Here's from a framework we are using. It barfs at the @available on the enum. @available(macOS 11.0, iOS 14.0, tvOS 14.0, watchOS 7.0, *) extension BNNS {   public enum ActivationFunction {     case identity     case rectifiedLinear     case leakyRectifiedLinear(alpha: Swift.Float)     case sigmoid     case logSigmoid     case tanh     case scaledTanh(alpha: Swift.Float, beta: Swift.Float)     case abs     case linear(alpha: Swift.Float)     case clamp(bounds: Swift.ClosedRange<Swift.Float>)     case softmax     case geluApproximation(alpha: Swift.Float, beta: Swift.Float)     case geluApproximation2(alpha: Swift.Float, beta: Swift.Float)     case gumbel(alpha: Swift.Float, beta: Swift.Float)     case gumbelMax(alpha: Swift.Float, beta: Swift.Float)     case hardSigmoid(alpha: Swift.Float, beta: Swift.Float)     case softplus(alpha: Swift.Float, beta: Swift.Float)     case softsign     case elu(alpha: Swift.Float)     case selu     case celu(alpha: Swift.Float)     case clampedLeakyRectifiedLinear(alpha: Swift.Float, beta: Swift.Float)     case linearWithBias(alpha: Swift.Float, beta: Swift.Float)     case logSoftmax     case hardShrink(alpha: Swift.Float)     case softShrink(alpha: Swift.Float)     case tanhShrink     case threshold(alpha: Swift.Float, beta: Swift.Float)     @available(macOS 12.0, iOS 15.0, tvOS 15.0, watchOS 8.0, *)     case hardSwish(alpha: Swift.Float, beta: Swift.Float)     @available(macOS 12.0, iOS 15.0, tvOS 15.0, watchOS 8.0, *)     case silu     public var bnnsActivation: Accelerate.BNNSActivation {       get     }   }