Objective-C: Issue more precise warning when user
is accessing 'isa' as an object pointer.
// rdar://13503456. FixIt to follow in another patch.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@178179 91177308-0d34-0410-b5e6-96231b3b80d8
Revert "[lib/Headers] Define NULL as __DARWIN_NULL when on __APPLE__."

Per feedback by Doug, we should avoid platform-specific implementations
in lib/Headers as much as possible.

This reverts commit r178110.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@178181 91177308-0d34-0410-b5e6-96231b3b80d8
Fixes a typo in my last patch.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@178184 91177308-0d34-0410-b5e6-96231b3b80d8
Add a front-end test case for r178186.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@178187 91177308-0d34-0410-b5e6-96231b3b80d8
Remove unnecessary attributes from test case.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@178188 91177308-0d34-0410-b5e6-96231b3b80d8