Verify JDK 9 classes.

.github/workflows/nightly-builds.yml

@@ -179,3 +179,21 @@ jobs:
           sbt \
             -Dpekko.build.scalaVersion=${{ matrix.scalaVersion }} \
             "+~ ${{ matrix.scalaVersion }} publishLocal publishM2"
+
+      - name: Install scala-cli
+        if: ${{ contains('11,17,21', matrix.javaVersion) }}
+        run: |-
+          curl -sS "https://virtuslab.github.io/scala-cli-packages/KEY.gpg" | sudo gpg --dearmor  -o /etc/apt/trusted.gpg.d/scala-cli.gpg 2>/dev/null
+          sudo curl -s --compressed -o /etc/apt/sources.list.d/scala_cli_packages.list "https://virtuslab.github.io/scala-cli-packages/debian/scala_cli_packages.list"
+          sudo apt update
+          sudo apt install scala-cli
+
+      - name: Use Scala-CLI to verify jdk 9 classes
+        if: ${{ contains('11,17,21', matrix.javaVersion) }}
+        run: |-
+          scala-cli --version
+          echo "Starting verification with Scala-CLI"
+          scala-cli stream/target/scala-cli/VerifyJDK9Classes.sc && echo "Verification successful" || (
+          echo "Error when VerifyJDK9Classes"
+          exit 1
+          )

build.sbt

@@ -436,6 +436,7 @@ lazy val stream = pekkoModule("stream")
   .settings(AutomaticModuleName.settings("pekko.stream"))
   .settings(OSGi.stream)
   .settings(Protobuf.settings)
+  .settings(VerifyJDK9Classes.settings)
   .enablePlugins(BoilerplatePlugin, Jdk9, SbtOsgi)
 
 lazy val streamTestkit = pekkoModule("stream-testkit")

project/VerifyJDK9Classes.scala

@@ -0,0 +1,85 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+object VerifyJDK9Classes {
+  import sbt._
+  import sbt.Keys._
+
+  lazy val settings: Seq[Setting[_]] = inConfig(Compile) {
+    Seq {
+      sourceGenerators += {
+        generateAndWriteScalaCLIScript(
+          target,
+          _ / "scala-cli" / "VerifyJDK9Classes.sc")
+      }
+    }
+  }
+
+  def generateAndWriteScalaCLIScript(dir: SettingKey[File], locate: File => File): Def.Initialize[Task[Seq[sbt.File]]] =
+    Def.task[Seq[File]] {
+      val script = generateScalaCLIScript(version.value)
+      val file = locate(dir.value)
+      val content = script.stripMargin.format(version.value)
+      if (!file.exists || IO.read(file) != content) IO.write(file, content)
+      // the generated file is not used.
+      Nil
+    }
+
+  private def generateScalaCLIScript(version: String): String =
+    s"""
+      |/*
+      | * Licensed to the Apache Software Foundation (ASF) under one or more
+      | * contributor license agreements. See the NOTICE file distributed with
+      | * this work for additional information regarding copyright ownership.
+      | * The ASF licenses this file to You under the Apache License, Version 2.0
+      | * (the "License"); you may not use this file except in compliance with
+      | * the License. You may obtain a copy of the License at
+      | *
+      | *    http://www.apache.org/licenses/LICENSE-2.0
+      | *
+      | * Unless required by applicable law or agreed to in writing, software
+      | * distributed under the License is distributed on an "AS IS" BASIS,
+      | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+      | * See the License for the specific language governing permissions and
+      | * limitations under the License.
+      | */
+      |//> using scala 2.13
+      |//> using dep "org.apache.pekko::pekko-stream:${version}"
+      |////> using jvm 11
+      |object VerifyJDK9Classes {
+      |  def main(args: Array[String]): Unit = {
+      |    import org.apache.pekko.actor.ActorSystem
+      |    import org.apache.pekko.stream.scaladsl.{ JavaFlowSupport, Source }
+      |
+      |    import java.lang.System.exit
+      |    import scala.concurrent.Await
+      |    import scala.concurrent.duration.DurationInt
+      |    implicit val system: ActorSystem = ActorSystem.create("test")
+      |    val future = Source(1 to 3).runWith(
+      |      JavaFlowSupport.Sink.asPublisher[Int](fanout = false).mapMaterializedValue { p =>
+      |        JavaFlowSupport.Source.fromPublisher(p).runFold(0)(_ + _)
+      |      })
+      |
+      |    val result = Await.result(future, 3.seconds)
+      |    println(s"Result:" + result)
+      |    system.terminate()
+      |    exit(if (result == 6) 0 else 1)
+      |  }
+      |}
+      |
+      |""".stripMargin
+}