From 9fc4e94986e68e0e33b260e2389765e2d3b7dd07 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ludovic=20Court=C3=A8s?= <ludo@gnu.org>
Date: Wed, 3 Mar 2021 12:27:18 +0100
Subject: [PATCH] gexp: #:references-graphs refers to non-native derivations.

Fixes a regression introduced in
c6d6aee6659acb293eb33f498fdac3b47a19a48, where #:reference-graphs would
end up referring to native inputs.

This would notably break the compilation of systems using a childhurd,
because they would attempt to build the 'hurd' package natively.

* guix/gexp.scm (lower-reference-graphs)[tuple->gexp-input]: Honor TARGET.
* tests/gexp.scm ("gexp->derivation #:references-graphs cross-compilation"):
New test.
---
 guix/gexp.scm  |  4 ++--
 tests/gexp.scm | 16 ++++++++++++++++
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/guix/gexp.scm b/guix/gexp.scm
index 8cd44ba534..b72b8f4061 100644
--- a/guix/gexp.scm
+++ b/guix/gexp.scm
@@ -875,9 +875,9 @@ corresponding <derivation-input> or store item."
   (define tuple->gexp-input
     (match-lambda
       ((thing)
-       (%gexp-input thing "out" #t))
+       (%gexp-input thing "out" (not target)))
       ((thing output)
-       (%gexp-input thing output #t))))
+       (%gexp-input thing output (not target)))))
 
   (match graphs
     (((file-names . inputs) ...)
diff --git a/tests/gexp.scm b/tests/gexp.scm
index a30d0ff6b4..834e78b9a0 100644
--- a/tests/gexp.scm
+++ b/tests/gexp.scm
@@ -1095,6 +1095,22 @@ importing.* \\(guix config\\) from the host"
                         (call-with-input-file g-guile read)
                         (list (derivation->output-path guile-drv) bash))))))
 
+(test-assertm "gexp->derivation #:references-graphs cross-compilation"
+  ;; The objects passed in #:references-graphs implicitly refer to
+  ;; cross-compiled derivations.  Make sure this is the case.
+  (mlet* %store-monad ((drv1 (lower-object coreutils (%current-system)
+                                           #:target "i586-pc-gnu"))
+                       (drv2 (lower-object coreutils (%current-system)
+                                           #:target #f))
+                       (drv3 (gexp->derivation "three"
+                                               #~(symlink #$coreutils #$output)
+                                               #:target "i586-pc-gnu"
+                                               #:references-graphs
+                                               `(("coreutils" ,coreutils))))
+                       (refs (references* (derivation-file-name drv3))))
+    (return (and (member (derivation-file-name drv1) refs)
+                 (not (member (derivation-file-name drv2) refs))))))
+
 (test-assertm "gexp->derivation #:allowed-references"
   (mlet %store-monad ((drv (gexp->derivation "allowed-refs"
                                              #~(begin