EXC_BAD_INSTRUCTION in cancel disk retrieve task by using dispatch_block_cancel

Originator:onevcat
Number:rdar://22432170 Date Originated:26-Aug-2015
Status:Resolved Resolved:YES
Product:iOS SDK Product Version:iOS SDK 9
Classification: Reproducible:Always
 
Summary:
The lib dispatch crashes on from Xcode 7 beta 6 on canceling a block.

Steps to Reproduce:
1. Create a new iOS app in Swift project in Xcode 7 beta 6.
2. Copy & paste the code snippet below to the application:didFinishLaunchingWithOptions: method in AppDelegate:

        let block = dispatch_block_create(DISPATCH_BLOCK_INHERIT_QOS_CLASS) { () -> Void in
            print("Hello world")
        }
        
        dispatch_async(dispatch_get_main_queue(), block)
        dispatch_block_cancel(block)

3. Run.

Expected Results:
App can be launched correctly, and nothing will be printed out in the console since the block is cancelled.

Actual Results:
Crash with a EXC_BAD_INSTRUCTION on the line of "dispatch_block_cancel"

Version:
8.1, 8.4, 9.0

Notes:
The attached files show screenshots when the crash happens

Configuration:
iPhone 6 Plus, iPhone Simulator from 8.1 to 9.0

Comments

Fixed

It is fixed in Xcode 7.1 beta 2 (7B75)

By onevcat at Sept. 24, 2015, 2:22 a.m. (reply...)

Apple Developer Relations24-Sep-2015 06:42 AM

Engineering has provided the following feedback regarding this issue:

Please verify this issue with the latest Xcode 7.1 beta 2 and update your bug report with your results.

If you still have any issues, please provide any relevant logs or information that could help us further investigate.

Xcode 7.1 beta 2 - 7B75 https://developer.apple.com/xcode/downloads/

Please let us know whether the issue is resolved for you by updating your bug report.

By onevcat at Sept. 24, 2015, 2:21 a.m. (reply...)

Seeing same thing XCode 7.1 beta (7b60) iOS 9.1

By pvanas at Sept. 18, 2015, 10:17 p.m. (reply...)

This still happens in Xcode 7.

By onevcat at Sept. 17, 2015, 5:32 a.m. (reply...)

This still happens in Xcode 7 GM

By onevcat at Sept. 10, 2015, 12:39 p.m. (reply...)

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