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<?php class Foo { public function byRef(&$val) { $val = 'replaced'; } } $f = new Foo(); $var = ['original']; array_map($f->byRef(...), $var); print_r($var);
Output for 8.3.0 - 8.3.30, 8.4.1 - 8.4.18, 8.5.0 - 8.5.3
Warning: Foo::byRef(): Argument #1 ($val) must be passed by reference, value given in /in/b1KoE on line 9 Array ( [0] => original )

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