Crash when providing type annotation for class __slots__ without assigning a value

[jphells]

Bug description

Pylint crashes fatally when linting a file with the following example code:

example.py

# pylint: disable=missing-docstring

class Foo:
    __slots__: str

pylint crashed with a AstroidError and with the following stacktrace:

Traceback (most recent call last):
  File "c:\Users\User\example\venv\lib\site-packages\astroid\nodes\scoped_nodes\scoped_nodes.py", line 2663, in igetattr
    attributes = self.getattr(name, context, class_context=class_context)
  File "c:\Users\User\example\venv\lib\site-packages\astroid\nodes\scoped_nodes\scoped_nodes.py", line 2603, in getattr
    raise AttributeInferenceError(
astroid.exceptions.AttributeInferenceError: '__slots__' not found on <ClassDef.Foo l.2 at 0x13232ba3220>.

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "c:\Users\User\example\venv\lib\site-packages\pylint\lint\pylinter.py", line 727, in _check_file
    check_astroid_module(ast_node)
  File "c:\Users\User\example\venv\lib\site-packages\pylint\lint\pylinter.py", line 926, in check_astroid_module
    retval = self._check_astroid_module(
  File "c:\Users\User\example\venv\lib\site-packages\pylint\lint\pylinter.py", line 976, in _check_astroid_module
    walker.walk(node)
  File "c:\Users\User\example\venv\lib\site-packages\pylint\utils\ast_walker.py", line 93, in walk
    self.walk(child)
  File "c:\Users\User\example\venv\lib\site-packages\pylint\utils\ast_walker.py", line 90, in walk
    callback(astroid)
  File "c:\Users\User\example\venv\lib\site-packages\pylint\checkers\classes\class_checker.py", line 838, in visit_classdef
    self._check_slots(node)
  File "c:\Users\User\example\venv\lib\site-packages\pylint\checkers\classes\class_checker.py", line 1369, in _check_slots
    for slots in node.igetattr("__slots__"):
  File "c:\Users\User\example\venv\lib\site-packages\astroid\nodes\scoped_nodes\scoped_nodes.py", line 2714, in igetattr
    raise InferenceError(
astroid.exceptions.InferenceError: '__slots__' not found on <ClassDef.Foo l.2 at 0x13232ba3220>.

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "c:\Users\User\example\venv\lib\site-packages\pylint\lint\pylinter.py", line 684, in _check_files
    self._check_file(get_ast, check_astroid_module, file)
  File "c:\Users\User\example\venv\lib\site-packages\pylint\lint\pylinter.py", line 729, in _check_file
    raise astroid.AstroidError from e
astroid.exceptions.AstroidError

A hotfix to my code is simply to assign a value to __slots__ in the class definition.

Expecting pylint not to crash and an empty output or warning/error telling that I am using a defined but unassigned __slots__.

Configuration

No response

Command used

pylint example.py

Pylint output

In the editor:

c:\Users\User\example\example.py: Fatal error while checking 'c:\Users\User\example\example.py'. Please open an issue in our bug tracker so we address this. There is a pre-filled template that you can use in 'C:\Users\User\AppData\Local\pylint\pylint\Cache\pylint-crash-2022-08-09-13.txt'.

pylint-crash-2022-08-09-13.txt (and when running pylint example.py):

Traceback (most recent call last):
  File "c:\Users\User\example\venv\lib\site-packages\astroid\nodes\scoped_nodes\scoped_nodes.py", line 2663, in igetattr
    attributes = self.getattr(name, context, class_context=class_context)
  File "c:\Users\User\example\venv\lib\site-packages\astroid\nodes\scoped_nodes\scoped_nodes.py", line 2603, in getattr
    raise AttributeInferenceError(
astroid.exceptions.AttributeInferenceError: '__slots__' not found on <ClassDef.Foo l.2 at 0x13232ba3220>.

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "c:\Users\User\example\venv\lib\site-packages\pylint\lint\pylinter.py", line 727, in _check_file
    check_astroid_module(ast_node)
  File "c:\Users\User\example\venv\lib\site-packages\pylint\lint\pylinter.py", line 926, in check_astroid_module
    retval = self._check_astroid_module(
  File "c:\Users\User\example\venv\lib\site-packages\pylint\lint\pylinter.py", line 976, in _check_astroid_module
    walker.walk(node)
  File "c:\Users\User\example\venv\lib\site-packages\pylint\utils\ast_walker.py", line 93, in walk
    self.walk(child)
  File "c:\Users\User\example\venv\lib\site-packages\pylint\utils\ast_walker.py", line 90, in walk
    callback(astroid)
  File "c:\Users\User\example\venv\lib\site-packages\pylint\checkers\classes\class_checker.py", line 838, in visit_classdef
    self._check_slots(node)
  File "c:\Users\User\example\venv\lib\site-packages\pylint\checkers\classes\class_checker.py", line 1369, in _check_slots
    for slots in node.igetattr("__slots__"):
  File "c:\Users\User\example\venv\lib\site-packages\astroid\nodes\scoped_nodes\scoped_nodes.py", line 2714, in igetattr
    raise InferenceError(
astroid.exceptions.InferenceError: '__slots__' not found on <ClassDef.Foo l.2 at 0x13232ba3220>.

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "c:\Users\User\example\venv\lib\site-packages\pylint\lint\pylinter.py", line 684, in _check_files
    self._check_file(get_ast, check_astroid_module, file)
  File "c:\Users\User\example\venv\lib\site-packages\pylint\lint\pylinter.py", line 729, in _check_file
    raise astroid.AstroidError from e
astroid.exceptions.AstroidError

Expected behavior

Expected: pylint does not crash and either empty output, or some kind of warning or error that I'm defining but not assigning to a __slots__ attribute.

Pylint version

pylint 2.14.5
astroid 2.11.7
Python 3.10.4 (tags/v3.10.4:9d38120, Mar 23 2022, 23:13:41) [MSC v.1929 64 bit (AMD64)]

OS / Environment

No response

Additional dependencies

astroid==2.11.7
colorama==0.4.5
dill==0.3.5.1
isort==5.10.1
lazy-object-proxy==1.7.1
mccabe==0.7.0
platformdirs==2.5.2
pylint==2.14.5
tomli==2.0.1
tomlkit==0.11.2
wrapt==1.14.1