add mutable shortlinks

[fricklerhandwerk]

closes #843

this allows mapping cleanly from the existing mutable links on nixos.org

[asymmetric]

• This needs a niv update, otherwise the build fails with:

Build finished. The HTML pages are in build/html.
installing
sed: can't read /nix/store/yabz0xx6iyd3h5ba6mv30g7gsjgyqhff-source/doc/manual/_redirects: No such file or directory
error: boost::bad_format_string: format-string is ill-formed

• The new links on this page are a 404

I'd be happy to pick this up if you're too busy atm.

[asymmetric]

Also, sorry for leaving a ❌ review on a draft, realized after the fact it could've just been a comment 😅

[fricklerhandwerk]

As mentioned in the top post, I let it rot waiting for an up-to-date Hydra build to happen. Otherwise we have to build Nix locally. If all versions are in the cache, I can update the pin.

[asymmetric]

@fricklerhandwerk I ran it locally and it took a few secs, so yes pretty sure they are.

[fricklerhandwerk]

Would be great if you can finish it, but otherwise I'll pick it up once I get back to it.

[DanielSidhion]

LGTM

[infinisil]

It still looks like Nix 2.13 needs to be built locally:

these 2 derivations will be built:
  /nix/store/kbfqff6b2ssqxvmg4hjkrmswg34x8nmy-nix-2.13.7.drv
  /nix/store/lgmy85cgivhxfl8f18yya6k794nvg1in-nix-dev.drv
these 2 paths will be fetched (3.16 MiB download, 65.83 MiB unpacked):
  /nix/store/qlzczyamb1dl0xprqlf57589w38nximq-nix-2.18.1-doc
  /nix/store/21krqgvbinpkh9rb41yx16ybkdcyajnh-nix-2.19.3-doc

[fricklerhandwerk]

I can reproduce with mkdir tmpstore; nix-build --store $PWD/tmpstore, but don't understand how that's possible.

https://hydra.nixos.org/eval/1803459 shows that the Hydra build succeeded, but it produces different store paths than the local evaluation:

/nix/store/w6dc6i4bi02f3xqpqknd6hppp99mxxm9-nix-2.13.7-debug
/nix/store/ki5j23x8ncimj2sx4bd8y9nr7a956xni-nix-2.13.7-dev
/nix/store/2pcpjixx8ar0wjrf4n3jp0m19vij8jk0-nix-2.13.7-doc
/nix/store/9jdq5q39kv2980z7gq3a7nmfk96wbvhp-nix-2.13.7

[infinisil]

@fricklerhandwerk I think I figured it out, and it's very cursed! Clearing the Nix cache makes it work for me:

mv ~/.cache/{nix,nix-broken}

And if that also works for you please comment in NixOS/nix#9905

Here's the details:

• For some reason, the flake-compat master tarball is marked as immutable in my fetcher cache, so it always used a version from like a year ago. I filed an issue for this here: Fetcher cache can end up marking mutable urls as immutable nix#9905
• At that point in time, flake-compat seemed to double-copy store paths, related is Importing a remote package using flake-compat is now broken edolstra/flake-compat#60
• But Hydra builds from Flakes, not flake-compat. While Flakes does have a problem causing double store imports, which I initially thought was the problem, that only happens for local source imports, which is not the case here.
• So this means, the Hydra builds only singly-import the source, but flake-compat doubly imports them, which is why it's two different derivations!
• And this isn't a problem with 2.16 because of Filter tests/nixos from source nix#8096, which started using lib.cleanSourceWith on self.outPath. And with flake-compat, self.outPath is provided by fetchGit: https://github.com/edolstra/flake-compat/blob/35bb57c0c8d8b62bbfd284272c928ceb64ddbde9/default.nix#L96. And because fetchGit doesn't compose with lib.cleanSourceWith, this causes a double store import, making it line up exactly with the double store from the old flake-compat, for entirely different reasons!
• Furthermore, starting with 2.15, flake-compat was getting pinned: add flake-compat to flake.nix and use sha256 in default.nix nix#7989

And here's the kicker, and this is a bit of speculation: You can't check that it works with --store because flake-compat does this on master, which triggers this issue: NixOS/nix#9852

[infinisil]

However, those curses are completely unrelated to this PR here, so this PR is looking good.

[fricklerhandwerk]

Wow, thanks a lot for digging into it. I had already slated to nix-diff my way in, but that would have been hopeless apparently. Holy $CURSE this is messed up.

Was addressed