Does SplObjectStorage leave memory leak references if it destructs while objects are still attached?

Question

If an SplObjectStorage instance destructs while still having some objects attached, does it implicitly detach the objects first, or does a memory leak result by the SplObjectStorage's references to those dangling objects? I'm trying to determine if userland code to "detach anything that's left before destructing" is necessary to prevent such a memory leak.

$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?

Answer 1

The simple answer is: it should free those two objects.

If this is not the case, this should be considered a bug.

To test: create a class with a destructor, and ensure that it's called.