Type-narrowing Union with Literal using comparison to Literal variable #16465
Description
Bug Report
Strangely, type-narrowing for unions including a Literal works for int but not datetime
To Reproduce
Mypy Playground. Copied here for convenience:
from datetime import datetime
from typing import Final, Literal
Unspecified = Literal['unspecified']
UNSPECIFIED: Final[Unspecified] = 'unspecified'
def do_thing(x: datetime | Unspecified) -> None:
if x != UNSPECIFIED:
print(x.utcnow()) # Unexpected error!
def do_thing_2(x: int | Unspecified) -> None:
if x != UNSPECIFIED:
print(x.real) # No probExpected Behavior
No errors.
Actual Behavior
Has errors:
main.py:9: error: Item "str" of "datetime | Literal['unspecified']" has no attribute "utcnow" [union-attr]
Your Environment
- Mypy version used: 1.7.0
- Mypy command-line flags: <none>
- Mypy configuration options from
mypy.ini(and other config files): <none> - Python version used: 3.11