(🐞) Bad error message when using `Concatenate` incorrectly

[KotlinIsland]

Despite the fact that a good message is output afterwards, the initial error seems like nonsense: "first arg to Callable must be a parameter specification". Huh? it is a ParamSpec?! I presume that this is because the type becomes Any (from error) due to the args being invalid. At runtime the type here would be Never (because it would raise).

from typing import Concatenate, Callable, ParamSpec, TypeVar, Any

P = ParamSpec("P")

def f(fn: Callable[Concatenate[P, int], None]): ...

main.py:5: error: The first argument to Callable must be a list of types, parameter specification, or "..."
main.py:5: note: See https://mypy.readthedocs.io/en/stable/kinds_of_types.html#callable-types-and-lambdas
main.py:5: error: The last parameter to Concatenate needs to be a ParamSpec
Found 2 errors in 1 file (checked 1 source file)

playground

[KotlinIsland]

@sobolevn Should the message The first argument to Callable must be a list of types, parameter specification, or "..." be updated to include Concatenate or do you think that Concatenate falls under "parameter specification"?

[sobolevn]

do you think that Concatenate falls under "parameter specification"?

I think this is correct 🤔

[gandhis1]

Does MyPy actually support Concatenate? I attempted to use it, but it's rejecting my first parameter in Callable[Concatenate[Dict[str, sa.Table], P], sa.sql.expression.Selectable]