Swift Demangle

SwiftDemangle.playground

typealias Swift_Demangle = @convention(c) (_ mangledName: UnsafePointer<UInt8>?,
                                           _ mangledNameLength: Int,
                                           _ outputBuffer: UnsafeMutablePointer<UInt8>?,
                                           _ outputBufferSize: UnsafeMutablePointer<Int>?,
                                           _ flags: UInt32) -> UnsafeMutablePointer<Int8>?

func swift_demangle(_ mangled: String) -> String? {
    let RTLD_DEFAULT = dlopen(nil, RTLD_NOW)
    if let sym = dlsym(RTLD_DEFAULT, "swift_demangle") {
        let f = unsafeBitCast(sym, to: Swift_Demangle.self)
        if let cString = f(mangled, mangled.count, nil, nil, 0) {
            defer { cString.deallocate() }
            return String(cString: cString)
        }
    }
    return nil
}

// How to use
if let s = swift_demangle("$s20MyPlayground_Sources4TestC4testSSyF") {
    print(s) // MyPlayground_Sources.Test.test() -> Swift.String
}