[Form] Add resource tracking for type extension classes in FormPass

When a form type extension uses getExtendedTypes() without the extended_type
tag, FormPass calls the static method at build time but does not track the
class as a container resource. This means the cache is not invalidated when
the method is edited.

Call $container->getReflectionClass() before accessing getExtendedTypes()
so that the class is automatically registered as a ReflectionClassResource,
the same pattern used by RegisterListenersPass in the EventDispatcher
component.

Author: ranpafin

Resource/ReflectionClassResource.php

@@ -12,6 +12,7 @@
 namespace Symfony\Component\Config\Resource;
 
 use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+use Symfony\Component\Form\FormTypeExtensionInterface;
 use Symfony\Component\Messenger\Handler\MessageSubscriberInterface;
 use Symfony\Contracts\Service\ServiceSubscriberInterface;
 
@@ -212,5 +213,12 @@ private function generateSignature(\ReflectionClass $class): iterable
             yield ServiceSubscriberInterface::class;
             yield print_r($class->name::getSubscribedServices(), true);
         }
+
+        if (interface_exists(FormTypeExtensionInterface::class, false) && $class->isSubclassOf(FormTypeExtensionInterface::class)) {
+            yield FormTypeExtensionInterface::class;
+            foreach ($class->name::getExtendedTypes() as $key => $value) {
+                yield $key.print_r($value, true);
+            }
+        }
     }
 }