Subject: [bug#61322] [PATCH] status: Print a hint when a 'package-cache' hook fails to build.

From: Ludovic Courtès <[email-masked]>
Date: Mon, 6 Feb 2023 15:13:52 +0100

* guix/channels.scm (package-cache-file): Add 'channels' to the #:properties
list.
* guix/status.scm (print-build-event): Upon failure, display a hint when
the derivation is a 'package-cache' hook.
---
 guix/channels.scm |  9 +++++++--
 guix/status.scm   | 18 +++++++++++++++++-
 2 files changed, 24 insertions(+), 3 deletions(-)

Hello!

This patch mitigates a longstanding user interface issue.  When pulling
from a channel set where one of them has an issue, such as a reference to
an unbound variable, you get something rather unhelpful like this:

--8<---------------cut here---------------start------------->8---
$ guix pull -C ~/.config/guix/hpc-channels.scm -p /tmp/chantest
Updating channel 'guix-hpc' from Git repository at 'https://gitlab.inria.fr/guix-hpc/guix-hpc.git'...
Updating channel 'guix' from Git repository at 'https://git.savannah.gnu.org/git/guix.git'...
Authenticating channel 'guix', commits 9edb3f6 to a582d86 (64 new commits)...
Building from these channels:
  guix      https://git.savannah.gnu.org/git/guix.git	a582d86
  guix-hpc  https://gitlab.inria.fr/guix-hpc/guix-hpc.git	0e522d1

[...]

 guix-daemon  399B                               205KiB/s 00:00 [##################] 100.0%
 guix-a582d8634  14KiB                           1.2MiB/s 00:00 [##################] 100.0%
building /gnu/store/c4racwl5ns6vpyjsx1ad3fxh9n48g0pl-guix-hpc.drv...
building CA certificate bundle...
listing Emacs sub-directories...
building fonts directory...
building directory of Info manuals...
building profile with 2 packages...
building /gnu/store/p2a500wi4nvznq85sf08jych48lpfijl-inferior-script.scm.drv...
building package cache...
\builder for `/gnu/store/pm5crwjcclblmdh8y15jk6i5wxml6j9g-guix-package-cache.drv' failed to produce output path `/gnu/store/12x6ka57amgv28rdnkc2wsq3hs8gr6gw-guix-package-cache'
build of /gnu/store/pm5crwjcclblmdh8y15jk6i5wxml6j9g-guix-package-cache.drv failed
View build log at '/var/log/guix/drvs/pm/5crwjcclblmdh8y15jk6i5wxml6j9g-guix-package-cache.drv.gz'.
cannot build derivation `/gnu/store/06d4wla2l7qqldcaxif2qzgpsk377hvr-profile.drv': 1 dependencies couldn't be built
guix pull: error: build of `/gnu/store/06d4wla2l7qqldcaxif2qzgpsk377hvr-profile.drv' failed
--8<---------------cut here---------------end--------------->8---

In this case the relevant bit in the build log is:

--8<---------------cut here---------------start------------->8---
In inria/hiepacs.scm:
   879:41  3 (inputs #<package [email-masked] inria/hi?>)
In ice-9/boot-9.scm:
  1685:16  2 (raise-exception _ #:continuable? _)
  1780:13  1 (_ #<&compound-exception components: (#<&undefined-vari?>)
In unknown file:
           0 (backtrace #<undefined>)

(exception unbound-variable (value #f) (value "Unbound variable: ~S") (value (python2-numpy)) (value #f))
--8<---------------cut here---------------end--------------->8---

We probably cannot reliably “extract” the actual error from the build
log, but we can at least hint in the right direction.  This is what
this patch does.  Now you would get:

--8<---------------cut here---------------start------------->8---
build of /gnu/store/dib9aa6g0zn3cvv7hvfrby7cnmpyrw2m-guix-package-cache.drv failed
hint: This usually indicates a bug in one of the channels you are pulling from, or some
incompatibility among them.  You can check the build log and report the issue to the
channel developers.

The channels you are pulling from are: guix guix-hpc.

View build log at '/var/log/guix/drvs/di/b9aa6g0zn3cvv7hvfrby7cnmpyrw2m-guix-package-cache.drv.gz'.
cannot build derivation `/gnu/store/y11nksh5lhyj09zqszlg9pvg89wzpv5p-profile.drv': 1 dependencies couldn't be built
guix build: error: build of `/gnu/store/y11nksh5lhyj09zqszlg9pvg89wzpv5p-profile.drv' failed
--8<---------------cut here---------------end--------------->8---

Thoughts?

Ludo’.

diff --git a/guix/channels.scm b/guix/channels.scm
index 40cbc4bb3a..d44e7a0a3a 100644
--- a/guix/channels.scm
+++ b/guix/channels.scm
@@ -952,6 +952,10 @@ (define build
                       (backtrace))))
               (mkdir #$output))))
 
+    (define channels
+      (map (compose string->symbol manifest-entry-name)
+           (manifest-entries manifest)))
+
     (gexp->derivation-in-inferior "guix-package-cache" build
                                   profile
 
@@ -960,8 +964,9 @@ (define build
                                   ;; instead of failing.
                                   #:silent-failure? #t
 
-                                  #:properties '((type . profile-hook)
-                                                 (hook . package-cache))
+                                  #:properties `((type . profile-hook)
+                                                 (hook . package-cache)
+                                                 (channels . ,channels))
                                   #:local-build? #t)))
 
 (define %channel-profile-hooks
diff --git a/guix/status.scm b/guix/status.scm
index 2c69f49fb5..5580c80ea9 100644
--- a/guix/status.scm
+++ b/guix/status.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2017-2022 Ludovic Courtès <[email-masked]>
+;;; Copyright © 2017-2023 Ludovic Courtès <[email-masked]>
 ;;; Copyright © 2018, 2019 Ricardo Wurmus <[email-masked]>
 ;;;
 ;;; This file is part of GNU Guix.
@@ -22,6 +22,7 @@ (define-module (guix status)
   #:use-module (guix i18n)
   #:use-module (guix colors)
   #:use-module (guix progress)
+  #:autoload   (guix ui) (display-hint)
   #:autoload   (guix build syscalls) (terminal-columns)
   #:autoload   (guix build download) (nar-uri-abbreviation)
   #:use-module (guix store)
@@ -526,6 +527,21 @@ (define erase-current-line*
      (erase-current-line*)                      ;erase spinner or progress bar
      (format port (failure (G_ "build of ~a failed")) drv)
      (newline port)
+     (let ((properties (and=> (false-if-exception
+                               (read-derivation-from-file drv))
+                              derivation-properties)))
+       (when (and (pair? properties)
+                  (eq? (assq-ref properties 'type) 'profile-hook)
+                  (eq? (assq-ref properties 'hook) 'package-cache))
+         (display-hint (format #f (G_ "This usually indicates a bug in one of
+the channels you are pulling from, or some incompatibility among them.  You
+can check the build log and report the issue to the channel developers.
+
+The channels you are pulling from are: ~a.")
+                               (string-join
+                                (map symbol->string
+                                     (or (assq-ref properties 'channels)
+                                         '(guix))))))))
      (match (derivation-log-file drv)
        (#f
         (format port (failure (G_ "Could not find build log for '~a'."))

base-commit: 25947bbc3217306742694304fa9b6499f0126c7a
-- 
2.39.1