Regression test

This now works with level checking on instantiation

Fixes #15154

Author: odersky

tests/new/test.scala

@@ -0,0 +1,24 @@
+trait RType
+trait TypeEntry{
+  def typeAdapter: TypeAdapter[_] = ???
+}
+
+trait TypeAdapter[E]
+case class OptionTypeAdapter[E](nullIsNone: Boolean, valueTypeAdapter: TypeAdapter[E]) extends TypeAdapter[E]
+case class JavaOptionalTypeAdapter[E](nullIsNone: Boolean, valueTypeAdapter: TypeAdapter[E]) extends TypeAdapter[E]
+
+def typeAdapterOf(concreteType: RType): TypeAdapter[_] = ???
+
+@main def test() = {
+  // https://github.com/gzoller/scalajack/blob/4a29366e28fbd594d7c21b4eb969ca14626ac0d1/core/src/main/scala/co.blocke.scalajack/typeadapter/TupleTypeAdapter.scala#L21-L30
+  val seq = List.empty[RType]
+  seq map { f =>
+    typeAdapterOf(f) match {
+      case ota: OptionTypeAdapter[_] => ota.copy(nullIsNone = true)
+      case jota: JavaOptionalTypeAdapter[_] => jota.copy(nullIsNone = true)
+      case other => other
+    }
+  }
+}
+
+// 15154