[SR-5625] Optional Enum (annotated with @objc) + Mutable Array Leak (Swift 3)

[swift-ci]

Previous ID	SR-5625
Radar	https://openradar.appspot.com/33683103
Original Reporter	cem (JIRA User)
Type	Bug
Status	Resolved
Resolution	Done

Additional Detail from JIRA

Votes	1
Component/s	Compiler
Labels	Bug
Assignee	@slavapestov
Priority	Medium

md5: 35cf4dfd70334327afe2879d0c779595

Issue Description:

Summary:
When a Swift class contains an optional Enum property that is marked with @objc, and this same class also contains a mutable (var) array holding at least one element, there is an unexpected memory leak.

Steps to Reproduce:
Steps:

1. Download the attachment project (EnumMemoryLeak.zip) OR clone if from: https://github.com/Giphy/ios-memory-leak-sample
2. Open the project in XCode
3. Command + I
4. Select Leaks Instrument
5. Record

You should now encounter leaks.

Expected Results:
No leaks.

Observed Results:
Memory leaking.

Version:
XCode:

• Version 9.0 beta 4 (9M189t)
  (Same issue on 8.3.3 as well)

Deployment Target:

• 8.0+

MacOS:

• Version 10.12.5 (16F73)

Notes:
Work around:

If we convert the optional enum class property to a non-optional, leak will disappear.

// Let's convert the optional property to a non-optional
var leakOptionalEnum: leakingObjCMarkedEnum = .memoryLeakCase

[slavapestov]

#11341

[swift-ci]

Comment by Jared Halpern (JIRA)

Thank you @slavapestov!

[swift-ci]

Comment by Cem Kozinoglu (JIRA)

that was fast, thanks @slavapestov