Rust lint (clippy) — error[clippy::...] / -D warnings

Log signatures

error: this `if` has identical blocks
warning: clippy::needless_return
could not compile due to clippy errors
note: `-D warnings` implied by `-D clippy::all`

What’s happening

Clippy found lints and the build runs with -D warnings, promoting every warning to a hard error. The structural cause of surprise clippy failures: a Rust toolchain update shipped new lints. Your code didn't change; the linter got stricter. Clippy lints come in tiers (correctness/suspicious lints are near-always real bugs; style/pedantic lints are judgment) — the tier should drive how seriously you take the finding.

Fix playbook

1. 1Reproduce with the exact CI invocation, including --all-targets (lints in tests/benches don't show without it) and the same toolchain (rustc --version vs CI).
2. 2cargo clippy --fix handles the mechanical cases; review the diff.
3. 3Correctness-tier lints: treat as bug reports, fix properly.
4. 4Style lints you disagree with: #[allow(clippy::lint_name)] at the narrowest scope with a comment — or set project policy in Cargo.toml's [lints] table so the decision is made once, visibly.
5. 5After a toolchain bump triggers a lint wave: fix in a dedicated PR, separate from feature work.