Was there an issue if you used a wrapped clang and those patches or not? I'm really confused.
Even with GHC/clang-wrapper and alex/happy with Nick's patches, I cannot build GHC head. (I'm not using GCC 42 at all in this case.) AlexTemplate (pre-processed by clang) has linemarkers like this: ---- # 1 "<built-in>" ---- So, Lexer.hs generated from Lexer.x by alex also includes this one. Lexer.hs is CPP language extension. So, it is pre-processed again by clang. Since clang-wrapper specifies "-x assembler-with-cpp", generated Lexcer.hscpp contains: ---- # 1 "<built-in>" ---- GHC cannot handle this, so build fails. My hack lets alex and happy not to produce linemarkers at all. Is this explanation clear to you? P.S. If we modify clang-wrapper to not convert "-x c" to "-x assembler-with-cpp", some other files which contains " #-}" cannot be compiled. --Kazu