Reland "Null safety migration of packages/flutter_tools/bin" (#111756)

This reverts commit f8f69575.

packages/flutter_tools/bin/flutter_tools.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/executable.dart' as executable;
 
 void main(List<String> args) {

packages/flutter_tools/bin/fuchsia_asset_builder.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:args/args.dart';
 import 'package:flutter_tools/src/asset.dart' hide defaultManifestPath;
 import 'package:flutter_tools/src/base/common.dart';
@@ -63,10 +61,10 @@ Future<void> run(List<String> args) async {
   Cache.flutterRoot = globals.platform.environment['FLUTTER_ROOT'];
 
   final String assetDir = argResults[_kOptionAsset] as String;
-  final AssetBundle assets = await buildAssets(
-    manifestPath: argResults[_kOptionManifest] as String ?? defaultManifestPath,
+  final AssetBundle? assets = await buildAssets(
+    manifestPath: argResults[_kOptionManifest] as String? ?? defaultManifestPath,
     assetDirPath: assetDir,
-    packagesPath: argResults[_kOptionPackages] as String,
+    packagesPath: argResults[_kOptionPackages] as String?,
     targetPlatform: TargetPlatform.fuchsia_arm64 // This is not arch specific.
   );
 
@@ -84,8 +82,9 @@ Future<void> run(List<String> args) async {
   final String outputMan = argResults[_kOptionAssetManifestOut] as String;
   await writeFuchsiaManifest(assets, argResults[_kOptionAsset] as String, outputMan, argResults[_kOptionComponentName] as String);
 
-  if (argResults.options.contains(_kOptionDepfile)) {
-    await writeDepfile(assets, outputMan, argResults[_kOptionDepfile] as String);
+  final String? depfilePath = argResults[_kOptionDepfile] as String?;
+  if (depfilePath != null) {
+    await writeDepfile(assets, outputMan, depfilePath);
   }
 }
 

packages/flutter_tools/bin/fuchsia_tester.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:convert' show json;
 import 'dart:math' as math;
 
@@ -57,7 +55,6 @@ Future<void> run(List<String> args) async {
     ..addOption(_kOptionTests, help: 'Path to json file that maps Dart test files to precompiled dill files')
     ..addOption(_kOptionCoverageDirectory, help: 'The path to the directory that will have coverage collected')
     ..addFlag(_kOptionCoverage,
-      defaultsTo: false,
       negatable: false,
       help: 'Whether to collect coverage information.',
     )
@@ -84,7 +81,7 @@ Future<void> run(List<String> args) async {
     if (!globals.fs.isDirectorySync(sdkRootSrc.path)) {
       throwToolExit('Cannot find SDK files at ${sdkRootSrc.path}');
     }
-    Directory coverageDirectory;
+    Directory? coverageDirectory;
     final String coverageDirectoryPath = argResults[_kOptionCoverageDirectory] as String;
     if (coverageDirectoryPath != null) {
       if (!globals.fs.isDirectorySync(coverageDirectoryPath)) {
@@ -95,13 +92,14 @@ Future<void> run(List<String> args) async {
 
     // Put the tester shell where runTests expects it.
     // TODO(garymm): Switch to a Fuchsia-specific Artifacts impl.
+    final Artifacts artifacts = globals.artifacts!;
     final Link testerDestLink =
-        globals.fs.link(globals.artifacts.getArtifactPath(Artifact.flutterTester));
+        globals.fs.link(artifacts.getArtifactPath(Artifact.flutterTester));
     testerDestLink.parent.createSync(recursive: true);
     testerDestLink.createSync(globals.fs.path.absolute(shellPath));
 
     final Directory sdkRootDest =
-        globals.fs.directory(globals.artifacts.getArtifactPath(Artifact.flutterPatchedSdkPath));
+        globals.fs.directory(artifacts.getArtifactPath(Artifact.flutterPatchedSdkPath));
     sdkRootDest.createSync(recursive: true);
     for (final FileSystemEntity artifact in sdkRootSrc.listSync()) {
       globals.fs.link(sdkRootDest.childFile(artifact.basename).path).createSync(artifact.path);
@@ -109,12 +107,12 @@ Future<void> run(List<String> args) async {
     // TODO(tvolkert): Remove once flutter_tester no longer looks for this.
     globals.fs.link(sdkRootDest.childFile('platform.dill').path).createSync('platform_strong.dill');
 
-    Directory testDirectory;
-    CoverageCollector collector;
+    Directory? testDirectory;
+    CoverageCollector? collector;
     if (argResults['coverage'] as bool) {
       // If we have a specified coverage directory then accept all libraries by
       // setting libraryNames to null.
-      final Set<String> libraryNames = coverageDirectory != null ? null :
+      final Set<String>? libraryNames = coverageDirectory != null ? null :
           <String>{FlutterProject.current().manifest.appName};
       final String packagesPath = globals.fs.path.normalize(globals.fs.path.absolute(argResults[_kOptionPackages] as String));
       collector = CoverageCollector(
@@ -162,7 +160,7 @@ Future<void> run(List<String> args) async {
       // package (i.e. contains lib/ and test/ sub-dirs). In some cases,
       // test files may appear to be in the root directory.
       if (coverageDirectory == null) {
-        globals.fs.currentDirectory = testDirectory.parent;
+        globals.fs.currentDirectory = testDirectory!.parent;
       } else {
         globals.fs.currentDirectory = testDirectory;
       }

packages/flutter_tools/lib/src/isolated/resident_web_runner.dart

@@ -521,9 +521,9 @@ class ResidentWebRunner extends ResidentRunner {
   }) async {
     if (_chromiumLauncher != null) {
       final Chromium chrome = await _chromiumLauncher!.connectedInstance;
-      final ChromeTab chromeTab = await (chrome.chromeConnection.getTab((ChromeTab chromeTab) {
+      final ChromeTab? chromeTab = await chrome.chromeConnection.getTab((ChromeTab chromeTab) {
         return !chromeTab.url.startsWith('chrome-extension');
-      }, retryFor: const Duration(seconds: 5)) as FutureOr<ChromeTab>);
+      }, retryFor: const Duration(seconds: 5));
       if (chromeTab == null) {
         throwToolExit('Failed to connect to Chrome instance.');
       }

packages/flutter_tools/lib/src/localizations/gen_l10n_types.dart

@@ -261,14 +261,14 @@ class Placeholder {
     if (value == null) {
       return <OptionalParameter>[];
     }
-    if (value is! Map<String, Object>) {
+    if (value is! Map<String, Object?>) {
       throw L10nException(
         'The "optionalParameters" value of the "$name" placeholder in message '
         '$resourceId is not a properly formatted Map. Ensure that it is a map '
         'with keys that are strings.'
       );
     }
-    final Map<String, Object> optionalParameterMap = value;
+    final Map<String, Object?> optionalParameterMap = value;
     return optionalParameterMap.keys.map<OptionalParameter>((String parameterName) {
       return OptionalParameter(parameterName, optionalParameterMap[parameterName]!);
     }).toList();

packages/flutter_tools/lib/src/test/flutter_tester_device.dart

@@ -348,7 +348,7 @@ StreamChannel<String> _webSocketToStreamChannel(WebSocket webSocket) {
       .pipe(webSocket);
   webSocket
       // We're only communicating with string encoded JSON.
-      .map<String?>((dynamic message) => message as String?)
+      .map<String>((dynamic message) => message as String)
       .pipe(controller.local.sink);
 
   return controller.foreign;

packages/flutter_tools/lib/src/test/flutter_web_platform.dart

@@ -344,7 +344,7 @@ class FlutterWebPlatform extends PlatformPlugin {
 
   Future<shelf.Response> _goldenFileHandler(shelf.Request request) async {
     if (request.url.path.contains('flutter_goldens')) {
-      final Map<String, Object> body = json.decode(await request.readAsString()) as Map<String, Object>;
+      final Map<String, Object?> body = json.decode(await request.readAsString()) as Map<String, Object?>;
       final Uri goldenKey = Uri.parse(body['key']! as String);
       final Uri testUri = Uri.parse(body['testUri']! as String);
       final num width = body['width']! as num;
@@ -352,9 +352,9 @@ class FlutterWebPlatform extends PlatformPlugin {
       Uint8List bytes;
 
       try {
-        final ChromeTab chromeTab = await (_browserManager!._browser.chromeConnection.getTab((ChromeTab tab) {
+        final ChromeTab chromeTab = (await _browserManager!._browser.chromeConnection.getTab((ChromeTab tab) {
           return tab.url.contains(_browserManager!._browser.url!);
-        }) as FutureOr<ChromeTab>);
+        }))!;
         final WipConnection connection = await chromeTab.connect();
         final WipResponse response = await connection.sendCommand('Page.captureScreenshot', <String, Object>{
           // Clip the screenshot to include only the element.

packages/flutter_tools/lib/src/web/web_device.dart

@@ -158,7 +158,7 @@ abstract class ChromiumDevice extends Device {
 
   @override
   Future<bool> stopApp(
-    ApplicationPackage app, {
+    ApplicationPackage? app, {
     String? userIdentifier,
   }) async {
     await _chrome?.close();
@@ -479,7 +479,7 @@ class WebServerDevice extends Device {
 
   @override
   Future<bool> stopApp(
-    ApplicationPackage app, {
+    ApplicationPackage? app, {
     String? userIdentifier,
   }) async {
     return true;