1 files changed, 33 insertions, 0 deletions
diff --git a/tests/pos/t1756.scala b/tests/pos/t1756.scala
new file mode 100644
index 000000000..767eb54a7
--- /dev/null
+++ b/tests/pos/t1756.scala
@@ -0,0 +1,33 @@
+trait Ring[T <: Ring[T]] {
+  def +(that: T): T
+  def *(that: T): T
+}
+
+class A extends Ring[A] {
+  def +(that: A) = new A
+  def *(that: A) = new A
+}
+
+class Poly[C <: Ring[C]](val c: C) extends Ring[Poly[C]] {
+  def +(that: Poly[C]) = new Poly(this.c + that.c)
+  def *(that: Poly[C]) = new Poly(this.c*that.c)
+}
+
+object Test extends App {
+
+  implicit def coef2poly[CI <: Ring[CI]](c: CI): Poly[CI] = new Poly(c)
+
+  val a = new A
+  val x = new Poly(new A)
+
+  println(x + a) // works
+  println(a + x) // works
+
+  val y = new Poly(new Poly(new A))
+
+  println(x + y*x) // works
+  println(x*y + x) // works
+  println(y*x + x) // works
+
+  println(x + x*y) // failed before, first with type error, after that was fixed with "orphan poly parameter CI".
+}