php / php/doc-en

isset() on hooks doesn't respect backing value

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#5,040 6 comments 0 reactions 0 assignees View on GitHub

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bug Status: Needs Triage
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Description

Description

The following code:

<?php

class User {
	public ?string $id {
		get => $this->id; // get => $this->id ?? null; works
		set => $this->id = $value;
	}
}

class User2 {
    public string $id;
}

$u = new User();
$u2 = new User2();
var_dump(isset($u2->id));//false OK
var_dump(isset($u->id));//error

Resulted in this output:
First var_dump retuns false and this is ok, second - produces Fatal error: Uncaught Error: Typed property User::$id must not be accessed before initialization
But I expected this output instead:
false two times

This suggests that isset() on hooked properties may incorrectly trigger property access instead of checking initialization state, unlike regular typed properties.

PHP Version
PHP 8.5.0 (cli) (built: Nov 20 2025 19:17:11) (NTS)
Copyright (c) The PHP Group
Built by Debian
Zend Engine v4.5.0, Copyright (c) Zend Technologies
    with Zend OPcache v8.5.0, Copyright (c), by Zend Technologies

PHP 8.4.15 (cli) (built: Nov 20 2025 17:43:25) (NTS)
Copyright (c) The PHP Group
Built by Debian
Zend Engine v4.4.15, Copyright (c) Zend Technologies
    with Zend OPcache v8.4.15, Copyright (c), by Zend Technologies
    with Xdebug v3.4.7, Copyright (c) 2002-2025, by Derick Rethans
Operating System

No response

Contributor guide

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Reproduce the supplied hooked-property example on PHP 8.4 and 8.5, then determine whether the behavior is a PHP runtime defect or a documentation gap. Check the relevant PHP documentation for hooked properties and isset(); done means the issue is routed to the appropriate fix with the expected behavior and a regression or documentation update identified.

Written by the indexing model from the issue text.

Assessment

Tech stack
php
Domain
backend
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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