Migrate older Xcode projects off the legacy build system (#52288)

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

@@ -24,6 +24,7 @@ import '../reporting/reporting.dart';
 import 'code_signing.dart';
 import 'migrations/ios_migrator.dart';
 import 'migrations/remove_framework_link_and_embedding_migration.dart';
+import 'migrations/xcode_build_system_migration.dart';
 import 'xcodeproj.dart';
 
 class IMobileDevice {
@@ -90,7 +91,8 @@ Future<XcodeBuildResult> buildXcodeProject({
   }
 
   final List<IOSMigrator> migrators = <IOSMigrator>[
-    RemoveFrameworkLinkAndEmbeddingMigration(app.project, globals.logger, globals.xcode, globals.flutterUsage)
+    RemoveFrameworkLinkAndEmbeddingMigration(app.project, globals.logger, globals.xcode, globals.flutterUsage),
+    XcodeBuildSystemMigration(app.project, globals.logger),
   ];
 
   final IOSMigration migration = IOSMigration(migrators);

packages/flutter_tools/lib/src/ios/migrations/ios_migrator.dart

@@ -20,7 +20,10 @@ abstract class IOSMigrator {
   bool migrate();
 
   /// Return null if the line should be deleted.
-  String migrateLine(String line);
+  @protected
+  String migrateLine(String line) {
+    return line;
+  }
 
   @protected
   void processFileLines(File file) {

packages/flutter_tools/lib/src/ios/migrations/remove_framework_link_and_embedding_migration.dart

@@ -10,9 +10,9 @@ import '../../project.dart';
 import '../../reporting/reporting.dart';
 import 'ios_migrator.dart';
 
-/// Xcode 11.4 requires linked and embedded frameworks to contain all targeted architectures before build phases are run.
-/// This caused issues switching between a real device and simulator due to architecture mismatch.
-/// Remove the linking and embedding logic from the Xcode project to give the tool more control over these.
+// Xcode 11.4 requires linked and embedded frameworks to contain all targeted architectures before build phases are run.
+// This caused issues switching between a real device and simulator due to architecture mismatch.
+// Remove the linking and embedding logic from the Xcode project to give the tool more control over these.
 class RemoveFrameworkLinkAndEmbeddingMigration extends IOSMigrator {
   RemoveFrameworkLinkAndEmbeddingMigration(
     IosProject project,
@@ -28,13 +28,8 @@ class RemoveFrameworkLinkAndEmbeddingMigration extends IOSMigrator {
   final Xcode _xcode;
   final Usage _usage;
 
-  /// Inspect [project] for necessary migrations and rewrite files as needed.
   @override
   bool migrate() {
-    return _migrateXcodeProjectInfoFile();
-  }
-
-  bool _migrateXcodeProjectInfoFile() {
     if (!_xcodeProjectInfoFile.existsSync()) {
       logger.printTrace('Xcode project not found, skipping migration');
       return true;

packages/flutter_tools/lib/src/ios/migrations/xcode_build_system_migration.dart

@@ -0,0 +1,48 @@
+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import '../../base/file_system.dart';
+import '../../base/logger.dart';
+import '../../project.dart';
+import 'ios_migrator.dart';
+
+// Xcode legacy build system no longer supported by Xcode.
+// Set in https://github.com/flutter/flutter/pull/21901/.
+// Removed in https://github.com/flutter/flutter/pull/33684.
+class XcodeBuildSystemMigration extends IOSMigrator {
+  XcodeBuildSystemMigration(
+    IosProject project,
+    Logger logger,
+  ) : _xcodeWorkspaceSharedSettings = project.xcodeWorkspaceSharedSettings,
+      super(logger);
+
+  final File _xcodeWorkspaceSharedSettings;
+
+  @override
+  bool migrate() {
+    if (!_xcodeWorkspaceSharedSettings.existsSync()) {
+      logger.printTrace('Xcode workspace settings not found, skipping migration');
+      return true;
+    }
+
+    final String contents = _xcodeWorkspaceSharedSettings.readAsStringSync();
+
+    // Only delete this file when it matches the original Flutter template.
+    const String legacyBuildSettingsWorkspace = '''
+<plist version="1.0">
+<dict>
+	<key>BuildSystemType</key>
+	<string>Original</string>
+</dict>
+</plist>''';
+
+    // contains instead of equals to ignore newline file ending variance.
+    if (contents.contains(legacyBuildSettingsWorkspace)) {
+      logger.printStatus('Legacy build system detected, removing ${_xcodeWorkspaceSharedSettings.path}');
+      _xcodeWorkspaceSharedSettings.deleteSync();
+    }
+
+    return true;
+  }
+}

packages/flutter_tools/test/general.shard/ios/ios_project_migration_test.dart

@@ -12,6 +12,7 @@ import 'package:platform/platform.dart';
 import 'package:flutter_tools/src/base/logger.dart';
 import 'package:flutter_tools/src/base/terminal.dart';
 import 'package:flutter_tools/src/ios/migrations/remove_framework_link_and_embedding_migration.dart';
+import 'package:flutter_tools/src/ios/migrations/xcode_build_system_migration.dart';
 import 'package:flutter_tools/src/macos/xcode.dart';
 import 'package:flutter_tools/src/project.dart';
 import 'package:flutter_tools/src/reporting/reporting.dart';
@@ -257,6 +258,84 @@ keep this 2
         verify(mockUsage.sendEvent('ios-migration', 'remove-frameworks', label: 'failure', value: null));
       });
     });
+
+    group('new Xcode build system', () {
+      MemoryFileSystem memoryFileSystem;
+      BufferLogger testLogger;
+      MockIosProject mockIosProject;
+      File xcodeWorkspaceSharedSettings;
+
+      setUp(() {
+        memoryFileSystem = MemoryFileSystem();
+        xcodeWorkspaceSharedSettings = memoryFileSystem.file('WorkspaceSettings.xcsettings');
+
+        testLogger = BufferLogger(
+          terminal: AnsiTerminal(
+            stdio: null,
+            platform: const LocalPlatform(),
+          ),
+          outputPreferences: OutputPreferences.test(),
+        );
+
+        mockIosProject = MockIosProject();
+        when(mockIosProject.xcodeWorkspaceSharedSettings).thenReturn(xcodeWorkspaceSharedSettings);
+      });
+
+      testWithoutContext('skipped if files are missing', () {
+        final XcodeBuildSystemMigration iosProjectMigration = XcodeBuildSystemMigration(
+          mockIosProject,
+          testLogger,
+        );
+        expect(iosProjectMigration.migrate(), isTrue);
+        expect(xcodeWorkspaceSharedSettings.existsSync(), isFalse);
+
+        expect(testLogger.traceText, contains('Xcode workspace settings not found, skipping migration'));
+        expect(testLogger.statusText, isEmpty);
+      });
+
+      testWithoutContext('skipped if nothing to upgrade', () {
+        const String contents = '''
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>BuildSystemType</key>
+	<string></string>
+</dict>
+</plist>''';
+        xcodeWorkspaceSharedSettings.writeAsStringSync(contents);
+
+        final XcodeBuildSystemMigration iosProjectMigration = XcodeBuildSystemMigration(
+          mockIosProject,
+          testLogger,
+        );
+        expect(iosProjectMigration.migrate(), isTrue);
+        expect(xcodeWorkspaceSharedSettings.existsSync(), isTrue);
+        expect(testLogger.statusText, isEmpty);
+      });
+
+      testWithoutContext('Xcode project is migrated', () {
+        const String contents = '''
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>BuildSystemType</key>
+	<string>Original</string>
+</dict>
+</plist>''';
+        xcodeWorkspaceSharedSettings.writeAsStringSync(contents);
+
+        final XcodeBuildSystemMigration iosProjectMigration = XcodeBuildSystemMigration(
+          mockIosProject,
+          testLogger,
+        );
+        expect(iosProjectMigration.migrate(), isTrue);
+        expect(xcodeWorkspaceSharedSettings.existsSync(), isFalse);
+
+        expect(testLogger.statusText, contains('Legacy build system detected, removing'));
+      });
+    });
   });
 }