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(8.15.2/8.15.2) with ESMTP id 081ATig0031397 for ; Tue, 1 Sep 2020 11:29:44 +0100 (BST) (envelope-from David.Allsopp@cl.cam.ac.uk) Received: from romulus.metastack.com (26.77-31-62.static.virginmediabusiness.co.uk [62.31.77.26]) (authenticated bits=0) by mail.authsmtp.com (8.15.2/8.15.2) with ESMTPSA id 081AThPk009998 (version=TLSv1 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Tue, 1 Sep 2020 11:29:44 +0100 (BST) (envelope-from David.Allsopp@cl.cam.ac.uk) Received: from remus.metastack.local (27.77-31-62.static.virginmediabusiness.co.uk [62.31.77.27]) by romulus.metastack.com (8.14.2/8.14.2) with ESMTP id 081ATg5S021460 (version=TLSv1/SSLv3 cipher=AES256-SHA bits=256 verify=NO) for ; Tue, 1 Sep 2020 11:29:42 +0100 Received: from Hermes.metastack.local (172.16.0.8) by Hermes.metastack.local (172.16.0.8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Tue, 1 Sep 2020 11:29:45 +0100 Received: from Hermes.metastack.local ([fe80::210d:d258:cd04:7b5a]) by Hermes.metastack.local ([fe80::210d:d258:cd04:7b5a%2]) with mapi id 15.01.1979.003; Tue, 1 Sep 2020 11:29:45 +0100 From: David Allsopp To: "cygwin@cygwin.com" Subject: RE: [ANNOUNCEMENT] unison2.48-2.48.4-2 (Warning: possible breakage) Thread-Topic: [ANNOUNCEMENT] unison2.48-2.48.4-2 (Warning: possible breakage) Thread-Index: AQHWf9mrcws+AcsuR0Oazo01y/ixzKlSthIAgAA693GAAJ+WYA== Date: Tue, 1 Sep 2020 10:29:44 +0000 Message-ID: <6ab4bc7a6011486c9f8ba5ae42000bda@metastack.com> References: <0e456fd0-0beb-6f04-40d7-836ed8b64612@cornell.edu> In-Reply-To: Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [172.16.0.125] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.65 on 62.31.77.26 X-Server-Quench: 0d3d36a5-ec3e-11ea-80b4-84349711df28 X-AuthReport-Spam: If SPAM / abuse - report it at: http://www.authsmtp.com/abuse X-AuthRoute: OCd1ZAARAlZ5RRob BmUtCCtbTh09DhZI RxQKKE1TKxwUVhJa I0lFL1x7O0wTWlBf HTVUBhpUUUISDCNq aQpTbRVcY0BMVg9u VAZPQExRFRtvBgID AAEcVwZzOQVOeQ8U PSY5XnBSVU1yO0J8 QkYaFTkFMWRmOWUC BRNbIh5VcVYbYxdF OFRiXHcOZWwAZ3s0 EVVjKQocb31sAQJz ZTwrBn83bGA3K3Yh QREZGjN1WxFVAn91 c0xgdhtGVAYuO180 MF0uCxoANAQJCwda EglHGiJQJFAOSmtD X-Authentic-SMTP: 61633634383431.1021:7416 X-AuthFastPath: 0 (Was 255) X-AuthSMTP-Origin: 62.31.77.26/25 X-AuthVirus-Status: No virus detected - but ensure you scan with your own anti-virus system. X-Spam-Status: No, score=-3.4 required=5.0 tests=BAYES_00, KAM_DMARC_STATUS, RCVD_IN_DNSWL_LOW, SPF_HELO_NONE, SPF_NEUTRAL, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: cygwin@cygwin.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: General Cygwin discussions and problem reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 01 Sep 2020 10:29:48 -0000 Andrew Schulman 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! >=20 > Glad you understand :) >=20 > > 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. >=20 > Yes, I could do that. I was hoping to avoid it, but it may be the only > realistic solution. >=20 > 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. >=20 > > 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. Just for reference, the format of OCaml marshalled values changed in OCaml = 4.08 (https://github.com/ocaml/ocaml/pull/1683). It's changed again in OCam= l 4.11 as well (https://github.com/ocaml/ocaml/pull/8791) but in that case = the new things which OCaml 4.11 can marshal would have caused errors in ear= lier versions, so I don't think that will affect Unison. Quoting https://caml.inria.fr/pub/docs/manual-ocaml/libref/Marshal.html (em= phasis mine): "The format for the byte sequences is compatible across all m= achines **for a given version of OCaml**" so it's an interesting design cho= ice of Unison's. That said, we (OCaml devs) change the marshal format as infrequently as pos= sible, and go to considerable lengths to ensure that the older format can b= e read by newer runtimes: IIRC that particular change was the first break s= ince OCaml 4.01 (Sep 2013). David