rust-rules

Rust Rules

These rules come from app/rules/rust/ in ai-toolkit. They cover the project's standards for coding style, frameworks, patterns, security, and testing in Rust. Apply them when writing or reviewing Rust code.

Rust Coding Style

Naming

• snake_case: functions, methods, variables, modules, crates.
• PascalCase: types, traits, enums, structs, type parameters.
• SCREAMING_SNAKE: constants and statics.
• Short lifetimes: 'a, 'b. Descriptive only when multiple coexist: 'input, 'output.
• Crate names: kebab-case in Cargo.toml, snake_case in code.

Ownership

• Borrow (&T) when you only need to read. Own (T) when storing or consuming.
• Use &str over String in function parameters when possible.
• Use Cow<'_, str> when you sometimes need to allocate.
• Avoid .clone() as a first resort -- restructure ownership instead.
• Use Arc<T> only when shared ownership across threads is required.

Types

• Use newtypes for domain primitives: struct UserId(Uuid).
• Use #[derive(Debug, Clone, PartialEq)] on data types.
• Implement Display for user-facing output, Debug for developer output.
• Use #[non_exhaustive] on public enums and structs for future compatibility.
• Prefer enums over boolean flags for state representation.

Functions

• Return Result<T, E> for operations that can fail. Avoid panicking.
• Use impl Trait in argument position for flexibility, return position for simplicity.
• Use where clauses for complex bounds instead of inline.
• Prefer iterators over index-based loops.
• Use let-else (1.65+) for early-exit pattern matching.

Modules

• Use mod.rs or filename-based modules. Be consistent within the project.
• Re-export public API from lib.rs for a clean surface.
• Keep modules focused. One major type or concept per module.
• Use pub(crate) for internal-only visibility.

Formatting

• Use rustfmt with default settings. Do not fight the formatter.
• Use clippy with -D warnings in CI. Fix all warnings.
• Set MSRV (Minimum Supported Rust Version) in Cargo.toml.