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New semantic analyzer: regression with circular import and TypeVar #7037
Description
I found a regression when using the new semantic analyzer in mypy 0.710.
To reproduce, you need the following two modules:
# factory.py
from typing import Generic, Type
from box import BoxT
class Factory(Generic[BoxT]):
value = 123
def create(self, boxClass: Type[BoxT]) -> BoxT:
return boxClass.create(self)# box.py
from typing import TYPE_CHECKING, Type, TypeVar
if TYPE_CHECKING:
from factory import Factory
BoxT = TypeVar('BoxT', bound='Box')
class Box:
@classmethod
def create(cls: Type[BoxT], f: Factory) -> BoxT:
return cls(f.value)
def __init__(self, value: int):
print(value)When mypy is run on these modules with the default arguments, no issues are reported. But when run withthe new semantic analyzer, the following happens:
$ mypy --new-semantic-analyzer box.py factory.py
factory.py:11: error: "Type[BoxT]" has no attribute "create"
The problem does not occur if there is no circular import. It also doesn't occur if the BoxT TypeVar is defined in the factory module instead of imported from the box module.
Activity
JukkaL commentedon Jun 21, 2019
Thanks for reporting this! This seems like an important issue to fix, in particular since the new semantic analyzer is supposed to work better with import cycles :-)
New semantic analyzer: Prohibit duplicate type variable definitions a…