Linking dist/build/darcs/darcs ...
Running Haddock for darcs-2.3.1...
Preprocessing library darcs-2.3.1...
Preprocessing executables for darcs-2.3.1...
Warning: The documentation for the following packages are not installed. No
links will be generated to these packages: base-3.0.3.2, ffi-1.0, rts-1.0

src/Darcs/Repository/Prefs.lhs:127:0:  error: unterminated comment

Let's fill out the 4 corners of this square:

Cabal 1.6.x - darcs 2.3.1 - ok
Cabal 1.6.x - darcs HEAD  - ok
Cabal 1.8.x - darcs 2.3.1 - FAIL
Cabal 1.8.x - darcs HEAD  - unknown

Duncan mention that there are changes in Cabal 1.8:

<dcoutts> ok so the difference is that Cabal-1.8 pre-processes before passing it
to haddock
<dcoutts> Cabal-1.6 just gave it all to haddock
<dcoutts> and the fact is that gcc -E does claim it's an unterminated comment
<dcoutts> what is somewhat surprising is that it did not fail before using haddock
 since we did pass --optghc-XCPP
 so haddock should have been running cpp on every file
<ivanm> dcoutts: is it the fact that it's .lhs a possible factor?
<dcoutts> ivanm: oh, maybe so. I think ghc does unlit and cpp in the wrong order
<ivanm> *nod*
<dcoutts> so it would do unlit first then cpp
 which in this case would help
 ivanm: yes I think that's it
<dcoutts> kowey: so the fix is simple
<dcoutts> just don't use /* */ style comments

Looks like there is a clear fix for this... could we get a volunteer?

dcoutts> So the fix is simple: just don't use /* */ style comments.

kowey> Looks like there is a clear fix for this... could we get a
kowey> volunteer?

There aren't any C comments in .lhs files in HEAD:

    $ grep -r '/\*\|\*/' --exclude-dir darcs --include '*.lhs' .
    ./src/Darcs/Commands/Dist.lhs: "  project=${PWD##*/} &&\n" ++
    ./src/Darcs/Patch/Match.lhs:          , ["src/foo.c", "src/", "\"src/*.(c|h)\""]
    ./src/Darcs/Repository/Prefs.lhs:simple \verb-darcs add newdir newdir/*-

Trent W. Buck wrote:
> There aren't any C comments in .lhs files in HEAD:
>
>     $ grep -r '/\*\|\*/' --exclude-dir darcs --include '*.lhs' .
>     ./src/Darcs/Commands/Dist.lhs: "  project=${PWD##*/} &&\n" ++
>     ./src/Darcs/Patch/Match.lhs:          , ["src/foo.c", "src/", "\"src/*.(c|h)\""]
>     ./src/Darcs/Repository/Prefs.lhs:simple \verb-darcs add newdir newdir/*-

Never mind; I see from patches on darcs-users that the problem is that
these *look* like C comments, but aren't.

It would be very clumsy to have a 2.4 release that can't build documentation
with the latest Cabal.

Do we know what package is ultimately responsible for this failure? Is it GNU
cpp, cpphs or haskell-src-exts that breaks its brain here?

The following patch updated the status of issue1720 to be resolved:

* Resolve issue1720:  Fix cabal haddock problem. 
Ignore-this: 1521b3a742711ac3ee979efc765f6b61