Merge pull request #2607 from retronym/ticket/7517

SI-7517 Fix higher kinded type inference regression

1 files changed, 22 insertions, 0 deletions

diff --git a/test/files/pos/t7517.scala b/test/files/pos/t7517.scala
new file mode 100644
index 0000000000..7ce4c6b13e
--- /dev/null
+++ b/test/files/pos/t7517.scala
@@ -0,0 +1,22 @@
+trait Box[ K[A[x]] ]
+
+object Box {
+   // type constructor composition
+   sealed trait ∙[A[_], B[_]] { type l[T] = A[B[T]] }
+
+   // composes type constructors inside K
+   type SplitBox[K[A[x]], B[x]] = Box[ ({ type l[A[x]] = K[ (A ∙ B)#l] })#l ]
+
+   def split[ K[A[x]], B[x] ](base: Box[K]): SplitBox[K,B] = ???
+
+   class Composed[B[_], L[A[x]] ] {
+      val box: Box[L] = ???
+
+      type Split[ A[x] ] = L[ (A ∙ B)#l ]
+      val a: Box[Split] = Box.split(box)
+
+      //Either of these work:
+      val a1: Box[Split] = Box.split[L,B](box)
+      val a2: Box[ ({ type l[A[x]] = L[ (A ∙ B)#l ] })#l ] = Box.split(box)
+   }
+}
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