Add SortedSet and BitSet to stdlib (capture checked)

Author: odersky

tests/pos-special/stdlib/collection/BitSet.scala

@@ -48,7 +48,7 @@ object BitSet extends SpecificIterableFactory[Int, BitSet] {
 
   def empty: BitSet = immutable.BitSet.empty
   def newBuilder: Builder[Int, BitSet] = immutable.BitSet.newBuilder
-  def fromSpecific(it: IterableOnce[Int]): BitSet = immutable.BitSet.fromSpecific(it)
+  def fromSpecific(it: IterableOnce[Int]^): BitSet = immutable.BitSet.fromSpecific(it)
 
   @SerialVersionUID(3L)
   private[collection] abstract class SerializationProxy(@transient protected val coll: BitSet) extends Serializable {

tests/pos-special/stdlib/collection/SortedSet.scala

@@ -14,6 +14,7 @@ package scala.collection
 
 import scala.annotation.{implicitNotFound, nowarn}
 import scala.annotation.unchecked.uncheckedVariance
+import language.experimental.captureChecking
 
 /** Base type of sorted sets */
 trait SortedSet[A] extends Set[A]
@@ -68,7 +69,7 @@ trait SortedSetOps[A, +CC[X] <: SortedSet[X], +C <: SortedSetOps[A, CC, C]]
     * @param start The lower-bound (inclusive) of the iterator
     */
   def iteratorFrom(start: A): Iterator[A]
-  
+
   @deprecated("Use `iteratorFrom` instead.", "2.13.0")
   @`inline` def keysIteratorFrom(start: A): Iterator[A] = iteratorFrom(start)
 
@@ -178,7 +179,7 @@ object SortedSetOps {
     def flatMap[B : Ordering](f: A => IterableOnce[B]): CC[B] =
       self.sortedIterableFactory.from(new View.FlatMap(filtered, f))
 
-    override def withFilter(q: A => Boolean): WithFilter[A, IterableCC, CC] =
+    override def withFilter(q: A => Boolean): WithFilter[A, IterableCC, CC]^{this, q} =
       new WithFilter[A, IterableCC, CC](self, (a: A) => p(a) && q(a))
   }
 

tests/pos-special/stdlib/collection/immutable/BitSet.scala

@@ -95,7 +95,7 @@ sealed abstract class BitSet
 @SerialVersionUID(3L)
 object BitSet extends SpecificIterableFactory[Int, BitSet] {
 
-  def fromSpecific(it: scala.collection.IterableOnce[Int]): BitSet =
+  def fromSpecific(it: scala.collection.IterableOnce[Int]^): BitSet =
     it match {
       case bs: BitSet => bs
       case _          => (newBuilder ++= it).result()

tests/pos-special/stdlib/collection/immutable/SortedSet.scala

@@ -13,6 +13,7 @@
 package scala
 package collection
 package immutable
+import language.experimental.captureChecking
 
 /** Base trait for sorted sets */
 trait SortedSet[A]
@@ -50,7 +51,7 @@ trait StrictOptimizedSortedSetOps[A, +CC[X] <: SortedSet[X], +C <: SortedSetOps[
   */
 @SerialVersionUID(3L)
 object SortedSet extends SortedIterableFactory.Delegate[SortedSet](TreeSet) {
-  override def from[E: Ordering](it: IterableOnce[E]): SortedSet[E] = it match {
+  override def from[E: Ordering](it: IterableOnce[E]^): SortedSet[E] = it match {
     case ss: SortedSet[E] if Ordering[E] == ss.ordering => ss
     case _ => super.from(it)
   }

tests/pos-special/stdlib/collection/mutable/BitSet.scala

@@ -361,7 +361,7 @@ class BitSet(protected[collection] final var elems: Array[Long])
 @SerialVersionUID(3L)
 object BitSet extends SpecificIterableFactory[Int, BitSet] {
 
-  def fromSpecific(it: scala.collection.IterableOnce[Int]): BitSet = Growable.from(empty, it)
+  def fromSpecific(it: scala.collection.IterableOnce[Int]^): BitSet = Growable.from(empty, it)
 
   def empty: BitSet = new BitSet()
 

tests/pos-special/stdlib/collection/mutable/SortedSet.scala

@@ -13,6 +13,7 @@
 package scala
 package collection
 package mutable
+import language.experimental.captureChecking
 
 /**
   * Base type for mutable sorted set collections