arpi@biblio301new2 ~ $ sudo emerge --ask --verbose --update --deep --with-bdeps=y --newuse --changed-deps=y --backtrack=30 @world

Local copy of remote index is up-to-date and will be used.

 * IMPORTANT: 12 news items need reading for repository 'gentoo'.
 * Use eselect news read to view new items.


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

Calculating dependencies... done!

!!! Multiple package instances within a single package slot have been pulled
!!! into the dependency graph, resulting in a slot conflict:

dev-lang/perl:0

  (dev-lang/perl-5.28.2-r1:0/5.28::gentoo, binary scheduled for merge) pulled in by
    dev-lang/perl:0/5.28= required by (dev-perl/File-ShareDir-Install-0.110.0:0/0::gentoo, binary scheduled for merge)
                 ^^^^^^^^                                                                                                                                 
    (and 7 more with the same problem)

  (dev-lang/perl-5.24.3:0/5.24::gentoo, installed) pulled in by
    dev-lang/perl:0/5.24=[-build(-)] required by (dev-perl/XML-Parser-2.440.0:0/0::gentoo, installed)
                 ^^^^^^^^                                                                                                                

NOTE: Use the '--verbose-conflicts' option to display parents omitted above

It may be possible to solve this problem by using package.mask to
prevent one of those packages from being selected. However, it is also
possible that conflicting dependencies exist such that they are
impossible to satisfy simultaneously.  If such a conflict exists in
the dependencies of two different packages, then those packages can
not be installed simultaneously.

For more information, see MASKED PACKAGES section in the emerge man
page or refer to the Gentoo Handbook.


!!! All ebuilds that could satisfy "x11-base/xorg-proto" have been masked.
!!! One of the following masked packages is required to complete your request:
- x11-base/xorg-proto-9999::gentoo (masked by: EAPI 7)
- x11-base/xorg-proto-2019.2::gentoo (masked by: EAPI 7)
- x11-base/xorg-proto-2019.1::gentoo (masked by: EAPI 7)
- x11-base/xorg-proto-2019.1 (masked by: EAPI 7)

The current version of portage supports EAPI '6'. You must upgrade to a
newer version of portage before EAPI masked packages can be installed.
(dependency required by "x11-libs/libSM-1.2.3::gentoo" [binary])
(dependency required by "x11-libs/libXt-1.1.5::gentoo" [installed])
(dependency required by "sys-apps/dbus-1.10.18::gentoo" [installed])
(dependency required by "gnome-base/dconf-0.30.1::gentoo" [binary])
(dependency required by "dev-libs/glib-2.58.3-r1::gentoo[dbus]" [ebuild])
(dependency required by "dev-libs/dbus-glib-0.110::gentoo" [binary])
(dependency required by "@autodeps" [set])
(dependency required by "@selected" [set])
(dependency required by "@world" [argument])
For more information, see the MASKED PACKAGES section in the emerge
man page or refer to the Gentoo Handbook.