+# Compute the derivation of a pack.
+drv="`guix pack coreutils -d --no-grafts`"
+guix gc -R "$drv" | grep "`guix build coreutils -d --no-grafts`"
+
+# Compute the derivation of a cross-compiled pack. Make sure it refers to the
+# cross-compiled package and not to the native package.
+drv="`guix pack idutils -d --no-grafts --target=arm-linux-gnueabihf`"
+guix gc -R "$drv" | \
+ grep "`guix build idutils --target=arm-linux-gnueabihf -d --no-grafts`"
+if guix gc -R "$drv" | grep "`guix build idutils -d --no-grafts`";
+then false; else true; fi
+