From b9373e262730578ba6c3805ffe44900f10bc655c Mon Sep 17 00:00:00 2001
From: Ludovic Courtès <ludo@gnu.org>
Date: Wed, 10 Jul 2019 18:39:25 +0200
Subject: gexp: 'lowered-gexp-guile' now returns a <derivation-input>.

* guix/derivations.scm (derivation-input-output-path): New procedure.
* guix/gexp.scm (lower-gexp): Wrap GUILE in a <derivation-input>.
(gexp->derivation): Adjust accordingly.
* guix/remote.scm (remote-pipe-for-gexp, remote-eval): Adjust
accordingly.
* tests/gexp.scm ("lower-gexp"): Adjust accordingly.
---
 guix/derivations.scm | 8 ++++++++
 1 file changed, 8 insertions(+)

(limited to 'guix/derivations.scm')

diff --git a/guix/derivations.scm b/guix/derivations.scm
index 23d058e832..92d50503ce 100644
--- a/guix/derivations.scm
+++ b/guix/derivations.scm
@@ -71,6 +71,7 @@ (define-module (guix derivations)
             derivation-input-derivation
             derivation-input-sub-derivations
             derivation-input-output-paths
+            derivation-input-output-path
             valid-derivation-input?
 
             &derivation-error
@@ -221,6 +222,13 @@ (define (derivation-input-output-paths input)
      (map (cut derivation->output-path drv <>)
           sub-drvs))))
 
+(define (derivation-input-output-path input)
+  "Return the output file name of INPUT.  If INPUT has more than one outputs,
+an error is raised."
+  (match input
+    (($ <derivation-input> drv (output))
+     (derivation->output-path drv output))))
+
 (define (valid-derivation-input? store input)
   "Return true if INPUT is valid--i.e., if all the outputs it requests are in
 the store."
-- 
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