build-system: Bags record their system and target.

* guix/build-system.scm (<bag>)[system, target]: New fields.
  (make-bag): Add #:system parameter and pass it to LOWER.
* gnu/packages/bootstrap.scm (make-raw-bag): Initialize 'system' field.
* guix/build-system/cmake.scm (lower): Likewise.
* guix/build-system/perl.scm (lower): Likewise.
* guix/build-system/python.scm (lower): Likewise.
* guix/build-system/ruby.scm (lower): Likewise.
* guix/build-system/trivial.scm (lower): Likewise.
* guix/build-system/gnu.scm (lower): Initialize 'system' and 'target'
  fields.
* guix/packages.scm (bag->derivation, bag->cross-derivation): New
  procedures.
  (package-derivation, package-cross-derivation): Use 'bag->derivation'.
* tests/packages.scm ("search paths"): Initialize 'system' and 'target'
  fields.
  ("package->bag", "package->bag, cross-compilation", "bag->derivation",
  "bag->derivation, cross-compilation"): New tests.

1 files changed, 3 insertions, 1 deletions

diff --git a/guix/build-system/perl.scm b/guix/build-system/perl.scm
index 6cf8cbe13a..1a968f4150 100644
--- a/guix/build-system/perl.scm
+++ b/guix/build-system/perl.scm
@@ -43,7 +43,8 @@
     (module-ref module 'perl)))
 
 (define* (lower name
-                #:key source inputs native-inputs outputs target
+                #:key source inputs native-inputs outputs
+                system target
                 (perl (default-perl))
                 #:allow-other-keys
                 #:rest arguments)
@@ -54,6 +55,7 @@
   (and (not target)                               ;XXX: no cross-compilation
        (bag
          (name name)
+         (system system)
          (host-inputs `(,@(if source
                               `(("source" ,source))
                               '())