PHPStan not follow DNF Type Declaration Constraints (PHP 8.2+)

[LastDragon-ru]

Bug report

The code is good for phpstan, but it is not valid for PHP :) (see https://wiki.php.net/rfc/dnf_types and https://php.watch/versions/8.2/dnf-types)

<?php declare(strict_types = 1);

interface X {}
interface Y {}

// Fatal error: Type Y&X is redundant with type X&Y in
// https://3v4l.org/gpAXA
function a(): (X&Y)|(Y&X) {
    return new class() implements X, Y {};
}

// Fatal error: Type X&Y is redundant as it is more restrictive than type X 
// https://3v4l.org/0jneS
function b(): (X&Y)|X {
    return new class() implements X {};
}

Code snippet that reproduces the problem

https://phpstan.org/r/75ab1049-8ffd-41bb-93ad-3082124ff2ec

Expected output

• Fatal error: Type Y&X is redundant with type X&Y in
• Fatal error: Type X&Y is redundant as it is more restrictive than type X

Did PHPStan help you today? Did it make you happy in any way?

Yep, helps a lot to move types intersections from phpdoc to code.