Getting MirroredElemLabels from Mirror

Scala 3's scala.deriving.Mirror has a type member MirroredElemLabels which is a tuple of string literals. What's the standard way to get that type as a value?

EDIT: here's the code that produces a compiler error from trying to use summonAll

case class Test(a: Int, b: String)
val mirror = implicitly[Mirror.ProductOf[Test]]
val labels = summonAll[mirror.MirroredElemLabels]

cannot reduce inline match with
 scrutinee:  compiletime.erasedValue[App.mirror.MirroredElemLabels] : App.mirror.MirroredElemLabels
 patterns :  case _:EmptyTuple
             case _:*:[t @ _, ts @ _]


  • Try to use scala.ValueOf

    case class A(i: Int, s: String)
    import scala.deriving.Mirror
    import scala.compiletime.summonAll
    val mirror = summon[Mirror.Of[A]]    
    type ValueOfs = Tuple.Map[mirror.MirroredElemLabels, ValueOf]
    val valueOfs = summonAll[ValueOfs]
    def values(t: Tuple): Tuple = t match
      case (h: ValueOf[_]) *: t1 => h.value *: values(t1)
      case EmptyTuple => EmptyTuple
    values(valueOfs) // (i,s)

    We can now use scala.compiletime.constValueTuple

    inline def constValueTuple[T <: Tuple]: T =
      (inline erasedValue[T] match
        case _: EmptyTuple => EmptyTuple
        case _: (t *: ts) => constValue[t] *: constValueTuple[ts]

    and the return type will be precise

    case class A(i: Int, s: String)
    val mirror = summon[Mirror.Of[A]]
    val res = constValueTuple[mirror.MirroredElemLabels] // (i,s)
    res: ("i", "s") // compiles

    Tested in 3.2.0