Drop restriction to 2nd order hk types

Allow hk type parameters to be higher kinded themselves.

4 files changed, 55 insertions, 6 deletions

diff --git a/tests/disabled/not-representable/pos/t2066.scala b/tests/disabled/not-representable/pos/t2066.scala
index 30cb99d45..d175769fa 100644
--- a/tests/disabled/not-representable/pos/t2066.scala
+++ b/tests/disabled/not-representable/pos/t2066.scala
@@ -3,7 +3,7 @@ trait A1 {
 }
 
 trait B1 extends A1 {
-  override def f[T[_]] = ()
+  override def f[T[+_]] = ()
 }
 
 
@@ -12,12 +12,12 @@ trait A2 {
 }
 
 trait B2 extends A2 {
-  override def f[T[_]] = ()
+  override def f[T[-_]] = ()
 }
 
 
 trait A3 {
-  def f[T[X[_]]] = ()
+  def f[T[X[+_]]] = ()
 }
 
 trait B3 extends A3 {
diff --git a/tests/neg/t2994.scala b/tests/neg/t2994.scala
index 23a3b6a8b..6964a080e 100644
--- a/tests/neg/t2994.scala
+++ b/tests/neg/t2994.scala
@@ -7,7 +7,7 @@ object Naturals {
     type a[s[_ <: NAT] <: NAT, z <: NAT] = z
   }
   final class SUCC[n <: NAT] extends NAT {
-    type a[s[_ <: NAT] <: NAT, z <: NAT] = s[n#a[s, z]] // old-error: not a legal path
+    type a[s[_ <: NAT] <: NAT, z <: NAT] = s[n#a[s, z]] // error: not a legal path
   }
   type _0 = ZERO
   type _1 = SUCC[_0]
@@ -20,8 +20,8 @@ object Naturals {
 
   // crashes scala-2.8.0 beta1
   trait MUL[n <: NAT, m <: NAT] extends NAT {
-    trait curry[n[_[_], _], s[_]] { type f[z <: NAT] = n[s, z] } // can't do double param lists: // error: `]' expected but `[` found. // error: wrong number of type arguments
-    type a[s[_ <: NAT] <: NAT, z <: NAT] = n#a[curry[m#a, s]#f, z] // old-error: not a legal path // old-error: not a legal path
+    trait curry[n[_[_], _], s[_]] { type f[z <: NAT] = n[s, z] }
+    type a[s[_ <: NAT] <: NAT, z <: NAT] = n#a[curry[m#a, s]#f, z] // error: not a legal path // error: not a legal path
   }
 
 }
diff --git a/tests/pos/t2066.scala b/tests/pos/t2066.scala
new file mode 100644
index 000000000..d175769fa
--- /dev/null
+++ b/tests/pos/t2066.scala
@@ -0,0 +1,25 @@
+trait A1 {
+  def f[T[+_]] = ()
+}
+
+trait B1 extends A1 {
+  override def f[T[+_]] = ()
+}
+
+
+trait A2 {
+  def f[T[-_]] = ()
+}
+
+trait B2 extends A2 {
+  override def f[T[-_]] = ()
+}
+
+
+trait A3 {
+  def f[T[X[+_]]] = ()
+}
+
+trait B3 extends A3 {
+  override def f[T[X[+_]]] = ()
+}
diff --git a/tests/pos/t2712-3.scala b/tests/pos/t2712-3.scala
new file mode 100644
index 000000000..dd599f40f
--- /dev/null
+++ b/tests/pos/t2712-3.scala
@@ -0,0 +1,24 @@
+package test
+
+object Test1 {
+  class Foo[T, F[_]]
+  def meh[M[_[_]], F[_]](x: M[F]): M[F] = x
+  meh(new Foo[Int, List]) // solves ?M = [X[_]]Foo[Int, X[_]] ?A = List ...
+}
+
+object Test2 {
+  trait TC[T]
+  class Foo[F[_], G[_]]
+  def meh[GG[_[_]]](g: GG[TC]) = ???
+  meh(new Foo[TC, TC]) // solves ?G = [X[_]]Foo[TC, X]
+}
+
+object Test3 {
+  trait TC[F[_]]
+  trait TC2[F[_]]
+  class Foo[F[_[_]], G[_[_]]]
+  new Foo[TC, TC2]
+
+  def meh[G[_[_[_]]]](g: G[TC2]) = ???
+  meh(new Foo[TC, TC2]) // solves ?G = [X[_[_]]]Foo[TC, X]
+}