Subject: [bug#43578] [PATCH 0/4] Rewriting implicit inputs with 'package-input-rewriting' & co.

From: zimoun <[email-masked]>
Date: Sat, 26 Sep 2020 00:38:03 +0200

Hi Ludo,

On Wed, 23 Sep 2020 at 18:12, Ludovic Courtès <[email-masked]> wrote:

> Concretely, the following commands had no effect thus far:
>
>   guix build python-itsdangerous --with-input=python=python2
>   guix build hello --with-input=gcc=gcc-toolchain@10
>
> In both cases, this is because the input we want to change is
> an implicit input.  This patch set fixes that, and it fixes
> <https://issues.guix.gnu.org/42156> as a side effect.

Maybe I am doing wrong and I miss something.

For example, I want to build the package ’emacs-helm’ –which does not
(directly) depends on the package ’emacs’– using the package
’emacs-next’ (changing the Emacs VM from 27 to 28 in this case).

--8<---------------cut here---------------start------------->8---
$ ./pre-inst-env guix build emacs emacs-next
/gnu/store/7kr0pg7gwhc31q4iq5vbnm5n99srhp84-emacs-next-28.0.50.1-0.2ea3466
/gnu/store/q3c6y4ccj3li5gfdcbyz24n466fnipp1-emacs-27.1

$ cat /tmp/manif.scm
(specifications->manifest '("emacs-helm"))

$ ./pre-inst-env guix build -m /tmp/manif.scm
/gnu/store/ka9lph0hpzaky0sa52zf09469apkhb68-emacs-helm-3.6.5

$ ./pre-inst-env guix build -m /tmp/manif.scm --with-input=emacs=emacs-next
/gnu/store/ka9lph0hpzaky0sa52zf09469apkhb68-emacs-helm-3.6.5
--8<---------------cut here---------------end--------------->8---

I miss why the hash is the same.  I was expecting a different one, as
with your ’hello’ example (that I reproduce exactly).  What do I miss?

Note it is the same with:

--8<---------------cut here---------------start------------->8---
$ ./pre-inst-env guix build emacs-helm --with-input=emacs=emacs-next
/gnu/store/ka9lph0hpzaky0sa52zf09469apkhb68-emacs-helm-3.6.5
--8<---------------cut here---------------end--------------->8---

Well, I am trying to provide an example to [1] because your patch set
supersedes it, somehow.

[1] <http://issues.guix.gnu.org/41732#7>

(I have not yet tried the build transformation at the manifest level.)

All the best,
simon