Remove extra slash from builder that is not handled on windows (#28027)

packages/flutter_build/lib/src/kernel_builder.dart

@@ -155,11 +155,11 @@ class FlutterKernelBuilder implements Builder {
     if (incrementalCompilerByteStorePath != null) {
       arguments.add('--incremental');
     }
-    final String generatedRoot = path.join(projectDir.absolute.path, '.dart_tool', 'build', 'generated', '$packageName', 'lib');
-    final String normalRoot =  path.join(projectDir.absolute.path, 'lib');
+    final String generatedRoot = path.join(projectDir.absolute.path, '.dart_tool', 'build', 'generated', '$packageName', 'lib${Platform.pathSeparator}');
+    final String normalRoot =  path.join(projectDir.absolute.path, 'lib${Platform.pathSeparator}');
     arguments.addAll(<String>[
       '--packages',
-      packagesFile.path,
+      Uri.file(packagesFile.path).toString(),
       '--output-dill',
       outputFile.path,
       '--filesystem-root',

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

@@ -4,8 +4,9 @@
 
 import 'dart:async';
 
+import 'package:build_daemon/data/build_status.dart';
 import 'package:build_daemon/data/build_target.dart';
-import 'package:build_runner_core/build_runner_core.dart';
+import 'package:build_runner_core/build_runner_core.dart' hide BuildStatus;
 import 'package:build_daemon/data/server_log.dart';
 import 'package:build_daemon/data/build_status.dart' as build;
 import 'package:build_daemon/client.dart';
@@ -87,7 +88,7 @@ class BuildRunner extends CodeGenerator {
           .stdout
           .transform(utf8.decoder)
           .transform(const LineSplitter())
-          .listen(printStatus);
+          .listen(printTrace);
       buildProcess
           .stderr
           .transform(utf8.decoder)
@@ -153,7 +154,7 @@ class BuildRunner extends CodeGenerator {
       final File syntheticPubspec = fs.file(fs.path.join(generatedDirectory, 'pubspec.yaml'));
       final StringBuffer stringBuffer = StringBuffer();
 
-      stringBuffer.writeln('name: synthetic_example');
+      stringBuffer.writeln('name: flutter_tool');
       stringBuffer.writeln('dependencies:');
       final YamlMap builders = await flutterProject.builders;
       for (String name in builders.keys) {
@@ -252,8 +253,17 @@ class _BuildRunnerCodegenDaemon implements CodegenDaemon {
   final File dillFile;
 
   @override
-  Stream<bool> get buildResults => buildDaemonClient.buildResults.map((build.BuildResults results) {
-    return results.results.first.status == build.BuildStatus.succeeded;
+  Stream<CodegenStatus> get buildResults => buildDaemonClient.buildResults.map((build.BuildResults results) {
+    if (results.results.first.status == BuildStatus.failed) {
+      return CodegenStatus.Failed;
+    }
+    if (results.results.first.status == BuildStatus.started) {
+      return CodegenStatus.Started;
+    }
+    if (results.results.first.status == BuildStatus.succeeded) {
+      return CodegenStatus.Succeeded;
+    }
+    return null;
   });
 
   @override

packages/flutter_tools/lib/src/codegen.dart

@@ -132,7 +132,7 @@ class UnsupportedCodeGenerator extends CodeGenerator {
 
 abstract class CodegenDaemon {
   /// Whether the previously enqueued build was successful.
-  Stream<bool> get buildResults;
+  Stream<CodegenStatus> get buildResults;
 
   /// Starts a new build.
   void startBuild();
@@ -229,14 +229,19 @@ class CodeGeneratingResidentCompiler implements ResidentCompiler {
       trackWidgetCreation: trackWidgetCreation,
     );
     codegenDaemon.startBuild();
-    await codegenDaemon.buildResults.firstWhere((bool result) => result);
+    final CodegenStatus status = await codegenDaemon.buildResults.firstWhere((CodegenStatus status) {
+      return status ==CodegenStatus.Succeeded || status == CodegenStatus.Failed;
+    });
+    if (status == CodegenStatus.Failed) {
+      printError('Codegeneration failed, halting build.');
+    }
     final ResidentCompiler residentCompiler = ResidentCompiler(
       artifacts.getArtifactPath(Artifact.flutterPatchedSdkPath),
       trackWidgetCreation: trackWidgetCreation,
       packagesPath: codegenDaemon.packagesFile.path,
       fileSystemRoots: <String>[
-        flutterProject.generated.absolute.path,
-        flutterProject.directory.path,
+        fs.path.join(flutterProject.generated.absolute.path, 'lib${platform.pathSeparator}'),
+        fs.path.join(flutterProject.directory.path, 'lib${platform.pathSeparator}'),
       ],
       fileSystemScheme: _kMultiRootScheme,
       targetModel: TargetModel.flutter,
@@ -261,7 +266,12 @@ class CodeGeneratingResidentCompiler implements ResidentCompiler {
   @override
   Future<CompilerOutput> recompile(String mainPath, List<String> invalidatedFiles, {String outputPath, String packagesFilePath}) async {
     _codegenDaemon.startBuild();
-    await _codegenDaemon.buildResults.first;
+    final CodegenStatus status = await _codegenDaemon.buildResults.firstWhere((CodegenStatus status) {
+      return status ==CodegenStatus.Succeeded || status == CodegenStatus.Failed;
+    });
+    if (status == CodegenStatus.Failed) {
+      printError('Codegeneration failed, halting build.');
+    }
     // Delete this file so that the frontend_server can handle multi-root.
     // TODO(jonahwilliams): investigate frontend_server behavior in the presence
     // of multi-root and initialize from dill.
@@ -291,3 +301,16 @@ class CodeGeneratingResidentCompiler implements ResidentCompiler {
     return _residentCompiler.shutdown();
   }
 }
+
+/// The current status of a codegen build.
+enum CodegenStatus {
+  /// The build has started running.
+  ///
+  /// If this is the current status when running a hot reload, an additional build does
+  /// not need to be started.
+  Started,
+  /// The build succeeded.
+  Succeeded,
+  /// The build failed.
+  Failed
+}