Re: [MirageOS-devel] supported OCaml versions

[Hannes Mehnert <hannes@xxxxxxxxxxx>]

On 23/11/2017 12:00, Martin Lucina wrote:
> IMO should definitely test 4.05.0, given the number of changes required for
> 4.06.0, its relative newness, and current lack of support in mirage-xen.

Ok, fair enough.  We can test 4.04.2, 4.05 and 4.06.  Once 4.07 is
released, should we then remove 4.04 -- i.e. try to have the three most
recent OCaml major releases supported?

> I'm keen on narrowing down the number of supported versions also for Solo5
> and related packages. This will have the benefit of reducing wasted CI (and
> thus developer) time.

Yes!

> If the consensus is that we support >= 4.04.2 in Mirage as a whole, then
> for ocaml-freestanding, mirage-solo5, mirage-*-solo5 I would go with the
> following steps:
> 
> 1. Document the >= 4.04.2 requirement somewhere. Probably in the
> mirage-solo5 and ocaml-freestanding READMEs since I don't know of a better
> place at this stage.

That sounds very reasonable.  We should also ensure that mirage.io
reflects this constraints in installation instructions.

> 2. Add an explicit "available: [ ocaml-version >= "4.04.2" ]" constraint to
> all affected packages, and get that propagated to opam-repository.

This is what I did in several PRs to mirage repositories.  Mirage 3.0.6
(currently PRed to opam-repository) already contains the >= "4.04.2"
constraints.

> 3. Remove OCaml versions < 4.04.2 from Travis CI for all affected packages.
> 
> 4. Ideally Datakit CI should also no longer test on the old compiler
> versions to prevent spurious failures, presumably the right thing will
> happen there due to the availability constraints automatically?
> 
> My justification for point 2. is that if we're no longer testing on those
> compilers then you should not be able to install the package on them
> either.
> 
> WDYT?

I think this is a great plan, and haven't heard from anyone who needs
interoperation with older OCaml compilers.


hannes

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