[SR-5548] Crash due to invalid casting in URLSession

[pushkarnk]

Previous ID	SR-5548
Radar	None
Original Reporter	@pushkarnk
Type	Bug
Status	Closed
Resolution	Done

Environment

Linux

Additional Detail from JIRA

Votes	0
Component/s	Foundation
Labels	Bug
Assignee	@pushkarnk
Priority	Medium

md5: bb295e9a2444101a117aa7e3c0ec7c0d

Issue Description:

This happens with a delegate class that implements URLSessionDownloadDelegate is used with a DataTask.

import Foundation
import Dispatch

class SharedDelegate: NSObject {
}

extension SharedDelegate: URLSessionDataDelegate {
    func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, didReceive data: Data) {
        print("Data task completed")
    }
}

extension SharedDelegate: URLSessionDownloadDelegate {
    func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL) {
    }
}

let sharedDelegate = SharedDelegate()
let session = URLSession(configuration: .default, delegate: sharedDelegate, delegateQueue: nil)
let dataRequest = URLRequest(url: URL(string: "http://httpbin.org/get")!)
let dataTask = session.dataTask(with: dataRequest)

dataTask.resume()

dispatchMain()

Expected output:
Data task completed

Actual output:
Could not cast value of type 'Foundation.URLSessionDataTask' (0x7f1d8e643c18) to 'Foundation.URLSessionDownloadTask' (0x7f1d8e6442f8)

[pushkarnk]

#1132