Daily report for head
marlowsd at gmail.com
Tue Aug 26 09:45:15 EDT 2008
Duncan Coutts wrote:
> On Tue, 2008-08-26 at 09:40 +0100, Simon Marlow wrote:
>> Claus Reinke wrote:
>>> Of course, warnings like
>>> Configuring html-22.214.171.124...
>>> Warning: This package indirectly depends on multiple versions of the
>>> package. This is highly likely to cause a compile failure.
>>> package html-126.96.36.199 requires base-188.8.131.52
>>> package unique-0.1 requires base-4.0
>>> package timeout-0.1 requires base-4.0
>>> package st-0.1 requires base-4.0
>>> package getopt-0.1 requires base-4.0
>>> package concurrent-0.1 requires base-4.0
>>> package base-184.108.40.206 requires base-4.0
>>> aren't really confidence-inspiring wrt to the base-compat solution,
>> These warnings are harmless when they refer to base-3 vs. base-4, as you
>> probably realised. We should make sure that the Cabal we ship with GHC
>> 6.10.1 doesn't emit these warnings though - Duncan, is that doable?
> We can hack it for the special case of base, or try and be slightly more
> general and not complain when the two versions that get pulled in
> directly depend on each other. In general there's no simple way for
> Cabal to know if using multiple versions of a package is going to work
> on not. It's quite unsatisfactory.
If there's a dependency, direct or indirect, between the two versions of
the package then it is ok to include them in the same program. The only
way this could occur is if the two versions are intended to be used
together, otherwise it would be a dependency loop. (you could approximate
this by checking for direct dependencies only, which will cover all cases
we're likely to see in the near future).
> It's going to be even worse for the dep planning. I'm not sure how to
> solve it yet.
So if you establish that base-3 and base-4 can coexist using the above
rule, can you then use that information when deciding whether two packages
can both be present in the plan?
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