Test case #4906

Author: odersky

tests/pos/i4906.scala

@@ -0,0 +1,36 @@
+object Test {
+  trait A
+  trait TestConstructor1 { type F[_ <: A] }
+  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
+  }
+
+  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 = ??? // ok
+  val v4: (f: TestConstructor2[A]) => (g: f.TestConstructor3[A]) => Unit = {f => ???}
+  val v5: (f: TestConstructor2[A]) => (g: f.TestConstructor3[A]) => Unit = {(f: TestConstructor2[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]
+  }
+}