Allow definition of new types in refinements

Allow definition of types in refinements that do not appear
in parent type.

2 files changed, 54 insertions, 0 deletions

diff --git a/tests/pos/t2712-2.scala b/tests/pos/t2712-2.scala
new file mode 100644
index 000000000..95172545d
--- /dev/null
+++ b/tests/pos/t2712-2.scala
@@ -0,0 +1,25 @@
+package test
+
+// See: https://github.com/milessabin/si2712fix-demo/issues/3
+object Test {
+  trait A[T1, T2] { }
+  trait B[T1, T2] { }
+  class C[T] extends A[T, Long] with B[T, Double]
+  class CB extends A[Boolean, Long] with B[Boolean, Double]
+
+  trait A2[T]
+  trait B2[T]
+  class C2[T] extends A2[T] with B2[T]
+  class CB2 extends A2[Boolean] with B2[Boolean]
+
+  def meh[M[_], A](x: M[A]): M[A] = x
+
+  val m0 = meh(new C[Boolean])
+  m0: C[Boolean]
+  val m1 = meh(new CB)
+  m1: B[Boolean, Double] // note: different order in which parents are visited for hk type inference. Dotty picks libearization order.
+  val m2 = meh(new C2[Boolean])
+  m2: C2[Boolean]
+  val m3 = meh(new CB2)
+  m3: B2[Boolean] // note: different order in which parents are visited for hk type inference. Dotty picks libearization order.
+}
diff --git a/tests/pos/t2712-5.scala b/tests/pos/t2712-5.scala
new file mode 100644
index 000000000..ed96d4c06
--- /dev/null
+++ b/tests/pos/t2712-5.scala
@@ -0,0 +1,29 @@
+package test
+
+import scala.language.higherKinds
+
+trait Functor[F[_]] {
+  def map[A, B](f: A => B, fa: F[A]): F[B]
+}
+
+object Functor {
+  implicit def function[A]: Functor[({ type l[B] = A => B })#l] =
+    new Functor[({ type l[B] = A => B })#l] {
+      def map[C, B](cb: C => B, ac: A => C): A => B = cb compose ac
+    }
+}
+
+object FunctorSyntax {
+  implicit class FunctorOps[F[_], A](fa: F[A])(implicit F: Functor[F]) {
+    def map[B](f: A => B): F[B] = F.map(f, fa)
+  }
+}
+
+object Test {
+
+  val f: Int => String = _.toString
+
+  import FunctorSyntax._
+
+  f.map((s: String) => s.reverse)
+}