RE: problems building ghc 6.4.1_pre using 6.4 with multiplecabalversions installed

Just glancing over the patch, I can't immediately see how it works.  GHC
6.4 gives priority to package modules over modules on the local search
path, so Distribution.* will be taken from the installed Cabal package.
However, when linking GHC you are ommitting -package Cabal, so I'd
expect a link error.

Hmm, I guess I should try this and figure out what's happening.

Cheers,
        Simon

On 12 September 2005 15:53, Duncan Coutts wrote:

> 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.
> 
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