NixOS manual: docbook schema configuration uses missing path

[jmitchell]

Issue description

While following the instructions in the manual to support DocBook 5 XML editing in Emacs I discovered the recommended schema configuration doesn't work when docbook5 is installed via environment.systemPackages. Specifically, /run/current-system/sw/share/xml/docbook-5.0/rng/docbookxi.rnc doesn't exist.

Steps to reproduce

1. add docbook5 to environment.systemPackages in /etc/nixos/configuration.nix
2. run nixos-rebuild switch
3. add (add-to-list 'rng-schema-locating-files "~/.emacs.d/schemas.xml") to Emacs configuration
4. write the following to ~/.emacs.d/schemas.xml

<?xml version="1.0"?>
<locatingRules xmlns="http://thaiopensource.com/ns/locating-rules/1.0">
  <namespace ns="http://docbook.org/ns/docbook"
             uri="/run/current-system/sw/share/xml/docbook-5.0/rng/docbookxi.rnc"/>
</locatingRules>

5. open $NIXPKGS/doc/manual.xml in Emacs.
6. go to *Messages* buffer and see the following error:

File mode specification error: (file-error Opening input file No such file or directory /run/current-system/sw/share/xml/docbook-5.0/rng/docbookxi.rnc)

7. notice that /run/current-system/sw/share has no xml directory.

Workaround

Use the other suggested approach where docbook5 is installed ad-hoc and the docbookxi.rnc path in the schemas.xml points to user profile instead.

Technical details

• System: 17.03.945.5acb454e2a (Gorilla)
• Nix version: nix-env (Nix) 1.11.8
• Nixpkgs version: "17.03.945.5acb454e2a"

[rvl]

I have the file /run/current-system/sw/share/xml/docbook-5.0/rng/docbookxi.rnc.

When I remove pkgs.docbook5 from environment.systemPackages and nixos-rebuild switch, the directory /run/current-system/sw/share/xml/docbook-5.0 disappears.

Is docbook5 in the list when you run nixos-option environment.systemPackages | grep --color docbook5?

[jmitchell]

Is docbook5 in the list when you run nixos-option environment.systemPackages | grep --color docbook5?

Yes, but even so the /run/current-system/sw/share directory still has no xml directory. Steps to ensure my environment is properly cleaned and set up to have docbook5 in the configured system packages.

1. nix-env -e docbook5
2. removed pkgs.docbook5 from environment.systemPackages
3. nix-collect-garbage
4. confirmed your suggested command returns nothing
5. added pkgs.docbook5 back to configured environment.systemPackages and run nixos-rebuild switch
6. ran your command again and saw "/nix/store/vv6pg515z9n70drggdpc9h04aw6zmlv5-docbook5-5.0" in the output
7. confirmed "/nix/store/vv6pg515z9n70drggdpc9h04aw6zmlv5-docbook5-5.0/share/xml/docbook-5.0/rng/docbookxi.rnc exists, but /run/current-system/sw/share/xml doesn't.

[rvl]

Hi @jmitchell, Just checking, do you now have /run/current-system/sw/share/xml/docbook-5.0 if pkgs.docbook5 is in environment.systemPackages?

[jtojnar]

I would suspect that this only works for some users because some module puts /share into their environment.pathsToLink. I believe this kind of carpet bombing is not correct, see #47173.

Instead of setting global paths in you profile, I would recommend to follow the suggestion in https://github.com/NixOS/nix-pills#development, along with a simplified config from #68236

[stale]

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[pennae]

docbook is no longer used for the manuals :)