[spicysharkco]

B012 does not report break or continue in a for or while loop inside a finally block, since they only leave that loop (#106, fixed in #107). An async for loop is missing from that exemption.

async def f(xs):
    try:
        pass
    finally:
        async for x in xs:
            if x:
                break
            continue

flake8 --select=B012 file.py reports:

file.py:7:17: B012 return/continue/break inside finally blocks cause exceptions to be silenced. ...
file.py:8:13: B012 return/continue/break inside finally blocks cause exceptions to be silenced. ...

The same loop written as for x in xs: in a plain def is clean. Neither statement can silence an exception from the try block, so both reports are false positives. The README text for B012 is about break, continue or return that "will silence exceptions or override return values from the try or except blocks".

Cause: _loop in check_for_b012 only treats ast.While and ast.For as loops (bugbear.py#L1415).

Fix: add ast.AsyncFor to that tuple. A return inside the loop is still reported.

Test: a new async def case in tests/eval_files/b012.py with break and continue (no warning) and return (B012). pytest tests/test_bugbear.py -k b012 fails before the fix with two extra B012 reports and passes after. Full tests/test_bugbear.py: 123 passed, 4 skipped (Python 3.12, flake8 7.4.1). The pre-commit hooks pass. I added a line under UNRELEASED in README.rst.

[Copilot]

🟡 Changes recommended

The exemption also hides valid warnings for exception-suppressing exits in an async loop’s else suite.

1 open issue

• Restrict async for exemption to loop body, not orelse · New

What changed in this PR

Extends B012’s loop exemption to async for inside finally, matching existing synchronous-loop handling.

Changes:

• Exempts async-loop break and continue while retaining warnings for return.
• Adds regression coverage and an unreleased changelog entry.

File	Description
tests/​eval_files/​b012.py	Adds async-loop diagnostic cases.
README.rst	Documents the B012 change.
bugbear.py	Adds ast.AsyncFor to loop handling.

_{Review effort: Balanced}

[cooperlees]

Thanks!