error with package ghc-6.10.1 and its dependency on process-1.0.1.[01]

Thomas Schilling nominolo at
Tue Nov 25 11:59:44 EST 2008

2008/11/25 allan <a.d.clark at>:
> Hi Duncan and Thomas
> Thanks for the help, unfortunately:
> -----------------------------------------------------
> allan at delgado:~$ ghc-pkg unregister --user Cabal-
> Writing new package config file... done.
> allan at delgado:~$ cabal install haddock
> Resolving dependencies...
> cabal: dependencies conflict: ghc-6.10.1 requires process == however
> process- was excluded because ghc-6.10.1 requires process ==
> allan at delgado:~$ ghc-pkg unregister Cabal-
> ghc-pkg: unregistering Cabal- would break the following packages: haddock-2.3.0 ghc-6.10.1 (use --
> ------------------------------------------------------

haskell98 also creates a transitive dependency on process and also
shadows the system one.

What happens if you do

  # cabal install -v --global haddock

This should ignore all the user packages.  There's definitely room for
improvement in cabal-install here.

> I tried to unregister haddock and then ghc and tried to re-register ghc (by doing 'make install' in the ghc source directory).
> Unfortunately this put me back in the same place again.
> To provide a bit more information this all comes from a recent upgrade to ghc-6.10.1.
> As you can see from the package listing in the previous mail, there aren't that many installed packages (over those installed by ghc).
> It seems a little strange that this is not a problem for everyone else. It looks to me (albeit inexperienced) that the error occurs during the ghc "make install" target, but then if that were the case I can't see why the same thing wouldn't happen to everyone.
> regards
> allan
> Duncan Coutts wrote:
>> On Mon, 2008-11-24 at 20:05 +0000, Thomas Schilling wrote:
>>> Could it be that the cabal gets confused because there are two
>>> versions of Cabal- but which probably depend on two different
>>> versions of process?
>> That could well be it. The user and global package dbs simply get
>> overlayed so identical package versions in the user-db mask ones in the
>> global db. So that would indeed mean that cabal would think that the ghc
>> global package depended on the Cabal package from the user db, which is
>> built against the different version of the process lib.
>> So the workaround for Allan would be to unregister the Cabal-
>> from the user db: ghc-pkg unregister --user Cabal-
>> and probably to rebuild anything that depends on it.
>> We'll have to think about if there's a better way to manage this. In the
>> longer term I'd like to use hashes to identify installed packages but
>> for now...
>> Duncan
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Push the envelope.  Watch it bend.

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