Can Clone Readonly Properties

Readonly properties may be changed, both at constructor and cloning time, since PHP 8.3. Until then, they could not be changed, once set.

PHP code

<?php

class x {
     readonly int $p;

     function __construct() {
             $this->p = 2;
     }

     function __clone() {
             $this->p++;
     }
}

$x = new x;
$y = clone $x;

var_dump($y);

?>

Before

PHP Fatal error:  Uncaught Error: Cannot modify readonly property x::$p in /codes/cloneReadonly.php:11
Stack trace:
#0 /codes/cloneReadonly.php(16): x->__clone()
#1 {main}
  thrown in /codes/cloneReadonly.php on line 11

Fatal error: Uncaught Error: Cannot modify readonly property x::$p in /codes/cloneReadonly.php:11
Stack trace:
#0 /codes/cloneReadonly.php(16): x->__clone()
#1 {main}
  thrown in /codes/cloneReadonly.php on line 11

After

object(x)#2 (1) {
  ["p"]=>
  int(3)
}

PHP version change

This behavior changed in 8.3

Error Messages

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