Issue with Swift and C++ Interoperability: Passing void pointer between Swift and C++

Hello everyone,

I'm encountering an issue with Swift and C++ interoperability when passing a void pointer between Swift and C++ functions. When I pass pMessageBuffer (an UnsafeMutableRawPointer) from Swift to MyCppClass.NFCompletion (a static c++ function), which expects a reference to void pointer, Swift throws an error "Cannot convert value of type 'UnsafeMutableRawPointer' to expected argument type 'Optional<UnsafeMutableRawPointer>' ".

Here is a sample code to help in better visualization of the usecase.

Cpp Code

class MyCppClass {
public:
    static void SendData(void *pMessage, TUInt16 pMessageLength) {
        // Assume vSocket is my Swift object held in C++.
        vSocket.Send(pMessage, pMessageLength);
    }

    static void NFCompletion(void * & pBuffer, TInt64 pErrorCode, VPtr pCompletionFunction) {
        // Process the buffer.
    }
};

Swift Code:

public class MySwiftClass {
    var vConnection: NWConnection?
    
    public init() {}
    
    public func Send(_ pMessageBuffer: UnsafeMutableRawPointer, _ pMessageLength: TSUInt16) {
        let messageData = Data(bytesNoCopy: pMessageBuffer, count: Int(pMessageLength), deallocator: .none)
        
        self.vConnection?.send(content: messageData, completion: .contentProcessed { nw_error in
            var error_code: TSInt64 = 0
            
            if let nw_error = nw_error {
                error_code = self.InternalGetNetworkErrorCode(nw_error)
            }
            
            // Here's where the issue arises:
            MyCppClass.NFCompletion(pMessageBuffer, TInt64(error_code), self.uCompletionHandler)
        })
    }
    
    // Example function to handle network errors
    private func InternalGetNetworkErrorCode(_ error: Error) -> TSInt64 {
        // Implementation to convert nw_error to TSInt64 error code
        return 0 // Placeholder return value
    }
}

Could someone please help me understand why this conversion error occurs? How should I correctly handle passing a void pointer between Swift and C++ functions, ensuring compatibility and proper memory management?

Note: TSInt64 is typealias for swift Int and TInt64 is alias of c++ int_64t.

Thank you in advance for your assistance!

Regards,

Harshal