Module import code action ignores reexported-modules

[guibou]

Your environment

Which OS do you use: Linux
Which LSP client (editor/plugin) do you use: NeoVim + lspconfig
Describe your project (alternative: link to the project): https://github.com/guibou/repro_hls_base_no_prelude

Steps to reproduce

You can checkout https://github.com/guibou/repro_hls_base_no_prelude, it contains two cabal project with one Main.hs file with the following content:

{-# LANGUAGE NoImplicitPrelude #-}
module Main where

main :: IO ()
main = putStrLn "Hello, Haskell!"

Expected behaviour

The code above should not typecheck (i.e. IO is not in scope). Code action on the offending line should suggestion to import a few module, such as System.IO or Prelude.

Actual behaviour

There is two variations in the sample codebase.

• One is a project with base as a dependency. Code action works as expected and suggest to import System.IO (as well as other modules from base which exports IO).

• The second project uses base-noprelude as a dependency. base-noprelude is a package which reexport all modules from base but Prelude. System.IO is exported, see: https://github.com/haskell-hvr/base-noprelude/blob/master/base-noprelude.cabal#L232, However, code action does not suggest to import System.IO:

Note that in both cases, importing System.IO fixs the type error.

[jhrcek]

Could you please share the precise version of haskell-language-server you're using?
I was experiencing similar issue (we're also using base-noprelude) and I think I fixed the problem in #2468
If it doesn't help with your issue, that fix might need to be revisited.

Here's what the code action offers to me in your reproducer project (haskell-language-server built from current master):

[guibou]

That's a super question that I should have answered when opening the issue.

• In my repro example, I use 1.5.1.0 as available in nixpkgs, so I suppose that's 1.5.1.0
• In my main repo, I use 87a69c2

Both are actually older than your #2468 so hey, the fix may already be there.

I'll try when next version will be released, the nix flake for current dev version does not work anymore (see #2030).

Thank you for your time.

[guibou]

@jhrcek I was able to test with latest HLS (master) and indeed the bug is fixed.

Thank you for your work, sorry for the noise, have a nice year!

[jhrcek]

@guibou thank you for confirming, my pleasure that the fix is useful for others.
Happy new year to you too 😄