object TupledAmbiguity {
  trait Base
  
  trait FooOps extends {
    def foo[T](t : T) = t
  }
  
  trait BarOps extends {
    def foo(s : String, i : Int) = (s, i)
  }
  
  implicit def baseFoo(b : Base) = new FooOps {}
  implicit def baseBar(b : Base) = new BarOps {}
  
  val b = new Base {}
  
  val f1 = b.foo(23)          // OK
  val f2 = b.foo("foo", 23)   // Ambiguous implicits
  val f3 = b.foo(("foo", 23)) // OK, explicit tuple
  
  def foo[T](t : T) = t
  def foo(s : String, i : Int) = (s, i)
  
  val f4 = foo(23)            // OK
  val f5 = foo("foo", 23)     // OK
}

src/bugs/TupledAmbiguity.scala:20: error: type mismatch;
 found   : bugs.TupledAmbiguity.b.type (with underlying type Object with bugs.TupledAmbiguity.Base)
 required: ?{val foo(x$1: ?>: String("foo") <: Any,x$2: ?>: Int(23) <: Any): ?}
Note that implicit conversions are not applicable because they are ambiguous:
 both method baseBar in object TupledAmbiguity of type (b: bugs.TupledAmbiguity.Base)Object with bugs.TupledAmbiguity.BarOps
 and method baseFoo in object TupledAmbiguity of type (b: bugs.TupledAmbiguity.Base)Object with bugs.TupledAmbiguity.FooOps
 are possible conversion functions from bugs.TupledAmbiguity.b.type to ?{val foo(x$1: ?>: String("foo") <: Any,x$2: ?>: Int(23) <: Any): ?}
  val f2 = b.foo("foo", 23)   // Ambiguous implicits
           ^
one error found