() {
       osx.environment['HOME'] = '/foo/bar';
       final IOSSimulator simulator = IOSSimulator(
         '123',
+        name: 'iPhone 11',
         simControl: simControl,
+        simulatorCategory: 'com.apple.CoreSimulator.SimRuntime.iOS-14-4',
       );
       expect(simulator.logFilePath, '/foo/bar/Library/Logs/CoreSimulator/123/system.log');
     }, overrides: <Type, Generator>{
@@ -121,7 +127,9 @@ void main() {
       osx.environment['IOS_SIMULATOR_LOG_FILE_PATH'] = '/baz/qux/%{id}/system.log';
       final IOSSimulator simulator = IOSSimulator(
         '456',
+        name: 'iPhone 11',
         simControl: simControl,
+        simulatorCategory: 'com.apple.CoreSimulator.SimRuntime.iOS-14-4',
       );
       expect(simulator.logFilePath, '/baz/qux/456/system.log');
     }, overrides: <Type, Generator>{
@@ -154,33 +162,6 @@ void main() {
     });
   });
 
-  group('compareIphoneVersions', () {
-    testWithoutContext('compares correctly', () {
-      // This list must be sorted in ascending preference order
-      final List<String> testList = <String>[
-        'com.apple.CoreSimulator.SimDeviceType.iPhone-4s',
-        'com.apple.CoreSimulator.SimDeviceType.iPhone-5',
-        'com.apple.CoreSimulator.SimDeviceType.iPhone-5s',
-        'com.apple.CoreSimulator.SimDeviceType.iPhone-6strange',
-        'com.apple.CoreSimulator.SimDeviceType.iPhone-6-Plus',
-        'com.apple.CoreSimulator.SimDeviceType.iPhone-6',
-        'com.apple.CoreSimulator.SimDeviceType.iPhone-6s-Plus',
-        'com.apple.CoreSimulator.SimDeviceType.iPhone-6s',
-      ];
-
-      for (int i = 0; i < testList.length; i++) {
-        expect(compareIphoneVersions(testList[i], testList[i]), 0);
-      }
-
-      for (int i = 0; i < testList.length - 1; i++) {
-        for (int j = i + 1; j < testList.length; j++) {
-          expect(compareIphoneVersions(testList[i], testList[j]), lessThan(0));
-          expect(compareIphoneVersions(testList[j], testList[i]), greaterThan(0));
-        }
-      }
-    });
-  });
-
   group('sdkMajorVersion', () {
     FakeSimControl simControl;
 
@@ -235,6 +216,7 @@ void main() {
         'x',
         name: 'Apple TV',
         simControl: simControl,
+        simulatorCategory: 'com.apple.CoreSimulator.SimRuntime.tvOS-14-5',
       );
       expect(simulator.isSupported(), false);
     }, overrides: <Type, Generator>{
@@ -248,6 +230,7 @@ void main() {
         'x',
         name: 'Apple Watch',
         simControl: simControl,
+        simulatorCategory: 'com.apple.CoreSimulator.SimRuntime.watchOS-8-0',
       ).isSupported(), false);
     }, overrides: <Type, Generator>{
       Platform: () => osx,
@@ -260,6 +243,7 @@ void main() {
         'x',
         name: 'iPad 2',
         simControl: simControl,
+        simulatorCategory: 'com.apple.CoreSimulator.SimRuntime.iOS-11-3',
       ).isSupported(), true);
     }, overrides: <Type, Generator>{
       Platform: () => osx,
@@ -272,6 +256,7 @@ void main() {
         'x',
         name: 'iPad Retina',
         simControl: simControl,
+        simulatorCategory: 'com.apple.CoreSimulator.SimRuntime.iOS-11-3',
       ).isSupported(), true);
     }, overrides: <Type, Generator>{
       Platform: () => osx,
@@ -284,6 +269,7 @@ void main() {
         'x',
         name: 'iPhone 5',
         simControl: simControl,
+        simulatorCategory: 'com.apple.CoreSimulator.SimRuntime.iOS-11-3',
       ).isSupported(), true);
     }, overrides: <Type, Generator>{
       Platform: () => osx,
@@ -296,6 +282,7 @@ void main() {
         'x',
         name: 'iPhone 5s',
         simControl: simControl,
+        simulatorCategory: 'com.apple.CoreSimulator.SimRuntime.iOS-11-3',
       ).isSupported(), true);
     }, overrides: <Type, Generator>{
       Platform: () => osx,
@@ -308,6 +295,7 @@ void main() {
         'x',
         name: 'iPhone SE',
         simControl: simControl,
+        simulatorCategory: 'com.apple.CoreSimulator.SimRuntime.iOS-11-3',
       ).isSupported(), true);
     }, overrides: <Type, Generator>{
       Platform: () => osx,
@@ -320,6 +308,7 @@ void main() {
         'x',
         name: 'iPhone 7 Plus',
         simControl: simControl,
+        simulatorCategory: 'com.apple.CoreSimulator.SimRuntime.iOS-11-3',
       ).isSupported(), true);
     }, overrides: <Type, Generator>{
       Platform: () => osx,
@@ -332,6 +321,7 @@ void main() {
         'x',
         name: 'iPhone X',
         simControl: simControl,
+        simulatorCategory: 'com.apple.CoreSimulator.SimRuntime.iOS-11-3',
       ).isSupported(), true);
     }, overrides: <Type, Generator>{
       Platform: () => osx,
@@ -368,6 +358,7 @@ void main() {
         'x',
         name: 'iPhone SE',
         simControl: simControl,
+        simulatorCategory: 'com.apple.CoreSimulator.SimRuntime.iOS-11-3',
       );
 
       final File screenshot = MemoryFileSystem.test().file('screenshot.png');
@@ -513,6 +504,7 @@ Dec 20 17:04:32 md32-11-vm1 Another App[88374]: Ignore this text'''
 
         final IOSSimulator device = IOSSimulator(
           '123456',
+          name: 'iPhone 11',
           simulatorCategory: 'iOS 10.0',
           simControl: simControl,
         );
@@ -547,6 +539,7 @@ Dec 20 17:04:32 md32-11-vm1 Another App[88374]: Ignore this text'''
 
         final IOSSimulator device = IOSSimulator(
           '123456',
+          name: 'iPhone 11',
           simulatorCategory: 'iOS 10.3',
           simControl: simControl,
         );
@@ -594,6 +587,7 @@ Dec 20 17:04:32 md32-11-vm1 Another App[88374]: Ignore this text'''
 
         final IOSSimulator device = IOSSimulator(
           '123456',
+          name: 'iPhone 11',
           simulatorCategory: 'iOS 10.3',
           simControl: simControl,
         );
@@ -665,6 +659,7 @@ Dec 20 17:04:32 md32-11-vm1 Another App[88374]: Ignore this text'''
 
         final IOSSimulator device = IOSSimulator(
           '123456',
+          name: 'iPhone 11',
           simulatorCategory: 'iOS 11.0',
           simControl: simControl,
         );
@@ -707,6 +702,7 @@ Dec 20 17:04:32 md32-11-vm1 Another App[88374]: Ignore this text'''
 
         final IOSSimulator device = IOSSimulator(
           '123456',
+          name: 'iPhone 11',
           simulatorCategory: 'iOS 11.0',
           simControl: simControl,
         );
@@ -902,11 +898,13 @@ Dec 20 17:04:32 md32-11-vm1 Another App[88374]: Ignore this text'''
     FakePlistParser testPlistParser;
     FakeSimControl simControl;
     Xcode xcode;
+    BufferLogger logger;
 
     setUp(() {
       simControl = FakeSimControl();
       xcode = Xcode.test(processManager: FakeProcessManager.any());
       testPlistParser = FakePlistParser();
+      logger = BufferLogger.test();
     });
 
     testUsingContext("startApp uses compiled app's Info.plist to find CFBundleIdentifier", () async {
@@ -933,7 +931,7 @@ Dec 20 17:04:32 md32-11-vm1 Another App[88374]: Ignore this text'''
       Xcode: () => xcode,
     });
 
-    testUsingContext('startApp respects the enable software rendering flag', () async {
+    testUsingContext('startApp fails when cannot find CFBundleIdentifier', () async {
       final IOSSimulator device = IOSSimulator(
         'x',
         name: 'iPhone SE',
@@ -944,6 +942,33 @@ Dec 20 17:04:32 md32-11-vm1 Another App[88374]: Ignore this text'''
       final Directory mockDir = globals.fs.currentDirectory;
       final IOSApp package = PrebuiltIOSApp(projectBundleId: 'incorrect', bundleName: 'name', bundleDir: mockDir);
 
+      const BuildInfo mockInfo = BuildInfo(BuildMode.debug, 'flavor', treeShakeIcons: false);
+      final DebuggingOptions mockOptions = DebuggingOptions.disabled(mockInfo);
+      final LaunchResult result = await device.startApp(package, prebuiltApplication: true, debuggingOptions: mockOptions);
+
+      expect(result.started, isFalse);
+      expect(simControl.requests, isEmpty);
+      expect(logger.errorText, contains('Invalid prebuilt iOS app. Info.plist does not contain bundle identifier'));
+    }, overrides: <Type, Generator>{
+      PlistParser: () => testPlistParser,
+      FileSystem: () => fileSystem,
+      ProcessManager: () => FakeProcessManager.any(),
+      Logger: () => logger,
+      Xcode: () => xcode,
+    });
+
+    testUsingContext('startApp respects the enable software rendering flag', () async {
+      final IOSSimulator device = IOSSimulator(
+        'x',
+        name: 'iPhone SE',
+        simulatorCategory: 'iOS 11.2',
+        simControl: simControl,
+      );
+      testPlistParser.setProperty('CFBundleIdentifier', 'correct');
+
+      final Directory mockDir = globals.fs.currentDirectory;
+      final IOSApp package = PrebuiltIOSApp(projectBundleId: 'correct', bundleName: 'name', bundleDir: mockDir);
+
       const BuildInfo mockInfo = BuildInfo(BuildMode.debug, 'flavor', treeShakeIcons: false);
       final DebuggingOptions mockOptions = DebuggingOptions.enabled(mockInfo, enableSoftwareRendering: true);
       await device.startApp(package, prebuiltApplication: true, debuggingOptions: mockOptions);
@@ -980,7 +1005,9 @@ flutter:
 
       final IOSSimulator simulator = IOSSimulator(
         'test',
+        name: 'iPhone 11',
         simControl: simControl,
+        simulatorCategory: 'com.apple.CoreSimulator.SimRuntime.iOS-11-3',
       );
       expect(simulator.isSupportedForProject(flutterProject), true);
     }, overrides: <Type, Generator>{
@@ -998,7 +1025,9 @@ flutter:
 
       final IOSSimulator simulator = IOSSimulator(
         'test',
+        name: 'iPhone 11',
         simControl: simControl,
+        simulatorCategory: 'com.apple.CoreSimulator.SimRuntime.iOS-11-3',
       );
       expect(simulator.isSupportedForProject(flutterProject), true);
     }, overrides: <Type, Generator>{
@@ -1014,7 +1043,9 @@ flutter:
 
       final IOSSimulator simulator = IOSSimulator(
         'test',
+        name: 'iPhone 11',
         simControl: simControl,
+        simulatorCategory: 'com.apple.CoreSimulator.SimRuntime.iOS-11-3',
       );
       expect(simulator.isSupportedForProject(flutterProject), false);
     }, overrides: <Type, Generator>{
@@ -1026,7 +1057,9 @@ flutter:
     testUsingContext('createDevFSWriter returns a LocalDevFSWriter', () {
       final IOSSimulator simulator = IOSSimulator(
         'test',
+        name: 'iPhone 11',
         simControl: simControl,
+        simulatorCategory: 'com.apple.CoreSimulator.SimRuntime.iOS-11-3',
       );
 
       expect(simulator.createDevFSWriter(null, ''), isA<LocalDevFSWriter>());

packages/flutter_tools/test/general.shard/mdns_discovery_test.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.8
-
 import 'package:flutter_tools/src/base/io.dart';
 import 'package:flutter_tools/src/base/logger.dart';
 import 'package:flutter_tools/src/build_info.dart';
@@ -24,9 +22,9 @@ void main() {
     setUp(() {
       setNetworkInterfaceLister(
         ({
-          bool includeLoopback,
-          bool includeLinkLocal,
-          InternetAddressType type,
+          bool? includeLoopback,
+          bool? includeLinkLocal,
+          InternetAddressType? type,
         }) async => <NetworkInterface>[],
       );
     });
@@ -44,7 +42,7 @@ void main() {
         logger: BufferLogger.test(),
         flutterUsage: TestUsage(),
       );
-      final int port = (await portDiscovery.query())?.port;
+      final int? port = (await portDiscovery.query())?.port;
       expect(port, isNull);
     });
 
@@ -56,7 +54,7 @@ void main() {
         logger: logger,
         flutterUsage: TestUsage(),
       );
-      final Uri uri = await portDiscovery.getObservatoryUri(
+      final Uri? uri = await portDiscovery.getObservatoryUri(
         '',
         FakeIOSDevice(),
       );
@@ -81,7 +79,7 @@ void main() {
         logger: BufferLogger.test(),
         flutterUsage: TestUsage(),
       );
-      final int port = (await portDiscovery.query())?.port;
+      final int? port = (await portDiscovery.query())?.port;
       expect(port, 123);
     });
 
@@ -107,7 +105,7 @@ void main() {
         logger: BufferLogger.test(),
         flutterUsage: TestUsage(),
       );
-      final MDnsObservatoryDiscoveryResult result = await portDiscovery.query();
+      final MDnsObservatoryDiscoveryResult? result = await portDiscovery.query();
       expect(result?.port, 123);
       expect(result?.authCode, 'xyz/');
     });
@@ -157,7 +155,7 @@ void main() {
         logger: BufferLogger.test(),
         flutterUsage: TestUsage(),
       );
-      final int port = (await portDiscovery.query(applicationId: 'fiz'))?.port;
+      final int? port = (await portDiscovery.query(applicationId: 'fiz'))?.port;
       expect(port, 321);
     });
 
@@ -184,7 +182,7 @@ void main() {
         logger: BufferLogger.test(),
         flutterUsage: TestUsage(),
       );
-      final int port = (await portDiscovery.query(applicationId: 'bar'))?.port;
+      final int? port = (await portDiscovery.query(applicationId: 'bar'))?.port;
       expect(port, 1234);
     });
 
@@ -199,7 +197,7 @@ void main() {
         logger: BufferLogger.test(),
         flutterUsage: TestUsage(),
       );
-      final int port = (await portDiscovery.query(applicationId: 'bar'))?.port;
+      final int? port = (await portDiscovery.query(applicationId: 'bar'))?.port;
       expect(port, isNull);
     });
 
@@ -236,7 +234,7 @@ void main() {
         logger: BufferLogger.test(),
         flutterUsage: TestUsage(),
       );
-      final Uri uri = await portDiscovery.getObservatoryUri('bar', device, hostVmservicePort: 0);
+      final Uri? uri = await portDiscovery.getObservatoryUri('bar', device, hostVmservicePort: 0);
       expect(uri.toString(), 'http://127.0.0.1:123/');
     });
   });
@@ -255,10 +253,10 @@ class FakeMDnsClient extends Fake implements MDnsClient {
 
   @override
   Future<void> start({
-    InternetAddress listenAddress,
-    NetworkInterfacesFactory interfacesFactory,
+    InternetAddress? listenAddress,
+    NetworkInterfacesFactory? interfacesFactory,
     int mDnsPort = 5353,
-    InternetAddress mDnsAddress,
+    InternetAddress? mDnsAddress,
   }) async {
     if (osErrorOnStart) {
       throw const OSError('Operation not supported on socket', 102);