ANNOUNCE: GHC 7.10.1 Release Candidate 1 - feedback on Mac OS

[Herbert Valerio Riedel]

On 2015-01-01 at 14:58:40 +0100, George Colpitts wrote:
> I built from source on Mac OS and found the following issues:

[...]

>    - ​cabal install cpphs fails:​
>    -    cabal install cpphs
>       Resolving dependencies...
>       Configuring cpphs-1.13...
>       Building cpphs-1.13...
>       Failed to install cpphs-1.13
>       Build log ( /Users/gcolpitts/.cabal/logs/cpphs-1.13.log ):
>       Warning: cpphs.cabal: Unknown fields: build-depends (line 5)
>       Fields allowed in this section:
>       name, version, cabal-version, build-type, license, license-file,
>       license-files, copyright, maintainer, stability, homepage,
>       package-url, bug-reports, synopsis, description, category, author,
>       tested-with, data-files, data-dir, extra-source-files,
>       extra-tmp-files, extra-doc-files
>       Configuring cpphs-1.13...
>       Building cpphs-1.13...
>       Preprocessing library cpphs-1.13...
>       - Language/Preprocessor/Cpphs.hs:1:1:
>           Could not find module ‘Prelude’
>           It is a member of the hidden package ‘base-4.8.0.0’.
>           Perhaps you need to add ‘base’ to the build-depends in your
>       .cabal file.
>           Use -v to see a list of the files searched for.

[...]

This is a known issue; cpphs-1.18.6 would actually work with GHC
7.10/base-4.8, but it depends on polyparse, but there isn't yet a
polyparse version compatible w/ base-4.8 (due to AMP) on Hackage[1]

Otoh, cpphs-1.13 is selected even though Hackage shows that it has a
constraint `base <4.8`. However, that's rather a bug in Hackage, as the
`.cabal` file is actually invalid, as it has the `build-depends` at the
wrong level. So effectively it has no build-depends line at all, so
cabal-install is led to believe that it works w/o any build-deps at
all.. I did file an issue about that[3]








 [1]: Coincidentally, I sent Malcolm a AMP-compatibility patch for
      polyparse just earlier today...

 [2]: http://hackage.haskell.org/package/cpphs-1.13

 [3]: https://github.com/haskell/hackage-server/issues/303