# cargo-fl
Lightning-fast Rust linter that runs **without compilation**. Similar to [ruff](https://github.com/astral-sh/ruff) for Python, but for Rust.
> `fl` = fast lint. Because developer time is precious.
## Features
- **< 1 second** on large codebases (100k+ lines)
- **Zero compilation** - pure AST analysis using `syn`
- **Parallel processing** with `rayon`
- **Auto-fix support** for common issues
- **Configurable rules** via `.fl.toml`
- **LSP Server** for real-time editor feedback
- **VSCode Extension** for seamless integration
## Installation
```bash
cargo install cargo-fl
```
## Usage
### Command Line
```bash
# Lint current directory
cargo fl check
# Lint specific path
cargo fl check src/
# Auto-fix issues
cargo fl check --fix
# Different output formats
cargo fl check --format json
cargo fl check --format github # For CI
# Strict mode (exit 1 on issues)
cargo fl check --strict
```
### Configuration
Generate a default config:
```bash
cargo fl config --init
```
This creates `.fl.toml`:
```toml
[rules]
enable_all = true
disable = ["specific_rule"]
[severity]
unused_imports = "warning"
missing_docs = "info"
```
### Editor Integration
#### VSCode
1. Install the cargo-fl VSCode extension
2. The extension will automatically use the LSP server for real-time feedback
#### Other Editors
Use the LSP server directly:
```bash
cargo-fl-lsp
```
The LSP server supports:
- Real-time diagnostics
- Code actions (auto-fixes)
- Configuration via `.fl.toml`
## Rules
### Core Quality Rules
- **unwrap_usage**: Detects `.unwrap()`, `.unwrap_unchecked()`, and `.expect()` calls
- **todo_macros**: Finds `todo!()`, `unimplemented!()`, `unreachable!()`, and `panic!()` macros
- **must_use**: Identifies unused results from functions with `#[must_use]` return types
- **anti_patterns**: Common Rust anti-patterns and code smells
### Style & Structure Rules
- **unused_imports**: Detects unused import statements
- **missing_docs**: Missing documentation for public items
- **line_length**: Lines exceeding configured character limit
- **naming_convention**: Rust naming convention violations
### Complexity Rules
- **cyclomatic_complexity**: Functions with high cyclomatic complexity
- **cognitive_complexity**: Functions with high cognitive load
- **unsafe_code**: Unsafe code block warnings
### Import & Organization
- **import_order**: Incorrect import statement ordering
- **syntax_errors**: Basic syntax validation
## Performance
Typical performance on a 100k line Rust codebase:
- Analysis: < 1 second
- Memory usage: < 100MB
- Parallel processing across CPU cores
## Contributing
1. Fork the repository
2. Create a feature branch
3. Make changes with tests
4. Submit a pull request
## License
MIT OR Apache-2.0