Hello,
I have a package that uses custom Setup.hs file that requires Cabal library at least in version 1.22. I need to build the package with GHC 7.8.

With cabal it is enough to cabal install cabal — and then Setup.hs will be linked against the latest Cabal library. Using GHC 7.8 with it works seamlessly.

How can I tell stack to use newer Cabal version for Setup.hs?

I tried adding Cabal-1.22.4.0 to the extra-deps field but it does not help — apparently the newer Cabal will be available to the built package but not its Setup.hs. It still gets Cabal-1.18.1.5 that comes with GHC 7.8.