Subject: Re: [bug#36641] [PATCH] gnu: python-gst: Fix build failure.

From: Marius Bakke <[email-masked]>
Date: Sun, 14 Jul 2019 00:52:11 +0200

Christopher Baines <[email-masked]> writes:

> Building python-gst fails with:
>
>   Unbound variable: python-version
>
> Therefore, add python-build-system to #:modules so that it's imported, and
> give it a prefix to avoid clashing with the gnu-build-system.
>
> Also, simplify the code by using the site-packages function from the
> python-build-system module.
>
> * gnu/packages/gstreamer.scm (python-gst)[arguments]: Rework to fix build
> failure.
> ---
>  gnu/packages/gstreamer.scm | 15 ++++++---------
>  1 file changed, 6 insertions(+), 9 deletions(-)
>
> diff --git a/gnu/packages/gstreamer.scm b/gnu/packages/gstreamer.scm
> index b0f0b032b3..efb9a6f796 100644
> --- a/gnu/packages/gstreamer.scm
> +++ b/gnu/packages/gstreamer.scm
> @@ -431,17 +431,14 @@ compression formats through the use of the libav library.")
>                  "0f1d9rvy2qxlymmfzyknnfr5rz1vx69jv17gp7wnamc5s6p7mp2m"))))
>      (build-system gnu-build-system)
>      (arguments
> -     ;; XXX: Factorize python-sitedir with python-build-system.
> -     `(#:imported-modules (,@%gnu-build-system-modules
> +     `(#:modules ((guix build gnu-build-system)
> +                  ((guix build python-build-system) #:prefix python:))
> +       #:imported-modules (,@%gnu-build-system-modules
>                             (guix build python-build-system))
>         #:configure-flags
> -       (let* ((python (assoc-ref %build-inputs "python"))
> -              (python-version (python-version python))
> -              (python-sitedir (string-append
> -                               "lib/python" python-version "/site-packages")))
> -         (list (string-append
> -                "--with-pygi-overrides-dir=" %output "/" python-sitedir
> -                "/gi/overrides")))))
> +       (list (string-append
> +              "--with-pygi-overrides-dir=" %output "/"

Nitpicking, but since we're refactoring, could you also change %output
to the less magical (assoc-ref %outputs "out")?

> +              (python:site-packages %build-inputs %outputs) "/gi/overrides"))))

Neat!  LGTM.