Require Java 11 for the build

.github/workflows/build-test-prValidation.yml

@@ -25,11 +25,11 @@ jobs:
       - name: Cache Coursier cache
         uses: coursier/cache-action@v6
 
-      - name: Setup Java 8
+      - name: Setup Java 11
         uses: actions/setup-java@v4
         with:
           distribution: temurin
-          java-version: 8
+          java-version: 11
 
       - name: Code style check
         run: |-
@@ -49,11 +49,11 @@ jobs:
           fetch-depth: 0
           fetch-tags: 0
 
-      - name: Setup Java 8
+      - name: Setup Java 11
         uses: actions/setup-java@v4
         with:
           distribution: temurin
-          java-version: 8
+          java-version: 11
 
       - name: Cache Coursier cache
         uses: coursier/cache-action@v6

.github/workflows/headers.yml

@@ -13,11 +13,11 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v4
 
-      - name: Setup Java 8
+      - name: Setup Java 11
         uses: actions/setup-java@v4
         with:
           distribution: temurin
-          java-version: 8
+          java-version: 11
 
       - name: Cache Coursier cache
         uses: coursier/cache-action@v6

.github/workflows/nightly-builds.yml

@@ -113,7 +113,7 @@ jobs:
         # binary version is required and Pekko build will set the right
         # full version from it.
         scalaVersion: ["2.12", "2.13", "3.3"]
-        javaVersion: [8, 11, 17, 21]
+        javaVersion: [11, 17, 21]
     steps:
       - name: Checkout
         uses: actions/checkout@v4

project/Doc.scala

@@ -140,10 +140,7 @@ object UnidocRoot extends AutoPlugin {
 
   lazy val pekkoSettings = UnidocRoot.CliOptions.genjavadocEnabled
     .ifTrue(Seq(
-      JavaUnidoc / unidoc / javacOptions := {
-        if (JdkOptions.isJdk8) Seq("-Xdoclint:none")
-        else Seq("-Xdoclint:none", "--ignore-source-errors", "--no-module-directories")
-      }))
+      JavaUnidoc / unidoc / javacOptions := Seq("-Xdoclint:none", "--ignore-source-errors", "--no-module-directories")))
     .getOrElse(Nil)
 
   override lazy val projectSettings = {
@@ -213,11 +210,7 @@ object BootstrapGenjavadoc extends AutoPlugin {
 
   override lazy val requires =
     UnidocRoot.CliOptions.genjavadocEnabled
-      .ifTrue {
-        // require 11, fail fast for 8, 9, 10
-        require(JdkOptions.isJdk11orHigher, "Javadoc generation requires at least jdk 11")
-        sbtunidoc.GenJavadocPlugin
-      }
+      .ifTrue(sbtunidoc.GenJavadocPlugin)
       .getOrElse(plugins.JvmPlugin)
 
   override lazy val projectSettings = UnidocRoot.CliOptions.genjavadocEnabled

project/Jdk9.scala

@@ -15,7 +15,6 @@ import sbt.Keys._
 import sbt._
 
 object Jdk9 extends AutoPlugin {
-  import JdkOptions.notOnJdk8
   import JdkOptions.JavaVersion._
 
   // The version 9 is special for any Java versions >= 9
@@ -59,15 +58,15 @@ object Jdk9 extends AutoPlugin {
 
   lazy val compileJdk9Settings = Seq(
     // following the scala-2.12, scala-sbt-1.0, ... convention
-    unmanagedSourceDirectories := notOnJdk8(additionalSourceDirectories.value),
-    scalacOptions := PekkoBuild.DefaultScalacOptions.value ++ notOnJdk8(Seq("-release", majorVersion.toString)),
-    javacOptions := PekkoBuild.DefaultJavacOptions ++ notOnJdk8(Seq("--release", majorVersion.toString)))
+    unmanagedSourceDirectories := additionalSourceDirectories.value,
+    scalacOptions := PekkoBuild.DefaultScalacOptions.value ++ Seq("-release", majorVersion.toString),
+    javacOptions := PekkoBuild.DefaultJavacOptions ++ Seq("--release", majorVersion.toString))
 
   lazy val testJdk9Settings = Seq(
     // following the scala-2.12, scala-sbt-1.0, ... convention
-    unmanagedSourceDirectories := notOnJdk8(additionalTestSourceDirectories.value),
-    scalacOptions := PekkoBuild.DefaultScalacOptions.value ++ notOnJdk8(Seq("-release", majorVersion.toString)),
-    javacOptions := PekkoBuild.DefaultJavacOptions ++ notOnJdk8(Seq("--release", majorVersion.toString)),
+    unmanagedSourceDirectories := additionalTestSourceDirectories.value,
+    scalacOptions := PekkoBuild.DefaultScalacOptions.value ++ Seq("-release", majorVersion.toString),
+    javacOptions := PekkoBuild.DefaultJavacOptions ++ Seq("--release", majorVersion.toString),
     compile := compile.dependsOn(CompileJdk9 / compile).value,
     classpathConfiguration := TestJdk9,
     externalDependencyClasspath := (Test / externalDependencyClasspath).value)
@@ -80,7 +79,7 @@ object Jdk9 extends AutoPlugin {
     // Since sbt-osgi upgrade to 0.9.5, the fullClasspath is no longer used on packaging when use sbt-osgi, so we have to
     // add jdk9 products to dependencyClasspathAsJars instead.
     //    Compile / fullClasspath ++= (CompileJdk9 / exportedProducts).value)
-    Compile / dependencyClasspathAsJars ++= notOnJdk8((CompileJdk9 / exportedProducts).value))
+    Compile / dependencyClasspathAsJars ++= (CompileJdk9 / exportedProducts).value)
 
   lazy val testSettings = Seq((Test / test) := {
     (Test / test).value

project/JdkOptions.scala

@@ -40,10 +40,6 @@ object JdkOptions extends AutoPlugin {
     }
   }
 
-  lazy val isJdk8: Boolean =
-    VersionNumber(specificationVersion).matchesSemVer(SemanticSelector(s"=1.8"))
-  lazy val isJdk11orHigher: Boolean =
-    VersionNumber(specificationVersion).matchesSemVer(SemanticSelector(">=11"))
   lazy val isJdk17orHigher: Boolean =
     VersionNumber(specificationVersion).matchesSemVer(SemanticSelector(">=17"))
 
@@ -55,8 +51,6 @@ object JdkOptions extends AutoPlugin {
       "--add-opens=java.base/java.nio=ALL-UNNAMED" :: Nil
     } else Nil
 
-  def notOnJdk8[T](values: Seq[T]): Seq[T] = if (isJdk8) Seq.empty[T] else values
-
   def targetJdkScalacOptions(
       targetSystemJdk: Boolean,
       jdk8home: Option[File],
@@ -66,7 +60,6 @@ object JdkOptions extends AutoPlugin {
       targetSystemJdk,
       jdk8home,
       fullJavaHomes,
-      Seq(if (scalaVersion.startsWith("3.")) "-Xtarget:8" else "release:8"),
       (java8home: File) => Seq("-release", "8"))
   def targetJdkJavacOptions(
       targetSystemJdk: Boolean,
@@ -76,7 +69,6 @@ object JdkOptions extends AutoPlugin {
       targetSystemJdk,
       jdk8home,
       fullJavaHomes,
-      Nil,
       // '-release 8' would be a neater option here, but is currently not an
       // option because it doesn't provide access to `sun.misc.Unsafe` https://github.com/akka/akka/issues/27079
       (java8home: File) => Seq("-source", "8", "-target", "8", "-bootclasspath", java8home + "/jre/lib/rt.jar"))
@@ -85,12 +77,9 @@ object JdkOptions extends AutoPlugin {
       targetSystemJdk: Boolean,
       jdk8home: Option[File],
       fullJavaHomes: Map[String, File],
-      jdk8options: Seq[String],
       jdk11options: File => Seq[String]): Seq[String] =
     if (targetSystemJdk)
       Nil
-    else if (isJdk8)
-      jdk8options
     else
       jdk8home.orElse(fullJavaHomes.get("8")) match {
         case Some(java8home) =>

project/PekkoBuild.scala

@@ -119,15 +119,6 @@ object PekkoBuild {
     }
   }
 
-  private def jvmGCLogOptions(isJdk11OrHigher: Boolean, isJdk8: Boolean): Seq[String] = {
-    if (isJdk11OrHigher)
-      // -Xlog:gc* is equivalent to -XX:+PrintGCDetails. See:
-      // https://docs.oracle.com/en/java/javase/11/tools/java.html#GUID-BE93ABDC-999C-4CB5-A88B-1994AAAC74D5
-      Seq("-Xlog:gc*")
-    else if (isJdk8) Seq("-XX:+PrintGCTimeStamps", "-XX:+PrintGCDetails")
-    else Nil
-  }
-
   // -XDignore.symbol.file suppresses sun.misc.Unsafe warnings
   final val DefaultJavacOptions = Seq("-encoding", "UTF-8", "-Xlint:unchecked", "-XDignore.symbol.file")
 
@@ -227,8 +218,10 @@ object PekkoBuild {
         // faster random source
         "-Djava.security.egd=file:/dev/./urandom")
 
+      // -Xlog:gc* is equivalent to -XX:+PrintGCDetails. See:
+      // https://docs.oracle.com/en/java/javase/11/tools/java.html#GUID-BE93ABDC-999C-4CB5-A88B-1994AAAC74D5
       defaults ++ CliOptions.runningOnCi
-        .ifTrue(jvmGCLogOptions(JdkOptions.isJdk11orHigher, JdkOptions.isJdk8))
+        .ifTrue(Seq("-Xlog:gc*"))
         .getOrElse(Nil) ++
       JdkOptions.versionSpecificJavaOptions
     },
@@ -327,10 +320,7 @@ object PekkoBuild {
   lazy val docLintingSettings = Seq(
     compile / javacOptions ++= Seq("-Xdoclint:none"),
     test / javacOptions ++= Seq("-Xdoclint:none"),
-    doc / javacOptions ++= {
-      if (JdkOptions.isJdk8) Seq("-Xdoclint:none")
-      else Seq("-Xdoclint:none", "--ignore-source-errors")
-    })
+    doc / javacOptions ++= Seq("-Xdoclint:none", "--ignore-source-errors"))
 
   def loadSystemProperties(fileName: String): Unit = {
     import scala.collection.JavaConverters._

project/TestExtras.scala

@@ -15,7 +15,6 @@ import sbt.Keys._
 import sbt._
 
 object TestExtras {
-  import JdkOptions.isJdk8
   object Filter {
     object Keys {
       lazy val excludeTestNames = settingKey[Set[String]](
@@ -61,17 +60,11 @@ object TestExtras {
           def shouldExist(description: String, filename: String): Unit =
             require(file(filename).exists, s"$description should be run as part of the build")
 
-          val baseList =
-            List(
-              "The java JavaExtension.java" -> "actor-tests/target/test-reports/TEST-org.apache.pekko.actor.JavaExtension.xml")
-          val jdk9Only = List(
+          val testsToCheck = List(
+            "The java JavaExtension.java" -> "actor-tests/target/test-reports/TEST-org.apache.pekko.actor.JavaExtension.xml",
             "The jdk9-only FlowPublisherSinkSpec.scala" -> "stream-tests/target/test-reports/TEST-org.apache.pekko.stream.scaladsl.FlowPublisherSinkSpec.xml",
             "The jdk9-only JavaFlowSupportCompileTest.java" -> "stream-tests/target/test-reports/TEST-org.apache.pekko.stream.javadsl.JavaFlowSupportCompileTest.xml")
 
-          val testsToCheck =
-            if (isJdk8) baseList
-            else baseList ::: jdk9Only
-
           testsToCheck.foreach((shouldExist _).tupled)
         })
     }