bug#22138: Search paths of dependencies are not honored

[Mark H Weaver <mhw@netris.org>]

Hi Julien,

Julien Lepiller <julien@lepiller.eu> writes:

> Hi, I've been looking at our current code and would like to propose the
> attached patch for that issue.
>
> From cfd2c229087166ab4cc0a9e2bdb72c8b393bcdd5 Mon Sep 17 00:00:00 2001
> From: Julien Lepiller <julien@lepiller.eu>
> Date: Thu, 1 Aug 2019 22:09:38 +0200
> Subject: [PATCH] guix: Recursively honor search paths of dependencies.
>
> * guix/packages.scm (all-transitive-inputs)
> (package-all-transitive-inputs)
> (package-all-transitive-native-search-paths): New procedures.
> * guix/profiles.scm (package->manifest-entry): Use
> package-all-transitive-native-search-paths to generate manifest search
> paths.

As I recall this kind of solution has been proposed in the past and
rejected.  It's a reasonable suggestion, but I personally think that it
goes too far, because it would include a great many packages whose code
is nowhere to be found in the resulting profile.  For example, it would
include documentation generators used to build man pages, and the
compilers that were used to build those documentation generators, etc,
all the way back to the early bootstrap binaries.

Having said this, I agree that there is a longstanding problem in Guix
with search-paths not including enough packages in its calculation.
We've known about this problem for a long time, but as far as I know we
have not yet found a satisfactory solution.

Our current hacky workaround for problems like this has been to set
certain environment variables unconditionally in /etc/profile.  For
example, you'll see that MANPATH, INFOPATH, XDG_DATA_DIRS,
XDG_CONFIG_DIRS, XCURSOR_PATH, DICPATH, and GST_PLUGIN_PATH are all set
there.  See 'operating-system-etc-service' in (gnu system) for the
relevant code.

At the very least, I think we should wait for input from Ludovic before
applying anything along these lines.

Anyway, thanks for looking into it and making the proposal.

      Best,
       Mark