Linting & Formatting Highlights Summary

Every highlight bullet from the 9 pages in this section, gathered on one page and grouped by the page it came from.

Rust's Built-In Quality Tooling

• rustfmt removes style debate by defining one canonical layout, not by offering configurable taste.
• clippy runs after rustc's own checks and catches non-idiomatic or inefficient code that still compiles cleanly.
• Lint levels (allow/warn/deny/forbid) are a dial, not a switch, letting teams tune strictness per crate or per line.
• The [lints] table in Cargo.toml centralizes policy so it travels with the code instead of living in CI scripts.
• None of this tooling replaces tests or code review; it only removes a category of avoidable, low-value discussion.

rustfmt

• Use rustfmt to enforce consistent Rust formatting
• Run cargo fmt locally and cargo fmt --check in CI
• Configure rustfmt with a rustfmt.toml file at your repo root
• Pin your Rust toolchain version to avoid rustfmt version differences
• Exclude generated files from formatting to prevent merge conflicts
• Use #[rustfmt::skip] sparingly for macro-heavy code

Clippy

• Run Clippy on every PR with -D warnings to treat lints as errors
• Use cargo clippy --workspace --all-targets to lint all code
• Fix feature-gated dead code warnings with cargo clippy --all-features
• Match your CI toolchain version to avoid stale Clippy suggestions
• Treat clippy::redundant_clone seriously in hot code paths
• Prefer [lints.clippy] in Cargo.toml for crate-wide policy

Lint Levels & Attributes

• Rust lints can be allowed, warned, denied, or forbidden
• Cargo.toml [lints] tables centralize lint policy
• forbid is the strongest level and cannot be overridden downstream
• deny(warnings) without policy breaks on new Rust warnings
• #[allow(clippy::lint)] suppresses a lint for a specific item
• Libraries often warn on unwrap; applications may deny it

Configuring Clippy

• Configure Clippy with clippy.toml or Cargo.toml [lints.clippy]
• Tune thresholds, disallowed methods, and third-party macros
• Place clippy.toml at the workspace root or crate root
• Use disallowed-methods to ban specific APIs with custom reasons
• Set msrv in clippy.toml to filter lints for your Rust version
• Review Clippy changelogs when upgrading Rust toolchains

Documentation Lints

• Enable missing_docs for libraries your consumers depend on
• Use broken_intra_doc_links = "deny" to catch invalid doc links
• Document public items with /// and crate/module with //!
• Use RUSTDOCFLAGS="-D warnings" to fail CI on broken links
• Add # Errors or # Safety sections for relevant public APIs

Pre-commit & Editor Setup

• Local tooling catches fmt and clippy issues before CI
• Configure rust-analyzer for inline clippy hints and format-on-save
• Use pre-commit hooks to run cargo fmt --check and cargo clippy
• Pin your Rust toolchain with rust-toolchain.toml for consistency
• Add rustfmt and clippy components to your toolchain

Linting in CI

• CI enforces cargo fmt --check and cargo clippy -D warnings
• Cache dependencies and pin Rust 1.97.0 for reproducible lint results
• Run fmt --check first for fast feedback on style drift
• Use rust-cache or GitHub cache to speed up repeated CI runs
• Lint with --all-features to catch issues in cfg-gated code

Linting & Formatting Best Practices

• cargo fmt --check on every PR
• clippy -D warnings with all-targets
• Pinned Rust 1.97.0 toolchain
• Documented allow exceptions only