gistfile1.swift

// Bug demonstrating Release crash in swift code (XCode 6.2 / swift 1.1, Release builds only)

import UIKit
import XCTest

func dictSetValue(value: AnyObject, forKey key: String, inout #dictionary: [String : AnyObject]) {
  dictSetValue(value, forKeyPathComponents: key.componentsSeparatedByString("."), dictionary: &dictionary)
}

func dictSetValue(value: AnyObject, forKeyPathComponents components: [String], inout #dictionary: [String : AnyObject]) {
  if components.isEmpty {
    return
  }
  
  let head = components.first!
  
  if components.count == 1 {
    dictionary[head] = value
  } else {
    var child = (dictionary[head] as? [String : AnyObject]) ?? [:]
    
    let tail = Array(components[1..<components.count])
    dictSetValue(value, forKeyPathComponents: tail, dictionary: &child)
    
    return dictionary[head] = child // <- crash here
  }
}

class SwiftObjectMapperBugTests: XCTestCase {
  
  func testCrash() {
    var dict: [String: AnyObject] = [:]
    dictSetValue(1, forKey: "a.b", dictionary: &dict)
    dictSetValue(2, forKey: "a.c", dictionary: &dict) // <- crash

    XCTAssert(true, "crashes before here")
  }
  
}