Open Radar

 
Summary:
In Swift calling a method/property on __FUNCTION__ (e.g. lowercaseString) from inside an autorelease pool crashes when exiting the pool due to an over-release.

Steps to Reproduce:
Paste this code into main.swift for a new command line app and run it

import Foundation

func crashOnRelease() {
    println(__FUNCTION__.lowercaseString)
}

autoreleasepool {
    crashOnRelease()
}


Expected Results:
Generated executable prints "crashonrelease()" and exits cleanly

Actual Results:
Generated executable prints "crashonrelease()" but crashes when exiting the autoreleasepool with the following stack:

(lldb) bt
* thread #1: tid = 0x76fdb, 0x00007fff9683e44f libobjc.A.dylib`objc_release + 15, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x20)
    frame #0: 0x00007fff9683e44f libobjc.A.dylib`objc_release + 15
    frame #1: 0x00007fff9683ce8f libobjc.A.dylib`(anonymous namespace)::AutoreleasePoolPage::pop(void*) + 575
    frame #2: 0x000000010000685e modifyfunctionname`ObjectiveC.autoreleasepool (() -> ()) -> () + 46
  * frame #3: 0x00000001001bf477 modifyfunctionname`main + 119 at main.swift:17
    frame #4: 0x00007fff917a65c9 libdyld.dylib`start + 1


Version:
Xcode-Beta-6.3 (6D520o)

Notes:
Discovered when creating `XCTestCase`s that use __FUNCTION__ since those are executed inside an autorelease pool.

This doesn't crash in Xcode 6.1.1 (6A2008a)

Configuration:
Always on Xcode-Beta-6.3 on Yosemete

Alternative repro:
This problem isn't limited to the __FUNCTION__ string. I've found that reading the contents of a file into a string and then using `lowercaseString` inside an autorelease pool will similarly crash due to an over-release.

import Cocoa
@NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate {

    func applicationDidFinishLaunching(aNotification: NSNotification) {
        autoreleasepool {
            let bundle = NSBundle(forClass: self.dynamicType)
            if let path = bundle.pathForResource("Hello", ofType: "txt"),
                var text = String(contentsOfFile: path, encoding: NSUTF8StringEncoding, error: nil) {
                    text.lowercaseString
            }
        }
    }
}