cargo-unused

cargo-unused.py

#!/usr/bin/env python3
import pytoml as toml
import argparse
import subprocess
import sys

def main():
    p = argparse.ArgumentParser('cargo-unused')

    # TODO: Should have an --all flag that detects unused deps on all crates in a workspace
    p.add_argument('--manifest-path', default='Cargo.toml', help='Path to Cargo.toml')

    # TODO: it would be better to search just the rs files that belong to the crate.
    #       Not sure how to properly do this though; Cargo.toml can tell us the crate root,
    #       but only rustc knows how to find the other modules from that.
    # TODO: Maybe support a glob option with globstars?
    p.add_argument('--search-path', default='src', help='source directory')

    # FIXME: how are you supposed to properly handle the fact that the first arg of a cargo
    #        subcommand is the subcommand name itself?
    argv = sys.argv
    if argv[0] == 'unused':
        del argv[0]
    args = p.parse_args(argv)

    with open(args.manifest_path) as f:
        cargo_toml = toml.load(f)

    # TODO: build-dependencies, which should only search rs files that belong to the build script
    found_unused = False
    for deps_key in ('dependencies', 'dev-dependencies'):
        for dep_package in cargo_toml[deps_key]:
            # TODO: support renamed dependencies
            dep_crate = dep_package.replace('-', '_')

            result = check_rg_match(
                pattern=rf'\b{dep_crate}\b',
                search_paths=[args.search_path],
            )
            if not result:
                print(f'Unused package: {dep_package}')
                found_unused = True

    sys.exit(int(found_unused))

def check_rg_installed():
    try: subprocess.check_output(['rg', '--version'])
    except FileNotFoundError: die('Please install ripgrep: cargo install rg')
    except subprocess.CalledProcessError: die('Error calling rg --version')

def check_rg_match(pattern, search_paths):
    try: subprocess.check_output(['rg', '--', pattern] + search_paths)
    except subprocess.CalledProcessError: return False
    return True

def die(*args):
    print(*args, file=sys.stderr)
    sys.exit(1)

if __name__ == '__main__':
    main()