select ResidentCompiler during FlutterDevice initialization (#28603)

.gitignore

@@ -32,6 +32,9 @@
 /packages/flutter/coverage/
 version
 
+# packages file containing multi-root paths
+.packages.generated
+
 # Flutter/Dart/Pub related
 **/doc/api/
 .dart_tool/

dev/integration_tests/codegen/lib/main.dart

@@ -17,7 +17,7 @@ class ExampleWidget extends StatefulWidget {
 }
 
 class _ExampleWidgetState extends State<ExampleWidget> {
-  String _message = '';
+  bool _pressed = false;
 
   @override
   Widget build(BuildContext context) {
@@ -30,14 +30,21 @@ class _ExampleWidgetState extends State<ExampleWidget> {
               child: const Text('Press Button, Get Coffee'),
               onPressed: () async {
                 setState(() {
-                 _message = generated.message;
+                 _pressed = true;
                 });
               },
             ),
-            Text(_message),
+            _pressed ? GeneratedWidget() : const SizedBox(),
           ],
         ),
       ),
     );
   }
 }
+
+class GeneratedWidget extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    return Text(generated.message);
+  }
+}

dev/integration_tests/codegen/lib/message.spec

-final String message = 'Thanks for using PourOverSupremeFiesta by Coffee by Flutter Inc.';
+String get message => 'Thanks for using PourOverSupremeFiesta by Coffee by Flutter Inc.';

dev/integration_tests/codegen/test/example_test.dart

+import 'package:codegen/main.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  testWidgets('can reference generated code', (WidgetTester tester) async {
+    await tester.pumpWidget(MaterialApp(home: GeneratedWidget()));
+
+    expect(find.text('Thanks for using PourOverSupremeFiesta by Coffee by Flutter Inc.'), findsOneWidget);
+  });
+}

dev/integration_tests/codegen/test_driver/main_test.dart

@@ -24,4 +24,4 @@ void main() {
       final String fullMessage = await driver.getText(find.text(message));
       expect(fullMessage, message);
     });
-}
+}
\ No newline at end of file

packages/flutter_build/lib/src/kernel_builder.dart

@@ -89,25 +89,18 @@ class FlutterKernelBuilder implements Builder {
       return;
     }
     final AssetId outputId = buildStep.inputId.changeExtension(_kFlutterDillOutputExtension);
-    final AssetId packagesOutputId = buildStep.inputId.changeExtension(_kPackagesExtension);
 
     // Create a scratch space file that can be read/written by the frontend server.
     // It is okay to hard-code these file names because we will copy them back
     // from the temp directory at the end of the build step.
     final Directory tempDirecory = await Directory.systemTemp.createTemp('_flutter_build');
-    final File packagesFile = File(path.join(tempDirecory.path, _kPackagesExtension));
+    final Directory projectDir = File(packagesPath).parent;
+    final String packagesFilePath = path.join(projectDir.path, '.packages.generated');
     final File outputFile =  File(path.join(tempDirecory.path, 'main.app.dill'));
     await outputFile.create();
-    await packagesFile.create();
 
-    final Directory projectDir = File(packagesPath).parent;
     final String packageName = buildStep.inputId.package;
-    final String oldPackagesContents = await File(packagesPath).readAsString();
-    // Note: currently we only replace the root package with a multiroot
-    // scheme. To support codegen on arbitrary packages we will need to do
-    // this for each dependency.
-    final String newPackagesContents = oldPackagesContents.replaceFirst('$packageName:lib/', '$packageName:$_kMultirootScheme:/');
-    await packagesFile.writeAsString(newPackagesContents);
+
     String absoluteMainPath;
     if (path.isAbsolute(mainPath)) {
       absoluteMainPath = mainPath;
@@ -143,7 +136,7 @@ class FlutterKernelBuilder implements Builder {
     final String normalRoot =  path.join(projectDir.absolute.path, 'lib${Platform.pathSeparator}');
     arguments.addAll(<String>[
       '--packages',
-      Uri.file(packagesFile.path).toString(),
+      packagesFilePath,
       '--output-dill',
       outputFile.path,
       '--filesystem-root',
@@ -158,7 +151,7 @@ class FlutterKernelBuilder implements Builder {
     }
     final Uri mainUri = _PackageUriMapper.findUri(
       absoluteMainPath,
-      packagesFile.path,
+      packagesFilePath,
       _kMultirootScheme,
       <String>[normalRoot, generatedRoot],
     );
@@ -178,7 +171,6 @@ class FlutterKernelBuilder implements Builder {
       await server.exitCode;
       await _stdoutHandler.compilerOutput.future;
       await buildStep.writeAsBytes(outputId, await outputFile.readAsBytes());
-      await buildStep.writeAsBytes(packagesOutputId, await packagesFile.readAsBytes());
     } catch (err, stackTrace) {
       log.shout('frontend server failed to start: $err, $stackTrace');
     }

packages/flutter_tools/lib/src/build_runner/build_runner.dart

@@ -22,12 +22,18 @@ import '../base/logger.dart';
 import '../base/process_manager.dart';
 import '../codegen.dart';
 import '../convert.dart';
+import '../dart/package_map.dart';
 import '../dart/pub.dart';
 import '../globals.dart';
 import '../project.dart';
 import '../resident_runner.dart';
 import 'build_script_generator.dart';
 
+// Arbitrarily choosen multi-root file scheme. This is used to configure the
+// frontend_server to resolve a package uri to multiple filesystem directories.
+// In this case, the source directory and a generated directory.
+const String _kMultirootScheme = 'org-dartlang-app';
+
 /// A wrapper for a build_runner process which delegates to a generated
 /// build script.
 ///
@@ -37,7 +43,7 @@ class BuildRunner extends CodeGenerator {
   const BuildRunner();
 
   @override
-  Future<CodeGenerationResult> build({
+  Future<CodeGenerationResult> build(FlutterProject flutterProject, {
     @required String mainPath,
     @required bool aot,
     @required bool linkPlatformKernelIn,
@@ -46,8 +52,7 @@ class BuildRunner extends CodeGenerator {
     List<String> extraFrontEndOptions = const <String>[],
     bool disableKernelGeneration = false,
   }) async {
-    await generateBuildScript();
-    final FlutterProject flutterProject = await FlutterProject.current();
+    await generateBuildScript(flutterProject);
     final String frontendServerPath = artifacts.getArtifactPath(
       Artifact.frontendServerSnapshotForEngineDartSdk
     );
@@ -99,7 +104,7 @@ class BuildRunner extends CodeGenerator {
       status.stop();
     }
     if (disableKernelGeneration) {
-      return const CodeGenerationResult(null, null);
+      return const CodeGenerationResult(null);
     }
     /// We don't check for this above because it might be generated for the
     /// first time by invoking the build.
@@ -114,21 +119,17 @@ class BuildRunner extends CodeGenerator {
       throw Exception('build_runner cannot find generated directory');
     }
     final String relativeMain = fs.path.relative(mainPath, from: flutterProject.directory.path);
-    final File packagesFile = fs.file(
-      fs.path.join(generatedDirectory.path,  fs.path.setExtension(relativeMain, '.packages'))
-    );
     final File dillFile = fs.file(
       fs.path.join(generatedDirectory.path, fs.path.setExtension(relativeMain, '.app.dill'))
     );
-    if (!packagesFile.existsSync() || !dillFile.existsSync()) {
+    if (!dillFile.existsSync()) {
       throw Exception('build_runner did not produce output at expected location: ${dillFile.path} missing');
     }
-    return CodeGenerationResult(packagesFile, dillFile);
+    return CodeGenerationResult(dillFile);
   }
 
   @override
-  Future<void> generateBuildScript() async {
-    final FlutterProject flutterProject = await FlutterProject.current();
+  Future<void> generateBuildScript(FlutterProject flutterProject) async {
     final Directory entrypointDirectory = fs.directory(fs.path.join(flutterProject.dartTool.path, 'build', 'entrypoint'));
     final Directory generatedDirectory = fs.directory(fs.path.join(flutterProject.dartTool.path, 'flutter_tool'));
     final File buildScript = entrypointDirectory.childFile('build.dart');
@@ -180,7 +181,6 @@ class BuildRunner extends CodeGenerator {
       stringBuffer.writeln('  flutter_build:');
       stringBuffer.writeln('    sdk: flutter');
       syntheticPubspec.writeAsStringSync(stringBuffer.toString());
-
       await pubGet(
         context: PubContext.pubGet,
         directory: generatedDirectory.path,
@@ -210,7 +210,7 @@ class BuildRunner extends CodeGenerator {
   }
 
   @override
-  Future<CodegenDaemon> daemon({
+  Future<CodegenDaemon> daemon(FlutterProject flutterProject, {
     String mainPath,
     bool linkPlatformKernelIn = false,
     bool targetProductVm = false,
@@ -218,8 +218,8 @@ class BuildRunner extends CodeGenerator {
     List<String> extraFrontEndOptions = const <String> [],
   }) async {
     mainPath ??= findMainDartFile();
-    await generateBuildScript();
-    final FlutterProject flutterProject = await FlutterProject.current();
+    await generateBuildScript(flutterProject);
+    _generatePackages(flutterProject);
     final String frontendServerPath = artifacts.getArtifactPath(
       Artifact.frontendServerSnapshotForEngineDartSdk
     );
@@ -265,19 +265,28 @@ class BuildRunner extends CodeGenerator {
       builder.target = flutterProject.manifest.appName;
     }));
     final String relativeMain = fs.path.relative(mainPath, from: flutterProject.directory.path);
-    final File generatedPackagesFile = fs.file(fs.path.join(flutterProject.generated.path, fs.path.setExtension(relativeMain, '.packages')));
     final File generatedDillFile = fs.file(fs.path.join(flutterProject.generated.path, fs.path.setExtension(relativeMain, '.app.dill')));
-    return _BuildRunnerCodegenDaemon(buildDaemonClient, generatedPackagesFile, generatedDillFile);
+    return _BuildRunnerCodegenDaemon(buildDaemonClient, generatedDillFile);
+  }
+
+  // Create generated packages file which adds a multi-root scheme to the user's
+  // project directory. Currently we only replace the root package with a multiroot
+  // scheme. To support codegen on arbitrary packages we would need to do
+  // this for each dependency.
+  void _generatePackages(FlutterProject flutterProject) {
+    final String oldPackagesContents = fs.file(PackageMap.globalPackagesPath).readAsStringSync();
+    final String appName = flutterProject.manifest.appName;
+    final String newPackagesContents = oldPackagesContents.replaceFirst('$appName:lib/', '$appName:$_kMultirootScheme:/');
+    final String generatedPackagesPath = fs.path.setExtension(PackageMap.globalPackagesPath, '.generated');
+    fs.file(generatedPackagesPath).writeAsStringSync(newPackagesContents);
   }
 }
 
 class _BuildRunnerCodegenDaemon implements CodegenDaemon {
-  _BuildRunnerCodegenDaemon(this.buildDaemonClient, this.packagesFile, this.dillFile);
+  _BuildRunnerCodegenDaemon(this.buildDaemonClient, this.dillFile);
 
   final BuildDaemonClient buildDaemonClient;
   @override
-  final File packagesFile;
-  @override
   final File dillFile;
   @override
   CodegenStatus get lastStatus => _lastStatus;

packages/flutter_tools/lib/src/codegen.dart

@@ -9,6 +9,7 @@ import 'base/context.dart';
 import 'base/file_system.dart';
 import 'base/platform.dart';
 import 'compile.dart';
+import 'dart/package_map.dart';
 import 'globals.dart';
 import 'project.dart';
 
@@ -44,8 +45,9 @@ abstract class CodeGenerator {
   const CodeGenerator();
 
   /// Run a partial build include code generators but not kernel.
-  Future<void> generate({@required String mainPath}) async {
+  Future<void> generate(FlutterProject flutterProject, {@required String mainPath}) async {
     await build(
+      flutterProject,
       mainPath: mainPath,
       aot: false,
       linkPlatformKernelIn: false,
@@ -59,7 +61,7 @@ abstract class CodeGenerator {
   ///
   /// The defines of the build command are the arguments required in the
   /// flutter_build kernel builder.
-  Future<CodeGenerationResult> build({
+  Future<CodeGenerationResult> build(FlutterProject flutterProject, {
     @required String mainPath,
     @required bool aot,
     @required bool linkPlatformKernelIn,
@@ -73,7 +75,7 @@ abstract class CodeGenerator {
   ///
   /// The defines of the daemon command are the arguments required in the
   /// flutter_build kernel builder.
-  Future<CodegenDaemon> daemon({
+  Future<CodegenDaemon> daemon(FlutterProject flutterProject, {
     @required String mainPath,
     bool linkPlatformKernelIn = false,
     bool targetProductVm = false,
@@ -83,14 +85,14 @@ abstract class CodeGenerator {
 
   // Generates a synthetic package under .dart_tool/flutter_tool which is in turn
   // used to generate a build script.
-  Future<void> generateBuildScript();
+  Future<void> generateBuildScript(FlutterProject flutterProject);
 }
 
 class UnsupportedCodeGenerator extends CodeGenerator {
   const UnsupportedCodeGenerator();
 
   @override
-  Future<CodeGenerationResult> build({
+  Future<CodeGenerationResult> build(FlutterProject flutterProject, {
     String mainPath,
     bool aot,
     bool linkPlatformKernelIn,
@@ -103,12 +105,12 @@ class UnsupportedCodeGenerator extends CodeGenerator {
   }
 
   @override
-  Future<void> generateBuildScript() {
+  Future<void> generateBuildScript(FlutterProject flutterProject) {
     throw UnsupportedError('build_runner is not currently supported.');
   }
 
   @override
-  Future<CodegenDaemon> daemon({
+  Future<CodegenDaemon> daemon(FlutterProject flutterProject, {
     String mainPath,
     bool linkPlatformKernelIn = false,
     bool targetProductVm = false,
@@ -128,8 +130,6 @@ abstract class CodegenDaemon {
   /// Starts a new build.
   void startBuild();
 
-  File get packagesFile;
-
   File get dillFile;
 }
 
@@ -137,9 +137,8 @@ abstract class CodegenDaemon {
 ///
 /// If no dill or packages file is generated, they will be null.
 class CodeGenerationResult {
-  const CodeGenerationResult(this.packagesFile, this.dillFile);
+  const CodeGenerationResult(this.dillFile);
 
-  final File packagesFile;
   final File dillFile;
 }
 
@@ -176,8 +175,10 @@ class CodeGeneratingKernelCompiler implements KernelCompiler {
         'sdkRoot, packagesPath are not supported when using the experimental '
         'build* pipeline');
     }
+    final FlutterProject flutterProject = await FlutterProject.current();
     try {
       final CodeGenerationResult buildResult = await codeGenerator.build(
+        flutterProject,
         aot: aot,
         linkPlatformKernelIn: linkPlatformKernelIn,
         trackWidgetCreation: trackWidgetCreation,
@@ -206,13 +207,16 @@ class CodeGeneratingResidentCompiler implements ResidentCompiler {
   /// Creates a new [ResidentCompiler] and configures a [BuildDaemonClient] to
   /// run builds.
   static Future<CodeGeneratingResidentCompiler> create({
-    @required String mainPath,
+    @required FlutterProject flutterProject,
+    String mainPath,
     bool trackWidgetCreation = false,
     CompilerMessageConsumer compilerMessageConsumer = printError,
     bool unsafePackageSerialization = false,
+    String outputPath,
+    String initializeFromDill,
   }) async {
-    final FlutterProject flutterProject = await FlutterProject.current();
     final CodegenDaemon codegenDaemon = await codeGenerator.daemon(
+      flutterProject,
       extraFrontEndOptions: <String>[],
       linkPlatformKernelIn: false,
       mainPath: mainPath,
@@ -221,22 +225,23 @@ class CodeGeneratingResidentCompiler implements ResidentCompiler {
     );
     codegenDaemon.startBuild();
     final CodegenStatus status = await codegenDaemon.buildResults.firstWhere((CodegenStatus status) {
-      return status ==CodegenStatus.Succeeded || status == CodegenStatus.Failed;
+      return status == CodegenStatus.Succeeded || status == CodegenStatus.Failed;
     });
     if (status == CodegenStatus.Failed) {
-      printError('Codegeneration failed, halting build.');
+      printError('Code generation failed, build may have compile errors');
     }
     final ResidentCompiler residentCompiler = ResidentCompiler(
       artifacts.getArtifactPath(Artifact.flutterPatchedSdkPath),
       trackWidgetCreation: trackWidgetCreation,
-      packagesPath: codegenDaemon.packagesFile.path,
+      packagesPath: PackageMap.globalGeneratedPackagesPath,
       fileSystemRoots: <String>[
-        fs.path.join(flutterProject.generated.absolute.path, 'lib${platform.pathSeparator}'),
+        fs.path.join(flutterProject.generated.path, 'lib${platform.pathSeparator}'),
         fs.path.join(flutterProject.directory.path, 'lib${platform.pathSeparator}'),
       ],
       fileSystemScheme: _kMultiRootScheme,
       targetModel: TargetModel.flutter,
       unsafePackageSerialization: unsafePackageSerialization,
+      initializeFromDill: initializeFromDill,
     );
     return CodeGeneratingResidentCompiler._(residentCompiler, codegenDaemon);
   }
@@ -274,7 +279,7 @@ class CodeGeneratingResidentCompiler implements ResidentCompiler {
       mainPath,
       invalidatedFiles,
       outputPath: outputPath,
-      packagesFilePath: _codegenDaemon.packagesFile.path,
+      packagesFilePath: PackageMap.globalGeneratedPackagesPath,
     );
   }
 

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

@@ -205,13 +205,14 @@ class AttachCommand extends FlutterCommand {
     }
     try {
       final bool useHot = getBuildInfo().isDebug;
-      final FlutterDevice flutterDevice = FlutterDevice(
+      final FlutterDevice flutterDevice = await FlutterDevice.create(
         device,
         trackWidgetCreation: false,
         dillOutputPath: argResults['output-dill'],
         fileSystemRoots: argResults['filesystem-root'],
         fileSystemScheme: argResults['filesystem-scheme'],
         viewFilter: argResults['isolate-filter'],
+        target: argResults['target'],
         targetModel: TargetModel(argResults['target-model']),
       );
       flutterDevice.observatoryUris = <Uri>[ observatoryUri ];

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

@@ -346,11 +346,12 @@ class AppDomain extends Domain {
     final Directory cwd = fs.currentDirectory;
     fs.currentDirectory = fs.directory(projectDirectory);
 
-    final FlutterDevice flutterDevice = FlutterDevice(
+    final FlutterDevice flutterDevice = await FlutterDevice.create(
       device,
       trackWidgetCreation: trackWidgetCreation,
       dillOutputPath: dillOutputPath,
       viewFilter: isolateFilter,
+      target: target,
     );
 
     ResidentRunner runner;

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

@@ -4,6 +4,7 @@
 
 import '../base/common.dart';
 import '../codegen.dart';
+import '../project.dart';
 import '../runner/flutter_command.dart';
 
 class GenerateCommand extends FlutterCommand {
@@ -24,7 +25,8 @@ class GenerateCommand extends FlutterCommand {
     if (!experimentalBuildEnabled) {
       throwToolExit('FLUTTER_EXPERIMENTAL_BUILD is not enabled, codegen is unsupported.');
     }
-    await codeGenerator.generate(mainPath: argResults['target']);
+    final FlutterProject flutterProject = await FlutterProject.current();
+    await codeGenerator.generate(flutterProject, mainPath: argResults['target']);
     return null;
   }
 }

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

@@ -10,8 +10,6 @@ import '../base/time.dart';
 import '../base/utils.dart';
 import '../build_info.dart';
 import '../cache.dart';
-import '../codegen.dart';
-import '../compile.dart';
 import '../device.dart';
 import '../globals.dart';
 import '../ios/mac.dart';
@@ -346,13 +344,9 @@ class RunCommand extends RunCommandBase {
         argResults[FlutterOptions.kEnableExperiment].isNotEmpty) {
       expFlags = argResults[FlutterOptions.kEnableExperiment];
     }
-
-    ResidentCompiler residentCompiler;
-    if (experimentalBuildEnabled) {
-      residentCompiler = await CodeGeneratingResidentCompiler.create(mainPath: argResults['target']);
-    }
-    final List<FlutterDevice> flutterDevices = devices.map<FlutterDevice>((Device device) {
-      return FlutterDevice(
+    final List<FlutterDevice> flutterDevices = <FlutterDevice>[];
+    for (Device device in devices) {
+      final FlutterDevice flutterDevice = await FlutterDevice.create(
         device,
         trackWidgetCreation: argResults['track-widget-creation'],
         dillOutputPath: argResults['output-dill'],
@@ -360,9 +354,10 @@ class RunCommand extends RunCommandBase {
         fileSystemScheme: argResults['filesystem-scheme'],
         viewFilter: argResults['isolate-filter'],
         experimentalFlags: expFlags,
-        generator: residentCompiler,
+        target: argResults['target'],
       );
-    }).toList();
+      flutterDevices.add(flutterDevice);
+    }
 
     ResidentRunner runner;
     final String applicationBinaryPath = argResults['use-application-binary'];

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

@@ -9,6 +9,7 @@ import '../base/common.dart';
 import '../base/file_system.dart';
 import '../base/platform.dart';
 import '../cache.dart';
+import '../project.dart';
 import '../runner/flutter_command.dart';
 import '../test/coverage_collector.dart';
 import '../test/event_printer.dart';
@@ -104,6 +105,7 @@ class TestCommand extends FlutterCommand {
   Future<FlutterCommandResult> runCommand() async {
     final List<String> names = argResults['name'];
     final List<String> plainNames = argResults['plain-name'];
+    final FlutterProject flutterProject = await FlutterProject.current();
 
     Iterable<String> files = argResults.rest.map<String>((String testPath) => fs.path.absolute(testPath)).toList();
 
@@ -170,6 +172,7 @@ class TestCommand extends FlutterCommand {
       trackWidgetCreation: argResults['track-widget-creation'],
       updateGoldens: argResults['update-goldens'],
       concurrency: jobs,
+      flutterProject: flutterProject,
     );
 
     if (collector != null) {

packages/flutter_tools/lib/src/compile.dart

@@ -661,7 +661,11 @@ class ResidentCompiler {
     return null;
   }
 
-  Future<dynamic> shutdown() {
+  Future<dynamic> shutdown() async {
+    // Server was never sucessfully created.
+    if (_server == null) {
+      return 0;
+    }
     _server.kill();
     return _server.exitCode;
   }

packages/flutter_tools/lib/src/dart/package_map.dart

@@ -20,6 +20,8 @@ class PackageMap {
 
   static String get globalPackagesPath => _globalPackagesPath ?? kPackagesFileName;
 
+  static String get globalGeneratedPackagesPath => fs.path.setExtension(globalPackagesPath, '.generated');
+
   static set globalPackagesPath(String value) {
     _globalPackagesPath = value;
   }

packages/flutter_tools/lib/src/project.dart

@@ -113,6 +113,7 @@ class FlutterProject {
 
   /// The directory containing the generated code for this project.
   Directory get generated => directory
+    .absolute
     .childDirectory('.dart_tool')
     .childDirectory('build')
     .childDirectory('generated')
@@ -165,6 +166,12 @@ class FlutterProject {
     final YamlMap pubspec = loadYaml(await pubspecFile.readAsString());
     return pubspec['builders'];
   }
+
+  /// Whether there are any builders used by this package.
+  Future<bool> get hasBuilders async {
+    final YamlMap result = await builders;
+    return result != null && result.isNotEmpty;
+  }
 }
 
 /// Represents the iOS sub-project of a Flutter project.

packages/flutter_tools/lib/src/resident_runner.dart

@@ -49,6 +49,45 @@ class FlutterDevice {
          experimentalFlags: experimentalFlags,
        );
 
+  /// Create a [FlutterDevice] with optional code generation enabled.
+  static Future<FlutterDevice> create(Device device, {
+    @required bool trackWidgetCreation,
+    String dillOutputPath,
+    List<String> fileSystemRoots,
+    String fileSystemScheme,
+    String viewFilter,
+    @required String target,
+    TargetModel targetModel = TargetModel.flutter,
+    List<String> experimentalFlags,
+    ResidentCompiler generator,
+  }) async {
+    ResidentCompiler generator;
+    final FlutterProject flutterProject = await FlutterProject.current();
+    if (experimentalBuildEnabled && await flutterProject.hasBuilders) {
+      generator = await CodeGeneratingResidentCompiler.create(flutterProject: flutterProject, mainPath: target);
+    } else {
+      generator = ResidentCompiler(
+        artifacts.getArtifactPath(Artifact.flutterPatchedSdkPath),
+        trackWidgetCreation: trackWidgetCreation,
+        fileSystemRoots: fileSystemRoots,
+        fileSystemScheme: fileSystemScheme,
+        targetModel: targetModel,
+        experimentalFlags: experimentalFlags,
+      );
+    }
+    return FlutterDevice(
+      device,
+      trackWidgetCreation: trackWidgetCreation,
+      dillOutputPath: dillOutputPath,
+      fileSystemRoots: fileSystemRoots,
+      fileSystemScheme:fileSystemScheme,
+      viewFilter: viewFilter,
+      experimentalFlags: experimentalFlags,
+      targetModel: targetModel,
+      generator: generator,
+    );
+  }
+
   final Device device;
   final ResidentCompiler generator;
   List<Uri> observatoryUris;

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

@@ -24,10 +24,12 @@ import '../base/process_manager.dart';
 import '../base/terminal.dart';
 import '../build_info.dart';
 import '../bundle.dart';
+import '../codegen.dart';
 import '../compile.dart';
 import '../convert.dart';
 import '../dart/package_map.dart';
 import '../globals.dart';
+import '../project.dart';
 import '../vmservice.dart';
 import 'watcher.dart';
 
@@ -89,6 +91,7 @@ void installHook({
   int observatoryPort,
   InternetAddressType serverType = InternetAddressType.IPv4,
   Uri projectRootDirectory,
+  FlutterProject flutterProject,
 }) {
   assert(enableObservatory || (!startPaused && observatoryPort == null));
   hack.registerPlatformPlugin(
@@ -107,6 +110,7 @@ void installHook({
       trackWidgetCreation: trackWidgetCreation,
       updateGoldens: updateGoldens,
       projectRootDirectory: projectRootDirectory,
+      flutterProject: flutterProject,
     ),
   );
 }
@@ -232,7 +236,7 @@ class _CompilationRequest {
 // This class is a wrapper around compiler that allows multiple isolates to
 // enqueue compilation requests, but ensures only one compilation at a time.
 class _Compiler {
-  _Compiler(bool trackWidgetCreation, Uri projectRootDirectory) {
+  _Compiler(bool trackWidgetCreation, Uri projectRootDirectory, FlutterProject flutterProject) {
     // Compiler maintains and updates single incremental dill file.
     // Incremental compilation requests done for each test copy that file away
     // for independent execution.
@@ -265,7 +269,16 @@ class _Compiler {
       trackWidgetCreation: trackWidgetCreation,
     );
 
-    ResidentCompiler createCompiler() {
+    Future<ResidentCompiler> createCompiler() async {
+      if (experimentalBuildEnabled && await flutterProject.hasBuilders) {
+        return CodeGeneratingResidentCompiler.create(
+          flutterProject: flutterProject,
+          trackWidgetCreation: trackWidgetCreation,
+          initializeFromDill: null, // TODO(jonahwilliams): investigate multi-root support in init from dill.
+          unsafePackageSerialization: false,
+          compilerMessageConsumer: reportCompilerMessage,
+        );
+      }
       return ResidentCompiler(
         artifacts.getArtifactPath(Artifact.flutterPatchedSdkPath),
         packagesPath: PackageMap.globalPackagesPath,
@@ -290,7 +303,7 @@ class _Compiler {
           final Stopwatch compilerTime = Stopwatch()..start();
           bool firstCompile = false;
           if (compiler == null) {
-            compiler = createCompiler();
+            compiler = await createCompiler();
             firstCompile = true;
           }
           suppressOutput = false;
@@ -374,6 +387,7 @@ class _FlutterPlatform extends PlatformPlugin {
     this.trackWidgetCreation,
     this.updateGoldens,
     this.projectRootDirectory,
+    this.flutterProject,
   }) : assert(shellPath != null);
 
   final String shellPath;
@@ -389,6 +403,7 @@ class _FlutterPlatform extends PlatformPlugin {
   final bool trackWidgetCreation;
   final bool updateGoldens;
   final Uri projectRootDirectory;
+  final FlutterProject flutterProject;
 
   Directory fontsDirectory;
   _Compiler compiler;
@@ -545,7 +560,7 @@ class _FlutterPlatform extends PlatformPlugin {
 
       if (precompiledDillPath == null && precompiledDillFiles == null) {
         // Lazily instantiate compiler so it is built only if it is actually used.
-        compiler ??= _Compiler(trackWidgetCreation, projectRootDirectory);
+        compiler ??= _Compiler(trackWidgetCreation, projectRootDirectory, flutterProject);
         mainDart = await compiler.compile(mainDart);
 
         if (mainDart == null) {

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

@@ -15,6 +15,7 @@ import '../base/process_manager.dart';
 import '../base/terminal.dart';
 import '../dart/package_map.dart';
 import '../globals.dart';
+import '../project.dart';
 import 'flutter_platform.dart' as loader;
 import 'watcher.dart';
 
@@ -34,6 +35,7 @@ Future<int> runTests(
   bool updateGoldens = false,
   TestWatcher watcher,
   @required int concurrency,
+  FlutterProject flutterProject,
 }) async {
   // Compute the command-line arguments for package:test.
   final List<String> testArgs = <String>[];
@@ -80,6 +82,7 @@ Future<int> runTests(
     trackWidgetCreation: trackWidgetCreation,
     updateGoldens: updateGoldens,
     projectRootDirectory: fs.currentDirectory.uri,
+    flutterProject: flutterProject,
   );
 
   // Make the global packages path absolute.

packages/flutter_tools/test/build_runner/code_generating_kernel_compiler.dart

@@ -30,6 +30,7 @@ void main() {
     testUsingContext('delegates to build_runner', () async {
       const CodeGeneratingKernelCompiler kernelCompiler = CodeGeneratingKernelCompiler();
       when(mockBuildRunner.build(
+        any,
         aot: anyNamed('aot'),
         extraFrontEndOptions: anyNamed('extraFrontEndOptions'),
         linkPlatformKernelIn: anyNamed('linkPlatformKernelIn'),
@@ -37,7 +38,7 @@ void main() {
         targetProductVm: anyNamed('targetProductVm'),
         trackWidgetCreation: anyNamed('trackWidgetCreation'),
       )).thenAnswer((Invocation invocation) async {
-        return CodeGenerationResult(fs.file('.packages'), fs.file('main.app.dill'));
+        return CodeGenerationResult(fs.file('main.app.dill'));
       });
       final CompilerOutput buildResult = await kernelCompiler.compile(
         outputFilePath: 'output.app.dill',