Tighten types a bit. No functionality change.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@171902 91177308-0d34-0410-b5e6-96231b3b80d8
Clear LV cache when dropping availability attributes.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@171906 91177308-0d34-0410-b5e6-96231b3b80d8
PR14855: don't silently swallow a nested-name-specifier after a type name.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@171908 91177308-0d34-0410-b5e6-96231b3b80d8