[tool] Move Android lint checks

packages/pigeon/platform_tests/alternate_language_test_plugin/android/build.gradle

@@ -57,7 +57,3 @@ android {
         testImplementation "org.mockito:mockito-core:5.1.1"
     }
 }
-
-project.getTasks().withType(JavaCompile){
-    options.compilerArgs.addAll(["-Xlint:all", "-Werror"])
-}

packages/pigeon/platform_tests/alternate_language_test_plugin/example/android/build.gradle

@@ -29,3 +29,11 @@ subprojects {
 task clean(type: Delete) {
     delete rootProject.buildDir
 }
+
+gradle.projectsEvaluated {
+    project(":alternate_language_test_plugin") {
+        tasks.withType(JavaCompile) {
+            options.compilerArgs << "-Xlint:all" << "-Werror"
+        }
+    }
+}

packages/pigeon/platform_tests/test_plugin/android/build.gradle

@@ -58,6 +58,12 @@ android {
         }
     }
 
+    lintOptions {
+        checkAllWarnings true
+        warningsAsErrors true
+        disable 'AndroidGradlePluginVersion', 'InvalidPackage', 'GradleDependency'
+    }
+
     dependencies {
         testImplementation 'junit:junit:4.+'
         testImplementation "io.mockk:mockk:1.13.5"

packages/pigeon/platform_tests/test_plugin/example/android/build.gradle

@@ -29,3 +29,11 @@ subprojects {
 task clean(type: Delete) {
     delete rootProject.buildDir
 }
+
+gradle.projectsEvaluated {
+    project(":test_plugin") {
+        tasks.withType(JavaCompile) {
+            options.compilerArgs << "-Xlint:all" << "-Werror"
+        }
+    }
+}

script/tool/lib/src/common/repository_package.dart

@@ -151,4 +151,19 @@ class RepositoryPackage {
         .map((FileSystemEntity entity) =>
             RepositoryPackage(entity as Directory));
   }
+
+  /// Returns the package that this package is a part of, if any.
+  ///
+  /// Currently this is limited to checking up two directories, since that
+  /// covers all the example structures currently used.
+  RepositoryPackage? getEnclosingPackage() {
+    final Directory parent = directory.parent;
+    if (isPackage(parent)) {
+      return RepositoryPackage(parent);
+    }
+    if (isPackage(parent.parent)) {
+      return RepositoryPackage(parent.parent);
+    }
+    return null;
+  }
 }

script/tool/lib/src/gradle_check_command.dart

@@ -6,6 +6,7 @@ import 'package:file/file.dart';
 
 import 'common/core.dart';
 import 'common/package_looping_command.dart';
+import 'common/plugin_utils.dart';
 import 'common/repository_package.dart';
 
 /// A command to enforce gradle file conventions and best practices.
@@ -84,6 +85,8 @@ class GradleCheckCommand extends PackageLoopingCommand {
         .childFile('AndroidManifest.xml');
   }
 
+  bool _isCommented(String line) => line.trim().startsWith('//');
+
   /// Validates the build.gradle file for a plugin
   /// (some_plugin/android/build.gradle).
   bool _validatePluginBuildGradle(RepositoryPackage package, File gradleFile) {
@@ -101,6 +104,9 @@ class GradleCheckCommand extends PackageLoopingCommand {
     if (!_validateSourceCompatibilityVersion(lines)) {
       succeeded = false;
     }
+    if (!_validateGradleDrivenLintConfig(package, lines)) {
+      succeeded = false;
+    }
     return succeeded;
   }
 
@@ -110,9 +116,16 @@ class GradleCheckCommand extends PackageLoopingCommand {
       RepositoryPackage package, File gradleFile) {
     print('${indentation}Validating '
         '${getRelativePosixPath(gradleFile, from: package.directory)}.');
-    // TODO(stuartmorgan): Move the -Xlint validation from lint_android_command
-    // to here.
-    return true;
+    final String contents = gradleFile.readAsStringSync();
+    final List<String> lines = contents.split('\n');
+
+    // This is tracked as a variable rather than a sequence of &&s so that all
+    // failures are reported at once, not just the first one.
+    bool succeeded = true;
+    if (!_validateJavacLintConfig(package, lines)) {
+      succeeded = false;
+    }
+    return succeeded;
   }
 
   /// Validates the app-level build.gradle for an example app (e.g.,
@@ -193,11 +206,9 @@ build.gradle "namespace" must match the "package" attribute in AndroidManifest.x
   /// lead to compile errors that show up for clients, but not in CI).
   bool _validateSourceCompatibilityVersion(List<String> gradleLines) {
     if (!gradleLines.any((String line) =>
-            line.contains('languageVersion') &&
-            !line.trim().startsWith('//')) &&
+            line.contains('languageVersion') && !_isCommented(line)) &&
         !gradleLines.any((String line) =>
-            line.contains('sourceCompatibility') &&
-            !line.trim().startsWith('//'))) {
+            line.contains('sourceCompatibility') && !_isCommented(line))) {
       const String errorMessage = '''
 build.gradle must set an explicit Java compatibility version.
 
@@ -225,4 +236,75 @@ for more details.''';
     }
     return true;
   }
+
+  /// Returns whether the given gradle content is configured to enable all
+  /// Gradle-driven lints (those checked by ./gradlew lint) and treat them as
+  /// errors.
+  bool _validateGradleDrivenLintConfig(
+      RepositoryPackage package, List<String> gradleLines) {
+    final List<String> gradleBuildContents = package
+        .platformDirectory(FlutterPlatform.android)
+        .childFile('build.gradle')
+        .readAsLinesSync();
+    if (!gradleBuildContents.any((String line) =>
+            line.contains('checkAllWarnings true') && !_isCommented(line)) ||
+        !gradleBuildContents.any((String line) =>
+            line.contains('warningsAsErrors true') && !_isCommented(line))) {
+      printError('${indentation}This package is not configured to enable all '
+          'Gradle-driven lint warnings and treat them as errors. '
+          'Please add the following to the lintOptions section of '
+          'android/build.gradle:');
+      print('''
+        checkAllWarnings true
+        warningsAsErrors true
+''');
+      return false;
+    }
+    return true;
+  }
+
+  /// Validates whether the given [example]'s gradle content is configured to
+  /// build its plugin target with javac lints enabled and treated as errors,
+  /// if the enclosing package is a plugin.
+  ///
+  /// This can only be called on example packages. (Plugin packages should not
+  /// be configured this way, since it would affect clients.)
+  ///
+  /// If [example]'s enclosing package is not a plugin package, this just
+  /// returns true.
+  bool _validateJavacLintConfig(
+      RepositoryPackage example, List<String> gradleLines) {
+    final RepositoryPackage enclosingPackage = example.getEnclosingPackage()!;
+    if (!pluginSupportsPlatform(platformAndroid, enclosingPackage,
+        requiredMode: PlatformSupport.inline)) {
+      return true;
+    }
+    final String enclosingPackageName = enclosingPackage.directory.basename;
+
+    // The check here is intentionally somewhat loose, to allow for the
+    // possibility of variations (e.g., not using Xlint:all in some cases, or
+    // passing other arguments).
+    if (!(gradleLines.any((String line) =>
+            line.contains('project(":$enclosingPackageName")')) &&
+        gradleLines.any((String line) =>
+            line.contains('options.compilerArgs') &&
+            line.contains('-Xlint') &&
+            line.contains('-Werror')))) {
+      printError('The example '
+          '"${getRelativePosixPath(example.directory, from: enclosingPackage.directory)}" '
+          'is not configured to treat javac lints and warnings as errors. '
+          'Please add the following to its build.gradle:');
+      print('''
+gradle.projectsEvaluated {
+    project(":$enclosingPackageName") {
+        tasks.withType(JavaCompile) {
+            options.compilerArgs << "-Xlint:all" << "-Werror"
+        }
+    }
+}
+''');
+      return false;
+    }
+    return true;
+  }
 }

script/tool/lib/src/lint_android_command.dart

@@ -38,22 +38,6 @@ class LintAndroidCommand extends PackageLoopingCommand {
           'Plugin does not have an Android implementation.');
     }
 
-    bool failed = false;
-
-    // Ensure that the plugin has a strict Gradle-driven lint configuration, so
-    // that this test actually catches most issues.
-    if (!_mainGradleHasLintConfig(package)) {
-      failed = true;
-      printError('This plugin is not configured to enable all Gradle-driven '
-          'lint warnings and treat them as errors. '
-          'Please add the following to the lintOptions section of '
-          'android/build.gradle:');
-      print('''
-        checkAllWarnings true
-        warningsAsErrors true
-''');
-    }
-
     for (final RepositoryPackage example in package.getExamples()) {
       final GradleProject project = GradleProject(example,
           processRunner: processRunner, platform: platform);
@@ -75,62 +59,10 @@ class LintAndroidCommand extends PackageLoopingCommand {
       // inline, and the rest have to be checked via the CI-uploaded artifact.
       final int exitCode = await project.runCommand('$packageName:lintDebug');
       if (exitCode != 0) {
-        failed = true;
+        return PackageResult.fail();
       }
-
-      // In addition to running the Gradle-driven lint step, also ensure that
-      // the example project is configured to build with javac lints enabled and
-      // treated as errors.
-      if (!_exampleGradleHasJavacLintConfig(example, packageName)) {
-        failed = true;
-        printError('The example '
-            '"${getRelativePosixPath(example.directory, from: package.directory)}" '
-            'is not configured to treat javac lints and warnings as errors. '
-            'Please add the following to its build.gradle:');
-        print('''
-gradle.projectsEvaluated {
-    project(":${package.directory.basename}") {
-        tasks.withType(JavaCompile) {
-            options.compilerArgs << "-Xlint:all" << "-Werror"
-        }
     }
-}
-''');
-      }
-    }
-
-    return failed ? PackageResult.fail() : PackageResult.success();
-  }
-
-  /// Returns whether the plugin project is configured to enable all Gradle
-  /// lints and treat them as errors.
-  bool _mainGradleHasLintConfig(RepositoryPackage package) {
-    final List<String> gradleBuildContents = package
-        .platformDirectory(FlutterPlatform.android)
-        .childFile('build.gradle')
-        .readAsLinesSync();
-    return gradleBuildContents
-            .any((String line) => line.contains('checkAllWarnings true')) &&
-        gradleBuildContents
-            .any((String line) => line.contains('warningsAsErrors true'));
-  }
 
-  /// Returns whether the example project is configured to build with javac
-  /// lints enabled and treated as errors.
-  bool _exampleGradleHasJavacLintConfig(
-      RepositoryPackage example, String pluginPackageName) {
-    final List<String> gradleBuildContents = example
-        .platformDirectory(FlutterPlatform.android)
-        .childFile('build.gradle')
-        .readAsLinesSync();
-    // The check here is intentionally somewhat loose, to allow for the
-    // possibility of variations (e.g., not using Xlint:all in some cases, or
-    // passing other arguments).
-    return gradleBuildContents.any(
-            (String line) => line.contains('project(":$pluginPackageName")')) &&
-        gradleBuildContents.any((String line) =>
-            line.contains('options.compilerArgs') &&
-            line.contains('-Xlint') &&
-            line.contains('-Werror'));
+    return PackageResult.success();
   }
 }