Install this version:
emerge -a =dev-perl/constant-boolean-0.20.0
If this version is masked, you can unmask it using the autounmask tool or standard emerge options:
autounmask =dev-perl/constant-boolean-0.20.0
Or alternatively:
emerge --autounmask-write -a =dev-perl/constant-boolean-0.20.0
# Copyright 1999-2020 Gentoo Authors
# Distributed under the terms of the GNU General Public License v2
EAPI=7
DIST_AUTHOR=DEXTER
DIST_VERSION=0.02
inherit perl-module
DESCRIPTION="Define TRUE and FALSE constants"
SLOT="0"
KEYWORDS="~amd64 ~x86"
RDEPEND="
>=dev-perl/Symbol-Util-0.20.0
"
DEPEND="dev-perl/Module-Build"
BDEPEND="${RDEPEND}
dev-perl/Module-Build
"
dev-perl/Module-Build
>=dev-perl/Symbol-Util-0.20.0
>=dev-perl/Symbol-Util-0.20.0 dev-perl/Module-Build