Building Haddock documentation on Windows for larger packages (e.g. OpenGLRaw) is broken in 7.10.2, similar to linking: The reason is once again the silly Windows command line length limitation, so we need response files here, too. Haddock 2.16.1 already has support for this, but this seems to be broken (probably https://github.com/haskell/haddock/commit/9affe8f6b3a9b07367c8c14162aecea8b15856a6 is missing), see the corresponding check in cabal (https://github.com/haskell/cabal/blob/master/Cabal/Distribution/Simple/Haddock.hs#L470).

So in a nutshell: We would need a new Haddock release (bundled with GHC 7.10.3) and a new cabal release with support for Haddock response files (in cabal's HEAD, but not yet released). Would this be possible?