Exclude arm64 from valid iOS simulators (#73458)

dev/devicelab/bin/tasks/ios_content_validation_test.dart

@@ -182,6 +182,43 @@ Future<void> main() async {
           await flutter('clean');
         });
 
+        section('Build app for simulator with all available architectures');
+
+        // Apple Silicon ARM simulators not yet supported.
+        // Prove (on Xcode 12) Flutter knows to exclude this architecture.
+        await inDirectory(flutterProject.rootPath, () async {
+          await flutter('build', options: <String>[
+            'ios',
+            '--simulator',
+            '--no-codesign',
+            '--verbose',
+          ], environment: <String, String>{
+            'FLUTTER_XCODE_ONLY_ACTIVE_ARCH': 'NO'
+          });
+        });
+
+        final String simulatorAppFrameworkBinary = path.join(
+          flutterProject.rootPath,
+          'build',
+          'ios',
+          'iphonesimulator',
+          'Runner.app',
+          'Frameworks',
+          'App.framework',
+          'App',
+        );
+
+        final String archs = await fileType(simulatorAppFrameworkBinary);
+        if (!archs.contains('Mach-O 64-bit dynamically linked shared library x86_64')) {
+          throw TaskResult.failure('Unexpected architecture');
+        }
+
+        section('Clean build');
+
+        await inDirectory(flutterProject.rootPath, () async {
+          await flutter('clean');
+        });
+
         section('Archive');
 
         await inDirectory(flutterProject.rootPath, () async {

packages/flutter_tools/bin/podhelper.rb

@@ -68,6 +68,9 @@ def flutter_additional_ios_build_settings(target)
     # When deleted, the deployment version will inherit from the higher version derived from the 'Runner' target.
     # If the pod only supports a higher version, do not delete to correctly produce an error.
     build_configuration.build_settings.delete 'IPHONEOS_DEPLOYMENT_TARGET' if inherit_deployment_target
+
+    # Apple Silicon ARM simulators not yet supported.
+    build_configuration.build_settings['EXCLUDED_ARCHS[sdk=iphonesimulator*]'] = 'arm64 i386'
   end
 end
 

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

@@ -250,7 +250,7 @@ Future<XcodeBuildResult> buildXcodeProject({
     if (buildForDevice) {
       buildCommands.addAll(<String>['-sdk', 'iphoneos']);
     } else {
-      buildCommands.addAll(<String>['-sdk', 'iphonesimulator', '-arch', 'x86_64']);
+      buildCommands.addAll(<String>['-sdk', 'iphonesimulator']);
     }
   }
 

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

@@ -209,6 +209,9 @@ List<String> _xcodeBuildSettingsLines({
   if (useMacOSConfig) {
     // ARM not yet supported https://github.com/flutter/flutter/issues/69221
     xcodeBuildSettings.add('EXCLUDED_ARCHS=arm64');
+  } else {
+    // Apple Silicon ARM simulators not yet supported.
+    xcodeBuildSettings.add('EXCLUDED_ARCHS[sdk=iphonesimulator*]=arm64 i386');
   }
 
   for (final MapEntry<String, String> config in buildInfo.toEnvironmentConfig().entries) {

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

@@ -683,12 +683,14 @@ Information about project "Runner":
 
       final String contents = config.readAsStringSync();
       expect(contents.contains('ARCHS=armv7'), isTrue);
+      expect(contents.contains('EXCLUDED_ARCHS[sdk=iphonesimulator*]=arm64 i386'), isTrue);
 
       final File buildPhaseScript = fs.file('path/to/project/ios/Flutter/flutter_export_environment.sh');
       expect(buildPhaseScript.existsSync(), isTrue);
 
       final String buildPhaseScriptContents = buildPhaseScript.readAsStringSync();
       expect(buildPhaseScriptContents.contains('ARCHS=armv7'), isTrue);
+      expect(buildPhaseScriptContents.contains('"EXCLUDED_ARCHS[sdk=iphonesimulator*]=arm64 i386"'), isTrue);
     });
 
     testUsingOsxContext('sets TRACK_WIDGET_CREATION=true when trackWidgetCreation is true', () async {

packages/flutter_tools/test/integration.shard/build_ios_config_only_test.dart

@@ -41,10 +41,7 @@ void main() {
 
     // Config is updated if command succeeded.
     expect(generatedConfig, exists);
-    expect(generatedConfig.readAsStringSync(), allOf(
+    expect(generatedConfig.readAsStringSync(), contains('DART_OBFUSCATION=true'));
-      contains('DART_OBFUSCATION=true'),
-      isNot(contains('EXCLUDED_ARCHS')),
-    ));
 
     // file that only exists if app was fully built.
     final File frameworkPlist = fileSystem.file(