There is a difference between typing.Callable and collections.abc.Callable.

>>> import typing, collections.abc
>>> T = typing.TypeVar('T')
>>> C1 = typing.Callable[[T], T]
>>> C2 = collections.abc.Callable[[T], T]
>>> C1
typing.Callable[[~T], ~T]
>>> C2
collections.abc.Callable[[~T], ~T]
>>> C1[int]
typing.Callable[[int], int]
>>> C2[int]
collections.abc.Callable[[~T], int]

Here I think the behavior of typing.Callable is correct.

Yeah, the fix will require a variant of types.GenericAlias that substitute's type variables in lists.

Of course. There is more than one way to fix it:

* Make GenericAlias substituting type variables in list. It is easier and it will fix this particular case, but there will be subtle differences in __args__.
* Add a GenericAlias subclass with overridden constructor, __repr__, __getitem__, __reduce__ (like the _GenericAlias subclass added in issue40397).

I think we should first resolve issue40397 and later decide what way be better. It is not necessary to reproduce all details of _GenericAlias if the practical behavior is the same.

Hm, I am indeed torn. ISTM a subclass just for Callable is slightly better.

From https://bugs.python.org/issue42195 it looks like we need to create a subclass just for Callable. See https://bugs.python.org/issue42102 and PR 22848.

Now that issue42195 has been resolved by subclassing types.GenericAlias, can this be closed?

On 3.9 and 3.10:

>>> import typing, collections.abc
>>> T = typing.TypeVar('T')
>>> C2 = collections.abc.Callable[[T], T]
>>> C2[int]
collections.abc.Callable[[int], int]

It seems to be fixed :).

Indeed. Thanks!