       memberAfterInsert: memberAfterInsert.base as! ConcreteElement)
   }
 
-  @inlinable // FIXME(sil-serialize-all)
+  @inlinable
   @discardableResult
   public mutating func update<ConcreteElement : Hashable>(
     with newMember: ConcreteElement

      .map { $0.base as! ConcreteElement }
  }

  @inlinable // FIXME(sil-serialize-all)
  @discardableResult
  public mutating func remove<ConcreteElement : Hashable>(
    _ member: ConcreteElement

//===----------------------------------------------------------------------===//

extension Set where Element == AnyHashable {
  @inlinable
  public mutating func insert<ConcreteElement : Hashable>(
    _ newMember: ConcreteElement
  ) -> (inserted: Bool, memberAfterInsert: ConcreteElement) {
