[bug#38612] Pass system and target arguments to gexp->file.

[Mathieu Othacehe]

Hello,

The attached patch fixes issues encountered when cross-compiling a
system.  gexps passed to gexp->file were not honoring target argument.

Mathieu

>From 67c3982503c4d9ab4c77b5df295957abbe60dfeb Mon Sep 17 00:00:00 2001
From: Mathieu Othacehe <address@hidden>
Date: Sat, 14 Dec 2019 17:52:53 +0100
Subject: [PATCH] gexp: Add system and target support to gexp->file.

* guix/gexp.scm (gexp->file): Add system and target arguments and pass them to
gexp->derivation and load-path-expression calls,
(scheme-file-compiler): adapt accordingly to pass system and target arguments.
---
 guix/gexp.scm | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/guix/gexp.scm b/guix/gexp.scm
index a96592ac76..ca436b5a66 100644
--- a/guix/gexp.scm
+++ b/guix/gexp.scm
@@ -2,6 +2,7 @@
 ;;; Copyright © 2014, 2015, 2016, 2017, 2018, 2019 Ludovic Courtès 
<address@hidden>
 ;;; Copyright © 2018 Clément Lassieur <address@hidden>
 ;;; Copyright © 2018 Jan Nieuwenhuizen <address@hidden>
+;;; Copyright © 2019 Mathieu Othacehe <address@hidden>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -456,7 +457,10 @@ This is the declarative counterpart of 'gexp->file'."
   ;; Compile FILE by returning a derivation that builds the file.
   (match file
     (($ <scheme-file> name gexp splice?)
-     (gexp->file name gexp #:splice? splice?))))
+     (gexp->file name gexp
+                 #:splice? splice?
+                 #:system system
+                 #:target target))))
 
 ;; Appending SUFFIX to BASE's output file name.
 (define-record-type <file-append>
@@ -1603,7 +1607,9 @@ imported modules in its search path.  Look up EXP's 
modules in MODULE-PATH."
 (define* (gexp->file name exp #:key
                      (set-load-path? #t)
                      (module-path %load-path)
-                     (splice? #f))
+                     (splice? #f)
+                     (system (%current-system))
+                     target)
   "Return a derivation that builds a file NAME containing EXP.  When SPLICE?
 is true, EXP is considered to be a list of expressions that will be spliced in
 the resulting file.
@@ -1626,10 +1632,14 @@ Lookup EXP's modules in MODULE-PATH."
                                                     exp
                                                     (gexp ((ungexp exp)))))))))
                         #:local-build? #t
-                        #:substitutable? #f)
+                        #:substitutable? #f
+                        #:system system
+                        #:target target)
       (mlet %store-monad ((set-load-path
                            (load-path-expression modules module-path
-                                                 #:extensions extensions)))
+                                                 #:extensions extensions
+                                                 #:system system
+                                                 #:target target)))
         (gexp->derivation name
                           (gexp
                            (call-with-output-file (ungexp output)
@@ -1642,7 +1652,9 @@ Lookup EXP's modules in MODULE-PATH."
                                                       (gexp ((ungexp 
exp)))))))))
                           #:module-path module-path
                           #:local-build? #t
-                          #:substitutable? #f))))
+                          #:substitutable? #f
+                          #:system system
+                          #:target target))))
 
 (define* (text-file* name #:rest text)
   "Return as a monadic value a derivation that builds a text file containing
-- 
2.24.0