Multiple dict unpacking for function arguments gives type error #4708
Description
When I run the following code through MyPy:
def fn(a: int, b: int, c: int) -> None:
print((a, b, c))
fn(**{'a': 10}, **{'b': 20, 'c': 30})
I receive the following:
$ python -m mypy mypy_problem.py
mypy_problem.py:8: error: Too many arguments for "fn"
I expect this to not give an error because as far as I know it's valid python code - it works at least! A workaround is to wrap the whole thing in another dictionary, i.e.:
fn(**{**{'a': 10}, **{'b': 20, 'c': 30}})
But this is messy and possibly introduces an additional overhead.
$ conda list | grep 'python\|mypy\|typed-ast'
mypy 0.570 <pip>
python 3.5.2 0 conda-forge
typed-ast 1.1.0 <pip>
I'm using Windows 7 64-bit.