Open Radar

 
Summary:
Covariant array assignment doesn't work as expected in Swift – it should either be prevented at compile-time or work properly at runtime.

In Xcode6-Beta4, things like

    let array : [MyProtocol] = [MyClass()] as [MyClass] // MyClass conforms to MyProtocol

should work without any error, since MyClass is a subtype of MyProtocol.

Yet doing such operation ends up with a runtime EXC_BAD_ACCESS error.

Steps to Reproduce:
1. Install Xcode6-Beta4
2. Open the attached "covariant-array-assignment.playground" file
3. Execute the playground

Expected Results:
No runtime error, console displaying "1" (the array's count)

Actual Results:
Runtime EXC_BAD_ACCESS error, console displaying the backtrace (attached as "error-backtrace.log" for reference)

Version:
Xcode 6.0 Beta 4 (6A267n)
OS X 10.9.4 (13E28)
MacPro5,1

Notes:
Related Apple Developer Forums thread: https://devforums.apple.com/message/1015772

Configuration:
Issue is always reproducible, on any installation of Xcode6-Beta4 (6A267n)

Attachments:
'error-backtrace.log' and 'covariant-array-assignment.playground.zip' were successfully uploaded.

--- 28-Aug-2014 07:54 PM

I noticed that the uploaded playground file is damaged. Here is a link to the valid archive.

http://cl.ly/3j0a2b2t2D3K/download/rdar-17894354.zip

--- 22-Jan-2015 05:43 AM / ADR

Engineering has determined that your bug report is a duplicate of another issue and will be closed. 

18480439