Add test for #35895

ext/standard/tests/serialize/bug35895.phpt

@@ -0,0 +1,24 @@
+--TEST--
+Bug #35895 (__sleep and private property)
+--FILE--
+<?php
+class Parents {
+   private $parents;
+   public function __sleep() {
+       return array("parents");
+   }
+}
+
+class Child extends Parents {
+    private $child;
+    public function __sleep() {
+        return array_merge(array("child"), parent::__sleep());
+    }
+}
+
+$obj = new Child();
+serialize($obj);
+
+?>
+--EXPECTF--
+Notice: serialize(): "parents" returned as member variable from __sleep() but does not exist in %sbug35895.php on line %d