Change theSeq to immtuable.Seq

Author: lrytz

build.sbt

@@ -82,6 +82,7 @@ lazy val xml = crossProject(JSPlatform, JVMPlatform, NativePlatform)
         ProblemFilters.exclude[ReversedMissingMethodProblem]("scala.xml.Attribute.value"),
         ProblemFilters.exclude[ReversedMissingMethodProblem]("scala.xml.MetaData.apply"),
         ProblemFilters.exclude[ReversedMissingMethodProblem]("scala.xml.MetaData.value"),
+        ProblemFilters.exclude[ReversedMissingMethodProblem]("scala.xml.NodeSeq.theSeq"),
 
         // Synthetic static accessors (for Java interop) have a changed return type
         ProblemFilters.exclude[IncompatibleResultTypeProblem]("scala.xml.Null.apply"),
@@ -95,6 +96,9 @@ lazy val xml = crossProject(JSPlatform, JVMPlatform, NativePlatform)
         ProblemFilters.exclude[IncompatibleSignatureProblem]("scala.xml.PrefixedAttribute.value"),
         ProblemFilters.exclude[IncompatibleSignatureProblem]("scala.xml.UnprefixedAttribute.apply"),
         ProblemFilters.exclude[IncompatibleSignatureProblem]("scala.xml.UnprefixedAttribute.value"),
+        ProblemFilters.exclude[IncompatibleSignatureProblem]("scala.xml.Document.theSeq"),
+        ProblemFilters.exclude[IncompatibleSignatureProblem]("scala.xml.Group.theSeq"),
+        ProblemFilters.exclude[IncompatibleSignatureProblem]("scala.xml.Node.theSeq"),
 
         // Option[c.Seq] => Option[i.Seq] results in a changed generic signature
         ProblemFilters.exclude[IncompatibleSignatureProblem]("scala.xml.MetaData.get"),

shared/src/main/scala-2.13+/scala/xml/ScalaVersionSpecific.scala

@@ -48,6 +48,8 @@ private[xml] trait ScalaVersionSpecificNodeSeq
     fromSpecific(new View.Map(this, f))
   def flatMap(f: Node => IterableOnce[Node]): NodeSeq =
     fromSpecific(new View.FlatMap(this, f))
+
+  def theSeq: scala.collection.Seq[Node]
 }
 
 private[xml] trait ScalaVersionSpecificNodeBuffer { self: NodeBuffer =>

shared/src/main/scala/scala/xml/Document.scala

@@ -96,7 +96,7 @@ class Document extends NodeSeq with Serializable {
 
   // methods for NodeSeq
 
-  override def theSeq: Seq[Node] = this.docElem
+  override def theSeq: ScalaVersionSpecific.SeqOfNode = this.docElem
 
   override def canEqual(other: Any): Boolean = other match {
     case _: Document => true

shared/src/main/scala/scala/xml/Group.scala

@@ -22,7 +22,7 @@ import scala.collection.Seq
  */
 // Note: used by the Scala compiler.
 final case class Group(nodes: Seq[Node]) extends Node {
-  override def theSeq: Seq[Node] = nodes
+  override def theSeq: ScalaVersionSpecific.SeqOfNode = nodes.toSeq
 
   override def canEqual(other: Any): Boolean = other match {
     case _: Group => true

shared/src/main/scala/scala/xml/Node.scala

@@ -166,7 +166,7 @@ abstract class Node extends NodeSeq with ScalaVersionSpecificNode {
   /**
    *  returns a sequence consisting of only this node
    */
-  override def theSeq: Seq[Node] = this :: Nil
+  override def theSeq: ScalaVersionSpecific.SeqOfNode = this :: Nil
 
   /**
    * String representation of this node

shared/src/main/scala/scala/xml/NodeSeq.scala

@@ -26,7 +26,7 @@ import scala.collection.Seq
 object NodeSeq {
   final val Empty: NodeSeq = fromSeq(Nil)
   def fromSeq(s: Seq[Node]): NodeSeq = new NodeSeq {
-    override def theSeq: Seq[Node] = s
+    override def theSeq: ScalaVersionSpecific.SeqOfNode = s.toSeq
   }
 
   // ---
@@ -48,7 +48,7 @@ object NodeSeq {
  *  @author  Burak Emir
  */
 abstract class NodeSeq extends AbstractSeq[Node] with immutable.Seq[Node] with ScalaVersionSpecificNodeSeq with Equality with Serializable {
-  def theSeq: Seq[Node]
+  def theSeq: ScalaVersionSpecific.SeqOfNode
   override def length: Int = theSeq.length
   override def iterator: Iterator[Node] = theSeq.iterator