Shouldn't hie-wrapper be started in the root directory? about lsp-haskell

[Ptival]

Fixed by:

(add-hook! 'haskell-mode-hook
  (setq lsp-haskell-process-args-hie (list "-d" "-l" "/tmp/hie.log" "-r" (haskell-cabal-find-dir))))

I feel like this could be the default value.

[tonyday567]

Had the same issue.

I also had to clear the .emacs.d/.lsp-session-v1 cache to remove prior incorrect root information.

[michaelpj]

Looking in lsp-mode, it seems that this issue comes up frequently. Their position seems to be:

• You should get an interactive choice of root, which gives you the option to pick where the right root is.
• As far as lsp-mode guessing the root goes, they delegate to projectile which apparently has hooks for configuring that.

So I think we shouldn't implement logic ourselves for this.

[Ptival]

Note: this was harder than I thought.

Essentially you need to modify lsp-haskell-process-wrapper-function before the Haskell mode starts, so that the command sent to the server is correct.

But the value of lsp-haskell--get-root is . until the Haskell mode has started.

My personal workaround is to have a hook to set lsp-haskell-process-wrapper-function before the Haskell mode starts, defining it as:

(lambda (argv)
  (append argv (list "-r" (haskell-cabal-find-dir default-directory))))

[Ptival]

Somehow things seem worse now. When I enter a Haskell buffer, lsp-haskell--hie-command seems to be called twice:

• once from the file that I opened (in which case my workaround works)
• then, a second time, from my project directory (which is bad: I no longer know which file is being processed)

[Ptival]

The following repository lets one reproduce the issue:

https://github.com/Ptival/mock-haskell-project-02/tree/7b3e875347bae083ec5975e1b32dfea9373c439d

If you try to open a Haskell file from this repository, HIE will be started in the root directory, rather than in the not-root directory, and thus will fail to figure out which GHC to use and crash.

[Ptival]

The main issue I see is that LSP runs commands from the projectile project root, but hie-wrapper needs to be ran either from the directory that contains the cabal file, or be given such directory with the -r option.

[alanz]

The behaviour in hie/ghcide/hls changed, it used to detect from the root directory given in the LSP protocol initialisation, but now expects to be in the given directory. Will update.

[FranklinChen]

I'm using hls 0.3.0 and there seems no "-r" option but the following worked for me:

(add-hook 'haskell-mode-hook
          (lambda ()
            (setq lsp-haskell-process-args-hie (list "-d" "-l" "/tmp/hie.log" "--cwd" (haskell-cabal-find-dir)))))