Exclude arm64 from iOS app archs if unsupported by plugins (#87244)

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

@@ -4,6 +4,7 @@
 
 import '../artifacts.dart';
 import '../base/file_system.dart';
+import '../base/os.dart';
 import '../build_info.dart';
 import '../cache.dart';
 import '../flutter_manifest.dart';
@@ -35,7 +36,7 @@ Future<void> updateGeneratedXcodeProperties({
   bool useMacOSConfig = false,
   String? buildDirOverride,
 }) async {
-  final List<String> xcodeBuildSettings = _xcodeBuildSettingsLines(
+  final List<String> xcodeBuildSettings = await _xcodeBuildSettingsLines(
     project: project,
     buildInfo: buildInfo,
     targetOverride: targetOverride,
@@ -136,13 +137,13 @@ String? parsedBuildNumber({
 }
 
 /// List of lines of build settings. Example: 'FLUTTER_BUILD_DIR=build'
-List<String> _xcodeBuildSettingsLines({
+Future<List<String>> _xcodeBuildSettingsLines({
   required FlutterProject project,
   required BuildInfo buildInfo,
   String? targetOverride,
   bool useMacOSConfig = false,
   String? buildDirOverride,
-}) {
+}) async {
   final List<String> xcodeBuildSettings = <String>[];
 
   final String flutterRoot = globals.fs.path.normalize(Cache.flutterRoot!);
@@ -204,7 +205,15 @@ List<String> _xcodeBuildSettingsLines({
     // ARM not yet supported https://github.com/flutter/flutter/issues/69221
     xcodeBuildSettings.add('EXCLUDED_ARCHS=arm64');
   } else {
-    xcodeBuildSettings.add('EXCLUDED_ARCHS[sdk=iphonesimulator*]=i386');
+    String excludedSimulatorArchs = 'i386';
+
+    // If any plugins or their dependencies do not support arm64 simulators
+    // (to run natively without Rosetta translation on an ARM Mac),
+    // the app will fail to build unless it also excludes arm64 simulators.
+    if (globals.os.hostPlatform == HostPlatform.darwin_arm && !(await project.ios.pluginsSupportArmSimulator())) {
+      excludedSimulatorArchs += ' arm64';
+    }
+    xcodeBuildSettings.add('EXCLUDED_ARCHS[sdk=iphonesimulator*]=$excludedSimulatorArchs');
   }
 
   for (final MapEntry<String, String> config in buildInfo.toEnvironmentConfig().entries) {

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

@@ -215,6 +215,58 @@ class XcodeProjectInterpreter {
     }
   }
 
+  /// Asynchronously retrieve xcode build settings for the generated Pods.xcodeproj plugins project.
+  ///
+  /// Returns the stdout of the Xcode command.
+  Future<String?> pluginsBuildSettingsOutput(
+      Directory podXcodeProject, {
+        Duration timeout = const Duration(minutes: 1),
+      }) async {
+    if (!podXcodeProject.existsSync()) {
+      // No plugins.
+      return null;
+    }
+    final Status status = _logger.startSpinner();
+    final List<String> showBuildSettingsCommand = <String>[
+      ...xcrunCommand(),
+      'xcodebuild',
+      '-alltargets',
+      '-sdk',
+      'iphonesimulator',
+      '-project',
+      podXcodeProject.path,
+      '-showBuildSettings',
+    ];
+    try {
+      // showBuildSettings is reported to occasionally timeout. Here, we give it
+      // a lot of wiggle room (locally on Flutter Gallery, this takes ~1s).
+      // When there is a timeout, we retry once.
+      final RunResult result = await _processUtils.run(
+        showBuildSettingsCommand,
+        throwOnError: true,
+        workingDirectory: podXcodeProject.path,
+        timeout: timeout,
+        timeoutRetries: 1,
+      );
+
+      // Return the stdout only. Do not parse with parseXcodeBuildSettings, `-alltargets` prints the build settings
+      // for all targets (one per plugin), so it would require a Map of Maps.
+      return result.stdout.trim();
+    } on Exception catch (error) {
+      if (error is ProcessException && error.toString().contains('timed out')) {
+        BuildEvent('xcode-show-build-settings-timeout',
+          type: 'ios',
+          command: showBuildSettingsCommand.join(' '),
+          flutterUsage: _usage,
+        ).send();
+      }
+      _logger.printTrace('Unexpected failure to get Pod Xcode project build settings: $error.');
+      return null;
+    } finally {
+      status.stop();
+    }
+  }
+
   Future<void> cleanWorkspace(String workspacePath, String scheme, { bool verbose = false }) async {
     await _processUtils.run(<String>[
       ...xcrunCommand(),

packages/flutter_tools/lib/src/xcode_project.dart

@@ -146,6 +146,30 @@ class IosProject extends FlutterProjectPlatform implements XcodeBasedProject {
   /// Xcode workspace shared workspace settings file for the host app.
   File get xcodeWorkspaceSharedSettings => xcodeWorkspaceSharedData.childFile('WorkspaceSettings.xcsettings');
 
+  /// Do all plugins support arm64 simulators to run natively on an ARM Mac?
+  Future<bool> pluginsSupportArmSimulator() async {
+    final Directory podXcodeProject = hostAppRoot
+        .childDirectory('Pods')
+        .childDirectory('Pods.xcodeproj');
+    if (!podXcodeProject.existsSync()) {
+      // No plugins.
+      return true;
+    }
+
+    final XcodeProjectInterpreter? xcodeProjectInterpreter = globals.xcodeProjectInterpreter;
+    if (xcodeProjectInterpreter == null) {
+      // Xcode isn't installed, don't try to check.
+      return false;
+    }
+    final String? buildSettings = await xcodeProjectInterpreter.pluginsBuildSettingsOutput(podXcodeProject);
+
+    // See if any plugins or their dependencies exclude arm64 simulators
+    // as a valid architecture, usually because a binary is missing that slice.
+    // Example: EXCLUDED_ARCHS = arm64 i386
+    // NOT: EXCLUDED_ARCHS = i386
+    return buildSettings != null && !buildSettings.contains(RegExp('EXCLUDED_ARCHS.*arm64'));
+  }
+
   @override
   bool existsSync()  {
     return parent.isModule || _editableDirectory.existsSync();

packages/flutter_tools/test/src/context.dart

@@ -306,6 +306,14 @@ class FakeXcodeProjectInterpreter implements XcodeProjectInterpreter {
     return <String, String>{};
   }
 
+  @override
+  Future<String> pluginsBuildSettingsOutput(
+      Directory podXcodeProject, {
+        Duration timeout = const Duration(minutes: 1),
+      }) async {
+    return null;
+  }
+
   @override
   Future<void> cleanWorkspace(String workspacePath, String scheme, { bool verbose = false }) {
     return null;