name: rust-ci-tooling description: Use when the user asks about CI/CD for Rust projects, clippy lints, rustfmt configuration, feature flag CI matrix, workspace-level tooling, justfile or Makefile setup, GitHub Actions for Rust, or pre-commit hooks for Rust projects. version: 1.0.0

Rust CI & Tooling — Clippy, Formatting & Automation

Workspace-level tooling configuration and CI patterns. Keep it simple — use cargo test and standard tooling. The goal: a single just ci command that catches everything, and a GitHub Actions workflow that mirrors it.

Clippy Configuration

Configure clippy at the workspace level in the root Cargo.toml:

[workspace.lints.clippy]
# Start with pedantic, then selectively allow the noisy ones
pedantic = { level = "warn", priority = -1 }

# These fire too often to be useful
module_name_repetitions = "allow"
must_use_candidate = "allow"
missing_errors_doc = "allow"
missing_panics_doc = "allow"

# Enforce in library crates (but allow in tests/binaries via per-crate overrides)
unwrap_used = "warn"

[workspace.lints.rust]
unsafe_code = "deny"

Member crates inherit with:

[lints]
workspace = true

Binary/test crates can relax specific lints:

[lints]
workspace = true

[lints.clippy]
unwrap_used = "allow"  # fine in binaries and tests

CI command

cargo clippy --workspace --all-targets -- -D warnings

The -- -D warnings promotes all warnings to errors in CI, ensuring clippy issues block the build.

rustfmt Configuration

Create .rustfmt.toml at the workspace root:

edition = "2021"
max_width = 100

CI command

cargo fmt --all -- --check

Feature Flag CI Strategy

Test multiple feature configurations to catch conditional compilation issues:

# Default features (what users get)
cargo test --workspace

# No default features (catches missing feature guards)
cargo test --workspace --no-default-features

# All features (catches feature conflicts)
cargo test --workspace --all-features

For crates with meaningful feature combinations, add a CI matrix. Document tested combinations in the workflow.

justfile — Workspace Task Runner

Use just (https://just.systems) for common workspace commands. Create a justfile at the workspace root:

# Default: run all checks
default: check test

# Format code
fmt:
    cargo fmt --all

# Check formatting (CI)
fmt-check:
    cargo fmt --all -- --check

# Run clippy
check:
    cargo clippy --workspace --all-targets -- -D warnings

# Run tests
test:
    cargo test --workspace

# Run tests with all feature combinations
test-features:
    cargo test --workspace
    cargo test --workspace --no-default-features
    cargo test --workspace --all-features

# Full CI pipeline locally
ci: fmt-check check test-features

# Build in release mode
build:
    cargo build --workspace --release

# Clean build artifacts
clean:
    cargo clean

# Watch and run tests on change (requires cargo-watch)
watch:
    cargo watch -x 'test --workspace'

GitHub Actions Workflow

Create .github/workflows/ci.yml:

name: CI

on:
  push:
    branches: [master]
  pull_request:
    branches: [master]

env:
  CARGO_TERM_COLOR: always
  RUSTFLAGS: "-D warnings"

jobs:
  check:
    name: Check
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - uses: dtolnay/rust-toolchain@stable
        with:
          components: clippy, rustfmt

      - uses: Swatinem/rust-cache@v2

      - name: Check formatting
        run: cargo fmt --all -- --check

      - name: Clippy
        run: cargo clippy --workspace --all-targets -- -D warnings

  test:
    name: Test
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - uses: dtolnay/rust-toolchain@stable

      - uses: Swatinem/rust-cache@v2

      - name: Run tests
        run: cargo test --workspace

      - name: Run tests (no default features)
        run: cargo test --workspace --no-default-features

      - name: Run tests (all features)
        run: cargo test --workspace --all-features

Pre-Commit Hooks

Keep pre-commit hooks lightweight. Only run fast checks:

#!/bin/sh
# .git/hooks/pre-commit (or via pre-commit framework)
cargo fmt --all -- --check

Do NOT run clippy or tests in pre-commit — they're too slow and will frustrate the workflow. Those belong in CI.

Consider typos-cli for catching spelling mistakes:

cargo install typos-cli
typos  # runs on all files

Useful Cargo Extensions

Related Skills

For workspace-level Cargo.toml setup and [workspace.lints], see the rust-project-setup skill. For test organization, see the rust-testing skill.