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Version 0.780 does not recognize python internal types as typing.Type anymore #8992
Description
Since upgrading from version 0.770 to 0.780 we saw issues, where types used during runtime were recognized as object and not as typing.Type anymore.
-
Are you reporting a bug, or opening a feature request?
Bug -
Please insert below the code you are checking with mypy
# test.py
from typing import Type, Union
def method(type: Type) -> None:
pass
method(int)
method(Union[int, str])- What is the actual behavior/output?
> mypy test.py # mypy==0.780
test.py:8: error: Argument 1 to "method" has incompatible type "object"; expected "Type[Any]"
Found 1 error in 1 file (checked 1 source file)
- What is the behavior/output you expect?
> mypy test.py # mypy==0.770
Success: no issues found in 1 source file
- What are the versions of mypy and Python you are using?
Do you see the same issue after installing mypy from Git master?- Python version 3.8.2
- failing mypy versions: 0.780 + latest master
- passing mypy version: 0.770
Activity
ilevkivskyi commentedon Jun 12, 2020
This is intended, at runtime
Union[int, str]is not a subclass oftype(on most newer version of Python anymore).aachurin commentedon Jun 16, 2020
But the documentation says the following:
The only legal parameters for Type are classes, Any, type variables, and unions of any of these types. For example:
def new_non_team_user(user_class: Type[Union[BaseUser, ProUser]]): ...Type[Any] is equivalent to Type which in turn is equivalent to type, which is the root of Python’s metaclass hierarchy.
hmvp commentedon Jun 17, 2020
The same happens with
Optional[str]etc.. IfTypeis not the correct type to use, what should be used instead? How should I annotatemappingin this example?:JukkaL commentedon Jun 19, 2020
@hmvp You need to use
objectorAny.hmvp commentedon Jun 22, 2020
@JukkaL That's not really satisfying isn't it? I would like to use something that expresses that the values in the mapping are type-like, not instances. Using
Anyorobjectis basically saying "I don't care about the type". I want mypy to warn that any of the following entries are not allowed: