Enable null safety by default in templates (#78619)

dev/integration_tests/ios_host_app/flutterapp/lib/main

@@ -38,13 +38,14 @@ void main() {
   run(ui.window.defaultRouteName);
 }
 
-Future<String> run(String name) async {
+Future<String> run(String? name) async {
   // The platform-specific component will call [setInitialRoute] on the Flutter
   // view (or view controller for iOS) to set [ui.window.defaultRouteName].
   // We then dispatch based on the route names to show different Flutter
   // widgets.
   // Since we don't really care about Flutter-side navigation in this app, we're
   // not using a regular routes map.
+  name ??= '';
   switch (name) {
     case greenMarqueeRouteName:
       runApp(Marquee(color: Colors.green[400]));
@@ -62,7 +63,7 @@ Future<String> run(String name) async {
 }
 
 class FlutterView extends StatelessWidget {
-  const FlutterView({@required this.initialRoute});
+  const FlutterView({required this.initialRoute});
 
   @override
   Widget build(BuildContext context) {
@@ -76,7 +77,7 @@ class FlutterView extends StatelessWidget {
 }
 
 class MyHomePage extends StatefulWidget {
-  const MyHomePage({this.initialRoute});
+  const MyHomePage({required this.initialRoute});
 
   @override
   _MyHomePageState createState() => _MyHomePageState();
@@ -131,7 +132,7 @@ class _MyHomePageState extends State<MyHomePage> {
   /// Callback for messages sent by the platform-specific component.
   ///
   /// Increments our internal counter.
-  Future<String> _handlePlatformIncrement(String message) async {
+  Future<String> _handlePlatformIncrement(String? message) async {
     // Normally we'd dispatch based on the value of [message], but in this
     // sample, there is only one message that is sent to us.
     _incrementCounter();

dev/integration_tests/ios_host_app/flutterapp/lib/marquee

@@ -7,7 +7,7 @@ import 'package:flutter/animation.dart';
 import 'package:flutter/services.dart';
 
 class _MarqueeText extends AnimatedWidget {
-  const _MarqueeText({Key key, Animation<double> animation})
+  const _MarqueeText({Key? key, required Animation<double> animation})
       : super(key: key, listenable: animation);
 
   @override
@@ -26,15 +26,15 @@ class _MarqueeText extends AnimatedWidget {
 class Marquee extends StatefulWidget {
   const Marquee({this.color});
 
-  final Color color;
+  final Color? color;
 
   @override
   State<StatefulWidget> createState() => MarqueeState();
 }
 
 class MarqueeState extends State<Marquee> with SingleTickerProviderStateMixin {
-  AnimationController controller;
-  Animation<double> animation;
+  late AnimationController controller;
+  late Animation<double> animation;
 
   @override
   void initState() {

packages/flutter_tools/lib/src/commands/create.dart

@@ -242,8 +242,8 @@ class CreateCommand extends CreateBase {
       macos: featureFlags.isMacOSEnabled && platforms.contains('macos'),
       windows: featureFlags.isWindowsEnabled && platforms.contains('windows'),
       windowsUwp: featureFlags.isWindowsUwpEnabled && platforms.contains('winuwp'),
-      // Enable null-safety for sample code, which is - unlike our regular templates - already migrated.
-      dartSdkVersionBounds: sampleCode != null ? '">=2.12.0-0 <3.0.0"' : '">=2.7.0 <3.0.0"'
+      // Enable null safety everywhere.
+      dartSdkVersionBounds: '">=2.12.0 <3.0.0"'
     );
 
     final String relativeDirPath = globals.fs.path.relative(projectDirPath);
@@ -325,11 +325,6 @@ In order to run your $application, type:
   \$ cd $relativeAppPath
   \$ flutter run
 
-To enable null safety, type:
-
-  \$ cd $relativeAppPath
-  \$ dart migrate --apply-changes
-
 Your $application code is in $relativeAppMain.
 ''');
       // Show warning if any selected platform is not enabled

packages/flutter_tools/templates/app/lib/main.dart.tmpl

@@ -35,7 +35,7 @@ class MyApp extends StatelessWidget {
 }
 
 class MyHomePage extends StatefulWidget {
-  MyHomePage({Key key, this.title}) : super(key: key);
+  MyHomePage({Key? key, required this.title}) : super(key: key);
 
   // This widget is the home page of your application. It is stateful, meaning
   // that it has a State object (defined below) that contains fields that affect
@@ -138,8 +138,10 @@ class _MyAppState extends State<MyApp> {
   Future<void> initPlatformState() async {
     String platformVersion;
     // Platform messages may fail, so we use a try/catch PlatformException.
+    // We also handle the message potentially returning null.
     try {
-      platformVersion = await {{pluginDartClass}}.platformVersion;
+      platformVersion =
+          await {{pluginDartClass}}.platformVersion ?? 'Unknown platform version';
     } on PlatformException {
       platformVersion = 'Failed to get platform version.';
     }

packages/flutter_tools/templates/app/test/widget_test.dart.tmpl

@@ -40,7 +40,7 @@ void main() {
     expect(
       find.byWidgetPredicate(
         (Widget widget) => widget is Text &&
-                           widget.data.startsWith('Running on:'),
+                           widget.data!.startsWith('Running on:'),
       ),
       findsOneWidget,
     );

packages/flutter_tools/templates/module/common/lib/main.dart.tmpl

@@ -32,7 +32,7 @@ class MyApp extends StatelessWidget {
 }
 
 class MyHomePage extends StatefulWidget {
-  MyHomePage({Key key, this.title}) : super(key: key);
+  MyHomePage({Key? key, required this.title}) : super(key: key);
 
   // This widget is the home page of your application. It is stateful, meaning
   // that it has a State object (defined below) that contains fields that affect
@@ -135,8 +135,10 @@ class _MyAppState extends State<MyApp> {
   Future<void> initPlatformState() async {
     String platformVersion;
     // Platform messages may fail, so we use a try/catch PlatformException.
+    // We also handle the message potentially returning null.
     try {
-      platformVersion = await {{pluginDartClass}}.platformVersion;
+      platformVersion =
+          await {{pluginDartClass}}.platformVersion ?? 'Unknown platform version';
     } on PlatformException {
       platformVersion = 'Failed to get platform version.';
     }

packages/flutter_tools/templates/module/common/test/widget_test.dart.tmpl

@@ -40,7 +40,7 @@ void main() {
     expect(
       find.byWidgetPredicate(
         (Widget widget) => widget is Text &&
-                           widget.data.startsWith('Running on:'),
+                           widget.data!.startsWith('Running on:'),
       ),
       findsOneWidget,
     );

packages/flutter_tools/templates/plugin/lib/projectName.dart.tmpl

@@ -13,8 +13,8 @@ class {{pluginDartClass}} {
   static const MethodChannel _channel =
       const MethodChannel('{{projectName}}');
 
-  static Future<String> get platformVersion async {
-    final String version = await _channel.invokeMethod('getPlatformVersion');
+  static Future<String?> get platformVersion async {
+    final String? version = await _channel.invokeMethod('getPlatformVersion');
     return version;
   }
 }

packages/flutter_tools/templates/plugin/lib/projectName_web.dart.tmpl

@@ -28,7 +28,6 @@ class {{pluginDartClass}}Web {
     switch (call.method) {
       case 'getPlatformVersion':
         return getPlatformVersion();
-        break;
       default:
         throw PlatformException(
           code: 'Unimplemented',

packages/flutter_tools/templates/plugin/pubspec.yaml.tmpl

@@ -4,7 +4,7 @@ version: 0.0.1
 homepage:
 
 environment:
-  sdk: ">=2.7.0 <3.0.0"
+  sdk: {{dartSdkVersionBounds}}
   flutter: ">=1.20.0"
 
 dependencies:

packages/flutter_tools/test/commands.shard/permeable/create_test.dart

@@ -2450,25 +2450,6 @@ void main() {
     FeatureFlags: () => TestFeatureFlags(isWindowsEnabled: true, isAndroidEnabled: false, isIOSEnabled: false),
     Logger: () => logger,
   });
-
-  testUsingContext('flutter create prints note about null safety', () async {
-    await _createProject(
-      projectDir,
-      <String>[],
-      <String>[],
-    );
-    expect(logger.statusText, contains('dart migrate --apply-changes'));
-  }, overrides: <Type, Generator>{
-    Pub: () => Pub(
-      fileSystem: globals.fs,
-      logger: globals.logger,
-      processManager: globals.processManager,
-      usage: globals.flutterUsage,
-      botDetector: globals.botDetector,
-      platform: globals.platform,
-    ),
-    Logger: () => logger,
-  });
 }
 
 Future<void> _createProject(

packages/flutter_tools/test/integration.shard/generated_plugin_registrant_test.dart

@@ -47,7 +47,7 @@ void main() {
     // We need to add a dependency with web support to trigger
     // the generated_plugin_registrant generation.
     await _addDependency(projectDir, 'shared_preferences',
-        version: '^0.5.12+4');
+        version: '^2.0.0');
     await _analyzeProject(projectDir);
 
     expect(

packages/flutter_tools/test/integration.shard/migrate_test.dart

-// Copyright 2014 The Flutter Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-// @dart = 2.8
-
-import 'package:flutter_tools/src/base/file_system.dart';
-import 'package:flutter_tools/src/base/io.dart';
-
-import '../src/common.dart';
-import 'test_utils.dart';
-
-void main() {
-  /// Verifies that `dart migrate` will run successfully on the default `flutter create`
-  /// template.
-  group('dart migrate', () {
-    testWithoutContext('dart migrate succeeds on flutter create template', () async {
-      Directory tempDir;
-      try {
-        tempDir = await _createProject(tempDir);
-        await _migrate(tempDir);
-        await _analyze(tempDir);
-      } finally {
-        tempDir?.deleteSync(recursive: true);
-      }
-    });
-
-    /// Verifies that `dart migrate` will run successfully on the module template
-    /// used by `flutter create --template=module`.
-    testWithoutContext('dart migrate succeeds on module template', () async {
-      Directory tempDir;
-      try {
-        tempDir = await _createProject(tempDir, <String>['--template=module']);
-        await _migrate(tempDir);
-        await _analyze(tempDir);
-      } finally {
-        tempDir?.deleteSync(recursive: true);
-      }
-    });
-
-    /// Verifies that `dart migrate` will run successfully on the module template
-    /// used by `flutter create --template=plugin`.
-    testWithoutContext('dart migrate succeeds on plugin template', () async {
-      Directory tempDir;
-      try {
-        tempDir = await _createProject(tempDir, <String>['--template=plugin']);
-        await _migrate(tempDir);
-        await _analyze(tempDir);
-      } finally {
-        tempDir?.deleteSync(recursive: true);
-      }
-    });
-
-    /// Verifies that `dart migrate` will run successfully on the module template
-    /// used by `flutter create --template=package`.
-    testWithoutContext('dart migrate succeeds on package template', () async {
-      Directory tempDir;
-      try {
-        tempDir = await _createProject(tempDir, <String>['--template=package']);
-        await _migrate(tempDir);
-        await _analyze(tempDir);
-      } finally {
-        tempDir?.deleteSync(recursive: true);
-      }
-    });
-  }, timeout: const Timeout(Duration(seconds: 90)));
-}
-
-Future<Directory> _createProject(Directory tempDir, [List<String> extraAgs]) async {
-  tempDir = createResolvedTempDirectorySync('dart_migrate_test.');
-  final ProcessResult createResult = await processManager.run(<String>[
-    _flutterBin,
-    'create',
-    if (extraAgs != null)
-      ...extraAgs,
-    'foo',
-  ], workingDirectory: tempDir.path);
-  if (createResult.exitCode != 0) {
-    fail('flutter create did not work: ${createResult.stdout}${createResult.stderr}');
-  }
-  return tempDir;
-}
-
-Future<void> _migrate(Directory tempDir) async {
-  final ProcessResult migrateResult = await processManager.run(<String>[
-    _dartBin,
-    'migrate',
-    '--apply-changes',
-  ], workingDirectory: fileSystem.path.join(tempDir.path, 'foo'));
-  if (migrateResult.exitCode != 0) {
-    fail('dart migrate did not work: ${migrateResult.stdout}${migrateResult.stderr}');
-  }
-}
-
-Future<void> _analyze(Directory tempDir) async {
-  final ProcessResult analyzeResult = await processManager.run(<String>[
-    _flutterBin,
-    'analyze',
-  ], workingDirectory: fileSystem.path.join(tempDir.path, 'foo'));
-  if (analyzeResult.exitCode != 0) {
-    fail('flutter analyze had errors: ${analyzeResult.stdout}${analyzeResult.stderr}');
-  }
-}
-
-String get _flutterBin => fileSystem.path.join(getFlutterRoot(), 'bin', platform.isWindows ? 'flutter.bat' : 'flutter');
-String get _dartBin => fileSystem.path.join(getFlutterRoot(), 'bin', platform.isWindows ? 'dart.bat' : 'dart');