From 29c1793dc224597aa08af3bd7a0bdc39eb2babf8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ludovic=20Court=C3=A8s?= <ludo@gnu.org>
Date: Tue, 15 Jan 2013 01:05:39 +0100
Subject: [PATCH] build-system/gnu: Allow the `source' argument to be #f.

* guix/build-system/gnu.scm (gnu-build): Allow SOURCE to be #f.
---
 guix/build-system/gnu.scm | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/guix/build-system/gnu.scm b/guix/build-system/gnu.scm
index a3a770f631..3eaed4bd78 100644
--- a/guix/build-system/gnu.scm
+++ b/guix/build-system/gnu.scm
@@ -204,7 +204,7 @@ (define* (gnu-build store name source inputs
   (define builder
     `(begin
        (use-modules ,@modules)
-       (gnu-build #:source ,(if (derivation-path? source)
+       (gnu-build #:source ,(if (and source (derivation-path? source))
                                 (derivation-path->output-path source)
                                 source)
                   #:system ,system
@@ -239,7 +239,9 @@ (define guile-for-build
 
   (build-expression->derivation store name system
                                 builder
-                                `(("source" ,source)
+                                `(,@(if source
+                                        `(("source" ,source))
+                                        '())
                                   ,@inputs
                                   ,@(if implicit-inputs?
                                         (parameterize ((%store store))