Improve the diagnostic given when referring to a tag type without a tag (in C)
or that's been hidden by a non-type (in C++).

The ideal C++ diagnostic here would note the hiding declaration, but this
is a good start.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@96141 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed