PHP 8.1: Unable to load classes with public readonly properties

[AnnaDamm]

When loading a class with readonly properties, an error is thrown: PHP Fatal error: Uncaught Error: Cannot initialize readonly property ...

This happens, because readonly properties

TestCase:

<?php

require 'vendor/autoload.php';

use Brick\VarExporter\VarExporter;

class Test
{
    public function __construct(
        public readonly string $foo
    ) {
    }
}

$object = new Test('bar');
$string = VarExporter::export($object, VarExporter::ADD_RETURN);
echo $string;

$newObject = eval($string);
echo "yay!";

Output

return (static function() {
    $class = new \ReflectionClass(\Test::class);
    $object = $class->newInstanceWithoutConstructor();

    $object->foo = 'bar';

    return $object;
})();

Fatal error: Uncaught Error: Cannot initialize readonly property Test::$foo from global scope in  test.php(19) : eval()'d code on line 5

Error: Cannot initialize readonly property Test::$foo from global scope in test.php(19) : eval()'d code on line 5

Expected Output

return (static function() {
    $class = new \ReflectionClass(\Test::class);
    $object = $class->newInstanceWithoutConstructor();
    (function() {
        $this->foo = 'bar';
    })->bindTo($object, \Test::class)();

    return $object;
})();yay!

Possible solution

instead of just setting the property on the object via $object->foo = 'bar' it should be set via bindTo:

(function() {
        $this->foo = 'bar';
    })->bindTo($object, \Test::class)();

one could use $property-> isReadOnly to determine if this is necessary.