Fix association mapping with enum fields

Enum fields as ID have worked for some time, but referencing these fields from other entities in association mappings such as OneToOne, ManyToOne and ManyToMany resulted in fatal error as there was an attempt to convert enum value to string improperly.

lib/Doctrine/ORM/UnitOfWork.php

@@ -2812,6 +2812,10 @@ public function createEntity($className, array $data, &$hints = [])
                         $joinColumnValue = $data[$srcColumn] ?? null;
 
                         if ($joinColumnValue !== null) {
+                            if ($joinColumnValue instanceof BackedEnum) {
+                                $joinColumnValue = $joinColumnValue->value;
+                            }
+
                             if ($targetClass->containsForeignIdentifier) {
                                 $associatedId[$targetClass->getFieldForColumn($targetColumn)] = $joinColumnValue;
                             } else {

tests/Doctrine/Tests/Models/GH10132/Complex.php

@@ -0,0 +1,51 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\Tests\Models\GH10132;
+
+use Doctrine\Common\Collections\ArrayCollection;
+use Doctrine\Common\Collections\Collection;
+use Doctrine\ORM\Mapping\Column;
+use Doctrine\ORM\Mapping\Entity;
+use Doctrine\ORM\Mapping\Id;
+use Doctrine\ORM\Mapping\OneToMany;
+use Doctrine\Tests\Models\Enums\Suit;
+
+/** @Entity */
+class Complex
+{
+    /**
+     * @Id
+     * @Column(type = "string", enumType = Suit::class)
+     */
+    protected Suit $type;
+
+    /** @OneToMany(targetEntity = ComplexChild::class, mappedBy = "complex", cascade = {"persist"}) */
+    protected Collection $complexChildren;
+
+    public function __construct()
+    {
+        $this->complexChildren = new ArrayCollection();
+    }
+
+    public function getType(): Suit
+    {
+        return $this->type;
+    }
+
+    public function setType(Suit $type): void
+    {
+        $this->type = $type;
+    }
+
+    public function getComplexChildren(): Collection
+    {
+        return $this->complexChildren;
+    }
+
+    public function addComplexChild(ComplexChild $complexChild): void
+    {
+        $this->complexChildren->add($complexChild);
+    }
+}

tests/Doctrine/Tests/Models/GH10132/ComplexChild.php

@@ -0,0 +1,45 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\Tests\Models\GH10132;
+
+use Doctrine\ORM\Mapping\Column;
+use Doctrine\ORM\Mapping\Entity;
+use Doctrine\ORM\Mapping\Id;
+use Doctrine\ORM\Mapping\JoinColumn;
+use Doctrine\ORM\Mapping\ManyToOne;
+use Doctrine\Tests\Models\Enums\Suit;
+
+/** @Entity */
+class ComplexChild
+{
+    /**
+     * @ManyToOne(targetEntity = Complex::class, inversedBy = "complexChildren")
+     * @JoinColumn(name = "complexType", referencedColumnName = "type", nullable = false)
+     */
+    protected Complex $complex;
+
+    /**
+     * @Id
+     * @Column(type = "string", enumType = Suit::class)
+     */
+    protected Suit $complexType;
+
+    public function setComplex(Complex $complex): void
+    {
+        $complex->addComplexChild($this);
+        $this->complexType = $complex->getType();
+        $this->complex     = $complex;
+    }
+
+    public function getComplexType(): Suit
+    {
+        return $this->complexType;
+    }
+
+    public function getComplex(): Complex
+    {
+        return $this->complex;
+    }
+}

tests/Doctrine/Tests/ORM/Functional/Ticket/GH10132Test.php

@@ -0,0 +1,49 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\Tests\ORM\Functional\Ticket;
+
+use Doctrine\Tests\Models\Enums\Suit;
+use Doctrine\Tests\Models\GH10132\Complex;
+use Doctrine\Tests\Models\GH10132\ComplexChild;
+use Doctrine\Tests\OrmFunctionalTestCase;
+
+/**
+ * @requires PHP 8.1
+ */
+class GH10132Test extends OrmFunctionalTestCase
+{
+    public function setUp(): void
+    {
+        parent::setUp();
+
+        $this->createSchemaForModels(
+            Complex::class,
+            ComplexChild::class
+        );
+    }
+
+    public function testQueryBackedEnumInCompositeKeyJoin(): void
+    {
+        $complex = new Complex();
+        $complex->setType(Suit::Clubs);
+
+        $complexChild = new ComplexChild();
+        $complexChild->setComplex($complex);
+
+        $this->_em->persist($complex);
+        $this->_em->persist($complexChild);
+        $this->_em->flush();
+        $this->_em->clear();
+
+        $qb = $this->_em->createQueryBuilder();
+        $qb->select('s')
+            ->from(ComplexChild::class, 's')
+            ->where('s.complexType = :complexType');
+
+        $qb->setParameter('complexType', Suit::Clubs);
+
+        self::assertNotNull($qb->getQuery()->getOneOrNullResult());
+    }
+}