Rust Formatting

Rust Formatting

Use When

• Setting up or validating code formatting for Rust projects.
• Configuring rustfmt and Clippy for consistent style.
• Integrating formatting into the IDE or pre-commit hooks.

Standard Formatters

1. rustfmt (built-in, recommended)

• Rust's official formatter; part of the standard toolchain.
• Install: rustup component add rustfmt.
• Run: cargo fmt to format all files in the workspace.

1. Clippy (linting)

• Official Rust linter; catches idiomatic and correctness issues.
• Install: rustup component add clippy.
• Run: cargo clippy -- -D warnings to treat warnings as errors.

Configuration

rustfmt.toml (project root):

edition = "2021"
max_width = 100
tab_spaces = 4
use_small_heuristics = "Default"
imports_granularity = "Crate"
group_imports = "StdExternalCrate"

.clippy.toml or Cargo.toml (Clippy lints):

[lints.clippy]
pedantic = "warn"
nursery = "warn"
unwrap_used = "deny"
expect_used = "warn"

VS Code .vscode/settings.json:

{
  "[rust]": {
    "editor.formatOnSave": true,
    "editor.defaultFormatter": "rust-lang.rust-analyzer"
  },
  "rust-analyzer.checkOnSave.command": "clippy",
  "rust-analyzer.rustfmt.extraArgs": []
}

Checklist

1. Consistency

• rustfmt is configured with a rustfmt.toml that matches team preferences.
• Clippy is run on CI with -- -D warnings to prevent regressions.
• Edition is explicitly set (edition = "2021" recommended).

1. IDE integration

• rust-analyzer extension is installed and active.
• Format-on-save is enabled.
• Clippy is used as the check command (not just cargo check).

1. Pre-commit hooks

• Use pre-commit or git hooks to run cargo fmt --check and cargo clippy.
• Prevents unformatted or lint-failing code from entering the repository.

1. Import organization

• imports_granularity = "Crate" groups imports by crate for readability.
• group_imports = "StdExternalCrate" separates std, external, and local imports.

Formatting Rules

• Indentation: 4 spaces (Rust standard).
• Line width: 100 characters (rustfmt default is 100).
• Trailing commas: Used in multi-line structures.
• Imports: Grouped by std, external crates, and local modules.

Common Commands

• Format: cargo fmt.
• Check (no changes): cargo fmt -- --check.
• Lint: cargo clippy.
• Lint as errors: cargo clippy -- -D warnings.

Output Requirements

When setting up or validating formatting, provide:

• Formatter versions and configuration.
• IDE integration status.
• Pre-commit hook setup summary.
• Any formatting conflicts or Clippy violations found.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: caraya
• Source: caraya/agent-skills
• License: MIT

Install and usage instructions live in the source repository linked above.