3v4l.org

run code in 300+ PHP versions simultaneously
<?php $foo = null; $foo = function() use ($foo){ return &$foo; }; var_dump($foo()->__invoke()==$foo);
Output for 5.3.0 - 5.3.28, 5.4.0 - 5.4.30
Parse error: syntax error, unexpected '&' in /in/r0dgZ on line 4
Process exited with code 255.
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198.15 ms | 1395 KiB | 67 Q