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False error in conditional expression returning union #6898
Description
- Are you reporting a bug, or opening a feature request?
Bug
- Please insert below the code you are checking with mypy,
or a mock-up repro if the source is private. We would appreciate
if you try to simplify your case to a minimal repro.
from typing import TypeVar, Union
T = TypeVar("T")
def get_or_str(value: T) -> Union[str, T]:
return value
def f(b: bool) -> Union[str, bool]:
return "" if b else get_or_str(True)- What is the actual behavior/output?
a.py:12: error: Argument 1 to "get_or_str" has incompatible type "bool"; expected "str"
- What is the behavior/output you expect?
No error.
- What are the versions of mypy and Python you are using?
Do you see the same issue after installing mypy from Git master?
0.710+dev.5f08ccf029aa3046b15e1afc60743ba692e4758d (from master)
- What are the mypy flags you are using? (For example --strict-optional)
None
Activity
ilevkivskyi commentedon May 26, 2019
The tuple example is a separate (relatively simple, but old) issue. The original example is just another case (among dozens) where single-bin inference would help.
I think we should really do this.
utkarshgupta137 commentedon Jun 8, 2021
I'm getting `Argument 1 to "func" has incompatible type "Union[str, float]"; expected "str" [arg-type]'. Is this related as well? Am I doing something wrong?
Use union of current context and left side for right side narrowing o…