emerge uwsgi -pv

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

Calculating dependencies... done!

!!! All ebuilds that could satisfy "uwsgi" have been masked.
!!! One of the following masked packages is required to complete your request:
- www-servers/uwsgi-2.0.18::net-kit (masked by: invalid: DEPEND: USE flag 'ruby_targets_ruby30' referenced in conditional 'ruby_targets_ruby30?' is not in IUSE, invalid: RDEPEND: USE flag 'ruby_targets_ruby30' referenced in conditional 'ruby_targets_ruby30?' is not in IUSE)
- www-servers/uwsgi-2.0.17.1-r1::net-kit (masked by: invalid: DEPEND: USE flag 'ruby_targets_ruby30' referenced in conditional 'ruby_targets_ruby30?' is not in IUSE, invalid: RDEPEND: USE flag 'ruby_targets_ruby30' referenced in conditional 'ruby_targets_ruby30?' is not in IUSE)
- www-servers/uwsgi-2.0.17.1::net-kit (masked by: invalid: DEPEND: USE flag 'ruby_targets_ruby30' referenced in conditional 'ruby_targets_ruby30?' is not in IUSE, invalid: RDEPEND: USE flag 'ruby_targets_ruby30' referenced in conditional 'ruby_targets_ruby30?' is not in IUSE)
- www-servers/uwsgi-2.0.17::net-kit (masked by: invalid: DEPEND: USE flag 'ruby_targets_ruby30' referenced in conditional 'ruby_targets_ruby30?' is not in IUSE, invalid: RDEPEND: USE flag 'ruby_targets_ruby30' referenced in conditional 'ruby_targets_ruby30?' is not in IUSE)For more information, see the MASKED PACKAGES section in the emerge
man page or refer to the Gentoo Handbook.