il FAUT mettre à jour l’arbre portage et les overlays comme Calculate en utilisant la commande :
eix-sync
Sinon vous risquez d’avoir des erreurs.
Dans la commande, le “N” signifie NewUse en gros vous avez indiqué un nouveau USE FLAGS et vous souhaitez que celui-ci soit pris en compte pour l’ensemble de votre Calculate, vous n’avez pas besoin de l’indiquer à chaque fois.
La documentation de emerge indique que (sorry) :
--newuse (-N)
Tells emerge to include installed packages where USE flags have changed since compilation. This option also implies the --selective option. USE flag changes include:
A USE flag was added to a package. A USE flag was removed from a package. A USE flag was turned on for a package. A USE flag was turned off for a package.
USE flags may be toggled by your profile as well as your USE and package.use settings. If you would like to skip rebuilds for which disabled flags have been added to or removed from IUSE, see the related --changed-use option.