This commit adds new warning to prevent user from creating 'circular containers'.
Mutable collections from NSFoundation allows user to add collection to itself, e.g.:
NSMutableArray *a = [NSMutableArray new];
[a addObject:a];
The code above leads to really weird behaviour (crashes, 'endless' recursion) and
retain cycles (collection retains itself) if ARC enabled.
Patch checks the following collections:
- NSMutableArray,
- NSMutableDictionary,
- NSMutableSet,
- NSMutableOrderedSet,
- NSCountedSet.
llvm-svn: 231265
Alex Denisov