feat: make generated classes sealed/final

packages/freezed/lib/src/freezed_generator.dart

@@ -146,7 +146,7 @@ class FreezedGenerator extends ParserGenerator<GlobalData, Data, Freezed> {
       genericsParameterTemplate: GenericsParameterTemplate.fromGenericElement(
         declaration.declaredElement!.typeParameters,
       ),
-      shouldMarkSealedOrFinal: configs.finalize ?? false,
+      shouldMarkSealedOrFinal: configs.finalize!,
     );
   }
 

packages/freezed/pubspec_overrides.yaml

@@ -13,3 +13,11 @@ dependency_overrides:
   quiver: ^3.2.0
   # watcher 1.0.0 extends, implements, or mixens sealed class 'FileSystemEvent'
   watcher: ^1.1.0
+  # There seems to be a regression with Flutter ^3.24.0
+  # that causes an error when generating sources using the build_runner
+  # after running `flutter pub downgrade` in GitHub actions,
+  # because it then installs frontend_server_client: ^3.0.0:
+  #  Could not find a command named
+  #  "/path/to/flutter/stable-3.24.0-x64/bin/cache/dart-sdk/bin/snapshots/frontend_server.dart.snapshot".
+  # see https://github.com/dart-lang/build/issues/3733#issuecomment-2272082820
+  frontend_server_client: ^4.0.0

packages/freezed/test/finalized_test.dart

@@ -81,4 +81,65 @@ void main() {
       expect(error.errorCode.name, 'PATTERN_NEVER_MATCHES_VALUE_TYPE');
     });
   });
+
+  group('disabled (finalize: false)', () {
+    test('finalize is disabled by default', () async {
+      final main = await resolveSources(
+        {
+          'freezed|test/integration/main.dart': r'''
+library main;
+import 'finalized.dart';
+
+void main() {
+  switch (FinalizedDisabledFoo()) {
+    case FinalizedDisabledBar():
+      break;
+
+    case FinalizedDisabledFoo():
+      break;
+  }
+}
+''',
+        },
+        (r) => r.findLibraryByName('main'),
+      );
+
+      final errorResult = await main!.session
+          .getErrors('/freezed/test/integration/main.dart') as ErrorsResult;
+
+      // the absence of a warning means that the generated subclasses of FinalizedDisabled
+      // or not sealed/final, and therefore it is disabled by default
+      expect(errorResult.errors, isEmpty);
+    });
+  });
+  group('default config', () {
+    test('finalize is disabled by default', () async {
+      final main = await resolveSources(
+        {
+          'freezed|test/integration/main.dart': r'''
+library main;
+import 'finalized.dart';
+
+void main() {
+  switch (FinalizedDefaultFoo()) {
+    case FinalizedDefaultBar():
+      break;
+
+    case FinalizedDefaultFoo():
+      break;
+  }
+}
+''',
+        },
+        (r) => r.findLibraryByName('main'),
+      );
+
+      final errorResult = await main!.session
+          .getErrors('/freezed/test/integration/main.dart') as ErrorsResult;
+
+      // the absence of a warning means that the generated subclasses of FinalizedDefault
+      // or not sealed/final, and therefore it is disabled by default
+      expect(errorResult.errors, isEmpty);
+    });
+  });
 }

packages/freezed/test/integration/finalized.dart

@@ -18,3 +18,15 @@ sealed class FinalizedMultiple with _$FinalizedMultiple {
   factory FinalizedMultiple.b() = FinalizedMultipleB;
   factory FinalizedMultiple.c() = FinalizedMultipleC;
 }
+
+@Freezed()
+sealed class FinalizedDefault with _$FinalizedDefault {
+  factory FinalizedDefault.foo() = FinalizedDefaultFoo;
+  factory FinalizedDefault.bar() = FinalizedDefaultBar;
+}
+
+@Freezed(finalize: false)
+sealed class FinalizedDisabled with _$FinalizedDisabled {
+  factory FinalizedDisabled.foo() = FinalizedDisabledFoo;
+  factory FinalizedDisabled.bar() = FinalizedDisabledBar;
+}

packages/freezed_annotation/lib/freezed_annotation.dart

@@ -515,6 +515,7 @@ class Freezed {
   ///       break;
   ///   }
   /// ```
+  @JsonKey(defaultValue: false)
   final bool? finalize;
 
   /// Options for customizing the generation of `map` functions

packages/freezed_annotation/pubspec_overrides.yaml

@@ -11,3 +11,11 @@ dependency_overrides:
   pub_semver: ^2.1.3
   # watcher 1.0.0 extends, implements, or mixens sealed class 'FileSystemEvent'
   watcher: ^1.1.0
+  # There seems to be a regression with Flutter ^3.24.0
+  # that causes an error when generating sources using the build_runner
+  # after running `flutter pub downgrade` in GitHub actions,
+  # because it then installs frontend_server_client: ^3.0.0:
+  #  Could not find a command named
+  #  "/path/to/flutter/stable-3.24.0-x64/bin/cache/dart-sdk/bin/snapshots/frontend_server.dart.snapshot".
+  # see https://github.com/dart-lang/build/issues/3733#issuecomment-2272082820
+  frontend_server_client: ^4.0.0

packages/freezed_annotation/test/freezed_test.dart

@@ -151,6 +151,7 @@ void main() {
       expect(defaultValue.unionValueCase, isNull);
       expect(defaultValue.when, isNull);
       expect(defaultValue.makeCollectionsUnmodifiable, isTrue);
+      expect(defaultValue.finalize, isFalse);
     });
 
     test('.fromJson({map: x})', () {