Add NixOS installation method to doc

[schalkms]

No description provided.

[codecov]

Codecov Report

Merging #5757 (df04a86) into main (488d0b8) will decrease coverage by 0.05%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##               main    #5757      +/-   ##
============================================
- Coverage     84.52%   84.48%   -0.05%     
- Complexity     3731     3742      +11     
============================================
  Files           544      546       +2     
  Lines         12759    12791      +32     
  Branches       2232     2233       +1     
============================================
+ Hits          10785    10806      +21     
- Misses          864      869       +5     
- Partials       1110     1116       +6     

Impacted Files	Coverage Δ
...turbosch/detekt/rules/style/UnusedPrivateMember.kt	92.22% <0.00%> (-0.64%)	⬇️
...in/kotlin/io/github/detekt/report/xml/XmlEscape.kt	65.97% <0.00%> (ø)
.../arturbosch/detekt/core/util/PerformanceMonitor.kt	85.71% <0.00%> (ø)
...rturbosch/detekt/rules/style/StyleGuideProvider.kt	100.00% <0.00%> (ø)
...h/detekt/core/baseline/IndentingXMLStreamWriter.kt	56.33% <0.00%> (ø)
...rbosch/detekt/rules/style/UnusedPrivateProperty.kt	92.72% <0.00%> (ø)
...b/arturbosch/detekt/rules/style/UnusedParameter.kt	77.35% <0.00%> (ø)

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[3flex]

I'm not familiar with Nix - does the hash in the filename have to be updated with every detekt release? If so, is there a way to remove that from this command, because having to update this for every release may be a bit of a hassle.

[schalkms]

I just saw on Slack in our #detekt channel that @mdr added detekt as a nix package.
@mdr do you know whether the hash has to be updated with each and every detekt release?

[mdr]

@mdr do you know whether the hash has to be updated with each and every detekt release?

(With the caveat I'm a Nix beginner!) Yes - if you specify a specific revision as above then you'd always get the same version of Detekt, so you'd have to update to get a more recent version of Detekt. You can just reference the detekt package unqualified, e.g. with nix-shell -p detekt - and then you'll get the Detekt version associated with the Nix channel you're using. If you're using the stable channel, that might be a few months out of date (and right now, detekt is too new to be in a stable Nix channel).

[schalkms]

Okay, then I'll change the script in the docs to be more generic, like this.

nixpkgs=https://github.com/NixOS/nixpkgs/archive/[hash].tar.gz

[3flex]

I guess at some point when it's in stable channel we can simplify the command. But this is good in the meantime.

Where do people get the hash though? Is there a link we can include in the instructions?

[mdr]

You can grab a commit hash from the Nix status page (for the nixpkgs-unstable channel). It does feel kinda awkward - I don't know if there's a way you can directly reference the latest nixpkgs-unstable channel directly in the command.

[mdr]

If you have added the unstable channel via nix-channel, you can run: nix-shell -I nixpkgs=channel:nixpkgs-unstable -p detekt

[cortinico]

I've backported it here #5776