This diagnostic could be improved by adding the name of the input file
containing the invalid data and/or some information about how to
identify the specific offending attribute/tag in the input. But that's
not an immediate priority as these corner cases of invalid input
shouldn't come up too often.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@269727 91177308-0d34-0410-b5e6-96231b3b80d8