mirror of
https://github.com/astro/deadnix.git
synced 2024-12-11 12:57:47 +03:00
135 lines
3.7 KiB
Markdown
135 lines
3.7 KiB
Markdown
# deadnix
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Scan `.nix` files for dead code (unused variable bindings).
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## Usage with Github Actions
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See [deadnix-action](https://github.com/astro/deadnix-action)
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## Usage with Nix Flakes
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### Help
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```
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$ nix run github:astro/deadnix -- --help
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```
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```
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USAGE:
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deadnix [OPTIONS] [FILE_PATHS]...
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ARGS:
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<FILE_PATHS>... .nix files, or directories with .nix files inside [default: .]
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OPTIONS:
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-_, --no-underscore
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Don't check any bindings that start with a _
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-e, --edit
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Remove unused code and write to source file
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-f, --fail
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Exit with 1 if unused code has been found
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-h, --hidden
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Recurse into hidden subdirectories and process hidden .*.nix files
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--help
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Print help information
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-l, --no-lambda-arg
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Don't check lambda parameter arguments
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-L, --no-lambda-pattern-names
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Don't check lambda attrset pattern names (don't break nixpkgs callPackage)
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-o, --output-format <OUTPUT_FORMAT>
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Output format to use [default: human-readable] [possible values: human-readable, json]
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-q, --quiet
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Don't print dead code report
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-V, --version
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Print version information
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```
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Reports contain ANSI color escape codes unless the
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[`$NO_COLOR`](https://no-color.org/) environment variable is set.
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### Scan for unused code
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```
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$ nix run github:astro/deadnix test.nix
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```
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```
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Warning: Unused declarations were found.
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╭─[example.nix:1:1]
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│
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1 │ unusedArgs@{ unusedArg, usedArg, ... }:
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· ─────┬──── ────┬────
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· │ ╰────── Unused lambda pattern: unusedArg
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· │
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· ╰────────────────── Unused lambda pattern: unusedArgs
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3 │ inherit (builtins) unused_inherit;
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· ───────┬──────
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· ╰──────── Unused let binding: unused_inherit
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5 │ unused = "fnord";
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· ───┬──
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· ╰──── Unused let binding: unused
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10 │ shadowed = 42;
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· ────┬───
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· ╰───── Unused let binding: shadowed
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11 │ _unused = unused: false;
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· ───┬─── ───┬──
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· │ ╰──── Unused lambda argument: unused
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· │
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· ╰────────────── Unused let binding: _unused
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13 │ x = { unusedArg2, x ? args.y, ... }@args: used1 + x;
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· ─────┬────
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· ╰────── Unused lambda pattern: unusedArg2
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────╯
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```
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### Remove unused code automatically
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**Do commit** your changes into version control **before!**
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```
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$ nix run github:astro/deadnix -- -eq test.nix
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```
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## Behavior
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### Renaming of all unused to lambda args to start with `_`
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If you disfavor marking them as unused, use option `--no-lambda-arg`.
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### nixpkgs `callPackages` with multiple imports
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`callPackages` guesses the packages to inject by the names of a
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packages' lambda attrset pattern names. Some packages alias these with
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`@args` to pass them to another `import ...nix args`.
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As the used args are only named in the imported file they will be
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recognized as dead in the package source file that is imported by
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`callPackage`, rendering it unable to guess the dependencies to call
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the packages with.
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Use option `--no-lambda-pattern-names` in this case.
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## What if the produced reports are wrong?
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Please open an issue. Do not forget to include the `.nix` code that
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produces incorrect results.
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## Commercial Support
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The author can be hired to implement the features that you wish, or to
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integrate this tool into your toolchain.
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