[SR-11606] XMLElement.attribute(forName:) broken on Linux

[florianreinhart]

Previous ID	SR-11606
Radar	None
Original Reporter	@florianreinhart
Type	Bug

Environment

Swift version 5.1.1 (swift-5.1.1-RELEASE)

Additional Detail from JIRA

Votes	0
Component/s	Foundation
Labels	Bug, Linux
Assignee	None
Priority	Medium

md5: 454e540889fcb0bbebb5cd7f49ac3454

relates to:

• SR-10424 Parity: XMLElement: XML Namespaces

Issue Description:

I ran into a regression probably introduced in FoundationXML bundled with Swift 5.1 by PR2313.

XMLElement.attribute(forName:) does not return an attribute if xmlns is set to an empty string in the element.

The following program demonstrates the issue:

import Foundation
#if canImport(FoundationXML)
import FoundationXML
#endif


func parseXML(_ xmlData: Data) {

    let xmlDocument = try! XMLDocument(data: xmlData)

    let rootElement = xmlDocument.rootElement()!

    let child = rootElement.children?.first(where: { $0.localName == "child" }) as! XMLElement
    print("child attributes: \(child.attributes?.description ?? "nil")")
    print("child attribute1: \(child.attribute(forName: "attribute1")?.description ?? "nil")")
}


// XML without xmlns
let xmlData1 = Data("""
<rootElement>
    <child attribute1="value1">Child Content</child>
</rootElement>
""".utf8)

parseXML(xmlData1)


// XML with xmlns set to empty string
let xmlData2 = Data("""
<rootElement>
    <child xmlns="" attribute1="value1">Child Content</child>
</rootElement>
""".utf8)

parseXML(xmlData2)

On macOS the output is:

child attributes: [attribute1="value1"]
child attribute1: attribute1="value1"
child attributes: [attribute1="value1"]
child attribute1: attribute1="value1"

And on Linux:

child attributes: [ attribute1="value1"]
child attribute1:  attribute1="value1"
child attributes: [ attribute1="value1"]
child attribute1: nil

Also notice the additional space in front of the attribute name on Linux.

[florianreinhart]

CC @millenomi

[weissi]

Still not fixed in current main

root@0ae6b2f0fd1a:/Users/johannes/devel/swift-corelibs-foundation# swift
Welcome to Swift version 5.5-dev (LLVM fb5a91b4e892ed9, Swift f17142883421ec0).
Type :help for assistance.
  1> import Foundation 
  2. #if canImport(FoundationXML) 
  3. import FoundationXML 
  4. #endif 
  5.  
  6.  
  7. func parseXML(_ xmlData: Data) { 
  8.  
  9.     let xmlDocument = try! XMLDocument(data: xmlData) 
 10.  
 11.     let rootElement = xmlDocument.rootElement()! 
 12.  
 13.     let child = rootElement.children?.first(where: { $0.localName == "child" }) as! XMLElement 
 14.     print("child attributes: \(child.attributes?.description ?? "nil")") 
 15.     print("child attribute1: \(child.attribute(forName: "attribute1")?.description ?? "nil")") 
 16. } 
 17.  
 18.  
 19. // XML without xmlns 
 20. let xmlData1 = Data(""" 
 21. <rootElement> 
 22.     <child attribute1="value1">Child Content</child> 
 23. </rootElement> 
 24. """.utf8) 
 25.  
 26. parseXML(xmlData1) 
 27.  
 28.  
 29. // XML with xmlns set to empty string 
 30. let xmlData2 = Data(""" 
 31. <rootElement> 
 32.     <child xmlns="" attribute1="value1">Child Content</child> 
 33. </rootElement> 
 34. """.utf8) 
 35.  
 36. parseXML(xmlData2)
child attributes: [ attribute1="value1"]
child attribute1:  attribute1="value1"
child attributes: [ attribute1="value1"]
child attribute1: nil
xmlData1: Data = 81 bytes
xmlData2: Data = 90 bytes

[florianreinhart]

I just tested this with the current Swift Docker image (Swift version 6.0.3 (swift-6.0.3-RELEASE)) and it is not fixed.