B007 does not detect unused variables when they are shadowed or appear in inner scope

[LordAro]

B007 (unused-loop-control-variable) does not trigger when variables are shadowed.

See this extremely contrived example:

my_dict = my_other_dict = {}
my_list = []
for k, (v1, v2) in my_dict.items():
    for v1 in my_other_dict.values():
        print(v1)
    v2 = "flibble"
    print([k for k in my_list if k > 0])

https://play.ruff.rs/92ded63b-80d4-4d7d-989a-3460865af51b

(Example is somewhat nested loop focused as that's what I thought the problem was initially)

Interestingly, PERF102 does trigger with this example, but I think only because it doesn't process comprehensions at all? If it's expanded out the warning goes away.

The only thing of note from ALL is PLW2901, which detects the variable shadowing.

Related issues: #8786 #9454 #10723

ruff 0.7.2

[dylwil3]

Excellent, thanks for this! It looks like the same problem occurs even in this smaller example Playground link:

for k in ls:
    print([k for k in otherls])

[dylwil3]

I guess technically my previous example wasn't "shadowing", but an issue of scope. But shadowing also doesn't work (as you showed well in your original example):

for k in ls:
    k = 2

But, as you also point out, this is caught by PLW2901.