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Misleading error when using a dict of keyword args #14073
Description
Bug Report
When passing at least part of the function parameter as an ** expanded dictionary, if one or more of the parameters is missing, a misleading "incomaptible type" is shown, instead of "missing parameter".
See also stackoverflow for a way to get a better (but still not correct, since it lists all the parameters as missing) message
To Reproduce
def my_func(a: str = 'Hello', b: bool = False, c: int = 1):
return a, b, c
input_kwargs = {'b': True}
result = my_func(**input_kwargs)or see the gist
Actual Behavior
main.py:14: error: Argument 1 to "fib" has incompatible type "**Dict[str, int]"; expected "str"
Found 1 error in 1 file (checked 1 source file)
Your Environment
- Mypy version used: 0.812 (or 0.981 on mypy-play)
- Mypy command-line flags:
- Mypy configuration options from
mypy.ini(and other config files):
check_untyped_defs = True
show_error_codes = True
pretty = True
ignore_missing_imports = True
- Python version used: 3.8 (or 3.10 on mypy-play)
Activity
ikonst commentedon Jan 27, 2023
This report is a bit misleading since it might appear that in the example, the problem is that mypy understands that
input_kwargsprovides parameterbbut notaandc, which in practiceinput_kwargsis seen as an opaquedict[str, bool].A simpler case is:
Actual:
Now, as to what's "expected", maybe something like this?
or maybe, if we want to nudge users towards TypedDict:
Playground URL: https://mypy-play.net/?gist=3d6875bd1447fe1b1259c3455155bea5