Major Description
ScalaReflection.dataTypeFor fails when Array[T] has been aliased for some T, and then the alias is being used as a component of e.g. a product.
Minimal example, tested in version 3.1.2:
type Data = Array[Long] val xs:List[(Data,Int)] = List((Array(1),1), (Array(2),2)) sc.parallelize(xs).toDF("a", "b")
This gives the following exception:
scala.MatchError: Data (of class scala.reflect.internal.Types$AliasNoArgsTypeRef)
at org.apache.spark.sql.catalyst.ScalaReflection$.$anonfun$dataTypeFor$1(ScalaReflection.scala:104)
at scala.reflect.internal.tpe.TypeConstraints$UndoLog.undo(TypeConstraints.scala:69)
at org.apache.spark.sql.catalyst.ScalaReflection.cleanUpReflectionObjects(ScalaReflection.scala:904)
at org.apache.spark.sql.catalyst.ScalaReflection.cleanUpReflectionObjects$(ScalaReflection.scala:903)
at org.apache.spark.sql.catalyst.ScalaReflection$.cleanUpReflectionObjects(ScalaReflection.scala:49)
at org.apache.spark.sql.catalyst.ScalaReflection$.dataTypeFor(ScalaReflection.scala:88)
at org.apache.spark.sql.catalyst.ScalaReflection$.$anonfun$serializerFor$6(ScalaReflection.scala:573)
at scala.collection.TraversableLike.$anonfun$map$1(TraversableLike.scala:238)
at scala.collection.immutable.List.foreach(List.scala:392)
at scala.collection.TraversableLike.map(TraversableLike.scala:238)
at scala.collection.TraversableLike.map$(TraversableLike.scala:231)
at scala.collection.immutable.List.map(List.scala:298)
at org.apache.spark.sql.catalyst.ScalaReflection$.$anonfun$serializerFor$1(ScalaReflection.scala:562)
at scala.reflect.internal.tpe.TypeConstraints$UndoLog.undo(TypeConstraints.scala:69)
at org.apache.spark.sql.catalyst.ScalaReflection.cleanUpReflectionObjects(ScalaReflection.scala:904)
at org.apache.spark.sql.catalyst.ScalaReflection.cleanUpReflectionObjects$(ScalaReflection.scala:903)
at org.apache.spark.sql.catalyst.ScalaReflection$.cleanUpReflectionObjects(ScalaReflection.scala:49)
at org.apache.spark.sql.catalyst.ScalaReflection$.serializerFor(ScalaReflection.scala:432)
at org.apache.spark.sql.catalyst.ScalaReflection$.$anonfun$serializerForType$1(ScalaReflection.scala:421)
at scala.reflect.internal.tpe.TypeConstraints$UndoLog.undo(TypeConstraints.scala:69)
at org.apache.spark.sql.catalyst.ScalaReflection.cleanUpReflectionObjects(ScalaReflection.scala:904)
at org.apache.spark.sql.catalyst.ScalaReflection.cleanUpReflectionObjects$(ScalaReflection.scala:903)
at org.apache.spark.sql.catalyst.ScalaReflection$.cleanUpReflectionObjects(ScalaReflection.scala:49)
at org.apache.spark.sql.catalyst.ScalaReflection$.serializerForType(ScalaReflection.scala:413)
at org.apache.spark.sql.catalyst.encoders.ExpressionEncoder$.apply(ExpressionEncoder.scala:55)
at org.apache.spark.sql.Encoders$.product(Encoders.scala:285)
at org.apache.spark.sql.LowPrioritySQLImplicits.newProductEncoder(SQLImplicits.scala:251)
at org.apache.spark.sql.LowPrioritySQLImplicits.newProductEncoder$(SQLImplicits.scala:251)
at org.apache.spark.sql.SQLImplicits.newProductEncoder(SQLImplicits.scala:32)
... 48 elided
At first glance, I think this could be fixed by changing e.g.
getClassNameFromType(tpe) to getClassNameFromType(tpe.dealias)
in ScalaReflection.dataTypeFor. I will try to test that and submit a pull request shortly.
