Crash on numtype numpy stubs package related to property

[hauntsaninja]

rm -rf tmp
mkdir tmp
cd tmp
git clone https://github.com/numpy/numtype.git
mypy numtype/src --show-traceback 

numtype commit 864cda2

Seems similar to #18648 cc @ilevkivskyi

...
  File "/Users/shantanu/dev/mypy/mypy/nodes.py", line 580, in accept
    return visitor.visit_overloaded_func_def(self)
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^
  File "/Users/shantanu/dev/mypy/mypy/checker.py", line 641, in visit_overloaded_func_def
    self._visit_overloaded_func_def(defn)
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^
  File "/Users/shantanu/dev/mypy/mypy/checker.py", line 697, in _visit_overloaded_func_def
    found_method_base_classes = self.check_method_override(defn)
  File "/Users/shantanu/dev/mypy/mypy/checker.py", line 2022, in check_method_override
    result = self.check_method_or_accessor_override_for_base(
        defn, base, check_override_compatibility
    )
  File "/Users/shantanu/dev/mypy/mypy/checker.py", line 2060, in check_method_or_accessor_override_for_base
    if self.check_method_override_for_base_with_name(defn, name, base):
       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^
  File "/Users/shantanu/dev/mypy/mypy/checker.py", line 2194, in check_method_override_for_base_with_name
    self.check_setter_type_override(defn, base_attr, base)
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/shantanu/dev/mypy/mypy/checker.py", line 2084, in check_setter_type_override
    original_type, is_original_setter = get_raw_setter_type(base_node)
                                        ~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^
  File "/Users/shantanu/dev/mypy/mypy/checker.py", line 8919, in get_raw_setter_type
    assert var.type is not None
           ^^^^^^^^^^^^^^^^^^^^
AssertionError: 
numtype/src/numpy-stubs/ma/core.pyi:308: : note: use --pdb to drop into pdb

[hauntsaninja]

Partially minimised repro:

rm -rf repro
mkdir repro
cd repro

python -m venv env
env/bin/python -m pip install numpy

mkdir numpy-stubs

echo '
from typing import Any, Generic
from typing_extensions import TypeVar

from . import matlib as matlib  # load bearing since it imports numpy

_DTypeT2_co = TypeVar("_DTypeT2_co", covariant=True)
_ShapeT2 = TypeVar("_ShapeT2", bound=tuple[int, ...])
_ShapeT2_co = TypeVar("_ShapeT2_co", bound=tuple[int, ...], covariant=True)
_ScalarT2_co = TypeVar("_ScalarT2_co", covariant=True)

class ndarray(Generic[_ShapeT2_co, _DTypeT2_co]):
    @property
    def shape(self) -> _ShapeT2_co: ...
    @shape.setter
    def shape(self: ndarray[_ShapeT2, Any], shape: _ShapeT2, /) -> None: ...
' > numpy-stubs/__init__.pyi

echo '
from typing_extensions import TypeVar

import numpy as np

_ShapeT = TypeVar("_ShapeT", bound=tuple[int, ...])
_ShapeT_co = TypeVar("_ShapeT_co", bound=tuple[int, ...], default=tuple[int, ...], covariant=True)
_DTypeT_co = TypeVar("_DTypeT_co", covariant=True)

class MaskedArray(np.ndarray[_ShapeT_co, _DTypeT_co]):
    @property
    def shape(self) -> _ShapeT_co: ...
    @shape.setter
    def shape(self: MaskedArray[_ShapeT], shape: _ShapeT, /) -> None: ...
' > numpy-stubs/core.pyi

mypy . --python-executable env/bin/python --show-traceback

[ilevkivskyi]

Oh well, I was wandering why some code paths (inconsistently) expose settable property type as Overloaded(...) with a single item. Ultimately, this is just another case of the checkmember.py mega-issue. I am still not sure what to do about this particular case: another band-aid, or try cleaning this up for real. Taking into account the 1.16 is coming soon it will likely be the former, but I want to think a bit more, before I do this.

[ilevkivskyi]

@hauntsaninja could you please check that #18774 fixes the original crash? (I have a very minimalist example in the tests.)