Implement type checking of Objective-C property attributes.
 - readonly and readwrite are mutually exclusive.
 - assign, copy, and retain are mutually exclusive.
 - copy and retain are invalid on non-object types.
 - Warn about using default 'assign' property on object types
   (attempting to follow gcc behavior).


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@56507 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed