Add test

Author: odersky

tests/pos/i20184.scala

@@ -0,0 +1,12 @@
+object Outer:
+  def Test =
+    object Inner:
+      var x: Int = 2
+      class Rgb():
+        def f = x
+
+    type Id[X] = X
+    type TRgb = Id[Inner.Rgb]
+
+    val ok = new Inner.Rgb()
+    val crash = new Id[Inner.Rgb]