Add regression test for 16463

Closes #16463

Author: mbovel

tests/neg/16463.check

@@ -0,0 +1,31 @@
+-- Error: tests/neg/16463.scala:42:33 ----------------------------------------------------------------------------------
+42 |  println(compiletime.constValue[TupleOps.BubbleSort[(1, 2)]]) // error: Recursion limit exceeded
+   |                                 ^
+   |                 Recursion limit exceeded.
+   |                 Maybe there is an illegal cyclic reference?
+   |                 If that's not the case, you could also try to increase the stacksize using the -Xss JVM option.
+   |                 For the unprocessed stack trace, compile with -Yno-decode-stacktraces.
+   |                 A recurring operation is (inner to outer):
+   |
+   |                   reduce type  EmptyTuple *: EmptyTuple match ...
+   |                   reduce type  EmptyTuple *: EmptyTuple match ...
+   |                   reduce type  EmptyTuple *: EmptyTuple match ...
+   |                   reduce type  EmptyTuple *: EmptyTuple match ...
+   |                   reduce type  EmptyTuple *: EmptyTuple match ...
+   |                   reduce type  EmptyTuple *: EmptyTuple match ...
+   |                   reduce type  EmptyTuple *: EmptyTuple match ...
+   |                   reduce type  EmptyTuple *: EmptyTuple match ...
+   |                   reduce type  EmptyTuple *: EmptyTuple match ...
+   |                   reduce type  EmptyTuple *: EmptyTuple match ...
+   |                   ...
+   |
+   |                   reduce type  EmptyTuple *: EmptyTuple match ...
+   |                   reduce type  EmptyTuple *: EmptyTuple match ...
+   |                   reduce type  EmptyTuple *: EmptyTuple match ...
+   |                   reduce type  EmptyTuple *: EmptyTuple match ...
+   |                   reduce type  EmptyTuple *: EmptyTuple match ...
+   |                   reduce type  EmptyTuple *: EmptyTuple match ...
+   |                   reduce type  EmptyTuple *: EmptyTuple match ...
+   |                   reduce type  EmptyTuple *: EmptyTuple match ...
+   |                   reduce type  ((1 : Int) *: EmptyTuple.type) *: EmptyTuple match ...
+   |                   reduce type  ((1 : Int), (2 : Int)) match ...

tests/neg/16463.scala

@@ -0,0 +1,43 @@
+//> using scala "3.2.1"
+
+import scala.compiletime.ops.int._
+
+object TupleOps {
+  import Tuple._
+
+  type Reduce[T <: NonEmptyTuple, F[_, _]] =
+    Fold[Tuple.Tail[T], Tuple.Head[T], F]
+
+  type Maximum[T <: NonEmptyTuple] = Reduce[
+    T,
+    [A, B] =>> (A, B) match {
+      case (Int, Int) => A `Max` B
+    }
+  ]
+
+  type IndexOfRec[T <: Tuple, Elem, I <: Int] = Tuple.Elem[T, I] match {
+    case Elem => I
+    case _    => IndexOfRec[T, Elem, I + 1]
+  }
+
+  type IndexOf[T <: Tuple, Elem] = IndexOfRec[T, Elem, 0]
+
+  type DropLargest[T <: NonEmptyTuple] =
+    T `IndexOf` Maximum[T] match {
+      case Int =>
+        (
+          (T `Take` (T `IndexOf` Maximum[T])) `Concat`
+          (T `Drop` ((T `IndexOf` Maximum[T]) + 1))
+        ) *: EmptyTuple
+    }
+
+  type BubbleSort[T <: Tuple] = T match {
+    case EmptyTuple => EmptyTuple
+    case NonEmptyTuple =>
+      BubbleSort[DropLargest[T]] `Concat` (Maximum[T] *: EmptyTuple)
+  }
+}
+
+object demo extends App {
+  println(compiletime.constValue[TupleOps.BubbleSort[(1, 2)]]) // error: Recursion limit exceeded
+}