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

[Mathieu Othacehe]

Hello,

> trick ensures that we get the system that current at the time of the
> monadic bind, whereas your change get the system and target that are
> current at the time of the call.
>
> It’s a terrible pitfall, I know…

Ok, then, I used the same trick to read %current-target-system at bind
time. With this trick, target is set to the value passed to the guix
system command (it is #f otherwise).

WDYT?

Mathieu

>From c8b0e65d9b264bd484c7c6571c2ce3d68173b057 Mon Sep 17 00:00:00 2001
From: Mathieu Othacehe <address@hidden>
Date: Tue, 24 Dec 2019 15:04:57 +0100
Subject: [PATCH] profiles: Fix profile-derivation cross-compilation.

* guix/store.scm (current-target-system): New exported monadic procedure.
* guix/profiles.scm (profile-derivation): Set target at bind time using the
above procedure.
---
 guix/profiles.scm | 4 ++++
 guix/store.scm    | 7 +++++++
 2 files changed, 11 insertions(+)

diff --git a/guix/profiles.scm b/guix/profiles.scm
index 987bab4e7f..d20f06e7b3 100644
--- a/guix/profiles.scm
+++ b/guix/profiles.scm
@@ -9,6 +9,7 @@
 ;;; Copyright © 2017 Huang Ying <address@hidden>
 ;;; Copyright © 2017 Maxim Cournoyer <address@hidden>
 ;;; Copyright © 2019 Kyle Meyer <address@hidden>
+;;; Copyright © 2019 Mathieu Othacehe <address@hidden>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -1459,6 +1460,9 @@ are cross-built for TARGET."
   (mlet* %store-monad ((system (if system
                                    (return system)
                                    (current-system)))
+                       (target (if target
+                                   (return target)
+                                   (current-target-system)))
                        (ok?    (if allow-collisions?
                                    (return #t)
                                    (check-for-collisions manifest system
diff --git a/guix/store.scm b/guix/store.scm
index cf25d347fc..f99fa581a8 100644
--- a/guix/store.scm
+++ b/guix/store.scm
@@ -1,6 +1,7 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019 Ludovic Courtès 
<address@hidden>
 ;;; Copyright © 2018 Jan Nieuwenhuizen <address@hidden>
+;;; Copyright © 2019 Mathieu Othacehe <address@hidden>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -159,6 +160,7 @@
             %guile-for-build
             current-system
             set-current-system
+            current-target-system
             text-file
             interned-file
             interned-file-tree
@@ -1816,6 +1818,11 @@ the store."
   (lambda (state)
     (values (%current-system system) state)))
 
+(define-inlinable (current-target-system)
+  ;; Consult the %CURRENT-TARGET-SYSTEM fluid at bind time.
+  (lambda (state)
+    (values (%current-target-system) state)))
+
 (define %guile-for-build
   ;; The derivation of the Guile to be used within the build environment,
   ;; when using 'gexp->derivation' and co.
-- 
2.24.1