RE: problems building ghc 6.4.1_pre using 6.4 with multiple cabalversions installed

On Mon, 2005-09-12 at 13:33 +0100, Simon Marlow wrote:
> Quite right this is a problem, and it looks like something we should fix
> before 6.4.1.  I'll give it some thought.

Hi Simon, glad to have you back! :-)

Andres Loeh has looked into this a bit in the last few days. He's
knocked up this patch which we're using in our Gentoo ebuilds for recent
ghc-6.4.1 snapshots (2005/08/19 and 2005/09/09):

http://haskell.org/~gentoo/gentoo-haskell/portage/dev-lang/ghc/files/ghc-6.4.1-nocabal.patch

The patch is to make it build without using any existing installation of
Cabal. So it'll work if there is no Cabal, 1 cabal or 2+ Cabal versions
installed. Andres's disclamer is that it might make some gentoo-specific
assumptions.

Duncan

> On 24 August 2005 14:42, Duncan Coutts wrote:
> 
> > With our current 6.4.1 snapshot 20050819, we have problems building
> > when we've got more than over version of cabal registered.
> > 
> > That is we build it using ghc 6.4 and we have cabal-1.0 and
> > cabal-1.1.2 installed. Then it complains that multiple packages match
> > "-package cabal".
> > 
> > It also has problems when no version of cabal is registered.
> > 
> > There is no problem building with ghc 6.2.2 with no cabal installed.
> > 
> > I think it would be much more reliable if ghc did not rely on the
> > version of cabal installed and registered with ghc 6.4. Since it has
> > to work without cabal anyway (for the 6.2.2 case), wouldn't it be
> > possible to make it ignore any installed version of cabal even when
> > building with ghc 6.4?
> > 
> > At the moment, it looks like we're going to have problems on gentoo
> > upgrading users from ghc 6.4 to 6.4.1. Our current idea is to
> > unregister the Cabal-1.0 package that ghc 6.4 comes with and use a
> > later version (Cabal-1.1.2 at the moment) however it's not clear that
> > ghc will cope with using the later version. We need to install the
> > later version anyway for other reasons (version 1.0 has bugs and
> > lacks some features we need for reasonable packaging) and ghc 6.4
> > does not cope very well with having multiple versions of a package
> > installed (this is improved in 6.4.1), hence the rationale for
> > unregistering the 1.0 version entirely.