guix gc: Error out when extra arguments are passed.

Fixes <http://bugs.gnu.org/21817>.
Reported by Petter Berntsen <petter@mykolab.ch>.

* guix/scripts/gc.scm (guix-gc)[assert-no-extra-arguments]: New
  procedure.
  Use it for actions 'collect-garbage', 'optimize', and 'verify'.
* tests/guix-gc.sh: Add tests.

1 files changed, 7 insertions, 1 deletions

diff --git a/tests/guix-gc.sh b/tests/guix-gc.sh
index c1eb66cef53..a100f186f51 100644
--- a/tests/guix-gc.sh
+++ b/tests/guix-gc.sh
@@ -1,5 +1,5 @@
 # GNU Guix --- Functional package management for GNU
-# Copyright © 2013 Ludovic Courtès <ludo@gnu.org>
+# Copyright © 2013, 2015 Ludovic Courtès <ludo@gnu.org>
 #
 # This file is part of GNU Guix.
 #
@@ -25,6 +25,12 @@ guix gc --version
 trap "rm -f guix-gc-root" EXIT
 rm -f guix-gc-root
 
+# For some operations, passing extra arguments is an error.
+for option in "" "-C 500M" "--verify" "--optimize"
+do
+    if guix gc $option whatever; then false; else true; fi
+done
+
 # Check the references of a .drv.
 drv="`guix build guile-bootstrap -d`"
 out="`guix build guile-bootstrap`"