Type narrowing not performed in walrus operator conditional #19036
Description
Bug Report
Type narrowing is not performed in a conditional containing a walrus operator if:
- There is another conditional in the same statement (
if maybe and), and - An attribute access is performed on the value of the walrus operator (
foo := Foo(True)).value)
To Reproduce
https://mypy-play.net/?mypy=latest&python=3.13&flags=strict&gist=7e7edfa1d3debec48847590a6c4532c9
class Foo:
value: bool
def __init__(self, value: bool) -> None:
self.thing = value
def bad(maybe: bool) -> None:
foo = None
if maybe and (foo := Foo(True)).value:
reveal_type(foo)
def correct1(maybe: bool) -> None:
foo = None
if maybe and (foo := Foo(True)):
reveal_type(foo)
def correct2(maybe: bool) -> None:
foo = None
if maybe:
if (foo := Foo(True)).value:
reveal_type(foo)Expected Behavior
The revealed type is always Foo.
Actual Behavior
main.py:11: note: Revealed type is "Union[__main__.Foo, None]"
main.py:17: note: Revealed type is "__main__.Foo"
main.py:24: note: Revealed type is "__main__.Foo"
Success: no issues found in 1 source file
Your Environment
- Mypy version used: 1.15.0
- Mypy command-line flags:
--strict - Python version used: 3.13