[ANNOUNCEMENT] unison2.48-2.48.4-2 (Warning: possible breakage)

[Ken Brown]

On 8/31/2020 8:39 PM, Andrew Schulman via Cygwin wrote:
>>> There is unfortunately another layer of incompatibility in Unison: Two
>>> Unison executables are only compatible if they were built with the same
>>> version of OCaml.
>>
>> What a mess!
> 
> Glad you understand :)
> 
>> Would you consider embedding the OCaml version in the package name
>> as suggested by the Debian maintainer
>> (http://lists.seas.upenn.edu/pipermail/unison-hackers/2020-August/001975.html)?
>> Thus unison2.48-2.48.4-1 would be replaced by something like
>> unison2.48+4.04.1... and unison2.48-2.48.4-2 would be replace by something like
>> unison2.48+4.08.1....  That way people who are happy with unison2.48-2.48.4-1
>> can keep using it without being pestered by setup to update.
> 
> Yes, I could do that. I was hoping to avoid it, but it may be the only realistic
> solution.
> 
> It may be mainly Unison 2.48 that's affected, and maybe also 2.51 and the
> forthcoming 2.52. I guess that very few people are still using the older
> versions, and if they are they don't want any changes now.
>   
>> FWIW, here's my situation, which is probably not typical.  When you released
>> unison2.48-2.48.4-1 a few years ago, it was incompatible with the Linux server
>> that I sync with.  So I simply built OCaml and unison myself on that server,
>> using the same versions that you used, and installed unison in my own ~/bin
>> directory.
>>
>> I could do that again, now using OCaml 4.08.1.  But I'd much rather just keep my
>> current arrangement, without having setup try to update unison2.48 every time I
>> run it.
> 
> Thanks, that's helpful to know. Your situation might not be unusual, I don't
> know. For all I know, you and I are the only Cygwin Unison users.
> 
> So was unison2.48-2.48.4-1 built with OCaml 4.04.1? I don't remember, and I'm
> not sure how to tell.

I just checked a Cygwin snapshot from around the time unison2.48-2.48.4-1 was 
built 
(http://ctm.crouchingtigerhiddenfruitbat.org/pub/cygwin/circa/64bit/2017/02/22/131407/index.html), 
and it looks like the current version of Cygwin's OCaml was 4.02.3 at the time. 
I mentioned 4.04.1 above because that's the version I built for Linux.  So maybe 
the crucial thing is that it was pre-4.08.1.

Ken