Share common logic between UnpackMacOS and UnpackIOS build targets (#168034)

`UnpackIOS` and `UnpackMacOS` have shared logic, which is currently
basically duplicate code. We also plan to add more shared logic for
SwiftPM. To simply that, this PR creates an abstract `UnpackDarwin`
class with the shared logic.

No functionality is changed other than slightly changed error logs for
`UnpackMacOS`. Code is tested by:

-
https://github.com/flutter/flutter/blob/master/packages/flutter_tools/test/general.shard/build_system/targets/ios_test.dart
-
https://github.com/flutter/flutter/blob/master/packages/flutter_tools/test/general.shard/build_system/targets/macos_test.dart

Fixes https://github.com/flutter/flutter/issues/168029.

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [x] I signed the [CLA].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [x] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [x] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel
on [Discord].

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[breaking change policy]:
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[Data Driven Fixes]:
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packages/flutter_tools/lib/src/build_system/targets/darwin.dart

@@ -4,8 +4,10 @@
 
 import 'package:meta/meta.dart';
 
+import '../../artifacts.dart';
 import '../../base/common.dart';
 import '../../base/file_system.dart';
+import '../../base/io.dart';
 import '../../build_info.dart';
 import '../../flutter_plugins.dart';
 import '../../globals.dart' as globals;
@@ -152,3 +154,106 @@ abstract class CheckDevDependencies extends Target {
     globals.stdio.stderrWrite('error: $message');
   }
 }
+
+abstract class UnpackDarwin extends Target {
+  const UnpackDarwin();
+
+  /// Copies the [framework] artifact using `rsync` to the [environment.outputDir].
+  /// Throws an error if copy fails.
+  @protected
+  Future<void> copyFramework(
+    Environment environment, {
+    EnvironmentType? environmentType,
+    TargetPlatform? targetPlatform,
+    required Artifact framework,
+    required BuildMode buildMode,
+  }) async {
+    final String basePath = environment.artifacts.getArtifactPath(
+      framework,
+      platform: targetPlatform,
+      mode: buildMode,
+      environmentType: environmentType,
+    );
+
+    final ProcessResult result = await environment.processManager.run(<String>[
+      'rsync',
+      '-av',
+      '--delete',
+      '--filter',
+      '- .DS_Store/',
+      '--chmod=Du=rwx,Dgo=rx,Fu=rw,Fgo=r',
+      basePath,
+      environment.outputDir.path,
+    ]);
+    if (result.exitCode != 0) {
+      throw Exception(
+        'Failed to copy framework (exit ${result.exitCode}:\n'
+        '${result.stdout}\n---\n${result.stderr}',
+      );
+    }
+  }
+
+  /// Verifies and destructively thins the framework binary found at [frameworkBinaryPath]
+  /// to include only the architectures specified in [archs].
+  ///
+  /// [archs] should be a space separated list passed from Xcode containing one or
+  /// more architectures (e.g. "x86_64 arm64", "arm64", "x86_64").
+  ///
+  /// Throws an error if the binary does not contain the [archs] or fails to thin.
+  @protected
+  Future<void> thinFramework(
+    Environment environment,
+    String frameworkBinaryPath,
+    String archs,
+  ) async {
+    final List<String> archList = archs.split(' ').toList();
+    final ProcessResult infoResult = await environment.processManager.run(<String>[
+      'lipo',
+      '-info',
+      frameworkBinaryPath,
+    ]);
+    final String lipoInfo = infoResult.stdout as String;
+
+    final ProcessResult verifyResult = await environment.processManager.run(<String>[
+      'lipo',
+      frameworkBinaryPath,
+      '-verify_arch',
+      ...archList,
+    ]);
+
+    if (verifyResult.exitCode != 0) {
+      throw Exception(
+        'Binary $frameworkBinaryPath does not contain architectures "$archs".\n'
+        '\n'
+        'lipo -info:\n'
+        '$lipoInfo',
+      );
+    }
+
+    // Skip thinning for non-fat executables.
+    if (lipoInfo.startsWith('Non-fat file:')) {
+      environment.logger.printTrace('Skipping lipo for non-fat file $frameworkBinaryPath');
+      return;
+    }
+
+    // Thin in-place.
+    final ProcessResult extractResult = await environment.processManager.run(<String>[
+      'lipo',
+      '-output',
+      frameworkBinaryPath,
+      for (final String arch in archList) ...<String>['-extract', arch],
+      frameworkBinaryPath,
+    ]);
+
+    if (extractResult.exitCode != 0) {
+      throw Exception(
+        'Failed to extract architectures "$archs" for $frameworkBinaryPath.\n'
+        '\n'
+        'stderr:\n'
+        '${extractResult.stderr}\n\n'
+        'lipo -info:\n'
+        '$lipoInfo',
+      );
+    }
+  }
+}

packages/flutter_tools/lib/src/build_system/targets/ios.dart

@@ -239,7 +239,7 @@ class DebugUniversalFramework extends Target {
 /// This class is abstract to share logic between the three concrete
 /// implementations. The shelling out is done to avoid complications with
 /// preserving special files (e.g., symbolic links) in the framework structure.
-abstract class UnpackIOS extends Target {
+abstract class UnpackIOS extends UnpackDarwin {
   const UnpackIOS();
 
   @override
@@ -271,7 +271,20 @@ abstract class UnpackIOS extends Target {
     if (archs == null) {
       throw MissingDefineException(kIosArchs, name);
     }
-    await _copyFramework(environment, sdkRoot);
+
+    // Copy Flutter framework.
+    final EnvironmentType? environmentType = environmentTypeFromSdkroot(
+      sdkRoot,
+      environment.fileSystem,
+    );
+    await copyFramework(
+      environment,
+      environmentType: environmentType,
+      framework: Artifact.flutterFramework,
+      targetPlatform: TargetPlatform.ios,
+      buildMode: buildMode,
+    );
+    await _copyFrameworkDysm(environment, sdkRoot: sdkRoot, environmentType: environmentType);
 
     final File frameworkBinary = environment.outputDir
         .childDirectory('Flutter.framework')
@@ -280,40 +293,15 @@ abstract class UnpackIOS extends Target {
     if (!await frameworkBinary.exists()) {
       throw Exception('Binary $frameworkBinaryPath does not exist, cannot thin');
     }
-    await _thinFramework(environment, frameworkBinaryPath, archs);
+    await thinFramework(environment, frameworkBinaryPath, archs);
     await _signFramework(environment, frameworkBinary, buildMode);
   }
 
-  Future<void> _copyFramework(Environment environment, String sdkRoot) async {
+  Future<void> _copyFrameworkDysm(
-    // Copy Flutter framework.
+    Environment environment, {
-    final EnvironmentType? environmentType = environmentTypeFromSdkroot(
+    required String sdkRoot,
-      sdkRoot,
+    EnvironmentType? environmentType,
-      environment.fileSystem,
+  }) async {
-    );
-    final String basePath = environment.artifacts.getArtifactPath(
-      Artifact.flutterFramework,
-      platform: TargetPlatform.ios,
-      mode: buildMode,
-      environmentType: environmentType,
-    );
-
-    final ProcessResult result = await environment.processManager.run(<String>[
-      'rsync',
-      '-av',
-      '--delete',
-      '--filter',
-      '- .DS_Store/',
-      '--chmod=Du=rwx,Dgo=rx,Fu=rw,Fgo=r',
-      basePath,
-      environment.outputDir.path,
-    ]);
-    if (result.exitCode != 0) {
-      throw Exception(
-        'Failed to copy framework (exit ${result.exitCode}:\n'
-        '${result.stdout}\n---\n${result.stderr}',
-      );
-    }
-
     // Copy Flutter framework dSYM (debug symbol) bundle, if present.
     final Directory frameworkDsym = environment.fileSystem.directory(
       environment.artifacts.getArtifactPath(
@@ -342,63 +330,6 @@ abstract class UnpackIOS extends Target {
       }
     }
   }
-
-  /// Destructively thin Flutter.framework to include only the specified architectures.
-  Future<void> _thinFramework(
-    Environment environment,
-    String frameworkBinaryPath,
-    String archs,
-  ) async {
-    final List<String> archList = archs.split(' ').toList();
-    final ProcessResult infoResult = await environment.processManager.run(<String>[
-      'lipo',
-      '-info',
-      frameworkBinaryPath,
-    ]);
-    final String lipoInfo = infoResult.stdout as String;
-
-    final ProcessResult verifyResult = await environment.processManager.run(<String>[
-      'lipo',
-      frameworkBinaryPath,
-      '-verify_arch',
-      ...archList,
-    ]);
-
-    if (verifyResult.exitCode != 0) {
-      throw Exception(
-        'Binary $frameworkBinaryPath does not contain architectures "$archs".\n'
-        '\n'
-        'lipo -info:\n'
-        '$lipoInfo',
-      );
-    }
-
-    // Skip thinning for non-fat executables.
-    if (lipoInfo.startsWith('Non-fat file:')) {
-      environment.logger.printTrace('Skipping lipo for non-fat file $frameworkBinaryPath');
-      return;
-    }
-
-    // Thin in-place.
-    final ProcessResult extractResult = await environment.processManager.run(<String>[
-      'lipo',
-      '-output',
-      frameworkBinaryPath,
-      for (final String arch in archList) ...<String>['-extract', arch],
-      ...<String>[frameworkBinaryPath],
-    ]);
-
-    if (extractResult.exitCode != 0) {
-      throw Exception(
-        'Failed to extract architectures "$archs" for $frameworkBinaryPath.\n'
-        '\n'
-        'stderr:\n'
-        '${extractResult.stderr}\n\n'
-        'lipo -info:\n'
-        '$lipoInfo',
-      );
-    }
-  }
 }
 
 /// Unpack the release prebuilt engine framework.

packages/flutter_tools/lib/src/build_system/targets/macos.dart

@@ -32,7 +32,7 @@ import 'native_assets.dart';
 ///   * [DebugUnpackMacOS]
 ///   * [ProfileUnpackMacOS]
 ///   * [ReleaseUnpackMacOS]
-abstract class UnpackMacOS extends Target {
+abstract class UnpackMacOS extends UnpackDarwin {
   const UnpackMacOS();
 
   @override
@@ -55,30 +55,15 @@ abstract class UnpackMacOS extends Target {
       throw MissingDefineException(kBuildMode, 'unpack_macos');
     }
 
-    // Copy Flutter framework.
+    // Copy FlutterMacOS framework.
     final BuildMode buildMode = BuildMode.fromCliName(buildModeEnvironment);
-    final String basePath = environment.artifacts.getArtifactPath(
+    await copyFramework(
-      Artifact.flutterMacOSFramework,
+      environment,
-      mode: buildMode,
+      framework: Artifact.flutterMacOSFramework,
+      buildMode: buildMode,
     );
-    final ProcessResult result = environment.processManager.runSync(<String>[
-      'rsync',
-      '-av',
-      '--delete',
-      '--filter',
-      '- .DS_Store/',
-      '--chmod=Du=rwx,Dgo=rx,Fu=rw,Fgo=r',
-      basePath,
-      environment.outputDir.path,
-    ]);
 
     _removeDenylistedFiles(environment.outputDir);
-    if (result.exitCode != 0) {
-      throw Exception(
-        'Failed to copy framework (exit ${result.exitCode}:\n'
-        '${result.stdout}\n---\n${result.stderr}',
-      );
-    }
 
     final File frameworkBinary = environment.outputDir
         .childDirectory('FlutterMacOS.framework')
@@ -90,7 +75,11 @@ abstract class UnpackMacOS extends Target {
       throw Exception('Binary $frameworkBinaryPath does not exist, cannot thin');
     }
 
-    await _thinFramework(environment, frameworkBinaryPath);
+    await thinFramework(
+      environment,
+      frameworkBinaryPath,
+      environment.defines[kDarwinArchs] ?? 'x86_64 arm64',
+    );
   }
 
   /// Files that should not be copied to build output directory if found during framework copy step.
@@ -110,51 +99,6 @@ abstract class UnpackMacOS extends Target {
       }
     }
   }
-
-  Future<void> _thinFramework(Environment environment, String frameworkBinaryPath) async {
-    final String archs = environment.defines[kDarwinArchs] ?? 'x86_64 arm64';
-    final List<String> archList = archs.split(' ').toList();
-    final ProcessResult infoResult = await environment.processManager.run(<String>[
-      'lipo',
-      '-info',
-      frameworkBinaryPath,
-    ]);
-    final String lipoInfo = infoResult.stdout as String;
-
-    final ProcessResult verifyResult = await environment.processManager.run(<String>[
-      'lipo',
-      frameworkBinaryPath,
-      '-verify_arch',
-      ...archList,
-    ]);
-
-    if (verifyResult.exitCode != 0) {
-      throw Exception(
-        'Binary $frameworkBinaryPath does not contain $archs. Running lipo -info:\n$lipoInfo',
-      );
-    }
-
-    // Skip thinning for non-fat executables.
-    if (lipoInfo.startsWith('Non-fat file:')) {
-      environment.logger.printTrace('Skipping lipo for non-fat file $frameworkBinaryPath');
-      return;
-    }
-
-    // Thin in-place.
-    final ProcessResult extractResult = environment.processManager.runSync(<String>[
-      'lipo',
-      '-output',
-      frameworkBinaryPath,
-      for (final String arch in archList) ...<String>['-extract', arch],
-      ...<String>[frameworkBinaryPath],
-    ]);
-
-    if (extractResult.exitCode != 0) {
-      throw Exception(
-        'Failed to extract $archs for $frameworkBinaryPath.\n${extractResult.stderr}\nRunning lipo -info:\n$lipoInfo',
-      );
-    }
-  }
 }
 
 /// Unpack the release prebuilt engine framework.

packages/flutter_tools/test/general.shard/build_system/targets/macos_test.dart

@@ -286,7 +286,7 @@ void main() {
             (Exception exception) => exception.toString(),
             'description',
             contains(
-              'does not contain arm64 x86_64. Running lipo -info:\nArchitectures in the fat file:',
+              'does not contain architectures "arm64 x86_64".\n\nlipo -info:\nArchitectures in the fat file:',
             ),
           ),
         ),