Problems building ghc-current

[Volker Stolz]

In local.glasgow-haskell-users, you wrote:
> | 2.4. Updating Your Source Tree
> | It can be tempting to cvs update just part of a source tree to bring in
> | some changes that someone else has made, or before committing your own
> | changes. This is NOT RECOMMENDED! [...]
> |
> | So, to avoid a lot of hassle, follow this recipe for updating your tree:
> | $ cd fptools
> | $ cvs update -Pd 2>&1 | tee log
> 
> The '-P' flag (prune) suppresses empty directories in the update.

Hm, okay, probably -dP is the same as -Pd. You're right, this in fact
pulls in all the stuff from the entire tree. There probably should be a
warning attached to this line.

> > You probably won't need greencard anyway, so maybe it's best to wipe it
> > from the disk (and all the other unrelated stuff).
> 
> I have no problem with that. I think this situation is unsatisfactory,
> though, I'll have to cvs-update my source repository in two, maybe three
> separate steps, to avoid checking everything out _again_.

A safe bet is simply invoking 'cvs update' in fptools (w/o -d) and only
checking for new directories if you need to. Reasoning:

- If you just need one GHC from CVS, you've got a fresh checkout and
    only want to track minimal changes, e.g. to the STABLE branch where
    new directories probably won't be created (hmm, not quite true for
    the hierarcichal libraries now...)
- You really track HEAD, in which case you know what you're doing anyway :)

This is far from optimal, but hard to do any better. But as I said,
that line in the building guide really ought to be fixed. Thanks for
pointing this out!

Volker
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