Improve testcase

Author: Blaisorblade

tests/pos/i4884.scala

@@ -1,13 +1,37 @@
 object Test {
   trait A
+  trait B
   trait TestConstructor1 { type F[_ <: A] }
-  trait TestConstructor2[D] { type F[_ <: D] }
+  trait TestConstructor2[D] {
+    type F[_ <: D]
+    class G[X <: D]
+    trait TestConstructor3[E] {
+      type G[_ <: D & E]
+      class H[X <: D & E]
+    }
+  }
 
   val v1: TestConstructor1 => Unit = { f =>
-    type P[a <: A] = f.F[a] // OK
+    type P[a <: A] = f.F[a]
   }
 
   val v2: TestConstructor2[A] => Unit = { f =>
-    type P[a <: A] = f.F[a] // Error! Type argument a does not conform to upper bound D
+    type P[a <: A] = f.F[a]
+  }
+
+  def f2(f: TestConstructor2[A]): Unit = {
+    type P[a <: A] = f.F[a]
+  }
+
+  type C = A & B
+  def f3(f: TestConstructor2[A], g: f.TestConstructor3[B]): Unit = {
+    type P1[a <: A] = f.F[a]
+    type P2[a <: A] = f.G[a]
+    type Q1[c <: C] = g.G[c]
+    type Q2[c <: C] = g.H[c]
+    type R1[c <: C] = f.G[c] & g.H[c]
+    type R2[c <: C] = f.G[c] | g.H[c]
+    type S1[c <: C] = ([X <: C] => f.F[X] & g.G[X])[c]
+    type S2[c <: C] = ([X <: C] => f.F[X] | g.G[X])[c]
   }
-}
+}