Was it ever considered to include the relevant META files in ocaml.git, and consequently install them via make install? While ocamlfind.git does have some sort of overlay, it is as of today at least partly outdated because it does not seem to handle the inclusion of the seq library. The result is a failure in lwt dune runtest, I think:
[ 65s] --- let_1.expect 2019-10-29 13:41:49.440000000 +0000
[ 65s] +++ let_1.fixed 2019-10-29 13:41:50.176000000 +0000
[ 65s] @@ -1,3 +1 @@
[ 65s] -File "let_1.ml", line 2, characters 10-12:
[ 65s] -Error: This pattern matches values of type unit
[ 65s] - but a pattern was expected which matches values of type int
[ 65s] +ocamlfind: Package `seq' not found - required by `lwt'
For the openSUSE builds I will move the META files from ocaml-findlib to ocaml also for other reasons. That move will finally allow the usage of the verbatim dune external-lib-deps output for my ocamlfind() rpm requires/provides tags. In other words, I can add a BuildRequires: ocamlfind(unix) to a rpm specfile and do not need to worry if “unix” (or any other package that can appear in a dune (library) section) is provided as an external library or as a compiler built-in library.