ghc-8.4.2 fails to build due to haddock-api-2.19.0.1 requiring ghc-8.4.1

[newhoggy]

stack --stack-yaml=stack.yaml install                                      \
        && cp '/Users/jky/.local/bin/hie' '/Users/jky/.local/bin/hie-8.4.2'    \
        && cp '/Users/jky/.local/bin/hie-8.4.2' '/Users/jky/.local/bin/hie-8.4'

Error: While constructing the build plan, the following exceptions were encountered:

In the dependencies for haddock-api-2.19.0.1:
    ghc-8.4.2 from stack configuration does not match ==8.4.1  (latest matching version is 8.4.1)
needed due to haskell-ide-engine-0.2.0.0 -> haddock-api-2.19.0.1

Some different approaches to resolving this:

  * Set 'allow-newer: true' to ignore all version constraints and build anyway.

  * Consider trying 'stack solver', which uses the cabal-install solver to attempt to find some working build
    configuration. This can be convenient when dealing with many complicated constraint errors, but results may be
    unpredictable.

  * Recommended action: try adding the following to your extra-deps
    in /Users/jky/wrk/arbor-networks/haskell-ide-engine/stack.yaml:

- ghc-8.4.1

Plan construction failed.
make: *** [hie-8.4.2] Error 1

[alanz]

Are you building with current master? I'm pretty sure this was fixed with https://github.com/haskell/haskell-ide-engine/commit/4af12c1edabb8a04c1591e841a2a03e3f22d4489

circleci is happy : https://circleci.com/workflow-run/c33c0e53-b7fa-4ac1-bb2b-6024b4442a55

[egormkn]

I have the same problem. Haddock-api requires ==8.4.1, that was changed in its latest revision two days ago.

[wz1000]

We need haddock-api-2.20, which is not on hackage as of yet.

/cc @hvr @alexbiehl

[hvr]

The revision was made because haddock-api-1.19 is in fact incompatible with GHC 8.4.2 for the on-disk formats. We should be able to release haddock-api-2.20 RSN!