Disable warnings for the dart plugin registrant (#76561)

packages/flutter_tools/lib/src/compile.dart

@@ -250,6 +250,8 @@ class KernelCompiler {
         mainUri,
         newMainDart,
         mainFile,
+        // TODO(egarciad): Turn this on when the plugins are fixed.
+        throwOnPluginPubspecError: false,
       )) {
         mainUri = newMainDart.path;
       }

packages/flutter_tools/lib/src/plugins.dart

@@ -539,6 +539,7 @@ List<PluginInterfaceResolution> resolvePlatformImplementation(
       if (plugin.implementsPackage == null || plugin.implementsPackage.isEmpty) {
         final String defaultImplementation = plugin.defaultPackagePlatforms[platform];
         if (defaultImplementation == null) {
+          if (throwOnPluginPubspecError) {
             globals.printError(
               'Plugin `${plugin.name}` doesn\'t implement a plugin interface, nor sets '
               'a default implementation in pubspec.yaml.\n\n'
@@ -555,6 +556,7 @@ List<PluginInterfaceResolution> resolvePlatformImplementation(
               '    implements: <plugin-interface>'
               '\n'
             );
+          }
           didFindError = true;
           continue;
         }
@@ -569,12 +571,14 @@ List<PluginInterfaceResolution> resolvePlatformImplementation(
       if (directDependencyResolutions.containsKey(resolutionKey)) {
         final PluginInterfaceResolution currResolution = directDependencyResolutions[resolutionKey];
         if (currResolution.plugin.isDirectDependency && plugin.isDirectDependency) {
+          if (throwOnPluginPubspecError) {
             globals.printError(
               'Plugin `${plugin.name}` implements an interface for `$platform`, which was already '
               'implemented by plugin `${currResolution.plugin.name}`.\n'
               'To fix this issue, remove either dependency from pubspec.yaml.'
               '\n\n'
             );
+          }
           didFindError = true;
         }
         if (currResolution.plugin.isDirectDependency) {
@@ -931,19 +935,22 @@ Future<void> _writeAndroidPluginRegistrant(FlutterProject project, List<Plugin>
 /// Returns [true] if it's necessary to create a plugin registrant, and
 /// if the new entrypoint was written to disk.
 ///
+/// This method also validates each plugin's pubspec.yaml, but errors are only
+/// reported if [throwOnPluginPubspecError] is [true].
+///
 /// For more details, see https://flutter.dev/go/federated-plugins.
 Future<bool> generateMainDartWithPluginRegistrant(
   FlutterProject rootProject,
   PackageConfig packageConfig,
   String currentMainUri,
   File newMainDart,
-  File mainFile,
-) async {
+  File mainFile, {
+  bool throwOnPluginPubspecError,
+}) async {
   final List<Plugin> plugins = await findPlugins(rootProject);
   final List<PluginInterfaceResolution> resolutions = resolvePlatformImplementation(
     plugins,
-    // TODO(egarciad): Turn this on after fixing the pubspec.yaml of the plugins used in tests.
-    throwOnPluginPubspecError: false,
+    throwOnPluginPubspecError: throwOnPluginPubspecError,
   );
   final LanguageVersion entrypointVersion = determineLanguageVersion(
     mainFile,

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

@@ -1915,6 +1915,7 @@ void main() {
           'package:app/main.dart',
           flutterBuild,
           mainFile,
+          throwOnPluginPubspecError: true,
         );
         expect(didGenerate, isTrue);
         expect(flutterBuild.readAsStringSync(),
@@ -2000,6 +2001,7 @@ void main() {
             'package:app/main.dart',
             flutterBuild,
             mainFile,
+            throwOnPluginPubspecError: true,
           ), throwsToolExit(message:
             'Invalid plugin specification url_launcher_macos.\n'
             'Invalid "macos" plugin specification.'
@@ -2055,6 +2057,7 @@ void main() {
             'package:app/main.dart',
             flutterBuild,
             mainFile,
+            throwOnPluginPubspecError: true,
           ), throwsToolExit(message:
             'Invalid plugin specification url_launcher_macos.\n'
             'Cannot find the `flutter.plugin.platforms` key in the `pubspec.yaml` file. '
@@ -2066,6 +2069,35 @@ void main() {
         FileSystem: () => fs,
         ProcessManager: () => FakeProcessManager.any(),
       });
+
+      testUsingContext('Does not show error messages if throwOnPluginPubspecError is false', () async {
+        final FileSystem fs = MemoryFileSystem();
+        final Set<String> directDependencies = <String>{
+          'url_launcher_windows',
+        };
+        resolvePlatformImplementation(<Plugin>[
+          Plugin.fromYaml(
+            'url_launcher_windows',
+            '',
+            YamlMap.wrap(<String, dynamic>{
+              'platforms': <String, dynamic>{
+                'windows': <String, dynamic>{
+                  'dartPluginClass': 'UrlLauncherPluginWindows',
+                },
+              },
+            }),
+            <String>[],
+            fileSystem: fs,
+            appDependencies: directDependencies,
+          ),
+        ],
+          throwOnPluginPubspecError: false,
+        );
+        expect(testLogger.errorText, '');
+      }, overrides: <Type, Generator>{
+        FileSystem: () => fs,
+        ProcessManager: () => FakeProcessManager.any(),
+      });
     });
 
     group('pubspec', () {