[LuisFigueroaG]

Refs #452.

B018 already reports a bare call to a builtin without side effects, like sorted(x) or isinstance(x, int), but not the ones that return a lazy iterator, where the statement looks like it does something and doesn't:

map(print, items)  # nothing iterates over the map, so print never runs
reversed(items)  # meant items.reverse()

This adds map, filter, reversed, zip and enumerate. The first three are the calls @JelleZijlstra listed in #452 next to sorted, which is already covered; zip and enumerate are lazy in the same way. It's also an easy leftover from Python 2, where map() and filter() returned lists. iter stays out, since a bare iter(x) is there to call x.__iter__().

Like the operations from #579, a call directly in a try/with block is left alone. These check their arguments right away, and tests call them only to see that raise, as CPython does with with self.assertRaises(TypeError): zip(BadIterable()) and try: reversed(f) except TypeError:. As with the other builtins, the arguments aren't looked at: in map(handle, fetch()), fetch runs but handle never does, so that's still reported.

On CPython's Lib from main (2,071 files, tests included), Ubuntu's dist-packages (2,145) and about 14,000 files from other projects, this adds 3 reports: filter(identity, Squares(5)) in test_builtin.py, which tests filter itself, and two enumerate(...) lines in a black formatter fixture. Both files already get B018.

Tests are in tests/eval_files/b018_lazy_calls.py. b905_py310.py and b912_py314.py call zip() and map() as statements, so I assigned their results, like #547 did in b023.py. tox py310–py315 and pre-commit pass.

[Copilot]

🟢 Approval recommended

The scoped detection change, exemptions, documentation, and fixture updates are consistent, with no unresolved findings.

No open issues 🎉

What changed in this PR

Extends B018’s useless-expression detection to report discarded calls to lazy builtins, addressing another case discussed in #452.

Changes:

• Detects standalone map, filter, reversed, zip, and enumerate calls while preserving direct try/with exemptions.
• Adds coverage for reported calls and intentional exclusions, and adjusts existing fixtures to avoid unrelated B018 diagnostics.
• Documents the expanded behavior and adds a changelog entry.

File	Description
tests/​eval_files/​b912_py314.py	Assigns map results and adjusts expected B912 columns.
tests/​eval_files/​b905_py310.py	Assigns zip results and adjusts expected B905 columns.
tests/​eval_files/​b018_lazy_calls.py	Covers discarded lazy calls, consumed results, and raising-block exemptions.
README.rst	Documents lazy-call detection and records the change.
bugbear.py	Adds lazy builtin names and integrates them into B018 detection.

_{Review effort: Balanced}

[cooperlees]

LGTM - Thanks for more work on reported issues!