Rule: Warn on unconsumed concurrent.futures.Executor.map() calls

[tmct]

Hello, currently this Python pattern, if used, leads to unhandled errors - silent failures:

with ThreadPoolExecutor(max_workers=n_workers) as executor:
    executor.map(...)  # n.b. we don't call list() or otherwise iterate

do_subsequent_things()

This is because exceptions are only raised when the values are retrieved from the iterator, and here that never happens. A simple fix is to iterate over it, e.g. _ = list(executor.map(...)).

It feels like the result of map() being not assigned at all is the kind of thing that static analysis could catch well? And it feels not unreasonable that intentional use cases of this ("fire-and-forget" maps) could be made to explicitly acknowledge usage of this with a "noqa"?

So... do you think that would this make a useful ruff lint rule?

Thanks,
Tom

[ntBre]

I think there's already a request for this rule in #21345!

[tmct]

Ah yes, that is indeed the same thing! Sorry, this didn't come up in my searches. Thank you