Fix Xcode 15 build failure due to DT_TOOLCHAIN_DIR (#132803)

Starting in Xcode 15, when building macOS, DT_TOOLCHAIN_DIR cannot be used to evaluate LD_RUNPATH_SEARCH_PATHS or LIBRARY_SEARCH_PATHS. `xcodebuild` error message recommend using TOOLCHAIN_DIR instead.

Since Xcode 15 isn't in CI, I tested it in a one-off `led` test:
* [Pre-fix failure](https://luci-milo.appspot.com/raw/build/logs.chromium.org/flutter/led/vashworth_google.com/04e485a0b152a0720f5e561266f7a6e4fb64fc76227fcacc95b67486ae2771e7/+/build.proto)
* [Post-fix success](https://luci-milo.appspot.com/raw/build/logs.chromium.org/flutter/led/vashworth_google.com/d454a3e181e1a97692bdc1fcc197738fe04e4acf1cb20026fd040fd78513f3b0/+/build.proto)

Fixes https://github.com/flutter/flutter/issues/132755.

packages/flutter_tools/lib/src/macos/cocoapods.dart

@@ -19,6 +19,7 @@ import '../build_info.dart';
 import '../cache.dart';
 import '../ios/xcodeproj.dart';
 import '../migrations/cocoapods_script_symlink.dart';
+import '../migrations/cocoapods_toolchain_directory_migration.dart';
 import '../reporting/reporting.dart';
 import '../xcode_project.dart';
 
@@ -172,6 +173,11 @@ class CocoaPods {
       // This migrator works around a CocoaPods bug, and should be run after `pod install` is run.
       final ProjectMigration postPodMigration = ProjectMigration(<ProjectMigrator>[
         CocoaPodsScriptReadlink(xcodeProject, _xcodeProjectInterpreter, _logger),
+        CocoaPodsToolchainDirectoryMigration(
+          xcodeProject,
+          _xcodeProjectInterpreter,
+          _logger,
+        ),
       ]);
       postPodMigration.run();
 

packages/flutter_tools/lib/src/migrations/cocoapods_toolchain_directory_migration.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 '../base/file_system.dart';
+import '../base/project_migrator.dart';
+import '../base/version.dart';
+import '../ios/xcodeproj.dart';
+import '../xcode_project.dart';
+
+/// Starting in Xcode 15, when building macOS, DT_TOOLCHAIN_DIR cannot be used
+/// to evaluate LD_RUNPATH_SEARCH_PATHS or LIBRARY_SEARCH_PATHS. `xcodebuild`
+/// error message recommend using TOOLCHAIN_DIR instead.
+///
+/// This has been fixed upstream in CocoaPods, but migrate a copy of their
+/// workaround so users don't need to update.
+class CocoaPodsToolchainDirectoryMigration extends ProjectMigrator {
+  CocoaPodsToolchainDirectoryMigration(
+    XcodeBasedProject project,
+    XcodeProjectInterpreter xcodeProjectInterpreter,
+    super.logger,
+  )   : _podRunnerTargetSupportFiles = project.podRunnerTargetSupportFiles,
+        _xcodeProjectInterpreter = xcodeProjectInterpreter;
+
+  final Directory _podRunnerTargetSupportFiles;
+  final XcodeProjectInterpreter _xcodeProjectInterpreter;
+
+  @override
+  void migrate() {
+    if (!_podRunnerTargetSupportFiles.existsSync()) {
+      logger.printTrace('CocoaPods Pods-Runner Target Support Files not found, skipping TOOLCHAIN_DIR workaround.');
+      return;
+    }
+
+    final Version? version = _xcodeProjectInterpreter.version;
+
+    // If Xcode not installed or less than 15, skip this migration.
+    if (version == null || version < Version(15, 0, 0)) {
+      logger.printTrace('Detected Xcode version is $version, below 15.0, skipping TOOLCHAIN_DIR workaround.');
+      return;
+    }
+
+    final List<FileSystemEntity> files = _podRunnerTargetSupportFiles.listSync();
+    for (final FileSystemEntity file in files) {
+      if (file.basename.endsWith('xcconfig') && file is File) {
+        processFileLines(file);
+      }
+    }
+  }
+
+  @override
+  String? migrateLine(String line) {
+    final String trimmedString = line.trim();
+    if (trimmedString.startsWith('LD_RUNPATH_SEARCH_PATHS') || trimmedString.startsWith('LIBRARY_SEARCH_PATHS')) {
+      const String originalReadLinkLine = r'{DT_TOOLCHAIN_DIR}';
+      const String replacementReadLinkLine = r'{TOOLCHAIN_DIR}';
+
+      return line.replaceAll(originalReadLinkLine, replacementReadLinkLine);
+    }
+    return line;
+  }
+}

packages/flutter_tools/lib/src/xcode_project.dart

@@ -104,11 +104,14 @@ abstract class XcodeBasedProject extends FlutterProjectPlatform  {
   File get podManifestLock => hostAppRoot.childDirectory('Pods').childFile('Manifest.lock');
 
   /// The CocoaPods generated 'Pods-Runner-frameworks.sh'.
-  File get podRunnerFrameworksScript => hostAppRoot
+  File get podRunnerFrameworksScript => podRunnerTargetSupportFiles
+      .childFile('Pods-Runner-frameworks.sh');
+
+  /// The CocoaPods generated directory 'Pods-Runner'.
+  Directory get podRunnerTargetSupportFiles => hostAppRoot
       .childDirectory('Pods')
       .childDirectory('Target Support Files')
-      .childDirectory('Pods-Runner')
-      .childFile('Pods-Runner-frameworks.sh');
+      .childDirectory('Pods-Runner');
 }
 
 /// Represents the iOS sub-project of a Flutter project.

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

@@ -16,6 +16,7 @@ import 'package:flutter_tools/src/ios/migrations/remove_framework_link_and_embed
 import 'package:flutter_tools/src/ios/migrations/xcode_build_system_migration.dart';
 import 'package:flutter_tools/src/ios/xcodeproj.dart';
 import 'package:flutter_tools/src/migrations/cocoapods_script_symlink.dart';
+import 'package:flutter_tools/src/migrations/cocoapods_toolchain_directory_migration.dart';
 import 'package:flutter_tools/src/migrations/xcode_project_object_version_migration.dart';
 import 'package:flutter_tools/src/migrations/xcode_script_build_phase_migration.dart';
 import 'package:flutter_tools/src/migrations/xcode_thin_binary_build_phase_input_paths_migration.dart';
@@ -1003,6 +1004,150 @@ platform :ios, '11.0'
         expect(testLogger.statusText, contains('Upgrading Pods-Runner-frameworks.sh'));
       });
     });
+
+    group('Cocoapods migrate toolchain directory', () {
+      late MemoryFileSystem memoryFileSystem;
+      late BufferLogger testLogger;
+      late FakeIosProject project;
+      late Directory podRunnerTargetSupportFiles;
+      late ProcessManager processManager;
+      late XcodeProjectInterpreter xcode15ProjectInterpreter;
+
+      setUp(() {
+        memoryFileSystem = MemoryFileSystem();
+        podRunnerTargetSupportFiles = memoryFileSystem.directory('Pods-Runner');
+        testLogger = BufferLogger.test();
+        project = FakeIosProject();
+        processManager = FakeProcessManager.any();
+        xcode15ProjectInterpreter = XcodeProjectInterpreter.test(processManager: processManager, version: Version(15, 0, 0));
+        project.podRunnerTargetSupportFiles = podRunnerTargetSupportFiles;
+      });
+
+      testWithoutContext('skip if directory is missing', () {
+        final CocoaPodsToolchainDirectoryMigration iosProjectMigration = CocoaPodsToolchainDirectoryMigration(
+          project,
+          xcode15ProjectInterpreter,
+          testLogger,
+        );
+        iosProjectMigration.migrate();
+        expect(podRunnerTargetSupportFiles.existsSync(), isFalse);
+
+        expect(testLogger.traceText, contains('CocoaPods Pods-Runner Target Support Files not found'));
+        expect(testLogger.statusText, isEmpty);
+      });
+
+      testWithoutContext('skip if xcconfig files are missing', () {
+        podRunnerTargetSupportFiles.createSync();
+        final CocoaPodsToolchainDirectoryMigration iosProjectMigration = CocoaPodsToolchainDirectoryMigration(
+          project,
+          xcode15ProjectInterpreter,
+          testLogger,
+        );
+        iosProjectMigration.migrate();
+        expect(podRunnerTargetSupportFiles.existsSync(), isTrue);
+        expect(testLogger.traceText, isEmpty);
+        expect(testLogger.statusText, isEmpty);
+      });
+
+      testWithoutContext('skip if nothing to upgrade', () {
+        podRunnerTargetSupportFiles.createSync();
+        final File debugConfig = podRunnerTargetSupportFiles.childFile('Pods-Runner.debug.xcconfig');
+        const String contents = r'''
+LD_RUNPATH_SEARCH_PATHS = $(inherited) /usr/lib/swift '@executable_path/../Frameworks' '@loader_path/Frameworks' "${TOOLCHAIN_DIR}/usr/lib/swift/${PLATFORM_NAME}"
+LIBRARY_SEARCH_PATHS = $(inherited) "${TOOLCHAIN_DIR}/usr/lib/swift/${PLATFORM_NAME}" /usr/lib/swift
+''';
+        debugConfig.writeAsStringSync(contents);
+
+        final File profileConfig = podRunnerTargetSupportFiles.childFile('Pods-Runner.profile.xcconfig');
+        profileConfig.writeAsStringSync(contents);
+
+        final File releaseConfig = podRunnerTargetSupportFiles.childFile('Pods-Runner.release.xcconfig');
+        releaseConfig.writeAsStringSync(contents);
+
+        final CocoaPodsToolchainDirectoryMigration iosProjectMigration = CocoaPodsToolchainDirectoryMigration(
+          project,
+          xcode15ProjectInterpreter,
+          testLogger,
+        );
+        iosProjectMigration.migrate();
+        expect(debugConfig.existsSync(), isTrue);
+        expect(testLogger.traceText, isEmpty);
+        expect(testLogger.statusText, isEmpty);
+      });
+
+      testWithoutContext('skipped if Xcode version below 15', () {
+        podRunnerTargetSupportFiles.createSync();
+        final File debugConfig = podRunnerTargetSupportFiles.childFile('Pods-Runner.debug.xcconfig');
+        const String contents = r'''
+LD_RUNPATH_SEARCH_PATHS = $(inherited) /usr/lib/swift '@executable_path/../Frameworks' '@loader_path/Frameworks' "${DT_TOOLCHAIN_DIR}/usr/lib/swift/${PLATFORM_NAME}"
+LIBRARY_SEARCH_PATHS = $(inherited) "${DT_TOOLCHAIN_DIR}/usr/lib/swift/${PLATFORM_NAME}" /usr/lib/swift
+''';
+        debugConfig.writeAsStringSync(contents);
+
+        final File profileConfig = podRunnerTargetSupportFiles.childFile('Pods-Runner.profile.xcconfig');
+        profileConfig.writeAsStringSync(contents);
+
+        final File releaseConfig = podRunnerTargetSupportFiles.childFile('Pods-Runner.release.xcconfig');
+        releaseConfig.writeAsStringSync(contents);
+
+        final XcodeProjectInterpreter xcode14ProjectInterpreter = XcodeProjectInterpreter.test(
+          processManager: processManager,
+          version: Version(14, 0, 0),
+        );
+
+        final CocoaPodsToolchainDirectoryMigration iosProjectMigration = CocoaPodsToolchainDirectoryMigration(
+          project,
+          xcode14ProjectInterpreter,
+          testLogger,
+        );
+        iosProjectMigration.migrate();
+        expect(debugConfig.existsSync(), isTrue);
+        expect(testLogger.traceText, contains('Detected Xcode version is 14.0.0, below 15.0'));
+        expect(testLogger.statusText, isEmpty);
+      });
+
+      testWithoutContext('Xcode project is migrated and ignores leading whitespace', () {
+        podRunnerTargetSupportFiles.createSync();
+        final File debugConfig = podRunnerTargetSupportFiles.childFile('Pods-Runner.debug.xcconfig');
+        const String contents = r'''
+LD_RUNPATH_SEARCH_PATHS = $(inherited) /usr/lib/swift '@executable_path/../Frameworks' '@loader_path/Frameworks' "${DT_TOOLCHAIN_DIR}/usr/lib/swift/${PLATFORM_NAME}"
+  LIBRARY_SEARCH_PATHS = $(inherited) "${DT_TOOLCHAIN_DIR}/usr/lib/swift/${PLATFORM_NAME}" /usr/lib/swift
+''';
+        debugConfig.writeAsStringSync(contents);
+
+        final File profileConfig = podRunnerTargetSupportFiles.childFile('Pods-Runner.profile.xcconfig');
+        profileConfig.writeAsStringSync(contents);
+
+        final File releaseConfig = podRunnerTargetSupportFiles.childFile('Pods-Runner.release.xcconfig');
+        releaseConfig.writeAsStringSync(contents);
+
+        final CocoaPodsToolchainDirectoryMigration iosProjectMigration = CocoaPodsToolchainDirectoryMigration(
+          project,
+          xcode15ProjectInterpreter,
+          testLogger,
+        );
+        iosProjectMigration.migrate();
+
+        expect(debugConfig.existsSync(), isTrue);
+        expect(debugConfig.readAsStringSync(), r'''
+LD_RUNPATH_SEARCH_PATHS = $(inherited) /usr/lib/swift '@executable_path/../Frameworks' '@loader_path/Frameworks' "${TOOLCHAIN_DIR}/usr/lib/swift/${PLATFORM_NAME}"
+  LIBRARY_SEARCH_PATHS = $(inherited) "${TOOLCHAIN_DIR}/usr/lib/swift/${PLATFORM_NAME}" /usr/lib/swift
+''');
+        expect(profileConfig.existsSync(), isTrue);
+        expect(profileConfig.readAsStringSync(), r'''
+LD_RUNPATH_SEARCH_PATHS = $(inherited) /usr/lib/swift '@executable_path/../Frameworks' '@loader_path/Frameworks' "${TOOLCHAIN_DIR}/usr/lib/swift/${PLATFORM_NAME}"
+  LIBRARY_SEARCH_PATHS = $(inherited) "${TOOLCHAIN_DIR}/usr/lib/swift/${PLATFORM_NAME}" /usr/lib/swift
+''');
+        expect(releaseConfig.existsSync(), isTrue);
+        expect(releaseConfig.readAsStringSync(), r'''
+LD_RUNPATH_SEARCH_PATHS = $(inherited) /usr/lib/swift '@executable_path/../Frameworks' '@loader_path/Frameworks' "${TOOLCHAIN_DIR}/usr/lib/swift/${PLATFORM_NAME}"
+  LIBRARY_SEARCH_PATHS = $(inherited) "${TOOLCHAIN_DIR}/usr/lib/swift/${PLATFORM_NAME}" /usr/lib/swift
+''');
+        expect(testLogger.statusText, contains('Upgrading Pods-Runner.debug.xcconfig'));
+        expect(testLogger.statusText, contains('Upgrading Pods-Runner.profile.xcconfig'));
+        expect(testLogger.statusText, contains('Upgrading Pods-Runner.release.xcconfig'));
+      });
+    });
   });
 
   group('update Xcode script build phase', () {
@@ -1239,6 +1384,9 @@ class FakeIosProject extends Fake implements IosProject {
 
   @override
   File podRunnerFrameworksScript = MemoryFileSystem.test().file('podRunnerFrameworksScript');
+
+  @override
+  Directory podRunnerTargetSupportFiles = MemoryFileSystem.test().directory('Pods-Runner');
 }
 
 class FakeIOSMigrator extends ProjectMigrator {