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var-annotated errors for iteration should point to the line where the variable is defined #22265
Description
Bug Report
See title
To Reproduce
from typing import Never
x: Never
sum( # non-native parser errors here
y # native parser errors here
for y in x # expected error here
)Expected Behavior
Expected an error at # expected error here.
Actual Behavior
Got an error at either # non-native parser errors here or # native parser errors here based on the parser.
Your Environment
Reproduced in mypy-play.
- Mypy version used: 2.4.0
- Mypy command-line flags: N/A
- Mypy configuration options from
mypy.ini(and other config files): N/A - Python version used: 3.12
Activity
ilevkivskyi commentedon Oct 22, 2026
This error is actually kind-of pointless in this case, since you cannot add an annotation inside a comprehension. Instead, we should say something different for a variable in comprehension.
A5rocks commentedon Oct 23, 2026
Yeah in these cases I've been resorting to:
but obviously that runs into the fact the annotation doesn't actually get persisted through -- kinda surprising until you remember narrowing behavior can vary based on whether the assignment has a declared type!
ilevkivskyi commentedon Oct 23, 2026
@A5rocks I am not sure you understand: mypy still shows
Need type annotation for "y"in your example, becauseyoutside comprehension, andyinside comprehension are two different variables (because comprehensions introduce a new scope).