Force plugins to inherit minimum macOS version from Flutter app (#72764)

dev/devicelab/bin/tasks/plugin_test_ios.dart

@@ -9,5 +9,6 @@ Future<void> main() async {
   await task(combine(<TaskFunction>[
     PluginTest('ios', <String>['-i', 'objc', '--platforms=ios']),
     PluginTest('ios', <String>['-i', 'swift', '--platforms=ios']),
+    PluginTest('macos', <String>['--platforms=macos']),
   ]));
 }

dev/devicelab/lib/tasks/plugin_tests.dart

@@ -117,27 +117,31 @@ class _FlutterProject {
     });
 
     final _FlutterProject project = _FlutterProject(directory, name);
-    if (template == 'plugin' && target == 'ios') {
-      project._reduceIOSPluginMinimumVersion(name);
+    if (template == 'plugin' && (target == 'ios' || target == 'macos')) {
+      project._reduceDarwinPluginMinimumVersion(name, target);
     }
     return project;
   }
 
   // Make the platform version artificially low to test that the "deployment
   // version too low" warning is never emitted.
-  void _reduceIOSPluginMinimumVersion(String plugin) {
-    final File podspec = File(path.join(rootPath, 'ios', '$plugin.podspec'));
+  void _reduceDarwinPluginMinimumVersion(String plugin, String target) {
+    final File podspec = File(path.join(rootPath, target, '$plugin.podspec'));
     if (!podspec.existsSync()) {
       throw TaskResult.failure('podspec file missing at ${podspec.path}');
     }
-    const String versionString = "s.platform = :ios, '8.0'";
+    final String versionString = target == 'ios'
+        ? "s.platform = :ios, '8.0'"
+        : "s.platform = :osx, '10.11'";
     String podspecContent = podspec.readAsStringSync();
     if (!podspecContent.contains(versionString)) {
-      throw TaskResult.failure('Update this test to match plugin minimum iOS deployment version');
+      throw TaskResult.failure('Update this test to match plugin minimum $target deployment version');
     }
     podspecContent = podspecContent.replaceFirst(
       versionString,
-      "s.platform = :ios, '7.0'",
+      target == 'ios'
+          ? "s.platform = :ios, '7.0'"
+          : "s.platform = :osx, '10.8'"
     );
     podspec.writeAsStringSync(podspecContent, flush: true);
   }
@@ -146,14 +150,37 @@ class _FlutterProject {
     await inDirectory(Directory(rootPath), () async {
       final String buildOutput =  await evalFlutter('build', options: <String>[target, '-v']);
 
-      if (target == 'ios') {
+      if (target == 'ios' || target == 'macos') {
         // This warning is confusing and shouldn't be emitted. Plugins often support lower versions than the
         // Flutter app, but as long as they support the minimum it will work.
         // warning: The iOS deployment target 'IPHONEOS_DEPLOYMENT_TARGET' is set to 8.0,
         // but the range of supported deployment target versions is 9.0 to 14.0.99.
+        //
+        // (or "The macOS deployment target 'MACOSX_DEPLOYMENT_TARGET'"...)
         if (buildOutput.contains('the range of supported deployment target versions')) {
           throw TaskResult.failure('Minimum plugin version warning present');
         }
+
+        final File podsProject = File(path.join(rootPath, target, 'Pods', 'Pods.xcodeproj', 'project.pbxproj'));
+        if (!podsProject.existsSync()) {
+          throw TaskResult.failure('Xcode Pods project file missing at ${podsProject.path}');
+        }
+
+        final String podsProjectContent = podsProject.readAsStringSync();
+        // This may be a bit brittle, IPHONEOS_DEPLOYMENT_TARGET appears in the
+        // Pods Xcode project file 6 times. If this number changes, make sure
+        // it's not a regression in the IPHONEOS_DEPLOYMENT_TARGET override logic.
+        // The plugintest target should not have IPHONEOS_DEPLOYMENT_TARGET set.
+        // See _reduceDarwinPluginMinimumVersion for details.
+        if (target == 'ios' && 'IPHONEOS_DEPLOYMENT_TARGET'.allMatches(podsProjectContent).length != 6) {
+          throw TaskResult.failure('plugintest may contain IPHONEOS_DEPLOYMENT_TARGET');
+        }
+
+        // Same for macOS, but 12.
+        // The plugintest target should not have MACOSX_DEPLOYMENT_TARGET set.
+        if (target == 'macos' && 'MACOSX_DEPLOYMENT_TARGET'.allMatches(podsProjectContent).length != 12) {
+          throw TaskResult.failure('plugintest may contain MACOSX_DEPLOYMENT_TARGET');
+        }
       }
     });
   }

packages/flutter_tools/bin/podhelper.rb

@@ -73,9 +73,17 @@ end
 
 # Same as flutter_ios_podfile_setup for macOS.
 def flutter_additional_macos_build_settings(target)
-  print target.platform_name
   return unless target.platform_name == :osx
 
+  # [target.deployment_target] is a [String] formatted as "10.8".
+  deployment_target_major, deployment_target_minor = target.deployment_target.match(/(\d+).?(\d*)/).captures
+
+  # Suppress warning when pod supports a version lower than the minimum supported by the latest stable version of Xcode (currently 10.9).
+  # This warning is harmless but confusing--it's not a bad thing for dependencies to support a lower version.
+  inherit_deployment_target = !target.deployment_target.blank? &&
+    (deployment_target_major.to_i < 10) ||
+    (deployment_target_major.to_i == 10 && deployment_target_minor.to_i < 9)
+
   # This podhelper script is at $FLUTTER_ROOT/packages/flutter_tools/bin.
   # Add search paths from $FLUTTER_ROOT/bin/cache/artifacts/engine.
   artifacts_dir = File.join('..', '..', '..', '..', 'bin', 'cache', 'artifacts', 'engine')
@@ -89,6 +97,10 @@ def flutter_additional_macos_build_settings(target)
 
     # ARM not yet supported https://github.com/flutter/flutter/issues/69221
     build_configuration.build_settings['EXCLUDED_ARCHS'] = 'arm64'
+
+    # 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 'MACOSX_DEPLOYMENT_TARGET' if inherit_deployment_target
   end
 end