dangle

A dead code detector for multi-language projects. Finds symbols that are defined but never referenced elsewhere in your codebase.

Installation

cargo install dangle

Usage

Run dangle in a git repository to find dead code candidates:

dangle

Output format:

path/to/file.rs:42: fn unused_function
path/to/file.py:17: class UnusedClass

Options

• -v, --verbose - Show all definitions found
• -h, --help - Print help

How It Works

Dangle uses tree-sitter for accurate AST-based parsing. Unlike regex-based approaches, it correctly ignores symbols that appear only in strings or comments.

The algorithm:

1. Discovers source files via git ls-files
2. Extracts definitions (functions, classes, structs, etc.) using tree-sitter queries
3. Extracts all identifier references
4. Reports definitions that are referenced only once (the definition itself)

Supported Languages

• Rust
• Python

More tree-sitter language support is planned for future releases.

Filters

Dangle automatically excludes:

• main functions
• test_* functions
• __* names (Python dunders, etc.)
• drop (Rust)
• Definitions marked with nodangle in a comment on the same line

License

MIT