     displayStyle: DisplayStyle? = nil,
     ancestorRepresentation: AncestorRepresentation = .generated
   ) {
-    // FIXME: Can't use Builtin.unreachable() due to https://github.com/apple/swift/issues/57622.
-    self.init(reflecting: subject)
+    Builtin.unreachable()
   }
   public let subjectType: Any.Type
   public let children: Children

    displayStyle: DisplayStyle? = nil,
    ancestorRepresentation: AncestorRepresentation = .generated
  ) {
    // FIXME: Can't use Builtin.unreachable() due to https://github.com/apple/swift/issues/57622.
    self.init(reflecting: subject)
  }
  public init<Subject>(
    _ subject: Subject,

    displayStyle: DisplayStyle? = nil,
    ancestorRepresentation: AncestorRepresentation = .generated
  ) where C.Element == Child {
    Builtin.unreachable()
  }
  public init<Subject, C: Collection>(
    _ subject: Subject,
