如果SplObjectStorage实例在仍然附着一些对象的情况下发生破坏，它是否首先隐式分离对象，或者SplObjectStorage对那些悬空对象的引用会导致内存泄漏？我试图确定是否需要使用用户区代码“分离销毁前剩下的任何东西”来防止这种内存泄漏。
$storage = new SplObjectStorage();
$x = new stdClass();
$y = new stdClass();
$storage->attach($x);
$storage->attach($y);
$storage = null;
// did not explicitly detach $x and $y... does $storage's destruction do it?
// or do the zval counts on $x and $y now off by one?
$x = null;
$y = null;
// at this point, are there two dangling references to $x and $y,
// simply because $storage did not dereference from them before destroying itself?