Expose extra frontend options through build apk/ios/macOS (#53273)

This will allow experimenting with the remove to string transformer before we're ready to turn it on by default. This doesn't work for web yet since we use dart2js instead of the frontend_server for producing kernel

packages/flutter_tools/bin/macos_assemble.sh

@@ -84,6 +84,7 @@ RunCommand "${FLUTTER_ROOT}/bin/flutter" --suppress-analytics               \
     -dDartObfuscation="${dart_obfuscation_flag}"                            \
     -dSplitDebugInfo="${SPLIT_DEBUG_INFO}"                                  \
     -dDartDefines="${DART_DEFINES}"                                         \
+    -dExtraFrontEndOptions="${EXTRA_FRONT_END_OPTIONS}"                     \
     --build-inputs="${build_inputs_path}"                                   \
     --build-outputs="${build_outputs_path}"                                 \
     --output="${ephemeral_dir}"                                             \

packages/flutter_tools/bin/xcode_backend.sh

@@ -187,6 +187,7 @@ BuildApp() {
     -dDartObfuscation="${dart_obfuscation_flag}"                          \
     -dEnableBitcode="${bitcode_flag}"                                     \
     -dDartDefines="${DART_DEFINES}"                                       \
+    -dExtraFrontEndOptions="${EXTRA_FRONT_END_OPTIONS}"                   \
     "${build_mode}_ios_bundle_flutter_assets"
 
   if [[ $? -ne 0 ]]; then

packages/flutter_tools/lib/src/android/gradle.dart

@@ -313,7 +313,7 @@ Future<void> buildGradleApp({
   command.add('-Ptrack-widget-creation=${buildInfo.trackWidgetCreation}');
 
   if (buildInfo.extraFrontEndOptions != null) {
-    command.add('-Pextra-front-end-options=${buildInfo.extraFrontEndOptions}');
+    command.add('-Pextra-front-end-options=${buildInfo.extraFrontEndOptions.join(',')}');
   }
   if (buildInfo.extraGenSnapshotOptions != null) {
     command.add('-Pextra-gen-snapshot-options=${buildInfo.extraGenSnapshotOptions}');

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

@@ -204,7 +204,10 @@ class KernelSnapshot extends Target {
     final TargetPlatform targetPlatform = getTargetPlatformForName(environment.defines[kTargetPlatform]);
 
     // This configuration is all optional.
-    final List<String> extraFrontEndOptions = environment.defines[kExtraFrontEndOptions]?.split(',');
+    final String rawFrontEndOption = environment.defines[kExtraFrontEndOptions];
+    final List<String> extraFrontEndOptions = (rawFrontEndOption?.isNotEmpty ?? false)
+      ? rawFrontEndOption?.split(',')
+      : null;
     final List<String> fileSystemRoots = environment.defines[kFileSystemRoots]?.split(',');
     final String fileSystemScheme = environment.defines[kFileSystemScheme];
 

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

@@ -20,6 +20,7 @@ class BuildAotCommand extends BuildSubCommand with TargetPlatformBasedDevelopmen
     addBuildModeFlags();
     usesPubOption();
     usesDartDefineOption();
+    usesExtraFrontendOptions();
     argParser
       ..addOption('output-dir', defaultsTo: getAotBuildDirectory())
       ..addOption('target-platform',
@@ -33,10 +34,6 @@ class BuildAotCommand extends BuildSubCommand with TargetPlatformBasedDevelopmen
         allowed: DarwinArch.values.map<String>(getNameForDarwinArch),
         help: 'iOS architectures to build.',
       )
-      ..addMultiOption(FlutterOptions.kExtraFrontEndOptions,
-        splitCommas: true,
-        hide: true,
-      )
       ..addMultiOption(FlutterOptions.kExtraGenSnapshotOptions,
         splitCommas: true,
         hide: true,

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

@@ -29,6 +29,7 @@ class BuildApkCommand extends BuildSubCommand {
     addSplitDebugInfoOption();
     addDartObfuscationOption();
     usesDartDefineOption();
+    usesExtraFrontendOptions();
     argParser
       ..addFlag('split-per-abi',
         negatable: false,

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

@@ -27,6 +27,7 @@ class BuildAppBundleCommand extends BuildSubCommand {
     addSplitDebugInfoOption();
     addDartObfuscationOption();
     usesDartDefineOption();
+    usesExtraFrontendOptions();
     argParser
       ..addFlag('track-widget-creation', negatable: false, hide: !verboseHelp)
       ..addMultiOption('target-platform',

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

@@ -21,6 +21,7 @@ class BuildBundleCommand extends BuildSubCommand {
     usesFilesystemOptions(hide: !verboseHelp);
     usesBuildNumberOption();
     addBuildModeFlags(verboseHelp: verboseHelp);
+    usesExtraFrontendOptions();
     argParser
       ..addFlag(
         'precompiled',
@@ -49,10 +50,6 @@ class BuildBundleCommand extends BuildSubCommand {
           'windows-x64',
         ],
       )
-      ..addMultiOption(FlutterOptions.kExtraFrontEndOptions,
-        splitCommas: true,
-        hide: true,
-      )
       ..addOption('asset-dir', defaultsTo: getAssetBuildDirectory())
       ..addMultiOption(FlutterOptions.kExtraGenSnapshotOptions,
         splitCommas: true,

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

@@ -28,6 +28,7 @@ class BuildIOSCommand extends BuildSubCommand {
     usesBuildNameOption();
     addDartObfuscationOption();
     usesDartDefineOption();
+    usesExtraFrontendOptions();
     argParser
       ..addFlag('simulator',
         help: 'Build for the iOS simulator instead of the device.',

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

@@ -51,6 +51,7 @@ class BuildIOSFrameworkCommand extends BuildSubCommand {
     usesDartDefineOption();
     addSplitDebugInfoOption();
     addDartObfuscationOption();
+    usesExtraFrontendOptions();
     argParser
       ..addFlag('debug',
         negatable: true,

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

@@ -22,6 +22,7 @@ class BuildMacosCommand extends BuildSubCommand {
     usesTargetOption();
     addBuildModeFlags();
     addDartObfuscationOption();
+    usesExtraFrontendOptions();
   }
 
   @override

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

@@ -239,6 +239,10 @@ List<String> _xcodeBuildSettingsLines({
     xcodeBuildSettings.add('DART_DEFINES=${jsonEncode(buildInfo.dartDefines)}');
   }
 
+  if (buildInfo.extraFrontEndOptions?.isNotEmpty ?? false) {
+    xcodeBuildSettings.add('EXTRA_FRONT_END_OPTIONS=${buildInfo.extraFrontEndOptions.join(',')}');
+  }
+
   return xcodeBuildSettings;
 }
 

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

@@ -429,6 +429,13 @@ abstract class FlutterCommand extends Command<void> {
       );
   }
 
+  void usesExtraFrontendOptions() {
+    argParser.addMultiOption(FlutterOptions.kExtraFrontEndOptions,
+      splitCommas: true,
+      hide: true,
+    );
+  }
+
   void usesFuchsiaOptions({ bool hide = false }) {
     argParser.addOption(
       'target-model',

packages/flutter_tools/test/general.shard/build_system/targets/dart_test.dart

@@ -130,6 +130,68 @@ void main() {
     expect(processManager.hasRemainingExpectations, false);
   }));
 
+  test('KernelSnapshot correctly handles an empty string in ExtraFrontEndOptions', () => testbed.run(() async {
+    globals.fs.file('.packages').writeAsStringSync('\n');
+    final String build = androidEnvironment.buildDir.path;
+    processManager = FakeProcessManager.list(<FakeCommand>[
+      FakeCommand(command: <String>[
+        artifacts.getArtifactPath(Artifact.engineDartBinary),
+        artifacts.getArtifactPath(Artifact.frontendServerSnapshotForEngineDartSdk),
+        '--sdk-root',
+        artifacts.getArtifactPath(Artifact.flutterPatchedSdkPath) + '/',
+        '--target=flutter',
+        '-Ddart.developer.causal_async_stacks=false',
+        ...buildModeOptions(BuildMode.profile),
+        '--aot',
+        '--tfa',
+        '--packages',
+        '/.packages',
+        '--output-dill',
+        '$build/app.dill',
+        '--depfile',
+        '$build/kernel_snapshot.d',
+        '/lib/main.dart',
+      ], stdout: 'result $kBoundaryKey\n$kBoundaryKey\n$kBoundaryKey $build/app.dill 0\n'),
+    ]);
+
+    await const KernelSnapshot()
+      .build(androidEnvironment..defines[kExtraFrontEndOptions] = '');
+
+    expect(processManager.hasRemainingExpectations, false);
+  }));
+
+  test('KernelSnapshot correctly forwards ExtraFrontEndOptions', () => testbed.run(() async {
+    globals.fs.file('.packages').writeAsStringSync('\n');
+    final String build = androidEnvironment.buildDir.path;
+    processManager = FakeProcessManager.list(<FakeCommand>[
+      FakeCommand(command: <String>[
+        artifacts.getArtifactPath(Artifact.engineDartBinary),
+        artifacts.getArtifactPath(Artifact.frontendServerSnapshotForEngineDartSdk),
+        '--sdk-root',
+        artifacts.getArtifactPath(Artifact.flutterPatchedSdkPath) + '/',
+        '--target=flutter',
+        '-Ddart.developer.causal_async_stacks=false',
+        ...buildModeOptions(BuildMode.profile),
+        '--aot',
+        '--tfa',
+        '--packages',
+        '/.packages',
+        '--output-dill',
+        '$build/app.dill',
+        '--depfile',
+        '$build/kernel_snapshot.d',
+        'foo',
+        'bar',
+        '/lib/main.dart',
+      ], stdout: 'result $kBoundaryKey\n$kBoundaryKey\n$kBoundaryKey $build/app.dill 0\n'),
+    ]);
+
+    await const KernelSnapshot()
+      .build(androidEnvironment..defines[kExtraFrontEndOptions] = 'foo,bar');
+
+    expect(processManager.hasRemainingExpectations, false);
+  }));
+
   test('KernelSnapshot can disable track-widget-creation on debug builds', () => testbed.run(() async {
     globals.fs.file('.packages').writeAsStringSync('\n');
     final String build = androidEnvironment.buildDir.path;

packages/flutter_tools/test/general.shard/commands/build_apk_test.dart

@@ -279,6 +279,38 @@ void main() {
       ProcessManager: () => mockProcessManager,
     });
 
+    testUsingContext('--extra-front-end-options are provided to gradle project', () async {
+      final String projectPath = await createProject(tempDir,
+          arguments: <String>['--no-pub', '--template=app']);
+
+      await expectLater(() async {
+        await runBuildApkCommand(projectPath, arguments: <String>[
+          '--extra-front-end-options=foo',
+          '--extra-front-end-options=bar',
+        ]);
+      }, throwsToolExit(message: 'Gradle task assembleRelease failed with exit code 1'));
+
+      verify(mockProcessManager.start(
+        <String>[
+          gradlew,
+          '-q',
+          '-Ptarget-platform=android-arm,android-arm64,android-x64',
+          '-Ptarget=${globals.fs.path.join(tempDir.path, 'flutter_project', 'lib', 'main.dart')}',
+          '-Ptrack-widget-creation=true',
+          '-Pextra-front-end-options=foo,bar',
+          '-Pshrink=true',
+          'assembleRelease',
+        ],
+        workingDirectory: anyNamed('workingDirectory'),
+        environment: anyNamed('environment'),
+      )).called(1);
+    },
+    overrides: <Type, Generator>{
+      AndroidSdk: () => mockAndroidSdk,
+      FlutterProjectFactory: () => FakeFlutterProjectFactory(tempDir),
+      ProcessManager: () => mockProcessManager,
+    });
+
     testUsingContext('shrinking is disabled when --no-shrink is passed', () async {
       final String projectPath = await createProject(tempDir,
           arguments: <String>['--no-pub', '--template=app']);