Update SeqView.updated

scala2-library-cc/src/scala/collection/Seq.scala

@@ -957,7 +957,7 @@ trait SeqOps[+A, +CC[_], +C] extends Any with SeqViewOps[A, CC, C] { self =>
     *                                    lazy collection this exception may be thrown at a later time or not at
     *                                    all (if the end of the collection is never evaluated).
     */
-  def updated[B >: A](index: Int, elem: B): CC[B] = {
+  override def updated[B >: A](index: Int, elem: B): CC[B] = {
     if(index < 0) throw new IndexOutOfBoundsException(index.toString)
     val k = knownSize
     if(k >= 0 && index >= k) throw new IndexOutOfBoundsException(index.toString)

scala2-library-cc/src/scala/collection/SeqView.scala

@@ -30,11 +30,17 @@ trait SeqViewOps[+A, +CC[_], +C] extends Any with IterableOps[A, CC, C] {
   def length: Int
   def apply(x: Int): A
   def appended[B >: A](elem: B): CC[B]^{this}
-  def updated[B >: A](index: Int, elem: B): CC[B]^{this}
   def prepended[B >: A](elem: B): CC[B]^{this}
   def reverse: C^{this}
   def sorted[B >: A](implicit ord: Ordering[B]): C^{this}
 
+  // Placeholder implementation for that method in SeqOps.
+  // This is needed due to the change in the class hierarchy in cc stdlib.
+  // See #19660 and #19819.
+  def updated[B >: A](index: Int, elem: B): CC[B]^{this} =
+    assert(false, "This is a placeholder implementation in the capture checked Scala 2 library.")
+    ???
+
   def reverseIterator: Iterator[A]^{this} = reversed.iterator
 }
 
@@ -46,15 +52,6 @@ trait SeqView[+A] extends SeqViewOps[A, View, View[A]] with View[A] {
   override def map[B](f: A => B): SeqView[B]^{this, f} = new SeqView.Map(this, f)
   override def appended[B >: A](elem: B): SeqView[B]^{this} = new SeqView.Appended(this, elem)
 
-  // Copied from SeqOps. This is needed due to the change of class hierarchy in stdlib.
-  // See #19660.
-  override def updated[B >: A](index: Int, elem: B): View[B]^{this} = {
-    if(index < 0) throw new IndexOutOfBoundsException(index.toString)
-    val k = knownSize
-    if(k >= 0 && index >= k) throw new IndexOutOfBoundsException(index.toString)
-    iterableFactory.from(new View.Updated(this, index, elem))
-  }
-
   override def prepended[B >: A](elem: B): SeqView[B]^{this} = new SeqView.Prepended(elem, this)
   override def reverse: SeqView[A]^{this} = new SeqView.Reverse(this)
   override def take(n: Int): SeqView[A]^{this} = new SeqView.Take(this, n)