JDK 17+ compatibility: JCTools 4.x, suppress deprecation warnings, expand CI matrix

[halotukozak]

Summary

Dependencies

• JCTools 3.3.0 → 4.0.5

CI

• Expand JVM test matrix: Java 11 → Java 11, 17, 21, 25

Deprecation suppressions

Add @nowarn("msg=deprecated") to suppress warnings that appear on newer JDKs but are absent on JDK 11:

• Thread.getId (deprecated since JDK 19) — Platform, DynamicWorkerThreadFactory, StandardWorkerThreadFactory, ThreadFactoryBuilder
• sun.misc.Unsafe — FromMessagePassingQueue, FromCircularQueue
• -Wconf:cat=unused-nowarn:s in build.sbt to prevent the above @nowarn annotations from being flagged as unused on JDK 11

Test plan

• CI green on Java 11, 17, 21, 25
• sbt +compile passes on all Scala versions
• sbt +test passes (JVM)

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Updates Monix’s build/tooling and CI to improve compatibility with newer JDKs (incl. JDK 25), modernizes GitHub Actions, and bumps key build dependencies (including JCTools).

Changes:

• Bumped build tooling and plugins (SBT 1.10.7, sbt plugins, scalac/tpolecat configuration) and updated JCTools to 4.0.5.
• Replaced Unsafe.fullFence() usage with VarHandle.fullFence() in two JVM queue adapters.
• Modernized CI workflows (actions v4, ubuntu-latest, expanded JVM test matrix to JDK 8/11/21/25).

Reviewed changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
project/plugins.sbt	Updates sbt plugin versions; adds a dependency scheme override for geny.
project/build.properties	Bumps sbt version to 1.10.7.
monix-execution/shared/src/main/scala/monix/execution/CancelablePromise.scala	Suppresses an exhaustivity warning for a list destructure.
monix-execution/jvm/src/main/scala/monix/execution/internal/collection/queues/FromMessagePassingQueue.scala	Switches fencing implementation to VarHandle.fullFence().
monix-execution/jvm/src/main/scala/monix/execution/internal/collection/queues/FromCircularQueue.scala	Switches fencing implementation to VarHandle.fullFence().
build.sbt	Bumps versions (JCTools, plugins) and adjusts scalac/tpolecat options.
.jvmopts	Removes a deprecated JVM option (CMSClassUnloadingEnabled).
.gitignore	Ignores .planning/.
.github/workflows/build.yml	Modernizes actions/runners; expands JVM matrix and updates Scala versions.

Comments suppressed due to low confidence (1)

.github/workflows/build.yml:104

• Node.js 14 is end-of-life and may eventually stop being available on GitHub-hosted runners / receive security updates. Since this workflow is being modernized, consider bumping node-version to a supported LTS (e.g. 18 or 20) unless Scala.js tooling here explicitly requires 14.

      - name: Setup NodeJS
        uses: actions/setup-node@v4
        with:
          node-version: 14

---

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[mikkolaj]

This fixes error reporting for ForkJoinPool, but I think case ref: ScheduledExecutorService => branch is still broken. Try adding this test suite:

object ScheduledExecutorSuite extends ExecutorSchedulerSuite {
  def setup(): SchedulerService =
    monix.execution.Scheduler(Executors.newSingleThreadScheduledExecutor(), reporter = testsReporter)
}

For me it fails the same way ForkJoinPool did before the fix.