Add deprecation notice for Android x86 when building for the target (#159750)

Related to https://github.com/flutter/flutter/issues/157543

packages/flutter_tools/lib/src/android/gradle.dart

@@ -122,6 +122,11 @@ String getAarTaskFor(BuildInfo buildInfo) {
   return _taskFor('assembleAar', buildInfo);
 }
 
+@visibleForTesting
+const String androidX86DeprecationWarning =
+  'Support for Android x86 targets will be removed in the next stable release after 3.27. '
+  'See https://github.com/flutter/flutter/issues/157543 for details.';
+
 /// Returns the output APK file names for a given [AndroidBuildInfo].
 ///
 /// For example, when [splitPerAbi] is true, multiple APKs are created.
@@ -188,6 +193,13 @@ class AndroidGradleBuilder implements AndroidBuilder {
       // Module projects artifacts are located in `build/host`.
       outputDirectory = outputDirectory.childDirectory('host');
     }
+
+    final bool containsX86Targets = androidBuildInfo.where(
+      (AndroidBuildInfo info) => info.containsX86Target,
+    ).isNotEmpty;
+    if (containsX86Targets) {
+      _logger.printWarning(androidX86DeprecationWarning);
+    }
     for (final AndroidBuildInfo androidBuildInfo in androidBuildInfo) {
       await buildGradleAar(
         project: project,
@@ -300,6 +312,9 @@ class AndroidGradleBuilder implements AndroidBuilder {
     int retry = 0,
     @visibleForTesting int? maxRetries,
   }) async {
+    if (androidBuildInfo.containsX86Target) {
+      _logger.printWarning(androidX86DeprecationWarning);
+    }
     if (!project.android.isSupportedVersion) {
       _exitWithUnsupportedProjectMessage(_logger.terminal, _analytics);
     }

packages/flutter_tools/lib/src/build_info.dart

@@ -396,6 +396,8 @@ class AndroidBuildInfo {
   /// The target platforms for the build.
   final Iterable<AndroidArch> targetArchs;
 
+  bool get containsX86Target => targetArchs.contains(AndroidArch.x86);
+
   /// Whether to bootstrap an empty application.
   final bool fastStart;
 }

packages/flutter_tools/test/general.shard/android/android_gradle_builder_test.dart

@@ -811,6 +811,85 @@ void main() {
       AndroidStudio: () => FakeAndroidStudio(),
     });
 
+    testUsingContext('prints deprecation warning when building for x86', () async {
+      // See https://github.com/flutter/flutter/issues/157543 for details.
+      final AndroidGradleBuilder builder = AndroidGradleBuilder(
+        java: FakeJava(),
+        logger: logger,
+        processManager: processManager,
+        fileSystem: fileSystem,
+        artifacts: Artifacts.test(),
+        analytics: fakeAnalytics,
+        gradleUtils: FakeGradleUtils(),
+        platform: FakePlatform(),
+        androidStudio: FakeAndroidStudio(),
+      );
+      processManager.addCommand(const FakeCommand(
+        command: <String>[
+          'gradlew',
+          '-q',
+          '-Ptarget-platform=android-x86',
+          '-Ptarget=lib/main.dart',
+          '-Pbase-application-name=android.app.Application',
+          '-Pdart-obfuscation=false',
+          '-Ptrack-widget-creation=false',
+          '-Ptree-shake-icons=false',
+          'assembleRelease',
+        ],
+      ));
+      fileSystem.directory('android')
+        .childFile('build.gradle')
+        .createSync(recursive: true);
+
+      fileSystem.directory('android')
+        .childFile('gradle.properties')
+        .createSync(recursive: true);
+
+      fileSystem.directory('android')
+        .childDirectory('app')
+        .childFile('build.gradle')
+        ..createSync(recursive: true)
+        ..writeAsStringSync('apply from: irrelevant/flutter.gradle');
+
+      fileSystem.directory('build')
+        .childDirectory('app')
+        .childDirectory('outputs')
+        .childDirectory('flutter-apk')
+        .childFile('app-release.apk')
+        .createSync(recursive: true);
+
+      final FlutterProject project = FlutterProject.fromDirectoryTest(fileSystem.currentDirectory);
+      project.android.appManifestFile
+        ..createSync(recursive: true)
+        ..writeAsStringSync(minimalV2EmbeddingManifest);
+
+      await builder.buildGradleApp(
+        project: project,
+        androidBuildInfo: const AndroidBuildInfo(
+          BuildInfo(
+            BuildMode.release,
+            null,
+            treeShakeIcons: false,
+            packageConfigPath: '.dart_tool/package_config.json',
+          ),
+          targetArchs: <AndroidArch>[AndroidArch.x86],
+        ),
+        target: 'lib/main.dart',
+        isBuildingBundle: false,
+        configOnly: false,
+        localGradleErrors: const <GradleHandledError>[],
+      );
+
+      expect(
+        logger.statusText,
+        contains('Built build/app/outputs/flutter-apk/app-release.apk (0.0MB)'),
+      );
+      expect(logger.warningText, contains(androidX86DeprecationWarning));
+      expect(processManager, hasNoRemainingExpectations);
+    }, overrides: <Type, Generator>{
+      AndroidStudio: () => FakeAndroidStudio(),
+    });
+
     testUsingContext('Uses namespace attribute if manifest lacks a package attribute', () async {
       final FlutterProject project = FlutterProject.fromDirectoryTest(fileSystem.currentDirectory);
       final AndroidSdk sdk = FakeAndroidSdk();