ReflectionClass can't detect readonly properties for mysqli

[RV7PR]

Description

The following code:

<?php
$reflection = new ReflectionClass(mysqli::class);
$props = [];
foreach ($reflection->getProperties() as $property) {
    $props[] = $property->getName() . ' | readonly: ' . (int) $property->isReadOnly();
}
print_r($props);

Resulted in this output:

Array
(
    [0] => affected_rows | readonly: 0
    [1] => client_info | readonly: 0
    [2] => client_version | readonly: 0
    [3] => connect_errno | readonly: 0
    [4] => connect_error | readonly: 0
    [5] => errno | readonly: 0
    [6] => error | readonly: 0
    [7] => error_list | readonly: 0
    [8] => field_count | readonly: 0
    [9] => host_info | readonly: 0
    [10] => info | readonly: 0
    [11] => insert_id | readonly: 0
    [12] => server_info | readonly: 0
    [13] => server_version | readonly: 0
    [14] => sqlstate | readonly: 0
    [15] => protocol_version | readonly: 0
    [16] => thread_id | readonly: 0
    [17] => warning_count | readonly: 0
)

But I expected this output instead:

Array
(
    [0] => affected_rows | readonly: 1
    [1] => client_info | readonly: 1
    [2] => client_version | readonly: 1
    [3] => connect_errno | readonly: 1
    [4] => connect_error | readonly: 1
    [5] => errno | readonly: 1
    [6] => error | readonly: 1
    [7] => error_list | readonly: 1
    [8] => field_count | readonly: 1
    [9] => host_info | readonly: 1
    [10] => info | readonly: 1
    [11] => insert_id | readonly: 1
    [12] => server_info | readonly: 1
    [13] => server_version | readonly: 1
    [14] => sqlstate | readonly: 1
    [15] => protocol_version | readonly: 1
    [16] => thread_id | readonly: 1
    [17] => warning_count | readonly: 1
)

PHP Version

PHP 8.3.8

Operating System

No response

[iluuu1994]

This is not bug, because these properties are not really readonly.

php-src/ext/mysqli/mysqli.stub.php

Lines 616 to 617 in 46ee0fb

	/** @readonly */
	public string $client_info;

The @readonly is only added for documentation purposes. mysqli handles property writes through custom object handlers that predate the readonly keyword, and they have not been migrated over. We can treat this as a feature request though.

[nielsdos]

The way I see it is that it's more like a "get" hook without a "set" hook. Reason being that the extension can still change the value. So I think that isReadOnly should actually return false.

[RV7PR]

Well, internally that may be true but on the user side it's still readonly so I think it should return true

[iluuu1994]

Readonly currently also means that the value never changes. If the value can change then readonly is not the correct flag to use.

[cmb69]

The way I see it is that it's more like a "get" hook without a "set" hook. Reason being that the extension can still change the value. So I think that isReadOnly should actually return false.

So ReflectionProperty::getHooks() and friends should ideally be implemented; at least, gen_stubs.php (and PhD) should be improved to handle @property-read annotations. Is there already someone working on this (or is it planned)?

[iluuu1994]

It gets a bit worse, since we can have a missing set operation (from the users pov) through various mechanisms:

• readonly.
• Hooks with no set, but only when the property is virtual.
• Hooks implemented through object handlers. The set really just throws an exception.
• Soon, private(set).

Maybe we should have something like: is{Readable,Writeable}(?string $fromScope = null). It's not completely clear whether the default should refer to the current scope, or private scope (i.e. the one used for {get,set}Value().

[cmb69]

Okay, than leave this ticket for Reflection improvements/fixes, and have #15553 regarding the stubs.