3v4l.org

run code in 300+ PHP versions simultaneously
<?php class A{ function __debugInfo(){ $x['lol'] = $this; return $x; } } class B{ private $lol; function __construct(){ $this->lol = $this; } } var_dump(new B);
Output for 5.4.0 - 5.4.45, 5.5.0 - 5.5.38, 5.6.0 - 5.6.40, 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.7
object(B)#1 (1) { ["lol":"B":private]=> *RECURSION* }
preferences:
254.84 ms | 404 KiB | 377 Q