deadnix

deadnix

Scan .nix files for dead code (unused variable bindings).

Usage with Github Actions

See deadnix-action

Usage with Nix Flakes

Help

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Reports contain ANSI color escape codes unless the $NO_COLOR environment variable is set.

The --exclude parameter accepts multiple paths. Separate them with -- to pass [FILE_PATHS]....

Scan for unused code

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Remove unused code automatically

Do commit your changes into version control before!

nix run github:astro/deadnix -- -eq test.nix

Usage with pre-commit

Add the following to your project's .pre-commit-config.yaml:

repos:
  - repo: https://github.com/astro/deadnix
    rev: ID # frozen: VERSION
    hooks:
      - id: deadnix
        #args: [--edit] # Uncomment to automatically modify files
        stages: [commit]

Replace ID and VERSION above with the relevant version tag and commit ID for reference, for example:

rev: da39a3ee5e6b4b0d3255bfef95601890afd80709  # frozen: v1.2.3

Behavior

Renaming of all unused to lambda args to start with _

If you disfavor marking them as unused, use option -l/--no-lambda-arg.

nixpkgs callPackages with multiple imports

callPackages guesses the packages to inject by the names of a packages' lambda attrset pattern names. Some packages alias these with @args to pass them to another import ...nix args.

As the used args are only named in the imported file they will be recognized as dead in the package source file that is imported by callPackage, rendering it unable to guess the dependencies to call the packages with.

Use option -L/--no-lambda-pattern-names in this case.

Skipping reports for certain declarations

As of 1.1.0 deadnix supports the following pragma to skip check of bindings in the following line:

# deadnix: skip

What if the produced reports are wrong?

Please open an issue. Do not forget to include the .nix code that produces incorrect results.

Commercial Support

The author can be hired to implement the features that you wish, or to integrate this tool into your toolchain.