I've been getting a mysterious error for a while now. It's come and gone, but seems to be showing up slightly more consistently now. Before I was on ghc 6.8.2 and now I'm on ghc 6.8.3, OS X 10.4 and now 10.5, i386 arch. The problem is that randomly while compiling I get an error like this: unknown flags in {-# OPTIONS #-} pragma: -XDeriveDataTypeabl<Data/Array/IArray.hs" #<e Ui.Font ( TextStyle(..), Font(..), FontFace(..) ) where import qualified Data.Generics as <Data/Array/IArray.lhs.L<array-0.1.0.0ali<Color as Color import Foreign import qualified Ui.Util as Util {-# LINE 14 "Ui/Font.hsc" It looks like somehow pragma parsing gets a bunch of random junk scrambled in. In the past this would happen consistently until I did a make clean and rebuild, but more recently all I have to do is try again and it doesn't happen the second time. I haven't gotten it while compiling for a while, but since I'm using hint which uses the ghc api to interpret haskell, I'm getting this quite frequently inside a GhcException when hint wants to interpret some code. I've also gotten this from ghci occasionally, and the usual fix is just to do a reload, and the second time it works. Does this sound familiar to anyone? It's not fatal since a retry clears things up, but it's a little worrying and would not look very good in released software. I cast about a bit on the ghc trac and didn't find any open bugs like this.