class Foo(xs: List[_])
object Foo {
  def make(xs: List[_]): Foo = new Foo(xs)
  implicit def make[A](xs: List[A])(implicit X: DummyImplicit): Foo = new Foo(xs)
}

List(""): Foo

scala> List(""): Foo
           ^
       error: ambiguous reference to overloaded definition,
       both method make in object Foo of type [A](xs: List[A])(implicit X: DummyImplicit)Foo
       and  method make in object Foo of type (xs: List[_])Foo
       match argument types (List[String]) and expected result type Foo