Callables like `operator.call` produce `arg-type` error with callables that take `*args: Unpack[Ts]` and >= 1 keyword argument
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Description
Bug Report
operator.call and similar ParamSpec callables (e.g. concurrent.futures.Executor.submit) produce an arg-type error when doing call(fn, fn2, some_kwarg=...) where fn has signature (fn2: Callable[[Unpack[Ts]], T], *args: Unpack[Ts], some_kwarg: ...) -> ...
this looks like a TypeVarTuple analog of #16405.
To Reproduce
import operator
from collections.abc import Callable
from typing import TypeVar
from typing import TypeVarTuple
from typing import Unpack
T = TypeVar("T")
Ts = TypeVarTuple("Ts")
def run(func: Callable[[Unpack[Ts]], T], *args: Unpack[Ts], some_kwarg: str = "asdf") -> T:
raise NotImplementedError
def foo() -> str:
raise NotImplementedError
run(foo) # OK
operator.call(run, foo) # OK
run(foo, some_kwarg="a") # OK
operator.call(run, foo, some_kwarg="a")
# error: Argument 1 to "call" has incompatible type "Callable[[Callable[[VarArg(*Ts)],
# T], VarArg(*Ts), DefaultNamedArg(str, 'some_kwarg')], T]"; expected
# "Callable[[Callable[[], str], str], str]" [arg-type]
Expected Behavior
no error.
Actual Behavior
see comments in the reproducer above.
Your Environment
- Mypy version used: 1.7.1 (compiled) & latest master (uncompiled)
- Mypy command-line flags: none
- Mypy configuration options from
mypy.ini(and other config files): none - Python version used: CPython 3.12.1
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by running the provided reproducer with mypy on current master and compare the behavior with issue #16405. Trace the handling of operator.call, ParamSpec, and TypeVarTuple callables; done means the keyword-argument call produces no arg-type error while the existing checks remain correct.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- devtools
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100