Update anchor to `recursive sets` in nix manual.

[wathiede]

[nlewo]

Do you know how the recursive set ID is generated in the Nix manual? I'm not sure this ID is actually stable. Maybe we should first explicitly set this anchor in the Nix manual.

[jtojnar]

Yeah, it is non-deterministic. And Nix manual has been ported to Markdown so all links will be broken now anyway :scream_cat:

[wathiede]

Is the version live at https://nixos.org/manual/nix/stable/ the 'ported to Markdown' version, or an 'old' version?

I ran https://github.com/linkchecker/linkchecker and pointed it to https://nixos.org/manual/nix/stable/ with the following config:

[output]
status=1
fileoutput = text,csv 
[text]
filename=linkchecker-out.txt
[gml]
[dot]
[csv]
filename=linkchecker-out.csv
[sql]
[html]
[blacklist]
[xml]
[gxml]
[sitemap]
[checking]
[filtering]
checkextern=1
[authentication]
[AnchorCheck]

It reports 44 broken links/anchors, which isn't too bad. If the version live at https://nixos.org/manual/nix/stable/ is the markdown version, I'm happy to submit some PRs to https://github.com/NixOS/nix to add stable anchors to the things currently pointing to unstable anchors, and clean up all the rest (it looks like there's a number of links that go through a redirect from /nixpkgs/manual/ to /manual/nixpgs/stable/ and linkchecker doesn't like this).

This PR started as something I saw broken while reading through the pills, but I'm happy to do the larger cleanup if you want.

If the markdown version isn't what is live at https://nixos.org/manual/nix/stable/ then maybe there's a much bigger breakage coming, and I'll leave that cleanup to whomever is rolling out the port to markdown.

[jtojnar]

https://github.com/NixOS/nix/pull/3857 has only been merged recently so it is not available on the website AFAIK. Unfortunately it will break all links.

[wathiede]

Ok, sounds like this change isn't very useful. Thanks for the additional context and link.

[jtojnar]

Perhaps we should point it to the unstable manual: https://nixos.org/manual/nix/unstable/expressions/language-constructs.html#recursive-sets