[bug#49672] [PATCH v2 3/6] utils: Introduce the ‘current-target-nix-system’ procedure

[Thiago Jung Bauermann]

Both ‘glibc-dynamic-linker’ and ‘system->llvm-target’ use the same logic
for the default value of their arguments, so factor it out into a separate
procedure.

It turns out that this procedure will be useful in other places as well.

* gnu/packages/bootstrap.scm (glibc-dynamic-linker): Use result of
‘current-target-nix-system’ as default value for ‘system’ argument.
* gnu/packages/llvm.scm (system->llvm-target): Likewise.
* guix/utils.scm (current-target-nix-system): Define.
---
 gnu/packages/bootstrap.scm | 4 +---
 gnu/packages/llvm.scm      | 4 +---
 guix/utils.scm             | 7 +++++++
 3 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/gnu/packages/bootstrap.scm b/gnu/packages/bootstrap.scm
index 8bd0c4eaf3ab..8f444b1ff338 100644
--- a/gnu/packages/bootstrap.scm
+++ b/gnu/packages/bootstrap.scm
@@ -309,9 +309,7 @@ (define rewritten-input
                                  package-with-bootstrap-guile)))))
 
 (define* (glibc-dynamic-linker
-          #:optional (system (or (and=> (%current-target-system)
-                                        gnu-triplet->nix-system)
-                                 (%current-system))))
+          #:optional (system (current-target-nix-system)))
   "Return the name of Glibc's dynamic linker for SYSTEM."
   ;; See the 'SYSDEP_KNOWN_INTERPRETER_NAMES' cpp macro in libc.
   (cond ((string=? system "x86_64-linux") "/lib/ld-linux-x86-64.so.2")
diff --git a/gnu/packages/llvm.scm b/gnu/packages/llvm.scm
index eb949bed1b47..e2bc5398715a 100644
--- a/gnu/packages/llvm.scm
+++ b/gnu/packages/llvm.scm
@@ -77,9 +77,7 @@ (define-module (gnu packages llvm)
             system->llvm-target))
 
 (define* (system->llvm-target #:optional
-                              (system (or (and=> (%current-target-system)
-                                                 gnu-triplet->nix-system)
-                                          (%current-system))))
+                              (system (current-target-nix-system)))
   "Return the LLVM target name that corresponds to SYSTEM, a system type such
 as \"x86_64-linux\"."
   ;; See the 'lib/Target' directory of LLVM for a list of supported targets.
diff --git a/guix/utils.scm b/guix/utils.scm
index 44c46cb4a96c..d5e15581acea 100644
--- a/guix/utils.scm
+++ b/guix/utils.scm
@@ -85,6 +85,7 @@ (define-module (guix utils)
             gnu-triplet->nix-system
             %current-system
             %current-target-system
+            current-target-nix-system
             package-name->name+version
             target-linux?
             target-hurd?
@@ -635,6 +636,12 @@ (define %current-target-system
   ;; cross-building to.
   (make-parameter #f))
 
+(define (current-target-nix-system)
+  "Return the Nix system identifier for the current target, whether we are
+cross-building or not."
+  (or (and=> (%current-target-system) gnu-triplet->nix-system)
+      (%current-system)))
+
 (define* (package-name->name+version spec
                                      #:optional (delimiter #\@))
   "Given SPEC, a package name like \"foo@0.9.1b\", return two values: \"foo\"