JDK compatibility needs tooling info for JDK 25

[SethTisue]

as followup to #3215

currently we have:

| JDK         | scala-cli  | sbt       | mill       |
|:-----------:|:----------:|:---------:|:-----------|
| 23          | 1.4.1      | 1.9.0     | 0.11.8     |
| 21 (LTS)    | 1.0.0      | 1.9.0     | 0.11.5     |
| 17 (LTS)    | 1.0.0      | 1.6.0     | 0.7.0      |
| 11 (LTS)    | 1.0.0      | 1.1.0     | 0.1.5      |
| 8 (LTS)     | 1.0.0      | 1.0.0     | 0.1.0      |

We will update this table soon to include information about JDK 25. <!-- TODO -->

I want to remove the "23" line and add a "25 (LTS)" line

@eed3si9n what should the sbt column say?
@Gedochao what should the scala-cli column say?
@lefou what should the mill column say?

[eed3si9n]

I'm not 100% sure. On one hand, I see pull requests like sbt/sbt#8284 being able to build on JDK 25, but on the other hand due to scala/scala#11028 we should wait till Scala 2 releases 2.12.21 with new ASM?

[SethTisue]

@eed3si9n I think it's unlikely that people will need to run the optimizer from their build definition, so I think it would be okay to ignore that issue. for the purposes of this table, it's enough that things basically work, we don't require zero possibility of trouble

also the Scala 2 community build is on JDK 25 and sbt 1.11.6 and works fine. one possibility would be to be cautious and put 1.11.6 even though earlier versions probably work too; another possibility would be to put an older version that has the last potentially related bugfix that you can think of. as you see fit

[eed3si9n]

As far as I know, sbt 1.9.0 should work fine. It feels consistent to list the minimal version, since otherwise I would recommend using latest for any JDKs.

Note that there is a bug reported about sbt 1.11.6 runner displaying a lot of warnings on startup (sbt/sbt#8286), likely due to Scala 3's use of Unsafe, since the Launcher code now uses Scala 3.

[xuwei-k]

another sbt issues

• JEP 472: WARNING: java.lang.System::load has been called by org.scalasbt.ipcsocket.NativeLoader since JDK 24 sbt/sbt#7634
• Support for Java 24 (without sun.misc.Unsafe warning) sbt/sbt#8073

[SethTisue]

I suppose I could add some wording about "build tools may print harmless warnings on startup on JDK 25"

[eed3si9n]

I suggest an asterisk saying

sbt documentation currently recommends JDK 8, 11, or 17. Use any other JDKs at your own risk.

[Gedochao]

I ran the Scala CLI test suite for JDK 25 at VirtusLab/scala-cli#3874
I merged the PR adding JDK 25 to the Coursier JVM Index today morning, too: coursier/jvm-index#363
With the JVM Index updated, users should already be able to try it out with --jvm 25.
The ugly warnings about LazyVal won't go away until we solve scala/scala3#9013 (which we have to in 3.8.0 anyway).
I will update here once I have any confidence how the support for Scala CLI with JVM 25 looks like.

[lefou]

Mill 1.0.0 is compatible with Java 25. I also plan to cut a 0.12.16 maintenance release to support Java 25, but it's not there yet.

[SethTisue]

@eed3si9n is this somewhat toned-down wording okay?

The sbt developers have primarily tested on JDK 8, 11, and 17,
but 21 and 25 are believed to also work.

[SethTisue]

I pushed e4c60b7 with what we know so far