[flutter_tools] add --config-only option to flutter build ios (#64848)

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

@@ -40,6 +40,11 @@ class BuildIOSCommand extends BuildSubCommand {
     addNullSafetyModeOptions(hide: !verboseHelp);
     usesAnalyzeSizeFlag();
     argParser
+      ..addFlag('config-only',
+        help: 'Update the project configuration without performing a build. '
+          'This can be used in CI/CD process that create an archive to avoid '
+          'performing duplicate work.'
+      )
       ..addFlag('simulator',
         help: 'Build for the iOS simulator instead of the device. This changes '
           'the default build mode to debug if otherwise unspecified.',
@@ -64,13 +69,27 @@ class BuildIOSCommand extends BuildSubCommand {
   @override
   Future<FlutterCommandResult> runCommand() async {
     final bool forSimulator = boolArg('simulator');
+    final bool configOnly = boolArg('config-only');
+    final bool shouldCodesign = boolArg('codesign');
     defaultBuildMode = forSimulator ? BuildMode.debug : BuildMode.release;
+    final BuildInfo buildInfo = getBuildInfo();
 
     if (!globals.platform.isMacOS) {
-      throwToolExit('Building for iOS is only supported on the Mac.');
+      throwToolExit('Building for iOS is only supported on macOS.');
+    }
+    if (forSimulator && !buildInfo.supportsSimulator) {
+      throwToolExit('${toTitleCase(buildInfo.friendlyModeName)} mode is not supported for simulators.');
+    }
+    if (configOnly && buildInfo.codeSizeDirectory != null) {
+      throwToolExit('Cannot analyze code size without performing a full build.');
+    }
+    if (!forSimulator && !shouldCodesign) {
+      globals.printStatus(
+        'Warning: Building for device with codesigning disabled. You will '
+        'have to manually codesign before deploying to device.',
+      );
     }
 
-    final BuildInfo buildInfo = getBuildInfo();
     final BuildableIOSApp app = await applicationPackages.getPackageForPlatform(
       TargetPlatform.ios,
       buildInfo,
@@ -80,18 +99,7 @@ class BuildIOSCommand extends BuildSubCommand {
       throwToolExit('Application not configured for iOS');
     }
 
-    final bool shouldCodesign = boolArg('codesign');
-
-    if (!forSimulator && !shouldCodesign) {
-      globals.printStatus('Warning: Building for device with codesigning disabled. You will '
-        'have to manually codesign before deploying to device.');
-    }
-    if (forSimulator && !buildInfo.supportsSimulator) {
-      throwToolExit('${toTitleCase(buildInfo.friendlyModeName)} mode is not supported for simulators.');
-    }
-
     final String logTarget = forSimulator ? 'simulator' : 'device';
-
     final String typeName = globals.artifacts.getEngineType(TargetPlatform.ios, buildInfo.mode);
     globals.printStatus('Building $app for $logTarget ($typeName)...');
     final XcodeBuildResult result = await buildXcodeProject(
@@ -100,6 +108,7 @@ class BuildIOSCommand extends BuildSubCommand {
       targetOverride: targetFile,
       buildForDevice: !forSimulator,
       codesign: shouldCodesign,
+      configOnly: configOnly,
     );
 
     if (!result.success) {

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

@@ -97,6 +97,7 @@ Future<XcodeBuildResult> buildXcodeProject({
   DarwinArch activeArch,
   bool codesign = true,
   String deviceID,
+  bool configOnly = false,
 }) async {
   if (!upgradePbxProjWithFlutterAssets(app.project, globals.logger)) {
     return XcodeBuildResult(success: false);
@@ -187,6 +188,9 @@ Future<XcodeBuildResult> buildXcodeProject({
     buildInfo: buildInfo,
   );
   await processPodsIfNeeded(project.ios, getIosBuildDirectory(), buildInfo.mode);
+  if (configOnly) {
+    return XcodeBuildResult(success: true);
+  }
 
   final List<String> buildCommands = <String>[
     '/usr/bin/env',

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

+// 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 'package:file_testing/file_testing.dart';
+import 'package:flutter_tools/src/base/file_system.dart';
+import 'package:flutter_tools/src/base/io.dart';
+import 'package:flutter_tools/src/base/platform.dart';
+import 'package:process/process.dart';
+import 'package:flutter_tools/src/globals.dart' as globals;
+
+import '../src/common.dart';
+
+void main() {
+  test('flutter build ios --config only updates generated xcconfig file without performing build', () async {
+    final String woringDirectory = globals.fs.path.join(getFlutterRoot(), 'examples', 'hello_world');
+    final String flutterBin = globals.fs.path.join(getFlutterRoot(), 'bin', 'flutter');
+
+    await const LocalProcessManager().run(<String>[
+      flutterBin,
+      'clean',
+    ], workingDirectory: woringDirectory);
+    final ProcessResult result = await const LocalProcessManager().run(<String>[
+      flutterBin,
+      'build',
+      'ios',
+      '--config-only',
+      '--release',
+      '--obfuscate',
+      '--split-debug-info=info',
+      '--no-codesign',
+    ], workingDirectory: woringDirectory);
+
+    print(result.stdout);
+    print(result.stderr);
+
+    expect(result.exitCode, 0);
+
+    final File generatedConfig = globals.fs.file(
+      globals.fs.path.join(woringDirectory, 'ios', 'Flutter', 'Generated.xcconfig'));
+
+    // Config is updated if command succeeded.
+    expect(generatedConfig, exists);
+    expect(generatedConfig.readAsStringSync(), allOf(
+      contains('DART_OBFUSCATION=true'),
+      contains('FLUTTER_FRAMEWORK_DIR=${globals.fs.path.absolute(getFlutterRoot(), 'bin', 'cache', 'artifacts', 'engine')}'),
+    ));
+
+    // file that only exists if app was fully built.
+    final File frameworkPlist = globals.fs.file(
+      globals.fs.path.join(woringDirectory, 'build', 'ios', 'iphoneos', 'Runner.app', 'AppFrameworkInfo.plist'));
+
+    expect(frameworkPlist, isNot(exists));
+  },skip: !const LocalPlatform().isMacOS);
+}