[LuisFigueroaG]

B018 reports a bare map(), filter(), reversed(), zip() or enumerate() statement as a lazy builtin (#605), but it doesn't check that the name is the builtin. When the module binds it to something else, the call can do real work. From statsmodels' tests:

# statsmodels/tsa/statespace/tests/test_kalman.py
def test_copied_filter(self):
    _, filter = self.init_filter()
    filter()  # B018, but this runs the Kalman filter

The same goes for a module with its own def map(func, items) or from mylib import map.

B031 and B911 already have this check for groupby() and batched() (#608). This makes it take the module the name should come from, and B018 uses it with builtins. Still reported:

• names the module never binds, which is the usual case.
• from builtins import map and from builtins import *.
• map = builtins.map.

On about 51,000 files (site-packages from ten project virtualenvs, Ubuntu's Python 3.12 stdlib and the repos in my workspace), B018 reports go from 2887 to 2886. Nothing new is reported. The removed one is the statsmodels case above. The other 16 lazy-builtin reports stay, such as map(np.random.shuffle, d1) in numpy's tests, which never shuffles anything.

New cases are in tests/eval_files/b018_shadowed*.py. Two of them fail on main (the alias case passes there and guards the regression). tox py310–py315, mypy and pep8_naming pass, and so does pre-commit.

[Copilot]

🟡 Changes recommended

An active moderate issue remains because later module-level definitions or assignments do not override the earlier import, causing B018 to misidentify shadowed names as lazy builtins.

1 open issue

• Resolve later module bindings over builtin imports · New

What changed in this PR

This pull request updates B018 to report bare lazy-iterator calls only when they resolve to Python builtins, avoiding false positives for module-defined or imported alternatives. It also generalizes module-binding resolution used by B031 and B911.

Changes:

• Generalizes module binding detection for arbitrary source modules and aliases.
• Applies builtin resolution to B018’s map(), filter(), reversed(), zip(), and enumerate() checks.
• Adds shadowing and alias regression fixtures.
• Documents the unreleased behavior change in README.rst.

File	Summary
tests/​eval_files/​b018_shadowed.py	Tests module-defined lazy-function names and builtin fallback behavior.
tests/​eval_files/​b018_shadowed_import.py	Tests builtin and third-party imports under lazy-builtin names.
tests/​eval_files/​b018_shadowed_alias.py	Tests assignments from builtins.map.
README.rst	Documents the unreleased B018 shadowing behavior.
bugbear.py	Generalizes name-resolution helpers and applies builtin resolution to B018, B031, and B911. A moderate issue remains because later definitions or assignments do not override earlier imports in source-order resolution.

This pull request requires changes.

_{Review effort: Lite}