Final Promoted Properties

Promoted properties could not be final until PHP 8.5.

PHP code

<?php

class x {
    function __construct(
        public final int $i
    ) {}
}

var_dump(new x(1));

?>

Before

PHP Fatal error:  Cannot use the final modifier on a parameter

Fatal error: Cannot use the final modifier on a parameter

After

object(x)#1 (1) {
  ["i"]=>
  int(1)
}

PHP version change

This behavior changed in 8.5

Error Messages