Initial build report of Hackage with GHC 6.10

[Don Stewart]

Hey guys,

Here's a summary of what builds out of the box, and what doesn't, from
hackage, with today's amd64 GHC RC. The initial system was just GHC
6.10, with cabal-install from darcs (the upcoming cabal-install
release).

The initial package list was based on the 700 or so packages
in http://haskell.org/~duncan/cabal/pkgs-6.10 and we run it like:

    $ cabal install -O0 $(cat pkgs-6.10)

*232 packages built* (out of >700). The build results are attached below.

The majority of failures were due to the following packages not
building:

      6 wxcore-0.10.3
      8 SDL-0.5.4
      8 haskell-src-exts-0.3.7
     10 X11-1.4.3
     12 haskell-src-1.0.1.2
     47 QuickCheck-1.1.0.0
    119 network-2.2.0.0

Now, why did these fail?

network/haskell-src fail due to needing syb, and thus base-3:

    Language/Haskell/Syntax.hs:67:7:
        Could not find module `Data.Generics.Instances':
          it is a member of package base-3.0.3.0, which is hidden

    Network/URI.hs:128:7:
        Could not find module `Data.Generics':
          it is a member of package base-3.0.3.0, which is hidden

while QuickCheck fails due to needing the old exception thing, and again base-3.

So that gives us a ballpark figure. About 200 packages or so fail if we *default*
to base-4. Some of these we can just fix the version constraints, or we
can *fix a bunch of things* by uploading new versions of the key
packages with base >= 3 && < 4 set.

We should audit the extra-libs for this constraint.

So the next round is to add a "soft constraint":

    base<4

to the "preferred-versions" file, and add it to my 00-index.tar.gz. At which
point cabal-install will take this as a soft constraint to add to the
dependency resolution tricks.

This should improve things quite a bit. More results to follow...

-- Don