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<?php $a = array(); $a[] = &$a; preg_grep('/abc/', $a); var_dump($a); ?>
Output for 8.0.0 - 8.0.30, 8.1.0 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.25, 8.4.1 - 8.4.12
Warning: Array to string conversion in /in/0f1ba on line 4 array(1) { [0]=> *RECURSION* }
Output for 5.2.14 - 5.2.17, 5.3.3 - 5.3.29, 5.4.0 - 5.4.45, 5.5.0 - 5.5.38, 5.6.0 - 5.6.40, 7.0.0 - 7.0.33, 7.1.0 - 7.1.27, 7.2.0 - 7.2.33, 7.3.0 - 7.3.31, 7.4.0 - 7.4.33
Notice: Array to string conversion in /in/0f1ba on line 4 array(1) { [0]=> &array(1) { [0]=> *RECURSION* } }
Output for 7.3.32 - 7.3.33
array(1) { [0]=> &array(1) { [0]=> *RECURSION* } }
Output for 5.2.7 - 5.2.13, 5.3.0 - 5.3.2
Notice: Array to string conversion in /in/0f1ba on line 4 array(1) { [0]=> &array(1) { [0]=> &array(1) { [0]=> *RECURSION* } } }
Output for 5.1.0 - 5.1.6, 5.2.0 - 5.2.6
Notice: Array to string conversion in /in/0f1ba on line 4 string(5) "Array"
Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.9, 5.0.0 - 5.0.5
Notice: Array to string conversion in /in/0f1ba on line 4 array(1) { [0]=> array(1) { [0]=> *RECURSION* } }

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