There is an updated pull request by leahneukirchen against master on the void-packages repository

https://github.com/leahneukirchen/void-packages ocaml412
https://github.com/void-linux/void-packages/pull/29279

OCaml 4.12
First stab at it.

Currently broken:

- [x] xen
- [x] libguestfs
- [x] unison
- [ ] polygen
- [x] coccinelle

A patch file from https://github.com/void-linux/void-packages/pull/29279.patch is attached