Type checking for *args and **kwargs when passing them to another function

Problem:

I am writing a python application, and I made a function that creates an object and passes its additional *args and **kwargs to object's constructor and takes few its own arguments. I want to make *args and **kwargs typed exactly as inner function's arguments.

Description and examples:

A simple example with two functions:

def inner(a: int, b: int) -> None:
    ...


def wrapper(arg1: str, *args, **kwargs) -> None:
    inner(*args, **kwargs)  # It will automatically detect passing arguments to another function

In my case, inner is object constructor, I gave an example with functions to make it more simple.

Type checkers should see wrapper's signature like this:

def wrapper(arg1: str, a: int, b: int):
    ...

It may be enabled by default when passing *args and **kwargs to another function is detected or it may be enabled by adding a decorator to the function.

Detailed description:

Already suggested this to mypy, detailed description of this feature can be found here: python/mypy#19302.

Inizia con gli esempi di wrapper e di funzione interna nell’issue, poi leggi la discussione collegata mypy#19302 sulla proposta esistente e sui vincoli. Il lavoro sarà completato quando sarà disponibile un approccio documentato e concordato per derivare o dichiarare i tipi degli argomenti del wrapper dalla funzione o dal costruttore che riceve *args e **kwargs.