diff --git a/lib/Doctrine/ORM/Proxy/ProxyFactory.php b/lib/Doctrine/ORM/Proxy/ProxyFactory.php
index c3f9b5fd42e..eeff253eb7e 100644
--- a/lib/Doctrine/ORM/Proxy/ProxyFactory.php
+++ b/lib/Doctrine/ORM/Proxy/ProxyFactory.php
@@ -24,21 +24,13 @@
  */
 class ProxyFactory extends AbstractProxyFactory
 {
-    /** @var EntityManagerInterface The EntityManager this factory is bound to. */
-    private $em;
-
     /** @var UnitOfWork The UnitOfWork this factory uses to retrieve persisters */
-    private $uow;
-
-    /** @var string */
-    private $proxyNs;
+    private UnitOfWork $uow;
 
     /**
      * The IdentifierFlattener used for manipulating identifiers
-     *
-     * @var IdentifierFlattener
      */
-    private $identifierFlattener;
+    private IdentifierFlattener $identifierFlattener;
 
     /**
      * Initializes a new instance of the <tt>ProxyFactory</tt> class that is
@@ -51,23 +43,23 @@ class ProxyFactory extends AbstractProxyFactory
      *                                             values are constants of {@see AbstractProxyFactory}.
      * @psalm-param bool|AutogenerateMode $autoGenerate
      */
-    public function __construct(EntityManagerInterface $em, $proxyDir, $proxyNs, $autoGenerate = AbstractProxyFactory::AUTOGENERATE_NEVER)
-    {
+    public function __construct(
+        /** @var EntityManagerInterface The EntityManager this factory is bound to. */
+        private EntityManagerInterface $em,
+        string $proxyDir,
+        private string $proxyNs,
+        $autoGenerate = AbstractProxyFactory::AUTOGENERATE_NEVER
+    ) {
         $proxyGenerator = new ProxyGenerator($proxyDir, $proxyNs);
 
         $proxyGenerator->setPlaceholder('baseProxyInterface', Proxy::class);
         parent::__construct($proxyGenerator, $em->getMetadataFactory(), $autoGenerate);
 
-        $this->em                  = $em;
         $this->uow                 = $em->getUnitOfWork();
-        $this->proxyNs             = $proxyNs;
         $this->identifierFlattener = new IdentifierFlattener($this->uow, $em->getMetadataFactory());
     }
 
-    /**
-     * {@inheritDoc}
-     */
-    protected function skipClass(ClassMetadata $metadata)
+    protected function skipClass(ClassMetadata $metadata): bool
     {
         return $metadata->isMappedSuperclass
             || $metadata->isEmbeddedClass
@@ -77,7 +69,7 @@ protected function skipClass(ClassMetadata $metadata)
     /**
      * {@inheritDoc}
      */
-    protected function createProxyDefinition($className)
+    protected function createProxyDefinition($className): ProxyDefinition
     {
         $classMetadata   = $this->em->getClassMetadata($className);
         $entityPersister = $this->uow->getEntityPersister($className);
diff --git a/lib/Doctrine/ORM/Tools/AttachEntityListenersListener.php b/lib/Doctrine/ORM/Tools/AttachEntityListenersListener.php
index d1657367eef..72908a86636 100644
--- a/lib/Doctrine/ORM/Tools/AttachEntityListenersListener.php
+++ b/lib/Doctrine/ORM/Tools/AttachEntityListenersListener.php
@@ -14,7 +14,7 @@
 class AttachEntityListenersListener
 {
     /** @var mixed[][] */
-    private $entityListeners = [];
+    private array $entityListeners = [];
 
     /**
      * Adds a entity listener for a specific entity.
@@ -23,11 +23,13 @@ class AttachEntityListenersListener
      * @param string      $listenerClass    The listener class.
      * @param string      $eventName        The entity lifecycle event.
      * @param string|null $listenerCallback The listener callback method or NULL to use $eventName.
-     *
-     * @return void
      */
-    public function addEntityListener($entityClass, $listenerClass, $eventName, $listenerCallback = null)
-    {
+    public function addEntityListener(
+        string $entityClass,
+        string $listenerClass,
+        string $eventName,
+        $listenerCallback = null
+    ): void {
         $this->entityListeners[ltrim($entityClass, '\\')][] = [
             'event'  => $eventName,
             'class'  => $listenerClass,
@@ -37,10 +39,8 @@ public function addEntityListener($entityClass, $listenerClass, $eventName, $lis
 
     /**
      * Processes event and attach the entity listener.
-     *
-     * @return void
      */
-    public function loadClassMetadata(LoadClassMetadataEventArgs $event)
+    public function loadClassMetadata(LoadClassMetadataEventArgs $event): void
     {
         $metadata = $event->getClassMetadata();
 
diff --git a/lib/Doctrine/ORM/Tools/DebugUnitOfWorkListener.php b/lib/Doctrine/ORM/Tools/DebugUnitOfWorkListener.php
index ab8b301c20f..42d25aa9c68 100644
--- a/lib/Doctrine/ORM/Tools/DebugUnitOfWorkListener.php
+++ b/lib/Doctrine/ORM/Tools/DebugUnitOfWorkListener.php
@@ -26,12 +26,6 @@
  */
 class DebugUnitOfWorkListener
 {
-    /** @var string */
-    private $file;
-
-    /** @var string */
-    private $context;
-
     /**
      * Pass a stream and context information for the debugging session.
      *
@@ -40,26 +34,19 @@ class DebugUnitOfWorkListener
      * @param string $file
      * @param string $context
      */
-    public function __construct($file = 'php://output', $context = '')
+    public function __construct(private $file = 'php://output', private $context = '')
     {
-        $this->file    = $file;
-        $this->context = $context;
     }
 
-    /**
-     * @return void
-     */
-    public function onFlush(OnFlushEventArgs $args)
+    public function onFlush(OnFlushEventArgs $args): void
     {
         $this->dumpIdentityMap($args->getEntityManager());
     }
 
     /**
      * Dumps the contents of the identity map into a stream.
-     *
-     * @return void
      */
-    public function dumpIdentityMap(EntityManagerInterface $em)
+    public function dumpIdentityMap(EntityManagerInterface $em): void
     {
         $uow         = $em->getUnitOfWork();
         $identityMap = $uow->getIdentityMap();
@@ -119,10 +106,7 @@ public function dumpIdentityMap(EntityManagerInterface $em)
         fclose($fh);
     }
 
-    /**
-     * @param mixed $var
-     */
-    private function getType($var): string
+    private function getType(mixed $var): string
     {
         if (is_object($var)) {
             $refl = new ReflectionObject($var);
@@ -133,10 +117,7 @@ private function getType($var): string
         return gettype($var);
     }
 
-    /**
-     * @param object $entity
-     */
-    private function getIdString($entity, UnitOfWork $uow): string
+    private function getIdString(object $entity, UnitOfWork $uow): string
     {
         if ($uow->isInIdentityMap($entity)) {
             $ids      = $uow->getEntityIdentifier($entity);
diff --git a/lib/Doctrine/ORM/Tools/ResolveTargetEntityListener.php b/lib/Doctrine/ORM/Tools/ResolveTargetEntityListener.php
index e7f2fb3e469..663c4b681dc 100644
--- a/lib/Doctrine/ORM/Tools/ResolveTargetEntityListener.php
+++ b/lib/Doctrine/ORM/Tools/ResolveTargetEntityListener.php
@@ -23,12 +23,12 @@
 class ResolveTargetEntityListener implements EventSubscriber
 {
     /** @var mixed[][] indexed by original entity name */
-    private $resolveTargetEntities = [];
+    private array $resolveTargetEntities = [];
 
     /**
      * {@inheritDoc}
      */
-    public function getSubscribedEvents()
+    public function getSubscribedEvents(): array
     {
         return [
             Events::loadClassMetadata,
@@ -39,13 +39,9 @@ public function getSubscribedEvents()
     /**
      * Adds a target-entity class name to resolve to a new class name.
      *
-     * @param string $originalEntity
-     * @param string $newEntity
      * @psalm-param array<string, mixed> $mapping
-     *
-     * @return void
      */
-    public function addResolveTargetEntity($originalEntity, $newEntity, array $mapping)
+    public function addResolveTargetEntity(string $originalEntity, string $newEntity, array $mapping): void
     {
         $mapping['targetEntity']                                   = ltrim($newEntity, '\\');
         $this->resolveTargetEntities[ltrim($originalEntity, '\\')] = $mapping;
@@ -53,10 +49,8 @@ public function addResolveTargetEntity($originalEntity, $newEntity, array $mappi
 
     /**
      * @internal this is an event callback, and should not be called directly
-     *
-     * @return void
      */
-    public function onClassMetadataNotFound(OnClassMetadataNotFoundEventArgs $args)
+    public function onClassMetadataNotFound(OnClassMetadataNotFoundEventArgs $args): void
     {
         if (array_key_exists($args->getClassName(), $this->resolveTargetEntities)) {
             $args->setFoundMetadata(
@@ -71,10 +65,8 @@ public function onClassMetadataNotFound(OnClassMetadataNotFoundEventArgs $args)
      * Processes event and resolves new target entity names.
      *
      * @internal this is an event callback, and should not be called directly
-     *
-     * @return void
      */
-    public function loadClassMetadata(LoadClassMetadataEventArgs $args)
+    public function loadClassMetadata(LoadClassMetadataEventArgs $args): void
     {
         $cm = $args->getClassMetadata();
 
diff --git a/lib/Doctrine/ORM/Utility/IdentifierFlattener.php b/lib/Doctrine/ORM/Utility/IdentifierFlattener.php
index 837f2dc1d57..f8291c92396 100644
--- a/lib/Doctrine/ORM/Utility/IdentifierFlattener.php
+++ b/lib/Doctrine/ORM/Utility/IdentifierFlattener.php
@@ -19,27 +19,19 @@
  */
 final class IdentifierFlattener
 {
-    /**
-     * The UnitOfWork used to coordinate object-level transactions.
-     *
-     * @var UnitOfWork
-     */
-    private $unitOfWork;
-
-    /**
-     * The metadata factory, used to retrieve the ORM metadata of entity classes.
-     *
-     * @var ClassMetadataFactory
-     */
-    private $metadataFactory;
-
     /**
      * Initializes a new IdentifierFlattener instance, bound to the given EntityManager.
      */
-    public function __construct(UnitOfWork $unitOfWork, ClassMetadataFactory $metadataFactory)
-    {
-        $this->unitOfWork      = $unitOfWork;
-        $this->metadataFactory = $metadataFactory;
+    public function __construct(
+        /**
+         * The UnitOfWork used to coordinate object-level transactions.
+         */
+        private UnitOfWork $unitOfWork,
+        /**
+         * The metadata factory, used to retrieve the ORM metadata of entity classes.
+         */
+        private ClassMetadataFactory $metadataFactory
+    ) {
     }
 
     /**