Use isProvisional instead of has LazyRef

Author: dwijnand

compiler/src/dotty/tools/dotc/typer/Typer.scala

@@ -2376,8 +2376,8 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
     val bound2 = if tree.bound.isEmpty then
       val lub = cases1.foldLeft(defn.NothingType: Type): (acc, case1) =>
         if !acc.exists then NoType
-        else if case1.body.tpe.existsPart(_.isInstanceOf[LazyRef]) then NoType
-        else acc | TypeOps.avoid(case1.body.tpe, patVars(case1))
+        else if case1.body.tpe.isProvisional then NoType
+        else acc | case1.body.tpe
       if lub.exists then TypeTree(lub, inferred = true)
       else bound1
     else bound1

tests/pos/Tuple.Drop.scala

@@ -0,0 +1,7 @@
+import compiletime.ops.int.*
+
+type Drop[T <: Tuple, N <: Int] <: Tuple = N match
+  case 0 => T
+  case S[n1] => T match
+    case EmptyTuple => EmptyTuple
+    case x *: xs => Drop[xs, n1]

tests/pos/Tuple.Elem.scala

@@ -0,0 +1,7 @@
+import compiletime.ops.int.*
+
+type Elem[T <: Tuple, I <: Int] = T match
+  case h *: tail =>
+    I match
+      case 0 => h
+      case S[j] => Elem[tail, j]