I needed to look into the C code made by ghc-7.4.1
GHC doesn't write C source any more.
Warning: The -fvia-C flag does nothing; it will be removed in a future GHC release
which is what this is telling you
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
and this appears to be a symptom of it not having been completely removed; the phase it wants to stop at no longer exists so it's getting caught after the fact. "Oops"
2. How to see this C code? What GHC version shows it?
ghc6.x supported -fvia-C, ghc7.x does not. Modern ghc uses a more efficient native code generator instead of going through C.
Why is the purported C code supposed to be useful?