Prevents incorrect table aliases to be generated

When a defined subclass has a case typo, the query builder will be lost
and will generate exotic table alias. This commit fixes the issue at the
root by prohibiting case typo in discriminator map.

See #8112 for the consequence of
such typo.

lib/Doctrine/ORM/Mapping/ClassMetadata.php

@@ -10,6 +10,7 @@
 use Doctrine\ORM\Reflection\ReflectionService;
 use Doctrine\ORM\Sequencing\Planning\ValueGenerationPlan;
 use Doctrine\ORM\Utility\PersisterHelper;
+use ReflectionClass;
 use ReflectionException;
 use RuntimeException;
 use function array_filter;
@@ -1002,6 +1003,11 @@ public function addDiscriminatorMapClass($name, string $className) : void
             throw MappingException::invalidClassInDiscriminatorMap($className, $this->className);
         }
 
+        $refl = new ReflectionClass($className);
+        if ($refl->name !== $className) {
+            throw MappingException::invalidClassInDiscriminatorMap($className, $this->className);
+        }
+
         if (is_subclass_of($className, $this->className) && ! in_array($className, $this->subClasses, true)) {
             $this->subClasses[] = $className;
         }

tests/Doctrine/Tests/ORM/Mapping/AbstractMappingDriverTest.php

@@ -1081,6 +1081,15 @@ public function testDiscriminatorColumnDefaultName() : void
 
         self::assertEquals('dtype', $class->discriminatorColumn->getColumnName());
     }
+
+    /**
+     * @expectedException \Doctrine\ORM\Mapping\MappingException
+     * @expectedExceptionMessage Entity class 'Doctrine\Tests\ORM\Mapping\cube' used in the discriminator map of class 'Doctrine\Tests\ORM\Mapping\Shape' does not exist.
+     */
+    public function testInvalidSubClassCase()
+    {
+        $this->createClassMetadata(Shape::class);
+    }
 }
 
 /**
@@ -1344,6 +1353,25 @@ class Dog extends Animal
 {
 }
 
+/**
+ * @ORM\Entity
+ * @ORM\InheritanceType("SINGLE_TABLE")
+ * @ORM\DiscriminatorMap({"cube" = cube::class})
+ * @ORM\DiscriminatorColumn(name="discr", length=32, type="string")
+ */
+abstract class Shape
+{
+    /**
+     * @ORM\Id @ORM\Column(type="string") @ORM\GeneratedValue(strategy="AUTO")
+     */
+    public $id;
+}
+
+/** @ORM\Entity */
+class Cube extends Shape
+{
+}
+
 /**
  * @ORM\Entity
  */

tests/Doctrine/Tests/ORM/Mapping/xml/Doctrine.Tests.ORM.Mapping.Shape.dcm.xml

@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<doctrine-mapping xmlns="http://doctrine-project.org/schemas/orm/doctrine-mapping"
+      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+      xsi:schemaLocation="http://doctrine-project.org/schemas/orm/doctrine-mapping
+                          https://www.doctrine-project.org/schemas/orm/doctrine-mapping.xsd">
+    <entity name="Doctrine\Tests\ORM\Mapping\Shape" inheritance-type="SINGLE_TABLE">
+        <discriminator-column name="discr" type="string" length="32" />
+        <discriminator-map>
+            <discriminator-mapping value="cube" class="Doctrine\Tests\ORM\Mapping\cube" />
+        </discriminator-map>
+        <id name="id" type="integer" column="id">
+            <generator strategy="AUTO" />
+        </id>
+    </entity>
+</doctrine-mapping>