Current version 0.12 doesnt build:

...
ld: gnunet-fs-gtk.o: in function `process_paste':
/tmp/guix-build-gnunet-gtk-0.12.0.drv-0/gnunet-gtk-0.12.0/src/fs/gnunet-fs-gtk.c:369: undefined reference to `GNUNET_free_non_null'
ld: gnunet-fs-gtk.o: in function `arm_connection_state_change':
/tmp/guix-build-gnunet-gtk-0.12.0.drv-0/gnunet-gtk-0.12.0/src/fs/gnunet-fs-gtk.c:539: undefined reference to `GNUNET_free_non_null'
ld: gnunet-fs-gtk.o: in function `service_list_callback':
/tmp/guix-build-gnunet-gtk-0.12.0.drv-0/gnunet-gtk-0.12.0/src/fs/gnunet-fs-gtk.c:526: undefined reference to `GNUNET_free_non_null'
ld: gnunet-fs-gtk_download-save-as.o: in function `GNUNET_FS_GTK_free_download_entry':
/tmp/guix-build-gnunet-gtk-0.12.0.drv-0/gnunet-gtk-0.12.0/src/fs/gnunet-fs-gtk_download-save-as.c:109: undefined reference to `GNUNET_free_non_null'
ld: gnunet-fs-gtk_download-save-as.o: in function `GNUNET_GTK_save_as_dialog_response_cb':
/tmp/guix-build-gnunet-gtk-0.12.0.drv-0/gnunet-gtk-0.12.0/src/fs/gnunet-fs-gtk_download-save-as.c:173: undefined reference to `GNUNET_free_non_null'
ld: gnunet-fs-gtk_download-save-as.o:/tmp/guix-build-gnunet-gtk-0.12.0.drv-0/gnunet-gtk-0.12.0/src/fs/gnunet-fs-gtk_download-save-as.c:201: more undefined references to `GNUNET_free_non_null' follow
collect2: error: ld returned 1 exit status