pytype.tools.annotate_ast.annotate_source crashes with RecursionError: maximum recursion depth exceeded in __instancecheck__

[YingboFu]

Hi,

Thanks a lot for the amazing PyType you developed.

When I run the annotate_source on the following file (simplified)

from abc import ABC
from typing import Any, Callable, Generic, Iterator, List, Literal, Optional, Set, TypeVar, Union, cast

T = TypeVar("T")
V = TypeVar("V")

Factory = Optional[Callable[[object], T]]  # note the argument is anything, due e.g. memory loader can inject anything


class Convert(ABC, Generic[T]):
    """A class that converts a raw type to a given tox (python) type."""

    def to(self, raw: T, of_type: type[V], factory: Factory[V]) -> V:  # noqa: PLR0911
        """
        Convert given raw type to python type.

        :param raw: the raw type
        :param of_type: python type
        :param factory: factory method to build the object
        :return: the converted type
        """
        from_module = getattr(of_type, "__module__", None)
        if from_module in {"typing", "typing_extensions"}:
            return self._to_typing(raw, of_type, factory)

    def _to_typing(self, raw: T, of_type: type[V], factory: Factory[V]) -> V:  # noqa: C901
        origin = getattr(of_type, "__origin__", of_type.__class__)
        if origin in {list, List}:
            entry_type = of_type.__args__[0]  # type: ignore[attr-defined]
            result = [self.to(i, entry_type, factory) for i in self.to_list(raw, entry_type)]

PyType crashes with the traceback info:

File "/Users/fuyingbo/Desktop/into_the_wild_dev/venv/lib/python3.9/site-packages/pytype/output.py", line 312, in value_to_pytd_type
    elif isinstance(v, (typing_overlay.TypeVar, typing_overlay.ParamSpec)):
pytype.tools.annotate_ast.annotate_ast.PytypeError: Pytype error: RecursionError: maximum recursion depth exceeded in __instancecheck__

I guess one potential reason behind this crash is that Convert.to might call Convert._to_typing while Convert._to_typing might also call Convert.to back, which PyType consider as an infinite recursion and crashes.

The full file is at https://github.com/tox-dev/tox/blob/main/src/tox/config/loader/convert.py

I am unsure if it is a bug, but an error message might be better than crashes and thus report it.

Thanks a lot.