bug3774.scala:2: error: overloaded method value ++ with alternatives:
  [B1 >: List[Int]](xs: scala.collection.TraversableOnce[((Int, Int), B1)])scala.collection.immutable.Map[(Int, Int),B1] <and>
  [B >: ((Int, Int), List[Int]),That](that: scala.collection.TraversableOnce[B])(implicit bf: scala.collection.generic.CanBuildFrom[scala.collection.immutable.Map[(Int, Int),List[Int]],B,That])That
 cannot be applied to (scala.collection.immutable.IndexedSeq[((Int, Int), scala.collection.immutable.Range.Inclusive)])
  Map[(Int,Int),List[Int]]() ++ (for(x <- 0 to 1 ; y <- 0 to 1) yield {(x,y)-> (0 to 1)})
                             ^
one error found