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<?php $a = ['teste' => 'teste']; $key = 'teste'; var_dump($a[$key] ?? ($key === null ? $a : null));
Output for 7.0.0 - 7.0.33, 7.1.0 - 7.1.25, 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 - 8.2.18, 8.3.0 - 8.3.6
string(5) "teste"
Output for 5.5.0 - 5.5.38, 5.6.0 - 5.6.38
Parse error: syntax error, unexpected '?' in /in/svMq8 on line 5
Process exited with code 255.

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