Error “unknown package: ghc” when building heroku app with yesod

Question

I'm trying to build a heroku app with a new version of yesod (1.1.9), unfortunately it fails becauce of the ghc-paths dependency (yesod version 1.1.2 works since it does not have this dependency). I tried various dependencies and all possible ghc-paths versions, but in the end I always get this awkward error message that ghc is an unknown package. A local build works just fine with the same dependencies.

main-is:           main.hs
hs-source-dirs:    app
build-depends:   base          == 4.5.*
                 , http-types
                 , shakespeare == 1.0.2
                 , template-haskell 
                 , wai           
                 , wai-extra     
                 , warp          
                 , yesod         == 1.1.9

.

[176] rejecting: ghc-paths-0.1.0.9 (unknown package: ghc)
[__6] fail (backjumping, conflict set: TestHeroku, ghc, yesod)
[__5] rejecting: yesod-1.1.8.2, ... , 0.0.0.2, 0.0.0.1, 0.0.0 (conflict: TestHeroku => yesod==1.1.9)
[__0] fail (backjumping, conflict set: TestHeroku, ghc, yesod)

Shakespeare is needed because of the error mentioned here and I use the heroku-buildpack-haskell .

Answer 1

If anyone struggles with the same problem, I took matters into my own hands and created a new buildpack based on the versions that are already circulating. It runs with yesod-1.1.9.

https://github.com/ichistmeinname/heroku-buildpack-haskell