Merge pull request #10962 from griggt/fix-#9355

Fix #9355: Add regression test

Author: odersky

tests/pos/i9355/MainTest_2.scala

@@ -0,0 +1,3 @@
+object MainTest extends App {
+  println(JSON.JArray(1))
+}

tests/pos/i9355/Main_1.scala

@@ -0,0 +1,9 @@
+object JSON {
+  sealed trait Json
+  final case class JArray(elems: JValue*) extends Json
+  type JValue = Number | JArray
+}
+
+object Main extends App {
+  println(JSON.JArray(1))
+}