Build on Java 21 (but keep JDK 8 compatibility)

.github/scripts/ci.sh

@@ -25,11 +25,9 @@ if [ "$IS_UNIX" == "true" ]; then
   sbt \
     'set version in ThisBuild := "'"$TEST_VERSION"'"' \
     publishLocal
-  echo "Running JDK 11 tests…"
-  # test that things work from JDK 11
-  # not actually building things from it, running into weird proguard issues…
+  echo "Running JDK 8 tests…"
 
-  TEST_JDK="adopt:1.11.0-7"
+  TEST_JDK="adoptium:8"
   eval "$(cs java --jvm "$TEST_JDK" --env)"
 
   java -Xmx32m -version

.github/workflows/ci.yml

@@ -23,7 +23,7 @@ jobs:
     - uses: coursier/cache-action@v6
     - uses: coursier/setup-action@v1.3
       with:
-        jvm: 8
+        jvm: 21
         apps: sbt
     - name: Test
       run: ./.github/scripts/ci.sh
@@ -40,7 +40,7 @@ jobs:
     - uses: coursier/cache-action@v6
     - uses: coursier/setup-action@v1.3
       with:
-        jvm: 8
+        jvm: 21
     - run: .github/scripts/gpg-setup.sh
       shell: bash
       env:

build.sbt

@@ -19,6 +19,8 @@ inThisBuild(List(
 
 lazy val finalPackageBin = taskKey[File]("")
 
+lazy val isJava9OrMore = sys.props.get("java.version").exists(!_.startsWith("1."))
+
 lazy val interface = project
   .enablePlugins(SbtProguard)
   .settings(
@@ -121,11 +123,13 @@ lazy val interface = project
         "-keep class coursierapi.** {\n  public protected *;\n}"
       )
 
-      val isJava9OrMore = sys.props.get("java.version").exists(!_.startsWith("1."))
       val maybeJava9Options =
         if (isJava9OrMore) {
           val javaHome = sys.props.getOrElse("java.home", ???)
-          Seq(s"-libraryjars $javaHome/jmods/java.base.jmod")
+          Seq(
+            s"-libraryjars $javaHome/jmods/java.base.jmod",
+            s"-libraryjars $javaHome/jmods/java.xml.jmod"
+          )
         }
         else
           Nil

project/Settings.scala

@@ -3,21 +3,50 @@ import com.typesafe.tools.mima.plugin.MimaPlugin
 import sbt._
 import sbt.Keys._
 
+import scala.util.Properties
+
+import java.util.Locale
+
 object Settings {
 
   def scala213 = "2.13.15"
 
   def scala212 = "2.12.20"
 
+  private def isArm64 =
+    Option(System.getProperty("os.arch")).map(_.toLowerCase(Locale.ROOT)) match {
+      case Some("aarch64" | "arm64") => true
+      case _                         => false
+    }
+  private lazy val java8Home = Option(System.getenv("COURSIER_INTERFACE_JAVA8_HOME")).getOrElse {
+    val jvmId =
+      if (Properties.isMac && isArm64)
+        // no native JDK 8 on Mac ARM, using amd64 one
+        "https://github.com/adoptium/temurin8-binaries/releases/download/jdk8u432-b06/OpenJDK8U-jdk_x64_mac_hotspot_8u432b06.tar.gz"
+      else
+        "adoptium:8"
+    os.proc("cs", "java-home", "--jvm", jvmId)
+      .call()
+      .out.trim()
+  }
+  private lazy val rtJar = {
+    val path = os.Path(java8Home) / "jre/lib/rt.jar"
+    assert(os.isFile(path))
+    path
+  }
   lazy val shared = Seq(
     scalaVersion := scala213,
     crossScalaVersions := Seq(scala213, scala212),
-    scalacOptions += "-target:jvm-1.8",
+    scalacOptions ++= Seq("--release", "8"),
     javacOptions ++= Seq(
-      "-source", "1.8",
-      "-target", "1.8"
+      "-source", "8",
+      "-target", "8",
+      "-bootclasspath", rtJar.toString
     ),
-    Compile / doc / javacOptions := Seq("-source", "1.8")
+    Compile / doc / javacOptions := Seq(
+      "-source", "8",
+      "-bootclasspath", rtJar.toString
+    )
   )
 
   private val filterOut = Set("0.0.1")

project/plugins.sbt

@@ -3,3 +3,5 @@ addSbtPlugin("com.typesafe" % "sbt-mima-plugin" % "0.8.1")
 addSbtPlugin("com.lightbend.sbt" % "sbt-proguard" % "0.4.0")
 
 libraryDependencies += "com.eed3si9n.jarjarabrams" %% "jarjar-abrams-core" % "1.14.0"
+
+libraryDependencies += "com.lihaoyi" %% "os-lib" % "0.11.3"