[bug#51198] [PATCH v2 2/2] gnu: b2sum: Build on the local machine.

[Leo Famulari <leo@famulari.name>]

* gnu/packages/crypto.scm (b2sum)[arguments]: Set '#:substitutable? #f' and
'#:local-build? #t'.
---
 gnu/packages/crypto.scm | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/gnu/packages/crypto.scm b/gnu/packages/crypto.scm
index b6f2010a80..d4c6717eb5 100644
--- a/gnu/packages/crypto.scm
+++ b/gnu/packages/crypto.scm
@@ -858,9 +858,19 @@ (define-public b2sum
                  (base32 "04z631v0vzl52g73v390ask5fnzi5wg83lcjkjhpmmymaz0jn152"))))
       (build-system gnu-build-system)
       (arguments
-       `(#:make-flags (list (string-append "CC=" ,(cc-for-target))
-                            (string-append "PREFIX=" (assoc-ref %outputs "out")))
+       `(;; By default, b2sum uses the compiler to generate instructions
+         ;; tailored to the CPU of the running machine, using "-march=native".
+         ;; This gives a ~1.5x speedup on a Core i5-6300U with a large dataset
+         ;; paged in, whereas compilation of b2sum takes ~1.5 seconds.
+         ;; b2sum does not support run-time feature detection:
+         ;; https://github.com/BLAKE2/BLAKE2/issues/1
+         ;; For more information, see the discussion beginning here:
+         ;; https://debbugs.gnu.org/cgi/bugreport.cgi?bug=51198#13
+         #:substitutable? #f
+         #:local-build? #t
          #:tests? #f ; No test suite
+         #:make-flags (list (string-append "CC=" ,(cc-for-target))
+                            (string-append "PREFIX=" (assoc-ref %outputs "out")))
          #:phases
          (modify-phases %standard-phases
            (add-before 'build 'change-directory
-- 
2.33.1