3v4l.org

run code in 500+ PHP versions simultaneously
<?php class Foo implements Iterator { public function current(): Foo { return $this; } public function key(): Foo { return $this; } public function next(): void {} public function rewind(): void {} public function valid(): bool { return true; } } foreach ( new Foo as $key => $value ) { var_dump($key, $value); break; }
Output for 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 - 8.1.34, 8.2.0 - 8.2.30, 8.3.0 - 8.3.30, 8.4.1 - 8.4.18, 8.5.0 - 8.5.3
object(Foo)#1 (0) { } object(Foo)#1 (0) { }

preferences:
107.3 ms | 1479 KiB | 4 Q