These are the packages that would be merged, in order:

Calculating dependencies ... done!
Dependency resolution took 1.11 s (backtrack: 0/20).


The following USE changes are necessary to proceed:
 (see "package.use" in the portage(5) man page for more details)
# required by gnome-base/gnome-shell-49.7::gentoo
# required by =gnome-base/gnome-shell-49.7 (argument)
>=app-crypt/gcr-4.4.1 introspection
# required by gnome-base/gnome-shell-49.7::gentoo
# required by =gnome-base/gnome-shell-49.7 (argument)
>=gui-libs/gtk-4.22.5-r1 introspection
# required by gnome-base/gnome-shell-49.7::gentoo
# required by =gnome-base/gnome-shell-49.7 (argument)
=x11-wm/mutter-49.7 introspection

!!! The ebuild selected to satisfy ">=x11-wm/mutter-49.0:0/17[introspection,test?]" has unmet requirements.
- x11-wm/mutter-49.7::gentoo USE="X wayland (xwayland) -bash-completion -debug -devkit -elogind -gnome -gtk-doc -introspection -screencast (-selinux) -sysprof (-systemd) -test -udev" INPUT_DEVICES="-wacom" VIDEO_CARDS="-nvidia"

  The following REQUIRED_USE flag constraints are unsatisfied:
    wayland? ( exactly-one-of ( elogind systemd ) udev )

  The above constraints are a subset of the following complete expression:
    any-of ( X wayland ) devkit? ( screencast wayland ) gtk-doc? ( introspection ) wayland? ( exactly-one-of ( elogind systemd ) udev ) test? ( screencast wayland )

(dependency required by "gnome-base/gnome-shell-49.7::gentoo" [ebuild])
(dependency required by "=gnome-base/gnome-shell-49.7" [argument])