[Serializer] Deprecate annotations

components/property_info.rst

@@ -464,19 +464,30 @@ the :class:`Symfony\\Component\\PropertyInfo\\Extractor\\SerializerExtractor`
 provides list information. This extractor is *not* registered automatically
 with the ``property_info`` service in the Symfony Framework::
 
-    use Doctrine\Common\Annotations\AnnotationReader;
     use Symfony\Component\PropertyInfo\Extractor\SerializerExtractor;
     use Symfony\Component\Serializer\Mapping\Factory\ClassMetadataFactory;
-    use Symfony\Component\Serializer\Mapping\Loader\AnnotationLoader;
+    use Symfony\Component\Serializer\Mapping\Loader\AttributeLoader;
 
-    $serializerClassMetadataFactory = new ClassMetadataFactory(
-        new AnnotationLoader(new AnnotationReader)
-    );
+    $serializerClassMetadataFactory = new ClassMetadataFactory(new AttributeLoader());
     $serializerExtractor = new SerializerExtractor($serializerClassMetadataFactory);
 
     // the `serializer_groups` option must be configured (may be set to null)
     $serializerExtractor->getProperties($class, ['serializer_groups' => ['mygroup']]);
 
+.. versionadded:: 6.4
+
+    The
+    :class:`Symfony\\Component\\Serializer\\Mapping\\Loader\\AttributeLoader`
+    was introduced in Symfony 6.4. Prior to this, the
+    :class:`Symfony\\Component\\Serializer\\Mapping\\Loader\\AnnotationLoader`
+    must be used.
+
+.. deprecated:: 6.4
+
+    The
+    :class:`Symfony\\Component\\Serializer\\Mapping\\Loader\\AnnotationLoader`
+    was deprecated in Symfony 6.4.
+
 If ``serializer_groups`` is set to ``null``, serializer groups metadata won't be
 checked but you will get only the properties considered by the Serializer
 Component (notably the ``@Ignore`` annotation is taken into account).

components/serializer.rst

@@ -279,6 +279,13 @@ for each format:
 
     $classMetadataFactory = new ClassMetadataFactory(new AnnotationLoader(new AnnotationReader()));
 
+* Attributes in PHP files::
+
+    use Symfony\Component\Serializer\Mapping\Factory\ClassMetadataFactory;
+    use Symfony\Component\Serializer\Mapping\Loader\AttributeLoader;
+
+    $classMetadataFactory = new ClassMetadataFactory(new AttributeLoader());
+
 * YAML files::
 
     use Symfony\Component\Serializer\Mapping\Factory\ClassMetadataFactory;
@@ -293,6 +300,21 @@ for each format:
 
     $classMetadataFactory = new ClassMetadataFactory(new XmlFileLoader('/path/to/your/definition.xml'));
 
+.. versionadded:: 6.4
+
+    The
+    :class:`Symfony\\Component\\Serializer\\Mapping\\Loader\\AttributeLoader`
+    was introduced in Symfony 6.4. Prior to this, the
+    :class:`Symfony\\Component\\Serializer\\Mapping\\Loader\\AnnotationLoader`
+    must be used.
+
+.. deprecated:: 6.4
+
+    Reading annotations in PHP files is deprecated since Symfony 6.4.
+    Also, the
+    :class:`Symfony\\Component\\Serializer\\Mapping\\Loader\\AnnotationLoader`
+    was deprecated in Symfony 6.4.
+
 .. _component-serializer-attributes-groups-annotations:
 .. _component-serializer-attributes-groups-attributes:
 
@@ -645,7 +667,7 @@ this is already set up and you only need to provide the configuration. Otherwise
     use Symfony\Component\Serializer\Normalizer\ObjectNormalizer;
     use Symfony\Component\Serializer\Serializer;
 
-    $classMetadataFactory = new ClassMetadataFactory(new AnnotationLoader(new AnnotationReader()));
+    $classMetadataFactory = new ClassMetadataFactory(new AttributeLoader());
 
     $metadataAwareNameConverter = new MetadataAwareNameConverter($classMetadataFactory);
 
@@ -1533,10 +1555,9 @@ Instead of throwing an exception, a custom callable can be executed when the
 maximum depth is reached. This is especially useful when serializing entities
 having unique identifiers::
 
-    use Doctrine\Common\Annotations\AnnotationReader;
     use Symfony\Component\Serializer\Annotation\MaxDepth;
     use Symfony\Component\Serializer\Mapping\Factory\ClassMetadataFactory;
-    use Symfony\Component\Serializer\Mapping\Loader\AnnotationLoader;
+    use Symfony\Component\Serializer\Mapping\Loader\AttributeLoader;
     use Symfony\Component\Serializer\Normalizer\AbstractObjectNormalizer;
     use Symfony\Component\Serializer\Normalizer\ObjectNormalizer;
     use Symfony\Component\Serializer\Serializer;
@@ -1560,7 +1581,7 @@ having unique identifiers::
     $level3->id = 3;
     $level2->child = $level3;
 
-    $classMetadataFactory = new ClassMetadataFactory(new AnnotationLoader(new AnnotationReader()));
+    $classMetadataFactory = new ClassMetadataFactory(new AttributeLoader());
 
     // all callback parameters are optional (you can omit the ones you don't use)
     $maxDepthHandler = function (object $innerObject, object $outerObject, string $attributeName, string $format = null, array $context = []): string {
@@ -1761,7 +1782,7 @@ this is already set up and you only need to provide the configuration. Otherwise
     use Symfony\Component\Serializer\Normalizer\ObjectNormalizer;
     use Symfony\Component\Serializer\Serializer;
 
-    $classMetadataFactory = new ClassMetadataFactory(new AnnotationLoader(new AnnotationReader()));
+    $classMetadataFactory = new ClassMetadataFactory(new AttributeLoader());
 
     $discriminator = new ClassDiscriminatorFromClassMetadata($classMetadataFactory);