WIP better testcase

Author: Blaisorblade

tests/pos/i4884.scala

@@ -1,7 +1,14 @@
 object Test {
   trait A
   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
@@ -10,4 +17,25 @@ object Test {
   val v2: TestConstructor2[A] => Unit = { f =>
     type P[a <: A] = f.F[a] // Error! Type argument a does not conform to upper bound D
   }
+
+  def f2(f: TestConstructor2[A]): Unit = {
+    type P[a <: A] = f.F[a] // Error! Type argument a does not conform to upper bound D
+  }
+
+  // val v3: (f: TestConstructor2[A]) => (g: f.TestConstructor3[A]) => Unit = { f => g =>
+  //   type P[a <: A] = f.F[a] // Error! Type argument a does not conform to upper bound D
+  //   // type Q[a <: A] = g.G[a]
+  //   // type R[a <: A] = (f.F & g.G)[a]
+  //   // type R[a <: A] = ([X] => f.F[X] & g.G[X])[a]
+  // }
+  def f3(f: TestConstructor2[A], g: f.TestConstructor3[A]): Unit = {
+    type P[a <: A] = f.F[a] // Error! Type argument a does not conform to upper bound D
+    type Q[a <: A] = g.G[a]
+    // type R[a <: A] = (f.F & g.G)[a] // compiler error
+    type R[a <: A] = ([X <: A] => f.F[X] & g.G[X])[a]
+    type S[a <: A] = f.G[a] & g.H[a]
+  }
+  //val v4: (f: TestConstructor2[A]) => (g: f.TestConstructor3[A]) => Unit = {f => ???} // crash
+  //val v5: (f: TestConstructor2[A]) => (g: f.TestConstructor3[A]) => Unit = {(f: TestConstructor2[A]) => ???} // crash
+  //val v6: (f: TestConstructor2[A]) => (g: f.TestConstructor3[A]) => Unit = {(f: TestConstructor2[A]) => (g: f.TestConstructor3[A]) => ???} // crash
 }