40/40: time-machine: Also validate the reference from a channels file.

[guix-commits]

apteryx pushed a commit to branch master
in repository guix.

commit c3d48d024b95f57850ec429d7f326d817dda5090
Author: Maxim Cournoyer <maxim.cournoyer@gmail.com>
AuthorDate: Tue Sep 5 17:04:12 2023 -0400

    time-machine: Also validate the reference from a channels file.
    
    * guix/scripts/time-machine.scm (guix-time-machine)
    <validate-guix-channel>: Update doc.  Fall-back to use the Guix channel
    reference when REF is #f.
    
    Reported-by: Simon Tournier <zimon.toutoune@gmail.com>
    Co-authored-by: Simon Tournier <zimon.toutoune@gmail.com>
---
 guix/scripts/time-machine.scm | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/guix/scripts/time-machine.scm b/guix/scripts/time-machine.scm
index 87000d82ec..3ecf735acb 100644
--- a/guix/scripts/time-machine.scm
+++ b/guix/scripts/time-machine.scm
@@ -164,13 +164,20 @@ Execute COMMAND ARGS... in an older version of Guix.\n"))
        (define (validate-guix-channel channels)
          "Finds the Guix channel among CHANNELS, and validates that REF as
 captured from the closure, a git reference specification such as a commit hash
-or tag associated to CHANNEL, is valid and new enough to satisfy the 'guix
-time-machine' requirements.  A `formatted-message' condition is raised
-otherwise."
+or tag associated to the channel, is valid and new enough to satisfy the 'guix
+time-machine' requirements.  If the captured REF variable is #f, the reference
+validate is the one of the Guix channel found in CHANNELS.  A
+`formatted-message' condition is raised otherwise."
          (let* ((guix-channel (find guix-channel? channels))
+                (guix-channel-commit (channel-commit guix-channel))
+                (guix-channel-branch (channel-branch guix-channel))
+                (guix-channel-ref (if guix-channel-commit
+                                      `(tag-or-commit . ,guix-channel-commit)
+                                      `(branch . ,guix-channel-branch)))
+                (reference (or ref guix-channel-ref))
                 (checkout commit relation (update-cached-checkout
                                            (channel-url guix-channel)
-                                           #:ref (or ref '())
+                                           #:ref reference
                                            #:starting-commit
                                            %oldest-possible-commit)))
            (unless (memq relation '(ancestor self))