Template type becomes array when implementing method with variadic parameter

[bronek89]

Bug report

Hi, I'm not sure how to describe this error, but:
When implementing method with variadic templated type - that type becomes array<int, T>. For example: TKey becomes array<int, TKey>.

/**
 * @template TKey
 * @template TValue
 */
interface A
{
    /**
     * @phpstan-param array<int, TKey> $keys
     * @phpstan-return A<TKey, TValue>
     */
    public function methodName(...$keys): A;
}

/**
 * @template TKey
 * @template TValue
 * @implements A<TKey, TValue>
 */
class AI implements A
{
    /**
     * @phpstan-param array<int, TKey> $keys
     * @phpstan-return A<TKey, TValue>
     */
    public function methodName(...$keys): A
    {
         // return type of parent method is detected as array<int, TKey> 
    }
}

(full examples below)

Am I doing something wrong? :) Or this is a bug?

Code snippet that reproduces the problem

https://phpstan.org/r/1e9e5aab-3494-40bb-ab40-fe58993224af
https://phpstan.org/r/d78732e7-1bbb-41d4-bba6-e7dd6e6fd36c

The same error occurs with variadic syntax TKey ...$keys:
https://phpstan.org/r/25ea56c5-c03b-426d-b274-a0fda1df4b60

"Concrete variadic" types are ok:
https://phpstan.org/r/2ebfc221-b297-4c58-9843-e89f72666b98

Passing int as TKey by @implements does not produce error:
https://phpstan.org/r/6bb97423-efe2-4ed7-b78e-dd334d67e7d2

Expected output

No errors like in https://psalm.dev/r/e8a2f1414d or https://psalm.dev/r/d8ad951558

[ondrejmirtes]

Hi, yes, variadic generics are not yet supported. Filing under https://github.com/phpstan/phpstan/milestone/9.

[ondrejmirtes]

Fixed: phpstan/phpstan-src@a599eaa

[github-actions]

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