bug#31841: ./pre-inst-env guix system no longer works without ~/.config/guix

[Ludovic Courtès]

Hello,

address@hidden skribis:

> Based on this thread I am now making guix like this ...
>
> guix environment guix --ad-hoc guile-sqlite3 --root=build-env -- make 
> [MAKECMDGOALS]
>
> ... and using it like this ...
>
> source build-env/etc/profile
> ./pre-inst-env guix COMMAND ARGS...

Yeah we can improve the doc.  Currently, “Building from Git” mentions
‘guix environment guix’, but “Running Guix Before It Is Installed”
doesn’t.  How about this:

diff --git a/doc/contributing.texi b/doc/contributing.texi
index 205c972ae..3f82f4bc2 100644
--- a/doc/contributing.texi
+++ b/doc/contributing.texi
@@ -108,7 +108,9 @@ actually installing them.  So that you can distinguish 
between your
 ``end-user'' hat and your ``motley'' costume.
 
 To that end, all the command-line tools can be used even if you have not
-run @code{make install}.  To do that, prefix each command with
+run @code{make install}.  To do that, you first need to have an environment
+with all the dependencies available (@pxref{Building from Git}), and then
+simply prefix each command with
 @command{./pre-inst-env} (the @file{pre-inst-env} script lives in the
 top build tree of Guix), as address@hidden @option{-E} flag to
 @command{sudo} guarantees that @code{GUILE_LOAD_PATH} is correctly set

Note that I purposely did not mention “--ad-hoc guile-sqlite3” because
it has become unnecessary with commit
c5a2e1ffcb029f50c4c18352cf378b61c41c625e.

Likewise, I did not mention “source build-env/etc/profile” because
“Building from Git” suggests using ‘guix environment guix’, which sets
up the right environment variables.

WDYT?

Ludo’.