Dear GHC team, I needed to look into the C code made by ghc-7.4.1 (made from source by 7.0.1 on Debian Linux) for module TT (dropCWhile) where dropCWhile :: (Char -> Bool) -> [Char] -> [Char] dropCWhile p xs = case xs of [] -> [] x: ys -> if p x then dropCWhile p ys else xs And applied ghc -C -O TT.hs It reports ------------------------------------------- addFlag by -C on the commandline: Warning: The -fvia-C flag does nothing; it will be removed in a future GHC release ghc: panic! (the 'impossible' happened) (GHC version 7.4.1 for i386-unknown-linux): pipeLoop: at phase As but I wanted to stop at phase HCc Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug ------------------------------------------- 1. A bug report. 2. How to see this C code? What GHC version shows it? If you have such a version installed, can you, please, send me the C code? Regards, ------ Sergei mechvel@botik.ru