Fix a bug when annotated classes also use mixins (#1211)

Swapped a cast to ClassElement to less specific InterfaceElement

Fixes #1210

Prepare to release v6.4.1

Author: kevmoo

json_serializable/CHANGELOG.md

@@ -1,5 +1,6 @@
-## 6.4.1-dev
+## 6.4.1
 
+- Fixed a bug when an `@JsonSerializable` class uses a mixin with fields.
 - Added more documentation `@JsonEnum`.
 
 ## 6.4.0

json_serializable/lib/src/field_helpers.dart

@@ -36,8 +36,9 @@ class _FieldSet implements Comparable<_FieldSet> {
   int compareTo(_FieldSet other) => _sortByLocation(sortField, other.sortField);
 
   static int _sortByLocation(FieldElement a, FieldElement b) {
-    final checkerA =
-        TypeChecker.fromStatic((a.enclosingElement3 as ClassElement).thisType);
+    final checkerA = TypeChecker.fromStatic(
+      (a.enclosingElement3 as InterfaceElement).thisType,
+    );
 
     if (!checkerA.isExactly(b.enclosingElement3)) {
       // in this case, you want to prioritize the enclosingElement that is more

json_serializable/pubspec.yaml

@@ -1,5 +1,5 @@
 name: json_serializable
-version: 6.4.1-dev
+version: 6.4.1
 description: >-
   Automatically generate code for converting to and from JSON by annotating
   Dart classes.

json_serializable/test/integration/json_test_example.dart

@@ -239,3 +239,21 @@ class PrivateConstructor {
   bool operator ==(Object other) =>
       other is PrivateConstructor && id == other.id && value == other.value;
 }
+
+mixin RegressionTestIssue1210Mixin {
+  bool? get someProperty => null;
+
+  @override
+  int get hashCode => identityHashCode(this);
+}
+
+@JsonSerializable()
+class RegressionTestIssue1210 with RegressionTestIssue1210Mixin {
+  const RegressionTestIssue1210(this.field);
+
+  factory RegressionTestIssue1210.fromJson(Map<String, dynamic> json) =>
+      _$RegressionTestIssue1210FromJson(json);
+  final String field;
+
+  Map<String, dynamic> toJson() => _$RegressionTestIssue1210ToJson(this);
+}

json_serializable/test/integration/json_test_example.g.dart

@@ -247,3 +247,23 @@ class PrivateConstructor {
   bool operator ==(Object other) =>
       other is PrivateConstructor && id == other.id && value == other.value;
 }
+
+mixin RegressionTestIssue1210Mixin {
+  bool? get someProperty => null;
+
+  @override
+  int get hashCode => identityHashCode(this);
+}
+
+@JsonSerializable(
+  anyMap: true,
+)
+class RegressionTestIssue1210 with RegressionTestIssue1210Mixin {
+  const RegressionTestIssue1210(this.field);
+
+  factory RegressionTestIssue1210.fromJson(Map<String, dynamic> json) =>
+      _$RegressionTestIssue1210FromJson(json);
+  final String field;
+
+  Map<String, dynamic> toJson() => _$RegressionTestIssue1210ToJson(this);
+}