3v4l.org

run code in 300+ PHP versions simultaneously
<?php namespace NS { class C { public $fn; public function __construct() { $this->fn = function (string $arg) { var_dump("fn"); }; } } } namespace { $fn = (new NS\C)->fn; $fn("null"); echo "Done\n"; }
Output for 7.0.0 - 7.0.20, 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 - 8.2.19, 8.3.0 - 8.3.7
string(2) "fn" Done
Output for 5.4.2 - 5.4.45, 5.5.24 - 5.5.35, 5.6.8 - 5.6.28
Catchable fatal error: Argument 1 passed to NS\C::NS\{closure}() must be an instance of NS\string, string given, called in /in/6pNY6 on line 17 and defined in /in/6pNY6 on line 8
Process exited with code 255.
preferences:
192.02 ms | 402 KiB | 271 Q