P256K Int256 addingReportingOverflow(_:) Instance Method addingReportingOverflow(_:) iOS 18.0+ macCatalyst 18.0+ macOS 15.0+ tvOS 18.0+ visionOS 2.0+ watchOS 11.0+ func addingReportingOverflow(_ rhs: Int256) -> (partialValue: Int256, overflow: Bool)