Alias that is generic over a ParamSpec is not hashable when using a list as parameters_expression

Bug report

Bug description:

This is slightly related to #124445, but a different issue, maybe it can be solved at the same time?

Consider the following code where [T] is a parameters_expression according to PEP 612. Similar to using Callable or using Generic[P] or Protocol[P] I would expect the following code to work and receive a hashable variable:

from typing import TypeVar
from collections.abc import Callable
type X[**P] = Callable[P, int]
T = TypeVar("T")
hash(X[[T]])
# ~~~~^^^^^^^^
# TypeError: unhashable type: 'list'

Cause:

The problem is that X[[T]].__args__ == ([T],) which cannot be hashed. I think the list should either be turned into a tuple. Either a nested one as its done for Generic and Protocol or joined like for Callable[P, str][[int]].__args__.

Discussion:

I've opened a parallel topic on discuss

CPython versions tested on:

3.13.0.rc2

Operating systems tested on:

Linux

EDIT: A thought, should this be changed for whole class in general?

從 issue 中的重現案例開始，將 ParamSpec 別名的行為與引用的 Generic、Protocol 和 Callable 案例進行比較。閱讀 PEP 612、issue #124445 以及連結的討論，以釐清列表參數應該變成巢狀 tuple，還是應該合併。完成的標準是 hash(X[[T]]) 能夠在沒有不可雜湊列表的情況下運作，同時保留預期的引數。