In trying to create a transmission-qt package, I inherit from transmission, remove the gtkmm dependency and the phases that deal with moving transmission-gtk to the :gui output, and add a few qt dependencies so that transmission-qt is built. See the package definition below:
(define-module (bodertz transmission-qt) #:use-module (gnu packages bittorrent) #:use-module (gnu packages qt) #:use-module (guix packages) #:use-module (guix gexp) #:use-module (guix utils)) (define-public transmission-qt (package (inherit transmission) ;; (outputs '("out")) (name "transmission-qt") (arguments (substitute-keyword-arguments (package-arguments transmission) ((#:phases phases) #~(modify-phases #$phases (delete 'move-gui) (delete 'glib-or-gtk-wrap) (delete 'wrap-program))))) (inputs (modify-inputs (package-inputs transmission) (delete "gtkmm") (append qtbase qttools qtsvg))))) This works fine, except that an unnecessary transmission-qt:gui output is created which contains license files (apologies if the email messes up the formatting): $ tree /gnu/store/k34zx89kvd712maqfi62spnbb5s31bqd-transmission-qt-4.0.6-gui /gnu/store/k34zx89kvd712maqfi62spnbb5s31bqd-transmission-qt-4.0.6-gui └── share └── doc └── transmission-qt-4.0.6 ├── bsd-3-clause.txt ├── COPYING ├── gpl-2.0.txt ├── gpl-3.0.txt └── mit.txt When I uncomment the ;; outputs '("out")) line from my package definition, I expected that it would only create the ordinary :out output, but instead, I get this error: $ guix build transmission-qt [...] builder for `/gnu/store/026fwjchyis1x99iqsgliqga284wydbc-transmission-qt-4.0.6.drv' failed to produce output path `/gnu/store/v331nyi7kqg4gi432gvhz1c719n8x7xf-transmission-qt-4.0.6-gui' Is there a way to avoid the attempt to create a :gui output?