With GHC 6.4.x I was able to use a ghc driver to compile .cpp sources. Now, with GHC HEAD I cannot. GHC HEAD now ALWAYS enforces "treat as .c" option. Let's compare "DriverPipeline.hs". GHC 6.4.x: let langopt | hcc = [ SysTools.Option "-x", SysTools.Option "c"] | otherwise = [ ] SysTools.runCc dflags ( -- force the C compiler to interpret this file as C when -- compiling .hc files, by adding the -x c option. -- Also useful for plain .c files, just in case GHC saw a -- -x c option. langopt ++ ... GHC HEAD: SysTools.runCc dflags ( -- force the C compiler to interpret this file as C when -- compiling .hc files, by adding the -x c option. -- Also useful for plain .c files, just in case GHC saw a -- -x c option. [ SysTools.Option "-x", SysTools.Option "c"] ++ ... This completely breaks my build infrastructure. Could it be reversed? Cheers, Kyra