1 files changed, 29 insertions, 0 deletions
diff --git a/test/files/pos/t8237.scala b/test/files/pos/t8237.scala
new file mode 100644
index 0000000000..005089079e
--- /dev/null
+++ b/test/files/pos/t8237.scala
@@ -0,0 +1,29 @@
+import scala.language.higherKinds
+
+object TestExplicit {
+  trait TC[A]
+  def fTt[A,E[X] <: List[X]](a: A)(implicit tt: TC[E[A]]) = a
+  implicit def tc[T]: TC[T] = ???
+
+  // Typechecking results in SOE in TypeVar.isGround
+  fTt(1)(tc)
+  // fun = TestExplicit.this.fTt[Int, E](1)
+  // args = TestExplicit.this.tc[E[Int]]
+  // argTpes.head.instantiateTypeParams = TC[?E#1[Int]]
+  // formals.head.instantiateTypeParams = TC[?E#2[Int]]
+  //   (where ?E#1 and ?E#2 as distinct AppliedTypeVars that resulted
+  //    from separate applications of type args to the same HKTypeVar, ?E)
+  //
+  // As we check if the argument conforms to the formal, we would have
+  // AppliedTypeVars sharing the same TypeConstraints on the LHS and RHS,
+  // which leads to a cyclic constraint.
+}
+
+object TestImplicit    {
+  trait TC[A]
+  def fTt[A,E[X] <: List[X]](a: A)(implicit tt: TC[E[A]]) = a
+  implicit def tc[T]: TC[T] = ???
+
+  // Oddly enough, this one works.
+  fTt(1)
+}