Support Explicit Backed Enum casting

Description

The following code:

https://3v4l.org/pfXH4#v8.5.3

<?php

echo '----- Backed integer enum -----'.PHP_EOL;
enum DayOfWeekInt : int
{
    case Monday = 1;
    case Tuesday = 2;
    case Wednesday = 3;
    case Thursday = 4;
    case Friday = 5;
    case Saturday = 6;
    case Sunday = 7;
}
$var = DayOfWeekInt::Monday;

try {
    echo '--- intval($var) --'.PHP_EOL;
    echo intval($var);    
} catch (\Throwable $ex) {
    echo $ex;
}
echo PHP_EOL;

try {
    echo '--- (int) $var ---'.PHP_EOL;
    echo (int) $var;
} catch (\Throwable $ex) {
    echo $ex;
}
echo PHP_EOL;

echo PHP_EOL;
echo '----- Backed string enum -----'.PHP_EOL;
enum DayofWeekString : string
{
    case Monday = 'monday';
    case Tuesday = 'tuesday';
    case Wednesday = 'wednesday';
    case Thursday = 'thursday';
    case Friday = 'friday';
    case Saturday = 'saturday';
    case Sunday = 'sunday';
}
$var = DayofWeekString::Monday;

try {
    echo '--- strval($var) ---'.PHP_EOL;
    echo strval($var);
} catch (\Throwable $ex) {
    echo $ex;
}
echo PHP_EOL;
    
try {
    echo '--- (string) $var ---'.PHP_EOL;
    echo (string) $var;
} catch (\Throwable $ex) {
    echo $ex;
}
echo PHP_EOL;

Resulted in this output:

----- Backed integer enum -----
--- intval($var) --

Warning: Object of class DayOfWeekInt could not be converted to int in /in/pfXH4 on line 18
1
--- (int) $var ---

Warning: Object of class DayOfWeekInt could not be converted to int in /in/pfXH4 on line 26
1

----- Backed string enum -----
--- strval($var) ---
Error: Object of class DayofWeekString could not be converted to string in /in/pfXH4:48
Stack trace:
#0 {main}
--- (string) $var ---
Error: Object of class DayofWeekString could not be converted to string in /in/pfXH4:56
Stack trace:
#0 {main}

But I expected this output instead:

no warnings, no errors and a correct explicit conversion.

----- Backed integer enum -----
--- intval($var) --
1
--- (int) $var ---
1

----- Backed string enum -----
--- strval($var) ---
monday
--- (string) $var ---
monday

PHP Version

PHP 8.5.3

Operating System

No response

Commencez par exécuter la reproduction fournie pour PHP 8.5.3 dans l’issue et comparez les casts explicites vers integer et string pour les backed enums. Suivez le comportement du casting des enums dans le code source de PHP, puis ajoutez une couverture pour les valeurs attendues et l’absence de warnings ou d’erreurs. C’est terminé lorsque les quatre conversions produisent les backed values indiquées dans le rapport.