Missing plugins for GHC 9.12.2 in 2.10.0.0

[svenpanne]

Your environment

Which OS do you use?
Windows

Which version of GHC do you use and how did you install it?
9.12.2 from ghcup

Which version of HLS do you use and how did you install it?
2.10.0.0 from ghcup

Steps to reproduce

Use ghcup tui to install HLS 2.10.0.0. Compare the plugins for GHC 9.10.1 and 9.12.2:

PS C:\Users\svenp> Compare-Object (haskell-language-server-9.10.1.exe --list-plugins) (haskell-language-server-9.12.2.exe --list-plugins)

Output:

InputObject                                                                         SideIndicator
-----------                                                                         -------------
cabal-gild:                                                                         <=
    Provides formatting of cabal files with cabal-gild                              <=
fourmolu:                                                                           <=
    Provides formatting of Haskell files via fourmolu. Built with fourmolu-0.16.2.0 <=
gadt:                                                                               <=
    Provides a code action to convert datatypes to GADT syntax                      <=
ghcide-code-actions-bindings:                                                       <=
    Provides various quick fixes for bindings                                       <=
ghcide-code-actions-fill-holes:                                                     <=
    Provides a code action to fill a hole                                           <=
ghcide-code-actions-imports-exports:                                                <=
    Provides various quick fixes                                                    <=
ghcide-code-actions-type-signatures:                                                <=
    Provides various quick fixes for type signatures                                <=
ghcide-extend-import-action:                                                        <=
    Provides a command to extend the import list                                    <=
ormolu:                                                                             <=
    Provides formatting of Haskell files via ormolu. Built with ormolu-0.7.7.0      <=
rename:                                                                             <=
    Provides renaming of Haskell identifiers                                        <=
stan:                                                                               <=
    Provides stan diagnostics. Built with stan-0.2.0.0                              <=

Expected behaviour

The essential plugins for the latest GHC 9.12.2 are there and the docs are up-to-date.

Actual behaviour

The documentation regarding the supported plugins is out-of-sync with the actual implementation for 9.12.2, e.g. quite a few essential things are missing: Neither ormolu nor fourmolu is supported (i.e. no formatter present), rename is missing (very essential, no idea why this is tier 2 and not tier 1), etc.

Is there a place in the source code where one can easily see what is actually supported? Downloading the HLS just to find out that it is effectively unusable for 9.12.2 at the moment is a bit suboptimal.

[fendor]

Hi thanks for the bug report!

Unfortunately, I forgot to accurately update the docs for the release of 2.10.0.0, which is why the information is outdated on the release docs https://haskell-language-server.readthedocs.io/en/2.10.0.0/support/plugin-support.html.

The current docs with the "latest" tag accurately represent what HLS HEAD supports.
As there will be a 2.11.0.0 release, this should fix this out-of-date docs.

Is there a place in the source code where one can easily see what is actually supported?

The test CI can be used to get that information from the source code directly, or the haskell-language-server.cabal file.

https://github.com/haskell/haskell-language-server/blob/wip/2.10.0.0/.github/workflows/test.yml

[fendor]

I updated the release branch, but I couldn't nudge readthedocs to actually update, as it only builds off the tag, not the branch. But I don't want to modify the release tag to fix this :(

[svenpanne]

Is there already a plan for the next HLS release with better 9.12 support? AFAICT, the master branch already supports a few more plugins. And IMHO a language server without support for basic things like formatting or renaming is effectively useless, so 9.12 is currently not really supported at all. At least it's hard to sell to co-workers in 2025... 😟

[fendor]

Yes, a release is scheduled to happen this week.

9.12 is currently not really supported at all.

Yes, it only has "basic" support, see https://haskell-language-server.readthedocs.io/en/stable/support/ghc-version-support.html. That's actually documented right now. GHC 9.12.2 is rather new, so it is to be expected that full support takes a release or two.