On Sat, Dec 15, 2012 at 08:13:44AM +0100, Petr P wrote:
> This is strange, I thought that cpphs should be specified in
> "build-tools:", not in "build-depends:".
> <
> http://www.haskell.org/cabal/users-guide/developing-packages.html#build-information
> >
>
> Best regards,
> Petr

Presumably the reason to list it in build-depends instead of
build-tools is that in the latter case cabal will not automatically
install it as a dependency.  But you are right that this is a strange
situation, since if it is being used only as a preprocessor,
semantically it ought to be listed in build-tools.