UPDATE 2025/10/8: The example in the original issue report (preserved below) has been fixed, but Pyrefly still generates some related false positives.
Example 1:
import pathlib
def f(mod: str, stubs_path: pathlib.Path):
_, *submods = mod.split(".")
if (path := stubs_path.joinpath(*submods, "__init__.pyi")).is_file():
return path
assert submods, path # false positive: `path` is uninitialized
sandbox
Example 2:
def check():
if (y := 2) <= 1:
return
print(y) # false positive: `y` is uninitialized
check()
sandbox
--- original issue report ---
Describe the Bug
from typing import *
def f(v):
x: int
if (x := v) and v:
print(x) # E: `x` may be uninitializedSandbox Link
https://pyrefly.org/sandbox/?code=GYJw9gtgBALgngBwJYDsDmUkQWEMoBUAUEQCYCmwUwAFAG4CUAXEVG1AB5OYoyvtIqNDlCYBeKIygBDFKUkt2SqAhCoYwhkSA&version=3.12
(Only applicable for extension issues) IDE Information
No response
UPDATE 2025/10/8: The example in the original issue report (preserved below) has been fixed, but Pyrefly still generates some related false positives.
Example 1:
sandbox
Example 2:
sandbox
--- original issue report ---
Describe the Bug
Sandbox Link
https://pyrefly.org/sandbox/?code=GYJw9gtgBALgngBwJYDsDmUkQWEMoBUAUEQCYCmwUwAFAG4CUAXEVG1AB5OYoyvtIqNDlCYBeKIygBDFKUkt2SqAhCoYwhkSA&version=3.12
(Only applicable for extension issues) IDE Information
No response