test: add in a regression test for #11255 (#17497)

[skip community_build]

closes #11255

Author: nicolasstucki

tests/pos/i11255.scala

@@ -0,0 +1,26 @@
+class A
+class B extends A
+
+object O:
+  opaque type Id[T] = T
+  extension [T](id: Id[T]) def get: T = id
+  def f[S <: A, T](ff: S => T): Id[S => T] = ???
+  def g[S <: A, T](ff: S => T): Option[S => T] = ???
+  def h[S, T](ff: S => T): Id[S => T] = ???
+
+object example:
+  import O._
+
+  val a = new A
+  val b = new B
+
+  val f1 = f((a: A) => 0)
+  f1.get.apply(a)
+  val f2 = f((b: B) => 0)
+  f2.get.apply(b)
+
+  val g1 = g((a: A) => 0)
+  g1.get.apply(a)
+
+  val h1 = h((a: A) => 0)
+  h1.get.apply(a)