python-build-system: Look up the interpreter in 'inputs'.

* guix/build/python-build-system.scm (wrap): Pass the shell
  interpreter from 'inputs' to 'wrap-program' using 'search-input-file'.

Partially-Fixes: <https://issues.guix.gnu.org/47869>
Signed-off-by: Ludovic Courtès <ludo@gnu.org>

1 files changed, 8 insertions, 1 deletions

diff --git a/guix/build/python-build-system.scm b/guix/build/python-build-system.scm
index 5b1339d14c..08871f60cd 100644
--- a/guix/build/python-build-system.scm
+++ b/guix/build/python-build-system.scm
@@ -10,6 +10,7 @@
 ;;; Copyright © 2020 Jakub Kądziołka <kuba@kadziolka.net>
 ;;; Copyright © 2020 Efraim Flashner <efraim@flashner.co.il>
 ;;; Copyright © 2021 Lars-Dominik Braun <lars@6xq.net>
+;;; Copyright © 2021 Maxime Devos <maximedevos@telenet.be>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -234,12 +235,18 @@ running checks after installing the package."
                          (string-append dir "/sbin"))))
                 outputs))
 
+  ;; Do not require "bash" to be present in the package inputs
+  ;; even when there is nothing to wrap.
+  ;; Also, calculate (sh) only once to prevent some I/O.
+  (define %sh (delay (search-input-file inputs "bin/bash")))
+  (define (sh) (force %sh))
+
   (let* ((var `("GUIX_PYTHONPATH" prefix
                 ,(search-path-as-string->list
                   (or (getenv "GUIX_PYTHONPATH") "")))))
     (for-each (lambda (dir)
                 (let ((files (list-of-files dir)))
-                  (for-each (cut wrap-program <> var)
+                  (for-each (cut wrap-program <> #:sh (sh) var)
                             files)))
               bindirs)))