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This output is from #8772:
$ mypy test.py
test.py:6: error: Argument 2 to "dumps" has incompatible type "**Dict[str, int]"; expected "bool"
test.py:6: error: Argument 2 to "dumps" has incompatible type "**Dict[str, int]"; expected "Optional[Type[JSONEncoder]]"
test.py:6: error: Argument 2 to "dumps" has incompatible type "**Dict[str, int]"; expected "Optional[Tuple[str, str]]"
test.py:6: error: Argument 2 to "dumps" has incompatible type "**Dict[str, int]"; expected "Optional[Callable[[Any], Any]]"
Found 4 errors in 1 file (checked 1 source file)
The error messages are pretty confusing. We should special case this and produce a customized error message that explains the situation better.
Here's the code that triggers the errors:
import json
json_kwargs = dict(indent=2)
json.dumps({}, **json_kwargs)Some ideas about what to do:
- Generate a single error message instead of multiple ones.
- Add a note suggesting the use of
Dict[str, Any]or a TypedDict type for the**kwargsargument. - Maybe also explain that mypy matches the value type against all arguments, or add a link to documentation (add something to common issues, for example).