mypy suggests deprecated code

[clo-vis]

To Reproduce

def function(arg: Callable[[], Iterable[int]]) -> Set[int]: return set()

Expected Behavior
error: Name "Callable" is not defined [name-defined]
error: Name "Iterable" is not defined [name-defined]
error: Name "Set" is not defined [name-defined]
and perhaps something like
(for Callable) note: Did you forget to import it from from "collections.abc"? (Suggestion: "from collections.abc import Callable")
(for Iterable) note: Did you forget to import it from from "collections.abc"? (Suggestion: "from collections.abc import Iterable")
(for Set) note: Use set[int] if the set is mutable or import Set from collections.abc if the set is immutable: "from collections.abc import Set"

Actual Behavior

error: Name "Callable" is not defined  [name-defined]
note: Did you forget to import it from "typing"? (Suggestion: "from typing import Callable")
error: Name "Iterable" is not defined  [name-defined]
note: Did you forget to import it from "typing"? (Suggestion: "from typing import Iterable")
error: Name "Set" is not defined  [name-defined]
note: Did you forget to import it from "typing"? (Suggestion: "from typing import Set")

typing.Callable, typing.Iterable, and typing.Set were all deprecated (python 3.9+)

Your Environment

• Mypy version used: 1.8.0 (compiled: yes)
• Mypy command-line flags: none
• Mypy configuration options from mypy.ini (and other config files): none
• Python version used: 3.11.6

[CarliJoy]

note: "Use set[int] if the set is mutable or import Set from collections.abc if the set is immutable: from collections.abc import Set

This is quite new to me. Can provide a documentation link that describes this?

[clo-vis]

https://docs.python.org/3.9/library/typing.html#corresponding-to-built-in-types
https://docs.python.org/3.10/library/typing.html#corresponding-to-built-in-types
https://docs.python.org/3.11/library/typing.html#corresponding-to-built-in-types
https://docs.python.org/3.12/library/typing.html#corresponding-to-built-in-types

[CarliJoy]

But where is written, that set[T] is mutable?
I see that collections.abc.Set is immutable but set is mutable as collections.abc.MutableSet is as well.

That is quite a bit confusing...

I get that set is mutable because it is not a frozenset but naming it exactly different with collections.abc, why?
Given that it is so confusing, the note shown to the users should reflect that.

Thanks for making me aware of this :-)

[JelleZijlstra]

Yes, this is confusing. We have a special case in flake8-pyi to deal with it: search for Y025 in https://github.com/PyCQA/flake8-pyi/blob/main/ERRORCODES.md.

It's a little off topic for this issue though: I assume mypy suggests the same deprecated code if you write List[int] without importing List.

I think it's still appropriate for mypy to suggest from typing import ... as long as we still support a version where list[int] doesn't work (i.e., Python 3.8). We could suggest list[int] instead when we know it's safe (i.e., when the project supports only 3.9+).

[hauntsaninja]

(In case its any consolation, note that while these symbols are deprecated, CPython will not remove them for a long long time, if ever)

[clo-vis]

Description updated (to show the problem also with Iterable and Callable)