--TEST-- Bug #79108: Referencing argument in a function makes it a reference in the stack trace --FILE-- <?php function test(string $val) { $a = &$val; hackingHere(); print_r($val); } function hackingHere() { // we're able to modify the $val from here, even though the arg was not a reference debug_backtrace()[1]['args'][0] = 'Modified'; } test('Original'); ?> --EXPECT-- Original