3v4l.org

run code in 200+ php & hhvm versions
<?php $array = []; $array["a"] =& $array["b"]; $array["b"] = 1; var_dump($array);
Output for 5.4.0 - 5.6.40, hhvm-3.10.1 - 3.22.0, 7.1.0 - 7.3.5
array(2) { ["b"]=> &int(1) ["a"]=> &int(1) }
Output for 7.0.0 - 7.0.33
array(2) { ["a"]=> &int(1) ["b"]=> &int(1) }
Output for 4.4.2 - 4.4.9, 5.1.0 - 5.3.29
Parse error: syntax error, unexpected '[' in /in/frbUc on line 3
Process exited with code 255.
Output for 4.3.0 - 4.3.1, 4.3.5 - 4.4.1, 5.0.0 - 5.0.5
Parse error: parse error, unexpected '[' in /in/frbUc on line 3
Process exited with code 255.
Output for 4.3.2 - 4.3.4
Parse error: parse error in /in/frbUc on line 3
Process exited with code 255.