BUG/QUESTION: Not sure if B020 is expected to trigger here

running flake8 with the latest version of bugbear on this snippet

for var in (var for var in range(10) if var % 2):
    print(var)

results in

t.py:1:5: B020 Found for loop that reassigns the iterable it is iterating with each iterable value.

Is this expected ? I don’t understand how the error message relates to what’s actually happening here, it seems to me that this could be a mistake.

[jpy-git]

I’ve made a PR to these false positives 👍

[jpy-git]

It’s comprehensions in general not just generators that have this issue

for var in [var for var in range(10)]:
    print(var)

for var in (var for var in range(10)):
    print(var)

for k, v in {k: v for k, v in zip(range(10), range(10, 20))}.items():
    print(k, v)

N.B. we don’t want to exclude comprehensions from this check completely. This example is still bad and should be flagged:

vars = range(10)
for vars in [i for i in vars]:
    print(vars)

So I think the rule needs to account for the fact that variables declared in the for clause of a comprehension are local to the scope of that comprehension and should be excluded from the check.