Support for custom GHC bindists?

ghcup can already do that. There's an undocumented option that I use during development: https://gitlab.haskell.org/haskell/ghcup-hs/-/blob/master/app/ghcup/Main.hs#L146-154

So if you do: ghcup -s https://some-url/foo.json install 8.8.3, then it will download foo.json and use the download information from there, which includes GHC versions, the tarballs etc.

See:

The type of download information: https://gitlab.haskell.org/haskell/ghcup-hs/-/blob/master/lib/GHCup/Types.hs#L54
The current download content: https://gitlab.haskell.org/haskell/ghcup-hs/-/blob/master/app/ghcup-gen/GHCupDownloads.hs
The haskell executable ghcup-gen generating JSON out of it: https://gitlab.haskell.org/haskell/ghcup-hs/-/blob/master/app/ghcup-gen/Main.hs
The pretty-printed json: https://gitlab.haskell.org/haskell/ghcup-hs/-/blob/master/ghcup-0.0.1.json

You should be able to modify this, either the JSON directly or change the haskell code in GHCupDownloads.hs, then run:

cabal run ghcup-gen -- gen -f ghcup-0.0.1.json
cabal run ghcup-gen -- check -f ghcup-0.0.1.json

Also note that file:///foo/bar is a valid URL scheme in ghcup, both for tarballs and the json file.

added typesupport label

As an example, I just added the 8.10.1-p1 (imaginary patch release) to the download info and tested:

      , ( [vver|8.10.1-p1|]
        , VersionInfo
            []
            Nothing
            Nothing
          $ M.fromList
              [ ( A_64
                , M.fromList
                  [ ( Linux UnknownLinux
                    , M.fromList
                      [ ( Nothing
                        ,
                        (DownloadInfo
                         [uri|https://downloads.haskell.org/~ghc/8.10.1/ghc-8.10.1-x86_64-fedora27-linux.tar.xz|]
  (Just [rel|ghc-8.10.1|])
  "3c4cd72b4806045779739e8f5d1658e30e57123d88c2c8966422cdbcae448470"
                          )
                        )
                      ]
                    )
                  ]
                )
              ]
        )

Ran: cabal run -w ghc-8.8.3 ghcup-gen -- gen -f ghcup-0.0.1.json -p

Then: cabal run -w ghc-8.8.3 ghcup -- -s file://$(pwd)/ghcup-0.0.1.json -c list

Output:

[..]                        
✓  ghc   8.8.3      recommended        
✗  ghc   8.10.1     latest             
✗  ghc   8.10.1-p1                    
[..]

Installation/removal/setting works. So I believe you can create a patch-tarball, such as: ghc-8.10.0-p1-x86_64-linux.tar.xz and just add that to the download info as above.

But there's currently no option around other than than maintaining your own ghcup.json download info and making sure it's in sync with the upstream one. It shouldn't be hard, since its haskell code and you can just rebase your commit/branch on top of master regularly.

Thinking about it: it would probably not be hard to add functionality to merge an additional download info into the default one. It could live entirely in Main.hs, so it doesn't pollute the actual API, but I'm not really sure if that's a strong enough use case.

@TerrorJack does that suffice?

Sorry for the late response; yes, the workflow of manually generating the JSON first suffices to get custom bindists running. Maybe adding a command line option to specify the bindist URL directly would make it more convenient though. Thanks for the detailed writeup!

@TerrorJack that's certainly possible. The minimal information we need of a bindist is:

URL
Version of GHC (this can't be reliably inferred from URL)
subdirectory of the tar archive, where the configure script resides

Since the bindist isn't part of the download info, it won't show up in 'ghcup list' until you installed it.

Another point: the help output is already huge, so I'm inclined to keep new edge case commands hidden from it.

closed via commit dad926f3

This is now in master. Example:

ghcup -n install ghc -u '{"dlHash": "", "dlSubdir": "ghc-8.10.1", "dlUri": "https://github.com/commercialhaskell/ghc/releases/download/ghc-8.10.1-release/ghc-8.10.1-x86_64-deb9-linux.tar.xz"}' 8.10.1

Will be in 0.1.8 release shortly.

mentioned in merge request !42 (merged)

Support for custom GHC bindists?

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