Bypassing readonly properties without visibilty can change behavior

[ms2ad]

Reproduction example:

1. composer require dg/bypass-finals --dev
2. index.php:

<?php

require_once __DIR__ . '/vendor/autoload.php';

\DG\BypassFinals::enable();

require_once __DIR__ . '/include.php';

new A('A');
new B('B');

3. include.php:

<?php

class A {
    public function __construct(
        readonly string $a
    ) {
        var_dump('A: ' . $this->a);
    }
}

class B {
    public function __construct(
        public readonly string $a
    ) {
        var_dump('B: ' . $this->a);
    }
}

Result:

php index.php
PHP Warning:  Undefined property: A::$a in /…/test-bypassfinals/include.php on line 7

Warning: Undefined property: A::$a in /…/test-bypassfinals/include.php on line 7
string(3) "A: "
string(4) "B: B"

The problem stems from the fact that readonly is just removed from the code thus changing the promoted property to a simple constructor argument and thus changing behavior.

Context: We use a third-party library that does uses this kind of code.

---

I am unsure whether this package can really fix this issue because at the moment, a "simple" replace logic without considering the context is used. Here, the context of being a promoted property would have to be known and readonly replaced with public.

[dg]

Resolving this issue is not easy because the parser must now distinguish when readonly is used with a class, when with a property with visibility, and when with a property without it. I will probably stick with the fact that it will be incompatible with code written this way.