Incorrect error message when passing a dict to a function

[SizzlingVortex]

from typing import Mapping


def func(results: Mapping[str, str]) -> None:
    pass


if __name__ == "__main__":
    # Passing an int here (even though all values should be strings) is intentional
    func({"1":"1", "2":2})

Running the above code through mypy gives me the following incorrect error message:

error: List item 1 has incompatible type "Tuple[str, int]"

Strangely enough, the next section of code (which is nearly the same as the above code) produces a better error message:

from typing import Mapping


def func(results: Mapping[str, str]) -> None:
    pass


if __name__ == "__main__":
    # Using an int here (even though all values should be strings) is intentional
    my_dict = {"1":"1", "2":2}
    func(my_dict)

Running this code through mypy gives the following (better) error message:

error: Argument 1 to "func" has incompatible type Dict[str, object]; expected Mapping[str, str]

My Specs:
Python 3.5.1
mypy-lang 0.4.2

[JukkaL]

This is a duplicate of an existing issue (#304).

The examples are a little different from mypy's point of view. In the the first case mypy tries to infer a type for the dictionary expression based on the context where it is used (Mapping[str, str]), and the values don't conform to the context. In the second case mypy infers a type for the dictionary based on no context, so it can give the dictionary are wide enough type. However, this turns out to be incompatible with the function argument later on.