Dependence on an old version of a package.

[Philippe Veber <philippe.veber@gmail.com>]

Hi all and sorry if it's a FAQ !

I would like to write a package definition for a program that expects
openmpi < 4.0.0, which is present in earlier versions of guix. If I'm not
mistaken I have to use inferiors in that case, and I tried this :

(use-modules (gnu packages mpi)
    (guix packages)
             (guix download)
             (guix build-system gnu)
             (guix licenses)
    (guix build utils)
    (guix gexp)
    (guix inferior)
    (guix channels))

(define mychannels
  (list (channel
         (name 'guix)
         (url "https://git.savannah.gnu.org/git/guix.git")
         ;; Last commit that still has openmpi < 4.0.0
         (commit
          "1482531cd7d0f1f7e565207240affb68dd822e17"))))

(define myinferior
  (inferior-for-channels mychannels))

(define myopenmpi
  (first (lookup-inferior-packages myinferior "openmpi")))

(package
 (name "coevol")
 (version "1.5b")
 (source (origin
 (method url-fetch)
 (uri (string-append "
https://github.com/bayesiancook/coevol/archive/refs/tags/v" version
".tar.gz"))
 (sha256 (base32 "112kjjxwlm9m3f3wks3q86gp561l8s5gsw17zrffrhljixd8qyyp"))))
 (build-system gnu-build-system)
 (arguments
  (list
   #:phases #~(modify-phases %standard-phases
    (delete 'configure)
    (add-after 'unpack 'chdir (lambda _ (chdir "sources") #t)))))
 (inputs (list myopenmpi))
 (synopsis "Correlated evolution of substitution rates and quantitative
traits")
 (description "...")
 (home-page "
https://megasun.bch.umontreal.ca/People/lartillot/www/downloadcoevol.html")
 (license gpl3+))

My problem is that when invoking guix I get this:

$ guix package --install-from-file=coevol.scm
Mise à jour du canal « guix » depuis le dépôt Git «
https://git.savannah.gnu.org/git/guix.git »...
Computing Guix derivation for 'x86_64-linux'... \fetching path
`/gnu/store/ir3092v7657h6g4g2vlsw3zrli3rndb3-zlib-1.2.11.tar.gz'...
substitute: updating substitutes from 'https://ci.guix.gnu.org'... 100.0%
substitute: updating substitutes from 'https://ci.guix.gnu.org'... 100.0%

and a spinning character for more than 10 hours. I can see a 'guix
substitute' process working and using quite some memory after a while (3-4
GB). My question is this: should I just be patient and wait for it to
complete or I'm doing this wrong?

Thanks for any hint!
  Philippe.