--- /dev/null
+# This file is part of NIT ( http://www.nitlanguage.org ).
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import core::kernel
+
+interface A
+ new do return new B(5)
+end
+
+class B
+ super A
+ var i: Int
+ redef fun output do
+ 'B'.output
+ i.output
+ end
+end
+
+interface G[E: Object]
+ new(a: E) do return new H[E](a)
+ fun dup:G[E] is abstract
+end
+
+class H[F: Object]
+ super G[F]
+ var o: F
+
+ redef fun output do
+ 'H'.output
+ o.output
+ end
+
+ redef fun dup do return new G[F](self.o)
+end
+
+var b = new B(1)
+b.output
+var a = new A
+a.output
+
+var ha = new H[A](a)
+ha.output
+var hb = new H[B](b)
+hb.output
+
+var ga = new G[A](a)
+ga.output
+var gb = new G[B](b)
+gb.output
+
+ga.dup.output
+gb.dup.output
+
+var gga = new G[G[A]](ga)
+gga.output
+var ggb = new G[G[B]](gb)
+ggb.output
+
+gga.dup.output
+ggb.dup.output