Greetings, First of all to people reading this at ghc-devs, I don't expect this to be a direct problem caused by GHC but who knows, so I'm CC'ing it anyway. As you might know, GHC 7.8.1 is scheduled to release Very Soon™ (later today?). We got a report at Haddock Trac few weeks ago about a strange error, see http://trac.haskell.org/haddock/ticket/284. I have asked about this on cabal-devel before and Mikhail said that maybe it's https://github.com/haskell/cabal/pull/1374 but it's unlikely because the changes aren't ran by default. Today I got new reports of this problem and so far everyone on OSX seems to be affected! This suddenly became a big problem. To replicate: 1. Find OSX machine 2. Get GHC 7.8 rc2 package (which includes Haddock at that stage) 3. git clone git@github.com:ekmett/free.git && cd free 4. cabal install --only-dependencies --enable-documentation && cabal configure && cabal haddock The reason I'm barking up cabal-devel and ghc-devs is because I honestly can not think of anything that has changed since Haddock 2.13.2.1 that could possibly cause this. Does anyone have any idea at all? I think it would be very bad to release now and have everyone on OSX unable to build docs. FYI I get build docs on 32-bit Linux. No idea about Windows. Thanks, I hope to hear back soon. PS: How does one go about downgrading Cabal and cabal-install? If we wanted to check whether cabal is the problem, how? -- Mateusz K.