On Mon, 25 Mar 2013, Andreas Voellmy wrote:

Sure, I can do that, but then I get:
$ cabal install --disable-library-profiling 
Resolving dependencies...
Configuring foo-1.0...
cabal: The field 'build-depends: foo' refers to a library which is defined
within the same package. To use this feature the package must specify at least
'cabal-version: >= 1.8'.
Failed to install foo-1.0
cabal: Error: some packages failed to install:
foo-1.0 failed during the configure step. The exception was:
ExitFailure 1

Maybe I could try with cabal-version >= 1.8, but this doesn't seem like it should be necessary. I wouldn't
need this build-depends: foo if A were just A.hs, right? So it seems odd (from a user's standpoint) that I
need it when it is A.hsc.

I don't think that this depends on the HSC preprocessing. With A.hs it would be the same problem. Have you tried it?