Don't build native assets in `flutter build bundle` (#136641)

Closes: https://github.com/flutter/flutter/issues/136547

packages/flutter_tools/lib/src/build_info.dart

@@ -967,6 +967,20 @@ const String kSdkRoot = 'SdkRoot';
 /// Whether to enable Dart obfuscation and where to save the symbol map.
 const String kDartObfuscation = 'DartObfuscation';
 
+/// Whether to enable Native Assets.
+///
+/// If true, native assets are built and the mapping for native assets lookup
+/// at runtime is embedded in the kernel file.
+///
+/// If false, native assets are not built, and an empty mapping is embedded in
+/// the kernel file. Used for targets that trigger kernel builds but
+/// are not OS/architecture specific.
+///
+/// Supported values are 'true' and 'false'.
+///
+/// Defaults to 'true'.
+const String kNativeAssets = 'NativeAssets';
+
 /// An output directory where one or more code-size measurements may be written.
 const String kCodeSizeDirectory = 'CodeSizeDirectory';
 

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

@@ -48,157 +48,163 @@ class NativeAssets extends Target {
 
   @override
   Future<void> build(Environment environment) async {
-    final String? targetPlatformEnvironment = environment.defines[kTargetPlatform];
-    if (targetPlatformEnvironment == null) {
-      throw MissingDefineException(kTargetPlatform, name);
-    }
-    final TargetPlatform targetPlatform = getTargetPlatformForName(targetPlatformEnvironment);
-
-    final Uri projectUri = environment.projectDir.uri;
+    final String? nativeAssetsEnvironment = environment.defines[kNativeAssets];
+    final List<Uri> dependencies;
     final FileSystem fileSystem = environment.fileSystem;
-    final File packagesFile = fileSystem
-        .directory(projectUri)
-        .childDirectory('.dart_tool')
-        .childFile('package_config.json');
-    final PackageConfig packageConfig = await loadPackageConfigWithLogging(
-      packagesFile,
-      logger: environment.logger,
-    );
-    final NativeAssetsBuildRunner buildRunner = _buildRunner ??
-        NativeAssetsBuildRunnerImpl(
-          projectUri,
-          packageConfig,
-          fileSystem,
-          environment.logger,
-        );
+    final File nativeAssetsFile = environment.buildDir.childFile('native_assets.yaml');
+    if (nativeAssetsEnvironment == 'false') {
+      dependencies = <Uri>[];
+      await writeNativeAssetsYaml(<Asset>[], environment.buildDir.uri, fileSystem);
+    } else {
+      final String? targetPlatformEnvironment = environment.defines[kTargetPlatform];
+      if (targetPlatformEnvironment == null) {
+        throw MissingDefineException(kTargetPlatform, name);
+      }
+      final TargetPlatform targetPlatform = getTargetPlatformForName(targetPlatformEnvironment);
+      final Uri projectUri = environment.projectDir.uri;
+      final File packagesFile = fileSystem
+          .directory(projectUri)
+          .childDirectory('.dart_tool')
+          .childFile('package_config.json');
+      final PackageConfig packageConfig = await loadPackageConfigWithLogging(
+        packagesFile,
+        logger: environment.logger,
+      );
+      final NativeAssetsBuildRunner buildRunner = _buildRunner ??
+          NativeAssetsBuildRunnerImpl(
+            projectUri,
+            packageConfig,
+            fileSystem,
+            environment.logger,
+          );
 
-    final List<Uri> dependencies;
-    switch (targetPlatform) {
-      case TargetPlatform.ios:
-        final String? iosArchsEnvironment = environment.defines[kIosArchs];
-        if (iosArchsEnvironment == null) {
-          throw MissingDefineException(kIosArchs, name);
-        }
-        final List<DarwinArch> iosArchs = iosArchsEnvironment.split(' ').map(getDarwinArchForName).toList();
-        final String? environmentBuildMode = environment.defines[kBuildMode];
-        if (environmentBuildMode == null) {
-          throw MissingDefineException(kBuildMode, name);
-        }
-        final BuildMode buildMode = BuildMode.fromCliName(environmentBuildMode);
-        final String? sdkRoot = environment.defines[kSdkRoot];
-        if (sdkRoot == null) {
-          throw MissingDefineException(kSdkRoot, name);
-        }
-        final EnvironmentType environmentType = environmentTypeFromSdkroot(sdkRoot, environment.fileSystem)!;
-        dependencies = await buildNativeAssetsIOS(
-          environmentType: environmentType,
-          darwinArchs: iosArchs,
-          buildMode: buildMode,
-          projectUri: projectUri,
-          codesignIdentity: environment.defines[kCodesignIdentity],
-          fileSystem: fileSystem,
-          buildRunner: buildRunner,
-          yamlParentDirectory: environment.buildDir.uri,
-        );
-      case TargetPlatform.darwin:
-        final String? darwinArchsEnvironment = environment.defines[kDarwinArchs];
-        if (darwinArchsEnvironment == null) {
-          throw MissingDefineException(kDarwinArchs, name);
-        }
-        final List<DarwinArch> darwinArchs = darwinArchsEnvironment.split(' ').map(getDarwinArchForName).toList();
-        final String? environmentBuildMode = environment.defines[kBuildMode];
-        if (environmentBuildMode == null) {
-          throw MissingDefineException(kBuildMode, name);
-        }
-        final BuildMode buildMode = BuildMode.fromCliName(environmentBuildMode);
-        (_, dependencies) = await buildNativeAssetsMacOS(
-          darwinArchs: darwinArchs,
-          buildMode: buildMode,
-          projectUri: projectUri,
-          codesignIdentity: environment.defines[kCodesignIdentity],
-          yamlParentDirectory: environment.buildDir.uri,
-          fileSystem: fileSystem,
-          buildRunner: buildRunner,
-        );
-      case TargetPlatform.linux_arm64:
-      case TargetPlatform.linux_x64:
-        final String? environmentBuildMode = environment.defines[kBuildMode];
-        if (environmentBuildMode == null) {
-          throw MissingDefineException(kBuildMode, name);
-        }
-        final BuildMode buildMode = BuildMode.fromCliName(environmentBuildMode);
-        (_, dependencies) = await buildNativeAssetsLinux(
-          targetPlatform: targetPlatform,
-          buildMode: buildMode,
-          projectUri: projectUri,
-          yamlParentDirectory: environment.buildDir.uri,
-          fileSystem: fileSystem,
-          buildRunner: buildRunner,
-        );
-      case TargetPlatform.windows_x64:
-        final String? environmentBuildMode = environment.defines[kBuildMode];
-        if (environmentBuildMode == null) {
-          throw MissingDefineException(kBuildMode, name);
-        }
-        final BuildMode buildMode = BuildMode.fromCliName(environmentBuildMode);
-        (_, dependencies) = await buildNativeAssetsWindows(
-          targetPlatform: targetPlatform,
-          buildMode: buildMode,
-          projectUri: projectUri,
-          yamlParentDirectory: environment.buildDir.uri,
-          fileSystem: fileSystem,
-          buildRunner: buildRunner,
-        );
-      case TargetPlatform.tester:
-        if (const LocalPlatform().isMacOS) {
+
+      switch (targetPlatform) {
+        case TargetPlatform.ios:
+          final String? iosArchsEnvironment = environment.defines[kIosArchs];
+          if (iosArchsEnvironment == null) {
+            throw MissingDefineException(kIosArchs, name);
+          }
+          final List<DarwinArch> iosArchs = iosArchsEnvironment.split(' ').map(getDarwinArchForName).toList();
+          final String? environmentBuildMode = environment.defines[kBuildMode];
+          if (environmentBuildMode == null) {
+            throw MissingDefineException(kBuildMode, name);
+          }
+          final BuildMode buildMode = BuildMode.fromCliName(environmentBuildMode);
+          final String? sdkRoot = environment.defines[kSdkRoot];
+          if (sdkRoot == null) {
+            throw MissingDefineException(kSdkRoot, name);
+          }
+          final EnvironmentType environmentType = environmentTypeFromSdkroot(sdkRoot, environment.fileSystem)!;
+          dependencies = await buildNativeAssetsIOS(
+            environmentType: environmentType,
+            darwinArchs: iosArchs,
+            buildMode: buildMode,
+            projectUri: projectUri,
+            codesignIdentity: environment.defines[kCodesignIdentity],
+            fileSystem: fileSystem,
+            buildRunner: buildRunner,
+            yamlParentDirectory: environment.buildDir.uri,
+          );
+        case TargetPlatform.darwin:
+          final String? darwinArchsEnvironment = environment.defines[kDarwinArchs];
+          if (darwinArchsEnvironment == null) {
+            throw MissingDefineException(kDarwinArchs, name);
+          }
+          final List<DarwinArch> darwinArchs = darwinArchsEnvironment.split(' ').map(getDarwinArchForName).toList();
+          final String? environmentBuildMode = environment.defines[kBuildMode];
+          if (environmentBuildMode == null) {
+            throw MissingDefineException(kBuildMode, name);
+          }
+          final BuildMode buildMode = BuildMode.fromCliName(environmentBuildMode);
           (_, dependencies) = await buildNativeAssetsMacOS(
-            buildMode: BuildMode.debug,
+            darwinArchs: darwinArchs,
+            buildMode: buildMode,
             projectUri: projectUri,
             codesignIdentity: environment.defines[kCodesignIdentity],
             yamlParentDirectory: environment.buildDir.uri,
             fileSystem: fileSystem,
             buildRunner: buildRunner,
-            flutterTester: true,
           );
-        } else if (const LocalPlatform().isLinux) {
+        case TargetPlatform.linux_arm64:
+        case TargetPlatform.linux_x64:
+          final String? environmentBuildMode = environment.defines[kBuildMode];
+          if (environmentBuildMode == null) {
+            throw MissingDefineException(kBuildMode, name);
+          }
+          final BuildMode buildMode = BuildMode.fromCliName(environmentBuildMode);
           (_, dependencies) = await buildNativeAssetsLinux(
-            buildMode: BuildMode.debug,
+            targetPlatform: targetPlatform,
+            buildMode: buildMode,
             projectUri: projectUri,
             yamlParentDirectory: environment.buildDir.uri,
             fileSystem: fileSystem,
             buildRunner: buildRunner,
-            flutterTester: true,
           );
-        } else if (const LocalPlatform().isWindows) {
+        case TargetPlatform.windows_x64:
+          final String? environmentBuildMode = environment.defines[kBuildMode];
+          if (environmentBuildMode == null) {
+            throw MissingDefineException(kBuildMode, name);
+          }
+          final BuildMode buildMode = BuildMode.fromCliName(environmentBuildMode);
           (_, dependencies) = await buildNativeAssetsWindows(
-            buildMode: BuildMode.debug,
+            targetPlatform: targetPlatform,
+            buildMode: buildMode,
             projectUri: projectUri,
             yamlParentDirectory: environment.buildDir.uri,
             fileSystem: fileSystem,
             buildRunner: buildRunner,
-            flutterTester: true,
           );
-        } else {
+        case TargetPlatform.tester:
+          if (const LocalPlatform().isMacOS) {
+            (_, dependencies) = await buildNativeAssetsMacOS(
+              buildMode: BuildMode.debug,
+              projectUri: projectUri,
+              codesignIdentity: environment.defines[kCodesignIdentity],
+              yamlParentDirectory: environment.buildDir.uri,
+              fileSystem: fileSystem,
+              buildRunner: buildRunner,
+              flutterTester: true,
+            );
+          } else if (const LocalPlatform().isLinux) {
+            (_, dependencies) = await buildNativeAssetsLinux(
+              buildMode: BuildMode.debug,
+              projectUri: projectUri,
+              yamlParentDirectory: environment.buildDir.uri,
+              fileSystem: fileSystem,
+              buildRunner: buildRunner,
+              flutterTester: true,
+            );
+          } else if (const LocalPlatform().isWindows) {
+            (_, dependencies) = await buildNativeAssetsWindows(
+              buildMode: BuildMode.debug,
+              projectUri: projectUri,
+              yamlParentDirectory: environment.buildDir.uri,
+              fileSystem: fileSystem,
+              buildRunner: buildRunner,
+              flutterTester: true,
+            );
+          } else {
+            // TODO(dacoharkes): Implement other OSes. https://github.com/flutter/flutter/issues/129757
+            // Write the file we claim to have in the [outputs].
+            await writeNativeAssetsYaml(<Asset>[], environment.buildDir.uri, fileSystem);
+            dependencies = <Uri>[];
+          }
+        case TargetPlatform.android_arm:
+        case TargetPlatform.android_arm64:
+        case TargetPlatform.android_x64:
+        case TargetPlatform.android_x86:
+        case TargetPlatform.android:
+        case TargetPlatform.fuchsia_arm64:
+        case TargetPlatform.fuchsia_x64:
+        case TargetPlatform.web_javascript:
           // TODO(dacoharkes): Implement other OSes. https://github.com/flutter/flutter/issues/129757
           // Write the file we claim to have in the [outputs].
           await writeNativeAssetsYaml(<Asset>[], environment.buildDir.uri, fileSystem);
           dependencies = <Uri>[];
-        }
-      case TargetPlatform.android_arm:
-      case TargetPlatform.android_arm64:
-      case TargetPlatform.android_x64:
-      case TargetPlatform.android_x86:
-      case TargetPlatform.android:
-      case TargetPlatform.fuchsia_arm64:
-      case TargetPlatform.fuchsia_x64:
-      case TargetPlatform.web_javascript:
-        // TODO(dacoharkes): Implement other OSes. https://github.com/flutter/flutter/issues/129757
-        // Write the file we claim to have in the [outputs].
-        await writeNativeAssetsYaml(<Asset>[], environment.buildDir.uri, fileSystem);
-        dependencies = <Uri>[];
+      }
     }
 
-    final File nativeAssetsFile = environment.buildDir.childFile('native_assets.yaml');
     final Depfile depfile = Depfile(
       <File>[
         for (final Uri dependency in dependencies) fileSystem.file(dependency),

packages/flutter_tools/lib/src/bundle_builder.dart

@@ -26,7 +26,11 @@ class BundleBuilder {
   /// Builds the bundle for the given target platform.
   ///
   /// The default `mainPath` is `lib/main.dart`.
-  /// The default  `manifestPath` is `pubspec.yaml`
+  /// The default `manifestPath` is `pubspec.yaml`.
+  ///
+  /// If [buildNativeAssets], native assets are built and the mapping for native
+  /// assets lookup at runtime is embedded in the kernel file, otherwise an
+  /// empty native assets mapping is embedded in the kernel file.
   Future<void> build({
     required TargetPlatform platform,
     required BuildInfo buildInfo,
@@ -36,6 +40,7 @@ class BundleBuilder {
     String? applicationKernelFilePath,
     String? depfilePath,
     String? assetDirPath,
+    bool buildNativeAssets = true,
     @visibleForTesting BuildSystem? buildSystem,
   }) async {
     project ??= FlutterProject.current();
@@ -60,6 +65,7 @@ class BundleBuilder {
         kTargetFile: mainPath,
         kDeferredComponents: 'false',
         ...buildInfo.toBuildSystemEnvironment(),
+        if (!buildNativeAssets) kNativeAssets: 'false'
       },
       artifacts: globals.artifacts!,
       fileSystem: globals.fs,

packages/flutter_tools/lib/src/commands/build_bundle.dart

@@ -132,6 +132,7 @@ class BuildBundleCommand extends BuildSubCommand {
       mainPath: targetFile,
       depfilePath: stringArg('depfile'),
       assetDirPath: stringArg('asset-dir'),
+      buildNativeAssets: false,
     );
     return FlutterCommandResult.success();
   }

packages/flutter_tools/test/commands.shard/permeable/build_bundle_test.dart

@@ -252,6 +252,7 @@ void main() {
         kIconTreeShakerFlag: 'false',
         kDeferredComponents: 'false',
         kDartObfuscation: 'false',
+        kNativeAssets: 'false',
       });
     }),
     FileSystem: fsFactory,
@@ -285,6 +286,7 @@ void main() {
         kIconTreeShakerFlag: 'false',
         kDeferredComponents: 'false',
         kDartObfuscation: 'false',
+        kNativeAssets: 'false',
       });
     }),
     FileSystem: fsFactory,
@@ -317,6 +319,7 @@ void main() {
         kIconTreeShakerFlag: 'false',
         kDeferredComponents: 'false',
         kDartObfuscation: 'false',
+        kNativeAssets: 'false',
       });
     }),
     FileSystem: fsFactory,
@@ -350,6 +353,7 @@ void main() {
         kIconTreeShakerFlag: 'false',
         kDeferredComponents: 'false',
         kDartObfuscation: 'false',
+        kNativeAssets: 'false',
       });
     }),
     FileSystem: fsFactory,
@@ -383,6 +387,7 @@ void main() {
         kIconTreeShakerFlag: 'false',
         kDeferredComponents: 'false',
         kDartObfuscation: 'false',
+        kNativeAssets: 'false',
       });
     }),
     FileSystem: fsFactory,
@@ -416,6 +421,7 @@ void main() {
         kIconTreeShakerFlag: 'false',
         kDeferredComponents: 'false',
         kDartObfuscation: 'false',
+        kNativeAssets: 'false',
       });
     }),
     FileSystem: fsFactory,
@@ -457,6 +463,7 @@ void main() {
         kIconTreeShakerFlag: 'false',
         kDeferredComponents: 'false',
         kDartObfuscation: 'false',
+        kNativeAssets: 'false',
       });
     }),
     FileSystem: fsFactory,
@@ -498,6 +505,7 @@ void main() {
         kIconTreeShakerFlag: 'false',
         kDeferredComponents: 'false',
         kDartObfuscation: 'false',
+        kNativeAssets: 'false',
       });
     }),
     FileSystem: fsFactory,
@@ -516,7 +524,7 @@ class FakeBundleBuilder extends Fake implements BundleBuilder {
     String? applicationKernelFilePath,
     String? depfilePath,
     String? assetDirPath,
-    Uri? nativeAssets,
+    bool buildNativeAssets = true,
     @visibleForTesting BuildSystem? buildSystem,
   }) async {}
 }

packages/flutter_tools/test/general.shard/custom_devices/custom_device_test.dart

@@ -645,6 +645,7 @@ class FakeBundleBuilder extends Fake implements BundleBuilder {
     String? depfilePath,
     String? assetDirPath,
     Uri? nativeAssets,
+    bool buildNativeAssets = true,
     @visibleForTesting BuildSystem? buildSystem
   }) async {}
 }

packages/flutter_tools/test/general.shard/preview_device_test.dart

@@ -196,7 +196,7 @@ class FakeBundleBuilder extends Fake implements BundleBuilder {
     String? applicationKernelFilePath,
     String? depfilePath,
     String? assetDirPath,
-    Uri? nativeAssets,
+    bool buildNativeAssets = true,
     @visibleForTesting BuildSystem? buildSystem
   }) async {
     final Directory assetDirectory = fileSystem