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[dateutil] Fix Generator parameters #15574

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[dateutil] Fix Generator parameters #15574

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4 changes: 3 additions & 1 deletion stubs/python-dateutil/dateutil/rrule.pyi
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Original file line number Diff line number Diff line change
Expand Up @@ -64,7 +64,9 @@ class rrulebase:
def count(self) -> int | None: ...
def before(self, dt: datetime.datetime, inc: bool = False) -> datetime.datetime | None: ...
def after(self, dt: datetime.datetime, inc: bool = False) -> datetime.datetime | None: ...
def xafter(self, dt: datetime.datetime, count: int | None = None, inc: bool = False) -> Generator[datetime.datetime]: ...
def xafter(
self, dt: datetime.datetime, count: int | None = None, inc: bool = False
) -> Generator[datetime.datetime, None, None]: ...
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@brianschubert brianschubert Mar 29, 2026

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Hmm, this shouldn't be needed - the defaults for send and return type vars is already None, so omitting them is the preferred form:

typeshed/stdlib/typing.pyi

Lines 543 to 544 in 24827c4

_SendT_contra = TypeVar("_SendT_contra", contravariant=True, default=None)
_ReturnT_co = TypeVar("_ReturnT_co", covariant=True, default=None)

Did you run into a specific problem that this helps with?

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@eliroca eliroca Mar 29, 2026

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Yes:

[    3s] + python3.11 -m mypy dateutil-stubs
[    5s] dateutil-stubs/rrule.pyi:67: error: "Generator" expects 3 type arguments, but 1 given  [type-arg]
[    5s] dateutil-stubs/tz/win.pyi:2: error: Module "ctypes" has no attribute "_NameTypes"  [attr-defined]

(for the second issue I also opened a PR)

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@brianschubert brianschubert Mar 29, 2026

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What version of mypy are you using? I'm guessing it's an older version that ships with an outdated copy of the stdlib stubs? Does it work if you use a later version (I think circa 1.15+ based on when those types were last touched in typeshed)?

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@eliroca eliroca Mar 29, 2026

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python311-mypy-1.8.0

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@eliroca eliroca Mar 29, 2026

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Well, all the other places in this project specify all 3 parameters.

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@brianschubert brianschubert Mar 29, 2026

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Yeah, that would be the problem. mypy 1.8.0 uses older version of the stdlib stubs that wouldn't be compatible with the current python-dateutil stubs (which I'm assuming you forked to create dateutil-stubs).

If you want to type check the current stubs, you'll need to either use a more recent version of mypy or use --custom-typeshed-dir with a checkout of a more recent copy of the typeshed stdlib stubs.

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@brianschubert brianschubert Mar 29, 2026 •
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Well, all the other places in this project specify all 3 parameters.

I'm sure there's some stragglers left over from before type var defaults were introduced :). We might update these in bulk eventually, but they don't really cause any problems at the moment since both forms are treated equivalently by type checkers. At least for new stubs the single argument form is preferred.

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@eliroca eliroca Mar 29, 2026

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I'm fine with keeping this as a patch on my side. Thanks for the pointers about mypy!

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@brianschubert brianschubert Mar 29, 2026

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I'll go ahead and close this out then. Thanks for the PR in any case!

If you do find any other issues with the dateutil stubs, patches here are always welcome!

def between(
self, after: datetime.datetime, before: datetime.datetime, inc: bool = False, count: int = 1
) -> list[datetime.datetime]: ...
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