UP035 false positive on typing_extensions.dataclass_transform on python 3.11

[DetachHead]

from typing_extensions import dataclass_transform
# UP035 Import from `typing` instead: `dataclass_transform`

typing_extensions.dataclass_transform has the frozen_default parameter which won't be in typing until python 3.12.

from typing_extensions:

if sys.version_info >= (3, 12):
    # dataclass_transform exists in 3.11 but lacks the frozen_default parameter
    dataclass_transform = typing.dataclass_transform
else:
    def dataclass_transform(
        *,
        eq_default: bool = True,
        order_default: bool = False,
        kw_only_default: bool = False,
        frozen_default: bool = False,
        field_specifiers: typing.Tuple[
            typing.Union[typing.Type[typing.Any], typing.Callable[..., typing.Any]],
            ...
        ] = (),
        **kwargs: typing.Any,
    ) -> typing.Callable[[T], T]:
        ...

[charliermarsh]

Ah interesting, okay, thank you.

[AlexWaygood]

Looks like ruff will also do this if you run ruff --fix --select="UP035":

- from typing_extensions import SupportsIndex
+ from typing import SupportsIndex

  isinstance(42, SupportsIndex)

But the isinstance() check there is 20x faster if you use the typing_extensions version, as typing_extensions backports a ton of optimisations that have been added to typing.Protocol in Python 3.12

[charliermarsh]

@AlexWaygood - Would you suggest not rewriting Protocol imports either for the same reason?

[AlexWaygood]

@AlexWaygood - Would you suggest not rewriting Protocol imports either for the same reason?

Yes -- and FWIW, pyupgrade recently made that change in asottile/pyupgrade@5059713, which is included in pyupgrade v3.7 (following my PR asottile/reorder-python-imports#341 to the reorder-python-imports project, which pyupgrade uses).

[charliermarsh]

Thanks!

[AlexWaygood]

following my PR asottile/reorder-python-imports#341 to the reorder-python-imports project, which pyupgrade uses

...which, looking at it again, it seems I forgot to include SupportsIndex in that PR, so I guess pyupgrade will continue to auto-replace from typing_extensions import SupportsIndex with from typing import SupportsIndex 🙃

Ruff can show its value-add here by not making that mistake :D

[charliermarsh]

Hahah oh no 😂