Proposed Check: variable used outside of for-loop scope

Hi,

Python doesn't scope variables from a for loop, which I don't think I've ever intentionally used as a language feature, and has only been a source of bugs for me.

for x in range(5):
    print(x)
print(x)  # conspicuous usage

I think this would be the same for scopes like context managers; using the file pointer after exiting the open context manager.

I dunno if this is something that would maybe be considered for bugbear to identify.

I was thinking that when it's intentional usage could maybe be identified with something like:

x = None
for x in range(5):
    print(x)
print(x)

# OR

for x in range(5):
    print(x)
last_x = x  #noqa

Thanks for considering this.

The issue proposes a new check for Python variables used after for-loop or context-manager scopes, but it does not name an implementation file, test, or entry point. Start by reviewing the existing flake8-bugbear checks and discuss the intended scope and exemptions. Done requires an agreed behavior and tests covering intentional and unintended uses.