[Serializer] Fix readonly property initialization from incorrect scope

Author: santysisi

src/Symfony/Component/Serializer/Normalizer/PropertyNormalizer.php

@@ -13,6 +13,7 @@
 
 use Symfony\Component\PropertyAccess\Exception\UninitializedPropertyException;
 use Symfony\Component\PropertyInfo\PropertyTypeExtractorInterface;
+use Symfony\Component\Serializer\Exception\LogicException;
 use Symfony\Component\Serializer\Mapping\ClassDiscriminatorResolverInterface;
 use Symfony\Component\Serializer\Mapping\Factory\ClassMetadataFactoryInterface;
 use Symfony\Component\Serializer\NameConverter\NameConverterInterface;
@@ -202,7 +203,24 @@ protected function setAttributeValue(object $object, string $attribute, mixed $v
             return;
         }
 
-        $reflectionProperty->setValue($object, $value);
+        if (!$reflectionProperty->isReadOnly()) {
+            $reflectionProperty->setValue($object, $value);
+
+            return;
+        }
+
+        if (!$reflectionProperty->isInitialized($object)) {
+            $declaringClass = $reflectionProperty->getDeclaringClass();
+            $declaringClass->getProperty($reflectionProperty->getName())->setValue($object, $value);
+
+            return;
+        }
+
+        if ($reflectionProperty->getValue($object) === $value) {
+            return;
+        }
+
+        throw new LogicException(\sprintf('Attempting to change readonly property "%s"::$%s.', $object::class, $reflectionProperty->getName()));
     }
 
     /**

src/Symfony/Component/Serializer/Tests/Fixtures/ChildClassDummy.php

@@ -0,0 +1,17 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Serializer\Tests\Fixtures;
+
+readonly class ChildClassDummy extends ParentClassDummy
+{
+    public string $childProp;
+}

src/Symfony/Component/Serializer/Tests/Fixtures/ParentClassDummy.php

@@ -0,0 +1,17 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Serializer\Tests\Fixtures;
+
+readonly class ParentClassDummy
+{
+    public string $parentProp;
+}

src/Symfony/Component/Serializer/Tests/Normalizer/PropertyNormalizerTest.php

@@ -30,6 +30,7 @@
 use Symfony\Component\Serializer\SerializerInterface;
 use Symfony\Component\Serializer\Tests\Fixtures\Attributes\GroupDummy;
 use Symfony\Component\Serializer\Tests\Fixtures\Attributes\GroupDummyChild;
+use Symfony\Component\Serializer\Tests\Fixtures\ChildClassDummy;
 use Symfony\Component\Serializer\Tests\Fixtures\Dummy;
 use Symfony\Component\Serializer\Tests\Fixtures\Php74Dummy;
 use Symfony\Component\Serializer\Tests\Fixtures\PropertyCircularReferenceDummy;
@@ -174,6 +175,22 @@ public function testDenormalize()
         $this->assertEquals('bar', $obj->getBar());
     }
 
+    /**
+     * @requires PHP 8.2
+     */
+    public function testDenormalizeWithReadOnlyClass()
+    {
+        /** @var ChildClassDummy $object */
+        $object = $this->normalizer->denormalize(
+            ['parentProp' => 'parentProp', 'childProp' => 'childProp'],
+            ChildClassDummy::class,
+            'any'
+        );
+
+        $this->assertEquals('parentProp', $object->parentProp);
+        $this->assertEquals('childProp', $object->childProp);
+    }
+
     public function testNormalizeWithParentClass()
     {
         $group = new GroupDummyChild();