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<?php $arr = [ 'deep' => [ 'bar' => 'foo', ], ]; foreach($arr['deep'] ?? [] as &$value) { $value = 'x'; } var_dump('x' === $arr['deep']['bar']); foreach($arr['deep'] as &$value) { $value = 'x'; } var_dump('x' === $arr['deep']['bar']);
Output for 8.0.1 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
bool(false) bool(true)

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