Crash with 'mypy.types.ProperType object expected; got mypy.types.TypeAliasType'

[kasium]

Crash Report

When running mypy on the below code it crashes. Please note that it seems to be related to mypyc, bc when using pure mypy it seems to work fine.

Traceback

foo.py:16: error: INTERNAL ERROR -- Please try using mypy master on GitHub:
https://mypy.readthedocs.io/en/stable/common_issues.html#using-a-development-mypy-build
Please report a bug at https://github.com/python/mypy/issues
version: 1.0.1
Traceback (most recent call last):
  File "mypy/checker.py", line 582, in accept
  File "mypy/nodes.py", line 1301, in accept
  File "mypy/checker.py", line 2648, in visit_assignment_stmt
  File "mypy/checker.py", line 2708, in check_assignment
  File "mypy/checker.py", line 3661, in check_lvalue
  File "mypy/checkexpr.py", line 2779, in analyze_ordinary_member_access
  File "mypy/checkmember.py", line 201, in analyze_member_access
  File "mypy/checkmember.py", line 229, in _analyze_member_access
  File "mypy/checkmember.py", line 431, in analyze_type_type_member_access
  File "mypy/checkmember.py", line 990, in analyze_class_attribute_access
TypeError: mypy.types.ProperType object expected; got mypy.types.TypeAliasType
foo.py:16: : note: use --pdb to drop into pdb

To Reproduce

from __future__ import annotations

from typing import Any, Callable, Generic, TypeVar, Union

T = TypeVar("T", bound="DummyClass[Any]")
GetterType = Union[str, int]
GetterCall = Callable[[], GetterType]

class DummyClass(Generic[T]):
    _getter: GetterCall | None = None

    @classmethod
    def set_getter(cls, getter: GetterType | GetterCall) -> None:
        cls._getter = (lambda: getter) if isinstance(getter, (str, int)) else getter

Your Environment

• Mypy version used: 1.0.1
• Mypy command-line flags: n/a
• Mypy configuration options from mypy.ini (and other config files): see below
• Python version used: 3.11.0
• Operating system and version: SUSE Linux Enterprise Server 15 SP3

[tool.mypy]
pretty = true
show_column_numbers = true
warn_unused_configs = true
strict_optional = false
disable_error_code = ["annotation-unchecked"]
explicit_package_bases = true

[kasium]

Still happens with mypy 1.1.1