The release announcement for the current beta implies that ghc 6.12
isn't supported (and it fails at least because of issue2161 and
issue2162), but the cabal file doesn't exclude 6.12.  It specifies
ghc >= 6.10 && < 7.6 and says
  Tested-with:    GHC==6.8.2
I'm looking at http://darcs.net/releases/next and the 2.7.99.1 tag.

It's unfortunate if 6.12 isn't supported, as that seems to be the latest
that's packaged for current Debian stable and Ubuntu LTS.

Thanks for the report. The omission of 6.12 from the announcement was an 
error (caused by needing to manually exclude 7.2 from the range). We 
failed to include the fixes for issue2161 and issue2162 in branch-2.8, 
but have done so now. Could you try from the release branch again now? 
It does build for me with 6.12.

I will also check on 6.10 and probably remove that out-of-date Tested-
with.

Ganesh Sittampalam <bugs@darcs.net> writes:

> Could you try from the release branch again now? 
> It does build for me with 6.12.

You are not alone.  Thanks.

This sounds to have been resolved.