Install this version:
emerge -a =app-vim/apkbuild-vim-20210911
If this version is masked, you can unmask it using the autounmask tool or standard emerge options:
autounmask =app-vim/apkbuild-vim-20210911
Or alternatively:
emerge --autounmask-write -a =app-vim/apkbuild-vim-20210911
# Copyright 2021 Gentoo Authors
# Distributed under the terms of the GNU General Public License v2
EAPI=8
inherit vim-plugin
MY_PN=${PN/-/.}
COMMIT="8dbd9745f76fb284656711238e8cd42d021da85e"
DESCRIPTION="vim plugin: edit and work with APKBUILD files"
HOMEPAGE="https://gitlab.alpinelinux.org/Leo/apkbuild.vim"
SRC_URI="https://gitlab.alpinelinux.org/Leo/${MY_PN}/-/archive/${COMMIT}/${MY_PN}-${COMMIT}.tar.bz2"
S="${WORKDIR}/${MY_PN}-${COMMIT}"
LICENSE="MIT"
KEYWORDS="~amd64 ~x86"
VIM_PLUGIN_HELPFILES="apkbuild-vim"