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run code in 150+ php & hhvm versions
Bugs & Features
<?php $a = [1, 2]; usort($a, function ($a, $b) { var_dump(debug_backtrace()); exit; });
Output for 7.0.0 - 7.1.0
array(2) { [0]=> array(2) { ["function"]=> string(9) "{closure}" ["args"]=> array(2) { [0]=> int(1) [1]=> int(2) } } [1]=> array(4) { ["file"]=> string(9) "/in/j9Dv7" ["line"]=> int(4) ["function"]=> string(5) "usort" ["args"]=> array(2) { [0]=> &array(2) { [0]=> int(1) [1]=> int(2) } [1]=> object(Closure)#1 (1) { ["parameter"]=> array(2) { ["$a"]=> string(10) "<required>" ["$b"]=> string(10) "<required>" } } } } }
Output for hhvm-3.12.0
array(1) { [0]=> array(4) { ["file"]=> string(9) "/in/j9Dv7" ["line"]=> int(4) ["function"]=> string(8) "Closure$" ["args"]=> array(2) { [0]=> int(1) [1]=> int(2) } } }
Output for hhvm-3.10.0

Process exited with code 153.
Output for 5.4.0 - 5.6.28
array(2) { [0]=> array(2) { ["function"]=> string(9) "{closure}" ["args"]=> array(2) { [0]=> &int(2) [1]=> &int(1) } } [1]=> array(4) { ["file"]=> string(9) "/in/j9Dv7" ["line"]=> int(4) ["function"]=> string(5) "usort" ["args"]=> array(2) { [0]=> &array(2) { [0]=> int(1) [1]=> int(2) } [1]=> object(Closure)#1 (1) { ["parameter"]=> array(2) { ["$a"]=> string(10) "<required>" ["$b"]=> string(10) "<required>" } } } } }
Output for 4.4.2 - 4.4.9, 5.1.0 - 5.3.29
Parse error: syntax error, unexpected '[' in /in/j9Dv7 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/j9Dv7 on line 3
Process exited with code 255.
Output for 4.3.2 - 4.3.4
Parse error: parse error in /in/j9Dv7 on line 3
Process exited with code 255.