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Description
Bug Report
This bug only occurs on the second run when using incremental mode. When using nested ParamSpecs, the outer ParamSpec (M below) is erroneously equal to the inner ParamSpec (P below).
Notably, pyright handles this correctly.
To Reproduce
from __future__ import annotations
from typing import Callable, Concatenate, Generic, ParamSpec, TypeVar
class ABase:
...
class ADerived(ABase):
def __init__(self, a_param_1: float) -> None:
super().__init__()
self.a_1 = a_param_1
M = ParamSpec("M")
P = ParamSpec("P")
R = TypeVar("R", bound=ABase)
class B(Generic[P, R]):
def __init__(
self,
a_class: Callable[P, R],
b_param_1: str,
*args: P.args,
**kwargs: P.kwargs,
) -> None:
self.a = a_class(*args, **kwargs)
self.b_1 = b_param_1
@classmethod
def build(
cls: Callable[Concatenate[Callable[P, R], M], B[P, R]],
a_class: Callable[P, R]
) -> Callable[M, B[P, R]]:
def new_constructor(
*args: M.args,
**kwargs: M.kwargs,
) -> B[P, R]:
return cls(a_class, *args, **kwargs)
return new_constructor
BADerived = B.build(ADerived)
reveal_type(BADerived) # note): Revealed type is "def (a_param_1: builtins.float) -> B[[a_param_1: builtins.float], ADerived]"
b_a_derived_1 = B(ADerived, "my_str", 1.0) # OK
b_a_derived_2 = BADerived( # [call-arg] error: Too many arguments
"my_str", 1.0 # [arg-type] error: Argument 1 has incompatible type "str"; expected "float"
)Expected Behavior
I expect the signature of BADerived to include b_param_1, like this:
mypy_nested_paramspec.py:49: note: Revealed type is "def (b_param_1: builtins.str, a_param_1: builtins.float) -> mypy_nested_paramspec.B[[a_param_1: builtins.float], ADerived]"
I also expect that calls to BADerived with the correct parameter count and types do not raise any errors.
Actual Behavior
mypy_nested_paramspec.py:49: note: Revealed type is "def (a_param_1: builtins.float) -> mypy_nested_paramspec.B[[a_param_1: builtins.float], mypy_nested_paramspec.ADerived]"
mypy_nested_paramspec.py:52: error: Too many arguments [call-arg]
mypy_nested_paramspec.py:53: error: Argument 1 has incompatible type "str"; expected "float" [arg-type]
Your Environment
- Mypy version used: mypy 0.991 (compiled: yes)
- Python version used: 3.10.6