It looks like the recently released app-emulation/wine-*-4.0 would rely on version 4.7.5 of app-emulation/wine-mono.
I guess so, I emerged the latest version with the "mono" USE flag enabled: [ebuild NS ~] app-emulation/wine-any-4.0:4.0::gentoo [3.21:3.21::gentoo] USE="X alsa d3d9 dos fontconfig gecko gstreamer jpeg lcms mono ncurses opencl opengl png (selinux) ssl staging threads truetype vaapi vkd3d vulkan xcomposite xml -capi -cups -custom-cflags -ffmpeg -gphoto2 -gsm -gssapi -kerberos -ldap -mp3 -netapi -nls -odbc -openal -osmesa -oss -pcap -perl -pipelight (-prelink) -pulseaudio -realtime -run-exes -samba -scanner -sdl -test -themes -udev -udisks -v4l -xinerama" ABI_X86="32 64 (-x32)" 30,957 KiB set the new version with eselect, ran "winecfg" and saw this: "Wine could not find a wine-mono package which is needed for .NET applications to work correctly. Wine can automatically download and install it for you. - Note: it is recommended to use your distribution's packages instead. See https://wiki.winehq.org/Mono for details. - Cancel / Install" > wine --version wine-4.0 (Staging)
The bug has been closed via the following commit(s): https://gitweb.gentoo.org/repo/proj/wine.git/commit/?id=a981e770b5ed7ada25f3801b40636b0ec2330efd commit a981e770b5ed7ada25f3801b40636b0ec2330efd Author: Nick Sarnie <sarnex@gentoo.org> AuthorDate: 2019-01-27 16:45:37 +0000 Commit: Nick Sarnie <sarnex@gentoo.org> CommitDate: 2019-01-27 16:45:37 +0000 app-emulation/wine-mono: Bump to 4.7.5 Closes: https://bugs.gentoo.org/676142 Package-Manager: Portage-2.3.58, Repoman-2.3.12 Signed-off-by: Nick Sarnie <sarnex@gentoo.org> app-emulation/wine-mono/Manifest | 1 + app-emulation/wine-mono/wine-mono-4.7.5.ebuild | 21 +++++++++++++++++++++ 2 files changed, 22 insertions(+)