ghc-lib-parser-9.10.1.20240511 no longer builds

[Tritlo]

There seems to be a missing version bound for happy. happy-2.0 was released today (or so I gather), and now I get the following error when trying to cabal install:

dist/build/GHC/Parser.hs:5975:24: error: [GHC-58481]
    parse error on input ‘<-’
    Suggested fix: Possibly caused by a missing 'do'?
     |
5975 |                   ; mg <- mkPatSynMatchGroup name happy_var_5
     |                        ^^

It seems we need a version bound on happy to happy-1.20 until this issue is fixed,
see haskell/happy#303

[geekosaur]

FWIW it built fine for me with happy-1.20.1.1, then I did cabal update; cabal install happy; cabal install --lib --package-env=. haskell-lib-parser and got the above error.

[sgraf812]

I deprecated happy-2.0 and am hopeful that the just-released happy-2.0.1 fixes the issue.

[Tritlo]

It's working again! I still think we should consider some versions bounds to prevent a similar situation in the future.