Error passing ** keyword args to function with multiple optional arguments of different types

[pdebelak]

This is a bug report present in mypy 0.720 (currently lastest mypy).

I get an unexpected type error when trying to pass ** keyword args to a function with multiple optional arguments of different types.

Take this example code:

from typing import Optional


def a_func(arg1: Optional[str] = None, arg2: Optional[int] = None):
    pass


a_func(**{"arg2": 1})

I would expect this to report no type errors, but instead I get:

error: Argument 1 to "a_func" has incompatible type "**Dict[str, int]"; expected "Optional[str]"

Is there a way to get this to pass mypy checking? My real code involves passing a dynamic kwarg (like year, month, or week) along with a length to create several differentdateutil.relativedelta instances so rewriting it to not use ** would involve rewriting the real code to have a large number of conditionals.

[ilevkivskyi]

This is a duplicate of #5382