gnu: %final-inputs-riscv64: Add comment.

* gnu/packages/commencement.scm (%final-inputs-riscv64): Add comment
explaining why this variable needs to exist.

1 files changed, 9 insertions, 0 deletions

diff --git a/gnu/packages/commencement.scm b/gnu/packages/commencement.scm
index 96d914344d..3fb4b2054f 100644
--- a/gnu/packages/commencement.scm
+++ b/gnu/packages/commencement.scm
@@ -3737,6 +3737,15 @@ exec ~a/bin/~a-~a -B~a/lib -Wl,-dynamic-linker -Wl,~a/~a \"$@\"~%"
       ("locales" ,glibc-utf8-locales-final))))
 
 (define-public %final-inputs-riscv64
+  ;; This is similar to the added (list gcc "lib") elsewhere in this file, but
+  ;; due to how (%current-system) is re-defined when performing builds with the
+  ;; '--system' flag, %final-inputs is too early in the evaulation pipeline to
+  ;; correctly identify the system for which a derivation will be built. Thus,
+  ;; since (%current-system) is re-determined by (guix build-system gnu) after
+  ;; loading %final-inputs but before taking into account the '--system' flag,
+  ;; the test for (target-riscv64?) needs to be in (guix build-system gnu),
+  ;; with %final-inputs-riscv64 already available at the same time that
+  ;; %final-inputs is available.
   `(("gcc:lib" ,gcc-final "lib")
     ,@%final-inputs))