Not in scope: type variable 'a'

[dmjio]

Unsure if this has been resolved, nixpkgs-unstable and nixos-unstable are running into this issue when attempting to build ghc-api-ghcjs before ghcjs.

dist/build/Parser.hs:1473:48: error:
    Not in scope: type variable ‘a’
     |
1473 | newtype HappyWrap209 = HappyWrap209 (([Located a],Bool))
     |   ```

[dmjio]

Using an older happy fixed this, cc @cocreature

[matthewbauer]

I just noticed this with ghcHEAD as well:

https://hydra.nixos.org/build/93826143

Is there some extension needed here?

[cdsmith]

@dmjio I'm running into this same problem. Which version of happy worked for you?

[dmjio]

@cdsmith, ended up using 1.19.9 per @cocreature's advice.

 happy = dontCheck (super.callHackage "happy" "1.19.9" {});

made things "happy" for me.

[matthewbauer]

Upstream bug: https://gitlab.haskell.org/ghc/ghc/issues/16652

[cdsmith]

Thanks!

[dmjio]

Think we're good here, please re-open if not.