bug#54003: local-file after Guile update

[Liliana Marie Prikler]

Hi Aleksandr

Am Montag, dem 14.02.2022 um 21:50 +0000 schrieb Aleksandr Vityazev:
> Hi,
> 
> I have the following dotfiles directory structure where I store my
> Guix home config:
> 
> > -etc
> > 
> > -subdir
> >   |
> >   |-home
> 
> 
> I often use the 'local-file' procedure in modules in the home
> directory. For example in /subdir/home/shells.scm:
> 
> #+begin_src scheme :scheme guile :season guile
> (simple-service 'add-zsh-files
>                 home-files-service-type
>                 `(("config/zsh/zshrc"
>                    ,(local-file "../../etc/zsh/zshrc"))))
> #+end_src
> And it works, as expected.
Be careful when invoking Hyrum's Law.  The meaning of this local-file
expression changes with the current working directory, which might be
different across invocations.  To avoid such issues, you can (almost?)
always use (current-file-name), which you might want to canonicalize
for the operations you're about to do.
Taking (dirname) thrice then brings you to $GUIX_HOME_CONFIG_ROOT,
which contains both etc and subdir.

> The following example also worked before the
> 076e825dc5d585943ce820a279fffe4af09757fb (gnu: guile: Add version
> 3.0.8 as
> 'guile-3.0-latest') commit.
> 
> in /subdir/home/wm.scm: 
> #+begin_src scheme :scheme guile :season guile
> (service
>  home-rofi-service-type
>  (home-rofi-configuration
>   (config-rasi
>    `(,#~(format
>          #f "@theme \"~a\""
>          #$(local-file "../../etc/rofi/nord.rasi"))))))
> #+end_src
> 
> After 076e825dc5d585943ce820a279fffe4af09757fb
> using (local-file "../../etc/rofi/nord.rasi") and not
> (local-file "etc/rofi/nord.rasi") causes an error:
> 
> guix home: error: canonicalize-path: No such file or
> directory: "../../etc/rofi/nord.rasi".
> 
> The example that causes the error uses the original Guix home
> implementation, which uses gexps.  When I figure out how to make a
> minimal reproducer that does not depend on it, I will update this
> report.
I don't think this is an issue particularly in Guix Home, but for a MWE
you could try only writing a bashrc, which ought to work with upstream
as well.  Use `guix home build` rather than `guix home reconfigure` so
as to not activate it.

Cheers