Support using Freezed on normal Dart classes (#1157)

Author: rrousselGit

packages/freezed/CHANGELOG.md

@@ -1,34 +1,52 @@
 ## Unreleased 3.0.0
 
+Freezed 3.0 is about supporting a "mixed mode".  
+From now on, Freezed supports both the usual syntax:
+
+```dart
+@freezed
+sealed class Usual with _$Usual {
+  factory Usual({int a}) = _Usual;
+}
+```
+
+But also:
+
+```dart
+@freezed
+class Usual with _$Usual {
+  Usual({this.a});
+  final int a;
+}
+```
+
+This has multiple benefits:
+
+- Simple classes don't need Freezed's "weird" syntax and can stay simple
+- Unions can keep using the usual `factory` syntax
+
+It also has another benefit:  
+Complex Unions now have a way to use Inheritance and non-constant default values,
+by relying on a non-factory `MyClass._()` constructor:
+
+```dart
+@freezed
+sealed class Response<T> with _$Response<T> {
+  Response._({DateTime? time}) : time = time ?? DateTime.now();
+  // Constructors may enable passing parameters to ._();
+  factory Response.data(T value, {DateTime? time}) = ResponseData;
+  // If those parameters are named optionals, they are not required to be passed.
+  factory Response.error(Object error) = ResponseError;
+
+  @override
+  final DateTime time;
+}
+```
+
+### Breaking changes:
+
 - **Breaking**: Removed `map/when` and variants. These have been discouraged since Dart got pattern matching.
 - **Breaking**: Freezed classes should now either be `abstract`, `sealed`, or manually implements `_$MyClass`.
-- Inheritance and dynamic default values are now supported by specifying them in the `MyClass._()` constructor.  
-  Inheritance example:
-  ```dart
-  class BaseClass {
-    BaseClass.name(this.value);
-    final int value;
-  }
-  @freezed
-  abstract class Example extends BaseClass with _$Example {
-    // We can pass super values through the ._ constructor.
-    Example._(super.value): super.name();
-
-    factory Example(int value, String name) = _Example;
-  }
-  ```
-  Dynamic default values example:
-  ```dart
-  @freezed
-  abstract class Example with _$Example {
-    Example._(Duration? duration)
-      : duration ??= DateTime.now();
-
-    factory Example({Duration? duration}) = _Example;
-
-    final Duration? duration;
-  }
-  ```
 
 ## 2.5.8 - 2025-01-06
 

packages/freezed/build.yaml

@@ -5,11 +5,11 @@ targets:
         enabled: true
         generate_for:
           exclude:
-            - test
             - example
+            - test/source_gen_src.dart
           include:
-            - test/integration/*
-            - test/integration/**/*
+            - test/*
+            - test/**/*
       source_gen|combining_builder:
         options:
           ignore_for_file:

packages/freezed/lib/src/ast.dart

@@ -2,7 +2,7 @@ import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
 
 extension AstX on AstNode {
-  String get documentation {
+  String? get documentation {
     final builder = StringBuffer();
 
     for (Token? token = beginToken.precedingComments;
@@ -11,6 +11,8 @@ extension AstX on AstNode {
       builder.writeln(token);
     }
 
+    if (builder.isEmpty) return null;
+
     return builder.toString();
   }
 }

packages/freezed/lib/src/freezed_generator.dart

@@ -2,8 +2,6 @@ import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/constant/value.dart';
 import 'package:collection/collection.dart';
 import 'package:freezed/src/templates/copy_with.dart';
-import 'package:freezed/src/templates/properties.dart';
-import 'package:freezed/src/tools/type.dart';
 import 'package:freezed_annotation/freezed_annotation.dart' show Freezed;
 import 'package:meta/meta.dart';
 import 'package:source_gen/source_gen.dart';
@@ -21,14 +19,6 @@ extension StringX on String {
   }
 }
 
-class CommonProperties {
-  /// Properties that have a getter in the abstract class
-  final List<Property> readableProperties = [];
-
-  /// Properties that are visible on `copyWith`
-  final List<Property> cloneableProperties = [];
-}
-
 @immutable
 class FreezedGenerator extends ParserGenerator<Freezed> {
   FreezedGenerator(this._buildYamlConfigs);
@@ -57,141 +47,14 @@ class FreezedGenerator extends ParserGenerator<Freezed> {
     return Class.from(declaration, configs, globalConfigs: _buildYamlConfigs);
   }
 
-  CommonProperties _commonParametersBetweenAllConstructors(Class data) {
-    final constructorsNeedsGeneration = data.constructors;
-
-    final result = CommonProperties();
-    if (constructorsNeedsGeneration case [final ctor]) {
-      result.cloneableProperties.addAll(
-        constructorsNeedsGeneration.first.parameters.allParameters
-            .map(Property.fromParameter),
-      );
-      result.readableProperties.addAll(result.cloneableProperties
-          .where((p) => ctor.isSynthetic(param: p.name)));
-      return result;
-    }
-
-    parameterLoop:
-    for (final parameter
-        in constructorsNeedsGeneration.first.parameters.allParameters) {
-      final isSynthetic =
-          constructorsNeedsGeneration.first.isSynthetic(param: parameter.name);
-
-      final library = parameter.parameterElement!.library!;
-
-      var commonTypeBetweenAllUnionConstructors =
-          parameter.parameterElement!.type;
-
-      for (final constructor in constructorsNeedsGeneration) {
-        final matchingParameter = constructor.parameters.allParameters
-            .firstWhereOrNull((p) => p.name == parameter.name);
-        // The property is not present in one of the union cases, so shouldn't
-        // be present in the abstract class.
-        if (matchingParameter == null) continue parameterLoop;
-
-        commonTypeBetweenAllUnionConstructors =
-            library.typeSystem.leastUpperBound(
-          commonTypeBetweenAllUnionConstructors,
-          matchingParameter.parameterElement!.type,
-        );
-      }
-
-      final matchingParameters = constructorsNeedsGeneration
-          .expand((element) => element.parameters.allParameters)
-          .where((element) => element.name == parameter.name)
-          .toList();
-
-      final isFinal = matchingParameters.any(
-        (element) =>
-            element.isFinal ||
-            element.parameterElement?.type !=
-                commonTypeBetweenAllUnionConstructors,
-      );
-
-      final nonNullableCommonType = library.typeSystem
-          .promoteToNonNull(commonTypeBetweenAllUnionConstructors);
-
-      final didDowncast = matchingParameters.any(
-        (element) =>
-            element.parameterElement?.type !=
-            commonTypeBetweenAllUnionConstructors,
-      );
-      final didNonNullDowncast = matchingParameters.any(
-        (element) =>
-            element.parameterElement?.type !=
-                commonTypeBetweenAllUnionConstructors &&
-            element.parameterElement?.type != nonNullableCommonType,
-      );
-      final didNullDowncast = !didNonNullDowncast && didDowncast;
-
-      final commonTypeString = resolveFullTypeStringFrom(
-        library,
-        commonTypeBetweenAllUnionConstructors,
-      );
-
-      final commonProperty = Property(
-        isFinal: isFinal,
-        type: commonTypeString,
-        isNullable: commonTypeBetweenAllUnionConstructors.isNullable,
-        isDartList: commonTypeBetweenAllUnionConstructors.isDartCoreList,
-        isDartMap: commonTypeBetweenAllUnionConstructors.isDartCoreMap,
-        isDartSet: commonTypeBetweenAllUnionConstructors.isDartCoreSet,
-        isPossiblyDartCollection:
-            commonTypeBetweenAllUnionConstructors.isPossiblyDartCollection,
-        name: parameter.name,
-        decorators: parameter.decorators,
-        defaultValueSource: parameter.defaultValueSource,
-        doc: parameter.doc,
-        // TODO support JsonKey
-        hasJsonKey: false,
-      );
-
-      if (isSynthetic) result.readableProperties.add(commonProperty);
-
-      // For {int a, int b, int c} | {int a, int? b, double c}, allows:
-      // copyWith({int a, int b})
-      // - int? b is not allowed because `null` is not compatible with the
-      //   first union case.
-      // - num c is not allowed because num is not assignable int/double
-      if (!didNonNullDowncast) {
-        final copyWithType = didNullDowncast
-            ? nonNullableCommonType
-            : commonTypeBetweenAllUnionConstructors;
-
-        result.cloneableProperties.add(
-          Property(
-            isFinal: isFinal,
-            type: resolveFullTypeStringFrom(
-              library,
-              copyWithType,
-            ),
-            isNullable: copyWithType.isNullable,
-            isDartList: copyWithType.isDartCoreList,
-            isDartMap: copyWithType.isDartCoreMap,
-            isDartSet: copyWithType.isDartCoreSet,
-            isPossiblyDartCollection: copyWithType.isPossiblyDartCollection,
-            name: parameter.name,
-            decorators: parameter.decorators,
-            defaultValueSource: parameter.defaultValueSource,
-            doc: parameter.doc,
-            // TODO support JsonKey
-            hasJsonKey: false,
-          ),
-        );
-      }
-    }
-
-    return result;
-  }
-
   Iterable<DeepCloneableProperty> _getCommonDeepCloneableProperties(
     List<ConstructorDetails> constructors,
-    CommonProperties commonProperties,
+    PropertyList commonProperties,
   ) sync* {
     for (final commonProperty in commonProperties.cloneableProperties) {
       final commonGetter = commonProperties.readableProperties
           .firstWhereOrNull((e) => e.name == commonProperty.name);
-      final deepCopyProperty = constructors.first.deepCloneableProperties
+      final deepCopyProperty = constructors.firstOrNull?.deepCloneableProperties
           .firstWhereOrNull((e) => e.name == commonProperty.name);
 
       if (deepCopyProperty == null || commonGetter == null) continue;
@@ -239,17 +102,15 @@ class FreezedGenerator extends ParserGenerator<Freezed> {
   ) sync* {
     if (data.options.fromJson) yield FromJson(data);
 
-    final commonProperties = _commonParametersBetweenAllConstructors(data);
-
     final commonCopyWith = data.options.annotation.copyWith ??
-            commonProperties.cloneableProperties.isNotEmpty
+            data.properties.cloneableProperties.isNotEmpty
         ? CopyWith(
             clonedClassName: data.name,
-            readableProperties: commonProperties.readableProperties,
-            cloneableProperties: commonProperties.cloneableProperties,
+            readableProperties: data.properties.readableProperties,
+            cloneableProperties: data.properties.cloneableProperties,
             deepCloneableProperties: _getCommonDeepCloneableProperties(
               data.constructors,
-              commonProperties,
+              data.properties,
             ).toList(),
             genericsDefinition: data.genericsDefinitionTemplate,
             genericsParameter: data.genericsParameterTemplate,
@@ -260,25 +121,23 @@ class FreezedGenerator extends ParserGenerator<Freezed> {
     yield Abstract(
       data: data,
       copyWith: commonCopyWith,
-      commonProperties: commonProperties.readableProperties,
+      commonProperties: data.properties.readableProperties,
+      globalData: globalData,
     );
 
     for (final constructor in data.constructors) {
       yield Concrete(
         data: data,
         constructor: constructor,
-        commonProperties: commonProperties.readableProperties,
+        commonProperties: data.properties.readableProperties,
         globalData: globalData,
         copyWith: data.options.annotation.copyWith ??
                 constructor.parameters.allParameters.isNotEmpty
             ? CopyWith(
                 clonedClassName: constructor.redirectedName,
-                cloneableProperties:
-                    constructor.properties.map((e) => e.value).toList(),
-                readableProperties: constructor.properties
-                    .where((e) => e.isSynthetic)
-                    .map((e) => e.value)
-                    .toList(),
+                cloneableProperties: constructor.properties.toList(),
+                readableProperties:
+                    constructor.properties.where((e) => e.isSynthetic).toList(),
                 deepCloneableProperties: constructor.deepCloneableProperties,
                 genericsDefinition: data.genericsDefinitionTemplate,
                 genericsParameter: data.genericsParameterTemplate,