~ruther/guix-local: Have `%nixpkgs-directory' default to #f when $NIXPKGS is the empty string.

a09ec3a5af3eb38b31d4eff0f323a2c47b82c114 — Ludovic Courtès 13 years ago 8366764

Have `%nixpkgs-directory' default to #f when $NIXPKGS is the empty string.

* guix/utils.scm (%nixpkgs-directory): Set to #f when the `NIXPKGS'
  environment variable is set but empty.  Reported by
  Andreas Enge <andreas@enge.fr>.

patch browse .tar.gz

1 files changed, 9 insertions(+), 1 deletions(-)

M guix/utils.scm

M guix/utils.scm => guix/utils.scm +9 -1

@@ 156,7 156,15 @@ evaluate to a simple datum."
 (define %nixpkgs-directory
   (make-parameter
    ;; Capture the build-time value of $NIXPKGS.
-   (or %nixpkgs (getenv "NIXPKGS"))))
+   (or %nixpkgs
+       (and=> (getenv "NIXPKGS")
+              (lambda (val)
+                ;; Bail out when passed an empty string, otherwise
+                ;; `nix-instantiate' will sit there and attempt to read
+                ;; from its standard input.
+                (if (string=? val "")
+                    #f
+                    val))))))
 
 (define* (nixpkgs-derivation attribute #:optional (system (%current-system)))
   "Return the derivation path of ATTRIBUTE in Nixpkgs."