diff --git a/lib/Doctrine/ORM/AbstractQuery.php b/lib/Doctrine/ORM/AbstractQuery.php
index 0aa53b09a44..055a2b836ca 100644
--- a/lib/Doctrine/ORM/AbstractQuery.php
+++ b/lib/Doctrine/ORM/AbstractQuery.php
@@ -507,10 +507,8 @@ protected function getResultSetMapping()
 
     /**
      * Allows to translate entity namespaces to full qualified names.
-     *
-     * @return void
      */
-    private function translateNamespaces(Query\ResultSetMapping $rsm)
+    private function translateNamespaces(Query\ResultSetMapping $rsm): void
     {
         $translate = function ($alias): string {
             return $this->_em->getClassMetadata($alias)->getName();
@@ -1137,10 +1135,7 @@ private function executeUsingQueryCache($parameters = null, $hydrationMode = nul
         return $result;
     }
 
-    /**
-     * @return TimestampCacheKey|null
-     */
-    private function getTimestampKey()
+    private function getTimestampKey(): ?TimestampCacheKey
     {
         $entityName = reset($this->_resultSetMapping->aliasMap);
 
diff --git a/lib/Doctrine/ORM/Cache/DefaultCache.php b/lib/Doctrine/ORM/Cache/DefaultCache.php
index 54c933799cc..fe8ba92f4df 100644
--- a/lib/Doctrine/ORM/Cache/DefaultCache.php
+++ b/lib/Doctrine/ORM/Cache/DefaultCache.php
@@ -278,10 +278,8 @@ public function getQueryCache($regionName = null)
      /**
       * @param ClassMetadata $metadata   The entity metadata.
       * @param mixed         $identifier The entity identifier.
-      *
-      * @return EntityCacheKey
       */
-    private function buildEntityCacheKey(ClassMetadata $metadata, $identifier)
+    private function buildEntityCacheKey(ClassMetadata $metadata, $identifier): EntityCacheKey
     {
         if (! is_array($identifier)) {
             $identifier = $this->toIdentifierArray($metadata, $identifier);
@@ -294,11 +292,12 @@ private function buildEntityCacheKey(ClassMetadata $metadata, $identifier)
      * @param ClassMetadata $metadata        The entity metadata.
      * @param string        $association     The field name that represents the association.
      * @param mixed         $ownerIdentifier The identifier of the owning entity.
-     *
-     * @return CollectionCacheKey
      */
-    private function buildCollectionCacheKey(ClassMetadata $metadata, $association, $ownerIdentifier)
-    {
+    private function buildCollectionCacheKey(
+        ClassMetadata $metadata,
+        string $association,
+        $ownerIdentifier
+    ): CollectionCacheKey {
         if (! is_array($ownerIdentifier)) {
             $ownerIdentifier = $this->toIdentifierArray($metadata, $ownerIdentifier);
         }
@@ -312,7 +311,7 @@ private function buildCollectionCacheKey(ClassMetadata $metadata, $association,
      *
      * @return array<string, mixed>
      */
-    private function toIdentifierArray(ClassMetadata $metadata, $identifier)
+    private function toIdentifierArray(ClassMetadata $metadata, $identifier): array
     {
         if (is_object($identifier) && $this->em->getMetadataFactory()->hasMetadataFor(ClassUtils::getClass($identifier))) {
             $identifier = $this->uow->getSingleIdentifierValue($identifier);
diff --git a/lib/Doctrine/ORM/Cache/DefaultCacheFactory.php b/lib/Doctrine/ORM/Cache/DefaultCacheFactory.php
index 45f3a88584d..f265c7a6261 100644
--- a/lib/Doctrine/ORM/Cache/DefaultCacheFactory.php
+++ b/lib/Doctrine/ORM/Cache/DefaultCacheFactory.php
@@ -207,12 +207,7 @@ public function getRegion(array $cache)
         return $this->regions[$cache['region']] = $region;
     }
 
-    /**
-     * @param string $name
-     *
-     * @return CacheAdapter
-     */
-    private function createRegionCache($name)
+    private function createRegionCache(string $name): CacheAdapter
     {
         $cacheAdapter = clone $this->cache;
 
diff --git a/lib/Doctrine/ORM/Cache/DefaultQueryCache.php b/lib/Doctrine/ORM/Cache/DefaultQueryCache.php
index 8d31931dbac..b4c97fdb8a8 100644
--- a/lib/Doctrine/ORM/Cache/DefaultQueryCache.php
+++ b/lib/Doctrine/ORM/Cache/DefaultQueryCache.php
@@ -344,11 +344,9 @@ public function put(QueryCacheKey $key, ResultSetMapping $rsm, $result, array $h
      * @param array<string,mixed> $assoc
      * @param mixed               $assocValue
      *
-     * @return mixed[]|null
-     *
      * @psalm-return array{targetEntity: string, type: mixed, list?: array[], identifier?: array}|null
      */
-    private function storeAssociationCache(QueryCacheKey $key, array $assoc, $assocValue)
+    private function storeAssociationCache(QueryCacheKey $key, array $assoc, $assocValue): ?array
     {
         $assocPersister = $this->uow->getEntityPersister($assoc['targetEntity']);
         $assocMetadata  = $assocPersister->getClassMetadata();
@@ -398,13 +396,13 @@ private function storeAssociationCache(QueryCacheKey $key, array $assoc, $assocV
     }
 
     /**
-     * @param string $assocAlias
-     * @param object $entity
-     *
      * @return array<object>|object
      */
-    private function getAssociationValue(ResultSetMapping $rsm, $assocAlias, $entity)
-    {
+    private function getAssociationValue(
+        ResultSetMapping $rsm,
+        string $assocAlias,
+        object $entity
+    ) {
         $path  = [];
         $alias = $assocAlias;
 
diff --git a/lib/Doctrine/ORM/Cache/Persister/Entity/AbstractEntityPersister.php b/lib/Doctrine/ORM/Cache/Persister/Entity/AbstractEntityPersister.php
index 5e96c309c63..25e24e73e8e 100644
--- a/lib/Doctrine/ORM/Cache/Persister/Entity/AbstractEntityPersister.php
+++ b/lib/Doctrine/ORM/Cache/Persister/Entity/AbstractEntityPersister.php
@@ -223,10 +223,7 @@ public function storeEntityCache($entity, EntityCacheKey $key)
         return $cached;
     }
 
-    /**
-     * @param object $entity
-     */
-    private function storeJoinedAssociations($entity)
+    private function storeJoinedAssociations(object $entity): void
     {
         if ($this->joinedAssociations === null) {
             $associations = [];
diff --git a/lib/Doctrine/ORM/Cache/Persister/Entity/NonStrictReadWriteCachedEntityPersister.php b/lib/Doctrine/ORM/Cache/Persister/Entity/NonStrictReadWriteCachedEntityPersister.php
index c2b36c18d00..0cafd632090 100644
--- a/lib/Doctrine/ORM/Cache/Persister/Entity/NonStrictReadWriteCachedEntityPersister.php
+++ b/lib/Doctrine/ORM/Cache/Persister/Entity/NonStrictReadWriteCachedEntityPersister.php
@@ -98,13 +98,7 @@ public function update($entity)
         $this->queuedCache['update'][] = $entity;
     }
 
-    /**
-     * @param object $entity
-     * @param bool   $isChanged
-     *
-     * @return bool
-     */
-    private function updateCache($entity, $isChanged)
+    private function updateCache(object $entity, bool $isChanged): ?bool
     {
         $class     = $this->metadataFactory->getMetadataFor(get_class($entity));
         $key       = new EntityCacheKey($class->rootEntityName, $this->uow->getEntityIdentifier($entity));
diff --git a/lib/Doctrine/ORM/Cache/Region/FileLockRegion.php b/lib/Doctrine/ORM/Cache/Region/FileLockRegion.php
index 2a09b3c1b0c..a60b8d58505 100644
--- a/lib/Doctrine/ORM/Cache/Region/FileLockRegion.php
+++ b/lib/Doctrine/ORM/Cache/Region/FileLockRegion.php
@@ -83,10 +83,7 @@ public function __construct(Region $region, $directory, $lockLifetime)
         $this->lockLifetime = $lockLifetime;
     }
 
-    /**
-     * @return bool
-     */
-    private function isLocked(CacheKey $key, ?Lock $lock = null)
+    private function isLocked(CacheKey $key, ?Lock $lock = null): bool
     {
         $filename = $this->getLockFileName($key);
 
@@ -117,30 +114,23 @@ private function isLocked(CacheKey $key, ?Lock $lock = null)
         return true;
     }
 
-    /**
-     * @return string
-     */
-    private function getLockFileName(CacheKey $key)
+    private function getLockFileName(CacheKey $key): string
     {
         return $this->directory . DIRECTORY_SEPARATOR . $key->hash . '.' . self::LOCK_EXTENSION;
     }
 
     /**
-     * @param string $filename
-     *
-     * @return string
+     * @return string|false
      */
-    private function getLockContent($filename)
+    private function getLockContent(string $filename)
     {
         return @file_get_contents($filename);
     }
 
     /**
-     * @param string $filename
-     *
-     * @return int
+     * @return int|false
      */
-    private function getLockTime($filename)
+    private function getLockTime(string $filename)
     {
         return @fileatime($filename);
     }
diff --git a/lib/Doctrine/ORM/Cache/TimestampQueryCacheValidator.php b/lib/Doctrine/ORM/Cache/TimestampQueryCacheValidator.php
index 196c4e1e0f2..a9cb6f07a7f 100644
--- a/lib/Doctrine/ORM/Cache/TimestampQueryCacheValidator.php
+++ b/lib/Doctrine/ORM/Cache/TimestampQueryCacheValidator.php
@@ -48,10 +48,7 @@ public function isValid(QueryCacheKey $key, QueryCacheEntry $entry)
         return $entry->time + $key->lifetime > microtime(true);
     }
 
-    /**
-     * @return bool
-     */
-    private function regionUpdated(QueryCacheKey $key, QueryCacheEntry $entry)
+    private function regionUpdated(QueryCacheKey $key, QueryCacheEntry $entry): bool
     {
         if ($key->timestampKey === null) {
             return false;
diff --git a/lib/Doctrine/ORM/EntityManager.php b/lib/Doctrine/ORM/EntityManager.php
index 66216dda028..8f4ba65a9ae 100644
--- a/lib/Doctrine/ORM/EntityManager.php
+++ b/lib/Doctrine/ORM/EntityManager.php
@@ -799,11 +799,9 @@ public function getConfiguration()
     /**
      * Throws an exception if the EntityManager is closed or currently not active.
      *
-     * @return void
-     *
      * @throws ORMException If the EntityManager is closed.
      */
-    private function errorIfClosed()
+    private function errorIfClosed(): void
     {
         if ($this->closed) {
             throw ORMException::entityManagerClosed();
diff --git a/lib/Doctrine/ORM/Event/PreUpdateEventArgs.php b/lib/Doctrine/ORM/Event/PreUpdateEventArgs.php
index 0f08dec473f..e0ab9155423 100644
--- a/lib/Doctrine/ORM/Event/PreUpdateEventArgs.php
+++ b/lib/Doctrine/ORM/Event/PreUpdateEventArgs.php
@@ -113,13 +113,9 @@ public function setNewValue($field, $value)
     /**
      * Asserts the field exists in changeset.
      *
-     * @param string $field
-     *
-     * @return void
-     *
      * @throws InvalidArgumentException
      */
-    private function assertValidField($field)
+    private function assertValidField(string $field): void
     {
         if (! isset($this->entityChangeSet[$field])) {
             throw new InvalidArgumentException(sprintf(
diff --git a/lib/Doctrine/ORM/Internal/CommitOrderCalculator.php b/lib/Doctrine/ORM/Internal/CommitOrderCalculator.php
index 589a3a08776..a099d432466 100644
--- a/lib/Doctrine/ORM/Internal/CommitOrderCalculator.php
+++ b/lib/Doctrine/ORM/Internal/CommitOrderCalculator.php
@@ -146,10 +146,8 @@ public function sort()
      * Visit a given node definition for reordering.
      *
      * {@internal Highly performance-sensitive method.}
-     *
-     * @param stdClass $vertex
      */
-    private function visit($vertex)
+    private function visit(stdClass $vertex): void
     {
         $vertex->state = self::IN_PROGRESS;
 
diff --git a/lib/Doctrine/ORM/Internal/Hydration/ArrayHydrator.php b/lib/Doctrine/ORM/Internal/Hydration/ArrayHydrator.php
index 80772e8e0d9..c5a6c050246 100644
--- a/lib/Doctrine/ORM/Internal/Hydration/ArrayHydrator.php
+++ b/lib/Doctrine/ORM/Internal/Hydration/ArrayHydrator.php
@@ -261,13 +261,14 @@ protected function hydrateRowData(array $row, array &$result)
      *
      * @param mixed[]  $coll     The element.
      * @param bool|int $index    Index of the element in the collection.
-     * @param string   $dqlAlias
      * @param bool     $oneToOne Whether it is a single-valued association or not.
-     *
-     * @return void
      */
-    private function updateResultPointer(array &$coll, $index, $dqlAlias, $oneToOne)
-    {
+    private function updateResultPointer(
+        array &$coll,
+        $index,
+        string $dqlAlias,
+        bool $oneToOne
+    ): void {
         if ($coll === null) {
             unset($this->_resultPointers[$dqlAlias]); // Ticket #1228
 
diff --git a/lib/Doctrine/ORM/Internal/Hydration/ObjectHydrator.php b/lib/Doctrine/ORM/Internal/Hydration/ObjectHydrator.php
index 69cd75a8f1e..c9f8ca44a49 100644
--- a/lib/Doctrine/ORM/Internal/Hydration/ObjectHydrator.php
+++ b/lib/Doctrine/ORM/Internal/Hydration/ObjectHydrator.php
@@ -171,15 +171,16 @@ protected function hydrateAllData()
     /**
      * Initializes a related collection.
      *
-     * @param object        $entity         The entity to which the collection belongs.
-     * @param ClassMetadata $class
-     * @param string        $fieldName      The name of the field on the entity that holds the collection.
-     * @param string        $parentDqlAlias Alias of the parent fetch joining this collection.
-     *
-     * @return PersistentCollection
+     * @param object $entity         The entity to which the collection belongs.
+     * @param string $fieldName      The name of the field on the entity that holds the collection.
+     * @param string $parentDqlAlias Alias of the parent fetch joining this collection.
      */
-    private function initRelatedCollection($entity, $class, $fieldName, $parentDqlAlias)
-    {
+    private function initRelatedCollection(
+        object $entity,
+        ClassMetadata $class,
+        string $fieldName,
+        string $parentDqlAlias
+    ): PersistentCollection {
         $oid      = spl_object_hash($entity);
         $relation = $class->associationMappings[$fieldName];
         $value    = $class->reflFields[$fieldName]->getValue($entity);
@@ -224,13 +225,11 @@ private function initRelatedCollection($entity, $class, $fieldName, $parentDqlAl
      *
      * @param string $dqlAlias The DQL alias of the entity's class.
      *
-     * @return object The entity.
-     *
      * @throws HydrationException
      *
      * @psalm-param array<string, mixed> $data     The instance data.
      */
-    private function getEntity(array $data, $dqlAlias)
+    private function getEntity(array $data, string $dqlAlias): object
     {
         $className = $this->_rsm->aliasMap[$dqlAlias];
 
@@ -273,13 +272,11 @@ private function getEntity(array $data, $dqlAlias)
     }
 
     /**
-     * @param string $className
-     *
      * @return mixed
      *
      * @psalm-param array<string, mixed> $data
      */
-    private function getEntityFromIdentityMap($className, array $data)
+    private function getEntityFromIdentityMap(string $className, array $data)
     {
         // TODO: Abstract this code and UnitOfWork::createEntity() equivalent?
         $class = $this->_metadataCache[$className];
diff --git a/lib/Doctrine/ORM/Internal/HydrationCompleteHandler.php b/lib/Doctrine/ORM/Internal/HydrationCompleteHandler.php
index 01185aa777e..7632ae3d123 100644
--- a/lib/Doctrine/ORM/Internal/HydrationCompleteHandler.php
+++ b/lib/Doctrine/ORM/Internal/HydrationCompleteHandler.php
@@ -55,7 +55,7 @@ public function __construct(ListenersInvoker $listenersInvoker, EntityManagerInt
      *
      * @param object $entity
      */
-    public function deferPostLoadInvoking(ClassMetadata $class, $entity)
+    public function deferPostLoadInvoking(ClassMetadata $class, $entity): void
     {
         $invoke = $this->listenersInvoker->getSubscribedSystems($class, Events::postLoad);
 
@@ -71,7 +71,7 @@ public function deferPostLoadInvoking(ClassMetadata $class, $entity)
      *
      * Method fires all deferred invocations of postLoad events
      */
-    public function hydrationComplete()
+    public function hydrationComplete(): void
     {
         $toInvoke                          = $this->deferredPostLoadInvocations;
         $this->deferredPostLoadInvocations = [];
diff --git a/lib/Doctrine/ORM/Mapping/ClassMetadataFactory.php b/lib/Doctrine/ORM/Mapping/ClassMetadataFactory.php
index cd821151319..9739d1573f9 100644
--- a/lib/Doctrine/ORM/Mapping/ClassMetadataFactory.php
+++ b/lib/Doctrine/ORM/Mapping/ClassMetadataFactory.php
@@ -61,7 +61,7 @@ class ClassMetadataFactory extends AbstractClassMetadataFactory
     /** @var EntityManagerInterface|null */
     private $em;
 
-    /** @var AbstractPlatform */
+    /** @var AbstractPlatform|null */
     private $targetPlatform;
 
     /** @var MappingDriver */
@@ -307,11 +307,9 @@ protected function newClassMetadataInstance($className)
      * Populates the discriminator value of the given metadata (if not set) by iterating over discriminator
      * map classes and looking for a fitting one.
      *
-     * @return void
-     *
      * @throws MappingException
      */
-    private function resolveDiscriminatorValue(ClassMetadata $metadata)
+    private function resolveDiscriminatorValue(ClassMetadata $metadata): void
     {
         if (
             $metadata->discriminatorValue
@@ -356,7 +354,7 @@ private function resolveDiscriminatorValue(ClassMetadata $metadata)
      *
      * @throws MappingException
      */
-    private function addDefaultDiscriminatorMap(ClassMetadata $class)
+    private function addDefaultDiscriminatorMap(ClassMetadata $class): void
     {
         $allClasses = $this->driver->getAllClassNames();
         $fqcn       = $class->getName();
@@ -384,12 +382,8 @@ private function addDefaultDiscriminatorMap(ClassMetadata $class)
 
     /**
      * Gets the lower-case short name of a class.
-     *
-     * @param string $className
-     *
-     * @return string
      */
-    private function getShortName($className)
+    private function getShortName(string $className): string
     {
         if (strpos($className, '\\') === false) {
             return strtolower($className);
@@ -402,10 +396,8 @@ private function getShortName($className)
 
     /**
      * Adds inherited fields to the subclass mapping.
-     *
-     * @return void
      */
-    private function addInheritedFields(ClassMetadata $subClass, ClassMetadata $parentClass)
+    private function addInheritedFields(ClassMetadata $subClass, ClassMetadata $parentClass): void
     {
         foreach ($parentClass->fieldMappings as $mapping) {
             if (! isset($mapping['inherited']) && ! $parentClass->isMappedSuperclass) {
@@ -427,11 +419,9 @@ private function addInheritedFields(ClassMetadata $subClass, ClassMetadata $pare
     /**
      * Adds inherited association mappings to the subclass mapping.
      *
-     * @return void
-     *
      * @throws MappingException
      */
-    private function addInheritedRelations(ClassMetadata $subClass, ClassMetadata $parentClass)
+    private function addInheritedRelations(ClassMetadata $subClass, ClassMetadata $parentClass): void
     {
         foreach ($parentClass->associationMappings as $field => $mapping) {
             if ($parentClass->isMappedSuperclass) {
@@ -455,7 +445,7 @@ private function addInheritedRelations(ClassMetadata $subClass, ClassMetadata $p
         }
     }
 
-    private function addInheritedEmbeddedClasses(ClassMetadata $subClass, ClassMetadata $parentClass)
+    private function addInheritedEmbeddedClasses(ClassMetadata $subClass, ClassMetadata $parentClass): void
     {
         foreach ($parentClass->embeddedClasses as $field => $embeddedClass) {
             if (! isset($embeddedClass['inherited']) && ! $parentClass->isMappedSuperclass) {
@@ -477,8 +467,11 @@ private function addInheritedEmbeddedClasses(ClassMetadata $subClass, ClassMetad
      * @param ClassMetadata $parentClass Parent class to add nested embedded classes metadata to.
      * @param string        $prefix      Embedded classes' prefix to use for nested embedded classes field names.
      */
-    private function addNestedEmbeddedClasses(ClassMetadata $subClass, ClassMetadata $parentClass, $prefix)
-    {
+    private function addNestedEmbeddedClasses(
+        ClassMetadata $subClass,
+        ClassMetadata $parentClass,
+        string $prefix
+    ): void {
         foreach ($subClass->embeddedClasses as $property => $embeddableClass) {
             if (isset($embeddableClass['inherited'])) {
                 continue;
@@ -502,10 +495,8 @@ private function addNestedEmbeddedClasses(ClassMetadata $subClass, ClassMetadata
 
     /**
      * Copy the table indices from the parent class superclass to the child class
-     *
-     * @return void
      */
-    private function addInheritedIndexes(ClassMetadata $subClass, ClassMetadata $parentClass)
+    private function addInheritedIndexes(ClassMetadata $subClass, ClassMetadata $parentClass): void
     {
         if (! $parentClass->isMappedSuperclass) {
             return;
@@ -526,10 +517,8 @@ private function addInheritedIndexes(ClassMetadata $subClass, ClassMetadata $par
 
     /**
      * Adds inherited named queries to the subclass mapping.
-     *
-     * @return void
      */
-    private function addInheritedNamedQueries(ClassMetadata $subClass, ClassMetadata $parentClass)
+    private function addInheritedNamedQueries(ClassMetadata $subClass, ClassMetadata $parentClass): void
     {
         foreach ($parentClass->namedQueries as $name => $query) {
             if (! isset($subClass->namedQueries[$name])) {
@@ -545,10 +534,8 @@ private function addInheritedNamedQueries(ClassMetadata $subClass, ClassMetadata
 
     /**
      * Adds inherited named native queries to the subclass mapping.
-     *
-     * @return void
      */
-    private function addInheritedNamedNativeQueries(ClassMetadata $subClass, ClassMetadata $parentClass)
+    private function addInheritedNamedNativeQueries(ClassMetadata $subClass, ClassMetadata $parentClass): void
     {
         foreach ($parentClass->namedNativeQueries as $name => $query) {
             if (! isset($subClass->namedNativeQueries[$name])) {
@@ -567,10 +554,8 @@ private function addInheritedNamedNativeQueries(ClassMetadata $subClass, ClassMe
 
     /**
      * Adds inherited sql result set mappings to the subclass mapping.
-     *
-     * @return void
      */
-    private function addInheritedSqlResultSetMappings(ClassMetadata $subClass, ClassMetadata $parentClass)
+    private function addInheritedSqlResultSetMappings(ClassMetadata $subClass, ClassMetadata $parentClass): void
     {
         foreach ($parentClass->sqlResultSetMappings as $name => $mapping) {
             if (! isset($subClass->sqlResultSetMappings[$name])) {
@@ -599,11 +584,9 @@ private function addInheritedSqlResultSetMappings(ClassMetadata $subClass, Class
      * Completes the ID generator mapping. If "auto" is specified we choose the generator
      * most appropriate for the targeted database platform.
      *
-     * @return void
-     *
      * @throws ORMException
      */
-    private function completeIdGeneratorMapping(ClassMetadataInfo $class)
+    private function completeIdGeneratorMapping(ClassMetadataInfo $class): void
     {
         $idGenType = $class->generatorType;
         if ($idGenType === ClassMetadata::GENERATOR_TYPE_AUTO) {
@@ -715,7 +698,7 @@ private function completeIdGeneratorMapping(ClassMetadataInfo $class)
     /**
      * Inherits the ID generator mapping from a parent class.
      */
-    private function inheritIdGeneratorMapping(ClassMetadataInfo $class, ClassMetadataInfo $parent)
+    private function inheritIdGeneratorMapping(ClassMetadataInfo $class, ClassMetadataInfo $parent): void
     {
         if ($parent->isIdGeneratorSequence()) {
             $class->setSequenceGeneratorDefinition($parent->sequenceGeneratorDefinition);
@@ -774,10 +757,7 @@ protected function isEntity(ClassMetadataInterface $class)
         return isset($class->isMappedSuperclass) && $class->isMappedSuperclass === false;
     }
 
-    /**
-     * @return Platforms\AbstractPlatform
-     */
-    private function getTargetPlatform()
+    private function getTargetPlatform(): Platforms\AbstractPlatform
     {
         if (! $this->targetPlatform) {
             $this->targetPlatform = $this->em->getConnection()->getDatabasePlatform();
diff --git a/lib/Doctrine/ORM/Mapping/ClassMetadataInfo.php b/lib/Doctrine/ORM/Mapping/ClassMetadataInfo.php
index d9867f88dc5..6397406df85 100644
--- a/lib/Doctrine/ORM/Mapping/ClassMetadataInfo.php
+++ b/lib/Doctrine/ORM/Mapping/ClassMetadataInfo.php
@@ -2539,11 +2539,9 @@ public function setPrimaryTable(array $table)
     /**
      * Checks whether the given type identifies an inheritance type.
      *
-     * @param int $type
-     *
-     * @return bool TRUE if the given type identifies an inheritance type, FALSe otherwise.
+     * @return bool TRUE if the given type identifies an inheritance type, FALSE otherwise.
      */
-    private function isInheritanceType($type)
+    private function isInheritanceType(int $type): bool
     {
         return $type === self::INHERITANCE_TYPE_NONE ||
                 $type === self::INHERITANCE_TYPE_SINGLE_TABLE ||
diff --git a/lib/Doctrine/ORM/Mapping/Driver/AnnotationDriver.php b/lib/Doctrine/ORM/Mapping/Driver/AnnotationDriver.php
index 05f4e536820..9e5a00d5e0e 100644
--- a/lib/Doctrine/ORM/Mapping/Driver/AnnotationDriver.php
+++ b/lib/Doctrine/ORM/Mapping/Driver/AnnotationDriver.php
@@ -598,14 +598,11 @@ private function loadRelationShipMapping(
     /**
      * Attempts to resolve the fetch mode.
      *
-     * @param string $className The class name.
-     * @param string $fetchMode The fetch mode.
-     *
-     * @return int The fetch mode as defined in ClassMetadata.
-     *
      * @throws MappingException If the fetch mode is not valid.
+     *
+     * @psalm-return \Doctrine\ORM\Mapping\ClassMetadata::FETCH_* The fetch mode as defined in ClassMetadata.
      */
-    private function getFetchMode($className, $fetchMode)
+    private function getFetchMode(string $className, string $fetchMode): int
     {
         if (! defined('Doctrine\ORM\Mapping\ClassMetadata::FETCH_' . $fetchMode)) {
             throw MappingException::invalidFetchMode($className, $fetchMode);
@@ -621,7 +618,7 @@ private function getFetchMode($className, $fetchMode)
      *
      * @psalm-return list<callable-array>
      */
-    private function getMethodCallbacks(ReflectionMethod $method)
+    private function getMethodCallbacks(ReflectionMethod $method): array
     {
         $callbacks   = [];
         $annotations = $this->reader->getMethodAnnotations($method);
@@ -666,8 +663,6 @@ private function getMethodCallbacks(ReflectionMethod $method)
     /**
      * Parse the given JoinColumn as array
      *
-     * @return mixed[]
-     *
      * @psalm-return array{
      *                   name: string,
      *                   unique: bool,
@@ -677,7 +672,7 @@ private function getMethodCallbacks(ReflectionMethod $method)
      *                   referencedColumnName: string
      *               }
      */
-    private function joinColumnToArray(Mapping\JoinColumn $joinColumn)
+    private function joinColumnToArray(Mapping\JoinColumn $joinColumn): array
     {
         return [
             'name' => $joinColumn->name,
@@ -692,10 +687,6 @@ private function joinColumnToArray(Mapping\JoinColumn $joinColumn)
     /**
      * Parse the given Column as array
      *
-     * @param string $fieldName
-     *
-     * @return mixed[]
-     *
      * @psalm-return array{
      *                   fieldName: string,
      *                   type: mixed,
@@ -709,7 +700,7 @@ private function joinColumnToArray(Mapping\JoinColumn $joinColumn)
      *                   columnDefinition?: string
      *               }
      */
-    private function columnToArray($fieldName, Mapping\Column $column)
+    private function columnToArray(string $fieldName, Mapping\Column $column): array
     {
         $mapping = [
             'fieldName' => $fieldName,
diff --git a/lib/Doctrine/ORM/Mapping/Driver/DatabaseDriver.php b/lib/Doctrine/ORM/Mapping/Driver/DatabaseDriver.php
index 190bfb2bbe4..c6a4433135d 100644
--- a/lib/Doctrine/ORM/Mapping/Driver/DatabaseDriver.php
+++ b/lib/Doctrine/ORM/Mapping/Driver/DatabaseDriver.php
@@ -259,11 +259,9 @@ public function loadMetadataForClass($className, ClassMetadata $metadata)
     }
 
     /**
-     * @return void
-     *
      * @throws MappingException
      */
-    private function reverseEngineerMappingFromDatabase()
+    private function reverseEngineerMappingFromDatabase(): void
     {
         if ($this->tables !== null) {
             return;
@@ -316,7 +314,7 @@ private function reverseEngineerMappingFromDatabase()
     /**
      * Build indexes from a class metadata.
      */
-    private function buildIndexes(ClassMetadataInfo $metadata)
+    private function buildIndexes(ClassMetadataInfo $metadata): void
     {
         $tableName = $metadata->table['name'];
         $indexes   = $this->tables[$tableName]->getIndexes();
@@ -339,7 +337,7 @@ private function buildIndexes(ClassMetadataInfo $metadata)
     /**
      * Build field mapping from class metadata.
      */
-    private function buildFieldMappings(ClassMetadataInfo $metadata)
+    private function buildFieldMappings(ClassMetadataInfo $metadata): void
     {
         $tableName      = $metadata->table['name'];
         $columns        = $this->tables[$tableName]->getColumns();
@@ -382,8 +380,6 @@ private function buildFieldMappings(ClassMetadataInfo $metadata)
     /**
      * Build field mapping from a schema column definition
      *
-     * @param string $tableName
-     *
      * @psalm-return array{
      *                   fieldName: string,
      *                   columnName: string,
@@ -400,7 +396,7 @@ private function buildFieldMappings(ClassMetadataInfo $metadata)
      *                   length?: int|null
      *               }
      */
-    private function buildFieldMapping($tableName, Column $column)
+    private function buildFieldMapping(string $tableName, Column $column): array
     {
         $fieldMapping = [
             'fieldName'  => $this->getFieldNameForColumn($tableName, $column->getName(), false),
@@ -501,7 +497,7 @@ private function buildToOneAssociationMappings(ClassMetadataInfo $metadata)
      *
      * @psalm-return array<string, ForeignKeyConstraint>
      */
-    private function getTableForeignKeys(Table $table)
+    private function getTableForeignKeys(Table $table): array
     {
         return $this->_sm->getDatabasePlatform()->supportsForeignKeyConstraints()
             ? $table->getForeignKeys()
@@ -513,7 +509,7 @@ private function getTableForeignKeys(Table $table)
      *
      * @return string[]
      */
-    private function getTablePrimaryKeys(Table $table)
+    private function getTablePrimaryKeys(Table $table): array
     {
         try {
             return $table->getPrimaryKey()->getColumns();
@@ -526,12 +522,8 @@ private function getTablePrimaryKeys(Table $table)
 
     /**
      * Returns the mapped class name for a table if it exists. Otherwise return "classified" version.
-     *
-     * @param string $tableName
-     *
-     * @return string
      */
-    private function getClassNameForTable($tableName)
+    private function getClassNameForTable(string $tableName): string
     {
         if (isset($this->classNamesForTables[$tableName])) {
             return $this->namespace . $this->classNamesForTables[$tableName];
@@ -543,14 +535,13 @@ private function getClassNameForTable($tableName)
     /**
      * Return the mapped field name for a column, if it exists. Otherwise return camelized version.
      *
-     * @param string $tableName
-     * @param string $columnName
-     * @param bool   $fk         Whether the column is a foreignkey or not.
-     *
-     * @return string
+     * @param bool $fk Whether the column is a foreignkey or not.
      */
-    private function getFieldNameForColumn($tableName, $columnName, $fk = false)
-    {
+    private function getFieldNameForColumn(
+        string $tableName,
+        string $columnName,
+        bool $fk = false
+    ): string {
         if (isset($this->fieldNamesForColumns[$tableName]) && isset($this->fieldNamesForColumns[$tableName][$columnName])) {
             return $this->fieldNamesForColumns[$tableName][$columnName];
         }
diff --git a/lib/Doctrine/ORM/Mapping/Driver/XmlDriver.php b/lib/Doctrine/ORM/Mapping/Driver/XmlDriver.php
index 27be9209ebf..c8dfcdceb6f 100644
--- a/lib/Doctrine/ORM/Mapping/Driver/XmlDriver.php
+++ b/lib/Doctrine/ORM/Mapping/Driver/XmlDriver.php
@@ -681,7 +681,7 @@ public function loadMetadataForClass($className, ClassMetadata $metadata)
      *
      * @return mixed[] The options array.
      */
-    private function parseOptions(SimpleXMLElement $options)
+    private function parseOptions(SimpleXMLElement $options): array
     {
         $array = [];
 
@@ -724,7 +724,7 @@ private function parseOptions(SimpleXMLElement $options)
      *                   columnDefinition?: string
      *               }
      */
-    private function joinColumnToArray(SimpleXMLElement $joinColumnElement)
+    private function joinColumnToArray(SimpleXMLElement $joinColumnElement): array
     {
         $joinColumn = [
             'name' => (string) $joinColumnElement['name'],
@@ -753,8 +753,6 @@ private function joinColumnToArray(SimpleXMLElement $joinColumnElement)
      /**
       * Parses the given field as array.
       *
-      * @return mixed[]
-      *
       * @psalm-return array{
       *                   fieldName: string,
       *                   type?: string,
@@ -769,7 +767,7 @@ private function joinColumnToArray(SimpleXMLElement $joinColumnElement)
       *                   options?: array
       *               }
       */
-    private function columnToArray(SimpleXMLElement $fieldMapping)
+    private function columnToArray(SimpleXMLElement $fieldMapping): array
     {
         $mapping = [
             'fieldName' => (string) $fieldMapping['name'],
@@ -821,11 +819,9 @@ private function columnToArray(SimpleXMLElement $fieldMapping)
     /**
      * Parse / Normalize the cache configuration
      *
-     * @return mixed[]
-     *
      * @psalm-return array{usage: mixed, region: string|null}
      */
-    private function cacheToArray(SimpleXMLElement $cacheMapping)
+    private function cacheToArray(SimpleXMLElement $cacheMapping): array
     {
         $region = isset($cacheMapping['region']) ? (string) $cacheMapping['region'] : null;
         $usage  = isset($cacheMapping['usage']) ? strtoupper($cacheMapping['usage']) : null;
@@ -853,7 +849,7 @@ private function cacheToArray(SimpleXMLElement $cacheMapping)
      *
      * @psalm-return list<string>
      */
-    private function getCascadeMappings(SimpleXMLElement $cascadeElement)
+    private function getCascadeMappings(SimpleXMLElement $cascadeElement): array
     {
         $cascades = [];
         foreach ($cascadeElement->children() as $action) {
diff --git a/lib/Doctrine/ORM/Mapping/Driver/YamlDriver.php b/lib/Doctrine/ORM/Mapping/Driver/YamlDriver.php
index 1f76be2031d..d0433f1721a 100644
--- a/lib/Doctrine/ORM/Mapping/Driver/YamlDriver.php
+++ b/lib/Doctrine/ORM/Mapping/Driver/YamlDriver.php
@@ -837,7 +837,7 @@ private function columnToArray(string $fieldName, ?array $column): array
      * @psalm-param array{usage: mixed, region: (string|null)} $cacheMapping
      * @psalm-return array{usage: mixed, region: (string|null)}
      */
-    private function cacheToArray($cacheMapping)
+    private function cacheToArray(array $cacheMapping): array
     {
         $region = isset($cacheMapping['region']) ? (string) $cacheMapping['region'] : null;
         $usage  = isset($cacheMapping['usage']) ? strtoupper($cacheMapping['usage']) : null;
diff --git a/lib/Doctrine/ORM/Mapping/Reflection/ReflectionPropertiesGetter.php b/lib/Doctrine/ORM/Mapping/Reflection/ReflectionPropertiesGetter.php
index 0d5be731368..7fc12cafdf1 100644
--- a/lib/Doctrine/ORM/Mapping/Reflection/ReflectionPropertiesGetter.php
+++ b/lib/Doctrine/ORM/Mapping/Reflection/ReflectionPropertiesGetter.php
@@ -56,7 +56,7 @@ public function __construct(ReflectionService $reflectionService)
      *
      * @psalm-param class-string $className
      */
-    public function getProperties($className)
+    public function getProperties($className): array
     {
         if (isset($this->properties[$className])) {
             return $this->properties[$className];
@@ -76,13 +76,11 @@ public function getProperties($className)
     }
 
     /**
-     * @param string $className
-     *
      * @return ReflectionClass[]
      *
      * @psalm-return list<ReflectionClass>
      */
-    private function getHierarchyClasses($className): array
+    private function getHierarchyClasses(string $className): array
     {
         $classes         = [];
         $parentClassName = $className;
@@ -124,18 +122,12 @@ private function getClassProperties(ReflectionClass $reflectionClass): array
         );
     }
 
-    /**
-     * @return bool
-     */
-    private function isInstanceProperty(ReflectionProperty $reflectionProperty)
+    private function isInstanceProperty(ReflectionProperty $reflectionProperty): bool
     {
         return ! $reflectionProperty->isStatic();
     }
 
-    /**
-     * @return ReflectionProperty|null
-     */
-    private function getAccessibleProperty(ReflectionProperty $property)
+    private function getAccessibleProperty(ReflectionProperty $property): ?ReflectionProperty
     {
         return $this->reflectionService->getAccessibleProperty(
             $property->getDeclaringClass()->getName(),
@@ -143,10 +135,7 @@ private function getAccessibleProperty(ReflectionProperty $property)
         );
     }
 
-    /**
-     * @return string
-     */
-    private function getLogicalName(ReflectionProperty $property)
+    private function getLogicalName(ReflectionProperty $property): string
     {
         $propertyName = $property->getName();
 
diff --git a/lib/Doctrine/ORM/NativeQuery.php b/lib/Doctrine/ORM/NativeQuery.php
index d39f4a6890a..546eda7e3e7 100644
--- a/lib/Doctrine/ORM/NativeQuery.php
+++ b/lib/Doctrine/ORM/NativeQuery.php
@@ -60,7 +60,7 @@ public function getSQL()
     }
 
     /**
-     * {@inheritdoc}
+     * {@inheritDoc}
      */
     protected function _doExecute()
     {
diff --git a/lib/Doctrine/ORM/PersistentCollection.php b/lib/Doctrine/ORM/PersistentCollection.php
index de24b0d36de..4387b0c6f8f 100644
--- a/lib/Doctrine/ORM/PersistentCollection.php
+++ b/lib/Doctrine/ORM/PersistentCollection.php
@@ -64,7 +64,7 @@ final class PersistentCollection extends AbstractLazyCollection implements Selec
     /**
      * The entity that owns this collection.
      *
-     * @var object
+     * @var object|null
      */
     private $owner;
 
@@ -129,11 +129,9 @@ public function __construct(EntityManagerInterface $em, $class, Collection $coll
      *
      * @param object $entity
      *
-     * @return void
-     *
      * @psalm-param array<string, mixed> $assoc
      */
-    public function setOwner($entity, array $assoc)
+    public function setOwner($entity, array $assoc): void
     {
         $this->owner            = $entity;
         $this->association      = $assoc;
@@ -143,18 +141,13 @@ public function setOwner($entity, array $assoc)
     /**
      * INTERNAL:
      * Gets the collection owner.
-     *
-     * @return object
      */
-    public function getOwner()
+    public function getOwner(): ?object
     {
         return $this->owner;
     }
 
-    /**
-     * @return Mapping\ClassMetadata
-     */
-    public function getTypeClass()
+    public function getTypeClass(): Mapping\ClassMetadata
     {
         return $this->typeClass;
     }
@@ -165,10 +158,8 @@ public function getTypeClass()
      * complete bidirectional associations in the case of a one-to-many association.
      *
      * @param mixed $element The element to add.
-     *
-     * @return void
      */
-    public function hydrateAdd($element)
+    public function hydrateAdd($element): void
     {
         $this->collection->add($element);
 
@@ -195,10 +186,8 @@ public function hydrateAdd($element)
      *
      * @param mixed $key     The key to set.
      * @param mixed $element The element to set.
-     *
-     * @return void
      */
-    public function hydrateSet($key, $element)
+    public function hydrateSet($key, $element): void
     {
         $this->collection->set($key, $element);
 
@@ -216,10 +205,8 @@ public function hydrateSet($key, $element)
     /**
      * Initializes the collection by loading its contents from the database
      * if the collection is not yet initialized.
-     *
-     * @return void
      */
-    public function initialize()
+    public function initialize(): void
     {
         if ($this->initialized || ! $this->association) {
             return;
@@ -233,10 +220,8 @@ public function initialize()
     /**
      * INTERNAL:
      * Tells this collection to take a snapshot of its current state.
-     *
-     * @return void
      */
-    public function takeSnapshot()
+    public function takeSnapshot(): void
     {
         $this->snapshot = $this->collection->toArray();
         $this->isDirty  = false;
@@ -248,7 +233,7 @@ public function takeSnapshot()
      *
      * @psalm-return array<string|int, mixed> The last snapshot of the elements.
      */
-    public function getSnapshot()
+    public function getSnapshot(): array
     {
         return $this->snapshot;
     }
@@ -259,7 +244,7 @@ public function getSnapshot()
      *
      * @return mixed[]
      */
-    public function getDeleteDiff()
+    public function getDeleteDiff(): array
     {
         return array_udiff_assoc(
             $this->snapshot,
@@ -276,7 +261,7 @@ static function ($a, $b): int {
      *
      * @return mixed[]
      */
-    public function getInsertDiff()
+    public function getInsertDiff(): array
     {
         return array_udiff_assoc(
             $this->collection->toArray(),
@@ -292,17 +277,15 @@ static function ($a, $b): int {
      *
      * @psalm-return array<string, mixed>
      */
-    public function getMapping()
+    public function getMapping(): array
     {
         return $this->association;
     }
 
     /**
      * Marks this collection as changed/dirty.
-     *
-     * @return void
      */
-    private function changed()
+    private function changed(): void
     {
         if ($this->isDirty) {
             return;
@@ -327,7 +310,7 @@ private function changed()
      *
      * @return bool TRUE if the collection is dirty, FALSE otherwise.
      */
-    public function isDirty()
+    public function isDirty(): bool
     {
         return $this->isDirty;
     }
@@ -336,10 +319,8 @@ public function isDirty()
      * Sets a boolean flag, indicating whether this collection is dirty.
      *
      * @param bool $dirty Whether the collection should be marked dirty or not.
-     *
-     * @return void
      */
-    public function setDirty($dirty)
+    public function setDirty($dirty): void
     {
         $this->isDirty = $dirty;
     }
@@ -348,20 +329,16 @@ public function setDirty($dirty)
      * Sets the initialized flag of the collection, forcing it into that state.
      *
      * @param bool $bool
-     *
-     * @return void
      */
-    public function setInitialized($bool)
+    public function setInitialized($bool): void
     {
         $this->initialized = $bool;
     }
 
     /**
      * {@inheritdoc}
-     *
-     * @return object
      */
-    public function remove($key)
+    public function remove($key): object
     {
         // TODO: If the keys are persistent as well (not yet implemented)
         //       and the collection is not initialized and orphanRemoval is
@@ -390,7 +367,7 @@ public function remove($key)
     /**
      * {@inheritdoc}
      */
-    public function removeElement($element)
+    public function removeElement($element): bool
     {
         $removed = parent::removeElement($element);
 
@@ -415,7 +392,7 @@ public function removeElement($element)
     /**
      * {@inheritdoc}
      */
-    public function containsKey($key)
+    public function containsKey($key): bool
     {
         if (
             ! $this->initialized && $this->association['fetch'] === ClassMetadata::FETCH_EXTRA_LAZY
@@ -432,7 +409,7 @@ public function containsKey($key)
     /**
      * {@inheritdoc}
      */
-    public function contains($element)
+    public function contains($element): bool
     {
         if (! $this->initialized && $this->association['fetch'] === ClassMetadata::FETCH_EXTRA_LAZY) {
             $persister = $this->em->getUnitOfWork()->getCollectionPersister($this->association);
@@ -463,10 +440,7 @@ public function get($key)
         return parent::get($key);
     }
 
-    /**
-     * {@inheritdoc}
-     */
-    public function count()
+    public function count(): int
     {
         if (! $this->initialized && $this->association !== null && $this->association['fetch'] === ClassMetadata::FETCH_EXTRA_LAZY) {
             $persister = $this->em->getUnitOfWork()->getCollectionPersister($this->association);
@@ -480,7 +454,7 @@ public function count()
     /**
      * {@inheritdoc}
      */
-    public function set($key, $value)
+    public function set($key, $value): void
     {
         parent::set($key, $value);
 
@@ -494,7 +468,7 @@ public function set($key, $value)
     /**
      * {@inheritdoc}
      */
-    public function add($value)
+    public function add($value): bool
     {
         $this->collection->add($value);
 
@@ -512,7 +486,7 @@ public function add($value)
     /**
      * {@inheritdoc}
      */
-    public function offsetExists($offset)
+    public function offsetExists($offset): bool
     {
         return $this->containsKey($offset);
     }
@@ -528,7 +502,7 @@ public function offsetGet($offset)
     /**
      * {@inheritdoc}
      */
-    public function offsetSet($offset, $value)
+    public function offsetSet($offset, $value): void
     {
         if (! isset($offset)) {
             $this->add($value);
@@ -541,26 +515,18 @@ public function offsetSet($offset, $value)
 
     /**
      * {@inheritdoc}
-     *
-     * @return object
      */
-    public function offsetUnset($offset)
+    public function offsetUnset($offset): object
     {
         return $this->remove($offset);
     }
 
-    /**
-     * {@inheritdoc}
-     */
-    public function isEmpty()
+    public function isEmpty(): bool
     {
         return $this->collection->isEmpty() && $this->count() === 0;
     }
 
-    /**
-     * {@inheritdoc}
-     */
-    public function clear()
+    public function clear(): void
     {
         if ($this->initialized && $this->isEmpty()) {
             $this->collection->clear();
@@ -625,7 +591,7 @@ public function __sleep(): array
      *
      * @psalm-return array<TKey,T>
      */
-    public function slice($offset, $length = null)
+    public function slice($offset, $length = null): array
     {
         if (! $this->initialized && ! $this->isDirty && $this->association['fetch'] === ClassMetadata::FETCH_EXTRA_LAZY) {
             $persister = $this->em->getUnitOfWork()->getCollectionPersister($this->association);
@@ -646,8 +612,6 @@ public function slice($offset, $length = null)
      * 3. Snapshot leads to invalid diffs being generated.
      * 4. Lazy loading grabs entities from old owner object.
      * 5. New collection is connected to old owner and leads to duplicate keys.
-     *
-     * @return void
      */
     public function __clone()
     {
@@ -671,7 +635,7 @@ public function __clone()
      *
      * @throws RuntimeException
      */
-    public function matching(Criteria $criteria)
+    public function matching(Criteria $criteria): Collection
     {
         if ($this->isDirty) {
             $this->initialize();
@@ -708,15 +672,12 @@ public function matching(Criteria $criteria)
      *
      * @return Collection<TKey, T>
      */
-    public function unwrap()
+    public function unwrap(): Collection
     {
         return $this->collection;
     }
 
-    /**
-     * {@inheritdoc}
-     */
-    protected function doInitialize()
+    protected function doInitialize(): void
     {
         // Has NEW objects added through add(). Remember them.
         $newlyAddedDirtyObjects = [];
diff --git a/lib/Doctrine/ORM/Persisters/Collection/ManyToManyPersister.php b/lib/Doctrine/ORM/Persisters/Collection/ManyToManyPersister.php
index 7f38f934640..1f72262e70e 100644
--- a/lib/Doctrine/ORM/Persisters/Collection/ManyToManyPersister.php
+++ b/lib/Doctrine/ORM/Persisters/Collection/ManyToManyPersister.php
@@ -526,14 +526,14 @@ protected function getInsertRowSQLParameters(PersistentCollection $collection, $
      * Collects the parameters for inserting/deleting on the join table in the order
      * of the join table columns as specified in ManyToManyMapping#joinTableColumns.
      *
-     * @param object $element
-     *
      * @return mixed[]
      *
      * @psalm-return list<mixed>
      */
-    private function collectJoinTableColumnParameters(PersistentCollection $collection, $element)
-    {
+    private function collectJoinTableColumnParameters(
+        PersistentCollection $collection,
+        object $element
+    ): array {
         $params      = [];
         $mapping     = $collection->getMapping();
         $isComposite = count($mapping['joinTableColumns']) > 2;
@@ -569,8 +569,7 @@ private function collectJoinTableColumnParameters(PersistentCollection $collecti
     }
 
     /**
-     * @param string $key
-     * @param bool   $addFilters Whether the filter SQL should be included or not.
+     * @param bool $addFilters Whether the filter SQL should be included or not.
      *
      * @return mixed[] ordered vector:
      *                - quoted join table name
@@ -580,8 +579,11 @@ private function collectJoinTableColumnParameters(PersistentCollection $collecti
      *
      * @psalm-return array{0: string, 1: list<string>, 2: list<mixed>, 3: list<string>}
      */
-    private function getJoinTableRestrictionsWithKey(PersistentCollection $collection, $key, $addFilters)
-    {
+    private function getJoinTableRestrictionsWithKey(
+        PersistentCollection $collection,
+        string $key,
+        bool $addFilters
+    ): array {
         $filterMapping = $collection->getMapping();
         $mapping       = $filterMapping;
         $indexBy       = $mapping['indexBy'];
@@ -655,8 +657,7 @@ private function getJoinTableRestrictionsWithKey(PersistentCollection $collectio
     }
 
     /**
-     * @param object $element
-     * @param bool   $addFilters Whether the filter SQL should be included or not.
+     * @param bool $addFilters Whether the filter SQL should be included or not.
      *
      * @return mixed[] ordered vector:
      *                - quoted join table name
@@ -666,8 +667,11 @@ private function getJoinTableRestrictionsWithKey(PersistentCollection $collectio
      *
      * @psalm-return array{0: string, 1: list<string>, 2: list<mixed>, 3: list<string>}
      */
-    private function getJoinTableRestrictions(PersistentCollection $collection, $element, $addFilters)
-    {
+    private function getJoinTableRestrictions(
+        PersistentCollection $collection,
+        object $element,
+        bool $addFilters
+    ): array {
         $filterMapping = $collection->getMapping();
         $mapping       = $filterMapping;
 
@@ -727,7 +731,7 @@ private function getJoinTableRestrictions(PersistentCollection $collection, $ele
      *
      * @return mixed[][]
      */
-    private function expandCriteriaParameters(Criteria $criteria)
+    private function expandCriteriaParameters(Criteria $criteria): array
     {
         $expression = $criteria->getWhereExpression();
 
@@ -744,10 +748,7 @@ private function expandCriteriaParameters(Criteria $criteria)
         return $types;
     }
 
-    /**
-     * @return string
-     */
-    private function getOrderingSql(Criteria $criteria, ClassMetadata $targetClass)
+    private function getOrderingSql(Criteria $criteria, ClassMetadata $targetClass): string
     {
         $orderings = $criteria->getOrderings();
         if ($orderings) {
@@ -768,11 +769,9 @@ private function getOrderingSql(Criteria $criteria, ClassMetadata $targetClass)
     }
 
     /**
-     * @return string
-     *
      * @throws DBALException
      */
-    private function getLimitSql(Criteria $criteria)
+    private function getLimitSql(Criteria $criteria): string
     {
         $limit  = $criteria->getMaxResults();
         $offset = $criteria->getFirstResult();
diff --git a/lib/Doctrine/ORM/Persisters/Collection/OneToManyPersister.php b/lib/Doctrine/ORM/Persisters/Collection/OneToManyPersister.php
index f872cc1c6d4..36efcc6999a 100644
--- a/lib/Doctrine/ORM/Persisters/Collection/OneToManyPersister.php
+++ b/lib/Doctrine/ORM/Persisters/Collection/OneToManyPersister.php
@@ -180,11 +180,9 @@ public function loadCriteria(PersistentCollection $collection, Criteria $criteri
     }
 
     /**
-     * @return int
-     *
      * @throws DBALException
      */
-    private function deleteEntityCollection(PersistentCollection $collection)
+    private function deleteEntityCollection(PersistentCollection $collection): int
     {
         $mapping     = $collection->getMapping();
         $identifier  = $this->uow->getEntityIdentifier($collection->getOwner());
@@ -210,11 +208,9 @@ private function deleteEntityCollection(PersistentCollection $collection)
      *
      * Thanks Steve Ebersole (Hibernate) for idea on how to tackle reliably this scenario, we owe him a beer! =)
      *
-     * @return int
-     *
      * @throws DBALException
      */
-    private function deleteJoinedEntityCollection(PersistentCollection $collection)
+    private function deleteJoinedEntityCollection(PersistentCollection $collection): int
     {
         $mapping     = $collection->getMapping();
         $sourceClass = $this->em->getClassMetadata($mapping['sourceEntity']);
diff --git a/lib/Doctrine/ORM/Persisters/Entity/BasicEntityPersister.php b/lib/Doctrine/ORM/Persisters/Entity/BasicEntityPersister.php
index 9e17c7e214f..f0dbfaf38f1 100644
--- a/lib/Doctrine/ORM/Persisters/Entity/BasicEntityPersister.php
+++ b/lib/Doctrine/ORM/Persisters/Entity/BasicEntityPersister.php
@@ -24,9 +24,9 @@
 use Doctrine\Common\Collections\Expr\Comparison;
 use Doctrine\Common\Util\ClassUtils;
 use Doctrine\DBAL\Connection;
+use Doctrine\DBAL\Driver\Statement as DriverStatement;
 use Doctrine\DBAL\LockMode;
 use Doctrine\DBAL\Platforms\AbstractPlatform;
-use Doctrine\DBAL\Statement;
 use Doctrine\DBAL\Types\Type;
 use Doctrine\ORM\EntityManagerInterface;
 use Doctrine\ORM\Mapping\ClassMetadata;
@@ -415,13 +415,15 @@ public function update($entity)
      * @param mixed[] $updateData      The map of columns to update (column => value).
      * @param bool    $versioned       Whether the UPDATE should be versioned.
      *
-     * @return void
-     *
      * @throws ORMException
      * @throws OptimisticLockException
      */
-    final protected function updateTable($entity, $quotedTableName, array $updateData, $versioned = false)
-    {
+    final protected function updateTable(
+        $entity,
+        $quotedTableName,
+        array $updateData,
+        $versioned = false
+    ): void {
         $set    = [];
         $types  = [];
         $params = [];
@@ -922,12 +924,11 @@ public function getManyToManyCollection(array $assoc, $sourceEntity, $offset = n
     /**
      * Loads an array of entities from a given DBAL statement.
      *
-     * @param mixed[]   $assoc
-     * @param Statement $stmt
+     * @param mixed[] $assoc
      *
      * @return mixed[]
      */
-    private function loadArrayFromStatement($assoc, $stmt)
+    private function loadArrayFromStatement(array $assoc, DriverStatement $stmt): array
     {
         $rsm   = $this->currentPersisterContext->rsm;
         $hints = [UnitOfWork::HINT_DEFEREAGERLOAD => true];
@@ -943,14 +944,15 @@ private function loadArrayFromStatement($assoc, $stmt)
     /**
      * Hydrates a collection from a given DBAL statement.
      *
-     * @param mixed[]              $assoc
-     * @param Statement            $stmt
-     * @param PersistentCollection $coll
+     * @param mixed[] $assoc
      *
      * @return mixed[]
      */
-    private function loadCollectionFromStatement($assoc, $stmt, $coll)
-    {
+    private function loadCollectionFromStatement(
+        array $assoc,
+        DriverStatement $stmt,
+        PersistentCollection $coll
+    ): array {
         $rsm   = $this->currentPersisterContext->rsm;
         $hints = [
             UnitOfWork::HINT_DEFEREAGERLOAD => true,
@@ -976,7 +978,7 @@ public function loadManyToManyCollection(array $assoc, $sourceEntity, Persistent
     }
 
     /**
-     * @return \Doctrine\DBAL\Driver\Statement
+     * @return DriverStatement
      *
      * @throws MappingException
      *
@@ -1660,8 +1662,6 @@ public function getSelectConditionStatementSQL($field, $value, $assoc = null, $c
     /**
      * Builds the left-hand-side of a where condition statement.
      *
-     * @param string $field
-     *
      * @return string[]
      *
      * @throws ORMException
@@ -1669,8 +1669,10 @@ public function getSelectConditionStatementSQL($field, $value, $assoc = null, $c
      * @psalm-param array<string, mixed>|null $assoc
      * @psalm-return list<string>
      */
-    private function getSelectConditionStatementColumnSQL($field, $assoc = null)
-    {
+    private function getSelectConditionStatementColumnSQL(
+        string $field,
+        ?array $assoc = null
+    ): array {
         if (isset($this->class->fieldMappings[$field])) {
             $className = $this->class->fieldMappings[$field]['inherited'] ?? $this->class->name;
 
@@ -1770,16 +1772,14 @@ public function loadOneToManyCollection(array $assoc, $sourceEntity, PersistentC
     /**
      * Builds criteria and execute SQL statement to fetch the one to many entities from.
      *
-     * @param object   $sourceEntity
-     * @param int|null $offset
-     * @param int|null $limit
-     *
-     * @return Statement
-     *
      * @psalm-param array<string, mixed> $assoc
      */
-    private function getOneToManyStatement(array $assoc, $sourceEntity, $offset = null, $limit = null)
-    {
+    private function getOneToManyStatement(
+        array $assoc,
+        object $sourceEntity,
+        ?int $offset = null,
+        ?int $limit = null
+    ): DriverStatement {
         $this->switchPersisterContext($offset, $limit);
 
         $criteria    = [];
@@ -1858,7 +1858,7 @@ public function expandParameters($criteria)
      *
      * @psalm-return array{0: array, 1: list<mixed>}
      */
-    private function expandToManyParameters($criteria)
+    private function expandToManyParameters(array $criteria): array
     {
         $params = [];
         $types  = [];
@@ -1878,8 +1878,7 @@ private function expandToManyParameters($criteria)
     /**
      * Infers field types to be used by parameter type casting.
      *
-     * @param string $field
-     * @param mixed  $value
+     * @param mixed $value
      *
      * @return int[]|null[]|string[]
      *
@@ -1887,7 +1886,7 @@ private function expandToManyParameters($criteria)
      *
      * @psalm-return list<(int|string|null)>
      */
-    private function getTypes($field, $value, ClassMetadata $class)
+    private function getTypes(string $field, $value, ClassMetadata $class): array
     {
         $types = [];
 
@@ -1938,7 +1937,7 @@ private function getTypes($field, $value, ClassMetadata $class)
      *
      * @return array{mixed}
      */
-    private function getValues($value)
+    private function getValues($value): array
     {
         if (is_array($value)) {
             $newValue = [];
diff --git a/lib/Doctrine/ORM/Persisters/Entity/JoinedSubclassPersister.php b/lib/Doctrine/ORM/Persisters/Entity/JoinedSubclassPersister.php
index 0ad5bab07b3..1f5026bb669 100644
--- a/lib/Doctrine/ORM/Persisters/Entity/JoinedSubclassPersister.php
+++ b/lib/Doctrine/ORM/Persisters/Entity/JoinedSubclassPersister.php
@@ -68,10 +68,8 @@ protected function getDiscriminatorColumnTableName()
     /**
      * This function finds the ClassMetadata instance in an inheritance hierarchy
      * that is responsible for enabling versioning.
-     *
-     * @return ClassMetadata
      */
-    private function getVersionedClassMetadata()
+    private function getVersionedClassMetadata(): ClassMetadata
     {
         if (isset($this->class->fieldMappings[$this->class->versionField]['inherited'])) {
             $definingClassName = $this->class->fieldMappings[$this->class->versionField]['inherited'];
@@ -576,12 +574,7 @@ protected function assignDefaultVersionValue($entity, array $id)
         $this->class->setFieldValue($entity, $this->class->versionField, $value);
     }
 
-    /**
-     * @param string $baseTableAlias
-     *
-     * @return string
-     */
-    private function getJoinSql($baseTableAlias)
+    private function getJoinSql(string $baseTableAlias): string
     {
         $joinSql          = '';
         $identifierColumn = $this->class->getIdentifierColumnNames();
diff --git a/lib/Doctrine/ORM/Proxy/ProxyFactory.php b/lib/Doctrine/ORM/Proxy/ProxyFactory.php
index b7aa3943992..9f7e38ab263 100644
--- a/lib/Doctrine/ORM/Proxy/ProxyFactory.php
+++ b/lib/Doctrine/ORM/Proxy/ProxyFactory.php
@@ -109,17 +109,15 @@ protected function createProxyDefinition($className)
     /**
      * Creates a closure capable of initializing a proxy
      *
-     * @return Closure
-     *
      * @throws EntityNotFoundException
      *
      * @psalm-return Closure(BaseProxy ): void
      */
-    private function createInitializer(ClassMetadata $classMetadata, EntityPersister $entityPersister)
+    private function createInitializer(ClassMetadata $classMetadata, EntityPersister $entityPersister): Closure
     {
         $wakeupProxy = $classMetadata->getReflectionClass()->hasMethod('__wakeup');
 
-        return function (BaseProxy $proxy) use ($entityPersister, $classMetadata, $wakeupProxy) {
+        return function (BaseProxy $proxy) use ($entityPersister, $classMetadata, $wakeupProxy): void {
             $initializer = $proxy->__getInitializer();
             $cloner      = $proxy->__getCloner();
 
@@ -162,15 +160,13 @@ private function createInitializer(ClassMetadata $classMetadata, EntityPersister
     /**
      * Creates a closure capable of finalizing state a cloned proxy
      *
-     * @return Closure
-     *
      * @throws EntityNotFoundException
      *
      * @psalm-return Closure(BaseProxy ): void
      */
-    private function createCloner(ClassMetadata $classMetadata, EntityPersister $entityPersister)
+    private function createCloner(ClassMetadata $classMetadata, EntityPersister $entityPersister): Closure
     {
-        return function (BaseProxy $proxy) use ($entityPersister, $classMetadata) {
+        return function (BaseProxy $proxy) use ($entityPersister, $classMetadata): void {
             if ($proxy->__isInitialized()) {
                 return;
             }
diff --git a/lib/Doctrine/ORM/Query.php b/lib/Doctrine/ORM/Query.php
index aefe10e5966..a2928b3e6b9 100644
--- a/lib/Doctrine/ORM/Query.php
+++ b/lib/Doctrine/ORM/Query.php
@@ -228,10 +228,8 @@ protected function getResultSetMapping()
      * Parses the DQL query, if necessary, and stores the parser result.
      *
      * Note: Populates $this->_parserResult as a side-effect.
-     *
-     * @return ParserResult
      */
-    private function parse()
+    private function parse(): ParserResult
     {
         $types = [];
 
@@ -279,7 +277,7 @@ private function parse()
     }
 
     /**
-     * {@inheritdoc}
+     * {@inheritDoc}
      */
     protected function _doExecute()
     {
@@ -335,7 +333,7 @@ private function evictResultSetCache(
         array $sqlParams,
         array $types,
         array $connectionParams
-    ) {
+    ): void {
         if ($this->_queryCacheProfile === null || ! $this->getExpireResultCache()) {
             return;
         }
@@ -353,7 +351,7 @@ private function evictResultSetCache(
     /**
      * Evict entity cache region
      */
-    private function evictEntityCacheRegion()
+    private function evictEntityCacheRegion(): void
     {
         $AST = $this->getAST();
 
@@ -494,7 +492,7 @@ public function useQueryCache($bool): self
      * @return Cache|null The cache driver used for query caching or NULL, if
      * this Query does not use query caching.
      */
-    public function getQueryCacheDriver()
+    public function getQueryCacheDriver(): ?Cache
     {
         if ($this->queryCache) {
             return $this->queryCache;
@@ -523,10 +521,8 @@ public function setQueryCacheLifetime($timeToLive): self
 
     /**
      * Retrieves the lifetime of resultset cache.
-     *
-     * @return int
      */
-    public function getQueryCacheLifetime()
+    public function getQueryCacheLifetime(): int
     {
         return $this->queryCacheTTL;
     }
@@ -547,10 +543,8 @@ public function expireQueryCache($expire = true): self
 
     /**
      * Retrieves if the query cache is active or not.
-     *
-     * @return bool
      */
-    public function getExpireQueryCache()
+    public function getExpireQueryCache(): bool
     {
         return $this->expireQueryCache;
     }
@@ -558,7 +552,7 @@ public function getExpireQueryCache()
     /**
      * @override
      */
-    public function free()
+    public function free(): void
     {
         parent::free();
 
@@ -583,10 +577,8 @@ public function setDQL($dqlQuery): self
 
     /**
      * Returns the DQL query that is represented by this query object.
-     *
-     * @return string|null
      */
-    public function getDQL()
+    public function getDQL(): ?string
     {
         return $this->dql;
     }
@@ -601,7 +593,7 @@ public function getDQL()
      *
      * @return int The query state.
      */
-    public function getState()
+    public function getState(): int
     {
         return $this->_state;
     }
@@ -610,10 +602,8 @@ public function getState()
      * Method to check if an arbitrary piece of DQL exists
      *
      * @param string $dql Arbitrary piece of DQL to check for.
-     *
-     * @return bool
      */
-    public function contains($dql)
+    public function contains($dql): bool
     {
         return stripos($this->getDQL(), $dql) !== false;
     }
@@ -639,7 +629,7 @@ public function setFirstResult($firstResult): self
      *
      * @return int|null The position of the first result.
      */
-    public function getFirstResult()
+    public function getFirstResult(): ?int
     {
         return $this->firstResult;
     }
@@ -665,7 +655,7 @@ public function setMaxResults($maxResults): self
      *
      * @return int|null Maximum number of results.
      */
-    public function getMaxResults()
+    public function getMaxResults(): ?int
     {
         return $this->maxResults;
     }
@@ -679,11 +669,9 @@ public function getMaxResults()
      * @param ArrayCollection|mixed[]|null $parameters    The query parameters.
      * @param string|int                   $hydrationMode The hydration mode to use.
      *
-     * @return IterableResult
-     *
      * @psalm-param ArrayCollection<int, Parameter>|array<string, mixed>|null $parameters
      */
-    public function iterate($parameters = null, $hydrationMode = self::HYDRATE_OBJECT)
+    public function iterate($parameters = null, $hydrationMode = self::HYDRATE_OBJECT): IterableResult
     {
         $this->setHint(self::HINT_INTERNAL_ITERATION, true);
 
@@ -701,7 +689,7 @@ public function toIterable(iterable $parameters = [], $hydrationMode = self::HYD
     /**
      * {@inheritdoc}
      */
-    public function setHint($name, $value)
+    public function setHint($name, $value): self
     {
         $this->_state = self::STATE_DIRTY;
 
@@ -711,7 +699,7 @@ public function setHint($name, $value)
     /**
      * {@inheritdoc}
      */
-    public function setHydrationMode($hydrationMode)
+    public function setHydrationMode($hydrationMode): self
     {
         $this->_state = self::STATE_DIRTY;
 
@@ -745,7 +733,7 @@ public function setLockMode($lockMode): self
      *
      * @return int|null The current lock mode of this query or NULL if no specific lock mode is set.
      */
-    public function getLockMode()
+    public function getLockMode(): ?int
     {
         $lockMode = $this->getHint(self::HINT_LOCK_MODE);
 
@@ -777,18 +765,13 @@ protected function getQueryCacheId(): string
         );
     }
 
-     /**
-      * {@inheritdoc}
-      */
-    protected function getHash()
+    protected function getHash(): string
     {
         return sha1(parent::getHash() . '-' . $this->firstResult . '-' . $this->maxResults);
     }
 
     /**
      * Cleanup Query resource when clone is called.
-     *
-     * @return void
      */
     public function __clone()
     {
diff --git a/lib/Doctrine/ORM/Query/AST/Functions/TrimFunction.php b/lib/Doctrine/ORM/Query/AST/Functions/TrimFunction.php
index b7e07099036..e41122b37c7 100644
--- a/lib/Doctrine/ORM/Query/AST/Functions/TrimFunction.php
+++ b/lib/Doctrine/ORM/Query/AST/Functions/TrimFunction.php
@@ -93,9 +93,9 @@ public function parse(Parser $parser)
     }
 
     /**
-     * @return int
+     * @psalm-return AbstractPlatform::TRIM_*
      */
-    private function getTrimMode()
+    private function getTrimMode(): int
     {
         if ($this->leading) {
             return AbstractPlatform::TRIM_LEADING;
@@ -112,10 +112,7 @@ private function getTrimMode()
         return AbstractPlatform::TRIM_UNSPECIFIED;
     }
 
-    /**
-     * @return void
-     */
-    private function parseTrimMode(Parser $parser)
+    private function parseTrimMode(Parser $parser): void
     {
         $lexer = $parser->getLexer();
         $value = $lexer->lookahead['value'];
diff --git a/lib/Doctrine/ORM/Query/Expr/Composite.php b/lib/Doctrine/ORM/Query/Expr/Composite.php
index f65c6975ccb..f75aa8d4654 100644
--- a/lib/Doctrine/ORM/Query/Expr/Composite.php
+++ b/lib/Doctrine/ORM/Query/Expr/Composite.php
@@ -51,10 +51,8 @@ public function __toString()
 
     /**
      * @param string|object $part
-     *
-     * @return string
      */
-    private function processQueryPart($part)
+    private function processQueryPart($part): string
     {
         $queryPart = (string) $part;
 
diff --git a/lib/Doctrine/ORM/Query/Filter/SQLFilter.php b/lib/Doctrine/ORM/Query/Filter/SQLFilter.php
index f9cb0a59a40..9cd80d05482 100644
--- a/lib/Doctrine/ORM/Query/Filter/SQLFilter.php
+++ b/lib/Doctrine/ORM/Query/Filter/SQLFilter.php
@@ -135,10 +135,8 @@ final public function __toString()
 
     /**
      * Returns the database connection used by the entity manager
-     *
-     * @return Connection
      */
-    final protected function getConnection()
+    final protected function getConnection(): Connection
     {
         return $this->em->getConnection();
     }
diff --git a/lib/Doctrine/ORM/Query/Parser.php b/lib/Doctrine/ORM/Query/Parser.php
index 27e1e127149..cb761fdcf27 100644
--- a/lib/Doctrine/ORM/Query/Parser.php
+++ b/lib/Doctrine/ORM/Query/Parser.php
@@ -464,10 +464,8 @@ public function parse()
      * as the hydration process relies on that order for proper operation.
      *
      * @param AST\SelectStatement|AST\DeleteStatement|AST\UpdateStatement $AST
-     *
-     * @return void
      */
-    private function fixIdentificationVariableOrder($AST)
+    private function fixIdentificationVariableOrder(Node $AST): void
     {
         if (count($this->identVariableExpressions) <= 1) {
             return;
@@ -559,7 +557,7 @@ public function semanticalError($message = '', $token = null)
      *
      * @psalm-return array<string, mixed>| null
      */
-    private function peekBeyondClosingParenthesis(bool $resetPeek = true)
+    private function peekBeyondClosingParenthesis(bool $resetPeek = true): ?array
     {
         $token        = $this->lexer->peek();
         $numUnmatched = 1;
@@ -591,9 +589,9 @@ private function peekBeyondClosingParenthesis(bool $resetPeek = true)
     /**
      * Checks if the given token indicates a mathematical operator.
      *
-     * @psalm-param array<string, mixed> $token
+     * @psalm-param array<string, mixed>|null $token
      */
-    private function isMathOperator($token): bool
+    private function isMathOperator(?array $token): bool
     {
         return $token !== null && in_array($token['type'], [Lexer::T_PLUS, Lexer::T_MINUS, Lexer::T_DIVIDE, Lexer::T_MULTIPLY]);
     }
@@ -1043,7 +1041,7 @@ public function AbstractSchemaName()
      *
      * @throws QueryException if the name does not exist.
      */
-    private function validateAbstractSchemaName($schemaName)
+    private function validateAbstractSchemaName(string $schemaName): void
     {
         if (! (class_exists($schemaName, true) || interface_exists($schemaName, true))) {
             $this->semanticalError(
@@ -3488,10 +3486,8 @@ public function FunctionDeclaration()
 
     /**
      * Helper function for FunctionDeclaration grammar rule.
-     *
-     * @return FunctionNode
      */
-    private function CustomFunctionDeclaration()
+    private function CustomFunctionDeclaration(): ?FunctionNode
     {
         $token    = $this->lexer->lookahead;
         $funcName = strtolower($token['value']);
diff --git a/lib/Doctrine/ORM/Query/ResultSetMappingBuilder.php b/lib/Doctrine/ORM/Query/ResultSetMappingBuilder.php
index 288ada32ec7..31063e7dac7 100644
--- a/lib/Doctrine/ORM/Query/ResultSetMappingBuilder.php
+++ b/lib/Doctrine/ORM/Query/ResultSetMappingBuilder.php
@@ -197,14 +197,10 @@ private function isInheritanceSupported(ClassMetadataInfo $classMetadata): bool
     /**
      * Gets column alias for a given column.
      *
-     * @param string $columnName
-     * @param int    $mode
-     *
-     * @return string
-     *
+     * @psalm-param self::COLUMN_RENAMING_* $mode
      * @psalm-param array<string, string>  $customRenameColumns
      */
-    private function getColumnAlias($columnName, $mode, array $customRenameColumns)
+    private function getColumnAlias(string $columnName, int $mode, array $customRenameColumns): string
     {
         switch ($mode) {
             case self::COLUMN_RENAMING_INCREMENT:
@@ -215,6 +211,12 @@ private function getColumnAlias($columnName, $mode, array $customRenameColumns)
 
             case self::COLUMN_RENAMING_NONE:
                 return $columnName;
+
+            default:
+                throw new InvalidArgumentException(sprintf(
+                    '%d is not a valid value for $mode',
+                    $mode
+                ));
         }
     }
 
@@ -223,15 +225,13 @@ private function getColumnAlias($columnName, $mode, array $customRenameColumns)
      *
      * This depends on the renaming mode selected by the user.
      *
-     * @param string $className
-     * @param int    $mode
-     *
      * @return string[]
      *
+     * @psalm-param self::COLUMN_RENAMING_* $mode
      * @psalm-param array<string, string> $customRenameColumns
      * @psalm-return array<array-key, string>
      */
-    private function getColumnAliasMap($className, $mode, array $customRenameColumns)
+    private function getColumnAliasMap(string $className, $mode, array $customRenameColumns): array
     {
         if ($customRenameColumns) { // for BC with 2.2-2.3 API
             $mode = self::COLUMN_RENAMING_CUSTOM;
diff --git a/lib/Doctrine/ORM/Query/SqlWalker.php b/lib/Doctrine/ORM/Query/SqlWalker.php
index 2831ac07a0e..b10f809091a 100644
--- a/lib/Doctrine/ORM/Query/SqlWalker.php
+++ b/lib/Doctrine/ORM/Query/SqlWalker.php
@@ -936,11 +936,11 @@ public function walkRangeVariableDeclaration($rangeVariableDeclaration)
 
     /**
      * Generate appropriate SQL for RangeVariableDeclaration AST node
-     *
-     * @param AST\RangeVariableDeclaration $rangeVariableDeclaration
      */
-    private function generateRangeVariableDeclarationSQL($rangeVariableDeclaration, bool $buildNestedJoins): string
-    {
+    private function generateRangeVariableDeclarationSQL(
+        AST\RangeVariableDeclaration $rangeVariableDeclaration,
+        bool $buildNestedJoins
+    ): string {
         $class    = $this->em->getClassMetadata($rangeVariableDeclaration->abstractSchemaName);
         $dqlAlias = $rangeVariableDeclaration->aliasIdentificationVariable;
 
@@ -2354,8 +2354,10 @@ public function walkResultVariable($resultVariable)
      *
      * @throws QueryException
      */
-    private function getChildDiscriminatorsFromClassMetadata(ClassMetadataInfo $rootClass, AST\InstanceOfExpression $instanceOfExpr): string
-    {
+    private function getChildDiscriminatorsFromClassMetadata(
+        ClassMetadataInfo $rootClass,
+        AST\InstanceOfExpression $instanceOfExpr
+    ): string {
         $sqlParameterList = [];
         $discriminators   = [];
         foreach ($instanceOfExpr->value as $parameter) {
diff --git a/lib/Doctrine/ORM/QueryBuilder.php b/lib/Doctrine/ORM/QueryBuilder.php
index feb8185ef1d..b9f7c47d708 100644
--- a/lib/Doctrine/ORM/QueryBuilder.php
+++ b/lib/Doctrine/ORM/QueryBuilder.php
@@ -393,10 +393,8 @@ public function getQuery()
      *
      * @param string $alias       The alias of the new join entity
      * @param string $parentAlias The parent entity alias of the join relationship
-     *
-     * @return string
      */
-    private function findRootAlias($alias, $parentAlias)
+    private function findRootAlias(string $alias, string $parentAlias): string
     {
         $rootAlias = null;
 
@@ -1394,10 +1392,7 @@ public function getDQLParts()
         return $this->_dqlParts;
     }
 
-    /**
-     * @return string
-     */
-    private function getDQLForDelete()
+    private function getDQLForDelete(): string
     {
          return 'DELETE'
               . $this->getReducedDQLQueryPart('from', ['pre' => ' ', 'separator' => ', '])
@@ -1405,10 +1400,7 @@ private function getDQLForDelete()
               . $this->getReducedDQLQueryPart('orderBy', ['pre' => ' ORDER BY ', 'separator' => ', ']);
     }
 
-    /**
-     * @return string
-     */
-    private function getDQLForUpdate()
+    private function getDQLForUpdate(): string
     {
          return 'UPDATE'
               . $this->getReducedDQLQueryPart('from', ['pre' => ' ', 'separator' => ', '])
@@ -1417,10 +1409,7 @@ private function getDQLForUpdate()
               . $this->getReducedDQLQueryPart('orderBy', ['pre' => ' ORDER BY ', 'separator' => ', ']);
     }
 
-    /**
-     * @return string
-     */
-    private function getDQLForSelect()
+    private function getDQLForSelect(): string
     {
         $dql = 'SELECT'
              . ($this->_dqlParts['distinct'] === true ? ' DISTINCT' : '')
diff --git a/lib/Doctrine/ORM/Repository/DefaultRepositoryFactory.php b/lib/Doctrine/ORM/Repository/DefaultRepositoryFactory.php
index 53a1b017cb1..f7fe2476a42 100644
--- a/lib/Doctrine/ORM/Repository/DefaultRepositoryFactory.php
+++ b/lib/Doctrine/ORM/Repository/DefaultRepositoryFactory.php
@@ -40,7 +40,7 @@ final class DefaultRepositoryFactory implements RepositoryFactory
     /**
      * {@inheritdoc}
      */
-    public function getRepository(EntityManagerInterface $entityManager, $entityName)
+    public function getRepository(EntityManagerInterface $entityManager, $entityName): ObjectRepository
     {
         $repositoryHash = $entityManager->getClassMetadata($entityName)->getName() . spl_object_hash($entityManager);
 
@@ -56,11 +56,11 @@ public function getRepository(EntityManagerInterface $entityManager, $entityName
      *
      * @param EntityManagerInterface $entityManager The EntityManager instance.
      * @param string                 $entityName    The name of the entity.
-     *
-     * @return ObjectRepository
      */
-    private function createRepository(EntityManagerInterface $entityManager, $entityName)
-    {
+    private function createRepository(
+        EntityManagerInterface $entityManager,
+        string $entityName
+    ): ObjectRepository {
         $metadata            = $entityManager->getClassMetadata($entityName);
         $repositoryClassName = $metadata->customRepositoryClassName
             ?: $entityManager->getConfiguration()->getDefaultRepositoryClassName();
diff --git a/lib/Doctrine/ORM/Tools/Console/Command/MappingDescribeCommand.php b/lib/Doctrine/ORM/Tools/Console/Command/MappingDescribeCommand.php
index 4c4c41a4513..adc1b4f4841 100644
--- a/lib/Doctrine/ORM/Tools/Console/Command/MappingDescribeCommand.php
+++ b/lib/Doctrine/ORM/Tools/Console/Command/MappingDescribeCommand.php
@@ -59,10 +59,7 @@
  */
 final class MappingDescribeCommand extends Command
 {
-    /**
-     * {@inheritdoc}
-     */
-    protected function configure()
+    protected function configure(): void
     {
         $this->setName('orm:mapping:describe')
              ->addArgument('entityName', InputArgument::REQUIRED, 'Full or partial name of entity')
@@ -79,10 +76,7 @@ protected function configure()
              );
     }
 
-    /**
-     * {@inheritdoc}
-     */
-    protected function execute(InputInterface $input, OutputInterface $output)
+    protected function execute(InputInterface $input, OutputInterface $output): int
     {
         $ui = new SymfonyStyle($input, $output);
 
@@ -99,8 +93,11 @@ protected function execute(InputInterface $input, OutputInterface $output)
      *
      * @param string $entityName Full or partial entity class name
      */
-    private function displayEntity($entityName, EntityManagerInterface $entityManager, SymfonyStyle $ui)
-    {
+    private function displayEntity(
+        string $entityName,
+        EntityManagerInterface $entityManager,
+        SymfonyStyle $ui
+    ): void {
         $metadata = $this->getClassMetadata($entityName, $entityManager);
 
         $ui->table(
@@ -171,11 +168,11 @@ private function getMappedEntities(EntityManagerInterface $entityManager): array
      * name
      *
      * @param string $entityName Full or partial entity name
-     *
-     * @return ClassMetadata
      */
-    private function getClassMetadata($entityName, EntityManagerInterface $entityManager)
-    {
+    private function getClassMetadata(
+        string $entityName,
+        EntityManagerInterface $entityManager
+    ): ClassMetadata {
         try {
             return $entityManager->getClassMetadata($entityName);
         } catch (MappingException $e) {
@@ -210,10 +207,8 @@ static function ($mappedEntity) use ($entityName) {
      * Format the given value for console output
      *
      * @param mixed $value
-     *
-     * @return string
      */
-    private function formatValue($value)
+    private function formatValue($value): string
     {
         if ($value === '') {
             return '';
@@ -256,7 +251,7 @@ private function formatValue($value)
      *
      * @psalm-return array{0: string, 1: string}
      */
-    private function formatField($label, $value): array
+    private function formatField(string $label, $value): array
     {
         if ($value === null) {
             $value = '<comment>None</comment>';
diff --git a/lib/Doctrine/ORM/Tools/ConvertDoctrine1Schema.php b/lib/Doctrine/ORM/Tools/ConvertDoctrine1Schema.php
index a4fdbf6817d..a9544396c56 100644
--- a/lib/Doctrine/ORM/Tools/ConvertDoctrine1Schema.php
+++ b/lib/Doctrine/ORM/Tools/ConvertDoctrine1Schema.php
@@ -107,8 +107,10 @@ public function getMetadata()
     /**
      * @param mixed[] $mappingInformation
      */
-    private function convertToClassMetadataInfo(string $className, $mappingInformation): ClassMetadataInfo
-    {
+    private function convertToClassMetadataInfo(
+        string $className,
+        array $mappingInformation
+    ): ClassMetadataInfo {
         $metadata = new ClassMetadataInfo($className);
 
         $this->convertTableName($className, $mappingInformation, $metadata);
@@ -137,13 +139,13 @@ private function convertTableName(string $className, array $model, ClassMetadata
     }
 
     /**
-     * @param string  $className
      * @param mixed[] $model
-     *
-     * @return void
      */
-    private function convertColumns($className, array $model, ClassMetadataInfo $metadata)
-    {
+    private function convertColumns(
+        string $className,
+        array $model,
+        ClassMetadataInfo $metadata
+    ): void {
         $id = false;
 
         if (isset($model['columns']) && $model['columns']) {
@@ -169,16 +171,18 @@ private function convertColumns($className, array $model, ClassMetadataInfo $met
     }
 
     /**
-     * @param string         $className
-     * @param string         $name
      * @param string|mixed[] $column
      *
      * @return mixed[]
      *
      * @throws ToolsException
      */
-    private function convertColumn($className, $name, $column, ClassMetadataInfo $metadata)
-    {
+    private function convertColumn(
+        string $className,
+        string $name,
+        $column,
+        ClassMetadataInfo $metadata
+    ): array {
         if (is_string($column)) {
             $string         = $column;
             $column         = [];
@@ -259,13 +263,13 @@ private function convertColumn($className, $name, $column, ClassMetadataInfo $me
     }
 
     /**
-     * @param string  $className
      * @param mixed[] $model
-     *
-     * @return void
      */
-    private function convertIndexes($className, array $model, ClassMetadataInfo $metadata)
-    {
+    private function convertIndexes(
+        string $className,
+        array $model,
+        ClassMetadataInfo $metadata
+    ): void {
         if (empty($model['indexes'])) {
             return;
         }
@@ -281,13 +285,13 @@ private function convertIndexes($className, array $model, ClassMetadataInfo $met
     }
 
     /**
-     * @param string  $className
      * @param mixed[] $model
-     *
-     * @return void
      */
-    private function convertRelations($className, array $model, ClassMetadataInfo $metadata)
-    {
+    private function convertRelations(
+        string $className,
+        array $model,
+        ClassMetadataInfo $metadata
+    ): void {
         if (empty($model['relations'])) {
             return;
         }
diff --git a/lib/Doctrine/ORM/Tools/DebugUnitOfWorkListener.php b/lib/Doctrine/ORM/Tools/DebugUnitOfWorkListener.php
index f9a9b046aba..d8dab8afab5 100644
--- a/lib/Doctrine/ORM/Tools/DebugUnitOfWorkListener.php
+++ b/lib/Doctrine/ORM/Tools/DebugUnitOfWorkListener.php
@@ -137,10 +137,8 @@ public function dumpIdentityMap(EntityManagerInterface $em)
 
     /**
      * @param mixed $var
-     *
-     * @return string
      */
-    private function getType($var)
+    private function getType($var): string
     {
         if (is_object($var)) {
             $refl = new ReflectionObject($var);
@@ -151,12 +149,7 @@ private function getType($var)
         return gettype($var);
     }
 
-    /**
-     * @param object $entity
-     *
-     * @return string
-     */
-    private function getIdString($entity, UnitOfWork $uow)
+    private function getIdString(object $entity, UnitOfWork $uow): string
     {
         if ($uow->isInIdentityMap($entity)) {
             $ids      = $uow->getEntityIdentifier($entity);
diff --git a/lib/Doctrine/ORM/Tools/EntityGenerator.php b/lib/Doctrine/ORM/Tools/EntityGenerator.php
index 6b1a77c37ec..fb1c8471bf7 100644
--- a/lib/Doctrine/ORM/Tools/EntityGenerator.php
+++ b/lib/Doctrine/ORM/Tools/EntityGenerator.php
@@ -747,10 +747,7 @@ protected function generateEntityConstructor(ClassMetadataInfo $metadata)
         return '';
     }
 
-    /**
-     * @return string
-     */
-    private function generateEmbeddableConstructor(ClassMetadataInfo $metadata)
+    private function generateEmbeddableConstructor(ClassMetadataInfo $metadata): string
     {
         $paramTypes     = [];
         $paramVariables = [];
diff --git a/lib/Doctrine/ORM/Tools/EntityRepositoryGenerator.php b/lib/Doctrine/ORM/Tools/EntityRepositoryGenerator.php
index d2b7487b6c1..9fbde5f53aa 100644
--- a/lib/Doctrine/ORM/Tools/EntityRepositoryGenerator.php
+++ b/lib/Doctrine/ORM/Tools/EntityRepositoryGenerator.php
@@ -95,24 +95,16 @@ public function generateEntityRepositoryClass($fullClassName)
 
     /**
      * Generates the namespace, if class do not have namespace, return empty string instead.
-     *
-     * @param string $fullClassName
-     *
-     * @return string $namespace
      */
-    private function getClassNamespace($fullClassName)
+    private function getClassNamespace(string $fullClassName): string
     {
         return substr($fullClassName, 0, strrpos($fullClassName, '\\'));
     }
 
     /**
      * Generates the class name
-     *
-     * @param string $fullClassName
-     *
-     * @return string
      */
-    private function generateClassName($fullClassName)
+    private function generateClassName(string $fullClassName): string
     {
         $namespace = $this->getClassNamespace($fullClassName);
 
@@ -129,22 +121,15 @@ private function generateClassName($fullClassName)
      * Generates the namespace statement, if class do not have namespace, return empty string instead.
      *
      * @param string $fullClassName The full repository class name.
-     *
-     * @return string $namespace
      */
-    private function generateEntityRepositoryNamespace($fullClassName)
+    private function generateEntityRepositoryNamespace(string $fullClassName): string
     {
         $namespace = $this->getClassNamespace($fullClassName);
 
         return $namespace ? 'namespace ' . $namespace . ';' : '';
     }
 
-    /**
-     * @param string $fullClassName
-     *
-     * @return string $repositoryName
-     */
-    private function generateEntityRepositoryName($fullClassName)
+    private function generateEntityRepositoryName(string $fullClassName): string
     {
         $namespace = $this->getClassNamespace($fullClassName);
 
diff --git a/lib/Doctrine/ORM/Tools/Pagination/LimitSubqueryOutputWalker.php b/lib/Doctrine/ORM/Tools/Pagination/LimitSubqueryOutputWalker.php
index b783390b0dc..62521fb6450 100644
--- a/lib/Doctrine/ORM/Tools/Pagination/LimitSubqueryOutputWalker.php
+++ b/lib/Doctrine/ORM/Tools/Pagination/LimitSubqueryOutputWalker.php
@@ -128,10 +128,8 @@ public function __construct($query, $parserResult, array $queryComponents)
 
     /**
      * Check if the platform supports the ROW_NUMBER window function.
-     *
-     * @return bool
      */
-    private function platformSupportsRowNumber()
+    private function platformSupportsRowNumber(): bool
     {
         return $this->platform instanceof PostgreSqlPlatform
             || $this->platform instanceof SQLServerPlatform
@@ -146,7 +144,7 @@ private function platformSupportsRowNumber()
      * Rebuilds a select statement's order by clause for use in a
      * ROW_NUMBER() OVER() expression.
      */
-    private function rebuildOrderByForRowNumber(SelectStatement $AST)
+    private function rebuildOrderByForRowNumber(SelectStatement $AST): void
     {
         $orderByClause              = $AST->orderByClause;
         $selectAliasToExpressionMap = [];
@@ -306,7 +304,7 @@ public function walkSelectStatementWithoutRowNumber(SelectStatement $AST, $addMi
      * Finds all PathExpressions in an AST's OrderByClause, and ensures that
      * the referenced fields are present in the SelectClause of the passed AST.
      */
-    private function addMissingItemsFromOrderByToSelect(SelectStatement $AST)
+    private function addMissingItemsFromOrderByToSelect(SelectStatement $AST): void
     {
         $this->orderByPathExpressions = [];
 
@@ -485,12 +483,10 @@ public function getOrderByPathExpressions()
     }
 
     /**
-     * @return string
-     *
      * @throws OptimisticLockException
      * @throws QueryException
      */
-    private function getInnerSQL(SelectStatement $AST)
+    private function getInnerSQL(SelectStatement $AST): string
     {
         // Set every select expression as visible(hidden = false) to
         // make $AST have scalar mappings properly - this is relevant for referencing selected
@@ -517,7 +513,7 @@ private function getInnerSQL(SelectStatement $AST)
      *
      * @psalm-return array<array-key, array-key>
      */
-    private function getSQLIdentifier(SelectStatement $AST)
+    private function getSQLIdentifier(SelectStatement $AST): array
     {
         // Find out the SQL alias of the identifier column of the root entity.
         // It may be possible to make this work with multiple root entities but that
diff --git a/lib/Doctrine/ORM/Tools/Pagination/LimitSubqueryWalker.php b/lib/Doctrine/ORM/Tools/Pagination/LimitSubqueryWalker.php
index a40f0545481..694d06b4d3b 100644
--- a/lib/Doctrine/ORM/Tools/Pagination/LimitSubqueryWalker.php
+++ b/lib/Doctrine/ORM/Tools/Pagination/LimitSubqueryWalker.php
@@ -24,6 +24,7 @@
 use Doctrine\ORM\Mapping\ClassMetadataInfo;
 use Doctrine\ORM\Query;
 use Doctrine\ORM\Query\AST\Functions\IdentityFunction;
+use Doctrine\ORM\Query\AST\Node;
 use Doctrine\ORM\Query\AST\PathExpression;
 use Doctrine\ORM\Query\AST\SelectExpression;
 use Doctrine\ORM\Query\AST\SelectStatement;
@@ -122,7 +123,7 @@ public function walkSelectStatement(SelectStatement $AST)
     /**
      * Validate the AST to ensure that this walker is able to properly manipulate it.
      */
-    private function validate(SelectStatement $AST)
+    private function validate(SelectStatement $AST): void
     {
         // Prevent LimitSubqueryWalker from being used with queries that include
         // a limit, a fetched to-many join, and an order by condition that
@@ -163,7 +164,7 @@ private function validate(SelectStatement $AST)
      *
      * @return IdentityFunction|PathExpression
      */
-    private function createSelectExpressionItem(PathExpression $pathExpression)
+    private function createSelectExpressionItem(PathExpression $pathExpression): Node
     {
         if ($pathExpression->type === PathExpression::TYPE_SINGLE_VALUED_ASSOCIATION) {
             $identity = new IdentityFunction('identity');
diff --git a/lib/Doctrine/ORM/Tools/Pagination/Paginator.php b/lib/Doctrine/ORM/Tools/Pagination/Paginator.php
index 4e0b9f7e628..150e39b1af9 100644
--- a/lib/Doctrine/ORM/Tools/Pagination/Paginator.php
+++ b/lib/Doctrine/ORM/Tools/Pagination/Paginator.php
@@ -180,14 +180,7 @@ public function getIterator()
         return new ArrayIterator($result);
     }
 
-    /**
-     * Clones a query.
-     *
-     * @param Query $query The query.
-     *
-     * @return Query The cloned query.
-     */
-    private function cloneQuery(Query $query)
+    private function cloneQuery(Query $query): Query
     {
         $cloneQuery = clone $query;
 
@@ -203,12 +196,8 @@ private function cloneQuery(Query $query)
 
     /**
      * Determines whether to use an output walker for the query.
-     *
-     * @param Query $query The query.
-     *
-     * @return bool
      */
-    private function useOutputWalker(Query $query)
+    private function useOutputWalker(Query $query): bool
     {
         if ($this->useOutputWalkers === null) {
             return (bool) $query->getHint(Query::HINT_CUSTOM_OUTPUT_WALKER) === false;
@@ -219,10 +208,8 @@ private function useOutputWalker(Query $query)
 
     /**
      * Appends a custom tree walker to the tree walkers hint.
-     *
-     * @param string $walkerClass
      */
-    private function appendTreeWalker(Query $query, $walkerClass)
+    private function appendTreeWalker(Query $query, string $walkerClass): void
     {
         $hints = $query->getHint(Query::HINT_CUSTOM_TREE_WALKERS);
 
@@ -236,10 +223,8 @@ private function appendTreeWalker(Query $query, $walkerClass)
 
     /**
      * Returns Query prepared to count.
-     *
-     * @return Query
      */
-    private function getCountQuery()
+    private function getCountQuery(): Query
     {
         $countQuery = $this->cloneQuery($this->query);
 
diff --git a/lib/Doctrine/ORM/Tools/ResolveTargetEntityListener.php b/lib/Doctrine/ORM/Tools/ResolveTargetEntityListener.php
index 4a6459085de..45c55b177f7 100644
--- a/lib/Doctrine/ORM/Tools/ResolveTargetEntityListener.php
+++ b/lib/Doctrine/ORM/Tools/ResolveTargetEntityListener.php
@@ -25,7 +25,6 @@
 use Doctrine\ORM\Event\OnClassMetadataNotFoundEventArgs;
 use Doctrine\ORM\Events;
 use Doctrine\ORM\Mapping\ClassMetadata;
-use Doctrine\ORM\Mapping\ClassMetadataInfo;
 
 use function array_key_exists;
 use function array_replace_recursive;
@@ -110,12 +109,9 @@ public function loadClassMetadata(LoadClassMetadataEventArgs $args)
     }
 
     /**
-     * @param ClassMetadataInfo $classMetadata
-     * @param mixed[]           $mapping
-     *
-     * @return void
+     * @param mixed[] $mapping
      */
-    private function remapAssociation($classMetadata, $mapping)
+    private function remapAssociation(ClassMetadata $classMetadata, $mapping): void
     {
         $newMapping              = $this->resolveTargetEntities[$mapping['targetEntity']];
         $newMapping              = array_replace_recursive($mapping, $newMapping);
diff --git a/lib/Doctrine/ORM/Tools/SchemaTool.php b/lib/Doctrine/ORM/Tools/SchemaTool.php
index 85443e4148c..7957fc22d63 100644
--- a/lib/Doctrine/ORM/Tools/SchemaTool.php
+++ b/lib/Doctrine/ORM/Tools/SchemaTool.php
@@ -373,12 +373,8 @@ static function (ClassMetadata $class) use ($idMapping): bool {
     /**
      * Gets a portable column definition as required by the DBAL for the discriminator
      * column of a class.
-     *
-     * @param ClassMetadata $class
-     *
-     * @return void
      */
-    private function addDiscriminatorColumnDefinition($class, Table $table)
+    private function addDiscriminatorColumnDefinition(ClassMetadata $class, Table $table): void
     {
         $discrColumn = $class->discriminatorColumn;
 
@@ -405,12 +401,8 @@ private function addDiscriminatorColumnDefinition($class, Table $table)
     /**
      * Gathers the column definitions as required by the DBAL of all field mappings
      * found in the given class.
-     *
-     * @param ClassMetadata $class
-     *
-     * @return void
      */
-    private function gatherColumns($class, Table $table)
+    private function gatherColumns(ClassMetadata $class, Table $table): void
     {
         $pkColumns = [];
 
diff --git a/lib/Doctrine/ORM/UnitOfWork.php b/lib/Doctrine/ORM/UnitOfWork.php
index e638fd5ad69..2cc6630c7e4 100644
--- a/lib/Doctrine/ORM/UnitOfWork.php
+++ b/lib/Doctrine/ORM/UnitOfWork.php
@@ -513,10 +513,8 @@ private function postCommitCleanup($entity): void
 
     /**
      * Computes the changesets of all entities scheduled for insertion.
-     *
-     * @return void
      */
-    private function computeScheduleInsertsChangeSets()
+    private function computeScheduleInsertsChangeSets(): void
     {
         foreach ($this->entityInsertions as $entity) {
             $class = $this->em->getClassMetadata(get_class($entity));
@@ -533,13 +531,9 @@ private function computeScheduleInsertsChangeSets()
      * 3. Proxies are skipped.
      * 4. Only if entity is properly managed.
      *
-     * @param object $entity
-     *
-     * @return void
-     *
      * @throws InvalidArgumentException
      */
-    private function computeSingleEntityChangeSet($entity)
+    private function computeSingleEntityChangeSet(object $entity): void
     {
         $state = $this->getEntityState($entity);
 
@@ -964,13 +958,7 @@ private function computeAssociationChanges(array $assoc, $value): void
         }
     }
 
-    /**
-     * @param ClassMetadata $class
-     * @param object        $entity
-     *
-     * @return void
-     */
-    private function persistNew($class, $entity)
+    private function persistNew(ClassMetadata $class, object $entity): void
     {
         $oid    = spl_object_hash($entity);
         $invoke = $this->listenersInvoker->getSubscribedSystems($class, Events::prePersist);
@@ -1092,12 +1080,8 @@ public function recomputeSingleEntityChangeSet(ClassMetadata $class, $entity)
 
     /**
      * Executes all entity insertions for entities of the specified type.
-     *
-     * @param ClassMetadata $class
-     *
-     * @return void
      */
-    private function executeInserts($class)
+    private function executeInserts(ClassMetadata $class): void
     {
         $entities  = [];
         $className = $class->name;
@@ -1156,11 +1140,11 @@ private function executeInserts($class)
         }
     }
 
-    /**
-     * @param object $entity
-     */
-    private function addToEntityIdentifiersAndEntityMap(ClassMetadata $class, string $oid, $entity): void
-    {
+    private function addToEntityIdentifiersAndEntityMap(
+        ClassMetadata $class,
+        string $oid,
+        object $entity
+    ): void {
         $identifier = [];
 
         foreach ($class->getIdentifierFieldNames() as $idField) {
@@ -1182,12 +1166,8 @@ private function addToEntityIdentifiersAndEntityMap(ClassMetadata $class, string
 
     /**
      * Executes all entity updates for entities of the specified type.
-     *
-     * @param ClassMetadata $class
-     *
-     * @return void
      */
-    private function executeUpdates($class)
+    private function executeUpdates(ClassMetadata $class): void
     {
         $className        = $class->name;
         $persister        = $this->getEntityPersister($className);
@@ -1219,12 +1199,8 @@ private function executeUpdates($class)
 
     /**
      * Executes all entity deletions for entities of the specified type.
-     *
-     * @param ClassMetadata $class
-     *
-     * @return void
      */
-    private function executeDeletions($class)
+    private function executeDeletions(ClassMetadata $class): void
     {
         $className = $class->name;
         $persister = $this->getEntityPersister($className);
@@ -2039,15 +2015,13 @@ private function doMerge(
     }
 
     /**
-     * @param object $entity
-     * @param object $managedCopy
-     *
-     * @return void
-     *
      * @throws OptimisticLockException
      */
-    private function ensureVersionMatch(ClassMetadata $class, $entity, $managedCopy)
-    {
+    private function ensureVersionMatch(
+        ClassMetadata $class,
+        object $entity,
+        object $managedCopy
+    ): void {
         if (! ($class->isVersioned && $this->isLoaded($managedCopy) && $this->isLoaded($entity))) {
             return;
         }
@@ -2067,12 +2041,8 @@ private function ensureVersionMatch(ClassMetadata $class, $entity, $managedCopy)
 
     /**
      * Tests if an entity is loaded - must either be a loaded proxy or not a proxy
-     *
-     * @param object $entity
-     *
-     * @return bool
      */
-    private function isLoaded($entity)
+    private function isLoaded(object $entity): bool
     {
         return ! ($entity instanceof Proxy) || $entity->__isInitialized();
     }
@@ -2125,14 +2095,14 @@ public function detach($entity)
     /**
      * Executes a detach operation on the given entity.
      *
-     * @param object  $entity
      * @param mixed[] $visited
      * @param bool    $noCascade if true, don't cascade detach operation.
-     *
-     * @return void
      */
-    private function doDetach($entity, array &$visited, $noCascade = false)
-    {
+    private function doDetach(
+        object $entity,
+        array &$visited,
+        bool $noCascade = false
+    ): void {
         $oid = spl_object_hash($entity);
 
         if (isset($visited[$oid])) {
@@ -2614,12 +2584,7 @@ public function isCollectionScheduledForDeletion(PersistentCollection $coll)
         return isset($this->collectionDeletions[spl_object_hash($coll)]);
     }
 
-    /**
-     * @param ClassMetadata $class
-     *
-     * @return ObjectManagerAware|object
-     */
-    private function newInstance($class)
+    private function newInstance(ClassMetadata $class): object
     {
         $entity = $class->newInstance();
 
diff --git a/lib/Doctrine/ORM/Utility/IdentifierFlattener.php b/lib/Doctrine/ORM/Utility/IdentifierFlattener.php
index 954501d4a4b..216fd66cb05 100644
--- a/lib/Doctrine/ORM/Utility/IdentifierFlattener.php
+++ b/lib/Doctrine/ORM/Utility/IdentifierFlattener.php
@@ -64,7 +64,7 @@ public function __construct(UnitOfWork $unitOfWork, ClassMetadataFactory $metada
      *
      * @psalm-return array<string, mixed>
      */
-    public function flattenIdentifier(ClassMetadata $class, array $id)
+    public function flattenIdentifier(ClassMetadata $class, array $id): array
     {
         $flatId = [];