test: add in a regression test for #14582 (#17511)

[skip community_build]

closes #14582

Author: nicolasstucki

tests/run/i14582.scala

@@ -0,0 +1,18 @@
+// https://github.com/lampepfl/dotty/issues/14582
+@main def Test() =
+  val map = Map(
+    "a" -> 1,
+    "b" -> 2
+  )
+
+  val mapView = map.view
+
+  val optionMapView = Some(mapView)
+
+  val listOfTuples: List[(String, String)] = List(("c", "d"), ("e", "f"))
+
+  val mapViewWithDefault = optionMapView.getOrElse(Map())
+
+  val result = mapViewWithDefault ++ listOfTuples
+
+  result.toSeq