[Unison-hackers] OCaml version mismatch breaks Unison 2.48.4

[Andrew Schulman]

> Le 04/09/2020 à 16:00, Andrew Schulman a écrit :
> >> Now, what I will do (I am the Unison maintainer in Debian) is embed the
> >> OCaml version in the package name (e.g. unison-2.52+4.08.1) so that one
> >> can have many combinations co-installed... but there will always be a
> >> single OCaml version in the official Debian archive for a given suite.
> > 
> > I'm willing to do this too for Cygwin. For now I'm planning to package
> > 
> > unison2.48+4.04.2
> > unison2.48+4.08.1
> > 
> > but that can change.
> > 
> > For the poor users who are trying to sync between, say, Cygwin and Debian,
> > I think it would help if the package versions were the same in different
> > distros. Then a user can just look and see that, for example,
> > unison2.52+4.08.1 is available on both sides, and just install that and not
> > have to worry about which OCaml versions are compatible with which others.
> > 
> > So if you know which versions you're planning to package for Debian, please
> > tell us here so I can package the same ones. And if the Unison maintainers
> > from other distros are also reading this list, it'd be good if we all
> > packaged the same versions.
> 
> At the moment, in testing/unstable, there is "unison-2.48" (compiled
> with OCaml 4.08.1). Since the next version of OCaml to be packaged in
> Debian will be 4.11.1 and unison-2.48 does not compile with it, I think
> I will let this unison-2.48 branch die and instead package the
> soon-to-be-released 2.52.0 as "unison-2.52+4.11.1".

Good, I'll do the same. Maybe other distros will follow.

> > BTW according to David Allsop on the Cygwin list[1], the first
> > incompatibility in OCaml's marshaling came in OCaml 4.08, and the next one
> > is coming in 4.11, although that one may not matter for Unison. So we
> > probably only need one pre-4.08 and one post-4.08 package for each Unison
> > version.
> 
> My plan is to stop using OCaml marshalling altogether. This may
> introduce new dependencies, though, that I guess will have somehow to be
> packaged for Cygwin. What's your take on this? I am thinking about
> ppx_bin_prot (in opam, but has many dependencies), ppx_protobuf (in
> opam, less dependencies, but does not support bigarrays so it won't work
> on 32-bit) or maybe a custom ppx with no new dependencies.

Not sure, as I don't maintain any OCaml packages for Cygwin, and am not
sure of the right way to package them. So like Benjamin, I'd prefer fewer
dependencies. But do what you need to do, we'll figure it out.

Andrew