False positive when using coroutines and generics #15886
Description
Bug report
Mypy is not consistent between sync and async variants of the same code.
How to reproduce
Consider the following code:
from typing import Generic, TypeVar
T = TypeVar("T")
class Cls(Generic[T]):
pass
def create_cls(arg: T) -> Cls[tuple[T]]:
return Cls()
def inner(var: Cls[tuple[T]]) -> T | None:
return None
def outer(x: int) -> int | None:
c = create_cls(x)
return inner(c)Running mypy test.py yields no errors, as expected.
However, if we make the functions async:
from typing import Generic, TypeVar
T = TypeVar("T")
class Cls(Generic[T]):
pass
def create_cls(arg: T) -> Cls[tuple[T]]:
return Cls()
async def inner(var: Cls[tuple[T]]) -> T | None:
return None
async def outer(x: int) -> int | None:
c = create_cls(x)
return await inner(c)Then running mypy test.py gives:
test.py:21: error: Argument 1 to "inner" has incompatible type "Cls[tuple[int]]"; expected "Cls[tuple[int | None]]" [arg-type]
Found 1 error in 1 file (checked 1 source file)Expected Behavior
Mypy should give no errors in the async case, there's no difference in any of the function signatures.
Your Environment
- Mypy version used:
mypy 1.5.0 (compiled: yes) - Mypy command-line flags: None
- Mypy configuration options from
mypy.ini(and other config files): None - Python version used: 3.11.0rc1