Use intermediate abstract classes to work around SPARK-3266

Author: JoshRosen

core/src/main/scala/org/apache/spark/api/java/JavaDoubleRDD.scala

@@ -32,7 +32,8 @@ import org.apache.spark.storage.StorageLevel
 import org.apache.spark.util.StatCounter
 import org.apache.spark.util.Utils
 
-class JavaDoubleRDD(val srdd: RDD[scala.Double]) extends JavaRDDLike[JDouble, JavaDoubleRDD] {
+class JavaDoubleRDD(val srdd: RDD[scala.Double])
+  extends AbstractJavaRDDLike[JDouble, JavaDoubleRDD] {
 
   override val classTag: ClassTag[JDouble] = implicitly[ClassTag[JDouble]]
 

core/src/main/scala/org/apache/spark/api/java/JavaPairRDD.scala

@@ -44,7 +44,7 @@ import org.apache.spark.util.Utils
 
 class JavaPairRDD[K, V](val rdd: RDD[(K, V)])
                        (implicit val kClassTag: ClassTag[K], implicit val vClassTag: ClassTag[V])
-  extends JavaRDDLike[(K, V), JavaPairRDD[K, V]] {
+  extends AbstractJavaRDDLike[(K, V), JavaPairRDD[K, V]] {
 
   override def wrapRDD(rdd: RDD[(K, V)]): JavaPairRDD[K, V] = JavaPairRDD.fromRDD(rdd)
 

core/src/main/scala/org/apache/spark/api/java/JavaRDD.scala

@@ -30,7 +30,7 @@ import org.apache.spark.storage.StorageLevel
 import org.apache.spark.util.Utils
 
 class JavaRDD[T](val rdd: RDD[T])(implicit val classTag: ClassTag[T])
-  extends JavaRDDLike[T, JavaRDD[T]] {
+  extends AbstractJavaRDDLike[T, JavaRDD[T]] {
 
   override def wrapRDD(rdd: RDD[T]): JavaRDD[T] = JavaRDD.fromRDD(rdd)
 

core/src/main/scala/org/apache/spark/api/java/JavaRDDLike.scala

@@ -38,6 +38,14 @@ import org.apache.spark.rdd.RDD
 import org.apache.spark.storage.StorageLevel
 import org.apache.spark.util.Utils
 
+/**
+ * As a workaround for https://issues.scala-lang.org/browse/SI-8905, implementations
+ * of JavaRDDLike should extend this dummy abstract class instead of directly inheriting
+ * from the trait. See SPARK-3266 for additional details.
+ */
+private[spark] abstract class AbstractJavaRDDLike[T, This <: JavaRDDLike[T, This]]
+  extends JavaRDDLike[T, This]
+
 /**
  * Defines operations common to several Java RDD implementations.
  * Note that this trait is not intended to be implemented by user code.

streaming/src/main/scala/org/apache/spark/streaming/api/java/JavaDStream.scala

@@ -36,7 +36,7 @@ import org.apache.spark.streaming.dstream.DStream
  * [[org.apache.spark.streaming.api.java.JavaPairDStream]].
  */
 class JavaDStream[T](val dstream: DStream[T])(implicit val classTag: ClassTag[T])
-    extends JavaDStreamLike[T, JavaDStream[T], JavaRDD[T]] {
+    extends AbstractJavaDStreamLike[T, JavaDStream[T], JavaRDD[T]] {
 
   override def wrapRDD(rdd: RDD[T]): JavaRDD[T] = JavaRDD.fromRDD(rdd)
 

streaming/src/main/scala/org/apache/spark/streaming/api/java/JavaDStreamLike.scala

@@ -34,6 +34,15 @@ import org.apache.spark.streaming._
 import org.apache.spark.streaming.api.java.JavaDStream._
 import org.apache.spark.streaming.dstream.DStream
 
+/**
+ * As a workaround for https://issues.scala-lang.org/browse/SI-8905, implementations
+ * of JavaDStreamLike should extend this dummy abstract class instead of directly inheriting
+ * from the trait. See SPARK-3266 for additional details.
+ */
+private[streaming]
+abstract class AbstractJavaDStreamLike[T, This <: JavaDStreamLike[T, This, R],
+  R <: JavaRDDLike[T, R]] extends JavaDStreamLike[T, This, R]
+
 trait JavaDStreamLike[T, This <: JavaDStreamLike[T, This, R], R <: JavaRDDLike[T, R]]
     extends Serializable {
   implicit val classTag: ClassTag[T]

streaming/src/main/scala/org/apache/spark/streaming/api/java/JavaPairDStream.scala

@@ -45,7 +45,7 @@ import org.apache.spark.streaming.dstream.DStream
 class JavaPairDStream[K, V](val dstream: DStream[(K, V)])(
     implicit val kManifest: ClassTag[K],
     implicit val vManifest: ClassTag[V])
-    extends JavaDStreamLike[(K, V), JavaPairDStream[K, V], JavaPairRDD[K, V]] {
+    extends AbstractJavaDStreamLike[(K, V), JavaPairDStream[K, V], JavaPairRDD[K, V]] {
 
   override def wrapRDD(rdd: RDD[(K, V)]): JavaPairRDD[K, V] = JavaPairRDD.fromRDD(rdd)