Fix duration_suboptimal_units false positive on small literal values

[veeceey]

Summary

Fixes #16532

For plain integer literals, suppress the duration_suboptimal_units lint when the promoted (converted) value would be <= 10. Small promoted values like from_millis(1_000) -> from_secs(1) are not necessarily more readable, and keeping the smaller unit makes quick adjustments easier (e.g. changing 1_000 to 1_200).

For expressions (e.g. from_secs(10 * 60)), always trigger the lint regardless of the promoted value, since the expression already signals intent to compute a converted value.

This follows the approach discussed in the issue.

Test plan

• Updated tests/ui/duration_suboptimal_units.rs with test cases for literals with small/large promoted values and expressions
• Updated tests/ui/duration_suboptimal_units_days_weeks.rs with analogous test cases
• All compile tests pass: cargo test --test compile-test -- duration_suboptimal_units

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changelog: [duration_suboptimal_units]: no longer triggers on small literal values where the promoted unit conversion result is <= 10

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r? @Jarcho

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[ada4a]

It looks like there is already another PR for this: #16565. Do you want to collaborate with the it's author to decide between, or maybe combine, your approaches?

[veeceey]

Thanks for flagging #16565! I didn't see that one when I started working on this. Happy to close this in favor of that PR if the approach there covers the same case, or we can coordinate if there are differences. Let me know what makes sense.

[rustbot]

This PR was rebased onto a different master commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

[ada4a]

I think I prefer your comments in the code and in the tests, since they describe things in a bit more detail, but the test cases themselves look fine in both PRs. I'd say let's concentrate our efforts in the older PR

[veeceey]

Thanks for the pointer — happy to consolidate efforts on #16565. That PR covers the same fix and I agree concentrating on one is better. Closing this in favor of that one.