Using `typing.Any` to register a structure hook for a generic type is not working.

• cattrs version: 1.0.0
• Python version: 3.8.2
• Operating System: archlinux

Description

import typing

import attr
import cattr
import typing_inspect


T = typing.TypeVar("T")


class GenericList(typing.List[T]):
    ...


def _structure_generic_list(d, t):
    (conv,) = typing_inspect.get_args(t)
    return list(map(conv, d.split(",")))

# this is ignored
cattr.register_structure_hook(GenericList[typing.Any], _structure_generic_list)

# this works
cattr.register_structure_hook(GenericList[str], _structure_generic_list)
cattr.register_structure_hook(GenericList[int], _structure_generic_list)


@attr.s(auto_attribs=True)
class Params:
    some_words: GenericList[str]
    some_ids: GenericList[int]


def test_structure_generic_list():
    src = {"some_words": "foo,bar", "some_ids": "123,456"}
    params = cattr.structure(src, Params)
    assert params == Params(some_words=["foo", "bar"], some_ids=[123, 456])

Using typing.Any to register a structure hook for a generic type is not working.

Start by running the provided test_structure_generic_list reproduction with cattrs 1.0.0, focusing on register_structure_hook and cattr.structure. Trace why the GenericList[typing.Any] registration is ignored, then confirm that the Any hook handles the generic type while the existing string and integer cases still pass.