Tweak warning text for nil value in ObjC container warning.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@179034 91177308-0d34-0410-b5e6-96231b3b80d8
<rdar://problem/13540921> Cope with deduced 'auto' in a C++11 for-range loop that is actually an Objective-C fast enumeration loop.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@179035 91177308-0d34-0410-b5e6-96231b3b80d8
<rdar://problem/13540921> Cope with instantiations of the C++11 range-based for loop that end up being Objective-C fast enumeration loops.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@179037 91177308-0d34-0410-b5e6-96231b3b80d8
doce parsing: adding few more headerdoc tags.
// rdar://12379114


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@179039 91177308-0d34-0410-b5e6-96231b3b80d8
In the comparison, both clang and GCC are popular and widely adopted.  This is no longer a win of GCC.

This whole doc should really be looked at.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@179040 91177308-0d34-0410-b5e6-96231b3b80d8