3.5.0 release thread

We’re working on it and need a bit more time. Sorry that we haven’t made it on time. We’re in the long process of backports and regression tests right now, but we’ve secured resources to ensure we can finish it quickly.
We’re going to start the release procedure for 3.5.0-RC2 tomorrow. The next LTS release might require at least 1 additional week.


at least should have a milestone created with 3.3.4 and added all the backports to that milestone

@WojciechMazur Will Java parser doesn't support JEP 409 sealed classes · Issue #18533 · scala/scala3 · GitHub be included in 3.3.4?

at least should have a milestone created with 3.3.4 and added all the backports to that milestone

Milestones are not used for backports with the exception of RC backports. In general milestones are rather used to group issues/prs required for next Scala Next release until it’s cut-off date. Instead, we use a dedicated GH project and dedicated tooling to streamline the process of backporting to the LTS scala3/project/RELEASES.md at main · scala/scala3 · GitHub

Will Java parser doesn’t support JEP 409 sealed classes · Issue #18533 · scala/scala3 · GitHub be included in 3.3.4?

Yes, but it requires some time. When backporting we try to follow the order of changes in the main branch to reduce the amount of conflicts. There is a long queue so please be patient, we’re working on it.


Thanks, we are using Java 21 With scala and need this before we migrate to Scala 3.3.x

@WojciechMazur what about backporting SIP-54 (multi-source extension methods) to LTS?

That is definitely out of policy for LTS. It is a language enhancement, not a bug fix. Moreover, it has a non-negligible chance of breaking someone’s source code somewhere.


This SIP really feels like a bugfix (and several issues posted as bugs are a testament to that), and the likelihood of code breaking in this case is far less than some far reaching fixes I’ve experienced in the LTS release thus far (that DID cause regressions). Something to consider.

I have no particular opinion on whether it’s appropriate to backport to 3.3–I agree it could break code–but I do think that extension methods are a toy feature not suitable for widespread use without the patch in.

So what I really don’t think would be good is messaging of “use extension methods! They’re great!” and also “Use 3.3 LTS!”.

Extension methods are great in 3.4.

Scala 3.5.0-RC2 is now available for testing.
The second RC besides bugfixes includes native binaries for the new Scala runner available for most of the popular platforms.


Will the next release upgrade the scala-library to 2.13.14, it currently is 2.13.12

The 2.13.14 upgrade is planned for RC3


2.13.14 confirmed as included, see https://mvnrepository.com/artifact/org.scala-lang/scala3-library_3/3.5.0-RC3. Thanks.


3.5.0-RC3 is available for testing. It comes with upgrade of Scala 2 library (now it’s using 2.13.14), improvements to new Scala runner and fixes to some of false-positive warnings.

We’re preparing the 3.5.0-RC4 as well to mitigate issues found just after publishing the RC3 artifacts. They should be available soon and we’ll inform you about details in the next notification. We’re hoping it will be the last RC for the 3.5.0.


Do We have plan for Document migration steps for changed rules for given prioritisation under 3.6 · Issue #20843 · scala/scala3 · GitHub before release 3.5.0? I think the implicit resolution is a big deal for the community.

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According to this comment 3.5 is currently bundled with Scala-cli 1.3.2.

I hope the final release can be bundled with the latest Scala-cli (1.4.0?) and also the latest Toolkit with latest libs (like os-lib for example). I had issues with Toolkit even on 3.4.2, it has an older os-lib I think.

yes, Scala 3.5.0 will use Scala CLI 1.4.0 and so default toolkit 0.4.0

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OK, I think my issue was that I’m using Scala-cli in a Native project, and os.proc was not yet supported in Native… toolkit 0.4.0 has os-lib 0.10.0 but the support was added in os-lib 0.10.2.

I’d appreciate it if these in the Toolkit are bumped, but I understand if it’s not possible / low priority


You guys are so fast, I love the community :heart: