Subject: Re: bug#64746: [PATCH 2/2] scripts: time-machine: Error when attempting to visit too old commits.

From: Maxim Cournoyer <[email-masked]>
Date: Fri, 21 Jul 2023 22:00:18 -0400

Hello,

Maxim Cournoyer <[email-masked]> writes:

> * doc/guix.texi (Invoking guix time-machine): Document limitation.
> * guix/scripts/time-machine.scm (%oldest-possible-commit): New variable.
> (guix-time-machine): Raise an error when the channel commit is too old.
>
> Suggested-by: Simon Tournier <[email-masked]>
> ---
>  doc/guix.texi                 |  6 ++++++
>  guix/scripts/time-machine.scm | 23 ++++++++++++++++++++++-
>  2 files changed, 28 insertions(+), 1 deletion(-)
>
> diff --git a/doc/guix.texi b/doc/guix.texi
> index 1d8ebcd72f..30fef813c0 100644
> --- a/doc/guix.texi
> +++ b/doc/guix.texi
> @@ -5056,6 +5056,12 @@ Invoking guix time-machine
>  large number of packages; the result is cached though and subsequent
>  commands targeting the same commit are almost instantaneous.
>  
> +Due to @command{guix time-machine} relying on the ``inferiors''
> +mechanism (@pxref{Inferiors}), the oldest commit it can travel to is
> +commit @samp{2ca299caf} (``Add (guix inferior) and (guix scripts
> +repl).''), dated July 10@sup{th}, 2018.  An error is returned when
> +attempting to navigate to older commits.
> +
>  @quotation Note
>  The history of Guix is immutable and @command{guix time-machine}
>  provides the exact same software as they are in a specific Guix
> diff --git a/guix/scripts/time-machine.scm b/guix/scripts/time-machine.scm
> index d7c71ef705..36a40a1538 100644
> --- a/guix/scripts/time-machine.scm
> +++ b/guix/scripts/time-machine.scm
> @@ -2,6 +2,7 @@
>  ;;; Copyright © 2019 Konrad Hinsen <[email-masked]>
>  ;;; Copyright © 2019, 2020, 2021 Ludovic Courtès <[email-masked]>
>  ;;; Copyright © 2021 Simon Tournier <[email-masked]>
> +;;; Copyright © 2023 Maxim Cournoyer <[email-masked]>
>  ;;;
>  ;;; This file is part of GNU Guix.
>  ;;;
> @@ -19,13 +20,15 @@
>  ;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
>  
>  (define-module (guix scripts time-machine)
> +  #:use-module (guix channels)
> +  #:use-module (guix diagnostics)
>    #:use-module (guix ui)
>    #:use-module (guix scripts)
>    #:use-module (guix inferior)
>    #:use-module (guix store)
>    #:use-module (guix status)
>    #:use-module ((guix git)
> -                #:select (with-git-error-handling))
> +                #:select (update-cached-checkout with-git-error-handling))
>    #:use-module ((guix utils)
>                  #:select (%current-system))
>    #:use-module ((guix scripts pull)
> @@ -38,9 +41,16 @@ (define-module (guix scripts time-machine)
>    #:use-module (srfi srfi-1)
>    #:use-module (srfi srfi-11)
>    #:use-module (srfi srfi-26)
> +  #:use-module (srfi srfi-34)
>    #:use-module (srfi srfi-37)
> +  #:use-module (srfi srfi-71)
>    #:export (guix-time-machine))
>  
> +;;; The commit introducing the 'inferiors' mechanism; it is the oldest commit
> +;;; that can be travelled to.
> +(define %oldest-possible-commit
> +  "2ca299caf64489f4e1e665ec1158fb0309b0b565")

I just tried travelling to that assumed oldest commit (because it
corresponds to the introduction of the inferiors mechanism), but it
fails like:

--8<---------------cut here---------------start------------->8---
Computing Guix derivation for 'x86_64-linux'...  Backtrace:
-           5 (primitive-load "/gnu/store/b70mihsj9xx0xxp6izliqb5vm4…")
In ice-9/eval.scm:
    155:9  4 (_ _)
    159:9  3 (_ #(#(#(#(#(#(#(#(#(#(#(…) …) …) …) …) …) …) …) …) …) …))
   173:47  2 (_ #(#(#(#(#(#(#(#(#(#(#(…) …) …) …) …) …) …) …) …) …) …))
In ./guix/self.scm:
    932:4  1 (guix-derivation "/gnu/store/yfn2s94i5bvwr7j7r6xcnivwg…" …)
    903:2  0 (guile-for-build "3.0")

./guix/self.scm:903:2: In procedure guile-for-build:
Throw to key `match-error' with args `("match" "no matching pattern" "3.0")'.
Backtrace:
In ice-9/boot-9.scm:
  1752:10 19 (with-exception-handler _ _ #:unwind? _ # _)
In guix/store.scm:
   659:37 18 (thunk)
In guix/status.scm:
    839:4 17 (call-with-status-report _ _)
In guix/store.scm:
   1298:8 16 (call-with-build-handler #<procedure 7ff1daabfd20 at g…> …)
In guix/monads.scm:
    576:2 15 (run-with-store #<store-connection 256.99 7ff1dab842d0> …)
In guix/inferior.scm:
    927:8 14 (_ _)
In guix/channels.scm:
    982:2 13 (_ _)
    924:2 12 (_ _)
In guix/store.scm:
   1883:0 11 (_ _)
   1996:8 10 (_ _)
In guix/channels.scm:
   675:14  9 (_ #<store-connection 256.99 7ff1dab842d0>)
In guix/monads.scm:
    576:2  8 (run-with-store #<store-connection 256.99 7ff1dab842d0> …)
In guix/store.scm:
   1298:8  7 (call-with-build-handler _ _)
   1298:8  6 (call-with-build-handler #<procedure 7ff1db8108b8 at g…> …)
In guix/channels.scm:
   690:14  5 (_)
In guix/monads.scm:
    576:2  4 (run-with-store #<store-connection 256.99 7ff1dab842d0> …)
In ice-9/eval.scm:
   191:27  3 (_ #(#(#<directory (build-self) 7ff1da984aa0> #<pr…>) …))
In ice-9/boot-9.scm:
   2007:7  2 (error _ . _)
  1685:16  1 (raise-exception _ #:continuable? _)
  1685:16  0 (raise-exception _ #:continuable? _)

ice-9/boot-9.scm:1685:16: In procedure raise-exception:
invalid build result (#<derivation /gnu/store/rj2g4x23lqyaq16471qm94xp90slxp3h-compute-guix-derivation.drv => /gnu/store/b70mihsj9xx0xxp6izliqb5vm462yifl-compute-guix-derivation 7ff1d8b55000> "")
--8<---------------cut here---------------end--------------->8---

Is this a bug or expected?

-- 
Thanks,
Maxim