Properly address new stubtest errors from mypy v1.18.1

#14699 added several allowlist entries that need to be investigated more closely. These are marked with the comment # FIXME: new stubtest errors from mypy v1.18.1, and are repeated below.

Any help is appreciated!

The new allowlist entries:

pymysql.connections.Connection.__init__ ([PyMySQL] Fix stubs for pymysql.connections.Connection.__init__ #14724)
django_filters(\.\w+)*\.OrderingFilter.field_class ([django-filter] Improve stubtest comment. #14738)
docutils\.nodes\.\w+\.content_model ([docutils] Extend applicable types to _ContentModelCategory #14719)
docutils.parsers.docutils_xml.Unknown.content_model (ditto)
docutils.transforms.universal.SmartQuotes.nodes_to_skip (ditto)
openpyxl.descriptors.sequence.UniqueSequence.seq_types ([openpyxl] Fix stubs for openpyxl.descriptors.sequence.UniqueSequence.seq_types #14725)
serial.win32.ULONG_PTR ([serial] Update stubtest comment #14739)

Id love to have a look as a first (proper) contribution. Do you have some documentation about what tests/checks to run?

The contributing guide is a bit lacking there i feel.

@JanEricNitschke

@JanEricNitschke https://github.com/python/typeshed/blob/main/tests/README.md should help! Thanks!

For the openpyxl one we have:

Runtime

class Sequence(Descriptor):
    expected_type = type(None)
    seq_types = (list, tuple)
    idx_base = 0
    unique = False
    container = list

class UniqueSequence(Sequence):
    """
    Use a set to keep values unique
    """
    seq_types = (list, tuple, set)
    container = set

Stubs:

class Sequence(Descriptor[_ContainerT]):
    expected_type: type[Any]  # expected type of the sequence elements
    seq_types: tuple[type, ...]  # allowed settable sequence types, defaults to `list`, `tuple`
    idx_base: int
    unique: bool
    container: type  # internal container type, defaults to `list`

# `_T` is the type of the elements in the sequence.
class UniqueSequence(Sequence[set[_T]]):
    seq_types: tuple[type[list[_T]], type[tuple[_T, ...]], type[set[_T]]]
    container: type[set[_T]]

and error:

error: openpyxl.descriptors.sequence.UniqueSequence.seq_types variable differs from runtime type tuple[Overload(def [_T] () -> builtins.list[_T`1], def [_T] (typing.Iterable[_T`1]) -> builtins.list[_T`1]), def [_T_co] (typing.Iterable[_T_co`1] =) -> builtins.tuple[_T_co`1, ...], Overload(def [_T] () -> builtins.set[_T`1], def [_T] (typing.Iterable[_T`1]) -> builtins.set[_T`1])]
Stub: in file D:\Programming\Projects\typeshed\stubs\openpyxl\openpyxl\descriptors\sequence.pyi:41
tuple[type[builtins.list[_T`1]], type[builtins.tuple[_T`1, ...]], type[builtins.set[_T`1]]]
Runtime:
(<class 'list'>, <class 'tuple'>, <class 'set'>)

Fix would be

class UniqueSequence(Sequence[set[_T]]):
    seq_types: tuple[type, ...] # defaults to `list`, `tuple`, `set`
    container: type[set[_T]]

i guess. Feels worse, but i guess it matches whats already there for Sequence?

For serial.win32.ULONG_PTR

we have as the actual code:

# ULONG_PTR is a an ordinary number, not a pointer and contrary to the name it
# is either 32 or 64 bits, depending on the type of windows...
# so test if this a 32 bit windows...
if is_64bit():
    ULONG_PTR = c_int64
else:
    ULONG_PTR = c_ulong

As the stub:

ULONG_PTR: type[c_int64 | c_ulong]

And from the tesrt

Stub: in file D:\Programming\Projects\typeshed\stubs\pyserial\serial\win32.pyi:10
type[ctypes.c_int64] | type[ctypes.c_ulong]
Runtime: in file C:\Users\Jan-Eric\AppData\Roaming\uv\python\cpython-3.13.1-windows-x86_64-none\Lib\ctypes\__init__.py:213
<class 'ctypes.c_longlong'>

So i dont really know if/how to address this. Current situation seems correct to me.

Yes, the serial.win32 one sounds like something where we should continue to ignore the stubtest error. We should add a comment explaining this to the allowlist though.

The openpyxl one looks like a bug in stubtest to me; the stub is correct and precise. Probably worth opening an issue on mypy with a minimal example. I haven't tried but probably something like (list,) at runtime vs. tuple[type[list[T]] in the stub is enough.

@brianschubert

@brianschubert I've converted the list in your post to a checklist and added links to the relevant PRs (if any). Hope that's okay.

[django-filter] Improve stubtest comment.

Update stubtest comment

[serial] Update stubtest comment (#14739)

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Properly address new stubtest errors from mypy v1.18.1 #14718

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Properly address new stubtest errors from mypy v1.18.1 #14718

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JanEricNitschke commented on Sep 14, 2025

brianschubert commented on Sep 14, 2025

JanEricNitschke commented on Sep 15, 2025

JanEricNitschke commented on Sep 15, 2025

JelleZijlstra commented on Sep 15, 2025

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