Crash in String+UTF16.swift - unescapeUTF16()

[Frederiks96]

I have experienced a crash in the unescapeUTF16 method in String+UTF16.swift. The markdown that led to the crash can be found here: https://github.com/apple/swift-evolution/blob/master/proposals/0240-ordered-collection-diffing.md

The crash was found on the line let endIndex = index(self.startIndex, offsetBy: $0 + 4) in the following code snippet:

stride(from: 0, to: count, by: 4).forEach {
    let startIndex = index(self.startIndex, offsetBy: $0)
    let endIndex = index(self.startIndex, offsetBy: $0 + 4)
    let hex4 = String(self[startIndex..<endIndex])
    if let utf16 = UInt16(hex4, radix: 16) {
        utf16Array.append(utf16)
    }
}

[DavidLari]

On a fork of this project called Haring, we fixed this issue by adding the following line to the beginning of the function. It stops the crash, but perhaps there's a better fix.

guard count >= 4 else { return nil }

[bmoliveira]

This crash should not be happening anymore.

But the code Element parser is not working 100% according to the Github parser if the language is specified it will appear on the final view and it shouldn't.

Check out #37 for more information.