Detect ARM macOS arch with sysctl hw.optional.arm64 (#67970)

packages/flutter_tools/lib/src/application_package.dart

@@ -328,7 +328,7 @@ abstract class IOSApp extends ApplicationPackage {
   }
 
   static Future<IOSApp> fromIosProject(IosProject project, BuildInfo buildInfo) {
-    if (getCurrentHostPlatform() != HostPlatform.darwin_x64) {
+    if (!globals.platform.isMacOS) {
       return null;
     }
     if (!project.exists) {

packages/flutter_tools/lib/src/base/os.dart

@@ -7,6 +7,7 @@ import 'package:file/file.dart';
 import 'package:meta/meta.dart';
 import 'package:process/process.dart';
 
+import '../build_info.dart';
 import '../globals.dart' as globals;
 import 'common.dart';
 import 'file_system.dart';
@@ -29,6 +30,13 @@ abstract class OperatingSystemUtils {
         platform: platform,
         processManager: processManager,
       );
+    } else if (platform.isMacOS) {
+      return _MacOSUtils(
+        fileSystem: fileSystem,
+        logger: logger,
+        platform: platform,
+        processManager: processManager,
+      );
     } else {
       return _PosixUtils(
         fileSystem: fileSystem,
@@ -112,6 +120,8 @@ abstract class OperatingSystemUtils {
     return osNames.containsKey(osName) ? osNames[osName] : osName;
   }
 
+  HostPlatform get hostPlatform;
+
   List<File> _which(String execName, { bool all = false });
 
   /// Returns the separator between items in the PATH environment variable.
@@ -246,30 +256,63 @@ class _PosixUtils extends OperatingSystemUtils {
     return _fileSystem.file(path);
   }
 
+  @override
+  String get pathVarSeparator => ':';
+
+  @override
+  HostPlatform hostPlatform = HostPlatform.linux_x64;
+}
+
+class _MacOSUtils extends _PosixUtils {
+  _MacOSUtils({
+    @required FileSystem fileSystem,
+    @required Logger logger,
+    @required Platform platform,
+    @required ProcessManager processManager,
+  }) : super(
+          fileSystem: fileSystem,
+          logger: logger,
+          platform: platform,
+          processManager: processManager,
+        );
+
   String _name;
 
   @override
   String get name {
     if (_name == null) {
-      if (_platform.isMacOS) {
       final List<RunResult> results = <RunResult>[
         _processUtils.runSync(<String>['sw_vers', '-productName']),
         _processUtils.runSync(<String>['sw_vers', '-productVersion']),
         _processUtils.runSync(<String>['sw_vers', '-buildVersion']),
-          _processUtils.runSync(<String>['uname', '-m']),
       ];
       if (results.every((RunResult result) => result.exitCode == 0)) {
-          _name = '${results[0].stdout.trim()} ${results[1].stdout
-              .trim()} ${results[2].stdout.trim()} ${results[3].stdout.trim()}';
-        }
+        _name =
+            '${results[0].stdout.trim()} ${results[1].stdout.trim()} ${results[2].stdout.trim()} ${getNameForHostPlatform(hostPlatform)}';
       }
       _name ??= super.name;
     }
     return _name;
   }
 
+  HostPlatform _hostPlatform;
+
+  // On ARM returns arm64, even when this process is running in Rosetta.
   @override
-  String get pathVarSeparator => ':';
+  HostPlatform get hostPlatform {
+    if (_hostPlatform == null) {
+      final RunResult arm64Check =
+          _processUtils.runSync(<String>['sysctl', 'hw.optional.arm64']);
+      // hw.optional.arm64 is unavailable on < macOS 11 and exits with 1, assume x86 on failure.
+      // On arm64 stdout is "sysctl hw.optional.arm64: 1"
+      if (arm64Check.exitCode == 0 && arm64Check.stdout.trim().endsWith('1')) {
+        _hostPlatform = HostPlatform.darwin_arm;
+      } else {
+        _hostPlatform = HostPlatform.darwin_x64;
+      }
+    }
+    return _hostPlatform;
+  }
 }
 
 class _WindowsUtils extends OperatingSystemUtils {
@@ -285,6 +328,9 @@ class _WindowsUtils extends OperatingSystemUtils {
     processManager: processManager,
   );
 
+  @override
+  HostPlatform hostPlatform = HostPlatform.windows_x64;
+
   @override
   void makeExecutable(File file) {}
 

packages/flutter_tools/lib/src/build_info.dart

@@ -398,6 +398,7 @@ bool isEmulatorBuildMode(BuildMode mode) {
 
 enum HostPlatform {
   darwin_x64,
+  darwin_arm,
   linux_x64,
   windows_x64,
 }
@@ -406,6 +407,8 @@ String getNameForHostPlatform(HostPlatform platform) {
   switch (platform) {
     case HostPlatform.darwin_x64:
       return 'darwin-x64';
+    case HostPlatform.darwin_arm:
+      return 'darwin-arm';
     case HostPlatform.linux_x64:
       return 'linux-x64';
     case HostPlatform.windows_x64:
@@ -418,6 +421,7 @@ String getNameForHostPlatform(HostPlatform platform) {
 enum TargetPlatform {
   android,
   ios,
+  // darwin_arm64 not yet supported, macOS desktop targets run in Rosetta as x86.
   darwin_x64,
   linux_x64,
   windows_x64,

packages/flutter_tools/test/src/context.dart

@@ -17,6 +17,7 @@ import 'package:flutter_tools/src/base/signals.dart';
 import 'package:flutter_tools/src/base/template.dart';
 import 'package:flutter_tools/src/base/terminal.dart';
 import 'package:flutter_tools/src/base/time.dart';
+import 'package:flutter_tools/src/build_info.dart';
 import 'package:flutter_tools/src/isolated/mustache_template.dart';
 import 'package:flutter_tools/src/cache.dart';
 import 'package:flutter_tools/src/context_runner.dart';
@@ -294,6 +295,9 @@ class FakeOperatingSystemUtils implements OperatingSystemUtils {
   @override
   ProcessResult makeExecutable(File file) => null;
 
+  @override
+  HostPlatform hostPlatform = HostPlatform.linux_x64;
+
   @override
   void chmod(FileSystemEntity entity, String mode) { }