50 Rust Rules Every Specialist Should Follow

A master checklist across safety, API design, async, performance, and tooling. Use in reviews and onboarding.

How to Use This List

Skim all 50 once, then deep-dive linked articles per gap.
Tick rules your team enforces in CI or CONTRIBUTING.md.
Revisit after toolchain or edition upgrades.

Safety and Correctness (1-10)

Minimize unsafe scope - isolate in small modules with # Safety docs.
Never unwrap in library public API - return Result.
Use ? for error propagation - avoid nested match noise.
Prefer try_from over lossy as casts - especially user input.
Run Miri/tests on unsafe code - catch UB in CI when feasible.
Deny unsafe_code in domain crates - single FFI crate exception documented.
Avoid panic! for control flow - use Result or Option.
Validate invariants in constructors - illegal states unconstructable.
Use checked_add for user-influenced arithmetic - or widen types.
Treat #[deny(warnings)] seriously on toolchain bumps - fix, do not silence globally.

Ownership and Types (11-20)

Newtype domain IDs - UserId not bare u64.
Borrow before clone - profile clones in hot paths.
Prefer &str over String in arguments - take impl AsRef<str> when flexible.
Use Cow at boundaries - borrow when possible, own when needed.
Enums over bool pairs - enum State { Draft, Live } not two bools.
Typestate for critical protocols - when illegal transitions are costly.
Implement From/TryFrom - standard conversion traits.
RAII for resources - files, locks, guards.
Avoid Rc<RefCell> webs - redesign with ownership or channels.
Document Send/Sync requirements - especially for generic bounds.

Async and Concurrency (21-30)

Do not block Tokio workers - spawn_blocking for sync I/O.
Use tokio::sync::Mutex in async - not std::sync::Mutex across await.
Timeout external calls - tokio::time::timeout.
Bound concurrency - semaphores on fan-out.
Understand Send bounds on spawned tasks - 'static + Send.
Graceful shutdown - signal + drain tasks.
Channels for work distribution - backpressure aware.
Atomics with correct ordering - not SeqCst by default everywhere.
Avoid shared mutable globals - OnceLock config instead.
Test async with #[tokio::test] - fake time with pause.

Performance and Build (31-40)

Measure release builds - profile before optimizing.
Thin LTO for production - tune with data.
Disable unused crate features - faster builds, smaller binaries.
Commit Cargo.lock for apps - reproducible deploys.
Use cargo clippy -D warnings - in CI.
Use cargo fmt --check - zero style debate.
Criterion for hot path regressions - not guesswork.
Avoid alloc in inner loops - reuse buffers.
Prefer iterators until proven slow - zero-cost abstractions.
Right-size connection pools - sqlx pool from load tests.

API, Errors, and Ecosystem (41-50)

Follow Rust API Guidelines naming - as_, to_, into_ conventions.
thiserror in libraries, anyhow in binaries - workspace policy.
Structured errors with context - error.source() chain.
Serde with #[serde(deny_unknown_fields)] on external input - when safe.
Feature flags documented - README examples.
cargo audit on schedule - supply chain hygiene.
Doctests on public examples - docs stay honest.
Integration tests on public API - not only private unit tests.
ADR for architecture forks - record tradeoffs.
Prefer std and well-maintained crates - audit before adding deps.

FAQs

All 50 mandatory?

Teams ratchet; start with safety, errors, CI (1-10, 41-48).

How enforce?

CI, clippy.toml disallowed methods, CODEOWNERS on unsafe crate.

Premium vs basic?

All listed rules are baseline specialist practice on this site.

Update cadence?

Review yearly with Rust edition and team incidents.

Junior vs senior?

Juniors focus 1-20; seniors own 21-50 and enforcement.

Link to deep dives?

See section articles: unsafe, async, performance, error rules.

Exceptions?

Document in ADR with owner and expiry date.

Embed in hiring?

Use as interview rubric for systems Rust roles.

vs clippy?

Rules align with clippy; clippy automates subset.

50 enough?

Starting point; team adds org-specific rules 51+.

Clippy Book / Lints - Official linter documentation.
The Rust Programming Language (The Book) - Canonical beginner-to-intermediate guide.
doc.rust-lang.org - Central documentation hub (The Rust Bookshelf).
Rust for Rustaceans (Amazon) - Jon Gjengset.
The Rust Programming Language, 3rd Edition (O'Reilly) - Klabnik, Nichols, Krycho.

Stack versions: This page was written for Rust 1.97.0 (edition 2024), Tokio 1.x, Axum 0.8, serde 1.0, sqlx 0.8, clap 4, and Polars 0.46+.

How to Use This List

Skim all 50 once, then deep-dive linked articles per gap.
Tick rules your team enforces in CI or CONTRIBUTING.md.
Revisit after toolchain or edition upgrades.

Safety and Correctness (1-10)

Minimize unsafe scope - isolate in small modules with # Safety docs.
Never unwrap in library public API - return Result.
Use ? for error propagation - avoid nested match noise.
Prefer try_from over lossy as casts - especially user input.
Run Miri/tests on unsafe code - catch UB in CI when feasible.
Deny unsafe_code in domain crates - single FFI crate exception documented.
Avoid panic! for control flow - use Result or Option.
Validate invariants in constructors - illegal states unconstructable.
Use checked_add for user-influenced arithmetic - or widen types.
Treat #[deny(warnings)] seriously on toolchain bumps - fix, do not silence globally.

Ownership and Types (11-20)

Newtype domain IDs - UserId not bare u64.
Borrow before clone - profile clones in hot paths.
Prefer &str over String in arguments - take impl AsRef<str> when flexible.
Use Cow at boundaries - borrow when possible, own when needed.
Enums over bool pairs - enum State { Draft, Live } not two bools.
Typestate for critical protocols - when illegal transitions are costly.
Implement From/TryFrom - standard conversion traits.
RAII for resources - files, locks, guards.
Avoid Rc<RefCell> webs - redesign with ownership or channels.
Document Send/Sync requirements - especially for generic bounds.

Async and Concurrency (21-30)

Do not block Tokio workers - spawn_blocking for sync I/O.
Use tokio::sync::Mutex in async - not std::sync::Mutex across await.
Timeout external calls - tokio::time::timeout.
Bound concurrency - semaphores on fan-out.
Understand Send bounds on spawned tasks - 'static + Send.
Graceful shutdown - signal + drain tasks.
Channels for work distribution - backpressure aware.
Atomics with correct ordering - not SeqCst by default everywhere.
Avoid shared mutable globals - OnceLock config instead.
Test async with #[tokio::test] - fake time with pause.

Performance and Build (31-40)

Measure release builds - profile before optimizing.
Thin LTO for production - tune with data.
Disable unused crate features - faster builds, smaller binaries.
Commit Cargo.lock for apps - reproducible deploys.
Use cargo clippy -D warnings - in CI.
Use cargo fmt --check - zero style debate.
Criterion for hot path regressions - not guesswork.
Avoid alloc in inner loops - reuse buffers.
Prefer iterators until proven slow - zero-cost abstractions.
Right-size connection pools - sqlx pool from load tests.

API, Errors, and Ecosystem (41-50)

Follow Rust API Guidelines naming - as_, to_, into_ conventions.
thiserror in libraries, anyhow in binaries - workspace policy.
Structured errors with context - error.source() chain.
Serde with #[serde(deny_unknown_fields)] on external input - when safe.
Feature flags documented - README examples.
cargo audit on schedule - supply chain hygiene.
Doctests on public examples - docs stay honest.
Integration tests on public API - not only private unit tests.
ADR for architecture forks - record tradeoffs.
Prefer std and well-maintained crates - audit before adding deps.

FAQs

All 50 mandatory?

Teams ratchet; start with safety, errors, CI (1-10, 41-48).

How enforce?

CI, clippy.toml disallowed methods, CODEOWNERS on unsafe crate.

Premium vs basic?

All listed rules are baseline specialist practice on this site.

Update cadence?

Review yearly with Rust edition and team incidents.

Junior vs senior?

Juniors focus 1-20; seniors own 21-50 and enforcement.

Link to deep dives?

See section articles: unsafe, async, performance, error rules.

Exceptions?

Document in ADR with owner and expiry date.

Embed in hiring?

Use as interview rubric for systems Rust roles.

vs clippy?

Rules align with clippy; clippy automates subset.

50 enough?

Starting point; team adds org-specific rules 51+.

Clippy Book / Lints - Official linter documentation.
The Rust Programming Language (The Book) - Canonical beginner-to-intermediate guide.
doc.rust-lang.org - Central documentation hub (The Rust Bookshelf).
Rust for Rustaceans (Amazon) - Jon Gjengset.
The Rust Programming Language, 3rd Edition (O'Reilly) - Klabnik, Nichols, Krycho.

Stack versions: This page was written for Rust 1.97.0 (edition 2024), Tokio 1.x, Axum 0.8, serde 1.0, sqlx 0.8, clap 4, and Polars 0.46+.

50 Rust Rules Every Specialist Should Follow

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50 Rust Rules Every Specialist Should Follow