02/02: doc: Mention how to remedy "source file ... newer than compiled error".

[guix-commits]

ngz pushed a commit to branch master
in repository guix.

commit 2f21931833274fb4760cb82203495fab5991877f
Author: Guix Together <jgart@dismail.de>
AuthorDate: Thu Dec 16 01:46:50 2021 -0500

    doc: Mention how to remedy "source file ... newer than compiled error".
    
    * doc/contributing.texi (Running Guix Before It Is Installed): Mention
    how to remedy "source file ... newer than compiled" error by running
    `make -j`.
    
    Co-authored-by: jgart <jgart@dismail.de>
    Co-authored-by: Julien Lepiller <julien@lepiller.eu>
    Co-authored-by: Ryan Prior <rprior@protonmail.com>
    Co-authored-by: Blake Shaw <blake@nonconstructivism.com>
    Signed-off-by: Nicolas Goaziou <mail@nicolasgoaziou.fr>
---
 doc/contributing.texi | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/doc/contributing.texi b/doc/contributing.texi
index f258d79bd2..196ac48879 100644
--- a/doc/contributing.texi
+++ b/doc/contributing.texi
@@ -243,6 +243,24 @@ local source tree; it simply updates the 
@file{~/.config/guix/current}
 symlink (@pxref{Invoking guix pull}).  Run @command{git pull} instead if
 you want to upgrade your local source tree.
 
+Sometimes, especially if you have recently updated your repository,
+running @command{./pre-inst-env} will print a message similar to the
+following example:
+
+@example
+;;; note: source file /home/user/projects/guix/guix/progress.scm
+;;;       newer than compiled /home/user/projects/guix/guix/progress.go
+@end example
+
+This is only a note and you can safely ignore it.  You can get rid of
+the message by running @command{make -j4}.  Until you do, Guile will run
+slightly slower because it will interpret the code instead of using
+prepared Guile object (@file{.go}) files.
+
+You can run @command{make} automatically as you work using
+@command{watchexec} from the @code{watchexec} package.  For example,
+to build again each time you update a package file, you can run
+@samp{watchexec -w gnu/packages make -j4}.
 
 @node The Perfect Setup
 @section The Perfect Setup