Patch to fix builds with custom targets on iOS simulator. (#17734)

* Patch to fix builds with custom targets on iOS simulator. #16787

* Fix for unused import.

* Code review changes applied.

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

@@ -82,7 +82,7 @@ class BuildIOSCommand extends BuildSubCommand {
     final XcodeBuildResult result = await buildXcodeProject(
       app: app,
       buildInfo: buildInfo,
-      target: targetFile,
+      targetOverride: targetFile,
       buildForDevice: !forSimulator,
       codesign: shouldCodesign,
     );

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

@@ -167,7 +167,7 @@ class IOSDevice extends Device {
       final XcodeBuildResult buildResult = await buildXcodeProject(
           app: package,
           buildInfo: debuggingOptions.buildInfo,
-          target: mainPath,
+          targetOverride: mainPath,
           buildForDevice: true,
           usesTerminalUi: usesTerminalUi,
       );

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

@@ -20,7 +20,6 @@ import '../base/process.dart';
 import '../base/process_manager.dart';
 import '../base/utils.dart';
 import '../build_info.dart';
-import '../bundle.dart' as bundle;
 import '../globals.dart';
 import '../plugins.dart';
 import '../services.dart';
@@ -189,7 +188,7 @@ class Xcode {
 Future<XcodeBuildResult> buildXcodeProject({
   BuildableIOSApp app,
   BuildInfo buildInfo,
-  String target: bundle.defaultMainPath,
+  String targetOverride,
   bool buildForDevice,
   bool codesign: true,
   bool usesTerminalUi: true,
@@ -246,7 +245,7 @@ Future<XcodeBuildResult> buildXcodeProject({
   updateGeneratedXcodeProperties(
     projectPath: fs.currentDirectory.path,
     buildInfo: buildInfo,
-    target: target,
+    targetOverride: targetOverride,
     previewDart2: buildInfo.previewDart2,
   );
 

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

@@ -283,7 +283,7 @@ class IOSSimulator extends Device {
       printTrace('Building ${package.name} for $id.');
 
       try {
-        await _setupUpdatedApplicationBundle(package, debuggingOptions.buildInfo);
+        await _setupUpdatedApplicationBundle(package, debuggingOptions.buildInfo, mainPath, usesTerminalUi);
       } on ToolExit catch (e) {
         printError(e.message);
         return new LaunchResult.failed();
@@ -350,14 +350,14 @@ class IOSSimulator extends Device {
     return criteria.reduce((bool a, bool b) => a && b);
   }
 
-  Future<Null> _setupUpdatedApplicationBundle(ApplicationPackage app, BuildInfo buildInfo) async {
-    await _sideloadUpdatedAssetsForInstalledApplicationBundle(app, buildInfo);
+  Future<Null> _setupUpdatedApplicationBundle(ApplicationPackage app, BuildInfo buildInfo, String mainPath, bool usesTerminalUi) async {
+    await _sideloadUpdatedAssetsForInstalledApplicationBundle(app, buildInfo, mainPath);
 
     if (!await _applicationIsInstalledAndRunning(app))
-      return _buildAndInstallApplicationBundle(app, buildInfo);
+      return _buildAndInstallApplicationBundle(app, buildInfo, mainPath, usesTerminalUi);
   }
 
-  Future<Null> _buildAndInstallApplicationBundle(ApplicationPackage app, BuildInfo buildInfo) async {
+  Future<Null> _buildAndInstallApplicationBundle(ApplicationPackage app, BuildInfo buildInfo, String mainPath, bool usesTerminalUi) async {
     // Step 1: Build the Xcode project.
     // The build mode for the simulator is always debug.
 
@@ -367,7 +367,13 @@ class IOSSimulator extends Device {
         extraGenSnapshotOptions: buildInfo.extraGenSnapshotOptions,
         preferSharedLibrary: buildInfo.preferSharedLibrary);
 
-    final XcodeBuildResult buildResult = await buildXcodeProject(app: app, buildInfo: debugBuildInfo, buildForDevice: false);
+    final XcodeBuildResult buildResult = await buildXcodeProject(
+      app: app,
+      buildInfo: debugBuildInfo,
+      targetOverride: mainPath,
+      buildForDevice: false,
+      usesTerminalUi: usesTerminalUi,
+    );
     if (!buildResult.success)
       throwToolExit('Could not build the application for the simulator.');
 
@@ -382,10 +388,11 @@ class IOSSimulator extends Device {
     await SimControl.instance.install(id, fs.path.absolute(bundle.path));
   }
 
-  Future<Null> _sideloadUpdatedAssetsForInstalledApplicationBundle(ApplicationPackage app, BuildInfo buildInfo) {
+  Future<Null> _sideloadUpdatedAssetsForInstalledApplicationBundle(ApplicationPackage app, BuildInfo buildInfo, String mainPath) {
     // When running in previewDart2 mode, we still need to run compiler to
     // produce kernel file for the application.
     return bundle.build(
+      mainPath: mainPath,
       precompiledSnapshot: !buildInfo.previewDart2,
       previewDart2: buildInfo.previewDart2,
       trackWidgetCreation: buildInfo.trackWidgetCreation,

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

@@ -37,17 +37,20 @@ void generateXcodeProperties(String projectPath) {
     updateGeneratedXcodeProperties(
       projectPath: projectPath,
       buildInfo: BuildInfo.debug,
-      target: bundle.defaultMainPath,
+      targetOverride: bundle.defaultMainPath,
       previewDart2: false,
     );
   }
 }
 
 /// Writes or rewrites Xcode property files with the specified information.
+///
+/// targetOverride: Optional parameter, if null or unspecified the default value
+/// from xcode_backend.sh is used 'lib/main.dart'.
 void updateGeneratedXcodeProperties({
   @required String projectPath,
   @required BuildInfo buildInfo,
-  @required String target,
+  String targetOverride,
   @required bool previewDart2,
 }) {
   final StringBuffer localsBuffer = new StringBuffer();
@@ -61,7 +64,8 @@ void updateGeneratedXcodeProperties({
   localsBuffer.writeln('FLUTTER_APPLICATION_PATH=${fs.path.normalize(projectPath)}');
 
   // Relative to FLUTTER_APPLICATION_PATH, which is [Directory.current].
-  localsBuffer.writeln('FLUTTER_TARGET=$target');
+  if (targetOverride != null)
+    localsBuffer.writeln('FLUTTER_TARGET=$targetOverride');
 
   // The runtime mode for the current build.
   localsBuffer.writeln('FLUTTER_BUILD_MODE=${buildInfo.modeName}');