ruiu added a comment. The vector for empty.pdb is [0, 0x34, 0, 0, 0x1, 0x35, 0x46]. Previously name_ids returned [0x34, 0, 0, 0x1] which is the two strings. 0x35 is the empty string, and 0x46 is the missing string. http://reviews.llvm.org/D20611