Merge pull request #3400 from retronym/ticket/8170

SI-8170 Fix regression in TypeRef#transform w. PolyTypes

2 files changed, 52 insertions, 0 deletions

diff --git a/test/files/pos/t8170.scala b/test/files/pos/t8170.scala
new file mode 100644
index 0000000000..b65f4b8572
--- /dev/null
+++ b/test/files/pos/t8170.scala
@@ -0,0 +1,27 @@
+object O {
+  trait X
+  trait B extends A {
+    override type T[F1 <: X] = F1
+  }
+  trait A {
+    type T[F <: X]
+  }
+}
+
+object Test {
+  import O._
+  val a: B = ???
+  val b: a.T[X] = ???
+  b.ensuring(x => true) // trigger an implicit search
+}
+
+
+/*
+this = {AliasArgsTypeRef@3004}"Test#7680.a#14899.T#14823[O#7702.X#7793]"
+  sym = type T#14823
+    info = namer: [F#14824 <: O#7703.X#7793]F#14824
+result = {AbstractNoArgsTypeRef@3237}"F#24451"
+tp = {PolyType@3235}"[F#14824 <: O#7703.X#7793]F#14824"
+tparams = 
+  (0)  = {AbstractTypeSymbol@3247}"type F#24451"
+*/
\ No newline at end of file
diff --git a/test/files/pos/t8170b.scala b/test/files/pos/t8170b.scala
new file mode 100644
index 0000000000..53036f6c8a
--- /dev/null
+++ b/test/files/pos/t8170b.scala
@@ -0,0 +1,25 @@
+import language._
+
+object ScalaZeee {
+  trait HFold[M[_], U] {
+    type Apply[E, A <: U] <: U
+  }
+  trait GenericCons[M[_], H, +T <: GenericList[M]] extends GenericList[M] {
+    val tail: T
+    override type Folded[N[X] >: M[X], U, F <: HFold[N, U]] = F#Apply[H, tail.Folded[N, U, F]]
+  }
+  val KNil: GenericList[Nothing] = ???
+  sealed trait GenericList[+M[_]] {
+     type Folded[N[X] >: M[X], U, F <: HFold[N, U]] <: U
+  }
+}
+ 
+object TypelevelUsage {
+  import ScalaZeee._
+  type T = GenericCons[Some, String, KNil.type]
+  val klist1: T = ???
+  type T2 = klist1.Folded[Option, Int, HFold[Option, Int]]
+  val count2: T2 = ???
+   
+  count2.ensuring(x => true).toChar // trigger an implicit search
+}