Description:
------------
In the following Script 1 and Script 2, the created objects are not destructed until the engine shutdowns because of a reference cycle.

The objects hold a reference to an anonymous function that itself hold a reference to the object.

It seems that the garbage collector is unable to break the cycle.

Script 3 doesn't leak memory because the anonymous function doesn't hold a reference to the object.

Test script:
---------------
# Script 1 (leaks with php5.4)

<?php

class Foo
{
    public $x;

    public function __construct() {
        $this->x = function() {};
    }
}

echo memory_get_usage(), "\n";

for ($i = 0; $i < 1000; ++$i) {
    new Foo;
}
gc_collect_cycles();

echo memory_get_usage(), "\n";
?>

# Script 2 (leaks with php5.3)

<?php

class Foo
{
    public $x;

    public function __construct() {
        $self = $this;
        $this->x = function() use ($self) {};
    }
}

echo memory_get_usage(), "\n";

for ($i = 0; $i < 1000; ++$i) {
    new Foo;
}
gc_collect_cycles();

echo memory_get_usage(), "\n";

?>

# Script 3 (no leak)

<?php

class Foo
{
    public $x;

    public function __construct() {
        $this->x = get_fun();
    }
}

function get_fun() {
    return function() {};
}

echo memory_get_usage(), "\n";

for ($i = 0; $i < 1000; ++$i) {
    new Foo;
}
gc_collect_cycles();

echo memory_get_usage(), "\n";
?>

Expected result:
----------------
Memory usage before and after is approximatel the same:

121040
121152

Actual result:
--------------
Objects are never freed and memory usage increases:

120724
417640