GHC dies silently with faulty preprocessor
This is perhaps a minor nuisance but I had to spend quite some time to track down my bug. When ghc is given a preprocessor which for some reason cannot execute then ghc just dies silently without giving any indication as to what the problem was. It would be nice with a little message hinting at the problem on stderr. Oh, and by the way, the -F flag doesn't have any documentation. It is only mentioned together with -optF.