Text system misuses objc_{load,store}Weak in some cases
| Originator: | twiomood | ||
| Number: | rdar://30860017 | Date Originated: | 05-Mar-2017 04:57 PM |
| Status: | Open | Resolved: | |
| Product: | macOS | Product Version: | 10.12.3 |
| Classification: | Other Bug | Reproducible: | Always |
Area:
AppKit
Summary:
When setting up a text system manually in order to use custom subclasses, the text system provokes a warning about objc_{load,store}Weak being used incorrectly.
Steps to Reproduce:
- Open the attached sample
- Enable the "Malloc Scribble" diagnostic option (and possible Malloc History to track down the identities of the objects involved later)
- Set a symbolic breakpoint on "objc_weak_error"
- Run the app
- The load time code will build up a text system attached to a text storage
- Click the button, this will tear down the old text system and replace it with a new one (still attached to the same text storage)
Expected Results:
- No misuse of ObjC weak references.
Actual Results:
- Breakpoint is hit
Version:
macOS 10.12.3
Notes:
Poking around, it looks like maybe the storage that is being misused is the private _textView ivar in NSTextContainer. Perhaps the "default text system" code is OK, but the manual setup path is directly assigning to the ivar instead of doing objc_storeWeak to clear the _textView.
Configuration:
Xcode 8.2.1
Attachments:
'TextContainerWeakTextView.zip' was successfully uploaded.
Sample code at <https://www.dropbox.com/s/k9ef9400gqmlxmk/TextContainerWeakTextView.zip?dl=0>
Comments
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