fix: copyWith sometimes not working with null (#808)

fixes #807
fixes #803

packages/freezed/CHANGELOG.md

@@ -1,3 +1,7 @@
+# [Unreleased fix]
+
+Fixes copyWith not working with `null` on some scenarios.
+
 # 2.2.1
 
 Upgrade analyzer

packages/freezed/lib/builder.dart

@@ -13,7 +13,7 @@ Builder freezed(BuilderOptions options) {
 // coverage:ignore-file
 // GENERATED CODE - DO NOT MODIFY BY HAND
 // ignore_for_file: type=lint
-// ignore_for_file: unused_element, deprecated_member_use, deprecated_member_use_from_same_package, use_function_type_syntax_for_parameters, unnecessary_const, avoid_init_to_null, invalid_override_different_default_values_named, prefer_expression_function_bodies, annotate_overrides, invalid_annotation_target
+// ignore_for_file: unused_element, deprecated_member_use, deprecated_member_use_from_same_package, use_function_type_syntax_for_parameters, unnecessary_const, avoid_init_to_null, invalid_override_different_default_values_named, prefer_expression_function_bodies, annotate_overrides, invalid_annotation_target, unnecessary_question_mark
     ''',
     options: options,
   );

packages/freezed/lib/src/templates/parameter_template.dart

@@ -1,9 +1,9 @@
 import 'package:analyzer/dart/element/element.dart';
-import 'package:analyzer/dart/element/nullability_suffix.dart';
 import 'package:build/build.dart';
 import 'package:freezed/src/templates/concrete_template.dart';
 import 'package:freezed/src/templates/properties.dart';
 import 'package:freezed/src/templates/prototypes.dart';
+import 'package:freezed/src/tools/type.dart';
 import 'package:freezed/src/utils.dart';
 
 class GenericsDefinitionTemplate {
@@ -70,7 +70,7 @@ class ParametersTemplate {
     Future<Parameter> asParameter(ParameterElement e) async {
       final value = Parameter(
         name: e.name,
-        isNullable: e.type.nullabilitySuffix == NullabilitySuffix.question,
+        isNullable: e.type.isNullable,
         isDartList: e.type.isDartCoreList,
         isDartMap: e.type.isDartCoreMap,
         isDartSet: e.type.isDartCoreSet,

packages/freezed/lib/src/templates/properties.dart

@@ -1,7 +1,7 @@
 import 'package:analyzer/dart/element/element.dart';
-import 'package:analyzer/dart/element/nullability_suffix.dart';
 import 'package:analyzer/dart/element/type.dart';
 import 'package:build/build.dart';
+import 'package:freezed/src/tools/type.dart';
 import 'package:source_gen/source_gen.dart';
 
 import '../utils.dart';
@@ -49,7 +49,7 @@ class Property {
 
     return Property(
       name: element.name,
-      isNullable: element.type.nullabilitySuffix == NullabilitySuffix.question,
+      isNullable: element.type.isNullable,
       isDartList: element.type.isDartCoreList,
       isDartMap: element.type.isDartCoreMap,
       isDartSet: element.type.isDartCoreSet,

packages/freezed/lib/src/tools/type.dart

@@ -5,6 +5,16 @@ import 'package:collection/collection.dart';
 
 import 'imports.dart';
 
+extension DartTypeX on DartType {
+  bool get isNullable {
+    final that = this;
+    if (that is TypeParameterType) {
+      return that.bound.isNullable;
+    }
+    return isDynamic || nullabilitySuffix == NullabilitySuffix.question;
+  }
+}
+
 /// Returns the [Element] for a given [DartType]
 ///
 /// this is usually type.element, except if it is a typedef then it is

packages/freezed/test/deep_copy_test.dart

@@ -5,6 +5,9 @@ import 'package:test/test.dart';
 
 import 'common.dart';
 import 'integration/deep_copy.dart';
+import 'integration/generic.dart'
+    show AnyGeneric, NullableGeneric, NonNullableGeneric;
+import 'integration/single_class_constructor.dart' show Dynamic;
 
 void main() {
   // TODO: copyWith is identical to itself if don't have descendants
@@ -67,6 +70,42 @@ void main() {
       () => company.copyWith.director!.assistant!(name: 'John'),
       throwsA(isA<TypeError>()),
     );
+
+    expect(
+      Dynamic(foo: 42, bar: 21).copyWith(foo: null, bar: null),
+      Dynamic(foo: null, bar: null),
+    );
+    expect(
+      Dynamic(foo: 42, bar: 21).copyWith(),
+      Dynamic(foo: 42, bar: 21),
+    );
+
+    expect(
+      AnyGeneric<int?>(42).copyWith(value: null),
+      AnyGeneric<int?>(null),
+    );
+    expect(
+      AnyGeneric<int?>(42).copyWith(),
+      AnyGeneric<int?>(42),
+    );
+
+    expect(
+      NullableGeneric<int?>(42).copyWith(value: null),
+      NullableGeneric<int?>(null),
+    );
+    expect(
+      NullableGeneric<int?>(42).copyWith(),
+      NullableGeneric<int?>(42),
+    );
+
+    expect(
+      NonNullableGeneric<int>(42).copyWith(value: 21),
+      NonNullableGeneric<int>(21),
+    );
+    expect(
+      NonNullableGeneric<int>(42).copyWith(),
+      NonNullableGeneric<int>(42),
+    );
   });
 
   group('DeepGeneric', () {

packages/freezed/test/integration/generic.dart

@@ -7,6 +7,21 @@ class Model<T> {
   final T value;
 }
 
+@freezed
+class AnyGeneric<T> with _$AnyGeneric<T> {
+  factory AnyGeneric(T value) = _AnyGeneric<T>;
+}
+
+@freezed
+class NullableGeneric<T extends Object?> with _$NullableGeneric<T> {
+  factory NullableGeneric(T value) = _NullableGeneric<T>;
+}
+
+@freezed
+class NonNullableGeneric<T extends Object> with _$NonNullableGeneric<T> {
+  factory NonNullableGeneric(T value) = _NonNullableGeneric<T>;
+}
+
 @freezed
 class Generic<T extends Model<dynamic>> with _$Generic<T> {
   factory Generic(T model) = _Generic<T>;

packages/freezed/test/integration/single_class_constructor.dart

@@ -1,10 +1,20 @@
+// ignore_for_file: unnecessary_question_mark
+
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:freezed_annotation/freezed_annotation.dart';
 
 part 'single_class_constructor.freezed.dart';
 
+@freezed
+class Dynamic with _$Dynamic {
+  factory Dynamic({
+    dynamic foo,
+    dynamic? bar,
+  }) = DynamicFirst;
+}
+
 class CustomMap<A, B> extends MapBase<A, B> {
   CustomMap(this._source);