checkBenevolentUnionTypes + @template TKey of array-key = false positive

[LastDragon-ru]

Bug report

I'm trying to enable checkBenevolentUnionTypes (as recomended in #9750), but seems I found something stange :)

<?php declare(strict_types = 1);

/**
 * @template TKey of array-key
 * @template TItem
 */
class PHPStanBug {
    /**
     * @param iterable<TKey, TItem> $items
     */
    public function __construct(
        private iterable $items,
    ) {
        // empty
    }

    /**
     * @return iterable<TKey, TItem>
     */
    protected function getItems(): iterable {
        return $this->items;
    }
}

PHPStan will report that:

 21     Method PHPStanBug::getItems() should return iterable<TKey of (int|string), TItem> but returns iterable<TKey of (int|string), TItem>.
         💡 Type int is not always the same as TKey. It breaks the contract for some argument types, typically subtypes.
         💡 Type string is not always the same as TKey. It breaks the contract for some argument types, typically subtypes.

With @template TKey of string|int there are no errors.

Code snippet that reproduces the problem

https://phpstan.org/r/3a30aea2-ea44-4546-8774-3a9589abe496

Expected output

Probably no error?

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

No response

[ondrejmirtes]

This is a really easy fix. RuleLevelHelper needs to transform TemplateBenevolentUnionType into TemplateUnionType in these two places:

• https://github.com/phpstan/phpstan-src/blob/26625c3df5cdbe390f6753bbcb86907ae211843d/src/Rules/RuleLevelHelper.php#L148-L159
• https://github.com/phpstan/phpstan-src/blob/26625c3df5cdbe390f6753bbcb86907ae211843d/src/Rules/RuleLevelHelper.php#L119-L124

Right now TemplateBenevolentUnionType is transformed into UnionType, resulting in these errors. /cc @VincentLanglet

[ondrejmirtes]

Fixed: phpstan/phpstan-src#2587

[github-actions]

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