backlog#1823 step 10, batch 2. Eighteen of the nineteen suppress nothing and are deleted; one was real and keeps an allow that now says why.
Rotation::Never is constructed only by the rolling-appender tests at rolling.rs:456, 477 and 498, so the lib target reports it as never constructed. Its allow is restored with that reason.
Finding it corrected the method used for batch 1. Removing all nineteen and running cargo check -p rustfs-obs --tests reported zero warnings even after touching every source file, while clippy --lib --tests -D warnings caught Rotation::Never. cargo's warning output is not a reliable completeness check — it does not re-emit for cached compilations, and touching the sources did not cover the lib target here. Later batches should treat clippy -D warnings as the gate; batch 1's six crates were re-checked under clippy and are clean.
Taken with #6086, which cleared this crate's 44 module-level blankets and left six real items, obs has now had 63 dead-code suppressions examined, of which seven were suppressing anything at all. The rest sat on items that are publicly reachable, where dead_code never applied — the same shape as the swift module and kms's dek.rs.
Verification: clippy --lib --tests -D warnings clean in the default, gpu and pyroscope lanes; cargo nextest run -p rustfs-obs 324 passed; make pre-commit exit 0.
Ref rustfs/backlog#1823 (step 10).
Zhengchao An