also reject \DateTime subclasses

Author: xabbuh

Mapping/Read/DateTimeTypePropertyMetadataLoader.php

@@ -38,7 +38,7 @@ public function load(string $className, array $options = [], array $context = []
             $type = $metadata->getType();
 
             if ($type instanceof ObjectType && is_a($type->getClassName(), \DateTimeInterface::class, true)) {
-                if (\DateTime::class === $type->getClassName()) {
+                if (is_a($type->getClassName(), \DateTime::class, true)) {
                     throw new InvalidArgumentException('The "DateTime" class is not supported. Use "DateTimeImmutable" instead.');
                 }
 

Tests/Mapping/Read/DateTimeTypePropertyMetadataLoaderTest.php

@@ -47,6 +47,18 @@ public function testThrowWhenDateTimeType()
         $loader->load(self::class);
     }
 
+    public function testThrowWhenDateTimeSubclassType()
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('The "DateTime" class is not supported. Use "DateTimeImmutable" instead.');
+
+        $loader = new DateTimeTypePropertyMetadataLoader(self::propertyMetadataLoader([
+            'mutable' => new PropertyMetadata('mutable', Type::object(DateTimeChild::class)),
+        ]));
+
+        $loader->load(self::class);
+    }
+
     /**
      * @param array<string, PropertyMetadata> $propertiesMetadata
      */
@@ -64,3 +76,7 @@ public function load(string $className, array $options = [], array $context = []
         };
     }
 }
+
+class DateTimeChild extends \DateTime
+{
+}