Workaround scala#11247

Author: nicolasstucki

bench-run/src/main/scala/dotty/tools/benchmarks/tuples/TupleOps.scala

@@ -50,7 +50,7 @@ class TupleOps {
   def tupleMergeSort(tuple: Tuple): Tuple =
     if (tuple.size <= 1) tuple
     else {
-      val (tuple1, tuple2) = tuple.splitAt(tuple.size / 2)
+      val (tuple1: Tuple, tuple2: Tuple) = tuple.splitAt(tuple.size / 2) // TODO remove ascriptions when #11247 is fixed
       val (sorted1, sorted2) = (tupleMergeSort(tuple1), tupleMergeSort(tuple2))
       tupleMerge(sorted1, sorted2)
     }

library/src/scala/Tuple.scala

@@ -70,9 +70,7 @@ sealed trait Tuple extends Product {
    *  consisting of the first n elements, and the tuple `(an+1, ..., am)` consisting
    *  of the remaining elements.
    */
-  // FIXME remove transparent
-  //       failure in bench-run/src/main/scala/dotty/tools/benchmarks/tuples/TupleOps.scala
-  transparent inline def splitAt[This >: this.type <: Tuple](n: Int): Split[This, n.type] =
+  inline def splitAt[This >: this.type <: Tuple](n: Int): Split[This, n.type] =
     runtime.Tuples.splitAt(this, n).asInstanceOf[Split[This, n.type]]
 }