It looks like piping to clang no longer works. [imac86:fariborz/radars/LLVM] fjahania% clang -rewrite-test undecl- objc-h.m > junk.c [imac86:fariborz/radars/LLVM] fjahania% clang junk.c [imac86:fariborz/radars/LLVM] fjahania% clang -rewrite-test undecl- objc-h.m | clang Segmentation fault - Fariborz