I think this is causing: /home/espindola/llvm/llvm/utils/TableGen/SetTheory.h:58:1: warning: struct 'Init' was previously declared as a class [-Wmismatched-tags] struct Init; ^ /home/espindola/llvm/llvm/utils/TableGen/Record.h:556:7: note: previous use is here class Init : public FastFoldingSetNode {