bug#26877: building fonts: fontcache must be updated regulary

[ng0 <ng0@pragmatique.xyz>]

Mark H Weaver transcribed 1.2K bytes:
> ng0 <ng0@pragmatique.xyz> writes:
> 
> > The problem: Right now after just installing fonts, they do
> > not become available. This can lead to some applications
> > appearing "broken", etc. Other operating systems solve this
> > by having a post-install hook which roughly does just this.
> >
> > A possible solution:
> > Our fictional, not yet existing, font-build-system should
> > run "fc-cache --force --really-force",
> 
> This cannot work, because the build system code is run within the build
> container, where it won't have access to anything in your home
> directory.  Furthermore, for most users, the packages are built on
> another machine, namely one of our build farm slaves.
> 
> Even the build system did somehow have access to your home directory,
> building the package is not the right time to run "fc-cache".  On a
> multiuser system, if two users request the same derivation, it is only
> built for the first user, and the second user simply uses the one that
> the first user built.  The relevant time to run "fc-cache" is when the
> font is _installed_ in your user profile.
> 
> The usual Guix way to handle things like this is to arrange for the font
> cache to be part of the profile, and to create a profile hook that
> creates the cache from all of the built packages included within.
> 
>        Mark
> 

Okay, you are right about the build system. Your approach reads
better, I was just looking for a way to start a discussion on
this. Right now it is not-obviously broken, and we need to fix
it at some point.
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