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<?php declare(strict_types = 1); $a = []; $a[-4] = 1; $a[] = 2; var_dump(array_keys($a));
Output for 8.3.3 - 8.3.30, 8.4.1 - 8.4.18, 8.5.0 - 8.5.3
array(2) { [0]=> int(-4) [1]=> int(-3) }
Output for 8.1.28 - 8.1.34, 8.2.17, 8.2.19 - 8.2.30
array(2) { [0]=> int(-4) [1]=> int(0) }
Output for 8.2.18
Warning: PHP Startup: Unable to load dynamic library 'sodium.so' (tried: /usr/lib/php/8.2.18/modules/sodium.so (libsodium.so.23: cannot open shared object file: No such file or directory), /usr/lib/php/8.2.18/modules/sodium.so.so (/usr/lib/php/8.2.18/modules/sodium.so.so: cannot open shared object file: No such file or directory)) in Unknown on line 0 array(2) { [0]=> int(-4) [1]=> int(0) }

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