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/gnu/packages/bootstrap.scm b/gnu/packages/bootstrap.scm
index efa8cd89eb1..315e8cf21eb 100644
--- a/gnu/packages/bootstrap.scm
+++ b/gnu/packages/bootstrap.scm
@@ -198,9 +198,11 @@ $out/bin/guile --version~%"
                 #:inputs `((,bash) (,builder)))))
 
 (define* (make-raw-bag name
-                       #:key source inputs native-inputs outputs target)
+                       #:key source inputs native-inputs outputs
+                       system target)
   (bag
     (name name)
+    (system system)
     (build-inputs inputs)
     (build raw-build)))