Garbled output of reveal_type(Type[bounded TypeVar])

[AndrewUshakov]

For the code below:

from typing import Type, TypeVar, TYPE_CHECKING


class A:
    def __init__(self, arg: int) -> None:
        self._arg = arg


class B(A):
    def __init__(self, arg: int) -> None:
        super().__init__(arg)


_TA = TypeVar('_TA', bound=A)


def get_entity(entity_class: Type[_TA], arg: int) -> _TA:
    if TYPE_CHECKING:
        reveal_type(entity_class)       # <- Revealed type is 'Type[_TA`-1]'
        reveal_type(entity_class(1))    # <- Revealed type is '_TA`-1'
    return entity_class(arg)


if __name__ == '__main__':
    print(get_entity(B, 3))

mypy 0.641 produces garbled output at lines 19 and 20:

H:\My Documents\PyCharm\tst>mypy --strict tst84.py
tst84.py:19: error: Revealed type is 'Type[_TA`-1]'
tst84.py:20: error: Revealed type is '_TA`-1'

Expected output is:

tst84.py:19: error: Revealed type is 'Type[_TA]'
tst84.py:20: error: Revealed type is '_TA'

[ilevkivskyi]

These numbers can be actually important. There can be two type variables with the same name, but every id unique (to certain extent). Maybe we can format them more clearly, like '_TA(id=-1)' (by agreement mypy uses positive ids for class variables, and negative ones for methods).