[bug#74425] [PATCH] ui: Include channels in load path before searching for commands.

[Carlo Zancanaro <carlo@zancanaro.id.au>]

* guix/ui.scm (extension-directories): Add channel directories to load path,
compiled load path, and returned list of directories.

Co-authored-by: Ludovic Courtès <ludo@gnu.org>
Change-Id: I3063cbf7164a065b2c6c2a5c6473df79ce8cbe9b
---

This patch allows extensions in channels to be found by the Guix
CLI. Most notably, this means that a script can define commands by
defining an appropriate (guix scripts X) module, with a guix-X
function.

This is a slight modification to a diff that Ludovic sent through IRC.

I've tested that it works when I use "guix time-machine". Guix is able
to find a command that I define in a channel.

I haven't specifically tested that it finds commands when run through
"guix pull", but I have tested that this change does not break "guix
pull".

 guix/ui.scm | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/guix/ui.scm b/guix/ui.scm
index 447550635c..a702b6f3f8 100644
--- a/guix/ui.scm
+++ b/guix/ui.scm
@@ -19,6 +19,7 @@
 ;;; Copyright © 2018 Steve Sprang <scs@stevesprang.com>
 ;;; Copyright © 2022 Taiju HIGASHI <higashi@taiju.info>
 ;;; Copyright © 2022 Liliana Marie Prikler <liliana.prikler@gmail.com>
+;;; Copyright © 2024 Carlo Zancanaro <carlo@zancanaro.id.au>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -73,6 +74,7 @@ (define-module (guix ui)                       ;import in user interfaces only
   #:use-module (srfi srfi-31)
   #:use-module (srfi srfi-34)
   #:use-module (srfi srfi-35)
+  #:use-module (srfi srfi-71)
   #:autoload   (ice-9 ftw)  (scandir)
   #:use-module (ice-9 match)
   #:use-module (ice-9 format)
@@ -2192,9 +2194,16 @@ (define* (command-files #:optional directory)
 
 (define (extension-directories)
   "Return the list of directories containing Guix extensions."
-  (filter file-exists?
-          (parse-path
-           (getenv "GUIX_EXTENSIONS_PATH"))))
+  (define package-path-entries
+    ;; We need to resolve this lazily, because even using an #:autoload is too
+    ;; much and breaks compilation during "guix pull".
+    (module-ref (resolve-module `(guix describe))
+                (symbol-append 'package-path-entries)))
+  (let ((scm-path go-path (package-path-entries)))
+    (set! %load-path (append %load-path scm-path))
+    (set! %load-compiled-path (append %load-compiled-path go-path))
+    (filter file-exists?
+            (parse-path (getenv "GUIX_EXTENSIONS_PATH") scm-path))))
 
 (define (commands)
   "Return the list of commands, alphabetically sorted."

base-commit: 23cbbe6860782c5d4a0ba599ea1cda0642e91661
-- 
2.46.0