rust-clippy

name	rust-clippy
description	Run Clippy with strict lint settings and fix warnings for Rust code. Use when asked to lint code, fix clippy warnings, enforce Rust idioms, check code quality, or run static analysis. Applies project-specific lint configuration and explains fixes.
allowed-tools	Bash, Read, Edit, Grep, Glob

Rust Clippy Lint Enforcer

Run Clippy with strict settings, analyze warnings, and apply idiomatic fixes for the cqlsh-rs project.

Workflow

1. Run Clippy with strict settings to identify all warnings
2. Categorize warnings by severity and type
3. Apply fixes automatically where safe, manually where judgment is needed
4. Verify fixes compile and pass tests

Running Clippy

CI-equivalent command (always run this before pushing)

The CI pipeline sets RUSTFLAGS="-Dwarnings" globally, which treats all Rust warnings as compilation errors. Always verify locally with the same flags:

RUSTFLAGS="-Dwarnings" cargo clippy --all-targets --all-features 2>&1

This catches not just clippy lints but also rustc warnings (unused imports, dead code, etc.) that CI will reject.

Full project scan (development)

cargo clippy --all-targets --all-features -- -W clippy::all -W clippy::pedantic -W clippy::nursery 2>&1

Specific module

cargo clippy --lib -- -W clippy::all 2>&1

Auto-fix safe suggestions

cargo clippy --fix --allow-dirty --allow-staged -- -W clippy::all 2>&1

Lint Categories

Apply these lint levels for cqlsh-rs:

Always fix (deny)

• clippy::unwrap_used — Use expect() with context or propagate with ?
• clippy::panic — Replace with proper error handling
• clippy::todo — Implement or convert to tracked issue
• clippy::unimplemented — Implement or return error
• clippy::dbg_macro — Remove before commit
• clippy::print_stdout / clippy::print_stderr — Use tracing or eprintln! for user-facing output

Strongly recommended (warn → fix)

• clippy::needless_pass_by_value — Take references where ownership isn't needed
• clippy::redundant_clone — Remove unnecessary .clone() calls
• clippy::large_enum_variant — Box large variants to reduce enum size
• clippy::inefficient_to_string — Use to_owned() for &str to String
• clippy::manual_let_else — Use let...else pattern (Rust 1.65+)
• clippy::needless_borrow — Remove unnecessary & or &mut
• clippy::explicit_iter_loop — Use for x in &collection instead of .iter()
• clippy::match_wildcard_for_single_variants — Name the variant explicitly
• clippy::implicit_clone — Use explicit .clone() for clarity
• clippy::uninlined_format_args — Use inline format args {var} instead of {}, var
• clippy::semicolon_if_nothing_returned — Add semicolon to unit-returning expressions

Context-dependent (evaluate case by case)

• clippy::module_name_repetitions — Allow if it matches CQL/Cassandra terminology
• clippy::must_use_candidate — Add #[must_use] to pure functions returning values
• clippy::missing_errors_doc — Add error docs to public API functions
• clippy::missing_panics_doc — Document panic conditions

Fix Patterns

Replace unwrap() with context

// Before
let value = map.get("key").unwrap();

// After
let value = map.get("key").expect("key must exist after validation");

// Or propagate
let value = map.get("key").ok_or_else(|| anyhow!("missing key"))?;

Fix needless clones

// Before
fn process(data: String) { /* only reads data */ }
process(my_string.clone());

// After
fn process(data: &str) { /* only reads data */ }
process(&my_string);

Use let-else for early returns

// Before
let value = match optional {
    Some(v) => v,
    None => return Err(Error::Missing),
};

// After
let Some(value) = optional else {
    return Err(Error::Missing);
};

Box large enum variants

// Before — large variant bloats all variants
enum Command {
    Simple(u8),
    Complex { data: [u8; 1024], metadata: HashMap<String, String> },
}

// After
enum Command {
    Simple(u8),
    Complex(Box<ComplexCommand>),
}

Output Format

After running Clippy, report:

1. Summary: Total warnings by category
2. Critical: Items that must be fixed (deny-level)
3. Recommended: Items that should be fixed (warn-level)
4. Skipped: Items intentionally allowed with rationale
5. Verification: Confirm cargo check and cargo test pass after fixes