Circular references may cause segmentation fault

circular-references-segfault.php

<?php
// Conclusion: This code will cause Segmentation fault, because
// of recursive calls to __clone(), but PHP should handle this.

// Bug filed here: http://bugs.php.net/bug.php?id=49664


date_default_timezone_set('America/Los_Angeles');
class Test {
    public $previous, $next = NULL;
    public $name = NULL;
    public function __construct($name) {
        $this->name = $name;
    }
    public function __clone() {
        $this->previous != NULL ? $this->previous = clone $this->previous : false;
        $this->next != NULL ? $this->next = clone $this->next : false;
    }
    public function __toString() {
        
 return $this->name . ' [' . ($this->previous != NULL ? '<' : 
'-') . ' ' . ($this->next != NULL ? '>' : '-') . ']';
    }
}

// Create some test objects
$a = new Test('a'); $b = new Test('b');

// Link them together
$a->next =& $b; $b->previous =& $a;

// Clone and print
echo "before cloning:\n" . $a . "\n" . $b . "\n";
$b = clone $a;
echo "These two should NOT look the same:\n" . $a . "\n" . $b . "\n";


// Will output:

// before cloning:
// a [- >]
// b [< -]
// Segmentation fault