Add omit-type-checks flag for wasm builds (#124341)

Add omit-type-checks flag for wasm builds

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

@@ -274,6 +274,7 @@ class Dart2WasmTarget extends Dart2WebTarget {
       ...decodeCommaSeparated(environment.defines, kExtraFrontEndOptions),
       for (final String dartDefine in decodeDartDefines(environment.defines, kDartDefines))
         '-D$dartDefine',
+      ...WasmCompilerConfig.fromBuildSystemEnvironment(environment.defines).toCommandOptions(),
       '--packages=.dart_tool/package_config.json',
       '--dart-sdk=$dartSdkPath',
       '--multi-root-scheme',

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

@@ -97,18 +97,19 @@ class BuildWebCommand extends BuildSubCommand {
     //
     if (featureFlags.isFlutterWebWasmEnabled) {
       argParser.addSeparator('Experimental options');
-      argParser.addFlag(
-        FlutterOptions.kWebWasmFlag,
-        help: 'Compile to WebAssembly rather than JavaScript.\nSee $kWasmPreviewUri for more information.',
-        negatable: false,
-      );
-    } else {
-      // Add the flag as hidden. Will give a helpful error message in [runCommand] below.
-      argParser.addFlag(
-        FlutterOptions.kWebWasmFlag,
-        hide: true,
-      );
     }
+    argParser.addFlag(
+      FlutterOptions.kWebWasmFlag,
+      help: 'Compile to WebAssembly rather than JavaScript.\nSee $kWasmPreviewUri for more information.',
+      negatable: false,
+      hide: !featureFlags.isFlutterWebWasmEnabled,
+    );
+    argParser.addFlag(
+      'omit-type-checks',
+      help: 'Omit type checks in Wasm output.',
+      negatable: false,
+      hide: !featureFlags.isFlutterWebWasmEnabled,
+    );
   }
 
   final FileSystem _fileSystem;
@@ -139,7 +140,9 @@ class BuildWebCommand extends BuildSubCommand {
       if (!featureFlags.isFlutterWebWasmEnabled) {
         throwToolExit('Compiling to WebAssembly (wasm) is only available on the master channel.');
       }
-      compilerConfig = const WasmCompilerConfig();
+      compilerConfig = WasmCompilerConfig(
+        omitTypeChecks: boolArg('omit-type-checks'),
+      );
     } else {
       compilerConfig = JsCompilerConfig(
         csp: boolArg('csp'),

packages/flutter_tools/lib/src/web/compiler_config.dart

@@ -128,11 +128,34 @@ class JsCompilerConfig extends WebCompilerConfig {
 
 /// Configuration for the Wasm compiler.
 class WasmCompilerConfig extends WebCompilerConfig {
-  const WasmCompilerConfig();
+  const WasmCompilerConfig({
+    required this.omitTypeChecks,
+  });
+
+  /// Creates a new [WasmCompilerConfig] from build system environment values.
+  ///
+  /// Should correspond exactly with [toBuildSystemEnvironment].
+  factory WasmCompilerConfig.fromBuildSystemEnvironment(
+          Map<String, String> defines) =>
+      WasmCompilerConfig(
+        omitTypeChecks: defines[kOmitTypeChecks] == 'true',
+      );
+
+  /// Build environment for [omitTypeChecks];
+  static const String kOmitTypeChecks = 'WasmOmitTypeChecks';
+
+  /// If `omit-type-checks` should be passed to `dart2wasm`.
+  final bool omitTypeChecks;
 
   @override
   bool get isWasm => true;
 
   @override
-  Map<String, String> toBuildSystemEnvironment() => const <String, String>{};
+  Map<String, String> toBuildSystemEnvironment() => <String, String>{
+    kOmitTypeChecks: omitTypeChecks.toString(),
+  };
+
+  List<String> toCommandOptions() => <String>[
+    if (omitTypeChecks) '--omit-type-checks',
+  ];
 }

packages/flutter_tools/test/general.shard/build_system/targets/web_test.dart

@@ -810,6 +810,41 @@ void main() {
     ProcessManager: () => processManager,
   }));
 
+  test('Dart2WasmTarget invokes dart2wasm with omit checks', () => testbed.run(() async {
+    environment.defines[kBuildMode] = 'release';
+    environment.defines[WasmCompilerConfig.kOmitTypeChecks] = 'true';
+
+    final File depFile = environment.buildDir.childFile('dart2wasm.d');
+
+    processManager.addCommand(FakeCommand(
+      command: <String>[
+        'bin/cache/dart-sdk/bin/dartaotruntime',
+        '--disable-dart-dev',
+        'bin/cache/dart-sdk/bin/snapshots/dart2wasm_product.snapshot',
+        '-Ddart.vm.product=true',
+        '--omit-type-checks',
+        '--packages=.dart_tool/package_config.json',
+        '--dart-sdk=bin/cache/dart-sdk',
+        '--multi-root-scheme',
+        'org-dartlang-sdk',
+        '--multi-root',
+        'bin/cache/flutter_web_sdk',
+        '--multi-root',
+        'bin/cache',
+        '--libraries-spec',
+        'bin/cache/flutter_web_sdk/libraries.json',
+        '--depfile=${depFile.absolute.path}',
+
+        environment.buildDir.childFile('main.dart').absolute.path,
+        environment.buildDir.childFile('main.dart.wasm').absolute.path,
+      ])
+    );
+
+    await Dart2WasmTarget(WebRendererMode.canvaskit).build(environment);
+  }, overrides: <Type, Generator>{
+    ProcessManager: () => processManager,
+  }));
+
   test('Dart2WasmTarget with skwasm renderer adds extra flags', () => testbed.run(() async {
     environment.defines[kBuildMode] = 'release';
     final File depFile = environment.buildDir.childFile('dart2wasm.d');

packages/flutter_tools/test/general.shard/web/compile_web_test.dart

@@ -45,6 +45,7 @@ void main() {
         'TargetFile': 'target',
         'HasWebPlugins': 'false',
         'ServiceWorkerStrategy': 'serviceWorkerStrategy',
+        'WasmOmitTypeChecks': 'false',
         'BuildMode': 'debug',
         'DartObfuscation': 'false',
         'TrackWidgetCreation': 'true',
@@ -68,7 +69,7 @@ void main() {
       'target',
       BuildInfo.debug,
       'serviceWorkerStrategy',
-      compilerConfig: const WasmCompilerConfig(),
+      compilerConfig: const WasmCompilerConfig(omitTypeChecks: false),
     );
 
     expect(logger.statusText, contains('Compiling target for the Web...'));