Migrate build_info to null safety (#79469)

packages/flutter_tools/lib/src/build_info.dart

@@ -2,9 +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:package_config/package_config_types.dart';
 
 import 'base/config.dart';
@@ -13,35 +10,40 @@ import 'base/file_system.dart';
 import 'base/logger.dart';
 import 'base/os.dart';
 import 'base/utils.dart';
-import 'build_system/targets/icon_tree_shaker.dart';
 import 'convert.dart';
 import 'globals_null_migrated.dart' as globals;
 
+/// Whether icon font subsetting is enabled by default.
+const bool kIconTreeShakerEnabledDefault = true;
+
 /// Information about a build to be performed or used.
 class BuildInfo {
   const BuildInfo(
     this.mode,
     this.flavor, {
     this.trackWidgetCreation = false,
-    this.extraFrontEndOptions,
-    this.extraGenSnapshotOptions,
+    List<String>? extraFrontEndOptions,
+    List<String>? extraGenSnapshotOptions,
     this.fileSystemRoots,
     this.fileSystemScheme,
     this.buildNumber,
     this.buildName,
     this.splitDebugInfoPath,
     this.dartObfuscation = false,
-    this.dartDefines = const <String>[],
+    List<String>? dartDefines,
     this.bundleSkSLPath,
-    this.dartExperiments = const <String>[],
-    @required this.treeShakeIcons,
+    List<String>? dartExperiments,
+    required this.treeShakeIcons,
     this.performanceMeasurementFile,
     this.packagesPath = '.packages', // TODO(jonahwilliams): make this required and remove the default.
     this.nullSafetyMode = NullSafetyMode.sound,
     this.codeSizeDirectory,
     this.androidGradleDaemon = true,
     this.packageConfig = PackageConfig.empty,
-  });
+  }) : extraFrontEndOptions = extraFrontEndOptions ?? const <String>[],
+       extraGenSnapshotOptions = extraGenSnapshotOptions ?? const <String>[],
+       dartDefines = dartDefines ?? const <String>[],
+       dartExperiments = dartExperiments ?? const <String>[];
 
   final BuildMode mode;
 
@@ -59,7 +61,7 @@ class BuildInfo {
   /// If not null, the Gradle build task will be `assembleFlavorMode` (e.g.
   /// `assemblePaidRelease`), and the Xcode build configuration will be
   /// Mode-Flavor (e.g. Release-Paid).
-  final String flavor;
+  final String? flavor;
 
   /// The path to the .packages file to use for compilation.
   ///
@@ -67,8 +69,8 @@ class BuildInfo {
   /// file. If not provided, defaults to `.packages`.
   final String packagesPath;
 
-  final List<String> fileSystemRoots;
-  final String fileSystemScheme;
+  final List<String>? fileSystemRoots;
+  final String? fileSystemScheme;
 
   /// Whether the build should track widget creation locations.
   final bool trackWidgetCreation;
@@ -84,18 +86,18 @@ class BuildInfo {
   /// It is used to determine whether one build is more recent than another, with higher numbers indicating more recent build.
   /// On Android it is used as versionCode.
   /// On Xcode builds it is used as CFBundleVersion.
-  final String buildNumber;
+  final String? buildNumber;
 
   /// A "x.y.z" string used as the version number shown to users.
   /// For each new version of your app, you will provide a version number to differentiate it from previous versions.
   /// On Android it is used as versionName.
   /// On Xcode builds it is used as CFBundleShortVersionString.
-  final String buildName;
+  final String? buildName;
 
   /// An optional directory path to save debugging information from dwarf stack
   /// traces. If null, stack trace information is not stripped from the
   /// executable.
-  final String splitDebugInfoPath;
+  final String? splitDebugInfoPath;
 
   /// Whether to apply dart source code obfuscation.
   final bool dartObfuscation;
@@ -103,7 +105,7 @@ class BuildInfo {
   /// An optional path to a JSON containing object SkSL shaders.
   ///
   /// Currently this is only supported for Android builds.
-  final String bundleSkSLPath;
+  final String? bundleSkSLPath;
 
   /// Additional constant values to be made available in the Dart program.
   ///
@@ -119,11 +121,11 @@ class BuildInfo {
   ///
   /// This is not considered a build input and will not force assemble to
   /// rerun tasks.
-  final String performanceMeasurementFile;
+  final String? performanceMeasurementFile;
 
   /// If provided, an output directory where one or more v8-style heap snapshots
   /// will be written for code size profiling.
-  final String codeSizeDirectory;
+  final String? codeSizeDirectory;
 
   /// Whether to enable the Gradle daemon when performing an Android build.
   ///
@@ -181,7 +183,7 @@ class BuildInfo {
 
   /// the flavor name in the output files is lower-cased (see flutter.gradle),
   /// so the lower cased flavor name is used to compute the output file name
-  String get lowerCasedFlavor => flavor?.toLowerCase();
+  String? get lowerCasedFlavor => flavor?.toLowerCase();
 
   /// Convert to a structured string encoded structure appropriate for usage as
   /// environment variables or to embed in other scripts.
@@ -189,28 +191,28 @@ class BuildInfo {
   /// Fields that are `null` are excluded from this configuration.
   Map<String, String> toEnvironmentConfig() {
     return <String, String>{
-      if (dartDefines?.isNotEmpty ?? false)
+      if (dartDefines.isNotEmpty)
         'DART_DEFINES': encodeDartDefines(dartDefines),
       if (dartObfuscation != null)
         'DART_OBFUSCATION': dartObfuscation.toString(),
-      if (extraFrontEndOptions?.isNotEmpty ?? false)
-        'EXTRA_FRONT_END_OPTIONS': extraFrontEndOptions?.join(','),
-      if (extraGenSnapshotOptions?.isNotEmpty ?? false)
-        'EXTRA_GEN_SNAPSHOT_OPTIONS': extraGenSnapshotOptions?.join(','),
+      if (extraFrontEndOptions.isNotEmpty)
+        'EXTRA_FRONT_END_OPTIONS': extraFrontEndOptions.join(','),
+      if (extraGenSnapshotOptions.isNotEmpty)
+        'EXTRA_GEN_SNAPSHOT_OPTIONS': extraGenSnapshotOptions.join(','),
       if (splitDebugInfoPath != null)
-        'SPLIT_DEBUG_INFO': splitDebugInfoPath,
+        'SPLIT_DEBUG_INFO': splitDebugInfoPath!,
       if (trackWidgetCreation != null)
         'TRACK_WIDGET_CREATION': trackWidgetCreation.toString(),
       if (treeShakeIcons != null)
         'TREE_SHAKE_ICONS': treeShakeIcons.toString(),
       if (performanceMeasurementFile != null)
-        'PERFORMANCE_MEASUREMENT_FILE': performanceMeasurementFile,
+        'PERFORMANCE_MEASUREMENT_FILE': performanceMeasurementFile!,
       if (bundleSkSLPath != null)
-        'BUNDLE_SKSL_PATH': bundleSkSLPath,
+        'BUNDLE_SKSL_PATH': bundleSkSLPath!,
       if (packagesPath != null)
         'PACKAGE_CONFIG': packagesPath,
       if (codeSizeDirectory != null)
-        'CODE_SIZE_DIRECTORY': codeSizeDirectory,
+        'CODE_SIZE_DIRECTORY': codeSizeDirectory!,
     };
   }
 
@@ -219,14 +221,14 @@ class BuildInfo {
   List<String> toGradleConfig() {
     // PACKAGE_CONFIG not currently supported.
     return <String>[
-      if (dartDefines?.isNotEmpty ?? false)
+      if (dartDefines.isNotEmpty)
         '-Pdart-defines=${encodeDartDefines(dartDefines)}',
       if (dartObfuscation != null)
         '-Pdart-obfuscation=$dartObfuscation',
-      if (extraFrontEndOptions?.isNotEmpty ?? false)
-        '-Pextra-front-end-options=${extraFrontEndOptions?.join(',')}',
-      if (extraGenSnapshotOptions?.isNotEmpty ?? false)
-        '-Pextra-gen-snapshot-options=${extraGenSnapshotOptions?.join(',')}',
+      if (extraFrontEndOptions.isNotEmpty)
+        '-Pextra-front-end-options=${extraFrontEndOptions.join(',')}',
+      if (extraGenSnapshotOptions.isNotEmpty)
+        '-Pextra-gen-snapshot-options=${extraGenSnapshotOptions.join(',')}',
       if (splitDebugInfoPath != null)
         '-Psplit-debug-info=$splitDebugInfoPath',
       if (trackWidgetCreation != null)
@@ -353,7 +355,7 @@ enum EnvironmentType {
   simulator,
 }
 
-String validatedBuildNumberForPlatform(TargetPlatform targetPlatform, String buildNumber, Logger logger) {
+String? validatedBuildNumberForPlatform(TargetPlatform targetPlatform, String buildNumber, Logger logger) {
   if (buildNumber == null) {
     return null;
   }
@@ -400,7 +402,7 @@ String validatedBuildNumberForPlatform(TargetPlatform targetPlatform, String bui
   return buildNumber;
 }
 
-String validatedBuildNameForPlatform(TargetPlatform targetPlatform, String buildName, Logger logger) {
+String? validatedBuildNameForPlatform(TargetPlatform targetPlatform, String buildName, Logger logger) {
   if (buildName == null) {
     return null;
   }
@@ -517,8 +519,6 @@ String getNameForDarwinArch(DarwinArch arch) {
     case DarwinArch.x86_64:
       return 'x86_64';
   }
-  assert(false);
-  return null;
 }
 
 DarwinArch getIOSArchForName(String arch) {
@@ -536,7 +536,7 @@ DarwinArch getIOSArchForName(String arch) {
   throw Exception('Unsupported iOS arch name "$arch"');
 }
 
-String getNameForTargetPlatform(TargetPlatform platform, {DarwinArch darwinArch}) {
+String getNameForTargetPlatform(TargetPlatform platform, {DarwinArch? darwinArch}) {
   switch (platform) {
     case TargetPlatform.android_arm:
       return 'android-arm';
@@ -572,11 +572,9 @@ String getNameForTargetPlatform(TargetPlatform platform, {DarwinArch darwinArch}
     case TargetPlatform.android:
       return 'android';
   }
-  assert(false);
-  return null;
 }
 
-TargetPlatform getTargetPlatformForName(String platform) {
+TargetPlatform? getTargetPlatformForName(String platform) {
   switch (platform) {
     case 'android':
       return TargetPlatform.android;
@@ -634,8 +632,6 @@ String getNameForAndroidArch(AndroidArch arch) {
     case AndroidArch.x86:
       return 'x86';
   }
-  assert(false);
-  return null;
 }
 
 String getPlatformNameForAndroidArch(AndroidArch arch) {
@@ -649,8 +645,6 @@ String getPlatformNameForAndroidArch(AndroidArch arch) {
     case AndroidArch.x86:
       return 'android-x86';
   }
-  assert(false);
-  return null;
 }
 
 String fuchsiaArchForTargetPlatform(TargetPlatform targetPlatform) {
@@ -660,8 +654,7 @@ String fuchsiaArchForTargetPlatform(TargetPlatform targetPlatform) {
     case TargetPlatform.fuchsia_x64:
       return 'x64';
     default:
-      assert(false);
-      return null;
+      throw UnsupportedError('Unexpected Fuchsia platform $targetPlatform');
   }
 }
 
@@ -683,7 +676,7 @@ HostPlatform getCurrentHostPlatform() {
 }
 
 /// Returns the top-level build output directory.
-String getBuildDirectory([Config config, FileSystem fileSystem]) {
+String getBuildDirectory([Config? config, FileSystem? fileSystem]) {
   // TODO(johnmccutchan): Stop calling this function as part of setting
   // up command line argument processing.
   if (context == null) {
@@ -695,7 +688,7 @@ String getBuildDirectory([Config config, FileSystem fileSystem]) {
     return 'build';
   }
 
-  final String buildDir = localConfig.getValue('build-dir') as String ?? 'build';
+  final String buildDir = localConfig.getValue('build-dir') as String? ?? 'build';
   if (localFilesystem.path.isAbsolute(buildDir)) {
     throw Exception(
         'build-dir config setting in ${globals.config.configPath} must be relative');
@@ -735,7 +728,7 @@ String getWebBuildDirectory() {
 }
 
 /// Returns the Linux build output directory.
-String getLinuxBuildDirectory([TargetPlatform targetPlatform]) {
+String getLinuxBuildDirectory([TargetPlatform? targetPlatform]) {
   final String arch = (targetPlatform == null) ?
       _getCurrentHostPlatformArchName() :
       getNameForTargetPlatformArch(targetPlatform);
@@ -777,10 +770,10 @@ String encodeDartDefines(List<String> defines) {
 }
 
 List<String> decodeCommaSeparated(Map<String, String> environmentDefines, String key) {
-  if (!environmentDefines.containsKey(key) || environmentDefines[key].isEmpty) {
+  if (!environmentDefines.containsKey(key) || environmentDefines[key]!.isEmpty) {
     return <String>[];
   }
-  return environmentDefines[key]
+  return environmentDefines[key]!
     .split(',')
     .cast<String>()
     .toList();
@@ -788,10 +781,10 @@ List<String> decodeCommaSeparated(Map<String, String> environmentDefines, String
 
 /// Dart defines are encoded inside [environmentDefines] as a comma-separated list.
 List<String> decodeDartDefines(Map<String, String> environmentDefines, String key) {
-  if (!environmentDefines.containsKey(key) || environmentDefines[key].isEmpty) {
+  if (!environmentDefines.containsKey(key) || environmentDefines[key]!.isEmpty) {
     return <String>[];
   }
-  return environmentDefines[key]
+  return environmentDefines[key]!
     .split(',')
     .map<Object>(_defineDecoder.convert)
     .cast<String>()
@@ -820,10 +813,8 @@ String getNameForTargetPlatformArch(TargetPlatform platform) {
     case TargetPlatform.linux_arm64:
       return 'arm64';
     default:
-      break;
+      throw UnsupportedError('Unexpected target platform $platform');
   }
-  assert(false);
-  return null;
 }
 
 String getNameForHostPlatformArch(HostPlatform platform) {
@@ -839,6 +830,4 @@ String getNameForHostPlatformArch(HostPlatform platform) {
     case HostPlatform.windows_x64:
       return 'x64';
   }
-  assert(false);
-  return null;
 }

packages/flutter_tools/lib/src/build_system/targets/icon_tree_shaker.dart

@@ -22,9 +22,6 @@ import 'common.dart';
 /// only the glyphs used by the application.
 const String kIconTreeShakerFlag = 'TreeShakeIcons';
 
-/// Whether icon font subsetting is enabled by default.
-const bool kIconTreeShakerEnabledDefault = true;
-
 List<Map<String, dynamic>> _getList(dynamic object, String errorMessage) {
   if (object is List<dynamic>) {
     return object.cast<Map<String, dynamic>>();

packages/flutter_tools/lib/src/runner/flutter_command.dart

@@ -19,7 +19,6 @@ import '../base/utils.dart';
 import '../build_info.dart';
 import '../build_system/build_system.dart';
 import '../build_system/targets/common.dart' show kExtraFrontEndOptions, kExtraGenSnapshotOptions; // for "useLegacyNames" only
-import '../build_system/targets/icon_tree_shaker.dart' show kIconTreeShakerEnabledDefault;
 import '../bundle.dart' as bundle;
 import '../cache.dart';
 import '../dart/generate_synthetic_packages.dart';