I was talking about compiling Pekko. We already can't solve deprecation warnings from Scala 2.13 due to source compatibility for compiling with Scala 2.12. As Scala 3 continues to deprecate and remove old syntax we'll continue to run into issues keeping Scala 2.12 compiling.
On Fri, 24 Mar 2023 at 13:32, Matthew Benedict de Detrich <matthew.dedetr...@aiven.io.invalid> wrote: > > One precondition to upgrade to newer versions of Scala 3 would be > dropping > support for Scala 2.12. > Scala 2.13 at least has support for some of the Scala 3 Syntax with > compiler flags to cross compile. > > Are you talking about support on artifact level or on syntax level? Afaik > there isn't any plan for Scala 3.3 to drop support for Scala 2.13 artifacts > (artifacts are completely separated from supported syntax). If we are > talking about a hypothetical Scala 3 user of Pekko, the Scala3 syntax that > Pekko happens to use will be irrelevant here. In other words, if a user is > upgrading from Scala 3.1/Scala 3.2 to Scala 3.3 then they will have to > upgrade the syntax of the source code irrespective of Pekko. If we are > talking about difficulties of cross compiling for Scala 3/Scala 2 within > Pekko itself I think we would have to see if there are any syntax breaking > changes in this regard (I didn't see any for Scala 3.3 but I may have > missed something). Since an RC for Scala 3.3 is out we can pretty easily > figure out if this is going to be a problem right now. > > I think what Johannes said here is important, which is that currently there > aren't any users of Pekko Scala 3 and because of this we really shouldn't > overthink it. And even then, if we do release Pekko with Scala 3.3 and some > hypothetical user is going to have problems because they haven't upgrade to > Scala 3.3 yet, they can easily use the Pekko Scala 2.13 artifact and since > we are not using any bespoke Scala 3 features in Pekko currently on a > source level the user is actually not going to notice any difference. > > On Fri, Mar 24, 2023 at 1:18 PM Nicolas Vollmar <nvoll...@gmail.com> > wrote: > > > IMHO we should use the lowest supported version of Scala 3 to not force > > user to upgrade to newer versions. > > > > Scala 3 continues to deprecate old syntax. Some of it will produce > warnings > > in Scala 3.2 and may be removed in 3.3 or later. > > For example > > > https://dotty.epfl.ch/docs/reference/dropped-features/package-objects.html > > or https://dotty.epfl.ch/docs/reference/changed-features/imports.html > > > > One precondition to upgrade to newer versions of Scala 3 would be > dropping > > support for Scala 2.12. > > Scala 2.13 at least has support for some of the Scala 3 Syntax with > > compiler flags to cross compile. > > > > > > > > On Fri, 24 Mar 2023 at 10:26, Matthew Benedict de Detrich > > <matthew.dedetr...@aiven.io.invalid> wrote: > > > > > So some discussions on github are popping up regarding which Scala 3 > > > version we should pick so I think it's time to discuss this formally on > > the > > > mailing list. > > > > > > As a precursor one thing people need to understand is that the Scala 3 > > > release cycle has changed, quoting from > > > > > > https://github.com/apache/incubator-pekko/issues/6#issuecomment-1302701657 > > > > > > > Scala 2 used epoch.major.minor version convention. Scala 3 has > > > major.minor.patch. > > > > > > > So there is no 3.0/3.1/3.2/etc cross-compilation - the assumption is > > > that: > > > > > > > * you can compile against the same minor version with backward- and > > > forward-compatibility: 3.1.3 dependency against 3.1.0 code, 3.0.0 > > > dependency against 3.0.1 code, etc > > > > * within the same major version you always have > backward-compatibility: > > > 3.1.3 dependency can be used in 3.1.3 project, but also 3.2.0 project > and > > > in future against 3.3.0 project > > > > > > This means that if we pick a Scala version, we are essentially forcing > > the > > > potential Scala 3 users of Pekko to bump their Scala 3 version to the > > minor > > > that we decide on. On surface value this means that we should pick the > > > lowest Scala 3 minor version that we can support however there is the > > fact > > > that Scala 3.3 is going to come out soon which will be an LTS release. > > The > > > LTS release means that if any bugs are found after Scala 3.3 for a > period > > > of 2 years, they will be backported to Scala 3.3. The big advantage > this > > > brings us, is that it allows us to freely bump Scala 3.3 without > breaking > > > our users if any potential bugs are found in the future. If we decide > to > > > stick with Scala 3.2 or 3.1 and some bug is found in Scala 3 later on > > that > > > affects us, we will have to update to a version of Scala 3 that will > > break > > > binary compatibility. This facet is of even more importance when > > > considering our 1.0.x release branches, which are designed to never > break > > > binary/backwards compatibility, i.e. if we do 1.0.x releases with Scala > > > 3.1/3.2 and some critical bug/CVE comes out later we could potentially > be > > > forced to update the minor version which would break this > > binary/backwards > > > compatibility, this wouldn't be the case with Scala 3.3 (for a certain > > > period of time). > > > > > > Of course the counter argument to using Scala 3.3 is that it would > force > > > all potential Pekko users (and the transitive set of Scala 3 libraries > > for > > > that Pekko user) to also use/support Scala 3.3. Unfortunately its not > > > possible to get download stats from Sonatype for artifacts you don't > > > maintain, but I wouldn't say its a controversial statement that the > > amount > > > of people that use Akka long with Scala 3 would be a tiny minority > (this > > is > > > also regarding other factors, i.e. the typical demographic of Akka > > users). > > > Ontop of this we need to take into account the delay of current Akka > > users > > > migrating to Pekko, in other words by the time people migrate to using > > > Pekko the fact that its using Scala 3.3 LTS would likely be a non > concern > > > at that point in time. > > > > > > And finally another thing to note is that even in the worst case > > scenario, > > > nothing is stopping users from using Scala 2 artifacts from within > Scala > > 3 > > > (this is perfectly supported and has been for a while). Afaik the > current > > > Scala 3 version of Akka/Pekko is not using any unique/bespoke features > of > > > Scala 3, if true this would mean from a Scala 3 user perspective there > > > really isn't going to be > > > a difference in using a Scala 2 artifact vs Scala 3 artifact. > > > > > > For these reasons my recommendation would be, assuming that the full > > > release of Scala 3.3 LTS is ready by the time we decide to make a > release > > > that we should try and target that. For details on the current release > > > schedule for Scala 3.3 LTS you can read > > > https://contributors.scala-lang.org/t/3-3-0-release-thread/6079/3. > > > > > > -- > > > > > > Matthew de Detrich > > > > > > *Aiven Deutschland GmbH* > > > > > > Immanuelkirchstraße 26, 10405 Berlin > > > > > > Amtsgericht Charlottenburg, HRB 209739 B > > > > > > Geschäftsführer: Oskari Saarenmaa & Hannu Valtonen > > > > > > *m:* +491603708037 > > > > > > *w:* aiven.io *e:* matthew.dedetr...@aiven.io > > > > > > > > -- > > Matthew de Detrich > > *Aiven Deutschland GmbH* > > Immanuelkirchstraße 26, 10405 Berlin > > Amtsgericht Charlottenburg, HRB 209739 B > > Geschäftsführer: Oskari Saarenmaa & Hannu Valtonen > > *m:* +491603708037 > > *w:* aiven.io *e:* matthew.dedetr...@aiven.io >
