PHPC-1230: Allow cloning Undefined objects

Author: alcaeus

src/BSON/Undefined.c

@@ -148,6 +148,8 @@ void php_phongo_undefined_init_ce(INIT_FUNC_ARGS) /* {{{ */
 	zend_class_implements(php_phongo_undefined_ce TSRMLS_CC, 1, zend_ce_serializable);
 
 	memcpy(&php_phongo_handler_undefined, phongo_get_std_object_handlers(), sizeof(zend_object_handlers));
+	/* Re-assign default handler previously removed in php_phongo.c */
+	php_phongo_handler_undefined.clone_obj = zend_objects_clone_obj;
 #if PHP_VERSION_ID >= 70000
 	php_phongo_handler_undefined.free_obj = php_phongo_undefined_free_object;
 	php_phongo_handler_undefined.offset   = XtOffsetOf(php_phongo_undefined_t, std);

tests/bson/bson-undefined-clone-001.phpt

@@ -0,0 +1,22 @@
+--TEST--
+MongoDB\BSON\Undefined can be cloned
+--FILE--
+<?php
+
+require_once __DIR__ . '/../utils/tools.php';
+
+$test = MongoDB\BSON\toPHP(MongoDB\BSON\fromJSON('{ "undefined": {"$undefined": true} }'));
+
+$undefined = $test->undefined;
+
+$clone = clone $undefined;
+
+var_dump($clone == $undefined);
+var_dump($clone === $undefined);
+?>
+===DONE===
+<?php exit(0); ?>
+--EXPECT--
+bool(true)
+bool(false)
+===DONE===