Open
Description
Bug Report
from collections.abc import Callable
type A1[**P, R] = Callable[[Callable[P, R]], Callable[P, R]]
type A2[**P, R] = Callable[P, R]
def decorator[**P, R]() -> A1[P, R]:
def inner(func: Callable[P, R]) -> Callable[P, R]:
return func
return inner
def decorator_working[**P, R]() -> Callable[[A2[P, R]], A2[P, R]]:
def inner(func: Callable[P, R]) -> Callable[P, R]:
return func
return inner
@decorator() # error
def f1(x: str) -> int:
return 1
@decorator_working()
def f2(x: str) -> int:
return 1
reveal_type(f1)
reveal_type(f2)
Condensed version for debugging
# mypy: allow-empty-bodies
from collections.abc import Callable
type A1[**P, R] = Callable[[Callable[P, R]], Callable[P, R]]
type A2[**P, R] = Callable[P, R]
def decorator[**P, R]() -> A1[P, R]: ...
def decorator_working[**P, R]() -> Callable[[A2[P, R]], A2[P, R]]: ...
@decorator()
def f1(x: str) -> int: ...
@decorator_working()
def f2(x: str) -> int: ...
reveal_type(f1)
reveal_type(f2)
Expected Behavior
Mypy should be able to resolve the TypeVars for decorator
just like it does for decorator_working
.
Actual Behavior
error: Argument 1 has incompatible type "Callable[[str], int]"; expected "Callable[[VarArg(Never), KwArg(Never)], Never]" [arg-type]
note: Revealed type is "def (*Never, **Never) -> Never"
note: Revealed type is "def (x: builtins.str) -> builtins.int"
Your Environment
- Mypy version used:
mypy 1.15.0+dev.68cffa7afe03d2b663aced9a70254e58704857db (compiled: no)
- Python version:
3.13