diff --git a/scala2-library-cc/src/scala/collection/Factory.scala b/scala2-library-cc/src/scala/collection/Factory.scala
index 5392d7e2c642..99f584b972fc 100644
--- a/scala2-library-cc/src/scala/collection/Factory.scala
+++ b/scala2-library-cc/src/scala/collection/Factory.scala
@@ -296,15 +296,10 @@ object IterableFactory {
   }
 }
 
-// !!! Needed to add this separate trait
-trait FreeSeqFactory[+CC[A]] extends IterableFactory[CC]:
-  def from[A](source: IterableOnce[A]^): CC[A]
-  override def apply[A](elems: A*): CC[A] = from(elems)
-
 /**
   * @tparam CC Collection type constructor (e.g. `List`)
   */
-trait SeqFactory[+CC[A] <: SeqOps[A, Seq, Seq[A]]] extends FreeSeqFactory[CC] {
+trait SeqFactory[+CC[A] <: SeqOps[A, Seq, Seq[A]]] extends IterableFactory[CC] {
   import SeqFactory.UnapplySeqWrapper
   final def unapplySeq[A](x: CC[A] @uncheckedVariance): UnapplySeqWrapper[A] = new UnapplySeqWrapper(x) // TODO is uncheckedVariance sound here?
 }
diff --git a/scala2-library-cc/src/scala/collection/Seq.scala b/scala2-library-cc/src/scala/collection/Seq.scala
index 334546d67dad..65927154c4b6 100644
--- a/scala2-library-cc/src/scala/collection/Seq.scala
+++ b/scala2-library-cc/src/scala/collection/Seq.scala
@@ -81,8 +81,6 @@ trait SeqOps[+A, +CC[_], +C] extends Any with SeqViewOps[A, CC, C] { self =>
 
   override def view: SeqView[A] = new SeqView.Id[A](this)
 
-  def iterableFactory: FreeSeqFactory[CC]
-
   /** Get the element at the specified index. This operation is provided for convenience in `Seq`. It should
     * not be assumed to be efficient unless you have an `IndexedSeq`. */
   @throws[IndexOutOfBoundsException]
@@ -167,7 +165,7 @@ trait SeqOps[+A, +CC[_], +C] extends Any with SeqViewOps[A, CC, C] { self =>
   def prependedAll[B >: A](prefix: IterableOnce[B]^): CC[B] = iterableFactory.from(prefix match {
     case prefix: Iterable[B] => new View.Concat(prefix, this)
     case _ => prefix.iterator ++ iterator
-  })
+  }).unsafeAssumePure // assume pure OK since iterableFactory.from is eager for Seq
 
   /** Alias for `prependedAll` */
   @`inline` override final def ++: [B >: A](prefix: IterableOnce[B]^): CC[B] = prependedAll(prefix)
@@ -532,6 +530,7 @@ trait SeqOps[+A, +CC[_], +C] extends Any with SeqViewOps[A, CC, C] { self =>
 
   @deprecated("Use .reverseIterator.map(f).to(...) instead of .reverseMap(f)", "2.13.0")
   def reverseMap[B](f: A => B): CC[B] = iterableFactory.from(new View.Map(View.fromIteratorProvider(() => reverseIterator), f))
+    .unsafeAssumePure // assume pure OK since iterableFactory.from is eager for Seq
 
   /** Iterates over distinct permutations of elements.
    *
@@ -947,7 +946,8 @@ trait SeqOps[+A, +CC[_], +C] extends Any with SeqViewOps[A, CC, C] { self =>
     */
   def patch[B >: A](from: Int, other: IterableOnce[B]^, replaced: Int): CC[B] =
     iterableFactory.from(new View.Patched(this, from, other, replaced))
-
+      .unsafeAssumePure // assume pure OK since iterableFactory.from is eager for Seq
+      
   /** A copy of this $coll with one single replaced element.
     *  @param  index  the position of the replacement
     *  @param  elem   the replacing element
diff --git a/scala2-library-cc/src/scala/collection/generic/IsSeq.scala b/scala2-library-cc/src/scala/collection/generic/IsSeq.scala
index 041d74f84d9c..7b5e50499c0c 100644
--- a/scala2-library-cc/src/scala/collection/generic/IsSeq.scala
+++ b/scala2-library-cc/src/scala/collection/generic/IsSeq.scala
@@ -84,7 +84,7 @@ object IsSeq {
           def toIterable: Iterable[Char] = new immutable.WrappedString(s)
           protected[this] def coll: String = s
           protected[this] def fromSpecific(coll: IterableOnce[Char]^): String = coll.iterator.mkString
-          def iterableFactory: FreeSeqFactory[immutable.ArraySeq] = immutable.ArraySeq.untagged
+          def iterableFactory: IterableFactory[immutable.ArraySeq] = immutable.ArraySeq.untagged
           override def empty: String = ""
           protected[this] def newSpecificBuilder: mutable.Builder[Char, String] = new StringBuilder
           def iterator: Iterator[Char] = s.iterator
@@ -102,7 +102,7 @@ object IsSeq {
           def toIterable: Iterable[A] = mutable.ArraySeq.make[A](a)
           protected def coll: Array[A] = a
           protected def fromSpecific(coll: IterableOnce[A]^): Array[A] = Array.from(coll)
-          def iterableFactory: FreeSeqFactory[mutable.ArraySeq] = mutable.ArraySeq.untagged
+          def iterableFactory: IterableFactory[mutable.ArraySeq] = mutable.ArraySeq.untagged
           override def empty: Array[A] = Array.empty[A]
           protected def newSpecificBuilder: mutable.Builder[A, Array[A]] = Array.newBuilder
           def iterator: Iterator[A] = a.iterator