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Description
I saw that there is a similar bug around redefining a variable, but I believe this one is slightly different problem, here is the code:
#! /usr/bin/env python
from typing import Dict, List, Union
def main(arg):
# type: (bool) -> Union[Dict[str, str], List[str]]
if arg:
var = list()
var.append('something')
else:
var = dict()
var['key'] = 'something'
return var
if __name__ == '__main__':
main(True)
The variable var
while it uses the same name, it is technically a different variable, but mypy 0.630 is complaining about it:
$ ../py37/bin/mypy --python-executable ../py27/bin/python test.py
test.py:12: error: Incompatible types in assignment (expression has type "Dict[<nothing>, <nothing>]", variable has type "List[str]")
test.py:13: error: No overload variant of "__setitem__" of "list" matches argument types "str", "str"
test.py:13: note: Possible overload variants:
test.py:13: note: def __setitem__(self, int, str) -> None
test.py:13: note: def __setitem__(self, slice, Iterable[str]) -> None
Ideally it should have no problem with it and at the point where there is return
statement it should just do an union so the type would be Union[Dict[str, str], List[str]]