ndmitchell / ndmitchell/hoogle
Parsing of ghc-pkg output by Input.Cabal.readGhcPkg is broken
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- Dominant language
- Haskell
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- 803
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Description
Different versions of GHC have different output format for ghc-pkg. For example I got different output under GHC 8.2.2 vs GHC 8.8.3: https://gist.github.com/jchia/cf4412d7402f7bfeb01324b9cd537986
One way the brokenness manifests is that with GHC 8.8.3, hoogle generate thinks that the packageDocs is Just "", and that the package name has some leading spaces, resulting in hoogle generate failing with "No packages were found, aborting (use no arguments to index all of Stackage)" because it thinks that none of the packages have documentation.
What about using Distribution.InstalledPackageInfo from Cabal? It may be a big change, but this way is less fragile than internal ad-hoc parsing, and I don't know what other problems there are already that result from broken parsing.
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Research direction
Start in Input.Cabal.readGhcPkg and compare its parsing assumptions with the GHC 8.2.2 and 8.8.3 ghc-pkg output linked in the issue. Investigate whether Distribution.InstalledPackageInfo from Cabal can replace the ad-hoc parsing. Done means hoogle generate discovers packages and their documentation across the reported GHC versions.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- haskell
- Domain
- tooling
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100