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Incorrect handling of default arguments for type Type with Typevars #6525
Description
Consider a function which takes type and returns instance of that type. This is handled correctly by mypy:
from typing import Type, TypeVar
MyType = TypeVar('MyType', str, int)
def func(t: Type[MyType]) -> MyType:
return t()However, if I set default argument for t, mypy fails:
from typing import Type, TypeVar
MyType = TypeVar('MyType', str, int)
# error: Incompatible default for argument "t" (default has type "Type[str]", argument has type "Type[int]")
def func(t: Type[MyType] = str) -> MyType:
return t()from typing import Type, TypeVar
MyType = TypeVar('MyType', str, int)
# error: Incompatible default for argument "t" (default has type "Type[int]", argument has type "Type[str]")
def func(t: Type[MyType] = int) -> MyType:
return t()from typing import Type, TypeVar
MyType = TypeVar('MyType')
# error: Incompatible default for argument "t" (default has type "Type[int]", argument has type "Type[MyType]")
def func(t: Type[MyType] = int) -> MyType:
return t()IMO that's a bug. Without TypeVar it works correctly though:
from typing import Type, TypeVar, Union
def func(t: Type[Union[str, int]] = str) -> Union[str, int]:
return t()Reacted by Jaanus Varus and mo
Activity
emmatyping commentedon Mar 8, 2019
This is a duplicate of #4236. Please make sure to search the issue tracker when reporting bugs (using a couple of words such as "default" and "generic"/"typevar" then scanning through the listed issues works well).