方法返回类型[U<:Record,T<:Table[U]]工作不正常

我有几个DAO(使用 Slick )像下面这样

abstract class SuperRecord

abstract class SubSuperRecord extends SuperRecord

class Record1 extends SuperRecord

class Record2 extends SubSuperRecord

abstract class SuperTable[T <: SuperRecord] extends slick.driver.MySQLDriver.simple.Table[T]

abstract class SubSuperTable[T <: SubSuperRecord] extends SuperTable[T]

object DAO1 extends SuperTable[Record1]

object DAO2 extends SubSuperTable[Record2]

我在下面的方法中返回这些-我不是声明返回类型,而是让类型推理引擎来处理它

def getTable(table: String) = {
  table match {
    case "DAO1" => DAO1
    case "DAO2" => DAO2
    case _ => throw new IllegalArgumentException("invalid table")
  }
}

我正在尝试重构该方法,以返回 Try 对象,但这似乎混淆了类型推理引擎

def getTable(table: String) = Try {
  table match {
    case "DAO1" => DAO1
    case "DAO2" => DAO2
    case _ => throw new IllegalArgumentException("invalid table")
  }
}

当我打开Success时,我得到了一个Serializable,所以我试图帮助类型推理引擎

def getTable[T <: SuperRecord, U <: SuperTable[T]](table: String): Try[U] = Try {
  table match {
    case "DAO1" => DAO1
    case "DAO2" => DAO2
    case _ => throw new IllegalArgumentException("invalid table")
  }
}

然而,编译器告诉我 DAO1 也没有 DAO2 匹配此类型。此方法的正确返回类型是什么?